Processing high-quality silicon for microstrip detectors

An investigation has been made into the behaviour of high-purity silicon (HP-Si) during the fabrication of microstrip detectors. The resistivity of the silicon used is 3 k-OMEGA cm. The investigation is centred on standard bipolar processes based on ion implantation. It is found that, comparing the processes used, the best diode characteristics are achieved when a heat treatment at 600-degrees-C is used after the ion-implantation step, whereas the worst results from an implantation and a 900-degrees-C heat treatment. Thus it is shown that if integration of the electronic circuitry and the detector on a single chip is required, then the high-temperature heat treatments must be done before the ion-implantation step needed for detector fabrication.