Abstract
With Pd as electrode, crystalline TiO2-based MIM capacitors were found to demonstrate improved leakage current by adopting nitrogen plasma treatment 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 near 3 orders to be 4.610-7 A/cm2 at -1 V while maintaining high capacitance density of 25.2 fF/μm2. The major role of nanocrystals is to trap electrons and then suppress leakage current by inducing Coulomb blockade effect or building an internal field to compensate the applied external field. The MIM capacitors developed in this work also display other intriguing features in terms of small TCC of 88 ppm/℃, low loss tangent of 0.020 and satisfactory capacitance change of 1.74 % after 10-year operation under 2.5 V stress. The MIM capacitor technology not only exhibits the prominent performance which is advantageous over other TiO2-based capacitors, it also possesses the capability to implement low-leakage/high-reliability MIM capacitors for next generation circuits.