JPH0139569B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a photosensitive material. More specifically, it relates to a photosensitive material that absorbs deep ultraviolet rays and crosslinks. Most of the resists currently used for manufacturing integrated circuits (ICs) are negative photoresists made by blending a bisazide compound with so-called cyclized rubber, which is made by cyclizing polyisoprene. This resist utilizes a reaction mechanism in which a bisazide compound absorbs near-ultraviolet light (300 nm or more), converts into nitrene, and crosslinks the cyclized rubber. However, since resists made of cyclized rubber use near-ultraviolet rays with long wavelengths as a means of crosslinking, they are susceptible to diffraction phenomena in the resist layer coated on the silicon substrate and the effects of light reflected from the silicon substrate surface. It is considered impossible to achieve submicron resolution due to problems such as scattering phenomena. In order to solve this problem, the development of resist materials that are sensitive to short-wavelength deep ultraviolet rays has progressed, including polymethyl methacrylate, polymethyl isopropenyl ketone, and poly(glycidyl methacrylate-methyl methacrylate). Polymers are being researched as far-UV resists, and some of them are already on the market. These resists have a different mechanism of action against light than the cyclized rubber photoresists described above. In other words, whereas cyclized rubber-based photoresists absorb ultraviolet light and crosslink, these resists decompose and utilize the improved solubility in solvents due to a decrease in the molecular weight of the polymer for patterning. This is a so-called positive photoresist. However, in order to make the solubility of a polymer that has been decomposed and reduced to a low molecular weight extremely different from that of the original polymer, the molecular weight must be reduced considerably, and a large amount of energy is required for this purpose. For example, polymethyl methacrylate is the material most rapidly studied, but it is already known that it has good resolution but poor sensitivity. Furthermore, in order to drastically change the solubility difference in the developing solution between the exposed and non-exposed areas of the resist, the cross-linked type is more advantageous than the decomposed type. This is because in the decomposition type, even if you try to decompose the material that makes up the resist to create a difference in molecular weight between the non-exposed area and the non-exposed area, the difference in molecular weight is limited, whereas in the cross-based type, the exposed area becomes three-dimensional. Therefore, from the concept of molecular weight, the difference in molecular weight from the non-photosensitive area is considered to be infinite. All of the above-mentioned far ultraviolet resists are positive type resists that belong to the decomposition type, and at present, almost no crosslinked type, so-called negative type, far ultraviolet resists are known. An object of the present invention is to provide a photosensitive material suitable as a negative-type deep ultraviolet resist, which has good resolution and particularly excellent sensitivity. According to the invention, the general formula (In the formula, R is a cyano group, a carboxyl group, an alkoxycarbonyl group, an alkyl group, a halogen atom, or a haloalkyl group.) Materials provided. The photosensitive material of the present invention has good resolution and excellent sensitivity, and also has the advantage that a thin film formed by coating on a substrate such as silicon or aluminum does not peel off easily. Next, the present invention will be explained in detail. The photosensitive material of the present invention, a compound having a structure obtained by (co)polymerizing a monomer having a pyrimidine group represented by the general formula, can be obtained, for example, by the following method: (1) A pyrimidine group represented by the general formula or a method of (co)polymerizing this monomer and other copolymerizable monomers. (2) A pyrimidine group of the general formula is added to a polymer of α,β-ethylenically unsaturated carboxylic acid or a copolymer of α,β-ethylenically unsaturated carboxylic acid and other monomers that can be copolymerized. A method of reacting a compound with The (co)polymerization method in (1) above is not particularly limited, but if the monomer having a pyrimidine group contains an ethylenically unsaturated bond, for example, a solution radical polymerization method may be used. In this case, the solvent is dimethylformamide, dimethylsulfoxide, hexamethylphosphoramide, tetrahydrofuran, etc., the catalyst is a radical polymerization initiator such as 2,2'-azobisisobutyronitrile, benzoyl peroxide, etc. An example of the temperature is 40 to 100°C. In addition, when the monomer having a pyrimidine group contains a ring-opening polymerizable epoxy group, for example, a ring-opening polymerization catalyst such as boron trifluoride, tin tetrachloride, or titanium tetrachloride is used as a solvent. can be (co)polymerized using dichloroethane, dimethylsulfoxide, dimethylformamide, etc., and at a polymerization temperature of, for example, -50°C to 150°C. The reaction method in (2) above is not particularly limited, but for example, a (co)polymer of α,β-ethylenically unsaturated carboxylic acid polymerized by solution polymerization method, emulsion polymerization method, etc. is mixed with dimethylformamide or dimethyl sulfoxide. , hexamethylphosphoramide, tetrahydrofuran, or other solvent, furthermore, a compound having a pyrimidine group of the general formula is added and dissolved, and the carboxyl group of the copolymer and the compound having a pyrimidine group of the general formula are heated to react. can be shown. The heating reaction temperature in this case is preferably 40 to 100°C. In the method (1) above, monomers having a pyrimidine group represented by the general formula include, for example, (In the formula, R is an alkoxycarbonyl group such as a cyano group, a carboxyl group, a methoxycarbonyl group, an ethoxycarbonyl group, or a propoxycarbonyl group, an alkyl group such as a methyl group, an ethyl group, or a propyl group, or a halogen atom such as a chlorine atom or a bromine atom. or a haloalkyl group such as a chloromethyl group or a bromomethyl group, and R ¹ is

[Formula] or

[Formula], R ² is a hydrogen atom, a lower alkyl group such as a methyl group, an ethyl group, or a propyl group, or a halogen atom such as a chlorine atom or a bromine atom, and R ³ is a hydrogen atom or a methyl group, an ethyl group, It is a lower alkyl group such as propyl group. ) can be mentioned. In particular, compounds represented by the general formula in which R is a cyano group, R ² is a hydrogen atom or a methyl group, and R ³ is a hydrogen atom or a methyl group can be suitably used. Examples of these compounds include N-2-acryloyloxyethyl-6-cyanouracil and N-2-methacryloyloxyethyl-6-cyanouracil. Other monomers that can be copolymerized with the monomer having a pyrimidine group represented by the general formula include ethyl methacrylate, propyl methacrylate, butyl methacrylate, isobutyl methacrylate, amyl methacrylate, and octyl methacrylate. Methacrylate, 2-
Methacrylic acid alkyl esters such as ethylhexyl methacrylate, decyl methacrylate, dodecyl methacrylate, acrylic acids such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, isobutyl acrylate, amyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, decyl acrylate, dodecyl acrylate Alkyl ester, cyclohexyl methacrylate,
Cyclic alkyl esters of methacrylic acid or acrylic acid such as cyclohexyl acrylate, aryl esters of methacrylic acid or acrylic acid such as benzyl methacrylate, phenylethyl methacrylate, benzyl acrylate, phenylethyl acrylate, diethyl maleate, diethyl fumarate, itaconic acid α, β such as diethyl
-Dialkyl ester of ethylenically unsaturated dicarboxylic acid, 2-hydroxyethyl methacrylate,
Hydroxy alkyl esters of methacrylic acid or acrylic acid such as 2-hydroxypropyl methacrylate, 2-hydroxyethyl acrylate, and 2-hydroxypropyl acrylate; moreolefin-based non-containers such as styrene, vinyltoluene, acrylonitrile, vinyl chloride, vinylidene chloride, and vinyl acetate; Examples include saturated compounds, conjugated diolefin compounds such as butadiene, isoprene, chloroprene, dimethylbutadiene, etc.
Examples of ring-opening polymerizable substances include epichlorohydrin,
Examples include glycidol, ethylene oxide, propylene oxide, isobutylene oxide, styrene oxide, and 2,3-epoxybutane. Examples of the α,β-ethylenically unsaturated carboxylic acid in the method (2) above include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid,
Monoethyl maleate, monoethyl fumarate, monoethyl itaconate, etc.
Other monomers that can be copolymerized with α,β-ethylenically unsaturated carboxylic acid include the same radically polymerizable monomers that can be copolymerized with the monomer having a pyrimidine group represented by the general formula above. I can list the following. In addition, in the method (2) above, a compound having a pyrimidine group of the general formula, for example, (In the formula, R represents the same substituent as R.) Specifically, 1,2-O-ethano-6-cyanouracil, 1,2-O-ethano-6-chloromethyl Examples include uracil, 1,2-O-ethano-6-trichloromethyluracil, and the like. In the present invention, the proportion of (co)polymerized structural units of the monomer having a pyrimidine group in a compound having a structure obtained by (co)polymerizing a monomer having a pyrimidine group represented by the general formula is determined by sensitivity and solvent solubility. 5 to 95% of the total number of (co)polymerized structural units in terms of
is preferable, particularly preferably 15 to 90%. In particular, a photosensitive material made of a compound having a structure obtained by copolymerizing a conjugated diolefin compound and a monomer having a pyrimidine group represented by the general formula has particularly excellent adhesion to a substrate. In this case, the content of conjugated diolefin compound units is preferably 5 to 95% of the total (co)polymer structural units, more preferably 10 to 85%, particularly preferably 10 to 50%.
%. Note that the molecular weight of the compound having a structure obtained by (co)polymerizing a monomer having a pyrimidine group represented by the general formula is not particularly limited, but when used as a resist, the number average molecular weight in terms of polystyrene is 5000 to 5000. 1,000,000, particularly preferably 10,000 to 500,000. A compound having a structure obtained by (co)polymerizing a monomer having a pyrimidine group represented by the general formula obtained by methods such as (1) or (2) above can be prepared by reprecipitation with a precipitating agent such as acetone, etc. It is purified by a method and made into a photosensitive material. When the photosensitive material of the present invention is used as a resist, it is generally dissolved in a solvent such as dimethylformamide, dimethylsulfoxide, hexamethylphosphoramide, tetrahydrofuran, etc., and applied as a solution to a substrate. It is also possible to add a photocrosslinking agent and a sensitizer to the photosensitive material of the present invention. EXAMPLES Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples in any way. Example 1 2.2 g (0.012 mol) of N-ethanooxy-6-
Dissolve cyanouracil in 15 ml of pyridine and add 3.7
ml of methacrylic anhydride was added and reacted at room temperature for 15 hours. After the reaction, pyridine and excess methacrylic acid were distilled off under reduced pressure, and the residue was recrystallized from ethanol to give 2.5 g of N-2-methacroyloxyethyl-6-cyanouracil in the form of colorless needles with a yield of 83%. Obtained as crystals. This product and butadiene were dissolved at a ratio (mole ratio) of 6:4 in a mixed solvent of water and ethanol (weight ratio = 1:1), and potassium persulfate was used as a radical initiator, and the mixture was heated to 18 °C at 60 °C.
By reacting for hours, a polymer having a number average molecular weight of about 10,000 in terms of polystyrene was obtained in a yield of 60% by weight. In this polymer, the proportion of (co)polymerized structural units of monomers having pyrimidine groups was 52% of the total number of (co)polymerized structural units. A photosensitive solution was prepared by dissolving 1 g of the reaction product obtained above in 5 ml of dimethylformamide and filtering through a Millipore filter with a pore size of 0.45 μm.
After applying this photosensitive solution on a silicon wafer with a spinner and drying it at room temperature in a nitrogen stream for 1 hour, the spectral sensitivity was measured using an irradiation spectrometer manufactured by JASCO Corporation, and it was found to be in the far ultraviolet region of 250 to 310 nm. This was confirmed. In addition, a quartz mask was closely attached to the resist film coated on the silicon wafer, and after irradiating it with far ultraviolet rays for 1 minute using a Canon Inc. exposure device PLA521F,
When developed with dimethylformamide, there was no film peeling and a fine pattern faithful to the mask could be reproduced. This wafer was placed in a nitrogen stream.
After post-baking at 120°C for 30 minutes, etching with a hydrogen fluoride/ammonium fluoride aqueous solution made it possible to create a pattern with almost no seepage.

Claims (1)

[Claims] 1. General formula (In the formula, R is a cyano group, a carboxyl group, an alkoxycarbonyl group, an alkyl group, a halogen atom, or a haloalkyl group.) material.