Variable resistance element, semiconductor device having variable resistance element, semiconductor device manufacturing method, and programming method using variable resistance element
This variable resistance element is provided with a variable resistance film, a first electrode, which is disposed in contact with one surface of the variable resistance film, and a second electrode, which is disposed in contact with the other surface of the variable resistance film. The first and the second electrodes have corner portions, respectively, and the distance between the corner portions of the first and the second electrodes is set equal to the shortest distance between the first and the second electrodes. Furthermore, the variable resistance element has a third electrode, which is disposed on the one surface of the variable resistance film.
1. A variable resistance element comprising:
a variable resistance film;
a first electrode placed on one of surfaces of the variable resistance film, the first electrode configured to be a wiring; and
a second electrode placed on the other surface of the variable resistance film, the second electrode configured to be an inactive electrode,
wherein
the first electrode has a curved edge;
an insulation barrier film has an opening formed therein, in which a part of the variable resistance film is inserted, the insulation barrier film provided between the first electrode and the variable resistance film; and
the curved edge of the first electrode is in contact with the variable resistance film through the opening.
2. The variable resistance element according to claim 1 comprising a third electrode placed on the one of surfaces of the variable resistance film, wherein
the third electrode is arranged so as to overlap the variable resistance film through the opening more so than the first electrode, wherein the first electrode is configured to be an active electrode.
3. The variable resistance element according to claim 1 , wherein,
the variable resistance element is a bipolar type,
the first electrode comprises a material as a supply source of a metal ion,
the second electrode is composed of a material which is harder to ionize than the first electrode, and
the variable resistance film is an ion conductive layer in which the metal ion is conductive.
4. The variable resistance element according to claim 3 , wherein,
the first electrode serves as a copper wiring, and
a surface of the first electrode that does not contact the variable resistance film is covered with a barrier metal.
5. The variable resistance element according to claim 3 , wherein at least the curved edge of the first electrode is composed of a material comprising copper.
6. The variable resistance element according to claim 3 , further comprising a third electrode placed on the one of surfaces of the variable resistance film, wherein,
the third electrode serves as a copper wiring, and
a surface of the third electrode that does not contact the variable resistance film is covered with a barrier metal.
7. The variable resistance element according to claim 4 , wherein:
the first electrode is configured to be any one of wiring layers of multi-layer wiring, and
the curved edge of the first electrode is configured to be a point such that the distance between the first electrode and a curved edge of the second electrode is the uniquely determined shortest distance between the curved edge of the first electrode and the curved edge of the second electrode.
8. A semiconductor device comprising the variable resistance element according to claim 1 .
9. A programming method using a variable resistance element, the variable resistance element including a variable resistance film; a first electrode placed on one of surfaces of the variable resistance film, the first electrode configured to be a wiring; a second electrode placed on the other surface of the variable resistance film, the second electrode configured to be an inactive electrode; and a third electrode placed on the one of surfaces of the variable resistance film and configured to be an inert electrode, wherein the first electrode has a curved edge; an insulation barrier film having an opening formed therein, in which a part of the variable resistance film is inserted, the insulation barrier film provided between the first electrode and the variable resistance film; and the curved edge of the first electrode is in contact with the variable resistance film through the opening; the method comprising:
applying a voltage between the first and second electrodes in an initial state; and
changing the electrical resistance of the variable resistance film by applying a voltage pulse to the third electrode.