Standard Cell Components Generated During Placement

Placement of standard cells has a unique set of requirements when compared to the placement of devices. In addition to standard cells, you require:

• Boundary Cells: At advanced nodes, adjacent cells (core cells) are placed in close proximity, which can lead to undesirable electrical effects. Adding boundary cells around core cells isolates the core cells from each other, and therefore prevents undesired effects.
  Boundary cells are represented by cells that have their component class set to BOUNDARYCELL. Component types are defined in the Cells table of the Configure Physical Hierarchy window—Component Types mode. After ensuring that the boundary cell definitions are in place, you can insert them between the core cells in your design.
• Tap Cells: In addition to boundary cells, you can insert either single-height or multi-height tap cells in the empty spaces between the standard cells. Tap cells are a set of contacts that are used to reduce latch-up effects between power and ground connections and the connections with wells or substrate contacts.
  Tap cells are represented by cells that have their component class set to STDSUBCONT. Component types are defined in the Cells table of the Configure Physical Hierarchy window—Component Types mode.
• Filler Cells: After standard cell placement, there might be some gaps or unfilled areas in layout designs. Unfilled areas might also result if the Utilization setting was selected on the Initialize tab when generating the design. Running a DRC check on such designs at this point could report several spacing violations. To avoid these violations, you must generate filler cells in the unfilled area between standard cells.
  Filler cells are assigned to a component type with their component class set to FILLER.
  Before inserting new filler cells, delete any existing filler cells. Otherwise, the placement of cells is prevented because of over congestion.

Related Topics

Auto P&R Assistant User Interface for Standard Cell

Placing Standard Cells Automatically

Adding Boundary Cells During Automated Standard Cell Placement

Adding Tap Cells During Automated Standard Cell Placement

Adding Filler Cells During Automated Standard Cell Placement