Intracavity laser spectroscopy of reactive intermediates in the CVD of silicon containing films

Abstract

The use of intracavity laser spectroscopy (ILS) in the real time, in situ, detection of intermediate gas phase species during the chemical vapor deposition (CVD) of silicon by plasma and pyrolysis processes is demonstrated. Gas phase species that are important in CVD processes as likely precursors either to film growth (e.g., SiH2) or to the incorporation of contaminants/dopants in the deposited films (e.g., C2, BH2) are observed with good sensitivity. ILS measurements of the relative concentrations of such species are used as a basis for selecting CVD process conditions and for evaluating the potentials of various organosilanes as alternative source materials to silane in the CVD of silicon films. These ILS data, in combination with the results of film composition analyses, indicate that SiH2 is formed in a homogeneous, gas phase process and is an important prerequisite for silicon film growth. This conclusion pertains to the CVD of silicon‐containing films prepared by pyrolytic decompositions of various organosilanes under conditions of moderate temperature and pressure.