Cryogenic behavior of high-permittivity gate dielectrics : the impact of atomic layer deposition temperature and the lithographic patterning method

Dielectrics featuring a high relative permittivity, i.e., high-k dielectrics, have become the standard insulators in gate architectures, enhancing the electrical performance of both room temperature and cryogenic electronics. This study delves into the cryogenic (3 K) performance of high-k dielectrics commonly used as gate insulators. We fabricated Al2O3 and HfO2 layers via atomic layer deposition (ALD) and extrapolated relative permittivity (k) and dielectric strength (EBD) from AC (100 Hz-100 kHz) and DC measurements on metal-insulator-metal capacitors. Our findings reveal a strong dependence of HfO2 cryogenic performance on ALD growth temperature, while the latter shows a negligible impact on Al2O3. We estimated similar to 9% and similar to 14% reductions in the relative permittivities of HfO2 and Al2O3, respectively, at temperatures from 300 to 3 K. Additionally, we designed and fabricatedAl(2)O(3)/HfO2 bilayers and checked their properties at cryogenic temperatures. The study also investigates the impact of the patterning method, namely, UV or electron-beam lithography (acceleration voltage of 10, 20, or 30 kV), on the high-k dielectric properties. (c) 2025 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license(https://creativecommons.org/licenses/by/4.0/).