laser repair

**Laser Repair** is a **mask repair technique that uses focused, pulsed laser beams to remove unwanted material from photomasks** — the laser ablates or photochemically removes opaque defects (excess chrome or contamination) from the mask surface. **Laser Repair Characteristics** - **Ablation**: Short-pulse (ns-fs) laser evaporates the defect material — fast, high-throughput repair. - **Wavelength**: UV lasers (248nm, 355nm) for better resolution and material selectivity. - **Clear Defects**: Limited capability for additive repair — laser repair is primarily subtractive (removing material). - **Speed**: Faster than FIB — suitable for large defects and high-volume mask repair. **Why It Matters** - **Speed**: Laser repair is significantly faster than FIB for large opaque defects — higher throughput. - **No Contamination**: No implantation (unlike FIB's gallium) — cleaner repair process. - **Resolution Limit**: Lower resolution than FIB or e-beam repair — not suitable for the finest features at advanced nodes. **Laser Repair** is **burning away mask defects** — fast, clean removal of unwanted material from photomasks using precisely focused laser pulses.