Patent ID: 7125496

Claim:
A method comprising the sequential steps of: (a) coating a photoresist layer on an etch target layer; (b) exposing the photoresist layer to light having a wavelength of 157 nm to 193 nm and then developing the photoresist layer to form a photoresist pattern; (c) applying a flow of a mixture of fluorine-based gas, an Ar gas, and an O 2 gas to form a polymer layer on the photoresist pattern without deforming the photoresist pattern, wherein the photoresist pattern defines a critical dimension of less than 90 nm, the fluorine-based gas is C x F y or C a H b F c , and x, y, a, b, and c ranges from 1 to 10, the flow of O 2 gas is about 1 sccm to less than 5 sccm, the flow of fluorine-based gas is about 5 sccm to about 20 sccm, and the flow of Ar gas is about 100 sccm to about 1000 sccm; and, (d) etching the etch target layer using the polymer layer and the photoresist pattern as an etch mask.