Formation of plasma induced surface damage in silica glass etching for optical waveguides

The mechanism of formation of plasma induced surface damage (PISD) in silica glass etching for optical waveguides was discussed. For the study, Ge, B, P-doped silica glass films were etched by inductively coupled plasma (ICP) with chrome etch masks. It was suggested that in most cases, PISD sources were formed on a glass surface after chrome etching, and metal compounds were identified in these sources. It was also suggested that PISD is decreased or even disappeared at high power and/or low pressure in glass etching, even if PISD sources were present on the glass surface before etching.