High capacitance density on-chip capacitor for Cu/SiO2 interconnect technology

The objective of this work is to achieve high capacitance density on-chip capacitor using 0.18 μm Cu/SiO₂ interconnect technology, compared with metal-insulator-metal (MIM) capacitor fabricated with existing mature techniques (700 Å silicon nitride as capacitor dielectric). Metal-insulator-metal-insulator-metal (MIMIM) structure was explored. Another approach, thin silicon nitride (300 Å) MIM capacitor was studied as reference. Capacitance densities of 1.7 and 1.9 fF/μm² have been achieved. Their DC and RF characteristics were studied and compared. Satisfactory characterization results were demonstrated. A simple and efficient MIM capacitor equivalent circuit model was applied in this study.