A double oxide layer RRAM and preparation method thereof

Abstract

The present invention belongs to the technical field of electronic devices, and specifically protects a double oxide layer RRAM based on metal oxide and a preparation method thereof. The double oxide layer RRAM includes a top electrode layer, a resistive oxide layer and a substrate stacked from top to bottom; the resistive oxide layer is a double metal oxide layer of In2O3 and Al2O3 stacked from top to bottom; the top electrode layer includes a plurality of top electrodes arrayed on the resistive oxide layer, and the top electrode is provided with a protective layer on the surface away from the resistive oxide layer; the substrate includes a bottom electrode layer and an insulating layer. The present invention adopts a solution process to prepare both metal oxide layers, so as to realize the preparation of low-cost RRAM. Compared with RRAM devices with a single metal oxide layer, the resistive oxide layer has better resistive characteristics, and the investment in equipment and raw materials is less, so large-scale industrial applications can be realized.

Description

Technical Field

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

[0002] With the rapid development of computer technology, mankind has long entered the digital technology era. As an extremely important basic memory component, memory has an irreplaceable position. Memory can be divided into three categories: disk memory, optical disk memory and semiconductor memory. Among them, semiconductor memory can be divided into two categories: volatile and non-volatile. The so-called volatile memory is that the information stored needs to be maintained by electricity during the process. After the power is off, the written data is lost, such as static RAM (SRAM), dynamic RAM (DRAM), etc. On the contrary, non-volatile memory can continue to retain information after power failure, such as flash memory (Flash), resistive random access memory (RRAM), etc. As the requirements for memory reading speed and access capacity become higher and higher, RRAM stands out among many non-volatile memories with its excellent performance. RRAM uses metal oxide as a storage medium. By changing the voltage applied to the metal oxide layer (Metal Oxide), the memory changes back and forth between high and low resistance states, thereby realizing data erasure, opening or blocking current channels and storage. Because of its significant characteristics such as low voltage, high speed, low power consumption and low cost, RRAM has received widespread attention in the industry.

[0003] Existing research on RRAM mainly focuses on storage mechanism, storage material screening, storage material performance optimization and stability improvement. Among them, research on the preparation process of resistive oxide layer is crucial. Traditional resistive oxide layer films can be achieved through sputtering, chemical vapor deposition (CVD), atomic layer deposition (ALD) and other methods, but the above methods are limited by equipment and have high production costs, and cannot meet the needs of large-scale and low-cost industrial production. Summary of the invention

[0004] In view of the insufficiency of the research on RRAM in the prior art, the present invention provides a double-oxide-layer RRAM based on metal oxide and a preparation method thereof, which can meet the demand for large-scale and low-cost industrial production.

[0005] The present invention is achieved through the following technical solutions:

[0006] The double oxide layer RRAM of the first aspect of the present invention comprises a top electrode layer, a resistive oxide layer and a substrate stacked from top to bottom; the top electrode layer comprises a plurality of top electrodes arrayed on the resistive oxide layer, and the top electrode is provided with a protective layer on the surface away from the resistive oxide layer; the resistive oxide layer is a double-layer metal oxide layer; the substrate comprises an upper bottom electrode layer and a lower insulating layer stacked.

[0007] The protective layer is any one of a metal aluminum thin film layer, a metal titanium thin film layer or a metal tungsten thin film layer.

[0008] The top electrode is a cylindrical metal nickel film layer or a titanium nitride film layer with a thickness of 30 to 80 nm and a diameter of 0.1 to 0.3 mm.

[0009] The double-layer metal oxide layer of the resistive oxide layer is an upper hafnium oxide HfO2 thin film layer and a lower indium oxide In2O3 thin film layer, and the thickness is 5-80nm respectively.

[0010] The bottom electrode layer is a metal platinum (Pt) thin film layer or a silicon (Si) thin film layer, and has a thickness of 50-150 nm.

[0011] Preferably, the insulating layer adopts a three-layer structure stacked up, including a titanium (Ti) film layer / a silicon dioxide (SiO2) film layer / a silicon (Si) film layer arranged from top to bottom.

[0012] A second aspect of the present invention provides a method for preparing the above-mentioned double oxide layer RRAM, comprising:

[0013] a) Substrate cleaning;

[0014] The substrate was sequentially immersed in deionized water, anhydrous ethanol, and deionized water, and ultrasonically cleaned respectively; after the third ultrasonic cleaning, the substrate was rinsed with deionized water and dried with nitrogen gas;

[0015] b) preparing a resistive oxide layer;

[0016] Indium nitrate hydrate InN3O9.xH2O is prepared into a 0.13-0.21 mol / L In2O3 precursor solution; the prepared In2O3 precursor solution is dripped onto the bottom electrode layer and spin-coated. After completion, annealing is performed until the solution solidifies into a film to obtain an In2O3 thin film layer.

[0017] Hafnium oxychloride octahydrate HfOCl2.8 (H2O) is dissolved in ethylene glycol methyl ether (HOCH2CH2OCH3) to prepare a 0.2-0.5 mol / L HfO2 precursor solution; the prepared HfO2 precursor solution is stirred evenly, and then allowed to stand for aging, and the aged HfO2 precursor solution is dropped onto the In2O3 thin film layer and spin-coated, and after the spin-coating is completed, annealing is performed until the solution solidifies into a film to obtain a HfO2 thin film layer;

[0018] c) preparing a top electrode layer;

[0019] The granular or powdered upper electrode material is plated on the resistive oxide layer by an evaporation coating method to form an upper electrode layer;

[0020] d) preparing a protective layer;

[0021] A granular metal protective layer material is plated on the surface of each upper electrode in the upper electrode layer away from the resistive oxide layer by an evaporation coating method to obtain an aluminum oxide-based RRAM.

[0022] 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.

[0023] In step b), the In2O3 precursor solution is prepared at 20°C to 30°C, stirred at a constant speed until it becomes clear, and allowed to stand at room temperature for 5 to 10 minutes after stirring, wherein the purity of the InN3O9.xH2O solute is 99.99%.

[0024] In step b), the In2O3 precursor solution is dripped onto the bottom electrode layer through a syringe with a polyethersulfone resin filter, preferably with a pore size of 0.45 μm.

[0025] In step b), the annealing temperature of the obtained In2O3 thin film layer is 150-350°C, and the annealing time does not exceed 1 hour.

[0026] In step b), the prepared HfO2 precursor solution is stirred in a water bath environment, the water bath temperature is 50-80°C, and the stirring time does not exceed 2.5h.

[0027] In step b), the uniformly stirred HfO2 precursor solution is allowed to stand for aging, and the standing time is no more than 3 days.

[0028] In step b), the annealing temperature when preparing the HfO2 thin film layer is 150-350°C, and the annealing time does not exceed 1 hour.

[0029] In step c), the evaporation coating method places the granular top electrode layer material or metal protective layer material in a crucible, covers the resistive oxide layer with a mask plate with an aperture of 0.1 to 0.3 mm, and puts it into an electron beam evaporation coating machine for evaporation coating operation.

[0030] The preparation process of the double oxide layer RRAM includes:

[0031] a) Substrate cleaning;

[0032] The purchased substrate is completely immersed in a beaker containing deionized water, and the beaker is placed in a deionized water environment for a first ultrasonic cleaning; after the first ultrasonic cleaning, the substrate is completely immersed in a beaker containing anhydrous ethanol, and the beaker is placed in a deionized water environment for a second ultrasonic cleaning; after the second ultrasonic cleaning, the substrate is rinsed with deionized water to remove residual impurities, and then the substrate is completely immersed in a beaker containing deionized water, and the beaker is placed in a deionized water environment for a third ultrasonic cleaning; after the third ultrasonic cleaning, the substrate is rinsed with deionized water and blown dry with nitrogen;

[0033] b) preparing a resistive oxide layer;

[0034] Take indium nitrate hydrate (InN3O9.xH2O) and use deionized water to prepare a 0.13-0.21 mol / L In2O3 precursor solution; drop the prepared In2O3 precursor solution on the bottom electrode layer and perform spin coating, the spin coating time does not exceed 60s, and the rotation speed is 2500-3500rpm; after spin coating, annealing is performed until the solution solidifies into a film to obtain an In2O3 thin film layer, the annealing temperature is 150-350°C, and the annealing time does not exceed 1h. Take hafnium oxychloride octahydrate (HfOCl2.8(H2O)) and dissolve it in ethylene glycol methyl ether (HOCH2CH2OCH3) to prepare a 0.2-0.5 mol / L HfO2 precursor solution; stir the prepared HfO2 precursor solution in a water bath environment, the water bath temperature is 50-80°C, and the stirring time does not exceed 2.5 hours; let the stirred HfO2 precursor solution stand for aging, and the standing time does not exceed 3 days; drop the aged HfO2 precursor solution on the In2O3 thin film layer and spin-coat it, the spin-coating time does not exceed 40 seconds, and the rotation speed is 2500-3500rpm; after the spin coating is completed, annealing is performed until the solution solidifies into a film to obtain a HfO2 thin film layer, the annealing temperature is 150-350°C, and the annealing time does not exceed 1 hour;

[0035] c) preparing a top electrode layer;

[0036] The granular or powdered upper electrode material is plated on the resistive oxide layer by an evaporation coating method to form an upper electrode layer;

[0037] d) preparing a protective layer;

[0038] A granular metal protection layer material is plated on the surface of each upper electrode in the upper electrode layer away from the resistive oxide layer by an evaporation coating method to obtain an aluminum oxide-based RRAM.

[0039] Technical Effects

[0040] Compared with the prior art, the present invention has the following technical effects:

[0041] 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;

[0042] 2) Compared with the RRAM device with a single-layer resistive oxide layer made by traditional process, the resistive effect is better, the voltage required for the set (SET) and reset (RESET) process is smaller, and its absolute value is between 1 and 2V. The double-layer resistive oxide layer also improves the tolerance and stability of the device;

[0043] 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

[0044] Figure 1 It is a structural schematic diagram of Example 1;

[0045] Figure 2 The figure is a graph showing the change in resistance switching characteristics of Example 1 within the range of 200 to 300°C;

[0046] In the figure: a metal protection layer 100 , a top electrode 101 , a second resistive oxide layer 200 , a first resistive oxide layer 201 , a bottom electrode layer 300 , a titanium thin film layer 400 , a silicon dioxide thin film layer 401 , and a silicon thin film layer 402 . DETAILED DESCRIPTION

[0047] The specific implementation of the present invention is described below with reference to the accompanying drawings.

[0048] Example 1

[0049] like Figure 1 As shown, this embodiment relates to a double oxide layer RRAM based on metal oxide, including a top electrode layer, a resistive oxide layer and a substrate stacked from top to bottom, wherein the top electrode layer includes a plurality of top electrodes 101 arrayed on the resistive oxide layer 200, and a metal protective layer 100 is provided on the surface of the top electrode 101 away from the resistive oxide layer 200;

[0050] The metal protection layer 100 is a metal tungsten (W) thin film layer.

[0051] The top electrode 101 in the top electrode layer is a cylindrical metal compound titanium nitride (TiN) thin film layer with a thickness of 30-80 nm and a diameter of 0.1-0.3 mm. Preferably, the thickness is 60 nm and the diameter is 0.1 mm.

[0052] The second resistive oxide layer 200 is a HfO 2 thin film layer, and the first resistive oxide layer 201 is an In 2 O 3 thin film layer.

[0053] The substrate includes a bottom electrode layer 300 and an insulating layer;

[0054] The bottom electrode layer is a metal platinum (Pt) thin film layer with a thickness of 50-150 nm, preferably, a thickness of 100 nm.

[0055] The insulating layer adopts a three-layer structure arranged in a stacked manner, including a titanium (Ti) film layer / a silicon dioxide (SiO2) film layer / a silicon (Si) film layer arranged from top to bottom.

[0056] This embodiment relates to a method for preparing the above RRAM, including:

[0057] a) Substrate cleaning;

[0058] The substrate is completely immersed in a beaker containing deionized water, and the beaker is placed in a deionized water environment for a first 15-minute ultrasonic cleaning;

[0059] After the first ultrasonic cleaning, the substrate was completely immersed in a beaker containing anhydrous ethanol, and the beaker was placed in a deionized water environment for a second ultrasonic cleaning for 15 minutes;

[0060] After the second 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 deionized water, and the beaker was placed in a deionized water environment for a third ultrasonic cleaning for 15 minutes;

[0061] After the third ultrasonic cleaning, the substrate was rinsed with deionized water and dried with nitrogen;

[0062] 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 45 minutes;

[0063] b) preparing a resistive oxide layer;

[0064] At room temperature (25°C), take indium nitrate hydrate (InN3O9.xH2O) and use deionized water to prepare a 0.13-0.21 mol / L In2O3 precursor solution; preferably, take 0.9 g of InN3O9.xH2O with a purity of 99.99% and place it in a beaker, and add 20 ml of deionized water to the beaker to prepare a 0.15 mol / L In2O3 precursor solution; stir at a uniform speed until the solution is clear, and then let it stand for 25 minutes;

[0065] Within 10 minutes after the surface plasma cleaning is completed, the prepared 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 rotation speed of 2500-3500 rpm; after the spin coating is completed, it is placed on a heating plate at 200°C-300°C for annealing for 1 hour, and the In2O3 precursor solution solidifies into a film on the bottom electrode layer 300 to obtain a resistive oxide layer 201;

[0066] At room temperature (25°C), hafnium oxychloride octahydrate (HfOCl2.8(H2O)) is dissolved in ethylene glycol methyl ether (HOCH2CH2OCH3) to prepare a 0.2-0.5 mol / L HfO2 precursor solution; preferably, 2.46 g of HfOCl2.8(H2O) with a purity of 99.99% is placed in a beaker, and 20 ml of ethylene glycol methyl ether solvent is added to the beaker to prepare a 0.3 mol / L HfO2 precursor solution; the prepared HfO2 precursor solution is stirred in a water bath environment, the water bath temperature is 50-80°C, and the stirring time does not exceed 2.5h; preferably, the water bath temperature is 70 degrees, and the stirring time is 2h; the evenly stirred HfO2 precursor solution is allowed to stand for aging, and the standing time does not exceed 3 days; preferably, the standing time is 2 days;

[0067] The fully configured HfO2 precursor solution is dripped onto the resistive oxide layer 201 through a syringe with a 0.22 μm pore size and a PTFE filter, and spin-coated for 30 seconds at a rotation speed of 2500-3500 rpm; after the spin-coating is completed, it is placed on a heating plate at 200° C. to 300° C. for annealing for 1 hour, and the HfO2 precursor solution solidifies into a film on the resistive oxide layer 201 to obtain the resistive oxide layer 200;

[0068] c) preparing a top electrode layer;

[0069] A granular metal compound material TiN 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 TiN is plated on the resistive oxide layer 200 to form a semi-finished product with a top electrode 101;

[0070] d) preparing a protective layer;

[0071] After the top electrode 101 is manufactured, the granular metal material W 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 W protective layer 100 on the top electrode 101.

[0072] like Figure 2 The figure shows the resistive switching effect test result 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 4V, and the resistive switching effect is maintained within a certain range. A gradual change phenomenon with a certain probability occurs in the RESET process.

[0073] 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 double oxide layer RRAM, characterized in that: It includes a top electrode layer, a resistive oxide layer and a substrate stacked from top to bottom; The top electrode layer comprises a plurality of top electrodes arrayed on the resistive oxide layer, wherein a protective layer is provided on the surface of the top electrode away from the resistive oxide layer; the resistive oxide layer is a double-layer metal oxide layer, wherein the upper layer is a hafnium oxide thin film layer, and the lower layer is an indium oxide thin film layer; the substrate comprises an upper bottom electrode layer and a lower insulating layer stacked in layers; The double oxide layer RRAM is manufactured according to the following steps: a) Substrate cleaning; The substrate was sequentially immersed in deionized water, anhydrous ethanol, and deionized water, and ultrasonically cleaned respectively; after the third ultrasonic cleaning, the substrate was rinsed with deionized water and dried with nitrogen gas; b) preparing a resistive oxide layer; Indium nitrate hydrate InN3O9.xH2O is prepared into a 0.13-0.21 mol / L In2O3 precursor solution; the prepared In2O3 precursor solution is dripped onto the bottom electrode layer and spin-coated. After completion, annealing is performed until the solution solidifies into a film to obtain an In2O3 thin film layer. Hafnium oxychloride octahydrate HfOCl2.8 (H2O) is dissolved in ethylene glycol methyl ether to prepare a 0.2-0.5 mol / L HfO2 precursor solution; the prepared HfO2 precursor solution is stirred evenly, and then allowed to stand for aging, and the aged HfO2 precursor solution is dropped onto the In2O3 thin film layer and spin-coated, and after the spin-coating is completed, annealing is performed until the solution solidifies into a film to obtain the HfO2 thin film layer; 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 an upper electrode layer; d) preparing a protective layer; The double oxide layer RRAM is manufactured by coating a granular metal protective layer material on the surface of each upper electrode in the upper electrode layer away from the resistive oxide layer through an evaporation coating method.

2. A double oxide layer RRAM according to claim 1, characterized in that: The protective layer is any one of a metal aluminum thin film layer, a metal titanium thin film layer or a metal tungsten thin film layer.

3. The double oxide layer RRAM 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 30-80 nm.

4. A double oxide layer RRAM according to claim 3, characterized in that: The thickness of the upper hafnium oxide film layer and the lower indium oxide film layer are 5-80 nm respectively.

5. The double oxide layer RRAM according to claim 1, characterized in that: The bottom electrode layer is a metal platinum thin film layer or a silicon thin film layer with a thickness of 50-150nm.

6. The double oxide layer RRAM according to claim 1, characterized in that: The insulating layer adopts a three-layer structure arranged in a stacked manner, including a titanium film layer / a silicon dioxide film layer / a silicon film layer arranged from top to bottom.

7. The double oxide layer RRAM according to claim 1, characterized in that: In step a), after ultrasonic cleaning, the substrate is subjected to surface plasma cleaning in a vacuum environment. The surface plasma cleaning process needs to last for at least 35 minutes. The resistive oxide layer is prepared within 10 minutes after the surface plasma cleaning is completed.

8. The double oxide layer RRAM according to claim 1, characterized in that: In step b), the In2O3 precursor solution is dripped onto the bottom electrode layer through a syringe with a polyethersulfone resin filter; the annealing temperature of the obtained In2O3 thin film layer is 150-350°C, and the annealing time does not exceed 1 hour.

9. The double oxide layer RRAM according to claim 1, characterized in that: In step b), the prepared HfO2 precursor solution is stirred in a water bath environment, the water bath temperature is 50-80°C, and the stirring time is not more than 2.5 hours. When the HfO2 thin film layer is obtained, the annealing temperature is 150-350°C, and the annealing time is not more than 1 hour.

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