An experimental design method was used to define the process behavior of the two barrier metal properties most applicable to semiconductor device fabrication: contact resistance and contact junction current leakage. Instead of using basic research-level evaluations such as sfoichiomefry and film composition, we attempt to optimize titanium nitride (TiN) barrier metal properties to obtain both low contact resistance and low contact junction current leakage. The optimization was based on TiN films made using a rapid thermal process (RTF).
Our study focussed on TiN barriers formed on arsenic-doped n-type contacts. A two-step thermal process was used with temperature and duration of each step and the initial titanium thickness chosen as process variables. Response surface modeling of the contact resistance and contact junction leakage current reveals response variations that suggest three regions of film formation. The model defines an optimum barrier metal process to minimize both contact resistance and current leakage for the arsenic-doped contacts used for this study.