D-2 LAMP PHOTOCHEMICAL VAPOR-DEPOSITION OF AL2O3 THIN-FILMS IN OXYGEN ATMOSPHERE

Al2O3 thin films have been deposited by D-2 lamp photochemical vapor deposition (CVD) in N-2 + O-2 atmosphere using aluminum-tri-isopropoxide as source material. The D-2 lamp emission lines overlap the strong absorption band of the source material and O-2 gas. The deposition rate increased remarkably at low temperatures compared with thermal CVD. The refractive index of the sample prepared below 270 degrees C increased with the irradiation, but above 270 degrees C the value approached the values of the samples prepared by thermal CVD. The value of tan delta at 100 Hz in the low temperature deposited samples was also improved by photo-CVD. But it showed a large value just after deposition, and it decreased to a small value after the sample was kept at room temperature. A tentative model of this change is discussed briefly.