Dielectric relaxation and breakdown detection of doped tantalum oxide high-k thin films

While TaO_x, HfO_x, ZrO_x, Hf-doped TaO_x, and Zr-doped TaO_x thin films are promising high-k gate dielectric candidates, their intrinsic reliability has not yet been investigated. In this paper, the authors examine some fundamental reliability aspects of these high-k films through ramp voltage stress testing. By studying dielectric relaxation and analyzing the transient conductivity, the breakdown mode of the tested high-k film is identified; a sensitive method of breakdown detection in ramped voltage tests is proposed and investigated.