System and method for characterizing silicon wafers
First Claim
1. 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.
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Abstract
A method and system is provided for characterizing silicon wafers. The method and system provide for measuring a resistance between a pair of points on an epitaxial layer of a wafer'"'"'s surface. The points may be substantially equidistant from the center of the wafer. The resistance measuring may be repeated at a series of pairs of points, each pair of points being radially spaced apart from an adjacent pair of points. The series of pairs of points may include a control group of pairs. A figure of merit may be calculated 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.
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Citations
31 Claims
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1. 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:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 25, 26, 27, 28, 29)
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13. A method for characterizing one or more silicon wafers, each wafer defining a center, a circular outer edge, and a front surface, each wafer including an epitaxial layer extending over the front surface from the center towards the outer edge, the method comprising:
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measuring a resistance between a pair of points on the epitaxial layer, the points being substantially equidistant from the center of the wafer;
repeating the step of resistance measuring 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;
calculating a figure of merit characteristic of the one or more wafers, 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. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 30)
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31. A system for characterizing a production run of silicon wafers, wherein a selected wafer from the production run defines a center, a circular outer edge, and a front surface, the selected wafer including an epitaxial layer extending over the front surface from the center toward the outer edge, the layer extending at least to within about 200 microns of the edge of the wafer, the system comprising:
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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.
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Specification