Equal Thickness Contours of Films Deposited on Inclined Substrates by Evaporation and Ion Beam Assisted Deposition

A study is presented of the geometrical shape of deposition contours that arise when material is evaporated from a point source onto an inclined substrate, an arrangement common in ion-assisted deposition. The shape of the contours, as determined by the inverse square law and the angles of emission and incidence, is described by a fourth-order algebraic equation in polar coordinates on the surface of the substrate. The equation defines a family of distorted ellipses whose form depends on the angle of tilt. An experimental test of these relations by electron-beam deposition of an ion-bombarded oil film on a tilted silicon wafer will be reported.