Modeling of Cu Transport in Sputtering Using a Monte Carlo Simulation

Abstract

For the Cu-sputtering process, conventional simulations have been carried out to examine individual phenomena such as the production of plasma, the emission of atoms from the target, the transport of emitted atoms through space and the sticking of atoms onto the wall surface. We have developed a simulator which enables the analysis of the Cu-sputtering process from the production of plasma to the transport and deposition of sputtered atoms. In the present simulation, the flux of Ar ions incident onto the target is determined by a plasma simulation using a particle-in-cell/Monte-Carlo (PIC/MCC) model. Sputtered atoms are assumed to be emitted following the cosine law with a Maxwellian velocity distribution. The test-particle Monte Carlo method is used in the simulation of the transport of the sputtered atoms. Sputtered atoms are assumed to stick to the walls with a constant sticking coefficient. With a sticking coefficient of 0.93, determined experimentally, the dependence of the film growth rate on two parameters, i.e., target–wafer distance and pressure, agreed well with the experimental results.