Short channel trenched DMOS transistor
AssigneeSiliconix Incorporated
InventorsFwu-Iuan Hshieh, Mike F. Chang, Hamza Yilmaz
Life of this patent
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Abstract
A DMOS transistor having a trenched gate is formed in a substrate such that the P body region of the transistor may be formed heavier or deeper while still maintaining a "short" channel. This is accomplished by forming a portion of the N+ type source region within the P body region prior to forming the trench, followed by a second implantation and diffusion of a relatively shallow extension of the N+ source region formed overlying a part of the P body region. The increased depth or doping concentration of the P body region advantageously lowers the resistance of the P body region, while the short channel lowers the on-resistance of the transistor for improved performance.
Claims11
A trenched transistor comprising:
- a substrate of a first conductivity type defining a trench containing a conductive gate electrode;
- a body region of a second conductivity type extending from a principal surface of the substrate adjacent to the trench into the substrate to a depth less than that of the trench, wherein a portion of the body region immediately adjacent to the trench is shallower with respect to the principal surface than is another portion of the body region away from the trench, an edge of the body region immediately adjacent the trench sloping such that a portion of the edge immediately adjacent the trench is closer to the principal surface;
- and
- a source region of the first conductivity type formed in the substrate.
A trenched transistor comprising:
- a substrate of a first conductivity type defining a trench containing a conductive gate electrode;
- a body region of a second conductivity type extending from a principal surface of the substrate adjacent to the trench into the substrate to a depth less than that of the trench, wherein a portion of the body region immediately adjacent to the trench has an edged which is sloping such that a portion of the edge immediately adjacent the trench is shallower with respect to the principal surface than is another edge portion of the body region away from the trench;
- and
- a source region of the first conductivity type formed in the substrate, the source region extending from the principal surface adjacent to the trench into the substrate to a depth less than that of the body region, the source region being deeper immediately adjacent to the trench and shallower away from the trench with respect to the principal surface.
Dependencies are inferred from the claim text.