Total-Ionizing-Dose Effects, Border Traps, and 1/<i>f</i> Noise in Emerging MOS Technologies
Daniel M. Fleetwood
Abstract
Subthreshold leakage currents and threshold-voltage shifts due to total-ionizing-dose (TID) irradiation are reviewed briefly for highly scaled devices in emerging MOS technologies. When isolation oxides of digital and analog MOS devices and ICs exhibit satisfactory performance, failure doses often are 100 krad(SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) to 1 Mrad(SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) or higher. Oxygen vacancies in SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> and/or high-K gate dielectrics and/or O-vacancy complexes with hydrogen are typically the dominant border traps before and after irradiation. Low-frequency noise measurements can provide significant insight into effective border-trap microstructures, densities, and energy distributions, especially when combined with complementary measurements and density-functional theory calculations. Illustrative examples are presented for past, present, and emerging MOS technologies with SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> and/or high-K gate dielectrics. These include FinFETs, MOS devices with alternative channels to Si, MOS devices based on 2-D materials, and SiC MOS devices. Traps in regions of MOS isolation oxides under strong gate control can also contribute to low-frequency noise, especially for multifinger, multiedge devices irradiated to high doses. The effects of defects on the 1/f noise of GaN-based HEMTs and thin metal lines are illustrated for comparison.