1. Purpose of the gate
Test chip tape-out is the first irreversible engineering commitment the company makes. Once the database is accepted and wafers start, the design is frozen: errors cannot be fixed until the next shuttle, and the cost of that delay is measured in runway as much as in money. The technical judgement on the database was made at Test chip sign-off. This review decides the release: that what goes to the provider is the signed-off database without change, that the provider has accepted it, and that everything needed to evaluate the silicon will be ready when it arrives.
The gate criteria are Test chip sign-off passed, with no change to the database since; the shuttle slot and die area confirmed with the foundry or shuttle provider; evaluation readiness, with the test board, package plan and evaluation plan ready; and a tape-out archive with the design data, tool versions and design kit version.
On a multi-project wafer shuttle the cut-off for database submission is set by the provider and does not move for one customer. The review is therefore held close to the cut-off, usually as a release review followed by an acceptance confirmation once the provider has run its own checks. If the provider asks for a change, the change goes back through the sign-off checks before resubmission. The decision can still be to hold for a later shuttle, and the review must be willing to take it.
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