A novel high-density capacitor design and its fabrication technique based on selective etching

The design, fabrication, and characterization of a novel high-density metal-insulator-metal (MIM) multilayer capacitor is reported. In order to interconnect the multiple electrode layers without using numerous photolithography steps, a unique process was developed based on depositing MIM layers onto a substrate with two pillars, fine polishing to expose the multilayer cross sections, and then selectively etching the metals on each pillar to form the capacitor electrodes. For demonstration purpose, only capacitors with two dielectric layers were fabricated, with measurement results verified by a theoretical model. With a dielectric thickness of 200nm, a capacitance density of 0.54fF/μm² was achieved, which can be easily increased by decreasing dielectric thickness and increasing the number of MIM layers. The capacitor also exhibits low equivalent series resistance (ESR) of 300-700mohms, and can operate up to 63MHz.