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
PCSK9 antagonists
Sampling switch circuit that uses correlated level shifting
Spray drying vancomycin
Clock generator circuit for a charge pump
Point-of-sale server and method
Method of allocating IP address of image forming apparatus using DHCP, image forming apparatus and system of allocating IP address using DHCP
  Randomly Featured Patents
Extending access to a device in a limited connectivity network to devices residing outside the limited connectivity network
Method of cleaning an inner wall of a mold by means of dry ice
In vitro cell culture system
Content addressable memory (CAM) devices that utilize dual-capture match line signal repeaters to achieve desired speed/power tradeoff and methods of operating same
Thin film transistor array
Wheel end play setting device
Apparatus for producing cartons
Seat recliner
Multi-way electric switch having operator control supported by two orthogonal parallel linkages coupled via intermediate part
Substituted isoxazolo compounds