Problem with auto via using custom via variant

Hi Brian,

I'm not 100% clear what you are trying to do here. The auto via feature (of the "create via" command) will try to fill overlapping regions with as many cuts as possible. A via variant is a via with (non-default) parameters set. and is used when you know exactly what via values you want to use.

So using the auto via feature is not consistent with using via variants. (Or have I misunderstood something)

You may want to click the "options" button on the create via form. This provides a few more options about how the cut array is generated.

Also, remember that the vias will be DRC correct, so if it is not doing what you want, create the via with the values you want manually (turn off the  "compute" button and click "Reset Parameters to.." .Viadef defaults.

Then run the DRC checker manually; verify->design->process rules...OK

This will flag any DRC rules and may give you an idea why it's not generating the via you want.

BTW, the above refers to using Layout XL, not L

Regards

Colin

Colin

Colin,

Thanks,

What I’m looking to do is to via from metal 1-4, using a via with non-default spacing of 0.49um. I create the via variant with this spacing. I then set the auto via tool to use this via variant, however it then does not fill the entire metal polygon with via, only the amount set in the via variant, ie 2 vias. What I want is the auto tool to fill the full polygon with 0.49um spaced via. Hopefully this is more clear.

Regards,

Brian.

Brian,

O.K. I can see what you are trying to do.

The auto via will not change the parameters of your via variant. Once created, the variants are fixed.

In fact you will need 3 (M1-M2, M2-M3, M3-M4). But you will still only get the number of cuts defined in your via variant.

So what you need to do is not use any via variants at all.

In the options form you will see a list of all the layers and vias. Select the standard vias (if you haven't already done this) and set the cut spacings to the values you want. (don't forget to click the checkbox to force the override values.

The tool should then be able to change the number of cuts to fill the overlap area.

If you are trying to fill polygon areas you may get different results depending on the software version you are using. Earlier versions could only create a rectangular  via region. Later versions can generate diamond-shaped regions for 45 degree shapes

Regards

Colin

Hi Colin,

I don’t see the option in the options tab to edit the cut spacings. Please see SS attached. Maybe I am on an older version of the tool?

Regards,

Brian.

Hi Brian,

you didn't mention your software version.

But I have checked and can see that these features are new and not yet fully tested.

The feature has been disabled by default.

If you want to test it you can put the following in your .cdsenv file

layout lmpiModeOn boolean t

If you see any problems with the flag enabled you will need to contact customer support.

Regards

Colin