Amorphous WO3 thin films have been deposited in a plasma-enhanced chemical vapordeposition system, and were patterned with a 193-nm excimer laser (one pulse, 10-25 mJ/cm2). Negative-tone, sub-0.5-micrometer lines and spaces were obtained following dry development in a low-power CF4 plasma. The mechanism for laser induced etch selectivity was studied with angle-resolved x-ray photoelectron spectroscopy. It was inferred from the fluorine photoelectron spectra that the laser induces atomic rearrangements that impede the etch process initiated by fluorine-containing radicals. A possible interpretation is that the rearrangements, which may be partially thermally activated, reduce the volume of the microvoids present in WO3.
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