Capacitor, semiconductor device having the same, and method of producing them
Provided is a capacitor that realizes a capacitance insulation film having a large relative permittivity and has sufficient capacitance even if an occupied space is small with a reduced amount of leakage current. A capacitor includes: a capacitance insulation film; and an upper electrode and lower electrode each formed on both sides of the capacitance insulation film. The capacitance insulation film is a complex oxide whose main ingredients are Zr, Al and O with the composition ratio of Zr to Al being set at (1−x): x (0.01≦x≦0.15) and is composed of a dielectric substance having a crystal structure. The lower electrode is composed of a conductor whose surface contiguous to at least the dielectric film has an amorphous structure.
1. A capacitor comprising:
a capacitance insulation film; and
an upper electrode and lower electrode each formed on both sides of the capacitance insulation film,
the capacitance insulation film being a complex oxide whose main ingredients are Zr, Al and O with the composition ratio of Zr to Al being set at (1−x): x (0.01≦x≦0.15) and being composed of a dielectric substance having a crystal structure, and
the lower electrode being composed of a conductor whose surface contiguous to at least the capacitance insulation film has an amorphous structure, wherein
the dielectric substance has a composition of Zr (1-x) Al x O y (0.01≦x≦0.15, 1≦y≦2-0.5x).
2. The capacitor according to claim 1 , wherein
the lower electrode has a laminated structure of a polycrystalline film and an amorphous film, with the amorphous film contiguous to the capacitance insulation film.
3. The capacitor according to claim 1 , wherein
the lower electrode has a laminated structure of an amorphous film and a metal polycrystalline film to which at least nitrogen or carbon is added, with the amorphous film contiguous to the capacitance insulation film.
4. The capacitor according to claim 1 , wherein
the major constituent element of the lower electrode is at least one metal or metal nitride selected from the group consisting of Ta, TaN, Ti and TiN.
5. The capacitor according to claim 1 ,
wherein the dielectric substance has a composition of Zr (1-x) Al x O y (0.02≦x≦0.10, 1≦y≦2−0.5x).
6. The capacitor according to claim 1 , wherein the dielectric substance has a composition of Zr (1-x) Al x O y (0.02≦x≦0.05, 1≦y≦2−0.5x).
7. The capacitor according to claim 1 , wherein
the upper electrode is composed of at least one metal or metal nitride selected from the group consisting of TiN, Ti, W, Pt, Ir and Ru.
8. The capacitor according to claim 1 , further comprising
a tubular structure in at least some portion.
9. The capacitor according to claim 1 , wherein the dielectric substance has a composition of Zr (1-x) Al x O y (0.01≦x≦0.08, 1≦y≦2−0.5x).
10. The capacitor according to claim 1 , comprising
a three-layer structure made up of the lower electrode, the capacitance insulation film and the upper electrode, wherein
the three-layer structure has a plurality of portions formed on different surfaces.
11. The capacitor according to claim 10 , wherein
the three-layer structure has a plurality of portions that cross each other at right angles.
12. A semiconductor device comprising:
the capacitor according to claim 1 ; and
a semiconductor substrate at least a surface of which is composed of a semiconductor,
the capacitor being formed on the semiconductor substrate.
13. The semiconductor device according to claim 12 , wherein:
a switching element is formed on the semiconductor substrate; and
the capacitor and the switching element are electrically connected.
14. A method of producing a capacitor having a capacitance insulation film and an upper electrode and lower electrode each formed on both sides of the capacitance insulation film, the method comprising:
a step of forming, as the lower electrode, a first electrode composed of a conductor whose surface contiguous to at least the capacitance insulation film has an amorphous structure;
a step of forming, as the capacitance insulation film, a dielectric film that is a complex oxide whose main ingredients are Zr, Al and O with the composition ratio of Zr to Al being set at (1−x): x (0.01≦x≦0.15) and is composed of a dielectric substance having a crystal structure; wherein the dielectric substance has a composition of Zr (1-x) Al x O y (0.01≦x≦0.15, 1≦y≦2−0.5x); and
a step of forming, as the upper electrode, a second electrode.
15. The method of producing the capacitor according to claim 14 , wherein
the step of forming the first electrode is a step of forming a laminated structure of a polycrystalline film and an amorphous film.
16. A method of producing a semiconductor device, comprising:
with the use of the method of producing the capacitor according to claim 14 , on a semiconductor substrate at least a surface of which is composed of a semiconductor, forming a capacitor having the first electrode, the dielectric film and the second electrode.