Achieving High Dielectric Constants in Tetragonal Single‐Phase ZrHfO2 Thin Films through the Atomic Layer Deposition Process Using a Mixed Precursor

Abstract

Herein, the deposition of homogeneous ZrxHf(1−x)O2 (x < 1) thin films for dynamic random‐access memory (DRAM) capacitor dielectric layers by atomic layer deposition (ALD) using a mixed precursor mixture of two precursors is investigated. ZrO2‐ and HfO2‐based thin films are widely used as capacitor dielectric layers because of their high dielectric constant (k) values and low leakage current properties. Herein, particularly, films with mixed structures of ZrO2/HfO2 are investigated because ZrO2 supports the growth of HfO2 in the tetragonal phase. However, the mixed structures deposited by ALD remain inhomogeneous even after the annealing process. The inhomogeneity results in part of the HfO2 remaining in the monoclinic phase, which reduces the k value. Herein, the formation of homogeneous tetragonal‐phase ZrxHf1−xO2 using a mixed precursor consisting of CpZr and CpHf precursors is investigated. The formation of the tetragonal phase in the ZrxHf(1−x)O2 thin films is determined through chemical and structural analysis. The variation of the electrical properties with the Zr/Hf concentration ratio is investigated. The electrical properties are enhanced compared to laminated ZrO2/HfO2 and single thin films.