Process-property relationships between silicon selective epitaxial growth ambients and degradation of insulators

Comprehensive thermodynamic analyses of the effects of silicon selective epitaxial growth (SEG) environments and low temperature substrate pretreatments on insulator degradation are presented. Silicon nitride is predicted to degrade at about 150 degrees C higher than silicon dioxide of the same thickness in DCS/H-2 ambients at 40 Torr, in agreement with experimental data. Hydrogen/HCl and hydrogen/HCl/dichlorosilane substrate treatments are shown to result in more extensive insulator degradation than a hydrogen bake at the same conditions (e.g., 40-150 Torr, 0.001-1 ppm H2O), also in agreement with experimental data. In low temperature silicon SEG, the addition of ppm levels of a chlorosilane to H-2 is predicted to lower the temperature at which substrate surfaces are cleaned in situ by about 150-200 degrees C, at 0.1-100 Torr, in agreement with experimental observations. Because these thermodynamic analyses take a short computation time (e.g., typically on the order of a few seconds), such results can serve as effective guidelines for substrate surface cleaning and insulator degradation during silicon SEG. Further, these results effectively yield basic process-property relationships between silicon SEG ambients and degradation of insulators with a minimal amount of experimentation. (C) 1996 American Vacuum Society.