Semiconductor device with gate electrode having side surfaces doped with carbon
A semiconductor device includes a gate insulating film on a semiconductor substrate, and a gate electrode on the gate insulating film. The gate electrode includes a first layer containing polycrystalline silicon, a second layer between the first layer and the gate insulating film and containing polycrystalline silicon and carbon, a third layer on an upper surface of the first layer and containing polycrystalline silicon and carbon, a fourth layer on a first side surface of the first layer and containing polycrystalline silicon and carbon, and a fifth layer on a second side surface of the first layer and containing polycrystalline silicon and carbon.
1. A semiconductor device, comprising:
a semiconductor substrate;
a gate insulating film on the semiconductor substrate; and
a gate electrode on the gate insulating film, wherein
the gate electrode includes
a first layer containing polycrystalline silicon,
a second layer between the first layer and the gate insulating film and containing polycrystalline silicon and carbon,
a third layer on an upper surface of the first layer and containing polycrystalline silicon and carbon,
a fourth layer on a first side surface of the first layer and containing polycrystalline silicon and carbon, and
a fifth layer on a second side surface of the first layer and containing polycrystalline silicon and carbon.
2. The semiconductor device according to claim 1 , wherein a thickness of each of the second to fifth layers is equal to or less than 5 nm.
3. The semiconductor device according to claim 1 , wherein the first layer is wrapped by the second to fifth layers.
4. The semiconductor device according to claim 1 , further comprising:
insulating side walls contacting sides of the gate electrode.
5. The semiconductor device according to claim 4 , wherein the insulating side walls include silicon oxide.
6. The semiconductor device according to claim 1 , wherein a concentration of the carbon is equal to or more than 1×10 20 /cm 3 .
7. The semiconductor device according to claim 1 , further comprising:
the semiconductor substrate including a first area of a first conductivity type;
a second area of a second conductivity type being provided on the first area;
a third area of the second conductivity type being provided on the first area, the third area being arranged apart from the second area in a first direction parallel to a surface of the substrate;
a fourth area of the second conductivity type being provided between the first area and the second area; and
a fifth area of the second conductivity type being provided between the first area and the third area.
8. The semiconductor device according to claim 7 , wherein a concentration of the fourth area is less than a concentration of the second area.
9. The semiconductor device according to claim 7 , wherein a depth of the fourth area is less than a depth of the second area in a second direction vertical to the surface of the substrate.
10. The semiconductor device according to claim 7 , wherein the first area includes a sixth area of the first conductivity type, the sixth area provided below the gate insulating film.
11. The semiconductor device according to claim 10 , wherein a concentrate of the sixth area is higher than a concentrate of the first area.
12. A semiconductor device, comprising:
a semiconductor substrate;
a gate insulating film on the semiconductor substrate; and
a gate electrode on the gate insulating film, wherein
the gate electrode includes
a first layer containing polycrystalline silicon,
a second layer on a bottom surface of the first layer and containing polycrystalline silicon and carbon,
a third layer on an upper surface of the first layer and containing polycrystalline silicon and carbon,
a fourth layer on a first side surface of the first layer and containing polycrystalline silicon and nitride, and
a fifth layer on a second side surface of the first layer and containing polycrystalline silicon and nitride.
13. The semiconductor device according to claim 12 , wherein a concentration of the nitride is equal to or more than 1×10 20 /cm 3 .
14. The semiconductor device according to claim 12 , wherein a thickness of each of the second to fifth layers is equal to or less than 5 nm.
15. The semiconductor device according to claim 12 , wherein the first layer is wrapped by the second to fifth layers.
16. The semiconductor device according to claim 12 , further comprising:
insulating side walls contacting sides of the gate electrode.
17. The semiconductor device according to claim 16 , wherein the insulating side walls include silicon oxide.
18. The semiconductor device according to claim 12 , wherein a concentration of the carbon is equal to or more than 1×10 20 /cm 3 .
19. The semiconductor device according to claim 12 , wherein the fourth layer and the fifth layer extend to partially cover side surfaces of the gate insulating film.
20. The semiconductor device according to claim 12 , wherein the fourth layer and the fifth layer extend to entirely cover side surfaces of the gate insulating film.