Performance of titanium nitride diffusion barriers in aluminum–titanium metallization schemes for integrated circuits

Three different contact schemes Al–Si, Al/Ti–Si, and Al/TiN/Ti–Si have been studied for their electrical characteristics and thermal stability on shallow n+p-junctions. Contact resistance and leakage current measurements indicate that the Al/Ti structure remains stable up to 450 °C and the Al/TiN/Ti structure up to 500 °C for 15 min, whereas Al–Si contacts degrade already at 400 °C. The stability of the Al/Ti contacts is limited by the thin film reaction between Al and Ti while the failure of the Al/TiN/Ti structure is attributed to local defects such as pinholes in the TiN barrier.