A Study on the Effects of High-k Interfacial Layer on Ferroelectric Hf0.5Zr0.5O2 Capacitor Characteristics

Abstract

Ferroelectric devices are attracting attention as a next-generation memory device for processing increasingly large amounts of data. However, in order to commercialize a device using ferroelectric, the interface reaction between the HfO2-based ferroelectric thin film and the Si substrate is a problem to be solved. In this study, we investigated interfacial reaction suppression by inserting a high-k interfacial layer (IL) and increasing its potential as a memory device. A capacitor with metal-ferroelectric-IL-Si (MFIS) structure was fabricated by depositing IL on a highly doped P-type Si wafer by ALD. Three types of thin films, HfO2, ZrO2, and La2O3, were used as the IL. 10 nm of Hf0.5Zr0.5O2 (HZO) deposited by ALD was used as ferroelectric thin film, and W was deposited with a sputter to form the top electrode. Crystallization of the thin film was achieved by annealing at 600°C for 10 s with RTA. 2 remanent polarization (Pr) value of about ~ 40 μC/cm2 and a coercive field (Ec) value of ~ 8 V were obtained through a polarization-voltage hysteresis loop. And the ratio of orthorhombic phase was increased through IL insertion. This is because IL improves the ferroelectric properties by acting as an oxygen scavenger that increases the oxygen vacancy of HZO. Our results provide the possibility of improving characteristics through IL insertion into memory devices.