Semiconductor device and its manufacturing method
A semiconductor device having, on a silicon substrate, a gate insulating film and a gate electrode in this order; wherein the gate insulating film comprises a nitrogen containing high-dielectric-constant insulating film which has a structure in which nitrogen is introduced into metal oxide or metal silicate; and the nitrogen concentration in the nitrogen containing high-dielectric-constant insulating film has a distribution in the direction of the film thickness; and a position at which the nitrogen concentration in the nitrogen containing high-dielectric-constant insulating film reaches the maximum in the direction of the film thickness is present in a region at a distance from the silicon substrate. A method of manufacturing a semiconductor device including introducing nitrogen by irradiating the high-dielectric-constant insulating film which is made of metal oxide or metal silicate, with a nitrogen containing plasma, is also provided.
1. A semiconductor device, comprising:
a gate insulating film and a gate electrode stacked in this order;
wherein said gate insulating film and said gate electrode are in contact with each other; and
wherein said gate insulating film comprises a silicon oxide film formed on a silicon substrate so as to be in contact therewith, and a nitrogen containing high-dielectric-constant insulating film formed on said silicon oxide film so as to be in contact therewith; and
wherein said nitrogen containing high-dielectric-constant insulating film which has a structure in which nitrogen is introduced into metal oxide or metal silicate; and
wherein a nitrogen concentration in said nitrogen containing high-dielectric-constant insulating film has a distribution in a direction of a film thickness; and
a position at which the nitrogen concentration in said nitrogen containing high-dielectric-constant insulating film reaches a maximum in the direction of the film thickness is present in a region at a distance from the silicon substrate such that a maximum impurity concentration of the nitrogen concentration is greater than a nitrogen concentration at an interface between the silicon oxide film and the nitrogen containing high-dielectric-constant insulating film.
2. The semiconductor device according to claim 1 , wherein said position at which the nitrogen concentration in said nitrogen containing high-dielectric-constant insulating film reaches the maximum in the direction of the film thickness is present in the region at the distance of not less than 0.5 nm from the silicon substrate.
3. The semiconductor device according to claim 1 , wherein said position at which the nitrogen concentration in said nitrogen containing high-dielectric-constant insulating film reaches the maximum in the direction of the film thickness is localized on a side of the gate electrode in said nitrogen containing high-dielectric-constant insulating film.
4. The semiconductor device according to claim 1 , wherein the position at which the nitrogen concentration in said nitrogen containing high-dielectric-constant insulating film reaches the maximum in the direction of the film thickness is localized in a central section of said nitrogen containing high-dielectric-constant insulating film.
5. The semiconductor device according to claim 1 , wherein the nitrogen concentration on a silicon substrate side interface of said gate insulating film is less than 3 atomic %.
6. The semiconductor device according to claim 1 , wherein the position of the maximum impurity concentration of the nitrogen concentration is present in the region at a distance from the silicon oxide film.
7. The semiconductor device according to claim 1 , wherein said silicon substrate and said gate insulating film are in contact with each other, and said gate insulating film and said gate electrode are in contact with each other; and
said gate electrode is made of either a polysilicon or a polysilicon germanium conductive film.
8. The semiconductor device according to claim 1 , wherein said gate insulating film contains at least one type selected from the group consisting of Zr, Hf, Ta, Al, Ti, Nb, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu.
9. The semiconductor device according to claim 1 , wherein the film thickness of said nitrogen containing high-dielectric-constant insulating film is greater than a film thickness of said silicon oxide film.