Frequently Asked Questions

• What is an optical profiler?

  An optical profiler is a non-contact surface metrology instrument that uses light-based measurement techniques to create a 3D map of a surface. Optical profilers are commonly used to measure surface topography, step height, roughness, film thickness, and surface defects.

• How does an optical profiler work?

  An optical profiler directs light onto a sample and analyzes the reflected light to determine surface height and reconstruct a 3D map of the surface. Most optical profilers use techniques such as white light interferometry (WLI), vertical scanning interferometry (VSI), structured illumination, phase shifting interferometry (PSI), confocal microscopy, or focus variation.

• What is the difference between PSI and VSI?

  Phase Shifting Interferometry (PSI) and Vertical Scanning Interferometry (VSI) are optical profiling techniques suited to different surface characteristics and measurement requirements.

  PSI (Phase Shifting Interferometry)

  • Best for smooth surfaces
  • Extremely high vertical resolution
  • Fast measurements
  • Limited vertical range

  VSI (Vertical Scanning Interferometry)

  • Better for rougher surfaces
  • Larger measurement range
  • Suitable for step heights and surface texture characterization

• What is the difference between a white light interferometer and a confocal profiler?

  White light interferometry uses interference patterns from reflected light to determine surface height and can provide exceptional vertical resolution for a wide range of surface topography measurements. Confocal optical profiling uses focus-based optical sectioning to determine surface height and can be well suited to surfaces and structures that are challenging for interferometry. The best technique depends on factors such as surface roughness, slope, reflectivity, and feature geometry.

• What can an optical profiler measure?

  Optical profilers can measure and characterize a wide range of surface features and properties, including:

  • Step height
  • Surface roughness
  • Etch depth
  • Film thickness
  • Flatness
  • Bow and warp
  • Particle dimensions
  • Volume measurements
  • Surface defects
  • 3D topography

• Can optical profilers measure rough surfaces?

  Yes. Optical profilers can measure a wide range of rough and textured surfaces. Techniques such as VSI and Enhanced Roughness Mode are specifically designed to measure rough and highly textured surfaces. The appropriate measurement mode depends on factors such as surface roughness, reflectivity, slope, and the profiler being used.

• Can optical profilers measure transparent films?

  Yes. Many optical profilers can measure transparent films using specialized algorithms and optical models. Film thickness measurements are a common application.

• What is the minimum step height an optical profiler can measure?

  Modern interferometric optical profilers can measure nanometer-scale and even sub-nanometer surface features depending on the measurement mode and sample characteristics.

• What is the maximum measurable step height an optical profiler can measure?

  Maximum measurable step height depends on the system design, objective lens, and stage travel. Many modern optical profilers can measure structures ranging from nanometers to millimeters in height.

• What are the advantages of optical profilometry compared to stylus profilometry?

  Compared with contact-based stylus profilometry, optical profilometry can offer several advantages, including:

  • Non-contact measurement
  • Faster area measurements
  • True 3D surface mapping
  • No risk of scratching delicate samples
  • High throughput for research and production environments

  Stylus profilers are recommended for thin transparent films, adjacent dissimilar materials, very steep structures, or applications requiring direct physical tracing.

• How do I choose the right optical profiler?

  Choosing the right optical profiler depends on your measurement requirements, sample characteristics, and throughput needs. Key considerations include:

  • Surface roughness scale/size
  • Step height range
  • Sample size
  • Required throughput
  • Vertical resolution requirements
  • Material type
  • Whether the sample is reflective, transparent, rough, smooth, or highly sloped

• Which industries and applications use optical profilometry?

  Optical profilers are widely used for surface metrology, process development, and quality control in:

  • Semiconductor manufacturing
  • MEMS
  • Photonics and optics
  • Advanced packaging
  • Solar cells
  • Medical devices
  • Microfluidics
  • Precision machining
  • Additive manufacturing
  • Academic research

• Can optical profilers be used in production?

  Yes. Optical profilers can be used in both R&D and production environments. Many systems support automated measurement routines, pass/fail analysis, defect inspection, wafer handling, and statistical process control for manufacturing environments.

• How do I get started with KLA optical profilometry?

  Fill out this inquiry form to get the process started, and one of our applications or sales representatives will contact you to discuss your applications requirements and answer any initial questions on pricing and lead times. A quote can be sent to you at this time, or you may wish to schedule a demo, either in-person or by sending samples for measurement. If a demo is completed, the report will be generated for you, after which you can decide how you would like to move forward.

• What happens once I place an order?

  Once an order is placed, your salesperson will keep you apprised of delivery schedule. Install and training is 1 day or less for the benchtop profilers, or longer for the automated systems. Some maintenance (such as calibration) can be performed by you. To order new or replacement step height standards, contact your sales representative. For questions that may arise as you are using the tool, our global Applications Team can provide assistance.