Instance Snapping in Abstract Mode Placement

The abstract mode placement allows fast placement of large layout blocks. The width spacing pattern (WSP) default abstract mode placement is performed in the following cases:

• • If the leSnapPatternSnappingVerticalGrid or leSnapPatternSnappingHorizontalGrid properties are not specified.
  • If the snapPatternSnappingMode environment variable is not set to abstract.
  • If the leSnapPatternSnapping property has not been specified.
  • If the instance master has a PR boundary or a snap boundary and a shape that can snap to the WSP grid.

In the above cases, the following tasks are performed to snap to the default WSP grid in either direction:

• • The largest period is identified.
  • For the matching period, the definition with the highest mask number snapping layer is identified.
  • In case there are multiple definitions on a snapping layer with the largest period, sorting is done based on the definition names.
  • If no WSP is found along a given direction, the snap pattern global grid is used for abstract mode placement.

The following is an example of an advanced scenario when abstract mode placement is performed for WSPs if you specify the leSnapPatternSnappingVerticalGrid or leSnapPatternSnappingHorizontalGrid property.

The offset overrides can be specified for WSP abstract mode snapping using the leSnapPatternSnapping property only if one of the properties, leSnapPatternSnappingVerticalGrid or leSnapPatternSnappingHorizontalGrid, has been set. If you do not specify either of these properties and only specify the offset overrides using the leSnapPatternSnapping property, the largest grid in the constraint in either direction is considered for snapping. It is assumed that you want to specify an offset override only when you override the grid.

In this case, the grid that you have specified is accepted without any further check. If the leSnapPatternSnapping property has an offset override, it is applied based on the existing rules that apply to this property. If only one direction grid has been specified, the other grid is determined based on the default algorithm.

When leSnapGridHorizontal and leSnapGridVertical abstract override properties have been specified, the object closest to pointer is used as the reference object for snapping. However, in case of modgens, the object that has the abstract override properties specified is used as the reference object for snapping.

Related Topics

Object Snapping Behavior in Width Spacing Patterns

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