Method for producing memristive elements with enhanced internal nonlinearity based on metal-nonstoichiometric oxide nanocomposite

Abstract

FIELD: microelectronics; nanoelectronics.SUBSTANCE: invention relates namely to the technology of producing memristive elements based on nanocomposite structures, which in turn can be used as a device-component base for the implementation of non-volatile memory and neuromorphic computing systems. The method for producing memristive elements based on a metal-non-stoichiometric oxide nanocomposite includes sequential deposition by ion-beam sputtering onto a glass-ceramic substrate of a layer of the lower Cr / Cu / Cr electrode, a dielectric interlayer of LiNbO3, a nanocomposite of (Co40Fe40B20)33.4(SiO2)66.6 and an upper Cu electrode, additional sputtering of a tunnel-transparent dielectric interlayer of at least 5 nm thickness between the lower Cr / Cu / Cr electrode and the dielectric interlayer of LiNbO3, and after the formation of the upper Cu electrode, heat treatment of the structure is carried out in a vacuum at a temperature of 300 to 350 °C for at least 1 hour.EFFECT: increase the internal nonlinearity of the current-voltage characteristics of memristive elements based on metal-nonstoichiometric oxide nanocomposites with an additional dielectric layer.2 cl, 2 dwg

Description

[0001] AREA OF TECHNOLOGY

[0002] The invention relates to the field of micro- and nanoelectronics, namely to the technology of producing memristive elements based on nanocomposite structures, which in turn can be used as a device-component base for the implementation of non-volatile memory and neuromorphic computing systems.

[0003] LEVEL OF TECHNOLOGY

[0004] Patent No. RU 2666165 “Method for forming a synaptic memristor based on a metal-non-stoichiometric oxide nanocomposite” is known, which consists of creating memristive structures Cr / Cu / Cr / (Co 40 Fe 40 B 20 )×(LiNbO 3-y ) 100-x / Cr / Cu / Cr using non-stoichiometric oxides capable of simulating the properties of biological synapses and at the same time possessing increased resistance to cyclic resistive switching and consisting of sequential deposition by ion-beam sputtering of a Cr / Cu / Cr layer, which is the lower electrode, a metal-non-stoichiometric oxide nanocomposite layer and a Cr / Cu / Cr layer, which is the upper electrode.

[0005] The disadvantage of this structure was the relatively low thermal stability properties.

[0006] The closest in technical essence is the method described in the source “The influence of heat treatment on the memristive properties of CU / (CO40FE40B20)X (SIO2)100-X / LINBO3 / CR / CU / CR capacitor structures”, by Sitnikov A.V., Kalinin Yu.E., Babkina I.V., Nikonov A.E., Shakurov A.R., Kopytin M.N. Solid State Physics. 2024. Vol. 66. No. 10. Pp. 1713-1720. https: / / www.mathnet.ru / links / c9499dae0ed8e2defe600bb07ac7013d / ftt10450.pdf), The method describes the replacement of the non-stoichiometric part of the oxide and the introduction of an additional dielectric layer of Cu / (Co 40 Fe 40 B 20 ) Х (SiO2) 100-Х / LiNbO3 / Cr / Cu / Cr, which made it possible to obtain optimal values ​​of memristive properties with sufficient thermal stability.

[0007] The disadvantage of these structures is the relatively low parameter of internal nonlinearity of the low-resistance section of the current-voltage characteristics (CVC), which is a critical factor when using such memristors in a cross-matrix architecture (crossbars), due to the presence of leakage currents that make it difficult to read data from an individual memristive element.

[0008] DISCLOSURE OF THE ESSENCE OF THE INVENTION

[0009] The technical result of the claimed invention is to increase the internal nonlinearity of the current-voltage characteristics of memristive elements based on metal-nonstoichiometric oxide nanocomposites with an additional dielectric layer.

[0010] In this description, the internal nonlinearity of the I-V characteristic is understood to be a parameter defined as the ratio of the current I(U) at a given voltage U to the current I(U / 2) at half voltage, that is, I(U) / I(U / 2).

[0011] The technical result is achieved by adding a tunnel-transparent dielectric interlayer of at least 5 nm thickness to the structure during the ion-beam deposition process, located between the layers of the lower Cr / Cu / Cr electrode and the LiNbO3 dielectric interlayer, and after applying the upper Cu electrode, heat treatment for at least one hour of the entire resulting structure in a vacuum at a temperature of 300 to 350°C.

[0012] The essence of the claimed invention is that in the method for producing memristive elements based on a metal-non-stoichiometric oxide nanocomposite, which includes sequential deposition by ion-beam sputtering on a glass-ceramic substrate of a layer of the lower Cr / Cu / Cr electrode, a dielectric interlayer of LiNbO3, a nanocomposite (Co 40 Fe 40 B 20 ) 33.4 (SiO2) 66.6and the upper Cu electrodes, a tunnel-transparent dielectric layer of at least 5 nm thick is additionally deposited between the lower Cr / Cu / Cr electrode and the LiNbO3 dielectric layer, and after the upper Cu electrode is formed, the structure is heat-treated in a vacuum at a temperature of 300 to 350°C for at least 1 hour, which ensures an increase in the internal nonlinearity parameter of the I-V characteristics of the memristive elements to at least 75 when a voltage of 4 V is applied.

[0013] BRIEF DESCRIPTION OF DRAWINGS

[0014] Fig. 1 shows a schematic representation of the resulting element, where:

[0015] 1 - Glass-ceramic substrate;

[0016] 2 - Lower Cr / Cu / Cr electrode

[0017] 3 - Tunnel-transparent dielectric interlayer

[0018] 4 - LiNbO3 dielectric layer

[0019] 5 - Nanocomposite (Co 40 Fe 40 B 20 ) 33.4 (SiO2) 66.6

[0020] 6 - Upper Cu electrode

[0021] In Fig. 2, using the example of a memristive structure Cu / (Co 40 Fe 40 B 20 ) 33.4 (SiO2) 66.6 / LiNbO3 / Ta2O5 / Cr / Cu / Cr / sital presents the dependences of the nonlinearity parameter of the I-V characteristics - I(U) / I(U / 2) on the applied voltage of memristive samples and the results obtained at different annealing temperatures of the samples.

[0022] IMPLEMENTATION OF THE INVENTION

[0023] At the initial stage, by ion beam sputtering at a vacuum value of less than 1⋅10 -6 Torr, the pressure of the working gas - argon equal to 3.9⋅10 -4 Torr and reactive gas - oxygen equal to 1⋅10 -5Torr, the lower Cr / Cu / Cr electrode (2) is deposited on a sitall substrate (1) with layer thicknesses of 100 / 1000 / 100 nm, respectively. Then, a tunnel-transparent dielectric interlayer (3), for example, Ta2O5 with a thickness of at least 5 nm, is applied to the lower Cr / Cu / Cr electrode (2), after which a layer of dielectric interlayer LiNbO3(4) with a thickness of 15 nm is applied to it. A layer of nanocomposite (Co) is deposited on top of the dielectric interlayer LiNbO3(4) 40 Fe 40 B 20 ) 33.4 (SiO2) 66.6 (5) 250 nm thick, onto which the top Cu electrode (6), measuring 0.5×0.2 mm, is then applied through a shadow mask 2 and a thickness of 1000 nm. Then in a vacuum of at least 1⋅10 -6 The resulting structure is heat treated at a temperature of 300 to 350°C for at least 1 hour.

[0024] Along with Ta2O5, Nb2O5 or amorphous Si with a similar thickness of at least 5 nm and heat treatment modes can also be used as a tunnel-transparent dielectric interlayer (3), which makes it possible to obtain comparable values ​​of the internal nonlinearity parameter of the I–V characteristic.

[0025] Using the described process technology allows the creation of memristive elements with I–V characteristics with values ​​of at least 75 when applying a 4 V voltage (Fig. 2), which is sufficient to reduce the negative impact of leakage currents in cross-bar structures. The I–V characteristics were studied using a Keithley 2450 current source meter.

[0026] The claimed method is implemented using standard vacuum ion beam sputtering equipment, power supplies and measuring equipment used in micro- and nanoelectronics, as well as available materials (Cr, Cu, Ta2O5, Nb2O5, amorphous Si, LiNbO3, nanocomposite (Co40 Fe 40 B 20 ) 33.4 (SiO2) 66.6 ), which makes it possible to use it in industry.

Claims

1. A method for producing memristive elements with enhanced internal nonlinearity based on a metal-nonstoichiometric oxide nanocomposite, which consists of sequential deposition by ion-beam sputtering on a glass-ceramic substrate of a layer of the lower Cr / Cu / Cr electrode, a dielectric interlayer of LiNbO3, a nanocomposite (Co 40 Fe 40 B 20 ) 33.4 (SiO2) 66.6 and an upper Cu electrode, characterized in that a tunnel-transparent dielectric layer of at least 5 nm thick is deposited between the layers of the lower Cr / Cu / Cr electrode and the LiNbO3 dielectric interlayer, and after applying the upper Cu electrode, the structure is heat-treated in a vacuum at a temperature of 300 to 350 °C for at least 1 hour.

2. The method according to paragraph 1, characterized in that Nb2O5, Ta2O5 or amorphous Si is used as the tunnel-transparent dielectric layer.

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