ELECTRON-CYCLOTRON RESONANCE PLASMA CHEMICAL VAPOR-DEPOSITION OF LARGE AREA UNIFORM SILICON-NITRIDE FILMS

Electron cyclotron resonance plasma (f = 2.45 GHz, microwave power P = 200-800 W) generated in a radially uniform magnetic field (B = 875-1000 G) was used to produce a large area (15-20 cm diam) uniform plasma stream at 20-30 cm from the source output. Low temperature (70-300-degrees-C) silicon nitride films with a thickness of 800-3000 angstrom were deposited on 5-20 cm diameter wafers with deposition rates of 100-350 angstrom/min. Film thickness uniformity was +/- 1% for 7.6-10.0 cm diam wafers, +/- 3% for 15 cm diam wafers, and +/- 9% for 20.0 cm diam wafers. It was found that the film deposition rate W(g) increased linearly with the silane flow rate, while W(g) increased slower than power 1/2 with the nitrogen flow rate. The film refractive index was 1.9-2.0 at a silane/nitrogen flow rate ratio of 0.40-0.6. The effects of plasma density and its profile on the film growth rate and uniformity are discussed.