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
Hepatitis B virus-binding polypeptides and methods of use thereof
Screen printing machine and method for controlling inside temperature of screen printing machine
Storage device carriers for adapting a storage device of a first size to a slot for a storage device of a second size
Compression limiting nut
Dust protection of sound transducer
Vehicle wheel rim
Wire rack shelf
  Randomly Featured Patents
Air cushion with independently adjustable resilient zones
Semiconductor device and method for fabricating the same
Diagonal bracing for lead post of folding partition
Heme concentrate and method for the preparation thereof
Apparatus for making a multi-layer plastic bottle with a handle
Impact reducing prosthetic pylon
Multilayer LC filter with improved magnetic coupling characteristics
Low noise cooling device
PSA process using an adsorbent with heterogeneous properties of capacity and/or selectivity
Cross-domain data transfer using deferred page remapping