Semiconductor device and method of manufacturing the same

1. A semiconductor device comprising:

a gate electrode formed over a semiconductor substrate of a first conductivity type with a first insulating film interposed therebetween;

a source region and a drain offset region of a second conductivity type formed away and facing each other over a surface of the semiconductor substrate with a channel region interposed therebetween, the channel region being formed immediately below the gate electrode;

a drain region of the second conductivity type formed to be included in the drain offset region; and

a punch through prevention region of the first conductivity type formed to be in contact with the drain offset region,

wherein, in a portion immediately below the gate electrode, peaks of concentration distribution in a depth direction of a first conductivity type impurity and a second conductivity type impurity in the drain offset region are in a same depth, the second conductivity type impurity being higher concentrated than the first conductivity type impurity.

2. The semiconductor device according to claim 1 , wherein the difference of the concentration peak value between the first conductivity type impurity and the second conductivity type impurity is not more than 10/cm 3 .

3. The semiconductor device according to claim 1 , further comprising a second insulating film formed on the surface of the drain offset region except immediately below the gate electrode, the second insulating film being thicker than the first insulating film,

wherein, in a portion immediately below the second insulating film, peaks of concentration distribution in a depth direction of the first conductivity type impurity and the second conductivity type impurity in the drain offset region are in a different depth, the second conductivity type impurity being higher concentrated than the first conductivity type impurity.

4. The semiconductor device according to claim 2 , further comprising a second insulating film formed on the surface of the drain offset region except immediately below the gate electrode, the second insulating film being thicker than the first insulating film,

wherein, in a portion immediately below the second insulating film, peaks of concentration distribution in a depth direction of the first conductivity type impurity and the second conductivity type impurity in the drain offset region are in a different depth, the second conductivity type impurity being higher concentrated than the first conductivity type impurity.

5. The semiconductor device according to claim 1 , wherein a distribution of a difference of the concentration peak value between the first conductivity type impurity and the second conductivity type impurity comprises substantially a convex shape.

6. The semiconductor device according to claim 5 , wherein the peak of the distribution of the difference of the concentration peak value between the first conductivity type impurity and the second conductivity type impurity is formed to substantially a same depth as the peaks of concentration distribution of the first conductivity type impurity and a second conductivity type impurity in the drain offset region below the gate electrode.

7. The semiconductor device according to claim 1 , further comprising a second insulating film formed on a surface of the drain offset region except below the gate electrode, the second insulating film being thicker than the first insulating film,

wherein, in a portion below the second insulating film, peaks of concentration distribution in a depth direction of the first conductivity type impurity and the second conductivity type impurity in the drain offset region are in a different depth.

8. The semiconductor device according to claim 1 , wherein a concentration distribution in the depth direction of a first conductivity type impurity comprises a shape substantially similar to a concentration distribution of second conductivity type impurity throughout the depth of the drain offset region.

9. The semiconductor device according to claim 1 , wherein a concentration distribution in the depth direction of a first conductivity type impurity is less than a concentration distribution of second conductivity type impurity throughout the depth of the drain offset region.

10. The semiconductor device according to claim 1 , wherein both a concentration distribution in the depth direction of a first conductivity type impurity and a concentration distribution of second conductivity type impurity throughout the depth of the drain offset region comprise a substantially convex shape.

11. The semiconductor device according to claim 2 , further comprising a second insulating film formed on a surface of the drain offset region except below the gate electrode,

wherein in a portion below the second insulating film, peaks of concentration distribution in the depth direction of the first conductivity type impurity and the second conductivity type impurity in the drain offset region are in different depths.

12. A semiconductor device comprising:

a gate electrode formed over a semiconductor substrate of a first conductivity type with a first insulating film interposed therebetween;

a source region and a drain offset region of a second conductivity type formed away and facing each other over a surface of the semiconductor substrate with a channel region interposed therebetween, the channel region being formed below the gate electrode;

a drain region of the second conductivity type formed to be included in the drain offset region; and

a punch through prevention region of a first conductivity type formed to be in contact with the drain offset region,

wherein, in a portion of the drain offset region below the gate electrode, peaks of concentration distribution in a depth direction of a first conductivity type impurity and a second conductivity type impurity in the drain offset region are in substantially a same depth.

13. The semiconductor device according to claim 12 , wherein the second conductivity type impurity is being higher concentrated than the first conductivity type impurity.

14. The semiconductor device according to claim 12 , wherein the difference of the concentration peak value between the first conductivity type impurity and the second conductivity type impurity is not more than 10/cm 3 .

15. The semiconductor device according to claim 12 , further comprising a second insulating film formed on a surface of the drain offset region except immediately below the gate electrode, the second insulating film being thicker than the first insulating film.

16. The semiconductor device according to claim 15 , wherein, in a portion below the second insulating film, peaks of concentration distribution in the depth direction of the first conductivity type impurity and the second conductivity type impurity in the drain offset region are in different depth, the second conductivity type impurity being higher concentrated than the first conductivity type impurity.