| 摘要 |
A process for fabricating a semiconductor device having reduced capacitance for high frequency circuit protection is disclosed that comprises first forming an n+ buried layer in a p-type substrate by depositing n-type dopant on the top surface of the substrate and then drive in or by implanting n-type material into the substrate, and then growing an n-type epitaxial layer atop the n+ buried layer as the device layer. Trenches that surrounds the device region with depth extending from the top surface, going through the n+ buried layer and reaching down to the substrate are then formed and then an n+ layer on the sidewalls of the trenches is formed by diffusion or ion implantation. The trenches are then filled by growing a layer of thermal oxide on the sidewalls of the trenches and followed by deposition of plasma enhanced oxide, nitride, TEOS oxide CVD oxide, or polysilicon into the trenches and then planarizing the top surface by plasma etch back or polishing. Then n+ region of the device is formed by forming an oxide layer on the top surface of the device layer and then etching the oxide by photolithography, then depositing n-type dopant material and then driving in by high temperature diffusion. Finally p+ region of the device is formed by etching the oxide using photolithography, then depositing p-type dopant material by solid or gas phase deposition or ion implantation and then driving in by high temperature diffusion so that the breakdown voltage between cathode and anode of the device is set to a targeted voltage for high frequency circuit protection.
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