Patent ID: 7670958

Claim:
An etching method providing an etch tool exhibiting a design based on a design specification designating use of argon only as an inert gas, wherein the improvement comprises: applying a photoresist over a substrate, the photoresist having a composition sensitized to an actinic energy wavelength of 248 nm or less; forming an opening in the photoresist; placing the substrate in the etch tool; and etching the substrate under the opening using a plasma generated with a gas composition comprising argon and an amount of krypton while applying a total power density of at least 5 W/cm 2 to a bottom electrode receiving the substrate, the amount being effective to increase photoresist stability compared to otherwise identical etching using argon or lower atomic mass noble gas in place of the krypton and the increase in photoresist stability decreases production of deformities in the photoresist of such an extent that smooth surfaces of the substrate before the etching would become roughened and/or striated during the etching and which deformities do not result merely from photoresist faceting.