JPS5848048A - Resist material for use in far ultraviolet exposure - Google Patents

Abstract

PURPOSE:To obtain a resist material for use in far UV exposure suitable for forming a micropattern, high in sensitivity and superior in dry etching performance, by using a benzyl methacrylate-glycidyl methacrylate copolymer having a specified copolymerization composition. CONSTITUTION:A copolymer composed of 70-50mol% benzyl methacrylate and 30-50mol% glycidyl methacrylate is prepared by copolymerizing such a composition of monomers dissolved in a solvent in the presence of a polymerization initiator. This is applied to a resist material for use in far UV exposure. As an embodiment of this material, it is dissolved in a solvent, coated on a silicon wafer to form a thin resist film, and a prescribed pattern mask is overlaid to expose it to far UV rays, and the part solubilized by exposure is dissolved off with a developing solution.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a resist sensitive to deep ultraviolet rays, and is suitable for forming ultra-fine patterns for semiconductor elements, integrated circuits, and the like.

Conventionally, in the manufacturing process of integrated circuits, mask transfer technology using ultraviolet rays has been used when producing circuit patterns. However, when ultraviolet light is used, the practical limit of resolution is about 2 μm due to diffraction phenomena, and ultra-LS
Even more subtle, such as I.

In manufacturing processes that require fine patterns, transfer technology that uses ultraviolet light is reaching its limits. Therefore, in order to cope with the increasing density of integrated circuits, mask transfer technology that uses far ultraviolet light (wavelength 200-360?Lm), which has less diffraction, is attracting attention1. There is an urgent need to develop a resist sensitive to ultraviolet rays, that is, a resist material Nemi 1 for deep ultraviolet exposure.

Conventionally, resist materials for deep ultraviolet exposure include methyl borimecrylate, polymethylinopropenylctone,
Diazide-based photoresists, which have been used as ultraviolet exposure resists and photoresists, have been studied, but they are insufficient in sensitivity, resolution, and dry etching resistance, and it is difficult to put these resists to practical use. However, various problems remain.

The present invention provides a positive type (solubilized in a developer after exposure to deep ultraviolet rays) far ultraviolet resist material that is highly sensitive and has excellent dry etching properties.
It is made of glycidyl methacrylate copolymer.

An example of a method for forming a resist I pattern using the resist material of the present invention is as follows. The following P (
BzMA-GMA) is dissolved in methyl cellosolve acetate to a concentration of 7 to 10 parts by weight (hereinafter simply expressed as parts) and filtered through a 0.2 μm filter to form a resist. Other solvents that can be used include toluene, xylene, and ethyl cellosolve acetate.

Next, about 5 cc of this resist melt is dropped onto a thermally oxidized silicon wafer, and a resist thin film with a thickness of about 1 μm is formed on the wafer by spin coating.

After heat-treating this substrate, a mask material (a quartz plate with a thin chromium film) having a predetermined pattern is placed on the substrate.
Expose to deep ultraviolet light for several tens to hundreds of seconds. The part exposed to deep ultraviolet rays becomes solubilized by a photoreaction. When this substrate is immersed in a developer, the resist in the exposed areas dissolves faster than in the unexposed areas, and after a certain period of development, only the unexposed areas remain as a pattern on the substrate. .

The substrate on which the resist pattern was formed in this way was
When dry etching was performed using y4 gas,
It was found that it has greater dry etching resistance than conventionally used polymethyl methacrylate.

P (BzMA/HMA) used in the present invention has a copolymerization composition of 30 to 50 mol/benzyl taacrylate.

70 to 60 mol of glycidyl methacrylate is effective. When 82M is less than 30 molti, the dry etching resistance decreases. However, when BzMA exceeds 60 molti, the sensitivity decreases.

It is effective for P (BzMA/GMA) used in the present invention to have a weight average molecular weight (hereinafter abbreviated as Mw) of 10,000 to 1,000,001, preferably 100,000 to 600,000. When Mw is less than 10,000, the properties as a polymer deteriorate,
I couldn't get a resist film with sufficient hardness, and I was disappointed, M.
1y1 million or more, the viscosity of the resist solution increases,
It is difficult to obtain a resist film with a uniform thickness using a spin coating method or the like.

67, -2 Examples of the present invention will be described in detail below.

Example 1 30 parts of BzM purified by vacuum distillation and 70 parts of GM were dissolved in 90 parts of purified benzene, and 0.09 part of azobisisobutyronitrile (hereinafter abbreviated as AIBN) was added as a polymerization initiator. The mixture was then polymerized for 6 hours at 90°C in a sealed tube. After polymerization, it was poured into 20 times the amount of methanol and purified by reprecipitation.

When the molecular weight of the obtained polymer was measured using gel chromatography (hereinafter abbreviated as GPC), it was found to be Mw 29. It was O million. This polymer was dissolved in methyl cellosolve acetate (hereinafter abbreviated as 3M) to make a 10% solution. This was filtered through a 0.2 μm filter and used as a resist solution. This solution was made from thermally oxidized silicon Add a drop onto Ueno®2 and use the spin coating method to coat 1μ
A resist film with a thickness of m was formed. This substrate was heat-treated at 120° C. for 30 minutes to form a sample.

Example 2 Same as Example 1, 60 parts of BzMA, 50 parts of HMA, 6, -
2. was dissolved in 90 parts of benzene, 3 parts of AIB No. 0 was added as a polymerization initiator, and the mixture was polymerized in a sealed tube at 90°C for 6 hours. After polymerization, it was poured into 20 times the amount of methanol and purified by reprecipitation. The molecular weight of the obtained polymer was measured by GPC and was found to be Mw 583,000. This polymer was dissolved in MC Muni to form a 1% and 7% solution. this@
It was filtered through a 0.2 μm filter to obtain a resist solution. This solution was dropped onto a thermally oxidized silicon wafer, and a 1 μm thick resist film was formed by spin coating. This substrate was heat treated at 120'C for 30 minutes to obtain Sample B.

Example 3 In the same manner as in Example 1, 150 parts of 82M and 50 parts of (rMA) were dissolved in 90 parts of benzene, 80 parts of AIB No. was added as a polymerization initiator, and the mixture was polymerized in a sealed tube at 90'C for 6 hours. Polymerization Then pour into 20 times the amount of methanol,
Reprecipitation purification was performed. The molecular weight of the obtained polymer is determined by GP.
When measured at C, the Mw was 82,000. The polymer was dissolved in MCj to make a 12-chi solution. which one is 0.2
It was filtered through a μm filter 7-2 to obtain a resist solution. This solution was dropped onto a thermally oxidized silicon wafer, and a 1 μm resist film was formed by spin coating. Heat this board at 120℃ for 30 minutes1
9 and designated as sample C.

Comparative Example 100 parts of methyl methacrylate purified by distillation under reduced pressure was dissolved in 100 parts of purified benzene, and 100 parts of methyl methacrylate was dissolved in 100 parts of purified benzene.
01 part was added as a polymerization initiator, and polymerization was carried out at 90'C for 2 hours in a sealed tube. After polymerization, it was poured into 20 times the volume of methanol and purified by reprecipitation. The molecular weight of the obtained polymer was measured using GPC and was found to be 634,000. This polymer was dissolved in ethyl cellosolve acetate to give a 5% solution. This was filtered through a 0.2 μm filter and used as a resist solution. This solution was dropped onto a thermally oxidized silicon wafer, a resist film with a thickness of 1 μm was formed by spin coating, and a sample was taken.

The samples prepared above were exposed to -D using a deep ultraviolet exposure device at various exposure times. After exposure, samples A to C were developed by immersion in methyl isobutyl ketone, and the sample was developed in 3 parts of isoamyl acetate.

The film was developed by immersing it in a developer containing 1 part of ethyl acetate, and the sensitivity was measured.

Further, the dry etching characteristics of samples M to D were evaluated using a parallel plate type reactive sputter etching apparatus. CF4 was used as the etching gas, and the gas pressure was o, 1To.
Etching was performed for 3□ minutes under the following conditions: rr, output 0.45 W/c, and i. The following table shows the evaluation results of sensitivity and dry etching resistance.

As described above, the present invention provides a resist with high sensitivity and excellent dry etching resistance, and will greatly contribute to the semiconductor industry.

Claims (1)

[Claims] A resist material for deep ultraviolet exposure consisting of a benzyl methacrylate/glycidyl methacrylate copolymer having a copolymerization composition of 70 to 60 moles of benzyl methacrylate and 30 to 50 moles of glycidyl methacrylate.