JPS6137825A - 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 I (wherein R1-3 are each H, a 1-6C hydrocarbon group or a group derived by replacing at least one H thereof with F) obtained by conducting Diels-Alder reaction between (methyl)cyclopentadiene and an (isopropenyl) ester of a carboxylic acid 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 a number-average MW of 10,000-1,000,000 having fundamental units of formula II in the molecular skeleton. A solution prepared by dissolving a mixture comprising this resist material and 0-50wt% organic material (e.g., epoxy resin) in a solvent is applied to a substrate, cured by heating to 100-200 deg.C, exposed to electron beams, and developed with a developer comprising a good solvent and a poor solvent.

Description

[Detailed Description of the Invention] The present invention has high sensitivity to radiation such as electron beams and X-rays, and high resolution. This is a positive type electron beam resist material with excellent dry etching resistance. is required to satisfy the following properties (1) to (2).

■: Must be highly sensitive to electron beams.

■: High resolution.

■: Excellent dry etching resistance.

Many materials for electron beam resists have been announced so far, 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 whether to use a negative type or a positive type, the trend toward finer images has been increasing in recent years, so high-resolution #
Expectations are especially strong for the resists and the smooth-type resists.

A typical positive electron beam resist developed so far is polybutene-1-sulfone (PBS).
) and polymethyl methacrylate (PMMA). Although PBS has very high sensitivity, it has poor dry etching resistance and resolution that is not very dry. PMMA has high resolution, but low sensitivity (and poor dry etching resistance. In other words, it does not satisfy the required properties (1) and (2).

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, both the PNS sensitivity and resolution are low (0), that is, the required properties (2) and (2) are not satisfied. PNS can also be said to be a satisfactory resist material for use in actual processes.

An object of the present invention is to provide a material for positive electron beam resist that has excellent dry etching resistance, high sensitivity, and high resolution, that is, it satisfies all of the above-mentioned required properties. Particularly, the object of the present invention is to obtain an essential portion of a polymer having a basic unit represented by the following general formula in its molecular skeleton.

A positive electron beam resist characterized by having a
~B indicates the hydrocarbon residue, R4 is ra) carbon number 1-2
The polymer of the present invention is usually A compound represented by the general formula rA) and 80. It is obtained by total copolymerization with.

In formula 1, R1 to R4 are the same as above) formula (λ)
The compound represented by is typically a Dale-Alder compound of cyclopentadiene and a vinyl ester of carboxylic acid (
(Dials-Alder) reaction (formula (At) below).

Compounds obtained by VC, such as carrying out the Dielg-Alder reaction using methylcyclopentadiene in place of cyclopentadiene and impropenyl ester of carboxylic acid in place of carboxylic acid novinyl ester, such as The following formula (A2) ~
The compounds shown in (A4) can also be used preferably.

(AI) (As) (A3)
rA4) In formula 1, R4#: t: same as above) A radical catalyst is usually used as a catalyst for the copolymerization of the compound represented by formula (A) and 802 at a temperature of −IDD°C to 100°C.
, preferred, 1. , < are carried out at -50°C to D°C.

In this case, a compound having an olefinic carbon=carbon double bond having 2 to 20 carbon atoms can also be coexisting as a monomer. These olefins are, for example, one or more of ethyl ene, propylene, butene, pentene, hexene, cyclopentene, cyclohexene, and styrene.

These olefins are preferably used in an amount of 50% by weight or less of the compound represented by formula (A).
A copolymer is obtained in which a 2-element is partially inserted into its molecular skeleton.

These copolymers belong to so-called polysulfones. The above-mentioned copolymer can also be totally synthesized and used by other methods known as polysulfone synthesis methods, such as oxidation of polysulfide.

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.

It is also possible to completely mix other organic materials into the polymer used in the present 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% by weight 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 5% to 20% by weight is prepared.

In the present invention, the resist material-containing solution is usually applied onto the substrate using a spin coater. Preheating can be performed as necessary after coating. Heating temperature is 100-200
℃, preferably 140 to 160℃.

A positive-type substrate coated with resist is exposed to electron beams or the like in a conventional manner, and only the exposed portions of the resist are decomposed to achieve the purpose.

As the phenomenon liquid after electron beam exposure, a mixture of a good solvent such as chloroform, cyclohexanone, tetrahydrofuran, and dioxane and a poor solvent 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 has higher sensitivity and resolution than PNS.

This is a substituent -0-C-R (R is ra) a hydrocarbon residue having 1 to 20 carbon atoms or (b
) represents one or more hydrogen atoms contained in a hydrocarbon residue having 1 to 20 carbon atoms replaced with a fluorine atom) is an effect that can only be realized by introducing it 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 -0-C-R 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.

The Dale-Alder reaction between cyclopentadiene and vinyl acetate was carried out at 30°C to obtain [Compound ■] in a yield of 92%. 1000 ml of 7-chlorohexanone compound (076 g (0.5 cm) and t- Butyl hydroperoxide 0. A5. g (0,005
mot) and stirrer? I put it in the attached 2t flask. While cooling the flask in a low-temperature bath, stir the contents and harmful substances to maintain the internal temperature at t-20℃, and add 32 g of sulfur dioxide (0.50 oL) there.
Polymerization was carried out by blowing in small amounts. After polymerization at −20° C. for 1 hour, polymerized oil i101 was added dropwise to methanol to form a white precipitate. This precipitate was purified by dissolving it in chloroform and reprecipitating it in methanol. When dried under reduced pressure at 50℃ for 24 hours, the weight of the precipitate was 82
g (yield 75%).

It was confirmed by elemental analysis, NMR analysis, and IR analysis that this precipitate was a 1/1 alternating copolymer of compound (1) and sulfur dioxide. When the molecular weight was determined by GPC analysis using all polystyrene standards, Mn: 4.8X 10', Mw
: 15. Ox I Q4 and ivy.

The vinyl ester of trifluoroacetic acid was synthesized by the Diels-Alder reaction with heptacyclopentadiene, and then, in the same manner as in Synthesis Example 1, compound
An alternating copolymer of No. 1 was synthesized. Mn: 8,4x1
0', Mw: 12.5xIQ'.

2, 2.3.3.4.4.5.8-CF,H [Compound ■] was synthesized by Diels-Alder reaction between vinyl ester of 5-octafluorovaleric acid and cyclopentadiene, and then synthesis In the same manner as in Example 1, a 1/1 alternating copolymer of compound 0η 1 and sulfur dioxide was synthesized. M
n: 3. <5X10', MW: 8.2X10'.

PNS'i was synthesized from synthetic norbornene and sulfur dioxide in the same manner as in Synthesis Example 1. Mn: 16.9X10'.

Mw: 147xIQ4.

Comparative Synthesis Example 2 A resist solution commercially available as polymethyl methacrylate (PMMA) OE s R-1000r Tokyo Ohka (
Co., Ltd.) was used.

Examples 1 to 3 and Comparative Examples 1 to 2 Polymers I to m obtained in Polymerization Examples 1 to 3 and PNSk obtained in Comparative Polymerization Example 1 were dissolved in cyclohexanone to obtain 1
A 0% by weight solution was prepared. These solutions and PMMA
OEBR-1000'k, a commercially available resist solution of
, using a spin coater tube to coat approximately 0.5
It was applied to a thickness of μm. Next, this wafer was preheated for 1 hour at a temperature of 160° C. in a constant temperature bath purged with nitrogen.

Electron beam resist evaluation equipment for electron beam exposure KRE-301 (
The test was carried out using an accelerating voltage of 20 KV using an electric motor (manufactured by Erionigis Co., Ltd.). 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 sensitivity and contrast (an index of resolution, the higher the better) of the resist were completely determined.

The plasma etching resistance of the coating film is determined by plasma reactor PR.
-501 (manufactured by Yamato Kagaku C Co., Ltd.), and the resistance to CF4 plasma was evaluated by the rate at which the film thickness decreased per unit time.

The results of the performance evaluation are shown in Table 1 and FIGS. 1 and 2.

As a result, Examples 1 to 3 using polymers I to
It can be seen that the dry etching resistance is almost the same as that of Comparative Example 1 using S, and the sensitivity is higher than that of Comparative Example 1.

Furthermore, the contrast values of Examples 1 to 3 were higher than those of Comparative Example 1, indicating that the resolution was higher. Comparative Example 2 using PMMA has high resolution but low sensitivity and poor etching resistance.

αυ

[Brief explanation of drawings]

The attached drawings are curves showing the performance of the resist material of the present invention in comparison with other resist materials, and Figure 1 shows the sensitivity characteristics of the resist material in terms of the relationship between the standardized film thickness and the electron beam exposure dose. Is the graph, Figure 2, dry etching resistance? 3 is a graph showing the relationship between plasma etching time and etching thickness.

Claims (1)

[Claims] ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R_1, R_2, and R_3 each represent hydrogen or a hydrocarbon residue having 1 to 6 carbon atoms, and R_4 is (a) ~20 hydrocarbon residues or (b) 1 to 2 carbon atoms
(Represents one or more hydrogen atoms contained in the hydrocarbon residue of 0 substituted with a fluorine atom) Having a polymer having the basic unit represented by the above general formula in its molecular skeleton as an essential component A material for positive electron beam resist characterized by: