Memory device and method for manufacturing same
According to one embodiment, a method for manufacturing a memory device is disclosed. The method includes forming a silicon diode. At least an upper portion of the silicon diode is made of a semiconductor material containing silicon and doped with impurity. The method includes forming a metal layer made of a metal on the silicon diode. The method includes forming a metal nitride layer made of a nitride of the metal on the metal layer. The method includes forming a resistance change film. In addition, the method includes reacting the metal layer with the silicon diode and the metal nitride layer by heat treatment to form an electrode film containing the metal, silicon, and nitrogen.
1. A memory device comprising:
a silicon diode, at least an upper portion of the silicon diode being made of a semiconductor material containing silicon and doped with impurity;
an electrode film provided on the silicon diode, being in contact with the silicon diode, and containing a metal, silicon, and nitrogen; and
a resistance change film provided below the silicon diode or above the electrode film,
the electrode film having higher silicon concentration in a lower surface of the electrode film than in an upper surface of the electrode film, and having higher nitrogen concentration in the upper surface than in the lower surface.
2. The device according to claim 1 , wherein a decrease amount of Gibbs free energy associated with oxidation reaction of the metal is larger than a decrease amount of Gibbs free energy associated with oxidation reaction of silicon.
3. The device according to claim 1 , wherein a heat absorption amount associated with oxidation reaction of the metal is larger than a heat absorption amount associated with oxidation reaction of silicon.
4. The device according to claim 1 , wherein the metal is one metal selected from the group consisting of titanium, tantalum, niobium, hafnium, zirconium, and chromium, or an alloy of the one metal with tungsten.
5. The device according to claim 1 , further comprising:
a metal nitride layer provided on the electrode film and containing the metal and nitrogen,
the resistance change film being located on the metal nitride layer.
6. The device according to claim 1 , further comprising:
a word line wiring layer made of a plurality of word lines extending in a first direction; and
a bit line wiring layer made of a plurality of bit lines extending in a second direction crossing the first direction,
the word line wiring layer and the bit line wiring layer being alternately stacked, and
a pillar having the silicon diode, the electrode film, and the resistance change film, the silicon diode, the electrode film, and the resistance change film being stacked, the pillar being formed between each of the word lines and each of the bit lines.