Polymorphic Hf(Zr)O2-Based Films for High-k Dielectrics

Abstract HfO2/ZrO2-based (HZO) materials are promising high-k dielectrics for integrated capacitors and advanced electronic devices. However, their performance is fundamentally constrained by polymorph competition and the trade-off between the dielectric constant and leakage current. Here, we report a stacking-engineered strategy that integrates HZO layers with optimized ferroelectric and dielectric properties separated by an Al2O3 interlayer (HAZO). A nonswitching pulse measurement is employed to exclude polarization-switching contributions and directly probe the intrinsic dielectric response. The optimized HAZO dielectric exhibits an enhanced dielectric constant while simultaneously suppressing leakage and improving the dielectric breakdown characteristics. Structural characterizations reveal that the engineered stacking stabilizes the coexistence of nonpolar tetragonal and polar orthorhombic phases and increases the phase-boundary density. This polymorphic configuration suppresses irreversible domain switching and enables a stable enhanced dielectric response. These results establish a robust pathway toward high-performance HZO-based dielectrics and provide key insights into tailoring dielectric properties through polymorphic-phase engineering.