Patent ID: 7790334

Claim:
A method of forming a photomask, comprising: patterning a resist mask layer on a photomask layer to define an opening in the resist mask layer, the photomask layer containing at least a chromium layer; depositing a conformal polymer protective layer on the patterned resist mask layer with a predefined thickness to define a trench in the patterned resist mask layer, the trench having a sidewall of the conformal polymer protective layer lining the opening in the patterned resist mask layer and a bottom closing the opening in the patterned resist mask layer, wherein the depositing of a conformal polymer protective layer is performed in the presence of one or more fluorocarbon processing gasses; anisotropically etching the bottom of the conformal polymer protective layer, while leaving at least a portion of the sidewalls of the conformal polymer protective layer intact to define an opening in the conformal polymer protective layer defined between the sidewalls of the conformal polymer protective layer; etching the chromium layer through the opening in the conformal polymer protective layer to expose an underlying layer, wherein the etching of the chromium layer is performed in the presence of a chlorine-containing gas; and removing the patterned resist mask layer and the polymer protective layer.