laser scanning

**Laser Scanning** in semiconductor metrology refers to **surface inspection and measurement techniques using focused laser beams** — detecting defects, particles, and surface irregularities by analyzing scattered or reflected laser light across the wafer surface. **Key Laser Scanning Techniques** - **Dark-Field Inspection**: Detects particles and defects via light scattered from the surface (KLA Surfscan). - **Bright-Field Inspection**: Detects pattern defects via reflected light comparison (die-to-die, die-to-database). - **Confocal Laser Scanning**: Measures surface topography with sub-micron depth resolution. - **Laser Scatterometry**: Measures surface roughness and haze using angle-resolved scattering. **Why It Matters** - **Defect Detection**: Laser scanning inspects 100% of wafers for killer defects (particles, scratches, crystal defects). - **Process Monitoring**: Surface haze and particle density track process cleanliness. - **Production Essential**: Every wafer in production is laser-scanned multiple times through the process flow. **Laser Scanning** is **the wafer surface inspector** — using focused light to find every particle, scratch, and defect that could kill a chip.