Image stabilization for digital lithography

Abstract

The present disclosure provides methods and systems for correcting the projection of an image from a spatial light modulator (SLM) onto a substrate in the presence of cross-scan vibration, including sub-pixel cross-scan vibration. These methods and systems include: offsetting a mask pattern on the SLM rotated relative to the lateral scan travel direction on the substrate, offsetting along the axis of the SLM to correct for the cross-scan vibration, and delaying or accelerating the projection of the mask pattern onto the substrate.

Description

background Technical Field

[0002] Embodiments of the present disclosure generally relate to lithography systems. In particular, embodiments of the present disclosure relate to a method for image stabilization for digital lithography. Background Art

[0004] Digital lithography is widely used in the manufacture of semiconductor devices, such as for back-end processing of semiconductor devices and display devices, such as liquid crystal displays (LCDs) and light emitting diode (LED) displays. For example, large area substrates are often used in the manufacture of LCDs. LCDs, or flat panel displays, are often used in active matrix displays, such as computers, touch panel devices, personal digital assistants (PDAs), cellular phones, television monitors, and the like. Typically, a flat panel display includes a layer of liquid crystal material as a phase change material at each pixel, sandwiched between two plates. When power from a power source is applied across or through the liquid crystal material, the amount of light passing through the liquid crystal material is controlled (i.e., selectively modulated) at the pixel location, enabling an image to be produced on the display.

[0005] One or more image projection systems can be utilized using conventional digital lithography systems. Each image projection system is constructed to project one or more write beams into the photoresist layer on the substrate surface. Each image projection system projects one or more write beams onto the surface of the substrate. By the write beam projected by the projection lens system, a pattern (also referred to as a mask pattern) is written into the photoresist layer on the substrate surface. However, due to the vibration in the digital lithography system, the write beam writes the corresponding image causing roughness, and sometimes causes waves or jagged patterns. In some cases, the roughness can have a pitch of up to 10nm to 10um. For example, a vibration source can be found in the actuator present in the digital lithography system and the air handling system, changing the stage velocity during image processing, air bearing flutter, and periodic resonance in the platform and eye mounting assembly.

[0006] Therefore, there is a need in the art for a method of stabilizing an image to reduce line roughness. Summary of the Invention

[0007] The method disclosed herein generally relates to a method for image stabilization for digital lithography. The method includes providing a spatial light modulator (SLM) in an image projection system, the spatial light modulator being positioned at a rotation angle relative to a transverse scanning (in-scan) direction, the spatial light modulator comprising a plurality of SLM pixels; and rasterizing a mask pattern for projection from the SLM, the mask pattern corresponding to a first group of SLM pixels among the plurality of pixels. Further embodiments include detecting cross-scan vibration between the SLM and a substrate at a controller, the cross-scan vibration causing cross-scan deviation; and in response to the detection, shifting the mask pattern within the SLM along the transverse scanning direction to a second group of SLM pixels to correct for the cross-scan deviation.

[0008] Further embodiments disclosed herein generally relate to a system for digital lithography, comprising a processor and a memory, the memory comprising computer-readable instructions for image stabilization. The method comprises providing a spatial light modulator (SLM) in an image projection system, the spatial light modulator positioned at a rotational angle relative to a transverse scanning direction, the spatial light modulator comprising a plurality of SLM pixels; and rasterizing a mask pattern for projection from the SLM, the mask pattern corresponding to a first group of SLM pixels among the plurality of pixels. Further embodiments comprise detecting, at a controller, cross-scan vibration between the SLM and a substrate, the cross-scan vibration causing cross-scan deviation; and in response to the detection, shifting the mask pattern within the SLM along the transverse scanning direction to a second group of SLM pixels to correct for the cross-scan deviation.

[0009] Embodiments disclosed herein generally relate to a non-transitory computer-readable medium comprising computer-readable instructions for a method for image stabilization in digital lithography. Embodiments of the method include providing a spatial light modulator (SLM) in an image projection system, the spatial light modulator positioned at a rotational angle relative to a transverse scanning direction, the spatial light modulator comprising a plurality of SLM pixels; and rasterizing a mask pattern for projection from the SLM, the mask pattern corresponding to a first group of SLM pixels among the plurality of pixels. Further embodiments include detecting, at a controller, cross-scan vibrations between the SLM and a substrate, the cross-scan vibrations causing cross-scan deviations; and in response to the detection, shifting the mask pattern within the SLM along the transverse scanning direction to a second group of SLM pixels to correct the cross-scan deviations. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Thus, so that the above-mentioned features of the present disclosure can be understood in detail, a more particular description of the present disclosure, briefly summarized above, can be obtained by reference to the embodiments, some of which are depicted in the accompanying drawings. It should be noted, however, that the drawings illustrate only exemplary embodiments and are therefore not to be considered limiting of the scope of the present disclosure, which may admit to other equally effective embodiments.

[0011] Figure 1 is a perspective view of a digital lithography system according to a disclosed embodiment.

[0012] Figure 2 is a schematic cross-sectional view of an image projection system according to an embodiment disclosed herein.

[0013] Figure 3 Depicted is a perspective schematic diagram of a multiple image projection system in accordance with disclosed embodiments.

[0014] Figure 4 Depicted is a perspective schematic diagram of an image projection system in accordance with disclosed embodiments.

[0015] Figure 5 Depicted is an enlarged perspective view of two pixel elements of a spatial light modulator in accordance with disclosed embodiments.

[0016] Figure 6 Schematic illustration of light beams reflected by two pixel elements of a spatial light modulator according to disclosed embodiments.

[0017] Figure 7 Schematically illustrates an implementation of a spatial light modulator as a platform passes beneath a processing unit in accordance with disclosed embodiments.

[0018] Figure 8 Correction of cross-scan direction vibrations according to an embodiment is depicted.

[0019] Figure 9 Image stabilization for sub-pixel cross-scan vibrations is depicted in accordance with disclosed embodiments.

[0020] Figure 10 Image stabilization of negative sub-pixel cross-scan vibrations according to disclosed embodiments is depicted.

[0021] Figure 11 Methods for image stabilization according to disclosed embodiments are described.

[0022] Figure 12 Depicted are example servers in an image processing system according to disclosed embodiments.

[0023] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation. DETAILED DESCRIPTION

[0024] Hereinafter, reference is made to embodiments of the present disclosure. However, it should be understood that the present disclosure is not limited to the specifically described embodiments. Rather, it is contemplated that any combination of the following features and elements, whether or not related to different embodiments, may be used to implement and practice the present disclosure. Furthermore, although embodiments of the present disclosure may achieve advantages over other possible solutions and / or over the prior art, whether or not a particular advantage is achieved by a given embodiment does not limit the present disclosure. Therefore, the following aspects, features, embodiments, and advantages are merely exemplary and are not considered to be elements or limitations of the appended claims unless expressly recited in the claims. Likewise, reference to the "present disclosure" should not be construed as a summary of any inventive subject matter disclosed herein and should not be considered to be elements or limitations of the appended claims unless expressly recited in the claims.

[0025] The present disclosure provides a method for correcting the projection of an image from a spatial light modulator (SLM) to a substrate in the presence of cross-scan vibrations including sub-pixel cross-scan vibrations.

[0026] In a typical digital lithography system, if cross-scan vibration is detected, the image can be projected earlier or later to compensate for the vibration. However, if cross-scan vibration is detected, the image is rasterized in real time and provided to the SLM for projection onto the substrate, a computationally intensive process. Furthermore, if the cross-scan vibration is smaller than the pixels of the SLM, previous approaches do not have a way to correct for this deviation.

[0027] The SLM is provided in an image projection system at an angle relative to the cross-scan direction. In some embodiments, the angle is about 1°, which can correct increments of up to 1 / 100 pixel, and angles up to 26° can correct increments of up to 1 / 2 pixel. The inventors have found that due to this angle, the SLM moves one pixel in the cross-scan direction, resulting in a 1.5-2% pixel shift in the corresponding cross-scan direction, which can be used to correct cross-scan vibration. The amount of pixel shift can be determined by dividing the cross-scan deviation by the tangent of the SLM rotation angle. For example, tan(1°) = 0.017 allows for correction of cross-scan vibration in increments of < 1 / 50 pixel; similarly, 3° allows correction in increments of < 1 / 20 pixel, 5° allows correction in increments of < 1 / 10 pixel, 11° allows correction in increments of < 1 / 5 pixel, 14° allows correction in increments of < 1 / 4 pixel, 18° allows correction in increments of < 1 / 3 pixel, and 26° allows correction in increments of < 1 / 2 pixel. By offsetting the rasterized image along the X-axis of the rotating SLM, cross-scan vibrations can be compensated for by sub-pixel distances. Once offset, the image deviates from the intended target only in the transverse scan direction, so the timing of the projection needs to be adjusted as described above. In some embodiments, the projection can be timed by setting a transverse scan direction coordinate of the substrate and triggering the projection when the SLM reaches that coordinate. In the context of this document, in some embodiments, "adjusting the timing of the projection" refers to changing the transverse scan coordinate at which the projection is triggered. By taking advantage of the relative rotational position of the SLM with respect to the transverse scan direction, each image can be rasterized before the SLM reaches a given image destination. In addition, as opposed to requiring real-time re-rasterization to compensate for cross-scan vibrations, the image provided will be substantially in accordance with the customer's design. This technical approach not only reduces the processing burden on processor and memory resources, but also produces a more faithful rendering of the intended customer design with less line edge roughness.

[0028] Figure 11 is a perspective view of a system 100 that may benefit from the embodiments disclosed herein. The system 100 includes a base frame 110, a slab 120, a platform 130, and a processing device 160. The base frame 110 can be placed on the floor of a manufacturing facility and can support the slab 120. A passive air isolator 112 can be located between the base frame 110 and the slab 120. The slab 120 can be a solid block of granite, and the platform 130 can be disposed on the slab 120. A substrate 140 can be supported by the platform 130. A plurality of holes (not shown) can be formed in the platform 130 to allow a plurality of lifting rods (not shown) to extend therethrough. The lifting rods can be raised to an extended position to receive the substrate 140, for example, from a transfer robot (not shown). The transfer robot can place the substrate 140 on the lifting rods, which can then gently lower the substrate 140 onto the platform 130.

[0029] The substrate 140 can be made of quartz, for example, and used as a part of a flat panel display. In other embodiments, the substrate 140 can be made of other materials. In some embodiments, the substrate 140 can have a photoresist layer formed on the substrate. The photoresist is sensitive to radiation and can be a positive photoresist or a negative photoresist, which means that after the pattern is written into the photoresist, those parts of the photoresist exposed to the radiation will be soluble or insoluble in the photoresist developer applied to the photoresist, respectively. The chemical composition of the photoresist determines whether the photoresist is a positive photoresist or a negative photoresist. For example, the photoresist can include at least one of diazonaphthoquinone, phenol formaldehyde resin, poly (methyl methacrylate (methyl methacrylate)), poly (methyl glutarimide (methyl glutarimide)) and SU-8. In this way, a pattern can be established on the surface of the substrate 140 to form an electronic circuit.

[0030] The system 100 may further include a pair of supports 122 and a pair of tracks 124. The pair of supports 122 may be disposed on the flat plate 120, and the flat plate 120 and the pair of supports 122 may be a single piece of material. The pair of tracks 124 may be supported by the pair of supports 122, and the platform 130 may move in a transverse scanning direction along the tracks 124. In one embodiment, the pair of tracks 124 is a pair of parallel magnetic channels. As shown in the figure, each track 124 of the pair of tracks 124 is straight. In other embodiments, the tracks 124 may have a non-linear shape. An encoder 126 or other sensor may be coupled to the platform 130 to provide position information to the controller 170 and may detect movement in the platform due to vibration. In some embodiments, the encoder 126 may be an interferometer or other device or sensor capable of detecting the position of the platform, the vibration of the platform, and the transverse scanning and / or cross-scanning deviation of the platform due to vibration.

[0031] The processing device 160 may include a support 162 and a processing unit 164. The support 162 may be disposed on the plate 120 and may include an opening 166 for the platform 130 to pass under the processing unit 164. The processing unit 164 may be supported by the support 162. In one embodiment, the processing unit 164 is a pattern generator configured to expose photoresist in a lithography process. In some embodiments, the pattern generator may be configured to perform a maskless lithography process. The processing unit 164 may include a plurality of image projection systems 301 (shown in FIG. 1 ) disposed in a housing 165. Figure 3 ). The processing device 160 can be used to perform maskless direct patterning. During operation, as Figure 1 As shown, one of the platforms 130 moves from a loading position to a processing position along a transverse scanning direction. A processing position may refer to one or more positions of the platform 130 when the platform 130 passes under the processing unit 164. During operation, the platform 130 may be supported by a plurality of air bearings 202 (shown in FIG. Figure 2 ) is lifted and can be moved from a loading position to a processing position along the pair of rails 124. A plurality of vertical guide air bearings 202 (shown in FIG. Figure 2 ) can be coupled to the platform 130 and positioned adjacent to the inner wall 128 of each support 122 to stabilize the movement of the platform 130. The platform 130 can also be moved in the cross-scan direction by moving along the rails 150 for processing and / or indexing the substrate 140.

[0032] Figure 2 According to one embodiment Figure 11 is a cross-sectional side view of the system 100. As shown, the platform 130 includes a plurality of air bearings 202 for elevating the platform 130. The platform 130 may also include motor coils (not shown) for moving the platform 130 along the track 124. The platform 130 and the processing equipment 160 may be surrounded by a housing (not shown) to provide temperature and pressure control.

[0033] The system 100 also includes a controller 170. The controller is generally designed to facilitate control and automation of the processing techniques described herein. The controller may be coupled to or in communication with one or more of the processing device 160, the platform 130, and the encoder 126. The processing device 160 and the platform 130 may provide information to the controller regarding substrate processing and substrate alignment. For example, the processing device 160 may provide information to the controller to alert it that substrate processing has been completed. The encoder 126 may provide position information to the controller, which is then used to control the platform 130 and the processing device 160.

[0034] The controller may include a central processing unit (CPU) (not shown), memory (not shown), and support circuits (or I / O) (not shown). The CPU may be any form of computer processor used in an industrial environment to control various processes and hardware (e.g., pattern generators, motors, and other hardware) and monitor these processes (e.g., process time and substrate position). The memory (not shown) is connected to the CPU and may be one or more readily accessible memories, such as random access memory (RAM), read-only memory (ROM), floppy disk, hard disk, or any other form of digital storage, local or remote. Software instructions and data may be encoded and stored in the memory for instructing the CPU. Support circuits (not shown) are also connected to the CPU in a conventional manner for supporting the processor. The support circuits may include conventional cache memory, power supplies, clock circuits, input / output circuits, subsystems, and the like. A program (or computer instructions) readable by the controller determines which tasks are executable on the substrate. The program may be software readable by the controller and may include code for monitoring and controlling, for example, process time and substrate position.

[0035] Figure 3 is a perspective diagram of a plurality of image projection systems 301 according to one embodiment. Figure 3As shown, each image projection system 301 generates a plurality of writing beams 302 along a plurality of tracks 310 that are projected onto a surface 304 of a substrate 140 corresponding to a plurality of processing locations 312. Each track 310 is scanned by one or more writing beams 302. The motion of the substrate 140 is along a transverse scanning direction indicated by arrow 315, while the cross-scan direction is indicated by arrow 320. As the substrate 140 moves along the transverse scanning direction and the cross-scan direction, the entire surface 304 can be patterned by the writing beams 302. The number of image projection systems 301 can vary based on the size of the substrate 140 and / or the speed of the platform 130. In one embodiment, there are 22 image projection systems 301 in the processing device 160.

[0036] Figure 4 According to one embodiment Figure 3 A perspective schematic diagram of one image projection system 301 among multiple image projection systems 301.

[0037] The image projection system 301 includes a spatial light modulator (SLM) 410 and projection optics 416. These components of the image projection system 301 vary depending on the SLM 410 used. The SLM 410 includes, but is not limited to, an array of microLEDs (microLEDs), VCSELs, liquid crystal displays (LCDs), or any solid-state emitters of electromagnetic radiation, and a digital mirror device (DMD). The SLM 410 includes a plurality of spatial light modulator pixels. Each of the plurality of SLM pixels is individually controllable and configured to project a writing beam corresponding to one of the plurality of pixels (e.g., Figure 5 、 6 , 7 , and other figures). The compilation of the plurality of pixels forms a pattern written into the photoresist, referred to herein as a mask pattern. The projection optics 416 include a projection lens, such as a 10x objective lens, for projecting light onto the substrate 140. In operation, each of the plurality of SLM pixels is in an "on" position or an "off" position based on mask pattern data provided to the SLM 410 by the controller 170. Each SLM pixel in the "on" position forms a writing beam, which is then projected by the projection optics 416 onto the surface of the photoresist layer of the substrate 140 to form one pixel of the mask pattern.

[0038] In one embodiment, spatial light modulator 410 is a DMD. Image projection system 301 includes light source 402, aperture 404, lens 406, frustrated prism assembly 408, SLM 410, and projection optics 416. In this embodiment, SLM 410 includes a plurality of mirrors, i.e., a plurality of spatial light modulator pixels. Each of the plurality of mirrors corresponds to a pixel, which may correspond to a pixel of a mask pattern. In some embodiments, the DMD includes more than approximately 4,000,000 mirrors, while in other embodiments, the DMD may include 1920×1080 mirrors, which represents the number of pixels for a high-definition television. Light source 402 is any suitable light source capable of generating light having a predetermined wavelength, such as a light emitting diode (LED) or a laser. In one embodiment, the predetermined wavelength is in the blue or near-ultraviolet (UV) range, for example, less than approximately 450 nm. Frustrated prism assembly 408 includes a plurality of reflective surfaces. In operation, a light beam 403 having a predetermined wavelength is generated by a light source 402. The light beam 403 is reflected by a truncated prism assembly 408 toward the DMD. When the light beam 403 reaches the mirrors of the DMD, each mirror in the "on" position reflects the light beam 403, i.e., forms a writing beam, also known as a "shot," which is then projected by the projection optics 416 to project onto the surface of the photoresist layer of the substrate 140. Multiple writing beams 302 (also known as multiple shots) form multiple pixels of the mask pattern.

[0039] Figure 5 4 is an enlarged perspective view of two pixel elements 502, 504 of an SLM 410 according to one embodiment. In an embodiment where the SLM 410 is a DMD, these pixel elements can be mirrors. As shown, each pixel element 502, 504 is arranged on a tilt mechanism 506, which is arranged on a memory unit 508. The memory unit 508 can be a CMOS SRAM. During operation, each pixel element 502, 504 is controlled by loading mask data into the memory unit 508. The mask data electrostatically controls the tilt of the pixel elements 502, 504 in a binary manner. When the pixel elements 502, 504 are in reset mode or no power is applied, the pixel elements 502, 504 are in a flat position that does not correspond to any binary position. Zero (0) in binary can correspond to the "off" position, which means that the pixel element is tilted at -10 degrees, -12 degrees, or any other feasible tilting manner in the negative direction. A one (1) in binary may correspond to the "on" position, meaning the pixel element is tilted at +10 degrees, +12 degrees, or any other possible tilt in the positive direction. Figure 5As shown, pixel element 502 is in the "off" position, while pixel element 504 is in the "on" position.

[0040] Figure 6 Schematically shows a Figure 5 4. The SLM 410 of FIG. 4 shows a light beam 403 reflected by two pixel elements 502 and 504 of the SLM 410. As shown in the figure, the pixel element 502 in the "off" position reflects the light beam 403 generated by the light source 402 to the light collector (light dump) 412. The pixel element 504 in the "on" position forms the writing beam 302 by reflecting the light beam 403 to the projection lens 416, which then projects the light beam 403 to the substrate 140.

[0041] Figure 7 One embodiment of an SLM 410 is schematically illustrated, wherein the stage 130 passes beneath the processing unit 164, transporting the substrate 140 beneath the image projection system 301 in a transverse scanning direction indicated by arrow 315, wherein the SLM 410 travels along a track 310 to project a mask pattern at a plurality of processing locations 312. At each processing location 312, the pixel elements of the SLM 410 direct light toward individual pixels of the substrate 140, or away from the pixels into a light collector 412.

[0042] The pixel elements 502, 504, etc. of the SLM 410 are arranged in an array. Figure 7 As shown, SLM 410 is positioned to be substantially aligned with substrate 140, but not perfectly aligned. The rotational offset of SLM 410 from substrate 140 defines the error. In some embodiments, the rotational offset of SLM 410 (e.g., the rotational offset of SLM axis 710 relative to the transverse scanning direction of SLM 410, indicated by arrow 315) is approximately 1 degree (e.g., for correction increments < 1 / 50 pixel), while in other embodiments, the rotational offset can be in the range of 0.5 degrees to 26 degrees for correction increments ranging from 1 / 100 pixel to 0.5 pixel. The rotation of SLM 410 can be seen in the positioning of SLM axis 710. In embodiments, SLM axis 710 is offset from the transverse scanning direction of the substrate by the same rotational angle as the rotational angle of SLM 410 from the transverse scanning direction, and SLM axis 710 can be considered the transverse scanning axis of the SLM.

[0043] As the substrate 140 moves beneath the SLM 410, if more than a threshold area per pixel of the substrate 140 is beneath the SLM 410, the pixel element 502, 504, etc. corresponding to the pixel in that location will receive an "on" (or "off" signal, depending on the image tone (e.g., photoresist type)). If less than a threshold area per pixel of the substrate 140 is beneath the SLM 410, the pixel element 502, 504, etc. corresponding to the pixel in that location will not receive an "off" (or "on" signal, depending on the image tone). The threshold area may be 50% of the surface area of ​​the pixel. In other threshold tests, the criterion may be whether the pixel centroid is inside or outside the geometry to be printed.

[0044] In one embodiment, the array of pixel elements 502, 504, etc. in the SLM 410 can be rectangular, with more pixel elements 502, 504 arranged in the cross-scan direction than in the cross-scan direction, where the cross-scan direction substantially corresponds to the direction of motion of the stage 130, and therefore the direction of motion of the substrate 140. In other embodiments, the SLM 410 can be square or any other shape.

[0045] For example, the ratio of the number of pixel elements 502, 504 arranged in the cross-scan direction to the number of pixel elements 502, 504 arranged in the cross-scan direction can be approximately 9:16, or approximately 7:21, or approximately 3:4. In one embodiment, an SXGA+ type SLM provides 1400 mirror pixels in the Y direction and 1050 mirror pixels in the X direction, with a total mirror pixel count of approximately 1.5 million and an aspect ratio (Y:X) of approximately 4:3. In another embodiment, a 1080P type SLM provides 1920 mirror pixels in the Y direction and 1080 mirror pixels in the X direction, with a total mirror pixel count of approximately 2 million and an aspect ratio (Y:X) of approximately 16:9. In another embodiment, a WQXGA type SLM provides 2560 mirror pixels in the Y direction and 1600 mirror pixels in the X direction, with a total mirror pixel count of approximately 4 million and an aspect ratio (Y:X) of approximately 16:10. In another embodiment, a 4K type SLM provides 4096 mirror pixels in the Y direction and 2160 mirror pixels in the X direction, for a total mirror pixel count of approximately 8 million, and an aspect ratio (Y:X) of approximately 17:9. In another embodiment, an SLM similar to the 4K type can be established, but with half the number of SLM pixel elements in the transverse scanning direction and twice the number of pixel elements in the cross-scanning direction. This type of SLM, referred to as a half 4K + half 4K type SLM, provides 8192 mirror pixels in the cross-scanning direction and 1080 mirror pixels in the transverse scanning direction, for a total mirror pixel count of approximately 8 million, and an aspect ratio (cross-scan: transverse scanning) of approximately 68:9. In another embodiment, an SLM can be established that doubles the number of mirror pixels in both the transverse scanning and cross-scanning directions. This type of SLM, called a full 4K+full 4K type SLM, provides 8192 mirror pixels in the cross-scan direction and 2160 mirror pixels in the horizontal scanning direction, with a total mirror pixel count of approximately 16 million and an aspect ratio (cross-scan: horizontal scan) of approximately 34:9.

[0046] Other embodiments may also be commercially practicable and / or available. For example, one embodiment of an SLM may be characterized by a total of 1080 pixel elements in the transverse scan direction and a total of 1920 pixel elements in the cross-scan direction. In another embodiment, the SLM may be characterized by a total of 1600 pixel elements in the transverse scan direction and a total of 2560 pixel elements in the cross-scan direction. In another embodiment, the SLM may be characterized by a total of 1960 pixel elements in the transverse scan direction and a total of 3880 pixel elements in the cross-scan direction. In another embodiment, the SLM may be characterized by an aspect ratio of 21:7 (cross-scan: transverse scan).

[0047] Those skilled in the art will appreciate that other ratios are possible. These embodiments share the following common feature: a greater number of pixel elements are provided in the direction of scanning, which improves scanning efficiency. However, this particular ratio may vary as a function of design and manufacture, as long as the number of pixel elements arranged in the cross-scan direction is greater than the number of pixel elements arranged in the transverse scan direction. In other embodiments, the number of pixel elements in the transverse scan direction may be greater than the number in the cross-scan direction, and in yet further embodiments, the number of pixel elements in each direction may be the same.

[0048] Figure 8 Correction 800 of cross-scan direction vibrations is depicted according to an embodiment.

[0049] The first example 801 depicts the SLM 410 approaching a processing location 312 within a track 310 on a substrate 140 (not shown in its entirety), traveling in a transverse scan direction as indicated by arrow 315, with a predetermined position for a mask pattern 805 that has been rasterized prior to arriving at the processing location 312. The controller 170 waits for the substrate 140 (moving relative to the SLM 410 in a direction opposite to the transverse scan direction indicated by arrow 315) to reach an overlap position to place the mask pattern 805 at a target location 806, at which point the controller 170 causes the light source 402 to flash onto the SLM 410 to transfer the mask pattern 805 at the target location 806 on the substrate 140.

[0050] A second example 810 depicts a position where the mask pattern 805 is to be printed at a desired target location 806 within the processing area 312. In this example, the controller 170 does not receive information from the encoder 126 indicating that the SLM 410 will experience vibration deviations while over the processing area 312. In this second example 810, radiation is projected onto the SLM 410, printing the mask pattern 805 at the desired location on the substrate 140. No shifting of the mask pattern 805 in the SLM 410 or modification of the printing time delay is required.

[0051] The third example 815 depicts a situation where the controller determines that negative cross-scan vibration exists when the SLM 410 is over the processing area 312. Because the SLM 410 and mask pattern 805 positions are predicted to be offset in the negative cross-scan direction by an amount 816, the controller delays printing of the SLM 410, resulting in the SLM 410 printing at the desired position, as shown by 818.

[0052] The fourth example 820 depicts a situation predicted by the controller 170 in which the encoder 126 detects a positive cross-scan vibration that, if no further action is taken, will result in a positive cross-scan offset 822. In response, the controller 170 accelerates the timing of the projection, as shown in 825, so that the SLM 410 projects the mask pattern 805 at the desired location within the processing area 312.

[0053] Figure 9 Image stabilization 900 for positive sub-pixel cross-scan vibrations is depicted in accordance with disclosed embodiments.

[0054] The fifth example 901 depicts a situation where the controller predictably determines that positive cross-scan vibration exists when the SLM 410 is over the processing area 312 based on data from the encoder 126. It can be seen that if no action is taken, the mask pattern 805 will be projected out of alignment with the desired target position.

[0055] In prior art methods, when the cross-scan vibration is equal to (or close to) an offset of the SLM pixel size, the mask pattern 805 is re-rastered, repositioned, or offset in SLM pixel increments along the cross-scan direction on the SLM 410. In the absence of cross-scan vibration, the SLM 410 is instructed to project the offset mask pattern 805 at the desired target location 806. However, because the mask pattern 805 can only be offset in full SLM pixel increments, placement errors in the cross-scan direction must be rounded to the nearest 0.5 pixel, which can cause image blurring, overlay errors, or line-edge roughness. As a result, without the benefit of the present disclosure, a digital lithography tool would need to optically shrink the pixel pitch to a smaller field size, which reduces the tool's productivity.

[0056] The sixth example 905 depicts correction of sub-pixel deviation in the positive cross-scan direction according to the disclosed embodiments. In this example, as in the fifth example 901, the controller 170 has received data from the encoder 126 indicating positive cross-scan vibration. The sixth example shows where the mask pattern 805 will be projected if no action is taken.

[0057] Controller 170 instructs image projection system 165 to shift mask pattern 805 on SLM 410 along axis 710 of SLM 410. As described above, because SLM 410 is rotated by an angle relative to cross-scan direction 315, shifting mask pattern 805 along SLM axis 710, as indicated by arrow 907, will in turn shift mask pattern 805 by 1.5-2% in the cross-scan direction for each pixel shifted in the direction of SLM axis 710. As a result, mask pattern 805 is shifted to the position of shifted mask pattern 906, correcting for positive cross-scan vibration. At this point, the shifted position of mask pattern 906 can be corrected in a manner similar to the fourth example 820 described above by instructing image projection system 165 to accelerate the projection time on SLM 410, so as to place the shifted mask pattern 805 at the desired target position 806. In some embodiments, the projection can be timed by setting a cross-scan direction coordinate of the substrate and triggering projection when the SLM reaches that coordinate. In this context, in some embodiments, "adjusting the timing of a projection" refers to changing the transverse scan coordinate at which the projection is triggered.

[0058] Figure 10 Image stabilization for negative sub-pixel cross-scan vibrations according to disclosed embodiments is depicted.

[0059] The seventh example 1005 depicts correction of sub-pixel deviation in the negative cross-scan direction according to the disclosed embodiments. In this example, the controller 170 has received data from the encoder 126 indicating negative cross-scan vibration. The seventh example shows where the mask pattern 805 will be projected if no action is taken.

[0060] Controller 170 instructs image projection system 165 to shift mask pattern 805 on SLM 410 in the negative direction of SLM axis 710. As described above, because SLM 410 is rotated by an angle relative to cross-scan direction 315, shifting mask pattern 805 along SLM axis 710 as indicated by arrow 1003 will in turn shift mask pattern 805 in the cross-scan direction by 1.5-2% (in embodiments with approximately 1 degree of SLM rotation) for each pixel shifted in the direction of SLM axis 710. As a result, mask pattern 805 is shifted to the position of shifted mask pattern 1006, correcting for negative cross-scan vibration. At this point, the position of shifted mask pattern 1006 can be corrected in a manner similar to the third example 815 described above by having controller 170 instruct image projection system 165 to delay projection time on SLM 410, so as to place shifted mask pattern 805 at the desired target position 806. In some embodiments, the projection may be timed by setting a transverse scan direction coordinate of the substrate and triggering the projection when the SLM reaches that coordinate. In this context, in some embodiments, "adjusting the timing of a projection" refers to changing the transverse scan coordinate at which the projection is triggered.

[0061] Figure 11 A method 1100 for image stabilization in accordance with disclosed embodiments is depicted.

[0062] At 1110, the method provides a spatial light modulator (SLM) in an image projection system, the spatial light modulator being positioned at a rotation angle relative to a transverse scanning direction, the spatial light modulator comprising a plurality of SLM pixels. In some embodiments, the rotation angle can be from 0.5 degrees to 26 degrees, and in some embodiments, the rotation angle is about 1 degree. For example, tan(1°)=0.017 allows for cross-scan vibration correction in increments of <1 / 50 pixel; similarly, 3° allows for correction in increments of <1 / 20 pixel, 5° allows for correction in increments of <1 / 10 pixel, 11° allows for correction in increments of <1 / 5 pixel, 14° allows for correction in increments of <1 / 4 pixel, 18° allows for correction in increments of <1 / 3 pixel, and 26° allows for correction in increments of <1 / 2 pixel.

[0063] At 1120 , method 1100 further includes rasterizing a mask pattern for projection from the SLM, the mask pattern corresponding to a first group of SLM pixels in the plurality of SLM pixels.

[0064] At 1130, the method includes detecting, at a controller, a cross-scan vibration between the SLM and the substrate, the cross-scan vibration causing the cross-scan deviation. In some embodiments, the detected cross-scan vibration is less than one SLM pixel in a plurality of SLM pixels.

[0065] At 1140, method 1100 further includes: in response to the detection, shifting the mask pattern within the SLM to a second set of SLM pixels in a cross-scan direction, in some embodiments along an axis of the SLM 710 that is primarily parallel to the cross-scan direction (e.g., the cross-scan axis), to correct for cross-scan deviation, and making a corresponding change to the cross-scan exposure location after shifting the mask pattern. In some embodiments, determining the amount of shift of the mask pattern along the SLM axis is determined by dividing the cross-scan deviation by the tangent of the rotation angle. In embodiments with a nominally 1 degree SLM rotation, shifting the mask pattern on the SLM by one pixel along the SLM axis corrects for 1.7% of the cross-scan deviation.

[0066] In an embodiment, the method 1100 further comprises providing radiation to the SLM for projecting the mask pattern onto the substrate, comprising one of delaying and accelerating the time of providing the radiation to the SLM based on the detection.

[0067] Figure 12 An example server 1200 in an image processing system is depicted that can perform the methods described herein, such as those related to Figures 1 to 11 A method of image stabilization is described.

[0068] The server 1200 includes a central processing unit (CPU) 1202 connected to a data bus 1216. The CPU 1202 is configured to process computer-executable instructions stored, for example, in the memory 1208 or the storage 1210 and cause the server 1200 to perform operations related to, for example, Figures 1 to 11 CPU 1202 is included to represent a single CPU, multiple CPUs, a single CPU with multiple processing cores, and other forms of processing architecture capable of executing computer-executable instructions.

[0069] The server 1200 further includes an input / output (I / O) device 1212 and an interface 1204 that allows the server 1200 to interface with the I / O device 1212, for example, to input / output data such as, for example, platform position data (e.g., real-time and / or instantaneous platform position data), such as cross-scan position data (e.g., x-coordinate position data) and cross-scan position data (e.g., y-coordinate position data) from the encoder 126 for providing patterns to an SLM such as the SLM 410 in the image projection system 301, and to input and output data to control a light source such as the light source 402, a keyboard, a display, a mouse device, a pen input device, and other devices that allow interaction with the server 1200. It should be noted that the server 1200 can be connected to external I / O devices (e.g., an external display device) via both physical and wireless connections.

[0070] The server 1200 further includes a network interface 1206 that provides the server 1200 with access to an external network 1214 , thereby providing access to external computing devices.

[0071] The server 1200 further includes a memory 1208, which in this example includes a memory for executing Figure 1-11 1218, rasterization module 1220, detection module 1222, offset module 1224, correction module 1226, delay module 1228, and acceleration module 1229. Figure 12 1220 is shown as residing in memory, but in some embodiments, one or more modules may be implemented in software, hardware, or a combination of software and hardware. In some embodiments, such hardware may be programmable hardware such as an FPGA. In some embodiments, rasterization module 1220 is in (or connected to) one or more graphics processing units (GPUs).

[0072] It should be noted that although for simplicity in Figure 12 A single memory 1208 is shown, but various aspects stored in memory 1208 may be stored in different physical memories, including memories remote from server 1200, but all of which are accessible by CPU 1202 via internal data connections such as bus 1216.

[0073] The memory 1210 further includes mask pattern data 1230, cross-scan vibration data 1232, and cross-scan deviation data 1234, which may be similar to Figure 1-11In some implementations, the cross-scan vibration data 1232 and the cross-scan deviation data 1234 may be provided by one or more sensors, such as the encoder 126 .

[0074] Despite Figure 12 Not shown, but other aspects may be included in storage 1210.

[0075] As with memory 1208, for simplicity, Figure 12 1210, but various aspects stored in storage 1210 may be stored in different physical storages, all of which are accessible to CPU 1202 via an internal data connection such as bus 1216 or an external connection such as network interface 1206. Those skilled in the art will appreciate that one or more elements of server 1200 may be located remotely and accessible via network 1214.

[0076] The foregoing description is provided to enable a person of ordinary skill in the art to practice the various embodiments described herein. The examples discussed herein do not limit the scope, applicability, or embodiments set forth in the claims. Various modifications to these embodiments will be apparent to a person of ordinary skill in the art, and the general principles defined herein may be applied to other embodiments. For example, the functions and arrangements of the elements discussed may be changed without departing from the scope of the present disclosure. Various examples may appropriately omit, replace, or add various processes or components. For example, the methods described may be performed in an order different from that described, and various steps may be added, omitted, or combined. Moreover, the features described with respect to some examples may be combined in some other examples. For example, a device may be implemented or a method may be practiced using any number of the aspects set forth herein. Furthermore, the scope of the present disclosure is intended to encompass such devices or methods practiced using other structures, functions, or structures and functions in addition to or in place of the various aspects of the present disclosure set forth herein. It should be understood that any aspect of the present disclosure disclosed herein may be embodied by one or more elements of the claims.

[0077] As used herein, a phrase referring to "at least one of" a list of items refers to any combination of those items, including single members. For example, "at least one of a, b, or c" is intended to encompass: a, b, c, ab, ac, bc, and abc, as well as combinations with multiples of the same element (e.g., aa, aaa, aab, aac, abb, acc, bb, bbb, bbc, cc, and ccc, or any other order of a, b, and c).

[0078] As used herein, the term "determining" encompasses a wide variety of actions. For example, "determining" may include calculating, computing, processing, deriving, investigating, searching (e.g., searching in a table, database, or another data structure), ascertaining, and the like. Furthermore, "determining" may include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory), and the like. Furthermore, "determining" may include resolving, selecting, choosing, establishing, and the like.

[0079] The methods disclosed herein include one or more steps or actions for implementing these methods. Without departing from the scope of the claims, these method steps and / or actions can be interchangeable with each other. In other words, unless the specific order of steps or actions is specified, the order and / or use of specific steps and / or actions can be modified without departing from the scope of the claims. In addition, the various operations of the above-mentioned method can be performed by any suitable means capable of performing the corresponding functions. The means may include various hardware and / or software components and / or modules, including but not limited to circuits, application specific integrated circuits (ASICs), or processors. Typically, in the case of operations shown in the figures, those operations can have means + function (means-plus-function) components of corresponding pairs with similar numbers.

[0080] The various illustrative logic blocks, modules, and circuits described in connection with the present disclosure may be implemented or executed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic devices, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but alternatively, the processor may be any commercially available processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, a combination of one or more microprocessors and a DSP core, or any other such configuration.

[0081] The processing system can be implemented using a bus architecture. Depending on the specific application and overall design constraints of the processing system, the bus can include any number of interconnecting buses and bridges. The bus can link together various circuits, including the processor, machine-readable media, and input / output devices. User interfaces (e.g., keyboard, display, mouse, joystick, etc.) can also be connected to the bus. The bus can also link various other circuits, such as timing sources, peripherals, voltage regulators, power management circuits, and other circuit elements that are well known in the art and will not be described in detail. The processor can be implemented as one or more general-purpose processors and / or special-purpose processors. Examples include microprocessors, microcontrollers, DSP processors, and other circuits that can execute software. Those skilled in the art will recognize how to best implement the described functionality for the processing system based on the specific application and the overall design constraints imposed on the entire system.

[0082] If implemented in software, these functions may be stored or transmitted as one or more instructions or codes on a computer-readable medium. Software should be broadly interpreted to mean instructions, data, or any combination thereof, whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. Computer-readable media include both computer storage media and communication media, such as any medium that facilitates the transfer of computer programs from one location to another. The processor may be responsible for managing the bus and general processing, including executing software modules stored on a computer-readable storage medium. A computer-readable storage medium may be coupled to the processor so that the processor can read information from the storage medium and write information to the storage medium. Alternatively, the storage medium may be integrated with the processor. For example, the computer-readable medium may include a transmission line, a carrier modulated by data, and / or a computer-readable storage medium separate from the wireless node and having instructions stored thereon, all of which can be accessed (or accessed) by the processor via a bus interface. Alternatively or additionally, the computer-readable medium or any portion thereof may be integrated into the processor, such as in the form of a cache and / or general register file. Examples of machine-readable storage media may include, for example, RAM (random access memory), flash memory, ROM (read-only memory), PROM (programmable read-only memory), EPROM (erasable programmable read-only memory), EEPROM (electrically erasable programmable read-only memory), registers, magnetic disks, optical disks, hard drives, or any other suitable storage media, or any combination thereof. The machine-readable medium may be embodied in a computer program product.

[0083] A software module may include a single instruction or multiple instructions and may be distributed across several different code segments, in different programs, and across multiple storage media. A computer-readable medium may include several software modules. These software modules include instructions that, when executed by a device such as a processor, cause a processing system to perform various functions. A software module may include a transmitting module and a receiving module. Each software module may reside in a single storage device or may be distributed across multiple storage devices. For example, when a triggering event occurs, a software module may be loaded from a hard drive into RAM. During the execution of a software module, the processor may load some instructions into a cache to increase access speed. One or more cache lines may then be loaded into a general register file for execution by the processor. When referring to the functions of a software module, it will be understood that such functions are implemented by the processor when instructions from that software module are executed.

[0084] The appended claims are not intended to be limited by the embodiments shown herein, but are to be accorded the full scope consistent with the language of the claims. In a claim, unless otherwise stated, a reference to an element in the singular is not intended to mean "one and only one," but rather "one or more." The term "some" means one or more unless expressly stated otherwise. No element of a claim is to be construed under Section 112(f) of the United States Patent Code unless the element is expressly recited using the phrase "means for" or, in the case of a method claim, the element is recited using the phrase "step for." All structural and functional equivalents to the elements throughout the various aspects described in this disclosure that are known or later come to be known to one of ordinary skill in the art are expressly incorporated herein by reference and are intended to be covered by the claims. In addition, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is expressly recited in the claims.

Claims

1. A method for image stabilization for digital lithography, comprising the following steps: providing a spatial light modulator (SLM) in the image projection system, the spatial light modulator being positioned at a rotation angle relative to a transverse scanning direction, the spatial light modulator comprising a plurality of SLM pixels; rasterizing a mask pattern to form a rasterized mask pattern for projection from the SLM, the mask pattern corresponding to a first group of SLM pixels of the plurality of SLM pixels; detecting, at a controller, cross-scan vibrations between the SLM and a substrate, the cross-scan vibrations causing cross-scan deviations; and In response to the detecting, the rasterized mask pattern within the SLM is shifted along the cross-scan direction to a second set of SLM pixels by adjusting the timing of the projections of the rasterized mask pattern to correct for the cross-scan deviation.

2. The method of claim 1, further comprising the steps of: Providing radiation to the SLM for projecting the rastered mask pattern onto a substrate includes one of delaying and accelerating the time of providing the radiation to the SLM based on the detecting.

3. The method of claim 1, further comprising the steps of: The offset of the rasterized mask pattern along the axis of the SLM is determined by dividing the cross-scan deviation by the tangent of the rotation angle. The method of claim 3 , wherein the rotation angle is from 0.5 degrees to 26 degrees. The method of claim 4 , wherein the rotation angle of the SLM is approximately 1 degree.

6. A system for digital lithography comprising a processor and a memory, the memory comprising computer readable instructions for a method for image stabilization, the method comprising the steps of: providing a spatial light modulator (SLM) in the image projection system, the spatial light modulator being positioned at a rotation angle relative to a transverse scanning direction, the spatial light modulator comprising a plurality of SLM pixels; rasterizing a mask pattern to form a rasterized mask pattern for projection from the SLM, the mask pattern corresponding to a first group of SLM pixels of the plurality of SLM pixels; detecting, at a controller, cross-scan vibrations between the SLM and a substrate, the cross-scan vibrations causing cross-scan deviations; and In response to the detecting, the rasterized mask pattern within the SLM is shifted along the cross-scan direction to a second set of SLM pixels by adjusting the timing of the projections of the rasterized mask pattern to correct for the cross-scan deviation.

7. The system of claim 6, wherein the method further comprises the steps of: Providing radiation to the SLM for projecting the rastered mask pattern onto a substrate includes one of delaying and accelerating the time of providing the radiation to the SLM based on the detecting.

8. The system of claim 6, wherein the method further comprises the steps of: The offset of the rasterized mask pattern along the axis of the SLM is determined by dividing the cross-scan deviation by the tangent of the rotation angle.

9. The system of claim 8, wherein the rotation angle is from 0.5 degrees to 26 degrees.

10. The system of claim 9, wherein the rotation angle of the SLM is approximately 1 degree.

11. A non-transitory computer readable medium comprising computer readable instructions for a method for image stabilization for digital lithography, the method comprising the steps of: providing a spatial light modulator (SLM) in the image projection system, the spatial light modulator being positioned at a rotation angle relative to a transverse scanning direction, the spatial light modulator comprising a plurality of SLM pixels; rasterizing a mask pattern to form a rasterized mask pattern for projection from the SLM, the mask pattern corresponding to a first group of SLM pixels of the plurality of SLM pixels; detecting, at a controller, cross-scan vibrations between the SLM and a substrate, the cross-scan vibrations causing cross-scan deviations; and In response to the detecting, the rasterized mask pattern within the SLM is shifted along the cross-scan direction to a second set of SLM pixels by adjusting the timing of the projections of the rasterized mask pattern to correct for the cross-scan deviation.

12. The non-transitory computer readable medium of claim 11 , the method further comprising the steps of: Providing radiation to the SLM for projecting the rastered mask pattern onto a substrate includes one of delaying and accelerating the time of providing the radiation to the SLM based on the detecting.

13. The non-transitory computer readable medium of claim 11, the method further comprising determining an offset of the rasterized mask pattern along an axis of the SLM by dividing the cross-scan deviation by a tangent of the rotation angle.

14. The non-transitory computer readable medium of claim 13, wherein the rotation angle is from 0.5 degrees to 26 degrees.

15. The non-transitory computer readable medium of claim 14, wherein the rotation angle of the SLM is approximately 1 degree.

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