Growth kinetics and properties of dielectric films synthesized by low pressure chemical vapor deposition from diethylsilane

Diethylsilane (DES) has been used to synthesize amorphous silicon carbide and silicon dioxide films by low pressure chemical vapor deposition. For silicon carbide, the deposition rate at 700°C was observed to vary linearly with flow rate and pressure while the stoichiometry of the deposits showed little variation from a composition of Si_0.6C_0.4. In the 600-700°C range, the growth rate was observed to follow an Arrhenius behavior with an activation energy of 41 kcal mol^-1. The stoichiometry became progressively richer in carbon with higher temperatures. The onset of crystallinity was observed to occur for the 850°C deposits and the films were found to be tensile in all cases. The silicon dioxide films were synthesized in the temperature range 350-475°C with the growth rate observed to follow an Arrhenius behavior with an apparent activation energy of 10 kcal mol^-1. The growth rate was seen to increase with higher pressure and to vary as a function of the square root of the DES flow rate and O₂-to-DES ratio. In both the pressure and the O₂-to-DES ratio studies conducted at 400°C, there were points of abrupt cessation in deposition. The density and index of refraction of the films were found to be 2.25 g cm^-3 and 1.45 respectively, independent of deposition conditions. The etch rate of the films in a 25°C P-etch solution was observed to decrease with higher deposition or annealing temperatures, reflecting densification of the material. Despite severe aspect ratios, the films were seen to exhibit good step coverage.