stiction

**Stiction** is the **adhesion-related sticking of released MEMS structures to nearby surfaces due to capillary, van der Waals, or electrostatic forces** - it is a major yield and reliability failure mode in MEMS. **What Is Stiction?** - **Definition**: Unintended contact and adhesion that prevents intended mechanical motion. - **Typical Triggers**: Capillary forces during drying, roughness interaction, and insufficient restoring force. - **Failure Timing**: Can occur during release drying, packaging, or field operation. - **Device Impact**: Leads to stuck beams, shifted resonance, or permanent performance loss. **Why Stiction Matters** - **Yield Loss**: Stiction can render otherwise correctly fabricated devices non-functional. - **Reliability Risk**: Intermittent sticking causes drift and unpredictable behavior in service. - **Process Sensitivity**: Minor changes in drying or surface chemistry can trigger failures. - **Design Constraint**: Mechanical geometry must provide sufficient restoring force margins. - **Packaging Coupling**: Humidity and contamination during assembly can worsen stiction effects. **How It Is Used in Practice** - **Surface Engineering**: Apply anti-stiction coatings and control roughness at contact interfaces. - **Drying Strategy**: Use critical-point or supercritical drying to avoid meniscus forces. - **Design Safeguards**: Increase gap, add dimples, and tune spring constants for release robustness. Stiction is **a primary mechanical-yield challenge in MEMS manufacturing** - stiction prevention requires coordinated process, design, and packaging controls.