FUNDAMENTAL-STUDIES ON THE SELECTIVE EPITAXIAL-GROWTH OF SILICON-BASED FILMS

Selective epitaxial growth of silicon-based films is investigated experimentally and theoretically at reduced system pressures and temperatures between 800 and 1100-degrees-C. Smiling and frowning Phenomena are examined by developing mask oxide adsorption layer profiles on patterned substrates. Adsorption and desorption rate constants are estimated from transition state theory and theoretical Langmuir adsorption isotherms, while surface diffusivities are modeled as functions of jump length, surface vibration frequency, and surface diffusion activation energy. At lower substrate temperatures, Cl* is predicted to be the most abundant mask oxide adatom, while at higher temperatures, H* is predicted to be the dominating adatom. SiCl2* is seen to be the major adatom in the temperature range of about 800 to 1000-degrees-C. At temperatures below 900-degrees-C, increased pressures are predicted to produce higher oxide surface coverages for H* and Cl*, and lower ones for SiCl2*. At temperatures above 900-degrees-C, lower pressures are seen to produce higher mask oxide surfaces coverages for H* and Cl*, and lower ones for SiCl2*. In selective growth environments, the higher the reactor inlet flow rate of HCl is, the weaker the smiling phenomena in seed windows are found to be. Agreement between experimental data and theoretical predictions is seen to be satisfactory.