Room-temperature HF vapor-phase cleaning for low-pressure chemical vapor deposition of epitaxial Si and SiGe layers

Silicon dioxide films can be etched in a mixture of HF and H sub(2)O vapor. This reaction can be performed at reduced pressure, which has allowed us to develop a high-vacuum compatible etch facility. Channeling Rutherford backscattering (RBS) analysis demonstrates the feasibility of epitaxial low-pressure chemical vapor deposition (LPCVD) of Si and SiGe layers at 600 degree C on Si(100) substrates that previously have been vapor-etched in situ at room temperature. The combination of vapor-etching, LPCVD and RBS also provides kinetic information about the deposition of Si and SiGe. For temperatures of up to 900 degree C the growth SiH sub(4) is measured to follow Arrhenius-type kinetics with an activation energy of 1.3 eV. On SiO sub(2) surfaces Si deposition is retarded relative to clean Si substrates. Over the temperature range of 600-800 degree C, the incorporation of Ge in Si from GeH sub(4)/SiH sub(4) mixtures obeys the relationship % Ge(s) = 5 x % GeH sub(4)(g), for gas mixtures containing up to 5% GeH sub(4). The growth rate of GeSi alloys is found to increase linearly with the partial pressure of GeH sub(4).