Simulation analysis of impurity profile extraction by SCM

We investigate the propriety of SCM (scanning capacitance microscopy) for determination of impurity distribution of MOSFETs. Two-dimensional impurity distribution is converted from /spl Delta/C//spl Delta/V signal obtained by SCM. It is revealed that the SCM signal is quite sensitive to the effects of charge depletion around the pn junction, singularity of structure in vicinity of SiO/sub 2//Si interface (edge effect), and the work function of the gate electrode. Making use of process/device simulations to analyze these effects, it is found that the SCM signal near the channel surface region of the Si substrate contains large error due to the edge effects. The lateral extent of the source/drain region obtained by SCM shows reasonable agreement with that determined by measurements and simulations of electrical characteristics of the MOSFET.