Improved leakage and fatigue properties of W/Hf0.5Zr0.5O2/W capacitor through the insertion of Pt metallic layer

Abstract

The successful integration of Hf_0.5Zr_0.5O₂ (HZO) ferroelectric (FE) thin film into memory devices necessitates addressing the challenges associated with achieving high remanent polarization (P_r) and low leakage current, in order to ensure excellent reliability. The limitations of HZO film are overcome in this paper through the design of a Pt/W bilayer electrode, wherein a thin Pt metallic layer (ML) is embedded at the top interface of the W/HZO/W capacitor. This innovative approach combines the unique advantages offered by both W and Pt electrodes. The results reveal that the 2P_r values of the W/HZO/5 Pt/W and W/HZO/10 Pt/W capacitors, with Pt ML thicknesses of 5 nm and 10 nm, respectively, are slightly lower at 42.1 μC/cm² and 35.9 μC/cm² compared to the reference W/HZO/W capacitor's value of 47.9 μC/cm². This notwithstanding, these 2P_r values still maintain comparability with previously reported findings. Moreover, compared to the reference W/HZO/W capacitor, the W/HZO/10 Pt/W capacitor exhibits a reduction of one order of magnitude in leakage current, a 30 % increase in breakdown field from 3.0 MV/cm to 3.9 MV/cm, and an improvement of one order of magnitude in endurance performance, reaching 1.3 × 10⁸ cycles. This improvement can be attributed to the incorporation of a thin Pt ML, which enhances the schottky barrier and prevents potential oxidation of adjacent W electrode near the HZO film, effectively alleviating the leakage current. The present work demonstrates the successful mitigation of leakage current and improved fatigue properties while preserving FE characteristics through strategic insertion of Pt ML. The research findings can offer valuable scientific guidance for optimizing the performance of HZO-based devices.