Semiconductor device and method for manufacturing the same
The semiconductor device has an insulation layer formed over a semiconductor substrate, a conductor plug 46 buried in the insulation layer, a capacitor formed above the insulation layer and the conductor plug and including a lower electrode formed of the first conduction film and the second conduction film formed over the first conduction film and formed of Pt, Pt alloy, Pd or Pd alloy, a capacitor dielectric film formed of a ferroelectric or a high dielectric formed over the lower electrode and an upper electrode formed over the capacitor dielectric film, the capacitor dielectric film contains a first element of Pb or Bi, and the concentration peak of the first element diffused in the lower electrode from the capacitor dielectric film positioning in the interface between the first conduction film and the second conduction film.
1. A method for manufacturing a semiconductor device comprising a capacitor including a lower electrode, a capacitor dielectric film of a ferroelectric or a high dielectric formed over the lower electrode and an upper electrode formed over the capacitor dielectric film, comprising:
forming a transistor over a semiconductor substrate;
forming an insulation layer over the semiconductor substrate and over the transistor;
burying a conductor plug in the insulation layer so that the conductor plug is electrically coupled to the transistor;
forming over the insulation layer and the conductor plug, the lower electrode including a first conduction film and a second conduction film formed over the first conduction film;
forming the capacitor dielectric film over the lower electrode, the capacitor dielectric film containing a first element of Pb or Bi, and
forming the upper electrode over the capacitor dielectric film wherein the lower electrode prevents the diffusion of the first element at an interface between the first conduction film and the second conduction film,
the method further comprising, after the burying the conductor plug and before forming the first conduction film, forming a conducting oxygen barrier film for preventing oxidation of the conduction plug,
wherein a concentration profile of the first element across the lower electrode along a direction perpendicular to the interface has a concentration peak in the interface between the first conduction film and the second conduction film.
2. The method for manufacturing a semiconductor device according to claim 1 , wherein
the first conduction film is formed of a platinum oxide or a palladium oxide; and
the second conduction film is Pt, a Pt alloy, Pd or a Pd alloy.
3. The method for manufacturing a semiconductor device according to claim 1 , wherein the lower electrode further comprises:
forming a third conduction film of Pt, a Pt alloy, Pd or a Pd alloy formed over the second conduction film.
4. The method for manufacturing a semiconductor device according to claim 1 , further comprising, after forming the lower electrode and before forming the capacitor dielectric film:
performing thermal processing in an atmosphere of an inert gas to partially reduce the lower electrode.
5. The method for manufacturing a semiconductor device according to claim 1 , wherein
forming the capacitor dielectric film includes forming a first dielectric film over the lower electrode by sputtering or a sol-gel process and forming a second dielectric film over the first dielectric film by metal organic chemical vapor deposition.
6. The method for manufacturing a semiconductor device according to claim 1 , wherein the oxygen barrier film is formed of TiAIN, TiAION, TaAIN or TaAION.
7. The method for manufacturing a semiconductor device according to claim 6 , further comprising, after burying the conductor plug and before forming the oxygen barrier film:
forming a conducting adhesion layer for improving crystallinity of the oxygen barrier film and for improving adhesion between the oxygen barrier film and the insulation layer.
8. The method for manufacturing a semiconductor device according to claim 7 , further comprising, after burying the conductor plug and before forming the adhesion layer:
exposing a surface of the insulation layer and a surface of the conduction plug to a plasma containing nitrogen.
9. The method for manufacturing a semiconductor device according to claim 8 , wherein
the plasma containing nitrogen is NH 3 plasma or N 2 plasma.
10. The method for manufacturing a semiconductor device according to claim 6 , further comprising, after burying the conductor plug and before forming the oxygen barrier film:
forming a base layer; and
polishing a surface of the base layer to planarize the surface of the base layer.
11. The method for manufacturing a semiconductor device according to claim 6 , further comprising, after burying the conductor plug and before forming the oxygen barrier film:
burying a base layer in a cavity formed in a part of the conductor plug where the conductor plug has been buried.