The use of the environmentally benign precursor ditertiarybutylsilane (DTBS) with NH3 to synthesize silicon nitride films by low pressure chemical vapor deposition was investigated. In the temperature range 600 to 700 °C, the growth rate is observed to follow an Arrhenius behavior with an activation energy of 50 kcal mol-1, while above 700 °C, the rate decreases with higher temperatures primarily due to the gas phase decomposition of DTBS. The growth rate varied linearly with total pressure over the investigated range of 0.2 to 0.65 Torr and with DTBS flow rate up to a value of 20 sccm in agreement with a Langmuir-Hinshelwood mechanism. A rapid decrease in growth rate was observed with higher NH3 DTBS ratios due to a reduction in the partial pressure of DTBS and its enhanced competition with NH3 for available surface sites. All deposits were found to be essentially stoichiometric and to contain ≈ 10 at% carbon. The films were found in all cases to be amorphous and highly tensile. At deposition temperatures below 750 °C, values of the refractive index were near those reported for Si3N4. FTIR spectra revealed the presence of hydrogen for even the highest investigated deposition temperature (900 °C). The hardness and Young's modulus of the films increased with higher deposition temperatures reaching values near 19 and 190 GPa, respectively, at 900 °C.
All Science Journal Classification (ASJC) codes
- General Materials Science
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering