KR101588980B1 - Synapse Apparatus for neuromorphic system applications and method of manufacturing the same - Google Patents

Abstract

A synapse device for neuromorphic system application and a manufacturing method are provided. The synapse device for neuromorphic system application comprises: a substrate; a first electrode which is positioned on the substrate; a tunneling barrier layer which is positioned on the first electrode; a resistance change layer which is positioned on the tunneling barrier layer; and a second electrode which is positioned on the resistance change layer. The resistance change layer has a state change caused by the formation and extinction of a metal filament, and the tunneling barrier layer plays the role of a barrier layer in electron movement to implement non-linear characteristics. Accordingly, the non-linear characteristics of the device can prevent current leakage leaking through another device in a cross-point array structure, and thus it is possible to implement a highly integrated array.

Description

Technical Field [0001] The present invention relates to a synapse device for use in a neuromotor system application,

The present invention relates to a synapse device, and more particularly, to a synapse device for a novel Lomographic system application and a method of manufacturing the same.

The von Neumann type of computing system, which is widely used at present, shows considerable processing power in repetitive and simple calculation. On the other hand, more complicated calculations such as high-dimensional calculations require considerable energy and time. The new LomoPick system, which is presented as a solution to this problem, can solve the problems that can not be solved by the existing von Neumann method in low power consumption and in a short time by taking advantage of the possibility of learning.

For this reason, research on the Nyomo pick system has been actively conducted in recent years. In implementing a neuromotor system, the underlying synaptic element is most important. The synaptic element performs a similar function to the brain synapse, enabling the learning and recognition functions of the novel Lomic system. A variety of memory-based devices such as Flash, SRAM, and DRAM can be used as synaptic devices, but phase change memory (PCM), ferroelectric random access memory (FeRAM), and ReRAM (Resistance Random Access Memory) have been studied. Particularly, in order to realize a highly integrated synapse device, a two-terminal device should be implemented as a synapse device, and a two-terminal device implemented as a cross-point array . However, in the case of a cross-point array type, a sneak-current problem may occur in which a current and a voltage are applied to a non-selected synapse device.

Therefore, in order to prevent such a sneak-current, a switch element serving as a switching element is required for each synapse element. Such a switch element can be used as a conventional transistor, but if a 3-terminal transistor is used as a switching element, the implementation of a highly integrated synapse element becomes more difficult. Therefore, it is necessary to develop a 2-terminal switch device or a synapse device including switch characteristics.

Korean Patent No. 10-1443271

A problem to be solved by the present invention is to provide a synapse device for a novel Lomographic system application for preventing a leakage current that may occur in a cross-point array structure and realizing a highly integrated device.

According to an aspect of the present invention, there is provided a synapse device for a novel Lomographic system application. A synapse device for a novel LomoPeek system application includes a substrate, a first electrode located on the substrate, a tunneling barrier layer located on the first electrode, a resistance variable layer located on the tunneling barrier layer, And the resistance variable layer has a state change due to the formation and disappearance of the metal filament, and the tunneling barrier layer serves as a barrier layer for electron transfer, thereby realizing a nonlinear characteristic .

The first electrode may include Pt or W. [

The resistance-variable layer may include TiO ₂ , NiO, Al ₂ O ₃ , Nb ₂ O ₅ , HfO ₂ , or V ₂ O ₅ .

The tunneling barrier layer may include a metal oxide.

The metal oxide may be selected from the group consisting of TiO _x , Ti _x O _y , HfO _x , Hf _x O _y , AlO _x , Al _x O _y , TaO _x , Ta _x O _y , VO _x , V _x O _y , Nb _x O _y , _x , Fe _x O _y , FeO _x , W _x O _y , or WO _x .

In addition, the tunneling barrier layer is formed of at least two metal oxide layers having different oxygen compositions.

The tunneling barrier layer comprises TiO _y layer on Ti0 _x layer and the Ti0 _x layer, and wherein may be the y> x.

In addition, the tunneling barrier layer may include a metal-insulator transition material. The metal-insulator transition material is _{TiO 2-y (0 = y} <2), Ti 2-x O 3-y (0 = x <2, 0 = y <3), Ti 3-x O 5-y ( 0 = x <3, 0 = y <5), Ti 4-x O 7-y (0 = x <4, 0 = y <7), VO 1-y (0 = y <1), VO 2- _{y (0 = y <2)} , V 2-x O 3-y (0 = x <2, 0 = y <3), V 4-x O 7-y (0 = x <4, 0 = y < _{7), V 5-x O} 9-y (0 = x <5, 0 = y <9), V 6-x O 11-y (0 = x <6, 0 = y <11), V 6- _{x O 13-y (0 =} x <6, 0 = y <13), V 8-x O 15-y (0 = x <8, 0 = y <15), Fe 3-x O 4-y ( 0 = x <3, 0 = y <4), NbO 2-y (0 = y <2), PrNiO 3-y (0 = y <3), NdNiO 3-y (0 = y <3), SmNiO _3-y (0 = y <3), and LaCoO _3-y (0 = y <3).

The second electrode may include Ti, Ti alloy, Cu, Cu alloy, Ag or Ag alloy.

And the metal filament is formed and extinguished by the oxidation-reduction reaction of the metal ions permeated from the second electrode.

According to another aspect of the present invention, there is provided a method of manufacturing a synapse device for use in a New Lomographic system. A method of manufacturing a synapse element for use in a Nyomo pick system application comprises the steps of preparing a substrate, forming a first electrode on the substrate, forming a tunneling barrier layer on the first electrode, And forming a second electrode on the resistance variable layer, wherein the resistance variable layer has a state change due to the formation and disappearance of the metal filament, and the tunneling barrier layer has electron transfer Thereby realizing a nonlinear characteristic.

The tunneling barrier layer may include a metal oxide. The metal oxide may be selected from the group consisting of TiO _x , Ti _x O _y , HfO _x , Hf _x O _y , AlO _x , Al _x O _y , TaO _x , Ta _x O _y , VO _x , V _x O _y , Nb _x O _y , _x , Fe _x O _y , FeO _x , W _x O _y , or WO _x .

The forming of the tunneling barrier layer on the first electrode may include forming at least two metal oxide layers having different compositions of oxygen on the first electrode.

Forming a tunneling barrier layer on the first electrode includes forming a TiO _x layer on the first electrode and annealing the TiO _x layer in an oxygen atmosphere to form a TiO _y layer thereon, > x.

In addition, the tunneling barrier layer may include a metal-insulator transition material. The metal-insulator transition material is _{TiO 2-y (0 = y} <2), Ti 2-x O 3-y (0 = x <2, 0 = y <3), Ti 3-x O 5-y ( 0 = x <3, 0 = y <5), Ti 4-x O 7-y (0 = x <4, 0 = y <7), VO 1-y (0 = y <1), VO 2- _{y (0 = y <2)} , V 2-x O 3-y (0 = x <2, 0 = y <3), V 4-x O 7-y (0 = x <4, 0 = y < _{7), V 5-x O} 9-y (0 = x <5, 0 = y <9), V 6-x O 11-y (0 = x <6, 0 = y <11), V 6- _{x O 13-y (0 =} x <6, 0 = y <13), V 8-x O 15-y (0 = x <8, 0 = y <15), Fe 3-x O 4-y ( 0 = x <3, 0 = y <4), NbO 2-y (0 = y <2), PrNiO 3-y (0 = y <3), NdNiO 3-y (0 = y <3), SmNiO _3-y (0 = y <3), and LaCoO _3-y (0 = y <3).

According to the present invention, the flow of current is nonlinearly implemented by inserting a tunneling barrier layer into a device having a linear characteristic. Therefore, by providing a synapse element having nonlinear characteristics, leakage current can be prevented in a cross-point array structure, and a highly integrated synapse element can be realized.

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

FIG. 1 is a schematic cross-sectional view of a synapse device for a New Lomographic system application in accordance with an embodiment of the present invention.
FIG. 2 is a graph illustrating current-voltage curves of a non-linear synapse device of the present invention and a conventional linear synapse device.
3 is a schematic cross-sectional view of a synapse device according to a production example.
Figure 4 is a TEM image of a portion of Figure 3;
5 and 6 are diagrams for explaining a readout margin calculation of a nonlinear synapse device according to a manufacturing example.
7 is a graph of current-voltage obtained by evaluating V reset in suppression characteristics of a nonlinear synapse device according to the production example.
8 is a graph of current-voltage obtained by evaluating Icc in the enhancement characteristics of the non-linear synapse device according to the production example.
9 is a graph showing a resistance value according to a reset voltage in a suppression characteristic of a nonlinear synapse device according to a manufacturing example.
10 is a graph illustrating resistance values according to current compliance in the enhancement characteristics of a nonlinear synapse device according to a manufacturing example.

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

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

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

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

The "non-linear characteristic" used in the present invention means that the current-voltage curve of the synapse device is nonlinear.

A synapse device for a novel Lomoc system application according to an embodiment of the present invention will be described.

FIG. 1 is a schematic cross-sectional view of a synapse device for a New Lomographic system application in accordance with an embodiment of the present invention.

Referring to FIG. 1, a synapse device for a novel Lomoc system application according to an embodiment of the present invention includes a substrate 100, a first electrode 200, a tunneling barrier layer 300, a resistance-variable layer 400, And may include a second electrode 500.

The substrate 100 may be any material that can serve as a support substrate. For example, such a substrate 100 may be a silicon substrate. On the other hand, such a substrate 100 may be omitted in some cases.

The first electrode 200 is located on the substrate. The first electrode 200 may include Pt or W. [ The first electrode 200 may be formed by sputtering, RF sputtering, RF magnetron sputtering, pulsed laser deposition, chemical vapor deposition, plasma enhanced chemical vapor deposition, atomic layer deposition, or molecular beam epitaxy deposition.

The tunneling barrier layer 300 is located on the first electrode. The tunneling barrier layer 300 functions as a barrier layer for electron mobility, thereby realizing nonlinear characteristics.

The tunneling barrier layer 300 may include a metal oxide or a metal-insulator transition material.

The metal oxide may be selected from the group consisting of TiO _x , Ti _x O _y , HfO _x , Hf _x O _y , AlO _x , Al _x O _y , TaO _x , Ta _x O _y , VO _x , V _x O _y , Nb _x O _y , _x , Fe _x O _y , FeO _x , W _x O _y , or WO _x . Where X and Y are real numbers greater than zero. On the other hand, when the same material is used as the material of the resistance variable layer 400 and the tunneling barrier layer 300 described later, the composition of oxygen in the material of the tunneling barrier layer 300 is set to be larger than that of the resistance variable layer 400 .

In addition, the tunneling barrier layer 300 may be formed of at least two metal oxide layers having different oxygen compositions. For example, the tunneling barrier layer (300) comprises TiO _y layer on Ti0 _x layer and the Ti0 _x layer, in which may be the y> x. By forming the tunneling barrier layer 300 in a multi-layered structure, a very high nonlinearity can be obtained as will be described in detail below.

That is, the titanium oxide film (TiO _x ) employed as the tunneling barrier layer of the present invention has a higher nonlinear value than TaO _x or AlO _x , which can be explained by a band structure. In the present invention, bandgap engineering is performed by controlling the thickness and oxygen distribution for the titanium oxide film (TiO _x ). This is because the optimal thickness of the titanium oxide layer can effectively reduce the current in the 1 / 2V _read region and the oxygen distribution can control the tunnel barrier properties of the titanium oxide layer to exhibit reliable nonlinear behavior. The oxygen annealing was oxidized from the surface of the titanium oxide film (TiO _x ) to the bulk region to produce an insulating ultra-thin TiO _y . The present invention can provide a highly integrated synapse device without a selection device.

In addition, the metal-insulator transition material is _{TiO 2-y (0 = y} <2), Ti 2-x O 3-y (0 = x <2, 0 = y <3), Ti 3-x O 5- _{y (0 = x <3,} 0 = y <5), Ti 4-x O 7-y (0 = x <4, 0 = y <7), VO 1-y (0 = y <1), VO _{2-y (0 = y <} 2), V 2-x O 3-y (0 = x <2, 0 = y <3), V 4-x O 7-y (0 = x <4, 0 = (0 = x <5, 0 = y <9), V _{6 -x} O _{11 -y} (0 = x <6, 0 = y <11), V _5-x O _{9-y 6-x O 13-y (} 0 = x <6, 0 = y <13), V 8-x O 15-y (0 = x <8, 0 = y <15), Fe 3-x O 4- _{y (0 = x <3,} 0 = y <4), NbO 2-y (0 = y <2), PrNiO 3-y (0 = y <3), NdNiO 3-y (0 = y <3) , SmNiO3 _-y (0 = y <3), and LaCoO3 _-y (0 = y <3). Such a metal-insulator transition material is a material in which a mott-transition behavior occurs. By using such a metal-insulator transition material as a material of the tunneling barrier layer 300, a change in the current-voltage curve of the device abruptly changes . Therefore, nonlinearity can be further increased.

The tunneling barrier layer 300 may be formed by sputtering, RF sputtering, RF magnetron sputtering, pulsed laser deposition, chemical vapor deposition, plasma enhanced chemical vapor deposition, atomic layer deposition, or molecular beam epitaxy deposition.

The resistance variable layer 400 is located on the tunneling barrier layer 300. The resistance variable layer 400 has a state change due to the formation and disappearance of the metal filament. At this time, the metal filament is formed and extinguished by the oxidation-reduction reaction of the metal ions permeated from the second electrode 500, which will be described later.

The resistance variable layer 400 may include TiO ₂ , NiO, Al ₂ O ₃ , Nb ₂ O ₅ , HfO ₂ , or V ₂ O ₅ .

The resistance variable layer 400 may be formed by sputtering, RF sputtering, RF magnetron sputtering, pulse laser deposition, chemical vapor deposition, plasma enhanced chemical vapor deposition, atomic layer deposition, or molecular beam epitaxy deposition.

The second electrode 500 is located on the resistance-variable layer 400. The material of the second electrode 500 may be any material capable of providing a metal ion capable of forming a metal filament in the resistance variable layer according to voltage application. For example, the second electrode 500 may include Ti, Ti alloy, Cu, Cu alloy, Ag or Ag alloy.

The second electrode 500 may be formed by sputtering, RF sputtering, RF magnetron sputtering, pulsed laser deposition, chemical vapor deposition, plasma enhanced chemical vapor deposition, atomic layer deposition, or molecular beam epitaxy deposition.

On the other hand, the capping layer (600 in FIG. 3) may be further positioned on the second electrode 500 as the case may be. This capping layer (600 in FIG. 3) may comprise Pt.

Thus, according to the present invention, a nonlinear synapse element can be provided by inserting a tunneling barrier layer into a linear synapse element.

FIG. 2 is a graph illustrating current-voltage curves of a non-linear synapse device of the present invention and a conventional linear synapse device.

In the case of the conventional linear synapse element of a black line (Linear ReRAM), it can be seen that the low resistance state (LRS) shows a linear characteristic. In the case of a blue-line synapse element (Selector-less ReRAM), for example, a TiO _y / TiO _x multi-layer By inserting a tunneling barrier layer, I _LRS of 1 / 2V _read is significantly reduced compared to conventional linear synapse devices. The LRS at this time means a low resistance state. Therefore, it can be seen that the flow of current is nonlinearly implemented by inserting the tunneling barrier layer.

Manufacturing example

Thereby producing a synapse device according to an embodiment of the present invention.

3 is a schematic cross-sectional view of a synapse device according to a production example. Figure 4 is a TEM image of a portion of Figure 3;

3 and 4, the synapse device of the present invention includes a tunneling barrier layer 300, a resistance-variable layer 400, a second electrode 500, and a capping layer 600 on a first electrode 200 Respectively.

As can be seen from the figure, the tunneling barrier layer 300 of the synapse device of the present invention is formed of multiple layers 310 and 320 having different compositions of oxygen.

These multi-layers were fabricated by bandgap engineering by controlling film thickness and oxygen distribution.

Here, the tunneling barrier layer 300 includes a TiO _x layer 310 and a TiO _y layer 320 obtained by heat-treating the TiO _x layer 310 in an oxygen atmosphere. In the present invention, the thickness of TiO _x is selected for bandgap engineering, which can be about 6 nm. The TiO _x layer is then annealed in an oxygen atmosphere to oxidize the top to produce TiO _y (where y> x). The thickness of the oxidized TiO _y layer was about 2.5 nm, so that the remaining TiO _x layer was 3.5 nm. By forming the tunneling barrier layer 300 in a multi-layered structure, a very high nonlinearity can be obtained as described in detail below.

At this time, a 4 nm thick HfO ₂ layer was applied to the resistance variable layer 400. The first electrode 200 and the second electrode 500 are made of Pt and Ti, respectively. The capping layer 600 is made of Pt.

 Experimental Example

5 and 6 are diagrams for explaining a readout margin calculation of a nonlinear synapse device according to a manufacturing example.

As shown in FIG. 5, it is possible to prevent a leakage current from escaping through other elements in a cross-point array structure, so that a larger number of arrays can be realized. That is, high integration is advantageous.

In addition, as shown in FIG. 6, the read margin according to the number of word lines and bit lines is compared, and as the non-linearity increases, the read margin becomes relatively higher.

The synapse device 20 has an asymmetric synaptic weight chage. The synaptic characteristic at this time includes the depression characteristic and the potentiation characteristic.

Therefore, the synaptic characteristics (potentiation & depression) of the nonlinear synapse device according to the present invention were evaluated.

7 is a graph of current-voltage obtained by evaluating V _reset in suppression characteristics of a nonlinear synapse device according to the production example. Referring to FIG. 7, it can be seen that the suppression characteristic that the resistance value increases as V _reset increases.

8 is a graph of current-voltage obtained by evaluating resistance value reduction according to I _cc in the enhancement characteristics of the non-linear synapse device according to the production example. At this time, cc means current compliance.

Referring to FIG. 8, it can be seen that the resistance value increases as I _cc increases in the enhancement characteristics of the synapse device.

9 is a graph showing a resistance value according to a reset voltage in a suppression characteristic of a nonlinear synapse device according to a manufacturing example. Referring to FIG. 9, it can be seen that the resistance value of the synapse device can be increased by adjusting V _reset .

10 is a graph illustrating resistance values according to current compliance in the enhancement characteristics of a nonlinear synapse device according to a manufacturing example. Referring to FIG. 10, it can be seen that the resistance value of the synapse device can be reduced by adjusting I _cc .

Therefore, in the case of the nonlinear synapse device according to the manufacturing example, the resistance value of the synapse device through V _reset and I _cc can be adjusted, and at the same time, nonlinear characteristics are shown. Through these characteristics, it is possible to carry out the work process through the learning and learning process of the synapse device in the new LomoPic system, and it is possible to integrate it without the additional switch element.

According to the present invention, the flow of current is nonlinearly implemented by inserting a tunneling barrier layer into a device having a linear characteristic. Therefore, by providing a synapse element having nonlinear characteristics, leakage current can be prevented in a cross-point array structure, and a highly integrated synapse element can be realized.

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

100: substrate 200: first electrode
300: tunneling barrier layer 310: TiO _x layer
320: TiO _y layer 400: resistance variable layer
500: second electrode 600: capping layer

Claims (18)

Board;
A first electrode located on the substrate;
A tunneling barrier layer located on the first electrode;
A resistance-variable layer located on the tunneling barrier layer; And
And a second electrode located on the resistance-variable layer,
Wherein the resistance variable layer has a state change due to the formation and disappearance of the metal filament,
The tunneling barrier layer functions as a barrier layer for electron transport, thereby realizing a nonlinear characteristic.
Wherein the tunneling barrier layer is formed of at least two metal oxide layers having different oxygen compositions,
Wherein the metal filament is formed and extinguished by redox reaction of metal ions impregnated from the second electrode. The method according to claim 1,
Wherein the first electrode comprises Pt or &lt; RTI ID = 0.0 &gt; W. &Lt; / RTI &gt; The method according to claim 1,
Wherein the resistance variable layer comprises TiO ₂ , NiO, Al ₂ O ₃ , Nb ₂ O ₅ , HfO ₂ , or V ₂ O ₅ . delete The method according to claim 1,
The metal oxide layers are _{TiO x, Ti x O y,} HfO x, Hf x O y, AlO x, Al x O y, TaO x, Ta x O y, VO x, V x O y, Nb x O y, NbO _x , Fe _x O _y , FeO _x , W _x O _y , or WO _x . delete The method according to claim 1,
Wherein the tunneling barrier layer comprises a TiO _x layer and a TiO _y layer located on the TiO _x layer,
Wherein y > x.
Synaptic Devices for Nyomorphic System Applications. delete delete The method according to claim 1,
Wherein the second electrode comprises Ti, Ti alloy, Cu, Cu alloy, Ag or Ag alloy. delete Preparing a substrate;
Forming a first electrode on the substrate;
Forming a tunneling barrier layer on the first electrode;
Forming a resistance variable layer on the tunneling barrier layer; And
And forming a second electrode on the resistance-variable layer,
Wherein forming the tunneling barrier layer on the first electrode comprises forming at least two metal oxide layers having different oxygen compositions on the first electrode,
Wherein the resistance variable layer has a state change due to the formation and disappearance of the metal filament,
Wherein the metal filament is formed and extinguished by a redox reaction of metal ions impregnated from the second electrode,
Wherein the tunneling barrier layer acts as a barrier layer for electron transport, thereby realizing a nonlinear characteristic. delete 13. The method of claim 12,
The metal oxide layers are _{TiO x, Ti x O y,} HfO x, Hf x O y, AlO x, Al x O y, TaO x, Ta x O y, VO x, V x O y, Nb x O y, NbO _x , Fe _x O _y , FeO _x , W _x O _y , or WO _x . delete 13. The method of claim 12,
Wherein forming the tunneling barrier layer on the first electrode comprises:
Forming a TiO _x layer on the first electrode, annealing the TiO _x layer in an oxygen atmosphere to form a TiO _y layer on the TiO _x layer,
Wherein y > x,
A method for manufacturing a synaptic device for the application of a neuromotor system. delete delete

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