Resist composition and patterning process

Abstract

A positive resist composition comprising a resin component having a solubility in an alkaline developer that increases under the action of an acid, a compound capable of generating an acid in response to actinic radiation, and an acidic organic compound having a molecular weight of at least 150 exhibits a high resolution and is effective in minimizing defects when processed by the photolithography. The composition is thus quite effective for precise micropatterning.

Description

Claims

1. A positive resist composition comprising (A) a resin component having a solubility in an alkaline developer that increases under the action of an acid,(B) a compound capable of generating an acid in response to actinic light or radiation, and(C) at least one acidic organic compound having a molecular weight of at least 150.

2. The positive resist composition of claim 1, wherein said acidic organic compound (C) has the general formula (1): R1—X  (1)

3. The positive resist composition of claim 1, wherein said acidic organic compound (C) has the general formula (2): CH3(A)nCH2—X  (2)

4. The positive resist composition of claim 1, wherein the resin component (A) comprises acidic recurring units.

5. A process for forming a pattern, comprising the steps of applying the positive resist composition of claim 1 onto a substrate to form a resist coating; heat treating the resist coating and exposing it to high-energy radiation or electron beam through a photomask; and heat treating the exposed coating and developing it with a developer; the exposing step being effected by the immersion lithography wherein a high refractive index liquid having a refractive index of at least 1.0 intervenes between the resist coating and a projection lens.

6. A process for forming a pattern, comprising the steps of applying the positive resist composition of claim 1 onto a substrate to form a resist coating; heat treating the resist coating and exposing it to high-energy radiation or electron beam through a photomask; and heat treating the exposed coating and developing it with a developer; said process further comprising the step of coating a protective film on the resist coating,the exposing step being effected by the immersion lithography wherein a high refractive index liquid having a refractive index of at least 1.0 intervenes between the protective film and a projection lens.