An accurate gate length extraction method for sub-quarter micron MOSFET's

Abstract

By comparing measured and simulated gate-to-source/drain capacitances, C/sub gds/, an accurate gate length extraction method is proposed for sub-quarter micron MOSFET's applications. We show that by including the 2-D field effect on the fringing capacitance, the polysilicon depletion and the quantum-well effects in the C/sub gds/ simulation, the polysilicon gate length, L/sub poly/, can be accurately determined for device lengths down to the 0.1 /spl mu/m regime. The accuracy of this method approaches that of cross-sectional TEM on the device under test, but without destroying the device. Furthermore, we note that as a result of accurate L/sub poly/ extraction, the source/drain lateral diffusion length, L/sub diff/, and effective channel length, L/sub eff/, can also be determined precisely. The accuracy of L/sub diff/ is confirmed by examining their consistency with experimentally obtained 2-D source/drain profile.