yield ramp slope

**Yield Ramp Slope** is the **rate of yield improvement during the ramp-to-volume phase** — measured as the yield increase per unit time (e.g., % yield per month or per wafer start), the ramp slope determines how quickly a new process or product reaches its yield targets and becomes profitable. **Ramp Slope Factors** - **Defect Learning**: Speed of defect source identification and elimination — inline inspection, failure analysis, root cause analysis. - **Process Optimization**: Iterative recipe tuning, split lot experiments — narrowing process parameter distributions. - **Design Fixes**: Design rule violations, marginal patterns — ECN (Engineering Change Notice) iterations. - **Equipment Qualification**: Tool matching, preventive maintenance optimization — reducing equipment-related variability. **Why It Matters** - **Revenue**: Steeper ramp slope = earlier revenue and faster return on the $10-20B fab investment. - **Market Share**: Faster yield ramp captures early market demand — customers commit to proven processes. - **KPI**: Yield ramp slope is a key performance indicator (KPI) for fab manufacturing excellence. **Yield Ramp Slope** is **how fast yield climbs** — the rate of improvement that determines when a new technology node becomes economically viable.