GENERATION LIFETIME MONITORING ON HIGH-RESISTIVITY SILICON USING GATED DIODES

A stringent requirement for the high performance of electronic circuits is a low diode leakage current. This so-called dark current can be accurately described by means of two parameters, τg, the bulk generation lifetime, and s, the surface generation velocity. In this paper it is shown that on high resistivity silicon, these two parameters cannot be derived as accurately or defined as uniquely from the classical MOS C-t measurements (Zerbst-technique), as is the case for standard doped silicon. The main reason for this is the fact that the boundary conditions for the measurement structure are no longer well defined. This causes physical parameters, which are normally neglected, to become important. Gated diodes on the other hand, when carefully designed, form a very well controlled structure. They allow the monitoring of the surface and the bulk defect density and defect energy level. Their behaviour can also be studied as a function of the processing sequence carried out, or the radiation dose the device was exposed to. Therefore gated diode structures are a major instrument to monitor the quality of silicon radiation detectors and to optimize their fabrication process. A for high resistivity silicon optimized device structure is proposed and its performance is illustrated with experimental results. © 1990.