Useful defect contrast
Define the wafer stack, defect class and reference response.
Inspect, measure and process · Industry, inspection & flow
Semiconductor wafer inspection
Connect defect contrast to the source, detector and scan recipe.
Application focusUseful defect contrast
Signal over background
Choose geometry, polarization, filters and detector together.
Stable scan acquisition
Control illumination, focus, position and exposure timing.
Why the source matters
Useful defect contrast depends on the wafer stack, illumination geometry, collection optics and detector as well as the laser wavelength.
The correct source is defined at the sample or process—not at the laser aperture. Wavelength and operating mode set the interaction; stability, delivery, timing, and control determine whether it stays useful in the complete system.
Light inUV and visible surface excitation; SWIR for suitable transmitting silicon stacks
InteractionProbe the wafer
ResultUseful defect contrast
Application workflow
Design from the result backward.
Three decisions turn the application into a practical source specification.
Define the inspection target
Record material, films, pattern, process stage and defect classes. Distinguish surface scatter, reflected pattern contrast, luminescence and a transmitting infrared path.
Prove the optical response
Compare candidate wavelengths and geometries on representative samples. Measure background, delivered power and dose, then qualify the collection optics and detector band.
Validate at the intended scan speed
Match motion, focus control, exposure and data capture. Establish repeatability, missed-defect and nuisance-call criteria before defining throughput and supply scope.
Selection guide
Match the architecture to the experiment.
These are starting architectures. Precisometer qualifies the final wavelength, output, delivery, control, and integration package against your setup.
- Wavelength band
- UV and visible surface excitation; SWIR for suitable transmitting silicon stacks
- Operating mode
- CW scanning or pulsed excitation matched to the measurement
Surface and pattern inspection
Compare CW UV or visible excitation with dark-field or bright-field collection. Pattern references, alignment and stray-light control influence the result.
Material-specific luminescence
Match excitation and detection bands to the wafer material and defect response. Specify short-pulse excitation only when the measurement needs its timing.
Buried silicon structures
Evaluate SWIR transmission or reflection on the actual stack, with an infrared-sensitive detector. Substrate thickness, doping, films and metal coverage limit optical access.
Source architecture
Wafer inspection sources & integration.
Four measurement paths
Dark-field scatter
Particles, scratches and surface anomalies on bare wafers or films.
Compare UV and visible excitation on the actual surface. Collection angle, polarization and film background matter alongside wavelength.
Bright-field reflection
Pattern differences, missing material and visible process anomalies.
Choose illumination angle, spectrum, coherence and polarization for pattern contrast. Laser illumination is one option; broadband illumination can also be appropriate.
Photoluminescence
Material and epitaxial nonuniformity, including suitable SiC and other compound-semiconductor defects.
Match excitation to the material, polytype and defect response. Specify emission filters and detector sensitivity separately from laser wavelength.
Through-silicon SWIR
Accessible buried structures, cracks or bonded-interface features in a transmitting silicon stack.
Evaluate a wavelength such as 1550 nm against the actual wafer transmission and camera response. Thickness, doping, coatings and metal layers can restrict the path.
Laser sources to evaluate
These existing catalogue examples illustrate different excitation architectures. Their model sheets govern power, stability, pulse duration and repetition rate. Match delivered power and dose to the sample; the highest catalogue power is not an inspection requirement.
CW UV · 266 nm
UV-DP-266-B
Evaluate UV surface contrast or material-specific excitation; confirm UV optics and delivered dose.
CW UV · 320 nm
UV-FN-320
An excitation option when the sample response and collection filters favor this UV line.
CW UV · 355 nm
UV-FN-355
Compare continuous UV excitation for scanning or luminescence measurements on the actual material.
Picosecond UV · 266 nm
FL-266-PS
Consider when the measurement requires short-pulse excitation. Specify pulse energy, timing and sample dose together.
Picosecond UV · 355 nm
EO-355-PS
A pulsed UV alternative for a timing-dependent experiment; verify its operating point against the model sheet.
Visible / violet CW · 405 nm
MDL-III-405
Evaluate reflected or scattered-light contrast with a matching camera, illumination profile and power control.
Infrared CW · 1550 nm
MDL-III-1550
A candidate for a transmitting silicon path, with an infrared-sensitive detector and verified optical transmission.
Specify the measurement chain
Pair the source with the detection band, collection optics, focus control and scan synchronization. Define cleanliness, wafer handling, defect references and acceptance criteria before committing to a system architecture. A laser wavelength or semiconductor process-node name does not establish detection sensitivity.
Ready to specify
Bring us the application—not a guessed model number.
Specify wafer material and layer stack, defect classes and references, measurement method, excitation and detection bands, delivered dose, scan timing, repeatability and acceptance criteria.
