High-consistency resistive random access memory and preparation method thereof

Abstract

The invention discloses a high-consistency resistive random access memory and a preparation method thereof, the resistive random access memory comprises a bottom electrode structure, a resistive random structure and a top electrode structure, and the resistance value of the resistive random structure can be adjusted. The corresponding oxide is formed on the bottom electrode structure by using the thermal oxidation process, and the corresponding oxide is diffused into the resistance change oxide in the resistance change structure through the high-temperature process based on the lower thermal stability of the corresponding oxide, so that the resistance change structure has high consistency. The device has high-consistency operation voltage and high and low resistance values, does not need an additional element doping process or ion implantation process, and simplifies the preparation process. The method has the advantages of high consistency, low operating voltage, low thermal budget, high CMOS compatibility and the like.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of semiconductor and integrated circuit, and particularly relates to a nonvolatile memory device with improved consistency of resistance switching parameters by element doping technology. BACKGROUND

[0002] Resistance random access memory (RRAM) generally has a sandwich structure of metal-resistance layer-metal, and stores information by changing the resistance of the resistance material between the upper and lower metal electrodes. Compared with the traditional embedded flash memory technology, this kind of memory has excellent storage properties such as low operating voltage, high on-off ratio, low power consumption, good durability and retention characteristics, and has good scaling advantage.

[0003] Although RRAM has many outstanding advantages, there are still some shortcomings that limit its large-scale commercial use. One is the forming process, that is, the initialization of the resistance switching behavior of RRAM. The forming voltage is much higher than the set voltage, which will limit the peripheral circuit design of RRAM. Another is the low consistency of resistance switching parameters, including the fluctuation of high / low resistance values and set / reset voltages, which are generally believed to be caused by the randomness of the formation and rupture of conductive filaments. SUMMARY

[0004] The purpose of the present application is to solve the problems of high forming voltage and consistency of resistance switching parameters of RRAM, and a new element doping technology based on resistance oxide layer is proposed, which promotes the formation of local wire filaments by mixing germanium oxide and resistance oxide, thereby reducing the forming voltage and the randomness of the formation and rupture of conductive filaments.

[0005] The purpose of the present application is achieved by the following technical solutions:

[0006] According to the first aspect of the present application, a high-consistency resistance random access memory is provided, which is sequentially connected from bottom to top by a bottom electrode structure, a resistance switching structure and a top electrode structure; the bottom electrode structure is germanium, which can form a germanium oxide film on its surface under a thermal oxidation process; the resistance switching structure is a germanium-doped resistance oxide layer, which is generated by the reaction of the germanium oxide film and the resistance oxide at high temperature; and the resistance value of the resistance switching structure can be adjusted.

[0007] Further, the doping concentration of germanium in the bottom electrode structure affects the resistivity of germanium, so that the bottom electrode structure can form a conductive filament in the resistance switching structure under the action of voltage with the top electrode structure.

[0008] Further, the germanium oxide film has low thermal stability and is easy to react with other oxides at high temperature.

[0009] Further, the top electrode structure is selected from Hf x Ge y O z , Ti x Ge y O z , Ni x Ge y O x , Y x Ge y O z , W x Ge y O z , Zr x Ge y O z or Ta x Ge y O z .

[0010] Further, the top electrode structure is an active metal, which can control the breaking and connecting of the conductive filament on the side of the top electrode structure.

[0011] Further, the top electrode structure is selected from Ni, Pd, W, Cu, Co, Ti, Al, Pd, TiN, TaN or Ru.

[0012] Further, the germanium oxide thin film acts as a germanium dopant, which generates more defects in the resistive switching oxide, reduces the oxygen vacancy formation energy of the resistive switching structure, and thus reduces the Forming voltage; the conductive filament is prone to form near the germanium dopant, which reduces the range of the formation and breaking of the conductive filament, and thus reduces the randomness and improves the consistency of the resistive switching parameters.

[0013] According to a second aspect of the present specification, a preparation method of a high-consistency resistive switching memory is provided, which comprises the following steps:

[0014] S1: performing a thermal oxidation process on the bottom electrode structure to form a germanium oxide thin film;

[0015] S2: growing a resistive switching oxide on the structure obtained in S1;

[0016] S3: placing the structure obtained in S2 in a high-temperature environment to mix the germanium oxide thin film and the resistive switching oxide, and generate a germanium-doped resistive switching oxide layer, i.e., a resistive switching structure;

[0017] S4: growing a top electrode metal on the structure obtained in S3 to form a discrete top electrode structure.

[0018] The beneficial effects of the present invention are: first, the present invention has a lower forming voltage; second, the present invention has good parameter consistency; third, the process steps of the present invention are simple; fourth, the operating voltage of the present invention is low, all lower than 3V; in summary, the present invention has the advantages of high consistency, simple preparation process, low preparation cost, high integration and low operating voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 A flow chart for preparing a high-consistency resistive random access memory according to an embodiment of the present invention;

[0021] Figure 2 A Forming-Set-Reset current-voltage characteristic diagram of a high-consistency resistive random access memory provided by an embodiment of the present invention;

[0022] Figure 3 The resistance and voltage distribution diagrams of the high-consistency resistive random access memory provided by the embodiment of the present invention and the conventional resistive random access memory without germanium dopant;

[0023] In the figure, there is a bottom electrode structure 01, a germanium oxide film 02, a resistive oxide 03, a resistive structure 04, and a top electrode structure 05. DETAILED DESCRIPTION

[0024] The technical solution of the present invention is described in detail below with reference to the accompanying drawings and specific embodiments. It is intended to provide a basic understanding of the present invention and is not intended to confirm the key or decisive elements of the present invention or the scope to be protected. It is easy to understand that without changing the essential spirit of the present invention, various replacements, changes and modifications are possible by those skilled in the art without departing from the spirit and scope of the present invention and the appended claims. Therefore, the following specific embodiments and the accompanying drawings are only exemplary illustrations of the technical solution of the present invention and should not be regarded as the entirety of the present invention or as a definition or limitation of the technical solution of the present invention.

[0025] An embodiment of the present invention provides a highly consistent resistive random access memory, comprising a bottom electrode structure 01, a resistive random access structure 04 and a top electrode structure 05; the bottom electrode structure 01, the resistive random access structure 04 and the top electrode structure 05 are directly connected in sequence; and the resistance value of the resistive random access structure 04 can be adjusted.

[0026] Further, the bottom electrode structure 01 is germanium, and the germanium has a high doping concentration, which makes the germanium have a low resistivity, and can form a conductive filament in the resistance change structure 04 under the action of voltage with the top electrode structure 05.

[0027] Further, the bottom electrode structure 01 is germanium, and under a thermal oxidation process, a germanium oxide film 02 can be formed on the surface of the bottom electrode structure 01, and the germanium oxide film 02 has low thermal stability and is easy to react with other oxides at high temperature.

[0028] Further, the resistance change structure 04 is a resistance change oxide layer doped with germanium, which is generated by the reaction of the germanium oxide film 02 and the resistance change oxide 03 at high temperature, and has good consistency of resistance change parameters. The resistance change structure 04 includes but is not limited to Hf x Ge y O z , Ti x Ge y O z , Ni x Ge y O x , Y x Ge y O z , W x Ge y O z , Zr x Ge y O z , Ta x Ge y O z .

[0029] Further, the top electrode structure 05 is an active metal, which can control the breaking and connection of the conductive filament on the side of the top electrode structure. The top electrode structure 05 includes but is not limited to Ni, Pd, W, Cu, Co, Ti, Al, Pd, TiN, TaN, and Ru.

[0030] For the resistance change memory, by applying a voltage on the bottom electrode structure 01 and the top electrode structure 05, an oxygen vacancy conductive filament is formed in the resistance change structure 04, and the device becomes a low resistance state. This process is called Forming. For the device in the low resistance state, by applying a voltage, the conductive filament is broken at the interface between the resistance change structure 04 and the top electrode structure 05, and the device returns to a high resistance state. This process is called Reset. For the device in the high resistance state, by applying a voltage, the broken part of the conductive filament is connected again, and the device returns to a low resistance state. This process is called Set.

[0031] The germanium-doped resistive oxide layer, formed by the high-temperature reaction of the germanium oxide film 02 and the resistive oxide 03, exhibits excellent resistive parameter consistency. Specifically, the fluctuations in the device's high and low resistance values ​​and set / reset voltages across different cycles within the device and between devices are narrower. This is due to the germanium dopant creating more defects in the resistive oxide, which reduces the oxygen vacancy formation energy in the resistive structure 04 and, consequently, the forming voltage. Furthermore, conductive filaments are more likely to form near the germanium dopant, narrowing the range of filament formation and breakage, reducing randomness, and thus achieving excellent resistive parameter consistency.

[0032] The embodiment of the present invention also provides a method for preparing the above-mentioned high consistency resistive random access memory, such as Figure 1 As shown, the method includes the following steps:

[0033] S1: performing a thermal oxidation process on the bottom electrode structure 01 - germanium substrate to form a germanium oxide thin film 02;

[0034] S2: growing a resistive oxide 03 on the structure obtained in S1;

[0035] S3: placing the structure obtained in S2 in a high temperature environment to mix the germanium oxide film 02 and the resistive oxide 03 to generate a germanium-doped resistive oxide layer, i.e., the resistive structure 04;

[0036] S4: On the structure obtained in S3, a top electrode metal is grown to form a discrete top electrode structure 05.

[0037] Figure 2 This is the Forming-Set-Reset current-voltage characteristic diagram of the high-consistency resistive random access memory in the present invention. Specifically: the left figure is the Forming-Set-Reset current-voltage characteristic curve of a conventional resistive random access memory, and it can be observed that the Forming voltage is much higher than the Set voltage; the right figure is the Forming-Set-Reset current-voltage characteristic curve of the resistive random access memory with a germanium-doped resistive random access structure in the present invention, and it can be seen that the Forming voltage and the Set voltage are very close, that is, the Forming-free phenomenon. This is due to the fact that the germanium dopant creates a large number of defects in the resistive random access oxide, which reduces the oxygen vacancy formation energy of the resistive random access structure.

[0038] Figure 3The resistance and voltage distribution diagram of the high-consistency resistive random access memory in the application and the conventional resistive random access memory without germanium dopant is shown. Specifically, the left drawing is a high-low resistance value distribution diagram. It can be observed that the fluctuation range of the low resistance state and the high resistance state of the high-consistency resistive random access memory in the application is smaller than that of the conventional resistive random access memory without germanium dopant. The right drawing is a Set / Reset voltage distribution diagram. It can be observed that the fluctuation range of the Set / Reset voltage of the high-consistency resistive random access memory in the application is smaller than that of the conventional resistive random access memory without germanium dopant.

[0039] The above merely describes the preferred embodiments of the present application. Although the present application has been disclosed with the preferred embodiments, it is not intended to limit the present application. Any person skilled in the art can make many possible changes and modifications to the present application or make equivalent embodiments with the disclosed methods and technical contents without departing from the scope of the present application. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application without departing from the scope of the present application shall still fall within the protection scope of the present application.

Claims

1. A high consistency resistive random access memory, characterized in that: The resistive switching memory comprises a bottom electrode structure, a resistive switching structure, and a top electrode structure connected sequentially from bottom to top; the bottom electrode structure is germanium, and a germanium oxide film can be formed on its surface under a thermal oxidation process; the resistive switching structure is a germanium-doped resistive switching oxide layer, which is formed by the reaction of the germanium oxide film and the resistive switching oxide at high temperature; and the resistance value of the resistive switching structure is adjustable.

2. The high consistency resistive random access memory according to claim 1, wherein: The doping concentration of germanium in the bottom electrode structure affects the resistivity of germanium, so that the bottom electrode structure and the top electrode structure can form a conductive filament in the resistive switching structure under the action of voltage.

3. The high consistency resistive random access memory according to claim 1, wherein: The germanium oxide film has low thermal stability and is easily reacted with other oxides at high temperatures.

4. The high consistency resistive random access memory according to claim 1, wherein: If you choose your own Hf x Ge y O z , Ti x Ge y O z , Ni x Ge y O x , Y x Ge y O z , W x Ge y O z , Zr x Ge y O z Or Ta x Ge y O z .

5. The high consistency resistive random access memory according to claim 1, wherein: The top electrode structure is an active metal, which can control the disconnection and connection of the conductive filament on the top electrode structure side.

6. The high consistency resistive random access memory according to claim 1, wherein: The top electrode structure is selected from Ni, Pd, W, Cu, Co, Ti, Al, Pd, TiN, TaN or Ru.

7. The high consistency resistive random access memory according to claim 1, wherein: The germanium oxide film acts as a germanium dopant, generating more defects in the resistive oxide, thereby reducing the oxygen vacancy formation energy of the resistive structure and thus reducing the forming voltage; Conductive filaments are easily formed near germanium dopants, which narrows the range of conductive filament formation and breakage, thereby reducing randomness and improving the consistency of resistive switching parameters.

8. A method for preparing the highly consistent resistive random access memory according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: S1: performing a thermal oxidation process on the bottom electrode structure to form a germanium oxide film; S2: growing a resistive oxide on the structure obtained in S1; S3: placing the structure obtained in S2 in a high temperature environment to mix the germanium oxide film and the resistive oxide to generate a germanium-doped resistive oxide layer, i.e., a resistive structure; S4: On the structure obtained in S3, a top electrode metal is grown to form a discrete top electrode structure.

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