Defect profiling in FEFET Si:HfO2 layers
Barry O’Sullivan, V. Putcha, Roman Izmailov, V. V. Afanas’ev, Eddy Simoen, Taehwan Jung, Y. Higashi, R. Degraeve, B. Truijen, B. Kaczer, N. Ronchi, S. R. C. McMitchell, Kaustuv Banerjee, Sergiu Clima, L. Breuil, G. Van den bosch, D. Linten, Jan Van Houdt
Abstract
Ferroelectric Si-doped HfO2 is a promising candidate for future generation memory devices. However, such devices are vulnerable to significant threshold voltage shifts resulting from charge trapping in oxide defects. We use complementary characterization and modeling techniques to reveal significant electron trapping/de-trapping behavior, together with a strong temperature dependence of the electron emission kinetics in ferroelectric layers, which results from the onset of polarization of the ferroelectric layer. This can lead to an apparent difference in the defect characteristics in ferroelectric-HfO2 compared to the paraelectric-HfO2 structures they are shown to closely resemble when this contribution is decoupled. The results demonstrate the presence of a defect band closely aligned to the silicon conduction band, which can easily be accessed during device operation.