Journal of the Electrochemical Society, Vol.146, No.6, 2337-2343, 1999
Quality of selective silicon epitaxial films deposited using disilane and chlorine
We have previously reported on the selectivity and growth of a silicon epitaxy process using Si2H6 and Cl-2 in an ultrahigh-vacuum rapid thermal chemical vapor deposition reactor. In this report, we have extended the previous work and provide information regarding the structural and electrical quality of thick (3000 Angstrom) selective silicon epitaxial layers deposited under a variety of growth conditions. Electrical test structures, including enclosed n-channel metal oxide semiconductor field effect transistors (MOSFETs) and large-area gated diodes, were fabricated within the epitaxial layers. We demonstrate that variations in the chlorine to silicon ratio (Cl/Si) acid the process temperature can lead to structural defects and low generation lifetimes. The defects, however, had a benign effect over the MOSFET drive current and channel transconductance. Overall, the results in this study indicate that high levels or chlorine, as well as low growth temperatures, can potentially inhibit the structural and/or electrical quality of selectively deposited silicon films. However, for growth at or above 800 degrees C with a Cl/Si ratio of 0.23, excellent selectivity as well as extremely high bulk generation lifetimes can be obtained for films with structural defect densities well below the detection limits used within this study.