| Atmospheric pressure chemical vapor deposition of epitaxial {dollar}rm Sisb{lcub}1-x-y{rcub}Gesb{lcub}x{rcub}Csb{lcub}y{rcub}{dollar} films was carried out in a commercial reactor between 500-700{dollar}spcirc{dollar}C using dichlorosilane, germane, ethylene and hydrogen, with the purpose of investigating the deposition chemistry and obtaining films suitable for device fabrication. A wide range of process conditions were explored to reveal important deposition trends. The results indicated that surface kinetics controlled the deposition process. The film composition greatly influenced the deposition process and the film quality.; Important surface reactions were identified and a kinetic model was developed that was in excellent agreement with the experimental results. It revealed that the change in concentrations of silicon and germanium vacant surface sites was responsible for most of the observed trends. Due to the low sticking coefficient of ethylene and its tendency to retain C-C bond after adsorption, use of a more suitable carbon source is recommended.; Defect free films containing up to 52 at. % germanium and 3.5 at. % carbon and thicknesses ranging from 600-5700 A were obtained. Characterization techniques available in a wafer fabrication facility such as bright light, optical microscopy, stress gauge and AFM were found to be very useful to investigate structure, composition and thickness of these films. The addition of a few at. % of carbon suppressed formation of misfit dislocations, reduced surface roughness, increased critical thickness and had a profound influence on the crystal structure. However, depending on the processing conditions there was a crucial carbon content above which the films became defective and amorphous. |
