Ultrahigh Capacitance Density for Multiple ALD-Grown MIM Capacitor Stacks in 3-D Silicon

ldquoTrenchrdquo capacitors containing multiple metal-insulator-metal (MIM) layer stacks are realized by atomic-layer deposition (ALD), yielding an ultrahigh capacitance density of 440 at a breakdown voltage VDB> 6 V. This capacitance density on silicon is at least 10times higher than the values reported by other research groups. On a silicon substrate containing high-aspect-ratio macropore arrays, alternating MIM layer stacks comprising high-kAl2O3dielectrics and TiN electrodes are deposited using optimized ALD processing such that the conductivity of the TiN layers is not attacked. Ozone annealing subsequent to each Al2O3deposition step yields significant improvement of the dielectric isolation and breakdown properties.