Ellipsometer

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Model No: HO-TCE-01

Ellipsometry is a very sensitive optical technique which provides unequaled capabilities for thin film metrology. Ellipsometry exploits phase information and polarization state of light and so can achieve angstrom level resolution. The main advantages of ellipsometry are its non-destructive character, high sensitivity and wide measurement range. The optical parameters like thickness and refractive indices of a thin film can be determined precisely by this technique.

In the ellipsometer model no: HO-TCE-01, an elliptically polarized light is made to incident on the test substrate and the reflected light which is linearly polarized is analyzed for polarization changes.

The instrument consists of two concentrically rotating arms around a precisely graduated disc fixed to a heavy base. A laser source is held on one arm and the detector assembly on the other arm. The graduated disc has 1 degree scale and 0.1 degree resolution achieved through a vernier. Power supplies for laser source and detector are placed separately. Polarizer, analyzer and quarter wave

plate are held in precision rotary stages in the optical path with precise graduations having 0-360 degree range and 0.1 degree resolution. Glan-Thompson Prisms are used for both polarizer and analyzer. Sample is placed on a precision micrometer driven vertical stage with height adjustment range of 10 mm and resolution 0.01 mm. Incident angle for laser source can be adjusted between 30 degree and 90 degree. For null method, detector can be replaced with a miniature screen for visual determination of null point, if required.

Measurement Range : 1 nm ~ 300 nm
Incident Angle : 30° ~ 90°, Error ≤ 0.1°

Rotation Range
Polarizer : 0° ~ 360°
Quarter-Wave : 0° ~ 360°
Resolution : 0.1 degree

Laser : DPSS
Rotation range : 70 degrees (from horizontal plane)
Main scale division : 1 degree
Resolution : 0.1 degree

Detector
Type : Si Photodiode with 5.8 x 5.8mm active area

Detector Arm
Rotation Range : 70 degrees (from horizontal plane)
Main scale division : 1 degree
Resolution : 0.1 degree

Sample holder
Height adjustment range : 10mm
Drive resolution : 10 microns
tilting range : +/- 2 degree

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Procedure

As shown in the figure right, randomly polarized laser light (532nm) passes through a polarizer (Glan-Thompson Prism) which changes the polarization of light from random polarization to linear polarization. The linearly polarized light then passes through a quarter-wave plate (set the fast axis at 45 degree) which changes the polarization state from linear to elliptical. After reflection from the sample thin film, the elliptically polarized light become linearly polarized and an analyzer (Glan-Thompson Prism) measures the degree of polarization.

Software

Holmarc has developed a unique software to be used along with the instrument for analyzing the data. The software which can be loaded into any personal computer plots the Δ – ψ graph and optical constant can be determined from the plot. It can be used for finding out simple and complex refractive indices

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