Step coverage prediction in plasma-enhanced deposition of silicon dioxide from TEOS

Abstract

Summary form only given. The authors have developed a transient mathematical model incorporating simultaneous Knudsen diffusion and the competing heterogeneous reactions in rectangular trenches to predict quantitatively step coverage in tetraethylorthosilicate (TEOS) PECVD. The model reveals that deposition uniformity, and hence the step coverage, is controlled by two dimensionless groups. The first group represents a ratio of a characteristic deposition rate to a characteristic atomic oxygen diffusion rate. The second group represents the ratio of a characteristic wall recombination, or quench rate to diffusion rate. These groups can be used as a guideline to determine how process conditions should be adjusted to increase deposition rate without degrading step coverage. The model correctly predicts that high step coverages are obtained with low RF power, low pressure, and low wafer temperature.<>