validLayers – Enclosed Stop Layers Specification

You can also use the validLayers constraint to specify that the areas defined by a NOT operation should be enclosed by a third layer. To do this, you must add a constraint to the stop layer using the INSIDE operation.

Consider the following example:

(Stopped 10001 (substrate 'not Nwell))

(StoppedWithInsideConstraint 10002 (Stopped 'inside Nburied))

(validLayers (StoppedWithInsideConstraint))

The constraint definition indicates that the:

Substrate, Nwell, and Nburied are extractable layers
Substrate is being stopped by the Nwell layer
Stopped regions of the substrate must be enclosed within the specified Nburied layer to be electrically insulated from the rest of the substrate

There can be several INSIDE layers for a specified pair of stop layer and stopped layer. For example:

(Stopped 10001 (substrate 'not Nwell))

(StoppedWithInsideConstraint1 10002 (Stopped 'inside Nburied1))

(StoppedWithInsideConstraint2 10002 (Stopped 'inside Nburied2))

(validLayers (StoppedWithInsideConstraint1 StoppedWithInsideConstraint2))

This indicates that the stopped regions of the substrate must be enclosed within one of the specified Nburied layers to be electrically insulated from the rest of the substrate.

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