End Cap Cells and how to place end cap cells in the design

END CAP CELLS

• End cap cells are pre placed physical only cells it has only physical connectivity 
• End cap cells are placed at the end of each site row [left and right side of the row]
• These library cells don't have signal connectivity
• They connect only to the power and ground rails once power rails are created in the design
• Each end of the core row, left and right, can have only one end cap cell specified
• However, you can specify a list of different end caps for inserting horizontal end cap lines, which terminate the top and bottom boundaries of objects such as macros
• End caps have a fixed attribute and cannot be moved by optimization steps
• A core row can be fragmented (contains gaps), since rows do not intersect objects such as power domains. For this, the tool places end cap cells on both ends of the un-fragmented segment
• while doing the fabrication of the chip the corner cells may get damage it leads to functional failure to resolve this issue will place the end cap cells at the end of the site rows, in this case end cap cells are protecting to the logical cells (Std cells). 

Command:

setEndcapMode -rightEdge FILL1 -leftEdge FILL1

addEndCap -prefix endcap -preCap FILL1 -postCap FILL1 

example: If your design is multi voltage we use the following command to place the end cap cells

• addEndCap -prefix endcap -preCap FILL1 -postCap FILL1 -powerDomain PD1
• addEndCap -prefix endcap -preCap FILL1 -postCap FILL1 -powerDomain PD2

Note: FILL1 cell i consider as a EndCap cell and PD1, PD2 are power domains