Patterning method and photoresist structure

Abstract

The application relates to a patterning method and a photoresist structure, and relates to the technical field of semiconductor manufacturing. The patterning method comprises the following steps: forming a first patterned photoresist layer on the top surface of a substrate, wherein the first patterned photoresist layer comprises a plurality of glue columns arranged at intervals along a first direction parallel to the top surface of the substrate; the outer sidewall of the glue column comprises a plurality of undercut structures recessed towards the glue column along the first direction; forming a second initial photoresist layer covering the outer surfaces of the plurality of glue columns and having a top surface higher than the top surfaces of the plurality of glue columns; patterning the second initial photoresist layer to obtain a second photoresist layer covering the outer surfaces of the plurality of glue columns, wherein the second photoresist layer comprises an embedded part located in the recess. The resolution of the pattern can be improved, the photoresist layer with low cost can occupy a larger volume fraction of the target pattern column, and the cost of the photoetching material can be reduced.

Description

Technical Field

[0001] This application relates to the field of semiconductor manufacturing technology, specifically to a patterning method and a photoresist structure. Background Technology

[0002] Photolithography is a crucial step in semiconductor manufacturing, used to transfer circuit patterns onto a silicon wafer. In photolithography, a photoresist layer is used to transfer the pattern from a mask onto the wafer, thus forming the desired tiny patterns on the wafer.

[0003] In the fabrication of highly integrated, high-resolution devices, high-resolution photoresist layers are required to complete precise photolithography processes. However, high-resolution photoresist layers are expensive, and photoresist consumption is severe after mass production, increasing the cost of the photolithography process. Using low-cost photoresist layers would reduce the accuracy of photolithography, thereby reducing the electrical performance and reliability of the chip. Summary of the Invention

[0004] The purpose of this application is to provide a patterning method and a photoresist structure. A patterned structure is formed by coating a low-resolution photoresist layer with a high-resolution photoresist layer. During the photolithography process, the high-resolution photoresist layer coated on the outside of the low-resolution photoresist layer can be used to perform photolithography, which can improve the accuracy of photolithography and thus improve the electrical properties and reliability of the chip. By using the low-resolution photoresist layer to occupy a large volume fraction of the patterned structure, the cost of the photolithography process can be reduced.

[0005] To achieve the objectives of this application, the following technical solution is provided:

[0006] Firstly, this application provides a graphical method, including:

[0007] Provide substrate;

[0008] A first patterned photoresist layer is formed on the top surface of a substrate. The first patterned photoresist layer includes a plurality of photoresist pillars spaced apart along a first direction parallel to the top surface of the substrate. The outer wall of the photoresist pillars includes a plurality of undercut structures recessed toward the inside of the photoresist pillar along the first direction. The plurality of undercut structures surround the photoresist pillar. The target size of the recess is related to the target size of the photoresist pillar and the opening size of the recess.

[0009] After surface activation treatment of multiple photoresist pillars, a second initial photoresist layer is formed that covers the outer surface of the multiple photoresist pillars and has a top surface higher than the top surface of the multiple photoresist pillars.

[0010] A second initial photoresist layer is patterned to obtain a second photoresist layer covering the outer surface of a plurality of photoresist pillars. The photoresist pillars and the second photoresist layer on their outer surfaces are used to jointly form target pattern pillars. The plurality of target pattern pillars are arranged at intervals along a first direction. The second photoresist layer includes an embedded portion located in a recess. The target size of the photoresist pillar is greater than or equal to half the target size of the target pattern pillar. The target size includes the length along the first direction.

[0011] The patterning method of this application includes providing a substrate, and then forming a first patterned photoresist layer on the top surface of the substrate. The first patterned photoresist layer includes a plurality of photoresist pillars spaced apart along a first direction parallel to the top surface of the substrate. The outer walls of the photoresist pillars include a plurality of undercut structures recessed toward the inward of the photoresist pillars along the first direction. The plurality of undercut structures surround the photoresist pillars. The target size of the recess is related to the target size of the photoresist pillars and the opening size of the recess. After further performing surface activation treatment on the plurality of photoresist pillars, a second initial photoresist layer is formed covering the outer surface of the plurality of photoresist pillars and having a top surface higher than the top surface of the plurality of photoresist pillars. The cost of the second initial photoresist layer is higher than that of the first patterned photoresist layer, and the resolution of the second initial photoresist layer is higher than that of the first patterned photoresist layer. Finally, the second initial photoresist layer is patterned to obtain a plurality of target patterned pillars spaced apart along the first direction. The photoresist pillars and the second photoresist layer on their outer surfaces are used to jointly constitute the target patterned pillars. The second photoresist layer includes an embedded portion located in the recess. The target size of the photoresist pillars is greater than or equal to half of the target size of the target patterned pillars, and the target size includes the length along the first direction. Multiple target pattern pillars are formed by coating a low-resolution first patterned photoresist layer with a high-resolution second photoresist layer. During photolithography, using the high-resolution second initial photoresist layer improves lithography accuracy, pattern resolution, sidewall morphology, and etching resistance, thereby enhancing the chip's electrical properties and reliability. By utilizing a low-cost photoresist layer to occupy a larger volume fraction of the target pattern pillars, the cost of photolithography materials can be reduced. Furthermore, this reduces the performance and quality requirements of the first patterned photoresist layer in the photolithography process, thus expanding the applicability of photolithography materials. Multiple undercut structures on the outer walls of the pillars secure the embedding portion of the second photoresist layer, preventing detachment and increasing the stability of the layer nesting.

[0012] Furthermore, by setting the target size of the glue column to be greater than or equal to half the target size of the target graphic column, the target size including the length along the first direction, the complexity and cost of preparing the target graphic column are reduced.

[0013] Furthermore, by setting the target size of the undercut structure recess to be related to the target size of the adhesive pillar and the opening size of the recess, the stability of the adhesive pillar is avoided from being reduced due to an excessively large opening or excessively deep recess. In one embodiment, forming the first patterned photoresist layer includes:

[0014] A first photoresist layer is formed on the top surface of the substrate;

[0015] The first photoresist layer is exposed and developed to obtain a first patterned photoresist layer comprising a plurality of initial pillars spaced apart along a first direction;

[0016] Multiple initial columns are treated at a first temperature for a first preset time to remove free water;

[0017] Multiple initial columns, after being baked at a second temperature to remove free water, were used to obtain multiple glue columns with multiple undercut structures on their outer walls.

[0018] In one embodiment, the first temperature is 60°C-100°C.

[0019] In one embodiment, the first preset time is 60s-180s.

[0020] In one embodiment, the second temperature is 80°C-120°C.

[0021] In one embodiment, surface activation treatment is performed on a plurality of adhesive pillars, including:

[0022] Multiple gel columns are surface-activated using a target airflow with a third temperature and containing oxygen and / or ozone.

[0023] In one embodiment, the third temperature is 20°C-30°C.

[0024] In one embodiment, the target size of the depression is d∈[0.25m, 0.5m] and d∈[0.125n, 0.25n]; where m is the maximum opening size of the depression and n is the maximum target size of the adhesive column where the depression is located.

[0025] In one embodiment, the size of the developing region during the formation of the first patterned photoresist layer is larger than the size of the developing region during the patterning of the second photoresist layer.

[0026] In one embodiment, the interior angle α of the undercut structure is [15°, 60°].

[0027] In one embodiment, the thickness of the second photoresist layer is less than the thickness of the first patterned photoresist layer, and the thickness is the dimension along the direction perpendicular to the top surface of the substrate.

[0028] Secondly, this application also provides a photoresist structure, fabricated using any of the aforementioned patterning methods. The photoresist structure includes: a substrate, a first patterned photoresist layer, and a second photoresist layer. The first patterned photoresist layer is located on the top surface of the substrate and includes a plurality of photoresist pillars spaced apart along a first direction parallel to the top surface of the substrate. The outer walls of the photoresist pillars include a plurality of undercut structures recessed towards the pillar along the first direction. The plurality of undercut structures surround the respective photoresist pillar. The target size of the recess is related to the target size of the respective photoresist pillar and the opening size of the recess. The second photoresist layer covers the outer surfaces of the plurality of photoresist pillars. The photoresist pillars and the second photoresist layer on their outer surfaces together constitute a target patterned pillar. The plurality of target patterned pillars are spaced apart along the first direction. The second photoresist layer includes an embedded portion located within the recess. The target size of the photoresist pillar is greater than or equal to half the target size of the target patterned pillar, and the target size includes a length along the first direction.

[0029] The photoresist structure of this application includes a substrate, a first patterned photoresist layer, and a second photoresist layer. The first patterned photoresist layer is located on the top surface of the substrate and includes a plurality of photoresist pillars spaced apart along a first direction parallel to the top surface of the substrate. The outer walls of the photoresist pillars include a plurality of undercut structures recessed into the photoresist pillars along the first direction. The plurality of undercut structures surround the photoresist pillars. The target size of the recess is related to the target size of the photoresist pillar and the opening size of the recess. The second photoresist layer covers the outer surface of the plurality of photoresist pillars, and the photoresist pillars and the second photoresist layer on their outer surfaces are used to jointly form a target patterned pillar. The plurality of target patterned pillars are spaced apart along the first direction, and the second photoresist layer includes an embedded portion located in the recess. The target size of the photoresist pillar is greater than or equal to half of the target size of the target patterned pillar, and the target size includes the length along the first direction. By covering a low-resolution first patterned photoresist layer with a high-resolution second photoresist layer, the high-resolution second initial photoresist layer can improve the accuracy of photolithography, increase the resolution of the pattern, improve the sidewall morphology and etching resistance of the pattern, and thus improve the electrical properties and reliability of the chip. Using a low-cost photoresist layer to occupy a large volume fraction of the target pattern pillars can reduce the cost of photolithography materials. Furthermore, it can reduce the performance and quality requirements of the first patterned photoresist layer in the photolithography process, thereby expanding the applicability of photolithography materials. Multiple undercut structures on the outer wall of the photoresist pillars can fix the embedding portion of the second photoresist layer, preventing the second photoresist layer from detaching from the photoresist pillars and increasing the stability of the layer nesting.

[0030] In one embodiment, the target size of the depression is d∈[0.25m, 0.5m] and d∈[0.125n, 0.25n]; where m is the maximum opening size of the depression and n is the maximum target size of the adhesive column where the depression is located.

[0031] In one embodiment, the interior angle α of the undercut structure is [15°, 60°].

[0032] In one embodiment, the thickness of the second photoresist layer is less than the thickness of the first patterned photoresist layer, and the thickness is the dimension along the direction perpendicular to the top surface of the substrate.

[0033] In summary, this application provides a patterning method and a photoresist structure, the unexpected effects of which include:

[0034] The second photoresist layer includes an embedding portion located within the recess; the target size of the photoresist pillar is greater than or equal to half the target size of the target pattern pillar, and the target size includes its length along a first direction. By covering the low-resolution first patterned photoresist layer with a high-resolution second initial photoresist layer, the photolithography process can improve the accuracy of the photolithography, increase the resolution of the pattern, improve the sidewall morphology and etch resistance of the pattern, thereby improving the electrical properties and reliability of the chip. Using a low-cost photoresist layer to occupy a large volume fraction of the target pattern pillar can reduce the cost of the photolithography material. Furthermore, it can reduce the performance and quality requirements of the first patterned photoresist layer in the photolithography process, thereby expanding the applicability of the photolithography material. Multiple undercut structures on the outer sidewall of the photoresist pillar can fix the embedding portion of the second photoresist layer, preventing the second photoresist layer from detaching from the photoresist pillar and increasing the stability of the layer nesting.

[0035] Furthermore, by setting the target size of the glue column to be greater than or equal to half the target size of the target graphic column, the target size including the length along the first direction, the complexity and cost of preparing the target graphic column are reduced.

[0036] Furthermore, by setting the target size of the recessed structure of the glue column to be related to the target size of the glue column and the opening size of the recess, the stability of the glue column is reduced by avoiding the recess opening being too large or the recess being too deep. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of this disclosure, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a flowchart illustrating a graphical method provided in one embodiment;

[0039] Figure 2 This is a cross-sectional schematic diagram of the structure obtained in step S11 of a graphical method provided in one embodiment;

[0040] Figure 3 This is a cross-sectional schematic diagram of the structure obtained in step S12 of a graphical method provided in one embodiment;

[0041] Figure 4 This is a schematic diagram of the cross-sectional structure of the structure obtained in step S13 of a graphical method provided in one embodiment;

[0042] Figure 5 This is a schematic diagram of the cross-sectional structure of the structure obtained in step S14 of a graphical method provided in one embodiment;

[0043] Figure 6 This is a flowchart illustrating steps S121 to S124 of a graphical method provided in one embodiment;

[0044] Figure 7 This is a cross-sectional schematic diagram of the structure obtained in step S121 of a graphical method provided in one embodiment.

[0045] Explanation of reference numerals in the attached figures

[0046] 10. Substrate; 20. First patterned photoresist layer; 201. Photoresist pillar; 2011. Undercut structure; 202. First photoresist layer; 301. Second initial photoresist layer; 30. Second photoresist layer; 40. Target pattern pillar. Detailed Implementation

[0047] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate preferred embodiments of the application. However, this application may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0048] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application.

[0049] It should be understood that when an element or layer is referred to as "on," "adjacent to," "connected to," or "coupled to" other elements or layers, it may be directly on, adjacent to, connected to, or coupled to other elements or layers, or there may be intervening elements or layers. Conversely, when an element is referred to as "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" other elements or layers, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc., may be used to describe various elements, parts, regions, layers, doping types, and / or portions, these elements, parts, regions, layers, doping types, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, part, region, layer, doping type, or portion from another element, part, region, layer, doping type, or portion. Therefore, without departing from the teachings of this invention, the first element, component, region, layer, doping type, or portion discussed below may be represented as a second element, component, region, layer, or portion; for example, the first doping type may be referred to as the second doping type, and similarly, the second doping type may be referred to as the first doping type; the first doping type and the second doping type are different doping types, for example, the first doping type may be P-type and the second doping type may be N-type, or the first doping type may be N-type and the second doping type may be P-type.

[0050] Spatial relation terms such as “below,” “under,” “below,” “under,” “above,” “above,” etc., are used herein to describe the relationship between one element or feature shown in the figure and other elements or features. It should be understood that, in addition to the orientation shown in the figure, spatial relation terms also include different orientations of the device in use and operation. For example, if the device in the figure is flipped, the element or feature described as “below,” “under,” or “below” will be oriented “above” the other element or feature. Therefore, the exemplary terms “below” and “under” can include both above and below orientations. Furthermore, the device may also include other orientations (e.g., rotated 90 degrees or other orientations), and the spatial descriptive terms used herein will be interpreted accordingly.

[0051] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that when the terms “comprise” and / or “comprising” are used in this specification, the presence of the stated feature, integer, step, operation, element, and / or part is established, but the presence or addition of one or more other features, integers, steps, operations, elements, parts, and / or groups is not excluded. Meanwhile, when used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0052] Embodiments of the invention are described herein with reference to cross-sectional views illustrating ideal embodiments (and intermediate structures) of the invention, thus allowing for variations in the illustrated shape due to, for example, manufacturing techniques and / or tolerances. Therefore, embodiments of the invention should not be limited to the specific shapes of the regions shown herein, but rather include shape deviations due to, for example, manufacturing techniques. For instance, implantation regions shown as rectangular typically have rounded or curved features at their edges and / or implantation concentration gradients, rather than a binary change from implantation regions to non-implantation regions. Similarly, the buried regions formed by implantation can result in some implantation in the region between the buried region and the surface traversed during implantation. Therefore, the regions shown in the figures are substantially schematic, and their shapes do not represent the actual shapes of regions of the device and do not limit the scope of the invention.

[0053] Photolithography is a crucial step in semiconductor manufacturing, used to transfer circuit patterns onto a silicon wafer. In photolithography, a photoresist layer is used to transfer the pattern from a mask onto the wafer, thus forming the desired tiny patterns on the wafer.

[0054] In the fabrication of highly integrated, high-resolution devices, high-resolution photoresist layers are required to complete precise photolithography processes. However, high-resolution photoresist layers are expensive, and photoresist consumption is severe after mass production, increasing the cost of the photolithography process. Using low-cost photoresist layers would reduce the accuracy of photolithography, thereby reducing the electrical performance and reliability of the chip.

[0055] This application provides a graphical method; please refer to [link / reference]. Figure 1 The graphical method includes:

[0056] S11: Provides a substrate.

[0057] For example, please refer to Figure 2 The substrate 10 may include, but is not limited to, at least one of the following: silicon substrate, gallium nitride (GaN) substrate, silicon carbide (SiC) substrate, sapphire substrate, silicon on insulator (SOI) substrate, silicon on diamond (SOD) substrate, and strained silicon substrate deposited on germanium-silicon wafer.

[0058] S12: A first patterned photoresist layer is formed on the top surface of the substrate. The first patterned photoresist layer includes a plurality of photoresist pillars spaced apart along a first direction parallel to the top surface of the substrate. The outer wall of the photoresist pillar includes a plurality of undercut structures recessed toward the inside of the photoresist pillar along the first direction. The plurality of undercut structures surround the photoresist pillar. The target size of the recess is related to the target size of the photoresist pillar and the opening size of the recess.

[0059] It should be noted that you should refer to [link / reference]. Figure 3The longitudinal section of the multiple undercut structures 2011 recesses can be a triangle with its apex extending inward toward the adhesive pillar along a first direction. The apex of the triangle is the interior angle α of the undercut structure, where α ∈ [15°, 60°]. For example, the interior angle α can be 15°, 30°, 40°, 50°, or 60°. The multiple undercut structures on the outer wall of the adhesive pillar can fix the embedded portion of the second photoresist layer, preventing the second photoresist layer from detaching from the adhesive pillar. This improves the adhesion between the first patterned photoresist layer 20 and the second photoresist layer 30, increasing the stability of the adhesive layer nesting. In subsequent steps, the second photoresist layer 30 can fill the undercut structure recesses of the first patterned photoresist layer 20, thereby interlocking the first patterned photoresist layer 20 and the second photoresist layer 30, improving the bonding between the first patterned photoresist layer 20 and the second photoresist layer 30, and ensuring a tight fit between the first patterned photoresist layer 20 and the second photoresist layer 30.

[0060] S13: After surface activation treatment of multiple photoresist pillars, a second initial photoresist layer is formed that covers the outer surface of the multiple photoresist pillars and has a top surface higher than the top surface of the multiple photoresist pillars.

[0061] For example, please refer to Figure 4 A second initial photoresist layer 301 can be formed by using, but is not limited to, spin coating processes to cover the outer surface of multiple photoresist pillars 201 and with its top surface higher than the top surface of the multiple photoresist pillars 201. By setting the cost of the second initial photoresist layer 301 to be higher than the cost of the first patterned photoresist layer 20, and by utilizing the low-cost first patterned photoresist layer 20 to occupy a larger volume fraction of the target pattern pillars, the cost of photolithography materials can be reduced.

[0062] S14: Pattern the second initial photoresist layer to obtain a second photoresist layer covering the outer surface of a plurality of photoresist pillars. The photoresist pillars and the second photoresist layer on their outer surfaces are used to jointly form target pattern pillars. The plurality of target pattern pillars are arranged at intervals along a first direction. The second photoresist layer includes an embedded portion located in a recess. The target size of the photoresist pillar is greater than or equal to half the target size of the target pattern pillar. The target size includes the length along the first direction.

[0063] For example, please refer to Figure 5 The first direction is as follows Figure 5 The ox direction shown can be used, but is not limited to, exposure and development processes to pattern the second initial photoresist layer 301 to obtain a second photoresist layer 30 covering the outer surface of multiple photoresist pillars 201. The photoresist pillars 201 and the second photoresist layer 30 on their outer surfaces are used to jointly form the target pattern pillars 40. The multiple target pattern pillars 40 are arranged at intervals along the first direction.

[0064] It should be noted that the cost of the second initial photoresist layer 301 is higher than that of the first patterned photoresist layer 20. The resolution of the patterned second initial photoresist layer 301 is also better than that of the first patterned photoresist layer 20, which can improve the pattern resolution during the photolithography process. Furthermore, the second initial photoresist layer 301 can cover the defects at the edge of the pattern caused by development during the formation of the first photoresist layer 202, thereby improving the uniformity and accuracy of etching.

[0065] For example, the cost reduction achieved by the aforementioned embodiments of this application can be calculated using the following formula:

[0066] C1=Cexpensive•(1-RT%)•S•THK;

[0067] C2=[Ccheap•(1-RT%)•S•THK]c+[Cexpensive•(1-RT%)•S•THK)•(1-c);

[0068] Cost down≈C1-C2≈[(Ccheap-Cexpensive)•(1-RT%)•S•THK]•c.

[0069] RT% is the transmittance, THK is the photoresist thickness; S is the wafer area, Ccheap is the unit cost of the lower-cost photoresist, Cexpensive is the unit cost of the higher-cost photoresist, and c is the volume fraction of the lower-cost photoresist in the target pattern pillar.

[0070] For example, please continue to refer to Figures 2-5The patterning method of this application includes providing a substrate 10, and then forming a first patterned photoresist layer 20 on the top surface of the substrate 10. The first patterned photoresist layer 20 includes a plurality of photoresist pillars 201 spaced apart along a first direction parallel to the top surface of the substrate 10; the outer wall of the photoresist pillars 201 includes a plurality of undercut structures 2011 recessed toward the inward of the photoresist pillars 201 along the first direction; the plurality of undercut structures 2011 surround the photoresist pillars 201; the target size of the recess is related to the target size of the photoresist pillar 201 and the opening size of the recess; further, the plurality of... After the adhesive pillars 201 undergo surface activation treatment, a second initial photoresist layer 301 is formed, covering the outer surface of multiple adhesive pillars 201 and having a top surface higher than the top surface of multiple adhesive pillars 201. The cost of the second initial photoresist layer 301 is higher than the cost of the first patterned photoresist layer 20. Finally, the second initial photoresist layer 301 is patterned to obtain a second photoresist layer 30 covering the outer surface of the adhesive pillars 201. The adhesive pillars 201 and the second photoresist layer 30 on their outer surfaces are used to jointly constitute the target pattern pillars 40. Multiple target pattern pillars 40 are arranged at intervals along the first direction. Multiple target pattern pillars 40 are formed by coating a low-resolution first patterned photoresist layer 20 with a high-resolution second photoresist layer 30. During photolithography, using the high-resolution second initial photoresist layer 301 improves lithography accuracy, pattern resolution, sidewall morphology, and etching resistance, thereby enhancing the chip's electrical properties and reliability. By utilizing a low-cost photoresist layer that occupies a large volume fraction of the target pattern pillars, the cost of photolithography materials can be reduced. Furthermore, the performance and quality requirements of the first patterned photoresist layer 20 in the photolithography process can be lowered, thus expanding the applicability of photolithography materials. Multiple undercut structures 2011 on the outer sidewall of the pillars 201 can fix the embedding portion of the second photoresist layer 30, preventing the second photoresist layer 30 from detaching from the pillars 201 and increasing the stability of the layer nesting. In some embodiments, please refer to... Figure 6 The formation of the first patterned photoresist layer includes:

[0071] S121: A first photoresist layer is formed on the top surface of the substrate.

[0072] For example, please refer to Figure 7 The first photoresist layer 202 can be formed on the top surface of the substrate 10 using, but is not limited to, spin coating.

[0073] S122: Expose and develop the first photoresist layer to obtain a first patterned photoresist layer comprising a plurality of initial pillars spaced apart along a first direction.

[0074] As an example, the longitudinal cross-section of the multiple initial columns spaced apart along the first direction can be any shape with more than two sides, such as a triangle, quadrilateral, or pentagon, etc. Specifically, in this embodiment, the longitudinal cross-section of the initial column is a quadrilateral. The volume of the initial column can be designed according to the actual situation and actual cost.

[0075] S123: Use the first temperature to process multiple initial columns for a first preset time to remove free water.

[0076] It should be noted that during the development and exposure of the first photoresist layer 202, when the developer comes into contact with the photoresist, free water molecules may be present in the first photoresist layer 202. Free water molecules reduce the adhesion between the photoresist and the wafer surface and may also cause local deformation of the photoresist layer, thereby reducing the accuracy of the pattern.

[0077] S124: Multiple initial columns after removing free water are baked at a second temperature to obtain multiple glue columns with multiple undercut structures on the outer sidewall.

[0078] It should be noted that baking the multiple initial pillars at the second temperature to remove free water can solidify the initial pillars, stabilize the patterned first photoresist layer 202, promote sidewall smoothing, improve the sidewall roughness of the photoresist layer caused during the development process, make the sidewall of the photoresist layer smoother, and help improve the sidewall perpendicularity of the pattern.

[0079] For example, the second temperature is 80℃-120℃. For instance, the second temperature can be 80℃, 90℃, 100℃, 110℃, or 120℃, etc.

[0080] The patterning method in this embodiment forms a first photoresist layer 202 on the top surface of the substrate 10. The first photoresist layer 202 is inexpensive and can provide support for the expensive, high-resolution second photoresist layer 30. The first photoresist layer 202 is then exposed and developed to obtain a first patterned photoresist layer 20 comprising a plurality of initial pillars spaced at intervals along a first direction ox. The exposure and development of the first photoresist layer 202 provides a pattern that supports the second photoresist layer 30. Further processing the plurality of initial pillars at a first temperature for a first preset time removes free water, improving the adhesion between the initial pillars and the substrate 10, preventing local deformation of the initial pillars, and thus improving the accuracy of the pattern. Finally, the initial pillars after removing free water are baked at a second temperature to obtain multiple photoresist pillars 201 with multiple undercut structures 2011 on their outer walls. This can solidify the initial pillars, stabilize the patterned first photoresist layer 202, promote sidewall smoothing, and improve the roughness of the sidewalls of the first photoresist layer 202 caused during the development process. This makes the sidewalls of the first photoresist layer 202 smoother, helps improve the perpendicularity of the pattern sidewalls, and enhances the accuracy of the patterning method.

[0081] In some embodiments, the first temperature is 60°C-100°C; the first preset time is 60s-180s.

[0082] As an example, the first temperature is 60℃-100℃, for example, the first temperature can be 60℃, 70℃, 80℃, 90℃ or 100℃, and the first preset time is 60s-180s, for example, the first preset time can be 60s, 70s, 80s, 90s, 100s, 110s, 120s, 130s, 140s, 150s, 160s, 170s or 180s.

[0083] It should be noted that the first temperature can be set according to the material and characteristics of the first photoresist layer 202. During the removal of free water, it is important to ensure that the temperature of all parts of the first photoresist layer 202 is uniform to avoid local overheating or insufficient cooling, which could affect the integrity and consistency of the first photoresist layer 202. The first time can be set according to the thickness of the first photoresist layer 202 and the free water content. When the water content in the photoresist layer is high, the first time needs to be set to a longer period.

[0084] The patterning method in this embodiment removes free water from the first photoresist layer 202 by reasonably setting the first temperature and the first time, which can ensure efficient removal of free water from the first photoresist layer 202 and thus improve the accuracy of the patterning method.

[0085] In some embodiments, surface activation of a plurality of adhesive columns includes: surface activation of the plurality of adhesive columns using a target airflow having a third temperature and containing oxygen and / or ozone.

[0086] For example, please refer to Figure 3 By using a target airflow containing oxygen at a third temperature to perform surface activation treatment on multiple glue columns 201, the bound water of multiple glue columns 201 can be removed, thereby improving the wettability of the glue columns 201.

[0087] In another example, please refer to [link / reference]. Figure 3 By using a target airflow containing ozone at a third temperature to perform surface activation treatment on multiple glue columns 201, the bound water of the glue columns 201 can be removed, thereby improving the wettability of the glue columns 201.

[0088] In yet another example, please refer to [link / reference needed]. Figure 3 By using a target airflow with a third temperature and containing oxygen and ozone, the surface of multiple glue columns is activated, which can remove the bound water of glue column 201 and improve the wettability of glue column 201.

[0089] The patterning method provided in this application embodiment uses a target airflow with a third temperature and containing oxygen and / or ozone to perform surface activation treatment on multiple photoresist pillars 201. This can remove the bound water of the photoresist pillars 201 while improving the wettability of the photoresist pillars 201, thereby facilitating the subsequent coating of a second photoresist layer on the surface of the photoresist pillars 201 and making it easier to remove the photoresist pillars 201 in subsequent processes.

[0090] In some embodiments, the third temperature is 20°C-30°C.

[0091] As an example, the third temperature is 20℃-30℃, for example, the third temperature can be 20℃, 21℃, 22℃, 23℃, 24℃, 25℃, 26℃, 27℃, 28℃, 29℃ or 30℃.

[0092] The graphical method provided in this application embodiment activates the surface of the adhesive column 201 by reasonably setting a third temperature, which can excite plasma in a high-energy state. The plasma comes into contact with the surface of the adhesive column 201 to trigger a chemical reaction, thereby activating the surface of the adhesive column 201.

[0093] In some embodiments, please refer to Figure 5 The target size of the glue column 201 is greater than or equal to half the target size of the target graphic column 40; the target size includes the length along the first direction.

[0094] As an example, the target size of the adhesive column 201 is greater than or equal to half the target size of the target graphic column 40. For instance, the target size of the adhesive column 201 can be 0.5, 0.6, 0.7, 0.8 or 0.9 times the target size of the target graphic column, etc., to reduce the complexity and cost of the manufacturing process.

[0095] The patterning method provided in this application embodiment, by setting the target size of the photoresist pillar 201 to be greater than or equal to half the target size of the target pattern pillar 40, can ensure that the inexpensive first photoresist material occupies a larger volume fraction compared to the expensive second photoresist material, thereby reducing the cost of photoresist materials.

[0096] In some embodiments, the size of the developing region during the formation of the first patterned photoresist layer 20 is larger than the size of the developing region during the patterning of the second initial photoresist layer 301. This reduces the cost of preparing photoresist patterns by means of a multi-layer patterning process with nested photoresist layers, overcomes the process limitations of single-layer photoresist pillars, and meets the practical needs of various application scenarios.

[0097] It should be noted that the smaller the developing area size, the higher the graphic resolution can be achieved, which in turn allows for finer lines and tighter spacing.

[0098] As an example, the development area size during the formation of the first patterned photoresist layer 20 is larger than the development area size during the patterning of the second initial photoresist layer 301, which can result in a higher resolution for the patterned second photoresist layer 30.

[0099] The patterning method provided in this application embodiment, by setting the size of the developing area during the patterning of the second initial photoresist layer 301 to be smaller than the size of the developing area during the formation of the first patterned photoresist layer 20, can make the resolution of the patterned second photoresist layer 30 higher, and further improve the accuracy and reliability of the photolithography process.

[0100] In some embodiments, please refer to Figures 3-4 The interior angles a of the multiple undercut structures 2011 are in the range of [15°, 60°]. For example, the interior angles a can be 15°, 30°, 40°, 50°, or 60°, etc., to promote the interlocking between the first patterned photoresist layer 20 and the second photoresist layer 30, improve the bonding between the first patterned photoresist layer 20 and the second photoresist layer 30, and make the first patterned photoresist layer 20 and the second photoresist layer 30 fit tightly together.

[0101] In some embodiments, please continue reading Figures 3-4 The thickness of the second photoresist layer 30 on the top surface of the photoresist pillar 201 is less than the thickness of the photoresist pillar 201, and the thickness is the dimension along the direction perpendicular to the top surface of the substrate. The target size d of the undercut structure 2011 recess is ∈ [0.25m, 0.5m], and d ∈ [0.125n, 0.25n]; where m is the maximum opening size of the recess, n is the maximum target size of the photoresist pillar where the recess is located, and the target size is the length along the first direction. For example, the target size d of the undercut structure 2011 recess can be 0.25m, 0.3m, 0.35m, 0.4m, 0.45m, or 0.5m, etc.; the target size d of the undercut structure recess can be 0.125n, 0.2n, 0.24n, or 0.25n, etc. To avoid the opening of the undercut structure 2011 being too small, which would reduce the structural strength of the second photoresist layer 30 embedded in the recess of the undercut structure 2011; and to avoid the opening of the undercut structure 2011 being too large, which would reduce the structural strength of the photoresist pillar 201 itself.

[0102] In some embodiments, please refer to Figure 5 The multiple undercut structures 2011 on the outer wall of the photoresist pillar 201 can fix the embedded part of the second photoresist layer 30, prevent the second photoresist layer 30 from detaching from the photoresist pillar 201, and increase the stability of the photoresist layer nesting.

[0103] In some embodiments, please continue reading Figure 5By setting the target size of the photoresist pillar 201 to be greater than or equal to half the target size of the target pattern pillar 40, the target size includes the length along the first direction, reducing the complexity and cost of fabricating the target pattern pillar 40. The patterning method provided in this embodiment includes setting the outer wall of the photoresist pillar 201 to include multiple undercut structures 2011 recessed inwards along the first direction; the multiple undercut structures 2011 surround the photoresist pillar 201; the target size of the recess is related to the target size of the photoresist pillar 201 and the opening size of the recess. The undercut structures 2011 can increase the bonding between the first patterned photoresist layer 20 and the second photoresist layer 30, allowing for a tighter fit between them. The first patterned photoresist layer 20 and the second photoresist layer 30 together form a patterned structure, enabling more precise etching using the patterned structure in subsequent photolithography processes, thus improving the accuracy and reliability of the photolithography process.

[0104] This application provides a photoresist structure; please refer to [link / reference]. Figure 5 The photoresist structure is fabricated using any of the patterning methods described in the above embodiments. The photoresist structure includes: a substrate 10, a first patterned photoresist layer 20, and a second photoresist layer 30. The first patterned photoresist layer 20 is located on the top surface of the substrate 10. The first patterned photoresist layer 20 includes a plurality of photoresist pillars 201 arranged at intervals along a first direction ox parallel to the top surface of the substrate 10. The outer wall of the photoresist pillar 201 includes a plurality of undercut structures 2011 recessed inward along the first direction toward the photoresist pillar 201. The plurality of undercut structures 2011 surround the photoresist pillar 201. The target size of the recess is related to the target size of the photoresist pillar 201 and the opening size of the recess. The second photoresist layer 30 covers the outer surface of the plurality of photoresist pillars 201. The photoresist pillars 201 and the second photoresist layer 30 on their outer surfaces together constitute target pattern pillars 40. The plurality of target pattern pillars 40 are arranged at intervals along the first direction ox.

[0105] For example, please refer to Figure 2 The substrate 10 may include, but is not limited to, at least one of the following: silicon substrate, gallium nitride (GaN) substrate, silicon carbide (SiC) substrate, sapphire substrate, silicon on insulator (SOI) substrate, silicon on diamond (SOD) substrate, and strained silicon substrate deposited on germanium-silicon wafer.

[0106] It should be noted that the longitudinal section of the multiple undercut structures 2011 recesses can be a triangle with its apex extending inward toward the adhesive pillar along the first direction. The apex angle of the triangle is the interior angle α of the undercut structure, where α ∈ [15°, 60°]. In subsequent steps, the second photoresist layer 30 can fill the undercut structure recesses of the first patterned photoresist layer 20, thereby enabling the first patterned photoresist layer 20 and the second photoresist layer 30 to interlock, improving the bonding strength between the first patterned photoresist layer 20 and the second photoresist layer 30, and ensuring a tight fit between the first patterned photoresist layer 20 and the second photoresist layer 30.

[0107] It should be noted that the cost of the second photoresist layer 30 is higher than that of the first patterned photoresist layer 20. The resolution of the patterned second photoresist layer 30 is also better than that of the first patterned photoresist layer 20, which can improve the pattern resolution during the photolithography process. Furthermore, the second photoresist layer 30 can cover the defects at the edge of the pattern caused by development during the formation of the first photoresist layer, thereby improving the uniformity and accuracy of etching.

[0108] The photoresist structure of this application includes a substrate 10, a first patterned photoresist layer 20, and a second photoresist layer 30. The first patterned photoresist layer 20 is located on the top surface of the substrate 10 and includes a plurality of photoresist pillars 201 arranged at intervals along a first direction ox parallel to the top surface of the substrate 10. The outer wall of the photoresist pillar 201 includes a plurality of undercut structures 2011 recessed inward along the first direction toward the photoresist pillar 201. The plurality of undercut structures 2011 surround the photoresist pillar 201. The target size of the recess is related to the target size of the photoresist pillar 201 and the opening size of the recess. The second photoresist layer 30 covers the outer surface of the plurality of photoresist pillars 201. The photoresist pillars 201 and the second photoresist layer 30 on their outer surfaces together constitute target pattern pillars 40. The plurality of target pattern pillars 40 are arranged at intervals along the first direction ox. By covering the low-resolution first patterned photoresist layer 20 with a high-resolution second initial photoresist layer 301, the photolithography process can be improved by using the high-resolution second initial photoresist layer 301. This improves the accuracy of the photolithography, increases the resolution of the pattern, improves the sidewall morphology and etching resistance of the pattern, and thus improves the electrical properties and reliability of the chip. By using a low-cost photoresist layer to occupy a large volume fraction of the target pattern pillars, the cost of photolithography materials can be reduced. Furthermore, the performance and quality requirements of the first patterned photoresist layer 20 in the photolithography process can be reduced, thereby expanding the applicability of photolithography materials.

[0109] In some embodiments, please continue reading Figure 5 The target size of the glue column 201 is greater than or equal to half the target size of the target graphic column; the target size includes the length along the first direction.

[0110] It should be noted that the smaller the developing area size, the higher the graphic resolution can be achieved, which in turn allows for finer lines and tighter spacing.

[0111] As an example, the development area size during the formation of the first patterned photoresist layer 20 is larger than the development area size during the patterning of the second initial photoresist layer 301, which can result in a higher resolution for the patterned second photoresist layer 30.

[0112] The photoresist structure provided in this application embodiment, by setting the size of the developing area during the patterning of the second initial photoresist layer 301 to be smaller than the size of the developing area during the formation of the first patterned photoresist layer 20, can make the resolution of the patterned second photoresist layer 30 higher, and further improve the accuracy and reliability of the photolithography process.

[0113] In summary, the patterning method and photoresist structure provided in this application have the following unexpected technical effects:

[0114] The second photoresist layer includes an embedded portion located within the recess; the target size of the photoresist pillar is greater than or equal to half the target size of the target pattern pillar, and the target size includes its length along a first direction. By covering the low-resolution first patterned photoresist layer with a high-resolution second photoresist layer, the precision of the photolithography can be improved, the resolution of the pattern can be increased, the sidewall morphology and etch resistance of the pattern can be improved, thereby improving the electrical properties and reliability of the chip. By using a low-cost photoresist layer to occupy a large volume fraction of the target pattern pillar, the cost of the photolithography material can be reduced. Furthermore, the performance and quality requirements of the first patterned photoresist layer in the photolithography process can be reduced, thereby expanding the applicability of the photolithography material. Multiple undercut structures on the outer sidewall of the photoresist pillar can fix the embedded portion of the second photoresist layer, preventing the second photoresist layer from detaching from the photoresist pillar and increasing the stability of the photoresist layer nesting.

[0115] Furthermore, by setting the target size of the glue column to be greater than or equal to half the target size of the target graphic column, the target size including the length along the first direction, the complexity and cost of preparing the target graphic column are reduced.

[0116] Furthermore, by setting the target size of the recessed structure of the glue column to be related to the target size of the glue column and the opening size of the recess, the stability of the glue column is reduced by avoiding the recess opening being too large or the recess being too deep.

[0117] 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 of 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.

[0118] The embodiments described above are merely examples of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the protection scope of this application.

Claims

1. A graphical method, characterized in that, include: Provide substrate; A first photoresist layer is formed on the top surface of the substrate; The first photoresist layer is exposed and developed to obtain a first patterned photoresist layer comprising a plurality of initial pillars spaced apart along the first direction; the plurality of initial pillars are treated at 60℃-100℃ for a first preset time to remove free water; the plurality of initial pillars after removing free water are baked at 80℃-120℃ to obtain a plurality of photoresist pillars whose outer walls include a plurality of undercut structures recessed toward the initial pillars along the first direction; the plurality of undercut structures surround the photoresist pillars; the longitudinal section of the plurality of undercut structures is a triangle with its apex extending toward the photoresist pillar along the first direction; the apex angle of the triangle is the interior angle α of the undercut structure, and the interior angle α ∈ [15°, 60°]; the target size of the recess d ∈ [0.25m, 0.5m], and d ∈ [0.125n, 0.25n]; where m is the maximum opening size of the recess, and n is the maximum target size of the photoresist pillar containing the recess. A target airflow containing oxygen and / or ozone at 20°C-30°C is used to perform surface activation treatment on the plurality of photoresist pillars to improve their wettability, thereby forming a second initial photoresist layer that covers the outer surface of the plurality of photoresist pillars and has a top surface higher than the top surface of the plurality of photoresist pillars. The cost of the second initial photoresist layer is higher than that of the first patterned photoresist layer, and the resolution of the second initial photoresist layer is better than that of the first patterned photoresist layer, so that the first patterned photoresist layer occupies a larger volume fraction of the target patterned pillars, thereby reducing the cost of photolithography materials. The second initial photoresist layer is patterned to obtain a second photoresist layer covering the outer surface of the plurality of photoresist pillars. The photoresist pillars and the second photoresist layer on their outer surfaces are used to jointly form target pattern pillars. The plurality of target pattern pillars are arranged at intervals along the first direction. The second photoresist layer includes an embedding portion located in the recess to increase the stability of the photoresist layer nesting. The target size of the photoresist pillar is greater than or equal to half the target size of the target pattern pillar, and the target size includes the length along the first direction.

2. The graphical method according to claim 1, characterized in that, The first preset time is 60s-180s.

3. The graphical method according to claim 1, characterized in that, The surface activation treatment of the plurality of adhesive columns includes: The first unit cost of the material used in the first patterned photoresist layer is lower than the second unit cost of the material used in the second initial photoresist layer.

4. The graphical method according to claim 3, characterized in that, The volume fraction of the adhesive column in the target pattern column is configured such that the cost savings calculated based on the first unit cost, the second unit cost, the wafer area, the adhesive layer thickness, and the light transmittance are greater than zero.

5. The graphical method according to any one of claims 1-4, characterized in that, A spin coating process is used to form a second initial photoresist layer that covers the outer surface of the plurality of adhesive pillars and has a top surface higher than the top surface of the plurality of adhesive pillars.

6. The graphical method according to any one of claims 1-4, characterized in that, The size of the developing region during the formation of the first patterned photoresist layer is larger than the size of the developing region during the patterning of the second photoresist layer.

7. The graphical method according to any one of claims 1-4, characterized in that, The thickness of the second photoresist layer is less than the thickness of the first patterned photoresist layer, and the thickness is the dimension along the direction perpendicular to the top surface of the substrate.

8. A photoresist structure, characterized in that, The photoresist structure is prepared using the patterning method according to any one of claims 1-7, and comprises: Substrate; A first patterned photoresist layer is located on the top surface of the substrate. The first patterned photoresist layer includes a plurality of photoresist pillars spaced apart along a first direction parallel to the top surface of the substrate. The outer sidewall of each photoresist pillar includes a plurality of undercut structures recessed into the photoresist pillar along the first direction. The plurality of undercut structures surround the photoresist pillar. The longitudinal section of the plurality of undercut structures is a triangle with its apex extending into the photoresist pillar along the first direction. The apex angle of the triangle is the interior angle α of the undercut structure, and the interior angle α ∈ [15°, 60°]. The target size of the recess d ∈ [0.25m, 0.5m] and d ∈ [0.125n, 0.25n]. Wherein, m is the maximum opening size of the recess, and n is the maximum target size of the photoresist pillar containing the recess. A second photoresist layer covers the outer surface of the plurality of photoresist pillars. The photoresist pillars and the second photoresist layer on their outer surfaces are used to jointly form a target pattern pillar. The plurality of target pattern pillars are arranged at intervals along the first direction. The second photoresist layer includes an embedded portion located in the recess to improve the adhesion between the first patterned photoresist layer and the second photoresist layer. The target size of the photoresist pillar is greater than or equal to half the target size of the target pattern pillar, and the target size includes the length along the first direction. The cost of the second initial photoresist layer is higher than that of the first patterned photoresist layer, and the resolution of the second initial photoresist layer is better than that of the first patterned photoresist layer, so that the first patterned photoresist layer occupies a larger volume fraction of the target pattern pillar, thereby reducing the cost of the photolithography material.

9. The photoresist structure according to claim 8, characterized in that, The thickness of the second photoresist layer is less than the thickness of the first patterned photoresist layer, and the thickness is the dimension along the direction perpendicular to the top surface of the substrate.

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