Buried Insulator Formation in Silicon by Ion Implantation: A Review

摘要

Dynamic annealing, impurity diffusion, chemical bonding and post-implantation annealing processes in the formation of silicon-on-insulator (SOI) materials by implantation of oxygen (SIMOX) and nitrogen (SIMNI) are reviewed. Implantation temperatures for SOI formation must be selected for dynamic annealing during implantation to retain crystallinity in a Si overlayer while maintaining implanted ion profiles in Si. These conditions are satisfied by temperatures near 500 deg C for beam currents and doses used in most studies for both SIMOX and SIMNI, and the implanted ions are chemically bonded into the Si host. SIMNI differs from SIMOX in two important ways: (i) in contrast to SIMOX where a high diffusivity of O in SiO sub 2 increases the oxide layer thickness when the O concentration exceeds that for SiO sub 2 during implantation, N diffusivity is low in both Si and in Si sub 3 N sub 4 so that N can accumulate in excess of that for Si sub 3 N sub 4 , and (ii) the buried nitride layer crystallizes during post-implantation annealing near 1200 deg C whereas the oxide layer remains amorphous. Effects of these differences on resultant SOI materials are considered. Information from recent studies on combined O and N implantations for SOI, and effects of annealing SIMOX and SIMNI at temperatures above 1200 deg C are included in the review. 50 refs., 13 figs. (ERA citation 12:008392)