Diffusion barrier properties of TiW between Si and Cu

100-nm-thick TiW (30 at. % Ti) films were used as diffusion barriers between silicon substrates and thin Cu films. Sheet resistance measurements, Rutherford backscattering spectrometry, Auger electron spectroscopy, transmission electron microscopy, scanning electron microscopy, and x-ray diffractometry indicated the absence of interdiffusion and structural change for unpatterned Si/TiW/Cu samples up to 775 °C if there was no exposure to air between TiW and Cu deposition and 850 °C if there was an exposure, respectively. Leakage current measurements showed no deterioration of diode junctions up to 725 °C for TiW without air exposure and 775 °C for air-exposed TiW.