Apparatus and methods for resistivity testing
First Claim
1. In an automatic sheet resistance mapping system for semiconductor wafers having a capability of taking multiple test readings in both contour scan and diameter scan modes, in combination:
- a rotatable wafer stage for carrying a semiconductor wafer thereon with a center of said wafer positioned substantially at an axis of rotation of said wafer stage;
a probe head assembly including a linear array of at least four equally spaced probe tips projecting from one surface thereof;
mounting means for mounting said probe head assembly with said one surface facing said wafer stage and for moving said array of probe tips alternately into and out of contact with the surface of a wafer carried on said wafer stage;
first positioning means for rotating said wafer stage to accurately registered angular test positions; and
second positioning means for producing translation between said wafer stage and said probe head assembly to position said array of probe tips at accurately registered radial test positions relative to the center of said wafer;
said first and second positioning means being operable in said diameter scan mode to locate said probe tips at a multiplicity of successive closely spaced test positions along a diameter line of said wafer and being operative in said contour scan mode to locate said probe tips at a two-dimensional array of different test positions across an area of said wafer;
said mounting means including means for mounting said probe head in a prearranged alignment position with said linear array of probe tips oriented at a prearranged small acute angle to said diameter line of said wafer as said second positioning means move said probe tips along said diameter line such that said probe tips each define a track of separated test probe footprints on said wafer in said diameter scan mode.
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Accused Products
Abstract
An automatic sheet resistance mapping system for semiconductor wafers which has the capability of taking high accuracy, multiple test readings in both contour scan and diameter scan modes. A rotatable wafer stage carries a semiconductor wafer thereon with the center of the wafer positioned substantially at the axis of rotation of the wafer stage. A probe head assembly, including a linear array of at least four equally spaced probe tips projecting from one surface of the assembly is mounted facing the wafer stage on an arrangement for moving the probe tips alternately into and out of contact with the surface of a wafer carried thereon. Positioning arrangements are provided for rotating the wafer stage to accurately registered angular test positions and for producing translation between the wafer stage and the probe head assembly to position the array of probe tips at accurately registered radial test positions relative to the center of the wafer. The positioning arrangements are operable in a diameter scan mode to locate the probe tips at a multiplicity of successive, closely spaced test positions along a diameter line of the wafer and are operative in a contour scan mode to locate the probe tips at a two-dimensional array of different positions across the area of the wafer. The mounting arrangement for the probe head positions the probe head in a prearranged alignment position with the linear array of probe tips oriented at a prearranged small acute angle to a radius line so that the test probe tips each define a track of separated test probe footprints on the wafer in the diameter scan mode.
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Citations
12 Claims
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1. In an automatic sheet resistance mapping system for semiconductor wafers having a capability of taking multiple test readings in both contour scan and diameter scan modes, in combination:
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a rotatable wafer stage for carrying a semiconductor wafer thereon with a center of said wafer positioned substantially at an axis of rotation of said wafer stage; a probe head assembly including a linear array of at least four equally spaced probe tips projecting from one surface thereof; mounting means for mounting said probe head assembly with said one surface facing said wafer stage and for moving said array of probe tips alternately into and out of contact with the surface of a wafer carried on said wafer stage; first positioning means for rotating said wafer stage to accurately registered angular test positions; and second positioning means for producing translation between said wafer stage and said probe head assembly to position said array of probe tips at accurately registered radial test positions relative to the center of said wafer; said first and second positioning means being operable in said diameter scan mode to locate said probe tips at a multiplicity of successive closely spaced test positions along a diameter line of said wafer and being operative in said contour scan mode to locate said probe tips at a two-dimensional array of different test positions across an area of said wafer; said mounting means including means for mounting said probe head in a prearranged alignment position with said linear array of probe tips oriented at a prearranged small acute angle to said diameter line of said wafer as said second positioning means move said probe tips along said diameter line such that said probe tips each define a track of separated test probe footprints on said wafer in said diameter scan mode. - View Dependent Claims (2, 3, 4, 5)
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6. In an automatic sheet resistance mapping system for semiconductor wafers having a capability of taking multiple test readings in both contour scan and diameter scan modes, in combination:
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a rotatable wafer stage for carrying a semiconductor wafer thereon with a center of said wafer positioned substantially at an axis of rotation of said wafer stage; a probe head assembly including a linear array of four probe tips projecting from one surface thereof and being equally spaced for each other by a known separation; mounting means for mounting said probe head assembly with said one surface facing said wafer stage and for moving said array of probe tips alternately into and out of contact with the surface of a wafer carried on said wafer stage; first positioning means for rotating said wafer stage to accurately registered angular test positions; and
second positioning means for producing translation between said wafer stage and said probe assembly to position said array of probe tips at accurately registered radial test positions relative to the center of said wafer;said first and second positioning means being operable in said diameter scan mode to locate said probe tips at a multiplicity of successive, closely spaced test positions along a diameter line of said wafer and being operable in said contour scan mode to locate said probe tips at a two-dimensional array of widely spaced test positions distributed across an area of said wafer surface; said test probe assembly including a cylindrical body portion and flange on one end of said body portion opposite said probe tips; said mounting means including clamping means for releasably clamping said cylindrical body portion of said test probe assembly in a fixed orientation and a stop means carried on said clamping means at a registered position and adapted to contact said flange of said test probe assembly to establish a preselected alignment position of said probe head assembly such that said linear array of probe tips is oriented at a prearranged small acute angle to said diameter line of said wafer along which said probe head assembly is moved by said second positioning means, said angle having a magnitude selected as a function of said known probe tip separation such that each of said probe tips defines a separate track of test point footprints in said diameter scan mode while maintaining a substantially radial oreintation of said probe tips for improved measurement accuracy at test positions near an edge of said wafer in both said diameter scan mode and sand contour scan mode. - View Dependent Claims (7, 8)
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9. In a method of performing sheet resistance mapping measurements on a semiconductor wafer in a diameter scan mode, the steps of:
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disposing a probe head assembly with a linear array of separated probe tips thereon adjacent a surface of said wafer with said linear array oriented at a prearranged small acute angle of orientation to a radius line of said wafer such that probe tip footprints made by contact with said wafer surface will be separated in a direction orthogonal to said radius line; translating said probe head assembly relative to said wafer along said radius line to position said probe tips at a multiplicity of closely spaced test point locations while maintaining a constant acute angle of orientation of said probe tip array relative to said radius line; and contacting said wafer surface with said probe tips at each test point location, thereby producing separate tracks of test probe footprints along said radius line. - View Dependent Claims (10, 11, 12)
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Specification