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Ellipsometer

Ellipsometer

Ellipsometer
Manufacturer
J.A. WOOLLAM
Model
RC2-XI
Category
Spectroscopy
Application

Ellipsometry measurements are ideal for thin film and multilayer characterization.

Generalized ellipsometry collects six values compared to the standard two (Ψ, ∆). This additional information completely characterizes the cross- polarization of anisotropic samples.

The light source has low power density: applicable on in vivo tissues.

Ellipsometry can measure:

  • film thickness,
  • refractive index n as a function of wavelength,
  • extinction coefficient k as a function of wavelength,
  • surface roughness,
  • interfacial mixing and thickness,
  • uniformity,
  • anisotropy,
  • composition, crystallinity,
  • graded film (optical constant change with the thickens).
Description

Wavelength range: 210 – 1690 nm.

Nr of wavelengths: 1065.

Incident angles: 45° – 90°.

Measure complete spectrum in 1/3 of a second.

Spot size: 120 μm.

Sample scan: up to 200 mm (8 inch).

 

Obtainable Data

  • Film thickness
  • Dispersion of complex optical constants:
    • Refractive index n
    • Extinction coefficient k
  • Band gap
  • Surface roughness
  • Interfacial mixing
  • Uniformity
  • Anisotropy
  • Composition
  • Crystallinity
  • Graded film
  • Porous films

Materials

  • Thin films starting from ~1 nm
  • Thick films up to ~ 10 mm
  • Multilayers and bulks
  • Any materials (metals, semiconductors, dielectrics), which reflects light in the given wavelength range
  • Liquid samples

Application

  • Low bandgap semiconductors
  • Conductive organics
  • Metals, alloys
  • Dielectrics
  • Mapping: map thin film uniformity (e.g., of wafers or glass panels)
  • Anisotropic applications

Display applications: measurements of a-Si, poly-Si, microcrystalline-Si, OLED layers, color filters, ITO, MgO, polyimide, and liquid crystals are beneficial during display R&D and production.

 

PRECISION AND ACCURACY

  • Data accuracy: Y = 0.006°, D= 0.015°
  • Thickness precision, StdDev down to 0.01 Å
  • Optical constant precision, StDev down to 0.0001

 

MEASUREMENT CAPABILITIES

  • SE: Y and D over their full wavelength range
  • Generalized SE: complete 2×2 Jones matrix for anisotropic samples
  • Mueller Matrix SE: all 16 elements of the 4×4 Mueller matrix
  • Depolarization: measure and model the non-ideal nature of your sample

Intensity: both reflectance and transmittance, including anisotropic terms such as like and cross-polarized intensities.

Other Applications

  • Transmission measurements
  • Thermo-optical investigations
  • Se measurements on in vivo tissues

WORKING PRINCIPLE

Spectroscopic ellipsometry (SE) measures changes in the reflectance and phase difference between the parallel (Rp) and perpendicular (Rs) components of a polarized light beam upon direct reflection from a surface of liquid or solid sample. 

Reflectance (p, s) is described by the main ellipsometric angles Y and D. Because ellipsometry measures the ratio of two values originated by the same signal, the data collected are highly accurate (e.g., can detected thickness down to Å resolution), and reproducible. Most importantly, no reference specimen is necessary; the measurements are independent from the light source intensity and mechanical vibrations.

 

 

 







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