Optical and compositional study of silicon oxide thin films deposited in a dual-mode (microwave/radiofrequency) plasma-enhanced chemical vapor deposition reactor

Silicon oxide deposition in a dual-model microwave/radiofrequency reactor is studied as a function of different plasma parameters. Optical and compositional analysis is conducted on deposited layer using in situ UV-visible and Fourier transform infrared ellipsometry techniques, IR transmission and VUV spectroscopies, and nuclear reactions. It is shown that it is possible to increase the density of the films and decrease their hydrogen content by using a higher deposition temperature and/or using helium dilution and/or using the ion bombardment effect of the rf plasma. In situ IR ellipsometry reveals water absorption on the as-deposited silicon oxide films, just after exposing them to the ambient atmosphere. UV absorption spectroscopy shows an absorption peak at 6.3 eV, with an amplitude dependent on the hydrogen content.