Recombination mechanisms in crystalline silicon: Bulk and surface contributions

Abstract

In the present paper the most interesting results of a work on the influence of some processes used in the fabrication of microstructures on the bulk and surface electrical activity of the Si substrate are reported. In these studies the minority carrier lifetime and the surface recombination velocity were used as sensors of the Si electrical activity changes. Other electrical (DLTS, C-V and I-V characteristics, EBIC) and structural (X-ray double crystal diffractometry, IR spectroscopy) techniques were used to gather information about the nature and concentration of the defects induced by processing. Two processes have been investigated: Rapid Thermal Annealing treatments (RTA), and Reactive Ion Etching (RIE): neither of them have a large influence on the minority carrier diffusion length when the substrate is an high quality Si wafer of the last production. On the contrary, the surface recombination velocity is largely influenced by both processes. The rearrangement of the surface structure and the formation and growth of hillocks is proposed as the more important mechanism responsible of the observed changes in the surface electrical activity.