JASCO’s ellipsometer employs a proprietary polarization modulation technique (a PEM dual lock-in system) utilizing a photoelastic modulator, instead of the rotational drive mechanism of conventional ellipsometers.
Ellipsometry is a method for determining the refractive index and extinction coefficients of a sample by measuring the change in polarization state of surface reflected light. Film thickness and optical constants of an adsorption layer or oxide film on a substrate surface can be determined with exceptional sensitivity.
Conventional interference spectroscopy utilizes light passed through separate optical paths, while ellipsometry is a form of interferometry that uses two vibrational components with the same optical path, providing measurements with excellent accuracy and sensitivity.
The PEM dual lock-in system of JASCO's ellipsometer provides a stable measurement with additional capabilities including high-speed data sampling and wavelength scanning.
|Measurement System||PEM dual lock-in|
|Wavelength||650 nm utilizing LD light source
Xe light source with a single monochromator to provide a range of 350 - 800 nm
|Spectral Bandwidth||1 nm|
|Incidence Angle||Continuous automated settings from 45° to 90°|
|Film Thickness||1 - 99,999 Å|
|Measurement Time||1 msec or greater (20 µsec optional)|
|Beam Diameter||Refractive index: ±0.01
Film thickness: ±1 Å (±0.1 nm)
Extinction coefficient: ±0.01
Values are for measurements of 100 msec or more and vary according to surface state and film quality
|Sample Stage||Standard sample size: 15 to 150 mm square or circular samples|
|Optical System||Optical path switching mechanism
Polarizer (Rochon prism), photo-elastic modulator (PEM), and optical servo and reference optics
(Glan-Taylor prism, plane mirror, and photomultiplier)
|Sample Chamber||Standard stage allows custom incidence angles and variable sample sizes.|
|Detector System||Analyzer (Glan-Taylor prism) and photomultiplier (R928)|