notch and flat

**Notch and flat** is the **physical wafer orientation features used to indicate crystal direction and support correct tool loading and process alignment** - they are foundational references in wafer handling and alignment systems. **What Is Notch and flat?** - **Definition**: A notch is a small edge cut, while a flat is a larger straight edge segment on legacy wafers. - **Orientation Function**: Both indicate crystallographic orientation and wafer type metadata. - **Manufacturing Role**: Used by robots, aligners, and metrology tools for rotational reference. - **Format Evolution**: Modern larger wafers commonly use notches; older formats often used flats. **Why Notch and flat Matters** - **Process Registration**: Incorrect orientation can misalign masks and process steps. - **Automation Reliability**: Machine vision and handlers depend on clear orientation landmarks. - **Quality Assurance**: Orientation errors can invalidate lot processing and data traceability. - **Device Performance**: Some anisotropic processes rely on correct crystal-direction alignment. - **Operational Efficiency**: Accurate orientation reduces setup time and run interruptions. **How It Is Used in Practice** - **Vision Calibration**: Maintain notch and flat detection algorithms for robust orientation pickup. - **Incoming Verification**: Check orientation feature integrity during wafer receiving and staging. - **Tool Interlocks**: Block processing when orientation mismatch is detected. Notch and flat is **a basic but essential reference system in wafer operations** - consistent notch and flat handling prevents alignment-driven process failures.