Optimization of selective TiSi2 chemical vapor deposition by mechanistic chemical kinetics

Abstract

The a priori kinetic optimization sometimes needed for process development has generally proven difficult for reactions governed by surface chemistry. The difficulty usually results from the considerable detail with which the component steps of the overall reaction must be understood. In the present work, we summarize advances in kinetic methodology that were required for fully modeling the chemical vapor deposition of titanium disilicide from TiCl4 and SiH4. Modifications of the ultrahigh vacuum (UHV) technique of temperature programmed desorption (TPD) proved invaluable in measuring useful rate constants for polycrystalline surfaces and for products not normally visible in TPD. New methodology for sample transfer into UHV also provided the data required for development of a silicide process having 100% selectivity on Si vs SiO2. This work represents to our knowledge the first time UHV-based kinetic models have successfully guided the a priori development of a process governed by surface reactions in which optimization has not already been accomplished by enlightened trial and error.