A flexible photolithography mask high-efficiency batch preparation process

Abstract

The application discloses a kind of flexible photolithography mask high-efficiency batch preparation process, belong to micro-nano manufacturing field.It includes: silicon substrate cleaning;Get the uniform distribution of defect-free low interface adhesion transferable photoresist film on silicon substrate.Remove solvent in the glue layer and improve the mechanical scratch resistance of photoresist film.Transfer, transfer photoresist to flexible stamp.Hard master mask pattern is proportionally transferred to photoresist.Hard master mask pattern is proportionally copied to photoresist.Metal deposition;Through the deposition of a layer of opaque metal, finally realize the efficient, low-cost preparation of large-area high-resolution flexible mask.Use adhesive tape to slowly peel off the metal and photoresist outside the structure, and get large-area high-resolution flexible mask.The application not only provides a more reliable and efficient process for traditional flexible mask processing and manufacturing, making the manufacturing process more stable and efficient, but also meets the manufacturing demand of large area.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of micro-nano manufacturing, and in particular to a flexible photomask high-efficiency batch preparation process. BACKGROUND

[0002] Optical imaging technology represented by large-aperture, sub-micron superlens; health monitoring technology represented by large-area stretchable flexible electronics; electromagnetic shielding technology represented by high aspect ratio, large-format transparent metal mesh, etc. have important application value in aerospace, national defense security, biomedical, advanced manufacturing and consumer electronics, etc. High-end industries. Among them, the preparation of large-area sub-micron structure is the most important. Therefore, many sub-micron structure preparation technologies have been developed accordingly, such as electron beam / laser beam / ion beam direct writing photolithography, projection photolithography, extreme ultraviolet lithography, nanoimprint, near-field photolithography, etc. Direct writing photolithography can process high-precision nanostructures in two-dimensional plane, but its point-by-point processing efficiency is low, the equipment is expensive, and it cannot meet the demand of high-efficiency and low-cost manufacturing of large-area structure; projection, extreme ultraviolet optical lithography can meet the requirements of large-area sub-micron structure preparation, but the design and manufacture of optical system is complex, the cost is high and the energy consumption is high; nanoimprint is one of the existing solutions to realize low-cost preparation of large-area sub-micron structure, but its high-precision mask preparation is difficult, the stress damage is large, it is easy to be contaminated, and the yield is low. Although the resolution of traditional contact photolithography is limited by the optical diffraction limit, the flexible mask proposed by researchers can realize perfect conformal near-field photolithography, which is expected to become a key technology that takes into account resolution and manufacturing area, cost and yield, and realize high-efficiency preparation of large-area micro-nano structure. However, there are still two challenges in the preparation of flexible mask: on the one hand, the manufacturing of flexible mask is not compatible with traditional lithography manufacturing process, its manufacturing combines electron beam direct writing process and subsequent assembly process, which increases the manufacturing complexity and reduces the manufacturing efficiency, making it difficult to meet the demand of industrial scale use; on the other hand, the preparation of most flexible masks is not in-situ manufacturing, and usually includes chemical or dry etching process, which not only lengthens the entire preparation process, but also easily damages the interface adhesion and affects the stability and durability of the flexible mask. Therefore, the development of a flexible photomask high-efficiency batch preparation technology greatly improves the manufacturing capability in the field of micro-nano, and also becomes the key to the scale use of various high-end industries. SUMMARY

[0003] In view of this, the present application provides a flexible photomask high-efficiency batch preparation process, which realizes near-field photolithography, metallization process, dry adhesive process, etc. by using low-interface adhesive photoresist, completes proportional, high-fidelity, large-area replication of hard master mask to flexible working mask, and finally realizes large-area high-resolution flexible mask rapid batch preparation. The present application not only solves the problems of flexible mask processing and manufacturing difficulty, poor process compatibility, low manufacturing efficiency, etc., but also realizes perfect conformal contact photolithography by using flexible mask, and has the processing advantages of resolution, manufacturing width, cost and yield.

[0004] A flexible photomask high-efficiency batch preparation process. The basic processing flow process includes:

[0005] Step one: silicon substrate cleaning; the silicon substrate is ultrasonically cleaned with deionized water for 5 minutes and dried with nitrogen, so that the silicon substrate surface is dry and clean.

[0006] Step two: glue coating; a static spin coating method is used to obtain a uniformly distributed defect-free low-interface adhesive transferable photoresist film on the silicon substrate.

[0007] Step three: pre-baking; after the glue coating is completed, it is placed on a hot plate at 80°C for 1-3 min to remove the solvent in the glue layer and improve the mechanical scratch resistance of the photoresist film.

[0008] Step four: transfer; slowly and bubble-free conformal paste the flexible stamp to the surface of the photoresist, and peel it off from the silicon substrate to realize the transfer of the photoresist to the flexible stamp.

[0009] Step five: exposure; slowly and bubble-free conformal paste the flexible stamp and photoresist to the hard master mask under the pressure applied by the roller press, and expose it to ultraviolet light for 2-15 s using a UV lithography machine to transfer the hard master mask pattern to the photoresist in proportion.

[0010] Step six: development; after exposure, the photoresist is developed in the developer for 3-10 s to copy the hard master mask pattern to the photoresist in proportion.

[0011] Step seven: metal deposition; finally realize the efficient and low-cost preparation of large-area high-resolution flexible mask by depositing a layer of opaque metal. The specific thickness of the opaque metal depends on its specific requirements.

[0012] Step eight: dry adhesive; slowly peel off the metal and photoresist outside the structure with adhesive tape to obtain a large-area high-resolution flexible mask.

[0013] Preferably, the substrate in step one includes at least one of a silicon wafer and a silicon dioxide wafer.

[0014] Preferably, the low interfacial adhesion transferable photoresist in step two comprises at least one of water-based polyvinyl alcohol series photoresist, SU-8 series photoresist, and red light photoresist.

[0015] Preferably, the pre-baking time in step three comprises 1 min (water-based polyvinyl alcohol series photoresist pre-baking time), 3 min (SU-8 photoresist pre-baking time), and 1 min (red light photoresist pre-baking time).

[0016] Preferably, the flexible stamp in step four comprises at least one of polydimethylsiloxane film and thermoplastic polyurethane film.

[0017] Preferably, the exposure time in step five comprises 2-5 s (water-based polyvinyl alcohol series photoresist exposure time), 10-15 s (SU-8 photoresist exposure time), and 10-25 s (red light photoresist exposure time).

[0018] Preferably, the developing solution in step six comprises deionized water (water-based polyvinyl alcohol series photoresist developing solution), SU-8 developing solution, and sodium hydroxide aqueous solution (red light photoresist developing solution).

[0019] Preferably, the metal deposition method in step seven comprises at least one of thermal evaporation, ion beam sputtering, magnetron sputtering, and atomic layer deposition.

[0020] Preferably, the dry stripping tape in step eight comprises at least one of thermal release tape, polyimide tape, and ultraviolet release tape.

[0021] The present application not only provides a more reliable and efficient process for traditional flexible mask manufacturing, making the manufacturing process more stable and efficient, but also realizes perfect conformal contact photolithography using a flexible mask, which can achieve better contact and contact force distribution in the photolithography process, thereby improving the accuracy and consistency of photolithography, realizing high-resolution manufacturing, and also meeting the demand for large-area manufacturing. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the present application, the following will briefly introduce the drawings needed in the embodiment description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0023] Figure 1 is a process flow chart.

[0024] Figure 2 is a water-based polyvinyl alcohol photoresist pattern on a polydimethylsiloxane film in Example 1.

[0025] Figure 3 SU-8 photoresist pattern on polydimethylsiloxane film for Example 3.

[0026] Figure 4 Microscope image of flexible mask: chromium metal pattern on polydimethylsiloxane film for Example 1. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work are within the protection scope of the present application. EMBODIMENT

[0028] A flexible photomask efficient batch preparation process. The process comprises:

[0029] Step one: substrate cleaning; the substrate is ultrasonically cleaned with deionized water for 5 minutes and dried with nitrogen, keeping the substrate surface dry and clean.

[0030] Step two: gluing; using static spin coating method, low speed 500 r / min, 10 s, high speed 2000 r / min, 60 s to get uniform distribution of low interfacial adhesion transferable water-based polyvinyl alcohol photoresist on silicon substrate (thickness about 380 nm).

[0031] Step three: pre-baking; after gluing, put it on the hot plate at 80°C for 1 min to remove the solvent in the glue layer and improve the mechanical scratch resistance of the glue film.

[0032] Step four: transfer; transfer the photoresist to the flexible stamp. Specific operation: slowly bubble-free conformal attachment of polydimethylsiloxane film to the surface of water-based polyvinyl alcohol photoresist, and peeling off from the silicon substrate.

[0033] Step five: exposure; the stamp and photoresist are perfectly conformally contacted with the hard master mask, and the UV lithography machine is used for exposure, and the hard master mask pattern is proportionally transferred to the photoresist. Specific operation: slowly bubble-free attachment of polydimethylsiloxane film and water-based polyvinyl alcohol photoresist to the hard master mask under the pressure applied by the rolling machine, and exposure for 2 s.

[0034] Step six: development; using immersion development, the hard master mask pattern is proportionally copied to the photoresist. Specific operation: develop the exposed photoresist in the developing solution for 4 s.

[0035] Step seven: metal deposition; the final realization of large area high resolution flexible mask of high efficiency, low cost preparation, then need to deposit a layer of opaque metal. Specific operation: using thermal evaporation metal deposition process in photoresist mask pattern on the deposition of a layer of chromium metal (thickness of about 30 nm).

[0036] Step eight: dry stripping; finally get flexible mask, using dry stripping. Specific operation: with polyimide tape outside the metal and photoresist slowly peeling off, get large area high resolution flexible mask. Embodiment

[0037] A kind of flexible photoetching mask high efficiency batch preparation process. Process includes:

[0038] Step one: substrate cleaning; the substrate is cleaned with deionized water for 5 minutes, and nitrogen is blown dry, keep the substrate surface dry and clean.

[0039] Step two: glue; using static spin coating method, low speed 500 r / min, 10 s, high speed 1500 r / min, 60 s to get uniform distribution of defect-free low interface adhesion transferable water-based polyvinyl alcohol photoresist on silicon substrate (thickness of about 500 nm).

[0040] Step three: prebaking; after coating, put it on the hot plate 80 ℃ heating 1 min. Remove the solvent in the glue layer and improve the mechanical scratch resistance of the glue film.

[0041] Step four: transfer; the photoresist is transferred to the flexible stamp. Specific operation: the polydimethylsiloxane film is slowly and bubble conformal attached to the surface of the water-based polyvinyl alcohol photoresist, and is peeled off from the silicon substrate.

[0042] Step five: exposure; the stamp and photoresist perfect conformal contact hard master mask, and use ultraviolet photoetching machine exposure, the hard master mask pattern is proportionally transferred to the photoresist. Specific operation: the polydimethylsiloxane film and water-based polyvinyl alcohol photoresist are slowly and bubble conformal attached to the hard master mask under the pressure of the rolling machine, and are exposed for 3 s.

[0043] Step six: development; using immersion development, the hard master mask pattern is proportionally copied to the photoresist. Specific operation: the exposed photoresist is developed in the developing solution for 5 s.

[0044] Step seven: metal deposition; the final realization of large area high resolution flexible mask of high efficiency, low cost preparation, then need to deposit a layer of opaque metal. Specific operation: using ion beam sputtering metal deposition process in photoresist mask pattern on the deposition of a layer of chromium metal (thickness of about 30 nm).

[0045] Step eight: dry stripping; the last stripping gets the flexible mask, which adopts dry stripping. Specific operation: the metal and photoresist outside the structure are slowly peeled off by polyimide tape, and a large-area high-resolution flexible mask is obtained. Embodiment

[0046] A flexible photomask efficient batch preparation process. The process includes:

[0047] Step one: substrate cleaning; the silicon wafer is ultrasonically cleaned with deionized water for 5 minutes and dried with nitrogen, keeping the substrate surface dry and clean.

[0048] Step two: glue coating; static spin coating is adopted, low speed 500 r / min, 10 s, high speed 5000 r / min, 60 s, to get uniform distribution of low interfacial adhesion defect-free transferable SU-8 photoresist on the silicon substrate.

[0049] Step three: pre-baking; after coating, it is placed on the hot plate at 80℃ for 3 min to remove the solvent in the glue layer and improve the mechanical scratch resistance of the glue film.

[0050] Step four: transfer; the photoresist is transferred to the flexible stamp. Specific operation: the polydimethylsiloxane film is slowly and bubble-free conformally attached to the surface of the SU-8 photoresist, and peeled off from the silicon substrate.

[0051] Step five: exposure; the stamp and photoresist are perfectly conformally contacted with the hard master mask, and the UV lithography machine is used for exposure, and the hard master mask pattern is proportionally transferred to the photoresist. Specific operation: the polydimethylsiloxane film and SU-8 photoresist are bubble-free attached to the hard master mask under the pressure applied by the rolling machine, and exposed for 6 s.

[0052] Step six: post-baking; SU-8 photoresist is a chemical amplification resist, and post-baking is also called cross-linking baking. The photoacid generated in exposure causes cross-linking reaction of the polymer in cross-linking baking. Specific operation: it is placed on the hot plate at 80℃ for 3 min.

[0053] Step seven: development; immersion development is adopted to proportionally copy the hard master mask pattern to the photoresist. Specific operation: the exposed photoresist is developed in the developer for 10 s.

[0054] Step eight: metal deposition; the final realization of the efficient and low-cost preparation of large-area high-resolution flexible mask requires the deposition of a layer of opaque metal. Specific operation: a layer of chromium metal (thickness about 30 nm) is deposited on the photoresist mask pattern by using thermal evaporation metal deposition process.

[0055] Step nine: dry stripping; the last stripping gets the flexible mask, which adopts dry stripping. Specific operation: the metal and photoresist outside the structure are slowly peeled off by polyimide tape, and a large-area high-resolution flexible mask is obtained. Embodiment

[0056] A flexible photomask efficient batch preparation process. The process includes:

[0057] Step one: substrate cleaning; the silicon wafer is ultrasonically cleaned with deionized water for 5 minutes and dried with nitrogen, keeping the substrate surface dry and clean.

[0058] Step two: glue coating; a static spin coating method is adopted, with a low speed of 500 r / min for 10 s and a high speed of 3000 r / min for 60 s to obtain a uniform distribution of defect-free low-interface adhesive transferable SU-8 photoresist on the silicon substrate.

[0059] Step three: pre-baking; after the coating is completed, it is placed on a hot plate at 80°C for 3 min to remove the solvent in the glue layer and improve the mechanical scratch resistance of the glue film.

[0060] Step four: transfer; transfer the photoresist to the flexible stamp. Specific operation: slowly conformal attach the polydimethylsiloxane film to the surface of the SU-8 photoresist without air bubbles, and peel it off from the silicon substrate.

[0061] Step five: exposure; the stamp and photoresist are perfectly conformal contact with the hard master mask, and the UV lithography machine is used for exposure, and the hard master mask pattern is transferred to the photoresist in proportion. Specific operation: the polydimethylsiloxane film and SU-8 photoresist are bubble-free attached to the hard master mask under the pressure applied by the rolling machine, and exposed for 6 s.

[0062] Step six: post-baking; SU-8 photoresist is a chemical amplification resist, and post-baking is also called crosslinking baking. The photoacid generated in the exposure makes the polymer crosslinking reaction in the crosslinking baking. Specific operation: place it on a hot plate at 80°C for 3 min.

[0063] Step seven: development; the hard master mask pattern is copied to the photoresist in proportion by immersion development. Specific operation: the exposed photoresist is developed in the developer for 10 s.

[0064] Step eight: metal deposition; the final realization of the process is the efficient and low-cost preparation of a large-area high-resolution flexible mask, which requires the deposition of a layer of opaque metal. Specific operation: a layer of chromium metal (thickness about 30 nm) is deposited on the photoresist mask pattern by ion beam sputtering metal deposition process.

[0065] Step nine: dry stripping; the last stripping to obtain the flexible mask, using dry stripping. Specific operation: the metal and photoresist outside the structure are slowly peeled off with polyimide tape to obtain a large-area high-resolution flexible mask.

[0066] Take examples 1 and 3 as examples: please refer to Figure 1 Figure 2 Figure 3 and Figure 4 ; Figure 1 is a process flow diagram; Figure 2 and Figure 3 is the result of copying the hard master mask pattern to the flexible working template, and then after the metal deposition and dry stripping step, the metal pattern Figure 4 , Figure 4 Microscope picture of the flexible mask prepared in example 1: chromium metal pattern on a polydimethylsiloxane film. From the picture, it can be seen that the mask pattern obtained by conformal attachment of a transferable photoresist to a hard master mask, exposure and development is very high in accuracy. And in the preparation method of examples 1-4, the chromium metal is directly prepared in situ on the flexible stamp, and no solvent is contacted during the preparation process, and no electron beam, etching and other time-consuming, high-cost manufacturing methods are used. The two existing problems of the flexible mask are solved: first, the transferable photoresist can solve the problem of incompatibility between the manufacture of the flexible mask and the traditional lithography manufacturing process, the complexity, low efficiency and high cost of the electron beam direct writing process; second, the metal preparation of the flexible mask is prepared in situ, and does not include chemical or dry etching process, which reduces the entire preparation process and enhances the adhesion between interfaces, thereby improving the stability and durability of the flexible mask. In summary, with the help of low interfacial adhesion transferable photoresist, the flexible mask can be efficiently, low-cost and large-scale prepared, which has great application prospects in typical devices such as large-aperture infrared superlens, nanoscale large-area flexible electronics, transparent conductive metal mesh, and curved optical electronic devices.

[0067] This paper makes a detailed introduction, and the principle and implementation mode of the application are described by applying specific examples; the above examples are only used to help understand the method and core idea of the application; at the same time, for those skilled in the art, according to the idea of the application, the specific implementation mode and application range will be changed; in view of the above, the content of the specification should not be understood as a limitation of the application.

[0068] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the system and unit described above can refer to the corresponding process in the foregoing method embodiments, which will not be repeated here.

Claims

1. A flexible photomask high-efficiency batch production process, characterized in that, The preparation process comprises the following steps: Step one: cleaning the silicon substrate; the silicon substrate is cleaned with deionized water and dried with nitrogen, keeping the surface of the silicon substrate dry and clean; Step two: coating glue; a static spin coating method is used to obtain a uniform distribution of defect-free low interfacial adhesion transferable photoresist film on the silicon substrate; Step three: pre-baking; after coating, the sample is placed on a hot plate at 80°C to remove the solvent in the glue layer and improve the mechanical scratch resistance of the photoresist film; Step four: transfer; the flexible stamp is slowly and bubble-free conformally attached to the surface of the photoresist, and is peeled off from the silicon substrate, realizing the transfer of the photoresist to the flexible stamp; Step five: exposure; the flexible stamp and photoresist are bubble-free attached to the hard master mask under the pressure applied by the roller press, and are exposed to ultraviolet light for 2-15 s, transferring the pattern of the hard master mask to the photoresist in a proportional manner; Step six: development; the exposed photoresist is developed in a developing solution for 3-10 s, copying the pattern of the hard master mask to the photoresist in a proportional manner; Step seven: metal deposition; By depositing a layer of light-tight metal, efficient and low-cost preparation of large-area high-resolution flexible mask is finally achieved; Step eight: dry stripping; The metal and photoresist outside the structure are slowly peeled off with adhesive tape, obtaining a large-area high-resolution flexible mask.

2. The process according to claim 1, wherein, The substrate in step one comprises at least one of a silicon wafer and a silicon dioxide wafer.

3. The process according to claim 1, wherein, The low interfacial adhesion transferable photoresist in step two comprises at least one of a water-based polyvinyl alcohol series photoresist, an SU-8 series photoresist, and a Ruishi photoresist.

4. The process according to claim 3, wherein, In the pre-baking time in step three, the pre-baking time of the water-based polyvinyl alcohol series photoresist is 1 min, the pre-baking time of the SU-8 photoresist is 3 min, and the pre-baking time of the Ruishi photoresist is 1 min.

5. The process according to claim 1, wherein, The flexible stamp in step four comprises at least one of a polydimethylsiloxane film and a thermoplastic polyurethane film.

6. The process according to claim 3, wherein, In the exposure time in step five, the exposure time of the water-based polyvinyl alcohol series photoresist is 2-5 s, the exposure time of the SU-8 photoresist is 10-15 s, and the exposure time of the Ruishi photoresist is 10-25 s.

7. The process according to claim 3, wherein, The developing solution in step six comprises deionized water, an SU-8 developing solution, and a sodium hydroxide aqueous solution; the deionized water is a developing solution for the water-based polyvinyl alcohol series photoresist; and the sodium hydroxide aqueous solution is a developing solution for the Ruishi photoresist. 8.The process of claim 1, wherein, The metal deposition method in step seven comprises at least one of thermal evaporation, ion beam sputtering, magnetron sputtering, and atomic layer deposition. 9.The process of claim 1, wherein, The dry stripping adhesive tape in step eight comprises at least one of a thermal release adhesive tape, a polyimide adhesive tape, and a UV release adhesive tape.

10. The process of claim 1, wherein, The low interfacial adhesion photoresist is used to realize near-field lithography, metallization process, and dry stripping process, to complete the proportional, high-fidelity, and large-area copying of the hard master mask to the flexible working mask, and finally realize the rapid and batch preparation of large-area high-resolution flexible mask.

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