LVS fails when some cells are in the hcell list
IC Verification & Signoff
The article explains how to fix LVS fail with seed promotion issue due to some cells inclusion in the hcell list.
If the LVS fails when some cells are included in the hcell list and is clean when those cells are removed, it can be a seed promotion issue even though there is no indication of seed promotion in the transcript. In certain cases when there is interaction of device seed-forming layers at differing levels of hierarchy, device seed layers can be promoted during the construction of the Calibre hierarchical database. This is before device recognition occurs, so there is no indication of seed promotion in the transcript. Such seed shape promotion results in LVS discrepancies.
There are two ways to solve the issue:
This issue can be solved by removing the cell from the hcell list.
If there is no agreement on having the cell that causes the seed promotion as an hcell, the user can remove the cell from the hcell list
Also, this can be solved by using the LVS EXPAND SEED PROMOTION YES statement.
The statement controls whether to expand hcells that were subject to seed promotion during hierarchical device recognition. This will solve the seed promotion issue and will show a warning message about the device seed promotion caused expansion of a cell.