Deposition on thin SiO2 layer by reactive sputtering

Abstract

We investigate the experimental possibilities for producing high purity stoichiometric SiO2 thin films by reactive ion beam sputtering. The layers were deposited in a UHV chamber ( base pressure 4 x 10(-9) mbar) by 1 keV Ar+ ions for sputtering from a high purity silicon target, using different values of the oxygen partial pressure ( 5 x 10(-6) -1 x 10(-3) mbar) and of the ion beam current on the target (1.67 - 6.85 mA). The argon partial pressure during ion gun operation was 1 x 10(-3) mbar. The substrates were held at room temperature or at 550 degrees C, and the films were deposited to 12.5 - 150 nm, at a rate from 0.0018 - 0.035 nm/s. To perform structural characterization we used Rutherford backscattering spectrometry, electron microprobe, X-ray diffraction and Raman spectroscopy. From the results it is clear that reactive ion beam sputtering proved to be efficient for deposition of high quality silica films at 550 degrees C, oxygen partial pressure of 2 x 10(-4) mbar ( ion beam current on the target from 5 to 5.5 mA) or at a lower deposition rate, ion beam current of 1.67 mA and oxygen partial pressure of 6 x 10(-5) mbar. The aim of these investigations was also to study the consumption of oxygen from the gas cylinder. We found that it is lower for higher deposition rates.