Patent ID: 6992353

Claim:
A self-aligned source structure, comprising: a semiconductor substrate, wherein the semiconductor substrate comprises a lightly-doped epitaxial silicon layer of a first conductivity type being formed on a heavily-doped silicon substrate of the first conductivity type; a body diffusion region of a second conductivity type being formed in a surface portion of the lightly-doped epitaxial silicon layer through a patterned window surrounded by a patterned oxide layer on a patterned polycrystalline-silicon gate layer, wherein the patterned polycrystalline-silicon gate layer is formed on a gate oxide layer; a heavily-doped diffusion region of the second conductivity type being formed in a surface portion of the body diffusion region through a first self-aligned implantation window surrounded by a first sidewall dielectric spacer, wherein the first sidewall dielectric spacer is formed over a sidewall of a silicon nitride layer and on a side portion of the silicon nitride layer in the patterned window; a heavily-doped source diffusion ring of the first conductivity type being formed in a surface portion of the body diffusion region and on an extended portion of the heavily-doped diffusion region through a second self-aligned implantation window formed between the sidewall of the silicon nitride layer and a masking layer on the silicon nitride layer surrounded by the first sidewall dielectric spacer; and a self-aligned contact window being formed by the heavily-doped source diffusion ring surrounded by a second sidewall dielectric spacer and the heavily-doped diffusion region surrounded by the heavily-doped source diffusion ring.