Effects of Ti–W target processing methods on defect generation during very large scale integrated device fabrication

Abstract

The relationship between Ti–W target manufacturing technique and deposited film quality is examined with an emphasis on film defect density. Three different target manufacturing methods are investigated; vacuum hot pressing (VHP), inert gas hot pressing, and hot isostatic pressing. The target composition in all cases is 18 wt % titanium, the configuration is seven inch diameter conical and two purity levels (99.95% and 99.995%) are evaluated. Target processing methods and microstructure results are discussed. Scanning electron microscopy micrographs show distinct differences in the amount of pure alpha titanium and the homogeneity of the titanium and tungsten rich beta Ti–W phases. The characteristics of films deposited from each of the three targets are investigated. Standard film properties are presented with an emphasis on film defect density as measured by several different methods. Transmission electron microscopy micrographs of the deposited film show distinct differences in film structure. Significant differences in defect density were also found with the VHP having the lowest overall defect density. A mechanism for defect generation due to pressure within target voids is discussed.