Deposition-Driven Phase Evolution in Hf1-x ZrxO2 Enabled by a Thermally Stabilized Cyclopentadienyl Precursor System

초록

Hf1-xZrxO2 (HZO) thin films have attracted considerable attention as promising ferroelectric materials for next-generation devices. The ferroelectric orthorhombic phase requires high-temperature annealing to crystallize. However, such thermal treatments are incompatible with back-end-of-line (BEOL) processes (<= 400 degrees C) and often degrade film quality, increase leakage, and reduce endurance. This paper demonstrates the use of thermally stabilized cyclopentadienyl-based hafnium and zirconium precursors that enable the direct crystallization of HZO films during atomic layer deposition at elevated growth temperatures, thereby eliminating the need for postdeposition annealing. Structural evolution and capacitor performance are systematically investigated within a wide deposition window (250-360 degrees C). This investigation demonstrates that increasing the deposition temperature enhances thin-film crystallization but inevitably promotes the monoclinic phase, which can be effectively suppressed through Zr-rich compositional control. Consequently, HZO thin films deposited at 360 degrees C exhibit robust ferroelectricity without the need for annealing, characterized by 2P(r) approximate to 27.56 mu C/cm(2), endurance exceeding 10(9) cycles, low leakage current, and symmetric coercive fields. These findings provide fundamental insights into deposition-induced phase stabilization and establish a practical pathway for the annealing-free integration of ferroelectric HZO under BEOL-compatible thermal budgets.

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