Filler cells placed outside EndCap

Hi Steve,

Nice to connect with you on the phone just now. For the benefit of others that might come across this issue, here's what we found:

First, the placement blockage in the image above (along with a routing blockage that's not visible) is modeling a cutout within a rectilinear block.  We discussed modeling the block as a true rectilinear instead of with a placement and routing obstruction (which the tool supports via the GUI and with the setObjFPlanBoxList command).

Second, we did some testing and noticed that addEndCap is placing the end cap instances a few microns away from the routing blockage to avoid a drc violation between the metal in the end cap cell and the routing blockage.  However, addFiller does *not* do this, even with "-doDRC true".  This was made particularly obvious because the large routing blockage triggered wider spacing due to width-dependant spacing rules in the tech lef.  This is why filler cells were able to sneak between the placement blockage and the end cap.  I'll look into the inconsistency and report back.

Further, we noticed a slight difference in terms of how far from the routing blockage addStripe stopped and where addEndCap placed the instance.  I'll also look into this and report back.

Issue related to wide swaths of routing obstructions are good examples why modeling a block as a true rectilnear.  Steve, if you could report back on how that works out for, that would be great.

Another approach might be to edit the LEF to remove the larger spacing requirements for wider wires, but it seemed preferrable (to me) to go the rectilinear route because that would enable the horizontal stripes and the end cap cells to be abutted with the rectilinear edge.

Thanks for raising this issue- it's a great example to learn from.  I'll be following up as I have more information on the points I mentioned.

Let me know if you have any more related questions, and thanks for using the forums. I appreciate it.

Hi Steve,

Nice to connect with you on the phone just now. For the benefit of others that might come across this issue, here's what we found:

First, the placement blockage in the image above (along with a routing blockage that's not visible) is modeling a cutout within a rectilinear block.  We discussed modeling the block as a true rectilinear instead of with a placement and routing obstruction (which the tool supports via the GUI and with the setObjFPlanBoxList command).

Second, we did some testing and noticed that addEndCap is placing the end cap instances a few microns away from the routing blockage to avoid a drc violation between the metal in the end cap cell and the routing blockage.  However, addFiller does *not* do this, even with "-doDRC true".  This was made particularly obvious because the large routing blockage triggered wider spacing due to width-dependant spacing rules in the tech lef.  This is why filler cells were able to sneak between the placement blockage and the end cap.  I'll look into the inconsistency and report back.

Further, we noticed a slight difference in terms of how far from the routing blockage addStripe stopped and where addEndCap placed the instance.  I'll also look into this and report back.

Issue related to wide swaths of routing obstructions are good examples why modeling a block as a true rectilnear.  Steve, if you could report back on how that works out for, that would be great.

Another approach might be to edit the LEF to remove the larger spacing requirements for wider wires, but it seemed preferrable (to me) to go the rectilinear route because that would enable the horizontal stripes and the end cap cells to be abutted with the rectilinear edge.

Thanks for raising this issue- it's a great example to learn from.  I'll be following up as I have more information on the points I mentioned.

Let me know if you have any more related questions, and thanks for using the forums. I appreciate it.