1. Field of the Invention
The present invention relates to a resist composition, a method of forming a resist pattern using the resist composition, and a novel compound useful as a quencher for the resist composition.
Priority is claimed on Japanese Patent Application No. 2010-273831, filed Dec. 8, 2010, the content of which is incorporated herein by reference.
2. Description of Related Art
In lithography techniques, for example, a resist film composed of a resist material is formed on a substrate, and the resist film is subjected to selective exposure of radial rays such as light or electron beam through a mask having a predetermined pattern, followed by development, thereby forming a resist pattern having a predetermined shape on the resist film. A resist material in which the exposed portions become soluble in a developing solution is called a positive-type, and a resist material in which the exposed portions become insoluble in a developing solution is called a negative-type.
In recent years, in the production of semiconductor elements and liquid crystal display elements, advances in lithography techniques have led to rapid progress in the field of pattern miniaturization.
Typically, these miniaturization techniques involve shortening the wavelength of the exposure light source. Conventionally, ultraviolet radiation typified by g-line and i-line radiation has been used, but nowadays KrF excimer lasers and ArF excimer lasers are now starting to be introduced in mass production. Furthermore, research is also being conducted into lithography techniques that use an exposure light source having a wavelength shorter than these excimer lasers, such as F2 excimer lasers, electron beam, extreme ultraviolet radiation (EUV), and X-ray.
Resist materials for use with these types of exposure light sources require lithography properties such as a high resolution capable of reproducing patterns of minute dimensions, and a high level of sensitivity to these types of exposure light sources.
As a resist material that satisfies these conditions, a chemically amplified resist composition is used, which includes a base material component that exhibits a changed solubility in an alkali developing solution under the action of acid and an acid generator component that generates acid upon exposure.
For example, as a chemically amplified positive resist composition, a chemically amplified resist composition is used, which includes a resin component (base resin) that exhibits increased solubility in an alkali developing solution under the action of acid, and an acid generator component. If the resist film formed using the resist composition is selectively exposed during formation of a resist pattern, then within the exposed portions, acid is generated from the acid generator component, and the action of this acid causes an increase in the solubility of the resin component in an alkali developing solution, making the exposed portions soluble in the alkali developing solution.
Currently, resins that contain structural units derived from (meth)acrylate esters within the main chain (acrylic resins) are now typically used as base resins for resists that use ArF excimer laser lithography, as they exhibit excellent transparency in the vicinity of 193 nm (for example, see Patent Document 1).
As acid generators usable in a chemically amplified resist composition, various types have been proposed including, for example, onium salt acid generators such as iodonium salts and sulfonium salts; oxime sulfonate acid generators; diazomethane acid generators; nitrobenzylsulfonate acid generators; iminosulfonate acid generators; and disulfone acid generators.
Furthermore, currently, in addition to the base resin and the acid generator, a nitrogen-containing organic compound such as an alkylamine, an alkylalcoholamine or the like is added to chemically amplified resist compositions. The nitrogen-containing organic compound functions as a quencher which traps the acid generated from the acid generator, and contributes to improving various lithography properties.
In recent years, as quenchers, studies have been made on photodegradable bases which are decomposed by light or radiation. The photodegradable bases included in the resist composition are those in which the unexposed portions function as a quencher whereas the exposed portions lose the quenching capacity due to decomposition of the nitrogen-containing organic compound itself, thereby maintaining, without reducing too much, the acid concentration within the exposed portions to an adequate level.