mature yield

**Mature Yield** is the **steady-state yield achieved after the learning phase is complete** — the maximum achievable yield for a given technology and product, limited by fundamental defect density, design marginality, and process capability, typically reached 12-24 months after production start. **Mature Yield Characteristics** - **Plateau**: Yield improvement slows and plateaus — the easy problems are solved, remaining issues are fundamental. - **Target**: Advanced logic: 80-95%; memory (DRAM/NAND): 90-98%; analog: 85-95% — varies by product complexity. - **Maintenance**: Maintaining mature yield requires ongoing defect monitoring, equipment maintenance, and process control. - **Excursions**: Even at mature yield, process excursions can cause temporary yield drops — rapid recovery is essential. **Why It Matters** - **Profitability**: Mature yield determines the long-term cost per die — the basis for product pricing and profitability. - **Design Impact**: Die size and design complexity determine the achievable mature yield — larger die have lower yield. - **Continuous Improvement**: Even at mature yield, incremental improvement (95% → 96%) has significant economic impact at high volume. **Mature Yield** is **the production steady state** — the maximum sustainable yield that represents the ultimate manufacturing capability for a given technology.