Orientation Independent Growth of Uniform Ferroelectric Hf0.5Zr0.5O2 Thin Films on Silicon for High-Density 3D Memory Applications

The highly scalable ferroelectric hafnia-based thin films can be easily integrated into ferroelectric field-effect transistors (FeFETs) by existing Si technology, which are regarded as one of the promising candidates for fast read/write, energy-efficient, and high-density nonvolatile memories. However, device-to-device variation in threshold voltage (V-TH) caused by non-uniformity of ferroelectric properties is a serious challenge for implementing hafnia-based FeFETs in high-density nonvolatile memories. Here, the substrate-orientation independent growth of Hf0.5Zr0.5O2 (HZO) thin films is realized with uniform ferroelectricity by using HfO2 seed layers. The HfO2 seed layers are beneficial to improving the ferroelectric polarization of HZO thin films grown on differently oriented Si substrates and reducing the variation in ferroelectric properties. Moreover, device simulation confirms that the proposed scheme contributes to realizing uniform memory properties in 3D vertical HZO-based FeFETs. This study suggests the possibility to implement hafnia-based FeFETs into 3D vertical high-density memory.