300mm stokes waferskan™ ellipsometer
The model LSE-WS Stokes WAFERSKAN Ellipsometer is a high speed film
thickness mapping system measuring one site per second including stage
travel! It uses advanced StokesMeter™ technology
(previous winner of Photonics Spectra and R&D 100 best new products
awards) to give tilt-free, focus
free, 2D/3D color thickness and index images on any size wafer up to 300mm .
The units' elegant design offers unprecedented ease of use and instantaneous measurement
at a cost much lower than conventional production control metrology systems.
Affordably priced the LSE-WS is a popular choice in a high precision scanning ellipsometer.
- Trouble-free, no moving parts advanced StokesMeter™
- Measures complete state of polarization providing increased accuracy.
- Accurate, stable measurements using spectrally precise laser
- Fastest possible instrument for thin film measurement.
- Tilt-free, focus free, hands-off operation for similar wafers.
- Simple, compact tabletop instrument - competitively priced.
high accuracy and performance
The model LSE-WS
builds on the production proven Gaertner WAFERSKAN™ line of ellipsometers
in widespread use throughout the world. From thin gate oxides only tens of
angstroms thick to thick polyimides and photoresists Gaertner has earned a
reputation for providing precise, reliable results. The model LSE-WS sets a
high performance standard to meet today's more demanding
Single Layer films such as oxides,
nitrides and photoresists can be measured to sub-angstrom precision. Two, three and
four layer films, with know bottom layers such as poly on oxide and oxide on poly on oxide
can be measured for the thickness and refractive index of the top layer or for both
thicknesses. Windows™ software enhances ease of use and understanding.
The measurement results are displayed on the computer monitor and can be sent to a printer. Results stored in a
text data file are displayed in a 2D contour or 3D Map images. The images
can be rotated, tilted, reduced or enlarged for
immediate viewing and
2D contour image of film thickness
3D contour image of film thickness
easy to use
The LSE-WS Stokes
WAFERSKAN™ is simple to operate. The user interacts with a single main
program screen so the set up is easy to understand and the measurement can
be quickly made. Stored
recipes are readily accessed for scanning
different films and patterns. Similar wafers are automatically scanned with
a single mouse click. The operator can chose 1, 5, 9, or 49 point circular measurement,
X-Y grid, diameter, or Polar Scans with up to 1000 measurement
points and set the wafer edge exclusion.
high precision stages
stepping motor stages provide precise and repeatable positions. The wafer is
held on the optically flat table by vacuum. The stages move automatically in
rapid yet precise steps under programmed computer control. Measurement time
is less that one second per point including stage travel. Step precision is
better than 10 microns, with the area of coverage and points within that
area easily set for automatic scanning.
The LSE-WS Ellipsometer measures by
reflecting a polarized laser beam from the sample surface at a 70° incident
angle and determines the change in polarization caused by the sample virtually
instantaneously. Since there are no moving parts in the StokesMeter™
measuring head the measurements are accurate and repeatable even after many months of continuous use.
Precision of measurement is further enhanced by the use of a stable, spectrally precise, high
signal to noise HeNe gas laser light source.
description of stokesmeter™ technology
This advanced device uses no
moving parts and no modulators to quickly and accurately determine the
complete polarization state of the measuring beam.
The diagram above shows the StokesMeter™ photopolarimeter for the
simultaneous measurement of all four Stokes parameters of light. The light beam, the state
of polarization of which is to be determined, strikes, at oblique angles of incidence,
three photodetector surfaces in succession, each of which is partially spectrally
reflecting and each of which generates an electrical signal proportional to the fraction
of the radiation it absorbs. A fourth photodetector is substantially totally light
absorptive and detects the remainder of the light. The four outputs thus developed form a
4x1 signal vector I which is linearly related, I=AS, to the input Stokes vector
Consequently, S is obtained by S=A(-1)I. The 4x4 instrument matrix
A must be nonsingular,
which requires that the planes of incidence for the first three detector surfaces are all
different. For a given arrangement of four detectors, A can either be computed or
determined by calibration.
The simple, compact StokesMeter™
replaces a typical rotating analyzer assembly consisting of a drum, prism, encoders,
switches, motor and detector and their associated electronics. In addition, the waveplate
mechanism on the polarizer arm, is eliminated. This results in a fast, precise, stable no
moving parts ellipsometer.
An outstanding feature is the
Stokes Ellipsometer's compensation for small changes in angular beam deviation caused by
sample out-of-flatness. This compensation permits fast, uninterrupted scanning over the entire wafer
surface without the need to pause to correct for focus and tilt. When scanning similar
wafers, tilt-free, focus-free, hands-off operation at high speed is the obvious
Optional LMS Microspot system shown above
optional Microspot System LMS
for measuring small areas on your wafer with a 15 micron measuring laser
beam diameter. 10 micron stage positioning and CCD camera
viewing of the measurement area on your PC permits areas as small as 15 X 45
micron to be viewed and measured using advanced StokesMeter™ technology
optional Small Spot optic LSS
Reduces standard 1 mm laser beam to 0.25 x 0.75
mm on sample
optional L-SCAT SOLAR CELL / SCATTERING
Rough scattering samples common in the solar cell industry are difficult
to measure accurately with most ellipsometers because of the loss of signal
strength and depolarization of the measurement beam. Although there are ways
to boost the signal strength and capture more scattered light, dealing with
depolarization is much more difficult and ideally requires the determination of the
complete state of polarization namely the measurement of the 4 stokes
parameters s0, s1, s2, s3. Gaertner Stokes
Ellipsometers do this naturally as our StokesMeterä
polarimeter is used as the ellipsometer analyzer. This gives Stokes
Ellipsometers the unique ability to instantly separate the polarized from
the unpolarized components of the measuring beam thereby delivering a highly
accurate measurement of film thickness and index based only on the totally
polarized component of light. The L-SCAT scatter option includes a hardware
modification to capture more of the scattered light from rough, textured
surfaces and a program display of the degree of polarization P.
Keep in mind however that some samples may be simply too rough and
scatter too much light to be measured ellipsometrically.
optional Stokes Calibration Kit L118-KIT
Recalibrate any Stokes Ellipsometer using
4 Gaertner traceable wafers plus glass (L118G-KIT)
4 NIST traceable wafers plus glass (L118N-KIT). Most
not require ellipsometer recalibration.
Intended for the
most exacting semiconductor manufacturers with extremely tight tolerances and
regulatory compliant users.
stokes waferskan™ ellipsometer
table height via computer alignment screen. Proprietary tilt and
table height system corrects for ordinary sample tilt and out-of-flatness with no need for sample readjustment or complicated, costly
and slow autofocusing systems.
||Advanced StokesMeter reads the complete beam polarization using no moving parts and no
modulators, only 4 stationary silicon detectors so measurements are exact and stable.
||One second per point including stage travel.
precise, stable, long lasting HeNe 6328A Laser with 1 mm beam diameter
(1x3 mm on wafer at 70 Typical lifetime is
over 3 years.
Similar light source used by NIST to produce calibration standards.
Optional Microspot has a 15 x 45 micron spot with CCD camera
||670 nm Laser
graphics runs under Windows™ included
||Up to 300mm diameter standard.
Vacuum held (requires 5 inch Hg.).
Stepping Motors under user programmed computer control with manual pushbutton
override. 150mm linear and 360° rotary motion covers any point on the sample. Tiltable
table permits correction for sample out-of-flatness up to 1° in both X and Y planes.
Map any size wafer up to 300mm at 1 second per point.
color images of film thickness, refractive index and location to monitor,
file or printer. Text data file is easily exported to other programs.
||Windows™ 10 Laptop PC included
60,000 Angstroms on substrate or on 1, 2 or 3 known sublayers
||Sub-Angstrom over most of the measurement range.
over most of the measurement range.
100V, 220V, 240V (50/60 Hz)
18 inches Width: 28 inches Depth: 20 inches
Net Weight: 85 lbs. Shipping Weight: 200 lbs.
series Ellipsometers comply with European safety directives and carry the CE mark.
laser ellipsometers supplied by Gaertner comply with CDRH requirements 21CFR 1040 for a
Class II laser product emitting less than 1 mW or Class IIIb less
than 5 mW of low power radiation. As with any
bright source such as the sun or arc lamp, the operator should not stare directly into the
laser beam or into its reflection from highly reflecting surfaces.
||1 year warranty covers all parts and labor
exclusive of shipping costs