VASE Ellipsometer

The VASE® is our most established and versatile ellipsometer. Useful for research on all types of materials, including semiconductors, dielectrics, polymers, metals, multi-layers, and more. Variable wavelength and angle of incidence enable flexible measurement capabilities. The VASE combines high accuracy and precision with the widest spectral range in the industry, 193 to 4000 nm.

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OVERVIEW

Why a VASE?

Maximum Data Accuracy

The VASE features a rotating analyzer ellipsometer (RAE) combined with our patented AutoRetarder® for unparalleled data accuracy.

High Precision Wavelength Selection

Our custom-built scanning monochromator is designed specifically for spectroscopic ellipsometry, optimizing speed, wavelength accuracy, and light throughput, while
automatically controlling wavelength selection and spectral resolution.

Flexible Measurements

The VASE features a vertical sample mount and vacuum stage to accommodate a large variety of measurement geometries including reflection, transmission, and
scattering.

Extended Wavelength Range

The VASE offers multiple combinations of detectors, including our latest 4IR extension which allows for measurements up to 4000 nm.

FEATURED COMPONENTS

AutoRetarder® Technology

The VASE is able to collect the most accurate data of any ellipsometer through its use of our patented AutoRetarder. The AutoRetarder adjusts the polarization state of the incident measurement beam to provide optimal sensitivity for all types of materials. This provides an optimum measurement for any sample, under any conditions.

AutoRetarder accurately measures:
+Ψ and Δ over the full range
+Generalized (anisotropic) Ellipsometry
+Depolarization data
+Mueller-matrix data

Custom Monochromator

Our custom-built, double-chamber monochromator provides superior stray-light rejection. Up to four gratings are used to provide the most efficient reflectivity across the measured spectral range. The monochromator is located before the sample, which restricts the intensity of light incident on the sample to just a narrow bandwidth around the wavelength being measured. This avoids photo-bleaching of light-sensitive samples, as can happen for other ellipsometers where the monochromator is placed after the sample.

Extended NIR Detection

The VASE has always offered the widest wavelength range of our UV-VIS-NIR ellipsometers. We recently added a new liquid-nitrogen-cooled InSb detector for measurements up to 4 μm in the infrared. The detector is enclosed inside a liquid nitrogen dewar; when filled before data acquisition, it provides up to
eight hours of data collection. Combined with our standard UV-VIS detector, the continuous spectral range from 193 to 4000 nm can be measured.

APPLICATIONS

Optical Coatings

Ellipsometry plays an effective role in both the design and manufacturing stage of optical coatings. Anti-reflection coatings, notch filters, and highly reflective film stacks are all examples of material systems composed of high/low-index films. The optical properties and thickness of each layer in a coating stack play a pivotal role in determining the performance of a coating stack within a given wavelength range.

Thin Absorbing Films

The variable angle capability of the VASE enables characterization of thin metal films. Transmission intensity measurements are easily acquired with the VASE. Simultaneous analysis of ellipsometry and transmission-intensity data enables characterization of very thin, non-opaque metal films less than 50 nm thick, including graphene, TiN, Au and more.

Semiconductors

Ellipsometry is highly sensitive to surface roughness and oxide layers that natively grow on most semiconductors. In addition, optical bandgap, electronic transitions, and critical points can be determined for bulk and thin-film semiconductor materials such as GaN, InP, SiGe, CdTe, etc. Crystallinity and alloy composition can also be determined by monitoring the shape and wavelength position of the critical points.

Liquid Studies

Liquid cells enable in-situ, real-time study of surfaces under varying liquid ambients. Typical studies include protein attachment, etch rates of photoresists, and oxide growth through electrolysis. Optical properties of liquids can also be accurately determined using the VASE with our liquid prism cell via the minimum deviation
experiments.

SPECIFICATIONS

Ellipsometer Configuration	Rotating Analyzer Ellipsometry (RAE) with patented AutoRetarder®, and automated wavelength selection via our custom monochromator
Spectral Range	Standard: 240-2500 nm +DUV extension: adds 193-240 nm +XXIR extension: adds 2500-3200 nm +4IR extension: adds 2500-4000 nm (requires liquid nitrogen cooling)
Number of Wavelengths	User defined before measurement
Angles of Incidence	+Fully-automated +Range: 15° to 90° (standard system) +Accuracy: 0.01 °
Data Acquisition Rate	+Typical: 0.1 to 3 seconds per wavelength, depending on reflectivity of sample. +High Accuracy: measurements using full- AutoRetarder capability require 20 seconds per wavelength.
Max substrate thickness	20mm
Power Requirements	100, 110, 220, 240 VAC, 50-60Hz, 4/8 Amps
Software	WVASE
Light Source	75 watt, convection-cooled xenon lamp
Dimensions	shown below

vase-ellipsometer-dimensions

ACCESSORIES

Temperature Control

By adding a cryostat or heat stage to the VASE for variable temperature studies, measurements can be conducted at temperatures as low as 4.2K and as high as 1000° C.

Linkam Standard Heat Stage

The Linkam Standard Heat Stage enables temperature-controlled ellipsometry measurements between -70° to 600° C with stability of 0.1° C. The heating chuck is 22 mm in diameter and can accommodate similarly sized samples. The heat stage features a custom lid with optical ports configured for ellipsometry measurements at 70° (AOI) to promote a controlled environment and enable purging when necessary.

Linkam High-Temperature Heat Stage

Linkam’s High Temperature Heat Stage is intended for applications that require temperature above 600° C. This heat stage enables measurements up to 1000° C by incorporating a crucible heater in the temperature stage. The crucible design is compatible with samples up to 17 mm in diameter and is sold with a custom lid that enables ellipsometry measurements at 60° (AOI). Customers with primary interest in temperature measurements below 600° C should consider the standard heat stage.

Lake Shore Cryostat

The Lake Shore Cryostat provides an ultra-high-vacuum, continuous-flow cryostat for variable temperature studies between 4.2 to 800 K. The cryostat can accommodate samples up to 25 x 25 mm and has optical viewports for ellipsometry measurements at 70° (AOI). The cryostat includes a temperature controller, turbo vacuum pump, custom table, and software for coordinating temperature control with ellipsometric measurements.

Liquid Studies

Several cells with optical windows for measurement through liquid ambient enable characterization of liquid/solid interface. Options include:

+45mL Electrochemical Cell
+270uL Liquid Cell
+5mL Liquid Cell
+Liquid Prism Cell

Sample Mounting Options

We offer a variety of sample stage mounts to accommodate your measurement needs. Our standard and small sample stages are provided with every ellipsometer, while the others are available as upgrades. Options include:

+Standard Stage
+Manual Translation
+Small Sample Stage
+Automated Translation
+Sample Rotator
+Auto-Z Stage

Focusing & Camera

Add focusing optics to decrease the measurement beam diameter. Our standard focusing option provides a 100 μm beam diameter. Our alternate focusing option provides a slightly larger, 200 μm beam diameter, but can be used during transmission measurements. Focusing optics are detachable for normal use. Add a camera to view the measurement spot on the sample and improve beam positioning.

FAQ

What advantages does VASE have over other UV-VIS-NIR models?

With our original VASE system, users have maximum control over measurement settings (including precise wavelength selection), the monochromator source protects sensitive samples from wide spectrum exposure, and the wavelength range can be extended up to 3.2 microns.

Can the VASE be used in situ?

M-2000 or RC2 are preferred.

Which software package is included?

WVASE

VASE Ellipsometer

Why a VASE?

Maximum Data Accuracy

High Precision Wavelength Selection

Flexible Measurements

Extended Wavelength Range

AutoRetarder® Technology

Custom Monochromator

Extended NIR Detection

Optical Coatings

Thin Absorbing Films

Semiconductors

Liquid Studies

Temperature Control

Linkam Standard Heat Stage

Linkam High-Temperature Heat Stage

Lake Shore Cryostat

Liquid Studies

Sample Mounting Options

Focusing & Camera

What advantages does VASE have over other UV-VIS-NIR models?

Can the VASE be used in situ?

Which software package is included?

Ellipsometers

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