Semiconductor device

1. A semiconductor device comprising:

a substrate;

a first semiconductor layer provided above the substrate, the first semiconductor layer including a first region;

a second semiconductor layer provided away from the first semiconductor layer in a first direction, the second semiconductor layer including a second region;

a third region provided between the first region and the second region;

an electrode provided above the third region;

a fourth region provided between the first region and the third region, the fourth region including carbon;

a fifth region provided between the second region and the third region, the fifth region including carbon;

a sixth region including boron and provided between the third region and the fourth region;

a seventh region including phosphorus and provided between the third region and the fourth region; and

an insulating film provided on a side surface of the electrode;

wherein

a carbon concentration in the first region and a carbon concentration in the second region are lower than a carbon concentration in the fourth region and a carbon concentration in the fifth region, and

at least one of the first semiconductor layer or the second semiconductor layer is provided with a part that is in contact with a side surface in the first direction of the insulating film.

2. The semiconductor device according to claim 1 , wherein the fourth and fifth regions include silicon carbon.

3. The semiconductor device according to claim 1 , wherein a carbon content in the fourth region and a carbon content in the fifth region are higher than 0% and lower than 5%.

4. The semiconductor device according to claim 1 , wherein

the first and second regions include boron; and

a boron concentration in the third region is lower than a boron concentration in the first region and a boron concentration in the second region.

5. The semiconductor device according to claim 1 , further comprising:

a first contact connected to the first region; and

a second contact connected to the second region;

wherein

the first and second contacts include metal.

6. The semiconductor device according to claim 1 , further comprising:

an insulating layer provided above the first and second regions;

an eighth region provided between the first region and the insulating layer, the eighth region including carbon; and

a ninth region provided between the second region and the insulating layer, the ninth region including carbon.

7. The semiconductor device according to claim 6 , wherein the sixth and seventh regions include silicon carbon.

8. The semiconductor device according to claim 6 , wherein a carbon content in the sixth region and a carbon content in the seventh region are higher than 0% and lower than 5%.

9. The semiconductor device according to claim 6 , wherein a boron concentration in the insulating layer is lower than a boron concentration in the first region and a boron concentration in the second region.

10. The semiconductor device according to claim 6 , further comprising insulating films provided on side surfaces of the electrode in the first direction;

wherein

one end of the eighth region and one end of the ninth region are in contact with each of the insulating films.

11. A semiconductor device comprising:

a first semiconductor layer;

a second semiconductor layer provided away from the first semiconductor layer in a first direction;

a third semiconductor layer provided between the first semiconductor layer and the second semiconductor layer;

an electrode provided above the third semiconductor layer;

a fourth semiconductor layer provided between the first semiconductor layer and the third semiconductor layer, the fourth semiconductor layer including carbon;

a fifth semiconductor layer provided between the second semiconductor layer and the third semiconductor layer, the fifth semiconductor layer including carbon; and

an insulating film provided on a side surface of the electrode; wherein

the third semiconductor layer includes:

a first region;

a second region including boron and provided between the first region and the fourth semiconductor layer; and

a third region including phosphorus and provided between the first region and the fourth semiconductor layer,

a carbon concentration in the first semiconductor layer and a carbon concentration in the second semiconductor layer are lower than a carbon concentration in the fourth semiconductor layer and a carbon concentration in the fifth semiconductor layer, and

at least one of the first semiconductor layer or the second semiconductor layer is provided with a part that is in contact with a side surface in the first direction of the insulating film.

12. The semiconductor device according to claim 11 , wherein

the third semiconductor layer is a part of a substrate;

the fourth semiconductor layer is provided along a first surface of the substrate facing the first semiconductor layer; and

the fifth semiconductor layer is provided along a second surface of the substrate facing the second semiconductor layer.

13. The semiconductor device according to claim 11 , further comprising:

a sixth semiconductor layer covering an upper surface of the first semiconductor layer; and

a seventh semiconductor layer covering an upper surface of the second semiconductor layer; wherein

at least a part of each of upper surfaces of the sixth and seventh semiconductor layers is located above an upper surface of the third semiconductor layer.

14. The semiconductor device according to claim 11 , wherein at least one of the first semiconductor layer or the second semiconductor layer is provided with a projecting portion projecting toward the third semiconductor layer in the first direction.

15. The semiconductor device according to claim 1 , wherein the seventh region is provided between the sixth region and the third region.

16. The semiconductor device according to claim 1 , wherein the boron concentration in the sixth region is lower than a boron concentration in the first region.

17. The semiconductor device according to claim 1 , wherein the fourth region provided between the first region and the sixth region, and the fourth region provided between the first region and the seventh region.