The effect of ‘warm’ gas scattering on the deceleration of energetic atoms: Monte Carlo study of the sputter-deposition of compounds

A Monte Carlo simulation code has been developed to account for the mass transfer in the sputtering deposition. In the present work, the velocity of gas atoms at ambient temperature is taken into consideration, while the gas atoms have been regarded cold enough compared to the sputtered particle. The effect of gas motion becomes important at higher pressures since sputtered particles tend to be scattered more frequently and to be decelerated more. We present the formalism of (1) mean free path of the sputtered particle, (2) velocity distribution of the colliding gas particle, and (3) transformation of the coordinates between colliding system and laboratory one. The effect of these processes on the compositional deviation of LaB6 films that are sputter-deposited at higher gas pressures is discussed.