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DRC metal density issue. How to fix it?

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shanmei

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For layout, I have the drc error:

M1.R.1 { @ Min M1 area coverage < 30%
DENSITY M1xd < 0.3 PRINT M1_DENSITY.log
}


How can I auto fill metal? Thanks.

The environment is cadence6.16. Calibre 2013.
 

First, find out whether you have to. Some foundries want to
put down the fills themselves using in-house mask prep folks.

Then, if you are on the hook for it, look for cells in the layout
library like "DENSITY" or "FILL". They will probably be small,
maybe 2x2 contact, via1, ..., viaN with criss-crossed metal
strips and maybe some poly, N+, P+, active features for
those.

I like to make little multilayer poly/m1/m2/... capacitors and
use those to push up fill% while also getting some supply
decoupling inside the bondwires. Might as well make some
use of the "white space".
 
The fab should provide the dummy filling rule to do it automatically.
 
Is the DRC error at your top level cell?
 
CambridgeLv said:
The fab should provide the dummy filling rule to do it automatically.
Click to expand...

Depends on the foundry and on the complexity of the rules. Old technologies can be filled by the user without much hassle. Newer ones are too tough, external scripts are required.
 
I do not start the top level DRC, thanks.
 

Metal density errors can be ignored until you run your top level cell.
 
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