Patent ID: 7474114

Claim:
A system for use in producing silicon wafers, wherein each wafer defines a center, a circular outer edge, a front surface, and an epitaxial layer on the front surface, the system including a capability for characterizing one or more of the wafers, the system comprising: an ohmmeter including two leads, each lead including a contact, the ohmmeter configured for measuring a resistance between a pair of points on the epitaxial layer, the points being substantially equidistant from the center of the wafer, the ohmmeter further being configured for measuring a series of resistances between a series of pairs of points, each pair of points being substantially radially spaced apart from an adjacent pair of points, the series of pairs of points including a control group of pairs; a computer, coupled to the ohmmeter to receive the series of resistances measured by the ohmmeter, the computer programmed to calculate a figure of merit, wherein the figure of merit is determined by subtracting from 1.0 the ratio of a minimum resistance of the resistances measured between the pairs of points to an average of the resistances measured between the pairs of points in the control group.