Abstract: A wafer edge-defect detection system with a probe assembly having one or more capacitive plates conforming in edge shape to an edge shape of a wafer; and processing electronics for electronically driving the one or more capacitive plates and for sensing an electrical signal representing capacitance between each one or more plates and the wafer. Filtering and demodulation techniques enhance the signal to noise ratio.

Abstract: A wafer edge detection system comprising a probe assembly having one or more capacitive plates conforming in edge shape to an edge shape of a wafer; and processing electronics for electronically driving the one or more capacitive plates and for sensing an electrical signal representing capacitance between each one or more plates and the wafer. Filtering and demodulation techniques enhance the signal to noise ratio.

Abstract: Apparatus and methods for calibrating a transducer measurement system having a plurality of subsystems, permitting total system calibration by a few selected adjustments without requiring complete system calibration when a new subsystem is added or a subsystem replaced and without requiring adjustments to be made to each individual subsystem. The measurement system provides a calibrated measurement signal indicative of a characteristic of an object with which the transducer interfaces. Each subsystem is characterized in terms of a minimum number of parameters associated therewith and the parameters are mathematically combined to reflect values of adjustable subsystem or system components. In this manner, variations associated with each separable subsystem from nominal, specified values, are combined and corrected by a single adjustment of a minimum number of selected adjustable components representing the degrees of freedom for errors in the system.

Abstract: Apparatus and methods for calibrating a transducer measurement system having a plurality of subsystems, permitting total system calibration by a few selected adjustments without requiring complete system calibration when a new subsystem is added or a subsystem replaced and without requiring adjustments to be made to each individual subsystem. The measurement system provides a calibrated measurement signal indicative of a characteristic of an object with which the transducer interfaces. Each subsystem is characterized in terms of a minimum number of parameters associated therewith and the parameters are mathematically combined to reflect values of adjustable subsystem or system components. In this manner, variations associated with each separable subsystem from nominal, specified values, are combined and corrected by a single adjustment of a minimum number of selected adjustable components representing the degrees of freedom for errors in the system.

Abstract: A conductivity-type sensor, typically for use in a wafer sorting system, for detecting the conductivity-type of semiconductor wafers. In measuring conductivity, a two-contact probe is applied to the semiconductor wafer and any static charge which may have been accumulated on the wafer is initially discharged at an accelerated rate. The charge state is measured and an acceptable level of discharge requires repeated indications of discharge below a predetermined level. Discharging and charge measurement is repeated a predetermined number of times as necessary to accomplish discharging or the wafer identified as defective. The conductivity-type of the discharged wafer is read from the rectified polarity of an oscillating signal applied to the contacts. A valid indication of conductivity-type requires two consecutive readings of the same conductivity-type.

Abstract: An automatic wafer alignment station is disclosed for aligning a wafer having flats about its centroid with the flats oriented in a preselected spatial direction. The wafer is held by a vacuum chuck which is operatively connected to a motor driven carriage for controlled movement about an X axis, to a .theta. actuator carried by the carriage for controlled rotation about the axis of the chuck, and to a Z actuator carried by the carriage for controlled motion about a Z axis. An X capacitive sensor and a Z capacitive sensor are positioned near the wafer. An X processing and Z compensating circuit is responsive to the X and the Z capacitive sensor output signals and provides an electrical signal that has values which exclusively represent the position of the edge of the wafer along the X axis only over a predetermined angular range. Circuit means including an A/D converter and a microprocessor respond to the electrical signal and produce a plurality of corrective signals to the X, Y, and .theta.