Total Ionizing Dose Effect at Low Temperature in HfO₂ MOS Capacitors Irradiated with Proton

The total ionizing dose effect of HfO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>MOS capacitors was investigated using proton irradiation at room temperature (300 K) and low temperature (100 K). Capacitance-voltage (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$C-V$</tex>) analysis measurement was utilized to characterize the oxide trapped charge density (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\Delta N_{ot}$</tex>) and the interface trapped charge density (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\Delta N_{it}$</tex>) before and after irradiation. Our experimental results show that i) the oxide trapped charge density (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\Delta N_{ot}$</tex>) in the HfO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>MOS at 100 K is <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$1.4\times 10^{12}cm^{-2}$</tex>, which is higher than the value of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$4\times 10^{11}cm^{-2}$</tex> measured at 300 K; ii) the interface trapped charge density (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\Delta N_{it}$</tex>) resulting from proton irradiation at 100 K is <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$2\times 10^{11}cm^{-2}$</tex>, which is lower than the value of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$6\times 10^{11}cm^{-2}$</tex> measured at 300 K. The mechanism of the temperature effect on HfO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> MOS capacitors was investigated through Kinetic Monte Carlo (KMC) simulations, which indicated that temperature decreasing can enhance the stability of charged defects in the oxide layer, facilitating the generation of oxide tapped charges. Besides, the temperature decreasing can reduce the interface trapped charges by suppressing hydrogen-related defect decomposition reactions. The assignment of how temperature affects the total ionizing dose effect in MOS capacitors is important to advance the understanding of complex processes occurring under ion-solid interactions, as well as in the design of aerospace MOS devices.