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 (
$\mu _{\textrm {eff}}$
) 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
$\mu _{\textrm {eff}}$
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
$\mu _{\textrm {eff}}$
improvement and degrade transconductance (
$g_{m}$
). A two-end source line is proposed to reduce
$R_{S}$
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
$\mu _{\textrm {eff}}$
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
$\mu _{\textrm {eff}}$
and layout-dependent effects in multifinger devices.