material review board

**Material Review Board (MRB)** is the **formal cross-functional governance body that convenes to evaluate and authorize disposition of significant non-conforming semiconductor material** — bringing together process engineering, device engineering, quality assurance, integration, and manufacturing operations to collectively assess technical risk, financial impact, and customer implications of major process excursions that exceed the authority of individual engineers to disposition independently. **Why MRB Exists** Individual engineers can make straightforward disposition decisions within defined authority limits. But major excursions create conflicts of interest and require balanced judgment that no single function can provide alone: **Production** wants to release held material quickly to recover schedule and revenue. **Quality** wants to scrap or extensively test before release to protect customer reputation. **Device Engineering** understands the margin but may be overconfident in simulation vs. real-world reliability. **Process Engineering** understands the root cause but has incentive to minimize perceived severity. The MRB structure forces these perspectives to debate openly and reach a documented consensus decision. **MRB Composition** Standard MRB composition includes: Process Engineering (owns the excursion technical facts), Device Engineering (models device impact), Quality Assurance (customer specification gatekeepers), Manufacturing Operations (understands schedule and financial impact), Product Engineering (customer liaison if applicable), and Reliability Engineering (for any disposition requiring reliability data collection). **MRB Process** **Presentation**: The process engineer presents a formal excursion report: what happened, when, how many wafers affected, what the deviation magnitude is, what the root cause is (or current hypothesis), and what corrective action is implemented or planned. **Technical Assessment**: Device engineering presents margin analysis — simulation or empirical data showing device performance at the deviant parameter. Reliability engineering presents any relevant life test data. **Risk Debate**: Quality and device engineering debate the residual risk. Key questions: Does the deviation fall within characterized design margin? What is the probability of infant mortality or wearout failures? What is the customer notification obligation? **Decision and Documentation**: MRB votes on disposition, with the decision recorded in a formal MRB record that includes: the excursion description, all technical data reviewed, the disposition decision, monitoring requirements (additional testing, lot-level controls), customer notification decision, and signatures of all approving members. **Post-MRB Obligations**: MRB dispositions often include conditions — the released material must pass 168-hour burn-in, or 5 units per lot must be subjected to accelerated life testing before the lot ships. These conditions are tracked in the MES with mandatory completion gates. **Material Review Board** is **the high court of yield governance** — the structured forum where competing stakeholder interests in the fate of non-conforming material are formally adjudicated, documented, and resolved through collective technical judgment rather than unilateral decisions.