A New Method for Accurate Extraction of Source Resistance and Effective Mobility in Nanoscale Multifinger nMOSFETs

A new method is is developed for accurate extraction of the effective mobility (μ_eff) in the multifinger nMOSFETs with various poly-to-poly (PO-PO) spaces. The wide PO-PO space intends to increase the tensile stress from a contact etching stop layer (CESL) and yields higher μ_eff in the nMOSFETs. However, the source resistance (R_S) emerges as a critical parasitic element in the multifinger devices with a large finger number. The wide PO-PO space generally leads to the further increase of R_S, which may offset μ_eff improvement and degrade transconductance (g_m). A two-end source line is proposed to reduce RS and the impact on g_m. The complicated layout-dependent effects containing the CESL strain, R_S, and 3-D fringing capacitances bring a crucial challenge to the μ_eff extraction. In this paper, a distributed transmission line model is derived for a reliable determination of R_S, which is a key to the realization of accurate extraction of μ_eff and layout-dependent effects in multifinger devices.