Method for solving photoetching morphology abnormity
By performing value compensation on the imaging focal length of the exposure equipment and establishing the correspondence between focal length and morphology, the problem of excessive white edges on the lines in lithography was solved, achieving a more effective and lower-cost solution to lithography morphology anomalies, and improving the three-dimensional contour accuracy and yield of lithographic patterns.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ANHUI JINGWEI TECHNOLOGY CO LTD
- Filing Date
- 2026-03-13
- Publication Date
- 2026-05-12
AI Technical Summary
In existing technologies, excessive white edges on lines lead to abnormal lithographic morphology, and existing solutions are complex and costly.
By adding a value to the imaging focal length of the exposure equipment, the correspondence between the imaging focal length and the morphology of the standard card is established. The FEM data is used to determine whether the large white edge of the line is caused by the fluctuation of the imaging focal length. The equipment parameters are adjusted first to solve the abnormal lithographic morphology.
It effectively reduces the complexity and cost of lithographic anomalies, prioritizes adjusting equipment parameters to solve the problem of excessive white edges on lines, and improves the three-dimensional contour accuracy and yield of lithographic patterns.
Smart Images
Figure CN122018246A_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to the semiconductor field, and more specifically to a solution for photolithographic anomalies. Background Technology
[0002] In semiconductor manufacturing, photolithography is one of the key technologies for integrated circuits. Photolithography generally includes resist coating, exposure, and development. After development, the results of the photolithography are typically observed under a scanning electron microscope, especially the lithographic morphology. The lithographic morphology refers to the three-dimensional contour features of the pattern formed by photolithography. The white edges of the lines in the three-dimensional contour are one such morphological feature. These white edges reflect the verticality of the sidewalls or the flatness of the sidewalls in the vertical direction. Reducing the white edges is crucial for improving the accuracy and yield of the three-dimensional contour of the photolithographic pattern.
[0003] In production, excessive white edges on lines are considered abnormal photolithography morphology, which stems from several main factors, including environment, equipment, materials, and process parameters. Therefore, further in-depth research is needed to provide solutions for production. Summary of the Invention
[0004] In view of the problems existing in the background art, one object of this disclosure is to provide a solution to the lithographic anomaly, which can provide a solution to the lithographic anomaly of excessive white edges on lines.
[0005] Another objective of this disclosure is to provide a solution to lithographic anomalies that can be resolved more effectively and at a lower cost.
[0006] Therefore, a solution to photolithography anomalies includes the following steps: S1, providing a product wafer before photolithography; S2, coating, exposing, and developing the product wafer, wherein the product wafer is patterned using a two-dimensional array of grains distributed along the X and Y directions and exposed using FEM data. In the FEM data, the exposure dose is constant, and the imaging focal length along the X or Y direction is taken as the normal imaging focal length F of the grain at the center of the product wafer and varies with the grain by a fixed step size ΔF. When the imaging focal length changes in the X direction, it increases from left to right; when the imaging focal length changes in the Y direction, it increases from top to bottom; S3, observing the developed product wafer. S4. Based on the same part of the same die at the same location on the product wafer, compare the observed morphology with the morphology of the standard card at the same normal imaging focal length. If the observed white edge of the line is greater than the specified value compared with the white edge of the line at the same normal imaging focal length on the standard card, it indicates that the photolithography morphology is abnormal. Otherwise, the photolithography morphology is normal and the process parameters for coating, exposure, and development in step S2 are used for subsequent production. S5. If the photolithography morphology is determined to be abnormal in step S4, the observed white edge of the line is mapped to the white edge of the line at a larger normal imaging focal length on the standard card and the larger normal imaging focal length F´ is determined. S6. The larger normal imaging focal length F´ is determined. S7. Subtract the normal imaging focal length F from the normal imaging focal length F in step S2 to obtain the normal imaging focal length difference. The negative value of the normal imaging focal length difference is the complement of the imaging focal length. S8. Add the complement of the imaging focal length to the exposure equipment so that the actual normal imaging focal length of the equipment after complement is the sum of the normal imaging focal length F in step S2 and the complement of the imaging focal length. S9. Provide another product wafer before photolithography. S10. Coat, expose, and develop the other product wafer, wherein the exposure equipment has been complemented based on the normal imaging focal length in step S7, and the die at the center of the product wafer is the actual normal imaging focal length of the equipment after complement. The morphology of the pattern on the other product wafer; S11, based on the same part of the same position of the grain on the other product wafer, the observed morphology is compared with the morphology of the standard card at the same normal imaging focal length as the actual normal imaging focal length. If the white edge of the observed line is still greater than the specified value compared with the white edge of the line at the same normal imaging focal length as the standard card, it indicates that the photolithography morphology is still abnormal and the solution to the abnormal photolithography morphology has failed. It is necessary to solve it from other aspects of the photolithography process. Otherwise, it indicates that the photolithography morphology has returned to normal. The process parameters of coating, exposure and development in step S9 are used for subsequent production.
[0007] The beneficial effects of this disclosure are as follows: In the solution to lithographic anomalies according to this disclosure, a standard card establishes a correspondence between different normal imaging focal lengths and morphologies. This correspondence is applicable to the process of determining the process window through FEM. Combined with the compensation value on the normal imaging focal length, it is possible to determine from the perspective of the exposure equipment parameters - normal imaging focal length whether the excessive white edge of the lines (i.e., exceeding the specified value) is caused by fluctuations in the normal imaging focal length. This provides a solution for the lithographic anomaly of excessive white edge of lines. Furthermore, if it is determined from the perspective of the exposure equipment parameters - normal imaging focal length that the excessive white edge of the lines is caused by fluctuations in the normal imaging focal length, the complexity of exploring solutions to this lithographic anomaly from a process perspective can be reduced. In other words, prioritizing a solution from the equipment perspective is more effective and less costly than a solution from a process perspective. Therefore, the solution to lithographic anomalies according to this disclosure can solve lithographic anomalies more effectively and at a lower cost. Attached Figure Description
[0008] Figure 1 It is a schematic diagram of the structural relationship between the mask, the product wafer, and the grain.
[0009] Figure 2 These are photographs of product wafers with abnormal lithographic morphology observed under a wide-area scanning electron microscope.
[0010] Figure 3 These are standard cards for the morphology under different normal imaging focal lengths.
[0011] Figure 4 It is the control interface of the machine for exposure before the normal imaging focal length is compensated.
[0012] Figure 5 It is the control interface of the machine for exposure after the normal imaging focal length is compensated.
[0013] Figure 6 This is a photograph of a product wafer with its lithographic morphology restored to normal, observed under a wide-area scanning electron microscope. Detailed Implementation
[0014] It will be understood that the disclosed embodiments are merely examples of this disclosure, which can be implemented in various forms. Therefore, the specific details disclosed herein should not be construed as limiting, but are intended only as the basis for the claims and as an illustrative basis to teach those skilled in the art how to implement this disclosure in various ways.
[0015] [Solutions to Photolithographic Morphology Anomalies] Reference Figures 1 to 6 The solution to photolithographic morphology anomalies according to this disclosure includes the following steps: S1 provides a product wafer before photolithography; S2, the product sheet is coated with adhesive, exposed, and developed. During exposure, a two-dimensional array of grains distributed along the X and Y directions is used to construct the product sheet layout (i.e., a mask), and FEM (Focus Energy Matrix) data is used for exposure. In the FEM data, the exposure dose is constant, and the imaging focal length along the X or Y direction is based on the grain at the center of the product sheet as the normal imaging focal length F, which varies with the grain by a fixed step size ΔF. When the imaging focal length changes in the X direction, it increases from left to right; when the imaging focal length changes in the Y direction, it increases from top to bottom (e.g., ...). Figure 1 (as shown) S3, observe the morphology of the developed product sheet (e.g., Figure 2 (as shown) S4, based on the same location of the grains at the same position on the product wafer, compares the observed morphology with a standard card (such as...). Figure 3 A comparison of the morphology at the same normal imaging focal length (as shown) is made. If the observed white edge of the line is greater than a specified value compared to the white edge of the line at the same normal imaging focal length on the standard card (e.g., ...), the morphology is compared. Figure 2 If the photolithography morphology is normal, it indicates an abnormal photolithography morphology. Conversely, if the photolithography morphology is normal, the process parameters for coating, exposure, and development in step S2 are used for subsequent production. S5, In the case of photolithography anomaly determined in step S4, the observed white line edge is mapped to the white line edge of the standard card at a larger normal imaging focal length and the larger normal imaging focal length F´ is determined. S6, subtract the normal imaging focal length F from the larger normal imaging focal length F in step S2 to obtain the normal imaging focal length difference. The negative value of the normal imaging focal length difference is the complement of the imaging focal length. S7, the compensated value of the imaging focal length is added to the exposed equipment so that the actual normal imaging focal length of the equipment after compensation is the sum of the normal imaging focal length F in step S2 and the compensated value of the imaging focal length (e.g., Figure 4 and Figure 5 (as shown) S8 provides another product wafer before photolithography; S9, the other product sheet is coated with adhesive, exposed and developed, wherein the exposure machine has been compensated for the normal imaging focal length based on step S7, and the grain at the center of the product sheet is the actual normal imaging focal length of the machine after compensation. S10, observe the morphology of the pattern on the other product sheet after development (e.g., Figure 6 (as shown) S11, based on the same location of the same part of the grain at the same position on the other product wafer, compare the observed morphology with the morphology of the standard card at the same normal imaging focal length. If the observed white edge of the line is still greater than the specified value compared with the white edge of the line at the same normal imaging focal length on the standard card, it indicates that the photolithographic morphology is still abnormal, and the solution to the abnormal photolithographic morphology has failed. It is necessary to solve the problem from other aspects of the photolithography process. Conversely, it indicates that the photolithographic morphology has returned to normal (e.g., Figure 6 As shown in the figure, the process parameters for coating, exposure, and development in step S9 are used for subsequent production.
[0016] In the solution to lithographic anomalies according to this disclosure, a standard card establishes a correspondence between different normal imaging focal lengths and morphologies. This correspondence is applicable to the process of determining the process window through FEM. Combined with the compensation value on the normal imaging focal length, it is possible to determine from the perspective of the exposure equipment parameters minus the normal imaging focal length whether the excessive white edge of the lines (i.e., exceeding a specified value) is caused by fluctuations in the normal imaging focal length. This provides a solution for the lithographic anomaly of excessive white edge of lines. Furthermore, if it is determined from the perspective of the exposure equipment parameters minus the normal imaging focal length that the excessive white edge of the lines is caused by fluctuations in the normal imaging focal length, the complexity of exploring solutions to this lithographic anomaly from a process perspective can be reduced. In other words, prioritizing a solution from the equipment perspective is more effective and less costly than a solution from a process perspective. Therefore, the solution to lithographic anomalies according to this disclosure can solve lithographic anomalies more effectively and at a lower cost.
[0017] In steps S1 and S8, in one example, the product wafer is an 8-inch diameter wafer with a 150 Å thick SIN film coating on its surface. However, this is not the only possibility; the surface condition and size of the product wafer can vary depending on actual production requirements. Furthermore, various functional layers may be present beneath the SIN film, depending on the product requirements.
[0018] In steps S2 and S9, in one example, the coating process includes the following sub-steps: Sa, HMDS film formation, where an HMDS film is formed on the surface of the product sheet using a vapor phase method; Sb, pre-coating cooling, where the product sheet with the HMDS film on its surface is cooled in a cooling bath to the temperature required for coagulation; Sc, coating, where the product sheet is spin-coated in a coagulation process tank; and Sd, pre-baking, where the spin-coated product sheet is pre-baked in a pre-baking process tank. Specifically, in one example, in sub-step Sa, the operation of forming the HMDS film using a vapor phase method involves placing the product sheet on a stage in a vacuum chamber and heating the stage to 110°C. Nitrogen is used as the carrier gas at a pressure of 25 kPa. HMDS vapor carried by nitrogen is introduced, the pressure in the vacuum chamber is maintained at 20 Pa, and the time for introducing the HMDS vapor carried by nitrogen is 60 s. The thickness of the formed HMDS film is 6 Å. Specifically, in one example, in sub-step Sb, the temperature required for coagulation is 23°C. Specifically, in one example, in sub-step Sc, the spin coating process is as follows: 1.5 mL of adhesive solution is dropped onto the center of the product sheet at a dynamic speed of 2050 rpm. After the adhesive solution is dropped completely in 1.5 seconds, the product sheet is rotated at 3180 rpm for 30 seconds, resulting in a final coating thickness of 5350 Å. Specifically, in one example, in sub-step Sc, the adhesive type is AR80-4CP. Specifically, in one example, in sub-step Sd, the pre-baking temperature is 90°C, and the time is 60 seconds.
[0019] In steps S3 and S10, in one example, the morphology is observed using a linewidth scanning electron microscope.
[0020] The standard cards for steps S4 and S11 can be collected and established during production. The specified values for steps S4 and S11 are determined based on actual production requirements, such as the ratio of the white edge of the line to the corresponding line width being greater than a certain value (e.g., but not limited to 5%).
[0021] In step S7, in one example, refer to Figure 4 and Figure 5 The normal imaging focal length F and its complement are determined through the offset and calib.offset(AIS) input fields under Wafer Focusing in the ADJUST machine parameters window of the exposure machine's control interface. Offset corresponds to the normal imaging focal length F, and calib.offset(AIS) corresponds to the complement of the normal imaging focal length.
[0022] In steps S2 and S9, in one example, the exposure includes the following sub-steps: Si, pre-exposure cooling, where the pre-baked product sheet coated with adhesive is cooled in a cooling bath to the required exposure temperature of 23°C; Si, exposure, using a photomask (i.e., mask) VOT612-005-BA and a Nikon SF120 machine for step exposure, with a step size of 12949 μm in the X direction and 250389 μm in the Y direction, and an exposure dose of 500 mJ / cm for each step exposure. 2 And the NA value is 0.62, the normal imaging focal length is 1.2μm in step S2 or the actual normal imaging focal length determined by the supplementary value -0.3μm in step S9; Siii, post-exposure baking, post-exposure baking is carried out in the post-exposure baking process tank, the temperature of post-exposure baking is 110℃ and the time is 120s.
[0023] In steps S2 and S9, in one example, development includes the following sub-steps: S1, pre-development cooling, where the exposed and baked product sheet is cooled in a cooling bath to the temperature required for development, 23°C; SII, development, where the pre-development cooled product sheet is placed on the turntable of the developing machine, and while rotating, developer is dripped onto the center of the product sheet, followed by rinsing with water while rotating. The rotation is unidirectional, the rotation speed is 2000 rpm, positive photoresist developer is used, the developer type is ZX-238, the development time is 60s, and the rinsing time is 30s; SIII, post-baking in a post-baking process tank, the post-baking temperature is 110°C, and the time is 90s.
[0024] [test] Example 1 Example 1 uses the following steps: S1 provides a product wafer before photolithography. This product wafer is an 8-inch diameter wafer with a 150Å thick SIN film coating on its surface. S2, the product sheet is coated with adhesive, exposed, and developed. During exposure, the product sheet is patterned using a two-dimensional array of grains distributed along the X and Y directions, and exposed using FEM data. In the FEM data, the exposure dose is constant, and the imaging focal length along the Y direction is the normal imaging focal length F (F = 1.2 μm) with the grain at the center of the product sheet, and varies with the grain by a fixed step size ΔF (ΔF = 0.3 μm). The imaging focal length along the Y direction increases from top to bottom. Figure 1 As shown; S3, observe the morphology of the developed product sheet, such as... Figure 2 As shown, the morphology was observed using a linewidth scanning electron microscope; S4, based on the same location of the grains at the same position on the product wafer (taking the grains at the center of the product wafer), compare the observed morphology with a standard card (such as...). Figure 3A comparison of the morphology at the same normal imaging focal length (i.e., 1.2 μm) of the standard card shows that the white edge of the line is greater than the specified value (the ratio of the white edge of the line to the corresponding line width is 5%), indicating that the lithographic morphology is abnormal. S5, if the lithographic morphology is determined to be abnormal in step S4, the observed white edge of the line is mapped to the white edge of the line of the standard card at a larger normal imaging focal length and the larger normal imaging focal length F´ (i.e. F´ is 1.5μm) is determined. S6, subtract the normal imaging focal length F (i.e. 1.5μm-1.2μm) from the larger normal imaging focal length F´ to obtain the normal imaging focal length difference (i.e. 1.5μm-1.2μm=0.3μm). The negative value of the normal imaging focal length difference (i.e. -0.3μm) is the complement value of the imaging focal length. S7, the compensated value of the imaging focal length is added to the exposed equipment so that the actual normal imaging focal length of the equipment after compensation is the sum of the normal imaging focal length F in step S2 and the compensated value of the imaging focal length (i.e., 1.2μm + (-0.3μm) = 0.9μm). Figure 4 and Figure 5 As shown, Figure 4 This is the control interface of the machine for exposure before image compensation at the normal imaging focal length. Figure 5 It is the control interface of the machine tool for exposure after the normal imaging focal length is compensated; S8 provides another product wafer before photolithography. Similarly, the other product wafer is an 8-inch diameter wafer with a 150Å thick SIN film coating on its surface. S9, the other product sheet is coated with adhesive, exposed and developed, wherein the exposure machine has been compensated for the normal imaging focal length in step S7 and the grain at the center of the product sheet is the actual normal imaging focal length of the machine after compensation (that is, the exposure machine will use 0.9μm as the normal imaging focal length for exposure). S10, observe the morphology of the pattern on the other product sheet after development, such as... Figure 6 As shown, the morphology was observed using a linewidth scanning electron microscope; S11, based on the same location of the grain at the same position on the other product sheet (taking the grain at the center of the product sheet), the observed morphology is compared with a standard card (such as...). Figure 3 Comparing the morphology of the standard card at the same normal imaging focal length (i.e., 0.9μm) as shown, it was observed that the white edge of the lines was lower than the specified value (the ratio of the white edge of the lines to the corresponding line width was 5%). This indicates that the photolithographic morphology has returned to normal, and the process parameters for coating, exposure, and development in step S9 are used for subsequent production. in, In steps S2 and S9, the adhesive application is performed using the following sub-steps: Sa, HMDS film formation: An HMDS film is formed on the surface of the product sheet using a vapor phase method. The operation of forming the HMDS film using the vapor phase method is as follows: The product sheet is placed on the stage of the vacuum chamber and the stage is heated to 110°C. Nitrogen is used as the carrier gas and the pressure of the nitrogen is 25 kPa. HMDS vapor carried by nitrogen is introduced. The pressure of the vacuum chamber is maintained at 20 Pa. The time for introducing HMDS vapor carried by nitrogen is 60 s. The thickness of the formed HMDS film is 6 Å. Sb, pre-coating cooling: The product sheet with HMDS film formed on the surface is cooled in a cooling bath to the temperature required for coagulation, wherein the temperature required for coagulation is 23°C. Sc, Coating, The product sheet is spin-coated in a spin coating process tank. The spin coating process is as follows: 1.5 mL of adhesive solution is dropped onto the center of the product sheet at a dynamic speed of 2050 rpm. After the adhesive solution is dropped completely in 1.5 s, the product sheet is rotated at 3180 rpm for 30 s. The final coating thickness is 5350 Å. The adhesive type is AR80-4CP. Sd, pre-baking, the product sheet after spin coating is pre-baked in the pre-baking process tank, where the pre-baking temperature is 90℃ and the time is 60s; In step S7, refer to Figure 4 and Figure 5 The normal imaging focal length F and the complement of the normal imaging focal length are determined through the offset and offset calibration (calib.offset(AIS)) input fields under WaferFocusing in the ADJUST machine parameters window of the exposure machine's control interface. In steps S2 and S9, the exposure employs the following sub-steps: Si, cooling before exposure: the pre-baking product sheet coated with adhesive is cooled in a cooling bath to the temperature required for exposure, 23°C. Sii exposure was performed using a VOT612-005-BA photomask and a Nikon SF120 exposure unit with step exposures. The step size was 12949 μm in the X direction and 12949 μm in the Y direction. The exposure dose per step was 500 mJ / cm². 2 Furthermore, the NA value is 0.62, the normal imaging focal length in step S2 is 1.2 μm, and the actual normal imaging focal length determined by the supplementary value of -0.3 μm in step S9 is the normal imaging focal length (i.e. 0.9 μm). Siii, Post-exposure baking: Post-exposure baking is carried out in a post-exposure baking process tank at a temperature of 110℃ for 120 seconds. In steps S2 and S9, the development process includes the following sub-steps: SI, pre-development cooling, involves cooling the exposed and baked product sheet in a cooling bath to the temperature required for development, 23°C. SII, Development: The product sheet, cooled before development, is placed on the turntable of the developing machine. While rotating, developer is dripped onto the center of the product sheet. Then, while rotating, water is rinsed. The rotation is unidirectional and the rotation speed is 2000 rpm. Positive cortical developer is used. The developer type is ZX-238. The development time is 60 seconds and the rinsing time is 30 seconds. SIII, post-drying in the post-drying process tank, the post-drying temperature is 110℃ and the time is 90s.
[0025] Several exemplary embodiments have been described in detail above, but this document is not intended to limit itself to the explicitly disclosed combinations. Therefore, unless otherwise stated, the various features disclosed herein can be combined to form several other combinations, which are not shown for simplicity.
Claims
1. A solution to photolithographic anomalies, characterized in that, Including the following steps: S1 provides a product wafer before photolithography; S2, the product sheet is coated with adhesive, exposed and developed. During exposure, the product sheet is patterned using a two-dimensional array of grains distributed along the X and Y directions and exposed using FEM data. In the FEM data, the exposure dose is constant, and the imaging focal length along the X or Y direction is the normal imaging focal length F with the grain at the center of the product sheet and changes with a fixed step size ΔF. When the imaging focal length changes in the X direction, the imaging focal length increases from left to right, and when the imaging focal length changes in the Y direction, the imaging focal length increases from top to bottom. S3, observe the morphology of the developed product sheet; S4. Based on the same part of the same die at the same location on the product wafer, compare the observed morphology with the morphology under the same normal imaging focal length of the standard card. If the white edge of the observed line is greater than the specified value compared with the white edge of the line under the same normal imaging focal length of the standard card, it indicates that the photolithography morphology is abnormal. Otherwise, the photolithography morphology is normal and the process parameters of coating, exposure and development in step S2 are used for subsequent production. S5, In the case of photolithography anomaly determined in step S4, the observed white line edge is mapped to the white line edge of the standard card at a larger normal imaging focal length and the larger normal imaging focal length F´ is determined. S6, subtract the normal imaging focal length F from the larger normal imaging focal length F in step S2 to obtain the normal imaging focal length difference. The negative value of the normal imaging focal length difference is the complement of the imaging focal length. S7, add the compensation value of the imaging focal length to the exposed machine, so that the actual normal imaging focal length of the machine after compensation is the sum of the normal imaging focal length F in step S2 and the compensation value of the imaging focal length. S8 provides another product wafer before photolithography; S9, the other product sheet is coated with adhesive, exposed and developed, wherein the exposure machine has been compensated for the normal imaging focal length based on step S7, and the grain at the center of the product sheet is the actual normal imaging focal length of the machine after compensation. S10, observe the morphology of the pattern on the other product sheet after development; S11, based on the same part of the same die at the same location on the other product wafer, compare the observed morphology with the morphology of the standard card at the same normal imaging focal length as the actual normal imaging focal length. If the white edge of the observed line is still greater than the specified value compared with the white edge of the line at the same normal imaging focal length as the standard card, it indicates that the photolithography morphology is still abnormal and the solution to the abnormal photolithography morphology has failed. It is necessary to solve the problem from other aspects of the photolithography process. Conversely, it indicates that the photolithography morphology has returned to normal. The process parameters for coating, exposure and development in step S9 are used for subsequent production.
2. The solution to photolithographic morphology anomalies according to claim 1, characterized in that, In steps S1 and S8, The product is an 8-inch diameter wafer with a 150Å thick SIN film coating on its surface.
3. The solution to photolithographic morphology anomalies according to claim 1, characterized in that, In steps S2 and S9, Applying adhesive includes the following sub-steps: Sa, HMDS film formation: HMDS film is formed on the surface of the product sheet using a vapor phase method; Sb, pre-coating cooling: The product sheet with an HMDS film formed on its surface is cooled in a cooling bath to the temperature required for coagulation. Sc, coating, refers to the process of spin coating a product sheet onto a coating tank. Sd, pre-baking, the product sheet after spin coating and uniform coating is pre-baked in the pre-baking process tank.
4. The solution to photolithographic morphology anomalies according to claim 3, characterized in that, In substep Sa, The operation of forming HMDS film by gas phase is as follows: the product sheet is placed on the stage of the vacuum chamber and the stage is heated to 110°C. Nitrogen is used as the carrier gas and the pressure of nitrogen is 25 kPa. HMDS vapor carried by nitrogen is introduced. The pressure of the vacuum chamber is maintained at 20 Pa and the time for introducing HMDS vapor carried by nitrogen is 60 s. The thickness of the formed HMDS film is 6 Å.
5. The solution to photolithographic morphology anomalies according to claim 3, characterized in that, In sub-step Sb, the temperature required for homogenization is 23°C.
6. The solution to photolithographic morphology anomalies according to claim 3, characterized in that, In sub-step Sc, the spin coating process is as follows: 1.5 mL of adhesive solution is dropped onto the center of the product sheet at a dynamic speed of 2050 rpm. After the adhesive solution is dropped in 1.5 s, the product sheet is rotated at 3180 rpm for 30 s, and the final coating thickness is 5350 Å. In sub-step Sc, the adhesive type is AR80-4CP; In sub-step Sd, the pre-baking temperature is 90℃ and the time is 60s.
7. The solution to photolithographic morphology anomalies according to claim 1, characterized in that, In step S7, the normal imaging focal length F and the complement of the normal imaging focal length are obtained through the offset and offset calibration input fields under Wafer Focusing in the ADJUST machine parameters window of the exposure machine control interface.
8. The solution to photolithographic morphology anomalies according to claim 3, characterized in that, In steps S2 and S9, Exposure includes the following sub-steps: Si, cooling before exposure: the pre-baking product sheet coated with adhesive is cooled in a cooling bath to the temperature required for exposure, 23°C. Sii exposure was performed using a VOT612-005-BA photomask and a Nikon SF120 exposure unit with step exposures. The step size was 12949 μm in the X direction and 12949 μm in the Y direction. The exposure dose per step was 500 mJ / cm². 2 Furthermore, the NA value is 0.62, and the normal imaging focal length is 1.2μm in step S2 or the actual normal imaging focal length determined by the supplementary value -0.3μm in step S9. Siii, Post-exposure baking: Post-exposure baking is performed in a post-exposure baking process tank at a temperature of 110℃ for 120 seconds.
9. The solution to photolithographic morphology anomalies according to claim 8, characterized in that, In steps S2 and S9, Development includes the following sub-steps: SI, pre-development cooling, involves cooling the exposed and baked product sheet in a cooling bath to the temperature required for development, 23°C. SII, Development: The product sheet, cooled before development, is placed on the turntable of the developing machine. While rotating, developer is dripped onto the center of the product sheet. Then, while rotating, water is rinsed. The rotation is unidirectional and the rotation speed is 2000 rpm. Positive cortical developer is used. The developer type is ZX-238. The development time is 60 seconds and the rinsing time is 30 seconds. SIII, post-drying in the post-drying process tank, the post-drying temperature is 110℃ and the time is 90s.
10. The solution to photolithographic morphology anomalies according to claim 1, characterized in that, In steps S3 and S10, the morphology is observed using a linewidth scanning electron microscope.