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
Water slide
Cover panel for frame based door lock
Simultaneous wafer bonding and interconnect joining
Herbal composition for the treatment of wound healing, a regenerative medicine
Packet transmission system and fault recovery method
Method for detecting motion of an electrical device or apparatus
Method for operation of multi-layer-multi-turn high efficiency inductors
  Randomly Featured Patents
System and methods for linking compiled code with extended dictionary support
Brake control apparatus
Pizza container
Methods for dual drive operation of an auger in a development station
Method of setting up secure communications and associated encryption/decryption system
Serial data receiving device having a memory for storing a reception permit signal which enable or disable the device from hand-shaking with the transmitting device
Adaptive concentration communication network ISDN access
Shower head
Electrolytic capacitor
Twelve-pulse HVDC transmission