ANNEALING OF DIAMOND ABOVE 800-DEGREES-C - NEED FOR AND RESULTS OF SI3N4 ENCAPSULATION

A boron-implanted marker and secondary ion mass spectroscopy analysis were used for diamond etching assessment. Trace amounts of oxygen in a rgon etch polycrystalline diamond films during annealing at 800 degree s C. The deposition of a protective PECVD hydrogenated amorphous silic on nitride layer prevents such etching during annealing at: least up t o 1300 degrees C. The hydrogen losses of Si3N4 during heating, from 10 % after growth to 0.5% at 1000 degrees C, do not reduce the diffusion barrier efficiency. This is attributed to Si-N bond reconstruction dur ing H effusion. The influence of high temperature annealing on the dia mond film was studied by IR transmission spectroscopy and X-ray microa nalysis. No carbon compound was found on the diamond surface after ann ealing and Si3N4 removal. However, a large amount of silicon carbide w as observed after annealing above 1100 degrees C at the interface betw een the diamond film and the silicon substrate.