Setting the Emissivity of an Imaging Bolometer in the Surface Temperature Profile Measurement of SiC-Based MEMS Heaters
RF Wolfenbuttel (TU Delft - Electronic Instrumentation)
David Bilby (Ford Motor Company)
Jaco H. Visser (Ford Motor Company)
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Abstract
The proper usage of a bandwidth-limited imaging bolometer for the measurement of the lateral temperature profile of microstructures in Silicon-Carbide (SiC) is analyzed. The SiC spectral emissivity, (Formula presented.), has a dip at (Formula presented.) (Formula presented.) m, which is in the band of a typical commercially available instrument and complicates the selection of the value of the equivalent emissivity, (Formula presented.), in the instrument settings. The impact is analyzed by deduction using simulation, and by experimental validation. Membranes of 3C-SiC of 1000 (Formula presented.) m diameter and 3 (Formula presented.) m thickness have been fabricated on Si wafers, with integrated poly-SiC resistors for both membrane heating and on-membrane temperature measurement for calibration purposes. The optimum setting was found as (Formula presented.) = 0.705 ± 0.025 by deduction and as (Formula presented.) = 0.66 ± 0.06 by experimental validation in the temperature range 120 °C to 400 °C. The apparent temperature coefficient of emissivity, (Formula presented.) 2 × 10
−4 °C
−1 is due to the shift of the Wien peak wavelength relative to the instrument’s sensitivity band.