Auto Mode Via Creation on Intersecting Shapes

You can automatically place a single via or a stacked via in the overlap area of intersecting polygons, rectangles, paths or path segments. The via is created if there are available valid vias in the current constraint group in the technology database that connect the two layers on which the shapes exist. If there is a taper type constraint in the constraint group in the technology database, the vias are added to the valid vias list. When you place vias with Auto option selected in the Create Via form, the via origin snaps to the center of the overlap, irrespective of the Snap Spacing settings in the Display Options form.

When a via is created in Auto mode or when the Compute – From Shape(s) check box is selected in the Create Via form, by default the Minimum Rules calculation mode is applied. However, you can change the calculation mode by enabling the createViaAlwaysUsesDefinedCalcMode environment variable.
Auto via mode supports polygonal overlaps. If a non-metal via is created in a polygonal overlap, such a via is non-editable. In case the overlap area is a path or path segment, the via is created in every path or path segment subpart.
When shapes abut, auto via mode creates a via only when the shapes are path or path segment and when they are connected by their begin or end center line point.

In case there are multiple shapes on different layers overlapping at the same place, the auto via mode considers the adjacent metals. For example, if there is an M1, M2, and M4 shape at the same location, auto via mode considers two different overlaps, M1-M2 and M2-M4. It does not consider M1-M4 as an overlap, unless M2 is not visible in the Palette assistant.

By default, in auto via mode, the via width, length, row and column spacing, and the enclosure values are derived based on the calculation mode set in the Via Parameters Calculation Mode list in Layout Editor Options form.

By using Auto mode in the Create Via form, you can do the following:

Automatically place a via with a single click
Automatically place a via based on the connectivity information of the intersecting shapes

Auto vias cannot be created at the click point within an intersection area if no valid via or constraint group is defined in the technology file for connecting the intersecting layers. You can either edit the technology file to include the definition for vias connecting the intersecting layers or change the layers of the intersection objects to match a via defined in your technology file. An appropriate warning message is issued in the CIW for each case.

Virtuoso Layout Suite XL: Basic Editing User Guide
Product Version IC23.1, November 2023