Redeposition in ion milling

Redeposition is, beside trenching, the most important secondary effect in ion milling, which has a serious influence on the obtained profiles. An analytical model is developed on the basis of mass preservation: The complete mass, emerging from one milled target point, is redeposited on a screen. Considering a cos(4)-distribution of the sputtered particles, an equation for the thickness of the redeposited layer is given. These results are implemented in the computer simulation program COMPOSITE. A comparison between simulated and etched profiles shows a good agreement. (IMT)