Prerequisites for Automatic Device Abutment in Layout XL

Abutment in Layout XL is triggered when two pins of different instances overlap or when named shapes within two Pcell instance submasters overlap. If they meet the following criteria, the abutment engine executes.

• The abutment engine is enabled.
• Both instances must be Pcells set up for abutment or cells with the appropriate abutment properties set.
• Both instances must share the same master or must have the abutClass property set.
  If two instances have the same master, then they can be abutted, even if the abutClass is set to different values on each instances.
  To abut two cells with different masters, you must add the abutClass property to the pin of each cell and enter the same abutment class name as the value for each property.
• The instances must overlap.
• Both instance pins must be connected to the same net.
  To abut overlapping instances with no nets, set the abutWithoutConnectivity environment variable.
• Both instance pins must be defined on shapes of the same layer or on layers that are defined as equivalent layers in the technology file.
• Both instance pins can have the same abutment direction if the rotation of one (but not both) of the pins is either R180 or MY, or any other rotation that transforms the left-hand side to the right-hand side.
• During placement, the Connectivity extractor and Abut transistors options in the Connectivity form must be turned on.
  When the Abut transistors option is turned on, devices that have not been abutted but are overlapping are abutted. If the devices are already abutted, autoAbutment does not re-abut the devices.
• If one of the instances is in any type of group (including a synchronous clone), the other instance must be in the same group.

Abutted devices can share diffusion, contacts, metal tabs, or any shape combined in an instance pin.

While creating specific parameters in Pcells and named diffusion shape pins, you also have to add the following properties on the shapes the pins are created on. The auto-abutment properties specify whether or not the Pcells can abut.

• abutClass Property – Pins with the same abutClass are able to abut.
• abutAccessDir Property – Defines the directions in which the pins are able to abut.
• abutGateNet Property – Defines the name of the net the gate shapes are on.
• abutCondInclusion Property – Defines the name of the boolean property that adds or removes contact shapes over the diffusion pin.

Related Topics

Pcell Set Up for Abutment

About Pcell Super and Submaster Cells

abutWithoutConnectivity

autoAbutment

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