variable angle stokes
ellipsometer L116S300 description
The model L116S300 for up to 300mm wafers builds on the
production proven Gaertner 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 L116S300 model
sets a new and even higher performance standard to meet today's more demanding metrology
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 LGEMP and optional LMOD
modeling software permits multiparameter measurements utilizing the
manually selectable angles of incidence.
The 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.
speed film thickness measuring system measures in less than a second!
The L116S300, based on advanced StokesMeter™ technology, offers instantaneous measurement at a low cost and is upgradeable to the
Imaging Waferskan, Two or Three Wavelength ellipsometers.
- Tilt-free, focus free, hands-off
operation for similar wafers.
- Fastest possible instrument for
thin film measurement.
- Variable angle useful for
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 ellipsometry.
- Simple, compact tabletop instrument
- competitively priced.
An outstanding feature is the
Stokes Ellipsometer's compensation for small changes in angular beam deviation caused by
sample thickness changes. This permits fast, uninterrupted measurement over the entire wafer
surface without the need to pause to correct for focus and tilt. When
wafers, tilt-free, focus-free operation is the obvious
description of stokesmeter™
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 S. 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.
Linear Rotary Stage L116LRS
(see photo above)
This linear rotary stage is moved by hand in a linear and 360º
rotary motion so that different areas on the
sample can be conveniently measured. The 8" sample table can accept up
to 300mm wafers and has 150 mm
left to right cross travel and can be scale read to 1 mm. The L116LRS
accepts sample thickness up to 1/2 inch and has provision for vacuum and
tilt up to 1 degree.
XY Linear Rotary Stage L116LRSY
This stage is same as the L116LRS except ± 1" micrometer front to back
travel in Y is added. The added Y coordinate motion facilities measurement
of a XY rectangular pattern.
Microspot Optics L116MS
Consist of both a
projector optic that reduces the normal 1mm laser beam diameter down to 15 microns and a
receiver optic. At 70 degrees incidence, 15 X 52 micron sample areas
can be measured. At 50 degrees incidence the measured area is 15 X 35 microns. Microspot
Optics are factory installed and non-removeable.
Polarizer Drum LPD (see photo above)
Polarizer drum divided 0 to 360º, settable to 0.1º, containing a Glan
Thompson prism added to the polarizer arm of the ellipsometer. Used to
change the azimute of the linear polarization for certain in-line
transmission measurements of transparent materials.
Stokes Calibration Kit
Permits recalibrating any Stokes Ellipsometer using calibration software and
4 wafers and glass. Gaertner traceable L118G-KIT or NIST traceable
users will not
require ellipsometer recalibration.
Intended for the most
exacting semiconductor manufacturers with extremely tight tolerances and
regulatory compliant users
L116S300 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
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. In addition, 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 are simply too rough and
scatter too much light to be measured ellipsometrically.
variable angle stokes ellipsometer
axis of rotation of incident arms is in the sample plane. Angles are easily selectable
with no need for alignment prisms or sample readjustment.
45º, 50º, 55º, 60º, 65º, 70º, 75º, 80º, 90º
||Advanced StokesMeter measurement head
6328 Angstrom Laser gives less than 1 mW output on sample
diameter (1 x 3mm on wafer @ 70º)
micron diameter (15 x 52 micron on wafer @ 70º)
State with no moving parts
39 power microscope (for surface viewing)/tilt monitor (for checking sample out of
||Up to 300mm
inch table with provision for vacuum is freely positioned by hand. 1/2
inch height adjustment together with tilt corrects for sample out of flatness
of up to 1º in both X and Y planes. Docking pedestal can be separated
to accommodate 2 inch thick samples or special fixturing.
10/8/7/ VISTA/XP LGEMP measures on up to 4 absorbing layers.
with available USB port .
||Sub-Angstrom over most of the measurement range
over most of the measurement range.
100V, 220V, 230V, 240V
Width: 33 inches
Depth: 15 inches
Net Weight: 65 lbs.
Shipping Weight: 95 lbs.
||USB cable connects Windows PC to ellipsometer
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.
Stokes Ellipsometers comply with European electrical directives and
carry the CE mark.