The Two‐Level Effect in Sheet Resistance Measurements Made with a Four‐Point Probe

Abstract

Sheet resistance measurements by the four‐point probe technique have been investigated on diffusions into opposite‐type backgrounds with junction depths from 0.25 to 3.0 µm. Sheet resistances, measured with a probe each of whose four points was weighted with 30–60g and whose tips were five mils in radius, were independent of this loading between 34 and 1570 ohms/sq. As the voltage is varied, sheet resistances show a two‐level effect, followed by a breakdown at 5.5V. The transition takes place, independent of the sheet resistance, at a constant voltage of 100 mV. This transition is explained by the correction factors for a four‐point probe derived from the multilayer potential distribution theory.