Study on precipitations of fluorine-doped silicon oxide

Abstract

Precipitation on fluorine-doped silicon oxide film (SiOF) was observed while exposure to air for a prolonged period of time (>4 h). Most of the precipitates are less than 1 mum and clustered at wafer center. Under SEM view, the precipitation shows hexagonal shape, and mainly composed of Si and O. SIMS analysis showed that SiOF films without F precipitates showed leveling F% profile, whereas SIMS result for SiOF films with precipitations shows increasing gradient with depth. In this study, factors affecting the precipitation of SiOF film were investigated. Humidity in environment was found to be one of the essential elements for the onset of precipitation. Process optimization and control methodologies were also investigated for precipitation prevention to provide a more robust and stable SiOF film, hence ensuring the reliability of device performance. (C) 2003 Elsevier B.V. All rights reserved.