Optical on wafer measurement of Ge content of virtual SiGe-substrates

We developed a procedure for a fast and non-destructive determination of th e Ge-content in virtual Si1-xGex-substratesin the range from x = 0.2-1. The virtual substrates were grown in our MBE-system. The reflectivity of SiGe substrates depends on the Ce content x and on the crosshatch surface corrug ations. The extremes in relative reflectance values are rather insensitive to surface corrugations contrary to the absolute values which depend signif icantly on the surface morphology. The reflectance of films was measured ex situ with a commercial measuring system (NanoSpec). This system measures r elatively to a measurement standard wafer (Silicon-wafer) over wavelength r ange from 370 to 800 nm. The reflection graphs have maxima in the range fro m 410 to 590 nm depending on the Ge-content. Results obtained by these meas urements with the NanoSpec measuring system were in a good agreement with S IMS-analysis and XRD data. (C) 1998 Elsevier Science S.A. All rights reserv ed.