US Patent 7098509 High energy ESD structure and method

In one embodiment, a concentric ring ESD structure includes a first p-type region and a second p-type region are formed in a layer of semiconductor material. The two p-type regions are coupled together with a floating n-type buried layer. The first and second p-type regions form a back-to-back diode structure with the floating n-type buried layer. A pair of shorted n-type and p-type contact regions is formed in each of the first and second regions. An isolation region is formed between the first and second p-type regions.