阅读说明：本技术 晶圆激光剥离装置及方法 (Wafer laser stripping device and method ) 是由 陈盟 罗帅 王刚 黎国柱 赵刚 兰珺琳 于 2021-09-07 设计创作，主要内容包括：本发明公开了一种晶圆激光剥离装置及方法,装置包括：用于提供激光束的光源机构、用于承载待剥离晶圆的承载机构以及挡光机构,挡光机构设置于光源机构与承载机构之间；挡光机构包括光掩模版,光掩模版上开设有与承载机构上所承载的待剥离晶圆芯片区域匹配的通光口,光源机构发出的激光束通过通光口落到待剥离晶圆芯片区域；在光源机构的激光束光路上设置光掩模版,光掩模版上开设于待剥离晶圆上芯片区域匹配的通光口,激光束通过通光口射到带剥离晶圆芯片上剥离芯片,待剥离晶圆芯片区域之外的部分被光掩模版挡住避免被激光束照射,有效避免晶圆上芯片区域之外的UV胶被激光束照射吸收激光而导致形貌异常,从而有效降低激光剥离带来的晶圆不良率。(The invention discloses a wafer laser stripping device and a method, wherein the device comprises: the device comprises a light source mechanism for providing laser beams, a bearing mechanism for bearing a wafer to be stripped and a light blocking mechanism, wherein the light blocking mechanism is arranged between the light source mechanism and the bearing mechanism; the light blocking mechanism comprises a photomask plate, a light through port matched with the wafer chip area to be stripped borne on the bearing mechanism is formed in the photomask plate, and a laser beam emitted by the light source mechanism falls to the wafer chip area to be stripped through the light through port; the laser beam light path of the light source mechanism is provided with a photomask, the photomask is provided with a light-passing port matched with a chip area on a wafer to be peeled, the laser beam is emitted to the chip to be peeled through the light-passing port, the part outside the chip area of the wafer to be peeled is blocked by the photomask to avoid being irradiated by the laser beam, the phenomenon that the appearance is abnormal due to the fact that the UV adhesive outside the chip area on the wafer is irradiated by the laser beam to absorb the laser is effectively avoided, and therefore the wafer reject ratio caused by laser peeling is effectively reduced.)

1. A wafer laser lift-off apparatus, comprising: the device comprises a light source mechanism for providing laser beams, a bearing mechanism for bearing a wafer to be stripped and a light blocking mechanism, wherein the light blocking mechanism is arranged between the light source mechanism and the bearing mechanism;

the light blocking mechanism comprises a photomask plate, a light through port matched with the wafer chip area to be stripped borne on the bearing mechanism is formed in the photomask plate, and laser beams emitted by the light source mechanism fall to the wafer chip area to be stripped through the light through port.

2. The wafer laser lift-off device of claim 1, wherein the light blocking mechanism further comprises a mounting portion for mounting the photo-mask plate, and the photo-mask plate is detachably mounted on the mounting portion.

3. The wafer laser lift-off device of claim 2, wherein the light blocking mechanism further comprises a driving member, and a driving end of the driving member is connected with the mounting portion and drives the mounting portion to rotate on the plane of the photomask plate by taking the driving end as a center.

4. The wafer laser lift off device of claim 3, wherein when there are two or more photomasks, the photomasks are equally spaced from the driving end of the driving member.

5. The wafer laser lift off device of claim 4, wherein the photomasks are equally spaced.

6. The wafer laser lift off device of claim 1, further comprising a box, wherein the light source mechanism, the light blocking mechanism and the carrying mechanism are disposed in the box.

7. The wafer laser lift off apparatus of claim 1, further comprising a beam shaping mechanism for energy-homogenizing the laser beam emitted by said light source mechanism.

8. The wafer laser lift off device of claim 7, wherein the beam shaping mechanism comprises a condenser lens, an objective lens, and a focusing lens; the laser beam emitted by the light source mechanism sequentially passes through the condenser lens, the objective lens and the focusing lens.

9. The wafer laser lift off device of claim 8, wherein the photomask is disposed between the objective lens and the focusing lens.

10. The wafer laser lift off device of claim 8 or 9, wherein the light source mechanism further comprises a mirror disposed between the objective lens and the focusing lens.

11. A wafer laser lift-off method using the wafer laser lift-off apparatus according to any one of claims 1 to 10, the method comprising:

installing a light blocking mechanism between the light source mechanism and the bearing mechanism and placing the wafer to be stripped on the bearing mechanism;

adjusting the position of the light blocking mechanism to enable the laser beam provided by the light source mechanism to pass through a photomask in the light blocking mechanism and then to be matched with the wafer chip area to be stripped;

and opening the light source mechanism to emit laser beams so that the laser beams pass through the photomask plate to obtain array focusing light spots which are arranged in line with the wafer chips to be stripped so as to carry out laser stripping on the wafer chips to be stripped.

Technical Field

The invention relates to the field of wafers, in particular to a laser stripping device and method for a wafer.

Background

The GaN-based sapphire substrate Micro-LED (hereinafter referred to as Micro-LED) is composed of a micron-sized semiconductor light emitting unit array, is a comprehensive technology of composite integration of a novel display technology and a light emitting diode technology, has the advantages of self-luminescence, high efficiency, low power consumption, high integration, high stability and all-weather work, and is considered to be one of the most promising next-generation novel display and light emitting devices. Micro-LEDs can be deployed in any existing display application from the smallest to the largest size due to their small size, high flexibility, easy disassembly and incorporation, etc., and in many cases will exert more unique effects than Liquid Crystal Displays (LCDs) and organic light emitting diode displays. In the future, Micro-LEDs will be expanded from flat panel displays to a variety of fields such as augmented reality/virtual reality/mixed reality (AR/VR/MR), spatial display, flexible transparent display, wearable/implantable photoelectric devices, optical communication/optical interconnection, medical detection, smart car lights, etc., and Micro-LEDs are likely to become a subversive and revolutionary next-generation mainstream display technology, bringing a new round of display technology to upgrade and upgrade.

Laser lift-off is an important process in Micro-LED display manufacturing, and is to transfer a Micro-LED chip onto a temporary carrier (temporary substrate) by using a laser lift-off technology after the Micro-LED chip is manufactured on an epitaxial layer/sapphire substrate. At present, UV glue is generally adopted as a bonding material of a Micro-LED chip to connect the chip and a temporary carrier plate (temporary substrate), and the UV glue has a close influence on a laser stripping effect. In addition, the properties and performance of the UV glue also strongly influence the ease of the next step after the chip is prepared by laser lift-off, i.e. the bulk transfer step. However, the wafer bonded using UV paste has some problems in process effect for the laser lift-off process.

Because the UV glue has high absorptivity to ultraviolet laser, and ultraviolet laser, even deep ultraviolet laser with wavelengths of 193nm, 248nm, 257nm and the like, is mostly adopted for laser stripping, in the laser stripping process, the laser can not only normally decompose the GaN serving as a luminescent semiconductor material, but also act on the UV glue, the material property of the UV glue is damaged, the wafer bonding effect is influenced, the wafer laser stripping effect is abnormal, and the adverse effects of chip damage and the like exist when the Micro-LED wafer product based on the UV glue serving as a bonding glue material is subjected to a laser stripping process. Therefore, the influence of laser on the action and material properties of the UV bonding glue material of the Micro-LED wafer product in the laser stripping process needs to be reduced as much as possible.

Therefore, in the prior art, an excimer laser is generally adopted as a light source to splice light spots to cover the whole breadth of a wafer so as to achieve laser stripping of the whole wafer, and then a sapphire substrate is stripped, or a semiconductor laser is adopted to cooperate with a high-speed vibrating mirror system and a focusing system to process, and the whole breadth is covered by scanning the whole breadth, so that GaN is decomposed, and the purpose of laser stripping is achieved. However, the two modes can not effectively avoid the problem that the quality and the appearance of the stripped chip are abnormal because the UV bonding glue in the etching channel of the Micro-LED wafer can not be effectively avoided.

Disclosure of Invention

The invention aims to: the wafer laser stripping device and method can effectively strip chips on an epitaxial layer/sapphire substrate in a wafer without damaging UV bonding glue in the wafer, so that the wafer defect rate caused by laser stripping is reduced.

The technical scheme of the invention is as follows: in a first aspect, the present invention provides a laser lift-off apparatus for a wafer, the apparatus comprising: the device comprises a light source mechanism for providing laser beams, a bearing mechanism for bearing a wafer to be stripped and a light blocking mechanism, wherein the light blocking mechanism is arranged between the light source mechanism and the bearing mechanism;

the light blocking mechanism comprises a photomask plate, a light through port matched with the wafer chip area to be stripped borne on the bearing mechanism is formed in the photomask plate, and laser beams emitted by the light source mechanism fall to the wafer chip area to be stripped through the light through port.

In a preferred embodiment, the light blocking mechanism further includes a mounting portion for mounting the photo-mask, and the photo-mask is detachably mounted on the mounting portion.

In a preferred embodiment, the light blocking mechanism further includes a driving member, and a driving end of the driving member is connected to the mounting portion and drives the mounting portion to rotate on the plane of the photomask with the driving end as a center.

In a preferred embodiment, when there are two or more photomasks, the photomasks are equally spaced from the driving end of the driving member.

In a preferred embodiment, the reticles are equally spaced.

In a preferred embodiment, the apparatus further includes a box, and the light source mechanism, the light blocking mechanism and the carrying mechanism are disposed in the box.

In a preferred embodiment, the apparatus further comprises a beam shaping mechanism for energy-homogenizing the laser beam emitted by the light source mechanism.

In a preferred embodiment, the beam shaping mechanism comprises a condenser lens, an objective lens and a focusing lens; the laser beam emitted by the light source mechanism sequentially passes through the condenser lens, the objective lens and the focusing lens.

In a preferred embodiment, the photomask is disposed between the objective lens and the focusing lens.

In a preferred embodiment, the light source mechanism further includes a mirror disposed between the objective lens and the focusing lens.

In a second aspect, the present invention further provides a wafer laser lift-off method, using the wafer laser lift-off apparatus according to any one of the first aspect, the method including:

installing a light blocking mechanism between the light source mechanism and the bearing mechanism and placing the wafer to be stripped on the bearing mechanism;

adjusting the position of the light blocking mechanism to enable the laser beam provided by the light source mechanism to pass through a photomask in the light blocking mechanism and then to be matched with the wafer chip area to be stripped;

and opening the light source mechanism to emit laser beams so that the laser beams pass through the photomask plate to obtain array focusing light spots which are arranged in line with the wafer chips to be stripped so as to carry out laser stripping on the wafer chips to be stripped.

Compared with the prior art, the invention has the advantages that: a wafer laser stripping device and method are provided, the device comprises: the device comprises a light source mechanism for providing laser beams, a bearing mechanism for bearing a wafer to be stripped and a light blocking mechanism, wherein the light blocking mechanism is arranged between the light source mechanism and the bearing mechanism; the light blocking mechanism comprises a photomask plate, a light through port matched with the wafer chip area to be stripped borne on the bearing mechanism is formed in the photomask plate, and a laser beam emitted by the light source mechanism falls to the wafer chip area to be stripped through the light through port; the laser beam light path of the light source mechanism is provided with a photomask, the photomask is provided with a light-passing port matched with a chip area on the wafer to be peeled, the laser beam is emitted to the chip to be peeled through the light-passing port, the part outside the chip area of the wafer to be peeled is blocked by the photomask to avoid being irradiated by the laser beam, and therefore quality and appearance abnormity caused by the fact that UV glue outside the chip area on the wafer is irradiated by the laser beam to absorb the laser is effectively avoided, and the wafer reject ratio caused by laser peeling is effectively reduced.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

FIG. 1 is a schematic structural diagram of a wafer to be peeled according to the present invention;

fig. 2 is a schematic diagram illustrating an optical path composition of a wafer laser lift-off apparatus according to an embodiment of the present invention;

fig. 3 is a first perspective view of a light blocking mechanism in the wafer laser lift-off apparatus according to the embodiment of the present invention;

fig. 4 is a second perspective view of a light blocking mechanism in the wafer laser lift-off apparatus according to the embodiment of the present invention;

wherein: 1. the wafer is to be stripped; 1a, an epitaxial layer; 1b, a chip, 1c and a UV bonding glue layer; 4. a light source; 5. a photomask; 51. a light-through port; 6. an installation part; 7. a drive member; 8. a condenser lens; 9. an objective lens; 10. a focusing lens; 11. a mirror.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As described in the background, an important step in the production of Micro-LED wafers is to use laser lift-off technology to peel off the chips from the epitaxial layer/sapphire substrate and then transfer the chips onto a temporary carrier (temporary substrate). Referring to fig. 1, a UV bonding glue layer is coated on the epitaxial layer/sapphire substrate, a plurality of chips are arranged on the UV bonding glue layer at intervals, and the UV bonding glue layer is exposed at the gaps between the chips, i.e. etching channels. In the current industry, one of the mainstream laser stripping schemes for Micro-LED wafers adopts an excimer laser, the laser wavelength is 248nm, and the pulse width is as follows: nanosecond ns is used as a light source, rectangular focusing light spots with the size of 2 x 2mm are used for splicing the light spots to cover the whole breadth of the wafer so as to achieve laser stripping of the whole wafer, and then the sapphire substrate is stripped; the UV bonding glue in the Micro-LED wafer etching channel cannot be avoided. Therefore, the quality and the shape of the peeled chip are often abnormal.

Another Micro-LED wafer Laser lift-off scheme employs a semiconductor Laser (DPSS), a Laser wavelength of 266nm, a pulse width: picosecond-level ps, the scheme generally adopts a circular focusing light spot with the diameter of 15-50 um, a high-speed galvanometer system and a focusing system are matched for processing, and the whole wafer is covered in a scanning mode, so that the aim of laser stripping is achieved by decomposing GaN. The scheme also adopts scanning on the whole breadth, and cannot effectively avoid the area with the UV adhesive material in the walkway, but because picosecond laser peak power is high, the overflow energy is less, and the damage to the adhesive material is small, the effect of the scheme is better than that of the excimer main flow scheme, but the quality and the appearance of the peeled chip caused by the damage of the laser to the UV bonding adhesive can not be effectively avoided.

In order to solve the problems, the invention provides a wafer laser stripping device, which adopts a photomask, can effectively and accurately shield UV bonding glue acting in a wafer etching channel (a channel between adjacent chips on a wafer), thereby effectively eliminating the damage and change of laser beams to the properties of a glue material; in addition, the designed through hole formed in the photomask is matched with the chip on the wafer, so that laser acting on the GaN buffer layer of the Micro-LED chip can be effectively transmitted, the GaN can be effectively decomposed to achieve the stripping purpose, and laser stripping of the Micro-LED wafer product based on the UV bonding adhesive can be finished at high quality.

Example 1: the present embodiment provides a wafer laser lift-off apparatus, as shown in fig. 1, the apparatus includes: a light source mechanism 4 for providing laser beams, a carrying mechanism (not shown) for carrying the wafer 1 to be stripped and a light blocking mechanism, wherein the light blocking mechanism is arranged between the light source mechanism and the carrying mechanism; the light blocking mechanism comprises a photomask plate 5, a light through opening 51 matched with the chip area of the wafer 1 to be stripped borne on the bearing mechanism is formed in the photomask plate 5, and laser beams emitted by the light source mechanism fall to the chip area of the wafer 1 to be stripped through the light through opening 51. Referring to fig. 1, the wafer 1 to be peeled includes an epitaxial layer 1a, a UV bonding adhesive layer 1c covering the surface of the epitaxial layer 1a, and chips 1b arranged on the UV bonding adhesive layer 1c at intervals, and a photomask 5 shields laser light emitted to etching tracks (tracks between adjacent chips 1 b) on the wafer 1 to be peeled, so as to prevent the laser light from being emitted to the exposed UV bonding adhesive layer 1c between the chips 1b to damage the UV bonding adhesive layer between the chips 1b, and only the laser light corresponding to the chips 1b on the wafer 1 to be peeled passes through a light-passing port 51 and is emitted to the chips 1b to peel the chips.

In a preferred embodiment, the light blocking mechanism further comprises a mounting portion 6 for mounting the photomask 5, and the photomask 5 is detachably mounted on the mounting portion 6. The photomask plate 5 is detachably arranged on the mounting part 6, so that the photomask plate 5 matched with wafers of different models and sizes can be conveniently detached and replaced. Illustratively, a bayonet is arranged on the mounting part 6, and the photomask 5 is embedded in the bayonet and the periphery of the photomask is clamped with the bayonet.

In a preferred embodiment, the light blocking mechanism further includes a driving member 7, and a driving end of the driving member 7 is connected to the mounting portion 6 and drives the mounting portion 6 to rotate around the driving end in a plane where the photomask 5 is located. Preferably, the projection of the driver 7 on the mounting part 6 in the direction perpendicular to the mounting part 6 is located between the photomasks 5, i.e. the projection of the driver 7 on the mounting part 6 when the light is irradiated perpendicular to the mounting part 6 has no overlapping area with the photomasks 5. Illustratively, the mounting portion 6 is a circular mounting plate, the driving member 7 is a rotating motor, and the driving end of the driving member, i.e. the rotating shaft of the rotating motor, penetrates through the circular mounting plate along the central axis of the circular mounting plate and is fixedly connected with the circular mounting plate.

In a preferred embodiment, when there are two or more photomasks 5, the photomasks 5 are equally spaced from the driving end of the driver 7. When wafers of different models need to be subjected to laser stripping, a corresponding number of photo-mask plates 5 need to be arranged, the distance between the photo-mask plates 5 and the driving end of the driving part 7 is equal, and after the model of the wafer to be stripped on the bearing mechanism is changed, the driving part 7 drives the mounting part 6 to rotate, so that the photo-mask plates 5 on the next station correspond to the wafer to be stripped on the bearing mechanism.

In a preferred embodiment, the reticles 5 are equally spaced, and each rotation of the drive 7 through a fixed angle changes the reticle 5 at the next station.

In a preferred embodiment, the apparatus further includes a box (not shown), the light source mechanism, the light blocking mechanism and the carrying mechanism are disposed in the box, and the light source mechanism, the light blocking mechanism and the carrying mechanism are fixed on the inner wall of the box through the mounting member, so as to facilitate installation and fixing of the position.

In a preferred embodiment, the device further comprises a beam shaping mechanism for homogenizing the energy of the laser beam emitted by the light source mechanism, and the beam shaping mechanism shapes the laser beam emitted by the light source 4 into a laser beam with a preset size and uniform capacity.

In a preferred embodiment, the beam shaping mechanism comprises a condenser lens 8, an objective lens 9 and a focusing lens 10; the laser beam emitted from the light source mechanism sequentially passes through a condenser lens 8, an objective lens 9, and a focusing lens 10. Specifically, the laser beam emitted from the light source 4 passes through the condenser lens 8, the objective lens 9, and the focusing lens 10 in this order and is perpendicular to the condenser lens 8, the objective lens 9, and the focusing lens 10.

In a preferred embodiment, the photomask 5 is disposed between the objective lens 9 and the focusing lens 10. The laser beam emitted by the light source 4 passes through the light-passing opening 51 of the photomask 5 perpendicularly.

In a preferred embodiment, the light source mechanism further comprises a mirror 11, the mirror 11 being arranged between the objective lens 9 and the focusing lens 10. Specifically, when the position of the wafer 1 to be peeled is not aligned with the light source 4 and the beam shaping mechanism, the mirror 11 is required to refract the laser beam to change the route of the laser beam emitted from the light source 4. The angle between the mirror 11 and the light source 4 is set according to the position of the wafer 1 to be peeled.

The embodiment provides a wafer laser lift-off device, the device includes: the device comprises a light source mechanism for providing laser beams, a bearing mechanism for bearing a wafer to be stripped and a light blocking mechanism, wherein the light blocking mechanism is arranged between the light source mechanism and the bearing mechanism; the light blocking mechanism comprises a photomask plate, a light through port matched with a wafer chip area to be stripped borne on the bearing mechanism is formed in the photomask plate, and a laser beam emitted by the light source mechanism falls to the wafer chip area to be stripped through the light through port; the laser beam light path of the light source mechanism is provided with a photomask, the photomask is provided with a light-passing port matched with a chip area on the wafer to be peeled, the laser beam is emitted to the chip to be peeled through the light-passing port, the part outside the chip area of the wafer to be peeled is blocked by the photomask to avoid being irradiated by the laser beam, and therefore quality and appearance abnormity caused by the fact that UV glue outside the chip area on the wafer is irradiated by the laser beam to absorb the laser is effectively avoided, and the wafer reject ratio caused by laser peeling is effectively reduced.

Example 2: the present embodiment provides a wafer laser lift-off method using the wafer laser lift-off device as in embodiment 1, including:

s1, installing a light blocking mechanism between the light source mechanism and the bearing mechanism and placing the wafer to be stripped on the bearing mechanism;

s2, adjusting the position of the light blocking mechanism to enable the laser beam provided by the light source mechanism to pass through a photomask in the light blocking mechanism and then to be matched with the wafer chip area to be stripped;

and S3, turning on the light source mechanism to emit laser beams so that the laser beams pass through the photomask to obtain array focusing light spots which are arranged in line with the wafer chips to be peeled so as to carry out laser peeling on the wafer chips to be peeled.

In a preferred embodiment, the method further comprises:

install the beam shaping mechanism that carries out energy homogenization to the laser beam that light source mechanism sent between light source mechanism and bearing mechanism, specifically include:

a condenser lens, an objective lens and a focusing lens are installed and a laser beam emitted from a light source mechanism sequentially passes through the condenser lens, the objective lens and the focusing lens, and a light blocking mechanism is installed between the objective lens and the focusing lens.

In a preferred embodiment, a reflector is installed between the objective lens and the focusing lens to change the optical path direction of the laser beam emitted by the light source mechanism so that the laser beam can be matched with the wafer to be stripped on the bearing mechanism.

More preferably, the mirror is mounted between the reticle and the focusing lens.

In a preferred embodiment, the method further comprises:

the positions of the light source mechanism, the condenser lens, the objective lens and the focusing lens are adjusted so that the center of the laser light is positioned on the same straight line with the centers of the condenser lens, the objective lens and the focusing lens.

In a preferred embodiment, the light blocking mechanism further comprises a mounting portion for mounting the photomask, the photomask being detachably mounted to the mounting portion, the method further comprising:

different types of photomasks are installed on the installation part.

More preferably, the light blocking mechanism further includes a driving member, a driving end of the driving member is connected to the mounting portion and drives the mounting portion to rotate on the plane where the photomask plate is located with the driving end as a center, and the method further includes:

and controlling the driving part to drive the mounting part to rotate so as to transform the photomask matched with the laser beam emitted by the light source mechanism.

It should be noted that: the wafer laser lift-off method provided in the above embodiment and the wafer laser lift-off device provided in embodiment 1 belong to the same concept, and the beneficial effects thereof are not described herein again.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

It should be understood that the above-mentioned embodiments are only illustrative of the technical concepts and features of the present invention, and are intended to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the scope of the present invention. All modifications made according to the spirit of the main technical scheme of the invention are covered in the protection scope of the invention.