[SOLVED] How to prevent manually placed vias from being removed during routing in ICC?

[zswong]

Hello EDA users,

I am using IC Compiler for layoutting and manually placed stack vias to connect from power rails (Metal1) of standard cells rows to the top-layer power straps (Metal 6). But during routing (route_opt), these manually placed stack-vias are "removed" and the power rails are "floating". The log does not specify any "removal". However,the stack-vias automatically placed by the tool during power-network synthesis remains after routing.

I split the routing procedure into "route_zrt_global" "route_zrt_track" "route_zrt_detail" stage and check for power-ground connection using "verify_pg_net" after each stage and found that after "route_zrt_track", the power-ground connection "floated" because the stack-vias are "removed".

Is there a way to prevent the "removal" of these manually stack-vias during routing?
Any suggestions, comments are welcomed and appreciated.

 

[matter]

I think that your manually placed vias/routes are not being treated as power nets. The router is thinking that these are regular routes and trying to auto route them. If you used the regular power strap creation commands, then the tool would have automatically set the correct power attributes on these nets/vias. I don't know why you had to manually place via stacks instead of going through the normal pg creation flow.
Anyways check if the "route_type" attribute on these vias is "P/G strap". My suspicion is that you won't see the P/G strap attribute, which might the reason for the regular zroute to modify these.

 

[zswong]

I think that your manually placed vias/routes are not being treated as power nets. The router is thinking that these are regular routes and trying to auto route them. If you used the regular power strap creation commands, then the tool would have automatically set the correct power attributes on these nets/vias. I don't know why you had to manually place via stacks instead of going through the normal pg creation flow.
Anyways check if the "route_type" attribute on these vias is "P/G strap". My suspicion is that you won't see the P/G strap attribute, which might the reason for the regular zroute to modify these.

Thank you for the suggestion...after changing the attribute, it remains after routing....many thanks