Novel noncontact thickness metrology for backend manufacturing of wide bandgap light emitting devices



Low coherence optical interferometry (D. Huang et al., Science 254, 1178 (1991) [1]) has been proven to be an effective tool for characterisation of thin and ultra-thin semiconductor Si wafers (W. J. Walecki et al., 3rd International Workshop on Thin Semiconductor Devices – Manufacturing and Applications, Munich, Germany, November 25, 2002; Q. Wang et al., phys. stat. sol. (a) 155, 289 (1996) [2]). Purpose of this paper is to present an extension of this method to characterisation of ultra-thin compound wide bandgap wafers mounted on insulating carriers. We present alternative technique, which does not suffer from above discussed limitations, and can be easily integrated in the production tools, and provide accurate measurement of samples while they are being processed. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)