A simple etch contour for near ideal breakdown voltage in plane and planar p-n junctions

It is shown that high avalanche breakdown voltage in both plane and planar p-n junctions can be achieved by extending the heavily doped side of the junction beyond the contact and partially etching into it. The technique, when properly applied, is capable of giving virtually ideal breakdown voltages for both plane and planar type p-n junctions and uses only a fraction of the area required for a typical negative bevel. The actual breakdown voltage depends on how carefully the etch is controlled. For planar junctions the breakdown voltages that can now be achieved are better than any previously reported. Moreover, since the technique is based on etching, mechanical contouring is avoided. This. in itself, is beneficial. The new method is illustrated both by exact calculations and by several experiments. Included in the calculations are a comparison of the new method to the 6° negative bevel for applications involving plane junctions and a comparison of the new method (for planar junctions) with the single floating field limiting ring approach.