JPS60196756A - Resist developing solution - Google Patents

Abstract

PURPOSE:To enable a fine resist image to be formed without swelling by incorporating dimethylformamide in a developing soln. for a resist made of a polymer contg. a specified trioxabicyclo compd. as structural units. CONSTITUTION:The developing soln. of a resist contg. as structural units a trioxabicyclo compd. represented by the formula, R being alkyl, incorporates dimethylformamide. This solvent perfectly dissolves the unexposed parts of the resist without leaving the residue, and moreover, it causes extremely small swelling during the development. The swelling can be more suppressed by using a mixture of a poor solvent, such as propylene glycol, with such a soln., thus permitting a resist image good in resolution to be formed and used for semiconductor integrated circuits, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a developer used in a resist image forming method, and more particularly to a developer used in a resist image forming method using electron beams or X-rays. .

[Prior art and its problems]

Traditionally, semiconductor devices have been manufactured using a processing method in which a photosensitive resin (photoresist) is coated on a substrate, exposed and developed to form a fine pattern, and the areas not covered by the resist pattern are wet etched. was used. However, this method has a limited resolution of approximately 1 micron due to light diffraction, and wet etching is affected by side etching and impurities in the etchant, so it is not suitable for microfabrication of 1 micron or less. The problem is that it is not suitable.

Recently, with the demand for higher densification of semiconductor integrated circuits, fine patterns have been formed using radiation such as X-rays and electron beams with shorter wavelengths instead of light, and plasma gas etching has been used instead of wet etching. Methods of forming highly precise fine patterns using dry etching, such as reactive sputtering, ion milling, etc., are becoming less mainstream.

Therefore, the resist used in such a microfabrication method is required to have high sensitivity to radiation and high resistance to plasma gas, reactive slag, and ion milling.

The present inventor has already proposed a resist material containing a trioxabicyclo compound represented by the general formula (where R represents an alkyl group) as a constituent element, and demonstrated that it is possible to form a good resist image with high sensitivity. Ta.

However, compounds containing the above-mentioned trioxabicyclo compounds as constituents are mainly composed of commonly used ketone solutions such as tetrahydrolane, methyl ethyl ketone and methyl isobutyl ketone, and ester solutions such as methyl ethyl acetate and cellosolve acetate. The developing solution containing the resist has the disadvantage that it undergoes severe swelling during development, making it difficult to form a fine resist image. The present invention provides a developer capable of forming a resist image.

[Structure of the invention]

The present inventor investigated various solvents as a developer for a resist material containing a trioxabicyclo compound as a component, and as a result, discovered that a developer containing dimethylformamide was particularly excellent, and thus arrived at the present invention.

That is, the present invention is characterized by containing dimethylformamide in a developer of a resist made of a polymer containing a trioxabicyclo compound represented by the general formula: (wherein R represents an alkyl group) as a constituent element. It will be a developer for the resist.

[Detailed explanation of the configuration]

The developer of the present invention is produced by irradiating a resist made of a polymer containing a trioxabicyclo compound as a component with electron beams, X-rays, etc. to make it insolubilized, and then dissolving and removing the unirradiated portions to form a resist image. It uses a method of forming
It consists of a solution containing dimethylformamide.

After comparing various solvents, we found that dimethylformamide dissolves the unirradiated areas very well without leaving any residue. Moreover, it was found that the swelling during development was extremely small. Therefore, when developed with a solution containing dimethylformamide as a main component, a fine resist image can be formed without leaving any residue. Although dimethylformamide may be used alone, swelling can be further suppressed by mixing with a poor solvent.

Examples of the poor solvent to be mixed include isopropyl alcohol, ethyl alcohol, etc. If necessary, after processing with a developer, rinsing with a poor solvent may be performed. In the developing solution, it is desirable that the amount of dimethylformamide is 20 volumes or more. If it is less than this, the solubility will not be sufficient and the unirradiated portion will not be completely dissolved.

[Explanation of Examples]

The present invention will be explained in detail below.

(Example 1) A homopolymer (average weight molecular weight 100,000, dispersion 2.8) synthesized from a trioxabicyclo compound (R=C,H,) was dissolved in a methylcellosolve acetate solution to give 15% by weight.
A resist solution was prepared. Using this resist solution, apply by spin coating (2000 revolutions/min) to 80%
C. for 30 minutes to obtain a uniform coating film with a thickness of 0.6 microns. Acceleration voltage 20KV.

After forming a latent image by drawing patterns of various dimensions with a radiation dose of 10 μc/cd, it was developed for 90 seconds with a mixed solvent of dimethylformamide and isopropyl alcohol in a ratio of 3:1.

When the obtained resist image was observed, a resist pattern with a width of 0.8 micrometers was formed, showing excellent resolution.

(Reference example) For comparison with the present invention, a conventional example similar to Example 1 was prepared using tetrahydrofuran: isopropyl alcohol 3:
When developed for 90 seconds with a mixed solvent of No. 1, a resist image with a width of 2 μm was formed, but no higher resolution was achieved.

In addition, residues were present in some places.

(Example 2) A homopolymer synthesized from trioxabicyclo compound (R-CHs) (average weight molecular weight 50,001 dispersion 2.4) was dissolved in methyl cellosolve acetate to prepare a resist solution with a specific weight % did. This resist solution was applied by spin coating (6000 rpm) and baked at 80° C. for 30 minutes to obtain a uniform coating film with a thickness of 0.48 microns. After exposure at an accelerating voltage of 20 KV and a dose of 20 μO/d, the film was developed with dimethylformamide for 90 seconds and rinsed with isopropyl alcohol for 30 seconds. As a result of observation, a resist image with a width of 0.6 microns was successfully formed.

(Example 3) Trioxabicyclo compound (R=C*) ω/acrytetraunitryl-60/40 average weight molecular weight 120,000, dispersion 3.
A 10% by weight resist solution was prepared by dissolving the copolymer No. 0 in benzonitrile. Using this resist solution, a coating film of 0.5 microns was formed by spin coating (aooo rotations/min). Acceleration voltage 20KV.

The film was exposed to light at a dose of 12 μe/di, developed with a 1:1 mixed solution of dimethylformamide and isopropyl alcohol for 90 seconds, and then rinsed with isopropyl alcohol for 30 seconds. As a result of observation, a resist image with a width of 0.8 microns was well formed, showing excellent resolution.

〔Effect of the invention〕

As described above, by using the solution of the present invention containing dimethylformamide as a developer for a polymer containing a trioxabicyclo compound as a component, swelling during development can be extremely reduced, and fine particles with good resolution can be obtained. This method has the effect of forming a resist image with a high quality.

Claims (1)

[Claims] (1) A resist developer comprising a trioxabicyclo compound represented by the general formula: (wherein R represents an alkyl group) and dimethylformamide.