1. A method for fabricating a semiconductor device, comprising: forming a dielectric layer in which zirconium, hafnium, and a IV group element are mixed, wherein the dielectric layer includes a ZrHfCeO layer and has a dielectric constant of 50 to 60.
2. The method of claim 1 , wherein the dielectric layer is formed using an atomic layer deposition method.
3. The method of claim 2 , wherein, in performing the atomic layer deposition method, a zirconium deposition cycle is performed A times, a hafnium deposition cycle is performed B times, a IV group element deposition cycle is performed C times, and the foregoing deposition cycles as a unit is performed D times, wherein A, B, C and D are natural numbers, wherein the numbers A is adjusted not to exceed the maximum deposition thickness by which the zirconium remains mixable, wherein the number B is adjusted not to exceed the maximum deposition thickness by which the hafnium remains mixable, wherein the number C is adjusted not to exceed the maximum deposition thickness by which the IV group element remains mixable, and wherein the number D is adjusted not to exceed a desired deposition total thickness of the dielectric layer.
4. The method of claim 2 , wherein in performing the atomic layer deposition method, a zirconium/hafnium deposition cycle is performed E times, and a IV group element deposition cycle is performed F times, and the foregoing deposition cycles as a unit is performed G times, wherein E, F and G are natural numbers, wherein the number E is adjusted not to exceed the maximum deposition thickness by which the zirconium/hafnium remains mixable, wherein the number G is adjusted not to exceed the maximum deposition thickness by which the IV group element remains mixable, and wherein the number G is adjusted not to exceed a desired deposition total thickness of the dielectric layer.
5. The method of claim 3 , wherein each of the deposition cycles includes a source gas introduction step, a purge step, a reaction gas introduction step, and a purge step.
6. The method of claim 4 , wherein the zirconium/hafnium deposition cycle includes a step of introducing a mixed source of zirconium and hafnium, a purge step, a reaction gas introduction step, and a purge step.
7. The method of claim 6 , wherein, in the mixed source, a mixture ratio of the zirconium and the hafnium is adjusted to be 1:1 to 4.
8. A method for fabricating a capacitor, comprising: forming a bottom electrode; forming a dielectric layer over the bottom electrode, wherein zirconium, hafnium, and a IV group element are mixed in the dielectric layer; and forming a top electrode over the dielectric layer, wherein the dielectric layer has a stack structure of a ZrHfMO layer and an M-rich ZrHfMO layer, wherein M is a IV group element.
9. The method of claim 8 , wherein the IV group element includes Si or Ce.
10. The method of claim 8 , wherein the M-rich ZrHfMO layer is formed at a portion of the dielectric layer making contact with the bottom electrode.
11. The method of claim 8 , wherein the dielectric layer further comprises an M-rich ZrHfMO layer is formed at a portion of the dielectric layer making contact with the top electrode.
12. The method of claim 8 , further, before the forming of the top electrode, comprising: performing a thermal process on the dielectric layer; and performing a surface nitrification process.
13. The method of claim 12 , wherein the thermal process includes a primary thermal process and a second thermal process or the primary thermal process and a plasma oxidation process.
14. The method of claim 13 , wherein the primary thermal process is performed in a rapid thermal process or a furnace at a temperature of 500° C. to 700° C. under a nitrogen atmosphere.
15. The method of claim 13 , wherein the secondary thermal process is performed in a rapid thermal process or a furnace under a O 2 or O 3 atmosphere.
16. The method of claim 13 , wherein the plasma oxidation process is performed at a temperature of 300° C. to 500° C. under the pressure of 0.1 Torr to 10 Torr.
17. The method of claim 12 , wherein the surface nitrification process is performed as a plasma nitrification process.
18. The method of claim 17 , wherein the surface nitrification process is performed using N 2 plasma or NH 3 plasma at a temperature of 300° C. to 500° C. under the pressure of 0.1 Torr to 10 Ton.
