System, method and storage medium for manufacturing a diffraction grating

Abstract

This application provides a fabrication system, method, and storage medium for a diffraction grating. The fabrication system includes a stage, a substrate disposed on the stage, and an optical system for forming write spots on the substrate surface. The optical system comprises, sequentially along an optical axis: a light source located in an incident light path extending in a first direction; a mask located in the incident light path, the mask being rotatable around the optical axis and having multiple equally spaced apertures; and a projection component located in a write light path connected to the incident light path and extending in a second direction. The projection component is configured to project the multiple apertures onto the substrate surface to form multiple write spots corresponding one-to-one with the apertures. This fabrication system can significantly improve photolithography efficiency, and by rotating the mask, the spacing between adjacent write spots on the substrate can be infinitely adjusted, achieving precise adjustment of the grating pitch.

Description

Technical Field

[0001] This invention relates to the field of photolithography, and in particular to a system, method and storage medium for fabricating diffraction gratings. Background Technology

[0002] As an important type of optical device, diffraction gratings have wide applications in beam splitting, beam combining, deflection, waveguide imaging, metrology, etc., and are involved in many fields such as spectroscopy, laser processing, motion control, optical communication, and augmented reality display, and have important application value.

[0003] The fabrication of diffraction gratings mainly includes the scribing method, the holographic method, and the direct-write lithography method. The scribing method uses a diamond tool to directly and mechanically scribble the grating lines onto the substrate one by one. This method not only requires high precision in the scribing equipment but also has extremely strict environmental requirements, such as temperature, humidity, and vibration. The holographic method utilizes the principle of laser interference, establishing a holographic interference optical path on an optically isolated platform. The substrate has photosensitive properties or its surface is coated with a photosensitive material. The holographic interference light field exposes the photosensitive material in a single exposure, and after necessary subsequent processing, a periodic grating structure is formed. This method requires strict control of process stability, especially for large-format exposures. High-precision diffraction grating interference fabrication also places correspondingly high demands on the precision of the optical components in the interference optical path to form a more ideal interference beam wavefront; direct-write... Photolithography, including laser direct-write lithography and electron beam direct-write lithography, also belongs to the photosensitive principle. Its basic approach falls into two main categories: one is similar to scribing, where the light spot acts as a cutting tool, drawing lines on the substrate surface for photosensitive exposure. The problem is its low fabrication efficiency. The other is arbitrary patterning lithography, where the grating stripes are designed as computer graphics files, which are then digitized and lithographically copied. This method offers advantages such as high flexibility, high lithography efficiency, and minimal area limitations. However, it suffers from complex error issues, involving errors in computer file definition, pixel errors in digitization, and exposure field stitching errors during equipment operation. Therefore, current general-purpose patterning lithography methods are unsuitable for fabricating high-precision diffraction gratings and have limited applications.

[0004] Given the application value of diffraction gratings and the characteristics and limitations of the aforementioned basic methods, providing a new method for fabricating diffraction gratings with advantages such as high efficiency, large format, high precision, and flexible control is an urgent problem to be solved. Summary of the Invention

[0005] Based on this, the present invention aims to provide an improved system, method and storage medium for fabricating diffraction gratings to solve at least one of the above problems.

[0006] In a first aspect, this application provides a system for fabricating a diffraction grating, including a workpiece stage, a substrate disposed on the workpiece stage, and an optical system for forming a writing spot on the surface of the substrate, wherein the optical system comprises, sequentially along the optical axis:

[0007] The light source is located in the incident light path extending along the first direction;

[0008] A photomask is located in the incident light path, and the photomask is rotatable around the optical axis and has multiple light holes at equal intervals.

[0009] A projection component is located in a write optical path that is connected to the incident optical path and extends along a second direction. The projection component is configured to project the plurality of optical holes onto the substrate surface to form a plurality of write optical spots that correspond one-to-one with the optical holes.

[0010] The above system has at least the following beneficial effects:

[0011] 1. Multiple writing spots are obtained by projecting multiple apertures on the photomask, and then combined with the movement of the workpiece stage, which is conducive to the parallel scanning of multiple writing spots, thereby multiplying the photolithography efficiency.

[0012] 2. By introducing a mask that can rotate around the optical axis into the direct-write lithography optical system and controlling the rotation angle, it is beneficial to achieve stepless adjustment of the spacing between adjacent write spots on the substrate, thereby achieving precise adjustment of the grating pitch and avoiding the problem of discontinuous digital adjustment in conventional direct-write lithography.

[0013] In one embodiment, the fabrication system further includes: a first adjustment mechanism coupled to the mask and configured to drive the mask to rotate about the optical axis to change the distance between two adjacent write spots; wherein, when the first adjustment mechanism drives the mask to rotate about the optical axis by a first angle θ, the distance L1 between two adjacent write spots changes to Where a represents the distance between two adjacent apertures, and m represents the scaling factor.

[0014] In one embodiment, the fabrication system further includes: a workpiece stage driving mechanism coupled to the workpiece stage and configured to drive the workpiece stage to move continuously along a third direction and to move in steps along a fourth direction by a preset amount of movement; wherein the third direction is perpendicular to the arrangement direction of the writing spot, and the fourth direction is parallel to the arrangement direction of the writing spot.

[0015] In one embodiment, when the number of light apertures is n, the preset movement amount is... Where p is any integer from 1 to n.

[0016] In one embodiment, the optical system further includes a reflector configured to reflect light emitted through the plurality of apertures and redirect it to the write optical path; the projection assembly includes: a tube lens located in the write optical path, near the reflector; an objective lens located in the write optical path, near the substrate; and a flat glass plate located in the write optical path and disposed between the tube lens and the objective lens, the flat glass plate being rotatable relative to a first reference plane to compensate for positional errors of the substrate; wherein the first reference plane passes through the center of the flat glass plate and is perpendicular to the optical axis.

[0017] In one embodiment, the fabrication system further includes a second adjustment mechanism coupled to the flat glass and configured to drive the flat glass to rotate relative to the first reference surface.

[0018] In one embodiment, the fabrication system further includes: a linear polarization control component located in the incident light path and disposed between the light source and the mask; wherein, when the light source is a linearly polarized light source, the linear polarization control component includes a half-wave plate rotatable about the optical axis; when the light source is a non-linearly polarized light source, the linear polarization control component includes a linear polarizer rotatable about the optical axis.

[0019] Secondly, this application provides a method for fabricating a diffraction grating, comprising:

[0020] An initial optical system and a photomask are provided; wherein, the initial optical system includes a light source and a projection component arranged sequentially along the optical axis, and the photomask has multiple light holes at equal intervals;

[0021] Place the substrate on the workpiece stage;

[0022] The mask is placed between the light source and the projection component of the initial optical system to form a target optical system; wherein the target optical system is configured to project the plurality of apertures onto the substrate surface to form a plurality of write spots corresponding one-to-one with the apertures, and when the mask rotates around the optical axis, the distance between two adjacent write spots changes synchronously.

[0023] The workpiece stage is controlled to move relative to the writing spot, so that the writing spot scans and exposes the substrate to form a grating pattern with a preset grating pitch.

[0024] The above method, on the one hand, can obtain multiple writing spots by projecting multiple apertures on the photomask, and then, in conjunction with the movement of the workpiece stage, achieve parallel scanning of multiple writing spots, thereby multiplying the photolithography efficiency; on the other hand, by rotating the photomask and controlling the rotation angle of the photomask, the stepless adjustment of the spacing between adjacent writing spots on the substrate can be achieved, thereby achieving the purpose of precisely adjusting the grating pitch.

[0025] In one embodiment, when the mask rotates about the optical axis by a first angle θ, the distance L1 between two adjacent write spots changes to... Where a represents the distance between two adjacent apertures, and m represents the scaling factor.

[0026] In one embodiment, controlling the movement of the workpiece stage relative to the writing spot includes: driving the workpiece stage to move continuously along a third direction and stepping along a fourth direction by a preset amount of movement; wherein the third direction is perpendicular to the arrangement direction of the writing spot, the fourth direction is parallel to the arrangement direction of the writing spot, and when the number of apertures is n, the preset amount of movement is... Where p is any integer from 1 to n.

[0027] In one embodiment, the projection assembly includes a tube lens, an objective lens, and a flat glass plate disposed between the tube lens and the objective lens. The flat glass plate has a first reference plane passing through the center of the flat glass plate and perpendicular to the optical axis. When the substrate has a positional error, the method further includes: driving the flat glass plate to rotate relative to the first reference plane, so that the writing spot moves along the offset direction of the substrate to compensate for the positional error of the substrate.

[0028] In one embodiment, the substrate has a second reference plane passing through the center of the substrate and perpendicular to the optical axis. When the substrate has a rotational attitude error relative to the second reference plane, the method further includes: driving the mask to rotate around the optical axis to reduce the distance between two adjacent light spots on the substrate and compensate for the rotational attitude error of the substrate relative to the second reference plane.

[0029] In one embodiment, the projection assembly includes a tube lens, an objective lens, and a flat glass plate disposed between the tube lens and the objective lens. The flat glass plate has a first reference plane passing through the center of the flat glass plate and perpendicular to the optical axis. The substrate has a reference axis parallel to the optical axis. When the substrate has a deflection attitude error about the reference axis, the method further includes: driving the mask plate to rotate about the optical axis to increase the distance between two adjacent light spots on the substrate, and then rotating the flat glass plate relative to the first reference plane during the writing light spot scanning exposure process so that the scanning direction of the writing light spot is parallel to the side of the substrate to compensate for the deflection attitude error of the substrate about the reference axis.

[0030] Thirdly, this application provides a computer-readable storage medium storing a computer program that, when executed, implements the steps of the method described in any of the preceding embodiments. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of this specification or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this specification. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the composition of a preparation system according to an embodiment of this application;

[0033] Figure 2 This is a schematic diagram of the operation of a preparation system according to an embodiment of this application;

[0034] Figure 3 This is a schematic diagram showing the change in projection spacing when the mask template is rotated in the fabrication system according to an embodiment of this application;

[0035] Figure 4 This is a schematic diagram of the step movement amount according to an embodiment of this application;

[0036] Figure 5 This is a schematic diagram of the step movement amount according to another embodiment of this application;

[0037] Figure 6 A schematic diagram of the composition of a preparation system according to another embodiment of this application;

[0038] Figure 7 This is a schematic diagram of an error compensation method according to an embodiment of this application;

[0039] Figure 8 This is a flowchart illustrating the steps of a method for fabricating a diffraction grating according to an embodiment of this application.

[0040] Figure 9 This is a schematic diagram of attitude error according to an embodiment of this application;

[0041] Figure 10 This is a schematic diagram of attitude error according to another embodiment of this application;

[0042] Figure 11 This is a schematic diagram of a diffraction grating pattern according to an embodiment of this application;

[0043] Figure 12 This is a schematic diagram of a diffraction grating pattern according to another embodiment of this application. Detailed Implementation

[0044] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0045] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0046] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0047] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0048] Fabricating diffraction gratings using conventional direct-write lithography has always been a challenge, primarily due to the additional diffraction orders within the fabricated grating causing diffraction efficiency that falls short of expectations or even renders it unusable. In addressing these issues, the inventors identified two main reasons:

[0049] 1. Digital quantization of the pattern in the direct-write lithography system will produce pixel errors, resulting in uneven grating pitch;

[0050] 2. Errors in the position and orientation of the workpiece stage movement can also cause discrepancies between the fabricated grating and the designed graphic.

[0051] Therefore, solving the pixel discreteness problem in diffraction grating fabrication and the pattern deviation problem caused by stage running error will effectively solve the problem of direct-write lithography fabrication of diffraction gratings, give full play to the advantages of the flexibility and controllability of the direct-write lithography method, and become a technical solution that combines efficiency and precision, with practical application value.

[0052] Based on this, this application provides an improved system for fabricating diffraction gratings. On the one hand, multiple writing spots are obtained by projecting multiple apertures on a mask, and with the movement of the workpiece stage, parallel scanning of multiple writing spots is facilitated, thereby significantly improving lithography efficiency. On the other hand, by introducing a mask that can rotate around the optical axis into the direct-write lithography optical system and controlling the rotation angle, stepless adjustment of the spacing between adjacent writing spots on the substrate is achieved, enabling precise adjustment of the grating pitch and avoiding the problem of discontinuous digital adjustment in conventional direct-write lithography methods. Thus, an effective comprehensive solution can be formed from the aspects of writing spot generation method and error compensation mechanism, realizing a more applicable diffraction grating fabrication technology.

[0053] like Figure 1 and Figure 2 As shown in the figure, this application provides a diffraction grating fabrication system 10, including a workpiece stage 160, a substrate 150 disposed on the workpiece stage 160, and an optical system for forming a writing spot on the surface of the substrate 150. It should be noted that the schematic diagram simplifies the necessary auxiliary optical paths for visual recognition, focusing detection, etc., but should not be considered as... Figure 1 and Figure 2 These necessary auxiliary optical paths were eliminated.

[0054] The optical system includes, in sequence along the optical axis: a light source 110 located in the incident light path extending in the first direction; a mask 120 located in the incident light path, the mask 120 being rotatable around the optical axis AX and having a plurality of light holes 121 at equal intervals; and a projection component 140 located in the write light path connected to the incident light path and extending in the second direction, configured to project the plurality of light holes 121 onto the surface of the substrate 150 to form a plurality of write light spots 121' corresponding one-to-one with the light holes 121.

[0055] For example, the fabrication system 10 also includes a workpiece stage driving mechanism (not shown) coupled to the workpiece stage 160 and configured to drive the workpiece stage 160 to move continuously along a third direction and to step along a fourth direction by a preset amount of movement; wherein the third direction (i.e., the Y direction) is perpendicular to the arrangement direction of the writing spot 121' (i.e., the X direction), and the fourth direction (i.e., the X direction) is parallel to the arrangement direction of the writing spot 121'.

[0056] For example, the second direction can be the same as the first direction. For instance, when the first direction is the Z' direction (the incident light path extends along the Z' direction), the second direction is also the Z' direction (the write light path extends along the Z' direction); when the first direction is the negative direction of X' (the incident light path extends along the negative direction of X'), the second direction is also the negative direction of X' (the write light path extends along the negative direction of X'). Optionally, the second direction can also be different from the first direction. Figure 1 For example, when the first direction is the Z' direction, a reflector 130 can be added to the optical system to redirect the incident light path extending along the first direction (Z' direction) to the writing light path extending along the second direction (the negative direction of X'). Alternatively, in some other embodiments, the incident light path extending along the first direction (Z' direction) can also be redirected to the writing light path extending along the second direction (X' direction), which helps to reduce the longitudinal length of the optical system. In summary, the orientation of the first and second directions can be determined according to the positions of the light source 110, the mask 120, and the projection component 140, and this application embodiment does not impose any limitations on this.

[0057] For example, the shape of the substrate 150 can be arbitrary. For ease of description, this embodiment takes the substrate 150 as a rectangle, and the placement direction matches the running direction of the workpiece stage 160. The grating lines to be prepared are parallel to one side of the substrate 150 and also parallel to the Y-axis.

[0058] For example, the shape, number, and spacing of the apertures 121 on the photomask 120 can be arbitrary, such as circular, square, or parallelogram shapes, and the number can be 2, 3, 4, 5, or 6, etc. The spacing can be set according to the actual grating pitch requirements. In this embodiment, taking 3 apertures as an example, it can be seen that 3 apertures are spaced apart on the photomask 120 along the X direction. Through the reflector 130 and the projection component 140, multiple writing spots 121' corresponding one-to-one with the apertures 121 can be formed on the surface of the substrate 150.

[0059] For example, such as Figure 1 As shown, the projection assembly 140 may include a tube lens 141 located near the reflector 130 in the write optical path and an objective lens 142 located near the substrate 150 in the write optical path. The projection assembly 140 can perform miniaturized projection onto the aperture on the mask 120.

[0060] The principle of fabricating a diffraction grating using the fabrication system 10 in this embodiment is as follows:

[0061] In theory, the resolution of the 160-step stage is high enough, and the size of the write spot 121' is small enough. The scanning of a single write spot 121' and the 160-step stage work together to achieve exposure of diffraction gratings with arbitrary pitch can be achieved. However, the lithography efficiency of a single write spot 121' is very low, limiting its practical application value. Using multiple write spots 121' in parallel scanning can theoretically increase lithography efficiency several times over, but the X-axis spacing of the write spots 121' must be strictly matched to the designed pitch of the diffraction grating. To achieve this objective, this embodiment replaces the spatial light modulator in a traditional parallel direct-write lithography system with a mask 120 having multiple apertures 121. Illumination is achieved using transmitted light, which is then focused onto the surface of the substrate 150 through micro-projection via a lens 141 and objective lens 142, forming multiple writing spots 121'. With the movement of the stage 160, the writing spots 121' are comb-scanned along the Y-direction and stepped together along the X-direction, resulting in the formation of a grating of a certain area through exposure. Further processing steps, such as development, complete the fabrication of the diffraction grating. It should be noted that this embodiment only involves the exposure stage and does not involve other preceding or subsequent processing steps.

[0062] In some embodiments of this application, the fabrication system 10 further includes: a first adjustment mechanism (not shown), coupled to the mask 120, configured to drive the mask 120 to rotate about the optical axis AX to change the distance between two adjacent write spots 121'; wherein, as Figure 3 As shown, when the first adjustment mechanism drives the mask 120 to rotate around the optical axis AX by a first angle θ, the distance L1 between two adjacent writing spots will change after miniaturization projection. Where 'a' represents the distance between two adjacent apertures, and 'm' represents the scaling factor. Using this method, the spacing between adjacent write spots on the substrate 150 can be steplessly adjusted, achieving precise adjustment of the grating pitch.

[0063] In some embodiments of this application, when the number of apertures 121 is n, the preset movement amount is... Where p is any integer from 1 to n. Specifically, as shown... Figure 4 As shown, when p is n, the amount of movement of the workpiece stage 160 along the X-axis is... To achieve the maximum stitching exposure speed, no grid lines will be repeatedly exposed; that is, no grid lines will be repeatedly exposed during two adjacent exposure processes. Figure 5 As shown, when p is n-1, the amount of movement of the workpiece stage 160 along the X-axis is... Some of the grid lines will be repeatedly exposed. When using this repeated exposure method in practice, it is necessary to fully consider the exposure dose received by the photosensitive material and the photosensitive process characteristics of the material, and to reasonably design the step size of the repeated exposure to achieve the goal of optimizing the grid line quality.

[0064] In some embodiments of this application, such as Figure 6 As shown, the projection assembly 140 also includes a flat glass plate 143 located in the writing optical path and disposed between the tube lens 141 and the objective lens 142. The flat glass plate 143 is rotatable relative to a first reference plane AS1 to compensate for the positional error of the substrate 150; wherein, the first reference plane AS1 passes through the center of the flat glass plate 143 and is perpendicular to the optical axis AX. Optionally, the fabrication system 10 also includes a second adjustment mechanism (not shown) coupled to the flat glass plate 143 and configured to drive the flat glass plate 143 to rotate relative to the first reference plane AS1. Figure 7 As shown in the example, when the driving plate glass 143 rotates a certain angle relative to the first reference surface AS1, the writing spot formed on the surface of the substrate 150 by the light passing through the aperture 121 will be translated along the X-direction or the -X-direction, thereby compensating for the positional error of the substrate 150. It is understood that the specific rotation angle parameters can be calculated based on the required translation amount combined with the focal length of the optical system, the thickness of the plate glass, the refractive index, wavelength, etc., which optical designers can understand; detailed explanations are not provided here.

[0065] In some embodiments of this application, the fabrication system 10 further includes a linear polarization control component (not shown), located in the incident light path and disposed between the light source 110 and the mask 120. When the light source 110 is a linearly polarized light source, the linear polarization control component includes a half-wave plate rotatable about the optical axis AX, thereby changing the polarization direction of the linearly polarized light. When the light source 110 is a non-linearly polarized light source, the linear polarization control component includes a linear polarizer rotatable about the optical axis AX, thereby converting non-linearly polarized light into linearly polarized light. Optionally, by designing a polarization control function in the above fabrication system, a liquid crystal polarization grating can be fabricated.

[0066] In some embodiments of this application, such as Figure 11 As shown, the diffraction grating prepared by the fabrication system 10 exhibits irregularities at both ends of the grating lines. Generally, the edge region is not a working area and does not affect the actual performance of the diffraction grating. Furthermore, the grating lines are microstructures, and this feature is not easily observed by the human eye. To eliminate this issue, the light spot can be further scanned and exposed around the diffraction grating (e.g., along the x-axis and / or y-axis) to make the ends neat. Alternatively, other exposure equipment can be used to perform edge-modification exposure on the diffraction grating to obtain a result such as... Figure 12 The diffraction grating pattern shown.

[0067] This application also provides a method for fabricating a diffraction grating. On the one hand, multiple writing spots are obtained by projecting multiple apertures on a mask, and then the workpiece stage is moved to achieve parallel scanning of multiple writing spots, thereby multiplying the photolithography efficiency. On the other hand, by rotating the mask and controlling the rotation angle of the mask, the spacing between adjacent writing spots on the substrate can be infinitely adjusted to achieve precise adjustment of the grating pitch.

[0068] like Figure 8 As shown in the figure, this application provides a method for fabricating a diffraction grating, including the following steps:

[0069] S100, providing an initial optical system and a mask; wherein, the initial optical system includes a light source and a projection component arranged sequentially along the optical axis, and the mask has multiple light holes at equal intervals;

[0070] S200, Place the substrate on the workpiece stage;

[0071] S300. A mask is placed between the light source and the projection component of the initial optical system to form a target optical system. The target optical system is configured to project multiple apertures onto the substrate surface to form multiple write spots corresponding to the apertures. When the mask rotates around the optical axis, the distance between two adjacent write spots changes synchronously.

[0072] S400: Control the workpiece stage to move relative to the writing spot, so that the writing spot scans and exposes the substrate to form a grating pattern with a preset grating pitch.

[0073] For example, the setup of the target optical system can be referenced to the setup of the optical system in the aforementioned fabrication system 10. Therefore, for ease of understanding, the fabrication method will continue to be described below by referring to the components in the fabrication system 10.

[0074] For example, such as Figure 3 As shown, when the mask 120 rotates by a first angle θ around the optical axis AX, the distance L1 between two adjacent write spots changes to... Where a represents the distance between two adjacent apertures, and m represents the scaling factor.

[0075] For example, such as Figure 1 and Figure 2 As shown, step S400 may include: driving the workpiece stage 160 to move continuously along a third direction (i.e., the Y direction) and stepping along a fourth direction (i.e., the X direction) by a preset amount of movement; wherein, the third direction is perpendicular to the arrangement direction of the writing light spots, the fourth direction is parallel to the arrangement direction of the writing light spots, and when the number of light holes is n, the preset amount of movement is... Where p is any integer from 1 to n.

[0076] For example, such as Figure 1 As shown, the target optical system may further include a reflector 130 disposed between the mask 120 and the projection assembly 140, to redirect light rays emitted through the aperture on the mask 120 to the write optical path, thereby reducing the longitudinal length of the optical system; the projection assembly 140 may include a tube lens 141 located near the reflector 130 in the write optical path and an objective lens 142 located near the substrate 150 in the write optical path. The projection assembly 140 can perform miniaturized projection onto the aperture on the mask 120.

[0077] In direct-write lithography systems, there is often a problem of mismatch in the accuracy of the grating pattern due to errors in the workpiece stage movement. Specifically, with Figure 1 Taking the fabrication system 10 shown as an example, the errors of the workpiece stage 160 can be divided into positioning errors in the XY direction and attitude errors of the XY axis: pitch error, roll error, and yaw error. Since this embodiment involves scanning lithography motion along the Y direction, the Y positioning error, Y-axis pitch error, and X-axis roll error of the workpiece stage 160 will not affect the grid line position. Therefore, the errors in this embodiment can be simplified to the scanning pattern accuracy mismatch problem caused by the three situations: X-axis positioning error, X-axis pitch error, Y-axis roll error, and X-axis yaw error. The specific values ​​of the above positioning and attitude errors can be measured in real time using a multi-axis laser interferometer, and will not be specifically explained here.

[0078] The compensation methods for the three error scenarios will be described in turn:

[0079] (1) X-axis positioning error

[0080] like Figure 7 As shown, the X-axis positioning error can be compensated by rotating the plate glass 143 set between the tube lens 141 and the objective lens 142, wherein the plate glass has a first reference plane AS1 that passes through the center of the plate glass 143 and is perpendicular to the optical axis AX.

[0081] like Figure 7As shown, when the substrate 150 has a positional error (i.e., X-axis positioning error), the positional error of the substrate 150 can be compensated by driving the flat glass 143 to rotate relative to the first reference surface AS1, causing the writing spot 121' to move along the offset direction of the substrate 150. For example, when the substrate 150 has an offset along the X direction, the flat glass 143 can be rotated counterclockwise by a certain angle relative to the first reference surface AS1, causing the writing spot to translate along the X direction, thereby compensating for the offset of the substrate 150 in the X direction; when the substrate 150 has an offset along the -X direction, the flat glass 143 can be rotated clockwise by a certain angle relative to the first reference surface AS1, causing the writing spot to translate along the -X direction, thereby compensating for the offset of the substrate 150 in the -X direction.

[0082] (2) X-axis pitch error and Y-axis roll error

[0083] like Figure 9 As shown, the substrate 150 has a second reference plane AS2 passing through the center of the substrate 150 and perpendicular to the optical axis AX. When the substrate 150 has a rotational attitude error relative to the second reference plane AS2 (such as a rotational error angle of α), the spacing between the writing spots 121' projected onto the substrate 150 by the multiple apertures 121 will be reduced from the distance between the two reference planes. Increase to This leads to pitch error.

[0084] To compensate for the pitch error caused by such errors, the spacing of the written spots in the X direction needs to be adjusted according to the deviation, so as to achieve the effect of keeping the spacing constant on the substrate 150. For example, the mask 120 can be driven to rotate around the optical axis AX to reduce the distance between two adjacent spots 121' on the substrate 150, thereby compensating for the rotational attitude error of the substrate 150 relative to the second reference plane AS2. For example, when the mask 120 continues to rotate by an angle γ, γ should satisfy the following relationship: cos(θ+γ)=cosθ·cosα. In this relationship, γ can be solved by trigonometric functions, which will not be elaborated here.

[0085] (3) X-axis yaw error and Y-axis yaw error

[0086] like Figure 10 As shown, substrate 150 has a reference axis parallel to the optical axis AX. Taking the reference axis as the Z-axis as an example, when substrate 150 generates a deflection attitude error around the Z-axis, the side of substrate 150 will generate a deflection angle of β relative to when no deflection attitude error occurs. If no error compensation is performed, it will form as shown in the figure. Figure 9 The exposure results for the grid lines (solid lines) are shown.

[0087] To compensate for the grid pattern error caused by this type of error, two aspects of compensation are required: one is the grid pitch error caused by the β deflection angle (leading to a reduction in grid pitch), and the other is the grid line orientation error caused by the β deflection angle. For the first aspect, the grid pitch error can be compensated by driving the mask 120 to rotate around the optical axis AX, thereby increasing the distance between two adjacent light spots 121' on the substrate 150. For the second aspect, the orientation error can be compensated by rotating the flat glass 143 relative to the first reference plane AS1 during the scanning exposure of the writing light spot 121', making the scanning direction of the writing light spot 121' parallel to the side of the substrate 150. The deflection attitude error of the substrate 150 is compensated through the above-mentioned compensation for grid pitch error and orientation error.

[0088] In summary, the aforementioned mask rotation and plate glass oscillation methods can compensate for the positioning and attitude errors of the workpiece stage's scanning motion in the Y direction and its stepping and stitching motion in the X direction. The scanning lithography system specifically designed for diffraction grating fabrication proposed in this application mainly comprises a light source, an optical system for generating and controlling multiple light spots, a moving workpiece stage, a drive and control system, and control software. A multi-axis laser interferometry system is installed between the workpiece stage and the optical system to provide position and attitude error data. The optical system for generating and controlling multiple light spots may include a multi-light spot pattern mask and a motion mechanism rotating around the optical axis, an infinity-scaled projection optical system including a tube lens and an objective lens, a plate glass disposed between the tube lens and the objective lens, and an oscillating motion mechanism. Other auxiliary components may include focusing detection, visual recognition, and reflectors, etc., which are not specifically limited in this application.

[0089] This application also provides a computer-readable storage medium storing a computer program that, when executed, performs the steps of the method described in any of the preceding embodiments.

[0090] It should be noted that the numbers used to describe and claim certain embodiments of this application, representing quantities or properties, should be understood to be modified in some cases by the terms "approximately," "about," "approximately," or "essentially." For example, unless otherwise stated, "approximately," "about," "approximately," or "essentially" can indicate a variation of ±20% of the value they describe. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, which may be changed according to the characteristics required by individual embodiments. In some embodiments, numerical parameters should take into account specified significant digits and employ a general method of digit reservation. Although the numerical ranges and parameters used to confirm their breadth of range in some embodiments of this application are approximate values, in specific embodiments, such numerical values ​​are set as precisely as feasible.

[0091] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0092] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A system for producing a diffraction grating, comprising a workpiece stage, a substrate disposed on the workpiece stage, and an optical system for forming a writing spot on a surface of the substrate, characterized by, The optical system is arranged sequentially along the optical axis as follows: The light source is located in the incident light path extending along the first direction; A photomask is located in the incident light path, and the photomask is rotatable around the optical axis and has multiple light holes at equal intervals. A projection component is located in a write optical path that is connected to the incident optical path and extends along a second direction. The projection component is configured to project the plurality of optical holes onto the substrate surface to form a plurality of write optical spots that correspond one-to-one with the optical holes.

2. The system according to claim 1, characterized in that, The preparation system further includes: A first adjustment mechanism, coupled to the mask, is configured to drive the mask to rotate about the optical axis to change the distance between two adjacent write spots; When the first adjustment mechanism drives the mask to rotate around the optical axis by a first angle θ, the distance L1 between two adjacent writing spots changes to... Where a represents the distance between two adjacent apertures, and m represents the scaling factor.

3. The system according to claim 2, characterized in that, The preparation system further includes: A workpiece stage driving mechanism, coupled to the workpiece stage, is configured to drive the workpiece stage to move continuously in a third direction and to move in steps in a fourth direction by a preset amount of movement. Wherein, the third direction is perpendicular to the arrangement direction of the writing light spot, and the fourth direction is parallel to the arrangement direction of the writing light spot.

4. The system according to claim 3, characterized in that, When the number of light apertures is n, the preset movement amount is Where p is any integer from 1 to n.

5. The system according to claim 1, characterized in that, The optical system further includes a mirror configured to reflect light rays exiting through the plurality of apertures to redirect them to the write optical path; The projection component includes: The tube mirror is located in the writing optical path, close to the reflector; The objective lens is located in the writing optical path, close to the substrate; and, A flat glass plate is located in the writing optical path and disposed between the tube lens and the objective lens. The flat glass plate can rotate relative to a first reference plane to compensate for the positional error of the substrate. The first reference plane passes through the center of the flat glass plate and is perpendicular to the optical axis.

6. The system according to claim 5, characterized in that, The preparation system further includes: The second adjustment mechanism, coupled to the flat glass, is configured to drive the flat glass to rotate relative to the first reference plane.

7. The system according to claim 1, characterized in that, The preparation system further includes: A linear polarization control component is located in the incident light path and disposed between the light source and the mask. Wherein, when the light source is a linearly polarized light source, the linear polarization control component includes a half-wave plate that can rotate around the optical axis; when the light source is a non-linearly polarized light source, the linear polarization control component includes a linear polarizer that can rotate around the optical axis.

8. A method for fabricating a diffraction grating, characterized in that, include: An initial optical system and a photomask are provided; wherein, the initial optical system includes a light source and a projection component arranged sequentially along the optical axis, and the photomask has multiple light holes at equal intervals; Place the substrate on the workpiece stage; The mask is placed between the light source and the projection component of the initial optical system to form a target optical system; wherein the target optical system is configured to project the plurality of apertures onto the substrate surface to form a plurality of write spots corresponding one-to-one with the apertures, and when the mask rotates around the optical axis, the distance between two adjacent write spots changes synchronously. The workpiece stage is controlled to move relative to the writing spot, so that the writing spot scans and exposes the substrate to form a grating pattern with a preset grating pitch.

9. The method according to claim 8, characterized in that, When the photomask rotates around the optical axis by a first angle θ, the distance L1 between two adjacent writing spots changes to Where a represents the distance between two adjacent apertures, and m represents the scaling factor.

10. The method according to claim 9, characterized in that, The control of the workpiece stage relative to the writing spot includes: The workpiece stage is driven to move continuously along a third direction and in steps along a fourth direction by a preset amount of movement; wherein the third direction is perpendicular to the arrangement direction of the writing light spots, the fourth direction is parallel to the arrangement direction of the writing light spots, and when the number of light holes is n, the preset amount of movement is... Where p is any integer from 1 to n.

11. The method according to any one of claims 8 to 10, characterized in that, The projection assembly includes a tube lens, an objective lens, and a plate glass disposed between the tube lens and the objective lens. The plate glass has a first reference plane passing through the center of the plate glass and perpendicular to the optical axis. When the substrate has a positional error, the method further includes: The flat glass is driven to rotate relative to the first reference surface, causing the writing spot to move along the offset direction of the substrate to compensate for the positional error of the substrate.

12. The method according to any one of claims 8 to 10, characterized in that, The substrate has a second reference plane passing through its center and perpendicular to the optical axis. When the substrate has a rotational attitude error relative to the second reference plane, the method further includes: The photomask is driven to rotate around the optical axis to reduce the distance between two adjacent light spots on the substrate and compensate for the rotational attitude error of the substrate relative to the second reference plane.

13. The method according to any one of claims 8 to 10, characterized in that, The projection assembly includes a tube lens, an objective lens, and a plate glass disposed between the tube lens and the objective lens. The plate glass has a first reference plane passing through the center of the plate glass and perpendicular to the optical axis. The substrate has a reference axis parallel to the optical axis. When the substrate has a deflection attitude error about the reference axis, the method further includes: The mask is driven to rotate around the optical axis to increase the distance between two adjacent light spots on the substrate. Then, during the scanning exposure of the writing light spot, the flat glass is rotated relative to the first reference surface so that the scanning direction of the writing light spot is parallel to the side of the substrate to compensate for the deflection attitude error of the substrate around the reference axis.

14. A computer-readable storage medium, characterized in that, The storage medium stores a computer program that, when executed, implements the steps of the method as described in any one of claims 8 to 13.

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