Chemical Vapor Deposition of Silicon Nitride: Encapsulant Layers for Annealing Gallium Arsenide

Abstract

Noncrystalline layers are grown at low temperatures by the chemical reaction of silane and ammonia, and at extremely high deposition rates (120Å/sec) which is 50 times higher than the usual deposition rates. Correlations between growth conditions and layer properties are studied. The growth conditions for obtaining the most suitable encapsulant layers for the annealing of ion‐implanted are: gas feed rates of silane, ammonia, and nitrogen carrier gas of 5, 200, and 1500 ml/min, respectively, and a growth temperature of 700°C. Layers formed under these conditions have a refractive index of 1.95 and an etch rate of 500 Å/min in 50% solution. These values are nearly equal to that of conventional layers deposited at lower deposition rates. Auger electron spectroscopic analysis shows an oxygen concentration below the detection limit (<0.1 atom percent) and a uniform Si/N ratio along the thickness direction. Out‐diffusion of Ga and As into the layer does not occur on 900°C annealing. No cracks are formed when thin layers, less than 1200Å thick, are deposited on substrates. These layers are useful as encapsulant films for the annealing of .