JPS6070443A - Formation of micropattern - Google Patents

Abstract

PURPOSE:To enable formation of a resist micropattern good in adhesion to a substrate with a small amt. of radiation to be irradiated by using a resist made of a mixture of specified radiation decomposable type polymers. CONSTITUTION:A substrate is coated as a radiation sensitive resist film with a mixture of one of a polymer group A made of a homopolymer of a monomer represented by formula I in which R1 is methyl or Cl and R2 is haloalkyl, or its copolymer with another vinyl monomer, and one of a polymer group B made of a copolymer of a monomer represented by formula II in which R3 is <9C alkyl. After it is prebaked at a proper temp., this resist film is exposed to radiation in a desired pattern. A resist micropattern superior in adhesion to the substrate is obtained by developing it to remove the irradiated parts selectively. As the polymer usable as said [A] group, polyrifluoroethyl alpha-chloroacryate, polytrifluoroisopropyl alpha-chloroacrylate, etc. are enumerated, and the polymer usable as the [B] group, cpolymers of methyl methacrylate-methacrylic acid and ethyl methacrylate-methacrylic acid are enumerated.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention broadly relates to the use of electron beams, X-rays,
The present invention relates to a method of forming a fine pattern by irradiating radiation such as an ion particle beam, and particularly to a method of forming a pattern using an improved polymer thin film.

[Technical background of the invention and its problems]

In recent years, lithography technology using radiation has been introduced as the density of semiconductor devices has increased. By the way, in the resist pattern formation method using radiation lithography, a radiation-sensitive resist film is coated on a substrate, this resist film is irradiated with radiation in a desired pattern, and then a development process is performed to form a pattern on the resist film. Wet or dry etching is performed using the resist pattern as a mask to form a desired pattern on the substrate IK.

Hitherto, halogen-containing positive resists such as polytonfluoroethyl α-chloroacrylate have been used as high-density positive radiation resists, but these resists are particularly suitable for silicon-based semiconductor substrates such as silicon, silicon oxide, silicon nitride, etc. They have poor adhesion with semiconductor substrates, and when patterns are formed on these semiconductor substrates, there is a drawback that pattern deformation is likely to occur due to poor adhesion with the substrate.

[Objective of the Invention J The present invention has been made in view of the above-mentioned circumstances, and it is an object of the present invention to completely form a fine resist pattern with excellent adhesion to a substrate without reducing sensitivity or resolution by using an improved resist film. We are trying to provide a way to obtain it.

[Summary of the invention]

That is, the present invention (forms a mixture of one or more polymers selected from the AJ group and one or more polymers selected from the CBJ group on a substrate as a radiation resist film, and prebakes at an appropriate temperature). After applying radiation, the resist film is irradiated with radiation in a desired number of turns and developed to selectively remove all the irradiated areas to form a fine resist pattern with excellent adhesion to the substrate.
-It is a characteristic.

(However, the tortoise represents a methyl group or a chlorine atom, and the island represents a rogenated alkyl group) (1) Consists of a homopolymer of the monomer represented by the formula or a copolymer of it and other vinyl yarn threads. Polymer group.

CB, Group 1 (- indicates an alkyl group having 8 or less carbon atoms) (2
) A group of polymers consisting of a copolymer of hetamine and methacrylic acid represented by the formula.

In the present invention, the polymers used as Group (A) include polytrifluoroethyl α-chloroacrylate, polytrinoroloinglovir α-chloroacrylate, polytrifluoro t-butyl α-chloroacrylate, poly1
-methquin trifluoroethyl α-chloroacrylate, polytrifluoroethyl methacrylate, polytrichloroethyl methacrylate, polyhexafluorobutyl methacrylate, and the like.

The resists used in group (B) include methyl methacrylate-methacrylic acid copolymer, ethyl methacrylate-methacrylic acid copolymer, and isopropyl methacrylate-methacrylic acid copolymer.

t-butyl methacrylate-methacrylic acid copolymer, n
-butyl methacrylate-methacrylic acid copolymer, isopentyl methacrylate-methacrylic acid copolymer, and the like.

The molecular weight of the polymer used as the CBJ group does not need to be high, but it is preferable that it is easily soluble in the coating solvent, and the molecular weight is preferably 100 or less. Also CB
If the copolymer ratio of methacrylic acid in the polymer used as the group ) increases, the solubility in the organic hexa-medium decreases, so it is preferable that the copolymer ratio of methacrylic acid is 30 molar or less.

Substrates used in the present invention include, for example, a single silicon substrate doped with impurities, a semiconductor substrate such as one in which a polycrystalline 7-licon film is provided via a silicon oxide layer using this substrate as a base material, and a compound such as gallium arsenide. semiconductor substrate,
Alternatively, a mask substrate such as a chromium film or a chromium oxide film laminated on a transparent glass plate can be used.

〔Effect of the invention〕

However, the resist used in the present invention is hydrophilic and contains as a component a copolymer having 1000H groups that strengthens the adhesiveness with the substrate.

It becomes possible to form a resist film with good adhesion to the substrate. However, if the mixing ratio of the CBJ group copolymers in this resist increases too much, the original properties of the CAJ group polymers, such as sensitivity and resolution, will be impaired. It is preferable that the mixing ratio is 10% by weight or less. That is, according to the present invention, by using the polymer mixed under the above conditions as a positive resist for radiation, it is possible to easily obtain a fine resist pattern with good adhesion to the substrate with a small irradiation dose. Become.

[Embodiments of the invention]

Example 1 Polytrifluoroethyl α-chloroacrylate (molecular weight 600,000) and methyl methacrylate-methacrylic acid copolymer (80:20) (molecule-1ijt 10,000) in a ratio of 95:5
A resist mixed at a ratio of (weight ratio) was applied to a film thickness of 1 μ by spin coating on a silicon substrate on which a silicon oxide film was formed, and prebaked at 200° C. for 1 hour.

Further, as a comparative example, polytrifluoroether α-chloroacrylate was formed to a thickness of 1 μm on a silicon oxide substrate by the same method.

Next, add the above two types of resin), beam diameter 0.1 to ffl
μ, acceleration d pressure 20KV playback beam 0.5μ life
1.0μ, X, /<-s, length 100μ pattern K
MIBK (methyl isobutyl ketone)-IPA (inglovir alcohol) was irradiated with a dose of 10 μC/d.
A pattern was formed using a developer consisting of a mixed solution (65:35 volume ratio). When the formed pattern was observed, it was found that the mixed resist pattern according to the present invention had no pattern flow and a fine pattern of 0.5 μm was formed. Pattern flow was observed in some parts of the resist. Then CF4-)(,(70:30
Partial pressure ratio) Dry etching was performed using a mixed gas to mask the mixed resist pattern, and when the resist was removed with oxygen plasma, the resist pattern was clearly visible.
It was confirmed that the image was transferred onto the AB silicon substrate.

Example 2 Polytrinofluoroinglovir α-chloroacrylate (molecular weight 1 million) and methyl methacrylate-methacrylic acid copolymer (80:20) (molecular weight 10,000) were mixed in a 95:5 ratio.
A resist mixed at a ratio of (weight ratio) is applied to a film thickness of 1μ on a silicon substrate by spin coating,
Pre-baking treatment was performed for 180°01 hour. In addition, as a comparative example, polytrifluoroimprovil α-chloroacrylate was formed to a thickness of 1 μm on a silicon substrate by the same method.

Next, an electron beam with a beam diameter of 0.1μ and an acceleration voltage of 20KV is applied to the above two types of resist films in a pattern with a life of 0.5μ, a space of 1.0μ, and a length of 100μ with a 10μΩ resistance (7).
[MiBK (methyl isobutyl ketone)
A pattern was formed using a developer consisting of a mixed solution of = IPA (Inglovir alcohol) (50:50 volume ratio). When we observed the formed patterns, we found that the mixed resist pattern had no Hapa p-7 flow and a fine pattern of 0.5 μm was formed, but the resist consisting of polytrifluoroimprovyl α-chloroacrylate alone had a much smaller pattern. Pattern flow was observed in the area. Then CF
Dry etching was performed using a 402 (96:4 partial pressure ratio) mixed gas using the above mixed resist pattern as a mask, and when the resist was removed with oxygen plasma, the resist pattern was clearly transferred onto the silicon substrate. was confirmed.

As detailed above, by using a resin made of a mixture of specific radiation-decomposable polymers (FC), it is possible to form a fine resist pattern with good adhesion to the substrate with a small amount of radiation irradiation. It is possible to provide a highly practical fine pattern forming method that can be effectively used for fine processing of mask substrates and the like.

Claims (1)

[Claims] (1) In a method of forming a fine pattern using radiation such as an electron beam, an X-ray, or an ion particle beam, one or more polymers selected from the group (A) and l selected from the LBJ group are used.
A homopolymer of the monomer represented by the formula (1) or other monomers (AJ group (where R1 is a methyl group or chlorine float, E2 is a -logonated alkyl group) is a mixture with a polymer of fm class or higher. Polymer group C83 consisting of a copolymer with vinyl monomers Polymer group 1 consisting of a polymer (2+ [, AJ group is represented by the general formula (3) (However, [R4ba-CH2CFs, -Ci-1(C)
J3) CB”3, -C(Ci(3)2 CF3,
-CH2CF2CHF2, -CH(OCH3)C1 pseudogroup. ) and the CBJ group is a copolymer group of methyl methacrylate and methacrylic acid.