Apparatus for, and method of, depositing a film on a substrate

Abstract

An electrical field between a positive anode and a negative target in a cavity and a magnetic field in the cavity cause electrons from the target to ionize neutral gas (e.g. argon) atoms in the cavity. The ions cause the target to release sputtered atoms (e.g. aluminum) for deposition on a substrate. A shield between the target and the substrate inhibits charged particle movement to the substrate. The anode potential may be positive, and the shield and the magnetic members may be grounded, to obtain electron movement to the anode, thereby inhibiting the heating of the shield and the magnetic members by electron impingement. The anode may be water cooled. The magnitude of the positive anode voltage relative to the target voltage provides selectively for (a) a uniform thickness of sputtered atoms on the walls of a groove in the substrate or (b) a filling of the groove by the sputtered atoms and a uniform thickness of deposition on the substrate surface including the filled groove. Progressive differences in the anode-substrate voltage produce progressive increases in the rate of the sputtered atom deposition on the substrate. Oxygen flow into the cavity may be varied through a wide range at a substantially constant anode voltage to produce a deposition of aluminum oxide on the substrate with variations in the refraction index between approximately 1.63-1.70. A selected oxygen flow rate may accordingly produce an acceptable aluminum oxide refraction index in the 1.63-1.70 range, without affecting the anode voltage, even with minor oxygen flow rate variations.