Assessing Benefits of a Buried Interconnect Layer in Digital Designs

In sub-15 nm technology nodes, local metal layers have witnessed extremely high congestion leading to pin-access-limited designs, and hence affecting the chip area and related performance. In this paper, we assess the benefits of adding a buried interconnect layer below the device layers for the purpose of reducing cell area, improving pin access, and reducing chip area. After adding the buried layer to a projected 7 nm standard cell library, results show ~9%-13% chip area reduction and 126% pin access improvement. This shows that buried interconnect, as an integration primitive, is very promising as an alternative method to density scaling.