Types of Physical-Only Cells

• End-cap cells - terminate the N-well at row ends.
• Tap cells - provide the body-bias contact.
• De-cap cells - act as a local power source.
• Spare or programmable cells.
• Filler cells - maintain N-well continuity.
• ESD cells, used as macros in flip-chip designs.
• Navigation marker cells.
• Foundry cells used to test the metal and CMOS layers.

KEY Physical-only cells include end-caps, tap, de-cap, spare, filler, ESD, marker and foundry test cells.

SPEF Parasitic Extraction

Inputs: the SPEF, netlist (.v), SDC and the db files, plus the macro netlist if the macro must be flattened. Inputs needed to generate parasitics: NXTGRD, the mapping file, the Milkyway library or DEF, and the macro DEF if the macro is to be flat - this is also called flat extraction.

• Metal-layer and via information is required.
• Capacitance and resistance models are required.
• A mapping file is required.
• A LEF or FRAM view is required.

Output of StarRC: the SPEF file, together with open and short information. SPEF stitching:

• The macro SPEF supplies the internal RC values of the macro.
• Several SPEF files will exist for the design.
• Read every lower-level SPEF before reading the top-level SPEF.
• Stitching saves SPEF generation time and CPU usage.
• However it is less accurate than full flat extraction.

KEY StarRC extracts SPEF from tech/RC models; stitching macro SPEFs is faster but less accurate than flat extraction.