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BUG: Drawing path in Virtuoso 6.1.6 only possible in routing layers

Sheppy

Hello,

Today, a colleague noticed a change between Virtuoso 6.1.5 and 6.1.6:

In the former it was possible to draw a path in any layer available in the LSW, in the latter it is only possible to draw in routing layers.

In our process we have a layer that defines the lateral isolation (LATISO), which we have to draw as a path around (a group of) active components. With the new version (6.1.6) we are unable to do that, it (the path procedure) simply selects the first routing layer (in our case METAL1).

This is a big inconvenience and the default setting of Virtuoso is obviously wrong. The only change we made is the version of Virtuoso, the PDK is still the same version, even using the same layout-cell-view to test this.

One method of "fixing" this is to specify LATISO as one of the routing layers. This will then also allow automatic routers to use LATISO, which is somehting we don't want, so we're not going to do that.

My question:

Is there a setting available to turn-off this behavior?

By the way: we are developing the PDK ourselves, so if something has to be done in the technology file, that is possible as well. Although this is not the preferred solution since it is a change in Virtuoso behavior that is the issue.

With kind regards,

Sjoerd

edit: added the part about PDK

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  • ColinSutlieff

    Hi Sjoerd,

    I just want to correct part of your text.

    Wires do not contain paths anymore. Wires contain pathSegs and vias

    In earlier versions (IC615) Wires contained either paths or pathsegs. Wires containing paths were called (geometric wires).

    In any case, wires are not subsets of paths or pathsegs.

    FYI, using wires  will guarantee that any 45 geometries will create on-grid coordinates. That is not the case with paths.

    Also, wires are compatible with the auto routing tools, paths aren't.

    So my recommendation: use wires for interconnect.

    Colin

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  • ColinSutlieff

    Hi Sjoerd,

    I just want to correct part of your text.

    Wires do not contain paths anymore. Wires contain pathSegs and vias

    In earlier versions (IC615) Wires contained either paths or pathsegs. Wires containing paths were called (geometric wires).

    In any case, wires are not subsets of paths or pathsegs.

    FYI, using wires  will guarantee that any 45 geometries will create on-grid coordinates. That is not the case with paths.

    Also, wires are compatible with the auto routing tools, paths aren't.

    So my recommendation: use wires for interconnect.

    Colin

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