Thin Film Metrology
Optical thickness of a coating is determined by white light interference and thepattern is translated into optical thickness
through mathematical calculations.
Thin film metrology involves the use of
these mathematical calculations to thepresence and thickness of coatings whichhave been deposited on a substrate material using a variety of processes. The techniques available for this measurement
range from profilometry to ellipsometry,
spectroscopic reflectometry and x-ray
analysis. Avantes instruments and fiberoptic sampling tools enable spectroscopic
reflectometry measurements to supportapplications in a variety of industries fromsemiconductor to solar and optical coating
measurements. Avantes thin film solutions
provide measurement systems for single
and multi-layer thin films on a number ofsubstrates.

Thin Film Quality Control
Thin film deposition processes require
regular monitoring and quality control particularly as new recipes are implementedand optimized in a coating facility. Typicalapplications require regular quality control
inspection during the initial phases requiring a high-speed offline measurement
system to validate film thickness. Avantes
thin film solutions enable high-speed spotmeasurements which can facilitate thinfilm presence and thickness validation.

Thin Film Reflectometry
Spectroscopic reflectometry involves
illuminating samples with a white light(typically tungsten halogen or deuteriumhalogen) at an incident angle which isnormal to the sample and then measuring the reflectance and interference fromthe same geometry. Depending upon thenature of the coating ultra-violet, visible ornear infrared wavelength measurements
may be necessary to obtain an optimum
fitting of the measured curve relative
to the theoretical reflectance curve. The
theoretical curve is developed from a
database of optical constants (n and k).
The “n” value is the refractive index and“k” is the extinction coefficient. The sampling process initially involves measuring aApplications
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reference uncoated substrate followed by
the sample measurement using the sameconditions. Characteristics about the substrate (thickness and material) are inputs
for the software along with characteristicsof the thin film layers (material, thickness).
Reflectance spectra are captured and analyzed by software algorithms which compare the measured data to theoretical calculated values derived from the databaseof optical constants. The software provides
a calculated thickness value along with ameasure of goodness of fit relative to thetheoretical curve.

Single-layer Thin Film Metrology
Avantes’ single-layer thin film metrology
system consists of our AvaSpec-ULS2048USB2 fiber-optic spectrometer, AvaLightDHc/AvaLight-DH-S deuterium-halogen
light source or AvaLight-HAL tungsten
halogen light source, the FCR-7UV2002-ME (optional FCR-7UV400-2-ME forhigher throughput) fiber-optic reflection
probe and our Thin Film Stage. The software that drives the single layer system isAvantes’ AvaSoft-Thinfilm which is a 32 orsystem consists of our AvaSpec-ULS2048USB2 fiber-optic spectrometer, AvaLightDHc/AvaLight-DH-S deuterium halogen
light source or AvaLight-HAL tungsten
halogen light source, the FCR-7UV2002-ME (optional FCR-7UV400-2-ME forhigher throughput) fiber-optic reflection
probe and our Thin Film Stage. The software which drives the multi-layer system
is TFProbe 2.0 which is developed byAngstrom Sun Technologies and is fullycompatible with Avantes spectrometers.
This sophisticated application supports
up to five layer measurements and supports a variety of methods including nk
constants, dispersion, and effective media
approximation (EMA). TFProbe provides auser-friendly graphical user interface toinput layer structure parameters. The system can include an optional thin-film standard which provides sample uncoated andcoated substrates for validation purposes.
TFProbe supports UV/VIS and NIR wavelengths from 200-1700 nm and enables
the connection of multiple spectrometers
to support this broadband wavelength
measurement capability. For most specularsurface UV measurements, the AvaLightDHc compact deuterium halogen sourceis adequate, but for more diffuse coatedsurfaces, the higher power AvaLight-DH-S
is recommended.

This bundle was especially designed forsingle layer thin film measurements, witha light source, a reflection probe and astage and standard included. The setup
can measure thin films ranging from 10 nm
up to 50 μm with a resolution of 1 nm andsupports UV, VIS and NIR measurementsfrom 200 up to 1100 nm.

Typical applications:Spectrometer

AvaSpec-ULS2048CL-EVO

Grating UA (200-1100nm)
100 μm slit, DCL-UV/VIS-200
OSC-UA
AvaSoft-ThinFilm

Light source

AvaLight-DHc

PS-12V/1.0A

Fiber optics

FCR-7UVIR200-2-ME

64-bit application which supports single
layer measurements of thin films ranging
from 10 nm-50 μm with 1 nm resolution.
AvaSoft-ThinFilm supports UV/VIS andNIR wavelength measurements from 2001100 nm. The system is available with anoptional thin film standard which provides
samples of uncoated and coated substrates
for validation purposes. For most specularsurface UV measurements, the AvaLightDHc compact deuterium halogen sourceis adequate, but for more diffuse coatedsurfaces, the higher power AvaLight-DH-S
is recommended.

Multi-layer Thin Film Metrology
Avantes’ multi-layer thin film metrology

Thin FilmIncluded• Semi-conductor industry• Solar panels• CoatingThinFilm stage & standard

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