KR102081020B1 - Selector and method of fabricating the same - Google Patents

Abstract

The present invention relates to a selection device using an anti-oxidation layer for preventing oxidation of a switch layer. According to an embodiment of the present invention, the selection device comprises: a first electrode; a switch layer formed on the first electrode, and including NbO_2; a first anti-oxidation layer formed on the switch layer, and including NbOx (0 <x < 2); a second electrode formed on the first anti-oxidation layer; and a first oxidation layer having at least one of oxygen introduced from the outside, non-grid oxygen in the switch layer, and second non-grid oxygen present in an initial anti-oxidation layer to have a reaction with an upper portion of the first anti-oxidation layer to be formed between the first anti-oxidation layer and the second electrode, and including NbO_y (0 < y < 2).

Description

Selecting device and manufacturing method thereof {Selector and method of fabricating the same}

The present invention relates to a nonvolatile resistance change memory, and more particularly, to a selection device and a method of manufacturing the same.

Next-generation memories have emerged as new nonvolatile memory devices to replace flash memory, which is a conventional nonvolatile memory device. As one of the next generation memories, resistance change memory (RRAM) has advantages such as low production cost, simple process, and fast read / write speed. In addition, when a cross-point structure is used, a large-capacity memory device can be implemented, and research on this has been actively conducted in recent years.

The crosspoint structure has a structure in which a word line and a bit line cross each other. In the crosspoint structure, there is a problem in that operation errors such as soft programming of unselected memory cells due to leakage currents occurring through adjacent memory cells must be reduced. One solution is to couple diodes to memory cells. However, when the diode is applied, it cannot be used for the bipolar resistance change memory device, and the transistor has a problem in that the memory integration is not improved.

Recently, the solution proposed is to use a selection device having a threshold switch characteristic, and a material having the threshold switch characteristic is a metal-insulator transition (MIT) material. The metal-insulator transition material exhibits the properties of the metal above a certain temperature and below that of the insulator. In addition, it is electrically symmetrical to the positive and negative external electric fields, so it can be applied to unipolar resistive change memory devices as well as bipolar resistive change memory devices, and low turn-off current flows at low external electric fields. At high external electric fields, high turn-on currents have good nonlinear characteristics.

In order for the metal-insulator transition material to exhibit the switch characteristic, a forming process for forming a conductive path is required. Additional power must be consumed for the forming process. In addition, surface oxidation of the metal-insulator transition material may occur by an unintended electrochemical reaction during the forming process, and the oxide formed may inhibit the operation of the memory device.

The problem to be solved by the present invention is to omit the forming process that causes the oxidation of the metal-insulator transition material to reduce the function of the selection device to improve the power consumption efficiency and to drive the resistance change memory with high accuracy and reliability It is to provide a selection device.

Another object of the present invention is to provide a method for manufacturing a selection device having the above advantages.

In order to solve the above problems, the selection device according to the present invention is formed on the first electrode, the first electrode, a switch layer containing NbO ₂ , and is formed on the switch layer, and NbO _x (0 < x <2), a second electrode formed on the first antioxidant layer and oxygen introduced from outside, a first non-lattice oxygen inside the switch layer, and an initial first antioxidant layer At least one kind of oxygen of the second non-lattice oxygen existing therein is formed between the first antioxidant layer and the second electrode by reacting with an upper portion of the initial first antioxidant layer, and NbO _y (0 < y <2). In one embodiment, the first oxide layer can have a larger Nb ⁴⁺ XPS peak than the first antioxidant layer, and in another embodiment, the switch layer, the first antioxidant layer and the first oxidation The sum of the thicknesses of the layers may be between 15 nm and 35 nm.

In another embodiment, the selection device may include a second anti-oxidation layer formed on the second electrode and oxygen introduced from the outside, inside the first non-lattice oxygen inside the switch layer and the initial second anti-oxidation layer. At least one kind of oxygen of the third non-lattice oxygen is reacted with the lower portion of the initial second antioxidant layer and is formed between the second antioxidant layer and the second electrode, and NbO _y (0 <y <2 May further comprise a second oxide layer, and in another embodiment, the second oxide layer may have a larger Nb ⁴⁺ XPS peak than the second antioxidant layer, optionally, The sum of the thicknesses of the first antioxidant layer, the first oxide layer, the switch layer, the second antioxidant layer and the second oxide layer may be 15 nm to 35 nm.

In addition, in the selection device according to the embodiment of the present invention and the selection device according to another embodiment, the switch layer may have a rutile crystalline phase.

In another embodiment, a method of manufacturing a selection device may include forming a first electrode, forming a switch layer including NbO ₂ on the first electrode, and forming NbO _z (0) on the switch layer. <z <2), forming an initial first antioxidant layer, forming a second electrode on the initial first antioxidant layer, and annealing the switch layer and the initial first antioxidant layer. And a first oxide layer comprising Nb-containing thin film formed by changing the switch layer and the initial first anti-oxidation layer from an amorphous state into a crystalline state and NbO _y (where 0 <y <2) on the Nb-containing thin film. And, in another embodiment, the initial first anti-oxidation layer may be deposited under a condition of oxygen partial pressure (P _{O 2} ) of 0% by direct current magnetron sputtering, optionally , The boss The location layer may be deposited at a condition of 2% to 5% oxygen partial pressure (P _{O 2} ) by direct current magnetron sputtering.

In another embodiment, at least any one of oxygen introduced from the outside of the Nb-containing thin film, first non-lattice oxygen inside the switch layer, and second non-lattice oxygen existing inside the initial first antioxidant layer. One type of oxygen may react with the top of the initial first antioxidant layer to form a first oxide layer.

In another embodiment, the selection device may further comprise forming an initial second antioxidant layer comprising NbO _z (where 0 <z <2) between the first electrode and the switch layer, In one embodiment, at least one kind of oxygen introduced from the outside on the Nb-containing thin film, the first non-lattice oxygen inside the switch layer and the second non-lattice oxygen existing inside the initial first antioxidant layer Of oxygen reacts with an upper portion of the initial first antioxidant layer to form a first oxide layer, oxygen introduced from outside into the lower portion of the Nb-containing thin film, first non-lattice oxygen inside the switch layer, and the initial agent At least one kind of oxygen of the third non-lattice oxygen existing in the second antioxidant layer may react with the lower portion of the initial second antioxidant layer to form a second oxide layer.

In one embodiment, forming the initial first antioxidant layer may be performed by an in-situ process, and in another embodiment, the initial first antioxidant layer is formed to a thickness of 10 nm to 15 nm. Optionally, the annealing may be performed at a temperature range of 650 ° C to 750 ° C.

According to an embodiment of the present invention, forming an anti-oxidation layer to prevent oxidation of the MIT material layer between an electrode and a material layer having a metal-insulator transition (MIT) characteristic, and forming by performing annealing A forming-free selection device in which a forming process is omitted may be provided.

In addition, by forming the anti-oxidation layer between the switch layer and the first electrode and the second electrode to prevent the oxidation reaction occurring in the first electrode and the second electrode and the switch layer to prevent unnecessary power consumption, more reliable And an accurate forming preselection device.

1 is a cross-sectional view showing the configuration of a multi-layer selection device according to an embodiment of the present invention, Figure 2 is a cross-sectional view of a multi-layer selection device according to another embodiment of the present invention.
3 is a flowchart illustrating a method of manufacturing a multilayer selection device according to an embodiment of the present invention.
4A and 4B are scanning electron microscope (SEM) images of cross-sectional structures before annealing and after annealing, respectively, of the multilayer selection device shown in FIG. 1, and FIGS. 4C and 4D are respectively shown in FIG. Scanning electron microscope image of the cross-sectional structure before annealing and after annealing of the selected multilayer selection device.
5A is an XPS analysis result of the first oxide layer measured after annealing of the multilayer selection device illustrated in FIG. 1, and FIG. 5B is an XPS analysis of the Nb-containing thin film measured after annealing of the multilayer selection device illustrated in FIG. 1. The result is.
6 shows XPS analysis results of the surface, middle, and bottom of the multilayer selection device after annealing.
FIG. 7A is a graph illustrating an IV measurement result of a multilayer selection device after annealing, and FIG. 7B is a graph illustrating an IV measurement result of a multilayer selection device after annealing.

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

The embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art, and the following examples can be modified in many different forms, and the scope of the present invention is as follows. It is not limited to an Example. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the inventive concept to those skilled in the art.

In addition, the thickness or size of each layer in the drawings are exaggerated for convenience and clarity, the same reference numerals in the drawings refer to the same elements. As used herein, the term "and / or" includes any and all combinations of one or more of the listed items.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" may include the plural forms as well, unless the context clearly indicates otherwise. Also, as used herein, "comprise" and / or "comprising" specify the shapes, numbers, steps, actions, members, elements and / or presence of these groups mentioned. It is not intended to exclude the presence or addition of one or more other shapes, numbers, operations, members, elements and / or groups.

Although the terms first, second, etc. are used herein to describe various members, parts, regions, and / or parts, these members, parts, regions, and / or parts should not be limited by these terms. Is self-explanatory. These terms are only used to distinguish one member, part, region or portion from another region or portion. Thus, the first member, part, region, or portion, which will be described below, may refer to the second member, component, region, or portion without departing from the teachings of the present invention.

In addition, when a layer is formed or disposed on another layer, an intermediate layer may be formed or disposed between these layers. Similarly, there may be an intermediate material between these materials even if one material is said to be adjacent to another material. Conversely, when a layer or material is said to be formed or disposed "directly" or "directly" on another layer or material, or when it is said to be "directly" or "directly" adjacent or in contact with another layer or material, these materials or layers It should be understood that there are no intermediate materials or layers in between.

Embodiments of the present invention will now be described with reference to the drawings, which schematically illustrate ideal embodiments of the present invention. In the drawings, for example, the size and shape of the members may be exaggerated for convenience and clarity of description, and in actual implementation, variations of the illustrated shape may be expected. Accordingly, embodiments of the invention should not be construed as limited to the specific shapes of the regions shown herein.

1 is a cross-sectional view showing the configuration of a multi-layer selection device 100 according to an embodiment of the present invention, Figure 2 is a cross-sectional view of a multi-layer selection device 200 according to another embodiment of the present invention.

Referring to FIG. 1, in an embodiment, the multilayer selection device 100 may include a first electrode EL1, a first antioxidant layer OPL1, a switch layer SWL, and a first oxide layer OL1. Can be. Although not shown, the first electrode EL1 may be formed on a substrate (not shown), and the second electrode EL2 may be formed on the first antioxidant layer OPL1. The substrate may include a material such as silicon (Si) or gallium arsenide (GaAs), but is not limited to the above materials, and may include a substrate made of a ceramic, polymer, or metal material capable of semiconductor integrated circuit processing. . In addition, the first electrode EL1 and the second electrode EL2 may include a conductive metal such as aluminum (Al), zinc (Zn), magnesium (Mg), platinum (Pt), or titanium nitride (TiN). In the present invention, since the first anti-oxidation layer OPL1 and the second anti-oxidation layer OPL2 prevent oxidation of the switch layer SWL, the reactivity of the electrodes with oxygen does not matter. The first electrode EL1 and the second electrode EL2 are sputtered, RF sputtered, RF magnetron sputtering, pulsed laser deposition (PLD), chemical vapor deposition (CVD), and chemical vapor deposition (CVD). It may be formed using Plasma Enhanced Chemical Vapor Deposition (PECVD), Atomic Layer Deposition (ALD) or Molecular Beam Epitaxy (MBE).

The switch layer SWL is formed on the first electrode and may include NbO ₂ . In one embodiment, when a voltage of a predetermined magnitude or more is applied across the switch layer SWL, a high current may flow in the switch layer SWL, and the switch layer SWL may change from a high resistance state to a low resistance state. Can be. This is because local oxygen vacancy is formed inside the switch layer SWL to form a conductive filament made of the oxygen vacancy, and current flows through the conductive filament. The NbO ₂ may exhibit semiconductor characteristics at a low temperature of 1080 K or less, and may have a metallic property at a high temperature of 1080 K or more. Such properties are referred to as switch characteristics or threshold characteristics, and the switch characteristics allow NbO ₂ to act as a selection device in a resistance change memory.

In addition, the NbO ₂ may have a distorted rutile phase at low temperatures and a rutile phase at high temperatures. When the NbO ₂ is heat-treated, the existing amorphous NbO ₂ may be crystallized and changed into the rutile phase to have the switch characteristics. Wherein the switching characteristics of the NbO ₂ is forming (forming) formed by the process or by heat treatment when said NbO ₂ crystallized can be formed and, NbO ₂ by performing the heat treatment, forming omitting the forming process, - pre-selection device Can be

In another embodiment, the switch layer SWL may be NbO _x (about 1.8 <x <2.2). When x is less than or equal to the lower threshold, the composition of NbO having a high conductivity is high, making it difficult to show sufficient switch characteristics such that the switch layer SWL acts as a selection device. As the composition of Nb ₂ O ₅ , which is a dielectric material, increases, it is difficult for the switch layer (SWL) to function as a selection device. The x may be greater than or less than the atomic ratio of oxygen satisfying the stoichiometric ratio or satisfying the stoichiometric ratio, and is not limited to a specific value.

The first anti-oxidation layer OPL1 is formed on the switch layer SWL and may include NbO _x (where 0 <x <2). In an embodiment, the first anti-oxidation layer OPL1 has an oxygen composition that is less than that of the switch layer SWL, and may be oxidized by reacting with oxygen to prevent oxidation of the switch layer SWL. The oxygen may be introduced by a reaction with an external electrode or an electrode, may include non-lattice oxygen present in the switch layer SWL, or may be formed on the first layer of the first antioxidant layer IOPL1 before the oxidation reaction. ) May contain non-lattice oxygen that was present inside. The non-lattice oxygen may be, for example, an oxygen atom not completely bonded to the Nb atom inside the Nb oxide. In addition, the first antioxidant layer OPL1 may include a metal, a nonmetal, or a combination thereof that is highly reactive with oxygen.

The first oxide layer OL1 is at least one of oxygen introduced from the outside, first non-lattice oxygen inside the switch layer SWL, and second non-lattice oxygen existing inside the initial first antioxidant layer IOPL1. Is formed between the first antioxidant layer OPL1 and the second electrode EL2 by reacting with an upper portion of the initial first antioxidant layer IOPL1, and may include NbO _y (where 0 <y <2). Can be. Oxidation of the switch layer SWL may be prevented by oxidizing the first anti-oxidation layer OPL1, and thus, it is possible to implement a selection device having high switch characteristics. In another embodiment, the first oxide layer OL1 may have a larger Nb ⁴⁺ XPS peak than the first antioxidant layer OPL1. As a result, the oxidation of the switch layer SWL is prevented by oxidizing the first antioxidant layer OPL1, and it can be seen that the first oxide layer OL1 is formed.

In another embodiment, the sum of the thicknesses of the switch layer SWL, the first antioxidant layer OPL1 and the first oxide layer OL1 of the multilayer selection device 100 may be 15 nm to 35 nm. When the sum of the thicknesses is less than 15 nm, it is difficult to form the first antioxidant layer OPL1 having a sufficient thickness to prevent oxidation of the switch layer SWL. In addition, when the sum of the thickness exceeds 35 nm, the size of the crystal formed by crystallization is excessively large, it may be difficult to form the conductive path due to the crystallization.

Referring to FIG. 2, the multilayer selection device 200 according to another embodiment may include a first electrode EL1, a switch layer SWL, a first antioxidant layer OPL1, a first oxide layer OL1, and a second electrode. The anti-oxidation layer OPL2, the second oxide layer OL2, and the second electrode EL2 may be included. For the description of the first electrode EL1, the switch layer SWL, the first anti-oxidation layer OPL1, the first oxide layer OL1, and the second electrode EL2, refer to the foregoing disclosure unless there is a contradiction. can do.

The second antioxidant layer OPL2 may be formed between the first electrode EL1 and the switch layer SWL. In an embodiment, the second anti-oxidation layer OPL2 has an oxygen composition that is less than that of the switch layer SWL, and may react with oxygen to prevent oxidation of the switch layer SWL. The oxygen is non-lattice oxygen introduced by the reaction with the outside or the electrode, inside the switch layer (SWL) or inside the initial second antioxidant layer (IOPL2) formed on the switch layer (SWL) prior to the oxidation reaction It may include, and may refer to the description of the first antioxidant layer OPL1 described above in a non-consistent range.

The second oxide layer OL2 is at least one of oxygen introduced from the outside, first non-lattice oxygen inside the switch layer SWL, and third non-lattice oxygen remaining inside the initial second anti-oxidation layer IOPL2. Oxygen is formed between the second antioxidant layer OPL2 and the second electrode EL2 by reacting with the lower portion of the initial second antioxidant layer IOPL2, and may include NbO _x (where 0 <x <2). Can be. For a description of the second oxide layer OL2, reference may be made to the disclosure for the first oxide layer described above. In another embodiment, the switch layer SWL, the first anti-oxidation layer OPL1, the first oxide layer OL1, the second anti-oxidation layer OPL2, and the second oxide layer of the multilayer selection element 200 may also be used. The sum of the thicknesses of the OL2 and the second electrode EL2 may be 15 nm to 35 nm. The description of the sum of the thicknesses refers to the description of the multi-layer selection element 100 described above unless there is a contradiction.

 3 is a flowchart illustrating a method of manufacturing a multilayer selection device according to an embodiment of the present invention. However, this is only a preferred embodiment for achieving the object of the present invention, of course, some steps may be added or deleted as necessary.

Referring to FIG. 3, a first electrode EL1 is formed on a substrate (S100). Thereafter, a switch layer SWL including NbO ₂ is formed on the first electrode EL1 (S200). In one embodiment, in the method of manufacturing the multilayer selection device 200, after formation of the first electrode EL1 (S100), between NbO _z (0 <0) between the first electrode EL1 and the switch layer SWL. A step S100a may be further formed to form an initial second antioxidant layer IOPL2 including z <2). Forming an initial first anti-oxidation layer (IOPL1) containing NbO _x (0 <x <2) on the switch layer to be described later with respect to the formation conditions of the initial second anti-oxidation layer (IOPL2) (S300) See disclosure at. In the case of the multilayer selection device 200, an additional oxidation prevention layer may be additionally formed on the first electrode to effectively prevent oxidation of the switch layer SWL from both electrode directions. Accordingly, both electrodes of the multilayer selection device 200 may be made of a metal, a nonmetal, and a combination thereof, and may not be limited by the size of oxygen and reactivity. In addition, by effectively preventing the oxidation of the switch layer (SWL), which serves as a selection device, it is possible to implement a highly reliable and accurate forming-free selection device.

In another embodiment, the switch layer (SWL) is 2% to 5% oxygen partial pressure (P _O2 ), preferably 2% to 3% oxygen partial pressure (P _O2 ) by direct current magnetron sputtering. May be deposited under conditions. If the partial pressure of oxygen (P _O2 ) is lower than 2%, the composition of NbO may be increased to reduce the switch characteristics, and if the oxygen partial pressure (P _O2 ) is more than 3%, the composition of Nb ₂ O ₅ may be Can prevail. In one embodiment, RF sputtering may be used and deposited at higher oxygen partial pressure conditions, for example, at 10% oxygen partial pressure (P _{O 2} ).

Referring back to FIG. 3, an initial first antioxidant layer IOPL1 including NbO _z (where 0 <z <2) is formed on the switch layer (S300). In one embodiment, the initial first anti-oxidation layer (IOPL1) may be deposited under a condition of oxygen partial pressure (P _O2 ) 0% by direct current magnetron sputtering (DS magnetron sputtering). In another embodiment, the initial first anti-oxidation layer IOPL1 may be formed at 0% to 1% oxygen partial pressure (PO ₂ ). External oxygen may be introduced during the deposition of the thin film, thereby increasing the oxygen composition of the first antioxidant layer. In another embodiment, the step of forming the initial first anti-oxidation layer (IOPL1) may be performed by an in-situ process, when the in-situ process is a low oxygen composition ratio by blocking the inflow of oxygen from the outside The branch may form the initial first antioxidant layer IOPL1.

In one embodiment, the initial first antioxidant layer IOPL1 may be formed to a thickness of 10 nm to 15 nm. If the thickness is less than 10 nm, it is not sufficient to prevent the oxidation of the switch layer SWL, so that the anti-oxidation effect of the switch layer SWL cannot be obtained. If the thickness exceeds 15 nm, the initial first oxidation prevention is prevented. The first oxide layer OL1 and the first anti-oxidation layer OPL1 formed by oxidizing the upper portion of the layer IOPL1 are high in the total selection elements, and the ratio of the switch layer SWL is small, thereby providing sufficient switch characteristics. Difficult to get.

After the switch layer SWL and the initial first antioxidant layer IOPL1 are formed, the switch layer SWL and the initial first antioxidant layer IOPL1 thin film are annealed to form the switch layer and the initial first antioxidant layer ( The first oxide layer including NbO _y (0 <y <2) may be formed on the Nb-containing thin film NTF and the Nb-containing thin film NTF formed by changing IOPL1 from an amorphous state to a crystalline state. (S500). In one embodiment, the annealing may be performed at a temperature range of 650 ℃ to 750 ℃. Immediately after the NbO _x (0 <x <2) thin film is deposited, it may have an amorphous state, and in the case of NbO ₂ , it may have a distorted rutile phase at room temperature. When the annealing temperature is less than 650 ℃, the crystallization by the annealing is not sufficiently made to form an additional forming process to obtain the crystalline state, when the annealing temperature exceeds 750 ℃, the switch layer ( The conductive path may be broken while distortion of the crystal structure of the SWL) and the initial first antioxidant layer IOPL1 occurs. The Nb-containing thin film NTF of the multilayer selection device 100 may include a first antioxidant layer OPL1 and a switch layer SWL, and the Nb-containing thin film NTF of the multilayer selection device 200 according to another embodiment. ) May include a first antioxidant layer OPL1, a switch layer SWL, and a second antioxidant layer OPL2.

In another embodiment, oxygen introduced from outside the Nb-containing thin film NTF, the first non-lattice oxygen inside the switch layer SWL, and the second non-lattice existing inside the initial first antioxidant layer IOPL1. At least one kind of oxygen may be reacted with the upper portion of the initial first antioxidant layer IOPL1 to form the first oxide layer OL1. The oxygen composition ratio of the first oxide layer OL1 may be greater than or equal to the oxygen composition ratio of the Nb-containing thin film NTF. In another embodiment, the Nb-containing thin film NTF may be an NbO ₂ thin film. As the first oxide layer OL1 is formed, oxidation of the remaining portion of the Nb-containing thin film NTF except the first oxide layer OL1 at the upper portion may be prevented. Accordingly, the remaining portion may have switching characteristics by maintaining a uniform crystalline state.

4A and 4B are scanning electron microscope (SEM) images of a cross-sectional structure before annealing and after annealing, respectively, of the multilayer selection device 100 shown in FIG. 1, and FIGS. 4C and 4D are respectively shown in FIG. A scanning electron microscope image of the cross-sectional structure before and after annealing of the multilayer selection device 200 shown in FIG. 2 is shown. The first electrode EL1 of the multilayer selection devices 100 and 200 is titanium nitride TiN, the second electrode EL2 is platinum Pt, the initial first anti-oxidation layer IOPL1 and the initial second oxidation. The prevention layer IOPL2 may be an Nb thin film, and the switch layer SWL may be an NbO _x (0 <x <2) thin film.

Referring to FIGS. 4A and 4B, it can be seen that the Nb thin film and the NbO _x thin film are divided with clear boundaries before annealing of the multilayer selection device 100. In contrast, it can be seen that after annealing of the multilayer selection device 100, the boundary between the Nb thin film and the NbO _x thin film disappears and a Nb-containing thin film NTF exists in a mixed phase. In another embodiment, the first oxide layer OL1 having an oxygen composition higher than that of the initial first antioxidant layer IOPL1 may be formed on the Nb-containing thin film NTF. In addition, it may be confirmed that the thickness of the Nb-containing thin film NTF is smaller than the sum of the thicknesses of the Nb thin film and the NbO ₂ thin film. This is a result of the crystal structure of the Nb thin film and the NbO ₂ thin film reconstituted in the annealing process, and the distance between atoms becomes uniform.

4C and 4D, it can be seen that the boundary of the triple layer structure of the Nb thin film and the NbO _x thin films is clear before the heat treatment of the multilayer selection device 200, and after the annealing of the multilayer selection device 200. It can be seen that the boundary between the Nb thin film and the NbO _x thin film disappears and an Nb-containing single film existing in a mixed phase is formed. As described above, the thickness of the Nb-containing thin film NTF is reduced, and in another embodiment, the first oxide having a higher oxygen composition than the oxygen composition of the initial first antioxidant layer IOPL1 is formed on top of the Nb-containing thin film NTF. A layer may be formed, and a second oxide layer having an oxygen composition higher than that of the initial second oxidation prevention layer IOPL2 may be formed below.

In another embodiment, the Nb-containing thin film NTF may include a first antioxidant layer OPL1 and a switch layer SWL, and the Nb-containing thin film NTF of the multilayer selection element 200 may include a first antioxidant layer. (OPL1), the switch layer (SWL) and the second antioxidant layer (OPL2) may be included. In one embodiment, each of the layers inside the Nb-containing thin film (NTF) may be observed as a plurality of thin films with clear boundaries, and may have boundaries that are unclear due to the diffusion of atoms by heat treatment. In addition, crystals may be rearranged during annealing so that each of the layers may form or integrate a single film of an Nb-containing thin film (NTF).

5A is an XPS analysis result of the first oxide layer OL1 measured after annealing of the multilayer selection device 100 illustrated in FIG. 1, and FIG. 5B is after annealing of the multilayer selection device 100 illustrated in FIG. 1. It is the result of XPS analysis about the measured Nb containing thin film. In the multilayer selection device 100, the first electrode EL1 may be titanium nitride (TiN), the second electrode EL2 may be platinum (Pt), and the Nb-containing thin film NTF may be formed of a first antioxidant layer ( OPL1) and a first oxide layer OL1. As described above, annealing the first first anti-oxidation layer IOPL1 and the switch layer SWL forms an Nb-containing thin film NTF, and an oxide layer OL1 is formed on the Nb-containing thin film NTF. The Nb-containing thin film NTF may be formed below. In one embodiment, it can be seen that the Nb-containing first oxide layer OL1 has a high ratio of Nb ²⁺ , and in the case of Nb-containing thin film NTF, the Nb ⁴⁺ ratio is high. According to the experimental example, the composition of NbO is high in the first oxide layer OL1, and the composition of NbO ₂ is high in the Nb-containing thin film NTF. Accordingly, oxidation of the switch layer SWL in the Nb-containing thin film NTF may be prevented to maintain switch characteristics.

6 is an XPS analysis result of the surface portion, the middle portion, and the bottom portion of the multilayer selection device 200 after annealing. Graph a is the XPS analysis result of the surface portion, graph b is the XPS analysis result of the middle portion, graph c is the XPS analysis result of the bottom portion, graph d is the XPS analysis result comparison graph of the surface portion, the middle portion, and the bottom portion to be. The thickness of the surface portion, the middle portion, and the bottom portion may vary, the graph is only a non-limiting experimental example, various embodiments are not limited to specific experimental conditions. In example embodiments, the surface portion may be a first oxide layer OL1, the middle portion may be an Nb-containing thin film NTF, and the bottom portion may be a second oxide layer OL2.

Referring to FIG. 6, after the annealing, the binding state of Nb ⁵⁺ does not exist in the multilayer selection device 200, and the Nb ⁴⁺ bonding state is predominant in the surface portion, and from this, NbO ₂ It can be seen that the phase is most present in the surface portion. In the middle part, it can be seen that Nb ²⁺ and Nb ⁴⁺ are in a mixed state, which means that the NbO ₂ and NbO phases are mixed in the Nb-containing single layer. In addition, it can be seen that the Nb ²⁺ bonding state is predominant in the bottom part, from which the most NbO phase is present.

In another embodiment, the most NbO phase may be present in the surface portion or the most NbO ₂ phase may be present in the bottom portion. In addition, in the XPS analysis result of the intermediate part, the ratio of the Nb ²⁺ binding state or the Nb ⁴⁺ binding state may vary, and at least some of the intermediate parts may exist in an amorphous state.

FIG. 7A is a graph illustrating I-V measurement results of the multilayer selection device 100 after annealing, and FIG. 7B is a graph illustrating I-V measurement results of the multilayer selection device 200 after annealing. Between the positive electrodes of the multilayer selection elements 100, 200 according to the embodiment of the present invention, a voltage sweep starting at 0 V to increase the voltage signal of negative polarity and again increase the voltage signal of positive polarity. It is the measurement result obtained by applying a signal.

7A and 7B, the multi-layer selection device 100 after annealing and the multi-layer selection device 200 after annealing show stable switch characteristics without a separate forming process. It can be seen that it can work as an element. In step ①, when a voltage greater than the negative threshold voltage (V _th ) is applied to both ends of the selection device, it can be seen that the magnitude of the current rapidly increases to have a metallic state. Subsequently, in step ②, the insulator state is maintained, and when a voltage greater than the positive threshold voltage is applied in step ③, the current is rapidly increased by changing to a metallic state. In (4), when the voltage is smaller than the positive threshold voltage again, the magnitude of the current decreases rapidly and the transition to the insulator state can be seen. Accordingly, it can be seen that it is possible to implement an accurate and reliable forming-preselection device by reducing unnecessary power consumption by eliminating the forming process and preventing the generation of unnecessary oxides during the annealing process for eliminating the forming process. .

100, 200: multilayer selection element
EL1: first electrode
EL2: second electrode
SWL: switch layer
OPL1: first antioxidant layer
OPL2: second antioxidant layer
OL1: first oxide layer
OL2: second oxide layer
IOPL1: Initial First Antioxidant Layer
IOPL2: initial second antioxidant layer
NTF: Nb-containing thin film

Claims (20)

A memory device comprising a memory cell and a selection device coupled to the memory cell to select the memory cell.
The selection element,
A first electrode;
A switch layer formed on the first electrode and comprising NbO ₂ ;
A first anti-oxidation layer formed on the switch layer and comprising NbO _x (where 0 <x <2);
A second electrode formed on the first antioxidant layer; And
It is formed between the first antioxidant layer and the second electrode, and reacts with the non-lattice oxygen of the initial first antioxidant layer or the switch layer to prevent oxidation of the switch layer, NbO _y (0 <y <2 And a first oxide layer comprising
The oxygen composition ratio of the first oxide layer is higher than the oxygen composition ratio of the first oxidation layer. The method of claim 1,
And the first oxide layer has a larger Nb ⁴⁺ XPS peak than the first antioxidant layer. The method of claim 1,
The sum of the thicknesses of the switch layer, the first antioxidant layer and the first oxide layer is 15 nm to 35 nm. A first electrode;
A switch layer formed on the first electrode and comprising NbO ₂ ;
A first anti-oxidation layer formed on the switch layer and comprising NbO _x (where 0 <x <2);
A first oxide layer formed on the first antioxidant layer and comprising NbO _y (where 0 <y <2);
A second electrode formed on the first oxide layer;
A second antioxidant layer formed between the first electrode and the switch layer and comprising NbO _x (where 0 <x <2); And
And a second oxide layer formed between the second antioxidant layer and the first electrode, the second oxide layer comprising NbO _y (where 0 <y <2). The method of claim 4, wherein
And the second oxide layer has a larger Nb ⁴⁺ XPS peak than the second antioxidant layer. The method of claim 5, wherein
And a sum of the thicknesses of the first antioxidant layer, the first oxide layer, the switch layer, the second antioxidant layer, and the second oxide layer is 15 nm to 35 nm. The method of claim 4, wherein
And the switch layer has a rutile crystalline phase. A method of manufacturing a memory device comprising a memory cell and a selection device coupled to the memory cell to select the memory cell.
Forming the selection device,
Forming a first electrode;
Forming a switch layer comprising NbO ₂ on the first electrode;
Forming an initial first antioxidant layer comprising NbO _z (where 0 <z <2) on the switch layer;
Forming a second electrode on the initial first antioxidant layer; And
Annealing the switch layer and the initial first antioxidant layer so that the Nb-containing thin film and the Nb-containing thin film formed from the amorphous state to the crystalline state are formed on top of the NbO _y (0 < forming a first oxide layer comprising y <2), and
Non-lattice oxygen of the initial first antioxidant layer or the switch layer reacts with the top of the initial first antioxidant layer to prevent oxidation of the switch layer,
The oxygen composition ratio of the first oxide layer is higher than the oxygen composition ratio of the first oxidation layer. The method of claim 8,
The initial first anti-oxidation layer is deposited under a condition of oxygen partial pressure (P _{O 2} ) 0% by direct current magnetron sputtering (DS magnetron sputtering). The method of claim 8,
The switch layer is a method of manufacturing a memory device is deposited under the conditions of oxygen partial pressure (P _O2 ) 2% to 5% by direct current magnetron sputtering (DS magnetron sputtering). The method of claim 8
At least one kind of oxygen introduced from the outside on the Nb-containing thin film, first non-lattice oxygen in the switch layer, and second non-lattice oxygen existing in the initial first antioxidant layer is the initial phase. A method of manufacturing a memory device, which reacts with an upper portion of a first antioxidant layer to form a first oxide layer. The method of claim 8
And forming an initial second antioxidant layer comprising NbO _z (where 0 <z <2) between the first electrode and the switch layer. Forming a first electrode;
Forming an initial second antioxidant layer comprising NbO _z (where 0 <z <2) on the first electrode;
Forming a switch layer comprising NbO ₂ on the initial second antioxidant layer;
Forming an initial first antioxidant layer comprising NbO _z (where 0 <z <2) on the switch layer;
Forming a second electrode on the initial first antioxidant layer; And
Annealing the switch layer, the initial first antioxidant layer, and the initial second antioxidant layer to form the switch layer, the initial first antioxidant layer, and the initial second antioxidant layer from an amorphous state to a crystalline state. Forming an Nb-containing thin film,
At least one kind of oxygen introduced from the outside on the Nb-containing thin film, first non-lattice oxygen in the switch layer, and second non-lattice oxygen existing in the initial first antioxidant layer is the initial phase. React with the top of the first antioxidant layer to form a first oxide layer comprising NbO _y (where 0 <y <2),
At least one kind of oxygen introduced from the outside of the Nb-containing thin film, the first non-lattice oxygen inside the switch layer, and the third non-lattice oxygen existing inside the initial second anti-oxidation layer is the initial phase. A method of manufacturing a selection device, which reacts with a lower portion of a second antioxidant layer to form a second oxide layer comprising NbO _y (where 0 <y <2). The method of claim 13,
Forming the initial first antioxidant layer is performed by an in-situ process. The method of claim 13,
And the initial first antioxidant layer is formed to a thickness of 10 nm to 15 nm. The method of claim 13,
The annealing is carried out in the temperature range of 650 ℃ to 750 ℃ manufacturing method of the selection device. The method of claim 4, wherein
And said first oxide layer has a larger Nb ⁴⁺ XPS peak than said first antioxidant layer. The method of claim 4, wherein
And the sum of the thicknesses of the switch layer, the first anti-oxidation layer and the first oxide layer is 15 nm to 35 nm. The method of claim 13,
And the initial first anti-oxidation layer is deposited under a condition of oxygen partial pressure (PO ₂ ) of 0% by direct current magnetron sputtering. The method of claim 13,
The switch layer is a method of manufacturing a selection device is deposited under the conditions of oxygen partial pressure (PO ₂ ) 2% to 5% by direct current magnetron sputtering (DS magnetron sputtering).

Images