Role of gate current and polarization switching in sub-60 mV/decade steep subthreshold slope in metal–ferroelectric HfZrO2–metal–insulator–Si FET

We experimentally observed a sub-60 mV/decade steep subthreshold slope (SS) in metal–ferroelectric HfZrO2 (FE:HZO)–metal–insulator–Si (MFMIS)-FET. We investigated its physical mechanism by monitoring gate leakage current, which enabled us to trace polarization switching. We fabricated MFMIS-FET by integrating an FE:HZO capacitor on a conventional MISFET. In our MFMIS-FET fabricated on MISFET with a leaky gate insulator, sub-60 mV/decade SS was observed along 2 decades of drain current, and the minimum SS was 21 mV/decade. The observed steep SS can be explained with a novel physical model by combining the charge injection to the internal gate and the polarization switching in FE:HZO. The characterization and analysis in this work will help provide insights into the physical mechanism of the steep SS phenomenon observed in MFMIS-FET.