COMPUTER-SIMULATION OF THE ION-BEAM DEPOSITION OF BINARY THIN-FILMS -CARBON NITRIDE AND BORON-CARBIDE

A dynamic TRIM-based computer simulation program that includes treatme nt of post-cascade atomic motion has been used to model the ion beam d eposition of carbon nitride and boron carbide thin films at energies b elow 100 eV. Simulations of chemically enhanced phenomena are based on describing the motion of the atoms as a sequence of ballistic steps f ollowed by a chemically guided step. In the case of B-C films, a satis factory description of the experimental results is achieved by includi ng only ballistic effects in the simulation. For C-N, agreement betwee n experiment and simulation requires the inclusion of a mechanism of p referential nitrogen re-emission into the program. This mechanism is m odeled by the formation of nitrogen-containing dimers which are consid ered volatile and are readily released through the surface. The probab ility of dimer formation depends on the local N concentration. The sim ulation reproduces well bath as-deposited composition measurements and Auger sputter depth profiling. The model represents a possible implem entation of chemical sputtering.