Method and apparatus for correcting a lithographic system

Abstract

Aspects of the present disclosure relate to methods and apparatus for correcting a lithography system. In one embodiment, a method of operating a lithography system includes directing a first light beam toward a reflective surface of a first substrate using an optical module. The method includes directing the first light beam collected by at least one objective lens toward a camera and taking a plurality of first images of the first light beam. The method includes directing a second light beam at an oblique angle toward a patterned surface of a second substrate using an illumination source disposed below the objective lens. The method includes directing the second light beam collected by the at least one objective lens toward the camera and taking a plurality of second images of the second light beam. The method includes determining a tip correction, a tilt correction, and an optimal vertical position of the optical module.

Description

Technical Field

[0001] This disclosure relates to methods and apparatus for calibrating a lithography system. In one example, tilt correction, tip correction, and vertical correction are determined for the optical modules of the lithography system. Background Technology

[0002] Operational problems arise when the image plane projected by the photolithography system is not parallel to the substrate and / or is not focused. For example, a non-parallel and / or out-of-focus image plane can cause incorrect patterns and / or mura on the substrate. Defects in the photolithography system can also lead to incorrect patterns and / or mura on the substrate.

[0003] In addition, focusing and / or paralleling the image plane to the substrate can be difficult, time-consuming, and resource-intensive.

[0004] Therefore, a method and apparatus are needed that help to position and focus an image plane projected by a photolithography system parallel to the substrate. Summary of the Invention

[0005] This disclosure relates to methods and apparatus for calibrating lithography systems. In one example, tilt correction, tip correction, and vertical correction are determined for the optical modules of a lithography system.

[0006] In one embodiment, a method of operating a photolithography system includes: guiding a first light beam to a reflective surface of a first substrate using a spatial light modulator of an optical module. The method includes: collecting the first light beam reflected from the reflective surface and passing at least through an objective lens of the optical module. The method includes: guiding the first light beam collected at least through the objective lens to a camera of the optical module using a beam splitter of the optical module. The method includes: capturing multiple first images of the first light beam guided to the camera using the camera. The method includes: guiding a second light beam at an oblique angle to a patterned surface of a second substrate using an illumination source positioned below the objective lens. The method includes: collecting the second light beam scattered away from the patterned surface at least through the objective lens; and guiding the second light beam collected at least through the objective lens to the camera using a beam splitter. The method includes: capturing multiple second images of the second light beam guided to the camera using the camera. The method includes determining tip correction, tilt correction, and optimal vertical position of the optical module.

[0007] In one embodiment, a non-transitory computer-readable medium includes instructions that, when executed, cause a lithography system to: guide a first light beam to a reflective surface of a first substrate using a spatial light modulator of an optical module; collect the first light beam reflected from the reflective surface and passing at least through an objective lens of the optical module; guide the first light beam collected by the optical module, at least through the objective lens, to a camera of the optical module using a beam splitter of the optical module; capture multiple first images of the first light beam guided to the camera using the camera; guide a second light beam at an oblique angle to a patterned surface of a second substrate using an illumination source positioned below the objective lens; collect the second light beam scattered away from the patterned surface by the objective lens; guide the second light beam collected by the objective lens, at least through the objective lens, to the camera using a beam splitter; capture multiple second images of the second light beam guided to the camera using the camera; and determine tip correction, tilt correction, and optimal vertical position of the optical module.

[0008] In one embodiment, a non-transitory computer-readable medium includes instructions that, when executed, cause a lithography system to: direct a bright-field beam of light to a reflective surface of a first substrate using a spatial light modulator of an optical module. The instructions also cause the lithography system to capture multiple bright-field images of the reflected bright-field beam of light reflected from the reflective surface using a camera of the optical module. The instructions further cause the lithography system to direct a dark-field beam of light to a patterned surface of a second substrate. The instructions also cause the lithography system to capture multiple dark-field images of the scattered dark-field beam of light scattering off the patterned surface using a camera. The instructions also cause the lithography system to determine tip correction, tilt correction, and optimal vertical position of the optical module. Attached Figure Description

[0009] Several specific embodiments can be referenced to illustrate the above-briefly summarized disclosure in a more specific way, and to gain a more detailed understanding of the features of the disclosure. The accompanying drawings illustrate some of these specific embodiments. However, it should be noted that the drawings are merely illustrative of general embodiments of the disclosure and should therefore not be considered as limiting the scope of the disclosure, as other equivalent embodiments are permissible.

[0010] Figure 1 This is a schematic partial perspective view of a photolithography system according to one embodiment.

[0011] Figure 2 According to one embodiment, during bright field lighting operation... Figure 1 A three-dimensional schematic diagram of the image projection device used in the lithography system shown.

[0012] Figure 3 According to one embodiment, during dark field illumination operation... Figure 1A three-dimensional schematic diagram of the image projection device used in the lithography system shown.

[0013] Figure 4A It is based on one implementation method. Figure 2 and Figure 3 A schematic partial view of an image taken by the camera shown.

[0014] Figure 4B It is a schematic diagram of the analysis resolution of a corresponding first or second image according to one embodiment.

[0015] Figure 5 This is a schematic diagram of the analytical resolution curve of an image taken by a camera after the optical module has been calibrated, according to one embodiment.

[0016] Figure 6 This is a schematic diagram of a method for operating a photolithography system according to one embodiment.

[0017] To aid understanding, the same reference numerals have been used as much as possible to designate common elements in the figures. It has been conceived that elements disclosed in one embodiment may be beneficially incorporated into other embodiments without further description. Detailed Implementation

[0018] This disclosure relates to methods and apparatus for calibrating a lithography system. In one example, tilt correction, tip correction, and vertical correction are determined for the optical modules of the lithography system.

[0019] Figure 1 This is a schematic partial perspective view of a lithography system 100 according to one embodiment. The lithography system 100 includes a base frame 110, a plate 120, a stage 130, and a processing device 160. The base frame 110 rests on the floor of the production facility and supports the plate 120. A passive air isolator 112 is located between the base frame 110 and the plate 120. In one embodiment that can be combined with other embodiments, the plate 120 is a single piece of granite, and the stage 130 is disposed on the plate 120. A substrate 140 is supported by the stage 130. A plurality of openings are formed in the stage 130 to allow a plurality of lifting pins to extend therethrough. The lifting pins rise to extended positions to receive the substrate 140, such as a substrate from one or more transfer robots (not shown). One or more transfer robots are used to load and unload substrates, such as the substrate 140, from the stage 130.

[0020] Substrate 140 comprises any suitable material, such as quartz, for use as part of a flat panel display. Substrate 140 may be made of other materials. Substrate 140 has a photoresist layer formed thereon. The photoresist layer is sensitive to radiation. Positive photoresist includes portions of photoresist that, when exposed to radiation, are soluble in photoresist developer applied to the photoresist after the pattern is written into the photoresist. Negative photoresist includes portions of photoresist that, when exposed to radiation, are insoluble in photoresist developer applied to the photoresist after the pattern is written into the photoresist. The chemical composition of the photoresist determines whether it is a positive or negative photoresist. Examples of photoresists include, but are not limited to, at least one of diazonaphthoquinone, phenolic resin, poly(methyl methacrylate), poly(methylglutarimide), and / or SU-8. During processing using the photolithography system 100, patterns are formed on the processing surface 141 of the substrate 140 to form electronic circuits, such as those used in large-area flat panel display screens.

[0021] The lithography system 100 includes a pair of supports 122 and a pair of tracks 124. The supports 122 are disposed on a plate 120, and both the plate 120 and the supports 122 are made of a single piece of material. The tracks 124 support the supports 122, and a stage 130 moves along the tracks 124 in the X direction. In addition to the stage 130 shown, the lithography system 100 may include one or more additional stages. In one embodiment, which may be combined with other embodiments, the pair of tracks 124 are a pair of parallel magnetic channels. Each track 124 of the pair of tracks 124 is linear. In one embodiment, which may be combined with other embodiments, one or more tracks 124 are non-linear. An encoder 126 is coupled to the stage 130 to provide position information to a controller 101.

[0022] The processing apparatus 160 includes a support 162 and a processing unit 164. The support 162 is disposed on a plate 120 and includes an opening 166 for allowing a stage 130 to pass through below the processing unit 164. The processing unit 164 is supported by the support 162. In one embodiment, the processing unit 164 is a pattern generator configured to expose photoresist in a photolithography process. In one embodiment, which may be combined with other embodiments, the pattern generator is configured to perform a maskless photolithography process. The processing unit 164 includes a plurality of image projection devices 200 (in... Figure 2 and Figure 3 (As shown in the diagram). In one embodiment, which can be combined with other embodiments, the processing unit 164 includes up to 84 or more image projection devices. Each image projection device is disposed in a housing 165. The processing unit 160 can be used for maskless direct patterning.

[0023] During the operation of the lithography system 100, stage 130 moves from such a position in the X direction as... Figure 1 The loading position is moved to the processing position. The processing position includes one or more positions of the stage 130 when it passes below the processing unit 164. During operation, the stage 130 is raised and lowered by a plurality of air bearings, and the stage 130 moves from the loading position to the processing position along a pair of tracks 124. A plurality of vertically guiding air bearings are coupled to the stage 130 and positioned near the inner wall 128 of each support 122 to stabilize the movement of the stage 130. The stage 130 also moves in the Y direction by moving along track 150 to process and / or index substrate 140. The stage 130 is capable of operating independently and can scan substrate 140 in one direction and step in another direction.

[0024] The metrology system measures the X and Y lateral position coordinates of each stage 130 in real time, enabling each of the multiple image projection devices to precisely position the pattern written into the photoresist-covered substrate. The metrology system also provides real-time measurement of the angular position of each stage 130 around the vertical or Z-axis. Angular position measurement can be used to maintain a constant angular position during scanning using a servo mechanism. Angular position measurement can be used for... Figure 2 and Figure 3 The position of the pattern written on the substrate 140 by the image projection device 200 is corrected. In one embodiment, these techniques can be used in combination with other embodiments.

[0025] Figure 2 According to one embodiment, during bright field lighting operation... Figure 1 A three-dimensional schematic diagram of the image projection device 200 used in the lithography system 100 shown. The image projection device 200 is used as a corresponding... Figure 1 Each of a plurality of image projection devices in each housing 165 used in the illustrated lithography system 100. The image projection device 200 includes an optical module 201. The optical module 201 includes a housing 202.

[0026] The image projection device 200 directs a plurality of first beams 222 toward the reflective surface 204 of the first substrate 240. When the first beams 222 are directed toward the reflective surface 204, the first substrate 240 can move in the X and Y directions. The first substrate 240 includes a mirror. In one embodiment that can be combined with other embodiments, the reflective surface 204 is a continuous plane.

[0027] 100 pairs of photolithography systems were used. Figure 1 The substrate 140 shown is patterned. Figure 2The first substrate 240 shown is used to calibrate the photolithography system 100, for example, by adjusting the optical module 201 of the image projection device 200. Each image projection device 200 includes its own motor to control the tilt position, tip position, and vertical position of its respective optical module 201. The number of image projection devices 200 can be based on the size of the substrate 140 and / or the speed of the stage 130 (in... Figure 1 (As shown in the image) and changes.

[0028] Optical module 201 includes a light source 206, an aperture 208, a lens 210, a mirror 212, a digital mirror device (DMD) 214, a light dump 216, a camera 218, and a projection lens 220. The light source 206 includes a light-emitting diode (LED) or a laser. In one example, the light source 206 includes a broadband LED. The light source 206 is capable of generating a light beam with a predetermined wavelength. In one embodiment, which can be combined with other embodiments, the predetermined wavelength is in the blue or near-ultraviolet (UV) range, for example, 450 nm or less. The mirror 212 includes a spherical mirror. The camera 218 may include, for example, a CCD camera and / or a CMOS camera.

[0029] The projection lens 220 includes an objective lens such as a 10X objective lens. The DMD 214 includes multiple mirrors, and the number of mirrors in the DMD 214 can correspond to the resolution of the projected image.

[0030] During operation, light source 206 emits a first beam 222 having a predetermined wavelength (such as wavelengths in the blue range). The first beam 222 is reflected to DMD 214 using mirror 212. Mirrors of DMD 214 can be individually controlled, and each of the plurality of mirrors of DMD 214 can be set to an "on" or "off" position based on pattern data. Pattern data can be provided to DMD 214 using controller 101. When the first beam 222 reaches a mirror of DMD 214, the mirror in the "on" position reflects the first beam 222 to guide it through beam splitter 230 and into projection lens 220 for projection onto reflective surface 204. Projection lens 220 guides the first beam 222 to reflective surface 204 of first substrate 240. Mirrors in the "off" position reflect the first beam 222 to guide it to light collector 216 instead of reflective surface 204 of first substrate 240.

[0031] A first beam 222 is reflected from the reflecting surface 204 and guided as a reflected first beam 223 to the projection lens 220. The projection lens 220 converges the reflected first beam 223 and guides it to the beam splitter 230. The reflected first beam 223 is reflected from the beam splitter 230 and guided to the camera 218. The beam splitter 230 is oriented such that at least a portion of the beam projected from the DMD 214 to the beam splitter 230 passes through the beam splitter 230 and is projected onto the projection lens 220. The beam splitter 230 is oriented such that at least a portion of the beam projected from the projection lens 220 to the beam splitter 230 is reflected toward the camera 218.

[0032] Camera 218 captures multiple first images of an image plane projected onto reflective surface 204. The first images captured by camera 218 include a reflected first beam of light 223 reflected back from reflective surface 204. Camera 218 sends the multiple first images, including the reflected first beam of light 223, to controller 101.

[0033] When the first beam 222 is projected onto the reflective surface 204, the optical module 201 moves vertically, and the camera 218 captures a first image including the reflected first beam 223. In one embodiment, which can be combined with other embodiments, the optical module 201 moves vertically upward and / or downward relative to the first substrate 240 along the Z-axis. In one example, the optical module 201 moves at multiple vertical positions. In one embodiment, which can be combined with other embodiments, the first image captured by the camera 218 corresponds to multiple vertical positions of the optical module 201. In one embodiment, which can be combined with other embodiments, the optical module 201 is positioned at a tip position and an inclined position while the optical module 201 moves vertically and the camera 218 captures the first image.

[0034] The projection lens 220 is part of the first illumination source, which serves as a bright-field illumination source. The bright-field illumination source projects a first beam 223 onto the reflecting surface 204 within the field of view of the projection lens 220.

[0035] During calibration of the photolithography system 100 using the first substrate 240, the first substrate 240 is not patterned by the first beam 222. In one embodiment, which can be combined with other embodiments, the first substrate 240 does not include a photoresist layer formed thereon.

[0036] exist Figure 2In the illustrated embodiment, optical module 201 includes a spatial light modulator (SLM) as part of a bright-field illumination source. In the illustrated embodiment, the SLM includes a DMD 214. This disclosure contemplates the use of other SLMs and related aspects to replace one or more aspects of optical module 201 (e.g., replacing DMD 214 and / or light source 206). In one embodiment that can be combined with other embodiments, optical module 201 includes a microLED array, a VCSEL array, and / or an LCD array as part of a first illumination source serving as a bright-field illumination source. In one example, a microLED array, a VCSEL array, and / or an LCD array are used, and one or more of DMD 214, light source 206, aperture 208, lens 210, mirror 212, and / or light collector 216 are omitted.

[0037] Figure 3 According to one embodiment, during dark field illumination operation... Figure 1 A three-dimensional schematic diagram of the image projection device 200 used in the lithography system 100 shown.

[0038] The optical module 201 includes an illumination source 250 disposed below the projection lens 220. In one embodiment, which can be combined with other embodiments, the illumination source 250 is coupled to the projection lens 220 and disposed circumferentially around the projection lens 220.

[0039] Illumination source 250 directs a plurality of second beams 322 toward a patterned surface 304 of second substrate 340. The second beams 322 are directed toward the patterned surface 304 at an angle A1 relative to the patterned surface 304. The second substrate 340 is different from the first substrate 240 described above. For example, the patterned surface 304 is patterned using photolithography, deposition, and / or etching operations. The patterned surface 304 includes a plurality of structures 305 formed thereon to scatter the second beams 322. Illumination source 250 is a second illumination source. Illumination source 250 includes a dark-field illumination source that projects the second beams 322 toward the patterned surface 304 from a position disposed outside the field of view of projection lens 220.

[0040] Figure 3 The second substrate 340 shown is used to calibrate the photolithography system 100, for example by adjusting the optical module 201 of the image projection device 200.

[0041] In one example, the illumination source 250 includes a ring and a plurality of light emitters, such as LEDs and / or laser emitters, emitting a second beam 322. In one example, the illumination source 250 includes a broadband LED. The light source 250 is capable of generating a beam of light having a predetermined wavelength. In one embodiment, which can be combined with other embodiments, the predetermined wavelength is in the blue or near-ultraviolet (UV) range, for example, 450 nm or less.

[0042] In one embodiment that can be combined with other embodiments, the illumination source 250 includes a spatial light modulator (SLM). In one example, the illumination source 250 includes one or more of a digital mirror device (DMD), a microLED array, a VCSEL array, and / or an LCD array.

[0043] During operation, light source 250 emits a second beam 322 having a predetermined wavelength (such as wavelengths in the blue range). The second beam 322 is directed onto patterned surface 304. Structure 305 scatters the second beam 322, directing it as a scattered second beam 323 toward projection lens 220. Projection lens 220 converges the scattered second beam 323, and the second beam 323 is directed to beam splitter 230. The scattered second beam 323 is reflected from beam splitter 230 and directed toward camera 218. In one embodiment, which can be combined with other embodiments, the wavelength of the second beam 322 projected using a dark-field illumination source is approximately the same as the wavelength of the first beam 222 projected using a bright-field illumination source. In one example, the wavelength of the second beam 322 differs from the wavelength of the first beam 222 by less than 50 nm.

[0044] Camera 218 captures multiple second images of an image plane projected onto patterned surface 304. The second images captured by camera 218 include a scattered second beam of light 323 that scatters away from patterned surface 304. Camera 218 sends the multiple second images, including the scattered second beam of light 323, to controller 101.

[0045] In one embodiment that can be combined with other embodiments, the reflected first beam 223 is a reflected bright field beam, while the scattered second beam 323 is a scattered dark field beam.

[0046] When the second beam 322 is projected onto the patterned surface 304, the optical module 201 moves vertically, and the camera 218 captures a second image including the scattered second beam 323. In one embodiment, which can be combined with other embodiments, the optical module 201 moves vertically upward and / or downward relative to the second substrate 340 along the Z-axis. In one example, the optical module 201 moves at multiple vertical positions. In one embodiment, which can be combined with other embodiments, the second image captured by the camera 218 corresponds to multiple vertical positions of the optical module 201. In one embodiment, which can be combined with other embodiments, the optical module 201 is positioned at a tip position and an inclined position while the optical module 201 moves vertically and the camera 218 captures the second image.

[0047] During the calibration of the photolithography system 100 using the second substrate 340, the second substrate 340 is not patterned by the second beam 322.

[0048] Controller 101 communicates with and is configured to control various aspects of the lithography system 100. In one example, controller 101 communicates with and is configured to control the optical module 201 and its corresponding motors, camera 218, DMD 214, light source 206, and / or illumination source 250. In one example, controller 101 is configured to adjust the tilt position, tip position, and vertical position of the optical module 205. The tilt position is the angular position of the optical module 205 about the X-axis. The tip position is the angular position of the optical module 205 about the Y-axis. The vertical position is the lateral position of the optical module 205 along the Z-axis. In one embodiment, which can be combined with other embodiments, each of the X-axis, Y-axis, and Z-axis extends through the center of the corresponding optical module 205.

[0049] Controller 101 receives multiple first images from camera 218, including reflected first beams 223. The first images correspond to multiple vertical positions of optical module 205. For each first image, controller 101 processes the outer regions (e.g., corner regions) of the respective image and analyzes the resolution of each outer region. In one example, the corner regions of the analyzed first image include a top-left corner region, a top-right corner region, a bottom-left corner region, and a bottom-right corner region. Resolution indicates the number of pixels, focus level, and / or the amount of luminous area in each corner region as identified by controller 101 or camera 218. In one embodiment, which can be combined with other embodiments, pixels correspond to reflected first beams 223 appearing in the corresponding corner region of the respective first image. In one embodiment, which can be combined with other embodiments, resolution indicates the measured light intensity in each corner region. The resolution of each outer region is analyzed for each first image (e.g., for each vertical position), and an optimal first image is determined for each outer region. For each outer region, the optimal first image is the first image and the corresponding vertical position where the respective corner region has the highest resolution. In one example, the highest resolution is the optimal focus level with the best sharpness, the maximum measured light intensity, the largest luminous area identified by controller 101 and / or camera 218, and / or the largest number of pixels. A first image is determined as optimal for each of the upper left, upper right, lower left, and lower right regions.

[0050] Using the optimal first image for each outer region, controller 101 determines the optimal brightfield tilt, optimal brightfield tip, and optimal brightfield vertical position. The optimal brightfield vertical position is determined by using the corresponding vertical position of the optimal first image for the corner region and calculating the average of the corresponding vertical positions. The first and second images each include a first image length extending along the left and right sides in the image plane and a second image length extending along the top and bottom.

[0051] As shown in Equation 1 below, the optimal bright field tilt is determined by calculating the first bright field difference D1 divided by the sine of the first image length L1. BF ).

[0052] Tilt BF =sin(D1 / L1) (Equation 1)

[0053] In one example, the first brightness difference D1 is determined by subtracting the corresponding vertical position of the best first image at the bottom left from the corresponding vertical position of the best first image at the top left. In another example, the first brightness difference D1 is determined by subtracting the corresponding vertical position of the best first image at the bottom right from the corresponding vertical position of the best first image at the top right.

[0054] As shown in Equation 2 below, the optimal brightfield tip is determined by calculating the second brightfield difference D2 divided by the sine of the second image length L2. BF ).

[0055] Tip BF =sin(D² / L²) (Equation 2)

[0056] In one example, the second brightness difference D2 is determined by subtracting the corresponding vertical position of the best first image at the top right corner from the corresponding vertical position of the best first image at the top left corner. In another example, the second brightness difference D2 is determined by subtracting the corresponding vertical position of the best first image at the top right corner from the corresponding vertical position of the best first image at the bottom left corner.

[0057] Controller 101 receives multiple second images from camera 218, including a scattered second beam of light 323. The second images correspond to multiple vertical positions of optical module 205. For each second image, controller 101 processes the outer regions (e.g., corner regions) of the respective image and analyzes the resolution of each corner region. In one example, the corner regions of the analyzed second image include an upper-left corner region, an upper-right corner region, a lower-left corner region, and a lower-right corner region. Resolution indicates the number of pixels, focus level, and / or the amount of luminous area in each corner region as identified by controller 101 or camera 218. In one embodiment, which can be combined with other embodiments, pixels correspond to the scattered second beam of light 323 appearing in the corresponding outer region of the respective second image. In one embodiment, which can be combined with other embodiments, resolution indicates the measured light intensity in each corner region. The resolution of each outer region is analyzed for each second image (e.g., for each vertical position), and an optimal second image is determined for each outer region. For each outer region, the optimal second image is the second image and the corresponding vertical position where the respective outer region has the highest resolution. In one example, the highest resolution is the optimal focus level with the best sharpness, the maximum measured light intensity, the largest luminous area identified by controller 101 and / or camera 218, and / or the largest number of pixels. A best second image is determined for each of the upper left, upper right, lower left, and lower right regions.

[0058] Using the optimal second image for each outer region, controller 101 determines the optimal dark field tilt, optimal dark field tip, and optimal dark field vertical position. The optimal dark field vertical position is determined by using the corresponding vertical position of the optimal second image for the corner region and calculating the average of the corresponding vertical positions.

[0059] As shown in Equation 3 below, the optimal dark field tilt is determined by calculating the first dark field difference D3 divided by the sine of the first image length L1. DF ).

[0060] Tilt DF =sin(D3 / L1) (Equation 3)

[0061] In one example, the first dark field difference D3 is determined by subtracting the corresponding vertical position of the best second image at the bottom left from the corresponding vertical position of the best second image at the top left. In another example, the first dark field difference D3 is determined by subtracting the corresponding vertical position of the best second image at the top right from the corresponding vertical position of the best second image at the bottom right.

[0062] As shown in Equation 4 below, the optimal dark tip is determined by calculating the second dark difference D4 divided by the sine of the second image length L2. DF ).

[0063] Tip DF =sin(D⁴ / L²) (Equation 4)

[0064] In one example, the second dark field difference D4 is determined by subtracting the corresponding vertical position of the best second image at the top right from the corresponding vertical position of the best second image at the top left. In another example, the second dark field difference D4 is determined by subtracting the corresponding vertical position of the best second image at the bottom right from the corresponding vertical position of the best second image at the bottom left.

[0065] In one embodiment that can be combined with other embodiments, the best first image is the best bright-field image, and the best second image is the best dark-field image.

[0066] The controller 101 then determines the tip correction, tilt correction, and optimal vertical position of the optical module 205. As shown in Equation 5 below, this is achieved by adjusting the optimal brightfield tilt (Tilt... BF Multiply by 2.0 to determine the tilt, and select the optimal dark field tilt (Tilt). DF Subtracting the tilt value from the original value will determine the tilt correction (X):

[0067] X = Tilt DF –(2*Tilt BF (Equation 5)

[0068] As shown in Equation 6 below, by using the optimal bright field tip (Tip) BF Multiply by 2.0 to determine the tip value, and select the optimal dark field tip (Tip). DF The tip value is subtracted from the original value to determine the tip correction (Y).

[0069] Y = Tip DF –(2*Tip BF (Equation 6)

[0070] As shown in Equation 7 below, by using the optimal bright field vertical position (Z) BF Multiply by a coefficient of 2.0 to determine the vertical value, and subtract the optimal dark field vertical position (Z) from the vertical value. DF This determines the optimal vertical position (Z). L ):

[0071] Z L =(2*Z) BF )–Z DF (Equation 7)

[0072] The controller 101 instructs the motor to use tilt correction (X) to adjust the tilt position of the optical module 205 (the tilt position used during the capture of the first and second images) to the corrected tilt position. The corrected tilt position is the corrected angular position of the optical module 205 about the X-axis after the tilt correction is applied to the tilt position.

[0073] In one embodiment that can be combined with other embodiments, each of tilt correction (X) and tip correction (Y) includes an angle value, and the optimal vertical position (Z) L This includes translation values.

[0074] The controller 101 instructs the motor to use tip correction (Y) to adjust the tip position of the optical module 205 (the tip position used during the capture of the first and second images) to the corrected tip position. The corrected tip position is the angular position of the optical module 205 about the Y-axis after tip correction is applied to the tip position.

[0075] Controller 101 instructs the motor to use the optimal vertical position (Z). L The vertical position of the optical module 205 is adjusted to the corrected vertical position. The corrected vertical position is approximately equal to the optimal vertical position along the Z-axis (Z...). L ).

[0076] After adjusting to the corrected tilt position, corrected tip position, and corrected vertical position, the optical module 205 is used to perform photolithography on the substrate (e.g., Figure 1 The substrate 140 shown is patterned.

[0077] Controller 101 includes a processor 181, such as a central processing unit (CPU), a memory 182, and support circuitry 183 for the processor 181. Controller 180 can be one of any form of general-purpose computer that can be used in an industrial environment to control various lithography system components and subprocessors. Memory 182 stores software (source code or object code), such as computer programs, which can be executed or invoked to control the overall operation of lithography system 100 and / or optical module 205 in the manner described herein.

[0078] The controller 101 includes a non-transitory computer-readable medium (e.g., memory 182) comprising instructions (e.g., software) that, when executed (e.g., by the processor 181), cause one or more operations described herein to be performed. In one embodiment, which may be combined with other embodiments, the instructions, when executed, cause the performance of operations targeting… Figures 1 to 6 One or more operations are described. In one embodiment, which may be combined with other embodiments, instructions on a non-transitory computer-readable medium of controller 101, when executed, cause one or more operations of method 600 to be performed. In one example, the instructions cause one or more of operations 601-621 to be performed relative to lithography system 100 and / or optical module 205 and / or aspects and / or components thereof.

[0079] The aspects described herein facilitate the projection of light onto a substrate at an image plane substantially parallel to the surface of the substrate to be patterned (to pattern the substrate during photolithography operations). The aspects described herein also facilitate the projection of light onto the substrate at an image plane within the focal point substantially across the entire image plane. As an example, adjusting the optical module to a corrected tip position, a corrected tilt position, and a corrected vertical position facilitates the adjustment of optical module 205 such that the imaging plane of optical module 205 is focused and parallel to the substrate being patterned on the projected image plane. The aspects described herein facilitate the simple, rapid, and efficient calibration of the tilt, tip, and vertical positions of optical module 205. As an example, the aspects described herein facilitate the simple calibration of the optical module 205 of the photolithography system 105 using the same optical module 205 used for patterning the substrate. Calibration can be performed rapidly, for example, in 10 minutes or less.

[0080] Calibrating the optical module 205 using tip correction, tilt correction, and optimal vertical positioning can also resolve structural defects in the optical module 205, such as speckling on the lenses of the optical module. Calibrating the optical module 205 can also resolve positional defects in the optical module 205, such as misalignment of certain components. Using the aspects described herein to calibrate the optical module 205 also facilitates efficient and accurate patterning of the substrate with reduced speckling, thereby promoting increased production volume, reduced machine downtime, reduced production time, and reduced operating costs.

[0081] Figure 4A It is based on one implementation method. Figure 2 and Figure 3 The diagram shows a schematic partial view of an image 400 captured by camera 218. Image 400 includes a first image length L1 and a second image length L2 in an image plane. Image 400 may be an example of one of a plurality of first images including a reflected first beam of light 223. Image 400 may be an example of one of a plurality of second images including a scattered second beam of light 323. Image 400 includes a plurality of image features 410 (e.g., pixels). In one example, when analyzing a first image, image feature 410 corresponds to the reflected first beam of light 223 appearing within the corresponding image 400. In one example, when analyzing a second image, image feature 410 corresponds to the scattered second beam of light 323 appearing within the corresponding image 400.

[0082] Image 400 includes processed and analyzed corner regions 412A-412D (top left corner region 412A, top right corner region 412B, bottom left corner region 412C, and bottom right corner region 412D). The resolution of each corner region 412A-412D is analyzed. In one example, the resolution of each corner region 412A-412D includes the number (e.g., pixels) of image features 410A-410D appearing within the respective corner region 412A-412D. In one example, the resolution of each corner region 412A-412D includes the measured light intensity of light appearing within each corner region 412A-412D.

[0083] Figure 4BFigure 450 is a schematic diagram of the analytical resolution of a corresponding first or second image according to one embodiment. The Y-axis of graph 450 represents the resolution of each corner region 412A-412D of each first or second image. In one example, the resolution is the number of image features (e.g., pixels) appearing within each corner region 412A-412D. In another example, the resolution is the light intensity measured within each corner region 412A-412D. The X-axis of graph 450 represents the image number of each first or second image. The image number on the X-axis corresponds to the corresponding vertical position of optical module 205 at which camera 218 captured an image. The resolution across the first or second image is mapped for each corner region 412A-412D and displayed in graph 450. Peaks 460A-460D are shown in graph 450 for each corner region 412A-412D. The peaks 460A-460D of each corresponding corner region 412A-412D correspond to the image number (and corresponding vertical position) with the highest resolution for that corner region 412A-412D. The image number (and corresponding vertical position) indicates the best first image (if the first image was analyzed) or the best second image (if the second image was analyzed) for each corresponding corner region 412A-412D.

[0084] Figure 5 This is a schematic diagram of the analytical resolution curve of an image 550 captured by a camera 218 after correcting the optical module 205, according to one embodiment. After correcting the tilt position of the optical module 205 to a corrected tilt position using tilt correction, and after correcting the tip position to a corrected tip position using tip correction, an image mapped in the graph 550 is captured. The resolution of each corner region 512A-512D is mapped in the graph 550. Figure 4B Compared to the corner regions 412A-412D shown, the resolution of corner regions 512A-512D is more aligned in image number (and corresponding vertical position). The resolution peaks 560A-560D of each corner region 412A-412D are aligned and appear in the same image number (and corresponding vertical position) to facilitate accurate patterning and focusing on a parallel image plane. After tip and tilt correction, the resolution peaks 560A-560D are also higher than those shown. Figure 4B The peaks 460A-460D shown are high. Graph 550 is exemplary.

[0085] Figure 6This is a schematic diagram of a method 600 for operating a photolithography system according to one embodiment. In operation 601, method 600 includes guiding a first light beam to a reflective surface of a first substrate using a digital mirror device of an optical module. Operation 603 includes collecting the first light beam reflected from the reflective surface of the first substrate, passing at least through an objective lens of the optical module. Operation 605 includes guiding the first light beam, at least through the objective lens, to a camera of the optical module using a beam splitter of the optical module. Operation 607 includes capturing multiple first images of the first light beam guided to the camera using the camera. Operation 609 includes guiding a second light beam at an oblique angle to a patterned surface of a second substrate using an illumination source positioned below the objective lens. Operation 611 includes collecting the second light beam scattered away from the patterned surface by at least the objective lens. Operation 613 includes guiding the second light beam, at least through the objective lens, to the camera using a beam splitter. Operation 615 includes capturing multiple second images of the second light beam guided to the camera using the camera.

[0086] Operation 617 includes determining the tip alignment, tilt alignment, and optimal vertical position of the optical module. Operation 619 includes adjusting the tip position of the optical module to the aligned tip position using tip alignment, and adjusting the tilt position of the optical module to the aligned tilt position using tilt alignment. Operation 619 also includes adjusting the vertical position of the optical module to the aligned vertical position using the optimal vertical position.

[0087] In one embodiment that can be combined with other embodiments, the first beam is a bright-field beam and the second beam is a dark-field beam. In one embodiment that can be combined with other embodiments, the first image is a bright-field image and the second image is a dark-field image. In one embodiment that can be combined with other embodiments, the objective lens is at least a portion of a bright-field illumination source, and the illumination source is at least a portion of a dark-field illumination source. In one embodiment that can be combined with other embodiments, the first substrate and the second substrate are test substrates.

[0088] Operation 621 includes patterning one or more production substrates using a photolithography system with the optical module calibrated to a calibrated tip position, a calibrated tilt position, and a calibrated vertical position.

[0089] The benefits of this disclosure include: rapid and efficient correction of the tip position, tilt position, and vertical position of the optical module; simple correction of the optical module and reduced resource consumption; correction of defects in the optical module; projection of light onto an image plane parallel to the substrate; projection of light onto a focused image plane; accurate patterning of the substrate; reduction of speckles on the patterned substrate; increased production capacity; reduced production time; reduced machine downtime; and reduced operating costs.

[0090] The aspects of this disclosure include a lithography system 100; an optical module 205; a camera 218; a first substrate 240; a second substrate 340; a first light beam 223; a reflected first light beam 223; a second light beam 322; a scattered second light beam 323; a controller 101; a first image; a second image; corner regions 412A-412D of image 400; and a method 600. It is contemplated that one or more aspects disclosed herein may be combined. Furthermore, it is contemplated that one or more aspects disclosed herein may include some or all of the foregoing benefits.

[0091] While the foregoing relates to specific embodiments of this disclosure, other and further embodiments of the disclosure may be conceived without departing from the basic scope of the foregoing. This disclosure is also contemplated that one or more aspects of the specific embodiments described herein may replace one or more other aspects described. The scope of this disclosure is defined by the appended claims.

Claims

1. A method for operating a photolithography system, comprising the following steps: The spatial light modulator of the optical module guides the first beam to the reflective surface of the first substrate; Collect the first beam of light reflected from the reflective surface that has passed at least through the objective lens of the optical module; The beam splitter of the optical module is used to guide the first beam collected at least through the objective lens to the camera of the optical module; The camera is used to capture a plurality of first images of the first beam of light directed to the camera. The second beam is directed at an angle to the patterned surface of the second substrate using an illumination source positioned below the objective lens; Collect at least the second beam of light that has been scattered away from the patterned surface by the objective lens; The beam splitter is used to guide the second beam, which is at least collected by the objective lens, to the camera. The camera is used to capture multiple second images of the second beam directed at the camera; and Determine the tip correction, tilt correction, and optimal vertical position of the optical module. The determination of the tip correction, tilt correction, and optimal vertical position of the optical module includes processing the outer regions of the plurality of first images and the outer regions of the plurality of second images, wherein the processing steps include the following steps: Analyze the resolution of each outer region of the plurality of first images; Determine the optimal first image for each outer region of the plurality of first images, wherein the optimal first image includes the highest resolution of each outer region of the plurality of first images; Analyze the resolution of each outer region of the plurality of second images; and Determine the optimal second image for each outer region of the plurality of second images, wherein the optimal second image comprises the highest resolution of each outer region of the plurality of second images.

2. The method of claim 1, wherein the plurality of first images are captured while the optical module is moved vertically relative to the first substrate, the plurality of first images corresponding to a plurality of vertical positions of the optical module.

3. The method of claim 2, wherein the plurality of second images are captured while the optical module is moved vertically relative to the second substrate, the plurality of second images corresponding to a plurality of vertical positions of the optical module.

4. The method of claim 1, wherein the first substrate includes a mirror, and the patterned surface of the second substrate includes a plurality of structures formed thereon to scatter the second light beam away from the second substrate.

5. The method of claim 1, wherein the outer regions of the plurality of first images are corner regions, and the outer regions of the plurality of second images are corner regions.

6. The method of claim 1, further comprising the following steps: The tip correction is used to adjust the tip position of the optical module; The tilt correction is used to adjust the tilt position of the optical module; and Adjust the vertical position of the optical module using the optimal vertical position.

7. A non-transitory computer-readable medium comprising instructions that, when executed, cause a photolithography system to perform the following operations: The spatial light modulator of the optical module guides the first beam to the reflective surface of the first substrate; Collect the first beam of light reflected from the reflective surface that has passed at least through the objective lens of the optical module; The beam splitter of the optical module is used to guide the first beam collected at least through the objective lens to the camera of the optical module; The camera is used to capture a plurality of first images of the first beam of light directed to the camera. The second beam is directed at an angle to the patterned surface of the second substrate using an illumination source positioned below the objective lens; Collect at least the second beam of light that has been scattered away from the patterned surface by the objective lens; The beam splitter is used to guide the second beam, which is at least collected by the objective lens, to the camera. The camera is used to capture multiple second images of the second beam directed at the camera; and Determine the tip correction, tilt correction, and optimal vertical position of the optical module. The determination of the tip correction, tilt correction, and optimal vertical position of the optical module includes processing the outer regions of the plurality of first images and the outer regions of the plurality of second images, wherein the processing steps include the following steps: Analyze the resolution of each outer region of the plurality of first images; Determine the optimal first image for each outer region of the plurality of first images, wherein the optimal first image includes the highest resolution of each outer region of the plurality of first images; Analyze the resolution of each outer region of the plurality of second images; and Determine the optimal second image for each outer region of the plurality of second images, wherein the optimal second image comprises the highest resolution of each outer region of the plurality of second images.

8. The non-transitory computer-readable medium of claim 7, wherein the plurality of first images are captured while the optical module is moved vertically relative to the first substrate, the plurality of first images corresponding to a plurality of vertical positions of the optical module.

9. The non-transitory computer-readable medium of claim 8, wherein the plurality of second images are captured while the optical module is moved vertically relative to the second substrate, the plurality of second images corresponding to a plurality of vertical positions of the optical module.

10. The non-transitory computer-readable medium of claim 7, wherein the first substrate includes a mirror, and the patterned surface of the second substrate includes a plurality of structures formed thereon to scatter the second light beam away from the second substrate.

11. The non-transitory computer-readable medium of claim 7, wherein the outer regions of the plurality of first images are corner regions, and the outer regions of the plurality of second images are corner regions.

12. The non-transitory computer-readable medium of claim 7, wherein the instructions, when executed, further cause the lithography system to: The tip correction is used to adjust the tip position of the optical module; The tilt correction is used to adjust the tilt position of the optical module; and Adjust the vertical position of the optical module using the optimal vertical position.

13. A non-transitory computer-readable medium comprising instructions that, when executed, cause a photolithography system to perform the following operations: A bright field beam is directed to the reflective surface of the first substrate using a spatial light modulator of an optical module. The camera using the optical module captures multiple bright-field images of the reflected bright-field beam that exits from the reflective surface. The dark field beam is directed to the patterned surface of the second substrate; The camera captures multiple dark-field images of scattered dark-field beams scattering away from the patterned surface; and Determine the tip correction, tilt correction, and optimal vertical position of the optical module; The determination of the tip correction, tilt correction, and optimal vertical position of the optical module includes processing the outer regions of the plurality of bright-field images and the outer regions of the plurality of dark-field images, wherein the processing steps include the following steps: Analyze the resolution of each outer region of the multiple bright-field images; Determine the optimal bright-field image for each outer region of the plurality of bright-field images, wherein the optimal bright-field image comprises the highest resolution of each outer region of the plurality of bright-field images; Analyze the resolution of each outer region of the plurality of dark field images; and Determine the optimal dark field image for each outer region of the plurality of dark field images, wherein the optimal dark field image comprises the highest resolution of each outer region of the plurality of dark field images.

14. The non-transitory computer-readable medium of claim 13, wherein the outer regions of the plurality of bright-field images are corner regions, and the outer regions of the plurality of dark-field images are corner regions.

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