JPS6137824A - New resist material - Google Patents

Abstract

PURPOSE:A resist material having excellent dry etchability, high sensitivity to electron beams and good resolution, comprising a polymer having specified fundamental units in the molecular skeleton. CONSTITUTION:A compound of formula III (wherein R1-3 are each H or a 1-6C hydrocarbon residue) obtained by conducting Diels-Alder reaction between (methyl)cyclopentadiene and a compound of formula I or II (wherein R4 is a 1-20C organic residue) is copolymerized with SO2 at -100-100 deg.C in the presence of a radical catalyst to obtain a resist material comprising a polymer of an average MW of 10,000-1,000,000, having fundamental units of formula IV in the molecular skeleton. A solution obtained by dissolving 3-40wt% mixture comprising this resist material and 0-50wt% organic material (e.g., epoxy resin) in a solvent (e.g., chloroform) is applied to a substrate, cured by heating to 100- 200 deg.C, exposed by irradiation with electron beams and developed with a developer (e.g., chloroform/methanol mixture).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a positive electron beam resist material that is highly sensitive to radiation such as electron beams and X-rays, has high resolution, and has excellent dry etching resistance. .

Electron beam resists for manufacturing semiconductor devices such as I C'PL S I are required to satisfy the following properties (1) to (2) of Klf-1 for use in actual microfabrication.

■: Must be highly sensitive to electron beams.

■: High resolution.

■: Excellent dry etching resistance.

Many materials for electron beam resists have been announced, but one that satisfies all of the above requirements has not yet been developed. Therefore, there are strong expectations in the electronics industry for the emergence of high-performance electron beam resist materials that can be used in actual processes. In addition, in terms of negative or positive resists, as the trend toward finer images has been increasing in recent years, expectations are particularly high for positive resists, which are easier to obtain high resolution.

Polybutene-1-sulfone (PBS) is a typical positive electron beam resist developed so far.
and polymethyl methacrylate (PMMA).

Although PBS has very high sensitivity, it has poor dry etching resistance and does not have very high resolution. In other words, the required properties are quite satisfied. PMMA has high resolution, but
It has low sensitivity and poor dry etching resistance. In other words, the required properties (■) and (■) are not completely satisfied.

Polynorbornenesulfone (PNS) has also been developed as a positive resist material that overcomes the weak dry etching resistance, which is a common drawback of PBS and PMMA.

However, PNS has low sensitivity and resolution. In other words, the required properties (■) and (2) are not satisfied. PNS cannot be said to be a satisfactory resist material for use in actual processes.

An object of the present invention is to provide a material tube for positive electron beam resist that has excellent dry etching resistance, high sensitivity, and high resolution, that is, a material tube for positive electron beam resist that satisfies all of the above-mentioned required properties. .

The object of the present invention is to produce a polymer having a basic unit represented by the following general formula in its molecular skeleton. Must have as an essential component
This is achieved by using a positive electron beam resist material with a %' characteristic.

In the formula 0, Rln R2+ R3 each represents hydrogen or a hydrocarbon residue having 1 to 6 carbon atoms, and R4 has 1 to 2 carbon atoms.
The polymer of the present invention usually comprises a compound represented by the general formula (A) and an organic residue of 80. It is obtained by copolymerizing with.

I R2 (wherein R1 to R4B are the same as above) formula rA)
The compound represented by formula (B1) is typically a mixture of cyclopentadiene and a compound represented by formula (B1).
Diels-Alder ) reaction (formula (Al) below).

In addition, methylcyclopentadiene is substituted for cyclopentadiene, and formula (
Compounds obtained by conducting Dials-Alder reaction 1 using the compound shown in B2), for example, the following formulas (A2) to (A4)
Compounds shown in can also be preferably used.

CH,=CH-R4...(B1) CR2=CRa...(B2)0H゛(R in the formula is the same as above) (A1) (A2)C in the formula,
R4 is the same as above) Radical catalyst P is usually used as a catalyst for copolymerization of the compound represented by formula (A) and S02 at a temperature of -100°C to 100°C.
, preferably at -509C to 0C. In this case, olefinic carbon having 2 to 20 carbon atoms as a monomer = carbon double bond? A compound that has They can also coexist.

These onfins include, for example, ethylene, propylene, butene, pentene, hexene, cyclopentene,
One or more types of cyclohexene, styrene, etc.

These onfins are preferably used in an amount of 50% by weight or less of the compound represented by formula (A).

When these olefins are used, olefin-8O
A copolymer is obtained in which 21 units are partially inserted into its molecular skeleton.

These copolymers belong to so-called polysulfones. The above-mentioned copolymers can also be synthesized and used by other known methods for synthesizing polysulfones, such as oxidation of polysulfides.

As for the molecular weight of these copolymers, those having a number average molecular number of usually 10,000 to 1,000,000, preferably 30,000 to 500,000 can be used in the present invention.

Other organic materials can also be mixed with the polymers used in the invention. Examples of this organic material include novolac type phenolic resin, resol type phenolic resin, epoxy resin, and petroleum resin. These organic materials are preferably used in an amount of 50% or less of the polymer used in the present invention.

The polymers used in the present invention are soluble in solvents such as chloroform, cyclohexanone, tetrahydrofuran, and dioxane. When using the polymer of the present invention as a resist material, by dissolving it in the above solvent,
A solution with a concentration of % heavy sweetness, preferably 5-20% by weight, is prepared.

In the present invention, the resist material-containing solution is usually applied to the substrate using a rotary coating machine. After coating, preheating can be carried out if necessary. Heating temperature is 100-200
℃, preferably 140 to 160℃.

The substrate coated with a positive resist' (R-) is exposed to light using an electron beam or the like in a conventional manner, and only the exposed portions of the resist are decomposed to achieve the fourth purpose.

As the phenomenon liquid for the electron beam exposure section, a mixture of good solvents such as chloroform, cyclohexanone, tetrahydrofuran, and dioxannatate and poor solvents such as ethanol, isopropanol, and toluene in an appropriate ratio can be used.

The resist material of the present invention is characterized in that it has dry etching resistance equivalent to that of PNS, and is also more sensitive and has a higher screening stability than PNS.

This effect is only achieved by introducing the substituent R4 (R represents an organic residue having 1 to 20 carbon atoms) into the side chain of the skeleton. Although the reason for this effect is not clear, it is presumed that the introduction of the substituent R4 increases the difference in dissolution rate in the developer between the electron beam exposed area and the unexposed area.

Hereinafter, the present invention will be explained in detail based on Synthesis Examples, Examples, and Comparative Examples, but the present invention is not limited thereto.

By carrying out the Diels-Alder reaction between cyclopentadiene and 1-pentene at 60°C, CH
3 was obtained in a yield of 90%. The compound (68 g (0.5 mol) l
! -t-butyl hydroperoxide 0.45 g (
0,005mot)? The mixture was dissolved and poured into a 2 t flask equipped with a stirrer. By stirring the contents while cooling the flask tube in a low-temperature bath, the internal temperature can be reduced to 12
32 g of sulfur dioxide (0.50 m
ot) Polymerization was carried out by blowing in small amounts. After polymerization at −20° C. for 1 hour, the mixture was dropped into methanol in the polymerization oil pipe 101 to form a white precipitate. This precipitate was purified by dissolving it in chloroform and reprecipitating it into methanol. After drying under reduced pressure at 50°C for 24 hours, the weight of the precipitate was 82 g (yield 82%). Elemental analysis, NMR analysis, and IR analysis revealed that this precipitate was a 1/1 alternating copolymerization of compound ■ and sulfur dioxide. I confirmed that it was a combination. Molecule 1i by GPC analysis using polystyrene as a standard? When calculated, Mn: 5.0X10', Mw
: 14.8×10'.

Synthesis Example 2 0-CH3 [Compound ♀] was totally synthesized by Diels-Alder reaction between vinyl methyl ether and cyclopentadiene, and then 1/1 of compound ♦ and sulfur dioxide were alternately synthesized in the same manner as in Synthesis Example 1. A copolymer was synthesized. Mn
: 7.1x10', My: 16.2X1
0' □ (CF2)5C by Diels-Alder reaction between perfluorohexylethylene and cyclopentadiene
F3 [Compound (2)] was synthesized, and then, in the same manner as in Synthesis Example 1, alternating copolymerization of Compound (1) and sulfur dioxide at 1/1 was carried out. Mn
: Z1x10', My: 13. Ivy at dx10'.

Synthesis example 4 CH2-0-CF2-CHF'-CF.

CHz OCF2 CHF-CFs [Compound ■] was polymerized by the Dils-Alter reaction of 2-human 90 perfluoropropyl allyl ether and cyclopentadiene, and compound ■ and sulfur dioxide were synthesized in the same manner as in Synthesis Example 1. /1 alternating copolymer was synthesized. Mn
: 4.5X 10', Mw: 9.2X 10
' Met.

Comparative Synthesis Example 1 From synthetic norbornene and sulfur dioxide, 1-
Is it PNS? Okinaru did. Mn: 16,9x
IQ'.

Mw: 147 x 10'.

Comparative Synthesis Example 2 V-cyst solution OE BR-1000 (manufactured by Tokyo Ohka Co., Ltd.), which is commercially available as polymethyl methacrylate (PMMA'), was used.

Examples 1 to 4 and Comparative Examples 1 to 2 Polymers I to lv obtained in Polymerization Examples 1 to 4 and PN8 obtained in Comparative Polymerization Example 1 were dissolved in total cyclohexanone to prepare a 10% by weight solution. . These solutions and PMM
OE B R-1000k, which is a commercially available resist solution of A
, using a spin coating machine to coat the silicon wafer with approximately 0.5
It was applied to a thickness of μm. Next is this wafer? The mixture was preheated at a temperature of 160° C. for 1 hour in a constant temperature bath purged with nitrogen.

Electron beam resist evaluation equipment for electron beam exposure ERE-601 (
1 plant)! ! ! ! )? The test was carried out under conditions of an acceleration voltage of 20 KV. After exposure, the film was developed using a developer appropriate for the material, and changes in film thickness were measured.

A characteristic curve was created from the relationship between the exposure amount and the change in film thickness, and the resist sensitivity and contrast (an index of resolution, the higher the better) were determined.

The plasma etching resistance of the coating film is determined by plasma reactor PR.
-501 (manufactured by Yamato Scientific Co., Ltd.) warehouse use, CF.

The resistance to plasma was determined at a rate of decrease in film thickness per unit time of 1IFI'Ifli.

The results of the performance evaluation are shown in Table 1 and Figures 1 and 2.◎ As a result, Examples 1 to 4 using polymer l-4V were
It can be seen that the dry etching resistance is almost the same as that of Comparative Example 1 using N8i, and the sensitivity is lower than that of Comparative Example 1. Furthermore, the contrast values of Examples 1 to 4 are higher than those of Comparative Example 1, indicating that the resolution is higher.

In addition, in Comparative Example 2 using PMMA, although the resolution is high,
It has been shown that sensitivity is low and etching resistance is poor.

[Brief explanation of the drawing]

Claims (1)

[Claims] ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R_1, R_2, R_3 each represent hydrogen or a hydrocarbon residue having 1 to 6 carbon atoms, and R_4
~20 organic residues) A positive electron beam resist material comprising as an essential component a polymer having a basic unit represented by the above general formula in its molecular skeleton.