KR100969153B1 - Nonvolatile Resistance Change Memory Device - Google Patents

Abstract

A nonvolatile resistance change memory device having uniform switching characteristics is disclosed. The nonvolatile resistance change memory device is formed on a lower electrode and a lower electrode, and includes an insulating film having a contact hole, an insulating spacer formed on the sidewall of the contact hole, and an oxide resist film and an oxide resist film located in the contact hole where the insulating spacer is formed. It includes an upper electrode formed. Therefore, since the filament is formed locally by narrowly limiting the contact area between the oxide resistive film and the lower electrode, the conductive filament can be formed even at a low electric field, and the effective current density can be improved.

Switching, non-volatile memory, resistance change memory

Description

Nonvolatile Resistance Random Memory Device

The present invention relates to a nonvolatile memory device, and more particularly, to a nonvolatile resistance change memory device.

Non-volatile resistance change memory (ReRAM) devices, which have been studied since the 1960s, are metal insulator metal (MIM) structures using metal oxides. This small memory-switching feature translates into a conductive state.

The resistance change memory device has fast access time and low power consumption because the device can be operated at low voltage. In addition, it can be quickly read and written and has a simple memory device structure. The defects of the phase can be reduced, and the production cost can be lowered.

However, the resistance change memory device operates the device by inducing the formation and breaking of the filament (ON / OFF). In the conventional nonvolatile resistance change memory, the number of filaments formed per unit area in a predetermined electric field is not uniform and iterative. Different filaments can be formed during in-switching operation, making it difficult to apply giga / terabit memory devices.

An object of the present invention for solving the above problems is to provide a nonvolatile resistance change memory device having a uniform switching characteristics.

The present invention for achieving the above object is formed on the lower electrode, the lower electrode, an insulating film having a contact hole, an insulating spacer formed on the sidewall of the contact hole, an oxide resist film located in the contact hole formed with the insulating spacer; A nonvolatile resistance change memory device including an upper electrode formed on the oxide resistive film is provided.

 According to the present invention, since the filament is formed locally by restricting the contact area between the oxide resistive film and the lower electrode, the conductive filament can be formed even at a low electric field, and the effective current density can be improved.

In addition, by forming a small number of conductive filaments can form or disappear the same conductive filament in a repetitive switching operation it is possible to implement a stable switching characteristics.

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

1A to 1E are cross-sectional views illustrating a manufacturing process of a nonvolatile resistance change memory device according to an exemplary embodiment of the present invention, and are shown in a limited form in a unit cell of the memory device.

Referring to FIG. 1A, a lower electrode 110 is provided. The lower electrode 110 may be a Ti, Cu, Ni, Pt, Ru, Ir, or Al film.

Referring to FIG. 1B, an insulating film 120 having a contact hole 125 is formed on the lower electrode 110. The insulating layer 120 may be SiO ₂ . The contact hole 125 may have a width of about 50 nm or less.

The spacer insulating layer 130 is formed on the substrate on which the contact hole 125 is formed.

The spacer insulating layer 130 may be a silicon nitride layer, and may be conformally formed to have a uniform thickness by using atomic layer deposition (ALD).

Referring to FIG. 1C, the spacer insulating layer 130 is anisotropically etched to form an insulating spacer 131 on sidewalls of the contact hole 125. The lower electrode 110 may be exposed in the contact hole 125 where the insulating spacer 131 is formed. The exposed lower electrode 110 may have a width of about 1 nm to about 10 nm.

Referring to FIG. 1D, an oxide resist film 140 is formed in the contact hole 125 in which the insulating spacer 131 is formed. The oxide resistance layer 140 may be a transition metal oxide layer. Specifically, such as TiO _{2 -X} , Al ₂ O _{3 -X} , NiO _{1 -X} , Nb ₂ O _{5 -X} , Ta ₂ O _{5 -X} , ZrO _{2 -X} , Cu0 _X , Fe ₂ O _{3 -X} and the like Binary oxides can be prepared in a non-stoichiometric composition with oxygen vacancy and used as a resistance change material. As an example, X may be 0.01-0.5.

The thickness of the oxide resistance layer 140 may be smaller than the thickness of the insulating layer 120. Specifically, the thickness of the oxide resistance layer 140 may be 2nm to 50nm.

The oxide resist film 140 may be formed by physical vapor deposition (PVD), such as sputtering, pulsed laser deposition (PLD), thermal evaporation, and electron-beam evaporation. Deposition), Molecular Beam Epitaxy (MBE), or Chemical Vapor Deposition (CVD). In this case, after the oxide film is formed to completely fill the contact hole 125 where the insulating spacer 131 is formed, the oxide resist film 140 is formed by chemical mechanical polishing (CMP) and etchback. ) Can be formed.

Unlike this, the oxide resistance layer 140 may be formed by oxidizing the exposed lower electrode 110. In this case, the thickness of the oxide resistive film 140 may be easily adjusted, and the lower electrode 110 may be a Ti film, a Cu film, or a Ni film.

Referring to FIG. 1E, an upper electrode 150 is formed on the oxide resistance layer 140.

The upper electrode 150 may be a Pt, W, Mo, Ti, Cu, Ni, Ru, Ir, or Al film, and may use etching through deposition or lithography.

In the nonvolatile resistance change memory device formed as described above, the oxide resistance layer 140 is formed in the contact hole 125 where the insulating spacer 131 is formed, thereby reducing the contact area between the oxide resistance layer 140 and the lower electrode. It can be narrowly defined. In this case, since the effective current density increases in the oxide resistive film in local contact with the lower electrode, the conductive filament can be easily formed even at a low electric field.

In addition, due to the minute contact area between the oxide resistance layer 140 and the lower electrode 110, the number of conductive filaments to be formed may be limited to one, preferably one. Therefore, since the same conductive filaments are formed or disappeared in the repetitive switching operation, stable switching characteristics can be realized.

To this end, as described above, the width of the lower electrode 110 exposed in the contact hole 125 in which the insulating spacer 131 is formed may be about 10 nm or less.

2 is a graph showing the cumulative distribution of resistances. Specifically, the cumulative distribution of the resistance when the switching is repeatedly performed is shown.

Referring to FIG. 2, when an electric field is formed in the oxide resistive film, a filament is formed and a current flows. Such a region is referred to as a low resistance state (LRS). Cut off, the area to which the principle of Joule heating is applied is called a high resistance state (HRS).

In the conventional device, when the switching is repeatedly performed, the LRS and the HRS are distributed in a wide range, and it is difficult to obtain a specific resistance value that can be distinguished between the LRS and the HRS. However, in the memory device according to the present invention, since the LRS and the HRS are distributed in a narrow range even when the switching is repeatedly performed, the resistance value ΔR that can distinguish between the LRS and the HRS is very wide.

In an embodiment of the present invention, by forming a filament in a local region, resistance may not be widely distributed even after repeated switching, and may be uniformly formed, and exhibit stable switching characteristics.

Although described above with reference to examples, those skilled in the art can understand that various modifications and changes can be made to the present invention without departing from the spirit and scope of the present invention as set forth in the claims below. There will be.

1A to 1E are cross-sectional views illustrating a manufacturing process of a nonvolatile resistance change memory device according to an exemplary embodiment of the present invention.

2 is a graph showing the cumulative distribution of resistances.

<Explanation of symbols for main parts of the drawings>

110: lower electrode 120: insulating film

125: contact hole 130: spacer insulating film

131: insulating spacer 140: oxide resistive film

150: upper electrode

Claims (7)

delete delete delete delete Forming an insulating film on the lower electrode; Forming a contact hole in the insulating layer to expose a portion of the lower electrode; Forming a spacer insulating film on the insulating film on which the contact hole is formed; Etching the spacer insulating layer to form an insulating spacer exposing a portion of the lower electrode on the sidewall of the contact hole; Oxidizing the lower electrode exposed by the insulating spacer to form an oxide resistive film; And Forming an upper electrode on the oxide resistive film. The method of claim 5, The width of the lower electrode exposed by the insulating spacer is a manufacturing method of the resistance change memory device 1nm to 10nm. The method of claim 5, And the lower electrode is any one selected from the group consisting of Ti, Cu, and Ni.

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