Reversal Etching of Chromium Film in Gas Plasma

Abstract

The mechanism of the reaction in the reversal gas plasma etching of anti-reflective chromium photomasks was studied. Auger spectrometer and x-ray photoelectron spectrometer studies of the film revealed that WO3 is incorporated in the surface of the chromium oxide layer of the anti-reflective photomasks for the samples showing reversal etching. WO3 forms a kind of masking layer for the etching. Decomposed species of the photoresist film are found to be responsible for the etching of WOs, and carbon monoxide is proposed as the reactive species for etching the WO~ masking layer. This reversal etching was applied to the fabrication of the photomasks for MOS LSI.