PROCESS-PROPERTY RELATIONSHIPS BETWEEN SILICON SELECTIVE EPITAXIAL-GROWTH AMBIENTS AND DEGRADATION OF INSULATORS

Comprehensive thermodynamic analyses of the effects of silicon selecti ve epitaxial growth (SEG) environments and low temperature substrate p retreatments on insulator degradation are presented. Silicon nitride i s predicted to degrade at about 150 degrees C higher than silicon diox ide 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 d egradation than a hydrogen bake at the same conditions (e.g., 40-150 T orr, 0.001-1 ppm H2O), also in agreement with experimental data. In lo w temperature silicon SEG, the addition of ppm levels of a chlorosilan e to H-2 is predicted to lower the temperature at which substrate surf aces are cleaned in situ by about 150-200 degrees C, at 0.1-100 Torr, in agreement with experimental observations. Because these thermodynam ic analyses take a short computation time (e.g., typically on the orde r of a few seconds), such results can serve as effective guidelines fo r substrate surface cleaning and insulator degradation during silicon SEG. Further, these results effectively yield basic process-property r elationships between silicon SEG ambients and degradation of insulator s with a minimal amount of experimentation. (C) 1996 American Vacuum S ociety.