Measurement and simulation of forces generated when a surface is sputtered

Forces on small plane sputter targets that are exposed to an ion beam at different angles of incidence are investigated. The force exerted on the sputter target is determined in two dimensions by means of an interferometric technique that measures the displacement of the target which is mounted at the end of an elastic cantilever. Different target materials made of silver, copper, aluminum, titanium, graphite, and carbon fiber velvet are studied. The experimental results are compared with a simulation based on the popular SRIM code. The forces are found to be caused predominantly by implanted beam particles and sputtered target atoms and insignificantly by re-emitted beam particles. The material dependent forces are discussed in connection with the simulations and in terms of the sputtering yield and surface topography. In case of the carbon fiber velvet, and in good approximation for graphite, the transferred momentum corresponds almost entirely to the momentum of the impinging beam particles.