Nanoimprint photoresist for dry etching as well as preparation method and application of nanoimprint photoresist

Abstract

The invention relates to the technical field of semiconductors, and particularly discloses a nanoimprint photoresist for dry etching as well as a preparation method and application of the nanoimprint photoresist. 0.5%-20% of an organic metal compound containing unsaturated double bonds; in the photocuring process of the organic metal compound containing the unsaturated double bonds, the unsaturated double bonds can be subjected to a copolymerization cross-linking reaction with the colloid matrix to form a cross-linking cured polymer; metal elements in the cross-linked and cured polymer chemically react with the plasma to generate an inorganic metal compound which is difficult to gasify; according to the invention, an organic metal compound containing unsaturated double bonds is introduced into a traditional colloid matrix, so that the organic metal compound is subjected to copolymerization crosslinking with a resin system in a photocuring process to form a stable metal-containing three-dimensional network structure, and in a subsequent dry etching process, the metal-containing three-dimensional network structure is formed; metal elements in the network can be subjected to an in-situ chemical reaction with plasma active species to generate an inorganic metal compound which is difficult to volatilize and compact.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of semiconductors, and particularly relates to a nanoimprint photoresist for dry etching and a preparation method and application thereof. BACKGROUND

[0002] Nanoimprint lithography (NIL) is a high-resolution patterning technology that can realize nanometer or sub-nanometer scale pattern replication without complex and expensive optical exposure systems. This technology has broad application prospects in the fields of semiconductor devices, photonic crystals, and biosensing micro-nano manufacturing due to its simple principle, low cost, and easy mass production. Currently, commercial nanoimprint photoresist systems mainly use organic polymers such as acrylates as the main component, and form cross-linked structures through ultraviolet curing to meet the basic requirements of pattern transfer.

[0003] However, such photoresists based on pure organic components have obvious performance shortfalls in the key dry etching process. Since the cross-linked network is composed of chemical bonds (such as C-C and C-H bonds) of elements such as carbon, hydrogen, and oxygen, the bond energy is relatively low, and it is easily eroded by physical sputtering and active radicals in the plasma etching environment, resulting in excessively high etching rate and low etching selectivity (i.e., the ratio of the etching rate of the substrate material to the photoresist). This defect directly causes excessive loss of the photoresist layer, degradation of the sidewall profile, and distortion of the critical dimension during pattern transfer, which severely restricts the application of nanoimprint technology in advanced semiconductor manufacturing that requires high-fidelity and high-aspect-ratio pattern structures. SUMMARY

[0004] The purpose of the present application is to provide a nanoimprint photoresist for dry etching and a preparation method and application thereof to solve the problems raised in the background.

[0005] To achieve the above purpose, the present application provides the following technical solutions:

[0006] A nanoimprint photoresist composition for dry etching, consisting of the following components by mass percentage:

[0007] Colloid matrix 80%-99.5%;

[0008] Organometallic compound containing unsaturated double bonds 0.5%-20%;

[0009] The organometallic compound containing unsaturated double bonds can undergo copolymerization cross-linking reaction with the colloid matrix during photocuring, forming a cross-linked and cured polymer;

[0010] The metal elements in the cross-linked cured polymer react chemically with the plasma to generate inorganic metal compounds that are difficult to vaporize, and these compounds accumulate on the surface of the photoresist film to form a protective layer.

[0011] Preferably, the organometallic compound containing unsaturated double bonds has at least one double bond, preferably one to four; the metal element is selected from at least one of magnesium, calcium, aluminum, titanium, zirconium, hafnium, vanadium, chromium, molybdenum, tungsten, manganese, iron, cobalt, nickel, copper, zinc, cadmium, indium, tin, or antimony.

[0012] Preferably, the organometallic compound containing unsaturated double bonds is zirconium methacrylate.

[0013] Preferably, the colloidal matrix comprises the following components in parts by weight: 8-30 parts of acrylate resin, 2-10 parts of free radical photoinitiator, 5-15 parts of reactive diluent, and 30-65 parts of organic solvent.

[0014] Preferably, the free radical photoinitiator is selected from at least one of 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone, isopropylthioxanthonone, 2,4-diethylthioxanthonone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 4-(N,N'-dimethyl-amino)benzophenone, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, or benzophenone.

[0015] Preferably, the reactive diluent is selected from at least one of isobornyl acrylate, isobornyl methacrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, isobutyl methacrylate, cyclopentyl methacrylate, cyclopentyl acrylate, cyclohexyl acrylate, tripropylene glycol diacrylate, trimethylolpropane triacrylate, dimethylolpropane tetraacrylate, or 1,6-hexanediol diacrylate.

[0016] Preferably, the organic solvent is selected from at least one of propylene glycol monomethyl ether, propylene glycol monobutyl ether, diethylene glycol dimethyl ether, diethylene glycol monomethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol monomethyl ether, propylene glycol methyl ether acetate, ethyl acetate, butyl lactate, methanol, ethanol, acetone, gamma-butyrolactone, toluene, or xylene.

[0017] A nanoimprint photoresist for dry etching, comprising the composition described in any one of the above, wherein the mass percentage of the organometallic compound containing unsaturated double bonds is 2%-17%, and the mass percentage of the colloidal matrix is ​​83%-98%.

[0018] A nanoimprint photoresist for dry etching, comprising the composition described in any one of the above, wherein the mass percentage of the organometallic compound containing unsaturated double bonds is 5%-10%, and the mass percentage of the colloidal matrix is ​​90%-95%.

[0019] A method for preparing the nanoimprint photoresist according to any one of the above claims includes the following steps:

[0020] Weigh each component according to the specified ratio, mix them evenly, and obtain the photoresist composition.

[0021] A method for preparing a dry etching resistant nanoimprint photoresist film includes:

[0022] The photoresist composition described in any of the above-mentioned methods is sequentially filtered, coated, baked, imprinted, exposed and cured, and then demolded to obtain a dry-etch resistant photoresist pattern with a protective film structure.

[0023] Preferably, the filter membrane used for filtration has a pore size of 0.01-1 μm; the coating membrane thickness is 0.1-10 μm; the baking temperature is 80-120℃ and the baking time is 30-180s; and the exposure dose is 30-300mJ / cm².

[0024] The application of any of the above-mentioned nanoimprint photoresists in semiconductor nanoimprint lithography processes.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] (1) By introducing organometallic compounds containing unsaturated double bonds into the traditional colloidal matrix, they can copolymerize and crosslink with the resin system during photocuring to form a stable metal-containing three-dimensional network structure. In the subsequent dry etching process, the metal elements in the network can react in situ with plasma active species to generate non-volatile and dense inorganic metal compounds, which accumulate on the surface of the photoresist to form an effective physicochemical protective layer. This protective layer can block the physical sputtering and chemical erosion of the plasma, reduce the etching rate of the photoresist, and improve the fidelity of pattern transfer.

[0027] (2) By selecting the type of metal element (such as zirconium, titanium, aluminum, etc.) and adapting to different etching gas chemical environments, high-performance pattern transfer can be achieved without changing the core conditions of existing nanoimprinting processes such as imprinting, exposure, and curing. While effectively improving the etching selectivity and pattern accuracy, it also fully considers the feasibility of mass production, process compatibility and cost controllability. Attached Figure Description

[0028] Figure 1 This is a flowchart of the present invention. Detailed Implementation

[0029] The technical solutions of 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 embodiments of the present invention, and not all embodiments. 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.

[0030] Example 1:

[0031] A nanoimprint photoresist composition for dry etching, comprising the following components by weight percentage:

[0032] Colloidal matrix 92%;

[0033] Organometallic compounds containing unsaturated double bonds account for 8%;

[0034] The organometallic compound containing unsaturated double bonds is titanium acrylate, which contains two carbon-carbon double bonds in its molecule and titanium as the metal element. During the photocuring process, its double bonds undergo a copolymerization and crosslinking reaction with the acrylate resin in the colloidal matrix to form a titanium-containing three-dimensional network structure.

[0035] The colloidal matrix is ​​composed of the following components in parts by weight: 20 parts of acrylate resin (selected as a copolymer of isoborneol acrylate and methyl methacrylate); 6 parts of free radical photoinitiator (selected as 2,4,6-trimethylbenzoyl diphenylphosphine oxide); 10 parts of reactive diluent (selected as 1,6-hexanediol diacrylate); and 50 parts of organic solvent (selected as propylene glycol monomethyl ether).

[0036] The preparation of the photoresist composition includes the following steps: acrylate resin and organic solvent are stirred and dissolved at 35°C for 40 minutes; reactive diluent and free radical photoinitiator are added, and stirring is continued for 50 minutes; titanium acrylate is added, and the mixture is stirred under nitrogen protection until the system is uniform and transparent; the mixture is filtered through a 0.2 μm polytetrafluoroethylene (PTFE) filter membrane to obtain the photoresist solution, which is then stored in a light-proof container for later use.

[0037] The photoresist film preparation and patterning process is as follows: the photoresist solution is filtered using a 0.2 μm pore size filter membrane; the photoresist is spin-coated onto a silicon wafer at a speed of 2500 rpm for 40 seconds to obtain a uniform photoresist film with a thickness of approximately 3.0 μm; the film is baked on a hot plate at 90°C for 150 seconds to remove residual solvent; a soft template with nano-patterns is used for imprinting under a pressure of 8 MPa; exposure is performed using an ultraviolet LED light source (wavelength 365 nm) with an exposure dose of 180 mJ / cm²; the film is then slowly and uniformly demolded to obtain a photoresist pattern with a clear nanostructure.

[0038] Example 2:

[0039] A nanoimprint photoresist composition for dry etching, comprising the following components by weight percentage:

[0040] 95% colloidal matrix;

[0041] Organometallic compounds containing unsaturated double bonds: 5%.

[0042] The organometallic compound containing unsaturated double bonds is zirconium methacrylate, which contains a carbon-carbon double bond in its molecule and zirconium as the metal element. During photocuring, its double bond undergoes a copolymerization and crosslinking reaction with the acrylate resin in the colloidal matrix to form a zirconium-containing three-dimensional network structure.

[0043] The colloidal matrix is ​​composed of the following components in parts by weight: 18 parts of acrylate resin (prepolymer of cyclohexyl methacrylate and trimethylolpropane triacrylate); 5 parts of free radical photoinitiator (1-hydroxycyclohexylphenyl ketone); 8 parts of reactive diluent (isobornyl methacrylate); and 55 parts of organic solvent (diethylene glycol dimethyl ether).

[0044] The preparation method includes the following steps: acrylate prepolymer and organic solvent are stirred and dissolved in a 40°C water bath for 60 minutes; after the system cools to 30°C, reactive diluent and free radical photoinitiator are added sequentially, and stirred at a constant speed for 40 minutes; under light-protected conditions, zirconium methacrylate is slowly added, and stirring is continued for 90 minutes until the system is homogeneous; the photoresist solution is obtained by filtration using a 0.1μm polytetrafluoroethylene (PTFE) filter membrane and stored in a brown bottle filled with nitrogen.

[0045] The photoresist film preparation and patterning process is as follows: The photoresist solution is filtered using a 0.1 μm pore size filter membrane; spin-coating is performed on a silicon substrate with pre-deposited silicon nitride at 3000 rpm for 30 seconds to obtain a uniform photoresist film with a thickness of approximately 2.5 μm; the film is baked on a hot plate at 100°C for 120 seconds; imprinting is performed using a quartz template with a 100 nm linewidth pattern under a pressure of 10 MPa; exposure is performed using 365 nm ultraviolet light with an exposure dose of 150 mJ / cm²; the film is slowly and uniformly demolded to obtain a photoresist pattern with a clear nanostructure.

[0046] Example 3:

[0047] A nanoimprint photoresist composition for dry etching, comprising the following components by weight percentage:

[0048] Colloidal matrix 88%;

[0049] Organometallic compounds containing unsaturated double bonds 12%.

[0050] The organometallic compound containing unsaturated double bonds is aluminum acrylate (chemical formula can be represented as Al(AA)3, where AA represents acrylate group). Its molecule contains three acrylate groups (i.e. three carbon-carbon double bonds) that can participate in free radical polymerization, and the metal element is aluminum. During photocuring, its multifunctional characteristics can promote the formation of aluminum-containing three-dimensional network structure.

[0051] The colloidal matrix is ​​composed of the following components in parts by weight: 25 parts of acrylate resin (selected as a copolymer of methyl methacrylate and butyl acrylate); 4 parts of free radical photoinitiator (selected as benzophenone); 8 parts of reactive diluent (selected as tripropylene glycol diacrylate); and 50 parts of organic solvent (selected as propylene glycol methyl ether acetate).

[0052] The preparation method includes the following steps: acrylate resin and organic solvent are stirred and mixed at 25°C for 2 hours until completely dissolved; reactive diluent and free radical photoinitiator are added sequentially, and stirring is continued for 60 minutes; aluminum acrylate complex is slowly added under light-protected and nitrogen-protected conditions, and stirring is continued for 90 minutes to ensure sufficient dispersion and pre-reaction; the photoresist solution is obtained by filtration using a 0.1 μm polytetrafluoroethylene (PTFE) filter membrane and stored in a brown bottle under nitrogen purging.

[0053] The photoresist film preparation and patterning process is as follows: The photoresist solution is filtered using a 0.1 μm pore size filter membrane; a silicon dioxide layer is thermally grown on the surface of the silicon wafer and spin-coated at 2800 rpm for 35 seconds to obtain a uniform photoresist film with a thickness of approximately 2.8 μm; the film is baked on a hot plate at 95°C for 130 seconds to remove residual solvent; a quartz template with a nano-grating pattern is used for imprinting under a pressure of 9 MPa; exposure is performed using an ultraviolet light source (wavelength 365 nm) with an exposure dose of 160 mJ / cm²; after exposure, the film is demolded at a uniform speed to obtain a photoresist pattern with a clear nanostructure.

[0054] Comparative example:

[0055] A conventional nanoimprint photoresist composition that does not contain any organometallic compounds and is a pure organic system;

[0056] The specific composition of the photoresist composition is as follows (by mass percentage):

[0057] The colloidal matrix is ​​100%; the colloidal matrix is ​​composed of the following components in parts by weight: 20 parts of acrylate resin (selected as a copolymer of methyl methacrylate and butyl acrylate); 5 parts of free radical photoinitiator (selected as 2-hydroxy-2-methyl-1-phenyl-1-propanone); 12 parts of reactive diluent (selected as tripropylene glycol diacrylate); and 60 parts of organic solvent (selected as propylene glycol methyl ether acetate).

[0058] The preparation method includes the following steps: acrylate resin and organic solvent are stirred and mixed at 25°C for 2 hours until completely dissolved; reactive diluent and free radical photoinitiator are added, and stirring is continued for 60 minutes until the system is homogeneous; the mixture is filtered through a 0.1μm polytetrafluoroethylene (PTFE) filter membrane to obtain a clear and transparent pure organic photoresist solution, which is stored in a light-proof container for later use.

[0059] The photoresist film preparation and patterning process is as follows: The photoresist solution is filtered using a 0.1 μm pore size filter membrane; spin-coating is performed on a silicon wafer of the same specifications (with a 300 nm silicon dioxide layer thermally grown on the surface) at a speed of 3000 rpm for 30 seconds to obtain a uniform photoresist film with an initial thickness of approximately 2.5 μm; the film is baked on a hot plate at 100 °C for 120 seconds; imprinting is performed using the same quartz template with a 100 nm linewidth / spacing grating pattern under a pressure of 10 MPa; exposure is performed using an ultraviolet light source (wavelength 365 nm) with an exposure dose of 150 mJ / cm²; the film is then slowly and uniformly demolded to obtain a photoresist pattern with a nanostructure.

[0060] Experimental example:

[0061] This experimental example uses a standardized nanoimprinting and dry etching process to quantitatively compare the performance of the photoresists prepared in Examples 1 to 3 of this invention with those of the comparative examples in key indicators such as dry etching resistance and pattern fidelity.

[0062] Three metal-containing photoresists prepared according to the present invention were selected as experimental groups: sample A (containing 5% zirconium methacrylate), sample B (containing 12% titanium acrylate), and sample C (containing 8% aluminum acrylate complex); meanwhile, a conventional pure organic photoresist without any organometallic compounds (comparative example) was used as control group sample D.

[0063] All photoresist samples were prepared using the same patterning process: on a 4-inch single-crystal silicon wafer with a 300nm silicon dioxide layer thermally grown on the surface, the initial photoresist film thickness was controlled to be (2.0±0.1)μm by spin coating, followed by baking on a hot plate at 100℃ for 120 seconds; using the same quartz template with a 100nm linewidth / spacing (1:1) grating pattern, nanoimprinting was performed under a pressure of 10MPa, and curing and demolding were performed with a 365nm wavelength ultraviolet light source and a fixed exposure dose of 150mJ / cm², thereby obtaining an initial nanopattern with a consistent structure;

[0064] All patterned samples were placed in the same inductively coupled plasma (ICP) etching chamber and subjected to simultaneous dry etching under identical process conditions. A CF4 / O2 / Ar mixed gas was used for etching, with parameters such as power, pressure, and flow rate kept constant. The etching target was to remove 150 nm of the exposed silicon dioxide layer. After etching, the thickness of the photoresist and silicon dioxide layer in the unpatterned areas was measured before and after etching using a film thickness gauge. The etching rates were calculated, and the etching selectivity (i.e., the ratio of silicon dioxide etching rate to photoresist etching rate) was further derived.

[0065] The cross-sectional morphology of the photoresist lines after etching was observed using a scanning electron microscope (SEM), and the critical dimension and sidewall angle at the top were measured and compared with the pattern before etching to evaluate the pattern fidelity (expressed as critical dimension retention rate).

[0066] X-ray photoelectron spectroscopy (XPS) surface analysis was performed on etched sample A (containing zirconium) and sample D (pure organic).

[0067] The experimental results are shown in the table below:

[0068] Performance metrics Sample A (Zr-containing) Sample B (Ti-containing) Sample C (Al-containing) Sample D (pure organic) Photoresist etch rate (nm / min) 32.5 29.8 26.4 108.2 Silicon dioxide etch rate (nm / min) 55.0 54.7 55.1 54.9 etch selectivity (SiO2 / resin) 1.69:1 1.84:1 2.09:1 0.51:1 Post-etch CD retention (top, %) 98.5 97.8 99.2 81.5 Post-etch sidewall angle (°) 88 87 89 74 Loss of resist after etching 150 nm of SiO2 (nm) ≈88 ≈81 ≈72 ≈ 295 (resist layer almost depleted)

[0069] As can be seen from the above, by introducing organometallic compounds that can participate in cross-linking into the photoresist, a dense metal compound protective layer is formed in situ on the surface of the photoresist layer in a dry etching environment, which effectively blocks the physical sputtering and chemical erosion of plasma, and improves the photoresist's resistance to dry etching, etching selectivity and pattern transfer fidelity.

[0070] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art 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 appended claims and their equivalents.

Claims

1. A nanoimprint resist composition for dry etching, characterized by, consists of the following components by mass percentage: colloidal matrix 80%-99.5%; unsaturated double bond-containing organometallic compound 0.5%-20%; the unsaturated double bond-containing organometallic compound can copolymerize and crosslink with the colloidal matrix during photocuring to form a crosslinked cured polymer; the metal element in the crosslinked cured polymer chemically reacts with plasma to form a refractory inorganic metal compound and accumulates on the surface of the photoresist film to form a protective layer.

2. The nanoimprint photoresist composition for dry etching according to claim 1, wherein: the unsaturated double bond-containing organometallic compound has at least one double bond, preferably 1-4 double bonds; the metal element is selected from at least one of magnesium, calcium, aluminum, titanium, zirconium, hafnium, vanadium, chromium, molybdenum, tungsten, manganese, iron, cobalt, nickel, copper, zinc, cadmium, indium, tin, or antimony.

3. The nanoimprint photoresist composition for dry etching according to claim 1, wherein: the unsaturated double bond-containing organometallic compound is zirconium methacrylate.

4. The nanoimprint photoresist composition for dry etching according to claim 1, wherein: the colloidal matrix comprises the following components by weight: acrylate resin 8-30 parts, free radical photoinitiator 2-10 parts, active diluent 5-15 parts, and organic solvent 30-65 parts.

5. A nanoimprint photoresist for dry etching, characterized by, consisting of the composition of any one of claims 1-4, wherein the mass percentage of the unsaturated double bond-containing organometallic compound is 2%-17% and the mass percentage of the colloidal matrix is 83%-98%.

6. A nanoimprint photoresist for dry etching, characterized by, consisting of the composition of any one of claims 1-4, wherein the mass percentage of the unsaturated double bond-containing organometallic compound is 5%-10% and the mass percentage of the colloidal matrix is 90%-95%.

7. A method of producing a nanoimprint resist according to any one of claims 1 to 6, characterized in that comprising the following steps: weighing the components according to the ratio, mixing uniformly to obtain the photoresist composition.

8. A method for preparing an anti-dry-etching nanoimprint resist film, characterized by, comprising: the photoresist composition of any one of claims 1-6 is sequentially filtered, coated, baked, imprinted, exposed and cured, and stripped to obtain a dry-etching-resistant photoresist pattern with a protective film structure.

9. A nanoimprint photoresist composition for dry etching according to claim 8, wherein: the filter membrane used for filtering has a pore size of 0.01-1 μm; the coating thickness is 0.1-10 μm; the baking temperature is 80-120°C and the time is 30-180 s; the exposure dose is 30-300 mJ / cm².

10. Use of the nanoimprint photoresist of any one of claims 1-6 in a semiconductor nanoimprint lithography process.

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