Optical tomography for dielectric profiling in processing electronic materials

Optical methods represent a powerful tool for contactless characterisation of materials in industrial processes. In particular, in the microelectronic field great impetus has been given to the on-line measurement of the doping profiles in large scale productions in order to increase the overall equipment effectiveness. In this framework, we propose a new technique based on optical tomography able to reconstruct the doping profiles in semiconductor wafers starting from reflected intensity measurements, taken at infrared wavelengths. Several numerical simulations have shown the effectiveness of the proposed approach. In particular, the reconstruction of typical shallow doping profiles, generated by a process simulator, has been performed with relatively high accuracy. (C)2000 Elsevier Science S.A. All rights reserved.