Photoetching method and photoetching structure
By using developable first and second antireflective coatings in the photolithography process and adjusting the thickness to address reflectivity and photoresist thickness issues, the aspect ratio and depth of field were improved, while costs were reduced.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHENGDU ZIGUANG SEMICON TECH CO LTD
- Filing Date
- 2024-11-04
- Publication Date
- 2026-05-08
AI Technical Summary
Existing photolithography processes face difficulties in controlling reflectivity and photoresist thickness, resulting in limitations on aspect ratio and depth of field. Furthermore, the use of high-cost etching materials increases production costs.
Two different types of anti-reflective coatings are used, including a developable first anti-reflective coating and a second anti-reflective coating. The aspect ratio and etching blocking ability are adjusted through the development and etching processes to reduce costs.
It enables flexible control of reflectivity, improves aspect ratio and depth of field, and reduces the cost of photolithography.
Smart Images
Figure CN121995699A_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to the field of photolithography technology, specifically to a photolithography method and a photolithography structure. Background Technology
[0002] In the wafer fabrication process, in order to effectively control reflectivity and ensure sufficient photoresist thickness to block reactive ion etching, the dry ArF lithography film scheme is usually PR+BARC, while the immersion ArF is PR+BARC+APF or PR+tri-layer (Si-ARC+SOC).
[0003] However, in the bi-layer film scheme (PR+BARC), sufficient photoresist thickness is required. Due to aspect ratio issues, the critical dimension (CD) cannot be too small, and the depth of field (DoF) cannot be too large. Immersion ArF offers better CD and DoF, but BARC+APF or Si-ARC+SOC both require etching, resulting in higher costs. Summary of the Invention
[0004] The purpose of this disclosure is to provide a photolithography method and a photolithography structure. The photolithography method utilizes two different types of anti-reflective coatings to flexibly adjust the process aspect ratio and etching blocking capability. At the same time, the use of a development process in the photolithography method can reduce costs.
[0005] To achieve the above objectives, according to a first aspect of this disclosure, a photolithography method is provided, comprising: A first anti-reflective coating, a second anti-reflective coating, and a photoresist layer are sequentially formed on the substrate; wherein, the first anti-reflective coating is a developable anti-reflective coating; The photoresist layer is patterned, and the second anti-reflective coating is etched using the patterned photoresist layer; The first anti-reflective coating is patterned using a development process and a patterned photoresist layer and an etched second anti-reflective coating. The substrate is etched using a graphical second anti-reflective layer.
[0006] Optionally, in the process of patterning the first antireflective coating using a developing process and a patterned photoresist layer and an etched second antireflective coating, the developer used is TMAH.
[0007] Optionally, the thickness of the first anti-reflective coating is greater than the thickness of the second anti-reflective coating.
[0008] Optionally, the thickness of the photoresist layer is greater than the thickness of the second antireflective coating.
[0009] Optionally, the thickness ratio of the photoresist layer to the second antireflective coating is 2 to 12.
[0010] Optionally, the thickness of the second anti-reflective coating is greater than or equal to 250 Å.
[0011] According to a second aspect of this disclosure, a photolithography structure is also provided, comprising: An anti-reflective coating includes a first, developable anti-reflective coating and a second anti-reflective coating disposed above the first anti-reflective coating; and A photoresist layer is disposed above the second antireflective coating.
[0012] Optionally, the thickness of the first anti-reflective coating is greater than the thickness of the second anti-reflective coating; and / or The thickness of the photoresist layer is greater than the thickness of the second antireflective coating.
[0013] Optionally, the thickness ratio of the photoresist layer to the second antireflective coating is 2 to 12.
[0014] Optionally, the thickness of the second anti-reflective coating is greater than or equal to 250 Å.
[0015] Through the above technical solution, the photolithography method of this disclosure sequentially forms a first anti-reflective coating, a second anti-reflective coating, and a photoresist layer on a substrate. Since the first anti-reflective coating is a developable anti-reflective coating, the photoresist layer is first patterned open, then the second anti-reflective coating is etched open, and then the first anti-reflective coating is opened through a development process using the patterned photoresist layer and the opened second anti-reflective coating. Finally, the desired structure is formed on the substrate by a typical etching process. The photolithography method of this disclosure provides a new mask scheme, which can achieve reflectivity control by adjusting the thickness of the first and second anti-reflective coatings. For example, the thickness of the first anti-reflective coating can be thicker, while the thickness of the second anti-reflective coating can be thinner. In addition, the photolithography method of this application includes exposure-development + etching + development + substrate etching. Compared with related technologies, this disclosure adopts two development processes and one intermediate etching process. On the one hand, the aspect ratio and etching blocking ability can be flexibly adjusted by using two different types of anti-reflective coatings; on the other hand, the use of a development process in the photolithography method can reduce costs.
[0016] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description
[0017] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the accompanying drawings...
[0018] Figure 1 This is a flowchart of a photolithography method provided in some embodiments of this disclosure.
[0019] Figures 2 to 6 This is a schematic diagram of the structure corresponding to each step in the photolithography method provided in some embodiments of this disclosure.
[0020] Figure 7 This is a schematic diagram of the 55nm AA bi-layer (PR+BARC) molding process in related technologies.
[0021] Figures 8a to 8e This is a schematic diagram of the photolithography method disclosed herein for 55nm AA forming.
[0022] Figure 9 This is a schematic diagram of the 40nm AA tri-layer (Si-ARC+SOC) molding process in related technologies.
[0023] Figures 10a to 10e This is a schematic diagram of the photolithography method disclosed herein for 40nm AA forming.
[0024] Explanation of reference numerals in the attached figures 100 - Anti-reflective coating; 110 - First anti-reflective coating; 120 - Second anti-reflective coating; 130 - Photoresist layer; 200 - Substrate; 201 - Shallow trench isolation; 210 - Oxide layer; 220 - Nitride layer. Detailed Implementation
[0025] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.
[0026] In this disclosure, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to upper and lower relative to the accompanying drawings. Furthermore, the terms "first," "second," etc., used in this disclosure are for distinguishing one element from another and do not imply sequentiality or importance. Additionally, in the following description, when referring to the accompanying drawings, unless otherwise explained, the same reference numerals in different drawings denote the same or similar elements. The above definitions are for explanation and illustration only and should not be construed as limiting this disclosure.
[0027] In the wafer fabrication process, in order to effectively control reflectivity and ensure sufficient photoresist thickness to block reactive ion etching, the dry ArF lithography film scheme is usually PR+BARC, while the immersion ArF is PR+BARC+APF or PR+tri-layer (Si-ARC+SOC).
[0028] In a bi-layer film scheme (PR+BARC), the thicker the BARC, the lower the reflectivity. During the BARC opening and subsequent etching stages, since the BARC to PR ratio is close to 1:1, sufficient photoresist thickness is required. Typically, the BARC to PR ratio is 1:2.5~4. However, the thicker the photoresist, the smaller the CD (critical dimension) and the larger the DoF (depth of field) can be due to aspect ratio issues.
[0029] Immersion ArF consists of PR+tri-layer (Si-ARC+SOC) or PR+BARC+SiON+APF. Because PR and Si-ARC, Si-ARC and SOC, or PR and SiON, SiON and APF offer good selectivity ratios, the photoresist thickness does not need to be too thick, resulting in better CD (critical dimension) and DoF (depth of field). However, both BARC+APF and Si-ARC+SOC require etching, leading to higher costs.
[0030] To address the aforementioned issues, this disclosure provides a photolithography method and structure that utilizes two different types of antireflective coatings, namely a first antireflective coating 110 (DBARC, Developable BARC) and a second antireflective coating 120 (BARC), to flexibly adjust the process aspect ratio and etching blocking capability. Simultaneously, the use of a development process in the photolithography method can reduce costs.
[0031] To achieve the above objectives, such as Figures 1 to 6 As shown, according to a first aspect of this disclosure, a photolithography method is provided, the method comprising steps S100 to S400.
[0032] In step S100, a first anti-reflective coating 110, a second anti-reflective coating 120, and a photoresist layer 130 are sequentially formed on the substrate 200; wherein, the first anti-reflective coating 110 is a developable anti-reflective coating.
[0033] In step S200, the photoresist layer 130 is patterned, and the second anti-reflective coating 120 is etched using the patterned photoresist layer 130.
[0034] In step S300, the first anti-reflective coating 110 is patterned using a development process and a patterned photoresist layer 130 and an etched second anti-reflective coating 120.
[0035] In step S400, the substrate 200 is etched using a patterned second anti-reflective layer.
[0036] Through the above technical solution, the photolithography method disclosed herein, by sequentially forming a first anti-reflective coating 110, a second anti-reflective coating 120, and a photoresist layer 130 on a substrate 200, wherein the first anti-reflective coating 110 is a developable anti-reflective coating, such as Figure 2 As shown. First, the photoresist layer 130 is opened graphically, as shown... Figure 3 As shown. Then, the second anti-reflective coating 120 is opened by etching, as shown. Figure 4 As shown. Then, through the patterned photoresist layer 130 and the opened second anti-reflective coating 120, the first anti-reflective coating 110 is opened by a development process, as... Figure 5 As shown. Finally, an etching process is typically used to form the desired structure (e.g., shallow trench isolation 201) on the substrate 200, such as... Figure 6 As shown. The photolithography method disclosed herein provides a novel mask scheme that allows for reflectivity control by adjusting the thickness of the first anti-reflective coating 110 and the second anti-reflective coating 120. For example, the first anti-reflective coating 110 can be thicker, while the second anti-reflective coating 120 can be thinner. Furthermore, the photolithography method of this application includes exposure-development + etching + development + etching of the substrate 200. Compared with related technologies, this application employs two development processes and one intermediate etching process. On the one hand, the aspect ratio and etching blocking capability can be flexibly adjusted using two different types of anti-reflective coatings; on the other hand, the use of a development process in the photolithography method can reduce costs.
[0037] It should be noted that the patterned photoresist layer 130 can be formed using methods and processes known in the relevant art. For example, the photoresist layer 130 can be opened by exposure and development to form the patterned photoresist layer 130. The etching process of the second anti-reflective coating 120 can be completed using a dry ET process. Therefore, in the entire photolithography method, the pattern formation method is: exposure-development+etching+development+etching of the substrate 200.
[0038] It is worth noting that the step of sequentially forming the first anti-reflective coating 110, the second anti-reflective coating 120, and the photoresist layer 130 on the substrate 200 further includes sequentially depositing an oxide layer 210 and a nitride layer 220 on the substrate 200; and then sequentially depositing the first anti-reflective coating 110, the second anti-reflective coating 120, and the photoresist layer 130 on the nitride layer 220. Similarly, in the final etching step, the nitride layer 220 and the oxide layer 210 need to be etched first, and then the substrate 200 needs to be etched, thereby forming a shallow trench isolation 201 on the substrate 200. The process of sequentially depositing the oxide layer 210 and the nitride layer 220 on the substrate 200 can be referred to relevant technologies and will not be elaborated here.
[0039] In some embodiments, in the patterning of the first antireflective coating 110 using the development process and the patterned photoresist layer 130 and the etched second antireflective coating 120, the developer used is TMAH. It should be noted that the use of TMAH as the developer is exemplary; other developers that can meet the requirements of the development process can also be used to complete this step, which will not be elaborated here.
[0040] Optionally, the thickness of the first anti-reflective coating 110 is greater than the thickness of the second anti-reflective coating 120. Specifically, the thickness of the developable first anti-reflective coating 110 (DBARC) is greater than the thickness of the etchable second anti-reflective coating 120 (BARC). Reflectivity control can be achieved by adjusting the thickness of the two layers, BARC and DBARC (Developable BARC), where the DBARC (Developable BARC) thickness is greater than the BARC thickness. For example, the thinnest single BARC in mass-produced BARC ARC29SR-303 is 260A, and reflectivity can be effectively controlled by increasing the DBARC (Developable BARC) thickness.
[0041] The photolithography structure formed in the photolithography method disclosed herein includes PR+BARC+DBARC, which replaces the traditional Bi-layer (PR+BARC) and tri-layer film scheme (Si-ARC+SOC), and the etching thickness is mainly composed of the superposition of PR+BARC+DBARC thickness.
[0042] Optionally, the thickness of the photoresist layer 130 is greater than the thickness of the second anti-reflective coating 120. The thickness of the photoresist layer 130 (PR) can be flexibly adjusted according to process requirements. For example, the ratio of the thickness of the photoresist layer 130 to the thickness of the second anti-reflective coating 120 can be 2 to 12 times, meaning the thickness of the photoresist layer 130 can be between 2 and 12 times the thickness of the second anti-reflective coating 120. For instance, the thickness of the photoresist layer 130 can be 2, 3, 5, 8, 10, or 12 times the thickness of the second anti-reflective coating 120. These ratios are merely illustrative; other ratios can also be within the range described above. For example, the photoresist layer 130 can be 2.5, 4.5, or 8.5 times the thickness of the second anti-reflective coating 120.
[0043] In some alternative embodiments, the thickness of the second antireflective coating 120 is greater than or equal to 250 Å. Since the reflectivity can be controlled by adjusting the thickness of the first antireflective coating 110 in the photolithography method of this disclosure, the second antireflective coating 120 can be made relatively thin. For example, for 55nm AA, the reflectivity (PR) is approximately 2100 Å, and the total thickness of BARC+DBARC is approximately 1020 Å, where BARC is approximately 260 Å and DBARC is approximately 760 Å, resulting in a reflectivity of approximately 0.5%, which is greater than the 0.43% reflectivity of a single 1020 Å antireflective coating.
[0044] According to the second aspect of this disclosure, such as Figure 2 As shown, a photolithography structure is also provided, which includes an anti-reflective coating and a photoresist layer 130 (PR). The anti-reflective coating includes a developable first anti-reflective coating 110 (DBARC) and a second anti-reflective coating 120 (BARC) disposed above the first anti-reflective coating 110; the photoresist layer 130 is disposed above the second anti-reflective coating 120. The developable first anti-reflective coating 110 is formed above the substrate 200, and the second anti-reflective coating 120 and the photoresist layer 130 are sequentially disposed above the first anti-reflective coating 110.
[0045] A first anti-reflective coating 110, a second anti-reflective coating 120, and a photoresist layer 130 are sequentially formed on a substrate 200. Since the first anti-reflective coating 110 is a developable anti-reflective coating, the photoresist layer 130 is first patterned open, then the second anti-reflective coating 120 is etched open, and then the first anti-reflective coating 110 is opened through a development process using the patterned photoresist layer 130 and the opened second anti-reflective coating 120. Finally, the desired structure is formed on the substrate 200 by a typical etching process. The photolithography method disclosed herein provides a novel mask scheme that allows for reflectivity control by adjusting the thickness of the first anti-reflective coating 110 and the second anti-reflective coating 120. Furthermore, the photolithography structure disclosed herein can be implemented using a photolithography method of exposure-development + etching + development + etching of the substrate 200 to pattern the photoresist layer 130, open the second anti-reflective coating 120, and the substrate 200. Compared with related technologies, this application adopts a two-stage development and one-stage intermediate etching process. On the one hand, the process aspect ratio and etching blocking ability can be flexibly adjusted by using two different types of anti-reflective coatings; on the other hand, the use of a development process in the photolithography method can reduce costs.
[0046] In some embodiments, the thickness of the first antireflective coating 110 is greater than the thickness of the second antireflective coating 120; wherein, the thickness of the developable first antireflective coating 110 (DBARC) is greater than the thickness of the second antireflective coating 120 (BARC) that needs to be etched, and the reflectivity control can be adjusted by the thickness of the two layers of BARC+DBARC (Developable BARC).
[0047] In some embodiments, the thickness of the photoresist layer 130 is greater than the thickness of the second antireflective coating 120. To ensure reflectivity and meet process requirements, in some embodiments, the thickness of the second antireflective coating 120 can be greater than or equal to 250 Å. For example, for 55nm AA, the photoresist layer 130 is approximately 2100 Å, and the total thickness of BARC+DBARC is approximately 1020 Å, where BARC is approximately 260 Å and DBARC is approximately 760 Å, resulting in a reflectivity of approximately 0.5%, which is greater than the 0.43% reflectivity of a single 1020 Å antireflective coating.
[0048] For example, for 40nm AA, PR is about 1200A, and the total thickness of BARC+DBARC is about 1800A, of which BARC is about 300A and DBARC is about 1500A. The reflectivity is about 0.6%, which is greater than the reflectivity of a single 1800A anti-reflective coating of 0.3%.
[0049] Optionally, the thickness ratio of the photoresist layer 130 to the thickness of the second anti-reflective coating 120 is 2 to 12. That is, the thickness of the photoresist layer 130 can be between 2 and 12 times the thickness of the second anti-reflective coating 120. For example, the thickness of the photoresist layer 130 can be 2, 3, 5, 8, 10, or 12 times the thickness of the second anti-reflective coating 120. The above-mentioned multiple relationships are only exemplary, and can also be multiple relationships between the above multiples. For example, the photoresist layer 130 can be 2.5, 4.5, 8.5, etc., of the second anti-reflective coating 120.
[0050] The thickness of the photoresist layer 130 (PR) can be flexibly adjusted according to the process requirements, with the thickness of PR being 2 to 12 times that of BARC. For example, with the 65nm ArF process, PR is about 3200 Å, and BARC is the thinnest BARC in mass production, ARC29SR-303, at 260 Å, which is about 12 times thick. The overall etching thickness is mainly composed of the superposition of PR + BARC + DBARC thickness.
[0051] like Figure 7 As shown, in one embodiment, in the related technology, taking the industry 55nm AA as an example, PR is about 2100 and BARC is about 1020A. Depending on the subsequent photolithography and etching processes, an STI structure can be formed.
[0052] like Figures 8a to 8e As shown, according to the photolithography process of this disclosure, OX, SIN, BARC, DBARC, and PR are formed on a Si substrate, wherein the thicknesses of PR 2100A (can be thinned) + BARC and DBARC are 260A and 760A, respectively. First, PR is patterned, as shown... Figure 8b As shown. Then etch the BARC 260A again using PR, as... Figure 8c As shown. The following uses TMAH to open DBARC 760A, as... Figure 8d As shown. Subsequent etching processes, such as... Figure 8e As shown. Can form with Figure 7 Same STI structure.
[0053] like Figure 9 As shown, in another embodiment, in related technologies, taking industry-leading 40nm AA as an example, PR is approximately 1200, Si-ARC is approximately 300A, and SOC is approximately 1500A. Through etching, it is possible to obtain... Figure 9 The STI structure in [the context].
[0054] like Figures 10a to 10e As shown, according to the photolithography process of this disclosure, OX, SIN, BARC, DBARC, and PR are formed on a Si substrate, wherein the thicknesses of BARC and DBARC are 300 Å and 1500 Å, respectively. Figure 10aAs shown. First, visualize PR, as follows. Figure 10b As shown. Then etch using PR to open the BARC (300A), as... Figure 10c As shown. The following uses TMAH to open DBARC (1500A), as... Figure 10d As shown. Subsequent etching processes, such as... Figure 10e As shown. Can form with Figure 9 Same STI structure.
[0055] In summary, the photolithography method and structure disclosed herein form a photolithographic structure on a substrate 200, specifically by sequentially forming a first anti-reflective coating 110, a second anti-reflective coating 120, and a photoresist layer 130 on the substrate 200. Since the first anti-reflective coating 110 is a developable anti-reflective coating, the photoresist layer 130 is first patterned open, then the second anti-reflective coating 120 is etched open, and then the first anti-reflective coating 110 is opened through a development process using the patterned photoresist layer 130 and the opened second anti-reflective coating 120. Finally, the desired structure is formed on the substrate 200 using a conventional etching process. The photolithography method disclosed herein provides a novel mask scheme that allows for reflectivity control by adjusting the thickness of the first anti-reflective coating 110 and the second anti-reflective coating 120. For example, the first anti-reflective coating 110 can be thicker, while the second anti-reflective coating 120 can be thinner. In addition, the photolithography method of this application includes exposure-development+etching+development+etching of substrate 200. Compared with related technologies, this application adopts two development processes and one intermediate etching process. On the one hand, the process aspect ratio and etching blocking ability can be flexibly adjusted by using two different types of anti-reflective coatings. On the other hand, the cost can be reduced by using a development process in the photolithography method.
[0056] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.
[0057] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.
[0058] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.
Claims
1. A photolithography method, characterized in that, include: A first anti-reflective coating, a second anti-reflective coating, and a photoresist layer are sequentially formed on the substrate; wherein, the first anti-reflective coating is a developable anti-reflective coating; The photoresist layer is patterned, and the second anti-reflective coating is etched using the patterned photoresist layer; The first anti-reflective coating is patterned using a development process and a patterned photoresist layer and an etched second anti-reflective coating. The substrate is etched using a graphical second anti-reflective layer.
2. The photolithography method according to claim 1, characterized in that, In the process of patterning the first antireflective coating using a developing process and a patterned photoresist layer and an etched second antireflective coating, the developer used is TMAH.
3. The photolithography method according to claim 1, characterized in that, The thickness of the first anti-reflective coating is greater than the thickness of the second anti-reflective coating.
4. The photolithography method according to claim 1, characterized in that, The thickness of the photoresist layer is greater than the thickness of the second antireflective coating.
5. The photolithography method according to claim 4, characterized in that, The thickness ratio of the photoresist layer to the second antireflective coating is 2 to 12.
6. The photolithography method according to claim 1, characterized in that, The thickness of the second antireflective coating is greater than or equal to 250 Å.
7. A photolithographic structure, characterized in that, include: An anti-reflective coating includes a first developable anti-reflective coating and a second anti-reflective coating disposed above the first anti-reflective coating; and A photoresist layer is disposed above the second antireflective coating.
8. The photolithography structure according to claim 7, characterized in that, The thickness of the first anti-reflective coating is greater than the thickness of the second anti-reflective coating; and / or The thickness of the photoresist layer is greater than the thickness of the second antireflective coating.
9. The photolithography structure according to claim 8, characterized in that, The thickness ratio of the photoresist layer to the second antireflective coating is 2 to 12.
10. The photolithography structure according to claim 7, characterized in that, The thickness of the second antireflective coating is greater than or equal to 250 Å.