Initiated by the demands of high temperature and high power electronics, the long-term stability of ohmic and Schottky contacts on III-V semiconductors has been extensively studied. These contact layer systems generally include a diffusion barrier that prevents the metallurgical reaction between metallization and semiconductor substrate. The stability of thin film diffusion barriers in semiconductor high-temperature metallization is essential for successful device performance.
In this work, we have investigated the deposition processes and thermal stability of reactively sputtered W-Ti-N thin films. This study was focused on the effect of nitrogen content in these films on structural, electrical and barrier properties.
The conductivity, stress, crystal structure and chemical composition as well as surface morphology have been investigated using four-point probe sheet resistance measurements, stress measurement optical system, X-ray diffraction, Rutherford backscattering spectrometry and atomic force microscopy.
Our results show, that by optimizing the parameters of sputter deposition ( W - Ti (30 at.%) target, dc power 200 W, nitrogen partial pressure 0.05 Pa, total gas pressure 0.5 Pa ), the 100 nm thick amorphous W₆₅Ti₁₇N₁₈ film shows excellent barrier property preventing the interaction between Au and GaAs under annealing at 750^o C.