THE INFLUENCE OF Si_3N_4 COMPOSITION AND MECHANICAL /CHEMICAL PRE-TREATMENTS ON THE ADHESION STRENGTH OF MPCVD DIAMOND FILMS

摘要

The influence of Si_3N_4 composition and surface state on CVD diamond nucleation density and adhesion strength is studied. Acid leaching, CF_4 plasma etching, scratching with diamond powder and ultrasonic diamond suspension agitation were the selected surface treatments prior to CVD diamond deposition. The effect of SiC inclusions in the Si_3N_4 matrix is further investigated, as the carbide enhances the substrate/film chemical bonding and promotes adhesion. Nucleation density was evaluated by SEM analysis. The film/substrate adhesion and stress state were measured by the Brale indentation method.