Method and apparatus for determining the center and orientation

Details Method and apparatus for determining the center and orientation Method and apparatus for determining the center and orientation

1996-03-29

1998-10-13

Shah, Kamini

Boots, shoes, and leggings

702150, 33520, 33549, 33644, G01B 713, G01B 900

Patent

active

058222138

ABSTRACT:
A device and method for determining the center and orientation of a circular workpiece such as a semiconductor wafer. A laser diode projects a sheet of light onto a linear array of charge coupled devices which measures light intensity as a semiconductor wafer is rotated with its outer periphery intersected by the sheet of light. From a plot of light intensity data versus position at the wafer edge, a derivative of such plot can be calculated to locate an orientation notch or flat in the edge of the wafer. Also, from the plot of light intensity versus edge position it is possible to locate the center of the wafer relative to a rotation axis of a spindle on which the wafer is supported.

REFERENCES:
patent: 4819167 (1989-04-01), Cheng et al.
patent: 5291270 (1994-03-01), Koch et al.
patent: 5365672 (1994-11-01), Kato
patent: 5466945 (1995-11-01), Brickell et al.
patent: 5497007 (1996-03-01), Uritsky et al.

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