Stress testing and characterization of high-k dielectric thin films

While TaO_x, HfO_x, Hf-doped TaO_x and Zr-doped TaO_x thin films exhibit promise as potential candidates for use as gate dielectric, their reliability is barely understood. Therefore, as an initial step in the investigation of their reliability, stress tests are conducted in this experimental study to characterize high-k thin films. In humidity stress tests, analyses of variance are performed on the measure defined in I-V and C-V curves to examine the significance of the stress effects. The high-k films are compared with SiO₂ in terms of leakage current and relaxation current. By studying the dielectric relaxation and analyzing the transient current, the breakdown mode of the tested high-k films is identified, and a sensitive method of breakdown detection is proposed.