KR20170073016A

KR20170073016A - Method of manufacturing Resistance Random Access Memory Device and Resistance Random Access Memory Device manufactured by the same

Info

Publication number: KR20170073016A
Application number: KR1020150181286A
Authority: KR
Inventors: 홍진표; 이아람; 백광호; 김태윤
Original assignee: 한양대학교 산학협력단
Priority date: 2015-12-17
Filing date: 2015-12-17
Publication date: 2017-06-28
Also published as: KR101764983B1

Abstract

A method of manufacturing a resistance change memory element and a resistance change memory element manufactured thereby. A method of fabricating a resistance change memory element includes forming an inert electrode on a substrate, forming a nitrogen-doped metal oxide layer on the inert electrode, and forming an active electrode on the nitrogen-doped metal oxide layer Wherein the step of forming the nitrogen-doped metal oxide layer is performed by performing sputtering in an atmosphere of a mixed gas of a nitrogen gas and an inert gas. Therefore, by forming the metal oxide layer doped with nitrogen as the resistance variable layer, it is possible to provide a resistance change memory element that operates without a forming process.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a resistance change memory device,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a resistance-variable memory element and a resistance-variable memory element manufactured thereby, and more particularly, to a method for manufacturing a resistance-variable memory element that operates without a forming process and a resistance-variable memory element manufactured thereby.

Recently, the development of digital information communication and household appliances industry has led to limitations in research on devices based on conventional charge control. In order to overcome these limitations, new memory devices using phase change and magnetic field change are being studied. The information storage method of new memory devices which is under study uses the principle of changing the resistance of the material itself by inducing the change of the material state.

In a flash memory which is a representative element of a nonvolatile memory, a high operation voltage is required for programming and erasing data. Therefore, when scale down by a line width of 45 nm or less, a malfunction may occur due to interference between adjacent cells, and slow operation speed and excessive power consumption are problematic.

Magnetic RAM (MRAM), another nonvolatile memory, has some problems in commercialization due to complicated manufacturing process and multi-layer structure, small margin of read / write operation. Therefore, development of a next generation nonvolatile memory device that can replace them is an essential research field.

Resistive RAM (ReRAM) devices have a structure in which an upper / lower electrode is disposed on a thin film and a resistance variable layer made of an oxide thin film is included between upper and lower electrodes. The memory operation is realized by using the phenomenon that the resistance state of the resistance variable layer is changed according to the voltage applied to the resistance variable layer.

In the case of a CBRAM (Conductive Bridge RAM) among these resistance change memory elements, metal filaments are formed by oxidation-reduction reaction of metal atoms or metal ions penetrating from the metal electrode into the resistance variable layer according to the voltage applied to the resistance variable layer And the resistance state is changed while disappearing.

Conventional ReRAM devices require a forming process before stable switching operation. Generally, a foaming phenomenon appears at a voltage bias that is much larger than the read, write, and erase voltages of the switching operation. Therefore, when a highly integrated array structure is applied, it may cause difficulties in circuit construction and may affect adjacent cells. In addition, there is a hard breakdown phenomenon in which a device breaks down during a high voltage process. Therefore, yield is also problematic. Setting a limit current to prevent this is also inconvenient for another additional design. Furthermore, since the switching characteristics appearing after the foaming phenomenon vary depending on the magnitude of the voltage inducing the foaming phenomenon, the limiting current, and the polarity, it has been found that ultimately it is advantageous to develop a device free from foaming phenomenon.

Korean Patent Publication No. 10-2012-0022218

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for fabricating a resistance-variable memory device that operates without a forming process, and a resistance-change memory device manufactured thereby.

According to one aspect of the present invention, there is provided a method of fabricating a resistance-variable memory device. A method of fabricating a resistance change memory element includes forming an inert electrode on a substrate, forming a nitrogen-doped metal oxide layer on the inert electrode, and forming an active electrode on the nitrogen-doped metal oxide layer Wherein the step of forming the nitrogen-doped metal oxide layer is performed by performing sputtering in an atmosphere of a mixed gas of a nitrogen gas and an inert gas.

The nitrogen-doped metal oxide layer is a nitrogen-doped binary metal oxide layer.

The binary metal oxide layer may also include tantalum oxide, nickel oxide, niobium oxide, titanium oxide, zirconium oxide, hafnium oxide, cobalt oxide, molybdenum oxide, vanadium oxide, tungsten oxide, aluminum oxide or zinc oxide .

In addition, the step of forming the nitrogen-doped metal oxide layer is characterized in that the nitrogen partial pressure of the mixed gas is 16.67% to 37.50%.

Therefore, the manufactured resistance change memory element is characterized in that the switching operation can be performed without forming.

In addition, the inert electrode may include Pt, Pt alloy, Pd or Pd alloy.

The active electrode may include Ta, Ta alloy, W, W alloy, Al, Al alloy, Ni, Ni alloy, Zr, Zr alloy, Ti or Ti alloy.

The nitrogen-doped metal oxide layer is a resistance-variable layer having a state change due to the formation and disappearance of the metal filament.

According to an aspect of the present invention, there is provided a resistance-change memory device. The resistance-variable memory device includes a substrate, an inert electrode disposed on the substrate, a resistance-variable layer located on the inert electrode and having a state change due to formation and disappearance of the metal filament, and an active electrode located on the resistance- And the resistance-variable layer is a nitrogen-doped metal oxide layer.

The nitrogen-doped metal oxide layer is formed by performing sputtering in an atmosphere of a mixed gas of nitrogen gas and inert gas.

The nitrogen partial pressure of the mixed gas is 16.67% to 37.50%.

The density of the nitrogen-doped metal oxide layer is not more than 8.0 g / cm ³ .

Further, the switching operation can be performed without a forming process.

According to the present invention, by forming the metal oxide layer doped with nitrogen as the resistance variable layer, a switching phenomenon with a sufficient on / off current ratio is possible without a high voltage forming process.

Accordingly, it is possible to solve the problems caused by the foaming phenomenon, to eliminate the high-voltage forming process, and to eliminate the limit current.

The technical effects of the present invention are not limited to those mentioned above, and other technical effects not mentioned can be clearly understood by those skilled in the art from the following description.

1 is a cross-sectional view illustrating a resistance change memory device according to an embodiment of the present invention.
2 is a graph showing a change in characteristics of a resistance-change memory device according to Comparative Example 1 in accordance with the foaming phenomenon.
FIGS. 3 and 4 are graphs showing current-voltage characteristics of the resistance-change memory device according to Production Example 1. FIG.
5 is a graph showing current-voltage characteristics of a resistance-change memory device according to Production Example 1. FIG.
6 is a graph showing the current-voltage characteristics of the resistance-change memory device according to Production Example 2. FIG.
7 is a graph showing current-voltage characteristics of a resistance-change memory device according to Production Example 3. FIG.
8 is a graph showing the current-voltage characteristics of the resistance-change memory device according to Production Example 4. FIG.
9 is a graph showing current-voltage characteristics of a resistance-change memory device according to Production Example 5. FIG.
10 is a graph showing current-voltage characteristics of a resistance-change memory device according to Production Example 6. FIG.
11 is a graph showing current-voltage characteristics of a resistance-change memory device according to Production Example 7. FIG.
12 is a graph showing current-voltage characteristics of a resistance-change memory device according to Production Example 8. FIG.
13 is a graph showing current-voltage characteristics of a resistance change memory device including a Ta active electrode according to the present invention.
FIG. 14 is a graph showing current-voltage characteristics of the resistance-change memory device including the W active electrode according to the present invention.
15 is a graph showing the density of a nitrogen-doped tantalum oxide layer with a nitrogen gas flow rate.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. Rather, the intention is not to limit the invention to the particular forms disclosed, but rather, the invention includes all modifications, equivalents and substitutions that are consistent with the spirit of the invention as defined by the claims.

It will be appreciated that when an element such as a layer, region or substrate is referred to as being present on another element "on," it may be directly on the other element or there may be an intermediate element in between .

Although the terms first, second, etc. may be used to describe various elements, components, regions, layers and / or regions, such elements, components, regions, layers and / And should not be limited by these terms.

A method of manufacturing a resistance-variable memory device according to an embodiment of the present invention will be described.

1 is a cross-sectional view illustrating a resistance change memory device according to an embodiment of the present invention.

Referring to FIG. 1, a substrate 100 is first prepared. The substrate 100 may be any material that can serve as a support substrate. For example, such a substrate 100 may be a silicon substrate. On the other hand, such a substrate may be omitted in some cases.

Then, an inert electrode is formed on the substrate. This inert electrode 200 may comprise an inert metal material. For example, the inert electrode 200 may comprise a Pt, Pt alloy, Pd or Pd alloy.

The inert electrode 200 may be formed by sputtering, RF sputtering, RF magnetron sputtering, pulsed laser deposition, chemical vapor deposition, plasma enhanced chemical vapor deposition, atomic layer deposition, or molecular beam epitaxy deposition. For example, a Pt electrode can be formed on a silicon substrate by sputtering.

Then, the resistance-variable layer 300 is formed on the inert electrode. In this resistance-variable layer 300, the resistance state is changed by the formation and disappearance of the metal filament due to voltage application. For example, the metal filament may be formed and destroyed by a redox reaction of a metal material, e.g., a metal ion, penetrated from the active electrode 400 to be described later.

The resistance-variable layer 300 may be a nitrogen-doped metal oxide layer. For example, the nitrogen-doped metal oxide layer may be a nitrogen-doped binary metal oxide layer. Such a binary metal oxide layer may comprise, for example, tantalum oxide, nickel oxide, niobium oxide, titanium oxide, zirconium oxide, hafnium oxide, cobalt oxide, molybdenum oxide, vanadium oxide, tungsten oxide, aluminum oxide or zinc oxide . For example, the resistance variable layer 300 may be a nitrogen doped tantalum oxide layer (N doped Ta ₂ O ₅ _- _x layer).

The resistance variable layer 300 may be formed by sputtering. For example, by performing sputtering in a mixed gas atmosphere of a nitrogen gas and an inert gas.

As a specific example, a tantalum oxide layer (N doped Ta ₂ O _5-x layer) can be formed by performing sputtering using a Ta ₂ O ₅ sputtering target under a mixed gas atmosphere of nitrogen gas and inert gas have.

Further, the inert gas at this time may be argon gas.

The nitrogen partial pressure of the mixed gas at this time is 16.67% to 37.50%. For example, the flow rate of the argon gas in the mixed gas composed of the nitrogen gas and the argon gas is preferably 10 sccm, and the nitrogen gas is preferably set in the range of 2 sccm to 6 sccm.

Accordingly, a porous thin film can be formed by flowing nitrogen gas together during the sputtering process, and the switching operation can be performed without a forming process.

If the partial pressure of the nitrogen gas is less than 16.67%, the reduction of the density of the thin film is small and the foaming process may be required. If the partial pressure of nitrogen gas exceeds 37.50%, N-vacancy bond is formed, nullity is generated and the density is increased, so that a forming process may be required.

In addition, especially when the partial pressure of nitrogen gas is 16.67% to 28.57%, the forming free property is better implemented. For example, the flow rate of the argon gas in the mixed gas consisting of nitrogen gas and argon gas is 10 sccm, and the nitrogen gas is 2 sccm to 6 sccm, the forming free characteristics of the manufactured resistance variable memory element are better implemented.

Further, the density of the nitrogen-doped tantalum oxide layer is not more than 8.0 g / cm < ³ >.

Then, the active electrode 400 is formed on the resistance-variable layer 300. Active electrode 400 may comprise a reactive metal material. For example, active electrode 400 may comprise Ta, Ta alloy, W, W alloy, Al, Al alloy, Ni, Ni alloy, Zr, Zr alloy, Ti or Ti alloy.

Such an active electrode may be formed in the form of a micro dot patter or a nano-plug. And may be formed in various known forms.

The active electrode 400 may be formed by sputtering, RF sputtering, RF magnetron sputtering, pulsed laser deposition, chemical vapor deposition, plasma enhanced chemical vapor deposition, atomic layer deposition, or molecular beam epitaxy deposition.

For example, a Ta electrode can be formed on the resistance variable layer by sputtering.

Production Example 1

Thereby fabricating a resistance change memory element according to an embodiment of the present invention.

That is, a Pt electrode / N ₂ doped Ta ₂ O ₅ _- _x layer / Ta electrode structure was fabricated as the structure of the inert electrode / resistance variable layer / active electrode.

First, a Pt target was deposited at a woking pressure of 3 mTorr, RF power: 30 W, and gas flowing Ar: 10 sccm using RF magnetron sputtering to form a Pt-inert electrode.

Then, Ta ₂ O ₅ by RF magnetron sputtering on Pt electrode layer target was deposited to a thickness of about 15 nm at a woking pressure of 3 mTorr, RF power: 30 W, gas flowing Ar: 10 sccm and N ₂ : 2 sccm to form an N ₂ doped Ta ₂ O _5-x layer.

Then, a Ta target was deposited on the N ₂ doped Ta ₂ O ₅ _- _x layer using RF magnetron sputtering under the conditions of a woking pressure of 3 mTorr, an RF power of 30 W and a gas flowing Ar of 10 sccm to form a microdot pattern dot pattern) was formed.

Production Example 2

And the flow rate of N ₂ gas was set to 4 sccm, a resistance change memory device according to an embodiment of the present invention was manufactured.

Production Example 3

And the flow rate of N ₂ gas was set to 6 sccm, a resistance change memory device according to an embodiment of the present invention was manufactured.

Production Example 4

And the N ₂ gas flow rate was set to 10 sccm, the same procedure as in Production Example 1 was conducted to fabricate a resistance change memory device according to an embodiment of the present invention.

Comparative Example 1

And the flow rate of N ₂ gas was set to 0 sccm, the same procedure as in Production Example 1 was conducted to fabricate a resistance change memory device according to an embodiment of the present invention.

Production Example 5

That is, a Pt electrode / N ₂ doped Ta ₂ O ₅ _- _x layer / W electrode structure was fabricated as the structure of the inert electrode / resistance variable layer / active electrode.

Then, Ta ₂ O ₅ by RF magnetron sputtering on Pt electrode layer N ₂ doped Ta ₂ O _5-x layer was formed at a thickness of about 2 nm under conditions of a working pressure of 3 mTorr, RF power: 30 W, gas flowing Ar: 10 sccm and N ₂ : 2 sccm.

Next, a W target was deposited on the N ₂ doped Ta ₂ O ₅ _- _x layer using RF magnetron sputtering at a woking pressure of 3 mTorr, RF power: 30 W, and gas flowing Ar: 10 sccm to form a nano-plug structure n-active structure of nano-plug structure. The diameter of the W electrode at this time is about 218 nm.

Production Example 6

Production Example 7

Production Example 8

And the flow rate of N ₂ gas was set to 10 sccm, a resistance change memory device according to an embodiment of the present invention was manufactured.

2 is a graph showing a change in characteristics of a resistance-change memory device according to Comparative Example 1 in accordance with the foaming phenomenon.

Referring to FIG. 2, it can be seen that the operation is performed only after the forming process is performed.

FIGS. 3 and 4 are graphs showing the current-voltage characteristics without the forming process, which is confirmed based on the resistance change memory device according to Production Example 1. FIG. 4 is a graph showing an enlargement of the negative bias reqion of FIG.

Referring to FIGS. 3 and 4, it can be seen that the switching operation is possible without the forming process.

5 is a graph showing current-voltage characteristics of a resistance-change memory device according to Production Example 1. FIG. 6 is a graph showing the current-voltage characteristics of the resistance-change memory device according to Production Example 2. FIG. 7 is a graph showing current-voltage characteristics of a resistance-change memory device according to Production Example 3. FIG.

Referring to FIGS. 5 to 7, it can be seen that the resistance change memory device according to Production Examples 1 to 3 can perform a switching operation without a forming process.

8 is a graph showing the current-voltage characteristics of the resistance-change memory device according to Production Example 4. FIG.

Referring to FIG. 8, it can be seen that the forming process is required for the resistance change memory device according to Production Example 4 in which the flow rate of nitrogen gas is 10 sccm (nitrogen partial pressure of 50%).

9 is a graph showing current-voltage characteristics of a resistance-change memory device according to Production Example 5. FIG. 10 is a graph showing current-voltage characteristics of a resistance-change memory device according to Production Example 6. FIG. 11 is a graph showing current-voltage characteristics of a resistance-change memory device according to Production Example 7. FIG.

Referring to FIGS. 9 to 11, it can be seen that the resistance change memory device according to Production Examples 5 to 7 can perform a switching operation without a forming process.

12 is a graph showing current-voltage characteristics of a resistance-change memory device according to Production Example 8. FIG.

Referring to FIG. 12, it can be seen that the forming process is required for the resistance change memory device according to Production Example 8 in which the flow rate of nitrogen gas is 10 sccm (nitrogen partial pressure 50%).

13 is a graph showing current-voltage characteristics of a resistance change memory device including a Ta active electrode according to the present invention. At this time, the Ta active electrode is in the form of a micro dot pattern.

Referring to FIG. 13, when the nitrogen gas flow rate is 2.0 sccm (nitrogen partial pressure 16.67%) and 4.0 sccm (nitrogen partial pressure 28.57%), the switching operation is possible without forming.

FIG. 14 is a graph showing current-voltage characteristics of the resistance-change memory device including the W active electrode according to the present invention. At this time, the W active electrode is in the form of a nano-plug.

Referring to FIG. 14, when the nitrogen gas flow rate is 2.0 sccm and 4.0 sccm, the switching operation is possible without the forming process.

2 to 14, the nitrogen gas flow rate is 2.0 sccm (nitrogen partial pressure 16.67%), 4.0 sccm (nitrogen partial pressure 28.57%), and the like, It can be seen that forming free is possible for 6.0 sccm (37.50% nitrogen partial pressure).

15 is a graph showing the density of a nitrogen-doped tantalum oxide layer with a nitrogen gas flow rate. The density was measured based on X-ray reflectometry (XRR).

Referring to FIG. 15, it can be seen that the density of the nitrogen-doped tantalum oxide layer formed as the N ₂ flow increases is decreased, and the density is increased again when the N ₂ flow is 10 sccm.

It should be noted that the embodiments of the present invention disclosed in the present specification and drawings are only illustrative of specific examples for the purpose of understanding and are not intended to limit the scope of the present invention. It will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention are possible in addition to the embodiments disclosed herein.

100: substrate 200: inert electrode
300: resistance variable layer 400: active electrode

Claims

Forming an inert electrode on the substrate;
Forming a nitrogen-doped metal oxide layer on the inert electrode; And
Forming an active electrode on the nitrogen doped metal oxide layer,
Wherein the step of forming the nitrogen-doped metal oxide layer is performed by performing sputtering in an atmosphere of a mixed gas of nitrogen gas and an inert gas.

The method according to claim 1,
Wherein the nitrogen-doped metal oxide layer is a nitrogen-doped binary metal oxide layer.

3. The method of claim 2,
Wherein the binary metal oxide layer comprises tantalum oxide, nickel oxide, niobium oxide, titanium oxide, zirconium oxide, hafnium oxide, cobalt oxide, molybdenum oxide, vanadium oxide, tungsten oxide, aluminum oxide or zinc oxide. Gt;

The method according to claim 1,
The step of forming the nitrogen-doped metal oxide layer comprises:
Wherein the nitrogen partial pressure of the mixed gas is 16.67% to 37.50%.

The method according to claim 1,
Wherein a switching operation is performed without a forming process.

The method according to claim 1,
Wherein the inert electrode comprises a Pt, Pt alloy, Pd or Pd alloy.

The method according to claim 1,
Wherein the active electrode comprises Ta, Ta alloy, W, W alloy, Al, Al alloy, Ni, Ni alloy, Zr, Zr alloy, Ti or Ti alloy.

The method according to claim 1,
Wherein the nitrogen-doped metal oxide layer is a resistance-variable layer having a state change due to formation and disappearance of a metal filament.

Board;
An inert electrode positioned on the substrate;
A resistance-variable layer disposed on the inert electrode and having a state change due to the formation and disappearance of the metal filament; And
And an active electrode located on the resistance-variable layer,
Wherein the resistance variable layer is a nitrogen-doped metal oxide layer.

10. The method of claim 9,
Wherein the nitrogen-doped metal oxide layer is formed by performing sputtering in an atmosphere of a mixed gas of nitrogen gas and an inert gas.

11. The method of claim 10,
Wherein the nitrogen partial pressure of the mixed gas is 16.67% to 37.50%.

10. The method of claim 9,
Wherein the nitrogen-doped metal oxide layer is a nitrogen-doped binary metal oxide layer.

13. The method of claim 12,
Wherein the binary metal oxide layer comprises tantalum oxide, nickel oxide, niobium oxide, titanium oxide, zirconium oxide, hafnium oxide, cobalt oxide, molybdenum oxide, vanadium oxide, tungsten oxide, aluminum oxide or zinc oxide. .

10. The method of claim 9,
And the density of the nitrogen-doped metal oxide layer is 8.0 g / cm < ³ > or less.

10. The method of claim 9,
Wherein a switching operation is possible without a forming process.