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Posted: September 7, 2010
EpiCurveTT AR for Advanced Curvature Resolution in Planetary Reactors
(Nanowerk News) Recently, LayTec launched EpiCurveŽTT AR (advanced resolution)
for measurements of the aspherical curvature component
during epitaxial growth.
The tool is the perfect solution for
PlanetaryŽ and other gas-foil rotation MOCVD systems where
the azimuth of the rotating wafers is unknown. The standard
EpiCurveŽTT without AR measures randomly either along the
major axis (larger bow - blue arrow in Fig. 1) or along the minor
axis (smaller bow - red arrow in Fig. 1). In a PlanetaryŽ reactor
the phase of rotation is unknown. As a result, the signal
looks "noisy" (red line in Fig. 2): it oscilates between the maximum
and the minimum of the azimuthal aspherical bow.
Fig. 1: measurement principle with a 1-dimensional detection system (EpiCurveŽTT without advanced resolution)
Fig. 2: Curvature measurements with conventional EpiCurveŽTT (red) and EpiCurveŽTT AR (black): the new tool eliminates the aspherical distortion in the signal.
The new AR tool measures curvature along two perpendicular axes and eliminates 2nd order azimuthal bowing effects.
In Fig. 2, the black line shows the curvature signal of the new
EpiCurveŽTT AR sensor. The signal-to-noise ratio of the tool
with advanced resolution improves the curvature signal from
ą8 km-1 (red line) to ą 0.2 km-1 (black line) and measures only
the main curvature component by eliminating the aspherical
Even the quantity of asphericity can be extracted by analysis of
the advanced resolution signal. For further information please
ask us for the new application note about EpiCurveŽTT AR.