Measuring the effective channel length of the deep submicron MOSFET and channel broadening effect

This paper investigates the channel broadening effect by the n-LDD (n-Lightly Doped Drain) doping on the n-channel MOSFET. The n-LDD L_eff modulation is due to charge density distribution by the gate bias and the carrier distribution `spill out´ of the source and drain into the channel. In this work, we present deep submicron silicon n-LDD experimental results with a comparison of several well-known L_eff measurement techniques. Low n-LDD implant concentration modulates L_eff. As the n-LDD doping level increases, the channel length modulation effect is reduced, providing optimum device performance. Several MOSFET effective channel length, i.e., L_eff , extraction methods with constant gate drive were used to observe n-LDD L_eff modulation. It is found that a constant gate drive is required to provide accurate results particularly when severe SCE or RSCE are observed. The L_eff measurements indicate that several different methods investigated provide matching results only when constant gate drive is used