THE EFFECT OF SURFACE PREPARATION ON THE NUCLEATION OF DIAMOND ON SILICON

A series of investigations into the surface preparation and modification techniques has been undertaken to study the influence of surface pre-treatment on nucleation enhancement of diamond film growth on silicon by microwave plasma-enhanced chemical vapour deposition. This paper deals with different scratching, cleaning and etching techniques. Polishing with dry diamond powder resulted in a high and uniform nucleation density and in good quality dense films, 2 mum thick, after deposition for 2 h, and the nucleation density increased with increasing polishing time. Polishing with fine-grained sprays is less effective than polishing with powders, and the nucleation density is reduced with increasing grain size with no growth for a 6 mum spray. By ultrasonic treatment in a diamond dispersion, neither a high density nor uniformity of nucleation has been obtained. The nucleation density decreased as a function of the length of the ultrasonic cleaning after the pre-treatment. The results support the theory that the residue left on the surface after pre-treatment is important to the nucleation.