Novel ester compounds, polymers, resist compositions and patterning process

Abstract

Novel ester compounds having formula (1) wherein A1 is a polymerizable functional group having a double bond, A2 is furandiyl, tetrahydrofurandiyl or oxanorbornanediyl, R1 and R2 each are a monovalent hydrocarbon group, or R1 and R2 may bond together to form an aliphatic hydrocarbon ring with the carbon atom, and R3 is hydrogen or a monovalent hydrocarbon group which may contain a hetero atom are polymerizable into polymers. Resist compositions comprising the polymers are sensitive to high-energy radiation, have an improved sensitivity, resolution, and etching resistance, and lend themselves to micropatterning with electron beams or deep-UV rays.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] The present application is a 37 C.F.R. § 1.53(b) divisional of U.S. application Ser. No. 10 / 671,948 filed Sep. 29, 2003, which in turn claims priority on Japanese Application No. 2002-285161 filed Sep. 30, 2002. The entire contents of each of these applications is hereby incorporated by reference.BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to (1) a novel ester compound, (2) a polymer comprising units of the ester compound which is blended as a base resin to formulate a chemically amplified resist composition suitable in the micropatterning technology, (3) a resist composition comprising the polymer, and (4) a patterning process using the resist composition. [0004] 2. Prior Art [0005] While a number of recent efforts are being made to achieve a finer pattern rule in the drive for higher integration and operating speeds in LSI devices, deep-ultraviolet lithography is thought to hold pa...

AI Technical Summary

Benefits of technology

[0010] Therefore, an object of the present invention is to provide (1) a novel ester compound capable of forming a polymer which is effectively acid-decomposable and can control the diffusion of the acid generated upon exposure, (2) a polymer which is blended as a base resin to formulate a resist composition having a higher sensitivity and resolution than conventional resist compositions as well as minimized line density dependency, (3) a resist composition comprising the polymer as a base resin, and (4) a patterning process using the resist composition.

[0011] It has been found that ester compounds of the general formula (1), shown below, can be prepared in high yields by a simple method to be described later; that polymers obtained using the ester compounds have high transparency at the exposure wavelength of an excimer laser; that resist compositions comprising the polymers as the base resin have a high sensitivity, high resolution and minimized line density dependency; and that these resist compositions lend themselves to precise micropatterning.

Problems solved by technology

While it is desired to achieve a finer pattern rule, none of these acid eliminatable protective groups are deemed to exert satisfactory performance.

However, in this event, the deactivation of the generated acid by air-borne basic substances has a relatively large influence, giving rise to such problems as a T-top pattern.

On the other hand, 2-tetrahydropyranyl and 1-ethoxyethyl are so reactive with acids that with the acid generated by exposure, elimination reaction may randomly proceed without a need for heat treatment, with the result that substantial dimensional changes occur between exposure and heat treatment / development.

Where these groups are used as protective groups for carboxylic acid, they have a low inhibiting effect to alkali dissolution, resulting in a high rate of dissolution in unexposed areas and film thinning during development.

If highly substituted polymers are used to avoid such inconvenience, there results an extreme drop of heat resistance.

These resins fail to provide a difference in rate of dissolution before and after exposure, resulting in resist materials having a very low resolution.

For the above-described resist materials using acid-eliminatable protective groups, there is a common problem of line density dependency that when a pattern to be transferred includes dense and sparse regions, it is impossible to produce the desired pattern in both the dense and sparse regions at the same exposure.

Then at the very fine pattern size for which an ArF excimer laser is actually used, a resist material having substantial line density dependency cannot be used in an industrially acceptable manner because solitary lines can disappear.

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