Chemical vapor deposition processes are employed to fill high aspect ratio (typically at least 3:1), narrow width (typically 1.5 microns or less and even sub 0.15 micron) gaps with significantly reduced incidence of voids or weak spots. This deposition process involves the use of both hydrogen and fluorine...http://www.google.com/patents/US6846745?utm_source=gb-gplus-sharePatent US6846745 - High-density plasma process for filling high aspect ratio structures
