How do you choose a macro keepout type?

Short Answer

The keepout type you choose expresses which objects get excluded and at which stage — the numeric margin value (how far the exclusion extends) is a completely separate decision from the type. Use hard when you need broad placement exclusion around the macro for essentially everything — this is the strictest, most conservative choice.

Technical Explanation

• Use soft when you want to exclude cells during initial placement but explicitly allow later optimization steps to place something there if needed to fix a violation — softer, more flexible.
• , avoiding macro-to-macro abutment) while still allowing standard cells nearby.
• Use routing_blockage when the concern isn't cell placement at all but routing shapes — you want to keep metal/via geometry away from the macro boundary, which is a different physical concern than cell placement and needs its own keepout mechanism.
• Always confirm exact support and semantics in your installed tool release rather than assuming keyword behavior carries over version to version, and remember a keepout attached to a macro travels with that macro if it moves later in the floorplan — it's not a fixed floorplan-coordinate object.

Formula Or Decision Rule

Decision rule: use the least restrictive type that protects the demonstrated access or rule need.

What To Check

• Warning sign: A hard halo blocks useful optimisation space when only macro separation was required.
• Inspect: choose one affected region, macro, row, pin, path, or net and trace the physical cause.
• Correct: Replace it with the correctly scoped type and compare rows, pin access, and congestion.

Healthy, Suspicious & Hard-stop Results

• Healthy: Choose by which objects must be excluded and for which stage: hard for broad placement exclusion, soft when later optimisation cells may be allowed, hard_macro to exclude hard macros, and routing_blockage when routing shapes must be kept away.
• Hard stop: required legality or physical feasibility is missing or unexplained.

What The Interviewer Is Testing

” to measurable physical evidence and an owned correction.

Follow-up Question & Model Response

"* Candidate Model Response: Model response: “I would change it if the same controlled rerun shows that a hard halo blocks useful optimisation space when only macro separation was required. ”