Low inductance thin film capacitors for decoupling applications

Abstract

Low inductance and high capacitance density thin film capacitors using barium strontium titanate (BST) based thin films have been developed for use in decoupling applications for GHz LSI operations. Increasing clock frequency and integration density of high performance logic LSI such as CPU requires very low power line impedance over wide frequency ranges up to GHz order. Decoupling capacitors for GHz LSI are required having both high capacitance and low inductance. BST thin film capacitors are promising for GHz LSI applications due to excellent electrical properties such as low leakage current, high capacitance, and high temperature stability. Fundamental electrical properties of Pt/BST/Pt thin film capacitor structures were investigated. BST thin films deposited by RF magnetron sputtering achieved C/A = 4000 nF/cm/sup 2/ and leakage current density < 10/sup -9/ A/cm/sup 2/. The fabricated thin film chip capacitors show low equivalent series inductance (ESL) lower than 20 pH. Developed high capacitance low inductance capacitors are fabricated on Si wafers, therefore, it is very easy to integrate to system packaging.