Ferroelectric Hafnium Nitride Thin Films Directly Formed on Si(100) Substrate

Abstract

We have investigated the ferroelectric hafnium nitride (HfN) thin films directly formed on the Si(100) substrate for the metal-ferroelectrics-Si field-effect transistor (MFSFET) applications. The 10 nm thick rhombohedral phase HfN layer was found to be formed on the Si(100) substrate utilizing the post-metallization annealing (PMA) at 400∘C/5 min for HfN0.5/HfN1.15/Si(100) MFS diode structure which was deposited with in situ process by the electron cyclotron resonance (ECR) plasma reactive sputtering. The remnant polarization (2Pr) of 24.0μC/cm2 with the coercive field (Ec) of 3.8 MV/cm was obtained from the P-V characteristic under the voltage sweep of ±10 V. Fatigue characteristics without wake-up were confirmed until 109 program/erase (P/E) cycles under the input pulses of ±6 V/5 μs although the 2Pr was gradually decreased to 10.7 μC/cm2. The polarization (Psw) of 13.4μC/cm2 was clearly observed by the positive-up negative-down (PUND) measurements utilizing the input pulses of 6± V/5 μs. The memory window (MW) of 0.32 V was realized in the C-V characteristics by the program operation at -10 V/1 s.