Kinetic modelling of a-C:H thin fllm chemical vapour deposition on Si substrate

Abstract

We simulated plasma enhanced chemical vapour deposition (CVD) of amorphous hydrogenated carbon (a-C:H) films on c-Si substrate using our new reaction rate model. Dependences of film deposition rate and mass density on the flux of atomic hydrogen were calculated for various CH3 fluxes and various ion energies. The calculated curves agree qualitatively with experimental results. Film deposition rate, as a function of hydrogen flux, has a maximum, which could be explained by (i) stabilization of dangling bond (DB) concentration on the surface and (ii) increased etching at high hydrogen fluxes. The results of simulation and experiments do not indicate any significant effect of ion energy variation on hydrogen content in the film. Detailed analysis of calculated dependences of sp 3 /sp 2 ratio and hydrogen content on ion energy has revealed some interesting facts. First, the main mechanism of sp 3 bond formation is adsorption of CH3 on the surface. Also, as expected, the content of sp 3 declines at higher ion energies due to graphitization.