Frequently Asked Questions

• What is a stylus profiler and how does it work?

  A stylus profiler (also called a stylus profilometer) uses a diamond-tipped stylus that physically traces the surface. Vertical movement of the stylus is recorded to generate a surface profile, allowing measurement of step height, roughness, waviness, film thickness, bow, and stress.

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• What can a stylus profiler measure?

  Common measurements include:

  • Step height
  • Film thickness
  • Surface roughness (Ra, Rq, Rz)
  • Waviness
  • Etch depth
  • Wafer bow
  • Radius of curvature
  • Thin film stress
  • 3D surface topography

• When should I use a stylus profiler instead of an optical profiler?

  Use a stylus profiler when:

  • Measuring transparent films
  • Measuring large step heights
  • Measuring deep trenches
  • A direct physical measurement is required
  • Surface reflectivity varies significantly

  Use an optical profiler when:

  • High throughput is needed
  • Large-area 3D mapping is required
  • The surface is too delicate to touch

• Can stylus profilers measure roughness?

  Yes. Roughness characterization is one of the most common uses of stylus profilers. Parameters such as Ra, Rq, Rz, waviness, and form can be calculated from scan data.

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• What factors affect stylus profiler accuracy?

  Stylus profilers are calibrated for measurement accuracy and repeatability using NIST-certified step height standards from VLSI Standards. Tip geometry relative to feature geometry can affect the results, so it is important to select the appropriate stylus tip. Performance can also be affected by environmental factors such as temperature, humidity, and mechanical and/or audio vibrations, so site specifications are very important.

• Can a stylus profiler measure transparent materials?

  Yes. One of the biggest advantages of stylus profilometry is that it is independent of material optical properties. Transparent, semi-transparent, and opaque materials can all be measured directly.

• Does contact measurement damage the sample?

  Stylus profilometry is generally minimally invasive when the appropriate stylus force and tip are used, and KLA stylus profilers operate with a constant applied force. Current systems can operate with forces as low as 0.03 mg, making them suitable for many soft materials. However, extremely delicate surfaces may be better suited for optical profilometry.

• Which stylus profiler model should I choose?

  KLA offers a wide range of stylus profilers, from entry-level benchtop systems to fully automated production systems:

  Profiler	2D/3D	Max Scan Length (mm)	Max XY Sample Size (mm)	Optics	Stage Types	Automation
  Alpha-Step® D-500	2D	30*	D = 140	Side	Manual XY Motorized Z	None
  Alpha-Step® D-600	both	55*	D = 200	Side	Motorized XY Motorized Z	None
  Tencor® P-7	both	150*	D = 200	Top or side	Motorized XY Motorized Z Manual or motorized θ	Optional
  Tencor® P-17	both	200	D = 200	Dual	Motorized XY Motorized Z Motorized θ Leveling	Optional
  Tencor® P-17 OF	both	200*	D = 300 or 240mm square	Dual	Motorized XY Motorized Z Motorized θ Leveling	Optional
  Tencor® P-170	both	200	D = 200	Dual	Motorized XY Motorized Z Motorized θ Leveling	Included + wafer handler
  HRP®-260	both	200	D = 200	Dual	Motorized XY Motorized Z Motorized θ Leveling	Included + wafer handler

  ^* without stitching

• Can stylus profilers measure thin film stress?

  Yes. By measuring wafer bow and curvature before and after film deposition, stress can be calculated using methods such as Stoney's equation. 2D stress measurement is available for all KLA stylus profilers, and 3D stress measurement is available for the Tencor^® P Series and HRP^® stylus profilers.

  Learn More: 2D Stress

  Learn More: 3D Stress

• Can a stylus profiler perform 3D measurements?

  Yes. The fundamental measurement is a 2D line scan, with multiple scans combined to generate full 3D surface maps. All KLA stylus profilers can generate 3D topography, except the Alpha-Step^® D-500, which has 2D profile capability only.

• How does stylus tip size affect results?

  The tip radius determines the smallest feature that can be accurately resolved. Smaller tips improve lateral resolution but typically wear faster and require more careful handling.

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• What is the minimum measurable step height?

  For current KLA stylus profilers, the practical lower limit is approximately 5nm, with angstrom-level vertical resolution available on higher-end systems.

• What is the maximum measurable step height?

  Depending on the model, step height measurements can range from nanometers up to approximately 1.0-1.2mm (1200μm).

• How is a stylus profiler different from AFM?

  Feature	Stylus Profiler	AFM
  Field of view	Up to hundreds of mm	Typically hundreds of μm
  Vertical resolution	Å-level	Atomic-scale
  Throughput	Faster for large areas	Slower
  Scan size	Large	Small
  Ease of use	Generally simpler	More complex

• What applications benefit from stylus profilers?

  • Semiconductor fabrication
  • Compound semiconductors
  • MEMS
  • Photonics and Optoelectronics
  • Photovoltaics
  • Thin films
  • Data storage
  • Biomedical devices
  • Consumer electronics

• What stylus force should I use?

  The lowest force that still maintains good contact is generally recommended. Lower forces reduce risk to both the sample and stylus and help when measuring soft materials. KLA sensor technologies are designed to ensure a constant, programmable applied force.

• What is the typical radius of a profilometer stylus?

  KLA stylus profilers include a standard 2µm or 5µm radius stylus, with additional types available for different applications.

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• What material is a profilometer stylus tip made from?

  KLA profilometer stylus tips are made from diamond to provide durability and ensure long-lasting wear resistance.

• What are the key advantages of KLA stylus profilers?

  Frequently cited differentiators include:

  • Direct material-independent measurements
  • Very low force control (down to 0.03 mg)
  • Long scan lengths without stitching
  • Large vertical range (up to 1200μm)
  • Angstrom-level resolution
  • Integrated 2D and 3D analysis
  • Extensive semiconductor process applications

• How do I get started?

  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 and KLA Service will work with you to ensure your site is install-ready. 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, and a maintenance schedule is provided/coordinated by the KLA Service team. To order new or replacement styli and 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.