Low-Pressure Chemical Vapor Deposition of Silicon Dioxide Using Diethylsilane

In this study, diethylsilane (DES) has been used as a precursor to produce silicon dioxide films by low-pressure chemical vapor deposition. These films were synthesized in the temperature range 350–475 °C with the growth kinetics observed to follow an Arrhenius behavior with an apparent activation energy of 10 kcal/mol. The growth rate was seen to increase with higher pressure and to vary as a function of the square root of the O₂ flow rate and O₂/DES ratio. In both the pressure and the O₂/DES ratio studies conducted at 400 °C, film deposition ceased abruptly for conditions where total pressure was less than 0.35 Torr and where the O₂/DES ratio was higher than 2.35. The density and index of refraction of the films were close to 2.25 g/cm³ and 1.45, respectively, independent of deposition conditions. The etch rate of the films in a 25 °C P-etch solution decreased with higher deposition or annealing temperatures, reflecting densification of the material. For aspect ratios close to 1.3, the films exhibited a step coverage better than 55%.