Self-aligned trench-type DMOS transistor structure and its manufacturing methods

摘要

The self-aligned trench-type DMOS transistor structure comprises a self-aligned source region being surrounded by a trench gate region. The self-aligned source region comprises a moderately-doped p-base diffusion region formed in a lightly-doped epitaxial semiconductor substrate, a self-aligned heavily-doped n⁺ source diffusion ring formed in a side surface portion of the moderately-doped p-base diffusion region, a heavily-doped p⁺ contact diffusion region formed in a surface portion of the moderately-doped p-base diffusion region surrounded by the heavily-doped n⁺ source diffusion ring, and a self-aligned source contact window formed by a semiconductor surface surrounded by a sidewall dielectric spacer. The trench gate region comprises a gate dielectric layer being lined over a trenched semiconductor surface with or without a thicker isolation dielectric layer formed on a bottom trenched semiconductor surface and a self-aligned highly conductive gate layer being formed at least over the gate dielectric layer.