Semiconductor device
According to one embodiment, it is possible to provide a semiconductor device provided with an MIS transistor which has an effective work function being, as much as possible, suitable for low threshold operation. A CMIS device provided with an electrode having an optimal effective work function and enabling low threshold operation to achieve by producing an in-gap level by the addition of a high valence metal in an Hf (or Zr) oxide and changing a position of the in-gap level by nitrogen or fluorine or the like has been realized.
1. A semiconductor device, comprising:
a semiconductor substrate having a first semiconductor layer and a second semiconductor layer separated from each other;
an nMIS transistor including,
a first source region and a first drain region, formed in the first semiconductor layer and separated from each other,
a first gate dielectric film covering a first channel region which is the first semiconductor layer between the first source region and the first drain region, and
a first gate electrode formed on the first gate dielectric film and including an Hf oxide film or a Zr oxide film in which a first element selected from a first group comprising Nb and W is added, and a second element selected from a second group comprising N, C, B, Mg, Ca, Sr, Ba, Al, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu is added; and
a pMIS transistor including,
a second source region and a second drain region, formed in the second semiconductor layer and separated from each other,
a second gate dielectric film covering a second channel region which is the second semiconductor layer between the second source region and the second drain region, and
a second gate electrode formed on the second gate dielectric film and including an Hf oxide film or a Zr oxide film in which the first element is added, and the second element is added in a larger amount than that in the first gate electrode.
2. The semiconductor device according to claim 1 , wherein the nMIS transistor and the pMIS transistor are each a Fin MIS transistor.
3. The semiconductor device according to claim 1 , wherein the added amount [α] (atom/cm 2 ) of the first element α selected from the first group and the added amount [β] (atom/cm 2 ) of the second element β selected from the second group satisfy the following expression:
0.08×[α]<[β]× K <[α]×([Number of electrons in the outermost shell of the element α]−4),
wherein the number of electrons in the outermost shell of the first element α is 5 for Nb and 6 for W, respectively;
when the second element β is N, then K is 1;
when the second element β is C, then K is 2;
when the second element β is B, then K is 3;
when the second element β is Mg, Ca, Sr or Ba, then K is 2; and
when the second element β is Al, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb or Lu, then K is 1.
4. The semiconductor device according to claim 1 , wherein the first element which is selected from the first group has an area density of 1×10 14 atoms/cm 2 or more and not more than 8×10 14 atoms/cm 2 .
5. The semiconductor device according to claim 1 , wherein the first element which is selected from the first group has an area density of 6×10 12 atoms/cm 2 or more and less than 1×10 14 atoms/cm 2 .
6. A semiconductor device, comprising:
a semiconductor substrate having a first semiconductor layer and a second semiconductor layer separated from each other;
an nMIS transistor including,
a first source region and a first drain region, which regions are formed in the first semiconductor layer and separated from each other,
a first gate dielectric film covering a first channel region which is the first semiconductor layer between the first source region and the first drain region,
a first gate electrode formed on the first gate dielectric film and including an Hf oxide film or a Zr oxide film in which Mo is added, and a first element selected from a first group comprising F, H and Ta is added; and
a pMIS transistor including,
a second source region and a second drain region, which regions are formed in the second semiconductor layer and separated from each other,
a second gate dielectric film covering a second channel region which is the second semiconductor layer between the second source region and the second drain region, and
a second gate electrode formed on the second gate dielectric film and including an Hf oxide film or a Zr oxide film in which the first element is added, and the second element is added in a smaller amount than that in the first gate electrode.
7. The semiconductor device according to claim 6 , wherein the nMIS transistor and the pMIS transistor are each a Fin MIS transistor.
8. The semiconductor device according to claim 6 , wherein
the added amount [η] (atom/cm 2 ) of the first element η which is selected from the first group and added and the added amount [θ] (atom/cm 2 ) of the second element θ which is selected from the second group and added satisfy the following expression:
0.08×[η]<[θ]×[η]×(8−[Number of electrons in the outermost shell of the first element η]),
wherein the number of electrons in the outermost shell of the first element η is 5 for V, 6 for Cr and 7 for Mn, Tc or Re, respectively.
9. The semiconductor device according to claim 6 , wherein the first element which is selected from the first group and added has an area density of 1×10 14 atoms/cm 2 or more and not more than 8×10 14 atoms/cm 2 .
10. The semiconductor device according to claim 6 , wherein the first element which is selected from the first group and added has an area density of 6×10 12 atoms/cm 2 or more and less than 1×10 14 atoms/cm 2 .
11. The semiconductor device according to claim 1 , wherein
when the first and second gate electrodes include an Hf oxide film, the Hf oxide film is made of any one of hafnium oxide, hafnium silicate and hafnium nitride silicate or a laminated film thereof; and
when the first and second gate electrodes include a Zr oxide film, the Zr oxide film is made of any one of zirconium oxide, zirconium silicate and zirconium nitride silicate or a laminated film thereof.