JPS627127A - Pattern formation - Google Patents

Abstract

PURPOSE:To delay the melting speed of the resist film and to widen the allowable range of the development by a method wherein the layer to be etched of a substrate is coated with a specified resist film and irradiated with electron beam to draw a desired pattern and then undergoes the developing process with developing liquid containing ester acetate to be patterned. CONSTITUTION:One surface of a glass substrate is coated with a chrome film that is a layer to be etched to form a photomask blank. Then, the chrome film is coated with a resist film shown by the formula, and the photomask blank with the resist is irradiated with electron beam to draw a pattern. The photomask blank having the irradiated resist film is dipped into an ester solution to develop the resist film, and the position of the electron beam irradiation is molted to form a resist pattern. Thus, the developing solution that delays the melting speed of the resist film is used to improve reproductivity.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for forming a pattern on a resist film provided on a substrate such as a photomask blank or a semiconductor substrate, and on a layer to be etched on the substrate, and in particular to a method for forming a pattern on a resist film provided on a substrate such as a photomask blank or a semiconductor substrate, and in particular on a method for forming a pattern on a layer to be etched on the substrate. The present invention relates to a pattern forming method suitable for a drawing method.

[Conventional technology]

Conventionally, as this type of pattern forming method, there have been, for example, the following methods.

First, a photomask blank was prepared by coating a glass substrate made of quartz glass with a Cr film (layer to be etched), which is a light-shielding thin film. A type of electron beam resist, EBR-9 manufactured by Toshi Co., Ltd., was applied onto the Cr film by a spin code method to form a resist film, and then prebaked, and then the resist film was irradiated with an electron beam. Then, the desired pattern was drawn. Next, a developing solution containing methyl isobutyl ketone as a good solvent and isopropyl alcohol as a poor solvent in a weight ratio of 7:3 was used.
The resist film after drawing was developed by a spray method to form a desired resist pattern (for example, a resist pattern with a width of 0.5 μm). Note that both good and poor solvents are used to dissolve the resist film, but the good solvent has a faster dissolution rate than the poor solvent, and the poor solvent is used to adjust the dissolution rate of the good solvent to an appropriate level. This is to prevent the resist film from swelling during development.

Next, the resist pattern is post-baked, and using this resist pattern as a mask, the Cr1l is etched by dry etching, etc., and the resist pattern is peeled off using oxygen plasma to form a C" pattern (pattern of the layer to be etched). A photomask was prepared.

That is, conventionally, when forming a pattern using a positive electron beam resist, a ketone liquid such as methyl isobutyl ketone or methyl isoamyl ketone has been used as a good solvent for a developer.

[Problem that the invention seeks to solve]

However, this ketone-based good solvent has good selectivity between the irradiated and unirradiated areas of a positive electron beam resist, that is, it can form a clear pattern, but it does not dissolve the resist film. Because the reaction is very slow, the above-mentioned 0 and 5
The permissible range of development time for forming a micron resist pattern with a μm width has the drawback that it must be controlled within a very narrow range of ±5 seconds at the time of setting. A resist pattern could not be formed.

Increasing the amount of poor solvent has been considered as a means of widening the above-mentioned tolerance range, but this would distort the shape of the created resist pattern and make it impossible to obtain a submicron resist pattern. There was a drawback. It is also possible to lower the temperature of the developing solution mentioned above and develop with strict temperature control.
According to this method, workability is significantly deteriorated and a desired bumimicron pattern cannot be obtained due to a slight temperature change.

Therefore, conventional methods have a submicron
Since a cyst pattern cannot be obtained, there is also the drawback that a submicron pattern of the layer to be etched cannot be obtained.

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to provide a method capable of forming a Nabumiku O pattern with good reproducibility and good workability using an electron beam resist. It is.

[Means for solving problems]

The first invention is based on the following general formula: A resist film represented by F, (a halogenated alkyl group substituted with at least one of 4 and Br, n is an integer) is coated on the layer to be etched of the substrate, and the A desired pattern is drawn by irradiating the resist film with an electron beam, and the drawn resist film is developed with a developer containing C113COOR2 (however, R2 is an alkyl group) to form the resist pattern. The second invention is a pattern forming method characterized by forming the following general formula I: (wherein X is any one of C113, (4', Br and F, and R1 is an alkyl group having 1 to 4 carbon atoms, or a halogenated alkyl group in which the hydrogen of the alkyl group is substituted with at least one of F, (4, and Br).

n is an integer. ) is coated on the etched layer F of the substrate, the resist film is irradiated with an electron beam to draw a desired pattern, and the drawn resist film is coated with CH3COOR2 (however, R2 is an alkyl group) to form a resist pattern, the layer to be etched is etched using the resist pattern as a mask, the resist pattern is removed, and the layer to be etched is etched. This is a pattern forming method characterized by forming a pattern.

The substrate is a glass substrate such as aluminosilicate glass, aluminoborosilicate glass, or quartz glass, and is coated with transition metal elements such as chromium, tantalum, molybdenum, nickel, and titanium, Si and Ge, or alloys thereof. I
Not only photomask blanks with a light-shielding film, which is a layer to be etched, made of a material with a composition that is continuously changed in the film thickness direction, but also semiconductor substrates (e.g., silicon wafers, etc.) can be used. It also includes a substrate as a layer to be etched or a semiconductor substrate in which a Si 02 film or the like is provided as a layer to be etched.

Furthermore, as the acetate ester C113COOR2, methyl acetate CH3COOCH3, ethyl acetate C
ll3 Coo C2+15, isopropyl acetate C
113COOC3117, butyl acetate C) 13 CO
OC4) 1g, isoamyl acetate C113COOc5N1
1 etc.

[For production]

The present invention provides the resist film of the general formula I with the general formula I
By using a 1-acid ester as a developer, the dissolution rate of the resist film can be slowed down, that is, the allowable range of development time can be widened.

〔Example〕

An embodiment of the pattern forming method according to the present invention will be described in detail below.

First, a layer to be etched, chromium F1 < film thickness: (approximately 700 people) to produce photomask blanks. Next, ERR-9 manufactured by Toshi, which is a positive electron beam resist having the chemical structural formula shown by the above formula (II), is dropped onto the chrome crotch, and a resist film (thickness: Approximately 4,000 people applied the drug. Next, the photomask blank with the resist film is placed in a clean open, and the resist film is coated for about 20 minutes.
Brebake is performed at 0° C. for 30 minutes, and then an electron beam is irradiated onto the resist film using an electron beam drawing device to draw a pattern in order to obtain a resist pattern with a line width of 0.5 μm, which will be described later. Next, the photomask blank having the irradiated resist film is placed in an acetate ester (for example, isoamyl acetate C113C (10C5Hll) solution (liquid temperature: 2
The resist film was developed by immersing it in a 20° C. temperature (2±2° C.) for 20 minutes, and the portion irradiated with an electron beam was dissolved to form a resist pattern.

A resist pattern (desired line width standard: 0.5 μm ± 0.1 μm) formed by the above method is used.
A resist pattern is formed by developing a photomask blank and a conventional developer for a set time using a cleaning method (desired line width specifications are the same as the above specifications).
Comparing each resist pattern with 10 photomask blanks having
In this example, as many as 9 pieces were made into good quality, whereas only 9 pieces were made into good quality. This is because the present example uses a developer that slows down the rate of dissolution of the resist film, resulting in better reproducibility than in the conventional method.

Next, the resist pattern is boss-baked, and then, using the resist pattern as a mask, the chromium film (layer to be etched) not covered by the resist pattern is sprayed with a mixed solution of ceric ammonium nitrate and perchloric acid. Etching was carried out for 25 seconds, and then the resist pattern was removed using 02 gas plasma to create a photomask provided with a chrome pattern (pattern of the layer to be etched).

According to this example, since a developer with a slow dissolution rate of the resist film is used, a fine resist pattern can be manufactured with good reproducibility. Temperature variations can be calculated from room temperature (
Since the resist film can be developed at about ±2°C (20 to 25°C), workability is also improved. Furthermore, since the resist pattern can be created with good reproducibility, the pattern of the layer to be etched can also be created with good workability and good reproducibility.

As described above, in the above embodiments, the resist film is (I[]
(However, n is an integer) Electron beam resists having the structural formula of the above formula (I [I) or (IV)] were used. That's fine. That is, the general formula (
X in I) is any one of C113, (4, Br, and F (7), and R1 is an alkyl group having 1 to 4 carbon atoms, or the hydrogen of this alkyl group is one of F, C1, and Br. Any halogenated alkyl group substituted with at least one of them may be used.

In addition, in the above example, only isoamyl acetate was used as the developer, but this is because acetic acid esters such as isoamyl acetate have the characteristics of a good solvent as well as the characteristics of a poor solvent for the resist of the example above. This is because it prevents the resist film from swelling. However, when using other resists or when dissolving the resist at an appropriate rate, acetic ester may be used as a good solvent, and isopropyl alcohol or an acetic ester other than the acetic ester used as a good solvent may be used as a poor solvent. . In order to etch the layer to be etched, a mixed solution of ceric ammonium nitrate and perchloric acid was used. Etching may be performed, or a dry etching method may be used.

〔Effect of the invention〕

As described above, according to the present invention, fine patterns, that is, submicron resist patterns and patterns of the layer to be etched can be manufactured with good reproducibility and good workability. Furthermore, there is an advantage that there is no need to provide the developing device with a mechanism that strictly limits the temperature of the developer.

Claims (2)

[Claims] (1) The following general formula I: ▲There are mathematical formulas, chemical formulas, tables, etc.▼... [I] (However, X is any one of CH_3, Cl, Br, and F, and R_1 is a carbon atom 1 to 4 alkyl groups or a halogenated alkyl group in which hydrogen of the alkyl group is substituted with at least one of F, Cl, and Br; n is an integer). of,
The layer to be etched on the substrate is coated, the resist film is irradiated with an electron beam to draw a desired pattern, and the drawn resist film is coated with CH_3COOR_2 (however, R_2
is an alkyl group. ) A pattern forming method comprising forming a resist pattern by developing with a developer containing: (2) General formula I below: ▲There are mathematical formulas, chemical formulas, tables, etc.▼...[I] (However, X is any one of CH_3, Cl, Br, and F, and R_1 is a carbon atom 1 to 4 alkyl groups or a halogenated alkyl group in which hydrogen of the alkyl group is substituted with at least one of F, Cl, and Br; n is an integer). of,
The layer to be etched on the substrate is coated, the resist film is irradiated with an electron beam to draw a desired pattern, and the drawn resist film is coated with CH_3COOR_2 (however, R_2
is an alkyl group. ) to form a resist pattern, etching the layer to be etched using the resist pattern as a mask, and removing the resist pattern to form a pattern of the layer to be etched. Characteristic pattern formation method.