Comment karlsuss2 SNF 2008-07-31 09:26:28: backside alignment sometimes poor

jwpchen at jwpchen at
Thu Jul 31 09:26:28 PDT 2008

SPR220 7um for backside through-wafer etch, aligning to frontside features. Verified alignment under contact, looked good, well within 5um. No jolt during exposure this time either.
However after backside etch, measured features to be off by about y=-30um consistent across wafer. Why?

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