Silicon wafer fabrication involves many operations,
most of which require the accurate determination of
the temperature of the silicon. The surface tempe-
rature is an essential control variable for efficient
high-quality processing of material. As the wafer
is processed, the emissivity of the surface can vary
considerably due to the different properties of the
substrate layers. To enable the accurate and rapid
measurement of the wafer temperature, a reflective
cup is used. The reflective cup prevents ambient
radiation from entering the sensor, which instead
reads reflected emitted radiation. By reducing errors
caused by ambient reflections and emissivity
variations, the measurement error can be reduced
by about a factor of ten. The IRt/c.1X is a suitable
sensor to use for this application, as it is small and
can easily be mounted to the reflective cup. The
concept of the cone can be applied in other applications
in which target has low or varying emissivity.