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