PASSIVATION, STRUCTURAL MODIFICATION, AND ETCHING OF AMORPHOUS-SILICON IN HYDROGEN PLASMAS

Atomic hydrogen from plasma discharges dissolves in silicon previously amorphized by ion implantation (aSi) in the form of Si-H bonds, givin g rise to infrared (IR) absorption at similar to 1990 cm(-1) and causi ng partial activation of implanted dopants. Passivation of aSi does no t affect the rate at which the material subsequently undergoes solid p hase epitaxy, Exposure giving rise to [H]>6 at. % causes the appearanc e of an additional IR absorption band at similar to 2080 cm(-1) sind c oloration of the layer. Despite annealing, the Si-H defects, normal so lid phase epitaxy does not occur during subsequent heat treatment. The structural modification by H-plasma exposure coincides with etching n f the layer. The observations can be understood in terms of void forma tion in aSi resulting from the clustering of Si-H. (C) 1997 American I nstitute of Physics.