Metal oxide doped resistive random access memory and preparation method thereof

Abstract

The present invention discloses a metal oxide-doped resistive random access memory and a preparation method thereof, comprising a top electrode layer, a resistive oxide layer and a substrate arranged from top to bottom; the top electrode layer comprises a plurality of top electrodes arranged on the resistive oxide layer; the resistive oxide layer is a doped metal oxide layer; the specific preparation steps include: a) substrate cleaning; b) preparation of the resistive oxide layer; c) preparation of the top electrode layer; d) preparation of the protective layer. The metal oxide layer and the doped powder in this case are prepared by a solution process to achieve the preparation of low-cost RRAM. Compared with RRAM devices with a single or double layer of pure metal oxide layers, the doped RRAM device has better resistive characteristics, and the investment in equipment and raw materials is less, which can achieve large-scale industrial application.

Description

Technical Field

[0001] The present invention relates to the field of microelectronic technology, in particular to a metal oxide powder-doped RRAM (Resistive random access memory) and a preparation method thereof. Background Art

[0002] As one of the most promising non-volatile memories, resistive random access memory (RRAM) has received more and more attention and research due to its excellent performance. RRAM uses metal oxide as a resistive layer to affect the device by applying voltage, so that the memory changes back and forth between high and low configurations, realizing the operation of erasing data and blocking the current channel. Its low voltage, high speed and low power consumption make RRAM devices extremely valuable for research.

[0003] Traditional resistive metal oxide films can be achieved through methods such as sputtering, chemical vapor deposition (CVD), and atomic layer deposition (ALD). However, the above methods are limited by equipment or environmental influences, have high production costs, and cannot meet the needs of large-scale and low-cost industrial production. Summary of the invention

[0004] The purpose of the present invention is to provide a RRAM based on a metal oxide layer doped with metal oxide powder and a preparation method thereof, in view of the insufficiency of research on RRAM in the prior art, which can meet the needs of large-scale and low-cost industrial production.

[0005] The technical solution of the present invention is: a metal oxide-doped resistive random access memory, comprising a top electrode layer, a resistive oxide layer and a substrate arranged from top to bottom; the top electrode layer comprises a plurality of top electrodes arranged on the resistive oxide layer, and a protective layer is provided on the surface of the top electrode away from the resistive oxide layer; the resistive oxide layer is a doped metal oxide layer; the substrate comprises an upper bottom electrode layer and a lower insulating layer stacked.

[0006] Preferably, the protective layer is any one of a metal aluminum thin film layer or a metal tungsten thin film layer.

[0007] Preferably, the top electrode is a cylindrical metal nickel thin film layer or a titanium nitride thin film layer with a thickness of 20-60 nm and a diameter of 0.1-0.4 mm.

[0008] Preferably, the resistive oxide layer is an indium oxide layer doped with gallium oxide powder, and has a thickness of 15 to 90 nm.

[0009] Preferably, the bottom electrode layer is a metal platinum (Pt) thin film layer or an indium tin oxide (ITO) thin film layer, and has a thickness of 50-150 nm.

[0010] Preferably, the insulating layer adopts a three-layer structure arranged in a stacked manner, including a titanium thin film layer, a silicon dioxide thin film layer, a silicon thin film layer stack or a transparent glass layer stack arranged from top to bottom.

[0011] A metal oxide-doped resistive random access memory and a preparation method thereof, wherein the preparation steps include:

[0012] a) Substrate cleaning;

[0013] The purchased substrate was completely immersed in a beaker containing anhydrous ethanol, and the beaker was placed in a deionized water environment for a first ultrasonic cleaning; after the first ultrasonic cleaning, the substrate was completely immersed in a beaker containing acetone, and the beaker was placed in a deionized water environment for a second ultrasonic cleaning; after the second ultrasonic cleaning, the substrate was rinsed with deionized water and blown dry with nitrogen;

[0014] b) preparing a resistive oxide layer;

[0015] Indium nitrate hydrate is prepared into a 0.13-0.21 mol / L In2O3 precursor solution with deionized water; gallium nitrate hydrate is dissolved in deionized water to prepare a 0.2-0.5 mol / L Ga2O3 precursor solution; the prepared Ga2O3 precursor solution is allowed to stand for aging for no more than 1 day; the aged Ga2O3 precursor solution is annealed for no more than 24 hours to obtain Ga2O3 powder; the Ga2O3 powder and The In2O3 precursor solution is doped with Ga2O3 powder at a ratio of 1:4-6.5 to obtain an In2O3 precursor solution, and the solution is allowed to stand for 3-5 hours; the stationary solution is dripped onto the bottom electrode layer and spin-coated, the spin-coating time does not exceed 60 seconds, and the rotation speed is 3500-5000 rpm; after the spin-coating is completed, annealing is performed until the solution solidifies into a film to obtain a doped In2O3 thin film layer, the annealing temperature is 150-350°C, and the annealing time does not exceed 1.5 hours;

[0016] c) preparing a top electrode layer;

[0017] The granular or powdered upper electrode material is plated on the resistive oxide layer by an evaporation coating method to form a top electrode layer;

[0018] d) preparing a protective layer;

[0019] The metal protective layer material in granular or powder form is plated on the surface of each top electrode layer away from the resistive oxide layer by an evaporation coating method to obtain a metal oxide-doped resistive random access memory.

[0020] Preferably, in step a), after ultrasonic cleaning, the substrate is surface plasma cleaned in a vacuum environment to enhance the hydrophilicity of the bottom electrode layer and improve the film-forming performance of the resistive oxide layer; the surface plasma cleaning process needs to last at least 35 minutes, and the resistive oxide layer is prepared within 10 minutes after the surface plasma cleaning is completed.

[0021] Preferably, in step b), the In2O3 precursor solution and the Ga2O3 precursor solution are prepared at 20°C-30°C, stirred at a uniform speed until clarified, and allowed to stand at room temperature for 5-10 minutes after stirring, wherein the purity of the InN3O9.xH2O solute is 99.99%.

[0022] Preferably, the evaporation coating method places granular top electrode layer material or metal protective layer material in a crucible, covers a mask plate with an aperture of 0.1-0.4 mm on the resistive oxide layer or the top electrode layer, and places it in an electron beam evaporation coating machine for evaporation coating operation.

[0023] The advantages of the present invention are:

[0024] 1) The pure solution method is used to prepare the resistive oxide layer, which is simple and convenient to operate, and realizes low-cost RRAM preparation. The equipment and raw material investment is relatively small, and it can be used for the preparation of large-area RRAM devices, realizing large-scale industrial applications;

[0025] 2) Compared with RRAM devices made of single-layer or stacked pure metal oxide layers using traditional processes, the resistive switching effect is better, the voltage required for the set (SET) and reset (RESET) processes is smaller, and its absolute value is less than 2 V. The doped metal oxide layer also improves the tolerance and stability of the device;

[0026] 3) Using single metal or single metal compound materials as the top electrode replaces the traditional oxide material top electrode, further reducing the cost and optimizing the preparation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0028] Figure 1 The schematic diagram is a structure of a metal oxide doped resistive random access memory;

[0029] Figure 2 The figure is a graph showing the change in resistance characteristics of a metal oxide-doped resistive random access memory in the range of 200-300°C;

[0030] In the figure: 100, protective layer; 101, top electrode layer; 200, resistive oxide layer; 300, bottom electrode layer; 400, titanium thin film layer; 401, silicon dioxide thin film layer; 402, silicon thin film layer. DETAILED DESCRIPTION

[0031] Example:

[0032] As attached Figure 1-2 As shown, a metal oxide doped resistive random access memory comprises a top electrode layer, a resistive oxide layer 200 and a substrate arranged from top to bottom; the top electrode layer comprises a plurality of top electrode layers 101 arranged on the resistive oxide layer 200, and a protective layer 100 is arranged on the surface of the top electrode layer away from the resistive oxide layer 200; the resistive oxide layer 200 is a doped metal oxide layer; the substrate comprises an upper bottom electrode layer 300 and a lower insulating layer; the insulating layer is a three-layer stacked arrangement The layer structure includes a titanium (Ti) film layer, a silicon dioxide (SiO2) film layer and a silicon (Si) film layer arranged from top to bottom; the bottom electrode layer is a metal platinum (Pt) film layer with a thickness of 100nm; the protective layer 100 is a metal aluminum (Al) film layer; the top electrode 101 in the top electrode layer is a cylindrical metal compound nickel (Ni) film layer with a thickness of 40nm and a diameter of 0.1mm; the resistive oxide layer 200 is an In2O3 film layer doped with Ga2O3 powder.

[0033] A metal oxide-doped resistive random access memory and a preparation method thereof, wherein the preparation steps include:

[0034] a) Substrate cleaning;

[0035] The substrate was completely immersed in a beaker containing anhydrous ethanol, and the beaker was placed in a deionized water environment for a first ultrasonic cleaning for 10 minutes;

[0036] After the first ultrasonic cleaning, the substrate was rinsed with deionized water to remove residual ethanol impurities, and then the substrate was completely immersed in a beaker containing acetone, and the beaker was placed in a deionized water environment for a second ultrasonic cleaning for 10 minutes;

[0037] After the second ultrasonic cleaning, the substrates were rinsed with deionized water and dried with nitrogen;

[0038] The above-mentioned substrate that has been ultrasonically cleaned and dried is placed in a vacuum chamber of a surface plasma cleaning machine, and surface plasma cleaning is performed to enhance the hydrophilicity of the bottom electrode layer 300; the surface plasma cleaning process lasts for 20 minutes;

[0039] b) preparing a resistive oxide layer;

[0040] At room temperature (preferably 25°C), take indium nitrate hydrate (InN3O9.xH2O) and prepare it into In2O3 precursor solution with deionized water; take 0.9g of InN3O9.xH2O with a purity of 99.99% and put it in a beaker, and add 20ml of deionized water to the beaker to prepare a 0.15 mol / L In2O3 precursor solution; stir at a constant speed until the solution is clear, and then let it stand for 30 minutes;

[0041] At room temperature (preferably 25°C), dissolve gallium nitrate hydrate (Ga(NO3)3.xH2O) in deionized water to prepare a Ga2O3 precursor solution; put 2.21g of Ga(NO3)3.xH2O with a purity of 99.99% in a beaker, and add 20ml of deionized water to the beaker to prepare a 0.3 mol / L Ga2O3 precursor solution; let the prepared Ga2O3 precursor solution stand for aging for 16 hours;

[0042] The Ga2O3 precursor solution that has been completely aged is annealed at a temperature of 250°C and an annealing time of 20 hours to obtain Ga2O3 powder;

[0043] Ga2O3 powder was doped with In2O3 precursor solution at a ratio of 1:5.2;

[0044] Within 10 minutes after the surface plasma cleaning is completed, the doped In2O3 precursor solution is dripped onto the bottom electrode layer 300 through a syringe with a pore size of 0.45 μm and a PES filter, and spin-coated for 45 seconds at a speed of 3500 rpm; after the spin coating is completed, it is placed on a heating plate at 250° C. for annealing for 1 hour, and the In2O3 precursor solution solidifies into a film on the bottom electrode layer 300 to obtain the resistive oxide layer 200;

[0045] c) preparing a top electrode layer;

[0046] A granular metal compound material Ni is placed in a crucible of an electron beam evaporation coating machine, a mask plate with an aperture of 0.1 mm is covered on the resistive oxide layer 200, the mask plate is placed downwardly on a suction plate in a coating machine chamber, the chamber is closed for evaporation coating operation, and the metal compound material Ni is plated on the resistive oxide layer 200 to form a semi-finished product with a top electrode 101;

[0047] d) preparing a protective layer;

[0048] After the top electrode 101 is manufactured, the granular metal material Al is placed in the crucible of the electron beam evaporation coating machine, and a mask plate with an aperture of 0.1 mm is covered on the top electrode 101. The mask plate is placed downward on the suction plate in the coating machine cavity, and the cavity is closed for secondary evaporation coating operation to form a metal Al protective layer 100 on the top electrode 101.

[0049] like Figure 2 The figure shows the test result of the resistive switching effect of the RRAM device of this embodiment. The horizontal axis 0 is used as the dividing line, the positive axis is the SET process, and the negative axis is the RESET process. The absolute values ​​of the voltage bias are all below 2V, and the resistive switching effect is maintained within a certain range. There is a certain probability of gradual change in the RESET process. The doping of the metal oxide layer also improves the tolerance and stability of the device.

[0050] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above examples. The above examples and descriptions are only for explaining the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A metal oxide-doped resistive random access memory, characterized in that: It includes a top electrode layer, a resistive oxide layer and a substrate arranged from top to bottom; The top electrode layer includes a plurality of top electrodes arranged on the resistive oxide layer, and a protective layer is provided on the surface of the top electrode away from the resistive oxide layer. The resistive oxide layer is an indium oxide layer doped with gallium oxide powder; the substrate includes an upper bottom electrode layer and a lower insulating layer stacked in layers.

2. The metal oxide-doped resistive random access memory according to claim 1, characterized in that: The protective layer is any one of a metal aluminum thin film layer or a metal tungsten thin film layer.

3. The metal oxide-doped resistive random access memory according to claim 1, characterized in that: The top electrode is a cylindrical metal nickel film layer or a titanium nitride film layer with a thickness of 20-60 nm.

4. The metal oxide doped resistive random access memory according to claim 1, characterized in that: The bottom electrode layer is a metal platinum thin film layer or an indium tin oxide thin film layer with a thickness of 50-150 nm.

5. The metal oxide-doped resistive random access memory according to claim 1, characterized in that: The insulating layer adopts a three-layer structure arranged in a stacked manner, including a titanium thin film layer, a silicon dioxide thin film layer, a silicon thin film layer stack or a transparent glass layer stack arranged from top to bottom.

6. A method for preparing a metal oxide-doped resistive random access memory, characterized in that: The specific preparation steps include: a) Substrate cleaning; The purchased substrate was completely immersed in a beaker containing anhydrous ethanol, and the beaker was placed in a deionized water environment for a first ultrasonic cleaning; after the first ultrasonic cleaning, the substrate was completely immersed in a beaker containing acetone, and the beaker was placed in a deionized water environment for a second ultrasonic cleaning; after the second ultrasonic cleaning, the substrate was rinsed with deionized water and blown dry with nitrogen; b) preparing a resistive oxide layer; Indium nitrate hydrate is prepared into a 0.13-0.21 mol / L In2O3 precursor solution with deionized water; gallium nitrate hydrate is dissolved in deionized water to prepare a 0.2-0.5 mol / L Ga2O3 precursor solution; the prepared Ga2O3 precursor solution is allowed to stand for aging for no more than 1 day; the aged Ga2O3 precursor solution is annealed for no more than 24 hours to obtain Ga2O3 powder; the Ga2O3 powder and The In2O3 precursor solution is doped with Ga2O3 powder at a ratio of 1:4-6.5 to obtain an In2O3 precursor solution, and the solution is allowed to stand for 3-5 hours; the stationary solution is dripped onto the bottom electrode layer and spin-coated, the spin-coating time does not exceed 60 seconds, and the rotation speed is 3500-5000 rpm; after the spin-coating is completed, annealing is performed until the solution solidifies into a film to obtain a doped In2O3 thin film layer, the annealing temperature is 150-350°C, and the annealing time does not exceed 1.5 hours; c) preparing a top electrode layer; The granular or powdered upper electrode material is plated on the resistive oxide layer by an evaporation coating method to form a top electrode layer; d) preparing a protective layer; The metal protective layer material in granular or powder form is plated on the surface of each top electrode layer away from the resistive oxide layer by an evaporation coating method to obtain a metal oxide-doped resistive random access memory.

7. The method for preparing a metal oxide-doped resistive random access memory according to claim 6, characterized in that: In step a), after ultrasonic cleaning, the substrate is surface plasma cleaned in a vacuum environment to enhance the hydrophilicity of the bottom electrode layer and improve the film-forming performance of the resistive oxide layer; the surface plasma cleaning process needs to last at least 35 minutes, and the resistive oxide layer is prepared within 10 minutes after the surface plasma cleaning is completed.

8. The method for preparing a metal oxide-doped resistive random access memory according to claim 6, characterized in that: In step b), the In2O3 precursor solution and the Ga2O3 precursor solution are prepared at 20°C-30°C, stirred at a constant speed until clarified, and allowed to stand at room temperature for 5-10 minutes after stirring, wherein the purity of the InN3O9.xH2O solute is 99.99%.

9. The method for preparing a metal oxide-doped resistive random access memory according to claim 6, characterized in that: The evaporation coating method places granular top electrode layer material or metal protective layer material in a crucible, covers the resistive oxide layer or the top electrode layer with a mask plate with an aperture of 0.1-0.4 mm, and puts it into an electron beam evaporation coating machine for evaporation coating operation.

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