Direct measurement and characterization of n⁺ superhalo implants in a 120 nm gate-length Si metal–oxide–semiconductor field-effect transistor using cross-sectional scanning capacitance microscopy

We have directly measured nanoscale electronic features associated with a 120 nm physical gate length p-channel silicon metal–oxide–semiconductor field-effect transistor device structure including n⁺ superhalo implants using cross-sectional scanning capacitance microscopy (SCM). A dc bias-dependent voltage series of SCM images representing nine bias conditions from 2 to -2 V in 0.5 V steps was obtained. The SCM contrast observed varies with the ac and dc bias applied to the sample and allows delineation of the device features, including the p⁺ source and drain contacts, p⁺ source and drain extensions, p⁺ polycrystalline silicon gate, electrical p–n junction, n-well, and n⁺ superhalo implants. It is demonstrated that the superhalo implant features are imaged only under specific SCM bias conditions. Detailed analysis of the resulting SCM contrast indicates an apparent channel length of 73±11 nm, and reveals clear asymmetry in the individual lobes of the n⁺ superhalo implant features. © 2002 American Institute of Physics.