TVS structures for high surge and low capacitance
AssigneeAlpha and Omega Semiconductor Incorporated
InventorsMadhur Bobde, Wenjiang Zeng, Limin Weng
Life of this patent
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Abstract
A transient voltage suppressing (TVS) device formed in an epitaxial layer of a first conductivity type supported on a semiconductor substrate. The TVS device further comprises a plurality of contact trenches opened and extended to a lower part of the epitaxial layer filled with a doped polysilicon layer of a second conductivity type wherein the trenches are further surrounded by a heavy dopant region of the second conductivity type. The TVS device further includes a metal contact layer disposed on a top surface of the epitaxial layer electrically connected to a Vcc electrode wherein the metal contact layer further directly contacting the doped polysilicon layer and the heavy dopant region of the second conductivity type.
Claims19
A method for manufacturing a transient voltage suppressing (TVS) device comprising:
- growing an epitaxial layer of a first conductivity type on a semiconductor substrate of the first conductivity type and opening a plurality of contact trenches in the epitaxial layer followed by implanting a dopant region of a second conductivity type below the contact trenches in the epitaxial layer;
- and
- filling the contact trenches with a doped conductive layer of the second conductivity type followed by applying a mask to form dopant regions of the second conductivity type near the top surface of the epitaxial layer followed by applying an elevated temperature to diffuse the dopant regions of the second conductivity type below each of the contact trenches to diffuse and surround the contact trenches in the epitaxial layer whereby the dopant regions of the second conductivity type form a P-N junction with the epitaxial layer of the first conductivity type.
A method for manufacturing a transient voltage suppressing (TVS) device comprising:
- growing a lower epitaxial layer having a first conductivity type on a semiconductor substrate of the first conductivity type and applying an implant mask to implant a buried dopant layer of the first conductivity type then growing a top epitaxial layer of the first conductivity type on top of the lower epitaxial layer followed by blanket implanting a top compensation layer of a second conductivity type near a top surface of the top epitaxial layer and opening a plurality of contact trenches in the upper epitaxial layer then implanting a trench-bottom dopant region of the second conductivity type below each of the contact trenches in the top epitaxial layer;
- carrying out a deposition process to form a conductive trench-filling layer to fill in the contact trenches followed by the etching back the conductive trench-filling layer to the top compensation layer followed by applying a mask to implant dopant regions near the top surface of the top compensation layer followed by carrying out a diffusion process to diffuse the trench-bottom dopant region to surround the contact trenches and to merge with the buried dopant layer;
- and
- applying a trench mask to open a plurality of isolation trenches followed by filling the isolation trenches with an insulation material.
Dependencies are inferred from the claim text.