Method of manufacturing semiconductor device

1. A method of producing a semiconductor device having a transistor equipped with a gate electrode, a source region, and a drain region, comprising the steps of:

(a) providing a semiconductor substrate having a main surface,

(b) forming a first conductivity type well in the semiconductor substrate,

(c) forming the gate electrode over the main surface of the semiconductor substrate,

(d) forming a first semiconductor region in the well region by ion implantation of a first impurity of a second conductivity type, which is a conductivity type opposite to the first conductivity type, from the outside of the gate electrode and from a direction tilted by 45° with respect to a direction perpendicular to the main surface of the semiconductor substrate,

(e) forming a first sidewall insulating film over a side wall of the gate electrode,

(f) forming a second semiconductor region in the well region by ion implantation of a second impurity of the second conductivity type from the outside of the gate electrode and the first sidewall insulating film and from a direction tilted by 45° with respect to a direction perpendicular to the main surface of the semiconductor substrate,

(g) forming a second sidewall insulating film over the first sidewall insulating film,

(h) forming a third semiconductor region in the well region by ion implantation of a third impurity of the second conductivity type from the outside of the gate electrode, the first sidewall insulating film, and the second sidewall insulating film and from a direction perpendicular to the main surface of the semiconductor substrate, and

(i) forming a silicide layer over the surface of the third semiconductor region,

wherein the first semiconductor region, the second semiconductor region, and the third semiconductor region forms the source region or the drain region,

wherein the impurity concentration of the first semiconductor region is lower than the impurity concentration of the second semiconductor region, and

wherein the ion implantation energy of the first impurity is greater than the ion implantation energy of the second impurity.

2. The method of manufacturing a semiconductor device according to claim 1 ,

wherein the first impurity and the second impurity are each phosphorus.

3. The method of manufacturing a semiconductor device according to claim 2 ,

wherein the third impurity is arsenic.

4. The method of manufacturing a semiconductor device according to claim 1 ,

wherein the impurity concentration of the third semiconductor region is higher than the impurity concentration of the second semiconductor region.

5. The method of manufacturing a semiconductor device according to claim 1 ,

wherein the ion implantation energy of the first impurity is greater than the ion implantation energy of the third impurity.

6. A method of manufacturing a semiconductor device having a first transistor equipped with a first gate electrode, a first source region, and a first drain region and a second transistor equipped with a second gate electrode, a second source region, and a second drain region, comprising the steps of:

(a) providing a semiconductor substrate having, in the main surface thereof, a first region for forming therein the first transistor and a second region for forming therein the second transistor;

(b) forming a first well region of a first conductivity type in the semiconductor substrate in the first region and forming a second well region of the first conductivity type in the semiconductor substrate in the second region;

(c) forming a first gate insulating film over the main surface of the semiconductor substrate in the first region and forming a second gate insulating film over the main surface of the semiconductor substrate in the second region;

(d) forming the first gate electrode over the first gate insulating film and forming the second gate electrode over the second gate insulating film;

(e) forming a first semiconductor region in the first well by ion implantation of a first impurity of a second conductivity type, which is a conductivity type opposite to the first conductivity type, from the outside of the first gate electrode and from a direction tilted by 45° with respect to a direction perpendicular to the main surface of the semiconductor substrate;

(f) forming a first sidewall insulating film over the side wall of each of the first gate electrode and the second gate electrode;

(g) forming a second semiconductor region in the second well region by ion implantation of a second impurity of the second conductivity type from the outside the second gate electrode and the first sidewall insulating film;

(h) forming a second sidewall insulating film over the first sidewall insulating film of each of the first gate electrode and the second gate electrode;

(i) forming a third semiconductor region in the first well region by ion implantation of a third impurity of the second conductivity type from the outside of the first gate electrode, the first sidewall insulating film, and the second sidewall insulating film and from a direction tilted by 45° with respect to a direction perpendicular to the main surface of the semiconductor substrate;

(j) forming a third sidewall insulating film over the second sidewall insulating film in the first region;

(k) forming a fourth semiconductor region in the first well region by ion implantation of a fourth impurity of the second conductivity type from the outside of the first gate electrode, the first sidewall insulating film, the second sidewall insulating film, and the third sidewall insulating film and from a direction perpendicular to the main surface of the semiconductor substrate; and

(l) forming a silicide layer over the surface of the fourth semiconductor region,

wherein the first semiconductor region, the third semiconductor region, and the fourth semiconductor region form the first source region or the first drain region,

wherein the second semiconductor region forms the second source region or the second drain region;

wherein the impurity concentration of the first semiconductor region is lower than the impurity concentration of the third semiconductor region, and

wherein the ion implantation energy of the first impurity is greater than the ion implantation energy of the third impurity.

7. The method of manufacturing a semiconductor device according to claim 6 ,

wherein the thickness of the first gate insulating film is greater than the thickness of the second gate insulating film.

8. The method of manufacturing a semiconductor device according to claim 6 ,

wherein the ion implantation energy of the first impurity is greater than the implantation energy of the second impurity.

9. The method of manufacturing a semiconductor device according to claim 8 ,

wherein the second impurity is ion-implanted from a direction perpendicular to the main surface of the semiconductor substrate.

10. The method of manufacturing a semiconductor device according to claim 6 ,

wherein the impurity concentration of the second semiconductor region is higher than the impurity concentration of each of the first semiconductor region and the third semiconductor region.

11. The method of manufacturing a semiconductor device according to claim 6 ,

wherein the width of the first sidewall insulating film is smaller than the width of the second sidewall insulating film.

12. The method of manufacturing a semiconductor device according to claim 6 , further comprising between the step (h) and the step (i):

(m) removing the second sidewall insulating film from the second region,

wherein in the step (j), the third sidewall insulating film is formed over the side wall of the second gate electrode in the second region; and

wherein in the step (k), in the second region, a fifth semiconductor region is formed by ion implantation of the fourth impurity in the second well region from the outside of the second gate electrode, the first sidewall insulating film, and the third sidewall insulating film in the second region.

13. The method of manufacturing a semiconductor device according to claim 12 ,

wherein the second semiconductor region and the fifth semiconductor region form the second source region or the second drain region.

14. The method of manufacturing a semiconductor device according to claim 6 , further comprising between the step (h) and the step (j):

(n) forming, in the first region, a sixth semiconductor region by ion implantation of a fifth impurity of the second conductivity type in the first well region from the outside of the first gate electrode, the first sidewall insulating film, and the second sidewall insulating film,

wherein the fifth impurity is ion-implanted from a direction perpendicular to the main surface of the semiconductor substrate.

15. The method of manufacturing a semiconductor device according to claim 14 ,

wherein the impurity concentration of the sixth semiconductor region is higher than the impurity concentration of the third semiconductor region.