Interferometer, Moire, Temperature
Saturday, September 09, 2006
A Moire Interferometer has been designed and developed to measure the temperature of a wafer. The technique relies on diffraction from a grating embossed on the wafer. The wafer temperature increases caused the expansion of the embossed grating, modifying the diffraction angle of the embossed grating.
Two laser light beams are symmetrically incident on the wafer’s embossed grating at known angles. The period, wavelength, and incident angles are properly arranged (the first order diffraction is close to normal to the wafer surface), so that the angle between the two output light beams varies with temperature. The use of symmetrically incident light beams allows for a differential technique for minimizing effects of wafer tilt and wafer warping during temperature measurement.
Source: “Non contact 1 *C resolution temperature measurement by projection Morire interferometery” J.Vac. Sci..Technol., B10, 166-169, 1992;
S. R. J. Brueck, S. H. Zaidi, M. K. Lang, and C. Huang, Center for High Technology Materials, University of New Mexico, NM
Reference: None Available
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posted by JD52 @ 5:59 PM,
