Pattern dependence in selective epitaxial Si1−xGex growth using reduced-pressure chemical vapor deposition

Abstract

Pattern dependence of the growth rate and Ge content in selective epitaxial Si1−xGex growth using reduced-pressure chemical vapor deposition has been examined for the SiH2Cl2-GeH4-H2 system. Contrary to selective epitaxial Si growth where pattern dependence diminishes at low growth temperatures, the growth rate of selectively grown Si1−xGex layers depends on the ratio of the exposed Si area to the oxide-covered area on a wafer, at temperatures as low as 600 °C. The Ge content in the layers also depends on the ratio, and the dependence is greater at higher temperatures. Adding HCl to the gas phase decreases the pattern dependence of both growth rate and Ge content. Although, in terms of the growth rate, an optimum HCl flow rate for pattern-insensitive growth exists, the Ge content in the layers is always higher for the wafer with a smaller exposed area.