Polarization and Reliability Enhancement for Ferroelectric Capacitors by Interface Engineering Through Crystalline TaN

A stack formed by consecutive deposition of 2 nm TaN/10 nm HfZrOx (HZO)/2 nm TaN in an ALD tool was proposed to be sandwiched between thick PVD TiN as the promising structure for ferroelectric capacitors (FeCAPs). Compared to the ALD TiN counterpart, ALD TaN exhibits a smaller coefficient of thermal expansion and a reduced lattice misfit between the electrode and HZO, enhancing remanent polarization (Pr). Additionally, ALD TaN demonstrates a larger barrier height with respect to HZO, contributing to improved reliability. The advantages of ALD-TaN FeCAPs over ALD-TiN FeCAPs are evidenced by a large operating field of 2.75 MV/cm for a 10-year lifetime with improvement of 0.15 MV/cm, a high 2Pr value of 38 $\mu \text{C}$ /cm2 with enhancement by 26.6%, and robust endurance of $3\times 10^{{10}}$ cycles with extension by 100X. The process holds the great potential to implement FeCAPs for high-reliability storage applications in AI era.