Substrates Used for Ellipsometry Measurements  

Ellipsometry is a powerful optical characterization technique used to measure thin film thickness, refractive index, extinction coefficient, and optical constants of semiconductor and dielectric materials. Researchers rely on silicon wafers, thermal oxide substrates, silicon nitride films, SOI wafers, GaN substrates, sapphire wafers, and fused silica for accurate ellipsometry measurements in semiconductor manufacturing, photonics, MEMS, nanotechnology, solar energy, and advanced materials research.

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Silicon Wafers for Ellipsometry and Thin Film Characterization

Silicon wafers are among the most widely used substrates for ellipsometry measurements because they provide an extremely smooth, stable, and well-characterized surface for optical analysis. Researchers use silicon substrates to measure thin film thickness, refractive index, extinction coefficient, and optical constants of deposited materials.

Prime-grade silicon wafers are often preferred for ellipsometry because they offer superior surface quality, excellent flatness, and minimal defects. These characteristics improve measurement accuracy when studying dielectric coatings, semiconductor films, polymers, oxides, nitrides, and advanced nanomaterials.

Common applications include:

  • Thin film thickness measurements
  • Refractive index characterization
  • Semiconductor process development
  • Optical coating analysis
  • MEMS device fabrication
  • Photonic device research
  • Solar cell development
  • Nanotechnology and materials science studies

Need Silicon Wafers for Ellipsometry? UniversityWafer supplies prime-grade, test-grade, mechanical-grade, SSP, and DSP silicon wafers in a variety of diameters, orientations, resistivities, and thicknesses.

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r Ellipsometry Measurements

Thermal oxide wafers are frequently used as calibration and measurement substrates for ellipsometry. The silicon dioxide (SiO₂) layer provides a well-defined optical structure that enables highly accurate thickness and refractive index measurements.

Researchers commonly select thermal oxide thicknesses ranging from 100nm to 2µm depending on the optical properties being evaluated. These substrates are widely used for studying silicon nitride films, dielectric coatings, optical waveguides, semiconductor devices, and multilayer thin-film stacks.

Available options include:

  • 100nm Thermal Oxide
  • 200nm Thermal Oxide
  • 500nm Thermal Oxide
  • 1µm Thermal Oxide
  • 2µm Thermal Oxide
  • Custom Oxide Thicknesses

Because thermal oxide has a well-characterized refractive index and excellent uniformity, it remains one of the most commonly used substrates in semiconductor and photonics research.

Common Silicon Wafer Specifications for Ellipsometry

Selecting the correct silicon wafer depends on the type of thin film being measured and the desired optical performance. The most common specifications used for ellipsometry applications include:

  • Diameter: 50mm, 75mm, 100mm, 150mm, 200mm, and 300mm
  • Crystal Orientation: (100), (111), and (110)
  • Dopant Type: Boron (P-Type), Phosphorus (N-Type), Arsenic
  • Resistivity: Low, Medium, or High Resistivity
  • Thickness: 200µm to 800µm+
  • Surface Finish: Single-Side Polished (SSP) or Double-Side Polished (DSP)
  • Grade: Prime, Test, Mechanical, and Reclaim

For the highest measurement accuracy, researchers typically choose prime-grade polished wafers with low surface roughness and excellent flatness characteristics.

How Thermal Oxide is Used in Semiconductor Research

Thermal oxide plays a critical role in semiconductor manufacturing and thin film research. The SiO₂ layer serves as an electrical insulator, diffusion barrier, optical layer, and protective coating. In ellipsometry studies, thermal oxide wafers provide a reliable platform for characterizing deposited films and verifying process uniformity.

Key applications include:

  • Gate oxides for MOSFET devices
  • Optical waveguide structures
  • MEMS device fabrication
  • Photonic integrated circuits
  • Silicon nitride deposition studies
  • Thin film process monitoring
  • Solar cell surface passivation
  • Advanced semiconductor packaging

Whether you need silicon wafers, thermal oxide wafers, SOI substrates, silicon nitride coated wafers, or custom semiconductor materials, UniversityWafer can provide substrates optimized for ellipsometry and thin film characterization research.

What is Ellipsometry and Why is it Important?

Ellipsometry system measuring thin films on silicon wafersEllipsometry is one of the most widely used optical characterization techniques for measuring thin film thickness, refractive index (n), extinction coefficient (k), and optical constants of semiconductor and dielectric materials. The technique is non-destructive, highly accurate, and capable of measuring films ranging from a few angstroms to several microns thick.

Researchers use ellipsometry to characterize deposited films, verify process quality, optimize semiconductor fabrication steps, and evaluate optical coatings. Applications include semiconductor manufacturing, photonics, MEMS devices, solar cells, optical waveguides, sensors, and advanced materials research.

Best Silicon Wafers for Ellipsometry Measurements

Prime grade silicon wafers are typically the preferred substrate for ellipsometry because they provide exceptional flatness, low surface roughness, and well-characterized optical properties. Single-side polished (SSP) and double-side polished (DSP) wafers are commonly selected depending on the measurement requirements.

Common specifications include:

  • 100mm, 150mm, 200mm, and 300mm diameters
  • (100) and (111) crystal orientations
  • P-type and N-type doping
  • Low, medium, or highly doped resistivities
  • Prime grade surface quality
  • Single-side polished or double-side polished finishes

For thin film characterization, prime-grade wafers are generally recommended because surface defects and excessive roughness can affect optical measurements and model accuracy.

Thermal Oxide Wafers for Thin Film Thickness Measurements

Thermal oxide silicon wafers are among the most common substrates used in ellipsometry studies. The silicon dioxide layer provides a stable and well-understood optical structure that enables highly accurate thickness measurements.

Researchers frequently use thermal oxide thicknesses ranging from 100nm to 2µm when evaluating:

  • PECVD silicon nitride films
  • LPCVD silicon nitride coatings
  • Optical waveguide structures
  • Dielectric thin films
  • Photonic devices
  • MEMS fabrication processes

Because SiO₂ optical constants are well documented, thermal oxide wafers serve as excellent calibration and reference substrates for ellipsometric analysis.

Silicon Nitride and Optical Waveguide Applications

Silicon nitride (Si₃N₄) deposited on thermal oxide is widely used in integrated photonics and optical waveguide fabrication. Ellipsometry allows researchers to accurately determine film thickness, refractive index, and extinction coefficient, all of which directly influence optical device performance.

Typical silicon nitride thicknesses evaluated by ellipsometry include 200nm, 400nm, and 800nm layers deposited by LPCVD or PECVD processes.

Gallium Nitride (GaN) Characterization Using Ellipsometry

Gallium nitride substrates and epitaxial structures are frequently analyzed using spectroscopic ellipsometry. Researchers use these measurements to determine optical constants, evaluate crystal quality, and compare experimental results with theoretical models such as density functional theory (DFT).

GaN ellipsometry is commonly used in the development of:

  • LEDs
  • Laser diodes
  • Power electronics
  • RF devices
  • High-electron-mobility transistors (HEMTs)

SOI Wafers and SIMOX Structures for Optical Analysis

Silicon-on-insulator (SOI) wafers provide a unique multilayer structure consisting of a device layer, buried oxide (BOX), and handle wafer. Spectroscopic ellipsometry can be used to characterize these layers and verify film thicknesses during research and development.

SIMOX SOI wafers are particularly useful when studying buried oxide structures, optical confinement, photonic devices, and advanced semiconductor architectures.

Polymer Film Thickness Measurements

Spin-coated polymer films are commonly deposited on polished silicon substrates for ellipsometric thickness measurements. The smooth surface of single-crystal silicon minimizes measurement uncertainty and provides excellent optical contrast for polymer characterization.

Applications include:

  • Organic electronics
  • Flexible electronics
  • Photoresists
  • Solar cell research
  • Biomedical coatings
  • Advanced polymer materials

Custom Substrates for Ellipsometry Research

UniversityWafer supplies custom substrates for ellipsometry applications, including silicon wafers, thermal oxide wafers, silicon nitride coated wafers, SOI substrates, GaN wafers, sapphire substrates, fused silica wafers, and other specialty materials. Custom diameters, thicknesses, crystal orientations, dopants, and film structures are available to support research, development, and production environments.

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