Trench-type power device and manufacturing method thereof

1 . A trench-type power device, comprising:

a semiconductor substrate;

a drift region on the semiconductor substrate;

a first trench and a second trench located in the drift region;

a gate stack located in the first trench; and

Schottky metal located on a side wall of the second trench,

wherein the Schottky metal and the drift region form a Schottky barrier diode,

wherein the trench-type power device further comprises:

a conductive channel, which is formed by filling a conductive material in the second trench and is positionally separated from the drift region by the Schottky metal, which is different from the conductive material;

a doped region located below a bottom of the second trench, wherein a dopant type of the doped region is opposite to that of the drift region; and

a second contact layer located on a bottom surface of the second trench.

2 . The trench-type power device according to claim 1 , further comprising:

a well region located in the drift region; and

a source region located in the well region,

wherein the first trench and the second trench respectively penetrate through the source region and the well region and extend to a predetermined depth in the drift region.

3 . The trench-type power device according to claim 2 , wherein a dopant type of the semiconductor substrate, the drift region and the source region is N-type, a dopant type of the well region is P-type, and the semiconductor substrate serves as a drain region of a power transistor.

4 . The trench-type power device according to claim 2 , wherein the Schottky metal is located at a lower part of the side wall of the second trench and is in contact with the drift region, and a top end of the Schottky metal is located between the source region and the drift region.

5 . The trench-type power device according to claim 4 , further comprising:

a first contact layer located at an upper part of the side wall of the second trench and being in contact with the source region.

6 . The trench-type power device according to claim 5 , wherein the first contact layer and the second contact layer are made of metal silicide.

7 . The trench-type power device according to claim 2 , wherein:

an electrical connection path between the source region and the Schottky metal is provided via the conductive channel.

8 . The trench-type power device according to claim 1 , wherein the conductive material has a conductivity higher than that of the Schottky metal.

9 . A manufacturing method of a trench-type power device, comprising:

forming a drift region on a semiconductor substrate;

forming a first trench and a second trench in the drift region;

forming a gate stack in the first trench;

forming Schottky metal on a side wall of the second trench;

forming a doped region located below a bottom of the second trench, wherein a dopant type of the doped region is opposite to that of the drift region;

forming a second contact layer located on a bottom surface of the second trench; and

filling a conductive material in the second trench to form a conductive channel,

wherein the Schottky metal and the drift region form a Schottky barrier diode,

wherein the conductive channel is positionally separated from the drift region by the Schottky metal, which is different from the conductive material.

10 . The manufacturing method according to claim 9 , further comprising:

forming a well region in the drift region; and

forming a source region in the well region,

wherein the first trench and the second trench respectively penetrate through the source region and the well region and extend to a predetermined depth in the drift region.

11 . The manufacturing method according to claim 10 , wherein a dopant type of the semiconductor substrate, the drift region and the source region is N-type, a dopant type of the well region is P-type, and the semiconductor substrate serves as a drain region of a power transistor.

12 . The manufacturing method according to claim 10 , wherein the step of forming the Schottky metal comprises:

forming a conformal first metal layer in the second trench; and

removing a portion, which is located at an upper part of the side wall of the second trench, of the first metal layer, and a portion, which is located at a bottom of the second trench, of the first metal layer, by performing anisotropic etching,

wherein a portion, which remains at a lower part of the side wall of the second trench, of the first metal layer forms the Schottky metal.

13 . The manufacturing method according to claim 12 , wherein in the step of forming the Schottky metal, a top end of the Schottky metal is located between the source region and the drift region by controlling etching time of the anisotropic etching.

14 . The manufacturing method according to claim 12 , wherein after the step of forming the Schottky metal, the manufacturing method further comprises:

forming a conformal second metal layer in the second trench;

generating silicide by reaction of a portion of the second metal layer, by performing a silicidation process; and

removing unreacted metal of the second metal layer relative to the Schottky metal and the silicide, by performing a selective etching process,

wherein a portion, which is located at the upper part of the side wall of the second trench, of the silicide, forms a first contact layer, and a portion, which is located at the bottom of the side wall of the second trench, of the silicide forms a second contact layer.

15 . The manufacturing method according to claim 12 , wherein an electrical connection path between the source region and the Schottky metal is provided by the conductive channel.

16 . The manufacturing method according to claim 10 , further comprising:

forming a P-type doped region below the bottom of the second trench by performing ion implantation via the second trench.

17 . The manufacturing method according to claim 9 , wherein the first contact layer and the second contact layer are made of metal silicide.