Problem asml SNF 2010-11-07 22:51:43: wafer missing

gsosa at gsosa at
Mon Nov 8 09:33:31 PST 2010

Found missing wafer intact on system baseplate. Based on the data from the batch report and the event log it is highly likely that there were 2 wafers in 1 slot. Suspect that the 2 wafers transfered to the pre-aligner. That is what caused the pre-alignment error(  The P/A system could not determine the wafer flat. The wafer was rejected and during the transfer to the E-chuck by the Dipod, the top wafer flew off. Luckily it did not land in a critical part of the tool, such as the wafer stage. This is a message for all users: IF you suspect that a wafer is lost in the tool, Shut the tool down and notify staff. Had the wafer landed on the granite it could have broken or been broken by the movement of the stage.Continued use under this condition could severley damage the stage. 

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