Epitaxial staircase structure for the calibration of electrical characterization techniques

Frequently electrical characterization techniques [such as the spreading resistance probe (SRP)], rely on the availability of a set of well-calibrated, homogeneously doped Si samples to establish the calibration curves (and parameters) necessary for the conversion of resistance measurements into carrier profiles. Although ideally such a calibration should be verified daily, in practice, time considerations limit the dairy verification to one (or a few) calibration samples. To remedy this situation a special multilayer Si structure has been grown consisting of a decreasing B-doped staircase containing seven Rat 4-5 mu m thick calibration layers doped from 10(20)/cm(3) down to 10(15)/cm(3) separated by slightly (factor 2-3) higher doped 1-2 mu m thick interface layers. The latter are included to facilitate the SRP calibrations as the SRP correction factor within the calibration layers now becomes very close to one. Since presently, a calibration curve can be generated quickly from a single measurement, daily measurements over a period of several months clearly indicate concentration-dependent drifts of the SRP-calibration curve. In addition to the calibration purposes we will demonstrate that this sample also can be used for the direct comparison of SRP, nano-SRP, scanning capacitance microscopy (SCM), and selective etching, etc. in terms of their dynamic range, quantification properties, and sensitivity. (C) 1998 American Vacuum Society.