Effect of atomic layer deposition process parameters on TiN electrode for Hf0.5Zr0.5O2 ferroelectric capacitor

Abstract

Hf0.5Zr0.5O2 (HZO), an innovative and exceptional ferroelectric material, exhibits remarkably high sensitivity, making it particularly vulnerable to electrode effect. Titanium nitride (TiN) is a commonly employed as electrode material in the complementary metal–oxide–semiconductor process. Optimizing the process parameters of preparing TiN film can alter matching degree with HZO capacitor, so as to find the optimal parameters of TiN process to improve ferroelectric property of HZO. In this study, the impact of key process parameters in atomic layer deposition (ALD) TiN, including cycle number, TiCl4 and NH3 pulse time, process temperature (Tp) on film thickness, crystalline phases of TiN, square resistivity (Rs), surface average roughness (Ra) and the root-mean-square roughness (Rq) of TiN film are comprehensively investigated. Through optimization, ∼10 nm ALD TiN film can achieve excellent uniformity of 0.43%, low Rs of 286.9 Ω/□, improved Ra and Rq of 1.82 Å and 2.28 Å. The results show that the maximum 2 times remnant polarization (2Pr) of the HZO ferroelectric capacitor with optimized TiN electrodes can reach 35.17 µC cm−2, and the switching cycle endurance exceeds 8 × 107.