Computer simulation of the ion beam deposition of binary thin films: Carbon nitride and boron carbide

Abstract

A dynamic trim-based computer simulation program that includes treatment of post-cascade atomic motion has been used to model the ion beam deposition of carbon nitride and boron carbide thin films at energies below 100 eV. Simulations of chemically enhanced phenomena are based on describing the motion of the atoms as a sequence of ballistic steps followed by a chemically guided step. In the case of B–C films, a satisfactory description of the experimental results is achieved by including only ballistic effects in the simulation. For C–N, agreement between experiment and simulation requires the inclusion of a mechanism of preferential nitrogen re-emission into the program. This mechanism is modeled by the formation of nitrogen-containing dimers which are considered volatile and are readily released through the surface. The probability of dimer formation depends on the local N concentration. The simulation reproduces well both as-deposited composition measurements and Auger sputter depth profiling. The model represents a possible implementation of chemical sputtering.