Dracula LVS

[Su]

I have a question about DRACULA LVS.

After finishing LVS, the lvserr.lvs shows that the schematic and layout
are matched. But there are warnings which are listed in lvserr.erc. It
says "stamping multiple-nodes for PSUB".

Is this a problem?

thanks,

suyu

 

Su wrote:

After finishing LVS, the lvserr.lvs shows that the schematic and layout
are matched. But there are warnings which are listed in lvserr.erc. It
says "stamping multiple-nodes for PSUB".

Is this a problem?

Yes. It means that one or more of your substrate taps
is NOT connected in metal to all the rest of your substrate
taps.

It could just be a floating tap.

It could be a floating guard ring.

It could be a tap connected in metal to another net.

Some of those are fatal, some are not. The Dracula
output should give you an XY location for the "minority"
tap(s), it's been some time since I ran Dracula, so I can't
tell you exactly what that output would look like.

-Jay-

 

[Su]

HI, Jay:

Thanks a lot for your reply.

I think I've found out the reason.

suyu
jayl-news@accelerant.net wrote:

Yes. It means that one or more of your substrate taps
is NOT connected in metal to all the rest of your substrate
taps.

It could just be a floating tap.

It could be a floating guard ring.

It could be a tap connected in metal to another net.

Some of those are fatal, some are not. The Dracula
output should give you an XY location for the "minority"
tap(s), it's been some time since I ran Dracula, so I can't
tell you exactly what that output would look like.

-Jay-