Pretreatment of silicon substrates for CVD diamond deposition studied by atomic force microscopy

We have investigated the early stages of biasing pretreatment experiments on (100) silicon substrates in a hot-filament CVD reactor under different conditions by Atomic Force Microscopy (AFM). The influence of the gas-phase composition on the surface morphology and the different behaviour under biasing and diamond deposition conditions are discussed. In addition to topographical imaging we have also utilized HF etching and force-distance curves in order obtain chemical information about the surface. The obtained results indicate that surface roughening, which is about a factor of two higher under biasing than under diamond deposition conditions, is caused by etching of elemental silicon via formation of hydrides.