In-process control of interface properties in the diode array camera tube target

Abstract

The studies discussed in this paper are concerned with the problem of adjustment of the final SiSiO 2 interface and surface properties in the Picturephone® diode array camera tube target. The effects of variations in certain processing parameters during target fabrication on the interface properties of blank oxide test slices and diode array targets, both immediately after a given process and in completed targets, are reported. It is found that certain process variations, for instance, the introduction of an inert gas anneal after dry oxidation, have no effect on final target properties although they give rise to adjustments in interface properties in test slices which are measured immediately after the particular process. Thus attempts to adjust final target properties by studies of the processes taken individually may be misleading. However, some simple variations in the heat treatments can lead to results which persist through additional high temperature processes to yield variations in the final target properties. For instance, a 5 min O 2 anneal immediately preceding the phosphorus diffusion step in the fabrication process leads to a significant increase in SiSiO 2 interface fixed charge, Q 88/ q, (from 2 × 10 11/ cm 2 to 6 × 10 11/ cm 2) in the final target. The effect of this anneal persists through two intermediate heat treating steps to appear in the completed device.