Heavy Ion Irradiation Effects on Structural and Ferroelectric Properties of HfO2 Films

The novel thin-film ferroelectric material hafnium oxide has revived the interest into ferroelectric memory concepts, which is due to the fact, that it facilitates CMOS and BEoL compatible integration. A major requirement hereby is the stability of the ferroelectric layer towards ionizing radiation, such as gamma and heavy ion exposure. In this study, we investigate for the first time the influence of heavy ion irradiation on the crystallographic and ferroelectric properties of hafnium oxide based thin films. We show, that up to fluences of 1010 ions/cm2 of Au26+ ions with an energy of 1.635 GeV both the crystallographic and ferroelectric properties of Si:HfO2 (HSO) and Hf0.5Zr0.5O2 (HZO) keep unchanged. For higher dosages, a soft affection can be observed, which is retrieved to be a result of irradiation supported phase transition. The results of this study will help to implement ferroelectric memories into aviation and space applications.