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OverUnder on large polygons

lkphoto
Hi Andrew,

I have problems in performing the “OverUnder” operation (=first using dbLayerSize with a positive amount, then with a twice the same negative amount, then with the positive amount again) caused by the fact that polygons cannot have more than 4000 points in SKILL. The purpose of the OverUnder operation is to remove acute angles, too small minimum spacings, and too small features during data preparation. These would create DRC errors.

I am designing photonic components, therefore the typical size of my cells is 10um x 10um or larger, moreover I have to use orthogonal polygons, and the curves are snapped to a 1nm grid.

I have a routine that writes such large polygons as a sum of subpolygons, each having less than 4000 points.

When I apply the dbLayerSize function to all the subpolygons at the same time, Cadence crashes –I assume because all the subpolygons together have more than 4000 points.

I ended up therefore by applying the dbLayerSize operation to single pairs of neighboring subpolygon, one at the time. The problem is that the result of the OverUnder operation depends on the way the big original shape is split into subpolygons. This is clearly not a clean solution, and I discarded it. Also, it is quite slow (taking few minutes for a single layer).

As a second attempt, I tiled the big polygon (=union of the many subpolygons) using square tiles (I used to this end the dbLayerAndNot) and applied OverUnder to each of them separately. Once this was done, I repeated the operation with the dual square lattice obtained by translating the tiles by half the tile pitch in both x and y directions. The result is predictable (as far as the tile size is sufficient), but the algorithm is extremely slow because of the dbLayerAndNot operation.

I wonder if there is a known solution to this problem.

For example, is there a way to get rid of the 4000 vertices per polygon limitation?

It would be great if I handn’t to go outside the Skill environment (e.g. by using Calibre), since these pCells see a number of other post-processing steps in Skill.

Thanks a lot in advance,
Parents
  • tweeks

    lkphoto said:
    Hi Andrew,

    Gee, can I reply too? :P  Maybe we should rename this the "Ask Andrew Forum".

    I'm going to assume that, if your message was really intended only for Andrew, you would have contacted him by email or the Cadence community private message feature.

    lkphoto said:

    When I apply the dbLayerSize function to all the subpolygons at the same time, Cadence crashes –I assume because all the subpolygons together have more than 4000 points.

    Please report this to your AE so that the bug gets fixed.

    lkphoto said:

    For example, is there a way to get rid of the 4000 vertices per polygon limitation?

    Have you tried using point arrays?

    We have:

     

    dbCompressPointArray
dbPointArrayAnd 
dbPointArrayAndNot 
dbPointArrayOr 
dbPointArraySize
dbPointArrayXor
dbTransformPointArray 
geCompressPointArray

    lkphoto said:

    It would be great if I handn’t to go outside the Skill environment (e.g. by using Calibre), since these pCells see a number of other post-processing steps in Skill.

    Could you stream out, run Calibre, and stream back in to SKILL? Or run Calibre on the OA database directly using sh() or ipcBeginProcess()? And then there's Assura... :)

Reply
  • tweeks

    lkphoto said:
    Hi Andrew,

    Gee, can I reply too? :P  Maybe we should rename this the "Ask Andrew Forum".

    I'm going to assume that, if your message was really intended only for Andrew, you would have contacted him by email or the Cadence community private message feature.

    lkphoto said:

    When I apply the dbLayerSize function to all the subpolygons at the same time, Cadence crashes –I assume because all the subpolygons together have more than 4000 points.

    Please report this to your AE so that the bug gets fixed.

    lkphoto said:

    For example, is there a way to get rid of the 4000 vertices per polygon limitation?

    Have you tried using point arrays?

    We have:

     

    dbCompressPointArray
dbPointArrayAnd 
dbPointArrayAndNot 
dbPointArrayOr 
dbPointArraySize
dbPointArrayXor
dbTransformPointArray 
geCompressPointArray

    lkphoto said:

    It would be great if I handn’t to go outside the Skill environment (e.g. by using Calibre), since these pCells see a number of other post-processing steps in Skill.

    Could you stream out, run Calibre, and stream back in to SKILL? Or run Calibre on the OA database directly using sh() or ipcBeginProcess()? And then there's Assura... :)

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