OPTIMIZED DIODE ANALYSIS OF ELECTRICAL SILICON SUBSTRATE PROPERTIES

In this paper the reverse current characteristics of Si p-n junction d iodes are analyzed in detail, in order to obtain an improved analysis of the underlying material parameters (generation and recombination li fetime, thermal activation energy). For that purpose, measurements on different geometry diodes are combined in order to separate peripheral from volume components. Using the correct depletion capacitance of th e p-n junction, one can separate the diffusion from the generation com ponent. From a study of the behavior with changing temperature, it is concluded that the peripheral generation component is due to surface g eneration by interface states. This is further supported by measuremen ts on gated diodes, which yield an extra feature that is speculated to be related to the surface generation along the isolation oxide edges. For the volume generation component, widely different activation ener gies have been found, depending on whether an internal gettering step was applied or not. A good agreement with deep-level parameters and tr ap profiles obtained by deep level transient spectroscopy has been fou nd. In the case of Czochralski material, there exists a clear correlat ion with the oxygen-precipitation related extended defects. Finally, i t is reported that the electric field dependence of the generation cur rent component is stronger than expected from the Poole-Frenkel effect only with an activation energy Towering which is much greater. Trap-a ssisted tunneling is a possible explanation.