Method and apparatus for measuring thickness of epitaxial layer by infrared reflectance

摘要

PCT No. PCT/US82/00729 Sec. 371 Date Oct. 28, 1982 Sec. 102(e) Date Oct. 28, 1982 PCT Filed May 27, 1982.Method and apparatus measure the thickness of an epi layer grown on a substrate. IR energy 12 is directed onto the epi layer 13 and a portion 14 of the energy is reflected from the surface of the epi layer and from the interface of the epi layer and substrate. The spectral reflectance of the reflected energy is measured by means of a Fourier transform IR spectrometer 10. The measured values of spectral reflectance are correlated with a series of theoretical reflectance values determined for different thicknesses of an epi layer in a range including the nominal thickness. The measured or actual epi thickness is determined from the correlation analysis.