Limit multi-cut via array size

Tue Feb 02, 2010 9:26 pm   

Hi!

I'm using
setNanoRouteMode -droutePostRouteSwapVia multiCut
routeDesign -viaOpt
in Encounter (9.1) to automatically convert single vias to multi-cut vias
after the initial routing.
The result is that I end up with via arrays of 50x50 vias since in parts
of the design lots of space is available, especially on higher layers.

Is there a way to limit size of the generated arrays to - say - 3x3 vias?

My vias are generated from a GENERATE DEFAULT rule. I guess removing the
generate rule and only explicitely defining small arrays would work, but
I would like to avoid that work if possible.

Joerg

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Fri Feb 05, 2010 6:21 am   

On Feb 3, 3:26 am, Joerg <jo...@sofort-mail.de> wrote:

Hi,

I don't have a testcase but from the LEF 5.7 documentation, it looks
like you can create fixed 3x3 vias as DEFAULT and use GENERATE for a
range of metal widths so that anything outside these widths will take
the default (3x3).
I might be wrong here but I think it looks like this:

-------------------------------------------------------------------------
#lefdefref.pdf pg 220

VIA myDefaultVia
VIARULE DEFAULT ;

CUTSIZE 0.1 0.1 ;
LAYERS M2 VIA23 M3 ;
CUTSPACING 0.1 0.1 ;
ENCLOSURE 0.05 0.01 0.01 0.05 ;

ROWCOL 3 3 ; # 3x3 default
END myDefaultVia

#lefdefref.pdf pg 222 , pg224

VIARULE myVia23 GENERATE
LAYER M2 ;
ENCLOSURE 0.05 0.01 ;
WIDTH 0.1 to 2.0 ; # valid rule only for M2 width
between 0.1 - 2.0 um
LAYER M3 ;
ENCLOSURE 0.05 0.01 ;
WIDTH 0.1 to 2.0 ; # valid rule only for M3 width
between 0.1 - 2.0 um
LAYER VIA23
RECT 0.1 0.1 ;
SPACING 0.1 BY 0.1 ;
END myVia23
-------------------------------------------------------------------------

To be honest, I've never come upon anything like this since usually
wide metal layers (6um and above) I have are used for power/ground
rings/stripes and I usually use as much via as I can to switch between
the layers.

Best Regards,
I-FAB