Effect of guard-ring on the DC and high-frequency performance of deep-submicrometer metal oxide semiconductor field effect transistor

The influence of guard-ring (GR) on the direct current (DC) and high-frequency performance of deep-submicrometer metal oxide semiconductor field effect transistors (MOSFETs) is investigated in this study. MOSFETs with four different GRs are fabricated using 90 nm complementary metal oxide semiconductor (CMOS) process, and a detailed comparative study on their device performances is performed. A united DC and small signal equivalent circuit model that takes into the effect of GR is developed. A set of simple, but efficient formulas provide a bidirectional bridge for the S parameters transformation between devices with different GRs. The corresponding model parameters for MOSFETs with different GRs are determined from S parameter on-wafer measurement up to 40 GHz.