A Study on Imprint Behavior of Ferroelectric Hafnium Oxide Caused by High-Temperature Annealing

Hafnium oxide is found to be a favorable material for ferroelectric nonvolatile memory devices. Its compatibility with complementary metal-oxide-semiconductor processes, the relatively low crystallization temperature when zirconium-doped, and the thickness scaling are among the advantageous properties of hafnium oxide. Different requirements must be fulfilled for different applications of hafnium oxide. Herein, high-temperature annealing and operation conditions are analyzed in order to investigate nonvolatile memories for automotive applications. A strong imprint behavior (shift in coercive voltages) is observed after annealing hafnium-zirconium-oxide thin films at temperatures varied between 100 and 200 degrees C. The imprint behavior is a significant challenge in many applications. Therefore, to reduce/recover the undesirable imprint behavior caused by high-temperature treatment, two different ways are successfully examined and delineated here: endurance cycling and applying high electric fields.