Repetitive failure in wafer handling is sometimes reported. Correlation with collision in handling transparent wafers has been clearly established. Although optical wafer edge detection has been succesfully tested with perfectly clean transparent wafers, problems still occur as any of the following conditions are encountered:
Glass wafers are defined as: transparent, clean or blank covered by semi-transparent material, or any structured layer on a transparent substrate. To avoid any inconvenience (extended period of equipment downtime, including booking cancellations), the procedure below must be followed:
In case of a wafer edge detection failure, the following dialog will appear:
DO NOT select the "Retry" option. A collision with the next wafer will happen!
Some dialog windows can be further seen in case a wafer is lost at a process station. In case the Retry button is pressed by accident at any time: hit the "panic button" (large red button at the right front side of the EVG) to stop the robot immediately. Contact CMI Staff as soon as possible. The machine cannot be turned on without staff help.
Next, change the cassette with an empty one after pressing abort. To proceed, press the "Cleanup" button on the left of the display and follow on-screen instructions. If cleared all stations successfully, the machine is ready to continue processing.