Reliability of Low-Temperature-Processing Hafnium Oxide Gate Dielectrics Prepared by Cost-Effective Nitric Acid Oxidation Technique

In this paper, the physical and electrical characteristics of low-temperature-processing hafnium oxide (HfO
₂
) films are studied. A simple cost-effective room-temperature process was introduced to prepare high-k HfO
₂
dielectrics. A novel technique of direct oxidation of an ultrathin Hf metal by nitric acid, followed by rapid thermal annealing in N
₂
is demonstrated. The prepared HfO
₂
gate dielectrics show good uniformity, low leakage currents, high breakdown field, and superior reliability under electrical stressing. The long-term ten-year lifetime was also evaluated by a time-dependent-dielectric-breakdown analysis to project the maximum operation voltage of -1.8 V for HfO
₂
gate stacks. This low-temperature oxidation technology for preparing high-quality high-k HfO
₂
dielectrics is promising for flat-panel-display applications.