C-Axis Oriented HZO on Flat Amorphous TiN Achieving High Uniformity, Breakdown Field, Final 2Pr, and Endurance

Abstract

Metal-ferroelectric-metal (MFM) capacitors with flat amorphous TiN are demonstrated to achieve the c-axis of orthorhombic phase (o-phase) well-aligned along the deposition direction, uniform electric field, negligible fatigue, and a high remanent polarization (2Pr) of $62 \; \mu $ C/cm2. The large lattice misfit between crystalline TiN and Hf0.5Zr0.5O2 (HZO) creates a larger barrier to form the o-phase HZO as compared to the amorphous TiN underlayer. Using chemical–mechanical polishing (CMP) can obtain a 0.3 nm roughness flat TiN, measured by atomic force microscopy (AFM). HZO on flat amorphous TiN exhibits a uniform and high breakdown field (EBD) of 4.8/−5.1 MV/cm for positive/negative voltage. A flat TiN mitigates the formation of oxygen vacancies (Vo) as compared to the rough TiN due to the weak and uniform electric field with few local extremes in HZO. After 4E12 endurance cycles, the HZO on the flat TiN exhibits a high final 2Pr of $56 \; \mu $ C/cm2 due to small dipole pinning by V $_{\text {o}}^{{2}+}$ . This work demonstrates the way to achieve uniformly high 2Pr, large EBD, and high endurance by the flat amorphous TiN.