| 摘要 |
A pattern is defined in a semiconductor wafer by forming one or more notches from a top major surface downwardly beyond the lowermost junction between opposite conductivity type regions, and by anodizing the wafer to provide a columnated porous region below and substantially confined to the lateral dimension of each notch. Anodization current flows substantially vertically, without significant lateral spreading. The porous regions are oxidized to afford well-defined vertically bordered insulative regions separating the lowermost junctions on opposite sides thereof.
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