High-Density MIM Capacitors With Porous Anodic Alumina Dielectric

We report on the fabrication and electrical characterization of MIM capacitors using as dielectric a thin porous anodic alumina layer between two Al films. The Al₂O₃/Al stack is grown electrochemically by partly anodizing an Al film on Si, while a top Al film is then deposited on the aluminum oxide and patterned in order to define the capacitor area. The obtained MIM capacitors exhibit at the same time large capacitance density (above ~5 fF/μm²), low leakage current density (below ~10^-9 A/cm² at 2 V), and good thermal stability of operation, demonstrated by an a coefficient that changes by less than 10% for temperature changes of the order of 100 K. The temperature stability is further demonstrated by the low leakage current density (below ~7 × 10^-9 A/cm²) even at temperatures as high as 420 K.