Blockages

A blockage object specifies an area in a design where certain objects cannot be placed or are to some degree restricted in their placement. The type of objects to exclude from the blockage area depends on the blockage type.

Blockages are defined by points. You can use the command to seed the Create Blockage form. The command captures the layer information of the blockage, if applicable. It also captures the blockage type and updates the environment variable blockageType. In addition, if the blockage is of type fill or screen, the command captures the value of maximum density per cent and updates the environment variable blockageMaxDensity.

The following are the different types of blockages:

• Placement blockage: Prohibits the placement instances in the blockage area.
• Routing blockage: Prohibits creating or placing interconnect shapes such as path segments, paths, multipart paths, single-level shapes such as rectangles and polygons, or vias in the blockage area on the defined layer.
• Pin blockage: Prohibits creating or placing shape, instance, or via pins in the blockage area on the defined material and layer.
• Feedthru blockage: Prohibits creating feedthrus, which is routing through multiple gates through the terminal on the same layer, in the blockage area.
• Screen blockage: Allows you to create routing in the blockage area until the maximum density specified for the blockage area is reached on the defined material and layer.

When Design Rule Driven Editing (DRD) is enabled, blockages participate in DRD rule checking so that error markers/messages are created when you violate certain design rules.

Effective Width for a Blockage

The effective width for a blockage is an attribute that you can assign to any blockage types defined by a layer or layers such as routing, pin, or feedthru. The following considerations apply when using effective width:

• The effective width if set, rather than the size of the block object, is used for the entire blockage when a minSpacing value in the table spacing rules is defined in the technology file. These values determine which spacing rules apply. DRD flags the error in Notify mode or prevents placement in Enforce mode if the object is closer than the defined width for the layer.
• If a single minSpacing value is defined in the technology file, it is applied and the effective width is not used.
• It is not necessary to have the effective width defined for all layer blockages.
• When the blockage type is placement, the Effective Width field is grayed out, since it applies to instances and not layers.

Blockage Owner

You can optionally use the Attach to Owner option to assign an object as the blockage owner, depending upon the type of blockage. In the case of a placement halo blockage, the owner should be an instance or PR boundary. An owner can have any number of blockages. Cyclical relationships are not allowed. For example, if object A is a parent to object B, then object B cannot be a parent for object A.

Blockage Summary

You can use the File - Summary command to view information about blockage objects. The summary contains the total number of blockage objects and the blockage count of each type of blockage in the cellview. The information is sorted by layer.

Related Topics

Creating a Blockage

Placement and Routing Objects

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