EFFECT OF ION IRRADIATION ON INTERNAL-STRESS OF AMORPHIC CARBON-FILMSPRODUCED BY PULSED-LASER

Amorphic carbon films either 50 or 160 nm thick were deposited on Si(1 00) and glass substrates at room temperature in a high-vacuum environm ent using a Q-switched Nd-YAG pulse laser focused on a graphite target . These films were irradiated with Ti+ or C+ ions having kinetic energ ies of 35 and 75 keV, and the changes in internal stresses of the film s with varying ion influence were investigated by measuring substrate bending using stylus profilometry. The ion energy and the film thickne ss were chosen such that the ion penetration depth, R(p), corresponded to either the film thickness or one half of the film thickness. The r esults indicate that there is an optimum ion fluence leading to a stre ss-free film for a given ion species and energy. Interpretation of the resulting stress behavior from ion irradiation was made based on the relaxation resulting from damage inside the film together with interfa cial mixing. The scanning electron microscopy pictures and surface rou ghness measurements showed a very smooth surface for both as-deposited and ion-irradiated films. The ion-irradiated films had a Vickers hard ness greater than 22 GPa, and were adherent to both Si and glass subst rates. An investigation of the film characteristics using Raman scatte ring and electron-energy loss spectra has revealed that high-energy io n irradiation of an intermediate ion fluence can be utilized successfu lly to deposit an adherent and hard carbon film with controlled intern al stress without changing the film structure significantly.