Optimizing Al Doped Hafnium Oxide in 3D Trench Capacitors for Energy Storage Applications

Aluminum-doped hafnium oxide was deposited in 3D trench Metal-Insulator-Metal capacitors on 300 mm silicon wafers at different deposition temperatures. The aluminum concentration (4.2 at% Al) was optimized for the antiferroelectric-like phase to achieve the best energy storage capacity and efficiencies. Further, the role of frequency in the polarization-electric field hysteresis curves are examined for selecting the operating conditions. The effect of geometry of the trench diameters is tested for highest energy storage and mechanical stability of the devices. It was found with changing the aspect ratio, increasing the pitch width, maintained good mechanical stability. The increased aspect ratio resulted in increased recoverable energy storage density in comparison to the planar capacitor. Endurance tests for the trench capacitors lasted for 108 polarization cycles at 3 MV/cm at various temperatures up to 125°C.