A Reliable Metric for Mobility Extraction of Short-Channel MOSFETs

When comparing the extracted carrier mobility of long- and short-channel transistors, special consideration must be given to the metallurgical gate length $(L_{\rm met})$, neglecting the impact of source and drain junction profiles. $L_{\rm met}$ can be identified with nanometer precision by using RF split-$C$ –$V$ measurements, and physical and electrical analysis can demonstrate the accuracy of the method. Another important parameter, the external transistor resistance $(R_{\rm sd})$, can be identified with linear current measurements of short-channel devices. However, it is important to quantify the mobility dependence from the gate length in order to obtain an accurate result. A method to estimate the electrical field $(E_{\rm eff})$ of short-channel devices is proposed. The extracted short-channel mobility shows a universal behavior identical to the classical long-channel one.