Minimization of line width variation in photolithography

Abstract

A practical photolithographic process for use in manufacturing isolation structures in semiconductor substrates at the 0.18 μm scale uses an inorganic anti-reflective coating (ARC) layer, particularly silicon oxynitride, under a silicon nitride mask layer to minimize substrate reflectivity. The same ARC layer increases latitude in process conditions in photolithographic patterning of both a first mask layer and a second planarization mask level. The silicon oxynitride layer additionally reduces edge/corner stress in isolation structures, improving gate oxide integrity in the device of which the isolation structure forms a part. Furthermore, because silicon oxynitride and silicon nitride respond to the same process conditions, a silicon oxynitride ARC layer can be introduced without increasing process complexity.

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