PLASMA CHEMICAL-VAPOR-DEPOSITION OF SIO2 ON AIR-EXPOSED SURFACES BY COLD-PLASMA TORCH

A compact size, cold plasma torch developed for open air material processing has been applied to SiO2 film deposition on various substrates. Under atmospheric pressure, homogenous nonequilibrium low temperature plasma was generated by an RF (13.56 MHz) excitation of helium or argon in a capacitively coupled cylindrical type reactor with the grounded anode shielded with a dielectric material. By using this cold plasma torch, SiO2 films have been deposited on substrates exposed to air at a temperature of 200 degrees C or below by feeding tetramethoxysilane (TMOS) or tetraethoxysilane (TEOS) into the plasma. The characterization of films by Fourier transform infrared spectroscopy x-ray photoelectron spectroscopy, and scanning electron microscopy revealed that the films were essentially SiO2. The muring of hydrogen in the plasma was found quite effective for reducing the carbon contamination and improving the film quality. The step coverage behavior of SiO2 films was also investigated using trenched Si substrates, and it differed markedly depending on the source gas of films.