Electrical and structural characterization of inhomogeneously doped semiconductors by infrared spectroscopy

Abstract

An optical method is presented for thenon-destructive electrical and structural characterisation of multilayer structures. The presented concept yields the complex refractive index profiles within an arbitrary composed layer system by using the symmetrical transmission and the asymmetrical reflectivity caused by the optical inhomogeneity of a material. This method includes the superimposition of coherent multiple reflections within the refractive index profile as well as incoherent multiple reflections within the whole wafer. This analysis yields the spacial distribution of free carrier density profiles within the sample as well as the transitions between different crystal phases by using the least squares fit procedures. The results of the optical analysis are compared with other methods used to quantitatively determine density profiles and phase transitions such as SIMS, spreading resistance, stripping Hall and RBS.