JPH0212244B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of forming a fluoroalkyl acrylate polymer coating on a substrate, and more particularly to a method of forming a resist coating.

The inventors have previously shown that fluoroalkyl acrylates can be formed by glow discharge to form a film of the polymer on a substrate, and by writing a pattern on this film with high-energy radiation and further development. He discovered that it was possible to form fine resist patterns and filed a patent application (Japanese Patent Application No. 142198-1982).

In other words, (1) (a) The inert gas excited by the glow discharge causes (b) Formula: R _f R ² OCOCR ¹ = CH ₂ (where R _f is a straight line with 1 to 15 carbon atoms). A chain or branched perfluoroalkyl group or a group in which one or more fluorine atoms are substituted with a hydrogen atom and has at least one fluorine atom, R ¹ is a hydrogen atom, a methyl group, an ethyl group, or (a halogen atom and R ² represent divalent hydrocarbon residues) and (c) a substrate characterized by polymerizing a polymerizable substance other than (b) as required. A method of forming a polymer coating of a homopolymer or copolymer of alkyl acrylate or a mixture of a homopolymer of fluoroalkyl acrylate and a homopolymer of another polymerizable substance, and (2)(A)(a) (b) Formula: R _f R ² OCOCR ¹ = OH ₂ (where R _f is a linear or branched perfluorinated chain having 1 to 15 carbon atoms). an alkyl group or a group in which one or more fluorine atoms thereof are substituted with a hydrogen atom and has at least one fluorine atom; R ¹ is a hydrogen atom, a methyl group, an ethyl group, or a halogen atom;
R ² represents a divalent hydrocarbon residue. ) and (c) polymerizable substances other than (b) if necessary to form a polymer film on the substrate, and (B) then irradiate the film with high energy rays. This is a method for producing a substrate having a resist pattern coating, which is characterized by drawing a latent image pattern and (C) finally developing it.

In this method, in a 0.5 μm resist film,
Although a pattern can be formed with an irradiation dose of 50 to 250 μC/cm ² and good sensitivity is obtained, it is still insufficient.

An object of the present invention is to obtain a resist film made of a fluoroalkyl acrylate polymer produced by glow discharge polymerization and having even better sensitivity.

That is, in the present invention, by an inert gas excited by glow discharge, (a) formula: R _f R ² OCOCR ¹ =OH ₂ (wherein, R _f is a linear chain having 1 to 15 carbon atoms or A branched perfluoroalkyl group or a group in which one or more fluorine atoms are replaced with a hydrogen atom and has at least one fluorine atom,
R ¹ represents a hydrogen atom, a methyl group, an ethyl group, or a halogen atom, and R ² represents a divalent hydrocarbon residue. ) Forming a film of a polymer of fluoroalkyl acrylate on a substrate characterized by polymerizing a fluoroalkyl acrylate represented by (b) and (c) tetramethyltin, if necessary, a polymerizable substance other than (a). Regarding how to. A latent image pattern is drawn on the film obtained by the present invention by irradiating it with high-energy rays, and if necessary, it is finally developed to produce a substrate having a resist pattern film.

According to the present invention, an irradiation dose of about 2μC/ ^cm2
A pattern can be formed on a resist film having a film thickness of 0.2 μm.

The excited inert gas in the present invention has a temperature of 0 to 200°C and a pressure of 10 to 10 ^-4 Torr, preferably 1 to 10 -4 Torr.
Obtained by passing an inert gas through the glow discharge area at 10 ^-2 Torr. The flow rate of the inert gas is, for example, 0.1 to 200 cm ³ STP/min in the container 1, preferably 10 to 200 cm ³ STP/min, and the glow discharge is performed under a high frequency electric field of 0.1 to 100 MHz at 1 to 500 W, especially 5 to 50 W. It is preferable to use a discharge power of .
Incidentally, the glow leaving is carried out by providing two parallel plate electrodes inside the reaction tube and applying a high frequency voltage, or by providing an induction coil outside the reaction tube and applying a high frequency current.

The inert gas can be helium, neon, argon, krypton, xenon, preferably argon and krypton.

The fluoroalkyl acrylate used in the present invention is represented by the above formula. R _f
The group has 1 to 15 carbon atoms, preferably 1 to 10 carbon atoms, and has at least 1 fluorine atom, preferably the sum of the number of carbon atoms in the R _f group and the number of carbon atoms in the R ² group. At least 1/2. R ² is for connecting the acrylate group or methacrylate group to the R _f group, and the number of carbon atoms is 1 to 10,
Among them, 1 to 5 are preferable, but not critical. Preferred fluoroalkyl acrylates have boiling points below 400°C at atmospheric pressure or 70°C at 40 Torr.
℃ or below.

Examples of the fluoroalkyl acrylates used in the present invention are: CH ₂ =C(CH ₃ )COOCH ₂ (CF ₂ ) ₂ H CH ₂ =C(CH ₃ )COOC(CH ₃ ) ₂ (CF ₂ ) ₂ H CH ₂ ＝C(CH ₃ )COOCH ₂ CHFCF ₃ CH ₂ ＝C(CH ₃ )COOCH ₂ CF ₂ CHFCF ₃ CH ₂ ＝C(CH ₃ )COOCH(CH ₃ )CF ₂ CHFCF ₃ CH ₂ ＝C(CH ₃ )COOCH (C ₂ H ₃ )CF ₂ CHFCF ₃ CH ₂ =C(CH ₃ )COOCH(C ₃ H ₇ )CF ₂ CHFCF ₃ CH ₂ =C(CH _{3 )COOC(CH 3 ) 2} CF ₂ CHFCF ₃ CH ₂ = _C ( _CH3 )COOC( _CH3 )( _C2H5 ) _CF2CHFCF3CH2 =C( _CH3 ) _COOCH2 ( _CF2CF2 ) _o Hn _is 2 _to 5 _{CH2 =} C( _CH3 ) COOC (CH ₃ ) ₂ (CF ₂ CF ₂ ) _o H n is 2 to 5 CH ₂ = C (CH ₃ ) COOC (CH ₃ ) ₂ CF ₂ CH (CF ₃ ) ₂ CH ₂ = C (CH ₃ ) COOCH ₂ CH ₂ (CF ₂ CF ₂ ) _o CF (CF ₃ ) ₂ n is 1 to 5, CH ₂ =C(CH ₃ ) COOCH ₂ CH ₂ (CF ₂ ) _o F n is 1 to 10, and the like.

In the present invention, such fluoroalkyl acrylate is preferably supplied at a rate of 0.5 to 50%, particularly 1 to 20%, of the inert gas flow rate.

The polymerizable substance other than (a) used as necessary in the present invention is a vinyl monomer having a double bond.

Examples of the vinyl monomer include ethylenically unsaturated olefins such as ethylene, propylene, butylene, isobutylene, and butadiene; styrenes such as styrene, α-methylstyrene, and p-chlorostyrene; acrylic acid, methacrylic acid, Unsaturated carboxylic acids such as itaconic acid, maleic acid, maleic anhydride; methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, dodecyl acrylate, n-octyl acrylate, 2-chloro-acrylate Esters of α-methylene aliphatic monocarboxylic acids such as ethyl, phenyl acrylate, methyl α-chloroacrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, and ethyl α-ethyl acrylate; vinyl methyl ether, vinyl Vinyl ethers such as ethyl ether and vinyl isobutyl ether; Vinyl esters such as vinyl chloride, vinyl acetate, vinyl propionate, vinyl butyrate, and vinyl benzoate; 1-methyl-1'-methoxyethylene, 1,1'-dimethoxyethylene ,
Ethylene derivatives such as 1,2-dimethoxyethylene, 1,1'-dimethoxycarbonylethylene, 1-methyl-1'-nitroethylene; N-vinylpyrrole, N-vinylcarbazole, N-vinylindole, N-vinylpyrrolidine, N-vinyl compounds such as N-vinylpyrrolidone; other acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, α-ethyl acrylamide, acrylanilide, p-chloroacrylanilide, m-nitroacrylanilide, m-methoxyacrylanilide, vinylidene Examples include chloride and vinylidencyanide.

The proportion of such vinyl monomer is preferably 30 mol% or less of the total amount with fluoroalkyl acrylate.

A known method can be employed for producing the fluoroalkyl acrylate.

For example, it can be obtained by reacting a fluoroalcohol with acrylic acid or methacrylic acid or a derivative thereof.

CH ₂ = CR ¹ COOH + R _f R ² OH → CH ₂ = CR ¹ COOR ² R _f +H ₂ O (In the formula, R ¹ , R ² and R _f are the same as above.) Specifically, for example, methacrylic acid chloride 2,2,3,4,4,4-hexafluorobutyl alcohol is added to the solution, and a small amount of a polymerization inhibitor such as hydroquinone dimethyl ether is added.
Heat to 60-120℃, 2, 2, 3, 4, 4, 4
- Hexafluorobutyl methacrylate can be produced.

The proportion of tetramethyltin is 0.1 to 20 mol% relative to fluoroalkyl acrylate, among others
0.5-10 mol% is preferred.

The substrate used in the present invention is not limited, and includes, for example, a salt crystal, a glass plate with a chromium mask, a semiconductor film such as silicon or germanium, a conductor film such as chromium, aluminum, titanium, or gold, silicon oxide, silicon nitride, Examples include insulating films such as phosphorus silicon glass, arsenic silicide glass, and boron silicide glass. Such a substrate is placed within the discharge zone or downstream of the discharge zone.

To carry out the invention, for example, the apparatus shown in FIG. 1 is used. Glow discharge is generated by supplying inert gas, fluoroalkyl acrylate, and tetramethyltin while adjusting the pressure to a predetermined level using a vacuum pump, and applying a high-frequency voltage to the board by placing or mounting it on a horizontal or vertical material installation stand. When this is done, a coating of fluoroalkyl acrylate polymer is formed on the substrate.

The polymer film thus formed is prebaked together with the substrate at 70 to 200°C, if necessary.

The substrate on which the polymer film has been formed can be irradiated with high energy beams such as electron beams, , a film having a fine resist pattern can be formed on a substrate.

For development, if drawing is done by electron beam irradiation, electron beam irradiation alone may be sufficient in some cases when the thickness of the resist film is small. In the case of development, electron beam irradiation can be kept small, which is preferable.

Furthermore, this development can also be carried out by dissolving the electron beam or X-ray irradiated area with a commonly used solvent.

In oxygen plasma etching, the gas pressure is 1 to 500
mTorr, at a temperature of 0 to 100°C, in a glow discharge area, for example, a polymer coating with a latent image on the substrate is placed on one pole of a parallel plate circular electrode, with insulation if necessary, and oxygen is passed therethrough. .

Oxygen is best mixed with an inert gas such as Ar, and the O ₂ concentration in the Ar−O ₂ gas mixture is
10 to 20 mol % is good, and the mixed gas is usually passed through at 10 to 100 cm ³ STP/min for a container volume of 3. The discharge power is preferably 0.2 to 2 W per 1 cm ³ of interelectrode volume.

Development by heating is from 1 to 10 ^-5 torr, preferably
Temperature that does not cause thermal decomposition above the glass transition point of the polymer under reduced pressure of 10 ^-2 to 10 ^-3 Torr, generally 80 to 250
It is best to do this at ℃.

Hydrogen or inert gas plasma etching
A polymer coating formed on a substrate in a hydrogen or inert gas plasma maintained at a temperature of 0 to 100° C. at a gas pressure of ^{10 −1} to 10 ⁻⁵ Torr, preferably 10 ⁻² to ^{10 −4} Torr. This can be done by placing . As the inert gas, for example, argon, helium, nitrogen, etc. can be used. Specifically, a substrate on which a polymer coating is formed is placed on one plate of the parallel electrodes so that the polymer coating faces the other plate. If necessary, the substrate and the electrode plate may be insulated.
The flow rate of hydrogen or inert gas is usually 3
The discharge power is 0.1 to 10 cm ³ STP/min, and the discharge power is 0.05 to 1 W per 1 cm ³ of interelectrode volume. Further, the discharge time may be appropriately selected according to the above conditions.

The resist pattern film thus formed can be applied to the manufacture of semiconductor devices, magnetic bubble devices, optical application parts, and video disks.

Next, the method of the present invention will be explained in more detail with reference to Reference Examples and Examples, but the present invention is not limited to these Examples.

Reference Example 1 A film of a fluoroalkyl acrylate polymer was formed on a substrate using the plasma polymerization apparatus shown in FIG.

The vacuum vessel 1, which is the main body of the device, has a total volume of 1, the pressure of the vacuum vessel 1 is adjusted to 0.7 Torr by a vacuum pump 11 and a McLeod vacuum gauge 3, and the gas in the vacuum vessel is pumped through a liquid nitrogen trap 10. Exhausted through. Argon from argon container 2 at the tip
Argon was supplied at a rate of 63.5 cm ³ STP/min and excited by passing through a 13.56 MHz glow discharge region generated by the induction coil 4 from the radio wave generator 7 via the wattmeter 6 and the impedance adjustment circuit 5. on the other hand,
A mixture of fluoroalkyl acrylate and tetramethyltin is supplied from the container 8 into the vacuum container 1 at a flow rate of 1.6 cm ³ STP/min, and the mixture is combined with the excited argon and cooled with cooling water.
It was brought into contact with an overlying substrate (not shown) and evacuated using a vacuum pump 11.

The conditions for forming the film were as follows.

Fluoroalkyl acrylate 2,2,3,
4,4,4-Hexafluorobutyl methacrylate substrate Chromium-deposited glass plate Surrounding temperature of the apparatus Room temperature gas pressure in the vacuum chamber 0.7 toll glow discharge power 10W Argon flow rate 63.5cm ³ STP/min Fluoroalkyl acrylate flow rate
1.55cm ³ STP/min Tetramethyltin flow rate 0.05cm ³ STP/min Contact time 30 minutes The film thickness was measured with a Taly step. Film thickness is 1.3μ
It was m.

Example 1 Electron beam drawing was performed on a film formed on a chrome plating layer on a glass plate under the same conditions as Reference Example 1.
The amount of decrease in film thickness for various irradiation doses was measured. For electron beam lithography, an electron beam was irradiated at 1 to 2 μC/cm ² at an acceleration voltage of 20 kV and a line and space of 4 μm under 10 ⁻⁵ to 10 ⁻⁶ Torr, and the amount of decrease in film thickness was measured using a Taly step. The results were as follows.

Irradiation dose Reduction in film thickness (μC/cm ² ) (μm) 1 0.04 1.5 0.12 2 0.25 Example 2 A film coated on chrome plating on a glass plate under the same conditions as Reference Example 1 was coated in the same manner as in Example 1. Electron beam irradiation was performed at various irradiation doses. Then 10 ^-3
Heat treatment was carried out at 170° C. for 4 minutes under reduced pressure of ˜10 ⁻⁴ Torr. The results are shown below.

Irradiation dose Total film thickness reduction (μC/cm ² ) (μm) 1 0.08 1.5 0.23 2 0.48 Example 3 A film formed on a chrome plating layer on a glass plate under the same conditions as Reference Example 1 was treated in the same manner as Comparative Example 1. Electron beam irradiation was performed at various irradiation doses. These coatings were then treated with hydrogen plasma. Hydrogen plasma treatment is performed using parallel disk electrodes (diameter 100 mm,
Place the sample with the coating facing upward on the lower electrode plate (with a spacing of 30 mm), and adjust the frequency while flowing hydrogen.
This was done by applying a high frequency voltage of 13.56MHz. The conditions for the hydrogen plasma treatment were as follows.

Discharge power: 100W Hydrogen pressure: 2 mTorr Hydrogen flow rate: 1 to 10 cm ³ STP/min Discharge time: 1 minute The results are shown below.

Irradiation dose Total film thickness reduction (μC/cm ² ) (μm) 1 0.06 1.5 0.21 2 0.45 Reference Example 2 A fluoroalkyl acrylate polymer film was formed on a substrate in the same manner as Reference Example 1.

The conditions for forming the film were as follows.

Fluoroalkyl acrylate 1,1-dimethyl 2,2,3,3-tetrafluoropropyl methacrylate substrate Temperature around the chromium-deposited glass plate device Room temperature Gas pressure inside the vacuum chamber 0.7 Torr Glow discharge power 10W Argon flow rate 63.5cm ³ STP /min Fluoroacrylate 2.3cm ³ STP/min Tetramethyltin flow rate 0.1cm ³ STP/min Contact time 30 minutes Film thickness was measured with Talystep. Film thickness is 1.9μ
It was m.

Example 4 Electron beam drawing was performed on the coating formed on the chrome plating layer on the glass plate under the same conditions as Reference Example 2.
The amount of decrease in film thickness for various irradiation doses was measured. For electron beam lithography, an electron beam of 1 to 2 μC/cm ² was irradiated with a line and space of 4 μm under 10 ⁻⁵ to 10 ⁻⁶ Torr, and the amount of decrease in film thickness was measured using a Talystep. The results were as follows.

Irradiation dose Reduction in film thickness (μC/cm ² ) (μm) 1 0.04 1.5 0.10 2 0.22

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of a plasma polymerization apparatus for carrying out the method of the present invention. (Drawing code), 1: Vacuum vessel, 2: Argon vessel, 3: McLeod vacuum gauge, 4: Induction coil,
5: Impedance adjustment circuit, 6: Power meter, 7:
Radio wave generator, 8: Mixture container of fluoroalkyl acrylate and tetramethyltin, 9: Sample installation stand, 10: Liquid nitrogen trap, 11: Vacuum pump.

Claims (1)

[Claims] 1. (a) Formula: R _f R ² OCOCR ¹ = CH ₂ (wherein, R _f is a linear chain having 1 to 15 carbon atoms). or a branched perfluoroalkyl group, or a group in which one or more fluorine atoms are replaced by a hydrogen atom and has at least one fluorine atom,
R ¹ represents a hydrogen atom, a methyl group, an ethyl group, or a halogen atom, and R ² represents a divalent hydrocarbon residue. ) Forming a film of a polymer of fluoroalkyl acrylate on a substrate characterized by polymerizing a fluoroalkyl acrylate represented by (b) and (c) tetramethyltin, if necessary, a polymerizable substance other than (a). how to.