WO2006075574A1

WO2006075574A1 - Resistance change element and manufacturing method thereof

Info

Publication number: WO2006075574A1
Application number: PCT/JP2006/300142
Authority: WO
Inventors: Akihiro Sakai; Hideaki Adachi; Akihiro Odagawa; Tsutomu Kanno; Yasunari Sugita; Kiyoshi Ohnaka
Original assignee: Matsushita Electric Industrial Co., Ltd.
Priority date: 2005-01-14
Filing date: 2006-01-10
Publication date: 2006-07-20
Also published as: JP2008060091A

Abstract

There are provided a resistance change element having an excellent heat resistance for suppressing degrading of resistance change characteristic upon temperature increase as compared to a conventional element and a manufacturing method of the element. The resistance change element includes a substrate and a multi-layered structure arranged on the substrate. The multi-layered structure has an upper electrode, a lower electrode, and a resistance change layer arranged between the upper electrode and the lower electrode. The resistance change element has at least two states when the electric resistance value of the upper electrode is different from that of the lower electrode. By applying a predetermined electric pulse between the upper electrode and the lower electrode, the state is changed from selected one of the at least two states to another state. The resistance change layer has a composition expressed by Expression (Pr, Ca)MnOx1 and the multi-layered structure further includes at least one electrode selected from the upper electrode and the lower electrode and an oxygen lacking layer having a composition expressed by Expression (Pr, Ca)MnOx2. Here, x1 and x2 satisfy the following: 0 < x1 ≤ 3, 0 < x2 < 3, and x2 < x1.

Description

Specification

Resistance change element and manufacturing method thereof

Technical field

The present invention relates to a resistance change element that changes its resistance value by applying an electric pulse, and a manufacturing method thereof.

Background art

Memory elements are used in a wide range of fields as important basic electronic components that support the information society. In recent years, with the widespread use of portable information terminals, there has been an increasing demand for miniaturization of memory elements, and nonvolatile memory elements are no exception. However, as device miniaturization reaches the nanometer range, conventional charge storage type memory devices (typically DRAM: Dynamic Random Access Memory) have the same charge capacity per information unit (bit). The decline is becoming a problem, and various improvements have been made to avoid this problem, but there are concerns about future technological limitations.

[0003] As a memory element that is not easily affected by miniaturization, attention is focused on a nonvolatile memory element (resistance change type memory element) that records information by changing the electric resistance R that is not the charge capacity C. As such a resistance change type memory element, US Pat. No. 6,204,139 discloses an element using perovskite oxide (Pr Ca MnO: PCMO).

0.7 0.3 3

[0004] An element disclosed in US Pat. No. 6,204,139 has a structure in which a lower electrode 101, a PCMO layer 102, and an upper electrode 103 are sequentially laminated, as shown in FIG. The resistance value of the PCMO layer 102 can be changed by applying a predetermined current or voltage between the upper electrode 103 and the lower electrode 101.

[0005] An element using such a change in resistance value is not easily affected by miniaturization, and can improve the recording speed and the erasing speed as compared with a flash memory widely used as a nonvolatile memory element in recent years. Therefore, practical application to next-generation memory devices is expected.

[0006] However, the element disclosed in US Pat. No. 6,204,139 has a problem that its resistance change characteristic deteriorates as the temperature rises. For example, one of the inventors in the patent, te Gunashev (Ignatiev [In Proceedings of 15th International bvmposium on Integrated Ferroelectronics (ISIF 2003), p. 584—585 (2003), the resistance change rate of an element having the same structure as that of the element disclosed in US Pat. No. 6,204,139 decreases near 100 ° C. I will report that.

[0007] Since electronic devices such as memory cells are expected to be used in a wide range of applications, elements incorporated in the device are required to be able to cope with changes in environmental temperature in which the device is used. For example, JIS (Enomoto Industrial Standard) that defines the heat resistance environment test method for electronic devices. 60068— 2—2: 1995 (former JIS C0021: 1995), 200. The heat resistance of C is specified, and it is difficult to use the above-mentioned element whose resistance change characteristic deteriorates in the temperature range near 100 ° C as a commercially available device.

Accordingly, an object of the present invention is to provide a resistance change element having excellent heat resistance in which deterioration of resistance change characteristics at the time of temperature rise is suppressed as compared with a conventional element, and a method for manufacturing the resistance change element. To do.

[0009] Note that US Pat. No. 6,972,238 (the same content as JP-A-2004-349690) can be cited as a document closely related to the present application. Differences between the technical contents disclosed in this document and the present invention will be described in the section of the best mode for carrying out the invention.

Disclosure of the invention

[0010] The resistance change element of the present invention includes a substrate and a multilayer structure disposed on the substrate, and the multilayer structure includes an upper electrode and a lower electrode, and between the upper electrode and the lower electrode. There are two or more states in which the electric resistance value between the upper electrode and the lower electrode is different, and a predetermined value is provided between the upper electrode and the lower electrode. It is an element that changes from one state selected from the two or more state forces to another state by applying an electric pulse. Here, the variable resistance layer has a composition represented by the formula (Pr, Ca) MnO xl, and the multilayer structure includes at least one electrode selected from the upper electrode and the lower electrode force, and the It further includes an oxygen-deficient layer having a composition represented by the formula (Pr, Ca) MnO and disposed between the resistance change layer. However, xl and x2

And x2 are numerical values satisfying 0 <xl≤3, 0 <x2 <3, and x2 <xl.

In the resistance change element of the present invention, the oxygen deficient layer can suppress deterioration of the resistance change characteristic of the element at the time of temperature rise, and is an element having higher heat resistance than the conventional resistance change element. be able to.

The variable resistance element manufacturing method (first manufacturing method) of the present invention is the above variable resistance element manufacturing method of the present invention, comprising: a lower electrode forming step of forming a lower electrode on a substrate; A variable resistance layer having a composition represented by the formula (Pr, Ca) MnO is formed on the lower electrode.

xl

Forming a variable resistance layer, forming an oxygen deficient layer having a composition represented by the formula (Pr, Ca) MnO on the variable resistance layer, and forming the variable resistance layer and the oxygen deficient layer. And an upper electrode forming step of forming an upper electrode sandwiching the lower electrode together with the lower electrode. However, xl and x2 are numerical values satisfying 0 <xl≤3, 0 <x2 <3, and x2 <xl, respectively.

[0013] A variable resistance element manufacturing method (second manufacturing method) according to the present invention is the above variable resistance element manufacturing method according to the present invention, comprising: a lower electrode forming step of forming a lower electrode on a substrate; An oxygen deficient layer forming step for forming an oxygen deficient layer having a composition represented by the formula (Pr, Ca) MnO on the lower electrode, and a formula (Pr, Ca) MnO represented on the oxygen deficient layer.

xl

A variable resistance layer forming step for forming a variable resistance layer having a composition, and an upper electrode forming step for forming an upper electrode for sandwiching the oxygen deficient layer and the variable resistance layer together with the lower electrode. is there. However, xl and χ2 are numerical values satisfying 0 <xl≤3, 0 <χ2 <3, and χ2 <xl, respectively.

Brief Description of Drawings

FIG. 1 is a cross-sectional view schematically showing an example of a variable resistance element according to the present invention.

FIG. 2 is a cross-sectional view schematically showing another example of the variable resistance element of the present invention.

FIG. 3 is a cross-sectional view schematically showing another example of the variable resistance element of the present invention.

FIG. 4 is a schematic diagram showing an example of a resistance change type memory including the resistance change element of the present invention.

FIG. 5A is a process diagram schematically showing an example of a method of manufacturing a resistance change element according to the present invention.

FIG. 5B is a process diagram schematically showing an example of a method of manufacturing a variable resistance element according to the present invention. [FIG. 5C] FIG. 5C is a process chart schematically showing an example of a method of manufacturing a variable resistance element according to the present invention.

FIG. 5D is a process diagram schematically showing an example of a method of manufacturing a variable resistance element according to the present invention.

FIG. 5E is a process diagram schematically showing an example of a method of manufacturing a resistance change element according to the present invention.

[FIG. 5F] FIG. 5F is a process chart schematically showing an example of a method of manufacturing a resistance change element according to the present invention.

FIG. 6A is a process diagram schematically showing an example of a method of manufacturing a resistance change element according to the present invention.

FIG. 6B is a process diagram schematically showing an example of a method of manufacturing a resistance change element according to the present invention.

[FIG. 6C] FIG. 6C is a process chart schematically showing an example of a method of manufacturing a variable resistance element according to the present invention.

[FIG. 6D] FIG. 6D is a process chart schematically showing an example of a method of manufacturing a variable resistance element according to the present invention.

[FIG. 6E] FIG. 6E is a process chart schematically showing an example of a method of manufacturing a variable resistance element according to the present invention.

[FIG. 6F] FIG. 6F is a process chart schematically showing an example of a method of manufacturing a variable resistance element according to the present invention.

[FIG. 6G] FIG. 6G is a process chart schematically showing an example of a method of manufacturing a resistance change element according to the present invention.

FIG. 7A is a process diagram schematically showing an example of a method of manufacturing a resistance change element according to the present invention.

FIG. 7B is a process diagram schematically showing an example of a method of manufacturing a variable resistance element according to the present invention.

[FIG. 7C] FIG. 7C is a process chart schematically showing an example of a method of manufacturing a variable resistance element according to the present invention. FIG. 7D is a process diagram schematically showing an example of a method of manufacturing a resistance change element according to the present invention.

[FIG. 7E] FIG. 7E is a process chart schematically showing an example of a method of manufacturing a variable resistance element according to the present invention.

[FIG. 7F] FIG. 7F is a process chart schematically showing an example of the method of manufacturing a resistance change element according to the present invention.

[FIG. 7G] FIG. 7G is a process chart schematically showing an example of a method of manufacturing a resistance change element according to the present invention.

[FIG. 7H] FIG. 7H is a process chart schematically showing an example of a method of manufacturing a resistance change element according to the present invention.

FIG. 8 is a cross-sectional view schematically showing an example of a conventional variable resistance element.

BEST MODE FOR CARRYING OUT THE INVENTION

In the variable resistance element of the present invention, the variable resistance layer is represented by the formula (Pr, Ca) MnO.

Three

It may have a composition.

In the variable resistance element of the present invention, the oxygen deficient layer and the variable resistance layer may be in contact with each other, and the oxygen deficient layer and the at least one electrode may be in contact with each other.

In the variable resistance element of the present invention, the multilayer structure may include only the oxygen deficient layer and the variable resistance layer as an oxide layer containing Pr, Ca, and Mn.

[0018] In the resistance change element of the present invention, the multilayer structure may include the oxygen deficient layer, the resistance change layer, the upper electrode, and the lower electrode.

In the resistance change element of the present invention, the oxygen deficient layer is represented by the formula Pr Ca MnO and p 1-p x2

It may have a composition. However, p is 0.6 or more and 0.8 or less.

[0020] In the resistance change element of the present invention, p 1-p xl is expressed by the resistance change layer force formula Pr Ca MnO.

It may have a composition. However, p is 0.6 or more and 0.8 or less.

In the first manufacturing method of the present invention, xl = 3 may be satisfied.

In the first manufacturing method of the present invention, in the oxygen deficient layer forming step, the oxygen deficient layer may be formed by reverse sputtering the surface of the variable resistance layer. At this time, xl = 3 may be satisfied. Further, the variable resistance layer may be formed in contact with the lower electrode, and the upper electrode may be formed in contact with the oxygen deficient layer formed on the surface of the variable resistance layer.

In the first production method of the present invention, in the oxygen deficient layer forming step, the oxygen deficient layer is formed by heat-treating the surface of the variable resistance layer in a non-oxidizing atmosphere. May be. At this time, xl = 3 may be satisfied. The resistance change layer may be formed so as to be in contact with the lower electrode, and the upper electrode may be formed so as to be in contact with the oxygen deficient layer formed on the surface of the resistance change layer.

In the first manufacturing method of the present invention, the partial pressure P ratio (P

inert and partial pressure of oxygen P)

/ P with oxy

Oxy inert may be larger than the ratio (P / P) of the atmosphere in the oxygen deficient layer forming step.

oxy inert

[0025] In the first manufacturing method of the present invention, in the variable resistance layer forming step, the variable resistance layer is formed by sputtering, and in the oxygen deficient layer forming step, the oxygen deficient layer is formed by sputtering. Also good.

In the second production method of the present invention, the partial pressure P (P / P) of the inert gas that the atmosphere in the variable resistance layer forming step has

inert and partial pressure of oxygen P

Ratio with oxy

oxy inert

In the second production method of the present invention, in the oxygen deficient layer forming step, the oxygen deficient layer is formed by sputtering, and in the variable resistance layer forming step, the variable resistance layer is formed by sputtering. Also good.

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

A resistance change element 1 shown in FIG. 1 includes a substrate 12, a pair of electrodes having a lower electrode 2 and an upper electrode 4, and a resistance change layer 3 sandwiched between the lower electrode 2 and the upper electrode 4. Contains. In addition, in the element 1, an oxide force including Pr (prasedium), Ca (calcium), and Mn (manganese) is provided between the upper electrode 4 and the resistance change layer 3 in the same manner as the resistance change layer 3. An oxygen-deficient layer 5 having a composition different from that of 3 is arranged. The lower electrode 2, the resistance change layer 3, the oxygen deficient layer 5, and the upper electrode 4 are arranged on the substrate 12 in the above order as a multilayer structure (laminated body) 11. The resistance change layer 3 has a composition A represented by the formula (Pr, Ca) MnO, and the oxygen deficient layer 5

xl

The yarn has the formula B expressed by the formula (Pr, Ca) MnO. Here, xl and x2 are values satisfying 0 <xl≤3, 0 <x2 <3, x2 and xl, respectively, and the oxygen deficiency layer 5 has an oxygen deficiency rate higher than that of the resistance change layer 3. Can be said to be a large layer. The resistance change layer 3 may have a composition represented by the formula (Pr, Ca) MnO (xl = 3).

Three

It meets the stoichiometric ratio.

[0031] The fractions of Pr and Ca in the yarn and composition A and the fraction in the yarn and composition B may be the same or different, but if they are the same, the oxygen deficient layer 5 It can be said that this is a layer in which the oxygen deficiency rate in the change layer 3 is increased.

[0032] In element 1, there are two or more states in which the electric resistance value between lower electrode 2 and upper electrode 4 is different, and a predetermined electric pulse is applied to element 1, specifically, lower electrode 2 and upper electrode 4. By applying between the electrode 4 and the electrode 4, the element 1 changes to one state force selected from the above-described two or more state forces to another state. If element 1 has two states with different electrical resistance values (relatively high resistance state A and relatively low resistance state B), device 1 will be in the state by applying a predetermined electrical pulse. Change from A to state B, or from state B to state A. The predetermined electric pulse is applied to the resistance change layer 3 and can be obtained.

[0033] By adopting such a resistance change element 1, it is possible to suppress the deterioration of the resistance change characteristic of the element at the time of temperature rise. In other words, the element 1 has better heat resistance than the conventional resistance change element, and the degree depends on the configuration of the element 1, but as shown in the examples described later, for example, even at 200 ° C., It can maintain a resistance change rate almost equal to (25 ° C). The specific value of the resistance change rate of the element 1 is a force depending on the configuration of the element 1, for example, 600% or more. The resistance change rate is a numerical value that serves as an index of the resistance change characteristic of the element. Specifically, the maximum electric resistance value indicated by the element is R

MAX, minimum electrical resistance R

When IN, the expression (R — R

MAX

) / R X 100 (%).

[0034] The oxygen deficient layer 5 and the resistance change layer 3 are not necessarily in contact. For example, an arbitrary layer may be disposed between the two, but as shown in FIG. It is preferable that they touch each other. Similarly, regarding the relationship between the oxygen deficient layer 5 and the upper electrode 4, an arbitrary layer may be disposed between the two, but it is preferable that the two are in contact with each other. Oxygen deficient layer 5 And the resistance change layer 3 are in contact with each other, the boundary between them may not necessarily be clear.

A laminated body 11 shown in FIG. 1 may include a force laminated body 11 including a lower electrode 2, an upper electrode 4, a resistance change layer 3, and an oxygen deficient layer 5, and may include any layer other than the above layers. At this time, it is preferable that the laminate 11 includes only the resistance change layer 3 and the oxygen deficient layer 5 having the above-described composition A and composition B, respectively, as the oxide layer containing Pr, Ca, and Mn.

FIG. 2 shows another example of the resistance change element 1 of the present invention. In the element 1 shown in FIG. 2, the oxygen deficient layer 5 is disposed between the lower electrode 2 and the resistance change layer 3, and the lower electrode 2, the oxygen deficient layer 5, the resistance change layer 3 and the upper electrode 4 are The laminated body 11 is arranged on the substrate 12 in the above order. By adopting such a resistance change element 1, it is possible to suppress the deterioration of the resistance change characteristic of the element at the time of temperature rise.

[0037] The oxygen deficient layer 5 and the lower electrode 2 are not necessarily in contact with each other. For example, an arbitrary layer may be disposed between the two, but as shown in FIG. It is preferable to touch.

FIG. 3 shows another example of the variable resistance element 1 of the present invention. In the element 1 shown in FIG. 3, the two oxygen deficient layers 5a and 5b are disposed between the lower electrode 2 and the resistance change layer 3, and between the upper electrode 4 and the resistance change layer 3, respectively. In the element 1 shown in FIG. 3, the lower electrode 2, the oxygen deficient layer 5a, the resistance change layer 3, the oxygen deficient layer 5b, and the upper electrode 4 are arranged on the substrate 12 as the stacked body 11 in the order described above. By adopting such a resistance change element 1, it is possible to suppress the deterioration of the resistance change characteristic of the element at the time of temperature rise.

The resistance change layer 3 only needs to satisfy the above composition A. For example, the formula Pr Ca MnO (0 p 1-p xl

6≤p≤0. 8) It is sufficient to have the thread and the condition indicated by 8).

[0040] The oxygen-deficient layer 5 only needs to satisfy the above-mentioned yarn composition B. For example, the formula Pr Ca MnO (0 p 1-p x2

[0041] The yarn formation of the resistance change layer 3 and the oxygen deficient layer 5 may be evaluated by an analytical method such as Auger electron spectroscopy.

[0042] The lower electrode 2 is typically metallic if it has electrical conductivity. For example, Pt (platinum), Ir (iridium), and alloys thereof may be used. [0043] It is preferable that the lower electrode 2 also has a material force capable of crystallizing the variable resistance layer 3 and the Z or oxygen deficient layer 5 on the surface thereof. In this case, the resistance change layer 3 and the Z or oxygen deficient layer 5 having a stable crystal structure can be formed on the lower electrode 2, and the resistance change layer 3 and the Z or oxygen deficient layer 5 on the lower electrode 2 can be formed. Can be formed more easily. As such a lower electrode 2, for example, from SrRuO, SrTiO, or Nb, Cr and La

3 3

Similar to (Pr, Ca) MnO, such as SrTiO doped with at least one selected element

3 3 An electrode made of a conductive oxide having a crystal structure can be mentioned.

[0044] The upper electrode 4 should basically have conductivity. For example, Au (gold), Pt (platinum), Ru (ruthenium), Ir (iridium), Ti (titanium), A1 (Aluminum), Cu (copper), Ta (tantalum), their alloys (eg, iridium-tantalum alloy (Ir—Ta)), oxides (eg, tin-doped indium oxides (ITO )), Nitrides, fluorides, carbides, borides and the like.

The substrate 12 is not particularly limited as long as the multilayer body 11 can be disposed on the substrate 12, and may be, for example, a silicon (Si) substrate or an MgO substrate. When the substrate 12 is a Si substrate, the combination of the resistance change element of the present invention and the semiconductor element becomes easy. At this time, the surface of the substrate 12 in contact with the lower electrode 2 may be oxidized, that is, an oxide film may be formed on the surface of the substrate 12.

[0046] The structure of the resistance change element of the present invention is such that a laminate 11 including a lower electrode 2, a resistance change layer 3, an oxygen deficient layer 5 and an upper electrode 4 is formed on a substrate 12, and the resistance change layer 3 is The oxygen deficient layer 5 is sandwiched between the lower electrode 2 and the upper electrode 4, and is arranged between at least one electrode selected from the lower electrode 2 and the upper electrode 4 and the resistance change layer 3. As long as it is not particularly limited. For example, as shown in FIG. 3, the stacked body 11 may include two or more oxygen-deficient layers 5, and although not illustrated, the stacked body 11 may include two or more resistance change layers 3.

[0047] By the application of a predetermined electric pulse, the state force in element 1 changes, for example, from state A to state B, but the changed state B is maintained until a predetermined electric pulse is applied to element 1 again. Then, by applying the electric pulse, for example, state B force state A is changed again. However, the predetermined electrical pulse applied to element 1 is when element 1 is in state A. The size, polarity, pulse shape, and the like that do not necessarily have to be the same between the state B and the state B may differ depending on the state of the element 1. That is, the “predetermined electric pulse” in this specification is an electric pulse that can change to another state different from the state when the element 1 is in a certain state.

Thus, in the resistance change element 1, since the electric resistance value can be held until a predetermined electric pulse is applied to the element 1, a mechanism for detecting the state of the element 1 and the element 1, that is, A nonvolatile resistance change memory can be constructed by combining a mechanism for detecting the electric resistance value of the element 1 and assigning a bit to each of the above states. For the bit assignment, for example, state A may be “0” and state B may be “1”. The resistance change type memory includes a memory array in which two or more memory elements are arranged in addition to the memory elements. Also, by assigning ON or OFF to each of the above states, element 1 can be applied to a switching element.

[0049] The electric pulse to be applied may be a voltage (pulse voltage) or a current (current pulse). The shape of the pulse is not particularly limited, and may be any shape as long as it is a sine wave shape, a rectangular wave shape, and a triangular wave force. The width of the pulse is usually in the range of a few nanoseconds to a few milliseconds.

[0050] In this case, it is preferable to apply a Nors voltage as the electrical norse. In this case, the element 1 can be miniaturized and the electronic device constructed using the element 1 can be more easily downsized. In the case of the element 1 in which the above two states A and B exist, a potential difference applying mechanism that generates a potential difference between the lower electrode 2 and the upper electrode 4 is connected to the element 1. By applying a bias voltage (positive bias voltage) that makes the potential of the upper electrode 4 positive with respect to the potential, the device 1 is changed from the state A to the state B, and the potential of the lower electrode 2 is On the other hand, a negative voltage (negative bias voltage) that causes the potential of the upper electrode 4 to be negative is applied to the element 1 (that is, the voltage with the polarity reversed when changing from state A to state B). Device 1 may be changed from state B to state A by applying. For example, a pulse generator may be used as the potential difference applying mechanism.

[0051] The resistance change element according to the present invention is combined with a semiconductor element, for example, a transistor such as a diode or a MOS field effect transistor (MOS-FET) to change the resistance. A type memory can be constructed.

FIG. 4 shows an example of a resistance change memory (element) in which the resistance change element of the present invention and a MOS-FET are combined.

A resistance change type memory element 31 shown in FIG. 4 includes a resistance change element 1 and a transistor 21, and the element 1 is electrically connected to the transistor 21 and the bit line 32. The gate electrode of the transistor 21 is electrically connected to the word line 33, and the remaining one electrode in the transistor 21 is grounded. In such a memory element 31, the transistor 21 can be used as a switching element to detect the above state in the element 1 (that is, to detect the electric resistance value of the element 1) and to apply a predetermined electrical noise to the element 1. It becomes. For example, when the element 1 takes two states having different electric resistance values, the memory element 31 shown in FIG. 4 can be a 1-bit resistance change memory element.

[0054] Recording of information in the memory element 31 may be performed by applying a predetermined electric pulse to the resistance change element 1. Reading of information recorded in the element 1 may be performed by, for example, a pulse voltage applied to the element 1. Alternatively, the current pulse may be changed by changing the magnitude of the current pulse.

[0055] For example, the element 1 has a pulsed positive bias voltage having a magnitude equal to or greater than a certain threshold value (V).

0

Applying (SET voltage V: I V I ≥V) changes from state A to state B, and a certain threshold (s S 0

V) pulse-like negative noise voltage (RESET voltage V: V

0, RS I RS I≥

It is assumed that the state B force changes to the state A by applying V).

0,

[0056] Here, a positive bias voltage having a magnitude of less than V or a negative bias having a magnitude of less than V

0 0 '

By applying a voltage to element 1, the electrical resistance value of element 1 can be detected as the current output of element 1. A voltage applied to detect the electric resistance value of the element 1 is defined as a READ voltage (V). The READ voltage is the same as the SET voltage and RESET voltage.

E

By using a pulse-like READ voltage even if it is in the form of a pulse, power consumption in the memory element 31 can be reduced and switching efficiency can be improved. When the READ voltage is applied, the state of the element 1 does not change, so even when the READ voltage is applied multiple times, the same electric resistance value can be detected.

[0057] As described above, by applying the pulse voltage to the element 1, information can be recorded and read from the memory element 31, and the magnitude of the output current of the element 1 obtained by the reading is as follows. Different depending on the state. Here, if the relatively large output current is “1” and the relatively small output current is “0”, the memory device 31 records information “1” by the SET voltage, and the RESET voltage. Thus, the memory device can record information “0” (delete information “1”).

[0058] The magnitude of the READ voltage is usually preferably about 1 Z4 to 1Z1000 with respect to the magnitude of the SET voltage and the RESET voltage. Specific values of the SET voltage and the RESET voltage are forces depending on the configuration of the resistance change element 1. Usually, the voltage is in the range of 0.1V to 20V, and the range of 1V to 12V is preferable.

The variable resistance element of the present invention can be formed, for example, by the method for manufacturing a variable resistance element of the present invention, which will be described in detail below.

In the manufacturing method of the present invention, after forming the lower electrode 2 on the substrate 12, the resistance change layer 3 having the composition A and the oxygen deficiency having the composition B are formed on the formed lower electrode 2. Layer 5 is formed. The composition of the variable resistance layer 3 to be formed is expressed by the formula (Pr, Ca) MnO.

3 composition (xl = 3), that is, a composition satisfying the stoichiometric ratio! / ヽ.

[0061] The order of forming the resistance change layer 3 and the oxygen deficiency layer 5 on the lower electrode 2, the number of the resistance change layers 3 and the oxygen deficiency layers 5 formed on the lower electrode 2, and the like are as follows. What is necessary is just to set suitably according to a structure. For example, a step of forming a lower electrode on the substrate (lower electrode forming step), a step of forming a resistance change layer having the composition A on the lower electrode (resistance change layer forming step), and the resistance change layer A step of forming an oxygen deficient layer having the above composition B (oxygen deficient layer forming step), a step of forming an upper electrode sandwiching the resistance change layer and the oxygen deficient layer together with the lower electrode (upper electrode forming step), May be performed in order (first manufacturing method). Further, for example, a lower electrode forming step, a step of forming an oxygen deficient layer having the above composition B on the lower electrode (oxygen deficient layer forming step), and a resistance change layer having the above composition A on the oxygen deficient layer The step of forming (resistance change layer forming step) and the upper electrode forming step may be sequentially performed (second manufacturing method). In the first and second production methods of the present invention, an optional step may be added between the above steps as necessary.

[0062] The lower electrode 2, the upper electrode 4, and the resistance change layer 3 apply a semiconductor manufacturing process, If it is formed by a general thin film formation process and microfabrication process. For example, pulsed laser deposition (PLD), ion beam deposition (IBD), cluster ion beam, and various types such as RF, DC, electron cyclotron resonance (ECR), helicon, inductively coupled plasma (ICP), and opposed target Sputtering, molecular beam epitaxy (MBE), ion plating, or the like may be used. In addition to these PVD (Physical Vapor D eposition) method, CVD (Chemical Vapor Deposition) method, MOCVD (Metal Organ ic Chemical Vapor Deposition) method, message ³ r method, MOD (Metal Organic Decomposition) method, or a sol-gel method, etc. May be used.

[0063] The microfabrication of each layer includes, for example, ion milling, RIE (Reactive Ion Etching), FIB (Focused Ion Beam) used in semiconductor manufacturing processes and magnetic device (such as magnetoresistive elements such as GMR and TMR) manufacturing processes. ) Or the like, and a photolithography technique using a stepper for forming a fine pattern, an electron beam (EB) method, or the like may be used in combination. For the planarization of the surface of each layer, for example, CMP (Chemical Mechanical Polishing), cluster ^ —— ion beam etching or the like may be used.

The same applies to an insulating layer deposition method, a microfabrication method, and a planarization method, which will be described later, and an electronic device such as a memory element or a memory array including the resistance change element of the present invention can be formed by the same method.

[0065] The method for forming the oxygen deficient layer 5 is not particularly limited, but for example, the following method may be used.

[0066] Method I In the first manufacturing method, after forming the resistance change layer 3, the resistance change layer

The oxygen deficient layer 5 is formed by reverse sputtering the surface of 3.

At this time, the composition of the resistance change layer 3 is a composition represented by the formula (Pr, Ca) MnO (xl = 3).

Three

It may be.

[0068] In Method I, the resistance change layer 3 and the oxygen deficient layer 5 that are in contact with each other can be formed.

In Method I, if the resistance change layer 3 is formed so as to be in contact with the lower electrode 2 and the upper electrode 4 is further formed so as to be in contact with the oxygen deficient layer 5 formed on the surface of the resistance change layer 3, FIG. Element 1 shown in Fig. 1 can be formed. [0070] Inverse sputtering may be performed by using the resistance change layer 3 as a target based on a general method. At this time, among the elements constituting the resistance change layer 3, the oxygen desorption degree is particularly large, so that the oxygen deficiency layer 5 can be formed by increasing the oxygen loss rate of the reverse-sputtered portion of the resistance change layer 3. .

[0071] The reverse sputtering is preferably performed in a non-oxidizing atmosphere, for example, in an atmosphere containing a reducing gas such as hydrogen and an inert gas such as Z or nitrogen or argon. Further, in order to prevent the resistance change layer 3 from being etched excessively at the time of reverse sputtering, it is desirable not to excessively increase the sputtering power to be input. The thickness of the oxygen-deficient layer 5 to be formed can be controlled by the time for performing reverse sputtering.

Method II In the first manufacturing method, after the variable resistance layer 3 is formed, the oxygen deficient layer 5 is formed by heat-treating the surface of the variable resistance layer 3 in a non-acidic atmosphere. .

Three

It may be.

In Method II, the resistance change layer 3 and the oxygen deficient layer 5 that are in contact with each other can be formed.

In Method II, if the resistance change layer 3 is formed in contact with the lower electrode 2 and the upper electrode 4 is further formed in contact with the oxygen deficient layer 5 formed on the surface of the resistance change layer 3, FIG. Element 1 shown in Fig. 1 can be formed.

[0076] The heat treatment may be performed based on a general method except that the heat treatment is performed in a non-oxidizing atmosphere. The non-oxidizing atmosphere may be an atmosphere containing a reducing gas such as hydrogen and an inert gas such as Z or nitrogen or argon. In the above heat treatment, among the elements constituting the resistance change layer 3, the desorption of oxygen is particularly promoted, so the oxygen deficiency rate of the heat-treated portion in the resistance change layer 3 is increased to form the oxygen deficiency layer 5. it can.

The temperature of the heat treatment is, for example, about 500 ° C. to 600 ° C. The time for the heat treatment may be about several minutes, although it depends on the thickness of the oxygen deficient layer 5 to be formed. In order to suppress an increase in the oxygen deficiency rate of the entire resistance change layer 3 due to heat being transferred to the entire resistance change layer 3, rapid temperature increase and temperature decrease after the heat treatment are desired during the heat treatment.

Method III In the first and second manufacturing methods, the ratio (P / P) between the partial pressure P of the inert gas and the partial pressure P of oxygen in the atmosphere in the variable resistance layer forming step is expressed as oxygen Deficiency The partial pressure ratio (P 1 / P 2) of the atmosphere in the layer forming process is increased. Oxy inert

In this case, method m changes the partial pressure of oxygen in the atmosphere in which each layer is formed, so that the resistance change layer 3 having a relatively small oxygen deficiency rate and the oxygen deficiency rate is relatively large. It can be said that this is a method of forming the oxygen deficient layer 5. The resistance change layer 3 is formed under a condition where the partial pressure of oxygen is relatively large, and the oxygen deficient layer 5 is formed under a condition where the partial pressure of oxygen is relatively small.

[0079] The method of forming the resistance change layer 3 and the oxygen deficient layer 5 is not particularly limited.

Any sputtering method may be used.

[0080] For example, when the resistance change layer 3 and the oxygen deficient layer 5 are formed using RF magnetron sputtering, when the resistance change layer 3 is formed, the partial pressure ratio between argon and oxygen (P / P oxy

)) To about 0.2 to 0.5 (conditions, when forming the oxygen deficient layer 5, the partial pressure ratio is

Ar

It should be around 0. 04-0. 1 (Condition B). Hereinafter, the partial pressure ratio between argon and oxygen is also simply referred to as “0 ZAr”.

2

When the variable resistance layer 3 is formed under the condition A, the oxygen deficient layer 5 can be formed in contact with the formed variable resistance layer 3 by changing to the condition B. Similarly, when the oxygen deficient layer 5 is formed under the condition B, the resistance change layer 3 can be formed in contact with the formed oxygen deficient layer 5 by changing to the condition A. The change to condition A or condition B may be performed continuously, intermittently or stepwise.

[0082] When the variable resistance layer 3 to be formed has a composition represented by the formula (Pr, Ca) MnO,

Three

Condition A is an oxide containing Pr, Ca, and Mn, and includes oxygen that is necessary and sufficient and not excessive to form the oxide satisfying the stoichiometric ratio. Condition B is oxygen It can be said that this is a condition for forming the oxide having defects.

[0083] Conditions A and B can be said to be sputtering conditions for forming the resistance change layer 3 and the oxygen deficient layer 5, respectively.

An example of the production method of the present invention is shown in FIGS. 5A to 5F.

First, the lower electrode 2 is formed on the substrate 12 (FIG. 5A). An oxide film is formed on the surface of the substrate 12 where the lower electrode 2 is formed, for example, an SiO film when the substrate 12 is a Si substrate.

2 It may be made. Next, an insulating layer 31 is deposited on the entire surface including the exposed surface of the lower electrode 2 (FIG. 5B), and a contact hole 32 leading to the lower electrode 2 is formed in a part of the insulating layer 31 (FIG. 5C). .

Next, after forming the oxygen deficient layer 5 on the exposed surface of the lower electrode 2 in the contact hole 32 so as to ensure electrical connection with the lower electrode 2, the resistance change layer 3 is further formed. (Figure 5D). As necessary, as shown in FIG. 5E, the surface of the formed resistance change layer 3 may be flattened and the resistance change layer 3 may be embedded.

[0088] The formation method of the oxygen deficient layer 5 and the resistance change layer 3 is not particularly limited. For example, after forming the oxygen deficient layer 5 under the condition B using the sputtering method, the resistance change layer 3 is formed according to the condition A. do it.

Next, an upper electrode 4 is formed on the resistance change layer 3 so as to ensure electrical connection with the resistance change layer 3 (FIG. 5F), and resistance change as shown in FIG. Between the layer 3 and the lower electrode 2, the resistance change element 1 in which the oxygen deficient layer 5 is disposed so as to be in contact with both layers is formed.

The insulating layer 31 plays a role as an interlayer insulating layer in the element 1 and may be made of an insulating material such as SiO, Al 2 O, or the like. The insulating layer 31 may be a resist material.

2 2 3

In this case, the insulating layer 31 can be easily formed by the spin coating method, and the insulating layer 31 having a flat surface can be easily formed on the surface having the undulations.

[0091] Another example of the production method of the present invention is shown in FIGS. 6A to 6G.

[0092] First, the lower electrode 2 is formed on the substrate 12 (Fig. 6A), and the insulating layer 31 is deposited on the entire surface including the exposed surface of the formed lower electrode 2 (Fig. 6B). In part, a contact hole 32 leading to the lower electrode 2 is formed (FIG. 6C).

Next, the resistance change layer 3 is formed on the exposed surface of the lower electrode 2 in the contact hole 32 so as to ensure electrical connection with the lower electrode 2 (FIG. 6D). If necessary, as shown in FIG. 6E, the surface of the formed resistance change layer 3 may be flattened, and the resistance change layer 3 may be embedded.

Next, the oxygen deficient layer 5 is formed on the surface of the resistance change layer 3 (FIG. 6F). The formation method of the oxygen deficient layer 5 is not particularly limited, and for example, the surface of the resistance change layer 3 may be subjected to reverse sputtering or heat treatment in a non-oxidizing atmosphere.

[0095] Next, in order to ensure electrical connection with the oxygen-deficient layer 5, an upper portion is formed on the oxygen-deficient layer 5. Electrode 4 is formed (FIG. 6G), and resistance change element 1 in which oxygen deficient layer 5 is disposed between resistance change layer 3 and upper electrode 4 so as to be in contact with both layers as shown in FIG. It is formed.

[0096] Another example of the production method of the present invention is shown in FIGS. 7A to 7H.

First, the lower electrode 2 is formed on the substrate 12 (FIG. 7A), and the resistance change layer 3 and the oxygen deficient layer 5 are sequentially formed on the formed lower electrode 2 (FIGS. 7B to 7C). The formation method of the resistance change layer 3 and the oxygen deficiency layer 5 is not particularly limited. For example, after forming the resistance change layer 3 according to the condition A and using the sputtering method, the oxygen deficiency layer 5 may be formed according to the condition B. . Further, for example, the oxygen deficient layer 5 may be formed by forming the resistance change layer 3 and then subjecting the surface of the resistance change layer 3 to reverse sputtering or heat treatment in a non-oxidizing atmosphere.

Next, the upper electrode 4 is formed on the oxygen deficient layer 5 so as to ensure electrical connection with the oxygen deficient layer 5 to form a laminate 11 (FIG. 7D). Next, a resist 33 is arranged on the upper electrode 4 in a region where the element 1 is to be formed (FIG. 7E), and is covered with the resist 33 in the laminate 11 by a fine processing means such as ion milling. Remove the part (Figure 7F).

[0099] Next, after depositing an insulating layer 31 on the entire exposed surface of the lower electrode 2, the resistance change layer 3, the oxygen deficient layer 5, and the upper electrode 4 (FIG. 7G), the resist 33 is lifted off. As shown in FIG. 1, a resistance change element 1 in which an oxygen deficient layer 5 is disposed so as to be in contact with both layers is formed between the resistance change layer 3 and the upper electrode 4 (FIG. 7H).

[0100] US Patent No. 6972238 (same content as JP-A-2004-349690) includes PrCaMnO.

By annealing a variable resistance element with three layers, a region consisting of PrCaMnO rich in oxygen (yl yl is greater than 3) and a PrCaMnO low in oxygen (y2 is less than 3) y2

A technique for changing the PrCaMnO layer in a region is disclosed. Disclosure in this document

Three

In the variable resistance element, one area is always PrCaMnO (yl is greater than 3) yl

And the other region is always composed of PrCaMnO (y2 is less than 3), so the subscript “yl” and y2

Both “y2” and “y2” cannot be less than 3. Therefore, as in the variable resistance element of the present invention, the fact that the subscript “xl” is greater than 0 and less than or equal to 3 and the subscript “x2” is greater than 0 and less than 3 is not disclosed or suggested in the document. It has not been done. On the contrary, this document implicitly denies that the subscript “xl” is greater than 0 and less than 3, and the subscript “x2” is greater than 0 and less than 3, as in the variable resistance element of the present invention. . Example

[0101] Hereinafter, the present invention will be described in more detail by way of examples. The present invention is not limited to the following examples.

[0102] (Example 1)

In Example 1, a resistance change element 1 as shown in FIG. 1 was produced by the method shown in FIGS. 6A to 6G, and the temperature dependence of the resistance change characteristics was evaluated.

[0103] First, a Pt layer (thickness: 200 nm) was laminated on the surface of the MgO substrate 12 as the lower electrode 2.

The Pt layer was laminated by RF magnetron sputtering in an argon atmosphere at a pressure of 1 Pa, with the substrate temperature set to room temperature (25 ° C) and the input power set to 80W.

[0104] Next, a SiO layer was deposited as the insulating layer 31 on the entire surface including the exposed surface of the formed Pt layer.

2

. The SiO layer is deposited by RF magnetron sputtering with argon at a pressure of 0.1 lPa.

2

Under the atmosphere, the temperature of the substrate was set to 100 ° C., and the input power was set to 100 W.

[0105] Next, a contact hole 32 (diameter 0.5 μm) leading to the Pt layer was formed in part of the SiO layer by RIE.

2

m) was formed.

[0106] Next, on the exposed surface of the Pt layer in the contact hole 32, Pr Ca is formed as the resistance change layer 3.

0.7 0

An MnO layer (PCMO layer: thickness 300 nm) was stacked. Lamination of the PCMO layer has the formula Pr Ca

.3 3 0.7 0.3

Targeting an oxide having the composition indicated by MnO, RF magnetron sputtering

Three

In a mixed atmosphere of oxygen and argon at a pressure of 3 Pa (partial pressure ratio O ZAr is about 0.2

2

In 5), the substrate temperature was set to 700 ° C and the input power was set to 80W. When the structure of the laminated PCMO layer was separately evaluated by X-ray diffraction measurement, it was confirmed to be a polycrystalline film.

Next, the surface of the laminated PCMO layer was flattened by CMP and buried in the contact hole 32.

[0108] Next, the oxygen deficiency layer 5 was formed by reverse sputtering the surface of the PCMO layer to increase the oxygen deficiency rate of a part of the PCMO layer including the surface. Reverse sputtering was performed by RF magnetron sputtering with the PCMO layer as the target, the substrate temperature at 300 ° C, and the input power at 40 W in a hydrogen atmosphere at a pressure of 5 Pa. Also, the frequency of reverse sputtering voltage to be applied is 100 MHz, and reverse sputtering 200 seconds.

Next, an Ag layer (thickness: 50 nm) was laminated as the upper electrode 4 on the surface of the oxygen deficient layer 5 formed by reverse sputtering to produce a resistance change element 1 (Sample 1-1).

[0110] The Ag layer was laminated by RF magnetron sputtering in an argon atmosphere at a pressure of 1 Pa, with the substrate temperature set at room temperature and the input power set at 80W.

[0111] Apart from the fabrication of Sample 1-1, the resistance change element 1 in which the thickness of the oxygen deficient layer 5 is different from that of Sample 1-1, except that the time for reverse sputtering the surface of the PCMO layer was set to 100 seconds Was made in the same way as Sample 1-1 (Sample 1-2). Since the reverse sputtering time is shorter than that of Sample 1-1, the thickness of oxygen deficient layer 5 in Sample 12 is considered to be smaller than that of Sample 1-1! /.

[0112] In addition to the preparation of Samples 1-1 and 1-2, a resistance variable element without the oxygen deficient layer 5 was sampled except that the surface of the PCMO layer that is the resistance change layer 3 was not reverse-sputtered. It was produced in the same manner as 1-1 (Sample A as a comparative example).

[0113] A pulsed SET voltage, RESET voltage, and READ voltage were applied to each sample fabricated in this way via the lower electrode (Pt layer) and the upper electrode (Ag layer), and the resistance change rate The temperature dependence of was evaluated. The temperature dependency was evaluated as follows, and the same was applied to Examples 2 to 4 below.

[0114] (Measurement method of resistance change rate)

Using a pulse generator between the Pt layer and Ag layer in each sample, the SET voltage is 5V (positive bias voltage), the RESET voltage is 5V (negative bias voltage, magnitude 5V), and the READ voltage is 0. IV. (Positive bias voltage) was applied randomly (pulse width of each voltage was 250ns). After applying the SET voltage and RESET voltage, calculate the electrical resistance value of the element from the current value read by applying the READ voltage.The maximum value of the calculated electrical resistance value is R and the minimum value is R. (R -R) / RX 100 (%)

Max in Max in ιη

The resistance change rate was determined.

[0115] (Temperature dependence evaluation method)

After each sample is held at room temperature (25 ° C), 100 ° C and 200 ° C until the temperature of each sample is approximately equal to the ambient temperature, the resistance of each sample is The anti-change rate was measured.

[0116] The evaluation results are shown in Table 1 below.

[0117] [Table 1]

[0118] As shown in Table 1, the rate of resistance change at room temperature was almost the same (600% or more) for all samples, but at 100 ° C, the rate of resistance change of sample A, which is a comparative example, was large. At 200 ° C, the resistance change characteristics of sample A almost disappeared (resistance change rate was less than 5%). On the other hand, the resistance change rate of Samples 11 and 12 hardly changed even at a temperature of 100 ° C or higher, and could maintain a resistance change rate almost equal to room temperature even at 200 ° C.

[0119] The reverse sputtering conditions for forming the oxygen deficient layer 5 are as follows: the substrate temperature is in the range of room temperature to 300 ° C, the gas pressure of the hydrogen atmosphere is in the range of lPa to: LOPa, and the input power is 40 to 80 W. When the range was changed, almost the same results as Samples 1-1 and 1-2 were obtained.

[0120] (Example 2)

In Example 2, a resistance change element 1 as shown in FIG. 1 was manufactured by the method shown in FIGS. 7A to 7H, and the temperature dependence of the resistance change characteristics was evaluated.

[0121] First, a Pt layer (thickness: 2 OOnm) was stacked as the lower electrode 2 on the surface of the Si substrate 12 in the same manner as in Example 1.

[0122] Next, on the surface of the laminated Pt layer, a PCMO layer as the resistance change layer 3 and an oxygen deficient layer 5 having a larger oxygen deficiency rate than the PCMO layer were sequentially laminated. The lamination of both layers is the formula Pr Ca

0.7 0.3

Three

As a result, the substrate temperature was set to 700 ° C and the input power was set to 80W. PCMO The partial pressure of oxygen in the stacking atmosphere was changed between when the layers were stacked and when the oxygen deficient layer 5 was stacked. Specifically, in a mixed atmosphere of oxygen and argon at a pressure of 3 Pa, the partial pressure ratio O

2

Laminate PCMO layers with ZAr approximately 0.25, under the same atmosphere, but partial pressure ratio O ZAr

An oxygen deficient layer 5 was laminated with 2 being 0.08. The total thickness of the PCMO layer and the oxygen deficient layer 5 was 300 nm.

[0123] The structure of the laminated PCMO layer was separately evaluated by X-ray diffraction measurement, and was confirmed to be a polycrystalline film.

Next, an Ag layer (thickness: 50 nm) was laminated as the upper electrode 4 on the surface of the laminated oxygen deficient layer 5 in the same manner as in Example 1.

[0125] Next, a resist 33 is arranged in a rectangular shape on the surface of the laminated Ag layer, and then the force that is not covered with the resist 33 in the Pt layer, the PCMO layer, the oxygen deficient layer 5 and the Ag layer by ion milling. One part was removed.

Next, a SiO layer was deposited as the insulating layer 31 on the entire exposed surface of each layer. Deposition of SiO layer

In 2 2, RF magnetron sputtering was performed at an input power of 100 W in an argon atmosphere with a substrate temperature of 100 ° C and a pressure of 0.1 IPa.

[0127] Finally, the resist 33 was lifted off, and a resistance change element 1 (Sample 2-1) was produced.

[0128] In addition to the preparation of Sample 2-1, the oxygen deficiency rate in oxygen deficient layer 5 is

— Variable resistance ratio O / 1 in the laminated atmosphere of oxygen deficient layer 5

2

A sample was prepared in the same manner as Sample 2-1 except that Ar was changed to 0.1 (Sample 2-2). Since the above partial pressure ratio is larger than that of Sample 2-1, the oxygen deficiency rate in the oxygen deficient layer of Sample 2-2 is considered to be smaller than that of Sample 2-1.

[0129] In addition to the manufacture of Samples 2-1 and 2-2, a resistance change element that does not include the oxygen-deficient layer 5 is the same as Sample 2-1 except that the oxygen-deficient layer 5 is not stacked. (Sample B-1 as a comparative example).

[0130] Further, separately from the production of each sample, a resistance change element including a PCMO layer and an oxygen excess layer containing excess oxygen exceeding the stoichiometric ratio between the Pt layer and the Ag layer, Instead of stacking the oxygen-deficient layer 5, the partial pressure ratio O ZAr in the stacking atmosphere is set to about 0.6.

2

The sample was prepared in the same manner as Sample 1-1 except that an oxygen-excess layer was laminated (Comparison An example is Sample B-2. Sample B-2 does not have an oxygen deficient layer 5). It can be said that the oxygen-excess layer is a layer having a composition represented by the formula Pr Ca MnO (yl> 3).

0.7 0.3 yl

[0131] A pulsed SET voltage, RESET voltage, and READ voltage were applied to each sample fabricated in this manner via the lower electrode (Pt layer) and the upper electrode (Ag layer). Similarly, the temperature dependence of the resistance change rate of each sample was evaluated.

[0132] The evaluation results are shown in Table 2 below.

[0133] [Table 2]

[0134] As shown in Table 2, the rate of change in resistance at room temperature was almost the same (600% or more) for all samples, but at 100 ° C, samples B-1 and B-2, which were comparative examples, were used. In particular, the resistance change rate of sample B-2 with an oxygen excess layer was greatly reduced, and at 200 ° C, the resistance change characteristics of samples B-1 and B-2 almost disappeared (resistance change rate 5% Less). On the other hand, the resistance change rate of Samples 2-1 and 2-2 hardly changed even at a temperature of 100 ° C or higher, and could maintain a resistance change rate almost equal to room temperature even at 200 ° C. .

[0135] (Example 3)

In Example 3, a resistance change element 1 as shown in FIG. 2 was produced by the method shown in FIGS. 5A to 5F, and the temperature dependence of the resistance change characteristics was evaluated.

[0136] First, a Pt layer (thickness: 200 nm) was laminated as the lower electrode 2 on the surface of the MgO substrate 12 in the same manner as in Example 1.

[0137] Next, the insulating layer 31 is formed on the entire surface including the exposed surface of the laminated Pt layer in the same manner as in Example 2. A SiO layer was deposited.

2

[0138] Next, the portion where the variable resistance element 1 in the deposited SiO layer is to be formed is formed by RIE.

2

A contact hole 32 (diameter 0.5 m) was formed.

Next, an oxygen deficient layer 5 was deposited on the exposed surface of the Pt layer in the formed contact hole 32. The stacking of the oxygen deficient layer 5 is performed by RF magnetron sputtering with the formula Pr Ca M

0.7 0.3 ηθ The target is an oxide having a composition represented by ηθ.

Three

In a mixed atmosphere (partial pressure ratio O ZAr is 0.1), the substrate temperature is set to 700 ° C

2

The power used was 80W.

[0140] Subsequently, a PCMO layer was laminated as the resistance change layer 3 on the surface of the laminated oxygen deficient layer 5. Lamination of the PCMO layer is done by setting the partial pressure ratio O ZAr in the lamination atmosphere to about 0.25.

2

The outside was performed in the same manner as the stacking of the oxygen deficient layer 5. The thickness of the laminated oxygen deficient layer 5 and PCMO layer was 300 nm in total.

[0141] When the structure of the laminated PCMO layer was separately evaluated by X-ray diffraction measurement, it was confirmed to be a polycrystalline film.

[0142] Next, the surface of the laminated PCMO layer was flattened by CMP, and an Ag layer (thickness 50 nm) was formed as the upper electrode 4 on the surface of the PCMO layer after the treatment in the same manner as in Example 1. By stacking, variable resistance element 1 (sample 3) was produced.

[0143] Separately from the preparation of Sample 3, a sample without oxygen deficient layer 5 was prepared in the same manner as Sample 3, except that the PCMO layer was directly laminated on the exposed surface of the Pt layer in contact hole 32. (Comparative sample C).

[0144] A pulsed SET voltage, RESET voltage, and READ voltage were applied to each sample fabricated in this manner via the lower electrode (Pt layer) and the upper electrode (Ag layer). Similarly, the temperature dependence of the resistance change rate of each sample was evaluated.

[0145] The evaluation results are shown in Table 3 below.

[0146] [Table 3] m ()

Sample No.

2 5 ° C 1 0 0. C 2 0 0

3 630 620 620

C (J; 瞧) 650 200

[0147] As shown in Table 3, the resistance change rate at room temperature was almost the same (600% or more) in all samples, but at 100 ° C, the resistance change rate of sample C, which is a comparative example, was large. At 200 ° C, the resistance change characteristics of sample C almost disappeared (resistance change rate was less than 5%). In contrast, the resistance change rate of sample 3 hardly changed even at temperatures of 100 ° C or higher, and could maintain a resistance change rate almost equal to room temperature even at 200 ° C

[0148] (Example 4)

In Example 4, a resistance change element 1 as shown in FIG. 1 was produced by the method shown in FIGS. 7A to 7H, and the temperature dependence of the resistance change characteristics was evaluated.

First, a Pt layer (thickness 2) is formed on the surface of the Si substrate 12 as the lower electrode 2 in the same manner as in Example 1.

OOnm) was laminated.

[0150] Next, a PCMO layer (thickness: 300 nm) was laminated as the resistance change layer 3 in the same manner as in Example 1 on the surface of the laminated Pt layer. When the structure of the laminated PCMO layer was separately evaluated by X-ray diffraction measurement, it was confirmed to be a polycrystalline film.

[0151] Next, the surface of the laminated PCMO layer was heat-treated in a nitrogen atmosphere, so that PCM

The oxygen deficiency layer 5 was formed by increasing the deficiency rate of a part of oxygen including the surface in the O layer. In the heat treatment, the entire substrate, including the substrate, is heated to 500 ° C in 1 minute.

After holding for 3 minutes, it was performed by rapidly cooling to room temperature.

Next, an Ag layer (thickness: 50 nm) was stacked as the upper electrode 4 on the surface of the formed oxygen deficient layer 5 in the same manner as in Example 1.

[0153] Next, a resist 33 is arranged in a rectangular shape on the surface of the laminated Ag layer, and then covered with the resist 33 in the Pt layer, the resistance change layer 3, the oxygen deficient layer 5, and the Ag layer by ion milling. The part which did not exist was removed. [0154] Next, an SiO layer as an insulating layer 31 is deposited on the entire exposed surface of each layer in the same manner as in Example 2.

2 stacked.

[0155] Finally, the resist 33 was lifted off, and a resistance change element 1 (sample 4) was produced.

[0156] Separately from the production of sample 4, a resistance change element without oxygen deficient layer 5 was produced in the same manner as sample 4 except that the surface of the PCMO layer that is resistance change layer 3 was not heat-treated. (Comparative sample D).

[0157] For each sample prepared in this way, the lower electrode (Pt layer) and the upper electrode (Ag layer)

) To apply a pulsed SET voltage, RESET voltage, and READ voltage.

In the same manner as in 1, the temperature dependence of the resistance change rate of each sample was evaluated.

[0158] The evaluation results are shown in Table 4 below.

[0159] [Table 4]

[0160] As shown in Table 4, the resistance change rate at room temperature was almost the same (600% or more) for all samples, but at 100 ° C, the resistance change rate of sample D, which is a comparative example, was large. At 200 ° C, the resistance change characteristics of sample D almost disappeared (resistance change rate was less than 5%). In contrast, the resistance change rate of sample 4 hardly changed even at temperatures of 100 ° C or higher, and the resistance change rate at 200 ° C was almost the same as that of room temperature.

[0161] As described above, the resistance change element of the present invention is superior in heat resistance compared to conventional resistance change elements, and can operate stably in a temperature environment of 200 ° C, for example. The resistance change element of the present invention can hold information in an nonvolatile manner as an electric resistance value, and the element can be easily miniaturized as compared with a conventional charge storage type memory element. As an electronic device using the variable resistance element of the present invention, for example, a non-volatile memory used for an information communication terminal or the like , Switching elements, sensors, image display devices, and the like.

Claims

The scope of the claims

[1] including a substrate and a multilayer structure disposed on the substrate,

The multilayer structure includes an upper electrode and a lower electrode, and a resistance change layer disposed between the upper electrode and the lower electrode,

There are two or more states where the electric resistance value between the upper electrode and the lower electrode is different, and by applying a predetermined electric pulse between the upper electrode and the lower electrode, two or more states A variable resistance element that changes from one state to another selected from:

The variable resistance layer has a composition represented by the formula (Pr, Ca) MnO;

xl

The multilayer structure has a thread structure represented by the formula (Pr, Ca) MnO, disposed between at least one electrode selected from the upper electrode and the lower electrode force and the resistance change layer. A resistance change element further including an oxygen deficient layer.

However, xl and x2 are numerical values that satisfy the following expressions, respectively.

0 <xl≤3

0 <x2 <3

x2 <xl

[2] The variable resistance layer according to claim 1, wherein the variable resistance layer has a composition represented by a formula (Pr, Ca) MnO.

Three

The variable resistance element listed.

[3] The resistance change element according to [1], wherein the oxygen deficient layer and the resistance change layer are in contact with each other.

[4] The resistance change element according to [1], wherein the oxygen deficient layer and the at least one electrode are in contact with each other.

5. The resistance change element according to claim 1, wherein the multilayer structure includes only the oxygen deficient layer and the resistance change layer as an oxide layer containing Pr, Ca, and Mn.

6. The variable resistance element according to claim 1, wherein the multilayer structure includes the oxygen deficient layer, the variable resistance layer, the upper electrode, and the lower electrode.

7. The p 1-p x2 according to claim 1, wherein the oxygen-deficient layer has a composition represented by the formula Pr Ca MnO. Resistance change element.

However, p is 0.6 or more and 0.8 or less.

[8] The p 1-p xl according to claim 1, wherein the variable resistance layer has a composition represented by a formula Pr Ca MnO.

Resistance change element.

However, p is 0.6 or more and 0.8 or less.

[9] including a substrate and a multilayer structure disposed on the substrate,

There are two or more states where the electric resistance value between the upper electrode and the lower electrode is different, and by applying a predetermined electric pulse between the upper electrode and the lower electrode, two or more states A method of manufacturing a resistance change element that changes from one state to another state selected from:

A lower electrode forming step of forming a lower electrode on the substrate;

A variable resistance layer having a composition represented by the formula (Pr, Ca) MnO is formed on the lower electrode.

A variable resistance layer forming step to be formed;

Forming an oxygen deficient layer having a composition represented by the formula (Pr, Ca) MnO on the variable resistance layer; and

An upper electrode forming step of forming an upper electrode for sandwiching the variable resistance layer and the oxygen deficient layer together with the lower electrode, in order.

0 <xl≤3

0 <x2 <3

x2 <xl

[10] The method for manufacturing a variable resistance element according to claim 9, wherein xl = 3.

11. The variable resistance element manufacturing method according to claim 9, wherein in the oxygen deficient layer forming step, the oxygen deficient layer is formed by reverse sputtering the surface of the variable resistance layer.

12. The method for manufacturing a variable resistance element according to claim 11, wherein xl = 3.

[13] forming the variable resistance layer in contact with the lower electrode;

12. The method of manufacturing a variable resistance element according to claim 11, wherein the upper electrode is formed so as to be in contact with the oxygen deficient layer formed on the surface of the variable resistance layer.

14. The resistance variable element manufacturing method according to claim 9, wherein in the oxygen deficient layer forming step, the oxygen deficient layer is formed by heat-treating a surface of the variable resistance layer in a non-oxidizing atmosphere. Method.

15. The method for manufacturing a variable resistance element according to claim 14, wherein xl = 3.

[16] forming the variable resistance layer in contact with the lower electrode,

15. The method of manufacturing a variable resistance element according to claim 14, wherein the upper electrode is formed so as to be in contact with the oxygen deficient layer formed on a surface of the variable resistance layer.

[17] Partial pressure of the inert gas in the atmosphere in the variable resistance layer forming step P

The ratio of inert to oxygen partial pressure P (P / P) is determined by the atmosphere in the oxygen deficient layer formation process.

10. The method for manufacturing a resistance change element according to claim 9, wherein the ratio is greater than the ratio.

[18] In the variable resistance layer forming step, the variable resistance layer is formed by sputtering,

18. The method of manufacturing a resistance change element according to claim 17, wherein in the oxygen deficient layer forming step, the oxygen deficient layer is formed by sputtering.

[19] including a substrate and a multilayer structure disposed on the substrate,

A lower electrode forming step of forming a lower electrode on the substrate;

An oxygen deficient layer having a composition represented by the formula (Pr, Ca) MnO is formed on the lower electrode. An oxygen deficient layer forming step to be formed;

A variable resistance layer having a composition represented by the formula (Pr, Ca) MnO on the oxygen deficient layer

xl

Forming a resistance change layer,

An upper electrode forming step of sequentially forming an upper electrode that sandwiches the oxygen deficient layer and the resistance change layer together with the lower electrode.

However, xl and χ2 are numerical values that satisfy the following formulas.

0 <xl≤3

0 <χ2 <3

x2 <xl

[20] Partial pressure of inert gas and oxygen in atmosphere in the resistance change layer forming step

The ratio of inert partial pressure P (P / P) is the oxygen deficient layer formation process atmosphere.

20. The method for manufacturing a resistance change element according to claim 19, wherein the ratio is greater than the ratio.

[21] In the oxygen deficient layer forming step, the oxygen deficient layer is formed by sputtering,

21. The variable resistance element manufacturing method according to claim 20, wherein in the variable resistance layer forming step, the variable resistance layer is formed by sputtering.