Variable resistance element and memory device

Patent metadata

Field	Value
Publication number	US-10312440-B2
Application number	US-201715704112-A
Country	US
Kind code	B2
Filing date	Sep 14, 2017
Priority date	Mar 14, 2017
Publication date	Jun 4, 2019
Grant date	Jun 4, 2019

Abstract

According to one embodiment, a variable resistance element includes first and conductive layers and first and second layers. The first conductive layer includes a first element including at least one selected from the group consisting of silver, copper, aluminum, nickel, and titanium. The second conductive layer includes at least one selected from the group consisting of platinum, gold, iridium, tungsten, palladium, rhodium, titanium nitride, and silicon. A first layer contacts the first conductive layer, and is provided between the first and second conductive layers. The first layer includes a first material. The first material is insulative. The second layer includes a second element and a second material and is provided between the first layer and the second conductive layer. The second element includes at least one selected from the group consisting of silver, copper, aluminum, nickel, and titanium. The second material is different from the first material.

First claim

What is claimed is:

1. A variable resistance element, comprising:
a first conductive layer including a first element including at least one selected from the group consisting of silver, copper, aluminum, nickel, and titanium;
a second conductive layer including at least one selected from the group consisting of platinum, gold, iridium, tungsten, palladium, rhodium, titanium nitride, and silicon;
a first layer contacting the first conductive layer, being provided between the first conductive layer and the second conductive layer, and including a first material, the first material being insulative; and
a second layer including a second element and a second material and being provided between the first layer and the second conductive layer, the second element including at least one selected from the group consisting of silver, copper, aluminum, nickel, and titanium, the second material being different from the first material, wherein
a thickness of the first layer is thinner than a thickness of the second layer.

2. The variable resistance element according to claim 1 , wherein
the second material includes an oxide.

3. The variable resistance element according to claim 1 , wherein an electron affinity of the first material is smaller than an electron affinity of the second material.

4. The variable resistance element according to claim 2 , wherein
the first material includes an oxide including at least one selected from the group consisting of Si, Mg, Ca, Hf, Zr, Sc, Ga, Al, Y, La, and Ce, and
the oxide included in the second material includes at least one selected from the group consisting of Ta, Nb, Mo, V, Cu, Fe, Mn, Ge, Zn, Gd, and W.

5. The variable resistance element according to claim 2 , wherein
the first material includes an oxide including at least one selected from the group consisting of Si, Mg, Ca, Al, Y, La, and Ce, and
the oxide included in the second material includes at least one selected from the group consisting of Hf, Zr, Sc, and Ga.

6. The variable resistance element according to claim 2 , wherein
the first material includes an oxide including at least one selected from the group consisting of Si, Mg, and Ca, and
the oxide included in the second material includes at least one selected from the group consisting of Al, Y, La, and Ce.

7. The variable resistance element according to claim 1 , wherein a relative dielectric constant of the first material is higher than a relative dielectric constant of the second material.

8. The variable resistance element according to claim 1 , wherein a concentration of the second element in the second layer is 1×10 20 atoms/cm 3 or more.

9. The variable resistance element according to claim 1 , wherein the first material includes aluminum oxide.

10. The variable resistance element according to claim 1 , wherein the second material includes hafnium oxide.

11. The variable resistance element according to claim 1 , wherein
a thickness of the first layer is not less than 0.2 nanometers and not more than 1.5 nanometers, and
a thickness of the second layer is greater than 1.5 nanometers and not more than 10 nanometers.

12. The variable resistance element according to claim 1 , wherein
the first material includes aluminum oxide,
the second material includes hafnium oxide,
the first layer does not include the second element, or
the first layer includes the second element, and a concentration of the second element in the second layer is higher than a concentration of the second element in the first layer.

13. A memory device, comprising:
the variable resistance element according to claim 1 ;
a first interconnect electrically connected to the first conductive layer;
a second interconnect electrically connected to the second conductive layer; and
a controller electrically connected to the first interconnect and the second interconnect, the controller implementing:
a first operation of applying a first voltage to the first interconnect, the first voltage being positive when referenced to a potential of the second interconnect,
a second operation of applying a second voltage to the first interconnect, the second voltage being negative when referenced to the potential of the second interconnect, and
a third operation of applying a third voltage to the first interconnect, the third voltage being smaller than the first voltage and being positive when referenced to the potential of the second interconnect,
the absolute value of a first current flowing in a stacked body via the first interconnect and the second interconnect in the third operation implemented after the first operation is greater than the absolute value of a second current flowing in the stacked body in the third operation implemented after the second operation, the stacked body including the first conductive layer, the second conductive layer, the first layer, and the second layer, and
the absolute value of a fourth current flowing in the stacked body via the first interconnect and the second interconnect when a fourth voltage is applied to the first interconnect is greater than the absolute value of a fifth current flowing in the stacked body via the first interconnect and the second interconnect when a fifth voltage is applied to the first interconnect, the fourth voltage being positive when referenced to the potential of the second interconnect, the fifth voltage being negative when referenced to the potential of the second interconnect, the fourth voltage being ⅓ of the third voltage, the absolute value of the fifth voltage being ⅓ of the third voltage.

14. The device according to claim 13 , wherein the absolute value of the first voltage is less than the absolute value of the second voltage.

15. The device according to claim 13 , wherein the absolute value of the first current is not less than 100 times the absolute value of the fourth current.

16. The device according to claim 13 , wherein the absolute value of the fifth voltage is less than ⅓ of the absolute value of the second voltage.

17. A variable resistance element, comprising:
a first conductive layer including a first element including at least one selected from the group consisting of silver, copper, aluminum, nickel, and titanium;
a second conductive layer including at least one selected from the group consisting of platinum, gold, iridium, tungsten, palladium, rhodium, titanium nitride, and silicon;
a first layer contacting the first conductive layer, being provided between the first conductive layer and the second conductive layer, and including a first material, the first material being insulative; and
a second layer including a second element and a second material and being provided between the first layer and the second conductive layer, the second element including at least one selected from the group consisting of silver, copper, aluminum, nickel, and titanium, the second material being different from the first material, wherein
the first layer does not include the second element, or
the first layer includes the second element, and a concentration of the second element in the second layer is higher than a concentration of the second element in the first layer.

18. The variable resistance element according to claim 17 , wherein the second material includes an oxide.

19. The variable resistance element according to claim 17 , wherein an electron affinity of the first material is smaller than an electron affinity of the second material.

20. The variable resistance element according to claim 18 , wherei

Assignees

• Toshiba Memory Corp
• Toshiba Mitsubishi Corp

Inventors

• Kuriyama Hiromichi
• Saitoh Masumi
• Ishikawa Takayuki
• Watanabe Harumi

Classifications

• G11C2213/15

  Current-voltage curve · CPC title

• G11C2213/54

  Structure including a tunneling barrier layer, the memory effect implying the modification of tunnel barrier conductivity · CPC title

• G11C13/0069 Primary

  Writing or programming circuits or methods · CPC title

• G11C11/5614

  using conductive bridging RAM [CBRAM] or programming metallization cells [PMC] · CPC title

• G11C13/0011

  comprising conductive bridging RAM [CBRAM] or programming metallization cells [PMCs] · CPC title