The recently developed four 𝑅 sd extraction methods from a single device, involving the constant-mobility method, the direct 𝐼 d -𝑉gs method, the conductance method and the Y-function method, are evaluated on 32 nm n-channel metal-oxide-semiconductor field-effect transistors (nMOSFETs). It is found that 𝑅 sd achieved from the constantmobility method exhibits the channel length independent characteristics. The 𝐿-dependent 𝑅 sd extracted from the other three methods is proven to be associated with the gate-voltage-induced mobility degradation in the extraction procedures. Based on 𝐿-dependent behaviors of 𝑅 sd , a new method is proposed for accurate series resistance extraction on deeply scaled MOSFETs.