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 $24.0 \mu \text{C}$ /cm2 with the coercive field ( ${\text{E}_{c}}$ ) 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/ $5 \mu \text{s}$ although the 2 ${\text {P}_{r}}$ was gradually decreased to $10.7 \mu \text{C}$ /cm2. The polarization (Psw) of $13.4 \mu \text{C}$ /cm2 was clearly observed by the positive-up negative-down (PUND) measurements utilizing the input pulses of ±6 V/ $5 \mu \text{s}$ . The memory window (MW) of 0.32 V was realized in the C-V characteristics by the program operation at −10 V/1 s.

Keywords

• Hafnium nitride
• ferroelectrics
• rhombohedral phase
• MFS diode
• ECR plasma
• reactive sputtering