Nonvolatile memory device and manufacturing method thereof

1. A nonvolatile memory device comprising:

first and second electrodes including first and second materials, respectively;

a conductive plug under the first and second electrodes, the conductive plug being electrically connected to the first electrode;

a bit line above the first and second electrodes, the bit line being electrically connected to the second electrode;

a first layer between the first and second electrodes;

a second layer between the first layer and the second electrode;

an information storage layer between the first and second layer,

wherein,

the first layer has a positive Peltier coefficient,

the second layer has a negative Peltier coefficient,

the information storage layer includes (a) resistance change layer that stores information as a changed electrical resistance value, and (b) an ionic source layer on the resistance change layer, the ionic source layer being a source of ions when an electrical potential is applied across the first and second electrodes,

the ionic source layer has a first portion and a second portion,

the first portion of the ionic source layer is between the resistance change layer and the second layer, with the second electrode being over the second layer,

the second portion of the ionic source layer is on the resistance change layer but the second layer and the second electrode are not disposed over the second portion of the ionic source layer,

the second portion of the ionic source layer is oxidized while the first portion of the ionic source layer is not oxidized, and

the second portion of the ionic source layer is less thick than the first portion of the ionic source layer.

2. The nonvolatile memory device according to claim 1 , wherein the first layer is made of a p-type thermoelectric material, and the second layer is made of an n-type thermoelectric material.

3. The nonvolatile memory device according to claim 1 , wherein a Seebeck coefficient of the first material of the first electrode is different from a Seebeck coefficient of the second material of the second electrode.

4. The nonvolatile memory device according to claim 1 , wherein:

the first material of the first electrode is a material selected from the group consisting of silver, gold, copper, lead, palladium, platinum, titanium, titanium nitride, and tungsten, and

the second material of the second electrode is a material selected from the group consisting of silver, gold, copper, lead, palladium, platinum, titanium, titanium nitride, and tungsten.

5. The nonvolatile memory device according to claim 1 , wherein the ionic source layer includes an ionic conductor that includes a metal.

6. A method of manufacturing a nonvolatile memory device comprising:

sequentially forming, on a substrate:

(a) a conductive plug,

(b) a first electrode including a first material,

(c) a first layer having a positive Peltier coefficient,

(d) an information storage layer including (i) a resistance change layer that stores information as a changed electrical resistance value, and (ii) an ionic source layer on the resistance change layer, the ionic source layer being a source of ions,

(e)the second layer having a negative Peltier coefficient,

(f) a second electrode including a second material, and

(g) a bit line,

wherein,

the ionic source layer has a first portion and a second portion,

the first portion of the ionic source layer is formed between the resistance change layer and the second laver, with the second electrode being formed over the second layer,

the second portion of the ionic source layer is formed on the resistance change layer but the second layer and the second electrode are not formed over the second portion of the ionic source layer,

after the ionic source layer is formed, the second portion of the ionic source layer is oxidized while the first portion of the ionic source layer is not oxidized, and

after being oxidized, the second portion of the ionic source layer is reduced in thickness to be less thick than the first portion of the ionic source layer.

7. The method of claim 6 , wherein the first layer is formed of a p-type thermoelectric material, and the second layer is formed of an n-type thermoelectric material.

8. The method of claim 6 , wherein a Seebeck coefficient of the first material of the first electrode is different from a Seebeck coefficient of the second material of the second electrode.

9. The method of claim 6 , wherein:

the first material of the first electrode is a material selected from the group consisting of silver, gold, copper, lead, palladium, platinum, titanium, titanium nitride, and tungsten, and

the second material of the second electrode is a material selected from the group consisting of silver, gold, copper, lead, palladium, platinum, titanium, titanium nitride, and tungsten.

10. The method of claim 6 , wherein the ionic source layer includes an ionic conductor that includes a metal.

11. The nonvolatile memory device according to claim 1 , wherein the second portion of the ionic source layer is about half as thick as the first portion of the ionic source layer.

12. The nonvolatile memory device of according to claim 1 , wherein:

the second portion of the ionic source layer has a first part and a second part, and

along a direction parallel to a surface of the second layer that faces the ionic source layer, the first and second parts of the second portion are respectively disposed on two sides of the first portion the ionic source layer.

13. The method according to claim 6 , wherein the second portion of the ionic source layer is reduced in thickness to be about half as thick as the first portion of the ionic source layer.

14. The method according to claim 6 , wherein:

the second portion of the ionic source layer has a first part and a second part, and

along a direction parallel to a surface of the second layer that faces the ionic source layer, the first and second parts of the second portion are respectively disposed on two sides of the first portion the ionic source layer.