Effect of angle of incidence during deposition on Ti-Pd-Au conductor film adhesion

Abstract

The influence of a number of the preparation conditions on the adhesive properties of the Ti-Pd-Au metallization on Ta2N film resistors was investigated. Test samples consisted of a filament-evaporated conductor film on an unpatterned Ta2N film on glass, sapphire and Al2O3 ceramic substrates. The adhesive properties of the Ti-Pd-Au films were examined as a function of the angle of incidence at which the Ti and Pd atoms were deposited. In addition the adhesive properties were examined after heat treatment in air and after electroplating gold. Transmission electron microscopy and density measurements established that at higher angles of incidence (>60°) Ti and Pd films became increasingly porous and that adhesion at the Ti-Pd interface degraded rapidly upon exposure to air. Both evaporated and plated Au layers appear to offer little protection for films evaporated under these conditions. Good adhesion was found to be independent of the substrate material and of the method used for gold deposition when the Ti-Pd films were evaporated at angles of incidence of 48° or less.