Femtosecond laser direct-write photoresist, negative femtosecond laser direct-write photoresist and its patterning method
The femtosecond laser direct-write photoresist film-forming resin synthesized by quaternary copolymerization solves the problem of poor etching resistance of traditional poly(meth)acrylate polymers, improves the etching resistance and resolution of photoresist, and enhances the integrity and morphology of photolithographic patterns.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ZHEJIANG LAB
- Filing Date
- 2023-06-15
- Publication Date
- 2026-05-26
AI Technical Summary
Traditional poly(meth)acrylate polymers, as film-forming resins, have poor etching resistance in photolithography processes and poor adhesion to wafers, leading to photolithographic pattern deformation, detachment, and reduced resolution.
A quaternary copolymer femtosecond laser direct-write photoresist film-forming resin was synthesized through free radical polymerization, introducing groups such as ester rings, hydroxyl groups, and benzene rings to prepare a negative femtosecond laser direct-write photoresist, thereby improving etching resistance and resolution.
High-resolution photolithographic patterning was achieved, improving the adhesion between the photoresist and the wafer and enhancing the morphological quality of the photolithographic pattern.
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Figure CN116554391B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of photoresist, specifically relating to a femtosecond laser direct writing photoresist film-forming resin, a negative femtosecond laser direct writing photoresist containing the film-forming resin, and a patterning method for the photoresist. Background Technology
[0002] The rapid development of smart devices has placed higher demands on chips, and photolithography is a crucial step in chip manufacturing. Photolithography refers to the technology of transferring patterns from a mask to a substrate by exposing the mask to light under a light source of a certain wavelength and then performing steps such as development and etching. Photolithography can be used to create micro- and nano-scale patterns. Photolithography technology consists of three parts: a light source, photoresist, and the photolithography process. Among these, photoresist is an important material in the photolithography process.
[0003] Photoresist, also known as photoresist, refers to a type of composition that undergoes cross-linking or photolysis reactions in the exposed area after exposure to light sources of different wavelengths, resulting in significant changes in its physical properties in the developer. Negative photoresist forms insoluble substances after exposure, while positive photoresist becomes soluble. Photoresist mainly consists of film-forming resin, photoacid generator, solvent, and some additives. Traditional film-forming resins mainly include poly(meth)acrylate systems, cyclic polymer systems, and cyclic olefin-maleic anhydride copolymer systems.
[0004] Poly(meth)acrylate polymers are abundant, easy to synthesize, and have high light transmittance, making them the preferred material for film-forming resins. However, the linear molecular chains and high oxygen content of poly(meth)acrylate polymers result in poor etching resistance, failing to protect the substrate surface during subsequent etching processes. Furthermore, poly(meth)acrylate polymers exhibit poor adhesion to wafers, making them susceptible to erosion from subsequent etching, ion implantation, and other processes. Ultimately, this leads to lithographic pattern deformation, detachment, and reduced resolution.
[0005] Therefore, we provide a polymer film-forming resin containing both methacrylate and cyclic structures to improve the polymer's etching resistance and resolution, thereby solving the above-mentioned technical problems. Summary of the Invention
[0006] The technical problem to be solved by the present invention is to provide a quaternary copolymer femtosecond laser direct writing photoresist film-forming resin, a negative femtosecond laser direct writing photoresist containing the film-forming resin, and a patterning method for the photoresist. The film-forming resin has the advantages of low raw material cost, simple synthesis, and high yield. The obtained negative photoresist has the advantages of high resolution and strong etching resistance, which is beneficial to meeting the requirements of high-precision patterning manufacturing.
[0007] In a first aspect, the present invention provides a femtosecond laser direct-write photoresist film-forming resin, the chemical structural formula of which is shown in formula (I):
[0008]
[0009] The femtosecond laser direct-write photoresist is a random copolymer with a weight-average molecular weight Mw between 1.7 and 2.2 kDa and a distribution index D (D = Mw / Mn, where Mw is the weight-average molecular weight and Mn is the number-average molecular weight) between 1.4 and 2. The x, y, m, and n represent the number of corresponding repeating units and satisfy the following condition: x:y:m:n = 1:0.5~3:0.5~1:0.5~1.5.
[0010] Preferably, the preparation method of the femtosecond laser direct-write photoresist film-forming resin is as follows:
[0011] Using styrene, methyl methacrylate, hydroxypropyl methacrylate, and isobornyl methacrylate as raw materials, wherein the molar ratio of methyl methacrylate to styrene, hydroxypropyl methacrylate, and isobornyl methacrylate is 1:0.5–3:0.5–1:0.5–1.5, and with the addition of an initiator, the femtosecond laser direct-write photoresist film-forming resin is synthesized via free radical polymerization. The chemical reaction formula is shown below:
[0012]
[0013] As a further preferred embodiment, the preparation method of the femtosecond laser direct-write photoresist film-forming resin is carried out according to the following steps:
[0014] In a container, styrene, methyl methacrylate, hydroxypropyl methacrylate, isobornyl methacrylate, and an appropriate amount of solvent are added sequentially. After all the solids have dissolved, an initiator is added, and the mixture is stirred and heated under N2 environment to remove oxygen. The reaction is carried out at 60-80℃ for 4-48 hours. After the reaction is completed, the mixture is cooled to room temperature, and the reaction solution is added dropwise to a precipitant. The mixture is then filtered to obtain a powdered solid, which is the femtosecond laser direct-write photoresist film-forming resin.
[0015] As a further preferred option, the initiator is one or more of azobisisobutyronitrile, azobisisobutyronitrile, benzoyl tert-butyl peroxide, and potassium persulfate.
[0016] As a further preferred option, the solvent used is one or more of deionized water, acetonitrile, xylene, and toluene.
[0017] As a further preferred embodiment, the ratio of methyl methacrylate to solvent is 30-50 mmol / 80 mL, and even more preferably 40 mmol / 80 mL, and the ratio of initiator to solvent is 0.4-0.5 g / 80 mL.
[0018] As a further preferred option, the precipitant used is one or more of ethanol, isopropanol, petroleum ether, diethyl ether, and 1,4-dioxane.
[0019] In a second aspect, the present invention provides a negative femtosecond laser direct writing photoresist, comprising, by weight percentage, 3-5 wt% film-forming resin, 5-10 wt% active monomer, 0.1-1 wt% two-photon initiator and 85-91 wt% solvent; wherein the film-forming resin is the aforementioned femtosecond laser direct writing photoresist film-forming resin.
[0020] The negative femtosecond laser direct-write photoresist of the present invention is prepared by the following steps: according to the ratio, the film-forming resin, active monomer, two-photon initiator and solvent are mixed evenly in a yellow light chamber, and then filtered and purified sequentially using organic filter membranes with pore sizes of 0.45 micrometers, 0.22 micrometers and 0.1 micrometers to obtain the negative femtosecond laser direct-write photoresist.
[0021] Preferably, the active monomer is one or more of pentaerythritol tetraacrylate, pentaerythritol tetraacrylate, 5,5,5-trifluoro-4-hydroxy-2-methyl-4-(trifluoromethyl)methacrylate, and dipentaerythritol pentaacrylate.
[0022] Preferably, the two-photon initiator is 7-diethylamino-4-methylcoumarin.
[0023] Preferably, the solvent is one or more of methanol, ethanol, acetone, and propylene glycol monomethyl ether acetate.
[0024] Thirdly, the present invention provides a patterning method for negative femtosecond laser direct-write photoresist, comprising the following steps:
[0025] 1) Apply negative femtosecond laser direct-write photoresist onto the substrate;
[0026] 2) Expose negative femtosecond laser direct writing photoresist using a femtosecond laser direct writing device;
[0027] 3) Immerse the exposed photoresist in the developing solution for development to obtain the photolithographic pattern.
[0028] Preferably, 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 5-10mW, and the writing speed is 0.1-10mm / s.
[0029] Preferably, in step 3), the developing solution is selected from one or more of n-butyl acetate, 1-ethoxy-2-propanol, isopropanol, and propylene glycol monomethyl ether acetate; the developing time is 25-60 s, and the developing temperature is room temperature. Further, a two-stage developing process is used: the primary developing solution is selected from n-butyl acetate, 1-ethoxy-2-propanol, or propylene glycol monomethyl ether acetate, and the developing time is 25-60 s; the secondary developing solution is selected from isopropanol, and the developing time is 40-60 s.
[0030] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention provides a femtosecond laser direct writing photoresist film-forming resin, which is synthesized by free radical polymerization and has the advantages of inexpensive raw materials, simple synthesis, and high yield; The present invention introduces groups such as ester rings, hydroxyl groups, and benzene rings into the film-forming resin, which can improve the etching resistance of the negative photolithography composition, enhance the adhesion between the film and the wafer, thereby improving the resolution of the photolithography pattern and improving the pattern morphology.
[0031] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description
[0032] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:
[0033] Figure 1 This is the 1H NMR spectrum of the quaternary film-forming resin obtained in Example 1 of the present invention in DMSO solvent;
[0034] Figure 2 This is the gel permeation chromatography curve of the quaternary film-forming resin obtained in Example 1 of the present invention;
[0035] Figure 3 This is a SEM image of the line array obtained by femtosecond laser direct writing photoresist processing in Embodiment 7 of the present invention;
[0036] Figure 4 This is a SEM image of the lines obtained by femtosecond laser direct writing photoresist in Embodiment 8 of the present invention;
[0037] Figure 5 This is a SEM image of the lines obtained by femtosecond laser direct writing photoresist processing in Embodiment 9 of the present invention;
[0038] Figure 6 This is a deep silicon etching effect diagram of the pattern obtained by femtosecond laser direct writing photoresist processing in Embodiment 7 of the present invention;
[0039] Figure 7 This is a SEM image of the pattern obtained by femtosecond laser direct writing photoresist processing in Comparative Example 3 of this invention;
[0040] Figure 8 This is a deep silicon etching effect diagram of the pattern obtained by femtosecond laser direct writing photoresist processing in Comparative Example 3 of this invention.
[0041] Figure 9 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
[0042] The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.
[0043] A schematic diagram of the femtosecond laser direct writing device used in this embodiment of the invention is shown below. Figure 9 As shown in the accompanying drawings, an embodiment of the present invention, including a quaternary polymer film-forming resin, a negative femtosecond laser direct-write photoresist, and a patterning method thereof, is described below with reference to the accompanying drawings.
[0044] Unless otherwise specified in the examples, the procedures 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.
[0045] Example 1
[0046] A quaternary polymer film-forming resin was prepared by free radical polymerization:
[0047] In a 250 mL three-necked flask, methyl methacrylate (4 g, 40 mmol), styrene (2.08 g, 20 mmol), hydroxypropyl methacrylate (2.88 g, 20 mmol), and isobornyl methacrylate (4.45 g, 20 mmol) were added sequentially, along with 0.5 g of azobisisobutyronitrile (AIBN) as the initiator and 80 mL of acetonitrile. After purging with N2 for 30 min, the mixture was heated to 60 °C and reacted for 4 h. After the reaction was complete, the mixture was cooled to room temperature. The solution was added dropwise to diethyl ether to precipitate the solid, which was then filtered to obtain a white powdery solid. Its 1H NMR spectrum in DMSO solvent is shown in [Figure number missing]. Figure 1 The gel permeation chromatography curve is shown in the figure. Figure 2 M was measured W =1.88kDa, D=1.44.
[0048] Example 2
[0049] In a 250 mL three-necked flask, methyl methacrylate (4 g, 40 mmol), styrene (12.49 g, 120 mmol), hydroxypropyl methacrylate (5.76 g, 40 mmol), and isobornyl methacrylate (13.34 g, 60 mmol) were added sequentially, along with benzoyl peroxide (0.4 g) as the initiator and 80 mL of toluene. After purging with N2 for 30 min, the mixture was heated to 80 °C and reacted for 24 h. After the reaction was complete, the mixture was cooled to room temperature. The solution was added dropwise to 1,4-dioxane to precipitate, and the precipitate was obtained by filtration, yielding a white powdery solid. The molecular weight (M) was determined by gel permeation chromatography. W =1.99kDa, D=1.93.
[0050] Example 3
[0051] In a 250 mL three-necked flask, methyl methacrylate (4 g, 40 mmol), styrene (6.25 g, 60 mmol), hydroxypropyl methacrylate (4.04 g, 28 mmol), and isobornyl methacrylate (8.89 g, 40 mmol) were added sequentially, along with 0.4 g of ammonium persulfate as initiator and 80 mL of deionized water. After purging with N2 for 30 min, the mixture was heated to 70 °C and reacted for 48 h. After the reaction was complete, the mixture was cooled to room temperature. The solution was added dropwise to ethanol to precipitate the solid, which was then filtered to obtain a white powdery solid. The molecular weight (M) was determined by gel permeation chromatography. W =2.15kDa, D=1.77.
[0052] Example 4
[0053] In a yellow light chamber, the quaternary polymer film-forming resin (80 mg), dipentaerythritol pentaacrylate (80 mg), 7-diethylamino-4-methylcoumarin (16 mg), and acetone (1.42 g) synthesized in Example 1 were mixed evenly and then filtered and purified sequentially using organic filter membranes with pore sizes of 0.45 μm, 0.22 μm, and 0.1 μm to obtain a negative femtosecond laser direct-write photoresist.
[0054] Example 5
[0055] In a photoluminescence chamber, the quaternary polymer film-forming resin (78.4 mg), pentaerythritol tetraacrylate (32 mg), 7-diethylamino-4-methylcoumarin (1.6 mg), and propylene glycol monomethyl ether acetate (1.36 g) synthesized in Example 2 were mixed evenly and then filtered and purified sequentially using organic filter membranes with pore sizes of 0.45 μm, 0.22 μm, and 0.1 μm to obtain a negative femtosecond laser direct-write photoresist.
[0056] Example 6
[0057] In a photoluminescence chamber, the quaternary polymer film-forming resin (48 mg), 5,5,5-trifluoro-4-hydroxy-2-methyl-4-(trifluoromethyl)methyl methacrylate (80 mg), 7-diethylamino-4-methylcoumarin (16 mg), and ethanol (1.46 g) synthesized in Example 3 were mixed evenly and then filtered and purified sequentially using organic filter membranes with pore sizes of 0.45 μm, 0.22 μm, and 0.1 μm to obtain a negative femtosecond laser direct-write photoresist.
[0058] Example 7
[0059] In the photoluminescence chamber, 5 drops of the negative femtosecond laser direct-write photoresist prepared in Example 4 were added to a glass substrate. The substrate was fixed to the sample stage with tape. Line arrays and circles were laser-written using a 780nm femtosecond laser. The laser pulse was 60 fs, the laser repetition rate was 10MHz, the writing power was 5Mw, and the writing speed was 0.1mm / s. After exposure, the photoresist was immersed in propylene glycol monomethyl ether acetate for 25s, then transferred to isopropanol for 40s, and allowed to dry. The resulting line array pattern is shown in the attached figure. Figure 3 As shown; the obtained circular pattern is further subjected to deep silicon etching, and the deep silicon etching effect is shown in the figure. Figure 6 As shown.
[0060] Example 8
[0061] In the photoluminescence chamber, 5 drops of the negative femtosecond laser direct-write photoresist prepared in Example 5 were added to a glass substrate. The substrate was fixed to the sample stage using tape. Laser direct writing was performed using a 900nm femtosecond laser with a laser pulse of 150fs, a laser repetition rate of 200MHz, a writing power of 10Mw, and a writing speed of 10mm / s. The exposed photoresist was then immersed in 1-ethoxy-2-propanol for 30s, transferred to isopropanol for 60s, and allowed to dry. The resulting pattern is shown in the attached figure. Figure 4 As shown.
[0062] Example 9
[0063] In the photoluminescence chamber, 5 drops of the negative femtosecond laser direct-write photoresist prepared in Example 6 were added to a glass substrate. The substrate was fixed to the sample stage using tape. Laser direct writing was performed using a 700nm femtosecond laser with a laser pulse of 120 fs, a laser repetition rate of 100MHz, a writing power of 5Mw, and a writing speed of 1mm / s. The exposed photoresist was then immersed in n-butyl acetate for 60s, transferred to isopropanol for 50s, and allowed to dry. The resulting pattern is shown in the attached figure. Figure 5 As shown.
[0064] Comparative Example 1
[0065] In a 250 mL three-necked flask, methyl methacrylate (4 g, 40 mmol), styrene (2.08 g, 20 mmol), azobisisobutyronitrile (0.5 g), and acetonitrile (80 mL) were added sequentially. After purging with N2 for 30 min, the mixture was heated to 80 °C and reacted for 4 h. After the reaction was complete, the mixture was cooled to room temperature. The solution was added dropwise to diethyl ether to precipitate the solid, which was then filtered to obtain a white powdery solid.
[0066] Comparative Example 2
[0067] In a yellow light chamber, the quaternary polymer film-forming resin (80 mg), dipentaerythritol pentaacrylate (80 mg), 7-diethylamino-4-methylcoumarin (16 mg), and acetone (1.42 g) synthesized in Comparative Example 1 were mixed evenly and then filtered and purified sequentially using organic filter membranes with pore sizes of 0.45 μm, 0.22 μm, and 0.1 μm to obtain negative femtosecond laser direct-write photoresist.
[0068] Comparative Example 3
[0069] In the photoluminescence chamber, 5 drops of the negative femtosecond laser direct-write photoresist composition prepared in Comparative Example 2 were added to a glass substrate. The substrate was fixed to the sample stage using tape. Line arrays and circles were laser-written using a 780nm femtosecond laser. The laser pulse was 60 fs, the laser repetition rate was 10MHz, the writing power was 5Mw, and the writing speed was 0.1mm / s. After exposure, the photoresist was immersed in propylene glycol monomethyl ether acetate for 25s, then transferred to isopropanol for 40s, and allowed to dry. The resulting line array pattern is shown below. Figure 7 As shown, the obtained circular pattern is further subjected to deep silicon etching, and the deep silicon etching effect is shown in the figure. Figure 8 As shown.
[0070] Comparing the photoresist patterns and deep silicon etching effects of Example 1 and Comparative Example 1, it can be seen that the negative femtosecond laser direct writing photoresist composition prepared by the present invention has better adhesion. After laser direct writing, the lines are preserved intact, and the etching resistance is improved. The pattern is not significantly damaged after etching.
[0071] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.
Claims
1. A negative femtosecond laser direct-write photoresist film-forming resin, characterized in that: The chemical structural formula of the negative femtosecond laser direct-write photoresist film-forming resin is shown in formula (I): (I) The femtosecond laser direct-write photoresist film-forming resin is a random copolymer with a weight-average molecular weight Mw between 1.7 and 2.2 kDa and a distribution index D between 1.4 and 2. Here, x, y, m, and n represent the number of corresponding repeating units and satisfy the following condition: x:y:m:n = 1:0.5 ~ 3:0.5 ~ 1:0.5 ~ 1.
5.
2. The negative femtosecond laser direct-write photoresist film-forming resin as described in claim 1, characterized in that: The preparation method of the femtosecond laser direct-write photoresist film-forming resin is as follows: Using styrene, methyl methacrylate, hydroxypropyl methacrylate, and isobornyl methacrylate as raw materials, wherein the molar ratio of methyl methacrylate to styrene, hydroxypropyl methacrylate, and isobornyl methacrylate is 1:0.5 ~ 3:0.5 ~ 1:0.5 ~ 1.5, and an initiator is added, the femtosecond laser direct-write photoresist film-forming resin is synthesized through a free radical polymerization reaction. The chemical reaction formula is shown below: (1)。 3. The negative femtosecond laser direct-write photoresist film-forming resin as described in claim 2, characterized in that: The preparation method of the femtosecond laser direct-write photoresist film-forming resin is carried out according to the following steps: Styrene, methyl methacrylate, hydroxypropyl methacrylate, isobornyl methacrylate, and an appropriate amount of solvent are added sequentially to a container. After all the solids have dissolved, an initiator is added, and the mixture is stirred and heated under N2 environment to remove oxygen. The reaction is carried out at 60-80℃ for 4-48 h. After the reaction is completed, the mixture is cooled to room temperature, and the reaction solution is added dropwise to a precipitant. The mixture is then filtered to obtain a powdered solid, which is the negative femtosecond laser direct writing photoresist film-forming resin.
4. The negative femtosecond laser direct-write photoresist film-forming resin as described in claim 3, characterized in that: The initiator is one or more of azobisisobutyronitrile, azobisisobutyronitrile, benzoyl tert-butyl peroxide, and potassium persulfate; the solvent used is one or more of deionized water, acetonitrile, xylene, and toluene; the ratio of methyl methacrylate to solvent is 30-50 mmol / 80 mL, and the ratio of initiator to solvent is 0.4-0.5 g / 80 mL; the precipitant used is one or more of ethanol, isopropanol, petroleum ether, diethyl ether, and 1,4-dioxane.
5. A negative femtosecond laser direct-write photoresist, characterized in that: The negative femtosecond laser direct-write photoresist comprises, by weight percentage, 3-5 wt% film-forming resin, 5-10 wt% active monomer, 0.1-1 wt% two-photon initiator and 85-91 wt% solvent; wherein the film-forming resin is the femtosecond laser direct-write photoresist film-forming resin according to any one of claims 1-4.
6. The negative femtosecond laser direct-write photoresist as described in claim 5, characterized in that: The active monomer is one or more of pentaerythritol tetraacrylate, 5,5,5-trifluoro-4-hydroxy-2-methyl-4-(trifluoromethyl)methacrylate, and dipentaerythritol pentaacrylate.
7. The negative femtosecond laser direct-write photoresist as described in claim 5, characterized in that: The two-photon initiator is 7-diethylamino-4-methylcoumarin.
8. The negative femtosecond laser direct-write photoresist as described in claim 5, characterized in that: The solvent is one or more of methanol, ethanol, acetone, and propylene glycol monomethyl ether acetate.
9. A patterning method for negative femtosecond laser direct-write photoresist as described in claim 5, comprising the following steps: 1) Apply negative femtosecond laser direct-write photoresist onto the substrate; 2) Expose negative femtosecond laser direct writing photoresist using a femtosecond laser direct writing device; 3) Immerse the exposed photoresist in the developing solution for development to obtain the photolithographic pattern.
10. The patterning method as described in claim 9, 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 5-10mW, and the writing speed is 0.1-10mm / s.