JPS62177005A - Styrene polymer containing silicon atom and pattern formation therewith - Google Patents

Abstract

PURPOSE:To provide a styrene polymer containing two silicon atoms per structural unit, highly resistant to dry etching as a resist material, useful for fine pattern formation in the double resist process. CONSTITUTION:For example, p-chlorostyrene is made to react with a compound of formula I (R1-R5 are each lower alkyl or H) followed by reaction with azobisisobutyronitrile to obtain the objective styrene polymer of formula II (n is positive integer). USE:A base plate on which an organic polymer layer is formed, is provided thereon with a resist layer consisting of the styrene polymer of the formula II followed by forming a negative pattern on said resist layer by X-ray, electron beam or ultraviolet light, said organic polymer layer being subjected to dry etching with said negative pattern as a mask, thus forming a fine pattern.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a styrenic polymer containing silicon atoms and a pattern forming method.

Recently, a two-layer resist method has been proposed as a fine pattern forming method suitable for manufacturing semiconductor integrated circuits, magnetic bubble memories, and the like. In this method, after forming an organic polymer layer on a substrate, a silicon-containing resist layer is provided thereon, and then exposure, development, and transfer are performed to form a fine pattern. Currently, silicon-containing resists suitable for this two-layer resist method are being actively developed.

Trimethylsilylstyrene or its copolymer has been proposed as a silicon-containing resist sensitive to X-rays, electron beams, or ultraviolet light (for example, Japanese Patent Application No. 12386/1986).
5).

[Problem that the invention seeks to solve]

However, the dry etching resistance of these conventional resist materials is not necessarily satisfactory. In general, if the dry etching resistance is insufficient, problems such as: - etching conditions during pattern transfer are restricted, - etching time becomes longer, and - the mask pattern is not transferred accurately, resulting in so-called pattern conversion differences. .

=\-1 An object of the present invention is to provide a styrene-based polymer containing silicon atoms that is highly resistant to dry etching and can be used as a resist material.

Another object of the present invention is to provide a method for forming fine patterns using a double resist method.

[Means for solving problems]

The styrenic polymer containing silicon atoms of the first invention is:
It is represented by the following general formula.

Further, in the pattern forming method of the second invention, after providing a resist layer made of a styrene polymer containing silicon atoms represented by the following general formula on a substrate on which an organic polymer layer is formed,
A negative pattern is formed on a resist layer using a beam, an electron beam, or an ultraviolet ray, and the organic polymer layer is dry-etched using the negative pattern as a mask to form a fine pattern.

(In the formula, n represents a positive integer, R1,, R2゜R3,
R4 and R5 represent a lower alkyl group or a hydrogen atom. ) [Function] Since the styrenic polymer containing silicon atoms according to the present invention (hereinafter simply referred to as styrene polymer) contains two silicon atoms per constituent unit, the silicon content in the polymer is low. becomes very large. On the other hand, in dry etching using oxygen, the etching resistance and the silicon content in the material to be etched are strongly correlated, and the higher the silicon content, the stronger the etching resistance.

Owing to their high silicon content, the styrenic polymers according to the invention exhibit very good dry etching resistance. As a result, the above-mentioned etching problem can be reduced.

The styrenic polymer according to the present invention is synthesized using the following reaction formula.

+ tar R, 几.

R2Rs (where n represents a positive integer, R+,, R2°R3,
几4. R5 represents a lower alkyl group or a hydrogen atom. ) After irradiating the styrenic polymer film synthesized in this way with X-rays, electron beams, or ultraviolet rays, it is possible to leave only the irradiated portions by developing them with an appropriate organic solvent.
The styrenic polymer according to the present invention can be used as a so-called negative resist.

Therefore, by using a pattern formed with this negative resist as a mask, a fine pattern can be transferred to the organic polymer layer.

〔Example〕

Next, the present invention will be explained in detail.

First, an example of the method for synthesizing the styrenic polymer of the first invention will be explained.

It was synthesized by the following method using an example of a monomer that forms a styrenic polymer.

After purging the inside of the flask with dry nitrogen gas, 1.5 f (0.06 gram atoms) of Grignard magnesium and 7 g of dry Tet """ l:, o 7 U' (hereinafter referred to as THF) were added.
10mA! I prepared it. After adding a small amount of ethyl bromide, a solution consisting of 8f (0.06 mol) of P-chlorostyrene and 50 rrl of dry THF was added dropwise to react.

Next, while maintaining the temperature at about 50°C, 9f (o, osmol) of chlorbentamethyldisylmethylene and 15m of dry THF were added.
1 solution was added dropwise to react. After the dropwise addition, the mixture was stirred at room temperature for about 1 hour. Next, ether extraction was performed after adding 100 ml of water, and the ether layer was dried with magnesium sulfate. After removing the ether, the product was obtained by vacuum distillation. Yield: 5.2t (yield: 42%), boiling point: 104℃/
2 mH9.

Next, styrene polymer monomer 5. synthesized by the method described above. Of, 30 my of asobisisobutylnitrile (hereinafter referred to as AIBN), and 5 ml of benzene were charged, and after degassing, a polymerization reaction was carried out at 70° C. for 19 hours.

After the reaction, a white solid was obtained by pouring the reaction solution into methyl alcohol. This polymer was fractionated and purified by a conventional method using a solution of methyl ethyl ketone and methyl alcohol. The yield was 1.5y (yield 3o%). The weight average molecular weight determined by gel permeation chromatography is approximately 26,000, and the polydispersity is approximately 1.
．． It was 3. In addition, the nuclear magnetic resonance spectrum (δ) ppm of this polymer is 0 (11H, methyl group and methylene group), 0.3 (6H, methyl group), 1.0 to 2.0 (
3H, methylene group), 6.2-7.3C4H, benzene ring).

The polymer lf synthesized in this way was heated in xylene at 10 mA.
! A resist solution was prepared by dissolving the resist solution, and a 0.2 μm thick polymer layer was formed on a Si substrate by spin coating. After irradiation with approximately 200 .mu.c7 cm.sup.2 using an electron beam exposure device, the sample was immersed in a developer consisting of THF and ethyl alcohol for 1 minute, and then in isopropyl alcohol for 1 minute.

As a result, a negative pattern with almost no film loss was obtained on the Si substrate.

Next, an embodiment of the pattern forming method of the second invention will be described.

A novolac resin layer was formed on a Si substrate by spin coating, and heat treated at 250° C. for 1 hour.

At this time, the thickness of the novolac resin layer was about 1.5 μm.

Next, on this novolac resin layer, a resist layer having a thickness of about 0.2 μm was formed using a resist solution prepared by dissolving styrene polymer 1F in 10 mJ of xylene. After exposure using an electron beam exposure device, THF
A submicron negative pattern was obtained by immersing it in a developer consisting of ethyl alcohol and isopropyl alcohol.

Further, using this negative pattern as a mask and using a reactive ion etching device, an oxygen flow rate of 58CCM%-1be2, QPa,o was obtained. Etching was performed for 7 minutes under the condition of 16 W/-.

As a result, it was confirmed by a scanning electron microscope that the submicron pattern made of the resist layer was accurately transferred to the underlying novolac resin layer. Similarly, fine patterns were also obtained using X-ray exposure, ultraviolet exposure, and the like.

〔Effect of the invention〕

As explained above, the silicon atom-containing styrenic polymer of the present invention has a large silicon content, so it can be used as a resist with strong dry etching resistance.

Furthermore, the negative pattern obtained by exposing and developing this styrene-based polymer film has sufficient resistance as a mask when etching a thick organic polymer layer by dry etching. This has the effect that transfer can be performed with high precision.

Claims (2)

[Claims] (1) General formula: ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, n represents a positive integer, R_1, R_2, R_
3, R_4 and R_5 represent a lower alkyl group or a hydrogen atom. ) A styrenic polymer containing silicon atoms. (2) On the substrate on which the organic polymer layer is formed, there are general formulas: ▲mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, n represents a positive integer, R_1, R_2, R_
3, R_4 and R_5 represent a lower alkyl group or a hydrogen atom. ) After providing a resist layer made of a styrene polymer containing silicon atoms, a negative pattern is formed on the resist layer using X-rays, electron beams, or ultraviolet rays,
A pattern forming method comprising dry etching the organic polymer layer using the negative pattern as a mask to form a fine pattern.