Preparation method and application of oxide film with high thermal stability

Abstract

The invention discloses a preparation method and application of an oxide film with high thermal stability, and belongs to the field of integrated circuit micro-nano electronic devices. A magnetron sputtering process is adopted, a sputtering target material is an indium-aluminum-zinc-oxygen target material with the mass ratio of indium oxide being 50-90%, the mass ratio of aluminum oxide being 0.1-10% and the mass ratio of zinc oxide being 10-50%, and the prepared film has high-temperature thermal stability. Under a high-temperature condition, the thin film is in an amorphous state after long-time thermal annealing treatment, and the defect concentration in the thin film is kept stable. Furthermore, the oxide transistor prepared by the method is high in performance thermal stability, and the preparation process is simple in step and low in cost.

Description

Technical Field

[0001] The invention belongs to the field of integrated circuit micro-nano electronic devices, and in particular relates to a preparation method of an oxide transistor material with high thermal stability and application thereof. Background Art

[0002] As the cornerstone of the information society, integrated circuits are increasingly affecting people's lives and playing a vital role in consumer electronics, medical care, artificial intelligence, the Internet of Things, aerospace, military, communications and other fields. Integrated circuits have been developed for more than 60 years guided by Moore's Law. However, as integrated circuit products are driven by the requirements for higher speed, energy efficiency and integration density, it is becoming increasingly challenging to reduce the size of transistors while maintaining low power consumption.

[0003] In recent years, oxide transistors have become a research hotspot in the field of integrated circuits due to their ultra-low leakage current, high uniformity, and good compatibility with silicon-based manufacturing processes. So far, various new applications based on oxide transistors have been developed, such as flexible chips, capacitor-free DRAM, and advanced sensors. In order to improve the integration density, a feasible way is to vertically integrate oxide transistors through back-end-of-line (BEOL) and monolithic three-dimensional (M3D) integration. Therefore, low-temperature manufacturing of oxide transistors, including thin film deposition and device optimization processes, has been widely studied to avoid performance degradation under high-temperature processes. However, in order to achieve a balance between electrical performance and bias stress stability, oxide transistors usually need to be annealed at temperatures of about or even above 400°C. Therefore, another way to achieve BEOL and M3D integration is to develop oxide materials and oxide transistors with better thermal stability. Therefore, the proposal and development of original technologies for high thermal stability oxide materials, structures, and preparation methods have very important research value and are of great significance to the development of my country's integrated circuit technology. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing an oxide film with high thermal stability and its application, which can effectively improve the performance stability of oxide transistors under high temperature conditions, and as the heat treatment time increases, the device performance remains stable, laying the foundation for applications in the field of monolithic three-dimensional integration.

[0005] The technical solution provided by the present invention is as follows:

[0006] A method for preparing an oxide film with high thermal stability, characterized in that the specific steps include the following:

[0007] 1) The substrate is fixed on the tray of the magnetron sputtering equipment;

[0008] 2) The back gas pressure of the magnetron sputtering equipment chamber is pumped to 1×10-4 -9×10 -4 Pa;

[0009] 3) Oxygen and argon are introduced into the cavity of the magnetron sputtering equipment, and the pressure control valve is adjusted to set the cavity pressure to 1 Pa;

[0010] 4) Turn on the tray rotation button and set the speed to 5-20 rpm;

[0011] 5) Turn on the radio frequency power supply, pre-sputter for 1-5 minutes, and the sputtering target used in the magnetron sputtering process is an indium aluminum zinc oxygen target material in which the mass ratio of indium oxide is 50-90%, the mass ratio of aluminum oxide is 0.1-10%, and the mass ratio of zinc oxide is 10-50%;

[0012] 6) Turn the magnetron sputtering target baffle and sputter for 1-30 minutes;

[0013] 7) After the deposition of the indium aluminum zinc oxide film is completed, turn off the RF power supply and the magnetron sputtering equipment.

[0014] Furthermore, the substrate is a single crystal silicon substrate, a silicon oxide substrate, a glass substrate, or a flexible substrate (PET and PI).

[0015] The present invention further provides an oxide transistor, comprising a substrate, a gate electrode, a dielectric layer, an oxide active layer and a source / drain electrode, characterized in that the oxide active layer is an indium aluminum zinc oxide thin film obtained by the preparation method according to claim 1.

[0016] The oxide transistor includes two types: bottom gate structure and top gate structure. The bottom gate structure is as follows: the gate electrode is located on the substrate, the dielectric layer is located on the gate electrode, the oxide active layer is located on the dielectric layer, and the source / drain electrode is located on the oxide active layer. The top gate structure is as follows: the oxide active layer is located on the substrate, the source / drain electrodes are located on both sides of the active layer, the dielectric layer is located on the oxide active layer, and the gate electrode is located on the dielectric layer.

[0017] Beneficial effects of the present invention:

[0018] The present invention proposes a method for preparing an oxide film with high thermal stability. The indium aluminum zinc oxide film obtained by the present invention has high-temperature thermal stability. That is, under high temperature conditions, after a long period of thermal annealing, the film is in an amorphous state, and the defect concentration in the film remains stable. The performance of the oxide transistor further prepared by the present invention has high thermal stability, that is, as the heat treatment time increases, the device performance remains stable, laying the foundation for the application of oxide films in the field of monolithic three-dimensional integration. In addition, the preparation process of the present invention is simple and low-cost, further providing technical support for the development of integrated circuits in my country. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a diagram showing the X-ray diffraction analysis result of the indium aluminum zinc oxide thin film prepared by the present invention;

[0020] Figure 2 The figure is a result of X-ray photoelectron spectroscopy of the indium aluminum zinc oxide thin film prepared by the present invention;

[0021] Figure 3 Schematic diagram of the structure of the oxide transistor prepared by the present invention, wherein (a) is a bottom gate structure and (b) is a top gate structure;

[0022] Figure 4 A flow chart of an oxide transistor prepared using the present invention;

[0023] Figure 5 A current-voltage characteristic diagram of the oxide transistor prepared by the present invention;

[0024] Figure 6 for Figure 3-Figure 4 Legend for . DETAILED DESCRIPTION

[0025] The present invention is further described below by examples in conjunction with the accompanying drawings of the specification. It should be noted that the purpose of publishing the embodiments is to help further understand the present invention, but those skilled in the art can understand that various substitutions and modifications are possible without departing from the spirit and scope of the present invention and the attached claims. Therefore, the present invention should not be limited to the contents disclosed in the embodiments, and the scope of protection claimed by the present invention shall be subject to the scope defined in the claims.

[0026] The preparation steps of the indium aluminum zinc oxide thin film of the present invention are as follows:

[0027] (1) The substrate is fixed on the tray of the magnetron sputtering equipment;

[0028] (2) The back gas pressure of the magnetron sputtering equipment chamber is pumped down to 1×10 -4 -9×10 -4 Pa;

[0029] (3) Oxygen and argon are introduced into the cavity of the magnetron sputtering equipment, and the pressure control valve is adjusted to set the cavity pressure to 1 Pa.

[0030] (4) Turn on the tray rotation button and set the speed to 5-20 rpm.

[0031] (5) Turn on the radio frequency power supply and pre-sputter for 1-5 minutes. The sputtering target used in the magnetron sputtering process is an indium aluminum zinc oxygen target material in which the mass ratio of indium oxide is 50-90%, the mass ratio of aluminum oxide is 0.1-10%, and the mass ratio of zinc oxide is 10-50%.

[0032] (6) Turn the magnetron sputtering target baffle to officially sputter for 1-30 minutes.

[0033] (7) After the deposition of the indium aluminum zinc oxide (IAZO) film is completed, turn off the RF power supply and the magnetron sputtering equipment.

[0034] The X-ray diffraction analysis results of the IAZO film of the present invention are shown in FIG. Figure 1 As shown in FIG. 1 , after deposition, under the conditions of air and oxygen at 400 degrees Celsius, the indium aluminum zinc oxide film presents an amorphous structure, and the defect concentration in the film remains stable. The X-ray photoelectron spectroscopy result of the indium aluminum zinc oxide film prepared by the present invention is shown in FIG. Figure 2 As shown in the figure, under the condition of 400 degrees Celsius in air, the O1s spectrum of the InAlZnO film is deconvoluted into two peaks using Gaussian fitting, representing the metal-oxygen bond (O I ,529.88eV) and oxygen vacancies (O II ,531.42eV), the oxygen defect content of the film remained stable at different times.

[0035] Figure 3 As shown, the structure diagram of the oxide transistor prepared by the present invention includes a substrate, a gate electrode, a dielectric layer, an oxide active layer and a source / drain electrode, wherein the oxide active layer is an indium aluminum zinc oxide thin film prepared by the present invention. Among them, the bottom gate structure is as follows: the gate electrode is located on the substrate, the dielectric layer is located on the gate electrode, the oxide active layer is located on the dielectric layer, and the source / drain electrode is located on the oxide active layer. The top gate structure is as follows: the oxide active layer is located on the substrate, the source / drain electrodes are located on both sides of the active layer, the dielectric layer is located on the oxide active layer, and the gate electrode is located on the dielectric layer.

[0036] Figure 4 The figure shows a flow chart of the preparation of oxide crystals of the present invention. The preparation method of the bottom-gate oxide transistor comprises the following specific steps:

[0037] (1) placing the substrate in acetone, ethanol, and deionized water for ultrasonic cleaning in sequence;

[0038] (2) Using photolithography to define the gate electrode pattern;

[0039] (3) depositing a gate electrode film on the substrate using a magnetron sputtering process;

[0040] (4) using a lift-off process to form a gate electrode structure;

[0041] (5) Using photolithography technology to define the patterns of the dielectric layer and the oxide active layer;

[0042] (6) depositing a dielectric layer thin film on the gate electrode using an atomic layer deposition process;

[0043] (7) On the dielectric layer, the indium aluminum zinc oxide thin film prepared by the preparation method of the present invention is used as an oxide active layer;

[0044] (8) using a lift-off process to form a dielectric layer and an oxide active layer structure;

[0045] (9) Using photolithography technology to define the source / drain electrode pattern;

[0046] (10) depositing source / drain electrode thin films on the oxide active layer using a magnetron sputtering process;

[0047] (11) using a lift-off process to form a source / drain electrode structure;

[0048] (12) Use annealing process to optimize the processing of oxide transistors.

[0049] The method for preparing a top-gate oxide transistor of the present invention comprises the following specific steps:

[0050] (1) placing the substrate in acetone, ethanol, and deionized water for ultrasonic cleaning in sequence;

[0051] (2) Using photolithography to define the active layer pattern;

[0052] (3) The indium aluminum zinc oxide thin film prepared by the preparation method of the present invention is used as an active layer thin film;

[0053] (4) using a lift-off process to form an active layer structure;

[0054] (5) Using photolithography technology to define source / drain deposition patterns;

[0055] (6) depositing source / drain electrode thin films on the active layer using a magnetron sputtering process;

[0056] (7) Using a lift-off process to form a source / drain electrode structure;

[0057] (8) Using photolithography to define the dielectric layer pattern;

[0058] (9) Depositing a dielectric film on the source / drain electrodes using an atomic layer deposition process;

[0059] (10) using a stripping process to form a dielectric structure;

[0060] (11) Using photolithography process to define the top gate electrode pattern;

[0061] (12) depositing a gate electrode pattern on the dielectric layer by a magnetron sputtering process;

[0062] (13) using a lift-off process to form a top gate electrode structure;

[0063] (14) An annealing process is used to optimize the processing of oxide transistors.

[0064] Among them, the gate electrode is a combination of one or more metals such as aluminum, titanium, molybdenum, gold, palladium, platinum, tantalum, etc., or a combination of one or more conductive films such as transparent conductive films indium tin oxide (ITO) and aluminum zinc oxide (AZO), and the thickness of the gate electrode is 2-500 nanometers.

[0065] The dielectric layer is Al 2 O 3 , HfO 2 、TiO 2 Or doped with Al 2 O 3 , HfO 2 、TiO 2 Such high-k dielectric materials, the thickness of the dielectric layer is 2-100 nanometers.

[0066] The thickness of the indium aluminum zinc oxide film is 1-100 nanometers.

[0067] The source / drain electrode is a combination of one or more metals such as aluminum, titanium, molybdenum, gold, palladium, platinum, tantalum, etc., or a combination of one or more conductive films such as transparent conductive films indium tin oxide (ITO) and aluminum zinc oxide (AZO), and the thickness of the source / drain electrode is 2-500 nanometers.

[0068] The current-voltage characteristics of the oxide transistor prepared by the present invention are as follows Figure 5 As shown, the device shows good transfer characteristics, with a field effect mobility of >60cm 2 V -1 s -1 .

[0069] Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the art can use the above disclosed methods and technical contents to make many possible changes and modifications to the technical solution of the present invention without departing from the scope of the technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of protection of the technical solution of the present invention.

Claims

1. A method for preparing an oxide film with high thermal stability, characterized in that: The specific steps include the following: 1) The substrate is fixed on the tray of the magnetron sputtering equipment; 2) The back gas pressure of the magnetron sputtering equipment chamber is pumped to 1×10 -4 -9×10 -4 Pa; 3) Oxygen and argon are introduced into the cavity of the magnetron sputtering equipment, and the pressure control valve is adjusted to set the cavity pressure to 1 Pa; 4) Turn on the tray rotation button and set the speed to 5-20 rpm; 5) Turn on the radio frequency power supply, pre-sputter for 1-5 minutes, and the sputtering target used in the magnetron sputtering process is an indium aluminum zinc oxygen target material in which the mass ratio of indium oxide is 50-90%, the mass ratio of aluminum oxide is 0.1-10%, and the mass ratio of zinc oxide is 10-50%; 6) Turn the magnetron sputtering target baffle and sputter for 1-30 minutes; 7) After the deposition of the indium aluminum zinc oxide film is completed, turn off the RF power supply and the magnetron sputtering equipment.

2. The preparation method according to claim 1, characterized in that The substrate is a single crystal silicon substrate, a silicon oxide substrate, a glass substrate or a flexible substrate.

3. An oxide transistor comprising a substrate, a gate electrode, a dielectric layer, an oxide active layer and source / drain electrodes, characterized in that: The oxide active layer is an indium aluminum zinc oxide thin film obtained by the preparation method described in claim 1.

4. The oxide transistor according to claim 3, wherein: The gate electrode is a combination of one or more metals such as aluminum, titanium, molybdenum, gold, palladium, platinum, tantalum, etc., or a combination of one or more conductive films such as indium tin oxide and aluminum zinc oxide. The thickness of the gate electrode is 2-500 nanometers.

5. The oxide transistor according to claim 3, wherein: The dielectric layer is Al2O3, HfO2, TiO2 or a dielectric material doped with Al2O3, HfO2 or TiO2, and the thickness of the dielectric layer is 2-100 nanometers.

6. The oxide transistor according to claim 3, wherein: The thickness of the indium aluminum zinc oxide film is 1-100 nanometers.

7. The oxide transistor according to claim 3, wherein: The source / drain electrode is a combination of one or more of aluminum, titanium, molybdenum, gold, palladium, platinum, and tantalum metals, or a combination of one or more of indium tin oxide and aluminum zinc oxide conductive films, and the thickness of the source / drain electrode is 2-500 nanometers.

8. The oxide transistor according to claim 3, wherein: The oxide transistor is a bottom gate structure, wherein a gate electrode is located on a substrate, a dielectric layer is located on the gate electrode, an oxide active layer is located on the dielectric layer, and a source / drain electrode is located on the oxide active layer.

9. The oxide transistor according to claim 3, wherein: The oxide transistor is a top gate structure, wherein an oxide active layer is located on a substrate, source / drain electrodes are located on both sides of the active layer, a dielectric layer is located on the oxide active layer, and a gate electrode is located on the dielectric layer.

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