Electrostatic discharge (ESD) checks are an important part of reliability verification because of the challenges posed by advanced process nodes as well as increasing design complexity. However, the work can be both time-consuming and prone to error.
Within ESD verification, checks for point-to-point (P2P) and current density (CD) are key. These are issues that must be addressed both at the cell level and also along paths where clamps are applied to provide ESD protection.
Foundries provide a wide range of process checks but a design will typically require some custom ones too. Creating these can be difficult if the verification engineer does not have a deep existing knowledge of ESD issues.
A recently published technical paper from Siemens EDA discusses how this process can be simplified by using configurable checks within the Calibre PERC reliability platform. This opens up a cell-based ESD reliability verification process to all members of a team in a way that, author Abdellah Bakhali says, is easy to use and minimizes runtime set up.
The PERC approach is based on logic-driven layout (LDL) technology where the pre-coded checks combine necessary geometric and topological information within each one.
“The Calibre PERC cell-based verification flow supports the Calibre PERC packaged checks for P2P/CD checking. When LDL cell-based checks are executed, device extraction is disabled, and all trivial pins… and empty sub-circuits are preserved in the extracted layout netlist for topological analysis,” Bakhali explains.
“These conditions facilitate checking of connectivity to any desired cell port (where the cell acts as a hierarchical cell). Because device extraction is not required when running LDL cell-based, a [layout vs. schematic]-clean layout with devices present is not a prerequisite for running LDL checks on cell placements.
“Also, because the device modules are skipped during circuit extraction, cell-based checks generally run very quickly.”
The paper describes further the nature of the pre-coded checks, their use and the path to debug. ‘Evaluate Electrostatic Discharge robustness with cell-based P2P/CD verification’ is available here.