CVD OF SILICON NITRIDE PLATE FROM HSiCI₃‐NH₃‐H₂ MIXTURES

Abstract

Preferred conditions for the chemical vapor deposition of thick, stoichiometric alpha-phase silicon nitride (Si₃N₄) plate from HSiCI₃-NH₃-H₂ were identified by means of a designed experiment. The design included temperatures from 1300−1500°C, pressures from 0.5−2.0 Torr, and mean gas residence times from 0.01−1.0 sec. Si₃N₄ plates 0.05−0.5 mm thick were produced on multiple vertical substrates at rates of 5−70;μm/hr. Plates 0.5−4.0 mm thick were produced on horizontal substrates at rates of 60−1200 μm/hr. Crystallite sizes determined by X-ray line broadening range from 0.05−1.0 m. Multiple correlation analyses show that thickness variations in the deposit are reduced by decreasing gas residence time and temperature. Si₃N₄ plate produced under the preferred conditions exhibits theoretical density and a columnar morphology in which the >222< ctystallographic direction is oriented preferentially normal to the surface.