A Kinetic Study on the Growth of Nanocrystalline Diamond Particles to Thin Film on Silicon Substrate

Abstract

A kinetic study has been made for the growth of nanocrystalline diamond (NCD) particles to a continuous thin film on silicon substrate in a microwave plasma chemical vapor deposition reactor. Parameters of deposition have been microwave power of 1.2 ㎾, the chamber pressure of 110 Torr, and the Ar/CH4 ratio of 200/2 sccm. The deposition has been carried out at temperatures in the range of 400~700℃ for the times of 0.5~16 h. It has been revealed that a continuous diamond film evolves from the growth and coalescence of diamond crystallites (or particles), which have been heterogeneously nucleated at the previously scratched sites. The diamond particles grow following an h2 = k’t relationship, where h is the height of particles, k’ is the particle growth rate constant, and t is the deposition time. The k’ values at the different deposition temperatures satisfy an Arrhenius equation with the apparent activation energy of 4.37 ㎉/㏖ or 0.19 eV/atom. The rate limiting step should be the diffusion of carbon species over the Si substrate surface. The growth of diamond film thickness (H) shows an H = kt relationship with deposition time, t. The film growth rate constant, k, values at the different deposition temperatures show another Arrhenius-type expression with the apparent activation energy of 3.89 ㎉/㏖ or 0.17 eV/atom. In this case, the rate limiting step might be the incorporation reaction of carbon species from the plasma on the film surface.