Formation of high moisture and dopant diffusion resistivity silicon nitride films by catalytic-CVD method

High resistivity for moisture and dopant diffusion silicon nitride films ar e prepared by catalytic-CVD method. In this method, SiH4 and NH3 gases are decomposed by the catalytic-cracking reactions with a heated tungsten catal yzer placed near substrates, and so that silicon nitride films are formed w ithout any help from plasma nor photochemical excitation at the temperature as high as 300 degreesC. The properties of catalytic-CVD silicon nitride f ilms are investigated. It is found that, 1) stoichiometric silicon nitride film whose refractive index is 2.0 shows high moisture resistance, 2) ultra thin silicon nitride film (equivalent oxide thickness: 3.5nm) blocks B diff usion even 1000 degreesC annealing.