Low-Resistivity and Adhesive Sputter-Deposited Cu–Ca Films with an Intermediate Oxide Layer

Abstract

We investigated a method of producing low-resistivity and adhesive sputter-deposited copper alloy films with an intermediate oxide layer that retains its adhesion after hydrogen annealing for applications of electric interconnections for thin film circuits and liquid crystal displays. The formation of an intermediate copper oxide layer between a copper film and a substrate by sputter deposition in the presence of oxygen enhances adhesion. However, when such films are exposed to hydrogen at elevated temperatures, hydrogen penetrates the films and reduces copper oxide. This reaction generates water molecules, which aggregate at the interface between the copper film and the substrate. As a result, microvoids form at the interface, degrading the film adhesion. Sputter-deposited films with an intermediate oxide layer produced from a Cu–Ca target are adhesive even after hydrogen annealing. As films deposited in pure argon have low resistivities, it is possible to form low-resistivity and adhesive metallization.