A photoresist composition and a method for preparing the same

Abstract

The present application relates to the technical field of photoresist, in particular to a photoresist composition and a preparation method thereof; the photoresist composition comprises 30-45 parts of p-hydroxystyrene copolymer, 2-4 parts of triphenylsulfonium salt, 8-15 parts of metal cluster, 10-20 parts of ethylene oxide, 2-3 parts of free radical photoinitiator and 30-40 parts of solvent; the p-hydroxystyrene copolymer is used as the main body, the triphenylsulfonium salt is used as the photoacid generator, the metal cluster is added to increase the absorption of ultraviolet light, the dendritic ethylene oxide resin is connected with each other to form a crosslinked network structure after ring-opening reaction under acidic conditions, the solubility of the photoresist film is reduced, the free radical photoinitiator is added, a negative photoresist composition is prepared, the negative photoresist composition has strong absorption capacity for deep ultraviolet light, the sensitivity and the etching resistance of the photoresist are improved, the minimum resolution size of the photoresist is small, the irradiation area forms a network structure and is not easy to be eluted, and the overall performance of the negative photoresist is improved.

Description

Technical Field

[0001] This invention relates to the field of photoresist technology, and more specifically to a photoresist composition and its preparation method. Background Technology

[0002] Photolithography is a crucial technique in the semiconductor industry for fabricating micro- and nano-scale patterns. Photoresist is fundamental for pattern transfer and is the core material of the photolithography process. It typically consists of resin, photosensitizer, solvent, and other additives. With the increasing demand for smaller photolithography sizes, light sources have evolved from g-line (436nm), i-line (365nm), KrF (248nm), and ArF (193nm) to extreme ultraviolet (13.5nm). Shorter wavelengths enable photolithography with smaller resolution patterns, but the high energy (up to 92eV) places new demands on the photoresist's etching resistance. Furthermore, the resolution of the photoresist is also a significant factor limiting the size of photolithography patterns.

[0003] my country still has weaknesses in the field of high-end lithography, particularly in KrF photoresist. 、 ArF and extreme ultraviolet (EUV) photoresists still lag behind top-tier standards. Domestically produced alternative photoresists are scarce and lack maturity. In recent years, domestic research on KrF... 、 ArF photoresists have made some progress, and extreme ultraviolet (EUV) photoresists are expected to catch up with world-class standards. Traditional photoresists are not suitable for EUV lithography. Traditional C-bonded photoresists absorb less EUV light, resulting in significant energy waste and affecting the resolution, roughness, and minimum resolution of the lithography. EUV lithography uses photon energies as high as 92 eV. During exposure, almost all atoms in existing photoresists can absorb EUV photons and become ionized, generating high-energy secondary electrons (65–87 eV), which increases roughness and makes them unsuitable for increasingly thinner photoresists.

[0004] For extreme ultraviolet (EUV) photoresists, there is a need to develop a photoresist with strong UV absorption capacity, good etching resistance, good stability, high sensitivity to UV, and small resolution to meet the domestic demand for EUV photoresists. Summary of the Invention

[0005] The purpose of this invention is to provide a photoresist composition and its preparation method, which makes the prepared negative photoresist composition have a strong absorption capacity for deep ultraviolet light, improves the sensitivity and etching resistance of the photoresist, has a small minimum resolution size, forms a mesh structure in the irradiated area, is not easily washed away, and improves the overall performance of the negative photoresist.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A photoresist composition comprising the following raw materials in parts by weight:

[0008]

[0009] The method for preparing the photoresist composition includes the following steps:

[0010] Step 1: Under light-protected conditions, take half the mass of the solvent and place it in the reaction vessel. Purge with nitrogen gas and then continuously introduce nitrogen gas. Add the mass of the metal cluster and stir to mix evenly. Add the mass of the triphenylthionium salt and continue stirring to mix evenly to obtain mixture A.

[0011] Step 2: Under light-protected conditions, place the remaining mass fraction of solvent into a reaction vessel, purge with nitrogen, and then continuously purge with nitrogen. Add the mass fractions of p-hydroxystyrene copolymer, ethylene oxide, and free radical photoinitiator, and stir to mix evenly to obtain mixture B.

[0012] Step 3: Under light-protected conditions, mix mixture A obtained in Step 1 and mixture B obtained in Step 2, and stir magnetically for 3 to 12 hours to obtain a photoresist composition.

[0013] More preferably, the general structural formula of the p-hydroxystyrene copolymer is:

[0014]

[0015] Among them, the functional group R is

[0016]

[0017] One or more of them.

[0018] Further preferably, the general structural formula of the triphenylthionium salt is:

[0019]

[0020] Wherein R is one or more of the following: halogen anion, p-hydroxybenzenesulfonic acid anion, hexafluorophosphate anion, sulfonate anion, and trifluoromethanesulfonate anion.

[0021] Further preferably, the metal cluster is a metal cluster composed of one of the metals Sn, Zn, Zr, Sb, and Ti as the core, and one or more of the ligands of methacrylic acid, trifluoroacetic acid, 4-methylpyrazole, 2-(trifluoromethyl)acrylic acid, and aromatic ring-containing organic carboxylic acids, with the number of metal cores being 4, 6, or 8.

[0022] Further preferably, the metal cluster is a metal cluster with four metal atoms as its core, and its structural formula is:

[0023]

[0024] Where M represents a metal atom and R represents a ligand.

[0025] Further preferably, the ethylene oxide is a dendritic ethylene oxide resin, which is:

[0026]

[0027] One or more of them.

[0028] Further preferably, the free radical photoinitiator is a mixture of 2-hydroxy-2-methyl-1-phenylpropanone, 1-hydroxycyclohexylphenyl ketone, and isopropylthioxanthone in a mass ratio of 1:3 to 5:2.

[0029] More preferably, the solvent is one or more of diethylene glycol monomethyl ether, ethyl acetate, n-butyl acetate, cyclopentanone, and cyclohexanone.

[0030] The beneficial effects of this invention are:

[0031] 1. Using p-hydroxystyrene copolymer as the main material and triphenyl thionium salt as the photoacid generator, metal clusters are added to increase the absorption of ultraviolet light. Dendritic ethylene oxide resin is added, which undergoes a ring-opening reaction under acidic conditions and then connects with each other to form a cross-linked network structure, reducing the solubility of the photoresist film. Free radical photoinitiators are added to prepare a negative photoresist composition, which improves the absorption of deep ultraviolet light by the photoresist composition and improves the sensitivity and etching resistance of the photoresist.

[0032] 2. This invention uses p-hydroxystyrene copolymer, whose side chains contain a variety of functional groups. The photosensitive groups generate free radicals under light irradiation, causing cross-linking reactions between the p-hydroxystyrene chains. This results in the p-hydroxystyrene copolymer forming larger molecules and reducing solubility. The double-bonded functional groups in the side chains can further assist in the cross-linking of the p-hydroxystyrene copolymer and reduce solubility. In addition, the introduction of oxygen- or sulfur-containing functional groups into the side chains increases the absorption intensity of the p-hydroxystyrene copolymer for extreme ultraviolet light, thereby improving the sensitivity of the prepared photoresist.

[0033] 3. This invention uses triphenylthionium salt as a photoacid-generating agent. Under light irradiation, the triphenylthionium salt photolyzes to form a thioether structure. The generated photoacid does not diffuse, ensuring the stability of the pattern formed by photolithography. The acid generated by the triphenylthionium salt under light irradiation provides local acidic conditions for the ethylene oxide resin. Under acidic conditions, the ethylene oxide undergoes a ring-opening reaction. The ring-opened ethylene oxide molecules connect with each other, causing the dendritic individual ethylene oxide resin molecules to connect into multiple, forming a network structure, reducing solubility. Moreover, the network structure is only formed in the light-illuminated area, making the light-illuminated area less susceptible to being washed away, which is beneficial to improving the performance of negative photoresist.

[0034] 4. Metal clusters, with d-orbital electron-containing metal atoms as cores and organic materials as ligands, form 4, 6, and 8-core metal clusters. The ligand materials have good compatibility with other organic components in the photoresist, allowing the metal clusters to be uniformly dispersed in the photoresist. The metal atomic cores have a high absorption cross-section for extreme ultraviolet light, improving the photoresist's sensitivity to extreme ultraviolet light. The structure of the metal clusters is precisely known, facilitating targeted design and forming small particles with uniform particle size, which is beneficial for precise control of the photoresist linewidth and roughness. In addition, compared with ordinary organic polymers, the addition of metal clusters helps to improve the etching resistance of the photoresist composition, meeting the etching resistance requirements even with thinner photoresist films. After absorbing extreme ultraviolet light, the metal clusters can directly polymerize, changing their solubility and improving the overall performance of the negative photoresist.

[0035] 5. The use of free radical photoinitiators assists the free radicals generated by the side chains under light irradiation to play a role in promoting the cross-linking polymerization reaction of various components in the photoresist. This allows the light-irradiated or light-radiated areas to quickly cross-link into a whole, making them difficult to wash off in subsequent development processes. Furthermore, it protects the metal film covered by the photoresist during the etching process, resulting in a clear pattern. The use of solvents increases the fluidity of the photoresist, dispersing the various components in the photoresist composition evenly, forming a photoresist with uniform composition and stable performance. Detailed Implementation

[0036] The technical solution of the present invention will be clearly and completely described below. 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.

[0037] Example 1

[0038] A photoresist composition comprising the following raw materials in parts by weight: 30 parts of p-hydroxystyrene copolymer, 2 parts of triphenyl thionium salt, 8 parts of metal clusters, 10 parts of ethylene oxide, 2 parts of free radical photoinitiator, and 30 parts of solvent;

[0039] The free radical photoinitiator is a mixture of 2-hydroxy-2-methyl-1-phenylpropanone, 1-hydroxycyclohexylphenyl ketone, and isopropylthioxanthone in a mass ratio of 1:3:2; the solvent is diethylene glycol monomethyl ether.

[0040] The general structural formula of the p-hydroxystyrene copolymer is:

[0041] Among them, the functional group R is

[0042] The general structural formula of the triphenylthionium salt is:

[0043] Where R is the trifluoromethanesulfonate anion;

[0044] The metal clusters are metal clusters with one of the metals Zn as the core and methacrylic acid as the ligand, and the number of metal cores is 4.

[0045] The ethylene oxide is a dendritic ethylene oxide resin, which is:

[0046]

[0047] The method for preparing the photoresist composition includes the following steps:

[0048] Step 1: Under light-protected conditions, take half the mass of the solvent and place it in the reaction vessel. Purge with nitrogen gas and then continuously introduce nitrogen gas. Add the mass of the metal cluster and stir to mix evenly. Add the mass of the triphenylthionium salt and continue stirring to mix evenly to obtain mixture A.

[0049] Step 2: Under light-protected conditions, place the remaining mass fraction of solvent into a reaction vessel, purge with nitrogen, and then continuously purge with nitrogen. Add the mass fractions of p-hydroxystyrene copolymer, ethylene oxide, and free radical photoinitiator, and stir to mix evenly to obtain mixture B.

[0050] Step 3: Under light-protected conditions, mix mixture A obtained in Step 1 and mixture B obtained in Step 2, and stir magnetically for 3 hours to obtain a photoresist composition.

[0051] Example 2

[0052] A photoresist composition comprising the following raw materials in parts by weight: 45 parts of p-hydroxystyrene copolymer, 4 parts of triphenyl thionium salt, 15 parts of metal clusters, 20 parts of ethylene oxide, 3 parts of free radical photoinitiator, and 40 parts of solvent;

[0053] The free radical photoinitiator is a mixture of 2-hydroxy-2-methyl-1-phenylpropanone, 1-hydroxycyclohexylphenyl ketone, and isopropylthioxanthone in a mass ratio of 1:5:2; the solvent is ethyl acetate.

[0054] The general structural formula of the p-hydroxystyrene copolymer is:

[0055] Among them, the functional group R is

[0056] The general structural formula of the triphenylthionium salt is:

[0057] Where R is the p-hydroxybenzenesulfonic acid anion;

[0058] The metal clusters are metal clusters with Ti as the core and 4-methylpyrazole as the ligand, and the number of metal cores is 6.

[0059] The ethylene oxide is a dendritic ethylene oxide resin, which is:

[0060]

[0061] The method for preparing the photoresist composition includes the following steps:

[0062] Step 1: Under light-protected conditions, take half the mass of the solvent and place it in the reaction vessel. Purge with nitrogen gas and then continuously introduce nitrogen gas. Add the mass of the metal cluster and stir to mix evenly. Add the mass of the triphenylthionium salt and continue stirring to mix evenly to obtain mixture A.

[0063] Step 2: Under light-protected conditions, place the remaining mass fraction of solvent into a reaction vessel, purge with nitrogen, and then continuously purge with nitrogen. Add the mass fractions of p-hydroxystyrene copolymer, ethylene oxide, and free radical photoinitiator, and stir to mix evenly to obtain mixture B.

[0064] Step 3: Under light-protected conditions, mix mixture A obtained in Step 1 and mixture B obtained in Step 2, and stir magnetically for 12 hours to obtain a photoresist composition.

[0065] Example 3

[0066] A photoresist composition comprising the following raw materials in parts by weight: 40 parts of p-hydroxystyrene copolymer, 3 parts of triphenyl thionium salt, 12 parts of metal clusters, 15 parts of ethylene oxide, 3 parts of free radical photoinitiator, and 35 parts of solvent;

[0067] The free radical photoinitiator is a mixture of 2-hydroxy-2-methyl-1-phenylpropanone, 1-hydroxycyclohexylphenyl ketone, and isopropylthioxanthone in a mass ratio of 1:4:2; the solvent is cyclopentanone.

[0068] The general structural formula of the p-hydroxystyrene copolymer is:

[0069] Among them, the functional group R is

[0070] The general structural formula of the triphenylthionium salt is:

[0071] Where R is the sulfonate anion;

[0072] The metal clusters are metal clusters with metal Sn as the core and 2-(trifluoromethyl)acrylic acid as the ligand, with a number of 8 metal cores;

[0073] The ethylene oxide is a dendritic ethylene oxide resin, which is:

[0074]

[0075] The method for preparing the photoresist composition includes the following steps:

[0076] Step 1: Under light-protected conditions, take half the mass of the solvent and place it in the reaction vessel. Purge with nitrogen gas and then continuously introduce nitrogen gas. Add the mass of the metal cluster and stir to mix evenly. Add the mass of the triphenylthionium salt and continue stirring to mix evenly to obtain mixture A.

[0077] Step 2: Under light-protected conditions, place the remaining mass fraction of solvent into a reaction vessel, purge with nitrogen, and then continuously purge with nitrogen. Add the mass fractions of p-hydroxystyrene copolymer, ethylene oxide, and free radical photoinitiator, and stir to mix evenly to obtain mixture B.

[0078] Step 3: Under light-protected conditions, mix mixture A obtained in Step 1 and mixture B obtained in Step 2, and stir magnetically for 8 hours to obtain a photoresist composition.

[0079] Testing: The photoresist compositions prepared in Examples 1-3 were spin-coated and tested. Specifically, the photoresist composition was dropped onto a silicon substrate, spin-coated at a low speed of 100 r / min for 10 s, then at a high speed of 10000 r / min for 60 s, dried at 110°C for 120 s, exposed to extreme ultraviolet light at 13.5 nm, and developed with dimethylacetamide for 60 s. The thickness change of the photoresist film was measured using a profilometer. Strips of different sizes were etched using argon ion dry etching at an energy of 400 eV. After etching, the smallest clearly resolvable strip size was recorded to characterize the resolution of the photoresist composition. The etching was performed at an energy of 400 eV and an argon ion dry etching process with an argon ion flow rate of 0.5 mA / cm². 2 The beam current density was set, and the photoresist composition was etched using argon ion dry etching for 10 min. The thickness of the photoresist film was measured using a profilometer, and the etched thickness was recorded to characterize the photoresist's etching resistance. The results are as follows:

[0080] Example 1 Example 2 Example 3 Thickness (nm) 833 836 834 Minimum resolution size (nm) 24 23 24 Etching away thickness (nm) 10 8 9

[0081] As shown in the table above, the photoresist composition prepared by the method of the present invention has good film-forming properties, uniform and stable film thickness, small minimum resolution size, less etched thickness, and good etching resistance.

[0082] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A photoresist composition, characterized in that, The raw materials include the following parts by weight: The metal clusters are metal clusters with one of the metals Sn, Zn, Zr, Sb, and Ti as the core and one or more of the ligands of methacrylic acid, trifluoroacetic acid, 4-methylpyrazole, 2-(trifluoromethyl)acrylic acid, and aromatic ring-containing organic carboxylic acids, and the number of metal cores is 4, 6, or 8. The ethylene oxide is a dendritic ethylene oxide resin, which is: One or more of them; The free radical photoinitiator is a mixture of 2-hydroxy-2-methyl-1-phenylpropanone, 1-hydroxycyclohexylphenyl ketone, and isopropylthioxanthone in a mass ratio of 1:3 to 5:

2. The method for preparing the photoresist composition includes the following steps: Step 1: Under light-protected conditions, take half the mass of the solvent and place it in the reaction vessel. Purge the air with nitrogen gas, and then continuously introduce nitrogen gas. Add the mass of the metal cluster and stir to mix evenly. Add the mass of the triphenylthionium salt and continue to stir to mix evenly to obtain mixture A. Step 2: Under light-protected conditions, place the remaining mass fraction of solvent into a reaction vessel, purge the air with nitrogen, and then continuously purge with nitrogen. Add the mass fractions of p-hydroxystyrene copolymer, ethylene oxide, and free radical photoinitiator, and stir to mix evenly to obtain mixture B. Step 3: Under light-protected conditions, mix mixture A obtained in Step 1 and mixture B obtained in Step 2, and stir magnetically for 3 to 12 hours to obtain a photoresist composition.

2. The photoresist composition according to claim 1, characterized in that, The general structural formula of the p-hydroxystyrene copolymer is: Among them, the functional group R is One or more of them.

3. The photoresist composition according to claim 1, characterized in that, The general structural formula of the triphenylthionium salt is... for: Wherein R is one or more of the following: halogen anion, p-hydroxybenzenesulfonic acid anion, hexafluorophosphate anion, sulfonate anion, and trifluoromethanesulfonate anion.

4. The photoresist composition according to claim 1, characterized in that: When the metal cluster is a metal cluster with four metal atoms as its core, its structural formula is: Where M represents a metal atom and R represents a ligand.

5. The photoresist composition according to claim 1, characterized in that: The solvent is one or more of diethylene glycol monomethyl ether, ethyl acetate, n-butyl acetate, cyclopentanone, and cyclohexanone.

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