A maleimide-based self-initiating two-photon photoresist and its preparation and patterning method

Abstract

The application discloses a maleimide-based self-initiating two-photon photoresist and a patterning method thereof. The maleimide-based self-initiating two-photon photoresist contains 100 parts of a maleimide compound, 10-30 parts of a polycyclopentenyl acrylate and 20-50 parts of a high-refractive fluorene-based active crosslinking agent. The maleimide-based self-initiating two-photon photoresist avoids the use of conventional two-photon initiators, thereby avoiding the migration and penetration of the residual photo-initiator and photolysis fragments in the common photoresist and the possibility of further photochemical reactions; the oxygen-blocking effect of the polycyclopentenyl acrylate can ensure the normal use of the photoresist in air; and the high-refractive fluorene-based active crosslinking agent can effectively adjust the refractive index of the photoresist to improve the writing effect. After the photoresist is written by a femtosecond laser and developed, two-dimensional lines with a feature size of hundreds of nanometers can be obtained, and three-dimensional structures with a size of hundreds of micrometers can also be written.

Description

Technical Field

[0001] This invention belongs to the field of laser micro-nano fabrication, and more specifically, relates to a self-initiated two-photon photoresist and its preparation and patterning method. Background Technology

[0002] The high-energy pulses of femtosecond lasers induce nonlinear absorption of photoresist materials using two-photon or multi-photon signals. Therefore, femtosecond lasers can be used to achieve three-dimensional, deep nanoscale resolution and maskless fabrication with arbitrary structural designs. Traditional photoresists require photoinitiators, and their concentrations are generally higher than theoretical levels, leaving significant initiator residues after irradiation. These residual photoinitiators and photodegradation debris can migrate, penetrate, and undergo further photochemical reactions, leading to problems such as volatile odors and yellowing.

[0003] Therefore, there is a need to provide a self-initiated two-photon photoresist and a patterning method. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing a maleimide-based self-initiated two-photon photoresist, its preparation method, and its patterning method.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0006] In a first aspect, the present invention provides a maleimide-based self-initiated two-photon photoresist, which, by weight, contains 100 parts of maleimide compound, 10-30 parts of polycyclopentenyl acrylate and 20-50 parts of high refractive index fluorene-based active crosslinking agent, and does not contain conventional two-photon initiators.

[0007] The structural formula of the maleimide compound is shown in formula (I) or (II):

[0008]

[0009] In equation (I), R1 is -C m H 2m OH, -C n H 2n+1 -C p H 2p OCOCH3, Where m is a natural number from 5 to 10, n is a natural number from 1 to 40, and p is a natural number from 2 to 10;

[0010]

[0011] In equation (II), x is a natural number from 1 to 5, and -R2- is either -CH2- or -O-.

[0012] The polycyclopentenyl acrylate is selected from at least one of the compounds with structural formulas as shown in formulas (III), (IV), and (V), and the polycyclopentenyl acrylate structure contains a highly polymerizable acrylate group and a low polymerizable cyclopentenyl group.

[0013]

[0014]

[0015] In equations (III), (IV), and (V), R3 is independently either -H or -CH3;

[0016] The high-refractive-index fluorene-based active crosslinking agent contains a fluorene ring matrix and acrylate substituents, selected from at least one compound with structures shown in formula (VI) and (VII).

[0017]

[0018] In equations (VI) and (VII), R6 and R7 are each independently -H or -CH3, R4 and R8 are each independently -H or -OH, and R5 and R9 are each independently -H or -C6H5.

[0019] Preferably, the maleimide-based self-initiated two-photon photoresist is made of 100 parts of maleimide compound, 10-30 parts of polycyclopentenyl acrylate and 20-50 parts of high refractive index fluorene active crosslinking agent.

[0020] In this invention, the conventional two-photon initiator refers to a compound that has nonlinear absorption of near-infrared femtosecond laser and can initiate two-photon radical polymerization, such as 2-isopropylthioxanthone, 7-diethylamino-3-thiophenecarboxylcoumarin, 3-(2-benzimidazolyl)-7-(diethylamino)coumarin, 7-diethylamino-3-(1-methyl-2-benzimidazolyl)coumarin, 3-(2'-benzothiazolyl)-7-diethylaminocoumarin, 3,3'-carbonylbis(7-diethylaminocoumarin), etc.

[0021] Secondly, the present invention provides a method for preparing the above-mentioned maleimide-based self-initiated two-photon photoresist, wherein the preparation method comprises: mixing maleimide compound, polycyclopentenyl acrylate and high refractive index fluorene-based active crosslinking agent in a yellow light chamber in a certain proportion to obtain a viscous maleimide-based self-initiated two-photon photoresist.

[0022] Thirdly, the present invention provides a patterning method for the above-mentioned maleimide-based self-initiated two-photon photoresist, comprising the following steps:

[0023] 1) Take maleimide-based self-initiated two-photon photoresist and drop it onto the substrate;

[0024] 2) Expose the two-photon photoresist using a femtosecond laser direct writing device;

[0025] 3) Immerse the exposed photoresist in the developing solution for development to obtain the photolithographic pattern.

[0026] Furthermore, in step 2), the femtosecond laser wavelength is 700-900nm, the laser pulse is 60-150fs, the laser repetition rate is 10-200MHz, the writing power is 5-20mW, and the writing speed is 0.1-100mm / s.

[0027] Further, in step 3), the developing solution is selected from one or more of n-butyl acetate, 1-ethoxy-2-propanol, isopropanol, propylene glycol methyl ether acetate, and ethyl 3-ethoxypropionate; the developing time is 6-30 min, and the developing temperature is room temperature. Even further, a two-stage developing process is used. The primary developing solution is selected from n-butyl acetate, 1-ethoxy-2-propanol, propylene glycol methyl ether acetate, or ethyl 3-ethoxypropionate, and the developing time is 5-15 min; the secondary developing solution is selected from isopropanol, and the developing time is 1-5 min.

[0028] This invention includes at least the following beneficial results:

[0029] 1. This invention provides a self-initiated two-photon photoresist based on maleimide. The N-alkyl-substituted maleimide possesses self-photosensitive properties and can self-crosslink and cure under two-photon laser irradiation, acting as both a reactive monomer and an initiator. Polycyclopentenyl acrylate contains an allyl structure, and the allyl hydrogen can act as a hydrogen donor to form a stable allyl radical. This allyl radical can absorb oxygen and generate hydrogen, further transforming into an allyl peroxide radical. In the presence of the N-alkyl-substituted maleimide, it decomposes into an active radical to continue initiating polymerization, while simultaneously acting as an oxygen barrier. The high-refractive-index fluorene-based active crosslinking agent has a relatively high refractive index, which is used to adjust the overall refractive index of the photoresist. Therefore, the maleimide-based self-initiated two-photon photoresist of the present invention avoids the use of conventional two-photon initiators, thereby avoiding the possibility of migration, penetration, and further photochemical reactions of residual photoinitiators and photolysis debris in ordinary photoresists; the oxygen barrier effect of polycyclopentenyl acrylate can ensure that the photoresist can be used normally in air; and the high refractive index fluorene-based active crosslinking agent can effectively adjust the refractive index of the photoresist to improve the writing effect.

[0030] 2. The present invention is based on maleimide self-initiated two-photon photoresist, which, after being written and developed by femtosecond laser, can obtain two-dimensional lines with feature sizes in the hundreds of nanometers, and can also write three-dimensional structures in the hundreds of micrometers. Attached Figure Description

[0031] Figure 1 This is an optical microscope image of the photoresist after femtosecond laser exposure and development in Example 4;

[0032] Figure 2 This is an electron microscope image of the photoresist after femtosecond laser exposure and development in Example 6;

[0033] Figure 3 This is an electron microscope image of the photoresist after femtosecond laser exposure and development in Example 8;

[0034] Figure 4 This is an optical microscope image of the photoresist after femtosecond laser exposure and development in Example 10;

[0035] Figure 5 This is an optical microscope image of the photoresist after femtosecond laser exposure and development in Example 11;

[0036] Figure 6 This is an optical microscope image of the photoresist after femtosecond laser exposure and development in Example 13;

[0037] Figure 7 This is a schematic diagram of the femtosecond laser direct writing device used in an embodiment of the present invention, wherein 1-femtosecond laser, 2-galvanometer, 3-objective lens, 4-displacement stage, and 5-photoresist. Detailed Implementation

[0038] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments, further clarifies the invention. However, those skilled in the art should understand that the specific description below is illustrative rather than restrictive and should not be construed as limiting the scope of protection of the present invention.

[0039] The present invention discloses a maleimide-based self-initiated two-photon photoresist, which, by weight, contains 100 parts of maleimide compound, 10-30 parts of polycyclopentenyl acrylate and 20-50 parts of high refractive index fluorene active crosslinking agent.

[0040] The structural formula of the maleimide compound is shown in formula (I) or (II):

[0041]

[0042] In equation (I), R1 is -C m H 2m OH, -C n H 2n+1 -C p H 2p OCOCH3, Where m is a natural number from 5 to 10, n is a natural number from 1 to 40, and p is a natural number from 2 to 10;

[0043]

[0044] In equation (II), x is a natural number from 1 to 5, and -R2- is either -CH2- or -O-.

[0045] The polycyclopentenyl acrylate is selected from at least one of the compounds with structural formulas as shown in formulas (III), (IV), and (V), and the polycyclopentenyl acrylate structure contains a highly polymerizable acrylate group and a low polymerizable cyclopentenyl group.

[0046]

[0047] In equations (III), (IV), and (V), R3 is independently either -H or -CH3;

[0048] The high-refractive-index fluorene-based active crosslinking agent contains a fluorene ring matrix and acrylate substituents, selected from at least one compound with structures shown in formula (VI) and (VII).

[0049]

[0050] In equations (VI) and (VII), R6 and R7 are each independently -H or -CH3, R4 and R8 are each independently -H or -OH, and R5 and R9 are each independently -H or -C6H5.

[0051] Based on the maleimide compound, if the maleimide compound accounts for 100 parts by weight, then the polycyclopentenyl acrylate is 10-30 parts; preferably, the polycyclopentenyl acrylate is 20-30 parts.

[0052] Based on the maleimide compound, if its proportion is 100 parts by weight, then the high refractive index fluorene-based active crosslinking agent is 20-50 parts; preferably, the high refractive index fluorene-based active crosslinking agent is 25-40 parts. Since the fluorene-based active crosslinking agent has a relatively high refractive index, it can improve the overall refractive index of the photoresist formulation, making the refractive indices of the photoresist and the writing system more matched, thus improving the writing effect; however, an excessively high refractive index can also affect the writing accuracy, so the amount of high refractive index fluorene-based active crosslinking agent C added is preferably 25-40 parts.

[0053] The present invention provides a method for preparing the above-mentioned maleimide-based self-initiated two-photon photoresist, which specifically involves: mixing maleimide compound, polycyclopentenyl acrylate and high refractive index fluorene-based active crosslinking agent in a yellow light chamber in a certain proportion to obtain a viscous maleimide-based self-initiated two-photon photoresist.

[0054] The present invention provides a patterning method for the above-mentioned maleimide-based self-initiated two-photon photoresist, comprising the following steps:

[0055] 1) Take 1-2 drops of two-photon photoresist and drop it onto the substrate;

[0056] 2) Expose the two-photon photoresist using a femtosecond laser direct writing device;

[0057] 3) Immerse the exposed photoresist in the developing solution for development to obtain the photolithographic pattern.

[0058] Preferably, in the above patterning method, the spin-coating substrate mentioned in step 1) includes, but is not limited to, semiconductor silicon wafers, quartz wafers, glass sheets, cover glass sheets, and glass slides.

[0059] Preferably, in the above patterning method, the femtosecond laser wavelength in step 2) is 700-900nm, more preferably 780-800nm; the femtosecond laser pulse is 60-150fs, more preferably 80-120fs; and the femtosecond laser repetition rate is 10-200MHz, more preferably 60-100MHz.

[0060] Preferably, in the above patterning method, the developing solution in step 3) is selected from one or more of n-butyl acetate, 1-ethoxy-2-propanol, isopropanol, propylene glycol methyl ether acetate, and ethyl 3-ethoxypropionate. The developing time is 6-30 min. The developing temperature is room temperature. More preferably, a two-stage developing process is used. The primary developing solution is selected from n-butyl acetate, 1-ethoxy-2-propanol, propylene glycol methyl ether acetate, or ethyl 3-ethoxypropionate, and the developing time is 5-15 min; the secondary developing solution is selected from isopropanol, and the developing time is 1-5 min.

[0061] A schematic diagram of the femtosecond laser direct writing device used in this embodiment of the invention is shown below. Figure 7 As shown, unless specific conditions are specified in the examples, they should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained through conventional technical means or commercially available.

[0062] Example 1

[0063] A method for preparing and patterning a self-initiated two-photon photoresist based on maleimide includes the following steps:

[0064] 1) In a yellow light chamber, 10g of N-hydroxypentylmaleimide (formula (I), R1 is -C) was placed in the light chamber. m H 2m OH, m=5), 1g dicyclopentenyl acrylate (formula (III), R3 is -H) and 2g ethoxyfluorene diacrylate (formula (VI), R6 is -H, R4 is -H, R5 is -H) are placed on a roller mixer and mixed evenly to obtain a maleimide-based self-initiated two-photon photoresist.

[0065] 2) Drop 2 drops of the above two-photon photoresist onto the glass slide.

[0066] 3) Exposure of two-photon photoresist was performed using a 780nm femtosecond laser with a power of 20mw, a pulse of 120fs, a repetition rate of 100MHz, and a writing speed of 100mm / s.

[0067] 4) After exposure, the photoresist is immersed in propylene glycol methyl ether acetate for 6 minutes for development, then transferred to isopropanol for 1 minute and allowed to stand and dry.

[0068] Example 2

[0069] The preparation and patterning of a maleimide self-initiated two-photon photoresist includes the following steps:

[0070] 1) In a yellow light chamber, 10g of N-hydroxydecyl maleimide (formula (I), R1 is -C) was placed in the light chamber. m H 2m OH, m=10), 3g tricyclopentenyl acrylate (formula (IV), R3 is -H) and 5g hydroxyethoxyfluorene dimethacrylate (formula (VI), R6 is -CH3, R4 is -OH, R5 is -H) were placed on a roller mixer and mixed evenly to obtain a self-initiated two-photon photoresist based on maleimide.

[0071] 2) Drop 2 drops of the above two-photon photoresist onto the quartz plate.

[0072] 3) Exposure of two-photon photoresist was performed using a 780nm femtosecond laser with a power of 10mw, a pulse of 100fs, a repetition rate of 60MHz, and a writing speed of 10mm / s.

[0073] 4) After exposure, the photoresist is immersed in n-butyl acetate for 5 minutes for development, then transferred to isopropanol for 1 minute and allowed to stand and dry.

[0074] Example 3

[0075] A method for preparing and patterning a self-initiated two-photon photoresist based on maleimide includes the following steps:

[0076] 1) In a yellow light chamber, 10g of N-hydroxyheptylmaleimide (formula (I), R1 is -C) was placed in the light chamber. m H 2m OH, m=7), 2g tetracyclopentenyl methacrylate (formula (V), R3 is -CH3) and 4g propoxyfluorene dimethacrylate (formula (VII), R7 is -CH3, R8 is -H, R9 is -H) were placed on a roller mixer and mixed evenly to obtain a maleimide-based self-initiated two-photon photoresist.

[0077] 2) Drop 2 drops of the above two-photon photoresist onto the cover glass.

[0078] 3) Exposure of two-photon photoresist was performed using a 780nm femtosecond laser with a power of 5mw, a pulse of 60fs, a repetition rate of 80MHz, and a writing speed of 0.1mm / s.

[0079] 4) After exposure, the photoresist is immersed in 1-ethoxy-2-propanol for 12 minutes for development, then transferred to isopropanol for 2 minutes and allowed to stand and dry.

[0080] Example 4

[0081] A method for preparing and patterning a self-initiated two-photon photoresist based on maleimide includes the following steps:

[0082] 1) In a yellow light chamber, 10g of N-methylmaleimide (formula (I), R1 is -C) is placed in the light chamber. n H 2n+1 2.5 g of tetracyclopentenyl methacrylate (formula (V), R3 is -CH3) and 3.5 g of hydroxypropoxyfluorene dimethacrylate (formula (VII), R7 is -CH3, R8 is -OH, R5 is -H) were placed on a roller mixer and mixed evenly to obtain a maleimide-based self-initiated two-photon photoresist.

[0083] 2) Drop 2 drops of the above two-photon photoresist onto the glass slide.

[0084] 3) Exposure of two-photon photoresist was performed using a 780nm femtosecond laser with a power of 15mw, a pulse of 120fs, a repetition rate of 80MHz, and a writing speed of 50mm / s.

[0085] 4) After exposure, immerse the photoresist in ethyl 3-ethoxypropionate for 15 minutes to develop, then transfer it to isopropanol and immerse for 5 minutes. Allow it to dry, and write the pattern as shown in the appendix. Figure 1 .

[0086] Example 5

[0087] A method for preparing and patterning a self-initiated two-photon photoresist based on maleimide includes the following steps:

[0088] 1) In a yellow light chamber, 10g of N-tetraalkylmaleimide (formula (I), R1 is -C) was placed in the light chamber. n H 2n+1 2.5 g of tetracyclopentenyl methacrylate (formula (V), R3 is -CH3) and 4 g of hydroxypropoxydiphenylfluorene dimethacrylate (formula (VII), R7 is -CH3, R8 is -OH, R9 is -C6H5) were mixed evenly on a roller mixer to obtain a maleimide-based self-initiated two-photon photoresist.

[0089] 2) Drop 2 drops of the above two-photon photoresist onto the semiconductor silicon wafer.

[0090] 3) Exposure of two-photon photoresist was performed using a 780nm femtosecond laser with a power of 10mw, a pulse of 120fs, a repetition rate of 80MHz, and a writing speed of 30mm / s.

[0091] 4) After exposure, the photoresist is immersed in propylene glycol methyl ether acetate for 10 minutes for development, then transferred to isopropanol for 2 minutes and allowed to stand and dry.

[0092] Example 6

[0093] A method for preparing and patterning a self-initiated two-photon photoresist based on maleimide includes the following steps:

[0094] 1) In a yellow light chamber, 10g of N-pentadecanylmaleimide (formula (I), R1 is -C) was placed in the light chamber. n H 2n+1 2.5 g of tetracyclopentenyl methacrylate (formula (V), R3 is -CH3) and 3.5 g of hydroxypropoxydiphenylfluorene dimethacrylate (formula (VII), R7 is -CH3, R8 is -OH, R9 is -C6H5) were mixed evenly on a roller mixer to obtain a maleimide-based self-initiated two-photon photoresist.

[0095] 2) Drop 1 drop of the above two-photon photoresist onto the semiconductor silicon wafer.

[0096] 3) Exposure of two-photon photoresist was performed using a 780nm femtosecond laser with a power of 20mw, a pulse of 120fs, a repetition rate of 80MHz, and a writing speed of 80mm / s.

[0097] 4) After exposure, immerse the photoresist in n-butyl acetate for 10 minutes to develop, then transfer it to isopropanol and immerse for 2 minutes. Allow it to stand and dry, and then write the pattern as shown in the appendix. Figure 2 .

[0098] Example 7

[0099] A method for preparing and patterning a self-initiated two-photon photoresist based on maleimide includes the following steps:

[0100] 1) In a yellow light chamber, 10g of N-acetoxyethyl maleimide (formula (I), R1 is -C) was placed in the light chamber. p H 2p OCOCH3 (p=2), 2.5 g of tricyclopentenyl acrylate (formula (IV), R3 is -H) and 3.5 g of propoxyfluorene dimethacrylate (formula (VII), R7 is -CH3, R8 is -H, R9 is -H) were mixed evenly on a roller mixer to obtain a maleimide-based self-initiated two-photon photoresist.

[0101] 2) Drop 1 drop of the above two-photon photoresist onto the semiconductor silicon wafer.

[0102] 3) Exposure of two-photon photoresist was performed using a 780nm femtosecond laser with a power of 15mw, a pulse of 120fs, a repetition rate of 80MHz, and a writing speed of 60mm / s.

[0103] 4) After exposure, the photoresist is immersed in n-butyl acetate for 12 minutes for development, then transferred to isopropanol for 2 minutes and allowed to stand and dry.

[0104] Example 8

[0105] A method for preparing and patterning a self-initiated two-photon photoresist based on maleimide includes the following steps:

[0106] 1) In a yellow light chamber, 10g of N-acetoxyhexylmaleimide (formula (I), R1 is -C) was placed in the light chamber. p H 2p OCOCH3 (p=6), 2.5 g tetracyclopentenyl methacrylate (formula (V), R3 is -CH3) and 3.5 g hydroxypropoxydiphenylfluorene dimethacrylate (formula (VII), R7 is -CH3, R8 is -OH, R9 is -C6H5) were mixed evenly on a roller mixer to obtain a maleimide-based self-initiated two-photon photoresist.

[0107] 2) Drop 1 drop of the above two-photon photoresist onto the semiconductor silicon wafer.

[0108] 3) Exposure of two-photon photoresist was performed using a 780nm femtosecond laser with a power of 18mw, a pulse of 120fs, a repetition rate of 80MHz, and a writing speed of 80mm / s.

[0109] 4) After exposure, the photoresist is immersed in n-butyl acetate for 10 minutes for development, then transferred to isopropanol for 2 minutes and allowed to stand and dry.

[0110] Example 9

[0111] A method for preparing and patterning a self-initiated two-photon photoresist based on maleimide includes the following steps:

[0112] 1) In a yellow light chamber, 10g of N-acetoxydecyl maleimide (formula (I), R1 is -C) was placed in the light chamber. p H 2p OCOCH3 (p=10), 2g of tetracyclopentenyl methacrylate (formula (V), R3 is -CH3) and 4g of hydroxypropoxydiphenylfluorene dimethacrylate (formula (VII), R7 is -CH3, R8 is -OH, R9 is -C6H5) were mixed evenly on a roller mixer to obtain a maleimide-based self-initiated two-photon photoresist.

[0113] 2) Drop 1 drop of the above two-photon photoresist onto the semiconductor silicon wafer.

[0114] 3) Exposure of two-photon photoresist was performed using a 780nm femtosecond laser with a power of 20mw, a pulse of 120fs, a repetition rate of 80MHz, and a writing speed of 90mm / s.

[0115] 4) After exposure, the photoresist is immersed in n-butyl acetate for 10 minutes for development, then transferred to isopropanol for 2 minutes and allowed to stand and dry.

[0116] Example 10

[0117] A method for preparing and patterning a self-initiated two-photon photoresist based on maleimide includes the following steps:

[0118] 1) In a photoluminescence chamber, 10g of N-cyclopentylmaleimide, 2g of tetracyclopentenyl methacrylate (formula (V), R3 is -CH3) and 4g of hydroxypropoxydiphenylfluorene dimethacrylate (formula (VII), R7 is -CH3, R8 is -OH, R9 is -C6H5) are placed on a roller mixer and mixed evenly to obtain a self-initiated two-photon photoresist based on maleimide.

[0119] 2) Drop 1 drop of the above two-photon photoresist onto the semiconductor silicon wafer.

[0120] 3) Exposure of two-photon photoresist was performed using a 780nm femtosecond laser with a power of 20mw, a pulse of 120fs, a repetition rate of 80MHz, and a writing speed of 95mm / s.

[0121] 4) After exposure, the photoresist is immersed in n-butyl acetate for 10 minutes for development, then transferred to isopropanol for 2 minutes and allowed to stand and dry.

[0122] Example 11

[0123] A method for preparing and patterning a self-initiated two-photon photoresist based on maleimide includes the following steps:

[0124] 1) In a photoluminescence chamber, 10g of N,N'-oxopropyl dimaleimide (formula (II), x=1), 2.5g of tetracyclopentenyl methacrylate (formula (V), R3 is -CH3) and 3.5g of hydroxypropoxydiphenylfluorene dimethacrylate (formula (VII), R7 is -CH3, R8 is -OH, R9 is -C6H5) are placed on a roller mixer and mixed evenly to obtain a self-initiated two-photon photoresist based on maleimide.

[0125] 2) Drop 1 drop of the above two-photon photoresist onto the semiconductor silicon wafer.

[0126] 3) Exposure of two-photon photoresist was performed using a 780nm femtosecond laser with a power of 20mw, a pulse of 120fs, a repetition rate of 80MHz, and a writing speed of 70mm / s.

[0127] 4) After exposure, the photoresist is immersed in n-butyl acetate for 10 minutes for development, then transferred to isopropanol for 2 minutes and allowed to stand and dry.

[0128] Example 12

[0129] A method for preparing and patterning a self-initiated two-photon photoresist based on maleimide includes the following steps:

[0130] 1) In a photoluminescence chamber, 10g of N,N'-undecyl dimaleimide (formula (II), x=5), 2.5g of tetracyclopentenyl methacrylate (formula (V), R3 is -CH3) and 3.5g of hydroxypropoxydiphenylfluorene dimethacrylate (formula (VII), R7 is -CH3, R8 is -OH, R9 is -C6H5) are placed on a roller mixer and mixed evenly to obtain a self-initiated two-photon photoresist based on maleimide.

[0131] 2) Drop 1 drop of the above two-photon photoresist onto the semiconductor silicon wafer.

[0132] 3) Exposure of two-photon photoresist was performed using a 780nm femtosecond laser with a power of 20mw, a pulse of 120fs, a repetition rate of 80MHz, and a writing speed of 85mm / s.

[0133] 4) After exposure, the photoresist is immersed in n-butyl acetate for 10 minutes for development, then transferred to isopropanol for 2 minutes and allowed to stand and dry.

[0134] Example 13

[0135] A method for preparing and patterning a self-initiated two-photon photoresist based on maleimide includes the following steps:

[0136] 1) In a photoluminescence chamber, 10g of N,N'-pentyl dimaleimide (formula (II), x=2), 2.5g of tetracyclopentenyl methacrylate (formula (V), R3 is -CH3) and 3.5g of hydroxypropoxydiphenylfluorene dimethacrylate (formula (VII), R7 is -CH3, R8 is -OH, R9 is -C6H5) are placed on a roller mixer and mixed evenly to obtain a self-initiated two-photon photoresist based on maleimide.

[0137] 2) Drop 1 drop of the above two-photon photoresist onto the semiconductor silicon wafer.

[0138] 3) Exposure of two-photon photoresist was performed using a 780nm femtosecond laser with a power of 20mw, a pulse of 120fs, a repetition rate of 80MHz, and a writing speed of 100mm / s.

[0139] 4) After exposure, the photoresist is immersed in n-butyl acetate for 10 minutes for development, then transferred to isopropanol for 2 minutes and allowed to stand and dry.

[0140] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All technical solutions formed by equivalent substitution or equivalent transformation fall within the protection scope claimed by the present invention.

Claims

1. A self-initiated two-photon photoresist based on maleimide, characterized in that: The maleimide-based self-initiated two-photon photoresist contains, by weight, 100 parts of maleimide compound, 10-30 parts of polycyclopentenyl acrylate and 20-50 parts of high refractive index fluorene active crosslinking agent, and does not contain conventional two-photon initiators. The structural formula of the maleimide compound is shown in formula (I) or (II): In equation (I), R1 is -C m H 2m OH, -C n H 2n+1 -C p H 2p OCOCH3, Where m is a natural number from 5 to 10, n is a natural number from 1 to 40, and p is a natural number from 2 to 10; In equation (II), x is a natural number from 1 to 5, and -R2- is either -CH2- or -O-. The polycyclopentenyl acrylate is selected from at least one of the compounds with structural formulas as shown in formulas (III), (IV), and (V). In equations (III), (IV), and (V), R3 is independently either -H or -CH3; The high-refractive-index fluorene-based active crosslinking agent is selected from at least one of the compounds with structures shown in formula (VI) and formula (VII). In equations (VI) and (VII), R6 and R7 are each independently -H or -CH3, R4 and R8 are each independently -H or -OH, and R5 and R9 are each independently -H or -C6H5.

2. The maleimide-based self-initiated two-photon photoresist as described in claim 1, characterized in that: The maleimide-based self-initiated two-photon photoresist is made of 100 parts of maleimide compound, 10-30 parts of polycyclopentenyl acrylate and 20-50 parts of high refractive index fluorene active crosslinking agent.

3. The maleimide-based self-initiated two-photon photoresist as described in claim 1 or 2, characterized in that: The polycyclopentenyl acrylate is present in quantities of 20-30 parts.

4. The maleimide-based self-initiated two-photon photoresist as described in claim 1 or 2, characterized in that: The high-refractive-index fluorene-based active crosslinking agent is present in quantities of 25-40 parts.

5. A method for preparing a maleimide-based self-initiated two-photon photoresist as described in claim 1 or 2, characterized in that: The preparation method is as follows: maleimide compound, polycyclopentenyl acrylate and high refractive index fluorene active crosslinking agent are stirred and mixed evenly in proportion in a yellow light chamber to obtain a viscous maleimide-based self-initiated two-photon photoresist.

6. A patterning method for maleimide-based self-initiated two-photon photoresist as described in claim 1 or 2, characterized in that: The patterning method includes the following steps: 1) Take maleimide-based self-initiated two-photon photoresist and drop it onto the substrate; 2) Expose the two-photon photoresist using a femtosecond laser direct writing device; 3) Immerse the exposed photoresist in the developing solution for development to obtain the photolithographic pattern.

7. The patterning method as described in claim 6, characterized in that: In step 2), the femtosecond laser wavelength is 700-900nm, the laser pulse is 60-150fs, the laser repetition rate is 10-200MHz, the writing power is 5-20mW, and the writing speed is 0.1-100mm / s.

8. The patterning method as described in claim 7, characterized in that: In step 2), the femtosecond laser wavelength is 780-800nm; the femtosecond laser pulse is 80-120fs; and the femtosecond laser repetition rate is 60-100MHz.

9. The patterning method as described in claim 6, characterized in that: In step 3), the developing solution is selected from one or more of n-butyl acetate, 1-ethoxy-2-propanol, isopropanol, propylene glycol methyl ether acetate, and ethyl 3-ethoxypropionate; the developing time is 6-30 min, and the developing temperature is room temperature.

10. The patterning method as described in claim 9, characterized in that: Step 3) uses two-stage development. The primary developer is selected from n-butyl acetate, 1-ethoxy-2-propanol, propylene glycol methyl ether acetate or ethyl 3-ethoxypropionate, and the development time is 5-15 min. The secondary developer is selected from isopropanol, and the development time is 1-5 min.

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