bevel edge

The bevel edge is the **rounded or chamfered perimeter** of a silicon wafer, typically extending **1-3mm** from the wafer edge. It prevents chipping during handling and processing but creates unique process challenges. **Edge Profile** **Crown (apex)**: Outermost point of the bevel curve. **Upper bevel**: Angled surface from the device side to the crown. **Lower bevel**: Angled surface from the backside to the crown. **Flat/Notch**: Orientation marker (200mm wafers use a flat, 300mm wafers use a notch). **Edge exclusion**: 1-3mm zone from the edge where no devices are printed (not part of the usable die area). **Process Challenges** **Film buildup**: Deposited films accumulate on the bevel edge with poor adhesion, creating flaking and peeling defect sources. **Resist edge bead**: Photoresist pools thicker at the wafer edge during spin coating. Edge bead removal (EBR) cleans this before exposure. **Etch non-uniformity**: Plasma etch rates vary at the extreme edge due to electric field and gas flow changes. **CMP edge effects**: Polishing pad interaction at the wafer edge causes different removal rates (edge roll-off). **Bevel Edge Cleaning** Bevel etch tools (e.g., **SEMES Aris**) selectively remove film buildup from the bevel edge without affecting the device area. This is performed after deposition steps where bevel contamination is problematic. It's critical for preventing particle defects that originate from flaking bevel films.