Effect of top electrode on interfacial layer formation and polarization switching kinetics in post-deposition annealed Hf0.5Zr0.5O2 capacitors

초록

HfO2-based ferroelectric thin films have attracted considerable attention for advanced electronic applications. Their ferroelectricity stems from a metastable polar orthorhombic phase, strongly influenced by post-annealing processes. While the effect of top electrode materials on the ferroelectric properties has been extensively investigated in post-metallization annealed samples, it remains underexplored in post-deposition annealed samples. Here, we investigated the ferroelectric properties of 5-nm-thick Hf0.5Zr0.5O2 (HZO) capacitors subjected to post-deposition annealing (PDA), with W, Mo, and TiN top electrodes. High-resolution transmission electron microscopy revealed that the formation of interfacial dead layers at the top interface varied with electrode material, significantly affecting polarization–voltage hysteresis and polarization switching speed. Notably, W/HZO/TiN capacitors, exhibiting negligible dead layers, showed enhanced ferroelectricity at lower operating voltages and achieved the fastest polarization switching. This work highlights that top electrode selection can be a critical factor even in PDA-treated ferroelectric HZO capacitors, providing valuable guidance for future device design.

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