WO2012066787A1 - 不揮発性記憶素子および不揮発性記憶素子の製造方法 - Google Patents
不揮発性記憶素子および不揮発性記憶素子の製造方法 Download PDFInfo
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- WO2012066787A1 WO2012066787A1 PCT/JP2011/006451 JP2011006451W WO2012066787A1 WO 2012066787 A1 WO2012066787 A1 WO 2012066787A1 JP 2011006451 W JP2011006451 W JP 2011006451W WO 2012066787 A1 WO2012066787 A1 WO 2012066787A1
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- oxynitrogen
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- tantalum oxide
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- BPUBBGLMJRNUCC-UHFFFAOYSA-N oxygen(2-);tantalum(5+) Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Ta+5].[Ta+5] BPUBBGLMJRNUCC-UHFFFAOYSA-N 0.000 claims abstract description 173
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- 230000002950 deficient Effects 0.000 claims abstract description 163
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Images
Classifications
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N70/00—Solid-state devices having no potential barriers, and specially adapted for rectifying, amplifying, oscillating or switching
- H10N70/801—Constructional details of multistable switching devices
- H10N70/881—Switching materials
- H10N70/883—Oxides or nitrides
- H10N70/8833—Binary metal oxides, e.g. TaOx
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10B—ELECTRONIC MEMORY DEVICES
- H10B63/00—Resistance change memory devices, e.g. resistive RAM [ReRAM] devices
- H10B63/80—Arrangements comprising multiple bistable or multi-stable switching components of the same type on a plane parallel to the substrate, e.g. cross-point arrays
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10B—ELECTRONIC MEMORY DEVICES
- H10B63/00—Resistance change memory devices, e.g. resistive RAM [ReRAM] devices
- H10B63/80—Arrangements comprising multiple bistable or multi-stable switching components of the same type on a plane parallel to the substrate, e.g. cross-point arrays
- H10B63/84—Arrangements comprising multiple bistable or multi-stable switching components of the same type on a plane parallel to the substrate, e.g. cross-point arrays arranged in a direction perpendicular to the substrate, e.g. 3D cell arrays
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N70/00—Solid-state devices having no potential barriers, and specially adapted for rectifying, amplifying, oscillating or switching
- H10N70/011—Manufacture or treatment of multistable switching devices
- H10N70/061—Shaping switching materials
- H10N70/063—Shaping switching materials by etching of pre-deposited switching material layers, e.g. lithography
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N70/00—Solid-state devices having no potential barriers, and specially adapted for rectifying, amplifying, oscillating or switching
- H10N70/20—Multistable switching devices, e.g. memristors
- H10N70/24—Multistable switching devices, e.g. memristors based on migration or redistribution of ionic species, e.g. anions, vacancies
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N70/00—Solid-state devices having no potential barriers, and specially adapted for rectifying, amplifying, oscillating or switching
- H10N70/801—Constructional details of multistable switching devices
- H10N70/821—Device geometry
- H10N70/826—Device geometry adapted for essentially vertical current flow, e.g. sandwich or pillar type devices
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N70/00—Solid-state devices having no potential barriers, and specially adapted for rectifying, amplifying, oscillating or switching
- H10N70/801—Constructional details of multistable switching devices
- H10N70/881—Switching materials
- H10N70/883—Oxides or nitrides
Definitions
- the present invention relates to a resistance change type nonvolatile memory element in which a resistance value reversibly changes by applying a voltage pulse, and a method for manufacturing the nonvolatile memory element.
- the resistance change element refers to an element that has a property that the resistance value reversibly changes by an electrical signal and that can store information corresponding to the resistance value in a nonvolatile manner.
- Patent Document 1 discloses a resistance change element in which tantalum oxide layers having different oxygen contents are stacked and used as a resistance change layer.
- the variable resistance element disclosed in Patent Document 1 includes a first electrode layer, a first variable resistance layer including tantalum oxide TaO x , a second variable resistance layer including tantalum oxide Ta 2 O 5 , A variable resistance element configured with the second electrode layer is formed.
- Patent Document 2 discloses a resistance change element using oxynitrogen-deficient tantalum oxynitride TaON as a resistance change layer.
- the resistance change element disclosed in Patent Document 2 includes a first electrode layer, a resistance change layer (TaON) containing an oxide containing Ta and nitrogen, and a second electrode layer.
- Patent Document 2 discloses that the oxygen content with respect to nitrogen in the resistance change layer (TaON) is 1.08 or more and 1.35 or less as an example.
- Patent Document 3 discloses a resistance change element using a resistance change layer having a three-layer structure in which tantalum oxide Ta 2 O 5 , tantalum oxynitride TaON, and tantalum oxide TaO x are laminated in this order. ing.
- the tantalum oxynitride TaON is formed as a barrier layer for preventing oxygen from entering the tantalum oxide TaO x in the manufacturing process.
- the resistance change characteristics of the conventional resistance change element may be deteriorated by a thermal budget or the like, or stable operation at a low voltage is difficult. It was found that it has a problem.
- the present invention provides a nonvolatile memory element that can suppress the deterioration of the oxygen concentration profile of the resistance change layer due to a thermal budget and that can stably operate at a low voltage, and a method for manufacturing the same. Objective.
- a nonvolatile memory element includes a first electrode layer formed on a substrate, a resistance change layer disposed on the first electrode layer, A second electrode layer disposed on the variable resistance layer, wherein the variable resistance layer has a two-layer structure in which an oxynitrogen-deficient tantalum oxynitride layer and a tantalum oxide layer are stacked.
- the oxynitrogen-deficient tantalum oxynitride material constituting the oxynitrogen-deficient tantalum oxynitride layer is an oxygen and / or nitrogen in comparison with an oxide having a stoichiometric composition.
- oxygen hardly diffuses even when a thermal budget is applied.
- oxygen can be prevented from diffusing from the tantalum oxide layer to the oxynitrogen-deficient tantalum oxynitride layer. . Thereby, it is possible to suppress the deterioration of the oxygen concentration profile.
- the resistance change layer is lowered in resistance by oxygen ions moving from the tantalum oxide layer to the oxynitrogen-deficient tantalum oxynitride layer, and the tantalum oxide is reduced from the oxynitrogen-deficient tantalum oxynitride layer. It is preferable to increase the resistance by moving oxygen ions to the physical layer.
- composition of the oxynitrogen-deficient tantalum oxynitride layer is expressed as TaO x N y
- x and y are 0.8 ⁇ x + y ⁇ 1.9. 0 ⁇ y ⁇ 0.5
- composition of the tantalum oxide layer is expressed as TaO z
- z is x + y ⁇ z Is preferably satisfied.
- the resistance changing operation is manifested when oxygen (oxygen ions) enters and exits the tantalum oxide layer by applying a voltage pulse.
- the oxynitrogen-deficient tantalum oxynitride layer has an effect of suppressing the diffusion of oxygen, but if the nitrogen content of the oxynitrogen-deficient tantalum oxynitride layer is too high (that is, the y value is reduced). If it is too high), resistance change operation will be hindered.
- the oxygen value-deficient tantalum oxynitride layer having a composition represented by TaO x N y has a y value of 0 ⁇ y ⁇ 0.5, thereby suppressing deterioration of the oxygen concentration profile. In addition, a good resistance change operation can be realized.
- the x value and y value of the oxynitrogen-deficient tantalum oxynitride layer are 0.8 ⁇ x + y ⁇ 1.9, and the tantalum oxide layer (composition: TaO z ) is x + y ⁇ z.
- the resistivity of the tantalum oxide layer becomes higher than the resistivity of the oxynitrogen-deficient tantalum oxynitride layer.
- the voltage pulse applied during the resistance change operation is distributed to both the tantalum oxide layer and the oxynitride-deficient tantalum oxynitride layer. Of these, the tantalum oxide from which oxygen enters and exits contributes to the resistance change operation.
- the voltage pulse component distributed to the tantalum oxide layer becomes larger, and the nonvolatile memory element can be operated at a lower voltage. It becomes possible to operate.
- the voltage required for the resistance change operation of the nonvolatile memory element is 2.4 V or less, and the nonvolatile memory element can be operated at a lower voltage than the conventional nonvolatile memory element. It becomes possible.
- the thickness of the oxynitrogen-deficient tantalum oxynitride layer is preferably larger than the thickness of the tantalum oxide layer.
- the oxynitrogen-deficient tantalum oxynitride layer preferably has conductivity.
- the electrode in contact with the tantalum oxide layer is preferably configured using one or a plurality of materials having a standard electrode potential higher than the standard electrode potential of tantalum.
- the electrode in contact with the oxynitrogen-deficient tantalum oxynitride layer is preferably configured using one or a plurality of materials having a standard electrode potential lower than the standard electrode potential of tantalum.
- the electrode in contact with the tantalum oxide layer is preferably configured using one or more materials of Au, Pt, Ir, Pd, Cu, and Ag.
- the electrode in contact with the oxynitrogen-deficient tantalum oxynitride layer is preferably formed using one or more materials of W, Ni, and TaN.
- the resistance change operation in the resistance change layer can be caused only at the interface between the tantalum oxide layer and the electrode in contact therewith, and a stable resistance change operation can be realized.
- a method for manufacturing a nonvolatile memory element includes a step (a) of forming a first electrode material layer constituting a first electrode layer on a substrate, and a step on the first electrode material layer.
- an oxynitrogen-deficient tantalum oxynitride material layer is formed by a sputtering method.
- a reactive sputtering method using tantalum as a sputtering target and oxygen and nitrogen as sputtering gases is used.
- a non-volatile memory element manufacturing method comprising: a step (a) of forming a second electrode material layer constituting a second electrode layer on a substrate; (B) forming a tantalum oxide material layer constituting a tantalum oxide layer, and an oxynitride-deficient tantalum acid constituting an oxynitride-deficient tantalum oxynitride layer on the tantalum oxide material layer A step (c) of forming a nitride material layer, and a step (d) of forming a first electrode material layer constituting the first electrode layer on the oxynitrogen-deficient tantalum oxynitride material layer.
- the oxynitrogen-deficient tantalum oxynitride material layer is formed by a sputtering method.
- TaO x N y (0.8 ⁇ x + y ⁇ 1.9, y ⁇ 0.5) is satisfied.
- the composition control of the oxynitrogen-deficient tantalum oxynitride layer having the composition shown is facilitated.
- the tantalum oxide layer can be formed by using a reactive sputtering method with a high film formation rate.
- the method for manufacturing a nonvolatile memory element described above when the tantalum oxide material layer is formed by reactive sputtering, the surface of the oxynitrogen-deficient tantalum oxynitride material layer is exposed to oxygen plasma. For this reason, the surface of the oxynitrogen-deficient tantalum oxynitride material layer is oxidized, and a variable resistance layer having a desired oxygen concentration profile cannot be obtained.
- the tantalum oxide material layer can be formed using a reactive sputtering method with a high film formation rate. Therefore, the manufacturing cost can be reduced.
- the present invention it is possible to provide a nonvolatile memory element that can suppress the deterioration of the oxygen concentration profile of the resistance change layer due to a thermal budget and that can stably operate at a low voltage, and a method for manufacturing the nonvolatile memory element. .
- FIG. 1A is a cross-sectional view illustrating a schematic configuration of the nonvolatile memory element according to Embodiment 1 of the present invention.
- FIG. 1B is a diagram illustrating a configuration of a variable resistance element in which a local region is formed by an initial break.
- 2A and 2B are cross-sectional views showing the steps of the method for manufacturing the nonvolatile memory element according to Embodiment 1 of the present invention, wherein FIG. 2A shows the step of forming the first wiring on the substrate, FIG.
- (c) is a diagram showing a process of forming a first contact hole
- (d) to (e) are diagrams showing a process of forming a first contact plug.
- (F) is a figure which shows the process of forming a 1st electrode material layer and an oxynitrogen deficient tantalum oxynitride material layer
- (g) is a figure which shows the process of forming a tantalum oxide material layer
- (h) The figure which shows the process of forming a 2nd electrode material layer
- (i) is a 1st electrode layer, an oxynitrogen deficient tantalum oxynitride layer, and a tantalum oxide layer by patterning using a mask and processing by dry etching And a step of forming a resistance change element including the second electrode layer.
- FIG. 3 is a view showing the relationship between the resistivity of the oxynitrogen-deficient tantalum oxynitride layer formed by using the manufacturing method in FIG. 2F, and the oxygen flow rate and the nitrogen flow rate.
- FIG. 4 is a diagram showing the relationship between the z value and the resistivity of a tantalum oxide material layer having a composition represented by TaO z .
- FIG. 5 is a diagram showing the result of measuring the electronic state of the valence band of the tantalum oxide material layer by the XPS method.
- FIG. 6 is a diagram showing the relationship between the x value and y value of the oxynitrogen-deficient tantalum oxynitride material layer having the composition represented by TaO x N y and the initial resistance value of the nonvolatile memory element.
- FIG. 7A is a diagram showing resistance values in the high resistance state and the low resistance state of the nonvolatile memory element, where the y value is 0.4 and the x value is 0.4 to 1.3. It is a figure which shows the resistance value in each state of a high resistance state and a low resistance state of the non-volatile memory element using a certain oxynitrogen deficient tantalum oxynitride material layer.
- FIG. 7A is a diagram showing resistance values in the high resistance state and the low resistance state of the nonvolatile memory element, where the y value is 0.4 and the x value is 0.4 to 1.3. It is a figure which shows the resistance value in each state of a high resistance state and a low resistance state of the non-
- FIG. 7B is a diagram showing resistance values of the nonvolatile memory element in a high resistance state and a low resistance state, where the y value is 0.22 and the x value is 0.6 to 1.5. It is a figure which shows the resistance value in each state of a high resistance state and a low resistance state of the non-volatile memory element using a certain oxynitrogen deficient tantalum oxynitride material layer.
- FIG. 8 is a diagram showing the relationship between the number of data rewrite pulses of the resistance change element and the resistance value.
- FIG. 9 is a diagram showing a y value and a cycling operation pass rate of an oxynitrogen-deficient tantalum oxynitride material layer having a composition represented by TaO x N y .
- FIG. 10 is a cross-sectional view illustrating a schematic configuration of a nonvolatile memory element, which is a modification of the nonvolatile memory element.
- FIG. 11 is a cross-sectional view showing a process of a method for manufacturing a nonvolatile memory element according to Embodiment 2 of the present invention, in which (a) shows a process of forming a first wiring on a substrate; ) Is a diagram showing a process of forming a first interlayer insulating layer, (c) is a diagram showing a process of forming a first contact hole, and (d) to (e) are diagrams showing a process of forming a first contact plug.
- (F) is a figure which shows the process of forming a 1st electrode material layer and a tantalum oxynitride material layer
- (g) is a figure which shows the process of forming an oxynitrogen deficient tantalum oxynitride material layer
- (h) Is a diagram showing a process of forming a second electrode material layer
- (i) is a first electrode layer, a tantalum oxide layer, and an oxynitrogen-deficient tantalum oxynitride by patterning using a mask and processing by dry etching
- J is a figure which shows the process of forming a 2nd interlayer insulation layer
- (k) is a figure which shows the process of forming a 2nd contact hole, a 2nd contact plug, and a 2nd wiring.
- FIG. 12 is a cross-sectional view showing a configuration example of the nonvolatile memory element according to Embodiment 3 of the present invention.
- FIG. 13 is a cross-sectional view showing a schematic configuration of a nonvolatile memory element on which the variable resistance element described in Patent Document 1 is mounted.
- FIG. 14 shows the oxygen concentration of the laminated film of the first tantalum oxide material layer, the second tantalum oxide material layer, and the second electrode material layer described in Patent Document 1 shown in FIG. It is a figure which shows a profile analysis result.
- FIG. 15 is a cross-sectional view illustrating a schematic configuration of a nonvolatile memory element on which the variable resistance element described in Patent Document 2 is mounted.
- FIG. 16 is a cross-sectional view illustrating a schematic configuration of a nonvolatile memory element on which the variable resistance element described in Patent Document 3 is mounted.
- FIG. 17 is a diagram showing resistance value characteristics of the variable resistance element described in Patent Document 3 shown in FIG.
- FIG. 13 is a cross-sectional view showing a schematic configuration of the nonvolatile memory element 20 on which the variable resistance element 212 described in Patent Document 1 is mounted.
- the nonvolatile memory element 20 includes a substrate 200 on which the first wiring 201 is formed, a first interlayer insulating layer 202 formed on the substrate 200 so as to cover the first wiring 201, A first contact hole 203 is formed through the first interlayer insulating layer 202 to electrically connect the first wiring 201 and the first electrode layer 205. Inside the contact hole 203, a first contact plug 204 embedded with tungsten as a main component is formed.
- variable resistance element 212 including the first electrode layer 205, the variable resistance layer 206, and the second electrode layer 207 is formed on the first interlayer insulating layer 202 so as to cover the first contact plug 204. Yes.
- a second interlayer insulating layer 208 is formed so as to cover the variable resistance element 212, and the second electrode layer 207 and the second wiring 211 are electrically connected through the second interlayer insulating layer 208.
- a second contact hole 209 is formed for this purpose. Inside the second contact hole 209, tungsten is embedded as a main component, and a second contact plug 210 is formed. Further, a second wiring 211 is formed on the second interlayer insulating layer 208 so as to cover the second contact plug 210.
- the resistance change layer 206 has a stacked structure of a first tantalum oxide layer 206a and a second tantalum oxide layer 206b.
- the first tantalum oxide material layer constituting the first tantalum oxide layer 206a has a composition represented by TaO x satisfying 0.8 ⁇ x ⁇ 1.9.
- the second tantalum oxide material layer constituting the second tantalum oxide layer 206b has a composition represented by TaO z that satisfies 2.1 ⁇ z ⁇ 2.5.
- the resistance change element 212 is heat-treated in steps such as formation of an interlayer insulating layer, formation of contact plugs, formation of wiring, and recovery annealing when forming a multilayer wiring. It will be.
- This application of heat treatment gives a thermal budget to the variable resistance element 212 and oxygen may diffuse from the second tantalum oxide layer 206b to the first tantalum oxide layer 206a. The inventors have found.
- the AES peak intensity in the second tantalum oxide material layer is attenuated, and the AES peak intensity in the first tantalum oxide material layer is increased. That is, by providing a thermal budget, it can be confirmed that oxygen in the second tantalum oxide material layer is diffused into the first tantalum oxide material layer.
- the resistance value and resistance change characteristic of the resistance change element 212 depend on the film thickness and oxygen content of the second tantalum oxide material layer. However, as shown in FIG. 14, oxygen is diffused from the second tantalum oxide layer 206b by a given thermal budget, so that the oxygen content and film thickness of the second tantalum oxide layer 206b are reduced.
- FIG. 15 is a cross-sectional view showing a schematic configuration of the nonvolatile memory element 30 on which the variable resistance element 312 described in Patent Document 2 is mounted.
- a substrate 300 on which the first wiring 301 is formed a first interlayer insulating layer 302 formed on the substrate 300 so as to cover the first wiring 301,
- a first contact hole 303 is formed through the first interlayer insulating layer 302 to electrically connect the first wiring 301 and the first electrode layer 305.
- a first contact plug 304 embedded with tungsten as a main component is formed inside the contact hole 303.
- a variable resistance element 312 including the first electrode layer 305, the variable resistance layer 306, and the second electrode layer 307 is formed on the first interlayer insulating layer 302 so as to cover the first contact plug 304. Yes.
- a second interlayer insulating layer 308 is formed so as to cover the variable resistance element 312, and the second electrode layer 307 and the second wiring 311 are electrically connected through the second interlayer insulating layer 308.
- a second contact hole 309 is formed for this purpose. Inside the second contact hole 309, tungsten is embedded as a main component, and a second contact plug 310 is formed. Further, a second wiring 311 is formed on the second interlayer insulating layer 308 so as to cover the second contact plug 310.
- the resistance change layer 306 in the resistance change element 312 is formed of an oxynitrogen-deficient tantalum oxynitride material layer, and the oxygen content of nitrogen in the oxynitrogen-deficient tantalum oxynitride layer is 1.08 or more. 35 or less.
- the inventors of the present application have found that in the oxynitrogen-deficient tantalum oxynitride layer, oxygen hardly diffuses even when a thermal budget is applied. That is, the inventors of the present application can suppress deterioration of the oxygen concentration profile of the resistance change layer due to a thermal budget by forming the resistance change layer 306 with an oxynitrogen-deficient tantalum oxynitride material layer. Thought.
- the resistance change layer 306 is formed of an oxynitrogen-deficient tantalum oxynitride material layer
- the resistance change operation of the resistance change layer 306 may be hindered.
- a pulse voltage as high as 3.0 V is applied to perform a resistance change operation.
- FIG. 16 is a schematic configuration diagram of a resistance change element 412 described in Patent Document 3.
- FIG. 17 is a diagram illustrating a resistance value characteristic of the variable resistance element 412.
- the resistance change element 412 described in Patent Document 3 includes a first electrode layer 405, a resistance change layer 406, and a second electrode layer 407.
- the resistance change layer 406 includes a tantalum oxynitride layer (TaON) 406b between the tantalum oxide layer (Ta 2 O 5 ) 406c and the tantalum oxide layer (TaO x ) 406a.
- TaON tantalum oxynitride layer
- the resistance change element 412 is desired to further stabilize the resistance value when the resistance changes, that is, further stabilize the resistance change operation.
- the embodiment of the present invention described below has been conceived based on the above examination, and further suppresses the deterioration of the oxygen concentration profile of the resistance change layer due to the thermal budget, and operates stably at a low voltage. It is possible to provide a possible nonvolatile memory element and a method for manufacturing the same.
- FIG. 1A is a cross-sectional view showing a schematic configuration of the nonvolatile memory element 10 according to Embodiment 1 of the present invention.
- the nonvolatile memory element 10 includes a substrate 100, a first wiring 101 formed on the substrate 100, a silicon oxide film formed on the substrate 100 so as to cover the first wiring 101, and the like ( 500 to 1000 nm), a first contact hole 103 (diameter: 50 to 300 nm) formed through the first interlayer insulating layer 102, and the inside of the first contact hole 103
- the first contact plug 104 is embedded with tungsten as a main component.
- a variable resistance element 112 is provided on the first interlayer insulating layer 102.
- a second wiring 111 is formed on the second interlayer insulating layer 108 so as to cover the second contact plug 110.
- the resistance change element 112 includes a first electrode layer 105 (thickness: 5 to 100 nm) made of tantalum nitride and the like, which is formed to cover the first contact plug 104, and a resistance change layer 106 (thickness: 20 to 100 nm) and a second electrode layer 107 (thickness: 5 to 100 nm) made of noble metal (Pt, Ir, Pd, etc.).
- the resistance change layer 106 includes an oxynitrogen-deficient tantalum oxynitride layer 106 a and an oxynitrogen-deficient tantalum oxynitride layer 106 a formed on the first electrode layer 105.
- the tantalum oxide layer 106b formed above has a two-layer structure.
- the oxynitrogen-deficient tantalum oxynitride layer 106a is conductive and has a feature that oxygen is less likely to diffuse than the first tantalum oxide layer 206a described in Patent Document 1. Therefore, by disposing the oxynitrogen-deficient tantalum oxynitride layer 106a, oxygen can be prevented from diffusing from the tantalum oxide layer 106b.
- the film thickness of the oxynitrogen-deficient tantalum oxynitride layer 106a is, for example, about 44.5 nm, and the film thickness of the tantalum oxide layer 106b is, for example, about 5.5 nm. That is, the thickness of the oxynitrogen-deficient tantalum oxynitride layer 106a is larger than the thickness of the tantalum oxide layer 106b.
- the tantalum oxynitride layer 406b has a thickness of about 3 nm to 5 nm, and is thinner than the tantalum oxide layer 406a.
- the oxygen concentration profile which is a problem of the conventional resistance change element, is deteriorated. It becomes possible to reduce.
- the film thickness of the oxynitrogen-deficient tantalum oxynitride layer 106a may be at least 15 nm.
- the film thickness of the oxynitrogen-deficient tantalum oxynitride layer 106a is preferably at least twice the film thickness of the tantalum oxide layer 106b.
- the oxynitrogen-deficient tantalum oxynitride material is a content of at least one of oxygen and nitrogen (atomic ratio: oxygen and nitrogen in the total number of atoms) compared to an oxynitride having a stoichiometric composition An oxynitride having a non-stoichiometric composition with a low atomic ratio).
- An oxynitrogen-deficient tantalum oxynitride material is a material having a composition such that 2x ′ + 3y ′ ⁇ 5 when its composition is represented by TaO x ′ N y ′ .
- Ta tantalum
- O oxygen
- the composition of the oxynitrogen-deficient tantalum oxynitride layer 106a is represented by TaO x N y
- the x value and the y value are 0.8 ⁇ x + y ⁇ 1.9, 0 ⁇ Y ⁇ 0.5.
- an oxynitrogen-deficient tantalum oxynitride layer 106a made of an oxynitrogen-deficient tantalum oxynitride material and a tantalum oxide layer 106b made of a tantalum oxide material having a high oxygen concentration are used.
- the initial resistance of the nonvolatile memory element 10 becomes very high due to the presence of the tantalum oxide layer 106b. Therefore, in order to obtain resistance change characteristics, an electric pulse (initial breakdown voltage) higher than a voltage used for normal resistance change is applied to the resistance change layer 106 in the initial state, whereby the conductive path is changed to the resistance change layer 106. It is necessary to form (break down) inside. Such processing is called initial break (initial breakdown).
- the resistance change layer 106 In the initial breakdown, by applying an initial breakdown voltage to the resistance change layer 106, a current flows through the tantalum oxide layer 106b having a high oxygen concentration in the resistance change layer 106, and the resistance value of the tantalum oxide layer 106b is reduced.
- the resistance value is adjusted from a very high initial resistance value (1 ⁇ 10 6 to 1 ⁇ 10 8 ⁇ ) to a resistance value (1 ⁇ 10 2 to 1 ⁇ 10 4 ⁇ ).
- the diameter of the conductive path formed by the initial break is considered to be about 10 nm.
- characteristics such as retention (data retention characteristics) and endurance (number of data rewrites) vary for each nonvolatile memory element 10.
- an appropriate initial break voltage cannot be set, and the yield of the nonvolatile memory element 10 is further reduced.
- the initial break voltage is too high, the resistance value indicating data “0” becomes low, and the resistance cannot be changed to the high resistance side indicating data “1”. This may cause an endurance failure that prevents rewriting.
- the initial break voltage is too low, the resistance value indicating data “0” becomes high.
- a retention failure data cannot be retained in which data is rewritten may occur due to the resistance value changing to the high resistance side indicating data “1” during data retention.
- the current density that flows in the element during the initial break that is, the effective cross section of the current flows.
- the variation in area is a cause of defects. As a result, the yield of the nonvolatile memory element 10 and the reliability deteriorate.
- the nonvolatile memory element 10 that has been initially broken is applied with a positive or negative voltage pulse applied to the second electrode layer 107 with respect to the first electrode layer 105, so that the resistance change element 112 is in a low resistance state or a high resistance state. It is changed to a resistance state.
- a negative voltage pulse applied to the second electrode layer 107
- the resistance change element 112 is changed from a high resistance state to a low resistance state (low resistance).
- a positive voltage pulse to the second electrode layer 107 the resistance change element 112 is changed from a low resistance state to a high resistance state (high resistance).
- the reduction in resistance is caused by a negative voltage pulse applied to the second electrode layer 107, whereby oxygen ions in a conductive path in the tantalum oxide layer 106b are expelled from the tantalum oxide layer 106b, and the conductivity of the tantalum oxide layer 106b is reduced. This is thought to be caused by a decrease in the oxygen content of the pass.
- the increase in resistance is caused by the positive voltage pulse applied to the second electrode layer 107, oxygen ions in the oxynitride-deficient tantalum oxynitride layer 106a are taken into the conductive path in the tantalum oxide layer 106b, This is considered to be caused by an increase in the oxygen content of the conductive path in the tantalum oxide layer 106b.
- FIG. 1B is a diagram illustrating a configuration of the variable resistance element 112 in which the local region 106c is formed by the initial break.
- the resistance change layer 106 to which the initial breakdown voltage is applied is in the vicinity of the interface between the oxynitride-deficient tantalum oxynitride layer 106a that is the first oxide layer and the tantalum oxide layer 106b that is the second oxide layer. Local area 106c is provided.
- the oxygen deficiency of the local region 106c is larger than the oxygen deficiency of the tantalum oxide layer 106b and is different from the oxygen deficiency of the oxynitrogen deficient tantalum oxynitride layer 106a.
- the local region 106c can be formed by applying an initial break voltage to the resistance change layer 106 having a laminated structure of the oxynitrogen-deficient tantalum oxynitride layer 106a and the tantalum oxide layer 106b.
- the initial break voltage is preferably a low voltage. Due to the initial break, a local region 106c that is in contact with the second electrode layer 107, penetrates the tantalum oxide layer 106b, partially penetrates the oxynitrogen-deficient tantalum oxynitride layer 106a, and is not in contact with the first electrode layer 105 is formed. It is formed.
- the local region 106c means a region of the resistance change layer 106 where current flows predominantly when a voltage is applied between the first electrode layer 105 and the second electrode layer 107.
- the local region 106 c means a region including a set of a plurality of filaments (conductive paths) formed in the resistance change layer 106. That is, the resistance change in the resistance change layer 106 is expressed through the local region 106c. It is presumed that the resistance change operation appears when the density of oxygen vacancies in the local region 106c changes due to redox. Therefore, when a driving voltage is applied to the resistance change layer 106 in the low resistance state, a current flows predominantly in the local region 106c including the filament. The resistance change layer 106 transitions between a high resistance state and a low resistance state in the local region 106c.
- the resistance value of the resistance change layer 306 is changed by forming a local region in which the resistance change operation occurs in the tantalum oxynitride, so that the high resistance state and the low resistance state. And transition.
- the composition of the oxynitrogen-deficient tantalum oxynitride layer 106a and the tantalum oxide layer 106b will be described.
- the value of x + y is smaller than 0.8, the resistance value of the variable resistance element 112 is low, so that it is difficult to apply a voltage to the variable resistance element 112 and it is necessary to increase the operating voltage.
- the value of x + y exceeds 1.9, the resistance value of the resistance change element 112 increases, and the operating voltage of the resistance change element 112 increases rapidly.
- the x value and the y value are 0.8 ⁇ x + y ⁇ 1. Is preferably in the range of .9.
- the resistance change element 112 operates when the y value is in the range of 0 ⁇ y ⁇ 0.5.
- the y value is preferably 0.22 ⁇ y ⁇ 0.5.
- the tantalum oxide layer 106b is set to have a higher oxygen concentration than the oxynitrogen-deficient tantalum oxynitride layer 106a, and thus the z value is x + y ⁇ It becomes the range of z. Note that the tantalum oxide layer 106b may not be an oxygen-deficient type.
- variable resistance element 112 With such a configuration, the operating voltage of the variable resistance element 112 can be reduced, and operation at a lower voltage is possible as compared with the conventional variable resistance element.
- FIGS. 2A to 2K are cross-sectional views illustrating a method for manufacturing the nonvolatile memory element 10 according to the present embodiment. The manufacturing method of the principal part of the non-volatile memory element 10 is demonstrated using these.
- the first wiring 101 is formed on the substrate 100.
- a conductive layer (thickness: 400 to 600 nm) made of aluminum or the like is formed on a substrate 100 over which a transistor, a lower layer wiring, and the like are formed by a sputtering method or the like.
- the first wiring 101 is formed by patterning using a mask having a desired wiring pattern and processing by dry etching. Note that the first wiring 101 may be formed using a manufacturing method such as damascene.
- a first interlayer insulating layer 102 is formed.
- plasma TEOS as an insulating layer on the substrate 100 so as to cover the first wiring 101 by the CVD method
- the surface is planarized to form the first interlayer insulating layer 102 (thickness: 500 to 1000 nm).
- a fluorine-containing oxide for example, FSG
- a low-k material may be used to reduce the parasitic capacitance between the wirings.
- a first contact hole 103 is formed.
- a first contact hole 103 (diameter: 50 to 300 nm) penetrating the first interlayer insulating layer 102 is formed by patterning using a mask having a desired contact hole pattern and processing by dry etching.
- the width of the first wiring 101 is smaller than the first contact hole 103, the contact area between the first wiring 101 and the first contact plug 104 changes due to the effect of mask misalignment, for example, the cell current varies. . From the viewpoint of preventing this, the width of the first wiring 101 is larger than that of the first contact hole 103.
- a first contact plug 104 connected to the first wiring 101 is formed.
- a titanium (Ti) / titanium nitride (TiN) layer (thickness: 5 to 30 nm each) functioning as an adhesion layer and a diffusion barrier is formed in the lower layer by sputtering and CVD, respectively, and then the first layer is formed in the upper layer.
- Tungsten (W, thickness: 200 to 400 nm) which is a main component of the contact plug 104, is formed by a CVD method.
- the first contact hole 103 is filled with a conductive layer 104 ′ having a laminated structure that will later become the first contact plug 104.
- the conductive layer 104 has the above-described W / Ti / TiN structure.
- the first contact plug 104 is formed. After the conductive layer 104 ′ is formed, the entire surface of the conductive layer 104 ′ is planarized and polished using a chemical mechanical polishing method (CMP method), and an unnecessary conductive layer 104 ′ on the first interlayer insulating layer 102 is polished. Then, the first contact plug 104 is formed in which the conductive layer 104 ′ is left only in the first contact hole 103.
- CMP method chemical mechanical polishing method
- a first electrode material layer 105 'and an oxynitrogen-deficient tantalum oxynitride material layer 106a' are formed.
- a first electrode material layer 105 ′ (thickness: 20 to 50 nm) made of tantalum nitride (TaN) is formed on the first interlayer insulating layer 102 so as to cover the first contact plug 104 by a sputtering method or the like. Form.
- an oxynitrogen-deficient tantalum oxynitride material layer 106a ′ is formed on the first electrode material layer 105 ′ by a sputtering method.
- a so-called reactive sputtering method in which a sputtering target made of tantalum is sputtered in an atmosphere containing oxygen and nitrogen is used.
- the thickness of the oxynitride-deficient tantalum oxynitride material layer 106a ' can be measured using a spectroscopic ellipsometry method, and the thickness is, for example, 20 to 50 nm.
- sputtering conditions for forming the oxynitrogen-deficient tantalum oxynitride material layer 106a ′ by the reactive sputtering method are set such that the power output is 1000 W, the deposition pressure is 0.05 Pa, and the sputtering gas is argon or oxygen. Using nitrogen, the flow rates of oxygen and nitrogen are controlled so that the resistivity of the oxynitrogen-deficient tantalum oxynitride material layer 106a ′ is 0.75 m ⁇ cm to 6 m ⁇ cm. A detailed relationship between the film forming conditions and resistivity of the oxynitrogen-deficient tantalum oxynitride material layer 106a 'will be described later.
- a tantalum oxide material layer 106b ′ is formed.
- a tantalum oxide material layer 106b ′ is formed on the oxynitrogen-deficient tantalum oxynitride material layer 106a ′.
- the tantalum oxide material layer 106b ′ is formed by RF magnetron sputtering using tantalum oxide having a composition represented by Ta 2 O 5 as a sputtering target and using argon (Ar) as a sputtering gas.
- the RF power output is 200 W
- the deposition pressure is 0.3 Pa
- the argon gas flow rate is 300 sccm
- the substrate temperature is room temperature.
- the thickness of the tantalum oxide material layer 106b ′ effective for laminating with the oxynitrogen-deficient tantalum oxynitride material layer 106a ′ is 3 to 10 nm, and the thickness thereof is determined by spectroscopic ellipsometry. Can be measured.
- the deposition rate when the tantalum oxide material layer 106b ′ is formed using the above-described sputtering conditions is 1.2 nm / min.
- a second electrode material layer 107 ' is formed.
- iridium (Ir) as the second electrode material layer 107 ′ is formed by, for example, a sputtering method.
- the thickness of the second electrode material layer 107 ′ formed by the sputtering method is about 80 nm.
- the first electrode material layer 105 ′ in contact with the oxynitrogen-deficient tantalum oxynitride material layer 106a ′ is made of tantalum such as W, Ni, and TaN. It is preferable to use one or a plurality of materials having a standard electrode potential lower than the standard electrode potential. Further, the second electrode material layer 107 ′ in contact with the tantalum oxide material layer 106b ′ is preferably configured using one or a plurality of materials having a standard electrode potential higher than the standard electrode potential of tantalum. .
- noble metals such as Au (gold), Pt (platinum), Ir (iridium), Pd (palladium), Cu (copper), and Ag (silver).
- processing of noble metals is difficult, but by arranging the second electrode material layer 107 ′ on the resistance change element 112, processing becomes relatively easy. With such a configuration, the resistance change operation in the resistance change layer 106 can be generated only at the interface between the tantalum oxide layer 106b and the second electrode layer 107 in contact with the tantalum oxide layer 106b. Can be realized.
- the variable resistance element 112 is formed.
- the first electrode material layer 105 ′, the oxynitrogen-deficient tantalum oxynitride material layer 106a ′, the tantalum oxide material layer 106b ′, and the second electrode material layer 107 are formed.
- the resistance change element 112 is formed.
- the thickness of the second electrode layer 107 is about 50 to 60 nm.
- the resistance change element 112 is covered, and a second interlayer insulating layer 108 (500 to 1000 nm) is formed.
- a second interlayer insulating layer 108 (500 to 1000 nm) is formed.
- the second interlayer insulating layer 108 in a furnace heated to 400 ° C. for the purpose of relaxing the residual stress of the second interlayer insulating layer 108 and removing moisture remaining on the second interlayer insulating layer 108. Heat treatment for 10 minutes.
- the second contact hole 109 and the second contact plug 110 are formed by the same manufacturing method as in FIGS. 2 (a) to (e). Thereafter, the second contact plug 110 is covered, and the second wiring 111 is formed. After the formation of the second wiring 111, heat treatment is performed for 10 minutes in a furnace heated to 400 ° C. for the purpose of preventing corrosion of the aluminum constituting the second wiring 111, thereby completing the nonvolatile memory element 10.
- FIG. 3 shows the flow rates of oxygen and nitrogen when an oxynitrogen-deficient tantalum oxynitride material layer 106a ′ having a composition represented by TaO x N y is formed by the method described in FIG. And the resistivity of the oxynitrogen-deficient tantalum oxynitride material layer 106a ′.
- FIG. 3 shows the resistivity of the oxynitrogen-deficient tantalum oxynitride material layer 106a ′ when the nitrogen flow rate is 2 sccm and 6 sccm and the oxygen flow rate is changed at each nitrogen flow rate.
- the resistivity of the oxynitrogen-deficient tantalum oxynitride material layer 106a ′ was calculated from the film thickness measurement by the spectroscopic ellipsometry method and the resistance measurement result by the four-terminal measurement method. From the results shown in FIG. 3, it can be seen that the resistivity of the oxynitrogen-deficient tantalum oxynitride material layer 106a ′ is higher when the nitrogen flow rate is 6 sccm than when the nitrogen flow rate is 2 sccm. That is, it can be confirmed that the resistivity of the oxynitrogen-deficient tantalum oxynitride material layer 106a ′ is increased by increasing the nitrogen flow rate.
- the nitrogen content of the oxynitrogen-deficient tantalum oxynitride material layer 106a ′ having a composition represented by TaO x N y is increased by increasing the nitrogen flow rate (that is, the y value is increased). Because).
- the resistivity of the oxynitrogen-deficient tantalum oxynitride material layer 106a ′ is increased by increasing the oxygen flow rate. This is because the oxygen content of the oxynitrogen-deficient tantalum oxynitride material layer 106a ′ having a composition represented by TaO x N y is increased by increasing the oxygen flow rate (that is, the x value is increased). Because).
- the nitrogen content and the oxygen content of the oxynitrogen-deficient tantalum oxynitride material layer 106a ′ are obtained by changing the nitrogen flow rate and the oxygen flow rate using the reactive sputtering method described in FIG. Can be controlled.
- composition of the oxynitrogen-deficient tantalum oxynitride layer [Composition of oxynitrogen-deficient tantalum oxynitride layer] Next, the composition of the oxynitrogen-deficient tantalum oxynitride material layer 106a ′ will be described.
- Table 1 shows an oxynitride-deficient tantalum oxynitride material having a composition represented by TaO x N y , formed by using the reactive sputtering method described in FIG. 2 (f) and having a nitrogen flow rate of 2 sccm and 6 sccm.
- the result of having analyzed x value and y value of the layer 106a 'by Rutherford backscattering method (RBS) is shown.
- the oxygen flow rate was adjusted so that the resistivity was approximately 2 m ⁇ cm.
- Each oxygen flow rate is shown in Table 1.
- the x value when the nitrogen flow rate is 0 sccm is also shown.
- the nitrogen content contained in the oxynitrogen-deficient tantalum oxynitride material layer 106a ′ formed using the method described in FIG. 2 (f) is considered to depend on the nitrogen flow rate during formation by reactive sputtering. It is done. Therefore, from the results shown in Table 1, the oxynitride-deficient tantalum oxynitride material layer 106a ′ formed with a nitrogen flow rate of 2 sccm has a y value of 0.22 and the nitrogen-flowrate tantalum acid formed with a nitrogen flow rate of 6 sccm.
- the y value of the nitride material layer 106a ′ is 0.4.
- the composition of oxygen and nitrogen analyzed by the RBS method includes a relatively large error of ⁇ 4% in units of atm%. For this reason, errors also occur in the x value and the y value.
- the y value when the nitrogen flow rate is 6 sccm is in the range of 0.30 ⁇ y ⁇ 0.50. Therefore, the maximum value of the y value of the oxynitrogen-deficient tantalum oxynitride having the composition represented by TaO x N y shown in Table 1 is 0.5.
- a 50-nm-thick tantalum oxide material layer 106b ′ is formed using the same conditions as those described in FIG. 2G, and the sheet resistance is measured by a four-terminal measurement method. It was. However, since it exceeded the measurable sheet resistance value (10 7 ⁇ / sq.), It could not be measured. Therefore, the resistivity of the tantalum oxide material layer 106b ′ in this embodiment is at least 50000 m ⁇ cm.
- FIG. 4 shows the relationship between the resistivity of the tantalum oxide material layer 106b ′ having a composition represented by TaO z and the z value measured by the RBS method.
- the resistivity of the tantalum oxide material layer 106b ′ is calculated from the film thickness measured by the spectroscopic ellipsometry method and the sheet resistance value measured by the four-terminal measurement method. From FIG. 4, it can be confirmed that the resistivity of the tantalum oxide material layer 106b ′ increases as the z value increases.
- z 2.42
- measurement by a four-terminal measurement method was possible, and the resistivity was 5300 m ⁇ cm. Therefore, when the composition of the tantalum oxide material layer 106b ′ formed by the method described in FIG. 2G is represented by TaO z from the measurable range of resistivity, the z value is in the range of 2.42 ⁇ z. It is in.
- the composition of the tantalum oxide material layer 106b ′ is expressed as TaO z , it can be expressed as z ⁇ 2.5. Note that the tantalum oxide material layer 106b ′ may not be the oxygen-deficient tantalum oxide material layer 106b ′.
- the composition of the tantalum oxide material layer 106b ′ in this embodiment is expressed by TaO z , and 2.42 ⁇ z ⁇ 2.5.
- the resistivity of the tantalum oxide material layer 106b ′ is 50000 m ⁇ cm or more.
- FIG. 6 is a diagram showing the relationship between the x value and y value of the oxynitrogen-deficient tantalum oxynitride material layer 106a ′ having a composition represented by TaO x N y and the initial resistance value of the nonvolatile memory element. is there.
- the initial resistance value is measured by changing the x value and the y value in a range of 0.8 ⁇ x + y ⁇ 1.9 and 0 ⁇ y ⁇ 0.5.
- nonvolatile memory using the oxynitrogen-deficient tantalum oxynitride material layer 106a ′ whose y value is 0, 0.22, 0.4, and x value is 0.4 to 1.42.
- the initial resistance value of the element 10 is shown.
- the x value at each point of the initial resistance value shown in FIG. 6 is shown in FIG.
- the film thickness of the tantalum oxide layer 106b is set to 5.5 nm.
- the data indicated by black squares in the figure shows the resistance of the oxynitrogen deficient tantalum oxynitride layer 106a when the resistivity of the oxynitrogen deficient tantalum oxynitride layer 106a is 2 m ⁇ cm, and the data indicated by the black rhombus indicates the resistance of the oxynitrogen deficient tantalum oxynitride layer 106a.
- the initial resistance value when the rate is 4 m ⁇ cm is shown.
- the resistivity of the tantalum oxide material layer 106b ′ is at least 50000 m ⁇ cm, the resistivity of the oxynitrogen-deficient tantalum oxynitride material layer 106a ′ (2 m ⁇ cm, 4 m ⁇ cm), and the resistivity of the first electrode material layer 105 ′ ( 3 m ⁇ cm), which is 10000 times larger than the resistivity (0.2 m ⁇ cm) of the second electrode material layer 107 ′.
- the initial resistance value of the nonvolatile memory element 10 is substantially determined by the film thickness and oxygen content (that is, the z value) of the tantalum oxide layer 106b having the highest resistivity.
- the initial resistance value of the nonvolatile memory element 10 when the y value is 0 is equal to the initial resistance value of the nonvolatile memory element 20 on which the variable resistance element 212 described in Patent Document 1 is mounted. Equivalent to.
- the material constituting the second tantalum oxide layer 206b in the variable resistance element 212 is the tantalum oxide material layer 106b 'in this embodiment, and the film thickness is 5.5 nm.
- the initial resistance value is determined by the film thickness and oxygen content of the second tantalum oxide material layer 206b.
- the initial resistance value is higher than that of the conventional nonvolatile memory element 20 described in Patent Document 1. high.
- the oxygen in the second tantalum oxide layer 206b is converted into the first tantalum oxide by the thermal budget given in the steps shown in FIGS. Diffusion into the material layer 206a reduces the film thickness and oxygen content of the tantalum oxide layer 206b.
- the tantalum oxide layer 106b to the oxynitrogen-deficient tantalum oxynitride material layer 106a since the initial resistance value is higher than that of the conventional nonvolatile memory element 20, the tantalum oxide layer 106b to the oxynitrogen-deficient tantalum oxynitride material layer 106a. It can be determined that the diffusion of oxygen into ′ is suppressed and the deterioration of the oxygen concentration profile of the tantalum oxide layer 106b is suppressed.
- the resistance change layer 106 includes the oxygen-nitrogen-deficient tantalum oxynitride material layer 106a ′ and the tantalum oxide material layer 106b ′ having oxygen barrier properties. Since it has a two-layer structure, it is considered that the resistance change characteristic of the resistance change element 112 is stabilized.
- the y value is preferably larger than 0.22.
- the nonvolatile memory element 10 changes between a high resistance state and a low resistance state by applying two types of voltage pulses having different polarities. That is, when a negative voltage pulse (voltage: ⁇ 1.8 V, pulse width 100 ns) is applied to the second electrode layer 107 with respect to the first electrode layer 105, the nonvolatile memory element 10 is in a high resistance state (resistance value). From 46000 to 150,000 ⁇ ) to a low resistance state (resistance value: about 10,000 ⁇ ). On the other hand, when a positive voltage pulse (voltage: 2.4 V, pulse width 100 ns) is applied to the second electrode layer 107, the nonvolatile memory element 10 increases from the low resistance state to the high resistance state.
- a negative voltage pulse voltage: ⁇ 1.8 V, pulse width 100 ns
- FIG. 7A and FIG. 7B show a high resistance when the resistance value is changed by applying voltage pulses having different polarities between the first electrode layer 105 and the second electrode layer 107 of the nonvolatile memory element 10. The resistance value in each state of a resistance state and a low resistance state is shown.
- the resistance values of the element 10 in a high resistance state and a low resistance state are shown.
- the resistivity of the oxynitrogen-deficient tantalum oxynitride material layer 106a ′ is set to 0.80, 2.1, and 5.8 m ⁇ cm, and the resistance in the high resistance state and the low resistance state with respect to each resistivity. Values are shown as black squares and black triangles, respectively.
- the x value for each resistivity is shown in FIG. 7A. In any of the x values of 0.4, 1.1, and 1.3, the nonvolatile memory element 10 exhibits a high resistance state and a low resistance state, and operates stably at a low voltage.
- the oxynitrogen-deficient tantalum oxynitride material layer 106a ′ when the y value is changed to 0.22, and the x value is changed to 0.6, 1.2, and 1.5, respectively, is used.
- the resistance values of the nonvolatile memory element 10 in the high resistance state and the low resistance state are shown.
- the resistivity of the oxynitrogen-deficient tantalum oxynitride material layer 106a ′ is set to 0.76, 1.9, and 6.0 m ⁇ cm, respectively.
- the resistance values are indicated by black squares and black triangles, respectively.
- the x value for each resistivity is shown in FIG. 7B. When the x value is 0.6, 1.2, or 1.5, the nonvolatile memory element 10 exhibits a high resistance state and a low resistance state, and operates stably at a low voltage.
- the nonvolatile memory element 10 can perform a resistance change operation at a voltage of 2.4 V or less, and has a lower voltage than the nonvolatile memory element 30 using the resistance change element 312 described in Patent Document 2. Is possible. Further, the resistance change operation does not appear only when the oxynitrogen-deficient tantalum oxynitride layer 106a is formed under a specific condition, and the resistance change operation is possible in the range of resistivity from 0.75 m ⁇ cm to 6 m ⁇ cm. It can be confirmed that there is.
- FIG. 8 is a diagram showing the relationship between the number of pulses of data rewriting of the resistance change element and the resistance value. In other words, the cycling characteristics are shown in which the high resistance state and the low resistance state are repetitively rewritten a plurality of times.
- the resistance change element 112 when the resistance change element 112 is repeatedly written in the high resistance state and the low resistance state, the change in resistance value is detected stably in two values, the high resistance state and the low resistance state. ing. Therefore, in the variable resistance element 112 shown in the present embodiment, the problem that the resistance value in the high resistance state gradually decreases or the resistance value in the low resistance state varies as compared with the prior art shown in FIG. You can see that.
- FIG. 9 is a diagram showing a y value and a cycling operation pass rate of the oxynitrogen-deficient tantalum oxynitride material layer 106a ′ having a composition represented by TaO x N y . That is, when the x value and the y value of the oxynitrogen-deficient tantalum oxynitride material layer 106a ′ having a composition represented by TaO x N y are changed, the high resistance state and the low resistance state are changed in the above-described cycling operation. Each case shows a value in a predetermined range (passed).
- the cycling operation pass rate is high. Therefore, it can be seen that in the resistance change element 112 according to the present exemplary embodiment, the rewriting operation of the resistance change element 112 is more stable when there is less deficiency of oxynitrogen.
- the non-volatile memory element according to the present embodiment differs from the non-volatile memory element according to the first embodiment in that a tantalum oxide layer is formed on the oxynitride-deficient tantalum oxynitride layer in the resistance change layer of the non-volatile memory element. This is the point where physical layers are arranged.
- FIG. 10 is a cross-sectional view of a nonvolatile memory element 11 which is a modification of the nonvolatile memory element 10 described in FIG. 1A. 10, the same components as those in FIG. 1A are denoted by the same reference numerals, and description thereof is omitted. As shown in FIG. 10, the difference between the nonvolatile memory element 11 and the nonvolatile memory element 10 is that the arrangement of the resistance change element 112 is turned upside down.
- the variable resistance element 112 has a first electrode layer 505 (thickness: formed of a noble metal (Pt, Ir, Pd, etc.) etc. formed so as to cover the first contact plug 104. 5 to 100 nm), a resistance change layer 106 (thickness: 20 to 100 nm), and a second electrode layer 507 (thickness: 5 to 100 nm) made of tantalum nitride or the like.
- a first electrode layer 505 thickness: formed of a noble metal (Pt, Ir, Pd, etc.) etc. formed so as to cover the first contact plug 104. 5 to 100 nm
- a resistance change layer 106 thinness: 20 to 100 nm
- a second electrode layer 507 thinness: 5 to 100 nm
- the resistance change layer 106 includes a tantalum oxide layer 106b formed on the first electrode layer 505 and an oxynitride-deficient tantalum formed on the tantalum oxide layer 106b. It has a two-layer structure including an oxynitride layer 106a. Other configurations are similar to those of the nonvolatile memory element 10 described in the first embodiment.
- FIG. 11A to 11K are cross-sectional views illustrating a method for manufacturing the nonvolatile memory element 11 according to the present embodiment. The manufacturing method of the principal part of the non-volatile memory element 11 is demonstrated using these.
- the first wiring 101 is formed on the substrate 100.
- a conductive layer (thickness: 400 to 600 nm) made of aluminum or the like is formed on a substrate 100 over which a transistor, a lower layer wiring, and the like are formed by a sputtering method or the like.
- the first wiring 101 is formed by patterning using a mask having a desired wiring pattern and processing by dry etching. Note that the first wiring 101 may be formed using a manufacturing method such as a damascene method.
- a first interlayer insulating layer 102 is formed.
- plasma TEOS as an insulating layer on the substrate 100 so as to cover the first wiring 101 by the CVD method
- the surface is planarized to form the first interlayer insulating layer 102 (thickness: 500 to 1000 nm).
- a fluorine-containing oxide for example, FSG
- a low-k material may be used to reduce the parasitic capacitance between the wirings.
- a first contact hole 103 is formed.
- a first contact hole 103 (diameter: 50 to 300 nm) penetrating the first interlayer insulating layer 102 is formed by patterning using a mask having a desired contact hole pattern and processing by dry etching.
- the width of the first wiring 101 is smaller than the first contact hole 103, the contact area between the first wiring 101 and the first contact plug 104 changes due to the effect of mask misalignment, for example, the cell current varies. . From the viewpoint of preventing this, the width of the first wiring 101 is larger than that of the first contact hole 103.
- a first contact plug 104 connected to the first wiring 101 is formed.
- a titanium (Ti) / titanium nitride (TiN) layer (thickness: 5 to 30 nm each) functioning as an adhesion layer and a diffusion barrier is formed in the lower layer by sputtering and CVD, respectively, and then the first layer is formed in the upper layer.
- Tungsten (W, thickness: 200 to 400 nm) which is a main component of the contact plug 104, is formed by a CVD method.
- the first contact hole 103 is filled with a conductive layer 104 ′ having a laminated structure that will later become the first contact plug 104.
- the conductive layer 104 has the above-described W / Ti / TiN structure.
- the first contact plug 104 is formed.
- the entire surface of the conductive layer 104 ′ is planarized and polished using a chemical mechanical polishing method (CMP method), and the unnecessary conductive layer 104 on the first interlayer insulating layer 102 is polished. 'Is removed to form a first contact plug 104 in which the conductive layer 104 ′ is left only in the first contact hole 103.
- CMP method chemical mechanical polishing method
- the first interlayer insulation so as to cover the first contact plug 104 is performed.
- a first electrode material layer 505 ′ (thickness: 20 to 50 nm) made of iridium (Ir) is formed on the layer 102 by a sputtering method.
- the first electrode material layer 505 ′ in contact with the tantalum oxide material layer 106b ′ constituting the tantalum oxide layer 106 is formed of a noble metal. It is desirable.
- a tantalum oxide material layer 106b ′ is formed on the first electrode material layer 505 ′ by a sputtering method.
- the tantalum oxide material layer 106b ′ is formed by RF magnetron sputtering using tantalum oxide having a composition represented by Ta 2 O 5 as a sputtering target and using argon (Ar) as a sputtering gas.
- the RF power output is 200 W
- the deposition pressure is 0.3 Pa
- the argon gas flow rate is 300 sccm
- the substrate temperature is room temperature.
- the thickness of the tantalum oxide material layer 106b ′ effective for causing a resistance change by being stacked with the oxynitrogen-deficient tantalum oxynitride material layer 106a ′ can be measured using a spectroscopic ellipsometry method, as an example. Its thickness is 3 to 10 nm.
- the oxynitride-deficient tantalum oxynitride material layer 106a ′ is formed on the tantalum oxide material layer 106b ′.
- a material layer 106a ′ is formed.
- the oxynitrogen-deficient tantalum oxynitride material layer 106a ' is formed by a reactive sputtering method in which a sputtering target made of tantalum is sputtered in an atmosphere containing oxygen and nitrogen.
- the thickness of the oxynitrogen-deficient tantalum oxynitride material layer 106a ' is measured using a spectroscopic ellipsometry method, and the thickness is 20 to 50 nm.
- the sputtering conditions for forming the oxynitrogen-deficient tantalum oxynitride material layer 106a ′ by reactive sputtering are as follows: the power output is 1000 W, the deposition pressure is 0.05 Pa, and the sputtering gas is argon, oxygen, or nitrogen. The oxygen and nitrogen flow rates are controlled so that the resistivity of the oxynitrogen-deficient tantalum oxynitride material layer 106a ′ is 0.75 m ⁇ cm to 6 m ⁇ cm.
- Tantalum nitride (TaN) as the second electrode material layer 507 ′ is formed by sputtering on the oxynitrogen-deficient tantalum oxynitride material layer 106a ′.
- the first electrode material layer 505 ′ and the tantalum oxide material layer are formed by patterning using a mask and processing by dry etching.
- 106b ′, the oxynitrogen-deficient tantalum oxynitride material layer 106a ′, and the second electrode material layer 507 ′ are processed by patterning, and the first electrode layer 505, the tantalum oxide layer 106b,
- the variable resistance element 112 including the insufficient tantalum oxynitride layer 106a and the second electrode layer 507 is formed.
- variable resistance element 112 is covered to form a second interlayer insulating layer 108 (500 to 1000 nm).
- a second interlayer insulating layer 108 500 to 1000 nm.
- the second contact hole 109 and the second contact plug 110 are formed by the same manufacturing method as in FIGS. 2 (a) to (e). Thereafter, the second contact plug 110 is covered, and the second wiring 111 is formed. After forming the second wiring 111, heat treatment is performed for 10 minutes in a furnace heated to 400 ° C. for the purpose of preventing corrosion of the aluminum constituting the second wiring 111, thereby completing the nonvolatile memory element 11.
- the oxynitrogen-deficient tantalum oxynitride material layer 106a ′ is exposed to an oxygen plasma atmosphere.
- the surface of the oxynitrogen-deficient tantalum oxynitride material layer 106a ' is oxidized, and the resistance change layer 106 having a desired oxygen concentration profile cannot be obtained.
- the oxynitrogen-deficient tantalum oxynitride material layer 106a ′ is not exposed to oxygen plasma, in the step of forming the tantalum oxide material layer 106b ′ shown in FIG.
- the tantalum oxide material layer 106b ′ can be formed by a reactive sputtering method using tantalum as a target and oxygen as a reaction gas.
- the film formation rate of the tantalum oxide material layer 106b ′ when formed by the reactive sputtering method is 6 nm / min, and the manufacturing method (film formation rate: 1.2 nm / min) shown in FIG. Compared to 5 times faster.
- the film formation rate can be increased, and the nonvolatile memory element 11 can be manufactured at a lower cost than the nonvolatile memory element 10.
- Embodiment 3 Next, Embodiment 3 according to one embodiment of the present invention will be described.
- the nonvolatile memory element according to this embodiment is different from the nonvolatile memory element according to Embodiment 1 in that a plurality of the nonvolatile memory elements described in Embodiments 1 and 2 are stacked. It is.
- FIG. 12 is a cross-sectional view showing a configuration example of the nonvolatile memory element 12 according to the embodiment of the present invention.
- the nonvolatile memory element 10 shown in FIG. 1A has a configuration in which two layers are stacked using the second wiring in common.
- a silicon oxide film or the like (500 to 1000 nm) formed on the second interlayer insulating layer 108 of the nonvolatile memory element 10 shown in FIG. ),
- a third contact hole 114 (diameter: 50 to 300 nm) formed through the third interlayer insulating layer 113, and tungsten inside the third contact hole 114.
- a variable resistance element 112 ′ having the same configuration as the variable resistance element 112 is formed on the third interlayer insulating layer 113 so as to cover the third contact plug 115.
- a third wiring 119 is formed on the fourth interlayer insulating layer 116 so as to cover the fourth contact plug 118.
- variable resistance layer 106 ′ constituting the variable resistance element 112 ′ has a two-layer structure in which an oxynitrogen-deficient tantalum oxynitride layer 106 a and a tantalum oxide layer 106 b are stacked.
- the oxynitrogen-deficient tantalum oxynitride layer 106a constituting the resistance change layer 106 and the resistance change layer 106 ' has an effect of suppressing diffusion of oxygen due to a given thermal budget. Therefore, in the nonvolatile memory element 12, even if the amount of applied thermal budget is different, the difference between the oxygen concentration profile of the resistance change layer 106 and the oxygen concentration profile of the resistance change layer 106 'can be suppressed.
- nonvolatile memory element 12 illustrated in FIG. 12
- an example in which two layers of resistance change elements are stacked is shown, but it is needless to say that two or more layers may be stacked.
- the nonvolatile memory element 11 shown in FIG. 10 may be stacked instead of the nonvolatile memory element 10 shown in FIG. 1A.
- the electrode in contact with the tantalum oxide layer is a standard electrode from the standard electrode potential of tantalum, such as Au (gold), Pt (platinum), Ir (iridium), Pd (palladium), Cu (copper), and Ag (silver). It is preferable to use one or a plurality of materials having a high potential.
- an electrode that is not in contact with the tantalum oxide layer that is, an electrode that is in contact with the oxynitrogen-deficient tantalum oxynitride layer is a material having a standard electrode potential lower than the standard electrode potential of tantalum, such as W, Ni and TaN. It is preferably constructed using one or more materials. With such a configuration, the resistance change operation in the resistance change layer can be generated only at the interface between the tantalum oxide layer and the electrode in contact therewith, and a stable resistance change operation can be realized. .
- nonvolatile memory element is not limited to a configuration in which two layers are stacked using the second wiring in common, and may be a configuration in which three or more layers are stacked.
- the nonvolatile memory element may have a configuration in which a plurality of the nonvolatile memory elements described above are provided and the nonvolatile memory elements are two-dimensionally arranged. Furthermore, a configuration in which a plurality of such two-dimensional arrangements are stacked may be used.
- the nonvolatile memory element and the manufacturing method thereof according to the present invention have an effect of suppressing deterioration of the oxygen concentration profile of the resistance change layer due to a thermal budget.
- the nonvolatile memory element and the manufacturing method thereof according to the present invention have an effect that the nonvolatile memory element can operate at a low voltage, and as a nonvolatile memory element such as a ReRAM using a resistance change element. It is valid.
- Nonvolatile memory element 100 Substrate 101 First wiring 102 First interlayer insulating layer 103 First contact hole 104 First contact plug 105 First electrode layer 105 ′ First electrode material layer 106 Resistance change layer 106 ′ Resistance Change layer 106a Oxygen-nitrogen-deficient tantalum oxynitride layer 106a 'Oxygen-nitrogen-deficient tantalum oxynitride material layer 106b Tantalum oxide layer 106b' Tantalum oxide material layer 106c Local region 107 Second electrode layer 107 'Second electrode material Layer 108 Second interlayer insulating layer 109 Second contact hole 110 Second contact plug 111 Second wiring 112 Resistance change element 112 ′ Resistance change element 113 Third interlayer insulation layer 114 Third contact hole 115 Third contact plug 116 Fourth interlayer Insulating layer 117 Contact holes 118 fourth contact plug 119 third wire 505 first electrode layer 505 'first electrode material layer 507 second electrode layer 507' second electrode material layer
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Abstract
Description
0.8≦x+y≦1.9
0<y≦0.5
を満足し、且つ前記タンタル酸化物層の組成をTaOzと表すと、zは
x+y<z
を満足することが好ましい。
[不揮発性記憶素子の構成]
図1Aは、本発明の実施の形態1に係る不揮発性記憶素子10の概略構成を示す断面図である。
図2の(a)から(k)は本実施の形態に係る、不揮発性記憶素子10の製造方法を示す断面図である。これらを用いて、不揮発性記憶素子10の要部の製造方法について説明する。
次に、酸窒素不足型タンタル酸窒化物材料層106a’の成膜条件と抵抗率の関係について説明する。
次に、酸窒素不足型タンタル酸窒化物材料層106a’の組成について説明する。
次に、タンタル酸化物材料層106b’の抵抗率と組成について説明する。抵抗変化素子112の初期抵抗値の大小は、タンタル酸化物材料層106b’の組成をTaOzと示したときのz値に依存する。
図6は、TaOxNyで表される組成を有する酸窒素不足型タンタル酸窒化物材料層106a’のx値およびy値と、不揮発性記憶素子の初期抵抗値との関係を示す図である。図6では、x値およびy値を0.8≦x+y≦1.9、0<y≦0.5の範囲で変更して初期抵抗値を計測している。具体的には、y値が0、0.22、0.4であり、x値が0.4~1.42である酸窒素不足型タンタル酸窒化物材料層106a’を用いた不揮発性記憶素子10の初期抵抗値を示している。また、図6に示した初期抵抗値の各点におけるx値を図6中に記載している。
次に、実施例および比較例のメモリとしての動作例、すなわち情報の書き込み/読み出しをする場合の動作例について説明する。
次に、本発明の一形態に係る実施の形態2について説明する。本実施の形態に係る不揮発性記憶素子が実施の形態1に係る不揮発性記憶素子と異なる点は、不揮発性記憶素子の抵抗変化層において、酸窒素不足型タンタル酸窒化物層の上にタンタル酸化物層が配置されている点である。
図10は、図1Aに記載した不揮発性記憶素子10の変形例である、不揮発性記憶素子11の断面図である。図10において、図1Aと同じ構成要素については同じ符号を用い、説明を省略する。図10に示すように、不揮発性記憶素子11と不揮発性記憶素子10との違いは、抵抗変化素子112の配置を上下逆にした点にある。
図11の(a)から(k)は本実施の形態に係る、不揮発性記憶素子11の製造方法を示す断面図である。これらを用いて、不揮発性記憶素子11の要部の製造方法について説明する。
次に、本発明の一形態に係る実施の形態3について説明する。本実施の形態に係る不揮発性記憶素子が実施の形態1に係る不揮発性記憶素子と異なる点は、実施の形態1および実施の形態2に示した不揮発性記憶素子が複数層積層されている点である。
100 基板
101 第1配線
102 第1層間絶縁層
103 第1コンタクトホール
104 第1コンタクトプラグ
105 第1電極層
105’ 第1電極材料層
106 抵抗変化層
106’ 抵抗変化層
106a 酸窒素不足型タンタル酸窒化物層
106a’ 酸窒素不足型タンタル酸窒化物材料層
106b タンタル酸化物層
106b’ タンタル酸化物材料層
106c 局所領域
107 第2電極層
107’ 第2電極材料層
108 第2層間絶縁層
109 第2コンタクトホール
110 第2コンタクトプラグ
111 第2配線
112 抵抗変化素子
112’ 抵抗変化素子
113 第3層間絶縁層
114 第3コンタクトホール
115 第3コンタクトプラグ
116 第4層間絶縁層
117 第4コンタクトホール
118 第4コンタクトプラグ
119 第3配線
505 第1電極層
505’ 第1電極材料層
507 第2電極層
507’ 第2電極材料層
Claims (11)
- 基板上に形成された第1電極層と、
前記第1電極層上に配置された抵抗変化層と、
前記抵抗変化層上に配置された第2電極層とを備え、
前記抵抗変化層は、酸窒素不足型タンタル酸窒化物層と、タンタル酸化物層とが積層された2層構造を有している
不揮発性記憶素子。 - 前記抵抗変化層は、
前記タンタル酸化物層から前記酸窒素不足型タンタル酸窒化物層へ酸素イオンが移動することにより低抵抗化し、
前記酸窒素不足型タンタル酸窒化物層から前記タンタル酸化物層へ酸素イオンが移動することにより高抵抗化する
請求項1に記載の不揮発性記憶素子。 - 前記酸窒素不足型タンタル酸窒化物層の組成をTaOxNyと表すと、xとyは
0.8≦x+y≦1.9
0<y≦0.5
を満足し、且つ
前記タンタル酸化物層の組成をTaOzと表すと、zは
x+y<z
を満足する
請求項1または2に記載の不揮発性記憶素子。 - 前記酸窒素不足型タンタル酸窒化物層の厚さは、前記タンタル酸化物層の厚さよりも厚い
請求項1~3のいずれか1項に記載の不揮発性記憶素子。 - 前記酸窒素不足型タンタル酸窒化物層は、導電性を有している
請求項1~4のいずれか1項に記載の不揮発性記憶素子。 - 前記タンタル酸化物層に接する電極は、タンタルの標準電極電位より標準電極電位が高い材料のうちの1つまたは複数の材料を用いて構成される
請求項1~5のいずれか1項に記載の不揮発性記憶素子。 - 前記酸窒素不足型タンタル酸窒化物層に接する電極は、タンタルの標準電極電位より標準電極電位が低い材料のうちの1つまたは複数の材料を用いて構成される
請求項1~6のいずれか1項に記載の不揮発性記憶素子。 - 前記タンタル酸化物層に接する電極は、Au、Pt、Ir、Pd、CuおよびAgのうちの1つまたは複数の材料を用いて構成される
請求項6に記載の不揮発性記憶素子。 - 前記酸窒素不足型タンタル酸窒化物層に接する電極は、W、NiおよびTaNのうちの1つまたは複数の材料を用いて構成される
請求項7に記載の不揮発性記憶素子。 - 基板上に、第1電極層を構成する第1電極材料層を形成する工程(a)と、
前記第1電極材料層上に、酸窒素不足型タンタル酸窒化物層を構成する酸窒素不足型タンタル酸窒化物材料層を形成する工程(b)と、
前記酸窒素不足型タンタル酸窒化物材料層上に、タンタル酸化物層を構成するタンタル酸化物材料層を形成する工程(c)と、
前記タンタル酸化物材料層上に、第2電極層を構成する第2電極材料層を形成する工程(d)とを有しており、
前記工程(b)において、前記酸窒素不足型タンタル酸窒化物材料層を、スパッタリング法により形成する
不揮発性記憶素子の製造方法。 - 基板上に、第2電極層を構成する第2電極材料層を形成する工程(a)と、
前記第2電極材料層上に、タンタル酸化物層を構成するタンタル酸化物材料層を形成する工程(b)と、
前記タンタル酸化物材料層上に、酸窒素不足型タンタル酸窒化物層を構成する酸窒素不足型タンタル酸窒化物材料層を形成する工程(c)と、
前記酸窒素不足型タンタル酸窒化物材料層上に、第1電極層を構成する第1電極材料層を形成する工程(d)と、を有しており、
前記工程(c)において、前記酸窒素不足型タンタル酸窒化物材料層を、スパッタリング法により形成する
不揮発性記憶素子の製造方法。
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WO2013080452A1 (ja) * | 2011-12-02 | 2013-06-06 | パナソニック株式会社 | 不揮発性記憶素子および不揮発性記憶装置 |
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US9000506B2 (en) | 2015-04-07 |
US20130001504A1 (en) | 2013-01-03 |
CN102714210B (zh) | 2015-08-12 |
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