Nitrogen-containing organic compound, chemically amplified positive resist composition, and patterning process

Abstract

An aralkylcarbamate of imidazole base is effective as the quencher. In a chemically amplified positive resist composition comprising the carbamate, deprotection reaction of carbamate takes place by reacting with the acid generated upon exposure to high-energy radiation, whereby the composition changes its basicity before and after exposure, resulting in a pattern profile with advantages including high resolution, rectangular shape, and minimized dark-bright difference.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No. 2010-189289 filed in Japan on Aug. 26, 2010, the entire contents of which are hereby incorporated by reference.TECHNICAL FIELD[0002]This invention relates to a novel nitrogen-containing organic compound, a chemically amplified positive resist composition comprising the compound, and a patterning process using the composition.BACKGROUND ART[0003]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, DUV and EUV lithography is thought to hold particular promise as the next generation in microfabrication technology. In particular, photolithography using an ArF excimer laser as the light source is thought requisite to the micropatterning technique capable of achieving a feature size of 0.13 μm or less.[0004]The ArF lithography started partial use fro...

AI Technical Summary

Benefits of technology

[0020]The nitrogen-containing organic compound of the invention is a carbamate, especially aralkylcarbamate of an imidazole base. In the chemically amplified positive resist composition comprising the nitrogen-containing organic compound, deprotection reaction of carbamate takes place by reacting with the acid generated upon exposure to high-energy radiation, whereby the composition changes its basicity before and after exposure. This results in a favorable resist pattern with advantages including high resolution, rectangular profile, and minimized dark-bright difference. In addition, the compound is effective for rendering the alkylsulfonium salt shelf stable. The compound is quite useful as the quencher in the chemically amplified positive resist composition.

Problems solved by technology

Although lithography using F2 laser (157 nm) was initially thought promising as the next lithography for 45-nm node devices, its development was retarded by several problems.

While the ArF immersion lithography has entered the commercial stage, the technology still needs a resist material which is substantially insoluble in water.

The triphenylsulfonium salts, however, have the drawback that they exhibit substantial absorption at the ArF exposure wavelength (193 nm) to reduce the transmittance of a resist film, sometimes leading to a low resolution and a less rectangular pattern profile.

The naphthyl-1-tetrahydrothiophenium salt suffers from a low stability in resist solution due to the alkylsulfonium salt structure susceptible to nucleophilic displacement reaction and a substantial difference in line width or pattern profile between grouped and isolated patterns, which are generally referred to as “dark-bright difference.” In particular, the pattern profile difference between dark and bright areas is a problem.