Sub-minimum Features Not Allowed
MOSIS Technical Notes
MOSIS sometimes receives designs containing layout features that are
smaller than process specifications allow.
Mask-making tools cannot render (resolve) such images exactly, and therefore the mask inspection equipment flags a discrepancy between the written mask and the original data. Each discrepancy must be reviewed and waived by MOSIS staff. The entire run is delayed while this review takes place.
In order to avoid needless delays at the mask shop, MOSIS must insist that the following constructs not appear anywhere in a layout file, not even in a logo or other piece of non-circuitry.
Mask-making tools cannot render (resolve) such images exactly, and therefore the mask inspection equipment flags a discrepancy between the written mask and the original data. Each discrepancy must be reviewed and waived by MOSIS staff. The entire run is delayed while this review takes place.
In order to avoid needless delays at the mask shop, MOSIS must insist that the following constructs not appear anywhere in a layout file, not even in a logo or other piece of non-circuitry.
- Any layout feature smaller than the minimum feature size for that layer.
- Any spacing between features smaller than the minimum spacing for that layer.
- Any acute angles in polygons or wires (paths), because the acute tip itself is a sub-minimum feature.
- Digitized images (bit maps), even when the pixel size is above minimum width, because each point where two pixels meet diagonally creates an unresolveable sub-minimum region; for example,
XXX XXX XXX XXX XXX XXX XXXXXX XXXXXX XXXXXXIf you feel that your design requires one or more of these constructs, you must declare this at the time of project submission so that your case may be reviewed before it is committed to fabrication.