Infrared emittance measurements at NIST

A new capability for the measurement of the temperature-dependent emittance of specular samples in the near infrared spectral region has been developed in NIST´s infrared spectrophotometry laboratory to provide emittance measurements and standards for a broad range of applications including rapid thermal processing (RTP). Our approach employs the indirect measurement of reflectance and transmittance measurements to obtain emittance. A vacuum goniometer system controls the sample environment and measurement geometry. The main system, including the sample, is contained in a vacuum chamber that enables characterization of materials otherwise susceptible to oxidation. Details of the lasers, sources, detectors, and other optics in the system are given. The system has initially been used to characterize the spectral emittance (by reflectance) of a variety of semiconductor wafer samples including bare silicon and silicon substrates coated with SiO ₂, Si₃N₄, and polysilicon films. The spectral range for these measurements is from 600 nm to 1100 nm, where Si is opaque; the temperature range is ambient to 800degC. The results are analyzed and compared with those predicted by several models from the literature