Patent · US Expired

Method and system for locating and positioning circular workpieces

US4833790A · kind A · utility

31Cited by
5References
21Claims
0Family size

Assignee

Inventors

Key dates

Filing dateMay 11, 1987
Grant dateMay 30, 1989
Priority date—
Expiry dateMay 11, 2007

Classification

  • Technology area (CPC G)Physics
  • CPC primaryG01B7/31
  • WIPO fieldMeasurement
  • WIPO sectorInstruments

Abstract

A system for locating and positioning wafers includes a wafer shuttle, a spindle, and a position sensor. The wafer shuttle retrieves wafers from a storage location, typically a wafer cassette, and transports the wafers to the spindle. The wafers are then incrementally rotated on the spindle, and the distance between the center of rotation and the periphery of the wafer along a linear path is measured. By using three such measurements, the distance and angle with which the center of the wafer is offset from the center of rotation may be calculated. The wafer can then be centered on the spindle by rotation and translated a proper distance by the wafer shuttle. Usually, the wafers will be further rotationally oriented so that the crystal lattice lies in a desired direction.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.