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 argon etch polycrystalline diamond films during annealing at 800 degrees C. The deposition of a protective PECVD hydrogenated amorphous silicon nitride layer prevents such etching during annealing at: least up to 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 during H effusion. The influence of high temperature annealing on the diamond film was studied by IR transmission spectroscopy and X-ray microanalysis. No carbon compound was found on the diamond surface after annealing and Si3N4 removal. However, a large amount of silicon carbide was observed after annealing above 1100 degrees C at the interface between the diamond film and the silicon substrate.