LPCVD deposited amorphous silicon dioxide SiO2 thin films from a new chemical vapor source, diethylsilane (DES), were characterized. This work is focused on evaluation of SiO2 films prepared by varies deposition temperatures and flow rates series.
SiO2 thin films were evaluated for density, porosity, and refractive index. Techniques for evaluation of the above mentioned parameters for this work included the use of infrared absorption spectroscopy, preferential etch procedures, optical measurement of refractive index and thickness, and thermal annealing of CVD films. The densification in vacuum ambient has been carried out at the temperature of 600 °, 750 °, and 900 °C, respectively.
The P-etch rates of SiO2 thin films, produced using DES as a silicon source, were found to be in the range of 846 A/min. to 930 A/min. for a deposition temperatures between 375 ° and 475 °C; while the etch rates were constant (about 900 A/min.) for SiO2 films produced by varing diethylsilane flow rates between 20 and 150 sccm.
In the infrared absorption spectra, the strong Si-O-Si stretching band at the frequency 1070 cm -1 shifted about 0 to 15 cm -1 to high frequency, after annealing. The degree of shifting depends on the original deposition and the annealing temperature. Shiftings were also observed at the Si-O-Si bending and rocking bands at 800 and 450 cm -1 respectively.
The ellipsometric measurement indicated the index of refraction for SiO2 thin film to be 1.45 with no significant difference for samples with different deposition conditions
