THE EFFECT OF HYDROGEN DILUTION ON THE AMINOSILANE PLASMA REGIME USEDTO DEPOSIT NITROGEN-RICH AMORPHOUS-SILICON NITRIDE

The first hydrogen dilution study of ammonia/silane plasmas tuned to a n aminosilane plasma regime is reported. The use of formal statistical experimental design techniques have enabled us to determine the effec ts that hydrogen dilution level, rf power density and substrate growth temperature have on various film properties. Hydrogen dilution of the ammonia/silane plasma reduced the amino (NH2) content of the deposite d nitride films while also driving the intrinsic film stress to compre ssive values. Increasing the substrate temperature also reduced the am ino concentration, but drove the film stress tensile. It was therefore possible to control the film stress and produce nitride films that co ntained only N-H and Si-N bonds (with no detectable NH2 or Si-H bonds) by choosing a suitable combination of H-2 dilution level and growth t emperature. Exodiffusion experiments on such 'bond optimised' films re vealed only one hydrogen evolution peak at temperatures in excess of 9 00 degrees C, with no ammonia exodiffusion detected.