The ARCspectro Thin Film Thickness Measurement System
Non-Contact characterization of thin films with a high performant FT-NIR spectrometer
The combination of our high resolution NIR spectrometer
and our dedicated Arcspectro Thin-Film software permits us to
characterize film thicknesses and refractive indices of materials
within minutes.
Thanks to our high performant FT-NIR spectrometer we can
measure thick layers from 2 to 800 micrometers with no sample
preparation or complex measurement procedure. The Arcspectro Thin-film
software (mainly based on FT algorithms) is also capable to handle more
complex multi-layer samples. Compared to competitor's products, which
are mainly based on grating spectrometers, our system based on a NIR
Fourier transform spectrometer (very different from grating
spectrometers) has higher performances in SNR and resolution. The Arcspectro thin film is a versatile device that can also be used as a standard high-performance fibered NIR spectrometer for any other application in your lab!
Depending on your application spot size, probe or
wavelength range must be adapted. We have almost for every situation a
solution. Thanks to our variety of spectrometers (MIR, NIR or even a
combination of VIS-NIR) and probes (fibered or direct illumination), we
have an impressive toolbox to solve almost any problem.
Large spectral range (900nm to 2500nm) providing enhanced reliability.
Possibility to use MIR spectral range if requested.
Very high SNR (measure layers with small refractive index difference)
Fast measurements (about 10 seconds)
Versatile (NIR spectrometer can be used for other applications)
High resolution (permits to measure accurately thick layers up to 0.8mm)
Easy maintenance
Easy to use. No sample preparation. Simple procedure.
Customization of hardware and software on demand
Cost effective NIR range system.
Principle
Ellipsometry and spectral reflectance, on the other
hand, are both non-contact optical techniques that permit to
determinate precisely layer thicknesses. The Arcspectro THINFILM NIR
spectrometer uses the spectral reflectance of the sample to determine
the thickness of the different layers that compose the sample.
Due to the wave-like behavior of the light, the
phenomenon of light interferences appears into a layer thinner than the
half coherence length of the light. The light reflected at the first
interface can interfere with the light reflected at the second
interface and their interaction is dependant on the wavelength of the
light and the refractive index of the layer. This effect leads to
oscillations into the reflectance spectrum measured by this instrument.
The frequency of this oscillation gives information about the
thickness of the layer and its refractive index
As depicted in the schematic above, the first part
of the incoming light is reflected at the interface n1/n2 (point A).
The amount of light reflected depends on the incidence angle, n1 and
n2. Some light pass through the first interface and is reflected at the
second interface (n2/substrate at point B). The two “rays” of light
that are reflected back by the sample have a phase difference linked to
the optical path difference (OPD) given by ABC-AD.
If this difference is equal to a multiple of 2n, there is a
constructive interference and it will lead to a maximum in the
reflectance spectrum. If this difference worth 2n+1 , there is a
destructive interference and it will result in a minimum in the
reflectance spectrum. Finally, some wavelengths will lead to
constructive interferences and some to destructive ones. Consequently,
modulation with a certain contrast (depending on the phase step between
the layers) of the measured spectrum is observed. By applying a
frequency analysis (by FFT) of the measured spectrum (picture right) we
can deduce the thickness of the layer present on the substrate.
The precision of the measurement will essentially be given by the
performance of the spectrometer. The Arcspectro- NIR spectrometer has
an excellent SNR and wavelength precision which cannot be achieved by
usual grating spectrometers. Also, its high resolution permits to
characterize relatively thick films (up to 800um) over a large spectral
range.
Other parameters such as the precision of the
refractive index of the material, the flatness and alignment of the
sample, the divergence of the light will influence the absolute
precision of the measurement.
General Specs table:
Features | Arcspectro NIR THINFILM |
Spectrometer type |
Scanning FT-NIR spectrometer (900-2500nm) |
Spectral range | 900nm-2500nm |
Spectral resolution | 2cm-1 équivalent to 2 nm (optical, reporting interval: 1nm) |
Measurement geometry | Fiber illuminated and fiber collected light |
Light source | Arclight NIR halogen lamp 20W |
Measurement time | ~10s (depends of averaging) |
SNR (Full dynamic range-signle measurement) | >10'000:1 |
Thickness repetabiltiy measurement | 10 nm |
Measurable thickness range | 2um to 800um (lower if used with VIS-NIR spectrometer on demand) |
Minimal refractive index step | < 0.01 |
Operating temperature | 10°C-40°C |
Operating power | 12V / 15W (line power adaptor is included) |
Communication Interface | USB |
Software interface | Windows 7 / 10 |
Product dimensions | 38mm x 25cm x 32cm |
Product weight | 2 kg |
Applications
Measurement of thin plastic films
In a few clicks, you can verify the thickness of any
plastic film. Ideal for quality control of plastic packing material.
Indeed with the Arcspectro THINFILM you can measure films up to 800um
which is sufficient for most packaging materials.
Coatings and membranes in Biomedial devices
The Arcspectro THINFILM spectrometer can also be used
in the medical field to determine for example determine catheter and
angioplasty Balloon wall thickness or on stends, small tubes,
implants...Also drug packaging thickness can be determined easily.
Wafers and membranes
In combination with a x-y table the Arcspectro THINFILM can be used for thickness mapping of all sorts of wafers..
Refractive index characterization
Not only films thicknesses but also refractive indices
can be determined. Indeed if the user knows exactely the the thickness
of the layer (detrmined by other means) it can determine the refractive
index of a material.
Materials that are only transparent in the IR
It happens that non-transparent materials must be
characterized. Some materials are only transparent in the IR region of
the spectrum. In this case, we can combine the Arcspectro THINFILM
software in combination with our ARCspectro-MIR spectrometer and also an
adequate transparent PIR or CIR fiber.