TiO2-based MIM capacitors featuring suppressed leakage current by embedding Ge nanocrystals

Abstract

With Pd as the electrode, crystalline TiO₂-based MIM capacitors were found to demonstrate improved leakage current performance when nitrogen plasma treatment was adopted due to the passivation of grain boundary related defects. Through the introduction of Ge nanocrystals into crystalline TiO₂, the leakage current can be further suppressed by more than 3 orders of magnitude to 1.1 × 10⁻⁷ A cm⁻² at −1 V while maintaining a high capacitance density of 25.2 fF μm⁻². The major role of the nanocrystals is to trap electrons and then suppress leakage current by inducing the Coulomb blockade effect or building an internal field to compensate the applied external field. The MIM capacitor technology not only exhibits performance which is notably advantageous over other TiO₂-based capacitors, it also possesses the capability to be implemented in low-leakage/high-reliability analog and mixed signal MIM capacitors for next generation circuits.