Growth of diamond on silicon during the bias pretreatment in chemical vapor deposition of polycrystalline diamond films

Abstract

The processes that occur on the silicon substrate during the bias pretreatment in a microwave plasma chemical vapor deposition system for the growth of diamond are investigated using a variety of techniques. The direct current during the bias pretreatment is correlated with changes in the shape of the plasma and with the amount and chemical and crystalline nature of the deposit on the substrate as well as with the nucleation density for subsequent diamond growth. The spatio-temporal nature of the nucleation process explains the evolution of the bias current. It is shown that the bias pretreatment alone already yields a closed layer of nanocrystalline diamond and a strong etching of the silicon substrate. An analysis of the nucleation conditions necessary for the formation of oriented and textured diamond crystallites leads to a choice of parameters during bias pretreatment that yield homogeneous layers of highly oriented and textured diamond crystals over an area of 100 mm2.