Metrology
Measuring and inspecting every layer.
Learn → Understand → Explore → Calculate
At a glance
Inputs
- Wafers at various process stages
- Reference standards / recipes
Outputs
- Dimensional, film, and overlay data; defect maps
What is it?
Measuring dimensions, film properties, and overlay, and inspecting for defects — repeatedly, throughout the fab — to keep the process within specification.
Why is it needed?
With hundreds of steps and nanometre tolerances, a fab cannot rely on the final test alone. In-line metrology and inspection catch drift and defects early, protecting yield and enabling process control.
How does it work?
Metrology measures what is intended: film thickness, critical dimensions, overlay alignment, and doping/stress. Inspection hunts for what is not intended: particles, pattern defects, and scratches.
Techniques span optical scatterometry, electron microscopy (CD-SEM), ellipsometry, and automated optical/e-beam defect inspection. Data feeds statistical process control loops.
Critical parameters
- Measurement precision & repeatability
- Throughput
- Sensitivity to small defects
- Sampling strategy
Typical defects
- Escaped (undetected) defects
- False counts
- Measurement drift
Equipment involved
- CD-SEM
- Optical scatterometry / ellipsometry
- Defect-inspection scanners
- Overlay metrology
Materials involved
- Reference / calibration wafers
Keep going
Related concepts
Related tools
No calculator maps directly to this step yet. Browse all tools →