Effects of thermal and electrical stress on defect generation in InAs metal–oxide–semiconductor capacitor

Defects in HfO ₂ dielectric film caused by indium and arsenide diffusion from InAs were investigated. To investigate the dissociation of InAs during post-deposition annealing (PDA) at 600 °C, we analyzed the ratio of the elements on the surface of the oxide layer and the chemical states by using time-of-flight secondary-ion mass spectroscopy and X-ray photoelectron spectroscopy, respectively. In–As bonding was dissociated and In and As atoms were diffused through the HfO ₂ layer from InAs. Fortunately, the diffusion and trap density could be controlled by using a 1-nm-thick Al ₂ O ₃ passivation layer. In addition, we used the nitridation process to control the trap density. We evaluated the thermal and electrical stability of three samples—HfO ₂ /InAs, HfO ₂ /Al ₂ O ₃ /InAs, and nitrided HfO ₂ /Al ₂ O ₃ /InAs—by analyzing the change in trap density before and after PDA at 600 °C and the stress-induced leakage current. In conclusion, the passivation layer effectively improved the thermal and electrical stability, whereas the nitridation process using NH ₃ gas did not. Moreover, although nitridation could reduce the interfacial defect states, due to structure distortion, it induced the degradation of the device.