JPS592040A - Formation of pattern - Google Patents

Abstract

PURPOSE:To form a positive resist pattern with superior sensitivity and dry etching resistance by using a resist material obtd. by introducing alpha,alpha'-dimethylbenzyl groups into a specified (co)polymer. CONSTITUTION:A resist material is made of a (co)polymer having the structure of polystyrene and alpha,alpha'-dimethylbenzyl groups bonded to the aromatic rings, e.g. a polymer represented by formula I or II, or it is composed of a polymer having the structure of polystyrene and a polymer having branched alpha,alpha'-dimethylbenzyl groups. The polymers are used in the form of a copolymer represented by formula III or the like. A positive resist pattern with high sensitivity and superior dry etching resistance is formed by exposing the resist material to high energy radiant light.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to a method for forming turns, and more specifically, for example, by irradiating with low-energy radiation such as an electron beam and performing full development. , a suitable image resist! A method of forming turns on a substrate. This 9-turn forming method can be particularly advantageously used in microfabrication processes for manufacturing semiconductor devices.

(2) Background of the Invention In the field of manufacturing semiconductor devices, high-energy radiation such as electron beams, X-rays, gamma rays, etc., is used as an exposure source to perform microfabrication on the order of submicrometers. Furthermore, various bog-type or negative-type rennost materials are used depending on the type of rennost pattern desired. In particular, for example, acrylic resin-based 4'' di-type resist materials are widely used in this technical field because they have commercial resolution suitable for fine processing of Saramicrons.

It is well known that the method of forming positive cast patterns using different materials takes advantage of the differences in solubility of the materials. For example, in the case of polymethyl methacrylate, which is a typical example of this material, when exposed to an electron beam of approximately 5×1O-5C, 2 or more, the main portion of the polymer in the exposed area, that is, the portion irradiated with the electron beam, is The chain is broken and the molecular efficiency of that part is reduced. If this electron beam irradiated area is developed with a developer such as organic m-fx,
Molecular charge.

Because the solubility of that part during development is high (compared to that of the unirradiated part) due to the decrease in gold, it can be selectively removed.

PRIOR ART AND PROBLEMS The above-mentioned positive resist materials for use with high-energy radiation have an essential drawback of poor dry etching resistance because they are composed of decomposable polymers. Such drawbacks cause deformation or decomposition of the renost material during the plasma etching process, which does not guarantee a satisfactory functioning of C as a resist material. In fact, although there have been no attempts to use polymers with excellent dry etching resistance, this is not preferable because it causes a decrease in sensitivity.

Degradable polymer? No attempt has been made to utilize differences in solubility of polymers to form patterns instead of using polymers to form patterns through cleavage of their main chains. for example,
Mr. Hatada et al. of Osaka University published a paper titled ('Polymer wire resist of polymethacrylic cut ester containing phenyl group in -ester group') (Poly + ner P
reprlnte, Japan +Vol-30,
A2, page 423). According to their paper, polymers such as polyα2α'-tumethyl R-endyl methacrylate can be highly sensitive electron beam renosts. The reason why high sensitivity is obtained is that methacrylic acid units are generated in the polymer by electron beam irradiation, which makes it easier to dissolve in alkaline solutions, in other words, it becomes possible to develop with alkali. it is conceivable that.

However, this type of polymer also has the essential drawback of poor dry etching resistance, making it impractical, just like the decomposable polymer described above.

(4) Purpose of the Invention The present invention is a pattern forming method using high-energy radiation exposure, which is an improved method that not only provides high sensitivity but also guarantees good dry etching resistance. The purpose is to provide a pattern forming method.

(5) Structure of the Invention In order to achieve all of the above objectives, the present inventors conducted research in the direction of completely improving the pattern forming method of Mr. Hatada et al.
It has been found that it is effective to introduce α,α'-nomethyl pen/nor groups into certain polymers or co-J remers.

That is, according to the present invention, a polymer or copolymer having a polystereno structure and having α, α in its aromatic ring.
When a pattern is formed using a resist material containing a copolymer of a polymer having a polystyrene structure and a polymer having an α,α′-tumethylpennol group in the side chain, , all intended objectives can be achieved.

When carrying out the entire invention, as mentioned above, i) a polymer or copolymer having a polystyrene structure in which an α,α'-tumethyl group is bonded to its aromatic ring; or 11) a polystyrene α in the polymer and side chain that make up the structure,
It is essential to use a copolymer with a polymer containing α'-tumeterpendyl groups as the renost material.

When such a Rennost material is fully irradiated with sieve energy radiation, -COOH groups are generated in the polymer in the irradiated area, and this area becomes alkali-soluble. Therefore, it becomes possible to completely dissolve and remove this portion by subsequent alkaline development and form a positive type renost lean on the substrate.

In addition to poly(α,α'-tumethylbenzyl p-vinyl penzoate) represented by the following formula, the fJ polymer useful as the Renost material in the present invention is (excluding p-position substitution) OH3 Nawate It includes polymers and copolymers such as.

As used herein, the term "high-energy radiation" refers to various forms of radiation, such as electron beams, X-rays, gamma rays, etc., as generally recognized in the art. Therefore, although the invention will be described below with particular reference to electron beam exposure, it should be understood that the invention is also useful with other radiation, such as, for example, X-rays.

When performing nine-turn formation in accordance with the present invention, a Renost solution is prepared from a polymer or copolymer as described above and applied onto the substrate to be etched.

Here, methyl cellosolve acetate, ethyl cellosolve acetate,
Pentoxone, etc., as a substrate, silicon weno,
Chrome-plated glass, etc. is coated using the spin code method, and the preferred coating thickness is approximately 0.1.
~2 μm'g, respectively.

After forming the resist film, two exposures of the image pattern are performed using a commonly used electron beam exposure apparatus. In the exposed area, -COOH groups are generated as a result of electron beam irradiation, and the Renost film thus becomes soluble in alkali.

Subsequently, the exposed Lenost film is developed with a suitable alkaline developer. Useful developing solutions include, for example, potassium hydroxide, tetramethylammonium idrooxide [N+(CH5-40H]), choline [)1OcH
Examples include water dissolution of 2cH2N+(CH3)OH3. By this development, it is possible to dissolve and remove the exposed portions which have become alkali-soluble in the previous exposure step, thereby obtaining a porcyst/mother turn corresponding to the exposed image pattern.

(6) Examples of the invention Next, the present invention will be illustrated by the following examples.

Example 1: A 15-fold jIt-MCA solution was obtained by dissolving poly(α,α'-trimethylbenzyl p-vinylbenzoate) (methyl cellosolve acetate) (MeA). This Bots-Rennost solution was spin-coded onto a 7-licon wafer with a film thickness of l tim. Subsequently, JEOL JBX-5A
An image is created using a type electron beam exposure system at a voltage of 20 kV. Exposed turn. After exposure, alkaline development was performed for 180 seconds with a 5-tripotassium hydroxide aqueous solution.
A bottom-shaped resist with a sensitivity of 7cm2 or more was obtained.The dry etching resistance of this Renost P-turn was evaluated by reactive ion etching using CHF3.
It was almost the same level as that of polystyrene.

(7) Effects of the invention According to the invention, sensitivity and dry etching resistance II
It can be easily formed by an excellent Bornostone E-turn all-alkaline development. Therefore, the present invention can be advantageously used to form nine fine turns by high-energy radiation exposure.

Claims (1)

[Scope of Claims] 1. A polymer or copolymer having a polystyrene structure in which an α, α′-trimethylbenzyl group is bonded to its aromatic group, or a polymer spanning a polystyrene structure and having α in the side chain A method for forming a pattern, characterized in that it uses a renost material consisting of a copolymer with a polymer having α'-trimethylpennol groups. 2. The method for forming seven turns according to claim 1, wherein the polymer as the renost material is represented by the following formula. 3. The mother turn forming method according to claim 1, wherein the polymer as the renost material is represented by the following formula. H5 4, the method for forming a round turn according to claim 1, wherein the copolymer as the Renost material is represented by the following formula: