A system and method for improving lithography resolution based on three-dimensional mobile exposure

Abstract

The present invention relates to the field of DMD device imaging exposure technology, and in particular to a system and method for improving lithography resolution based on three-dimensional mobile exposure, which fills the DMD pixel gap by repeated micro-movement of a three-dimensional mobile platform at a nanometer distance in lithography, thereby reducing the DMD pixel quantization error, improving the edge smoothness of the exposure pattern contour, and improving the resolution, and achieving different degrees of optimization results through different moving distances and different moving routes of the three-dimensional mobile platform. Compared with sub-image superposition lithography, the whole process is more convenient and flexible, and compared with ordinary non-sub-image superposition lithography, the edge smoothness of the pattern contour after exposure is smoother.

Description

Technical Field

[0001] The present invention relates to the technical field of DMD device imaging exposure, and in particular to a system and method for improving lithography resolution based on three-dimensional mobile exposure. Background Art

[0002] Photolithography is a process technology that uses the principle of photochemical reaction and chemical and physical etching methods to transfer the pattern on the mask to the wafer. In recent years, photolithography has made rapid progress, the feature size of its optical devices has continued to decrease, and the performance and integration of chips have continued to improve. After experiencing changes in exposure methods such as contact / proximity, equal-magnification projection, reduced step projection, and step-and-scan projection, the technical nodes of photolithography technology have increased from 1.5 microns, 1 micron, 0.5 microns, 90 nanometers, and 45 nanometers in 1978 to 22 nanometers today. However, there are still many problems that have not been solved, such as low efficiency, poor flexibility, complex process, and high time cost.

[0003] Based on the characteristics of low cost, high efficiency and light weight, DMD digital lithography technology has attracted wide attention from scholars at home and abroad. However, DMD digital lithography technology will produce a non-integer pixel error in the process of generating dynamic mask images, which is called DMD pixel quantization error, resulting in a jagged structure on the contour edge of the lithographic pattern. In order to solve the above problems, scholars at home and abroad have carried out relevant scientific research. K Kim et al. of Kyunghwa University in Seoul, South Korea proposed a sub-image dislocation superposition exposure method. While maintaining the ultraviolet exposure area, the oscillation technology was used to improve the lithographic resolution. Since the gaps between pixels were filled with overlapping patterns, the surface roughness of the microstructure was improved, but the smooth surface roughness was limited. Gao Yiqing et al. of Nanchang Hangkong University reduced the DMD pixel error by designing the feature size of the mask to be an integer multiple of the DMD pixel, but this method was limited by the design and processing of the microstructure slice layer, which reduced the flexibility of processing. Liu Hua and Guo Shuping et al. of Northeast Normal University proposed a spatiotemporal collaborative exposure technology. This technology improves the smoothness of the exposure pattern by continuously overlapping and filling sub-images, but it requires the production of a large number of sub-images and the process is cumbersome and inefficient. It can be seen that the existing technology for improving lithography resolution is difficult to meet the current needs in high-precision systems. Summary of the invention

[0004] In view of this, the purpose of the present invention is to propose a system and method for improving lithography resolution based on three-dimensional mobile exposure, so as to solve the problem that DMD digital lithography technology causes jagged structures on the contour edges of the lithographic graphics, thereby affecting the resolution.

[0005] Based on the above purpose, the present invention provides a system for improving lithography resolution based on three-dimensional mobile exposure, comprising an ultraviolet light source, a light-homogenizing collimating element, a DMD chip, a reflector, a projection lens and a three-dimensional mobile platform, wherein the ultraviolet light source is used to provide ultraviolet light;

[0006] The light-homogenizing collimating element is used to process the ultraviolet light into a uniform light beam and hit the DMD chip;

[0007] The DMD chip is used to reflect the uniform light beam to the reflector;

[0008] The reflector is used to project a uniform light beam into the projection objective;

[0009] The projection objective lens is used to focus the uniform light beam onto the three-dimensional moving platform;

[0010] The three-dimensional moving platform is used to place the workpiece to be photoetched, and optimizes the edge of the exposure pattern to different degrees through uninterrupted back and forth movement.

[0011] Preferably, the route of the three-dimensional mobile platform moving back and forth repeatedly is controlled by a computing terminal, and the control process includes:

[0012] Determine the moving position of the three-dimensional mobile platform;

[0013] Determine the number of steps as N-1, and divide the length of a pixel into N equal parts, with the distance of each part being n;

[0014] Determine the three-dimensional moving step length. Suppose that the step length of the x-axis in the exposure in the mth process is L x =mn, the step length of the y-axis is L y = mn;

[0015] Determine the exposure time. Assume that the optimal exposure time of the pattern without three-dimensional movement is T, then the time of three-dimensional movement exposure in the i-th process is t, t=T / N-1, where i=1, 2...N-1;

[0016] In the i-th step of the photolithography process, the x-axis and y-axis of the three-dimensional platform are moved to the left and upward by in respectively, and then returned to the initial point, and the process is repeated for a time of t.

[0017] Preferably, the three-dimensional mobile platform is a piezoelectric nano mobile platform.

[0018] Preferably, the ultraviolet light source is a 405 nanometer ultraviolet light source.

[0019] The present invention also provides a method for improving lithography resolution based on three-dimensional mobile exposure, comprising the following steps:

[0020] The DMD lithography system is debugged to enable the ultraviolet light source to pass through the uniform light collimating element in the DMD lithography system, and then pass through the DMD chip, reflector and projection lens in sequence, and accurately expose the required exposure pattern on the three-dimensional moving platform;

[0021] Place the workpiece to be photolithographically processed at the precise exposure position of the 3D mobile platform, turn on the 3D mobile platform and during the photolithography process, the DMD chip synchronizes the 3D mobile platform to make the exposure pattern move back and forth repeatedly on the 3D mobile platform. By controlling the moving route of the 3D mobile platform, the edges of the exposure pattern can be optimized to varying degrees.

[0022] Preferably, controlling the moving route of the three-dimensional mobile platform includes:

[0023] Determine the moving position of the three-dimensional mobile platform;

[0024] Determine the process, divide the length of a pixel into N parts equally, and the distance of each part is n;

[0025] Determine the three-dimensional moving step length. Suppose that the exposure is in the mth process and the step length of the x-axis is L x =mn, the step length of the y-axis is L y = mn;

[0026] Determine the exposure time. Assume that the optimal exposure time of the pattern without three-dimensional movement is T, then the time of three-dimensional movement exposure in the i-th process is t, t=T / N-1, where i=1, 2...N-1;

[0027] In the i-th step of the photolithography process, the x-axis and y-axis of the three-dimensional platform are moved to the left and upward by in respectively, and then returned to the initial point, and the process is repeated for a time of t.

[0028] Preferably, determining the moving position of the three-dimensional moving platform includes making the x-axis and y-axis of the exposure pattern parallel to the x-axis and y-axis of the three-dimensional moving platform.

[0029] Preferably, the length of one pixel is 7.56 micrometers.

[0030] Beneficial effects of the present invention: The present invention uses a three-dimensional mobile platform and DMD to work together to produce a system and method for improving lithography resolution based on three-dimensional mobile exposure. The system and method do not need to increase the magnification of the projection objective lens, and the process is simple. The DMD pixel gap is filled by repeated micro-movement of the three-dimensional mobile platform at a nanometer distance in lithography, thereby reducing the DMD pixel quantization error, improving the edge smoothness of the exposure graphic contour, and improving the resolution. Different degrees of optimization results are achieved through different moving distances and different moving routes of the three-dimensional mobile platform. Compared with sub-image superposition lithography, the whole process is more convenient and flexible, and compared with ordinary non-sub-image superposition lithography, the edge smoothness of the graphic contour after exposure is smoother. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only for the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 A schematic diagram of a system for improving lithography resolution based on three-dimensional mobile exposure according to an embodiment of the present invention;

[0033] Figure 2 A schematic diagram of a three-dimensional mobile exposure technology according to an embodiment of the present invention;

[0034] Figure 3 It is a comparison diagram of the lithography effect before and after the three-dimensional mobile exposure technology according to an embodiment of the present invention.

[0035] The markings in the figure are:

[0036] 1. Ultraviolet light source; 2. Light-homogenizing collimating element; 3. DMD chip; 4. Reflector; 5. Three-dimensional mobile platform; 6. DMD controller; 7. Computing terminal. DETAILED DESCRIPTION

[0037] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments.

[0038] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the present invention should be understood by people with ordinary skills in the field to which the present invention belongs. The "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0039] like Figure 1 As shown, the embodiment of this specification provides a system for improving lithography resolution based on three-dimensional mobile exposure, including an ultraviolet light source 1, a light-homogenizing collimating element 2, a DMD chip 3, a reflector 4, a projection objective lens and a three-dimensional mobile platform 5, wherein the ultraviolet light source 1 is used to provide ultraviolet light;

[0040] The light-homogenizing collimating element 2 is used to process the ultraviolet light into a uniform light beam and hit the DMD chip 3;

[0041] The DMD chip 3 is used to reflect the uniform light beam to the reflector 4;

[0042] The reflector 4 is used to project a uniform light beam into the projection objective lens;

[0043] The projection objective lens is used to focus the uniform light beam onto the three-dimensional moving platform 5;

[0044] The three-dimensional moving platform 5 is used to place the workpiece to be photoetched, and optimizes the edge of the exposure pattern to different degrees through uninterrupted back and forth movement.

[0045] For example, the DMD chip 3 is controlled by the DMD controller 6 , and the three-dimensional mobile platform 5 is controlled by the computing terminal 7 .

[0046] As an implementation manner, the three-dimensional mobile platform 5 is a piezoelectric nano mobile platform.

[0047] As an implementation mode, the ultraviolet light source 1 is a 405-nanometer ultraviolet light source, which has a small size, a long life, low energy consumption, and strong penetrating power.

[0048] The embodiment of this specification also provides a method for improving lithography resolution based on three-dimensional mobile exposure, comprising the following steps:

[0049] Debug the DMD lithography system, start the ultraviolet light source 1, generate ultraviolet light, and the light-homogenizing collimating element 2 processes the ultraviolet light into a uniform light beam, which hits the DMD chip 3. The DMD chip 3 reflects the uniform light beam to the reflector 4, and the reflector 4 then projects the uniform light beam into the projection objective lens. Finally, the projection objective lens focuses the uniform light beam onto the three-dimensional moving platform 5, and turns on the ultraviolet light source 1. By rotating the lifting platform and the three-dimensional moving platform 5, the precise exposure position is found.

[0050] Create an exposure pattern on a computer and import the pattern into the DMD chip 3;

[0051] Place a clean glass slide on a glue spreader, use a micropipette to drop an appropriate amount of photoresist on the silicon substrate, set the speed and time of the glue spreader, and spread the glue;

[0052] The prepared workpiece is placed at the precise exposure position on the three-dimensional mobile platform 5, and the three-dimensional mobile platform 5 and the light source are turned on at the same time. During the photolithography process, the DMD chip 3 synchronizes the three-dimensional mobile platform 5 to make the exposure pattern move back and forth repeatedly on the three-dimensional mobile platform. The moving route of the three-dimensional mobile platform 5 is controlled by a computer, and the edge of the exposure pattern is effectively optimized to different degrees.

[0053] Wherein, the control of the moving route of the three-dimensional mobile platform includes:

[0054] Step 1, determining the moving position of the three-dimensional mobile platform 5;

[0055] Step 2, determine the number of processes as N-1, divide the length of a pixel into N parts, and the distance of each part is n;

[0056] Step 3, determine the three-dimensional moving step length, assuming that in the exposure process m, the step length of the x-axis is Lx, and the step length of the y-axis is Ly;

[0057] Lx=mn

[0058] Ly=mn;

[0059] Specifically, this process is divided into N-1 processes, and the displacement step length of the three-dimensional mobile platform 5 is different in each process. The mth process refers to the mth cyclic movement set for the three-dimensional mobile platform 5.

[0060] Step 4, determine the exposure time. Assume that the optimal exposure time of the pattern without three-dimensional movement is T, and the time for three-dimensional movement exposure to move repeatedly at the same step length is t:

[0061] t=T / (N-1)

[0062] Step 5, during the photolithography process, move the x-axis and y-axis of the three-dimensional platform to the left and upward for 1n respectively, then return to the initial point, repeat this process, the time length is t, continue to move the x-axis and y-axis of the three-dimensional platform to the left and upward for 2n respectively, then return to the initial point, repeat this process, the time length is t; ...; continue to move the x-axis and y-axis of the three-dimensional platform to the left and upward for (N-1)n respectively, then return to the initial point, repeat this process, the time length is t, as shown in FIG. Figure 2 shown.

[0063] Preferably, the moving position of the three-dimensional mobile platform 5 is determined by making the x-axis and y-axis of the exposure pattern parallel to the x-axis and y-axis of the three-dimensional mobile platform 5 .

[0064] Preferably, the three-dimensional mobile platform 5 is a piezoelectric nano mobile platform. This nano mobile platform has high precision, and the piezoelectric ceramic platform can be programmed by a computer to freely control the precise movement of the nano mobile platform in three dimensions.

[0065] Preferably, the length of one pixel is 7.56 microns.

[0066] In summary, the relationship between parameter N and other specific parameters is shown in Table 1:

[0067] Table 1

[0068]

[0069] Through the above method, the repeated micro-movement of the three-dimensional mobile platform at nanometer distance in lithography fills the DMD pixel gap, thereby reducing the DMD pixel quantization error and making the edge of the exposure pattern contour smoother, thereby improving the lithography resolution.

[0070] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present invention (including the claims) is limited to these examples. Under the concept of the present invention, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity.

[0071] The present invention is intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A system for improving lithography resolution based on three-dimensional mobile exposure, characterized in that: It includes an ultraviolet light source, a light-homogenizing collimating element, a DMD chip, a reflector, a projection lens and a three-dimensional moving platform, wherein the ultraviolet light source is used to provide ultraviolet light; The light-homogenizing collimating element is used to process the ultraviolet light into a uniform light beam and hit the DMD chip; The DMD chip is used to reflect the uniform light beam to the reflector; The reflector is used to project a uniform light beam into the projection objective; The projection objective lens is used to focus the uniform light beam onto the three-dimensional moving platform; The three-dimensional moving platform is used to place the workpiece to be photoetched, and optimizes the edge of the exposure pattern to different degrees by moving back and forth repeatedly without interruption; The route of the three-dimensional mobile platform moving back and forth repeatedly is controlled by the computing terminal, and the control process includes: Determine the moving position of the three-dimensional mobile platform; Determine the number of steps as N-1, and divide the length of a pixel into N equal parts, with the distance of each part being n; Determine the three-dimensional moving step length. Suppose that the step length of the x-axis in the exposure in the mth process is L x =mn, the step length of the y-axis is L y = mn; Determine the exposure time. Assume that the optimal exposure time of the pattern without three-dimensional movement is T, then the time of three-dimensional movement exposure in the i-th process is t, t=T / N-1, where i=1, 2...N-1; In the i-th step of the photolithography process, the x-axis and y-axis of the three-dimensional platform are moved to the left and upward by in respectively, and then returned to the initial point, and the process is repeated for a time of t.

2. The system for improving lithography resolution based on three-dimensional mobile exposure according to claim 1, characterized in that: The three-dimensional mobile platform is a piezoelectric nano mobile platform.

3. The system for improving lithography resolution based on three-dimensional mobile exposure according to claim 1, characterized in that: The ultraviolet light source is a 405 nanometer ultraviolet light source.

4. A method for improving lithography resolution based on three-dimensional mobile exposure, characterized in that: The method comprises the following steps: The DMD lithography system is debugged to enable the ultraviolet light source to pass through the uniform light collimating element in the DMD lithography system, and then pass through the DMD chip, reflector and projection lens in sequence, and accurately expose the required exposure pattern on the three-dimensional moving platform; The workpiece to be photolithography is placed at the precise exposure position of the 3D mobile platform, and the 3D mobile platform is turned on. During the photolithography process, the DMD chip synchronizes the 3D mobile platform to make the exposure pattern move back and forth repeatedly on the 3D mobile platform. By controlling the moving route of the 3D mobile platform, the edge of the exposure pattern is optimized to varying degrees. The controlling the moving route of the three-dimensional mobile platform comprises: Determine the moving position of the three-dimensional mobile platform; Determine the process, divide the length of a pixel into N parts equally, and the distance of each part is n; Determine the three-dimensional moving step length. Suppose that the exposure is in the mth process and the step length of the x-axis is L x =mn, the step length of the y-axis is L y = mn; Determine the exposure time. Assume that the optimal exposure time of the pattern without three-dimensional movement is T, then the time of three-dimensional movement exposure in the i-th process is t, t=T / N-1, where i=1, 2...N-1; In the i-th step of the photolithography process, the x-axis and y-axis of the three-dimensional platform are moved to the left and upward by in respectively, and then returned to the initial point, and the process is repeated for a time of t.

5. The method for improving lithography resolution based on three-dimensional mobile exposure according to claim 4, characterized in that: Determining the moving position of the three-dimensional moving platform includes making the x-axis and y-axis of the exposure pattern parallel to the x-axis and y-axis of the three-dimensional moving platform.

6. The method for improving lithography resolution based on three-dimensional mobile exposure according to claim 4, characterized in that: The length of one pixel is 7.56 micrometers.

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