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
System and method for providing an extended platform for an operating system
Event handling in an integrated execution environment
Resist underlayer film forming composition for lithography, containing aromatic fused ring-containing resin
Real-time demand prediction in a fast service restaurant environment
Variable delay line for delay locked loop
Wireless communication system and wireless communication method
Cascode circuit device with improved reverse recovery characteristic
  Randomly Featured Patents
In-train information distribution and display system and in-train information distribution and display method
Presbyopia correction contact lens
Connector having metal shell shielding insulative housing
Suturing guide
China cabinet/buffet
Method of imbibing a component into a liquid crystal composite
Exhaust pipe and muffler for motorcycle that does not heat discolor
Contact lens package
Ejector mechanism in an injection molding machine