Photoetching method

Abstract

The invention relates to a photoetching method, and relates to the technical field of semiconductor preparation, in the photoetching method, after a first photoresist on a to-be-processed substrate is removed, a first surface needs to be cleaned, and the first surface has hydrophilicity when being cleaned, so that the adhesiveness between the subsequent photoresist and the to-be-processed substrate is influenced, and therefore, the first photoresist on the to-be-processed substrate is not damaged. The first reaction material is adopted to process the first surface to form the first hydrophobic surface, and the first hydrophobic surface has higher adhesiveness with the second light resistor, so that the collapse problem of the second light resistor is improved when the second light resistor is formed. And the mask plate is provided with the first extension part and the second extension part, so that the first frame in the formed second light resistor is provided with a channel, the tension of water flow is obviously reduced when the formed second light resistor is cleaned, and the problem of collapse of the second light resistor is further avoided.

Description

Technical Field

[0001] This application relates to the field of semiconductor fabrication technology, and in particular to a photolithography method. Background Technology

[0002] In semiconductor fabrication, photolithography is a crucial step. When defects such as critical dimensional deviations, registration accuracy errors, or crystal plane anomalies occur during photolithography, the photoresist can be removed through a rework process before exposure and development under new conditions.

[0003] In the photolithography thick resist process, during photoresist cleaning, capillary forces between adjacent photoresists can cause the edge areas of high aspect ratio photoresist patterns to collapse. Furthermore, rework leads to reduced substrate surface adhesion, resulting in large-area photoresist collapse and severely impacting process yield. Summary of the Invention

[0004] Therefore, it is necessary to provide a photolithography method to address the problem of photoresist collapse.

[0005] To achieve the above objectives, the present invention provides a photolithography method, comprising:

[0006] Remove the first photoresist located on the first surface of the substrate to be processed;

[0007] The first surface is treated with a first reactive material to form a first hydrophobic surface;

[0008] A photomask is provided, the photomask having a first blocking portion and a second blocking portion spaced apart, the second blocking portion surrounding the first blocking portion, the first blocking portion having a horizontal blocking strip and a vertical blocking strip, the horizontal blocking strip and the vertical blocking strip forming a hollowed-out mesh, and the end of the horizontal blocking strip having a first extension portion, the end of the vertical blocking strip having a second extension portion, the first extension portion and the second extension portion connecting the second blocking portion;

[0009] Based on the mask, a second photoresist is formed on the first hydrophobic surface.

[0010] In one embodiment, the formation of the mask further includes:

[0011] A third blocking portion is formed around the second blocking portion, and the third blocking portion is spaced apart from the second blocking portion.

[0012] In one embodiment, the step of treating the first surface with a first reactive material to form a first hydrophobic surface includes:

[0013] The first surface is treated with PFOTS material to form a first hydrophobic surface.

[0014] In one embodiment, after treating the first surface with a first reactive material to form a first hydrophobic surface, the process includes:

[0015] The substrate to be processed is subjected to rapid heat treatment.

[0016] In one embodiment, the process temperature range for rapid thermal processing of the substrate to be processed is 350°C-500°C, and the process time range is 1 min-3 min.

[0017] In one embodiment, the rapid thermal treatment of the substrate to be processed has an impact on the ion implantation depth of ≤10%.

[0018] In one embodiment, removing the first photoresist located on the first surface of the substrate to be processed includes:

[0019] The first photoresist was removed by a combination of dry and wet etching.

[0020] In one embodiment, prior to removing the first photoresist located on the first surface of the substrate to be processed, the process includes:

[0021] Provide the substrate to be processed;

[0022] The first surface is formed by treating the initial surface of the substrate to be processed with a second reactive material;

[0023] The first photoresist is formed on the first surface;

[0024] The first photoresist is cleaned;

[0025] If the first photoresist collapses during the cleaning process, the first photoresist located on the surface of the substrate to be processed is removed.

[0026] In one embodiment, the process of treating the initial surface of the substrate to be processed with a second reactive material to form the first surface includes:

[0027] The first surface is formed by passivating the initial surface of the substrate to be processed using H plasma.

[0028] In one embodiment, the formation of the substrate to be processed includes:

[0029] Provide the initial substrate to be processed;

[0030] Ion implantation is performed on the initial substrate to be processed based on a third photoresist;

[0031] High-temperature annealing is performed to form the substrate to be processed.

[0032] Compared with existing technologies, the above technical solution has unexpected beneficial effects:

[0033] In the aforementioned photolithography method, after removing the first photoresist from the substrate, the first surface needs to be cleaned. Cleaning the first surface makes it hydrophilic, affecting the adhesion between the photoresist and the substrate. Therefore, a first reactive material is used to treat the first surface to form a first hydrophobic surface. Because the adhesion between the first hydrophobic surface and the second photoresist is higher, the collapse problem of the second photoresist is improved during its formation. Furthermore, since the photomask has a first extension and a second extension, the first border of the formed second photoresist can have channels, which significantly reduces the surface tension of the water flow during cleaning, further preventing the collapse problem of the second photoresist. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a schematic diagram of an existing type of photoresist collapse;

[0036] Figure 2 This is a schematic flowchart of a photolithography method provided in an embodiment of this application;

[0037] Figure 3 A schematic diagram of a cross-sectional structure with a third photoresist provided in an embodiment of this application;

[0038] Figure 4 This is a schematic diagram of a cross-sectional structure for removing the third photoresist, provided in an embodiment of this application.

[0039] Figure 5 A schematic diagram of a cross-sectional structure for forming a first photoresist provided in an embodiment of this application;

[0040] Figure 6 A schematic diagram of a cross-sectional structure for removing the first photoresist provided in an embodiment of this application;

[0041] Figure 7 This is a schematic diagram of a cross-sectional structure for forming a first hydrophobic surface, provided in an embodiment of this application.

[0042] Figure 8 This is a schematic diagram of a cross-sectional structure for forming a second photoresist according to an embodiment of this application;

[0043] Figure 9 This is a schematic diagram of another mask structure provided in an embodiment of this application;

[0044] Figure 10 for Figure 9 A schematic diagram of the structure of the second photoresist formed by the mask in the image;

[0045] Figure 11 This is a schematic diagram of another type of photomask provided in an embodiment of this application;

[0046] Figure 12 for Figure 11 A schematic diagram of the structure of the second photoresist formed by the mask in the image.

[0047] Explanation of reference numerals in the attached drawings: 01-Substrate to be processed; 01a-First surface; 01b-First hydrophobic surface; 02-First photoresist; 03-Second photoresist; 03a-Target photoresist pattern; 03b-First border; 03c-Channel; 03d-Second border; 04-Mask; 04a-First blocking portion; 04b-Second blocking portion; 04c-Third blocking portion; 041-Horizontal blocking strip; 042-Vertical blocking strip; 043-First extension; 044-Second extension; 07-Buffer channel; 08-Third photoresist. Detailed Implementation

[0048] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can 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.

[0049] 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 is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0050] It should be understood that when a layer is referred to as "on," "adjacent to," or "connected to" other layers, it can be directly on, adjacent to, or connected to other layers, or there can be intervening layers. Conversely, when an element is referred to as "directly on," "directly adjacent to," or "directly connected to" other layers, there are no intervening layers.

[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 the terms “comprising,” “including,” or “having,” etc., specify the presence of the stated feature, whole, step, operation, component, part, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof.

[0052] Based on the background technology content, refer to Figure 1 , Figure 1 This is a schematic diagram of a type of photoresist collapse; collapse at the edge of the photoresist will prevent subsequent ion implantation processes from being performed.

[0053] Based on this, this application provides a photolithography method in which, after removing the first photoresist from the substrate to be processed, the first surface needs to be cleaned. Cleaning the first surface makes it hydrophilic, affecting the adhesion between the photoresist and the substrate. Therefore, a first reactive material is used to treat the first surface to form a first hydrophobic surface. Because the first hydrophobic surface has higher adhesion to the second photoresist, the collapse problem of the second photoresist is improved during its formation. Furthermore, because the photomask has a first extension and a second extension, the first border of the formed second photoresist has channels, significantly reducing the surface tension of the water flow during cleaning, further preventing the collapse of the second photoresist.

[0054] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, this application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0055] In one embodiment, reference Figure 2 , Figure 2 This application provides a schematic flowchart of a photolithography method, including the following steps:

[0056] Step S101: Remove the first photoresist 02 located on the first surface 01a of the substrate to be processed 01 (e.g., Figures 5-6 (As shown).

[0057] In this step, the substrate 01 to be processed can be a silicon dioxide substrate. A first photoresist 02 is formed on the surface of the silicon dioxide substrate. After the first photoresist 02 is formed, impurities after development need to be cleaned. At this time, due to the low adhesion between the first photoresist 02 and the substrate 01 to be processed, and the capillary forces between adjacent first photoresist 02s, the first photoresist 02 may collapse at the edges, or even collapse over a large area in the center. Therefore, the first photoresist 02 on the first surface 01a of the substrate 01 to be processed is removed.

[0058] Step S102: Treat the first surface 01a with the first reactive material to form the first hydrophobic surface 01b (e.g., Figure 7 (As shown).

[0059] In this step, after cleaning the first surface 01a, dangling Si-OH bonds will be formed on the first surface 01a (such as...). Figure 6 As shown in the figure, this increases the hydrophilicity of the first surface 01a, affecting the adhesion between the photoresist and the substrate 01 to be processed. Therefore, the first surface 01a of the substrate 01 to be processed is treated with a first reactive material to form a first hydrophobic surface 01b.

[0060] Step S103: Provide a mask plate 04. The mask plate 04 has a first blocking portion 04a and a second blocking portion 04b spaced apart. The second blocking portion 04b surrounds the first blocking portion 04a. The first blocking portion 04a has a horizontal blocking strip 041 and a vertical blocking strip 042. The horizontal blocking strip 041 and the vertical blocking strip 042 form a hollowed-out mesh. The end of the horizontal blocking strip 041 has a first extension portion 043, and the end of the vertical blocking strip 042 has a second extension portion 044. The first extension portion 043 and the second extension portion 044 are connected to the second blocking portion 04b.

[0061] In this step, the provided mask 04 may include a first masking portion 04a and a second masking portion 04b. The first masking portion 04a has a horizontal masking strip 041 and a vertical masking strip 042. The horizontal masking strip 041 and the vertical masking strip 042 form a hollowed-out mesh. The mask 04 may form a first extension 043 at the end of the horizontal masking strip 041 and a second extension 044 at the end of the vertical masking strip 042.

[0062] It should be noted that the first extension 043 may be formed only at the ends of a portion of the transverse blocking strip 041, and the second extension 044 may be formed only at the ends of a portion of the longitudinal blocking strip 042. The number and position of the first extension 043 and the second extension 044 are not specifically limited. For example... Figure 9 The first extension 043 and the second extension 044 are not provided at the corners. It should be noted that the horizontal blocking strip 041, the vertical blocking strip 042, the first extension 043, the second extension 044, and the second blocking strip 04b can be integrally formed.

[0063] It should be noted that the width and length of the horizontal blocking strip 041 and the vertical blocking strip 042 can be set as needed and are not specifically limited.

[0064] Step S104: Based on the mask 04, form a second photoresist 03 on the first hydrophobic surface 01b (e.g., Figure 8 (As shown).

[0065] In this step, a negative photoresist is first coated on the first hydrophobic surface 01b of the substrate 01 to be processed. Exposure and development are then performed based on a mask 04 to form a second photoresist 03. The increased hydrophobicity of the first hydrophobic surface 01b enhances the adhesion between the substrate 01 to be processed and the second photoresist 03. This second photoresist 03, when applied at this stage, reduces the risk of collapse during subsequent cleaning.

[0066] use Figure 9 The second photoresist 03 formed by the mask 04 in the middle is as follows Figure 10 As shown, there is a target photoresist pattern 03a arranged in an array and a first border 03b surrounding the target photoresist pattern 03a. The first border 03b has a channel 03c. When cleaning the second photoresist 03, the cleaning fluid will flow out from the channel 03c, thereby preventing the cleaning fluid from impacting the target photoresist pattern 03a when it returns, thus avoiding the problem of the second photoresist 03 collapsing.

[0067] In this embodiment, after removing the first photoresist 02 from the substrate 01, the first surface 01a needs to be cleaned. Cleaning the first surface 01a makes it hydrophilic, affecting the adhesion between the photoresist and the substrate 01. Therefore, a first reactive material is used to treat the first surface 01a to form a first hydrophobic surface 01b. Since the first hydrophobic surface 01b has a higher adhesion to the second photoresist 03, the collapse problem of the second photoresist 03 is improved during its formation. Furthermore, since the mask 04 is provided with a first extension 043 and a second extension 044, the first frame 03b in the formed second photoresist 03 can have a channel 03c, which significantly reduces the surface tension of the water flow during the cleaning of the formed second photoresist 03, further preventing the collapse problem of the second photoresist 03.

[0068] In another embodiment of this application, reference is made to Figure 11 Mask 04 also includes:

[0069] A third blocking portion 04c is formed around the second blocking portion 04b, and the third blocking portion 04c is disposed at a distance from the second blocking portion 04b.

[0070] Specifically, the mask 04 may have a third blocking portion 04c surrounding the second blocking portion 04b on its outer side. In this case, a first opening area exists between the third blocking portion 04c and the second blocking portion 04b. It should be noted that the transverse blocking strip 041, the longitudinal blocking strip 042, the first extension 043, the second extension 044, the second blocking portion 04b, and the third blocking portion 04c are integrally formed.

[0071] use Figure 11 The second photoresist 03 formed by the mask 04 in the middle is as follows Figure 12 As shown, the target photoresist pattern 03a is arranged in an array, and a first border 03b surrounds the target photoresist pattern 03a. The first border 03b has a channel 03c, and a second border 03d surrounds the first border 03b. A buffer channel 07 is provided between the second border 03d and the first border 03b. When cleaning the second photoresist 03, the cleaning fluid flows out from the channel 03c and enters the buffer channel 07, further preventing the cleaning fluid flowing out of the channel from returning and impacting the target photoresist pattern 03a, thus avoiding the problem of the second photoresist 03 collapsing.

[0072] In this embodiment, a third blocking part 04c is provided in the mask plate 04, which can further reduce the collapse of the second photoresist 03.

[0073] In another embodiment of this application, such as Figure 8 As shown, step S102 includes:

[0074] Step S1021: The first surface 01a is treated with PFOTS material to form the first hydrophobic surface 01b.

[0075] In this step, the first surface 01a is treated with chemical vapor deposition (CVD) using PFOTS material.

[0076] PFOTS material can be Cl3(nH-F) x )-Si-(CH4) x Self-assembled materials, such as 1H,1H,2H,2H-perfluorooctyltrichlorosilane. This PFOTS material can form good silicon-based surface bonds, yielding RO-Si(C8F) 17 The hydrophobic dangling bonds of C2H4 form the first hydrophobic surface 01b.

[0077] PFOTS treatment includes, but is not limited to, nH-F x A silicon-based self-assembly material with a structure, where n is the number of hydrogen atoms and x is the number of fluorine atoms.

[0078] In this step, PFOTS material is a self-assembly material. The self-assembly technology can repair the first surface 01a, making it more hydrophobic. This can increase the adhesion between the substrate 01 to be processed and the second photoresist 03, avoiding the problem of collapse during subsequent cleaning.

[0079] In another embodiment of this application, after step S104, the following is included:

[0080] Step S105: Perform rapid heat treatment on the substrate 01 to be processed.

[0081] In this embodiment, rapid heat treatment can remove water from the surface of the substrate 01 to be processed, thus preventing the substrate 01 from generating hydrophilic bonds again.

[0082] In another embodiment of this application, the process temperature range for rapid thermal processing of the substrate 01 to be processed is 350°C-500°C, and the process time range is 1 min-3 min.

[0083] Specifically, the process temperature range for rapid thermal processing of the substrate 01 can be 350℃-500℃, including the endpoint values. For example, the temperature during rapid thermal processing can be 350℃, 400℃, or 460℃, etc., without any specific limitation. The process time range for rapid thermal processing of the substrate 01 is 1min-3min, including the endpoint values. For example, the rapid thermal processing time can be 1.5min, 2min, or 3min, etc., without any specific limitation.

[0084] In another embodiment of this application, the rapid thermal treatment of the substrate 01 to be processed has an effect of ≤10% on the depth of ion implantation.

[0085] Specifically, the impact of rapid thermal treatment on the depth of ion implantation should be controlled to ≤10%. For example, the impact of rapid thermal treatment on the depth of ion implantation can be controlled to 1%, or 4%, or 7%, etc., without specific limitations.

[0086] In this embodiment, the impact of rapid thermal treatment on the depth of ion implantation is controlled to ≤10%, which can ensure the accuracy and stability of doping distribution and reduce implantation deviation.

[0087] In another embodiment of this application, S101 includes:

[0088] The first photoresist O2 was removed by a combination of dry and wet etching.

[0089] Specifically, when the first photoresist 02 collapses and does not comply with regulations, dry ashing and wet etching methods can be used to remove the first photoresist 02.

[0090] In another embodiment of this application, such as Figure 3 As shown, before step S101, the following steps are included:

[0091] Step S111: Provide the substrate 01 to be processed.

[0092] Step S112: The initial surface of the substrate 01 to be processed is treated with a second reaction material to form a first surface 01a (e.g., ...). Figure 4 (As shown).

[0093] In this step, the first surface 01a formed by treating the initial surface of the substrate 01 to be processed with the second reactive material can improve the adhesion between the first photoresist 02 and the substrate 01 to be processed.

[0094] Step S113: Form a first photoresist 02 on the first surface 01a (e.g., Figure 5 (As shown).

[0095] In this step, the process of forming the first photoresist 02 and the process of forming the second photoresist 03 can be the same, and will not be described in detail here.

[0096] Step S114: Clean the first photoresist O2.

[0097] Step S115: If the first photoresist 02 collapses during the cleaning process, remove the first photoresist 02 located on the surface of the substrate 01 to be processed.

[0098] In this step, if the first photoresist O2 does not collapse during the cleaning process, the process can be terminated and subsequent ion implantation can continue.

[0099] If the first photoresist 02 collapses during the cleaning process, step S101 is executed to ensure that the formed photoresist is free of defects.

[0100] In this embodiment, the adhesion between the substrate 01 to be processed and the first photoresist 02 is improved by using the second reactive material to treat the initial surface of the substrate 01 to be processed, thereby reducing the possibility of the first photoresist 02 collapsing.

[0101] In another embodiment of this application, step S112 includes:

[0102] Step S1121: Passivate the initial surface of the substrate 01 to be processed using H plasma to form the first surface 01a.

[0103] Specifically, when using H plasma to passivate the initial surface of the substrate 01 to be processed, the process temperature can be 400℃-650℃.

[0104] In this embodiment, passivation treatment with H plasma on the initial surface of the substrate 01 to be processed can form Si-H bonds, increasing the adhesion between the substrate 01 to be processed and the first photoresist 02.

[0105] In another embodiment of this application, step S111 includes:

[0106] Step S1111: Provide the initial substrate to be processed;

[0107] Step S1112: Ion implantation is performed on the initial substrate to be processed based on the third photoresist;

[0108] Step S1113: High-temperature annealing to form the substrate to be processed.

[0109] Specifically, an initial substrate 011 is first provided, and then a third photoresist 08 is formed on the initial substrate 011. An ion implantation process is then performed on the initial substrate 011 based on the third photoresist 08.

[0110] After ion implantation, the third photoresist 08 is removed, and high-temperature annealing is used to obtain a uniformly diffused ion implantation region to form the substrate 01 to be processed (e.g., Figure 4 (As shown). At this time, the diffusion depth ratio of ion implantation is required to be 40%-60%. The high-temperature annealing treatment temperature can be 950℃-1250℃, including the endpoint values. For example, the high-temperature annealing treatment temperature can be 950℃, or the high-temperature annealing treatment temperature can be 1100℃, or the high-temperature annealing treatment temperature can be 1210℃, etc., without specific limitations.

[0111] The above photolithography method is applicable to all technical routes that utilize optimized mask design combined with PFOTS processing to improve photoresist collapse. The mask design includes, but is not limited to, trench designs with a pixel size of 1 / 2 / 3... times.

[0112] In the description of this specification, references to terms such as "some embodiments," "another embodiment," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative descriptions of the above terms do not necessarily refer to the same embodiments or examples.

[0113] 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.

[0114] The embodiments described above are merely illustrative 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 all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A photolithography method, characterized by, The method comprises: removing a first photoresist on a first surface of a substrate to be processed; processing the first surface with a first reaction material to form a first hydrophobic surface; providing a mask plate, the mask plate having a first shielding part and a second shielding part arranged in a spaced manner, the second shielding part surrounding the first shielding part, the first shielding part having transverse shielding strips and longitudinal shielding strips, the transverse shielding strips and the longitudinal shielding strips forming a hollow grid, and the end of the transverse shielding strips having a first extension, and the end of the longitudinal shielding strips having a second extension, the first extension and the second extension connecting the second shielding part; forming a second photoresist on the first hydrophobic surface based on the mask plate.

2. The photolithography method of claim 1, wherein, The formation of the mask plate further comprises: forming a third shielding part surrounding the second shielding part, the third shielding part being arranged in a spaced manner with the second shielding part.

3. The photolithography method of claim 1, wherein, The processing of the first surface with a first reaction material to form a first hydrophobic surface comprises: processing the first surface with a PFOTS material to form a first hydrophobic surface.

4. The photolithography method of claim 1, wherein, After the processing of the first surface with a first reaction material to form a first hydrophobic surface, the method further comprises: rapid thermal processing the substrate to be processed.

5. The photolithography method of claim 4, wherein, The process temperature range of the rapid thermal processing of the substrate to be processed is 350-500℃, and the process time range is 1-3min.

6. The photolithography method of claim 4, wherein, The depth of ion implantation during the rapid thermal processing of the substrate to be processed has an influence of ≤10%.

7. The photolithography method of claim 1, wherein, The removing of the first photoresist on the first surface of the substrate to be processed comprises: removing the first photoresist by combining dry etching and wet etching.

8. The photolithography method of claim 1, wherein, Before the removing of the first photoresist on the first surface of the substrate to be processed, the method further comprises: providing the substrate to be processed; processing an initial surface of the substrate to be processed with a second reaction material to form the first surface; forming the first photoresist on the first surface; cleaning the first photoresist; when the first photoresist collapses during the cleaning process, removing the first photoresist on the surface of the substrate to be processed.

9. The photolithography method of claim 8, wherein, The processing of the initial surface of the substrate to be processed with a second reaction material to form the first surface comprises: passivating the initial surface of the substrate to be processed with H plasma to form the first surface.

10. The photolithography method of claim 8, wherein, The formation of the substrate to be processed comprises: providing an initial substrate to be processed; performing ion implantation on the initial substrate to be processed based on a third photoresist; high-temperature annealing to form the substrate to be processed.

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