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Spectroscopic Ellipsometry
Introduction to Spectroscopic Ellipsometry
http://www.jawoollam.com/tutorial_1.html
Ellipsometry is:
Precise AccurateWell known Non-destructive Analytical technique
It is used for a variety of measurements:Thickness of films.
DielectricsOrganicsSemiconductorsMetal layers Thickness Measurement RangeMetals 0.1 nm – 50 nmNon-Metals 0.1 nm – 0.01 mm
.
Optical propertiesRefractive indexCrystallinityUniformityModeling of surface roughness
Spectroscopic Ellipsometry Setup
1. Light Source
2. Linear Polarizer
3. Compensator
4. Analyzer
5. Detector
Sample
Unpolarized Light
Elliptically Polarized Light
Linearly Polarized Light
Multiple Wavelengths
Light Source
1. The light source consists of wavelengths in the following regions
Ultraviolet 185nm – 260nm
Visible 0.4nm – 0.7nm
Infrared 0.7nm – 1.1μm
http://www.flame-detection.net/flame_detector/flame_detection_school/flame_spectrum.htm
Components and Functions
2. Polarizer - produces light in a special state of polarization at the output
3. Compensator - used to shift the phase of one component of the incident light Depending on orientation, it transforms the ellipse of
polarization
4. Analyzer – second polarizer that detects the linearly polarized light reflected off the sample
5. Detector
http://www.nanofilm.de/fileadmin/cnt_pdf/technology/Ellipsometry_principle__150dpi_s.pdf
SE Advantages
No contact with the films is required for the analysis of films
Technique does not require a reference or standards
Analysis is less sensitive to the fluctuations of light intensity
Thickness measurement speed 1 – 300 sec/Location
https://www.filmetrics.com/metals
Single Wavelength Ellipsometry
Used in Imaging Ellipsometry
Commonly a HeNe laser with the wavelength of 632.8 nm
Advantages: Laser can focus on a specific spot Lasers have a higher power than broad band light
sources
http://www.eas.asu.edu/nanofab/capabilities/metrology.html
Single Wavelength Ellipsometry Setup
1. Light Source
2. Linear Polarizer
3. Compensator
4. Analyzer
5. Detector
Sample
Unpolarized Light
Elliptically Polarized Light
Linearly Polarized Light
One Wavelength
Imaging Ellipsometry
Combines SWE with Microscopy High Lateral Resolution
Possible to see tiny samples to detect various properties of samples
surface defects Inhomogenities
Advantages: Provides film thickness and refractive index Provides a real time contrast image of the sample Ability to restrict ellipsometric analysis to a particular region
of interest within the field-of-view The signal provided is spatially resolved to show the details
of the sample
http://www.soem.ecu.edu.au/physics/physics_facilities.htm
Two New Components
Imaging Ellipsometry Setup
Laser Light Source
Linear Polarizer
Compensator
Analyzer
Objective
CCD Camera
Sample
Unpolarized Light
Elliptically Polarized Light
Linearly Polarized Light
Thanks
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