Short-wavelength large-area conformal contact type photoetching process
By employing a conformal contact lithography technique using a low-cost, short-wavelength excimer lamp and transferable PMMA photoresist, the problems of high cost and complexity of short-wavelength lithography equipment have been solved, enabling low-cost processing of high-resolution, large-area patterns, which is suitable for the micro-nano manufacturing field.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-30
- Publication Date
- 2026-03-13
Smart Images
Figure CN121657375A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of micro-nano manufacturing, and in particular to a short-wavelength, large-area conformal contact photolithography process. Background Technology
[0002] Photolithography is a crucial micro- and nano-fabrication process that uses light irradiation to precisely transfer micro- and nano-patterns from a mask onto a photoresist surface. As a core component of pattern definition in advanced systems such as semiconductor devices, integrated circuits, and optoelectronic devices, photolithography plays a decisive role in the continuous evolution of process nodes. In recent years, with the rapid development of emerging fields such as flexible electronics, advanced packaging, and biosensing, the industry has placed higher demands on photolithography in terms of high resolution, large format, low cost, and high throughput compatibility.
[0003] To address the conflict between high resolution and large-format processing, various photolithography technologies have emerged. For example, electron beam lithography can achieve patterns below 10nm, but its slow exposure speed and high cost make it difficult to meet the high-throughput requirements of industrialization. While nanoimprint lithography has the ability to rapidly process extremely high-resolution patterns, it still faces a series of challenges in practical applications, such as complex template preparation processes, stress-induced structural damage, and limited yield in large-area high-throughput manufacturing. Projection lithography can achieve large-area submicron structures; however, the design and manufacturing of the optical system are very complex, and large-area exposure requires multiple exposures, resulting in stitching errors.
[0004] Conformal contact lithography uses transferable photoresist as an intermediate medium to ensure a zero-gap soft contact between the mask and the photoresist, thus achieving the theoretical resolution limit of contact lithography at a wavelength of 365 nm. However, existing conformal contact lithography methods face challenges in further improving pattern resolution, as the relatively long wavelength of traditional light sources (such as 365 nm) limits the fabrication capability of smaller feature sizes. Existing DUV (193 nm) and EUV (13.5 nm) lithography technologies have significant advantages in resolution improvement and micro / nano pattern transfer, but their high equipment costs, operating expenses, and complex maintenance processes have become major obstacles to their widespread deployment in research institutions and some industrial sectors.
[0005] Based on this, the present invention provides a short-wavelength, large-area conformal contact lithography process, aiming to solve the technical problems of high manufacturing cost, complex system structure, and difficult maintenance of short-wavelength lithography equipment. This process uses a low-cost short-wavelength excimer lamp as the exposure light source, significantly improving lithography resolution without requiring a complex, high-end optical system. Addressing the special requirements of short-wavelength lithography on the material system, the present invention further proposes a transferable PMMA photoresist material system suitable for short-wavelength exposure conditions and introduces it into the perfect conformal contact lithography process, thereby achieving stable fabrication and transfer of high-resolution patterns on large-area substrates.
[0006] To achieve the above objectives, this invention provides a short-wavelength, large-area conformal contact photolithography process, the basic processing flow of which includes: S100. The substrate is ultrasonically cleaned with deionized water for 5 minutes and dried with nitrogen gas. The substrate includes at least one of silicon wafer and silicon dioxide.
[0007] S200. A uniform, impurity-free, near-zero adhesion photoresist film is obtained by spin coating.
[0008] S300. After the photoresist is applied, preheat it by placing it on a hot plate at 180°C for 3-5 minutes to slowly remove excess solvent from the photoresist.
[0009] S400. Slowly conformally attach the stamp to the photoresist surface and non-destructively peel the photoresist from the substrate. The stamp includes at least one of polydimethylsiloxane (PDMS) film, polyurethane (TPU) film, and heat-release tape, with a non-destructive peeling speed ranging from 2 mm / s to 10 mm / s.
[0010] S500. The stamp and photoresist are conformally bonded to the mask and exposed using a 172nm vacuum ultraviolet lithography machine, with an exposure time range of 20-60s.
[0011] S600. Photoresist is released onto the silicon wafer without damage on a hot plate at 80°C.
[0012] The S700 uses immersion developing, where the photoresist released onto the silicon wafer is developed in a developing solution. The developing solution is a mixture of MIBK and IPA at a ratio of 1:3, and the developing time ranges from 30 to 60 seconds.
[0013] S800. Metallization of photoresist structures is achieved through metal deposition using a metal deposition equipment. The metal deposition equipment includes at least one of thermal evaporation, ion beam sputtering, magnetron sputtering, and atomic layer deposition.
[0014] S900. A high-precision metal structure is obtained by dry removal of photoresist using adhesive tape. The adhesive tape includes at least one of PI tape and thermally release tape.
[0015] The photoresist used is a transferable PMMA-A2 positive photoresist, and the photoresist preparation method includes: Weigh a certain proportion of PMMA photoresist and place it in a beaker. Slowly add solvent along the edge of the beaker and stir at 100-500 r / min for 10-30 min. After the solution is mixed evenly, slowly add the active agent and stir at 200-500 r / min for 5-20 min to obtain a uniform mixed solution. Let the uniform mixed solution obtained in the above steps stand in the dark to obtain the modified and transferable PMMA photoresist.
[0016] Further, the method includes: weighing a certain proportion of PMMA photoresist into a beaker, slowly adding solvent along the edge of the beaker, stirring at a speed of 100-200 r / min for 15-25 min, and slowly adding active additives after the solution is evenly mixed, stirring at a speed of 100-150 r / min for 10-15 min to obtain a uniform mixed solution; degassing the uniform mixed solution obtained in the above steps, and letting it stand in the dark to obtain modified transferable PMMA photoresist.
[0017] Furthermore, the selected PMMA photoresist is PMMA-A8 photoresist, the selected solvent is anisole, and the active agent includes at least one of polyether-modified acrylic-functionalized polydimethylsiloxane, dodecylbenzenesulfonic acid, sodium dodecyl sulfate, octylphenol polyoxyethylene ether, and dodecylphenol. The modified transferable PMMA photoresist is PMMA-A2 photoresist. The ratio of PMMA-A8 photoresist, solvent, and active agent is 1:3:0.02.
[0018] The technical advantages of the short-wavelength, large-area conformal contact photolithography process provided by this invention are at least reflected in: By employing a low-cost, spontaneously emitting vacuum ultraviolet light source as the exposure source, and using transferable polymethyl methacrylate (PMMA) photoresist and its derivatives with strong absorption characteristics for the corresponding wavelengths, conformal contact lithography technology is used to ensure efficient energy coupling between the light source radiation and the photoresist, and high-fidelity pattern transfer. This not only achieves high-fidelity pattern transfer of sub-200nm structures, but also enables large-area batch pattern processing on 3, 6, and 8-inch wafers. This reduces the construction and operation costs of short-wavelength lithography systems, simplifies the process flow, and meets the requirements of high resolution and high throughput.
[0019] The provided process not only has advantages such as simple structure, low cost, high resolution and large-format processing, but also is compatible with flexible substrates, providing a scalable solution for achieving wafer-level high-fidelity pattern transfer. Attached Figure Description
[0020] To more clearly illustrate the technical solutions of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0021] Figure 1 This is a process flow diagram.
[0022] Figure 2 This is a specific embodiment 1, showing the photoresist resolution limit pattern on a silicon wafer.
[0023] Figure 3 This is a large-area photoresist pattern on a 3, 6, or 8-inch silicon wafer in Specific Embodiment 1.
[0024] Figure 4 This is a metal pattern after metallization and removal of adhesive, as shown in Specific Embodiment 1. Detailed Implementation
[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0026] This invention provides a short-wavelength, large-area conformal contact lithography process to solve the technical problems of high manufacturing cost, complex system structure, and difficult maintenance of short-wavelength (222nm, 193nm, 172nm, etc.) lithography equipment. Example
[0027] In this embodiment, a short-wavelength, large-area conformal contact photolithography process is provided, and the photoresist preparation method includes: A certain proportion of PMMA-A8 photoresist was weighed and placed in a beaker. Solvent (anisole) was slowly added along the edge of the beaker, and the mixture was stirred at 200 rpm for 15 minutes. After the solution was homogeneous, the active agent (polyether-modified acrylic-functionalized polydimethylsiloxane) was slowly added, and the stirring speed was 100 rpm for 15 minutes to obtain a homogeneous solution. The homogeneous solution obtained in the above steps was then degassed and allowed to stand in the dark to obtain modified PMMA-A2 photoresist. The ratio of PMMA-A8 photoresist, solvent, and active agent was 1:3:0.02.
[0028] Figure 1 This is a schematic diagram of the process flow. For example... Figure 1 As shown, the basic processing flow of the short-wavelength, large-area conformal contact lithography process provided in this embodiment includes: Step 1: Substrate cleaning; ultrasonically clean the silicon wafer with deionized water for 5 minutes and then dry it with nitrogen gas.
[0029] Step 2: Coating; Using spin coating, at a low speed of 500 r / min for 10 s and a high speed of 2000 r / min for 60 s, a uniform and impurity-free near-zero adhesion PMMA photoresist (thickness approximately 120 nm) is obtained on the silicon substrate.
[0030] Step 3: Pre-baking; After the photoresist is applied, place it on a hot plate and heat it at 180°C for 5 minutes to slowly remove excess solvent from the photoresist.
[0031] Step 4: Peeling; Slowly conformally bond the PDMS to the photoresist surface and peel the photoresist off the substrate without damage.
[0032] Step 5: Exposure; Conformally bond PDMS and photoresist to the mask and expose for 30 seconds using a 172nm vacuum ultraviolet lithography machine.
[0033] Step 6: Release; release the photoresist onto the silicon wafer without damage on a hot plate at 80°C.
[0034] Step 7: Development; Use immersion development to develop the photoresist released onto the silicon wafer in the developing solution for 30 seconds.
[0035] Step 8: Metal deposition; Chromium metallization of the photoresist structure is achieved using a thermal evaporation device.
[0036] Step 9: Dry photoresist removal; a heat-release tape is used to achieve dry removal of the photoresist, resulting in a high-precision metallic chromium structure.
[0037] Step 10: Dry etching; ICP etching is used to obtain a large-aperture superlens for long-distance infrared imaging.
[0038] Figure 2 The photoresist resolution limit pattern on the silicon wafer in Specific Embodiment 1 demonstrates that the sub-200nm limit resolution can be achieved using the 172nm conformal contact lithography of the present invention.
[0039] Figure 3 The large-area photoresist patterns on 3, 6, and 8-inch wafers on silicon wafers in Specific Embodiment 1 demonstrate that this disclosure enables the rapid and low-cost fabrication of large-area, multi-scale structures.
[0040] Figure 4The metal pattern shown in Specific Embodiment 1 after metallization and photoresist removal demonstrates that the disclosure does not require toxic chemical reagents for photoresist removal; only adhesive tape is needed to remove the photoresist, which is environmentally friendly, fast, and low-cost.
[0041] The process method of Specific Embodiment 1 uses a low-cost spontaneously emitting vacuum ultraviolet light source as the exposure light source and a transferable polymethyl methacrylate (PMMA) photoresist and its derivatives with strong absorption characteristics for the corresponding wavelength. It adopts conformal contact lithography technology to ensure efficient energy coupling between the light source radiation and the photoresist and high-fidelity pattern transfer. This not only realizes high-fidelity pattern transfer of sub-200nm structures, but also enables large-area batch pattern processing on 3, 6, and 8-inch wafers. It reduces the construction and operation costs of short-wavelength lithography systems, simplifies the process flow, and takes into account the requirements of high resolution and high throughput. Example
[0042] In this embodiment, a short-wavelength, large-area conformal contact photolithography process is described, and the photoresist preparation method includes: Weigh a certain proportion of PMMA-A8 photoresist into a beaker, then slowly add solvent (anisole) along the edge of the beaker. Stir at 150 rpm for 10 minutes until the solution is homogeneous. Then slowly add the active agent (polyether-modified acrylic-functionalized polydimethylsiloxane) at 200 rpm for 10 minutes to obtain a homogeneous mixture. Degas the homogeneous mixture obtained in the above steps and let it stand in the dark to obtain modified PMMA-A2 photoresist. The ratio of PMMA-A8 photoresist, solvent, and active agent is 1:3:0.02.
[0043] In this embodiment, a short-wavelength, large-area conformal contact lithography process is also provided, the basic processing flow of which includes: Step 1: Substrate cleaning; ultrasonically clean the silicon wafer with deionized water for 5 minutes and then dry it with nitrogen gas.
[0044] Step 2: Coating; Using spin coating, at a low speed of 500 r / min for 10 s and a high speed of 3000 r / min for 60 s, a uniform and impurity-free near-zero adhesion PMMA photoresist (approximately 100 nm thick) is obtained on the silicon substrate.
[0045] Step 3: Pre-baking; After the photoresist is applied, place it on a hot plate and heat it at 180°C for 3 minutes to slowly remove excess solvent from the photoresist.
[0046] Step 4: Peeling; Slowly conformally bond the PDMS to the photoresist surface and peel the photoresist off the substrate without damage.
[0047] Step 5: Exposure; Conformally bond PDMS and photoresist to the mask and expose for 20 seconds using a 172nm vacuum ultraviolet lithography machine.
[0048] Step 6: Release; release the photoresist onto the silicon wafer without damage on a hot plate at 80°C.
[0049] Step 7: Development; Use immersion development to develop the photoresist released onto the silicon wafer in the developing solution for 30 seconds.
[0050] Step 8: Metal deposition; Metallization of chromium and silver in the photoresist structure is achieved using an ion beam sputtering device.
[0051] Step 9: Dry photoresist removal; a heat-release tape is used to achieve dry removal of the photoresist, resulting in a high-precision chromium and silver structure.
[0052] This technology not only has advantages such as simple structure, low cost, high resolution and large-format processing, but also is compatible with flexible substrates, providing a scalable solution for achieving wafer-level high-fidelity pattern transfer.
[0053] The above embodiments do not require expensive focusing optical systems and complex exposure control equipment, and have the characteristics of low cost, simple process and strong environmental adaptability, showing broad application prospects in the fields of micro-nano optical components, flexible electronics, and subwavelength structure manufacturing. Example
[0054] In this embodiment, a short-wavelength, large-area conformal contact photolithography process is provided, and the photoresist preparation method includes: Weigh a certain proportion of PMMA-A8 photoresist into a beaker, then slowly add solvent (anisole) along the edge of the beaker. Stir at 150 rpm for 10 minutes until the solution is homogeneous. Then slowly add the active agent (polyether-modified acrylic-functionalized polydimethylsiloxane) at 200 rpm for 10 minutes to obtain a homogeneous mixture. Degas the homogeneous mixture obtained in the above steps and let it stand in the dark to obtain modified PMMA-A2 photoresist. The ratio of PMMA-A8 photoresist, solvent, and active agent is 1:3:0.02.
[0055] In this embodiment, a short-wavelength, large-area conformal contact lithography process is also provided, the basic processing flow of which includes: Step 1: Substrate cleaning; ultrasonically clean the silicon wafer with deionized water for 5 minutes and then dry it with nitrogen gas.
[0056] Step 2: Coating; Using spin coating, at a low speed of 500 r / min for 10 s and a high speed of 3000 r / min for 60 s, a uniform and impurity-free near-zero adhesion PMMA photoresist (approximately 100 nm thick) is obtained on the silicon substrate.
[0057] Step 3: Pre-baking; After the photoresist is applied, place it on a hot plate and heat it at 180°C for 3 minutes to slowly remove excess solvent from the photoresist.
[0058] Step 4: Peeling; Slowly conformally bond the PDMS to the photoresist surface and peel the photoresist off the substrate without damage.
[0059] Step 5: Exposure; Conformally bond PDMS and photoresist to the mask and expose for 20 seconds using a 172nm vacuum ultraviolet lithography machine.
[0060] Step 6: Release; release the photoresist onto the silicon wafer without damage on a hot plate at 80°C.
[0061] Step 7: Development; Use immersion development to develop the photoresist released onto the silicon wafer in the developing solution for 30 seconds.
[0062] Step 8: Metal deposition; Metallization of chromium in the photoresist structure is achieved using a magnetron sputtering device.
[0063] Step 9: Dry photoresist removal; PI tape is used to achieve dry removal of photoresist, resulting in a high-precision metallic chromium structure.
[0064] The above embodiments not only achieve high-fidelity pattern transfer of sub-200nm structures, but also enable large-area batch pattern processing on 3-, 6-, and 8-inch wafers. This not only reduces the construction and operating costs of short-wavelength lithography systems and simplifies the process flow, but also balances the requirements of high resolution and high throughput. Example
[0065] In this embodiment, a short-wavelength, large-area conformal contact photolithography process is provided, and the photoresist preparation method includes: Weigh a certain proportion of PMMA-A8 photoresist into a beaker, then slowly add solvent (anisole) along the edge of the beaker. Stir at 150 rpm for 15 minutes until the solution is homogeneous. Then slowly add the active agent (polyether-modified acrylic-functionalized polydimethylsiloxane) while stirring at 200 rpm for 15 minutes to obtain a homogeneous mixture. De-aerator the homogeneous mixture obtained in the above steps and allow it to stand in the dark to obtain modified PMMA-A2 photoresist. The ratio of PMMA-A8 photoresist, solvent, and active agent is 1:3:0.02.
[0066] A short-wavelength, large-area conformal contact lithography process is also provided, the basic processing flow of which includes: Step 1: Substrate cleaning; ultrasonically clean the silicon wafer with deionized water for 5 minutes and then dry it with nitrogen gas.
[0067] Step 2: Coating; Using spin coating, at a low speed of 500 r / min for 10 s and a high speed of 2000 r / min for 60 s, a uniform and impurity-free near-zero adhesion PMMA photoresist (thickness approximately 120 nm) is obtained on the silicon substrate.
[0068] Step 3: Pre-baking; After the photoresist is applied, place it on a hot plate and heat it at 180°C for 5 minutes to slowly remove excess solvent from the photoresist.
[0069] Step 4: Peeling; Slowly conformally bond the PDMS to the photoresist surface and peel the photoresist off the substrate without damage.
[0070] Step 5: Exposure; Conformally bond PDMS and photoresist to the mask and expose for 25 seconds using a 172nm vacuum ultraviolet lithography machine.
[0071] Step 6: Release; release the photoresist onto the silicon wafer without damage on a hot plate at 80°C.
[0072] Step 7: Development; Use immersion development to develop the photoresist released onto the silicon wafer in the developing solution for 30 seconds.
[0073] Step 8: Metal deposition; Metallize the silver in the photoresist structure using a thermal evaporation device.
[0074] Step 9: Dry photoresist removal; PI tape is used to achieve dry removal of photoresist, resulting in a high-precision metallic silver structure.
[0075] Based on the above embodiments, the present invention uses a low-cost spontaneously emitting vacuum ultraviolet (VUV) 172nm light source as the exposure light source, combines a transferable polymethyl methacrylate (PMMA) photoresist and its derivatives with strong absorption characteristics for the 172nm wavelength, and employs conformal contact lithography (PCCL) technology to ensure efficient energy coupling between the light source radiation and the photoresist and high-fidelity transfer of the pattern.
[0076] This disclosure not only achieves high-fidelity pattern transfer of sub-200nm structures, but also enables large-area batch pattern processing on 3-, 6-, and 8-inch wafers. It not only reduces the construction and operating costs of short-wavelength lithography systems and simplifies the process flow, but also simultaneously meets the requirements of high resolution and high throughput. It has enormous application potential in emerging fields such as micro / nanoelectronic device manufacturing, advanced optical component processing, and flexible electronics, laying a solid foundation for the development of next-generation low-cost, high-performance lithography technology.
[0077] This invention has been described in detail, and specific examples have been used to illustrate the principles and implementation methods of this invention. The above embodiments are only used to help understand the method and core ideas of this invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this invention. Therefore, the content of this specification should not be construed as a limitation of this invention.
[0078] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process of the system and unit described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.
Claims
1. A short-wavelength, large-area conformal contact photolithography process, characterized in that, The process includes: S100. Ultrasonically clean the substrate with deionized water for 5 minutes and then dry it with nitrogen gas; S200. A uniform, impurity-free, near-zero adhesion photoresist film is obtained by spin coating. S300. Place it on a hot plate and heat at 180°C for 3-5 minutes to slowly remove excess solvent from the photoresist; S400. Slowly conformally attach the stamp to the photoresist surface and peel the photoresist off the substrate without damage. S500. The stamp and photoresist are conformally bonded to the mask and exposed using a 172nm vacuum ultraviolet lithography machine; S600. Photoresist is released onto the silicon wafer without damage on a hot plate at 80°C; S700. Uses immersion developing, which develops the photoresist released onto the silicon wafer in a developing solution; S800. Metal deposition is performed using a metal deposition device to achieve metallization of the photoresist structure; S900. A dry method for removing photoresist is achieved using adhesive tape, resulting in a high-precision metal structure.
2. The short-wavelength, large-area conformal contact photolithography process according to claim 1, characterized in that, The substrate includes at least one of silicon wafer and silicon dioxide.
3. The short-wavelength, large-area conformal contact photolithography process according to claim 1, characterized in that, The photoresist is a modified transferable photoresist, wherein the ratio of modified transferable photoresist:solvent:active agent is 1:3:0.
02.
4. The short-wavelength, large-area conformal contact photolithography process according to claim 3, characterized in that, The solvent is anisole, and the active additives include at least one of polyether-modified acrylic functionalized polydimethylsiloxane, dodecylbenzenesulfonic acid, sodium dodecyl sulfate, octylphenol polyoxyethylene ether, and dodecylphenol.
5. The short-wavelength, large-area conformal contact photolithography process according to claim 3, characterized in that, The method for preparing the modified transferable photoresist includes weighing a certain proportion of PMMA photoresist into a beaker, slowly adding solvent, stirring at a speed of 100-500 r / min for 10-30 min, and slowly adding an active agent after the solution is evenly mixed, stirring at a speed of 200-500 r / min for 5-20 min to obtain a uniform mixed solution and letting it stand in the dark.
6. The short-wavelength, large-area conformal contact photolithography process according to claim 5, characterized in that, The method for preparing the modified transferable photoresist includes weighing a certain proportion of PMMA photoresist into a beaker, slowly adding solvent, stirring at a speed of 100-200 r / min for 15-25 min, and slowly adding active additives after the solution is evenly mixed, stirring at a speed of 100-150 r / min for 10-15 min, obtaining a uniform mixed solution, performing bubble removal treatment, and letting it stand in the dark.
7. The short-wavelength, large-area conformal contact photolithography process according to claim 1, characterized in that, The stamp includes at least one of polydimethylsiloxane (PDMS) film, polyurethane (TPU) film, and heat-release tape.
8. The short-wavelength, large-area conformal contact photolithography process according to claim 1, characterized in that, The developer is a mixture of MIBK and IPA in a 1:3 ratio, and the development time ranges from 30 to 60 seconds.
9. The short-wavelength, large-area conformal contact photolithography process according to claim 1, characterized in that, The metal deposition equipment includes at least one of thermal evaporation, ion beam sputtering, magnetron sputtering, and atomic layer deposition.
10. The short-wavelength, large-area conformal contact photolithography process according to claim 1, characterized in that, The tape includes at least one type of PI tape and heat-release tape.