VERY PRECISE SECTIONING METHOD FOR MEASURING CONCENTRATION PROFILES IN ANODIC TANTALUM OXIDE

This paper describes a sectioning technique for anodic tantalum oxide, based on slow dissolution of the oxide in HF almost saturated with NH//4F. Layers as thin as 5 Angstrom have been repeatedly and reproducibly removed, and the standard error in the total thickness removed is effectively about 3 Angstrom for the purpose of profile measurements. Furthermore, the layers are removed with extreme uniformity. In effect, therefore, anodic oxide films on tantalum can be sectioned almost atom layer by atom layer.