阅读说明：本技术 浸润式光刻系统使用方法 (Method for using immersion lithography system ) 是由 李永尧 林韦志 林志建 于 2021-02-03 设计创作，主要内容包括：一种浸润式光刻系统的使用方法,包括：通过在平行于晶圆台的顶面的平面中移动晶圆台以校准浸润罩；移动晶圆台,以将浸润罩设置于晶圆台上的粒子捕获区域上；移动晶圆台,以在粒子捕获区域上定义二维选路轨迹以及在粒子捕获区域上定义了二维选路轨迹后,移动晶圆台以将浸润罩设置于晶圆台上的晶圆上。(A method of using an immersion lithography system, comprising: calibrating the immersion hood by moving the wafer table in a plane parallel to a top surface of the wafer table; moving the wafer table to place the immersion hood on the particle capture area on the wafer table; the wafer table is moved to define a two-dimensional routing trajectory on the particle capture area and to position the immersion hood on the wafer table after the two-dimensional routing trajectory is defined on the particle capture area.)

1. A method of using an immersion lithography system, the method comprising:

aligning an immersion hood by moving a wafer table in a plane parallel to a top surface of the wafer table;

moving the wafer stage to position the immersion hood over a particle capture area on the wafer stage;

moving the wafer stage to define a two-dimensional routing trajectory on the particle capture area; and

after the two-dimensional routing trajectory is defined on the particle capture area, the wafer stage is moved to position the immersion hood on a wafer on the wafer stage.

Technical Field

The present disclosure relates to a method for using an immersion lithography system.

Background

As technology nodes shrink, the proximity between elements in a semiconductor device increases. Photolithography systems are used to transfer patterns from a reticle to a wafer in order to define the locations of elements in a semiconductor device. The lithography system directs a beam to the reticle so that a pattern from the reticle is imparted to the beam. The beam is then directed to the wafer to transfer a pattern to the wafer, for example, using a photoresist material.

Immersion lithography is used to transfer a pattern from a reticle to a wafer to obtain a pattern with a line pitch of 90 nanometers (nm) or less. Immersion lithography uses an immersion fluid between a lens system and a wafer to reduce the amount of refractive index variation between the lens system and the wafer. Reducing the amount of refractive index variation helps to avoid refraction or bending of the light used to pattern the wafer. As a result, the accuracy of wafer patterning is improved, allowing patterns to be transferred to wafers with high elemental density.

Disclosure of Invention

According to an embodiment of the present disclosure, a method for using an immersion lithography system includes: calibrating the immersion hood by moving the wafer table in a plane parallel to a top surface of the wafer table; moving the wafer table to place the immersion hood on the particle capture area on the wafer table; the wafer table is moved to define a two-dimensional routing trajectory on the particle capture area and to position the immersion hood on the wafer table after the two-dimensional routing trajectory is defined on the particle capture area.

Drawings

The various aspects of the disclosure are best understood from the following detailed description when read in conjunction with the accompanying drawings. It is emphasized that, in accordance with the standard practice in the industry, various features are not drawn to scale and are used for illustrative purposes only. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

FIG. 1 is a cross-sectional view of an immersion lithography system according to some embodiments;

fig. 2A-2C are top views of a wafer table according to some embodiments;

3A-3F are top views of a routing path along a particle capture area according to some embodiments;

FIG. 4 is a schematic diagram of a system for controlling an immersion lithography system according to some embodiments;

FIG. 5 is a flow diagram of a method of using an immersion lithography system, in accordance with some embodiments;

FIG. 6 is a schematic diagram of a controller for controlling an immersion lithography system, according to some embodiments.

[ notation ] to show

100 immersion lithography system

110 wafer stage

112 wafer

115 top surface

120 soaking cover

125 lens system

132 immersion fluid input port

134 immersion liquid outlet port

136 hole (c)

138 hole (C)

140 impregnating solution

150 suction return line

152 suction return line

154 suction return line

156 drainage pipe

160: gap

200A wafer stage

200B wafer stage

200C wafer stage

210 sensor

220 sensor

230 sensor

240 particle trapping region

240' particle trap region

240' particle trap region

300A routing path

300B routing path

300C routing path

300D routing path

300E routing path

300F routing path

310A track

310B track

310C track

310D track

310E track

310F track

400 system

410 controller

420 infiltrating cover

430 motor of wafer stage

440 immersion fluid flow motor

500 method

510 operation

520 operation

530 operation

540 operation

550 operation

600 controller

602 processor

604 memory

606 computer program code

607 instruction

608 bus line

610I/O interface

612 network interface

614 network

Flow Rate 616 flow Rate

618 to pressure

620 stage position

622 mask position

X is the size

X' size

X is size

Y is size

Y size

Detailed Description

The following disclosure of embodiments provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. Of course, these examples are merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. Further, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

Furthermore, spatially relative terms such as "below … …," "below … …," "lower," "above … …," "upper," and the like may be used herein for ease of description to describe one element or feature's relationship to another element or feature as illustrated in the figures. Spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly as such.

Due to the use of the immersion liquid, the immersion lithography system can reliably transfer a pattern having a pitch density of 90 nanometers (nm) or less. Pitch density is the spacing between adjacent elements in a pattern. However, the immersion liquid also tends to transport particles present on the wafer table to above the wafer. Particles on the wafer increase the risk of incorrect patterning of parts of the wafer. Incorrectly patterned portions of the wafer are more likely to result in inoperable devices in the finished product.

The wafer patterning process involves relative motion between the lens system and the wafer. In some embodiments, the lens system may be movable relative to the wafer. In some embodiments, the wafer may be moved relative to the lens system. In some embodiments, the lens system and the wafer are both movable. Particles transported by the immersion fluid tend to accumulate on the wafer at the location where the lens system is first positioned to overlap the wafer, i.e., by moving the lens system over the wafer or moving the wafer under the lens system. The reason for the accumulation of particles at this location is due to surface property variations between the wafer table supporting the wafer and the patterned wafer surface. In some cases, the surface of the wafer table has hydrophilic properties. In some cases, the patterned wafer surface has hydrophobic properties. In some cases, the immersion liquid contains water. Due to the surface property change, the particles have a tendency to be transported from the immersion liquid to the wafer at the location where the lens system initially overlaps the wafer. The particles obstruct or scatter light from the immersion lithography system, which increases the risk of manufacturing errors in the portion of the wafer having the particles thereon.

To reduce or eliminate particles from being transported to the wafer, the current description includes a particle capture area on the wafer table. The lens system is caused to overlap the particle capture area and traverse the routing path along the particle capture area before overlapping the wafer. The particle catch region has surface properties similar to the wafer. As a result, the particles transported by the immersion fluid are collected on the particle capture area. By trapping particles on the particle trapping region, the number of particles subsequently transported to the wafer is reduced or completely avoided. The reduced number of particles on the wafer during wafer patterning improves the throughput of processes using an immersion lithography system that includes a particle trapping region, as compared to other approaches.

FIG. 1 is a cross-sectional view of an immersion lithography system 100 according to some embodiments. The immersion lithography system 100 includes a wafer table 110 for supporting a wafer 112. In some embodiments, the wafer table 110 may move in a plane parallel to the top surface 115 of the wafer table 110. The immersion hood 120 is above the wafer table 110. Immersion hood 120 includes a lens system 125 for directing a beam from a mask (not shown) toward wafer 112 for patterning the wafer. The immersion hood 120 further includes an immersion fluid inlet port 132 for receiving an immersion fluid 140. The immersion hood 120 further includes an immersion fluid output port 134 for outputting an immersion fluid 140. The immersion hood 120 further includes apertures 136 and 138 for also outputting an immersion fluid 140. The ends of holes 136 and 138 are shown cut-off for simplicity. One of ordinary skill in the art will recognize that the apertures 136 and 138 are used to deliver the immersion fluid 140 out of the immersion hood 120. The wafer table 110 further includes draw back lines 150, 152, and 154 for draining immersion fluid on the top surface 115 of the wafer table 110. The drain 156 allows the drain lines 150, 152 and 154 to dispense the immersion fluid 140. An immersion fluid 140 is disposed between the lens system 125 and the wafer 112 to improve the accuracy of patterning the wafer 112. A gap 160 exists between the bottom most surface of the immersion hood 120 and the top surface of the wafer 112 or the top surface 115 of the wafer table 110. The immersion fluid 140 is within the gap 160.

The wafer table 110 supports the wafer 112 during the patterning process. In some embodiments, the wafer table 110 uses a vacuum chuck (not shown) to hold the wafer 112 in place. In some embodiments, the wafer table 110 is attached to a motor to adjust the position of the wafer table 110 relative to the immersion hood 120. In some embodiments, the motor comprises a stepper motor, a rack and pinion motor, a piezoelectric motor, a servo motor, or other suitable motor. In some embodiments, the wafer table 110 is configured to translate in a plane parallel to the top surface 115. In some embodiments, the wafer table 110 is configured to rotate about an axis perpendicular to the top surface 115. In some embodiments, the wafer table 110 is configured to rotate about an axis parallel to the top surface 115. One of ordinary skill in the art will recognize that combinations of these motions are within the scope of the present disclosure. In some embodiments, the speed of moving the wafer table 110 is greater than 0.001 millimeters per second (mm/s). In some embodiments, the speed of moving the wafer table 110 is in the range of about 0.001mm/s to about 1 mm/s. In some cases, if the wafer table 110 is moved too fast, there is an increased risk of particles being pushed onto the wafer 112 due to splashing of the immersion fluid 140. In some cases, if the speed of moving the wafer table 110 is too slow, the risk of particles being trapped by the particle trapping region (described below) increases. The particle capture zone is described in detail below. The particle catch region is a region of the top surface 115 that has different surface properties than other portions of the top surface 115.

A portion of the wafer table 110 for supporting the wafer 112 is recessed relative to the top surface 115 such that the top surface of the wafer 112 is substantially coplanar with the top surface 115. The offset (if any) between the top surface 115 and the top surface of the wafer 112 is a result of multiple layers on the wafer. For example, during formation of elements from substrates near the wafer 112, the total thickness of the wafer 112 is less than during formation of elements from substrates away from the wafer 112.

In some embodiments, the sensor (see fig. 2A-2C) is in the top surface 115. In some embodiments, the top surface 115 includes a mirror portion for reflecting light from the lens system 125. Portions of the top surface 115 have hydrophilic properties that allow the immersion fluid 140 to spread over the top surface 115.

The wafer 112 is supported by the wafer table 110. The wafer 112 is patterned by a beam emitted from the immersion fluid 140 by the lens system 125 and then incident on the wafer 112. This beam changes the chemistry of the uppermost layer of the wafer 112. In some embodiments, the uppermost layer of the wafer 112 comprises photoresist material. In some embodiments, the uppermost layer of the wafer 112 comprises silicon. In some embodiments, a robot arm (not shown) is used to place the wafer 112 on the wafer table 110 and/or remove it from the wafer table 110.

The immersion hood 120 is configured to introduce an immersion fluid 140 into a gap 160 between the immersion hood 120 and the wafer table 110 and emit a beam from the lens system 125 to pattern the wafer 112. In some embodiments, the immersion hood 120 is stationary. In some embodiments, the immersion hood is capable of translational movement in a plane parallel to the top surface 115. In some embodiments, a motor is used to translate the immersion hood 120. In some embodiments, the motor comprises a stepper motor, a rack and pinion motor, a piezoelectric motor, a servo motor, or other suitable motor. In some embodiments, the motor used to move the immersion hood 120 is the same type of motor used to move the wafer table 110. In some embodiments, the motor used to move the immersion hood 120 is a different type of motor than the motor used to move the wafer table 110.

Lens system 125 is used to control the propagation of the light beam from the light source (not shown) to the mask and then to wafer 112. In some embodiments, the light source is configured to emit a light beam, such as an Ultraviolet (UV) or Extreme Ultraviolet (EUV) light source. In some embodiments, the light source comprises a mercury lamp with a wavelength of 436nm (G-line) or 365nm (I-line), a Krypton Fluoride (Krypton Fluoride, KrF) excimer laser with a wavelength of 248nm, an Argon Fluoride (ArF) excimer laser with a wavelength of 193nm, a Fluoride (Fluoride, F2) excimer laser with a wavelength of 157nm, or other light source with a desired wavelength (e.g., below about 100 nm). In some embodiments, the lens system 125 is free of mirrors. In some embodiments, the lens system 125 is a catadioptric system. In some embodiments, the lens system 125 is replaced by a reflective system.

The immersion fluid input port 132 is configured to receive the immersion fluid 140 from a supply source (not shown) and provide the immersion fluid 140 to the gap 160. The immersion fluid input port 132 is connected to a controllable pump (not shown) to control the flow rate and pressure of the immersion fluid 140 through the immersion hood 120. In some embodiments, the flow rate of the immersion fluid 140 through the immersion fluid input port 132 is in the range of about 1 liter per minute (L/min) to about 4L/min. In some cases, if the flow rate of the immersion fluid 140 is too low, the immersion fluid 140 may not be able to move particles from the wafer table 110 to the particle capture area. In some cases, if the flow rate of the immersion fluid 140 is too high, the immersion fluid 140 may cause an increased risk of particles being washed onto the wafer 112. In some embodiments, the pressure of the immersion fluid 140 passing through the immersion fluid input port 132 is less than or equal to 70 kilopascals (kPa). In some embodiments, the pressure of the immersion fluid 140 passing through the immersion fluid input port 132 is in the range of about 10kPa to about 70 kPa. In some cases, if the pressure of the immersion fluid 140 is too high, there is an increased risk of damaging the wafer 112 during the wafer patterning process. In some cases, if the pressure of the immersion fluid 140 is too low, the immersion fluid 140 may not move particles from the wafer table 110 to the particle capture zone.

The immersion fluid outlet port 134 is configured to allow the immersion fluid 140 to flow out of the immersion hood 120. In some cases, the immersion fluid 140 exiting the immersion fluid outlet port 134 is collected in a reservoir. In some embodiments, the immersion fluid 140 exiting the immersion fluid output port 134 is recovered and reintroduced into the immersion hood 120 through the immersion fluid input port 132. In some embodiments, the immersion fluid 140 exiting the immersion fluid output port 132 is filtered or otherwise treated prior to recovery.

The apertures 136 and 138 are similar to the immersion fluid outlet port 134, but include openings on the bottom-most surface of the immersion hood 120. In some cases, the immersion fluid 140 exiting at least one of the holes 136 or 138 is collected in a reservoir. In some embodiments, the immersion fluid 140 exiting either the aperture 136 or the hole 138 is recovered and reintroduced into the immersion hood 120 through the immersion fluid input port 132. In some embodiments, the immersion fluid 140 exiting either of the holes 136 or 138 is filtered or otherwise treated prior to recovery. In some embodiments, at least one of the apertures 136 or 138 is fluidly connected to the immersion fluid output port 134.

The immersion fluid 140 is used to reduce the refractive index difference between the lens system 125 and air. A light beam is refracted, i.e. bent and/or reflected, when it moves from one medium to another medium with different refractive indices. The refraction of the beam reduces the accuracy of the positioning of the beam on the wafer 112. The inclusion of the immersion fluid 140 reduces the amount of refraction and thus increases the accuracy of the positioning of the beam exiting the lens system 125 on the wafer 112. In some embodiments, the immersion fluid 140 has a refractive index of 1.44 or greater at a wavelength of 193 nm. In some embodiments, the immersion fluid 140 includes water. In some embodiments, the immersion fluid 140 includes deionized water (DIW). In some embodiments, the immersion fluid 140 includes a water-based solution that includes additives, such as acids, salts, or polymers. In some embodiments, the immersion fluid 140 includes a gas.

The wafer table 110 includes drawback lines 150, 152, and 154 for removing portions of the immersion fluid 140 in the gap 160. The suck back line 150 is on a first side of the wafer 112. The pull back line 152 is on a second side of the wafer 112 opposite the first side. The suck back line 154 connects the suck back lines 150 and 152 under the wafer 112. The suction lines 150, 152 and 154 are connected to a drain 156 for removing the immersion fluid 140 from the suction lines 150, 152 and 154. In some cases, the immersion fluid 140 leaving the drain 156 is collected in a reservoir. In some embodiments, the immersion fluid 140 exiting the drain 156 is recovered and reintroduced into the immersion hood 120 through the immersion fluid inlet port 132. In some embodiments, the immersion fluid 140 exiting the drain 156 is filtered or otherwise treated prior to recovery. In some embodiments, the drain 156 is connected to at least one of the holes 136 or 138 or the immersion fluid output port 132. In some embodiments, the suction back line 154 is omitted, and each of the suction back lines 150 and 152 extends to the rear surface of the wafer table 110 to a drain, such as drain 156.

Fig. 2A is a top view of a wafer table 200A according to some embodiments. The wafer table 200A may be used as the wafer table 110 in the immersion lithography system 100 (fig. 1). The wafer table 200A supports the wafer 112. The wafer table 200A includes a first sensor 210 at a first corner of the wafer table 200A. The wafer table 200A includes a second sensor 220 at a second corner of the wafer table 200A. The wafer table 200A includes a third sensor 230 at a third corner of the wafer table 200A. The wafer table 200A further includes a particle trapping region 240. Particle catch zone 240 has a dimension X in a first direction and a dimension Y in a second direction perpendicular to the first direction. Particle capture area 240 is separate from the wafer and each of sensors 210, 220, and 230. Fig. 2A includes arrows indicating the path of an immersion hood, such as immersion hood 120 (fig. 1), on wafer table 200A. As described above, the immersion hood and the wafer table 200A can be moved relative to each other by moving the wafer table 200A or the immersion hood.

The immersion hood is moved from the first sensor 210 to the second sensor 220 and then to the third sensor 230 to calibrate the immersion hood to determine the relative position between the immersion hood and the wafer table 200A. In some embodiments, at least one of the first sensor 210, the second sensor 220, or the third sensor 230 comprises a focus sensor to determine whether a lens system, such as the lens system 125 (FIG. 1), of the immersion hood is in proper focus. In some embodiments, at least one of the first sensor 210, the second sensor 220, or the third sensor 230 comprises an overlay error sensor in order to determine the relative position between the wafer table 200A and the immersion hood. In some embodiments, at least one of the first sensor 210, the second sensor 220, or the third sensor 230 comprises an energy sensor to determine the intensity of the beam exiting the immersion hood. In some embodiments, the first sensor 210 is the same sensor as each of the second sensor 220 and the third sensor 230. In some embodiments, the first sensor 210 is different from at least one of the second sensor 220 or the third sensor 230. In some embodiments, the second sensor 220 is different from the third sensor 230. In some embodiments, at least one of the first sensor 210, the second sensor 220, or the third sensor 230 is in a location other than a corner of the wafer table 200A. The locations of sensors 210, 220, and 230 are not particularly limited as long as the sensors do not overlap wafer 112 or particle capture area 240.

The particle catch region 240 extends along a surface, such as the top surface 115 (fig. 1), of the wafer table 200A. After the immersion hood is calibrated by overlapping each of the sensors 210, 220, and 230 with the immersion hood, the immersion hood travels along the particle capture area 240. Particle catch zone 240 is formed by depositing a layer of material on wafer table 200A. The material has similar surface characteristics as wafer 112. Similar surface characteristics help the particle capture area 240 collect particles from the immersion hood that accumulate during the calibration movement. By collecting the particles on the particle catch area 240, the particles are not transferred onto the wafer 112 and the production yield of the wafer 112 is improved.

In some embodiments, the material comprises silicon or silicon oxynitride. In some embodiments, the material comprises a photoresist material or another suitable material. In some embodiments, dimension X is greater than or equal to 26 millimeters (mm). In some cases, if the dimension X is too small, the risk of particles being transferred to the wafer 112 increases. In some embodiments, dimension Y is greater than or equal to 33 mm. In some cases, if dimension Y is too small, the risk of particles being transferred to wafer 112 increases.

In some embodiments, dimension X is less than 26mm or dimension Y is less than 33mm depending on the routing path of the immersion hood over particle capture area 240. The routing path is the trajectory of the immersion hood over the particle capture area 240. In some embodiments, the size of particle catch area 240 decreases as the length of the routing path increases. In some embodiments, the minimum routing path length in the first direction is 26 mm. In some embodiments, the minimum routing path length in the second direction is 33 mm. In some cases, if the routing path length in the first direction is too small, the risk of particles being transported to the wafer 112 increases. In some cases, if the routing path length in the second direction is too small, the risk of particles being transported to the wafer 112 increases. Fig. 3A-3F detail some embodiments of routing paths.

Fig. 2B is a top view of a wafer table 200B according to some embodiments. The wafer table 200B is similar to the wafer table 200A (fig. 2A). In contrast to wafer table 200A, wafer table 200B includes an additional particle capture region 240'. The particle catch region 240' is located along the same side of the wafer table 200B as the particle catch region 240. The particle catch zone 240' has the same size Y in the second direction as the particle catch zone 240. In some embodiments, particle catch region 240' has a different size in the second direction than particle catch region 240. Particle catch zone 240 'has a dimension X' in the first direction. In some embodiments, dimension X' is equal to dimension X. In some embodiments, dimension X' is different from dimension X. In some embodiments, dimension X' is greater than or equal to 26 mm. In some cases, if the dimension X' is too small, the risk of particles being transferred to the wafer 112 increases. In some embodiments, dimension X 'is less than 26mm depending on the length of the routing path over particle capture area 240'. In some embodiments, particle trapping region 240' comprises the same material as particle trapping region 240. In some embodiments, particle capture region 240' comprises a material that is different from the material of particle capture region 240.

In some embodiments, the immersion hood is routed over particle capture area 240 and particle capture area 240'. In some embodiments, the immersion hood is routed only on one of particle capture area 240 or particle capture area 240'. In some embodiments, the routing of the immersion hood is based on the material of the uppermost layer of the wafer 112. The immersion hood is routed over a particle capture zone 240 or 240 ', the particle capture zone 240 or 240' having surface characteristics that most closely resemble the surface characteristics of the uppermost layer of the wafer 112.

By including the particle catch region 240', the wafer table 200B includes additional variations in the interface between the immersion hood and the wafer table 200B. As described above, the change of the interface is a cause of deposition or adhesion of particles to the lower surface thereof. By increasing the amount of interface change, the wafer table 200B can reduce the likelihood of transporting particles to the wafer 112. The wafer table 200B includes two particle trapping regions. However, one of ordinary skill in the art will recognize that more than two particle capture regions are possible based on the present disclosure.

Fig. 2C is a top view of a wafer table 200C according to some embodiments. The wafer table 200C is similar to the wafer table 200A (fig. 2A). The wafer table 200C includes an additional particle capture region 240 "as compared to the wafer table 200A. The particle catch region 240 "is located along a different side of the wafer table 200C than the particle catch region 240. Particle catch area 240 "has a dimension Y" in the second direction. In some embodiments, dimension Y "is equal to dimension Y. In some embodiments, dimension Y "is different from dimension Y. In some embodiments, dimension Y "is greater than or equal to 33 mm. In some cases, if dimension Y "is too small, the risk of particles being transferred to wafer 112 increases. In some embodiments, dimension Y "is less than 33mm depending on the length of the routing path over particle capture area 240". Particle capture region 240 "has a dimension X in a first direction. In some embodiments, dimension X "is equal to dimension X. In some embodiments, dimension X "is different from dimension X. In some embodiments, dimension X "is greater than or equal to 26 mm. In some cases, if dimension X "is too small, the risk of particles being transferred to wafer 112 increases. In some embodiments, dimension X "is less than 26mm depending on the length of the routing path over particle capture area 240". In some embodiments, particle capture region 240 "comprises the same material as particle capture region 240. In some embodiments, particle capture region 240 "comprises a material that is different from the material of particle capture region 240.

In some embodiments, the immersion hood is routed over particle capture area 240 and particle capture area 240 ″. In some embodiments, the immersion hood is routed over only one of particle capture area 240 or particle capture area 240 ″. In some embodiments, the routing of the immersion hood is based on the material of the uppermost layer of the wafer 112. The immersion hood is routed over a particle capture zone 240 or 240 "that has surface characteristics that are most similar to the surface characteristics of the uppermost layer of the wafer 112 in the particle capture zone 240 or 240".

By including a particle capture area 240 ", the controller can select a routing path of the immersion hood over the wafer table 200C to move the immersion hood over the particle capture area, such as the particle capture area 240 or the particle capture area 240", having surface characteristics closest to surface characteristics of the wafer 112. By using a particle capture zone with surface properties closest to the wafer 112, the risk of particles being transferred to the wafer 112 is reduced. For example, in some embodiments, where the surface characteristics of wafer 112 are closest to particle capture area 240 ", the immersion hood is routed around particle capture area 240 to particle capture area 240". Regardless of which particle capture area is within the routing path of the immersion hood, the routing path of the immersion hood does not pass through the wafer 112 before passing through the particle capture area. In some embodiments, the immersion hood passes through particle capture area 240 and particle capture area 240 ″.

Figure 3A is a top view of routing path 300A along particle capture area 240 according to some embodiments. Routing path 300A includes a trajectory 310A having an L-shape. The total length of the traces 310A in the first direction is at least 26mm in order to reduce the risk of particles being transferred to the wafer, such as the wafer 112 (fig. 1 and 2A-2C). The total length of the track 310A in a second direction perpendicular to the first direction is at least 33mm in order to reduce the risk of particles being transported to a wafer, such as wafer 112. Since the trajectory 310A includes a single leg in the first direction and a single leg in the second direction, the overall size of the particle catch area 240 is at least 26mm in the first direction and at least 33mm in the second direction to accommodate the minimum trajectory length of the trajectory 310A in each direction.

Figure 3B is a top view of routing path 300B along particle capture area 240 according to some embodiments. Routing path 300B includes trajectory 310B. The track 310B is similar to the track 310A. In contrast to trace 310A, trace 310B has a U-shape. The track 310B has two legs in a first direction, where the two legs are oriented 180 degrees relative to each other. In some embodiments, because track 310B has two legs in the first direction, the overall size of particle catch region 240 of track 310B is reduced compared to particle catch region 240 of track 310A. In some embodiments, for a trajectory having N legs oriented 180 degrees relative to each other and parallel to the edges of particle capture region 240, the minimum dimension of the corresponding particle capture region 240 is equal to Ldx/N, where Ldx is the minimum length dimension in the respective direction. For example, in some embodiments, the smallest dimension of particle catch region 240 of trajectory 310B in the first direction is 13mm (26 mm/2). In some embodiments, particle catch area 240 is larger than the smallest dimension.

Figure 3C is a top view of routing path 300C along particle capture area 240 according to some embodiments. Routing path 300C includes trajectory 310C. Trace 310C is similar to trace 310A. In contrast to the trace 310A, the trace 310C has an S-shape. The track 310C has a plurality of legs in the first direction. However, since in some embodiments the legs in the first direction are not oriented 180 degrees from each other, the minimum dimension of the particle catch area 240 for the trajectory 310C in the first direction is 26 mm. The track 310C has 5 legs oriented 180 degrees from each other in the second direction. Thus, in some embodiments, the smallest dimension of the particle catch area 240 of the trajectory 310C in the second direction is 6.6mm (33 mm/5).

Figure 3D is a top view of routing path 300D along particle capture area 240 according to some embodiments. Routing path 300D includes trajectory 310D. The track 310D is similar to the track 310C. In contrast to the trace 310C, the trace 310D has a sawtooth shape. The track 310D has a plurality of legs oriented 180 degrees from each other. However, the legs of trajectory 310D are angled with respect to the edge of particle catch area 240. The smallest dimension of the particle capture area 240 of the trajectory 310D in each of the first and second directions depends on the angle of the legs of the trajectory 310D. In some embodiments, the minimum size of the particle catch area 240 is set such that the total distance of the trajectory 310D in the first direction is at least 26mm and in the second direction is at least 33 mm.

Figure 3E is a top view of routing path 300E along particle capture area 240 according to some embodiments. Routing path 300E includes trajectory 310E. Trace 310E is similar to trace 310C. In comparison to trace 310C, trace 310E has an S-shape with one leg in the first direction being longer than the other leg in the first direction. In some embodiments, the minimum size of particle catch area 240 is set such that the total distance of trajectories 310E in the first direction is at least 26mm and in the second direction is at least 33 mm.

Figure 3F is a top view of routing path 300F along particle capture area 240 according to some embodiments. Routing path 300F includes trajectory 310F. Track 310F is similar to the combination of track 310B and track 310C. The trace 310F has a first portion that is S-shaped and a second portion that is U-shaped. In some embodiments, the minimum size of particle catch area 240 is set such that the total distance of trajectories 310E in the first direction is at least 26mm and in the second direction is at least 33 mm.

One of ordinary skill in the art will recognize that fig. 3A-3F are merely examples of routing paths and that other routing path shapes are within the scope of the present disclosure.

FIG. 4 is a schematic diagram of a system 400 for controlling an immersion lithography system according to some embodiments. The system 400 includes a controller 410. The controller 410 communicates with the immersion hood 420, wafer stage motor 430, and immersion fluid flow motor 440. In some embodiments, the controller 410 communicates using a wired connection. In some embodiments, the controller communicates using a wireless connection.

The controller 410 is configured to control various portions of the immersion lithography system to direct the immersion hood 420 to overlap at least one particle capture zone on the wafer table coupled to the wafer table motor 430. The controller 410 controls at least one of the immersion hood 420 or the wafer table motor 430 to control the relative position of the immersion hood 420 on the wafer table. In some embodiments, the controller 410 is configured to control the movement of the immersion hood 420. In some embodiments, the controller 410 is used to control the operation of the wafer table motor 430. In some embodiments, the controller 410 is configured to control the movement of the immersion hood 420 and the operation of the wafer stage motor 430. In some embodiments, the controller 410 receives information about a wafer to be patterned, such as the type of wafer 112 (fig. 1 and 2A-2C), and determines which particle capture zone on the wafer table has a surface feature closest to the surface feature of the wafer. The controller 410 then controls the immersion hood 420 and/or the wafer stage motor 430 such that the immersion hood 420 overlaps the determined particle capture area. The controller 410 also receives information regarding the size of each particle capture area on the wafer table and determines the routing paths, such as routing paths 300A-300F (FIGS. 3A-3F), of the immersion hood 420 over the corresponding particle capture area to reduce the risk of particles being delivered to the wafer. As described above, the controller 410 selects the routing path to travel a minimum distance over the particle capture area in each of the first direction and the second direction.

The controller 410 is further configured to control the immersion fluid flow motor 440. The controller 410 controls the immersion fluid flow motor 440 to set the flow rate and pressure of the immersion fluid from the immersion hood 420.

The controller 410 is configured to receive information, for example, from the sensors 210, 220, and 230 (FIGS. 2A-2C), in order to determine the position of the immersion hood 420 relative to the wafer table. In some embodiments, the controller 410 is further configured to receive information, such as from a flow meter, to measure the flow rate and/or pressure of the immersion fluid exiting the immersion hood 420. Based on this information, the controller 410 is able to control the different components of the system 400 in order to reduce the risk of particles being transferred to the wafer. Therefore, the production yield of the wafer is improved.

The immersion hood 420, such as the immersion hood 120 (FIG. 1), delivers a patterned beam to a wafer, such as the wafer 112, on the wafer table and delivers an immersion liquid to the wafer table. In some embodiments, the immersion hood 420 is stationary. In some embodiments, the immersion hood 420 is movable.

The wafer table motor 430 is used to move the wafer table, such as the wafer table 110 (fig. 1), in a plane parallel to the top surface of the wafer table. In some embodiments, the wafer table motor 430 includes a plurality of motors. For example, in some embodiments, the wafer stage motor 430 includes a first motor for movement in a first direction and a second motor for movement in a second direction perpendicular to the first direction. In some embodiments, the wafer stage motor 430 includes a stepper motor, a rack and pinion motor, a piezo motor, a servo motor, or another suitable motor.

The immersion fluid flow motor 440 is configured to control the flow of immersion fluid, such as the immersion fluid 140 (FIG. 1), from the immersion hood 420 to the wafer table. In some embodiments, the immersion fluid flow motor 440 is part of the immersion hood 420. In some embodiments, the immersion fluid flow motor 440 is a piezoelectric motor, a servo motor, or another suitable motor.

FIG. 5 is a flow diagram of a method 500 of using an immersion lithography system according to some embodiments. The method 500 may be used with the system 100 (fig. 1), the wafer tables 200A-200C (fig. 2A-2C), and/or the system 400 (fig. 4). In operation 510, a wafer, such as wafer 112 (fig. 1), is placed on a wafer table, such as wafer table 110 (fig. 1). The wafer table has a particle catch region on a portion of a top surface of the wafer table. In some embodiments, a robot arm is used to place the wafer on the wafer table. In some embodiments, a vacuum chuck is used to hold the wafer on the wafer table. In some embodiments, the wafer table may move in a plane parallel to the top surface of the wafer table. In some embodiments, after operation 510, the wafer and wafer stage are similar to the arrangement in any of fig. 2A-2C.

In operation 520, the immersion hood is calibrated. An immersion hood, such as immersion hood 120 (fig. 1), is calibrated by placing the immersion hood over a sensor in the wafer table to accurately determine the position of the immersion hood relative to the wafer table. In some embodiments, the immersion hood is stationary. In some embodiments, the immersion hood is movable. In some embodiments, the immersion hood is calibrated by using a travel path similar to that in fig. 2A-2C.

In operation 530, the immersion hood is moved over the particle capture area. Particle capture regions, such as particle capture region 240 (fig. 2A-2C), help collect or capture particles from the wafer table to prevent the transport of these particles to the wafer. In some embodiments, the immersion hood is moved over the particle capture area by moving the wafer table. In some embodiments, the immersion hood is moved over the particle capture area by moving the immersion hood.

The particle catch region extends along the top surface of the wafer table. The particle catch region is formed by depositing a layer of material on the wafer table. The material has similar surface characteristics as the wafer. Similar surface characteristics help the particle capture area collect particles from the immersion hood that accumulate during the calibration motion. In some embodiments, during operation 530, the immersion hood is moved over the plurality of particle capture areas.

In some embodiments, the particle trapping region comprises silicon or silicon oxynitride. In some embodiments, the material comprises a photoresist material or another suitable material. In some embodiments, the minimum travel distance of the immersion hood over the particle capture area in the first direction is 26 mm. In some cases, if the distance of travel in the first direction is too small, the risk of particles being transferred to the wafer is increased. In some embodiments, the minimum travel distance of the immersion hood over the particle capture area in a second direction perpendicular to the first direction is 33 mm. In some cases, if the minimum travel distance in the second direction is too small, the risk of particles being transferred to the wafer is increased. In some embodiments, the immersion hood is moved over the particle capture area in a manner similar to at least one routing path in fig. 3A-3F. In some embodiments, the immersion hood moves over the particle capture area in a manner different from the routing path in fig. 3A-3F.

In operation 540, the wafer is exposed. The wafer is exposed by emitting a patterned beam from a lens system of the immersion hood, such as lens system 125 (FIG. 1), through an immersion fluid, such as immersion fluid 140 (FIG. 1), and onto the wafer. The patterned beam is scanned over the surface of the wafer by relative motion between the wafer table and the immersion hood. The patterned beam imparts a patterned photosensitive layer, which is located on the wafer.

In optional operation 550, the particle capture zone is flushed. Flushing the particle collection area after exposing the wafer helps to reduce the risk of accumulation of particles in the particle capture area, which are subsequently transported to another wafer. In some embodiments, the particle capture zone is flushed with an immersion fluid. For example, after the wafer is removed from the wafer table, the immersion fluid is passed through the wafer table at a high flow rate or pressure. In some embodiments, the particle capture region is rinsed with water, deionized water, or another suitable rinsing material. In some embodiments, the particle trapping region is rinsed using a mechanical wiping process. In some embodiments, operation 550 is omitted. For example, in some embodiments where the wafer is being rinsed as part of the exposure process, such a rinsing process will also rinse the particle trapping region and omit the separate operation 550.

FIG. 6 is a schematic diagram of a controller 600 for controlling an immersion lithography system according to some embodiments. The controller 600 includes a hardware processor 602 and a non-transitory computer-readable storage medium 604 having encoded (i.e., stored) computer program code 606, i.e., a set of executable instructions. Computer-readable storage medium 604 is also encoded with instructions 607 for interfacing with a manufacturing machine, such as a motor, pump, etc. The processor 602 is electrically coupled to the computer-readable storage medium 604 via the bus 608. The processor 602 is also electrically coupled to an I/O interface 610 through the bus 608. A network interface 612 is also electrically coupled to the processor 602 via the bus 608. The network interface 612 is connected to a network 614 so that the processor 602 and the computer-readable storage medium 604 can be connected to external elements via the network 614. The processor 602 is configured to execute computer program code 606 encoded in a computer readable storage medium 604 to make the controller 600 operable to perform some or all of the operations described in the method 500 or with respect to the system 400.

In some embodiments, the processor 602 is a Central Processing Unit (CPU), a multiprocessor, a decentralized processing system, an Application Specific Integrated Circuit (ASIC), and/or a suitable processing unit.

In some embodiments, the computer-readable storage medium 604 is an electronic system, a magnetic system, an optical system, an electromagnetic system, an infrared system, and/or a semiconductor system (or apparatus or device). The computer-readable storage medium 604 includes, for example, a semiconductor or solid state memory, magnetic tape, a removable computer diskette, a Random Access Memory (RAM), a read-only memory (ROM), a rigid magnetic disk and/or an optical disk. In some embodiments that use optical disks, the computer-readable storage medium 604 includes a compact disk-read only memory (CD-ROM), a compact disk-read/write (CD-R/W), and/or a Digital Video Disk (DVD).

In some embodiments, the storage medium 604 stores computer program code 606 for causing the controller 600 to perform the operations of the method 500 or the system 400. In some embodiments, the storage medium 604 also stores information needed to perform the actions of the method 500 or system 400 and information generated during performance of the performance, such as a flow rate parameter 616, a pressure parameter 618, a table position parameter 620, a mask position parameter 622, and/or a set of executable instructions to perform the operations of the method 500 or system 400.

In some embodiments, the storage medium 604 stores instructions 607 for interfacing with a manufacturing machine. The instructions 607 enable the processor 602 to generate fabrication machine-readable fabrication instructions to effectively implement the actions of the method 500 or system 400 during fabrication.

The system 600 includes an I/O interface 610. The I/O interface 610 is coupled to external circuitry. In some embodiments, the I/O interface 610 includes a keyboard, keypad, mouse, trackball, trackpad, and/or cursor direction keys for communicating information and commands to the processor 602.

The controller 600 also includes a network interface 612 that is coupled to the processor 602. The network interface 612 allows the controller 600 to communicate with a network 614, to which network 614 one or more other computer systems are connected. The network interface 612 includes a wireless network interface such as BLUETOOTH, WIFI, WIMAX, GPRS, or WCDMA, or a wired network interface such as ETHERNET, USB, or IEEE-1394. In some embodiments, the method 500 or system 400 is implemented in two or more controllers 600, and information such as flow rates, pressures, table positions, and mask positions are exchanged between the different controllers 600 via a network 614.

The controller 600 is configured to receive information related to the flow rate of an immersion fluid, such as the immersion fluid 140 (fig. 1). The flow rate is then stored as a flow rate parameter 616 in the computer-readable medium 604. The controller 600 is configured to receive information related to the immersion fluid pressure via the I/O interface 610 or the network interface 612. The information is stored 604 in a computer-readable medium as a pressure parameter 618. The controller 600 is configured to receive information regarding the position of a wafer table, such as the wafer table 110 (FIG. 1), via the I/O interface 610 or the network interface 612. The information is stored in the computer-readable medium 604 as station location parameters 620. The controller 600 is configured to receive information regarding the position of an immersion hood, such as the immersion hood 120 (FIG. 1), via the I/O interface 610 or the network interface 612. The information is stored in the computer-readable medium 604 as mask position parameters 622.

During operation, the processor 602 executes a set of instructions to determine a relative position of the immersion hood to the wafer table in order to route the immersion hood over the particle capture area prior to moving the immersion hood over a wafer of the wafer table. The processor 602 also executes instructions to control the flow rate and pressure of the immersion fluid during relative motion of the immersion hood and exposure of the wafer.

Aspects of the present description relate to an immersion lithography system. The immersion lithography system includes an immersion hood, wherein the immersion hood includes a lens system. The immersion lithography system further includes a wafer table, wherein the wafer table is movable relative to the immersion hood, and the wafer table includes an area for receiving a wafer. The immersion lithography system further includes a first particle capture zone on the wafer table and outside the region for receiving the wafer, wherein the first particle capture zone comprises silicon, silicon oxynitride, or photoresist material. In some embodiments, the first particle trap region comprises silicon oxynitride. In some embodiments, a dimension of the first particle catch zone in a first direction parallel to a top surface of the wafer table is at least 26 millimeters (mm). In some embodiments, a dimension of the first particle catch zone in a second direction parallel to the top surface of the wafer table is at least 33mm, and the second direction is perpendicular to the first direction. In some embodiments, the immersion lithography system further comprises a second particle capture region on the wafer table. In some embodiments, the second particle trapping region comprises a different material than the first particle trapping region. In some embodiments, the second particle trapping region has a different size than the first particle trapping region. In some embodiments, the second particle capture region is located on the same side of the wafer table along the first particle capture region. In some embodiments, the second particle catch region is located on a different side of the wafer table along the first particle catch region.

Aspects of the present description relate to a wafer table. The wafer table includes an area for receiving a wafer. The wafer table further includes a first sensor located outside of the area for receiving the wafer. The wafer table further includes a second sensor located outside the region for receiving the wafer, wherein the second sensor is spaced apart from the first sensor. The wafer table further includes a first particle capture region located outside the region for receiving the wafer, wherein the first particle capture region is separated from the first sensor and the second sensor, a dimension of the first particle capture region in a first direction parallel to the top surface of the wafer table is at least 26 millimeters (mm), a dimension of the first particle capture region in a second direction parallel to the top surface of the wafer table is at least 33mm, and the second direction is perpendicular to the first direction. In some embodiments, the first particle capture region comprises silicon, silicon oxynitride, or photoresist material. In some embodiments, the wafer stage further comprises a second particle capture region located outside the region for receiving the wafer, wherein the second particle capture region separates the first particle capture region, the first sensor and the second sensor. In some embodiments, the second particle catch zone has a dimension in the first direction of at least 33 mm. In some embodiments, the second particle capture zone has a dimension in the second direction of at least 26 mm.

Aspects of the present description relate to a method of using an immersion lithography system. The method includes calibrating the immersion hood by moving the wafer table in a plane parallel to a top surface of the wafer table. The method further includes moving the wafer table to place the immersion hood on a particle capture area of the wafer table. The method further includes moving the wafer table to define a two-dimensional routing trajectory over the particle capture area. The method further includes moving the wafer table to place the immersion hood on the wafer table after defining the two-dimensional routing trajectory over the particle capture area. In some embodiments, moving the wafer table to define the two-dimensional routing trajectory includes moving the wafer table in the first direction by a total distance of at least 26 millimeters (mm). In some embodiments, moving the wafer table to define the two-dimensional routing trajectory includes moving the wafer table a total distance of at least 33 millimeters in a second direction, and the second direction is perpendicular to the first direction. In some embodiments, moving the wafer table to define the two-dimensional routing trajectory includes defining a two-dimensional routing trajectory having an L-shape, a U-shape, or an S-shape. In some embodiments, moving the wafer table to define the two-dimensional routing trajectory comprises moving the wafer table at a speed of about 0.001 mm/sec to about 1 mm/sec. In some embodiments, the method further includes exposing the wafer using a beam from the immersion hood, wherein the beam has a wavelength of 193 nanometers (nm).

The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions and alterations herein without departing from the spirit and scope of the present disclosure.