Imaging 300mm stokes waferskan™ ellipsometer
The L115S300 Stokes WAFERSKAN Ellipsometer's high speed film thickness
mapping system, based on advanced StokesMeter™ technology, measures 49
sites in 49 seconds! It is a fast instrument for thin film measurements
giving tilt-free, focus-free, automatic 2D/3D color thickness and
index images of the sample surface. The easy to use model L115S300 maps
wafers up to 300mm in diameter and offers precise measurements at a cost much lower then conventional production control metrology systems.
Tilt-free, focus free, hands-off
operation for similar wafers.
Micron measuring spot standard
tilt/viewing scope standard
difficult to measure films.
Trouble-free, no moving parts
advanced StokesMeter measurement head.
Measures complete state of polarization useful for rough,scattering
Accurate, stable measurements using
spectrally precise laser source.
Simple, compact tabletop instrument
- competitively priced.
high accuracy and flexibility of
The model L115S300 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 L115S300 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. New modeling software permits multiparameter measurements
utilizing the manually selectable angles of incidence.
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 Image Map. The image can be rotated, tilted, reduced or enlarged for
immediate viewing and
2D contour image map of film thickness
3D contour image map of film thickness
easy to use
The L115S300 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.
for device wafers
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 Stokes WAFERSKAN™ comes
equipped with a 15 micron measuring beam together with a combination
viewing/tilt scope standard.
The L115S300 Ellipsometer measures by
reflecting a polarized laser beam from the sample surface at one of eight available
incident angles 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
signal to noise HeNe 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 clean, 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 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 tremendous speed is the obvious
L115S300 can be equipped with the following laser
LS405 Substitutes 405 nm Blue
laser diode in place of 633 nm HeNe Gas Laser
LS544 Substitutes 544 nm Green HeNe Gas laser in
place of 633 nm HeNe Laser
LS830 Substitutes 830 nm laser diode in place of
633 nm HeNe Gas Laser
ADD ADDITIONAL LASER FOR A 2
L2W405 Adds 405 nm Blue Laser Diode
to 633 nm ellipsometer
L2W544 Adds 544 nm Green HeNe Gas Laser to 633 nm
L2W830 Adds 830 nm laser diode to 633 nm
ADD TWO ADDITIONAL LASERS FOR A 3 WAVELENGTH
L3W405.544 Adds 405 Laser Diode and 544
Green Gas Laser to 633 nm ellipsometer
L3W405.830 Adds 405 Laser Diode and 830nm laser diode to
633 nm ellipsometer
L3W544.830 Adds 544 Green Gas Laser and 830nm laser diode
to 633 nm ellipsometer
L-SCAT SOLAR CELL / SCATTERING
SAMPLE MEASUREMENT OPTION $2K
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 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 many samples are simply too rough and
scatter too much light to be measured ellipsometrically.
stokes waferskan™ ellipsometer L115S300 specifications
axis of rotation of incident arms in the sample plane means that incidence angles are
easily set with no need for alignment prisms. Measurement site remains the same at any
angle of incidence with no need for sample readjustment.
45°, 50°, 55°, 60°, 65°, 70°, 75°, 80°, 90° Manually selectable
||Advanced StokesMeter determines the complete beam polarization using no moving parts and no
modulators, only 4 stationary silicon detectors so measurements are exact and stable.
instantaneous. One second per point including stage travel.
precise, stable, long lasting HeNe 6328A Laser. Typical lifetime is greater than 3 years.
Similar light source used by NIST to produce calibration standards.
micron diameter (15 x 52 micron on wafer @70°) is standard
39 power microscope (for surface viewing)/ tilt monitor (for checking sample out of
||Up to 300mm diameter
standard. Vacuum held (requires 5 inch Hg.).
Stepping Motors driven 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.
Maps a 12" wafer at 49 measurement sites
in 49 seconds or one second per point.
color image maps of film thickness, refractive index and location to monitor, printer or disc
60,000 Angstroms on substrate or on 1, 2 or 3 known sub layers
||Sub-Angstrom over most of the measurement range.
over most of the measurement range.
100V, 220V, 240V (50/60 Hz)
18 inches Width: 33 inches Depth: 16 inches
Net Weight: 145 lbs. Shipping Weight: 300 lbs.
laser ellipsometers supplied by Gaertner comply with CDRH requirements 21CFR 1040 for a
Class II laser product emitting less than 1 milliwatt 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.
series Ellipsometers comply with European safety directives and carry the CE mark.