Method for solving uniformity of line width in crystal grain
By using photoresist with different resolutions and optimization process steps in the lithography process, the problem of linewidth uniformity in the grain is solved, the photolithography imaging effect and product quality are improved, and the equipment cost is reduced.
Patent Information
- Application Number
- CN202510763410.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-09
- Publication Date
- 2025-08-15
AI Technical Summary
The prior art is difficult to effectively solve the problem of line width uniformity in the grain, which affects the imaging effect and product yield of the lithography process.
By using photoresist with different resolutions to glue the key sizes in the grains, combining the HMDS film formation, uniformity, exposure and development steps in the photolithography process, line width data is observed and collected, and optimization parameters and processes are determined to improve line width uniformity and imaging effects.
The optimization of the uniformity of the line width in the grain is achieved, the imaging effect and product yield of the lithography process are improved, and the cost of lithography equipment is saved.
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Figure CN120491391A_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to the field of semiconductors, and more particularly to a method for solving line width uniformity within a grain. Background Art
[0002] In the more than half a century since their introduction, microelectronics and integrated circuit technology have advanced rapidly, with advances in photolithography playing a significant role. The ever-shrinking critical dimensions, a key indicator of photolithography development, have placed higher demands on improving key parameters such as product linewidth uniformity. Further research is needed to improve linewidth uniformity within wafer dies, thereby optimizing processes and increasing product yield. Summary of the Invention
[0003] In view of the problems existing in the background technology, an object of the present disclosure is to provide a method for solving the line width uniformity within a grain, which can broaden the optimization direction for solving the line width uniformity within a grain.
[0004] Another object of the present disclosure is to provide a method for solving the line width uniformity within a grain, which can broaden the optimization direction for solving image effects.
[0005] Another object of the present disclosure is to provide a method for solving the problem of intra-grain line width uniformity, which can determine the optimized parameters of the intra-grain line width uniformity.
[0006] Another object of the present disclosure is to provide a method for solving the line width uniformity within a grain, which can determine the optimized parameters of the image effect.
[0007] Another object of the present disclosure is to provide a method for solving the problem of line width uniformity within a grain, which can provide an optimized process for batch production of photolithography processes.
[0008] Therefore, a method for solving the line width uniformity within the grain includes the following steps: S1, providing two product sheets before the photolithography process; S2, coating, including sub-steps: S21, HMDS film formation, forming an HMDS film on the surface of each product sheet by a gas phase method; S22, cooling before coating, cooling each product sheet with the HMDS film formed on the surface in a cooling tank to the temperature required for coating; S23, coating, each product sheet is spin-coated with a coating in a coating process tank, wherein the two product sheets are each spin-coated with a coating of different resolutions; S24, pre-baking, after the coating is spin-coated Each product sheet is pre-baked in a pre-baking process tank; S3, exposure, the two coated sheets after coating are exposed using a plurality of distributed grains to form a wafer layout to obtain two exposure sheets; S4, development, the two exposed sheets after exposure are developed using the same development conditions to obtain two development sheets; S5, observing and collecting the line width of the key size of the selected grain, collecting the line width in multiple areas of the selected grain, determining the influence of the two glues on the line width uniformity of the key size within the grain and determining the optimized parameters and optimized process for batch production of the lithography process.
[0009] The beneficial effects of the present disclosure are as follows. In the method for solving the line width uniformity within the grain according to the present disclosure, by targeting the influence of different glues with different resolutions (i.e., different adaptability to the size of the critical dimension, the higher the resolution, the more suitable it is for the critical dimension of small size, which can also be called size resolution) on the line width uniformity of the critical dimension within the grain, as verified by the test process, it can be clearly seen that glues with different resolutions in the glue coating process will affect the line width uniformity within the grain, and thus affect the imaging effect, thereby broadening the optimization direction for solving the line width uniformity and imaging effect within the grain, and being able to determine the type of glue that solves the line width uniformity and imaging effect within the grain (i.e., determining the optimization parameters for the line width uniformity and imaging effect within the grain), thereby being able to provide an optimized process for mass production of the lithography process. In addition, since only the type of glue needs to be changed, there is no need to replace the machine for the exposure process of the lithography machine, thereby saving the equipment cost of the lithography process. BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Figure 1 It is a schematic diagram of the structural relationship between the mask, the film and the grain.
[0011] Figure 2 FIG. 1 is a partial schematic structural diagram of an example of a single crystal grain.
[0012] Figure 3 It is a schematic diagram of the line width collection area division of a single grain.
[0013] Figure 4 yes Figure 2 Schematic structure diagram of a pixel of a single grain.
[0014] Figure 5 It is a local topography of a single pixel of the display film.
[0015] Figure 6 These are the representative line width values of nine regions of a die at the center of a selected wafer using one of the glues (GKR5315) of Example 1.
[0016] Figure 7 is with Figure 6 The display image of the die at the center of the selected wafer on the developer sheet formed by the corresponding glue is displayed at the final product test end.
[0017] Figure 8 : These are representative line width values of nine regions of a die at the center of a selected wafer using another glue (DHK-BF511) of Example 1.
[0018] Figure 9 is with Figure 8 The display image of the die at the center of the selected wafer on the developer sheet formed by the corresponding glue is displayed at the final product test end.
[0019] Figure 10 is with Figure 8 The corresponding glue thickness is Representative linewidth values for nine regions of a die at the center of a selected wafer.
[0020] Figure 11 is with Figure 10 The display image of the die at the center of the selected wafer on the developer sheet formed by the corresponding glue is displayed at the final product test end.
[0021] Figure 12 is with Figure 8 The corresponding glue thickness is Representative linewidth values for nine regions of a die at the center of a selected wafer.
[0022] Figure 13 is with Figure 12 The display image of the die at the center of the selected wafer on the developer sheet formed by the corresponding glue is displayed at the final product test end. DETAILED DESCRIPTION
[0023] It will be understood that the disclosed embodiments are merely examples of the present disclosure, which can be implemented in various forms. Therefore, the specific details disclosed herein should not be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously implement the present disclosure.
[0024] [Methods to solve the problem of line width uniformity within grains]
[0025] Reference Figures 1 to 5 According to the present disclosure, the method for solving the problem of line width uniformity within a grain includes the following steps:
[0026] S1, provides two product sheets before the photolithography process;
[0027] S2, glue application, includes the following sub-steps:
[0028] S21, HMDS film formation, forming an HMDS film on the surface of each product sheet by a vapor phase method;
[0029] S22, cooling before coating, each product sheet with HMDS film formed on the surface is cooled in a cooling tank to the temperature required for coating;
[0030] S23, coating, each product sheet is spin-coated with a uniform glue in a uniform glue process tank, wherein the two product sheets are spin-coated with glue of different resolutions;
[0031] S24, pre-baking, each product sheet after spin coating and coating is pre-baked in a pre-baking process tank;
[0032] S3, exposure, the two coated sheets after coating are exposed using a plurality of distributed grains constituting a wafer layout to obtain two exposure sheets;
[0033] S4, developing, developing the two exposed films using the same developing conditions to obtain two developed films;
[0034] S5, observe and collect the line width of the critical dimension of the selected grain, collect the line width in multiple areas of the selected grain, determine the impact of the two glues on the line width uniformity of the critical dimension within the grain and determine the optimized parameters and optimized process for mass production of the lithography process.
[0035] In the method for solving the line width uniformity within a grain according to the present disclosure, by targeting the influence of different glues with different resolutions (i.e., different adaptability to the size of critical dimensions, the higher the resolution, the more suitable it is for small critical dimensions, which can also be called size resolution) on the line width uniformity of critical dimensions within the grain, as verified by the test process, it can be clearly determined that glues with different resolutions in the glue coating process will affect the line width uniformity within the grain, and thus affect the imaging effect. Therefore, the optimization direction for solving the line width uniformity and imaging effect within the grain is broadened, and the type of glue that solves the line width uniformity and imaging effect within the grain can be determined (i.e., the optimization parameters for the line width uniformity and imaging effect within the grain are determined), thereby providing an optimized process for mass production of the lithography process. In addition, since only the type of glue needs to be changed, there is no need to replace the machine platform of the exposure process of the lithography machine, thereby saving the equipment cost of the lithography process.
[0036] In step S1, in one example, each product sheet is surface-coated with The thickness of the SIN film layer is 8 inches in diameter. Of course, it is not limited to this. The surface condition and size of each product wafer can be changed according to actual production conditions.
[0037] Specifically, in one example, in sub-step S21, the operation of forming the HMDS film by the gas phase method is as follows: each product sheet is placed on the wafer stage of the vacuum chamber and the wafer stage is heated to 110°C, nitrogen is used as the carrier gas and the nitrogen pressure is 25kPa, HMDS vapor carried by the nitrogen is introduced, the pressure of the vacuum chamber is maintained at 20Pa, the time of introducing the HMDS vapor carried by the nitrogen is 60s, and the thickness of the formed HMDS film is
[0038] Specifically, in one example, in sub-step S22, the temperature required for the coating is 23°C.
[0039] Specifically, in one example, in sub-step S23, a glue model is GKR5315, and the process of spin coating glue is as follows: 1.5 mL of glue solution is dripped to the center of each product sheet at 2050 rpm. After the glue solution is dripped for 1.5 seconds, each product sheet is rotated at 2200 rpm for 35 seconds. The final glue coating thickness is In sub-step S23, another glue model is DHK-BF511, and the process of spin coating glue is as follows: 1.5mL glue solution is dripped into the center of each product sheet at 2500rpm. After the glue solution is dripped for 2s, each product sheet is rotated at 2400rpm for 35s. The final glue coating thickness is
[0040] Specifically, in one example, in sub-step S24 , the pre-baking temperature is 90° C. and the time is 60 seconds.
[0041] In one example, the exposure in step S3 includes the following substeps: S31, pre-exposure cooling, in which each coated sheet after pre-baking is cooled in a cooling tank to the required exposure temperature of 23°C; S32, exposure, in which two coated sheets are exposed using a VOT612-010-BE plate with a layout design line width of 250±20nm and a Nikon S205C step-and-scan exposure machine. The step size in the X direction is 12949μm, the step size in the Y direction is 250389μm, and the exposure dose for each step-and-scan exposure is 29mj / cm 2 , the imaging focal length is 0.1 μm and the NA value is 0.60; S33, post-exposure baking, post-exposure baking is performed in a post-exposure baking process tank, the post-exposure baking temperature is 110° C., and the time is 120 s.
[0042] In one example, the development of step S4 includes the following sub-steps: S41, cooling before development, cooling each exposed film baked after exposure in a cooling tank to the temperature required for development, 23°C; S42, development, placing each exposed film cooled before development on the turntable of the developer, dripping developer to the center of each exposed film while rotating, and then flushing with water while rotating, the rotation is unidirectional, the rotation speed is 2000rpm, and a positive photoresist developer is used, the developer model is ZX-238, the development time is 60s, and the flushing time is 30s; S43, post-baking in a post-baking process tank, the post-baking temperature is 110°C, and the time is 90s.
[0043] In step S5, in one example, the line width uniformity is observed under a line width scanning electron microscope.
[0044] In step S5, refer to Figure 1 In each display film, the corresponding grains can be selected as the objects of observation and collection in the center, upper, lower, left, and right edges, the middle row and middle column between the center and the upper, lower, left, and right edges of the display film. Figure 1 In the case shown, a total of 11 grains are selected from each developer sheet for observation and collection of the critical dimension line width of each grain. Figure 3 The image is divided into nine equal line width collection areas. In each collection area, a critical size of a pixel at the center is selected as a representative. The number of pixels included in each grain is determined by the actual required resolution (i.e., image resolution). For example, the pixels are arranged in a 640×512 matrix, with 640 pixels in each horizontal row and 512 pixels in each vertical column. For ease of explanation, Figure 2 Only some pixels of one grain are shown.
[0045] [test]
[0046] Example 1
[0047] The method for solving the intra-grain line width uniformity in Example 1 adopts the following steps:
[0048] S1, provide two product sheets before photolithography process, wherein each product sheet is coated with Thickness of SIN film layer on 8-inch diameter wafer;
[0049] S2, glue application, uses the following sub-steps:
[0050] S21, HMDS film formation, using a gas phase method to form an HMDS film on the surface of each product sheet. The operation of forming the HMDS film by the gas phase method is as follows: each product sheet is placed on the wafer stage of the vacuum chamber and the wafer stage is heated to 110°C. Nitrogen is used as the carrier gas and the nitrogen pressure is 25kPa. HMDS vapor carried by nitrogen is introduced. The pressure of the vacuum chamber is maintained at 20Pa. The time of introducing HMDS vapor carried by nitrogen is 60s. The thickness of the formed HMDS film is
[0051] S22, cooling before coating, each product sheet with HMDS film formed on the surface is cooled in a cooling tank to the temperature required for coating, which is 23°C;
[0052] S23, coating, each product sheet is spin-coated with glue in the glue process tank, wherein the two product sheets are spin-coated with glue of different resolutions.
[0053] In sub-step S23, a glue model is GKR5315, and the process of spin coating glue is as follows: 1.5 mL of glue solution is dripped to the center of each product sheet at 2050 rpm. After the glue solution drips for 1.5 seconds, the glue solution is spin coated at 2200 rpm.
[0054] Rotate each product sheet for 35 seconds, and the final glue coating thickness is
[0055] In sub-step S23, the model of another glue is DHK-BF511,
[0056] The process of spin coating is as follows: 1.5 mL of glue solution is dripped into the center of each product sheet at 2500 rpm. After the glue solution is dripped for 2 seconds, each product sheet is rotated at 2400 rpm for 35 seconds. The final glue coating thickness is
[0057] S24, pre-baking, each product sheet after spin coating and coating is pre-baked in the pre-baking process tank,
[0058] The pre-baking temperature is 90°C and the time is 60s;
[0059] S3, exposure, the two coated sheets after coating are exposed using a plurality of distributed grains to form a wafer layout to obtain two exposure sheets,
[0060] The exposure in step S3 is performed using the following sub-steps:
[0061] S31, cooling before exposure, each coated sheet after pre-baking is cooled in a cooling tank to the required exposure temperature of 23°C;
[0062] S32, exposure, for two coated films, using the VOT612-010-BE plate with a layout design line width of 250±20nm and a Nikon S205C step-and-scan exposure machine. The step size in the X direction is 12949μm, the step size in the Y direction is 250389μm, and the exposure dose for each step-and-scan exposure is 29mj / cm 2 , the imaging focal length is 0.1 μm and the NA value is 0.60;
[0063] S33, post-exposure baking, performing post-exposure baking in a post-exposure baking process tank,
[0064] The post-exposure bake temperature was 110°C and the time was 120s;
[0065] S4, development, the two exposed films are developed using the same development conditions to obtain two developed films.
[0066] The development of step S4 adopts the following sub-steps:
[0067] S41, cooling before development, cooling each exposed sheet after post-exposure baking in a cooling tank to the temperature required for development, 23°C;
[0068] S42, developing, placing each exposed film that has been cooled before development on a turntable of a developing machine, dripping developer onto the center of each exposed film while rotating, and then flushing with water while rotating. The rotation is unidirectional and the rotation speed is 2000 rpm. A positive photoresist developer (model ZX-238) is used. The developing time is 60 seconds and the flushing time is 30 seconds.
[0069] S43, post-baking in a post-baking process tank, the post-baking temperature is 110° C., and the time is 90 seconds;
[0070] S5, under the line width scanning electron microscope, observe and collect the line width of the critical dimension of the selected grain, collect the line width in multiple areas of the selected grain, determine the impact of the two types of glue on the line width uniformity of the critical dimension within the grain and determine the optimized parameters and optimized process for mass production of the lithography process.
[0071] Figure 6 These are representative line width values of nine regions of a die at the center of a selected wafer for one of the glues (GKR5315) in Example 1. The difference between the maximum line width value and the minimum line width value is 23 nm (ie, 266 nm - 243 nm). Figure 7 is with Figure 6 The image of the grain in the center of the selected wafer of the developer film formed by the corresponding glue at the test end of the final product has obvious color difference.
[0072] Figure 8These are representative line width values of another glue (DHK-BF511) of Example 1 in nine regions of a die at the center of a selected wafer, and the difference between the maximum line width value and the minimum line width value is 10 nm (ie, 262 nm - 252 nm). Figure 9 is with Figure 8 The display image of the grain at the center of the selected wafer formed by the corresponding glue is displayed at the test end of the final product, and the image has no obvious color difference.
[0073] from Figures 6 to 9 It can be seen that the layout design line width is 250±20nm. Both GKR5315 and DHK-BF511 can achieve 250nm, but the intra-grain line width uniformity of DHK-BF511 is better than that of GKR5315, and the corresponding image of DHK-BF511 has no obvious color difference.
[0074] In other words, by using glues with different line width resolutions, the line width uniformity and imaging effect within the grain can be solved. In other words, there is no need to replace the machine for the exposure process. Only by selecting glue with high line width resolution can the problem of line width uniformity and imaging effect within the grain be solved. In addition, when other process conditions remain unchanged, DHK-BF511 can be used as a glue for the exposure process of batch production of the lithography process. In other words, for Example 1, using specific other process conditions and DHK-BF511, it can be used as an optimized process for this product (i.e., the layout design line width is 250±20nm) for batch production.
[0075] Supplementary Example
[0076] For the glue model of Example 1 being DHK-BF511, only the following two changes are made in sub-step S23, and the rest are the same as in Example 1:
[0077] One is the process of spin coating glue: drip 1.5mL glue solution to the center of each product sheet at 2500rpm. After the glue solution drips for 2s, spin each product sheet at 2500rpm for 35s. The final glue coating thickness is
[0078] The other is the process of spin coating glue: drip 1.5mL glue solution to the center of each product sheet at 2500rpm. After the glue solution drips for 2s, spin each product sheet at 2300rpm for 35s. The final glue coating thickness is
[0079] Figure 10 is with Figure 8 The corresponding glue thickness is The representative line width values of the nine regions of the die at the center of the selected wafer are shown in Figure 2. The difference between the maximum line width and the minimum line width is 8nm (i.e. 256nm-248nm), which is consistent with the Figure 6 The 10nm difference is not much. Figure 11 is with Figure 10 The corresponding image of the grain in the center of the selected wafer formed by the developer film is displayed on the final product test end. The corresponding image of DHK-BF511 also has no obvious color difference.
[0080] Figure 12 is with Figure 8 The corresponding glue thickness is The representative line width values of the nine regions of the die at the center of the selected wafer are shown in Figure 2. The difference between the maximum line width and the minimum line width is 12nm (i.e. 261nm-249nm), which is consistent with the Figure 6 The 10nm difference is not much. Figure 13 is with Figure 12 The corresponding image of the grain in the center of the selected wafer formed by the developer film is displayed on the final product test end. The corresponding image of DHK-BF511 also has no obvious color difference.
[0081] from Figures 10 to 13 Supplementary examples and Figures 6 to 9 It can be seen from Example 1 that the impact of different resolution glues on the line width uniformity and image effect (i.e., color difference) within the grain is much greater than the change in glue thickness. Within the range of glue thickness allowed by the process production, the selection of glues with different resolutions can be considered as a key point.
[0082] The above detailed description is used to describe a number of exemplary embodiments, but this document is not intended to be limited to the explicitly disclosed combinations. Therefore, unless otherwise stated, the various features disclosed herein may be combined to form multiple additional combinations that are not shown for the sake of brevity.
Claims
1. A method for solving the line width uniformity within a grain, characterized in that: Including steps: S1, provides two product sheets before the photolithography process; S2, glue application, includes the following sub-steps: S21, HMDS film formation, forming an HMDS film on the surface of each product sheet by a vapor phase method; S22, cooling before coating, each product sheet with HMDS film formed on the surface is cooled in a cooling tank to the temperature required for coating; S23, coating, each product sheet is spin-coated with a uniform glue in a uniform glue process tank, wherein the two product sheets are spin-coated with glue of different resolutions; S24, pre-baking, each product sheet after spin coating and coating is pre-baked in a pre-baking process tank; S3, exposure, the two coated sheets after coating are exposed using a plurality of distributed grains constituting a wafer layout to obtain two exposure sheets; S4, developing, developing the two exposed films using the same developing conditions to obtain two developed films; S5, observe and collect the line width of the critical dimension of the selected grain, collect the line width in multiple areas of the selected grain, determine the impact of the two glues on the line width uniformity of the critical dimension within the grain and determine the optimized parameters and optimized process for mass production of the lithography process.
2. The method for solving the problem of intra-grain line width uniformity according to claim 1, characterized in that: In step S1, each product sheet is surface-plated with Thickness of SIN film layer on 8-inch diameter wafer.
3. The method for solving the problem of intra-grain line width uniformity according to claim 1, characterized in that: In sub-step S21, the operation of forming the HMDS film by the gas phase method is as follows: each product sheet is placed on the wafer stage of the vacuum chamber and the wafer stage is heated to 110°C. Nitrogen is used as the carrier gas and the nitrogen pressure is 25kPa. HMDS vapor carried by nitrogen is introduced. The pressure of the vacuum chamber is maintained at 20Pa. The time of introducing HMDS vapor carried by nitrogen is 60s. The thickness of the formed HMDS film is 4. The method for solving the problem of intra-grain line width uniformity according to claim 1, characterized in that: In sub-step S22, the temperature required for the coating is 23°C.
5. The method for solving the problem of intra-grain line width uniformity according to claim 1, characterized in that: In sub-step S23, a glue model is GKR5315, and the process of spin coating glue is as follows: 1.5mL glue solution is dripped into the center of each product sheet at 2050rpm. After the glue solution drips for 1.5s, each product sheet is rotated at 2200rpm for 35s. The final glue coating thickness is In sub-step S23, another glue model is DHK-BF511, and the process of spin coating glue is as follows: 1.5mL glue solution is dripped into the center of each product sheet at 2500rpm. After the glue solution is dripped for 2s, each product sheet is rotated at 2400rpm for 35s. The final glue coating thickness is 6. The method for solving the problem of intra-grain line width uniformity according to claim 1, characterized in that: In sub-step S24, the pre-baking temperature is 90° C. and the time is 60 seconds.
7. The method for solving the problem of intra-grain line width uniformity according to claim 1, characterized in that: The exposure of step S3 includes the following sub-steps: S31, cooling before exposure, each coated sheet after pre-baking is cooled in a cooling tank to the required exposure temperature of 23°C; S32, exposure, for two coated films, using the VOT612-010-BE plate with a layout design line width of 250±20nm and a Nikon S205C step-and-scan exposure machine. The step size in the X direction is 12949μm, the step size in the Y direction is 250389μm, and the exposure dose for each step-and-scan exposure is 29mj / cm 2 , the imaging focal length is 0.1 μm and the NA value is 0.60; S33, post-exposure baking, post-exposure baking is performed in a post-exposure baking process tank, the post-exposure baking temperature is 110° C., and the time is 120 seconds.
8. The method for solving the problem of intra-grain line width uniformity according to claim 1, characterized in that: The development of step S4 includes the following sub-steps: S41, cooling before development, cooling each exposed sheet after post-exposure baking in a cooling tank to the temperature required for development, 23°C; S42, developing, placing each exposed film that has been cooled before development on a turntable of a developing machine, dripping developer onto the center of each exposed film while rotating, and then flushing with water while rotating. The rotation is unidirectional and the rotation speed is 2000 rpm. A positive photoresist developer (model ZX-238) is used. The developing time is 60 seconds and the flushing time is 30 seconds. S43, post-baking in a post-baking process tank, the post-baking temperature is 110° C., and the time is 90 seconds.
9. The method for solving the problem of intra-grain line width uniformity according to claim 1, characterized in that: In step S5 , line width uniformity is observed under a line width scanning electron microscope.