Simple nondestructive extraction of the vertical channel-impurity profile of small-size metal–oxide–semiconductor field-effect transistors

An improved method for extracting the vertical channel-impurity profile [Nsub(x)] of metal–oxide–semiconductor field-effect transistors (MOSFETs) from measured threshold–voltage dependence on bulk–source voltage is proposed. Previous restriction to slowly varying Nsub(x) is overcome by approximating Nsub(x) as a simple analytic function. Application to advanced MOSFETs with steep pileup or retrograded channel profiles and channel length down to 100 nm becomes possible. Extracted analytic profiles are additionally useful for modeling of Nsub(x)-dependent MOSFET phenomena, e.g., the reverse-short-channel effect.