US 2023/0411511 A1Published application

Power semiconductor device with dual shield structure in silicon carbide and manufacturing method thereof

AssigneeTrinno Technology Co., Ltd.

InventorsKwang Hoon OH, Soo Seong KIM, Chongman YUN

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Abstract

Power semiconductor device with dual shield structure in silicon carbide and manufacturing method thereof disclosed. A silicon carbide power semiconductor device includes a substrate of a first conductivity type made of silicon carbide, a drift layer of the first conductivity type formed on an upper surface of the substrate with a relatively low impurity concentration compared to that of the substrate, a body region of a second conductivity type formed in an upper region of the drift layer, a different-widths gate trench, being etched to extend into the drift layer deeper than the body region, wherein an upper region of the different-widths gate trench is formed to be a wide-width region with a relatively wider width and a lower region of the different-widths gate trench is formed to be a narrow-width region with a relatively narrower width, wherein the wide-width region and the narrow-width region share a vertical center line so that the different-widths gate trench is formed in a boundary shape bent to have a stepped edge, a different-widths poly gate electrode filled in the different-widths gate trench so as to be insulated by a different-widths gate oxide and formed in a shape corresponding to the shape of the different-widths gate trench and a source region of the first conductivity type formed in an upper region of the body region in contact with sidewalls of the different-widths gate trench.

Claims9

Dependent claims

A silicon carbide power semiconductor device, comprising:

a substrate of a first conductivity type made of silicon carbide;
a drift layer of the first conductivity type formed on an upper surface of the substrate with a relatively low impurity concentration compared to that of the substrate;
a body region of a second conductivity type formed in an upper region of the drift layer;
a different-widths gate trench, being etched to extend into the drift layer deeper than the body region, wherein an upper region of the different-widths gate trench is formed to be a wide-width region with a relatively wider width and a lower region of the different-widths gate trench is formed to be a narrow-width region with a relatively narrower width, wherein the wide-width region and the narrow-width region share a vertical center line so that the different-widths gate trench is formed in a boundary shape bent to have a stepped edge;
a different-widths poly gate electrode filled in the different-widths gate trench so as to be insulated by a different-widths gate oxide and formed in a shape corresponding to the shape of the different-widths gate trench;
and
a source region of the first conductivity type formed in an upper region of the body region in contact with sidewalls of the different-widths gate trench,
wherein the different-widths gate oxide formed on the bottom of the narrow region of the different-widths gate trench is formed to be twice or more thicker than a thickness of the different-widths gate oxide formed on the sidewall of the wide-width region,
wherein a shield region of the second conductivity type is formed at both corner regions of the different-widths gate trench where the bottom of the wide-width region and sidewalls of the narrow-width region cross.

6 more elements

A method of fabricating a silicon carbide power semiconductor device, comprising:

forming, on an upper surface of a silicon carbide substrate of a first conductivity type, a drift layer of the first conductivity type with an impurity concentration relatively lower than that of the substrate;
forming a source region of the first conductivity type in an upper region of the drift layer;
etching a narrow-width trench to form a narrow-width region having a predetermined width w1 through the source region to a predetermined depth d1 reaching the drift layer;
forming a lower oxide region having a thickness corresponding to a difference between the depth d1 and a depth d2 in the narrow-width region of the narrow-width trench;
forming an extension region of a second conductivity type extending in a lateral direction at a predetermined depth d3 and further extending along a sidewall of the narrow-width trench with a predetermined width w2 to the depth d2 of an upper surface of the lower oxide region on both sides of the narrow-width trench by vertically implanting ions of the second conductivity type on a top of the drift layer except for the narrow-width trench and obliquely implanting ions of the second conductivity type into the narrow-width trench through the sidewall of the narrow-width trench;
and
forming a different-widths gate trench having a wide-width region and the narrow-width region by etching a wide-width trench that shares a vertical center line with the narrow-width trench and forms the wide-width region with a predetermined width w3 for removing the extension region extending along the sidewall of the narrow-width trench to a depth d4, thereby separating the extension region into a body region in contact with the sidewall of the wide-width trench and a shield region in contact with a bottom of the wide-width trench and sidewall of the narrow-width trench,
wherein depths d1, d2, d3 and d4 have a relationship of d1>d2>d4>d3.

5 more elements

Dependencies are inferred from the claim text.