Laser processing apparatus

文档序号：1524876 发布日期：2020-02-11 浏览：28次中文

阅读说明：本技术 激光加工装置 (Laser processing apparatus ) 是由奥间惇治于 2018-07-23 设计创作，主要内容包括：激光加工装置具备：支撑部；激光光源；反射型空间光调制器；聚光光学系统；成像光学系统；镜；不经由聚光光学系统且与激光不同轴地对加工对象物照射第1测距用激光,并对其反射光进行受光,由此取得激光入射面的位移数据的第1传感器；及经由聚光光学系统且与激光同轴地对加工对象物照射第2测距用激光,并对其反射光进行受光,由此取得激光入射面的位移数据的第2传感器。从镜到达聚光光学系统的激光的光路设定成沿着第1方向。从反射型空间光调制器经由成像光学系统而到达镜的激光的光路设定成沿着与第1方向垂直的第2方向。第1传感器在与第1方向及第2方向垂直的第3方向上配置于聚光光学系统的一方侧。(The laser processing device is provided with: a support portion; a laser light source; a reflective spatial light modulator; a light-condensing optical system; an imaging optical system; a mirror; a 1 st sensor for obtaining displacement data of the laser light entrance surface by irradiating the 1 st distance measuring laser light to the object to be processed not via the condensing optical system but coaxially with the laser light and receiving the reflected light; and a 2 nd sensor for irradiating the object to be processed with the 2 nd distance measuring laser beam coaxially with the laser beam through the condensing optical system and receiving the reflected light to obtain displacement data of the laser beam incident surface. The optical path of the laser light reaching the condensing optical system from the mirror is set to be along the 1 st direction. An optical path of the laser light reaching the mirror from the reflective spatial light modulator via the imaging optical system is set to be along a 2 nd direction perpendicular to the 1 st direction. The 1 st sensor is disposed on one side of the condensing optical system in a 3 rd direction perpendicular to the 1 st direction and the 2 nd direction.)

1. A laser processing apparatus is characterized in that,

the disclosed device is provided with:

a support part for supporting the object to be processed;

a laser light source that emits laser light;

a reflective spatial light modulator that modulates and reflects the laser light;

a condensing optical system that condenses the laser beam on the object to be processed;

an imaging optical system constituting a bilateral telecentric optical system in which a reflection surface of the reflection-type spatial light modulator and an entrance pupil surface of the condensing optical system are in an imaging relationship;

a mirror that reflects the laser light having passed through the imaging optical system toward the condensing optical system;

a 1 st sensor that irradiates the object with a 1 st ranging laser beam not via the condensing optical system but coaxially with the laser beam, and receives reflected light of the 1 st ranging laser beam, thereby acquiring displacement data of a laser light incident surface of the object; and

a 2 nd sensor that irradiates the object with a 2 nd distance measuring laser beam through the condensing optical system and coaxially with the laser beam, and receives reflected light of the 2 nd distance measuring laser beam to acquire displacement data of the laser beam entrance surface,

an optical path of the laser light reaching the condensing optical system from the mirror is set to be along a 1 st direction,

an optical path of the laser light reaching the mirror from the reflective spatial light modulator via the imaging optical system is set to be along a 2 nd direction perpendicular to the 1 st direction,

the 1 st sensor is disposed on one side of the condensing optical system in a 3 rd direction perpendicular to the 1 st direction and the 2 nd direction.

2. Laser processing apparatus according to claim 1,

the disclosed device is provided with:

a frame body that supports at least the reflection type spatial light modulator, the condensing optical system, the imaging optical system, the mirror, and the 1 st sensor; and

a moving mechanism that moves the frame along the 1 st direction,

the condensing optical system and the 1 st sensor are mounted on one end side of the housing in the 2 nd direction,

the moving mechanism is attached to one side surface of the housing in the 3 rd direction.

3. Laser processing apparatus according to claim 1 or 2,

a plurality of the 1 st sensors are provided,

one of the plurality of the 1 st sensors is disposed on one side of the condensing optical system in the 3 rd direction,

another one of the plurality of 1 st sensors is disposed on the other side of the condensing optical system in the 3 rd direction.

4. A laser processing apparatus is characterized in that,

the disclosed device is provided with:

a laser light source that emits laser light;

a spatial light modulator that modulates the laser light;

a condensing optical system that condenses the laser beam on an object to be processed;

and a 2 nd sensor that irradiates the object with a 2 nd distance measuring laser beam through the condensing optical system and coaxially with the laser beam, and receives reflected light of the 2 nd distance measuring laser beam, thereby acquiring displacement data of the laser beam entrance surface.

5. The laser processing apparatus according to any one of claims 1 to 4,

the disclosed device is provided with:

a drive mechanism that moves the condensing optical system along an optical axis; and

a control unit that controls driving of the drive mechanism,

the control unit drives the drive mechanism so that the condensing optical system follows the laser light entrance surface, based on at least one of the displacement data acquired by the 1 st sensor and the displacement data acquired by the 2 nd sensor.

Technical Field

One aspect of the present invention relates to a laser processing apparatus.

Background

Patent document 1 describes a laser processing apparatus including: a holding mechanism for holding a workpiece; and a laser irradiation mechanism for irradiating the workpiece held by the holding mechanism with laser light. In this laser processing apparatus, each of the components disposed on the optical path of the laser light reaching the condenser lens from the laser oscillator is disposed in 1 frame. The frame is fixed to a wall portion erected on a base of the laser processing apparatus.

Disclosure of Invention

Technical problem to be solved by the invention

The laser processing apparatus as described above may include a sensor that obtains displacement data of the laser light incident surface of the object by irradiating the object with the distance measuring laser light and receiving reflected light of the distance measuring laser light. In such a case, it is desirable to obtain displacement data with high accuracy in accordance with various requirements. In addition, even in such a case, it is important to suppress the size increase of the apparatus.

An object of one aspect of the present invention is to provide a laser processing apparatus capable of accurately obtaining displacement data of a laser light entrance surface of an object to be processed in response to various requests while suppressing an increase in size of the apparatus.

Means for solving the problems

A laser processing apparatus according to an aspect of the present invention includes: a support part for supporting the object to be processed; a laser light source for emitting laser light; a reflective spatial light modulator that modulates and reflects the laser light; a condensing optical system for condensing the laser beam on the object to be processed; an imaging optical system of a bilateral telecentric optical system in an imaging relationship between a reflection surface of the reflection type spatial light modulator and an entrance pupil surface of the condensing optical system; a mirror that reflects the laser light having passed through the imaging optical system toward the condensing optical system; a 1 st sensor for irradiating the object to be processed with a 1 st distance measuring laser beam coaxially with the laser beam without passing through the condensing optical system, and receiving a reflected light of the 1 st distance measuring laser beam to obtain displacement data of a laser light incident surface of the object to be processed; and a 2 nd sensor that irradiates the object to be processed with the 2 nd distance measuring laser beam coaxially with the laser beam via the condensing optical system and receives reflected light of the 2 nd distance measuring laser beam to acquire displacement data of the laser beam entrance surface, wherein an optical path of the laser beam reaching the condensing optical system from the mirror is set to be along a 1 st direction, an optical path of the laser beam reaching the mirror from the reflective spatial light modulator via the imaging optical system is set to be along a 2 nd direction perpendicular to the 1 st direction, and the 1 st sensor is disposed on one side of the condensing optical system in a 3 rd direction perpendicular to the 1 st direction and the 2 nd direction.

The laser processing apparatus includes both a 1 st sensor for irradiating a 1 st distance measuring laser beam coaxially with a laser beam without passing through a condensing optical system and a 2 nd sensor for irradiating a 2 nd distance measuring laser beam coaxially with the laser beam through the condensing optical system as sensors for acquiring displacement data of a laser beam incident surface (hereinafter simply referred to as "laser beam incident surface") of an object to be processed. Since the 1 st sensor and the 2 nd sensor have different advantages, the respective advantages can be obtained by using them appropriately, and displacement data can be obtained with high accuracy in accordance with various requirements. The 1 st sensor is disposed on one side of a plane on which an optical path of the laser light reaching the condensing optical system from the reflective spatial light modulator is disposed. That is, the 1 st sensor can be efficiently arranged for each configuration arranged on the optical path of the laser light reaching the condensing optical system from the reflective spatial light modulator. Therefore, according to the laser processing apparatus according to the aspect of the present invention, displacement data of the laser light incident surface of the object to be processed can be accurately obtained in response to various requests while suppressing an increase in size of the apparatus.

The laser processing apparatus according to one aspect of the present invention may include a housing that supports at least a reflective spatial light modulator, a condensing optical system, an imaging optical system, a mirror, and a 1 st sensor; and a moving mechanism for moving the frame along the 1 st direction, wherein the condensing optical system and the 1 st sensor are mounted on one end side of the frame in the 2 nd direction, and the moving mechanism is mounted on one side surface of the frame in the 3 rd direction. According to this configuration, the reflective spatial light modulator, the condensing optical system, the imaging optical system, the mirror, and the 1 st sensor can be moved as one body while suppressing an increase in size of the apparatus.

The laser processing apparatus according to one aspect of the present invention may include a plurality of 1 st sensors, one of the plurality of 1 st sensors may be disposed on one side of the light condensing optical system in the 3 rd direction, and another of the plurality of 1 st sensors may be disposed on the other side of the light condensing optical system in the 3 rd direction. According to this configuration, the plurality of 1 st sensors can be efficiently arranged for each configuration arranged on the optical path of the laser light reaching the condensing optical system from the reflective spatial light modulator.

A laser processing apparatus according to an aspect of the present invention includes: a laser light source for emitting laser light; a spatial light modulator for modulating laser light; a condensing optical system for condensing the laser beam on the object to be processed; a 1 st sensor for irradiating the 1 st distance measuring laser beam to the object to be processed not via the condensing optical system but coaxially with the laser beam, and receiving reflected light of the 1 st distance measuring laser beam to obtain displacement data of the laser beam incident surface of the object to be processed; and a 2 nd sensor for irradiating the 2 nd distance measuring laser beam onto the object via the condensing optical system and coaxially with the laser beam, and receiving the reflected light of the 2 nd distance measuring laser beam to obtain displacement data of the laser beam entrance surface.

According to this laser processing apparatus, since the 1 st sensor and the 2 nd sensor have different advantages, the respective advantages can be obtained by appropriate use, and displacement data can be obtained with high accuracy in accordance with various requirements.

The laser processing apparatus according to one aspect of the present invention may include a driving mechanism that moves the condensing optical system along the optical axis, and a control unit that controls driving of the driving mechanism, wherein the control unit drives the driving mechanism such that the condensing optical system follows the laser light entrance surface based on at least one of the displacement data acquired by the 1 st sensor and the displacement data acquired by the 2 nd sensor. According to this configuration, for example, the condensing optical system can be moved so that the distance between the laser light entrance surface and the condensing point of the laser light is maintained constant by using at least one of the displacement data acquired by the 1 st sensor and the displacement data acquired by the 2 nd sensor.

ADVANTAGEOUS EFFECTS OF INVENTION

According to one aspect of the present invention, it is possible to provide a laser processing apparatus capable of obtaining displacement data of a laser light entrance surface of an object to be processed with high accuracy in response to various requests while suppressing an increase in size of the apparatus.

Drawings

Fig. 1 is a schematic configuration diagram of a laser processing apparatus for forming a modified region.

Fig. 2 is a plan view of an object to be processed to form a modified region.

Fig. 3 is a sectional view taken along line III-III of the object of fig. 2.

Fig. 4 is a plan view of the object after laser processing.

Fig. 5 is a cross-sectional view taken along line V-V of the object of fig. 4.

Fig. 6 is a sectional view taken along line VI-VI of the object of fig. 4.

Fig. 7 is a perspective view of a laser processing apparatus according to an embodiment.

Fig. 8 is a perspective view of a processing object mounted on a support base of the laser processing apparatus of fig. 7.

Fig. 9 is a cross-sectional view of the laser output section along the ZX plane of fig. 7.

Fig. 10 is a perspective view of a part of the laser output unit and the laser light condensing unit in the laser processing apparatus of fig. 7.

Fig. 11 is a cross-sectional view of the laser beam condensing portion along the XY plane of fig. 7.

Fig. 12 is a sectional view of the laser beam condensing portion taken along line XII-XII in fig. 11.

Fig. 13 is a cross-sectional view along XIII-XIII in fig. 12.

Fig. 14 is a diagram showing an optical arrangement relationship between the λ/2 wavelength plate unit and the polarizing plate unit in the laser output unit of fig. 9.

Fig. 15(a) is a view showing the polarization direction in the λ/2 wavelength plate unit of the laser output unit of fig. 9. Fig. 15(b) is a view showing the polarization direction in the polarizing plate unit of the laser output section of fig. 9.

Fig. 16 is a diagram showing the optical arrangement relationship of the reflective spatial light modulator, the 4f lens unit, and the condenser lens unit in the laser light condensing unit of fig. 11.

Fig. 17 is a diagram showing the movement of the conjugate point of the movement using the 4f lens unit of fig. 16.

Fig. 18 is a schematic diagram illustrating an on-axis distance measuring sensor and an off-axis distance measuring sensor in the laser processing apparatus of fig. 7.

Detailed Description

Hereinafter, embodiments will be described in detail with reference to the drawings. In the drawings, the same or corresponding portions are denoted by the same reference numerals, and redundant description thereof will be omitted.

In the laser processing apparatus according to the embodiment (described below), a modified region is formed in the object along the line to cut by condensing the laser light on the object. First, the formation of the modified region will be described with reference to fig. 1 to 6.

As shown in fig. 1, the laser processing apparatus 100 includes a laser light source 101 that pulse-oscillates the laser light L, a dichroic mirror 103 disposed so as to change the direction of the optical axis (optical path) of the laser light L by 90 °, and a condensing lens 105 for condensing the laser light L. The laser processing apparatus 100 includes a support table 107 for supporting the object 1 to be processed irradiated with the laser light L condensed by the condensing lens 105, a stage 111 for moving the support table 107, a laser light source control unit 102 for controlling the laser light source 101 to adjust the output of the laser light L, the pulse width, the pulse waveform, and the like, and a stage control unit 115 for controlling the movement of the stage 111.

In the laser processing apparatus 100, the laser beam L emitted from the laser light source 101 is changed in the direction of the optical axis by 90 ° by the dichroic mirror 103, and is condensed by the condensing lens 105 inside the object 1 placed on the support table 107. Simultaneously, the table 111 is moved, and the object 1 is moved relative to the laser light L along the line 5. Thereby, a modified region along the line 5 is formed in the object 1. Although the stage 111 is moved to relatively move the laser beam L here, the condensing lens 105 may be moved, or both may be moved.

As the object 1, a plate-like member (e.g., a substrate, a wafer, or the like) including a semiconductor substrate made of a semiconductor material, a piezoelectric substrate made of a piezoelectric material, or the like can be used. As shown in fig. 2, a line 5 to cut the object 1 is set in the object 1. The line 5 is a virtual line extending linearly. When forming a modified region inside the object 1, the laser light L is relatively moved along the line 5 to cut (i.e., in the direction of arrow a in fig. 2) while the converging point (converging position) P is aligned with the inside of the object 1, as shown in fig. 3. As a result, as shown in fig. 4, 5, and 6, the modified region 7 is formed in the object 1 along the line 5, and the modified region 7 formed along the line 5 becomes the starting point region for cutting 8.

The focal point P is a portion where the laser light L is focused. The line 5 is not limited to a straight line, and may be a curved line, a 3-dimensional line combining these lines, or a line designated by coordinates. The line 5 is not limited to a virtual line, and may be a line actually drawn on the front surface 3 of the object 1. The modified regions 7 may be formed continuously or intermittently. The modified regions 7 may be in the form of rows or dots, as long as the modified regions 7 are formed at least inside the object 1. Further, fractures may be formed from the modified region 7 as a starting point, and the fractures and the modified region 7 may be exposed to the outer surface (front surface 3, rear surface, or outer peripheral surface) of the object 1. The laser light entrance surface when forming the modified region 7 is not limited to the front surface 3 of the object 1, but may be the back surface of the object 1.

That is, when the modified region 7 is formed inside the object 1, the laser light L passes through the object 1 and is absorbed particularly in the vicinity of the converging point P located inside the object 1. Thereby, the modified region 7 is formed in the object 1 (i.e., internal absorption laser processing). In this case, since the laser light L is hardly absorbed on the surface 3 of the object 1, the surface 3 of the object 1 is not melted. On the other hand, when forming the modified region 7 on the front surface 3 of the object 1, the laser light L is particularly absorbed in the vicinity of the converging point P located on the front surface 3, and is melted and removed from the front surface 3 to form a removed portion such as a hole or a groove (surface absorption laser processing).

The modified region 7 is a region having a density, refractive index, mechanical strength, or other physical properties different from those of the surrounding region. The modified region 7 includes, for example, a melt-processed region (at least one of a region that is once melted and then solidified, a region in a molten state, and a region that is solidified again from the molten state), a crack region, an insulation breakdown region, a refractive index change region, and the like, and there are also regions in which these are mixed. The modified region 7 may be a region in which the density of the modified region 7 changes as compared with the density of the non-modified region in the material of the object 1, or a region in which lattice defects are formed. When the material of the object 1 is single crystal silicon, the modified region 7 may be referred to as a high dislocation density region.

The molten processed region, the refractive index changed region, the region where the density of the modified region 7 changes as compared with the density of the unmodified region, and the region where lattice defects are formed may further contain fractures (cracks, microcracks) inside these regions or in the interface between the modified region 7 and the unmodified region. The fractures contained may be formed over the entire modified region 7 or only in a part or in a plurality of parts. The object 1 includes a substrate made of a crystalline material having a crystalline structure. For example, the object 1 is made of gallium nitride (GaN), silicon (Si), silicon carbide (SiC), LiTaO ₃And sapphire (Al) ₂O ₃) At least any one of the above substrates. In other words, the object 1 includes, for example, a gallium nitride substrate, a silicon substrate, and a SiC groupPlate, LiTaO ₃A substrate, or a sapphire substrate. The crystalline material may be either anisotropic crystal or isotropic crystal. The object 1 may include a substrate made of an amorphous material having an amorphous structure (amorphous structure), for example, a glass substrate.

In the embodiment, the modified regions 7 can be formed by forming a plurality of modified spots (spots) (processing marks) along the lines 5. In this case, the plurality of modified light spots are collected to form the modified region 7. The modified spot is a modified portion formed by 1-pulse emission (shot) of the pulse laser (i.e., 1-pulse laser irradiation: laser emission). Examples of the modified spots include a crack spot, a fusion treatment spot, a refractive index change spot, and a spot in which at least 1 of them is mixed. The modified spots can be controlled in size and length of cracks generated, as appropriate, in consideration of required cutting accuracy, required flatness of cut surfaces, thickness, type, crystal orientation, and the like of the object 1. In the present embodiment, modified spots may be formed as the modified regions 7 along the lines 5.

Laser processing apparatus according to an embodiment

Next, a laser processing apparatus according to an embodiment will be described. In the following description, directions orthogonal to each other in a horizontal plane are referred to as an X-axis direction and a Y-axis direction, and a vertical direction is referred to as a Z-axis direction.

[ Overall Structure of laser processing apparatus ]

As shown in fig. 7, the laser processing apparatus 200 includes: a device frame 210; the 1 st moving mechanism 220; a support table (support portion) 230; and a 2 nd moving mechanism (moving mechanism) 240. Furthermore, the laser processing apparatus 200 includes: a laser output unit 300; a laser light-condensing section 400; and a control unit 500.

The 1 st moving mechanism 220 is mounted to the apparatus frame 210. The 1 st moving mechanism 220 includes: the 1 st track unit 221; the 2 nd track unit 222; and a movable base 223. The 1 st rail unit 221 is mounted to the device frame 210. The 1 st track unit 221 is provided with a pair of tracks 221a and 221b extending in the Y axis direction. The 2 nd track unit 222 is mounted to the pair of tracks 221a, 221b of the 1 st track unit 221 so as to be movable in the Y-axis direction. The 2 nd rail unit 222 is provided with a pair of rails 222a and 222b extending in the X-axis direction. The movable base 223 is mounted to the pair of rails 222a, 222b of the 2 nd rail unit 222 so as to be movable in the X-axis direction. The movable base 223 is rotatable about an axis parallel to the Z-axis direction.

The support table 230 is mounted on the movable base 223. The support table 230 supports the object 1. The object 1 is, for example, an object in which a plurality of functional elements (a light-receiving element such as a photodiode, a light-emitting element such as a laser diode, a circuit element formed as a circuit, or the like) are formed in a matrix on the front surface side of a substrate made of a semiconductor material such as silicon. When the object 1 is supported by the support table 230, for example, a surface 1a (a surface on the side of a plurality of functional elements) of the object 1 is attached to the film 12 stretched over the annular frame 11 as shown in fig. 8. The support table 230 supports the object 1 by holding the frame 11 by a jig and adsorbing the thin film 12 by a vacuum chuck. On the support table 230, the plurality of lines to cut 5a parallel to each other and the plurality of lines to cut 5b parallel to each other are set in a lattice shape so as to pass between the adjacent functional devices in the object 1.

As shown in fig. 7, the support table 230 moves in the Y-axis direction by operating the 2 nd track unit 222 at the 1 st moving mechanism 220. The support table 230 moves in the X-axis direction by operating the movable base 223 by the 1 st movement mechanism 220. Further, the support table 230 rotates about an axis parallel to the Z-axis direction as a center line by operating the movable base 223 by the 1 st movement mechanism 220. In this way, the support table 230 is attached to the apparatus frame 210 so as to be movable in the X-axis direction and the Y-axis direction and rotatable about an axis parallel to the Z-axis direction.

The laser output unit 300 is mounted on the apparatus frame 210. The laser beam condensing unit 400 is attached to the apparatus frame 210 via the 2 nd moving mechanism 240. The laser beam condensing unit 400 is moved in the Z-axis direction by the 2 nd movement mechanism 240. In this way, the laser beam condensing unit 400 is attached to the apparatus frame 210 so as to be movable in the Z-axis direction with respect to the laser beam output unit 300.

The control Unit 500 includes a CPU (Central Processing Unit), a ROM (Read only Memory), a RAM (Random Access Memory), and the like. The control unit 500 controls the operations of the respective units of the laser processing apparatus 200.

For example, in the laser processing apparatus 200, a modified region is formed inside the object 1 along the lines 5a and 5b (see fig. 8) as described below.

First, the object 1 is supported by the support table 230 so that the back surface 1b (see fig. 8) of the object 1 becomes a laser light entrance surface, and the lines 5a to cut of the object 1 are aligned in a direction parallel to the X-axis direction. Next, the 2 nd moving mechanism 240 moves the laser beam condensing unit 400 so that the condensing point of the laser beam L is located inside the object 1 at a position separated by a predetermined distance from the laser beam entrance surface of the object 1. Then, the converging point of the laser light L is relatively moved along each line 5a while maintaining a constant distance between the laser light entrance surface of the object 1 and the converging point of the laser light L. Thereby, a modified region is formed inside the object 1 along each line 5 a. The laser light entrance surface is not limited to the back surface 1b, and may be the front surface 1 a.

When the formation of the modified regions along the lines 5a is completed, the support table 230 is rotated by the 1 st moving mechanism 220 to align the lines 5b of the object 1 with the direction parallel to the X-axis direction. Next, the 2 nd moving mechanism 240 moves the laser beam condensing unit 400 so that the condensing point of the laser beam L is located inside the object 1 at a position separated by a predetermined distance from the laser beam entrance surface of the object 1. Then, the converging point of the laser light L is relatively moved along each line 5b while maintaining the distance between the laser light entrance surface of the object 1 and the converging point of the laser light L constant. Thereby, a modified region is formed inside the object 1 along each line 5 b.

In this way, in the laser processing apparatus 200, a direction parallel to the X-axis direction is a processing direction (scanning direction of the laser light L). Further, the relative movement of the converging point of the laser light L along each line 5a and the relative movement of the converging point of the laser light L along each line 5b are performed by moving the support table 230 in the X-axis direction by the 1 st moving mechanism 220. The relative movement of the converging point of the laser light L between the lines 5a and the relative movement of the converging point of the laser light L between the lines 5b are performed by moving the support table 230 in the Y-axis direction by the 1 st moving mechanism 220.

As shown in fig. 9, the laser output section 300 includes a mounting base 301, a cover 302, and a plurality of mirrors 303 and 304. The laser output unit 300 further includes: a laser oscillator (laser light source) 310; a shutter (shutter) 320; a λ/2 wavelength plate unit (output adjustment unit, polarization direction adjustment unit) 330; a polarizing plate unit (output adjustment unit, polarization direction adjustment unit) 340; a beam expander (laser parallelizing unit) 350; and a mirror unit 360.

The mounting base 301 supports a plurality of mirrors 303, 304, a laser oscillator 310, a shutter 320, a λ/2 wavelength plate unit 330, a polarizing plate unit 340, a beam expander 350, and a mirror unit 360. The plurality of mirrors 303, 304, the laser oscillator 310, the shutter 320, the λ/2 wavelength plate unit 330, the polarizing plate unit 340, the beam expander 350, and the mirror unit 360 are attached to the main surface 301a of the mounting base 301. The mounting base 301 is a plate-like member and is detachable from the apparatus frame 210 (see fig. 7). The laser output unit 300 is attached to the apparatus frame 210 via the attachment base 301. That is, the laser output unit 300 is detachable from the apparatus frame 210.

The cover 302 covers the plurality of mirrors 303 and 304, the laser oscillator 310, the shutter 320, the λ/2 wavelength plate unit 330, the polarizing plate unit 340, the beam expander 350, and the mirror unit 360 on the main surface 301a of the mounting base 301. The cover 302 is detachable from the mounting base 301.

The laser oscillator 310 pulse-oscillates the linearly polarized laser light L in the X-axis direction. The wavelength of the laser light L emitted from the laser oscillator 310 is included in any wavelength band of 500 to 550nm, 1000 to 1150nm, or 1300 to 1400 nm. The laser light L having a wavelength band of 500 to 550nm is suitable for internal absorption laser processing of a substrate made of, for example, sapphire. The laser light L of each wavelength band of 1000 to 1150nm and 1300 to 1400nm is suitable for internal absorption laser processing of a substrate made of, for example, silicon. The polarization direction of the laser light L emitted from the laser oscillator 310 is, for example, a direction parallel to the Y-axis direction. The laser beam L emitted from the laser oscillator 310 is reflected by the mirror 303 and enters the shutter 320 in the Y-axis direction.

In the laser oscillator 310, ON/OFF (ON/OFF) of the output of the laser light L is switched as described below. When the laser oscillator 310 is formed of a solid-state laser, the on/off of the output of the laser light L is switched at high speed by switching on/off of a Q switch (AOM (acousto-optic modulator), EOM (electro-optic modulator), or the like) provided in the resonator. When the laser oscillator 310 is formed of a fiber laser, the on/off of the output of the laser beam L is switched at high speed by switching the on/off of the output of a seed laser or a semiconductor laser that forms the laser beam of an amplifier (for excitation). When the laser oscillator 310 uses an external modulation element, the on/off of the output of the laser light L is switched at high speed by switching the on/off of an external modulation element (AOM, EOM, or the like) provided outside the resonator.

The shutter 320 opens and closes the optical path of the laser beam L by a mechanical mechanism. The on/off switching of the output of the laser light L from the laser output unit 300 is performed by the on/off switching of the output of the laser light L in the laser oscillator 310 as described above, but the provision of the shutter 320 can prevent the laser light L from being unintentionally emitted from the laser output unit 300, for example. The laser light L passing through the shutter 320 is reflected by the mirror 304 and sequentially enters the λ/2 wavelength plate unit 330 and the polarizing plate unit 340 along the X-axis direction.

The λ/2 wavelength plate unit 330 and the polarizing plate unit 340 function as an output adjustment unit that adjusts the output (light intensity) of the laser light L. The λ/2 wavelength plate unit 330 and the polarizing plate unit 340 function as a polarization direction adjustment unit that adjusts the polarization direction of the laser light L. As will be described in detail later, the laser light L passing through the λ/2 wavelength plate unit 330 and the polarizing plate unit 340 in this order enters the beam expander 350 along the X-axis direction.

The beam expander 350 adjusts the diameter of the laser light L and parallelizes the laser light L. The laser light L passing through the beam expander 350 is incident to the mirror unit 360 along the X-axis direction.

The mirror unit 360 has a support base 361 and a plurality of mirrors 362 and 363. The support base 361 supports a plurality of mirrors 362, 363. The support base 361 is attached to the mounting base 301 so as to be adjustable in position in the X-axis direction and the Y-axis direction. The mirror (1 st mirror) 362 reflects the laser light L passing through the beam expander 350 in the Y-axis direction. The mirror 362 is mounted to the support base 361 such that its reflecting surface can be angularly adjusted around an axis parallel to the Z axis, for example. The mirror (2 nd mirror) 363 reflects the laser light L reflected by the mirror 362 in the Z-axis direction. The mirror 363 is attached to the support base 361 so that its reflection surface can be angularly adjusted around an axis parallel to the X axis, for example, and so that its position can be adjusted along the Y axis direction. The laser light L reflected by the mirror 363 passes through the opening 361a formed in the support base 361 and enters the laser beam condensing unit 400 (see fig. 7) along the Z-axis direction. That is, the emission direction of the laser light L by the laser output unit 300 coincides with the movement direction of the laser beam condensing unit 400. As described above, each of the mirrors 362 and 363 has a mechanism for adjusting the angle of the reflecting surface. In the mirror unit 360, the position and angle of the optical axis of the laser light L emitted from the laser output unit 300 can be aligned with respect to the laser light condensing unit 400 by adjusting the position of the support base 361 with respect to the mounting base 301, the position of the mirror 363 with respect to the support base 361, and the angle of the reflecting surface of each of the mirrors 362 and 363. That is, the plurality of mirrors 362 and 363 are configured to adjust the optical axis of the laser light L emitted from the laser output unit 300.

As shown in fig. 10, the laser light condensing unit 400 includes a housing 401. The frame 401 has a rectangular parallelepiped shape with the Y-axis direction as the longitudinal direction. A 2 nd moving mechanism 240 (see fig. 11 and 13) is attached to one side surface 401e of the housing 401. The housing 401 is provided with a cylindrical light incident portion 401a so as to face the opening 361a of the mirror unit 360 in the Z-axis direction. The light incident unit 401a causes the laser light L emitted from the laser output unit 300 to be incident into the housing 401. The mirror unit 360 and the light entrance portion 401a are separated from each other by a distance that does not contact each other when the laser light condensing portion 400 is moved in the Z-axis direction by the 2 nd movement mechanism 240.

As shown in fig. 11 and 12, the laser beam condensing unit 400 includes a mirror 402 and a dichroic mirror 403. Further, the laser beam condensing unit 400 includes: a reflection type spatial light modulator (spatial light modulator) 410, a 4f lens unit 420, a condenser lens unit (condensing optical system) 430, a drive mechanism 440, and a pair of different-axis distance measuring sensors (1 st sensor) 450.

The mirror 402 is attached to the bottom surface 401b of the housing 401 so as to face the light incident portion 401a in the Z-axis direction. The mirror 402 reflects the laser light L incident into the housing 401 via the light incident portion 401a in a direction parallel to the XY plane. The laser light L collimated by the beam expander 350 of the laser output unit 300 enters the mirror 402 along the Z-axis direction. That is, the laser light L enters the mirror 402 as parallel light in the Z-axis direction. Therefore, even if the laser beam condensing unit 400 is moved in the Z-axis direction by the 2 nd movement mechanism 240, the state of the laser beam L incident on the mirror 402 in the Z-axis direction is maintained constant. The laser light L reflected by the mirror 402 is incident on the reflective spatial light modulator 410.

The reflective Spatial Light Modulator 410 is mounted on an end 401c of the housing 401 in the Y axis direction in a state where the reflection surface 410a faces the inside of the housing 401, the reflective Spatial Light Modulator 410 is, for example, a Spatial Light Modulator (SLM) of a reflective Liquid Crystal (LCOS), modulates the laser Light L and reflects the laser Light L in the Y axis direction, the laser Light L modulated by the reflective Spatial Light Modulator 410 and reflected enters the 4f lens unit 420 along the Y axis direction, an angle α formed by the optical axis of the laser Light L entering the reflective Spatial Light Modulator 410 and the optical axis of the laser Light L emitted from the reflective Spatial Light Modulator 410 is an acute angle (for example, 10 to 60 °) in a plane parallel to the XY plane, that is, the laser Light L is reflected at an acute angle along the reflection Spatial Light Modulator 410, and this is to suppress a decrease in diffraction efficiency in order to suppress an incident angle and a reflection angle of the laser Light L, and to sufficiently exert performance of the reflective Spatial Light Modulator 410, and the reflection surface 410 is, for example, a reflection layer of a substantially equal to several tens μm of the reflection surface, and thus, the reflection layer of the reflective Spatial Light is used in the reflective Spatial Light Modulator 410.

The 4f lens unit 420 has: a holder 421, a lens (imaging optical system) 422 on the reflective spatial light modulator 410 side, a lens (imaging optical system) 423 on the condenser lens unit 430 side, and a slit member 424. The holder 421 holds the pair of lenses 422 and 423 and the slit member 424. The holder 421 maintains a positional relationship between the pair of lenses 422 and 423 and the slit member 424 in a direction along the optical axis of the laser light L. The pair of lenses 422 and 423 constitute a bilateral telecentric optical system in which the reflection surface 410a of the reflective spatial light modulator 410 and the entrance pupil surface 430a of the condenser lens unit 430 are in an imaging relationship. Thereby, an image of the laser light L on the reflection surface 410a of the reflective spatial light modulator 410 (an image of the laser light L modulated by the reflective spatial light modulator 410) is transferred (imaged) onto the entrance pupil surface 430a of the condenser lens unit 430. Slit 424a is formed in slit member 424. The slit 424a is located between the lenses 422 and 423, that is, in the vicinity of the focal plane of the lenses 422. Unnecessary portions of the laser light L modulated and reflected by the reflective spatial light modulator 410 are blocked by the slit member 424. The laser light L passing through the 4f lens unit 420 enters the dichroic mirror 403 along the Y-axis direction.

The dichroic mirror 403 reflects most (e.g., 95 to 99.5%) of the laser beam L in the Z-axis direction and transmits a part (e.g., 0.5 to 5%) of the laser beam L in the Y-axis direction. Most of the laser light L is reflected at a right angle along the ZX plane at the dichroic mirror 403. The laser light L reflected by the dichroic mirror 403 enters the condenser lens unit 430 along the Z-axis direction.

The condenser lens unit 430 is attached to an end 401d (an end opposite to the end 401 c) of the housing 401 in the Y-axis direction via a drive mechanism 440. The condenser lens unit 430 has a holder 431 and a plurality of lenses 432. The holder 431 holds a plurality of lenses 432. The plurality of lenses 432 focus the laser light L on the object 1 (see fig. 7) supported by the support table 230. The driving mechanism 440 moves the condenser lens unit 430 in the Z-axis direction by the driving force of the piezoelectric element.

The pair of different-axis distance measuring sensors 450 is attached to the end portion 401d of the housing 401 so as to be positioned on both sides of the condenser lens unit 430 in the X-axis direction. Each of the different-axis distance measuring sensors 450 emits the 1 st distance measuring laser beam to the laser light entrance surface of the object 1 (see fig. 7) supported by the support table 230, and detects the distance measuring light reflected by the laser light entrance surface, thereby acquiring displacement data of the laser light entrance surface of the object 1. As the non-coaxial distance measuring sensor 450, a sensor of a triangular distance measuring method, a laser confocal method, a white confocal method, a spectral interference method, an astigmatism method, or the like can be used.

The laser beam condensing unit 400 includes a beam splitter 461, a pair of lenses 462 and 463, and an intensity distribution monitoring camera 464 for the laser beam L. The beam splitter 461 splits the laser light L transmitted through the dichroic mirror 403 into a reflected component and a transmitted component. The laser light L reflected by the beam splitter 461 enters the pair of lenses 462 and 463 and the camera 464 in this order along the Z-axis direction. The pair of lenses 462 and 463 constitute a bilateral telecentric optical system in which the entrance pupil surface 430a of the condenser lens unit 430 and the imaging surface of the camera 464 are in an imaging relationship. Thereby, an image of the laser light L on the entrance pupil surface 430a of the condenser lens unit 430 is transferred (imaged) on the imaging surface of the camera 464. As described above, the image of the laser light L on the entrance pupil surface 430a of the condenser lens unit 430 is the image of the laser light L modulated by the reflective spatial light modulator 410. Therefore, in the laser processing apparatus 200, the operation state of the reflective spatial light modulator 410 can be grasped by monitoring the imaging result obtained by the camera 464.

The laser beam condensing unit 400 includes a beam splitter 471, a lens 472, and a camera 473 for monitoring the optical axis position of the laser beam L. The beam splitter 471 splits the laser light L transmitted through the beam splitter 461 into a reflected component and a transmitted component. The laser light L reflected by the beam splitter 471 enters the lens 472 and the camera 473 in this order along the Z-axis direction. The lens 472 condenses the incident laser light L on the imaging surface of the camera 473. In the laser processing apparatus 200, the imaging results obtained by the camera 464 and the camera 473 are monitored, and the positional adjustment of the support base 361 with respect to the mounting base 301, the positional adjustment of the mirror 363 with respect to the support base 361, and the angular adjustment of the reflection surfaces of the mirrors 362 and 363 are performed in the mirror unit 360 (see fig. 9 and 10), so that the displacement of the optical axis of the laser light L incident on the condenser lens unit 430 (the positional displacement of the intensity distribution of the laser light with respect to the condenser lens unit 430 and the angular displacement of the optical axis of the laser light L with respect to the condenser lens unit 430) can be corrected.

The beam splitters 461 and 471 are disposed in the cylindrical body 404 extending from the end 401d of the housing 401 in the Y-axis direction. The pair of lenses 462 and 463 are disposed in the cylindrical body 405 erected on the cylindrical body 404 in the Z-axis direction, and the camera 464 is disposed at an end of the cylindrical body 405. The lens 472 is disposed in the cylinder 406 standing on the cylinder 404 in the Z-axis direction, and the camera 473 is disposed at the end of the cylinder 406. The cylinder 405 and the cylinder 406 are juxtaposed with each other in the Y-axis direction. The laser light L transmitted through the beam splitter 471 may be absorbed by a damper or the like provided at an end of the cylindrical body 404, or may be used for an appropriate purpose.

As shown in fig. 12 and 13, the laser beam condensing unit 400 includes: a visible light source 481, a plurality of lenses 482, a reticle (reticle)483, a mirror 484, a half mirror 485, a beam splitter 486, a lens 487, an observation camera 488, and a coaxial ranging sensor (No. 2 sensor) 460. The visible light source 481 emits visible light V in the Z-axis direction. The plurality of lenses 482 parallelizes the visible light V emitted from the visible light source 481. The reticle 483 gives a scale line to the visible light V. The mirror 484 reflects the visible light V collimated by the plurality of lenses 482 in the X-axis direction. The half mirror 485 divides the visible light V reflected by the mirror 484 into a reflective component and a transmissive component. The visible light V reflected by the half mirror 485 is transmitted through the beam splitter 486 and the dichroic mirror 403 in order along the Z-axis direction, and is irradiated to the object 1 (see fig. 7) supported by the support table 230 via the condenser lens unit 430.

The visible light V irradiated to the object 1 is reflected by the laser light entrance surface of the object 1, enters the dichroic mirror 403 via the condenser lens unit 430, and passes through the dichroic mirror 403 in the Z-axis direction. The beam splitter 486 splits the visible light V transmitted by the dichroic mirror 403 into a reflected component and a transmitted component. The beam splitter 486 reflects the 2 nd distance measuring laser light L2 described below and the reflected light L2R thereof. The visible light V transmitted through the beam splitter 486 passes through the half mirror 485 and enters the lens 487 and the observation camera 488 in this order along the Z-axis direction. The lens 487 condenses the incident visible light V on the imaging surface of the observation camera 488. In the laser processing apparatus 200, the state of the object 1 can be grasped by observing the imaging result obtained by the observation camera 488.

The mirror 484, the half mirror 485, and the beam splitter 486 are disposed in the holder 407 attached to the end portion 401d of the housing 401. The plurality of lenses 482 and the reticle 483 are disposed in the cylinder 408 erected on the holder 407 along the Z-axis direction, and the visible light source 481 is disposed at an end of the cylinder 408. The lens 487 is disposed in the cylinder 409 erected on the holder 407 in the Z-axis direction, and the observation camera 488 is disposed at an end of the cylinder 409. The cylinder 408 and the cylinder 409 are juxtaposed to each other in the X-axis direction. The visible light V transmitted through the half mirror 485 in the X-axis direction and the visible light V reflected in the X-axis direction by the beam splitter 486 may be absorbed by a damper or the like provided on a wall portion of the holder 407, respectively, or may be used in appropriate applications.

The coaxial ranging sensor 460 is mounted on the side of the holder 407. The coaxial distance measuring sensor 460 emits the 2 nd distance measuring laser light L2 to the laser light entrance surface of the object 1 (see fig. 7) supported by the support table 230, and detects the reflected light L2R of the 2 nd distance measuring laser light L2 reflected by the laser light entrance surface, thereby acquiring displacement data of the laser light entrance surface of the object 1. The 2 nd distance measuring laser light L2 emitted from the coaxial distance measuring sensor 460 is reflected by the beam splitter 486, guided to the condenser lens unit 430 through the dichroic mirror 403, and reflected by the laser light entrance surface in the vicinity of the focal point of the condenser lens unit 430. The reflected light L2R returns to the coaxial distance measuring sensor 460 on a path opposite to the 2 nd distance measuring laser beam L2. The coaxial distance measuring sensor 460 obtains displacement data of the object 1 by changing the state of the reflected light L2R according to the position of the laser light entrance surface with respect to the condenser lens unit 430. For example, as the coaxial distance measuring sensor 460, a sensor of an astigmatic method or the like can be used.

In the laser processing apparatus 200, replacement of the laser output unit 300 is assumed. This is because the wavelength of the laser light L suitable for processing differs depending on the specification of the object 1, the processing conditions, and the like. Therefore, a plurality of laser output units 300 having mutually different wavelengths of the laser light L to be emitted are prepared. Here, the laser output section 300 for emitting the laser beam L having a wavelength in a wavelength band of 500 to 550nm, the laser output section 300 for emitting the laser beam L having a wavelength in a wavelength band of 1000 to 1150nm, and the laser output section 300 for emitting the laser beam L having a wavelength in a wavelength band of 1300 to 1400nm are prepared.

On the other hand, in the laser processing apparatus 200, replacement of the laser beam condensing unit 400 is not assumed. This is because the laser beam condensing unit 400 corresponds to multiple wavelengths (corresponds to a plurality of bands which are not continuous with each other). Specifically, the mirror 402, the reflective spatial light modulator 410, the pair of lenses 422 and 423 of the 4f lens unit 420, the dichroic mirror 403, the lens 432 of the condenser lens unit 430, and the like correspond to multiple wavelengths. Here, the laser condensing portion 400 corresponds to the wavelength bands of 500 to 550nm, 1000 to 1150nm and 1300 to 1400 nm. This is achieved by designing each structure of the laser beam condensing unit 400 so as to satisfy desired optical performance, such as coating a predetermined dielectric multilayer film on each structure of the laser beam condensing unit 400. In the laser output section 300, the λ/2 wavelength plate unit 330 has a λ/2 wavelength plate, and the polarizing plate unit 340 has a polarizing plate. The lambda/2 wavelength plate and the polarizing plate are optical elements having high wavelength dependence. Therefore, the λ/2 wavelength plate unit 330 and the polarizing plate unit 340 are provided in the laser output section 300 as different structures for each wavelength band.

[ optical path and polarization direction of laser light in laser processing apparatus ]

In the laser processing apparatus 200, the polarization direction of the laser light L condensed on the object 1 supported by the support table 230 is parallel to the X-axis direction as shown in fig. 11, and coincides with the processing direction (scanning direction of the laser light L). Here, in the reflective spatial light modulator 410, the laser light L is reflected as P-polarized light. This is because, when liquid crystal is used in the light modulation layer of the reflective spatial light modulator 410, if the liquid crystal is oriented such that liquid crystal molecules are inclined in a plane parallel to a plane including the optical axis of the laser light L incident on and emitted from the reflective spatial light modulator 410, the laser light L is subjected to phase modulation while rotation of the polarization plane is suppressed (see, for example, japanese patent No. 3878758). On the other hand, in the dichroic mirror 403, the laser light L is reflected as S-polarized light. This is because the dichroic mirror 403 can be easily designed by reflecting the laser light L as S-polarized light rather than P-polarized light, for example, by reducing the number of layers of the dielectric multilayer film for associating the dichroic mirror 403 with multiple wavelengths.

Therefore, in the laser light collecting unit 400, the optical path from the mirror 402 to the dichroic mirror 403 via the reflective spatial light modulator 410 and the 4f lens unit 420 is set to be along the XY plane, and the optical path from the dichroic mirror 403 to the condenser lens unit 430 is set to be along the Z axis direction.

As shown in fig. 9, in the laser output section 300, the optical path of the laser light L is set along the X-axis direction or the Y-axis direction (a plane parallel to the main surface 301 a). Specifically, the optical path from the laser oscillator 310 to the mirror 303 and the optical path from the mirror 304 to the mirror unit 360 via the λ/2 wavelength plate unit 330, the polarizing plate unit 340, and the beam expander 350 are set along the X-axis direction, and the optical path from the mirror 303 to the mirror 304 via the shutter 320 and the optical path from the mirror 362 to the mirror 363 on the mirror unit 360 are set along the Y-axis direction.

Here, the laser light L traveling from the laser output unit 300 toward the laser light condensing unit 400 along the Z-axis direction is reflected by the mirror 402 in a direction parallel to the XY plane as shown in fig. 11, and enters the reflective spatial light modulator 410, and at this time, the optical axis of the laser light L entering the reflective spatial light modulator 410 and the optical axis of the laser light L emitted from the reflective spatial light modulator 410 form an acute angle α in the plane parallel to the XY plane, while the optical path of the laser light L is set along the X-axis direction or the Y-axis direction in the laser output unit 300 as described above.

Therefore, in the laser output unit 300, the λ/2 wavelength plate unit 330 and the polarizing plate unit 340 need to function not only as an output adjustment unit for adjusting the output of the laser light L but also as a polarization direction adjustment unit for adjusting the polarization direction of the laser light L.

[ lambda/2 wavelength plate unit and polarizing plate unit ]

As shown in fig. 14, the λ/2 wavelength plate unit 330 has a holder (1 st holder) 331, and a λ/2 wavelength plate 332. The holder 331 holds the λ/2 wavelength plate 332 so that the λ/2 wavelength plate 332 can rotate about an axis (1 st axis) XL parallel to the X-axis direction as a center line. The λ/2 wavelength plate 332 rotates the polarization direction by an angle 2 θ with respect to the axis XL as the center line and emits the laser light L when the polarization direction is inclined by the angle θ with respect to the optical axis (for example, fast axis) of the plate and the laser light L is incident (see fig. 15 a).

The polarizing plate unit 340 has a holder (2 nd holder) 341, a polarizing plate (polarizing member) 342, and an optical path correcting plate (optical path correcting member) 343. The holder 341 holds the polarizing plate 342 and the optical path correcting plate 343 such that the polarizing plate 342 and the optical path correcting plate 343 are integrally rotatable about an axis (2 nd axis) XL as a center line. The light incident surface and the light exit surface of the polarizer 342 are inclined at a predetermined angle (e.g., brewster angle). When the laser light L enters the polarizer 342, the P-polarized component of the laser light L that matches the polarization axis of the polarizer 342 is transmitted therethrough, and the S-polarized component of the laser light L is reflected or absorbed (see fig. 15 (b)). The light incident surface and the light emitting surface of the optical path correcting plate 343 are inclined toward the opposite side to the light incident surface and the light emitting surface of the polarizing plate 342. The optical path correcting plate 343 returns the optical axis of the laser beam L deviated from the axis XL by transmitting the polarizing plate 342 to the axis XL.

As described above, in the laser beam condensing unit 400, the optical axis of the laser beam L incident on the reflective spatial light modulator 410 and the optical axis of the laser beam L emitted from the reflective spatial light modulator 410 form an acute angle α (see fig. 11) in a plane parallel to the XY plane, while in the laser beam output unit 300, the optical path of the laser beam L is set to be along the X-axis direction or the Y-axis direction (see fig. 9).

Therefore, in the polarizing plate unit 340, the polarizing plate 342 and the optical path correcting plate 343 are integrally rotated about the axis XL, and as shown in fig. 15(b), the polarizing axis of the polarizing plate 342 is inclined at an angle α with respect to the direction parallel to the Y-axis direction, whereby the polarizing direction of the laser light L emitted from the polarizing plate unit 340 is inclined at an angle α with respect to the direction parallel to the Y-axis direction, and as a result, in the reflective spatial light modulator 410, the laser light L is reflected as P-polarized light, and in the dichroic mirror 403, the laser light L is reflected as S-polarized light, and the polarizing direction of the laser light L condensed on the object 1 to be processed supported by the support stage 230 is parallel to the X-axis direction.

As shown in fig. 15(b), the polarization direction of the laser beam L incident on the polarizing plate unit 340 is adjusted, and the light intensity of the laser beam L emitted from the polarizing plate unit 340 is adjusted. The adjustment of the polarization direction of the laser light L incident on the polarizing plate unit 340 is performed by rotating the λ/2 wavelength plate 332 about the axis XL as the center line in the λ/2 wavelength plate unit 330, and adjusting the angle of the optical axis of the λ/2 wavelength plate 332 with respect to the polarization direction (for example, the direction parallel to the Y-axis direction) of the laser light L incident on the λ/2 wavelength plate 332, as shown in fig. 15 (a).

As described above, in the laser output unit 300, the λ/2 wavelength plate unit 330 and the polarizing plate unit 340 function not only as an output adjustment unit (in the above-described example, an output attenuation unit) that adjusts the output of the laser light L but also as a polarization direction adjustment unit that adjusts the polarization direction of the laser light L.

[4f lens Unit ]

As described above, the pair of lenses 422 and 423 of the 4f lens unit 420 constitute a bilateral telecentric optical system in which the reflection surface 410a of the reflective spatial light modulator 410 and the entrance pupil surface 430a of the condenser lens unit 430 are in an imaging relationship. Specifically, as shown in fig. 16, the distance of the optical path between the lens 422 on the reflective spatial light modulator 410 side and the reflective surface 410a of the reflective spatial light modulator 410 becomes the 1 st focal point distance f1 of the lens 422, the distance of the optical path between the lens 423 on the condenser lens unit 430 side and the entrance pupil surface 430a of the condenser lens unit 430 becomes the 2 nd focal point distance f2 of the lens 423, and the distance of the optical path between the lens 422 and the lens 423 becomes the sum of the 1 st focal point distance f1 and the 2 nd focal point distance f2 (i.e., f1+ f 2). The optical path between the pair of lenses 422 and 423 in the optical path from the reflective spatial light modulator 410 to the condenser lens unit 430 is a straight line.

In the laser processing apparatus 200, from the viewpoint of increasing the effective diameter of the laser light L on the reflection surface 410a of the reflective spatial light modulator 410, the magnification M of the bilateral telecentric optical system satisfies 0.5< M <1 (reduction system). The larger the effective diameter of the laser light L on the reflection surface 410a of the reflective spatial light modulator 410 is, the more finely phase pattern the laser light L is modulated. From the viewpoint of suppressing the optical path length of the laser light L from the reflective spatial light modulator 410 to the condenser lens unit 430 from becoming long, M may be 0.6 ≦ M ≦ 0.95. Here, (magnification M of the bilateral telecentric optical system) — (size of the image on the entrance pupil surface 430a of the condenser lens unit 430)/(size of the object on the reflection surface 410a of the reflective spatial light modulator 410). In the case of the laser processing apparatus 200, the magnification M of the bilateral telecentric optical system, the 1 st focal length f1 of the lens 422, and the 2 nd focal length f2 of the lens 423 satisfy M ═ f2/f 1.

Furthermore, from the viewpoint of reducing the effective diameter of the laser light L on the reflection surface 410a of the reflection type spatial light modulator 410, the magnification M of the both-side telecentric optical system may satisfy 1< M <2 (expansion system). the smaller the effective diameter of the laser light L on the reflection surface 410a of the reflection type spatial light modulator 410, the smaller the magnification of the beam expander 350 (see fig. 9) may be, and in the plane parallel to the XY plane, the smaller the angle α (see fig. 11) formed by the optical axis of the laser light L incident on the reflection type spatial light modulator 410 and the optical axis of the laser light L emitted from the reflection type spatial light modulator 410 becomes, and from the viewpoint of suppressing the optical path length of the laser light L from the reflection type spatial light modulator 410 to the condenser lens unit 430 from being lengthened, M ≦ 1.05 ≦ 1.7 may be used.

In the 4f lens unit 420, since the magnification M of the bilateral telecentric optical system is not 1, when the pair of lenses 422 and 423 are moved along the optical axis as shown in fig. 17, the conjugate point on the condenser lens unit 430 side is moved. Specifically, when the pair of lenses 422 and 423 are moved along the optical axis toward the condenser lens unit 430 in the case of the magnification M <1 (reduction system), the conjugate point on the condenser lens unit 430 side moves toward the opposite side of the reflective spatial light modulator 410. On the other hand, when the magnification M >1 (magnification system) is used, if the pair of lenses 422 and 423 are moved toward the reflective spatial light modulator 410 along the optical axis, the conjugate point on the condenser lens unit 430 side is moved toward the opposite side of the reflective spatial light modulator 410. Thus, for example, when the mounting position of the condenser lens unit 430 is shifted, the conjugate point on the condenser lens unit 430 side is positioned on the entrance pupil surface 430a of the condenser lens unit 430. In the 4f lens unit 420, as shown in fig. 11, a plurality of long holes 421a extending in the Y axis direction are formed in the bottom wall of the holder 421, and the holder 421 is fixed to the bottom surface 401b of the housing 401 by bolt fixing through the long holes 421 a. Thus, the position adjustment of the pair of lenses 422 and 423 in the direction along the optical axis is performed by adjusting the fixed position of the holder 421 with respect to the bottom surface 401a of the housing 401 in the Y-axis direction.

[ coaxial distance measuring sensor and non-coaxial distance measuring sensor ]

As shown in fig. 18, the non-coaxial distance measuring sensor 450 irradiates the object 1 with the 1 st distance measuring laser light L1 coaxially with the laser light L without passing through the condenser lens unit 430, and receives the reflected light L1R of the 1 st distance measuring laser light L1, thereby acquiring displacement data of the laser light entrance surface. The non-coaxial ranging sensor 450 is provided with a pair (a plurality). The pair of different-axis distance measuring sensors 450 are disposed on one side and the other side of the condenser lens unit 430 in the X direction, respectively. The coaxial distance measuring sensor 460 irradiates the object with the 2 nd distance measuring laser light L2 coaxially with the laser light L through the condenser lens unit 430, and receives the reflected light L2R of the 2 nd distance measuring laser light L2, thereby acquiring displacement data of the laser light entrance surface. The acquired displacement data is transmitted to the control unit 500.

The displacement data is a signal related to the displacement, for example, an error signal. For example, the error signal is generated by the following equation based on the detection result of dividing and detecting the changing beam shape.

Error signal [ [ (I) _A+I _C)-(I _B+I _D)]/[(I _A+I _B+I _C+I _D)]

Wherein the content of the first and second substances,

I _A: a signal value outputted based on the light quantity of the 1 st light receiving surface among the 4 divided light receiving surfaces,

I _B: the light quantity based on the 2 nd light receiving surface of the 4 divided light receiving surfacesAnd the output signal value,

I _C: a signal value outputted based on the light quantity of the 3 rd light receiving surface among the 4 divided light receiving surfaces,

I _D: a signal value output based on the light quantity of the 4 th light-receiving surface out of the 4 divided light-receiving surfaces.

In the laser processing apparatus 200, as described above, the direction parallel to the X-axis direction is the processing direction (scanning direction of the laser light L). Therefore, when the converging point of the laser light L is relatively moved along the line to cut 5, the misalignment distance measuring sensor 450 of the pair of misalignment distance measuring sensors 450 that precedes the condenser lens unit 430 relatively can acquire displacement data of the laser light entrance surface of the object 1 along the line to cut 5.

The non-coaxial ranging sensor 450 has the following advantages. There are few design restrictions (wavelength, polarization, etc.). As described above, since the displacement data of the laser light entrance surface preceding the condenser lens unit 430 can be acquired, the shape of the laser light entrance surface (the shape of the object 1) can be grasped in advance. The distance measurement point is different from the control point, and displacement data can be acquired before the condenser lens unit 430. Even if there is a sharp displacement of the edge of the object 1 or the object 1, there is little hindrance in the follow-up operation (time-consuming control, vibration, etc.).

On the other hand, the coaxial ranging sensor 46 has the following advantages. The influence of disturbance (vibration, thermal expansion, etc.) can be eliminated. The influence of the positional deviation can be eliminated. Since the distance measurement point is the same as the control point, even when the support table 230 vibrates or is strained, the distance between the condenser lens unit 430 and the laser light entrance surface can be kept constant by the feedback control in consideration of this situation, and errors in the control result can be suppressed.

The control unit 500 drives the driving mechanism 440 so that the condenser lens unit 430 follows the laser light entrance surface based on at least one of the displacement data acquired by the different-axis distance measuring sensor 450 and the displacement data acquired by the coaxial distance measuring sensor 460 while scanning the laser light L along the line to cut 5. Thereby, based on the displacement data, the condenser lens unit 430 is moved in the Z-axis direction so that the distance between the laser light entrance surface of the object 1 and the converging point of the laser light L is maintained constant.

For example, the control unit 500 acquires an error signal as displacement data from the coaxial distance measuring sensor 460 while scanning the laser light L along the line 5 to cut, performs feedback control so that the acquired error signal maintains a target value, and causes the condenser lens unit 430 to move in the Z direction so as to follow the laser light entrance surface by the drive mechanism 440.

Alternatively, for example, the control unit 500 acquires an error signal as displacement data from the preceding different-axis distance measuring sensor 450 while scanning the laser light L along the line 5 to cut, performs a preceding read control (feedforward control) so that the acquired error signal maintains a target value, and causes the condenser lens unit 430 to move in the Z direction so as to follow the laser light entrance surface by the drive mechanism 440.

Alternatively, for example, the control unit 500 performs feedback control so that the signal based on both the error signal from the coaxial distance measuring sensor 460 and the error signal from the non-coaxial distance measuring sensor 450 maintains a target value while scanning the laser light L along the line 5 to cut, and causes the condenser lens unit 430 to move in the Z direction so as to follow the laser light entrance surface by the drive mechanism 440.

Alternatively, the control unit 500 may perform the following control based on at least one of the displacement data acquired by the different-axis distance measuring sensor 450 and the displacement data acquired by the coaxial distance measuring sensor 460. For example, the following at the position of the condenser lens unit 430 is checked using the displacement data acquired by the coaxial distance measuring sensor 460 while following the laser light entrance surface using the displacement data acquired by the preceding different-axis distance measuring sensor 450. Further, the displacement data acquired by the coaxial distance measuring sensor 460 may be used to detect the protrusion of at least one of the 1 st track unit 221, the 2 nd track unit 222, and the movable base 223 (see fig. 7) while following the laser light entrance surface using the displacement data acquired by the preceding different-axis distance measuring sensor 450. Further, the height position of the edge of the object 1 may be acquired by the preceding different-axis distance measuring sensor 450, and the height position when the optical axis of the condenser lens unit 430 enters the edge (when the optical axis of the coaxial distance measuring sensor 460 enters the edge) may be corrected based on the acquired height position. Further, the displacement data acquired by the preceding coaxial distance measuring sensor 460 may be used to perform feedback correction (feedforward control + feedback control) on the error of the following while following the laser light entrance surface using the displacement data acquired by the preceding non-coaxial distance measuring sensor 450. In order to expand options for processing a special wafer, an optimum one may be selected from the non-coaxial ranging sensor 450 and the coaxial ranging sensor 460 based on the type of the object 1.

[ Effect and Effect ]

As described above, the laser processing apparatus 200 includes both the misalignment distance measuring sensor 450 for irradiating the 1 st distance measuring laser light L1 coaxially with the laser light L without passing through the condenser lens unit 430 and the coaxial distance measuring sensor 460 for irradiating the 2 nd distance measuring laser light L2 coaxially with the laser light L through the condenser lens unit 430, as sensors for acquiring displacement data of the laser light entrance surface. Since the different-axis distance measuring sensor 450 and the coaxial distance measuring sensor 460 have different advantages, the displacement data can be accurately obtained according to various requirements by appropriately utilizing the advantages. More stable and highly accurate tracking operation can be realized. Further, the one different-axis distance measuring sensor 450 is disposed on one side of a plane (a plane parallel to the YZ plane) on which an optical path of the laser light L reaching the condenser lens unit 430 from the reflective spatial light modulator 410 is disposed. That is, one of the misalignment distance measuring sensors 450 can be efficiently arranged for each of the configurations arranged on the optical path of the laser light L reaching the condenser lens unit 430 from the reflective spatial light modulator 410.

Therefore, according to the laser processing apparatus 200 of the present invention, displacement data of the laser light entrance surface of the object 1 can be obtained with high accuracy in response to various requests while suppressing an increase in size of the apparatus. In the laser processing apparatus 200, the different-axis distance measuring sensor 450 and the coaxial distance measuring sensor 460 can be mounted at the same time, and by using the different-axis distance measuring sensor 450 and the coaxial distance measuring sensor 460 at the same time, a new function that cannot be achieved by a single body can be realized. A control combining the advantages of both can also be performed.

The laser processing apparatus 200 further includes: a housing 401 that supports at least the reflective spatial light modulator 410, the condenser lens unit 430, the pair of lenses 422 and 423, the dichroic mirror 403, and one of the misalignment distance measuring sensors 450; and a 2 nd moving mechanism 240 that moves the housing 401 along the 1 st direction (Z-axis direction). The condenser lens unit 430 and one of the misalignment distance measuring sensors 450 are attached to the end 401d of the housing 401 in the 2 nd direction (Y-axis direction). The 2 nd movement mechanism 240 is attached to one side surface 401e of the housing 401 in the 3 rd direction (X-axis direction). This makes it possible to move the reflective spatial light modulator 410, the condenser lens unit 430, the pair of lenses 422 and 423, the dichroic mirror 403, and one of the misalignment distance measuring sensors 450 as a single unit while suppressing an increase in size of the apparatus.

The laser processing apparatus 200 includes a plurality of the misalignment distance measuring sensors 450, one misalignment distance measuring sensor 450 is disposed on one side of the condenser lens unit 430 in the X direction, and the other misalignment distance measuring sensor 450 is disposed on the other side of the condenser lens unit 430 in the X direction. According to this configuration, the plurality of different-axis distance measuring sensors 450 can be efficiently arranged for each configuration arranged on the optical path of the laser light L reaching the condenser lens unit 430 from the reflective spatial light modulator 410.

The laser processing apparatus 200 includes: a drive mechanism 440 that moves the condenser lens unit 430 along the optical axis; and a control unit 500 for controlling the driving of the driving mechanism 440. The control unit 500 drives the driving mechanism 440 such that the condenser lens unit 430 follows the laser light entrance surface based on at least one of the displacement data acquired by the different-axis distance measuring sensor 450 and the displacement data acquired by the coaxial distance measuring sensor 460. With this configuration, for example, the condenser lens unit 430 can be moved so that the distance between the laser light entrance surface and the focal point of the laser light L is kept constant by using the displacement data of at least one of the different-axis distance measuring sensor 450 and the coaxial distance measuring sensor 460.

Further, the laser processing apparatus 200 can achieve the following operational effects.

In the laser processing apparatus 200, the mirror that reflects the laser light L having passed through the pair of lenses 422 and 423 toward the condenser lens unit 430 is the dichroic mirror 403. Thus, a part of the laser beam L transmitted through the dichroic mirror 403 can be used for various purposes.

In the laser processing apparatus 200, the dichroic mirror 403 reflects the laser light L as S-polarized light. Thus, by scanning the laser light L along the 3 rd direction (X-axis direction) with respect to the object 1, the scanning direction of the laser light L and the polarization direction of the laser light L can be aligned with each other. For example, when forming the modified region inside the object 1 along the line to cut, the modified region can be efficiently formed by aligning the scanning direction of the laser light L and the polarization direction of the laser light L with each other.

In the laser processing apparatus 200, the condenser lens unit 430 is attached to the end 401d of the housing 401 in the 2 nd direction (Y-axis direction) via the driving mechanism 440. Thus, for example, the condenser lens unit 430 can be moved so that the distance between the laser light entrance surface of the object 1 and the converging point of the laser light L is maintained constant.

In the laser processing apparatus 200, the reflective spatial light modulator 410 is attached to the end 401c of the housing 401 in the 2 nd direction (Y-axis direction). This allows each structure to be efficiently arranged with respect to the housing 401.

The laser processing apparatus 200 includes: a device frame 210; a support table 230 attached to the apparatus frame 210 and supporting the object 1; a laser output unit 300 attached to the apparatus frame 210; and a laser beam condensing unit 400 mounted on the apparatus frame 210 so as to be movable with respect to the laser beam output unit 300. The laser output section 300 includes a laser oscillator 310 that emits laser light L. The laser light condensing unit 400 includes: a reflective spatial light modulator 410 that modulates and reflects the laser light L; a condenser lens unit 430 for condensing the laser light L on the object 1; and a pair of lenses 422 and 423 constituting a bilateral telecentric optical system in which the reflection surface 410a of the reflection type spatial light modulator 410 and the entrance pupil surface 430a of the condenser lens unit 430 are in an imaging relationship.

In the laser processing apparatus 200, a laser beam condensing unit 400 having a reflective spatial light modulator 410, a condenser lens unit 430, and a pair of transmission paths 422 and 423 is movable relative to a laser beam output unit 300 having a laser oscillator 310. Therefore, for example, compared to the case where the entire components arranged on the optical path of the laser light L from the laser oscillator 310 to the condenser lens unit 430 are moved, the laser beam condensing unit 400 to be moved can be reduced in weight, and the 2 nd movement mechanism 240 for moving the laser beam condensing unit 400 can also be reduced in size. Further, since the reflective spatial light modulator 410, the condenser lens unit 430, and the pair of lenses 422 and 423 are integrally moved and maintain the positional relationship with each other, the image of the laser light L on the reflection surface 410a of the reflective spatial light modulator 410 can be transferred to the entrance pupil surface 430a of the condenser lens unit 430 with high accuracy. Therefore, according to the laser processing apparatus 200, the structure on the condenser lens unit 430 side can be moved with respect to the object 1 while suppressing an increase in size of the apparatus.

In the laser processing apparatus 200, the emission direction (Z-axis direction) of the laser light L from the laser output unit 300 coincides with the movement direction (Z-axis direction) of the laser light condensing unit 400. Thus, even if the laser beam condensing unit 400 moves relative to the laser output unit 300, the position of the laser beam L incident on the laser beam condensing unit 400 can be suppressed from changing.

In the laser processing apparatus 200, the laser output section 300 further includes a beam expander 350 for parallelizing the laser light L. Thus, even if the laser beam condensing unit 400 moves relative to the laser output unit 300, the diameter of the laser beam L incident on the laser beam condensing unit 400 can be suppressed from changing. Even if the laser light L is not perfectly parallel by the beam expander 350, the laser light L can be collimated in the reflective spatial light modulator 410 due to a slight divergence angle of the laser light L, for example.

In the laser processing apparatus 200, the laser beam condensing unit 400 further includes a housing 401 in which an optical path of the laser beam L reaching the condensing lens unit 430 from the reflective spatial light modulator 410 through the pair of lenses 422 and 423 is set, and the housing 401 is provided with a light incident unit 401a that causes the laser beam L emitted from the laser beam output unit 300 to enter the housing 401. Thus, the laser beam condensing unit 400 can be moved relative to the laser beam output unit 300 while maintaining the state of the optical path of the laser beam L from the reflective spatial light modulator 410 to the condenser lens unit 430 through the pair of lenses 422 and 423 at a constant level.

In the laser processing apparatus 200, the laser beam condensing unit 400 further includes: and a mirror 402 disposed in the housing 401 so as to face the light entrance portion 401a in the moving direction (Z-axis direction) of the laser light collection unit 400, the mirror 402 reflecting the laser light L incident into the housing 401 from the light entrance portion 401a toward the reflective spatial light modulator 410. This allows the laser light L incident on the laser beam condensing unit 400 from the laser beam output unit 300 to be incident on the reflective spatial light modulator 410 at a desired angle.

In the laser processing apparatus 200, the support table 230 is attached to the apparatus frame 210 so as to be movable along a plane (XY plane) perpendicular to the movement direction (Z axis direction) of the laser beam condensing unit 400. Thus, the converging point of the laser light L can be positioned at a desired position with respect to the object 1, and the laser light L can be scanned with respect to the object 1 in a direction parallel to a plane perpendicular to the moving direction of the laser light converging unit 400.

In the laser processing apparatus 200, the support table 230 is attached to the apparatus frame 210 via the 1 st moving mechanism 220, and the laser beam condensing unit 400 is attached to the apparatus frame 210 via the 2 nd moving mechanism 240. This makes it possible to reliably move the support stage 230 and the laser beam condensing unit 400.

The laser processing apparatus 200 further includes: a device frame 210; a support table 230 attached to the apparatus frame 210 and supporting the object 1; a laser output unit 300 that is attachable to and detachable from the apparatus frame 210; and a laser beam condensing unit 400 mounted on the device frame 210. The laser output section 300 includes a laser oscillator 310 that emits laser light L; and a lambda/2 wavelength plate unit 330 and a polarizing plate unit 340 for adjusting the output of the laser light L. The laser light condensing unit 400 includes: a reflective spatial light modulator 410 that modulates and reflects the laser light L; a condenser lens unit 430 for condensing the laser light L on the object 1; and a pair of lenses 422 and 423 constituting a bilateral telecentric optical system in which the reflection surface 410a of the reflection type spatial light modulator 410 and the entrance pupil surface 430a of the condenser lens unit 430 are in an imaging relationship.

In the laser processing apparatus 200, the laser output unit 300 including the laser oscillator 310, the λ/2 wavelength plate unit 330, and the polarizing plate unit 340 is detachable from the apparatus frame 210, separately from the laser condensing unit 400 including the reflective spatial light modulator 410, the condensing lens unit 430, and the pair of transmission paths 422 and 423. Therefore, when the wavelength of the laser light L suitable for processing differs depending on the specification of the object 1, the processing conditions, and the like, the laser oscillator 310 that emits the laser light L having a desired wavelength, the λ/2 wavelength plate unit 330 having wavelength dependency, and the polarizing plate unit 340 can be replaced in a lump. Therefore, according to the laser processing apparatus 200, a plurality of laser oscillators 310 having mutually different wavelengths of the laser light L can be used.

In the laser processing apparatus 200, the laser output unit 300 further includes: and a mounting base 301 that supports the laser oscillator 310, the λ/2 wavelength plate unit 330, and the polarizing plate unit 340 and is attachable to and detachable from the apparatus frame 210, wherein the laser output unit 300 is mounted to the apparatus frame 210 via the mounting base 301. This makes it easy to attach and detach the laser output unit 300 to and from the apparatus frame 210.

In the laser processing apparatus 200, the laser output unit 300 further includes mirrors 362 and 363 for adjusting the optical axis of the laser light L emitted from the laser output unit 300. Thus, for example, when the laser output unit 300 is attached to the apparatus frame 210, the position and angle of the optical axis of the laser light L incident on the laser beam condensing unit 400 can be adjusted.

In the laser processing apparatus 200, the λ/2 wavelength plate unit 330 and the polarizing plate unit 340 adjust the polarization direction of the laser light L. Thus, for example, when the laser output unit 300 is attached to the apparatus frame 210, the polarization direction of the laser light L incident on the laser beam condensing unit 400 can be adjusted, and the polarization direction of the laser light L emitted from the laser beam condensing unit 400 can be adjusted.

In the laser processing apparatus 200, the λ/2 wavelength plate unit 330 and the polarizing plate unit 340 include a λ/2 wavelength plate 332 and a polarizing plate 342. Thus, the wavelength-dependent λ/2 wavelength plate 332 and the polarizing plate 342 can be replaced together with the laser oscillator 310.

In the laser processing apparatus 200, the laser output section 300 further includes a beam expander 350 that adjusts the diameter of the laser beam L and parallelizes the laser beam L. Thus, for example, when the laser beam condensing unit 400 is moved relative to the laser output unit 300, the state of the laser beam L incident on the laser beam condensing unit 400 can be maintained constant.

In the laser processing apparatus 200, the reflective spatial light modulator 410, the condenser lens unit 430, and the pair of lenses 422 and 423 correspond to wavelength bands of 500 to 550nm, 1000 to 1150nm, and 1300 to 1400 nm. Thus, the laser output unit 300 that emits the laser light L of each wavelength band can be attached to the laser processing apparatus 200. The laser light L of a wavelength band of 500 to 550nm is suitable for internal absorption laser processing of a substrate made of, for example, sapphire. The laser light L of each wavelength band of 1000 to 1150nm and 1300 to 1400nm is suitable for internal absorption laser processing of a substrate made of, for example, silicon.

The laser processing apparatus 200 further includes: a support table 230 for supporting the object 1; a laser oscillator 310 that emits laser light L; a reflective spatial light modulator 410 that modulates and reflects the laser light L; a condenser lens unit 430 for condensing the laser light L on the object 1; and a pair of lenses 422 and 423 constituting a bilateral telecentric optical system in which the reflection surface 410a of the reflection type spatial light modulator 410 and the entrance pupil surface 430a of the condenser lens unit 430 are in an imaging relationship. Of the optical paths of the laser light L reaching the condenser lens unit 430 from the reflective spatial light modulator 410, at least the optical paths of the laser light L passing through the pair of lenses 422 and 423 (i.e., the lens 423 reaching the condenser lens unit 430 from the lens 422 on the reflective spatial light modulator 410 side) are aligned. The magnification M of the two-side telecentric optical system satisfies 0.5< M <1 or 1< M < 2. In the laser processing apparatus 200, the magnification M of the double-sided telecentric optical system, the 1 st focal length f1 of the lens 422, and the 2 nd focal length f2 of the lens 423 satisfy M ═ f2/f 1.

In the laser processing apparatus 200, the magnification M of the bilateral telecentric optical system is not 1. Thus, when the pair of lenses 422 and 423 moves along the optical axis, the conjugate point on the condenser lens unit 430 side also moves. Specifically, when the pair of lenses 422 and 423 are moved along the optical axis toward the condenser lens unit 430 in the case of the magnification M <1 (reduction system), the conjugate point on the condenser lens unit 430 side moves toward the opposite side of the reflective spatial light modulator 410. In addition, when the pair of lenses 422 and 423 is moved along the reflective spatial light modulator 410 side in the case where the magnification M >1 (magnification system), the conjugate point on the condenser lens unit 430 side moves to the opposite side of the reflective spatial light modulator 410. Therefore, for example, when the mounting position of the condenser lens unit 430 is shifted, the conjugate point on the condenser lens unit 430 side can be positioned on the entrance pupil surface 430a of the condenser lens unit 430. Further, since the optical path of the laser light L reaching the lens 423 on the condenser lens unit 430 side from at least the lens 422 on the reflective spatial light modulator 410 side is a straight line, the pair of lenses 422 and 423 can be easily moved along the optical axis. Therefore, according to the laser processing apparatus 200, the image of the laser light L on the reflection surface 410a of the reflective spatial light modulator 410 can be easily and accurately formed on the entrance pupil surface 430a of the condenser lens unit 430.

Further, by setting 0.5< M <1, the effective diameter of the laser light L on the reflection surface 410a of the reflection type spatial light modulator 410 can be increased, and the laser light L can be modulated with a high-definition phase pattern, on the other hand, by setting 1< M <2, the effective diameter of the laser light L on the reflection surface 410a of the reflection type spatial light modulator 410 can be reduced, and the angle α formed by the optical axis of the laser light L incident on the reflection type spatial light modulator 410 and the optical axis of the laser light L emitted from the reflection type spatial light modulator 410 can be reduced, it is important to suppress the incident angle and the reflection angle of the laser light L with respect to the reflection type spatial light modulator 410, and to sufficiently exert the performance of the reflection type spatial light modulator 410 while suppressing the decrease in diffraction efficiency.

In the laser processing apparatus 200, the magnification M may satisfy 0.6 ≦ M ≦ 0.95. This can more reliably suppress an increase in the optical path of the laser light L from the reflective spatial light modulator 410 to the condenser lens unit 430 while maintaining the effect achieved when the above-described 0.5< M < 1.

In the laser processing apparatus 200, the magnification M may satisfy 1.05 ≦ M ≦ 1.7. This can more reliably suppress an increase in the optical path of the laser light L from the reflective spatial light modulator 410 to the condenser lens unit 430 while maintaining the effect achieved when 1< M <2 as described above.

In the laser processing apparatus 200, the pair of lenses 422 and 423 are held by the holder 421, the holder 421 maintains a positional relationship between the pair of lenses 422 and 423 in a direction along the optical axis of the laser beam L to be constant, and the position adjustment of the pair of lenses 422 and 423 in the direction along the optical axis of the laser beam L (Y-axis direction) is performed by the position adjustment of the holder 421. This makes it possible to easily and reliably adjust the positions of the pair of lenses 422 and 423 (and thus adjust the positions of the conjugate points) while maintaining the positional relationship between the pair of lenses 422 and 423 constant.

The laser processing apparatus 200 further includes: a support table 230 for supporting the object 1; a laser oscillator 310 that emits laser light L; a reflective spatial light modulator 410 that modulates and reflects the laser light L; a condenser lens unit 430 for condensing the laser light L on the object 1; a pair of lenses 422 and 423 constituting a bilateral telecentric optical system in which the reflection surface 410a of the reflection type spatial light modulator 410 and the entrance pupil surface 430a of the condenser lens unit 430 are in an imaging relationship; and a dichroic mirror 403 that reflects the laser light L having passed through the pair of lenses 422 and 423 toward the condenser lens unit 430. The reflective spatial light modulator 410 reflects the laser light L at an acute angle along a predetermined plane (a plane parallel to the XY plane including a plane of an optical path of the laser light L incident and emitted from the reflective spatial light modulator 410). The optical path of the laser light L reaching the dichroic mirror 403 from the reflective spatial light modulator 410 through the pair of lenses 422 and 423 is set along the plane. The optical path of the laser light L reaching the condenser lens unit 430 from the dichroic mirror 403 is set along a direction (Z-axis direction) intersecting the plane.

In the laser processing apparatus 200, the optical path of the laser light L from the reflective spatial light modulator 410 to the dichroic mirror 403 via the pair of lenses 422 and 423 is set to be along a predetermined plane, and the optical path of the laser light L from the dichroic mirror 403 to the condenser lens unit 430 is set to be along a direction intersecting the plane. Thus, for example, the laser light L can be reflected as P-polarized light in the reflective spatial light modulator 410, and can be reflected as S-polarized light in the mirror. This is important in accurately forming an image of the laser light L on the reflection surface 410a of the reflective spatial light modulator 410 on the entrance pupil surface 430a of the condenser lens unit 430. The reflective spatial light modulator 410 reflects the laser light L at an acute angle. Suppressing the incident angle and the reflection angle of the laser light L with respect to the reflective spatial light modulator 410 is important in suppressing the decrease in diffraction efficiency and in sufficiently exhibiting the performance of the reflective spatial light modulator 410. As described above, according to the laser processing apparatus 200, the image of the laser light L on the reflection surface 410a of the reflective spatial light modulator 410 can be accurately formed on the entrance pupil surface 430a of the condenser lens unit 430.

In the laser processing apparatus 200, the optical path of the laser light L reaching the condenser lens unit 430 from the dichroic mirror 403 is set along the direction orthogonal to the above-described plane (plane parallel to the XY plane) as described above, and the dichroic mirror 403 reflects the laser light L at a right angle. This makes it possible to make the optical path of the laser light L reaching the condenser lens unit 430 from the reflective spatial light modulator 410 at a right angle.

In the laser processing apparatus 200, the reflective spatial light modulator 410 reflects the laser light L as P-polarized light, and the dichroic mirror 403 reflects the laser light L as S-polarized light. This enables the image of the laser light L on the reflection surface 410a of the reflective spatial light modulator 410 to be accurately formed on the entrance pupil surface 430a of the condenser lens unit 430.

The laser processing apparatus 200 further includes: a lambda/2 wavelength plate unit 330 and a polarizing plate unit 340, which are disposed on the optical path of the laser light L from the laser oscillator 310 to the reflective spatial light modulator 410 and adjust the polarization direction of the laser light L. Accordingly, since the polarization direction of the laser light L can be adjusted so that the reflective spatial light modulator 410 reflects the laser light L at an acute angle, the optical path of the laser light L reaching the reflective spatial light modulator 410 from the laser oscillator 310 can be made perpendicular.

The laser output unit 300 further includes: a laser oscillator 310 that emits laser light L; a lambda/2 wavelength plate unit 330 and a polarizing plate unit 340 for adjusting the output of the laser beam L emitted from the laser oscillator 310; a mirror unit 360 for emitting the laser light L having passed through the λ/2 wavelength plate unit 330 and the polarizing plate unit 340 to the outside; and a mounting base 301 having a main surface 301a on which the laser oscillator 310, the λ/2 wavelength plate unit 330, the polarizing plate unit 340, and the mirror unit 360 are arranged. The optical path of the laser light L reaching the mirror unit 360 from the laser oscillator 310 through the λ/2 wavelength plate unit 330 and the polarizing plate unit 340 is set to be along a plane parallel to the principal surface 301 a. The mirror unit 360 has mirrors 362 and 363 for adjusting the optical axis of the laser light L, and emits the laser light L to the outside along a direction (Z-axis direction) intersecting the plane.

In the laser output unit 300, the laser oscillator 310, the λ/2 wavelength plate unit 330, the polarizing plate unit 340, and the mirror unit 360 are disposed on the main surface 301a of the mounting base 301. Thus, the mounting base 301 is attached to and detached from the apparatus frame 210 of the laser processing apparatus 200, and the laser output unit 300 is easily attached to and detached from the laser processing apparatus 200. The optical path of the laser light L that reaches the mirror unit 360 from the laser oscillator 310 through the λ/2 wavelength plate unit 330 and the polarizing plate unit 340 is set along a plane parallel to the main surface 301a of the mounting base 301, and the mirror unit 360 emits the laser light L to the outside in a direction intersecting the plane. Accordingly, for example, when the emission direction of the laser light L is along the vertical direction, the laser output unit 300 is thinned, and therefore, the laser output unit 300 can be easily attached to and detached from the laser processing apparatus 200. The mirror unit 360 includes mirrors 362 and 363 for adjusting the optical axis of the laser beam L. Thus, when the laser output unit 300 is mounted on the apparatus frame 210 of the laser processing apparatus 200, the position and angle of the optical axis of the laser beam L incident on the laser beam condensing unit 400 can be adjusted. As described above, the laser output unit 300 is easily attached to and detached from the laser processing apparatus 200.

In the laser output section 300, the mirror unit 360 emits the laser light L to the outside along a direction orthogonal to a plane parallel to the main surface 301 a. This makes it possible to facilitate adjustment of the optical axis of the laser beam L in the mirror unit 360.

In the laser output unit 300, the λ/2 wavelength plate unit 330 and the polarizing plate unit 340 adjust the polarization direction of the laser light L emitted from the laser oscillator 310. Thus, when the laser output unit 300 is mounted on the apparatus frame 210 of the laser processing apparatus 200, the polarization direction of the laser light L incident on the laser beam condensing unit 400 can be adjusted, and further, the polarization direction of the laser light L emitted from the laser beam condensing unit 400 can be adjusted.

In the laser output section 300, the λ/2 wavelength plate unit 330 and the polarizing plate unit 340 have: a λ/2 wavelength plate 332 on which laser light L emitted from the laser oscillator 310 enters along an axis XL (an axis parallel to the main surface 301 a); a holder 331 for holding the λ/2 wavelength plate 332 so that the λ/2 wavelength plate 332 can rotate about the axis XL; a polarizing plate 342 into which the laser light L having passed through the λ/2 wavelength plate 332 enters along an axis XL; and a holder 341 for holding the polarizing plate 342 so that the polarizing plate 342 can rotate about the axis XL. This allows the output and polarization direction of the laser light L emitted from the laser oscillator 310 to be adjusted with a simple configuration. Further, by providing the laser output unit 300 with the λ/2 wavelength plate unit 330 and the polarizing plate unit 340, the λ/2 wavelength plate 332 and the polarizing plate 342 can be used according to the wavelength of the laser light L emitted from the laser oscillator 310.

The laser output unit 300 further includes: and a light path correcting plate 343 which is held by the holder 341 so as to be rotatable integrally with the polarizing plate 342 about the axis XL, and returns the optical axis of the laser beam L, which is deviated from the axis XL by passing through the polarizing plate 342, to the axis XL. This can correct the optical path shift of the laser light L caused by the transmission through the polarizer 342.

In the laser output unit 300, the axis about which the λ/2 wavelength plate 332 rotates and the axis about which the polarizing plate 342 rotates are the axis XL and coincide with each other. That is, the λ/2 wavelength plate 332 and the polarizing plate 342 are rotatable about the same axis XL as a center line. This can simplify and reduce the size of the laser output unit 300.

In the laser output unit 300, the mirror unit 360 includes a support base 361 and mirrors 362 and 363, the support base 361 is attached to the mounting base 301 so as to be adjustable in position, the mirror 362 is attached to the support base 361 so as to be adjustable in angle, the laser light L having passed through the λ/2 wavelength plate unit 330 and the polarizing plate unit 340 is reflected in a direction parallel to the main surface 301a, the mirror 363 is attached to the support base 361 so as to be adjustable in angle, and the laser light L reflected by the mirror 362 is reflected in a direction intersecting the main surface 301 a. Thus, when the laser output unit 300 is mounted on the apparatus frame 210 of the laser processing apparatus 200, the position and angle of the optical axis of the laser light L incident on the laser beam condensing unit 400 can be accurately adjusted. Further, by adjusting the position of the mounting base 301 by the support base 361, the mirrors 362 and 363 can be integrally and easily adjusted.

The laser output unit 300 further includes: and a beam expander 350 that is disposed on the optical path of the laser light L reaching the mirror unit 360 from the λ/2 wavelength plate unit 330 and the polarizing plate unit 340, and that collimates the laser light L while adjusting the diameter of the laser light L. Thus, even when the laser beam condensing unit 400 is moved relative to the laser output unit 300, the state of the laser beam L incident on the laser beam condensing unit 400 can be maintained constant.

The laser output unit 300 further includes: and a shutter 320 disposed on the optical path of the laser beam L from the laser oscillator 310 to the λ/2 wavelength plate unit 330 and the polarizing plate unit 340, for opening and closing the optical path of the laser beam L. Thus, the on/off switching of the output of the laser light L from the laser output unit 300 can be performed by the on/off switching of the output of the laser light L in the laser oscillator 310. Further, the shutter 320 can prevent the laser light L from being inadvertently emitted from the laser output unit 300, for example.

[ modified examples ]

The embodiments have been described above, but one embodiment of the present invention is not limited to the above embodiments.

A polarizing member other than the polarizing plate 342 may be provided in the polarizing plate unit 340. For example, a cubic polarizing member may be used instead of the polarizing plate 342 and the optical path correcting plate 343. The cube-like polarizing member is a member having a rectangular parallelepiped shape, and is a member in which side surfaces facing each other in the member are a light incident surface and a light emitting surface, and a layer having a function of a polarizing plate is provided between the side surfaces.

The axis about which the λ/2 wavelength plate 332 rotates and the axis about which the polarizing plate 342 rotates may not coincide with each other. In the above embodiment, the reflective spatial light modulator 410 is provided, but the spatial light modulator is not limited to the reflective type, and may be a transmissive type.

The laser output unit 300 has mirrors 362 and 363 for adjusting the optical axis of the laser beam L emitted from the laser output unit 300, but may have at least 1 mirror for adjusting the optical axis of the laser beam L emitted from the laser output unit 300.

The imaging optical system constituting the bilateral telecentric optical system in which the reflection surface 410a of the reflective spatial light modulator 410 and the entrance pupil surface 430a of the condenser lens unit 430 are in an imaging relationship is not limited to the pair of lenses 422 and 423, and may include a 1 st lens system (for example, a cemented lens, 3 or more lenses, etc.) on the reflective spatial light modulator 410 side and a 2 nd lens system (for example, a cemented lens, 3 or more lenses, etc.) on the condenser lens unit 430 side.

In the laser light collecting unit 400, the mirror that reflects the laser light L having passed through the pair of lenses 422 and 423 toward the condensing lens unit 430 is the dichroic mirror 403, but the mirror may be a total reflection mirror.

The condenser lens unit 430 and the pair of different-axis distance measuring sensors 450 are attached to the end 401d of the housing 401 in the Y-axis direction, but may be attached closer to the end 401d than the center position of the housing 401 in the Y-axis direction. The reflective spatial light modulator 410 is attached to the end 401c of the housing 401 in the Y-axis direction, but may be attached closer to the end 401c than the center position of the housing 401 in the Y-axis direction. The different-axis distance measuring sensor 450 may be disposed only on one side of the condenser lens unit 430 in the X-axis direction.

The laser condensing portion 400 may also be fixed to the device frame 210. In this case, the support table 230 is attached to the apparatus frame 210 so as to be movable not only in the X-axis direction and the Y-axis direction but also in the Z-axis direction.

The laser processing apparatus according to one embodiment of the present invention is not limited to forming the modified region inside the object 1, and may perform other laser processing such as ablation.

Description of the symbols

1 … object to be processed, 200 … laser processing apparatus, 230 … support base (support), 240 … 2 nd movement mechanism (movement mechanism), 310 … laser oscillator (laser light source), 401 … frame, 401c … end, 401d … end, 401e … side, 403 … dichroic mirror (mirror), 410 … reflection type spatial light modulator (spatial light modulator), 410a … reflection surface, 421 … holder, 422 … lens (imaging optical system), 423 … lens (imaging optical system), 430 … condenser lens unit (condensing optical system), 440 … drive mechanism, 450 … different axis distance measurement sensor (1 st sensor), 460 … coaxial distance measurement sensor (2 nd sensor), 500 … control unit, L … laser light, L1 … first distance measurement laser light, L1R … reflected light, L2 … second distance measurement laser light, and L2R … reflected light.

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