Near Normal Spectroscopic Reflectometer is a fundamental instrument used for thin film thickness analysis for industry & research. Holmarc’s NNSR (Model No: HO-NNSR-01) is able to analyze thin film’s thickness, complex refractive index & surface roughness with high speed & repeatability. NNSR theory works with complex matrix form of Fresnel equations. Absolute reflectance spectroscopy is the principle behind Reflectometer; which is the ratio of the intensity of the reflected light beam (usually polychromatic) to the intensity of the incident beam. Light beam which normally incident on the sample surface in turn reflect from top & bottom of the thin film which get interfered & is directed through optical fiber (Bi-furicated fibre) to CCD attached spectrometer via computer. On the monitor we get spectrogram with interference oscillations directly proportional to thin film thickness.
Holmarc’s Reflectometer can be used to analyze single, multi-layer, free standing & rough layer thickness of various stacks such as dielectric, crystalline, amorphous, metallic & absorbing samples. It also finds absolute transmittance & absorption directly for linear di-electric thin films. Roughness treatment is done with EMA modeling such as linear, Bruggemann & Maxwell garnet approximations. Manual scanning is provided for finding out roughness & uniformity of thin films. Without refractive index or any other optical properties, NNSR is able to find the thickness of thin / thick film & estimate its optical properties.
|Film Thickness Range||:||25nm – 3.5 μm|
|FFT Thickness Range||:||3500nm - 35 μm|
|Spectrometer wavelength range||:||340nm - 940nm|
|Reflectance wavelength range||:||390nm - 940nm|
|Light Source||:||Tungsten Halogen Quartz Lamp, 20 & 50W (customized)|
|Detector||:||CCD linear array, 3648 pixels|
|Transmission method||:||Bi-furicated fibre [Glass core & PMMA cladding]|
|Precision for thin film stack||:||± < 1 nm|
|Accuracy for same stack||:||± < 2 nm (without roughness) (compared with SEM)|
|Spot size on sample||:||120 micron with the 5X SLWPA objective|
|Working Distance||:||3 mm|
|Optical fiber||:||Multimode Bi-furcated fiber with SMA|
|Scanning||:||Manual (Micrometer controlled 15mm scanning)|
|Reference Sample||:||Bare NSF66 / Bare Aluminum (customized) / Normal slide|
|Dark Sample||:||N-Bk7 black coated / Al Mirror kept at 45° (customized)|
|Standard Sample||:||SiO2 thin film on NSF-66 Substrate / Bk7 substrate|
|Measuring modes||:||Curve fitting / Regression Algorithms, FFT, FFT + Curve Fit|
|Dispersion formulas||:||Cauchy, Sellmeier & Empirical Models|
|EMA models||:||Linear EMA, Bruggemann, Maxwell Garnett models|
Analyze single and multi-layer films (Indirect method)
Fiber optic probe for reflectance measurement at normal incident angle.
CCD linear array detector for absolute reflectance measurement.
Levenberg - Marquardt curve - fitting algorithm for thickness measurement.
FFT based Thick-layer thickness measurement standardized with PET films.
Linear, Bruggemann & Maxwell Garnet approximation models for roughness measurements.
Absorption & Transmittance studies.
Parameterized dispersion models such as Cauchy, sellimier, combination & drude for n and k values.
User extendable materials library
Data can be saved as an Excel file for extraction of optical properties