Poly finger fabrication for HCI degradation improvement of ultra-low-Ron EDNMOS

A method comprising:

• forming a polysilicon layer upon a gate oxide (GOX) layer over a substrate;
• forming a first gate and plurality of fingers and a second gate and plurality of fingers laterally separated through the polysilicon layer down the GOX layer by:
• forming a photoresist layer over the polysilicon layer;
• patterning a first, second, and third pair of openings in the photoresist layer, the pairs and the openings being laterally separated and wherein each of the first pair of openings is over the first and second p-well, respectively, and the second pair of openings is over the n-sub;
• patterning a single opening between and laterally separated from each opening of the third pair;
• etching the polysilicon layer through the pairs and the single opening down to the GOX layer;
• and
• stripping the photoresist layer;
• forming an oxide layer over the GOX layer and along sidewalls of the first and second gates and plurality of fingers;
• forming a nitride layer over the oxide layer;
• removing portions of the nitride and oxide layers down to the polysilicon and GOX layers to form a nitride spacer over and adjacent to a portion of the oxide layer on opposite sides of each gate and plurality of fingers;
• and
• forming source/drain (S/D) regions laterally separated in the substrate, each S/D region adjacent to a nitride spacer,
• wherein the substrate comprises an N-type substrate (n-sub) having a first and a second P-type well (p-well) laterally separated.