Orientation Independent Growth of Uniform Ferroelectric Hf_(0.5)Zr_(0.5)O_2 Thin Films on Silicon for High-Density 3D Memory Applications

摘要

The highly scalable ferroelectric hafnia-based thin films can be easilyintegrated into ferroelectric field-effect transistors (FeFETs) by existing Sitechnology, which are regarded as one of the promising candidates for fastread/write, energy-efficient, and high-density nonvolatile memories. However,device-to-device variation in threshold voltage (V_(TH)) caused by non-uniformityof ferroelectric properties is a serious challenge for implementing hafniabasedFeFETs in high-density nonvolatile memories. Here, the substrateorientationindependent growth of Hf_(0.5)Zr_(0.5)O_2 (HZO) thin films is realizedwith uniform ferroelectricity by using HfO2 seed layers. The HfO2 seedlayers are beneficial to improving the ferroelectric polarization of HZO thinfilms grown on differently oriented Si substrates and reducing the variationin ferroelectric properties. Moreover, device simulation confirms that theproposed scheme contributes to realizing uniform memory properties in 3Dvertical HZO-based FeFETs. This study suggests the possibility to implementhafnia-based FeFETs into 3D vertical high-density memory.