VASE

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.

Features

Maximum Data Accuracy

The VASE features a rotating analyzer 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, shown in red below.

Specifications

Spectral Range
• Standard: 240-2500 nm
• +DUV extension: adds 193-240 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: WWASE

Light Source: 75 watt, convection-cooled xenon lamp

Options

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.
• Basic Temperature Stage (room temp to 300°C)
• Standard Temperature Stage (-70°C to 600°C)
• Cryostat (4.2/77 to 500 Kelvin or 4.2/77 to 800 Kelvin)


Liquid Studies


Cells with optical windows are available 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 ?m beam diameter. Our alternate focusing option provides a slightly larger, 200 ?m 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.