Semiconductor device with controllable channel length and manufacturing method thereof

1. A semiconductor device, comprising:

a source region and a drain region respectively disposed in a substrate;

a closed-loop gate electrode having an opening area on the substrate and enclosing the source region formed in the opening area;

a P-type deep well region disposed under the opening area;

a drift region disposed adjacent to the drain region formed in an N-type well region;

an N-type deep well region spaced apart from the P-type deep well region and overlapping the drift region and the N-type well region; and

a P-type well region surrounding the source region and disposed to abut the drift region;

wherein the P-type deep well region and the N-type deep well region are deeply formed such that a lower surface of each deep well region contacts an N-type buried layer,

wherein the closed-loop gate electrode comprises:

a first corner and a second corner;

a first straight section between the first corner and the second corner;

a third corner and a fourth corner, each corner of the closed-loop gate electrode having a first radius of curvature;

a second straight section between the third corner and the fourth corner, the first and second straight sections being parallel to each other; and

a vertical axis passing simultaneously through the first and second straight sections and not overlapping the opening area, and

wherein a channel length of the semiconductor device is extendable to a desired length about the vertical axis.

2. The semiconductor device of claim 1 , further comprising:

a first insulating isolation region disposed on the drift region to partially overlap the closed-loop gate electrode; and

a second insulating isolation region enclosing a bulk tap region disposed in the P-type well region,

wherein the second insulating isolation region is configured to partially enclose the source region.

3. The semiconductor device of claim 1 , wherein the P-type deep well region, the P-type well region, and the closed-loop gate electrode overlap each other.

4. The semiconductor device of claim 2 , further comprising:

a deep trench isolation region disposed adjacent to the drain region; and

a buried oxide film disposed on the substrate,

wherein the N-type buried layer is disposed on the buried oxide film, and

wherein the deep trench isolation region is deeper than the first insulating isolation region and is disposed to be in contact with an upper surface of the buried oxide film.

5. A semiconductor device, comprising:

a source region and a drain region respectively disposed in a substrate;

a gate insulating layer formed on the substrate;

a closed-loop gate electrode formed on the gate insulating layer and having an opening area on the substrate, the closed-loop gate electrode enclosing the source region formed in the opening area;

a drift region adjacent to the drain region formed in an N-type well region;

a P-type well region overlapping the closed-loop gate electrode and disposed to abut the drift region;

a P-type deep well region disposed under the opening area;

an N-type deep well region spaced apart from the P-type deep well region and overlapping the drift region and the N-type well region;

wherein the P-type deep well region and the N-type deep well region are deeply formed such that a lower surface of each deep well region contacts an N-type buried layer,

wherein the closed-loop gate electrode comprises:

first to fourth corners, each corner having a round shape;

a first straight section between the first corner and the second corner;

a second straight section between the third corner and the fourth corner, the first and second straight sections being parallel to each other; and

a vertical axis passing simultaneously through the first and second straight sections and not overlapping the opening area, and

wherein a channel length of the semiconductor device is extendable to a desired length about the vertical axis.

6. The semiconductor device of claim 5 , further comprising:

a buried oxide film on the substrate;

a first insulating isolation region disposed on the drift region and overlapping the closed-loop gate electrode;

a second insulating isolation region completely surrounding a bulk tap region; and

a deep trench isolation region disposed near the drain region,

wherein the N-type buried layer is disposed on the buried oxide film.

7. The semiconductor device of claim 6 , wherein the second insulating isolation region is shaped to partially enclose the source region.

8. The semiconductor device of claim 6 , wherein the deep trench isolation region is deeper than the first insulating isolation region and is disposed in contact with the buried oxide film.

9. A semiconductor device, comprising:

a source region and a drain region respectively disposed in a substrate;

a closed-loop gate electrode having an opening area on the substrate and enclosing the source region formed in the opening area;

a P-type well region overlapping the closed-loop gate electrode and enclosing the source region;

an N-type well region disposed under the drain region and spaced apart from the P-type well region;

a P-type deep well region disposed under the opening area; and

an N-type deep well region spaced apart from the P-type deep well region and overlapping the N-type well region,

wherein the P-type deep well region and the N-type deep well region are deeply formed such that a lower surface of each deep well region contacts an N-type buried layer,

wherein the closed-loop gate electrode comprises:

first to fourth corners, each corner having a first radius of curvature;

a first straight section between the first corner and the second corner;

a second straight section between the third corner and the fourth corner, the first and second straight sections being parallel to each other; and

a vertical axis passing simultaneously through the first and second straight sections and not overlapping the opening area, and

wherein a channel length of the semiconductor device is extendable to a desired length about the vertical axis.

10. The semiconductor device of claim 9 , further comprising:

a drift region disposed to abut the P-type well region;

a first insulating isolation region disposed on the drift region to partially overlap the closed-loop gate electrode;

a second insulating isolation region enclosing a bulk tap region disposed in the P-type well region; and

a deep trench isolation region disposed adjacent to the drain region,

wherein the second insulating isolation region is configured to partially enclose the source region.

11. The semiconductor device of claim 10 , wherein the P-type well region, the P-type deep well region, and the gate electrode overlap each other.

12. The semiconductor device of claim 10 , further comprising:

a deep trench isolation region disposed adjacent to the drain region; and

a buried oxide film disposed on a lower surface of the N-type buried layer,

wherein the deep trench isolation region is deeper than the first insulating isolation region and is disposed to be in contact with an upper surface of the buried oxide film.

13. The semiconductor device of claim 10 , wherein the second insulating isolation region has a shape of a Roman character II in a top view, such that the second insulating isolation region has a closed-loop to isolate the bulk tap region from the source region and the bulk tap region is disposed inside the closed-loop.

14. The semiconductor device of claim 10 , wherein the N-type deep well region comprises a first N-type deep well region and a second N-type deep well region spaced apart from each other,

wherein the deep trench isolation region comprises a first deep trench isolation region and a second deep trench isolation region spaced apart from each other, and

wherein the first N-type deep well region abuts the first deep trench isolation region, and the second N-type deep well region abuts the second deep trench isolation region.

15. The semiconductor device of claim 14 , wherein the first N-type deep well region has a depth smaller than that of the first deep trench isolation region, and

wherein the second N-type deep well region has a depth smaller than that of the second deep trench isolation region.