Resources Contact Us Home
Method and apparatus for determining the center and orientation of a wafer-like object

Image Number 3 for United States Patent #5822213.

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.

  Recently Added Patents
Handheld electronic device with text disambiguation employing advanced editing feature
Liquid crystal display having wide viewing angle
Systems and methods for cryopreservation of cells
Tone enhancement bracket
Agglutination judgment method
System and method for displaying a constant time selection context menu interface
  Randomly Featured Patents
Method for manufacturing an electronic assembly
Separation of hydrocarbons from oil shales and tar sands
Hybrid electric vehicle
Oxadiazole substituted indazole derivatives for use as sphingosine 1-phosphate (S1P) agonists
Toner for developing electrostatic image and method for forming multicolor image
Document and card positioning device with spring releasable base
Prostate resectoscope having ultrasonic scanning
Device for and method of providing marks on an object by means of electromagnetic radiation