Junction leakage in titanium self-aligned silicide devices

Successful utilization of a titanium self-aligned silicide (salicide) process for reproducible device fabrication with high yield requires junction leakage due to the silicide process to be minimized. The microstructure and microchemistry of titanium salicide shallow junction diodes were studied and correlated with junction leakage. The direct correlation between junction leakage and junction structure was established by using several analytical techniques. The main cause of large leakage current was found to be a loss of p+/n junction under the titanium silicide layer and formation of titanium silicide/n-silicon Schottky barrier contact at the perimeter of the diodes. Process parameters for low leakage titanium silicide/p+/n diode fabrication were also established.