Adhesion improvement of diamond and other films after MeV ion irradiation

This paper reports the effects of MeV ion irradiation on the adhesion and quality of diamond films on WC-Co tool-bits and silver films on soda glass. Diamond films of about 3 mu m thickness were prepared, using the hot filament CVD technique, on WC-Co tool-bits. Silver films of 1000 Angstrom thickness were prepared, using the Joule evaporation technique, on soda glass. 100 MeV I-127 beam was irradiated on the films at various doses up to 1 x 10(14) ions/cm(2). Adhesion strength was measured using a pin-pull test. Scotch tape test was also performed on some of the films; SEM images show no morphological modifications of the diamond films after irradiation. Laser Raman spectra show that the irradiation causes almost complete elimination of non-diamond carbon present in the films. Adhesion strength of the diamond films as determined by Pin-pull test show improvement at least by 65 kgf/cm(2) after irradiation. Improvement in the adhesion of silver films is found to be dependent on the amount of electronic energy loss (S-e) at the film-substrate interface. It is shown that for silver film on soda glass S-e > 0.7 keV/Angstrom, is needed if the adhesion is required to be achieved at a dose of 1 x 10(13) ions/cm(2) using ion irradiation of 100 MeV I-127 beam. Main cause of the improvements in the adhesion and quality of the films is suggested to be the energy deposited to the electronic system of the material by the projectile ion. (C) 1998 Elsevier Science Ltd. All rights reserved