design rule waiver management

Design rule waiver management is the controlled process for accepting a foundry rule violation that cannot reasonably be eliminated before tape-out. **A waiver is not permission to ignore manufacturing physics.** It is a documented exception with an owner, evidence, foundry context, risk assessment, and approval trail. The danger is that waivers can become invisible technical debt: a local exception today can become a yield, reliability, or sign-off failure after a later layout change. | Waiver field | What it captures | Why it matters | |---|---|---| | Rule and location | Exact DRC rule, cell, block, and coordinates | Makes the exception reproducible | | Justification | Why the violation remains | Separates necessity from convenience | | Evidence | Simulation, foundry guidance, silicon history, or review notes | Supports the accepted risk | | Owner and expiry | Responsible engineer and revision boundary | Prevents stale waivers from drifting into tape-out | **The best waiver system is conservative.** Keep the count small, review changes after every ECO, distinguish foundry-approved exceptions from internal risk decisions, and make waiver closure part of the tape-out checklist.