Process and temperature insensitive flicker noise monitor circuit
First Claim
1. A method for monitoring defects in wafers, the method comprising:
- selecting at least one area on each one of the wafers to fabricate a monitoring circuit, wherein the monitoring circuit includes representative devices to replicate similar devices located in a die area of the wafers;
measuring a differential signal generated by selected ones of the representative devices located on each one of the wafers, the differential signal being indicative of a noise caused by the defects present in the selected ones; and
digitizing the differential signal to provide a digital signal, the digitizing being performed by the monitoring circuit.
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Abstract
In an apparatus and method for monitoring defects in wafers, a monitoring circuit is fabricated on an area of each one of the wafers. The monitoring circuit includes representative devices that replicate similar devices located in a die area of the wafers. Defects if present in the representative devices contribute to a generation of a noise, thereby causing an imbalance in a differential signal measurable across selected ones of the representative devices. A digitizing circuit that uses a common mode voltage as a reference to measure the imbalance digitizes the differential signal to a digital signal, the digital signal being indicative of the noise generated by the defects. The digital signal is stored over a configurable time interval to form a digital bit stream. The digital bit stream is compared to a reference to determine whether the defeats are within an allowable range.
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Citations
12 Claims
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1. A method for monitoring defects in wafers, the method comprising:
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selecting at least one area on each one of the wafers to fabricate a monitoring circuit, wherein the monitoring circuit includes representative devices to replicate similar devices located in a die area of the wafers; measuring a differential signal generated by selected ones of the representative devices located on each one of the wafers, the differential signal being indicative of a noise caused by the defects present in the selected ones; and digitizing the differential signal to provide a digital signal, the digitizing being performed by the monitoring circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification