[22p-A307-1~17] CS.7 Code-sharing Session of 6.1 & 13.3 & 13.5

[22p-A307-2] Field-Induced Polar-Axis Alignment for 3D High-Density Memory

〇Zhuo Li¹, Jixuan Wu¹, Xiaoran Mei¹, Xingyu Huang¹, Takuya Saraya¹, Toshiro Hiramoto¹, Takanori Takahashi², Mutsunori Uenuma², Yukiharu Uraoka², Masaharu Kobayashi^1,3 (1.IIS., Univ. of Tokyo, 2.NAIST, 3.d.lab, Univ. of Tokyo)

Keywords:FeFET, Hafnium Oxide

Ferroelectric FETs (FeFETs) have been attracting much attention for high speed and low power with the use of CMOS-compatible Fe-HfO₂. In addition, 3D vertical stack FeFETs can achieve more for high-density storage memory, with two additional challenges. 1) Typically, PVD cannot be used for conformal deposition in 3D structure. Thus ALD deposition is needed in a high-aspect ratio trench structure. 2) Fe-HfO₂ is usually poly-crystalline and does not assure out-of-plane polarization in as-grown layers. But it has to have out-of-plane polarization with respect to any type of surface in 3D structure. We consider how the polar-axis is aligned under the electric field. In this study, we theoretically investigate the polar-axis transition of FE-HfO₂ using the first-principle simulation, and experimentally fabricated HfZrO₂ films to observe and analyze grain crystal orientations. We confirmed polar-axis transition from in-plane to out-of-plane in Fe-HfO₂. This finding is useful in that Fe-HfO₂ can maximize the polarization for memory operation on any type of surface in 3D structure.