multi-cut definition in LEF

[Joerg]

Hi!

I'm trying to run encounter (8.1) for a technology that requires multi-cuts
between layers for wide tracks. I thus put in the technology LEF:
MINIMUMCUT 2 WIDTH 1.0 WITHIN 0.5 FROMABOVE ;
MINIMUMCUT 3 WIDTH 2.0 WITHIN 0.5 FROMABOVE ;

Encouter tries to respect the rule, but fails:
#WARNING (NRDB-778) No multicut vias are defined for LAYER ME2 in RULE
LEF_DEFAULT. When a LEF MINIMUMCUT rule is defined for a layer, you must
define multicut vias for the layer in the LEF file. Edit your LEF file and
read it in again.

I've search the LEF documentation, the Encounter documentation and the web
for information how to define a multi-cut via, but failed. I found that
maybe this is related to via-arrays or via-farms, but no info on this,
either...
I tried defining a VIA with ROWCOL 2 2, but this wasn't what encounter
wants to see...
So how do I define a rule that encounter likes?

On a similar note I have PREFERENCLOSURE in the TYPE CUT layer definitions
but I do not see an effect although there would plenty of room to extend the
wire. I would expect the wires to widen around the via. Is there anything
else besides having the PREFERENCLOSURE statement to make this work?

Joerg

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[Muzaffer Kal]

On Tue, 29 Dec 2009 14:54:38 +0000 (UTC), Joerg <joerg@sofort-mail.de>
wrote:

Hi!

I'm trying to run encounter (8.1) for a technology that requires multi-cuts
between layers for wide tracks. I thus put in the technology LEF:
MINIMUMCUT 2 WIDTH 1.0 WITHIN 0.5 FROMABOVE ;
MINIMUMCUT 3 WIDTH 2.0 WITHIN 0.5 FROMABOVE ;

Encouter tries to respect the rule, but fails:
#WARNING (NRDB-778) No multicut vias are defined for LAYER ME2 in RULE
LEF_DEFAULT. When a LEF MINIMUMCUT rule is defined for a layer, you must
define multicut vias for the layer in the LEF file. Edit your LEF file and
read it in again.

I've search the LEF documentation, the Encounter documentation and the web
for information how to define a multi-cut via, but failed. I found that
maybe this is related to via-arrays or via-farms, but no info on this,
either...
I tried defining a VIA with ROWCOL 2 2, but this wasn't what encounter
wants to see...
So how do I define a rule that encounter likes?

For multi-cut vias, you either need to define a via array (VIARULE
VIAx GENERATE) or you need to define the multicut vias directly ie add
multiple VIA layers in the VIA description ala:

VIA VIAxCUT2 DEFAULT
LAYER x ...;
RECT ...;
LAYER VIAx;
RECT rect1;
RECT rect2;
LAYER xp1
RECT ...;
END

to define a 2 cut via.

Hope this helps.
--
Muzaffer Kal

DSPIA INC.
ASIC/FPGA Design Services

http://www.dspia.com

 

[Joerg]

Muzaffer Kal wrote:

For multi-cut vias, you either need to define a via array (VIARULE
VIAx GENERATE) or you need to define the multicut vias directly ie add
multiple VIA layers in the VIA description ala:

VIA VIAxCUT2 DEFAULT
LAYER x ...;
RECT ...;
LAYER VIAx;
RECT rect1;
RECT rect2;
LAYER xp1
RECT ...;
END

to define a 2 cut via.

I already had the GENERATE rule, that one wasn't picked. Once I added
the via definition with the two RECTs, encounter was silenced. I have
yet to find a wire wide enough to require 3 vias to see if it also works
in that case.

Thanks,
Joerg

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