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Wafer Spin-Up Algorithm for Detection Scanning

IP.com Disclosure Number: IPCOM000039869D
Original Publication Date: 1987-Aug-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Batchelder, JS: AUTHOR

Abstract

The data detection rate of any wafer-scanning microscope can be kept constant by varying the rate of rotation in relation to a scanning detector. In a wafer-scanning inspection tool, the detector arrays are oriented such that the wafer can be translated under the detection optics in one direction at a uniform velocity. This allows for fast wafer scanning since every detector element is able to observe a strip of wafer that is different from that seen by other detectors. For example, the detectors could form a line, and the wafer is then moved perpendicular to that line. However, in order to produce data at the fullest rate of speed, the wafer must also be scanned at a uniform velocity over its entire surface.

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Wafer Spin-Up Algorithm for Detection Scanning

The data detection rate of any wafer-scanning microscope can be kept constant by varying the rate of rotation in relation to a scanning detector. In a wafer- scanning inspection tool, the detector arrays are oriented such that the wafer can be translated under the detection optics in one direction at a uniform velocity. This allows for fast wafer scanning since every detector element is able to observe a strip of wafer that is different from that seen by other detectors. For example, the detectors could form a line, and the wafer is then moved perpendicular to that line. However, in order to produce data at the fullest rate of speed, the wafer must also be scanned at a uniform velocity over its entire surface. Uniform wafer velocity can be obtained by mounting the wafer on a spinning platform and translating the optical head over the wafer in a manner similar to a loose arm over a record. Linear velocities of tens of meters per second of wafer under the detector are easily possible. To keep the data rate from the detector constant during a scan, the rate of rotation of the wafer will have to increase as the detector array moves radially towards the center of the wafer inversely as the radial distance from the wafer center to the detector.

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