Oxide Deposition By PECVD

Abstract

We have studied the chemical and physical properties of silicon oxide films plasma deposited from TEOS ( tetraethoxysilane), to gain an understanding of the origins of (1) step coverage and (2) film stability. TEOS was diluted in helium /oxygen mixtures and deposited as a function of discharge frequency (150 kHz and 14 MHz) and 02 flow in a parallel plate reactor. The typical deposition conditions were 1 torr total pressure, 320 °C substrate temperature, 1 -9% TEOS, 1 -80% 02, and -0.1 W /cm2 discharge power. Films deposited at high frequency with excess oxygen were generally oxygen -rich, chemically unstable and hygroscopic, while films deposited at low frequency were stable to moisture and slightly deficient in oxygen. However, coverage profiles of high frequency films showed an unusual degree of directionality, which could be used to advantage for the coating of high aspect ratio features. We suggest that a judicious combination of high and low frequency discharges may improve film properties while maintaining directional step coverage.Isotopic labeling experiments were performed using 1602 to gain insight into the origins of the oxygen that is contained in these PECVD films. Complete isotopic scrambling was not observed. Film composition data suggest that there is one tenacious Si -160 bond which remains with the silicon from the original TEOS molecule during the reaction to form SiO2.

Gap‐Fill with PECVD SiO2 Using Deposition/Sputter Etch Cycles

“…They changed the reactant mixture (from the usual high O2/TEOS ratio to a low ratio) in order to shift the mechanism of deposition from one dominated by surface reactions to one dominated by ion bombardment. Another approach has been the addition of nitrogen trifluoride, NFa, (8)(9)(10) or ammonia, NH~ (10) to inhibit growth of the film along the side-wall as completely as possible. However, the improvement in gapfill produced by all these modifications of deposition conditions has been illustrated only for relatively low AR spaces and thin conductors.…”