A detailed study of the changes in buried oxide charge as a function of processing and irradiation

The use of the quick-turn (QT) method of forming a simple buried-oxide capacitor (BOXCAP) to characterize the effects of process variations on the properties of the oxide and silicon layers is discussed. In particular, the results of a matrix of various anneal conditions, and an analysis of the effects of using a screen oxide during the SIMOX implantation are presented. The results indicate that the generation lifetime continues to improve with anneal temperature and time, but the fixed charge in the oxide increases with longer anneal times. With regard to the screen oxide investigation, it was found that wafers implanted with a screen oxide had long generation times, but also had more fixed oxide charge. Buried-oxide capacitor (BOXCAP) C-V analysis provides very useful information regarding the radiation response of the buried oxide. This technique has been used to characterize the oxide charges generated as a function of processing and substrate bias.<
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