Analysis of narrow gate to gate space dependence of MOS gate-source/drain capacitance by using contact-less and drawn-out source/drain test structure

A new test structure which can provide voltage to the very narrow source/drain region between adjacent gates by drawing out the source/drain silicide layer has been developed. By using the test structure, the dependence of the gate-drain capacitance (Cgd) on the gate-gate space (Lsp) has been successfully measured until the minimum gate pitch where no contact can be placed. Decrease of Cgd with respect to the decrease of Lsp has been observed and its main cause is identified as the decrease of the gate-drain overlap length.