Problem asml SNF 2011-03-06 11:18:31: wafer moving during exposure?

jcdoll at jcdoll at
Sun Mar 6 11:18:31 PST 2011

images in the top and bottom left corners of my wafers have multiple 'ghost' exposures. it's like the wafer shifted while the lamp was on, because there are partially exposed image copies (e.g. text labels show up in multiple places although only one appears to have completely exposed the resist).
this has been happening on 1-2 images per wafer, and most of the images look fine. for the exact same image, it might happen in the bottom left but not the top right of the wafer (or vice versa), and the severity of the problem varies between wafers.

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