SIMS, DLTS and generation lifetime measurements on SIMOX materials containing metal impurities

Summary form only given. Secondary ion mass spectroscopy (SIMS), current deep level transient spectroscopy (DLTS) and the gated-diode technique were used to study metal impurities in separation by implantation of oxygen (SIMOX) devices. Detectable amounts of impurities were found to be introduced during the high-dose oxygen implantation with a dominant impurity of iron. Their redistribution during the high-temperature annealing and the low-temperature processing, and their effects on device performance, are discussed. Metal impurities dissolved in interstitial sites have relatively low solid solubilities but high mobilities at device processing temperatures so that their concentrations in finished devices are very low. Although atomic metals are electrically active, they are relatively insignificant to device performance for this reason. Soft breakdown in the drain/body junction which was sensitive to the back-gate bias was observed, indicating that precipitates located at the back interface were responsible for the soft breakdown