LOW-PRESSURE CHEMICAL-VAPOR-DEPOSITION OF SILICON-NITRIDE USING THE ENVIRONMENTALLY FRIENDLY TRIS(DIMETHYLAMINO)SILANE PRECURSOR

This study investigates the use of the environmentally benign precurso r tri(dimethylamino)silane (TDMAS) with NH3 to synthesize silicon nitr ide films by low pressure chemical vapor deposition. The growth kineti cs are investigated as a function of deposition temperature, total pre ssure, and NH3/TDMAS flow ratios. The deposits are found to be essenti ally stoichiometric and to contain similar to 5 at. % carbon when appr opriate NH3 concentrations are present. The films are found in all cas es to be amorphous and highly tensile, For optimized processing condit ions, values of the refractive index are close to those reported for S i3N4. The film density is observed to increase with higher deposition temperatures up to 800 degrees C and then decrease due to the onset of gas phase nucleation effects. This behavior is readily reflected in t he etch rate of those films. FTIR spectra reveal the presence of hydro gen even at high deposition temperatures (900 degrees C). Hardness and Young's modulus of the films are seen to increase with higher deposit ion temperatures, reaching saturation values near 20 and 185 GPa, resp ectively, above 800 degrees C.