Variable Angle Stokes...
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
applications.
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
precise, high
signal to noise HeNe laser light source.
high
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.
features
- 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
samples.
- 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
measuring similar
wafers, tilt-free, focus-free operation is the obvious
benefit.
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 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.
optional accessories
Linear Rotary Stage L116LRS
(see photo above)This linear rotary stage is moved by hand in a linear and 360
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. $4K
XY Linear Rotary Stage L116LRSY
This stage is same as the L116LRS except1" micrometer front to back
travel in Y is added. The added
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