Surface Engineering of Ti–Pt Bottom Electrodes for Precise Texture Control of PZT Thin Films on Si

Growing ferroelectric films with different textures under identical process conditions poses a significant materials challenge. The texture of the ferroelectric films is largely influenced by the underlying substrate. Ti/Pt deposited on silicon is widely used as a bottom electrode and substrate for the growth of PZT thin films. In this study, we developed a novel two-step deposition process to engineer the surface of the Ti/Pt bottom electrode, enabling the growth of distinct (100) and (111) textured PZT thin films on different regions of the same silicon wafer. Using photolithography, we successfully sputter-deposited monolayer and bilayer Ti/Pt on separate regions of the wafer, allowing for controlled texture formation under identical processing conditions. We found that the bilayer Ti/Pt bottom electrode effectively suppressed Ti diffusion and oxide formation, critical factors for achieving (100) textured PZT growth. In contrast, the monolayer Ti/Pt exhibited Ti diffusion and oxide formation, leading to the growth of (111) textured PZT. Ferroelectric and piezoelectric measurements showed that (100) textured films exhibited enhanced piezoelectric and dielectric properties, ( d 33,f(100) = 115 pm/V, d 33,f(111) = 36 pm/V). These findings highlight the potential of surface-engineered Ti/Pt electrodes in optimizing PZT thin films for piezoelectric MEMS applications.