QUANTIFICATION OF NANOSPREADING RESISTANCE PROFILING DATA

In nanospreading resistance, the resistance measured at a particular p osition on the sample cross section is not exclusively determined by t he carrier concentration at this position, but by the entire surroundi ng carrier profile. The correct evaluation of this spreading effect re quires a detailed calculation, leading to a deconvolution algorithm, w hich recovers the charge-carrier profile from the measured resistance profile. In this work, a general scheme for transforming a wide range of profiles is proposed. The scheme is based upon finite-element calcu lations of the potential distribution and the current spreading of a c ircular flat contact current source on a semi-infinite semiconductor s ample with known carrier distribution. A correction factor database is formed as a function of typical profile characteristics such as (i) t he distance to perfectly isolating or conducting boundaries, (ii) carr ier gradient, and (iii) carrier curvature. In routine operation the tr ansformation of resistance data into the carrier-concentration profile is done by interpolation of the database, hereby avoiding the time-co nsuming finite-element calculations. The latter results in a very fast calculation of the carrier profile data with an accuracy better than 10%, without any loss in spatial resolution. Examples are given that i llustrate the accuracy of the method. (C) 1998 American Vacuum Society .