Quantification of scanning capacitance microscopy imaging of the pn junction through electrical simulation

Determining the cross-sectional doping profile of very small metal–oxide–semiconductor field effect transistors and specifically the direct measurement of their channel length is necessary for true channel engineering to be possible. Scanning capacitance microscopy (SCM) has generated unprecedented images of the cross-sectional doping profiles of very small transistors. The bias voltage dependence of these images has motivated us to investigate the SCM technique in greater detail. Using electrical simulations, we have focused on the pn junction to establish the qualitative and quantitative relationship between the bias voltage and the pn junction location. The ability to confidently interpret the images produced with SCM will allow us to improve simulation models, trouble-shoot process flow, and determine the effective channel length of semiconductor devices.