ATMOSPHERIC-PRESSURE CHEMICAL VAPOR-DEPOSITION OF SI AND SIGE AT LOW-TEMPERATURES

Ultraclean atmospheric pressure chemical vapor deposition has been used to grow Si and SiGe epitaxial films at low temperatures, 550-850-degrees-C, in several reactors including a commercial production type tool. The use of a load lock, gas purifiers, and careful gas handling procedures allows epitaxial films to be grown down to 550-degrees-C with undetectable levels of oxygen and carbon at the growth interface. This is achieved in part by the discovery that the atmosphere of hydrogen inhibits Si oxidation at the growth temperature. Doped layers with active concentrations of phosphorous and boron to 1-3 X 10(20) cm-3 have been achieved. Phosphine and arsine enhance the growth rate under certain process conditions which is contrary to all previous reports in the literature. N-type doping with phosphine can be modulated more than two orders of magnitude which indicates that dopant retention on sample or reactor wall surfaces is not a problem. Emitter-base diodes formed in the N-type epitaxial layers exhibited ideal forward and low-leakage reverse characteristics. SiGe/Si heterostructures with Ge content of 14%-44% exhibit abrupt interfaces and smooth surfaces. Selective Si and SiGe layers have been grown on oxide patterned wafers without the appearance of facets.