Specific Process Knowledge/Lithography/Aligners/Aligner: Maskless 01 processing: Difference between revisions
| Line 131: | Line 131: | ||
==Important note about correction options== | ==Important note about correction options== | ||
You must use all available alignment corrections! | <span style="color:red">You must use all available alignment corrections!</span> | ||
* 2 point alignment can only correct for rotation | * 2 point alignment can only correct for rotation | ||
* 3+ point alignment can correct for rotation, scaling and shearing - you must use all 3 alignment corrections! | * 3+ point alignment can correct for rotation, scaling and shearing - you must use all 3 alignment corrections! | ||
| Line 146: | Line 146: | ||
Using only two alignment marks is usually fine for smaller chips, but when exposing full wafers there may be misalignment, especially if previous prints are made on a different machine. With 4 alignment marks and all corrections applied, the best alignment accuracy is obtained for all substrates.<br/> | Using only two alignment marks is usually fine for smaller chips, but when exposing full wafers there may be misalignment, especially if previous prints are made on a different machine. With 4 alignment marks and all corrections applied, the best alignment accuracy is obtained for all substrates.<br/> | ||
If four marks are used, but scaling and shearing is not applied, significant misalignment will be observed, even on chips. On a 4" wafer | <span style="color:red">If four marks are used, but scaling and shearing is not applied, ''significant'' misalignment will be observed, even on chips. On a 4" wafer the shift in Y can be several hundred µm.</span> | ||
==Stitching== | ==Stitching== | ||