Checking and Error Disposition Strategy for GF Designs

GF states as follows:

"Test Site Multi Customer MPW runs have increased complexities and schedule constraints, and therefore require a streamlined Foundry verification and error disposition strategy. GF performs Basic checking on testsite MPWs to reduce complexity associated with handling multiple designs, and to minimize overall tapeout related churn (ie. data returns) and potential schedule impacts. This subset of Basic checks include DRC, Density, Line mode/ orthogonality, and XOR (if applicable) verification only. All other checking and analysis is the MPW Provider and Customer's responsibility.

"GF Error analysis and waiver requirements for test site multi Customer MPW runs are limited to issues which can have external impacts. External impacts errors are those violations which can potentially have impacts beyond that of a Customer's individual design, such as manufacturing tool or wafer contamination (ie. lifting photo resist) , impacts to adjacent riders, impacts to manufacturing kerf structures, and impacts to the mask house. Examples of external impact violations (but not limited to the following) include density, minimum space violations, off grid, and half line width errors. GF requires fixes or pre approved manufacturing waivers for violations of this nature. The Customer is fully responsible for all other violations that do not fall into the external impact bucket. Violations of this nature are characterized as internal impact errors, and examples include (but are not limited to the following) floating gate, ESD, latchup, modeling related errors, and packaging related rules. These issues do not require official waiver requests for MPW testsite runs. However, it is strongly recommended that these issues be fixed, as they can potentially impact yield, reliability, performance, packaging, and ultimately the transfer of the design into full production. Clean data is always the best strategy for all parties.

"GF MPW Provider Checking and Error Disposition is reserved for test site activity, and is not suitable for production level designs due to the reduced level of checking and error analysis. Full GF verification is recommended (and may be required), and full error analysis is required for any Production Ready design. Also, a test site design with existing violations may experience difficulties transferring into production phase on a stand alone maskset. GF analyzes production designs with a much higher level of detail and scrutiny, and may reject designs which may have previously passed based on MPW Provider checking rules. It is strongly recommended that all MPW designs tapeout as ground rule clean as possible (for all checks) to help minimize this risk.

"Key Points:

  1. Basic Checking is Performed on GF MPW Provider Test Site Runs: DRC, Density, Line Mode/ Orthoganility, and XOR (if applicable).
  2. GF Error Analysis and Waiver Requirements are Limited to Issues which can have impacts external to a Customer's design
  3. Verification and Error Analysis not Covered by MPW Provider checking strategy is Customer's and MPW Provider's Responsibility
  4. Testsite MPW runs and MPW Provider Checking are not suitable for Production Ready Designs
  5. Testsite Designs with Errors require fixes (recommended) or pre-approved waivers (which may be rejected) prior to transferring to Production
  6. Clean Data is always the best strategy for all parties."

(MOSIS offers the following clarification of the policy statement above:

Layout submitted to MOSIS for fabrication in one of the GF processes is checked for conformity to design rules and guidelines. MOSIS assumes that the customer has performed all available checks and is aware of all flags at the time he submits the layout for fabrication.

Checks detecting a condition which can affect other designs on a shared reticle, or integrity of the fabrication process, will result in the design being rejected for inclusion on that shared run. Violations which affect only the project itself will generally be waived, and the design will be accepted for manufacture on a shared run.

These are usually "category a" flags and must be repaired. Assura users must run the Floating Gate checks (and not just "DRC"), because GR594 antenna flags (Nwell tiedowns to substrate) are now "category a" also.

However, for those remaining, waived violations flagged by the available suite of GF design checks, the customer grants an implicit waiver and accepts all associated risk. Such violations include, but are not restricted to, floating gate, antenna, ESD, latchup, modeling-related errors, and packaging-related rule violations. GF and MOSIS strongly encourage the correction of these errors. Neither GF nor MOSIS are responsible for the quality of the resulting fabricated circuit.

Acceptance of a design by MOSIS for manufacturing in one of the GF processes does not imply any guaranty of functionality of the fabricated design. The significance of errors reported during design checking must be evaluated by the designer. It is the customer's responsibility to pursue appropriate action in response to errors and warnings generated by the GF design checks.

Only totally clean designs or designs with pre-approved waivers will be accepted for production manufacturing by GF. Acceptance of a design for manufacturing on an GF multi-project wafer lot does not imply that the layout will be accepted for production manufacturing by GF. Designs destined for eventual production, should be production-clean even when first submitted to an MPW run for prototyping. If this is not done, the layout will have to be modified to correct the flags and this will jeopardize the validity of evaluations based on the prototypes. Please make MOSIS aware if an MPW design should be considered an eventual production prototype, and we will cooperate to screen it according to production design guidelines.)