Polyimide-inorganic oxide composite dielectric films, their preparation methods, and flexible thin-film transistors

Abstract

This application relates to a polyimide-oxide-based composite dielectric film, comprising a polyimide layer formed by molecular layer deposition on a substrate and an inorganic oxide layer formed by atomic layer deposition. This application also relates to a method for preparing this polyimide-oxide-based composite dielectric film. This polyimide-inorganic oxide-based composite dielectric film possesses intrinsic flexibility and excellent insulating gate dielectric properties, and can be widely used in flexible electronic circuits. Using this polyimide-inorganic oxide-based composite dielectric film, all-carbon nanotube transistors with the composite dielectric film as the insulating gate dielectric layer and various flexible integrated circuit units, including inverters, ring oscillators, and logic gate circuits, can be fabricated. These flexible devices and circuits exhibit good mechanical properties; the inverter circuit has excellent gain performance and can be used as an analog amplifier to amplify small signals at the millivolt level; ultra-low drive voltage and ultra-low power consumption characteristics can also be achieved.

Description

Technical Field

[0001] This application relates to the field of integrated circuit dielectric materials, and more specifically, to flexible composite dielectric materials based on polyimide-inorganic oxides. This application also relates to flexible thin-film transistors incorporating the composite dielectric material. Background Technology

[0002] In recent years, the development of emerging technologies such as the Internet of Things (IoT) and artificial intelligence (AI) has brought numerous conveniences to people's lives, enabling the rise and widespread application of various "smart" technologies, including intelligent robots, smart homes, smart cities, and smart manufacturing. Flexible and wearable electronic circuits are an indispensable and important component of these "smart" technologies. They tightly connect the electronic devices around the user with the user themselves, establishing a fast and close interaction between the device and the user. Many cutting-edge fields, such as medical and healthcare, sensing and intelligent machinery, and brain-computer interfaces, have widely applied flexible electronic circuits and are continuously expanding their application scenarios and functions. Unlike traditional microelectronics, the basic building block of flexible electronic circuits is the thin-film transistor (TFT). Through TFT-based integration technology, flexible electronic circuits have already achieved applications such as digital and analog integration circuits, sensor arrays, and display panels. At the same time, the rapid development of flexible electronics technology has also placed increasingly higher and more complex demands on the characteristics and performance of TFTs, such as real-time interactive performance, high bending tolerance, and multi-functional integration capabilities. Among these, simultaneously achieving excellent electrical performance and mechanical flexibility is a significant challenge in the current development of flexible TFT technology. While thin-film transistor (TFT) circuits can achieve a certain degree of flexibility through engineering-level process design and structural optimization based on existing material systems, such flexible designs typically come at the cost of reduced circuit integration density. Therefore, fabricating intrinsically flexible TFTs using intrinsically flexible material systems and applying them to the construction of flexible integrated circuits is a crucial technological route in the current development of flexible electronics technology.

[0003] Against this backdrop, carbon nanotube-based thin-film transistors (TFTs) have recently attracted widespread attention. Carbon nanotubes possess excellent flexibility and can be used simultaneously as semiconductor channels and electrode / wire connection materials in TFT devices / circuits. In particular, TFTs where both the semiconductor layer and electrode / wire connections are made of carbon nanotubes are called all-carbon nanotube TFTs; this type of device utilizes the high mobility and mechanical flexibility of carbon nanotubes, showing strong potential in flexible electronic circuits. However, the performance of carbon nanotube-based TFTs is still limited by the insulating gate dielectric layer. Currently, carbon nanotube-based TFTs typically use brittle, high-dielectric-constant oxide materials as the insulating gate dielectric layer. Fracture under bending conditions can cause leakage current in the device, thus limiting its overall performance. Intrinsically flexible organic polymer dielectric materials are considered an alternative to the insulating gate dielectric layer material in carbon nanotube-based TFTs; however, their lower dielectric constant and the higher physical thickness required to achieve insulation properties further limit the overall performance of the device. Hybrid dielectric materials prepared from high-dielectric-constant oxides and organic polymers are another proposed solution for insulating gate dielectric layers, replacing pure oxide dielectric materials. These materials achieve a balance between dielectric and mechanical properties, ensuring excellent overall device performance. However, the strong phase separation characteristics of hybrid materials and the limitations of solution-based fabrication processes in large-scale fabrication restrict their application in flexible electronics, particularly circuit fabrication. Furthermore, while initiation-based chemical vapor deposition (CVD) has shown potential in recent years for preparing organic polymer or composite dielectric materials and for thin-film transistor applications, large-area uniform fabrication remains a significant challenge for traditional CVD methods in their industrial application. Summary of the Invention

[0004] To address the key technical challenges in the field of flexible electronics, this application proposes a composite dielectric material based on polyimide-inorganic oxide, which can be uniformly prepared over a large area.

[0005] According to one aspect of this application, this application provides a composite dielectric film based on polyimide-inorganic oxide, which includes a polyimide layer formed by molecular layer deposition on a substrate and an inorganic oxide layer formed by atomic layer deposition.

[0006] In this application, the polyimide layer formed by molecular layer deposition and the inorganic oxide layer formed by atomic layer deposition have a thickness of nanometer to sub-nanometer level, which makes the composite dielectric film have a stacked structure in the microscopic and preparation process, and uniform properties in the mesoscopic and macroscopic.

[0007] According to a preferred embodiment of this application, the total thickness of the composite dielectric film can be precisely controlled at the nanoscale through supercycling formulation and quantity, thereby achieving a minimum precision of 0.1 nm. According to a more preferred embodiment, the total thickness of the composite dielectric film can be controlled within the range of 0.1 nm to 1000 nm.

[0008] According to a preferred embodiment of this application, the composite dielectric film based on polyimide-inorganic oxide has the following characteristics: density 1.0 g / cm³. -3 ~3.5gcm -3 The preferred density is 1.0 g / cm³. -3 ~2.0gcm -3 Dielectric constant 3~9 (100Hz), resistivity 1×10 3 MΩcm ~ 1×10 9 MΩcm (0.5 MVcm -1 The surface root mean square roughness is 0.1 nm to 3.0 nm. According to a more preferred embodiment of this application, the composite dielectric film based on polyimide-inorganic oxide has the following characteristics: density 1.2 g / cm³. -3 ~1.8gcm -3 Dielectric constant 5~9 (100Hz), resistivity 1×10 7 MΩcm ~ 1×10 9 MΩcm(0.5 MVcm -1 The root mean square roughness of the surface is 0.2 nm ~ 0.5 nm.

[0009] According to a preferred embodiment of this application, in the polyimide-inorganic oxide-based composite dielectric film, the polyimide is a polyimide with at least one diamine selected from ethylenediamine, propylenediamine, butanediamine, pentanediamine, hexanediamine, phenylenediamine, and 4,4'-diaminodiphenyl ether, and at least one dianhydride selected from pyromellitic dianhydride and naphthalenetetracarboxylic dianhydride as precursors.

[0010] According to a more preferred embodiment of this application, when the diamine precursor in the molecular layer deposition process is an aliphatic compound, such as ethylenediamine, propylenediamine, butanediamine, pentanediamine, or hexanediamine, the composite dielectric film based on polyimide-inorganic oxide has the characteristic property of being transparent to visible light.

[0011] According to a preferred embodiment of this application, in the composite dielectric film based on polyimide-inorganic oxide, the inorganic oxide is at least one of aluminum oxide, zirconium oxide, and hafnium oxide.

[0012] According to a preferred embodiment of this application, in the composite dielectric film based on polyimide-inorganic oxide, the substrate is a single-crystal silicon substrate, a thermally oxidized silicon substrate, a glass substrate, a polyethylene terephthalate (PET) substrate, a polyethylene naphthalate substrate, or a polyimide substrate.

[0013] According to a further preferred embodiment of this application, this application provides a polyimide-alumina composite dielectric film comprising a stack of a polyimide layer deposited on a substrate at molecular layers and an alumina layer deposited at atomic layers.

[0014] According to a further preferred embodiment of this application, the polyimide-alumina composite dielectric film includes a substrate, an alumina buffer layer, a stack of molecularly deposited polyimide layer and atomically deposited alumina layer.

[0015] According to another aspect of this application, this application provides a method for preparing the polyimide-inorganic oxide-based composite dielectric film, which includes: polyimide molecular layer deposition and inorganic oxide atomic layer deposition, wherein the molecular layer deposition and atomic layer deposition are performed alternately in the same reactor.

[0016] According to a preferred embodiment of this application, in the method for preparing the composite dielectric film based on polyimide-inorganic oxide, the polyimide molecular layer deposition uses at least one diamine selected from ethylenediamine, propylenediamine, butanediamine, pentanediamine, hexanediamine, phenylenediamine, and 4,4'-diaminodiphenyl ether, and at least one dianhydride selected from pyromellitic dianhydride and naphthalenetetracarboxylic dianhydride as a precursor.

[0017] According to a preferred embodiment of this application, in the method for preparing the composite dielectric film based on polyimide-inorganic oxide, the inorganic oxide is at least one of aluminum oxide, zirconium oxide, and hafnium oxide.

[0018] According to a preferred embodiment of this application, in the method for preparing the composite dielectric film based on polyimide-inorganic oxide, the alumina atomic layer deposition uses at least one metal compound selected from aluminum trichloride, trimethylaluminum, triethylaluminum, dimethylisopropoxyaluminum, methyldiisopropoxyaluminum, triisopropoxyaluminum, diethylaluminum chloride, tridimethylaminoaluminum, and tridiethylaminoaluminum, as well as at least one oxidant selected from water vapor, hydrogen peroxide, ozone, air, oxygen plasma, and air plasma as a precursor.

[0019] According to a preferred embodiment of this application, in the method for preparing the composite dielectric film based on polyimide-inorganic oxide, the zirconium oxide atomic layer deposition uses at least one metal oxide selected from tetramethylethylaminozirconium, tetradimethylaminozirconium, tetradiethylaminozirconium, zirconium tetrachloride, and tetratert-butoxyzirconium, as well as at least one oxidant selected from water vapor, hydrogen peroxide, ozone, air, oxygen plasma, and air plasma as a precursor.

[0020] According to a preferred embodiment of this application, in the method for preparing the composite dielectric film based on polyimide-inorganic oxide, the hafnium oxide atomic layer deposition uses at least one of tetramethylethylaminohafnium, tetradimethylaminohafnium, tetradiethylaminohafnium, hafnium tetrachloride, tetratert-butoxyhafnium, cyclopentadiene tridimethylaminohafnium, and cyclopentadiene dimethylhafnium, as well as at least one of water vapor, hydrogen peroxide, ozone, air, oxygen plasma, and air plasma as a precursor.

[0021] According to a further preferred embodiment of this application, in the method for preparing the composite dielectric film based on polyimide-inorganic oxide, each reaction precursor is allowed to evaporate naturally at room temperature or is evaporated by heating. More preferably, ethylenediamine, trimethylaluminum, and water vapor reagent sources are allowed to evaporate naturally at room temperature, while pyromellitic dianhydride is placed in a hot air chamber and heated to evaporate at its sublimation temperature.

[0022] According to a further preferred embodiment of this application, in the method for preparing the composite dielectric film based on polyimide-inorganic oxide, heating devices such as heating belts, heating jackets, and hot air boxes are used as precursors for heating and volatilization.

[0023] According to a preferred embodiment of this application, in the method for preparing the composite dielectric film based on polyimide-inorganic oxide, purified nitrogen or purified argon is used as the purging and precursor transport auxiliary gas.

[0024] According to a preferred embodiment of this application, in the method for preparing the composite dielectric film based on polyimide-inorganic oxide, the pressure of the purging gas is 0.05 Torr ~ 50 Torr, and the purging time is 1 ~ 1000 s, so as to ensure the effective diffusion of the precursor and also to achieve effective purging.

[0025] According to a preferred embodiment of this application, in the method for preparing the composite dielectric film based on polyimide-inorganic oxide, the reaction chamber temperature can be set above the sublimation temperature of the anhydride precursor. Preferably, the reaction chamber temperature is set to 150°C ~ 220°C, more preferably 160°C ~ 200°C, and even more preferably 165°C ~ 180°C.

[0026] According to a preferred embodiment of this application, in the method for preparing the composite dielectric film based on polyimide-inorganic oxide, the polyimide molecular layer deposition process adopts either a "valve-off" or "flow-through" mode. The "valve-off" mode is more likely to achieve the required precursor exposure, while the "flow-through" mode has an advantage in terms of process time. The "flow-through" mode is preferred in this application. The exposure of the dianhydride and diamine precursors only needs to reach the saturation level of the polyimide molecular layer deposition. Preferably, the exposure of the dianhydride and diamine precursors is 0.001~10 Torr·s, more preferably 0.01~0.5 Torr·s, and even more preferably 0.03~0.08 Torr·s. This helps ensure that the surface reaction reaches saturation and saves on the amount of precursor used. In the embodiments, due to equipment limitations, a longer purging time is beneficial for improving the coating uniformity; however, a longer purging time is not necessarily better. In systems with higher purging efficiency, a shorter purging time can achieve the same coating uniformity and save more time.

[0027] According to a preferred embodiment of this application, in the method for preparing the composite dielectric film based on polyimide-inorganic oxide, the alumina atomic layer deposition process adopts either a "flow-through" or "valve-off" mode. The "valve-off" mode is more likely to achieve the required precursor exposure, while the "flow-through" mode has an advantage in terms of process time. In this application, the "flow-through" mode is preferred. The precursor exposure of the oxide atomic layer deposition is slightly higher than the saturation exposure required for the atomic layer deposition of oxides on a flat surface. Preferably, the exposure of the metal compound and oxidant precursor in the oxide atomic layer deposition is 0.001~10 Torr·s, more preferably, the exposure of the metal compound and oxidant precursor in the metal oxide atomic layer deposition is 0.01~1 Torr·s, and even more preferably, the exposure of the metal compound and oxidant precursor is 0.01~0.5 Torr·s and 0.02~1 Torr·s, respectively.

[0028] More preferably, the exposure amounts of aluminum compounds and oxidant precursors in the alumina atomic layer deposition are 0.01~0.5 Torr·s and 0.02~1 Torr·s, respectively. More preferably, the exposure amounts of trimethylaluminum and water vapor precursors are 0.01~0.1 Torr·s and 0.02~0.2 Torr·s, respectively.

[0029] According to a preferred embodiment of this application, in the method for preparing a composite dielectric film based on polyimide-inorganic oxide, the molecular layer deposition and atomic layer deposition processes for depositing the composite film are performed alternately in a supercycle manner. Each supercycle consists of 1 to 30 consecutive polyimide molecular layer deposition cycles followed by 1 to 20 atomic layer deposition cycles. More preferably, each supercycle consists of 1 to 10 consecutive polyimide molecular layer deposition cycles followed by 1 to 3 consecutive atomic layer deposition cycles. During the 1 to 10 cycles of polyimide molecular layer deposition, the film growth rate is relatively fast; at most 3 consecutive atomic layer depositions can achieve efficient alumina doping and prevent the formation of continuous alumina films, ensuring the overall flexibility of the composite film. Further preferably, each supercycle consists of 3 consecutive polyimide molecular layer deposition cycles followed by 3 atomic layer deposition cycles.

[0030] The polyimide-inorganic oxide-based composite dielectric film of this application is suitable for use as an insulating gate dielectric layer in flexible thin-film transistors, and is particularly suitable for all-carbon nanotube thin-film transistors. Similarly, it is also suitable for other flexible electronic circuits, particularly such as inverters, ring oscillators, logic gates, or amplifiers.

[0031] According to another aspect of this application, this application also provides a flexible thin-film transistor comprising the above-described composite dielectric film based on polyimide-inorganic oxide as an insulating gate dielectric layer.

[0032] According to a preferred embodiment of this application, the flexible thin-film transistor is an all-carbon nanotube thin-film transistor.

[0033] According to other aspects of this application, this application also provides flexible electronic circuits comprising the aforementioned flexible thin-film transistors, particularly all-carbon nanotube thin-film transistors. The all-carbon nanotube thin-film transistors have a density of -0.67 ± 0.14. V's small threshold voltage, 10 4.54±0.26 High on / off ratio, 0.26±0.05 V dec -1 Low subthreshold swing, and below 20 fA μm -2 It exhibits low leakage current density; in addition, the device demonstrates excellent mechanical flexibility, with no significant change in transistor characteristics after 2000 bends at a bending level of 3.4 mm radius of curvature.

[0034] In the composite process based on molecular layer deposition (MLD) and atomic layer deposition (ALD) techniques described in this application, MLD and ALD are performed alternately to achieve the growth of sub-nanometer-scale polyimide and oxide "layers," respectively, thereby realizing the growth of a homogeneous phase composite dielectric material at the nanoscale. This hybrid growth strategy enables the homogeneous phase composite material to possess both excellent mechanical flexibility and dielectric properties. Using this composite dielectric material, intrinsically flexible high-performance all-carbon nanotube thin-film transistors can be fabricated and further integrated and constructed into digital circuit units including inverters, ring oscillators, and logic gates, demonstrating strong application potential.

[0035] According to this application, a composite dielectric material based on polyimide and alumina is first prepared using a combination of molecular layer deposition (MLD) and atomic layer deposition (ALD). In the composite film, the polyimide polymer component provides intrinsic flexibility, while the alumina component significantly optimizes the film quality and electrical properties. The MLD-ALD combination process used in the material preparation is a vapor-phase thin film deposition process with large-area uniformity and excellent conformal properties, thus possessing unique advantages in large-area thin film preparation, thickness control, and process integration. In the composite process, MLD and ALD processes are performed alternately, achieving the alternating deposition of sub-nanometer-level organic and inorganic "layers," thereby obtaining a homogeneous composite dielectric film.

[0036] This composite dielectric film was subsequently integrated into the fabrication process of an all-carbon nanotube thin-film transistor, achieving the fabrication of an intrinsically flexible thin-film transistor device. This thin-film transistor exhibited excellent device performance, and the fabrication process also demonstrated top-tier large-area uniformity and device yield. Statistical analysis of the device characteristic parameters showed that the composite dielectric-all-carbon nanotube thin-film transistor possessed a performance characteristic of -0.67 ± 0.14. V's small threshold voltage, 10 4.54±0.26 High on / off ratio, 0.26±0.05 V dec -1 Low subthreshold swing, and below 20 fA μm -2The device exhibits low leakage current density and excellent mechanical flexibility, maintaining consistent transistor characteristics after 2000 bends at a bending radius of 3.4 mm. Building upon the composite dielectric-all-carbon nanotube thin-film transistor, various fundamental digital circuit units with superior characteristics, including inverters, ring oscillators, and logic gates, were further demonstrated. The inverter circuit achieved a record-breaking gain of 342.5 and maintained consistent output characteristics even after being subjected to a 3.1% tensile strain; its drive voltage requirement was as low as 50 mV, demonstrating strong application potential in low-voltage, low-power circuits. The inverter's excellent performance consistency allows for further integration, enabling the fabrication of larger-scale ring oscillators. Beyond digital circuit applications, this high-gain, low-voltage driven inverter also demonstrates excellent performance in analog signal amplification, amplifying millivolt-level input signals by 100 times. In summary, molecular layer deposition / atomic layer deposition composite dielectric deposition technology and all-carbon nanotube flexible circuit technology have broad application prospects and potential in the coming "Internet of Things" era, especially in real-time health monitoring and wearable devices. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the deposition process of the composite dielectric thin film in Example 1. Figure 1 A is a schematic diagram of the deposition process of the composite dielectric film; Figure 1 B is the curve showing the change in thin film deposition rate with different ethylenediamine precursor exposure levels; Figure 1 C is the curve showing the change in thin film deposition rate with the exposure amount of pyromellitic dianhydride precursor.

[0038] Figure 2 These are the material property characterization results of the molecular layer deposited polyimide film and composite film in Example 1. Among them, Figure 2 A is the XPS full element scan spectrum of polyimide and composite film; Figure 2 B represents the RBS experimental data spectral lines and fitting curves of the composite thin film; Figure 2 C is polyimide film and Figure 2 D is the AFM scan image of the composite thin film; Figure 2 E is the FTIR transmission spectrum of polyimide and composite film; Figure 2 F is the ultraviolet-visible transmission spectrum of polyimide and composite film; Figure 2 G is the current-electric field scan curve of a MIM capacitor based on polyimide and a composite thin film insulating gate dielectric layer; Figure 2 H is the capacitance-frequency response curve of a MIM capacitor based on a composite thin-film insulated gate dielectric layer.

[0039] Figure 3These are the test results for intrinsically flexible composite dielectric-all-carbon nanotube thin-film transistors. Among them... Figure 3 A is a schematic diagram of the cross-sectional structure of an intrinsically flexible composite dielectric-all-carbon nanotube thin-film transistor; Figure 3 B is the SEM image of the trench region; Figure 3 C is a schematic diagram of the uniform coating of the composite film on the channel region; Figure 3 D is the SEM image of the cross-section; Figure 3 E is a photograph of an intrinsically flexible composite dielectric-all-carbon nanotube thin-film transistor sample attached to a human body and rolled up. Figure 3 F is the transfer pattern of an intrinsically flexible composite dielectric-all-carbon nanotube thin-film transistor; Figure 3 G is the output characteristic curve; Figure 3 H represents the output characteristic curves of 30 transistor devices, with the corresponding gate leakage current curves displayed in the embedded panel. Figure 3 I is the transfer characteristic curve of a transistor device after being bent a different number of times; Figure 3 J is the transfer characteristic curve measured when the transistor device is bent at different radii of curvature; Figure 3 K demonstrates the process of testing samples under bending conditions.

[0040] Figure 4 These are the test results of an inverter based on an intrinsically flexible composite dielectric-all-carbon nanotube thin-film transistor. Figure 4 A is a schematic diagram of an integrated circuit sample; Figure 4 B is a photograph of the integrated circuit sample; Figure 4 C is the voltage transfer curve (V) of 20 inverters. dd =5V), the embedded panel displays the circuit diagram and photomicrograph of the inverter; Figure 4 D is the hysteresis curve of the inverter; Figure 4 E is the voltage transfer curve of the inverter after being bent by different radii of curvature; Figure 4 F is the statistical result of the gain values ​​of 70 pseudo-complementary transistor inverters (Vdd=1V), and the embedded panel shows a photomicrograph of the inverter; Figure 4 G is the voltage transfer curve of the inverter under different driving voltages; Figure 4 H is the gain value of the inverter under different driving voltages; Figure 4 The embedded panel in G shows the circuit diagram of the inverter; Figure 4 I represents the gain and tensile strain that can be withstood by the flexible inverter as reported in the comparison report; Figure 4 J represents the input and output waveforms for testing the dynamic characteristics of the inverter; Figure 4 K is the dynamic power consumption of the inverter under different driving voltages; Figure 4 L represents the driving voltage and peak power consumption of the flexible inverter as reported in the literature.

[0041] Figure 5 These are the test results of a ring oscillator and logic gate based on an intrinsically flexible composite dielectric-all-carbon nanotube thin-film transistor. Figure 5 A is a photomicrograph of the 3rd and 7th stage ring oscillators. Figure 5 B is the output waveform of the 7-stage ring oscillator under different driving voltages. Figure 5 C is the 1.75kHz oscillation waveform output by the 3-stage ring oscillator. Figure 5 D is the input signal waveform diagram used to test the function of the logic gate circuit and the truth table of the logic gate circuit under test. Figure 5 E- Figure 5 H is based on an intrinsically flexible composite dielectric-all-carbon nanotube thin-film transistor. Figure 5 E-NOT gate; Figure 5 F-OR NOT gate; Figure 5 G XOR gate; Figure 5 Output waveform, circuit diagram, and photomicrograph of the H-AND gate.

[0042] Figure 6 This is a schematic diagram of an amplifier based on an intrinsically flexible composite dielectric-all-carbon nanotube thin-film transistor and its potential electrocardiogram monitoring function. Figure 6 A is a schematic diagram of using a flexible amplifier to amplify electrocardiogram signals. Figure 6 B is an analog signal amplified up to 100 times by an amplifier. Figure 6 C represents the amplification effect of analog signals at different frequencies.

[0043] Figure 7 These are the growth characteristic curves of the composite dielectric film.

[0044] Figure 8 These are the Rutherford backscattering test results for the composite dielectric thin film. Figure 8 A is the Rutherford backscattering spectrum of the composite dielectric thin film. Figure 8 B represents the measured Al:N atomic ratio and film mass density in the composite dielectric film.

[0045] Figure 9 These are the test results of the electrical properties of the composite dielectric film. Figure 9 A is the voltage-current curve of the composite dielectric film. Figure 9 B is the relative permittivity / dielectric loss-frequency response of the composite dielectric film.

[0046] Figure 10 This is a schematic diagram of the polyimide molecular layer deposition process.

[0047] Figure 11 yes Figure 11 A. Polyimide Figure 11 The graph shows the linear increase in deposition thickness of the B composite film with the number of deposition cycles / supercycles.

[0048] Figure 12 It is a high-resolution XPS image. Figure 12 A- Figure 12 D-polyimide; Figure 12 E- Figure 12 H-composite film; Figure 12 I. Atomic proportions in thin films extracted from high-resolution XPS images.

[0049] Figure 13 This is the sample model used for fitting RBS spectral data. The alumina buffer layer, prepared by 20 cycles of alumina atomic layer deposition, is simulated by a 2nm Al2O3 layer with a mass density of 3.2g cm⁻³. The atomic ratio and total atomic surface density in the composite film layer are the fitting results. The fitting process considers signal stacking effects.

[0050] Figure 14 yes Figure 14 A polyimide and Figure 14 UV-Vis absorption spectrum of B composite film.

[0051] Figure 15 It is a transistor device. Figure 15 A bias stability and Figure 15 B. Temperature stability.

[0052] Figure 16 This is the inverter fabrication process. Steps 1-6 are the individual steps in the process.

[0053] Figure 17 yes Figure 17 A unipolar diode load inverter Figure 17 B-diode-loaded pseudo-complementary transistor inverter and Figure 17 Circuit diagram of a common-gate source pseudo-complementary transistor inverter. Figure 17 The voltage transfer characteristic curves of three unipolar inverters and Figure 17 E gain value.

[0054] Figure 18 This is the voltage transfer curve of the inverter and its mirror image. The area within the box represents its noise margin at the Vdd / 2 level. Detailed Implementation

[0055] The technical solution of this application will be described in more detail below through specific embodiments and in conjunction with the accompanying drawings.

[0056] Example 1

[0057] Experimental methods

[0058] Preparation and Characterization of Polyimide and Composite Dielectric Films: Both polyimide and composite films were prepared using a self-built tubular atomic layer deposition / molecular layer deposition system. The polyimide molecular layer deposition process used ethylenediamine (EDA) and pyromellitic dianhydride (PMDA) as precursors; the alumina atomic layer deposition process used trimethylaluminum (TMA) and water vapor as precursors. Polyimide films were prepared separately using this molecular layer deposition process, while composite films were prepared by alternating molecular layer deposition and atomic layer deposition in the same reactor. During these processes, the ethylenediamine, trimethylaluminum, and water vapor reagents were volatilized at room temperature, while the pyromellitic dianhydride was placed in a hot air chamber and sublimated at 163°C. Purified nitrogen was used as the purge and precursor transport auxiliary gas in the process. The purge gas pressure was 1 Torr. The reaction chamber temperature was set to 165°C, slightly higher than the sublimation temperature of pyromellitic dianhydride, to prevent condensation of pyromellitic dianhydride in the chamber. The polyimide molecular layer deposition process employed a "valve-off" mode, with exposures of 0.033 and 0.063 Torr·s for the pyromellitic dianhydride and ethylenediamine precursors, respectively, and a 100-s purge time. The alumina atomic layer deposition process employed a "flow-through" mode, with exposures of 0.014 and 0.064 Torr·s for the trimethylaluminum and water vapor precursors, respectively. The molecular layer deposition / atomic layer deposition composite process for depositing the composite film was constructed using a "supercycle" approach. Each supercycle consisted of three consecutive polyimide molecular layer deposition cycles followed by three atomic layer deposition cycles, for a total of 23 supercycles.

[0059] Thin film samples were prepared on thermally oxidized silicon substrates, highly doped single-crystal silicon substrates, glassy carbon sheets, potassium bromide wafers, and glass sheets, respectively. To ensure that the thin film samples deposited on different substrates have the same initial growth conditions and interface characteristics, 20 cycles of alumina atomic layer deposition were performed as a buffer layer before starting polyimide or composite thin film deposition.

[0060] The film thickness was measured using an ellipsometry (M-2000, JA Woollam), and the obtained spectra were fitted using a Cauchy model to extract the thickness values. X-ray photoelectron spectroscopy (Escalab 250Xi XPS system, ThermoScientific) was used to characterize the composition of the polyimide and composite film, with monochromatic Al Kα X-rays as the incident light source. Furthermore, the composition of the composite film was further analyzed using Rutherford backscattering (RBS) characterization, with 2 MeV He particles as the incident particle. +An atomic force microscope (Bruker, MultiMode 8-HR) was used to characterize the surface morphology of the thin films in contact mode, with a measurement range of 500 nm. Infrared spectral characteristics of the polyimide and composite films were acquired using a Fourier transform infrared spectrometer (PerkinElmer Frontier spectrometer); UV-Vis absorption spectra were measured using a UV-Vis spectrophotometer (Shimadzu UV-2450).

[0061] Fabrication and characterization of capacitors, transistors, and circuits: PET-ITO substrates were used to fabricate metal-insulated gate dielectric-metal (MIM) capacitors; a 20 nm ITO thin film pre-fabricated on the substrate served as the bottom electrode of the device; the insulating gate dielectric layer was fabricated using the following process: 20 cycles of alumina atomic layer deposition (forming an approximately 2 nm buffer layer), 200 cycles of polyimide molecular layer deposition (forming an approximately 30 nm polyimide thin film) or 23 super-cycle composite deposition process (forming an approximately 35 nm composite thin film); 30 cycles of alumina atomic layer deposition (forming an approximately 3 nm buffer layer); finally, 110 nm copper was fabricated as the top electrode by evaporation and patterning using a mask.

[0062] PEN substrates were used to fabricate thin-film transistors and circuits. Before device fabrication, the PEN substrates were first pre-baked at 180°C for 15 minutes; then subjected to 5 minutes of oxygen plasma treatment at a plasma power of 100W; finally, they were ultrasonically cleaned sequentially with acetone, ethanol, and deionized water, and dried with nitrogen. In the fabrication of top-gate bottom-contact thin-film transistors, single-walled carbon nanotube networks (SCNT networks) were first used to form channel patterns on the substrate via spin coating and standard photolithography; multi-walled carbon nanotube networks (MCNT networks) were then used to form source and drain electrode patterns via spin coating and standard photolithography; the carbon nanotubes were etched using reactive ion etching with oxygen plasma as the etching medium. The single-walled carbon nanotube suspension precursor was prepared by ultrasonically dispersing 1 mg of single-walled carbon nanotubes and 1 mg of poly[(m-phenylenevinylene)-co-(2,5-dioctoxy-p-phenylenevinylene)], PmPV) dispersant in 50 mL of 1,2-dichloroethane for 6 hours. The electrode precursor was a 2.0% (w / w) water-based multi-walled carbon nanotube suspension. After completing the channel and electrode patterning, the insulating gate dielectric layer was prepared by a composite process with 23 supercycles, resulting in a film thickness of 35 nm. Similar to the preparation of MIM capacitors, 20-cycle and 30-cycle ALD alumina buffer layers were prepared before and after the composite process, respectively. Depending on the type of circuit, the dielectric layer pattern and contact holes were prepared using a standard photolithography process. The dielectric layer was etched using a wet etching process with a 45% (v / v) concentrated phosphoric acid solution at 70°C for 2 minutes. Finally, the multi-walled carbon nanotube gate pattern was fabricated and patterned using the same process as the source and drain electrodes. The fabrication process is as follows: Figure 16 As shown.

[0063] Electrical characterization of MIM capacitors, thin-film transistors, and circuits was performed using a probe station and a semiconductor performance tester (B1500A, Keysight). In dynamic testing of digital circuits, the input signal was generated jointly by a function generator and a pulse generation unit (16440A, Agilent) (AFG3101C, Tektronix). Specifically, the frequency response of the MIM capacitors was precisely measured using an LCR source meter (E4980A, Keysight).

[0064] Results and Analysis:

[0065] Polyimide and composite film deposition and characterization: Figure 1 This is a schematic diagram of the composite dielectric thin film deposition process. Figure 1 A is a schematic diagram of the molecular layer deposition / atomic layer deposition composite process; Figure 1 B is the curve showing the change in thin film deposition rate with different ethylenediamine precursor exposure levels; Figure 1 C is the curve showing the change in thin film deposition rate with the exposure amount of pyromellitic dianhydride precursor.

[0066] like Figure 1 As shown, the composite polyimide-alumina film was prepared via a molecular layer deposition / atomic layer deposition composite process at a deposition temperature of 165°C. In this composite process, polyimide molecular layer deposition and alumina atomic layer deposition processes were performed alternately to achieve the alternating growth of sub-nanometer-scale polyimide and alumina "layers". Alumina atomic layer deposition has been widely studied and applied, while the polyimide molecular layer deposition process utilizes the self-limiting imidization reaction between ethylenediamine and pyromellitic dianhydride (PDM). Figure 1 A). In the imidization reaction, the amino group of ethylenediamine first undergoes an addition reaction with the acid anhydride bond to form an amide acid intermediate, and then further undergoes imidization, removing a water molecule to form a five-membered ring imide structure, such as... Figure 10 As shown. The self-limiting nature of the polyimide molecular layer deposition process was first verified by its saturation curve. For example... Figure 1 As shown in B and 1C, with the increase of precursor exposure in the molecular layer deposition cycle, the polyimide deposition rate initially increases positively, and finally exhibits saturation characteristics; after the precursor exposure of ethylenediamine and pyromellitic dianhydride exceeds 4 and 8 pulses respectively, the growth rate of the molecular layer deposited polyimide film reaches a saturation value of 1.5 Å per cycle. The molecular layer deposition / atomic layer deposition composite process for composite dielectric films is constructed using a "supercycle" mode; in each composite process supercycle, three consecutive polyimide molecular layer deposition cycles are first performed, followed by three alumina atomic layer deposition cycles, and so on. Figure 1 As shown in B and 1C, the composite process also retains good self-limiting properties. The composite dielectric film deposited by the composite process has a saturation growth rate of 16.0 Å per supercycle, and the required exposure amounts of ethylenediamine and pyromellitic dianhydride precursors to reach saturation are 2 pulses and 8 pulses, respectively (for pyromellitic dianhydride, each pulse corresponds to an exposure of 0.00633 Torr s; for ethylenediamine, each pulse corresponds to an exposure of 0.0167 Torr s). Figure 11 As shown, the linear growth characteristics of both the polyimide molecular layer deposition process and the composite process were also verified.

[0067] Subsequently, the material properties of molecular layer deposited polyimide and composite films were characterized and compared.

[0068] Figure 2 These are the material property characterization results for molecular layer deposited polyimide films and composite films. Among them, Figure 2A is the XPS full element scan spectrum of polyimide and composite films. Figure 2 B represents the RBS experimental data spectral lines and fitted curves of the composite thin film. Figure 2 C is polyimide film and Figure 2 D is the AFM scan image of the composite thin film. Figure 2 E is the FTIR transmission spectrum of polyimide and composite film. Figure 2 F is the ultraviolet-visible transmission spectrum of polyimide and composite films. Figure 2 G is the current-electric field scan curve of a MIM capacitor based on polyimide and a composite thin-film insulating gate dielectric layer. Figure 2 H is the capacitance-frequency response curve of a MIM capacitor based on a composite thin-film insulated gate dielectric layer.

[0069] Figure 2 A shows the X-ray photoelectron spectroscopy (XPS) of molecular layer deposited polyimide films and composite films. The polyimide film's spectrum shows spectral lines for carbon, nitrogen, and oxygen, and the ratio of carbon, nitrogen, and oxygen in the film can be calculated to be approximately C:N:O by integrating the spectral line areas. = 12.7:2.2:4.0, compared with the ideal ethylenediamine-pyromellitic dianhydride type polyimide polymer ([C 12 N2O4H6] n The elemental proportions in the samples are very close. The high-resolution XPS spectrum of the sample is as follows: Figure 12 As shown, a weak aluminum line was observed in the energy dispersive spectroscopy (EDS) spectrum of the polyimide film. This line is contributed by the alumina buffer layer at the bottom of the polyimide film, possibly indicating a "pinhole" structure in the molecularly deposited polyimide film. In addition to the carbon, nitrogen, and oxygen lines, a significant aluminum line was also observed in the EDS spectrum of the composite film, indicating the successful integration of the alumina component with the polyimide matrix. The elemental composition of the composite film was further analyzed using Rutherford backscattering (RBS) spectroscopy. Figure 2 B shows the RBS experimental data spectra and fitting curves of the composite thin film samples prepared on the glassy carbon substrate. The fitting yielded a nitrogen, oxygen, and aluminum ratio of N:O:Al in the thin film. = The ratio of 2.0:5.9:1.3 is close to the N:O ratio in polyimide. = 2:4 and the Al:O content in the alumina composition = The ideal scenario is 2:3 (see details). Figure 13Since the glassy carbon substrate signal masks the contribution of carbon in the sample, and RBS technology cannot measure the hydrogen content, the mass density of the sample can be calculated by assuming that the organic components in the film have an ideal stoichiometric ratio of ethylenediamine-pyromellitic dianhydride-type polyimide polymer. The calculated result is 1.65. g cm −3 Slightly higher than commercially available polyimide film products (1.42). g cm −3 This is due to the composite of inorganic components of alumina with higher mass density. Figure 2 Images C and D show atomic force microscopy (AFM) scans of the polyimide film and the composite film. The polyimide film has a relatively rough surface morphology (root mean square roughness of 2.64 nm) and exhibits pinhole structures; while the composite film has a much smoother surface (root mean square roughness of only 0.29 nm) and no pinhole structures. A smooth surface morphology is a prerequisite for a thin film to be suitable as an insulating gate dielectric layer in a thin-film transistor.

[0070] Fourier transform infrared spectroscopy (FTIR) has been used to characterize and analyze chemical bonding information in molecularly deposited polyimide and composite films. For example... Figure 2 As shown in the upper half of E, the infrared spectrum of the polyimide film contains a pair of structures located at 1778 and 1714 cm⁻¹, respectively. −1 absorption peak and a peak located at 1378 cm −1 The three peaks are derived from the absorption of symmetric and antisymmetric stretching vibrations of the imide carbonyl group, and the stretching vibration absorption of the C−N−C structure, respectively. It is noteworthy that the polyimide sample exhibits absorption peaks between 1700 and 1500 nm. cm −1 The absence of significant absorption in the wavenumber range indicates a high degree of imidization in the film. This is because the intermediate amide acid in the imidization reaction contributes to the absorption in this wavenumber range, including the stretching vibration of the carboxylate carbonyl group (1680). cm −1 ), amide bond carbonyl stretching vibration (1650) cm −1 Absorption, including [missing information]. The high degree of imidization in the film gives it a significant advantage in dielectric material applications, as it helps improve the material's insulation properties and long-term stability in air. To achieve a high degree of imidization, the traditional solution-based preparation process of polyimide involves high temperature (350°C). The polymerization process (at °C) is a necessary procedure. In contrast, the highest deposition temperature for polyimide molecular layer deposition is 165°C. This allows the polyimide molecular layer deposition process to be compatible with the process temperatures of common flexible electronic circuit substrates while ensuring a high degree of imide content in the polymer composition, demonstrating the broad application potential of this process. Figure 2 The lower half of E shows the infrared spectrum of the composite film. Compared to the polyimide sample, two additional high-intensity absorption peaks appear in the infrared spectrum of the composite film, located between 1000 and 500 nm. cm −1 and 1700-1500 cm −1 Within the wavenumber range: 1000–500 cm −1 The absorption band within the range is contributed by the vibrational absorption of the alumina component, while the 1700–1500 range... cm −1 The absorption components within this range are consistent with the carbonyl stretching vibration characteristics of carboxylate ions and carboxylate compounds. These structures likely originate at the interface between the alumina and polyimide components in the composite film. Due to the varying coordination interaction strengths between aluminum and these carbonyl components, the absorption peaks are broadened to some extent, resulting in the observed absorption band morphology. This infrared characteristic reveals, to a certain extent, the microstructure information of the phase interface in the composite film.

[0071] Ultraviolet-visible absorption spectroscopy has been further used to study the material properties of molecularly layered deposited polyimide films and composite films. For example... Figure 2 As shown in Figure F, both thin films exhibit high transmittance (>98%) in the visible light range (400–800 nm) and possess the same main absorption peak at approximately 240 nm. This is determined by the initial absorption wavelength (λ) in the spectrum. onset The determined optical band gaps for the polyimide and composite films are 4.52 and 4.27 eV, respectively. Figure 14 This value is significantly larger than the optical band gap of commercially available pyromellitic dianhydride-p-aminodiphenyl ether polyimide. This is because the use of non-aromatic diamine monomers in the molecular layer deposition process weakens the π-π stacking in the film. Therefore, molecular layer deposited polyimide and composite films are more suitable for application in transparent electronic circuits. Furthermore, it is noteworthy that the UV-Vis absorption spectrum of the composite film sample does not exhibit the weak absorption at 320 nm seen in the polyimide film sample. This absorption characteristic originates from electron transfer between intermolecular conjugated systems; therefore, the suppression of this spectral feature by the composite process may indicate that the composite film has better insulating properties.

[0072] The dielectric properties of molecularly layered polyimide and composite films were verified using metal-insulating gate dielectric-metal (MIM) capacitors. The MIM devices were fabricated on PET-ITO substrates, with ITO as the bottom electrode, polyimide or composite films as the insulating gate dielectric layer, and copper metal prepared by vacuum evaporation as the top electrode. Figure 2 As shown in G, the insulation performance of polyimide MIM devices is not ideal, 0.1 MV cm −1 Leakage current up to 1×10 −5 A cm −2 And in 0.5 MV cm −1 Under such an electric field strength, it breaks down rapidly. In contrast, composite films possess considerable insulating properties, achieving a dielectric strength of 1 MV. cm −1 The leakage current remains well maintained at 1.1 under the electric field strength. × 10 −7 A cm −2 Furthermore, the MIM device fabricated on the flexible substrate can withstand bending at a radius of curvature of 5 mm without a significant increase in leakage current. The relative permittivity of the composite film is 5.8 (1 kHz), and at C... i - No significant change was observed within the frequency range tested. Due to the composite of alumina components with high dielectric constant, this relative dielectric constant is higher than that of commercially available Kapton polyimide film products (3.9).

[0073] Intrinsic flexible composite dielectric-all-carbon nanotube thin-film transistor: Figure 3 These are the test results for intrinsically flexible composite dielectric-all-carbon nanotube thin-film transistors. Figure 3 A is a schematic diagram of the cross-sectional structure of an intrinsically flexible composite dielectric-all-carbon nanotube thin-film transistor. Figure 3 B is the SEM image of the channel region. Figure 3 C is a schematic diagram of the uniform coating of the channel region by the composite film. Figure 3 D is the SEM image of the cross-section. Figure 3 E is a photograph of an intrinsically flexible composite dielectric-all-carbon nanotube thin-film transistor sample attached to a human body and then rolled up. Figure 3 F is the transfer pattern of an intrinsically flexible composite dielectric-all-carbon nanotube thin-film transistor. Figure 3 G is the output characteristic curve. Figure 3 H represents the output characteristic curve of the 30-transistor device; the embedded panel displays the corresponding gate leakage current curve. Figure 3 I represents the transfer characteristic curves of a transistor device after being bent a certain number of times. Figure 3J is the transfer characteristic curve measured when the transistor device is bent at different radii of curvature.

[0074] The composite dielectric film prepared by the molecular layer deposition / atomic layer deposition composite process was then integrated into the fabrication process of the all-carbon nanotube thin film transistor, realizing the fabrication of the intrinsically flexible composite dielectric-all-carbon nanotube thin film transistor. Figure 3 A shows a schematic diagram of the vertical structure of the thin-film transistor; Figure 3 B is a SEM image of the device, magnified to show the contact situation in the channel region. Figure 3 C and D respectively illustrate the concept of coating carbon nanotubes with composite films, and the interface morphology characteristics of a single-layer, single-walled carbon nanotube network before and after being coated with a composite dielectric film using a composite process. It can be observed that the composite dielectric film uniformly covers the carbon nanotube network, demonstrating the superiority of dielectric layer fabrication processes based on molecular layer deposition / atomic layer deposition for film deposition on complex surfaces. Notably, all components in the device are intrinsically flexible materials; therefore, the fabricated device array also possesses intrinsic flexibility. Figure 3 E shows a photograph of a device sample attached to a human body and bent, demonstrating the device's excellent mechanical flexibility.

[0075] The electrical properties of intrinsically flexible composite dielectric-all-carbon nanotube thin-film transistors are as follows: Figure 3 The transfer characteristic curves and output characteristic curves in F and G are shown. Operating voltage (V) ranges from -5 to 3V. g Within the range, the device is near the threshold voltage of −0.6V (V TH This can achieve an on / off ratio (I) on / I off Up to 3.62 × 10 4 (I on = 81.3nA, I off Fast switching (2.24pA) with a low subthreshold swing of 0.17V. dec −1 Horizontal; simultaneously, the gate leakage current of the device (|I g The voltage consistently remains below 10 pA, demonstrating the excellent dielectric properties of the composite dielectric film. The low threshold voltage and subthreshold swing are crucial for achieving low-voltage operation of the transistor device, showcasing another advantage of the composite dielectric film with its high dielectric constant. Furthermore, the peak transconductance of this transistor device reaches as high as 2 nS. μm −1 This demonstrates that carbon nanotube devices possess the considerable current-driving performance required for analog circuit applications. In the output characteristic curves ( Figure 3G), distinct linear and saturation region characteristics were observed under both low and high drive voltage conditions; the current-voltage linearity near 0V drive indicates good contact characteristics between the electrode and the channel. Furthermore, the device's excellent temperature and bias stability were experimentally verified. Figure 15 As shown, at a gate bias of 1000 seconds (V g Under bias conditions, both the on-state and off-state currents remained nearly constant, demonstrating excellent bias stability. Furthermore, as the device temperature varied from 20°C to 180°C, neither the on-state nor off-state currents changed significantly, exhibiting excellent temperature stability. These stability tests demonstrate that the composite dielectric-all-carbon nanotube thin-film transistor device exhibits excellent performance across a wide range of applications and environments.

[0076] The broad consistency of device fabrication processes is crucial for subsequent integrated circuit fabrication. Therefore, the consistency of the composite dielectric-all-carbon nanotube thin-film transistor fabrication process was subsequently verified by measuring a large number of device characteristics. Figure 3 H shows the transfer characteristic curves of 30 randomly selected transistor devices on the same sample. The transfer characteristic curves of different devices overlap well within a small range, demonstrating the consistency of the fabrication process on a large area scale. Statistical analysis of the output characteristic parameters of these devices shows that the threshold voltage of this batch of devices is −0.67±0.14 V, and they possess 10 4.54±0.26 It exhibits a high on / off ratio and a low subthreshold swing of 0.26 ± 0.05 V dec−1; furthermore, the gate drain current density at different locations is below 20 fA μm. −2 This particularly demonstrates the wide-ranging uniformity of the composite dielectric thin film fabrication process. The standard deviations of these device parameters are all within 20% of the mean, which is better than previously reported all-carbon nanotube thin-film transistors.

[0077] To further investigate the mechanical flexibility of the device, the sample was subjected to 2000 bends at a bending radius of 3.4 mm. Figure 3 As shown in Figure I, the output characteristic curve of the device did not change significantly after bending, and all characteristic parameters were well preserved. The relative changes in subthreshold swing, on / off ratio, and threshold voltage were 10.9%, 7.2%, and 7.8%, respectively. More importantly, the leakage current of the device did not change significantly, indicating that the intrinsic flexibility of the composite dielectric film allows it to fully withstand the mechanical bending under experimental conditions. The device characteristics under bending conditions were also studied, such as... Figure 3As shown in J and K, the output characteristic curves of the device are basically consistent under bending conditions with radii of curvature of 8.7, 5.5, and 4.5 mm. Furthermore, under the bending condition with a curvature radius of 4.5 mm, the subthreshold swing, on / off ratio, and threshold voltage of the device differ from those under the flat condition by only 4.9%, 12.0%, and 8.6%, respectively. This indicates that the device can not only withstand mechanical bending but also maintain consistent response / output characteristics under bending conditions, which is a significant advantage for achieving stable electronic device characteristics in wearable devices. In conclusion, the application of the composite dielectric film prepared by the molecular layer deposition / atomic layer deposition composite process in all-carbon nanotube thin-film transistor devices has been fully demonstrated, and the results show that the device possesses both superior electrical and mechanical properties.

[0078] Inverters, ring oscillators, logic gates, and amplifiers: Figure 4 These are the test results of an inverter based on an intrinsically flexible composite dielectric-all-carbon nanotube thin-film transistor. Figure 4 A is a schematic diagram of an integrated circuit sample. Figure 4 B is a photograph of an integrated circuit sample. Figure 4 C is the voltage transfer curve (V) of 20 inverters. dd =5V); the embedded panel displays the circuit diagram and photomicrographs of the inverter. Figure 4 D is the hysteresis curve of the inverter. Figure 4 E is the voltage transmission curve of the inverter after being bent by different radii of curvature. Figure 4 F is the statistical result of the gain values ​​of 70 pseudo-complementary transistor inverters (V). dd =1V); the embedded panel displays a photomicrograph of the inverter. Figure 4 G is the voltage transfer curve of the inverter under different driving voltages. Figure 4 H is the gain value of the inverter under different driving voltages; Figure 4 The embedded panel in G shows the circuit diagram of the inverter. Figure 4 I represents the gain and tensile strain that can be withstood in a comparison report of a flexible inverter. Figure 4 J represents the input and output waveforms for testing the dynamic characteristics of the inverter. Figure 4 K represents the dynamic power consumption of the inverter under different drive voltages. Figure 4 L represents the driving voltage and peak power consumption of the flexible inverter as reported in the literature.

[0079] The applications of the intrinsically flexible composite dielectric-all-carbon nanotube thin-film transistors fabricated above in integrated circuits were further investigated. Firstly, basic functional units from three types of digital integrated circuits—inverters, ring oscillators, and logic gates—were fabricated and tested, such as… Figure 4 As shown in Figure A, integrated circuits on flexible substrates possess excellent transparency properties, such as... Figure 4 The photo in B is shown.

[0080] Inverters are the basic units for implementing logic functions in digital integrated circuits. Based on p-type intrinsically flexible composite dielectric-all-carbon nanotube thin-film transistors, there are two device structures that can be used to construct inverters: the common-gate source type (zero-V...). gs Common-gate source inverters have a simpler structure, making them more advantageous for achieving high integration; while pseudo-complementary transistor (PCS) structures typically offer superior performance, including high gain, low power consumption, and high noise margin. Figure 4 A presents the voltage transfer characteristic (VTC) curves of 20 diode-loaded inverters. Their reverse output characteristic oscillation is well controlled, especially the reverse voltage value, which has a relative statistical standard deviation of only 1.7%. Furthermore, no hysteresis is observed in the VTC of any of these devices. These excellent characteristics demonstrate the advantages of inverters based on intrinsically flexible composite dielectric-all-carbon nanotube thin-film transistors in terms of integration. Simultaneously, this type of inverter exhibits excellent mechanical flexibility; after being bent with a radius of curvature of 2 mm, the voltage transfer characteristics of the inverter do not change significantly. Figure 4 (E). Notably, previous reports on carbon nanotube-based inverters rarely included descriptions of device bending characteristics at the circuit level, as is the case in this application. This is likely due to the inherently brittle metal oxide dielectric materials used previously, which limited the mechanical flexibility of the integrated transistor device (see Table 1 for relevant statistics). Furthermore, a bending radius of 2 mm is sufficient to support the circuit in today's common flexible circuit applications, such as foldable / rollable displays, wearable devices, and electronic skin. The tensile strain experienced by the circuit elements on the upper surface of the substrate, calculated using a 125 μm substrate thickness, is approximately 3.1%, an impressive figure rarely reported at the circuit level.

[0081] Figure 4 F presents gain statistics for 70 pseudo-complementary transistor inverters, exhibiting an average gain of 63.0 and a maximum gain of 77.8 at a drive voltage of 1V. Furthermore, at V... dd At a level of / 2, the noise margin of the pseudo-complementary transistor inverter reaches 88.2% ( Figure 18 The device also has the capability to operate with a wide range of drive voltages, V dd The device exhibits excellent input / output response across a voltage range of 50mV to 5V. Figure 4 G, H). Specifically, in V ddAt 5V, the pseudo-complementary transistor inverter exhibited a gain of 342.5; this figure sets a new gain record for carbon nanotube-based flexible inverters within our most comprehensive survey range (see Table 1). Figure 4 As shown in Figure I, the inverter based on the composite dielectric-all-carbon nanotube thin-film transistor possesses both high gain and excellent mechanical flexibility, significantly outperforming the performance of carbon nanotube-based inverters reported in recent years. The high gain characteristic of inverters is crucial for signal holding and amplification in integrated circuits; therefore, this inverter will have significant advantages in digital electronic applications such as switching circuits, digital signal processing, and signal output layers. Furthermore, this inverter exhibits excellent characteristics of operating at low drive voltages (50mV), with peak and dynamic power consumption of approximately 0.74 and 0.66 nW, respectively. Figure 4 J, K). Currently, this power consumption level is the lowest among carbon nanotube-based unipolar (even complementary) inverters. Figure 4 Therefore, by combining molecular layer deposition / atomic layer deposition composite processes with all-carbon nanotube thin-film transistor fabrication processes, high-performance, low-power circuit applications with intrinsic flexibility can be realized; its low-voltage drive characteristics further give it the potential to be combined with emerging technologies in wearable devices such as bioelectric drives.

[0082] Table 1

[0083]

[0084] Note: PEN: Polyethylene naphthalate; PET: Polyethylene terephthalate; PVA: Polyvinyl alcohol

[0085] (References:)

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[0096] Figure 5 These are the test results of a ring oscillator and logic gate based on an intrinsically flexible composite dielectric-all-carbon nanotube thin-film transistor. Figure 5 A is a photomicrograph of the 3rd and 7th stage ring oscillators. Figure 5 B is the output waveform of the 7-stage ring oscillator under different driving voltages. Figure 5 C is the 1.75kHz oscillation waveform output by the 3-stage ring oscillator. Figure 5 D is the input signal waveform diagram used to test the function of the logic gate circuit and the truth table of the logic gate circuit under test. Figure 5 E- Figure 5 H is based on an intrinsically flexible composite dielectric-all-carbon nanotube thin-film transistor. Figure 5 E-NOT gate; Figure 5 F-OR NOT gate; Figure 5 G XOR gate; Figure 5 Output waveform, circuit diagram, and photomicrograph of the H-AND gate.

[0097] Multiple flexible inverters can be cascaded to form a ring oscillator, such as... Figure 5 As shown in Figure A, the output waveforms of the 3-stage and 7-stage ring oscillators are... Figure 5 The B and 5C models are shown. The 7-stage ring oscillator can be driven by a voltage ranging from 1.3 to 5V and maintains a stable oscillation output. Figure 5 B). Figure 5 C demonstrates the output signal of a three-stage ring oscillator operating at a 3V drive voltage, with a stable oscillation frequency reaching 1.75kHz. This frequency is sufficient for applications such as high refresh rate displays, biosignal sensing, and monitoring. Further integration of flexible composite dielectric-all-carbon nanotube thin-film transistors based on high-performance inverters, achieving ring oscillator-level circuitry, further demonstrates the high yield and wide-ranging consistency of composite dielectric thin film and circuit fabrication processes. This key characteristic for widespread manufacturing and application can also be reflected in the fabricated logic gate circuits. For example... Figure 5 As shown in DH, the NAND gate, NOR gate, XOR gate, and AND gate fabricated by composite dielectric-all-carbon nanotube thin film transistors can all stably achieve correct logic calculation functions.

[0098] Figure 6 This diagram illustrates an amplifier based on an intrinsically flexible composite dielectric-all-carbon nanotube thin-film transistor and its potential electrocardiogram monitoring function. Figure 6 A is a schematic diagram of using a flexible amplifier to amplify electrocardiogram signals. Figure 6 B is an analog signal amplified up to 100 times by an amplifier. Figure 6 C represents the amplification effect of analog signals at different frequencies.

[0099] Besides its application in logic circuits, the high-gain characteristics of inverters can also be used for signal amplification in analog circuits. For example, real-time monitoring of human biosignals is an important application scenario for flexible wearable devices, and amplifying weak biosignals is an important prerequisite for subsequent processing of these signals and analysis and monitoring of human condition. Electrocardiogram (ECG) signals are representative of such biosignals, typically exhibiting millivolt-level raw signal transduction. To demonstrate the application potential of flexible amplifiers based on composite dielectric-all-carbon nanotube thin-film transistors in such scenarios (…),… Figure 6 A), its amplification capability for small analog signals was first demonstrated. Figure 6 B). The 40mV input signal was amplified 100 times after being processed by the flexible amplifier, and the waveform was well preserved. Figure 6 C demonstrates the amplifier's amplification capability for small signals at different frequencies, exhibiting a stable amplification factor within the 10 to 50 Hz range. By further integrating digital circuit units (ring oscillators, logic gates) and analog circuit units (amplifiers) based on composite dielectric-all-carbon nanotube thin-film transistors, wearable health monitoring devices, such as ECG monitoring devices, can be driven by inherently flexible circuits. Figure 6 A) This demonstrates the broad application prospects and potential of molecular layer deposition / atomic layer deposition composite dielectric deposition technology and all-carbon nanotube flexible circuit technology in the coming era of the "Internet of Things".

[0100] Example 2

[0101] Fabrication and characterization of composite dielectric thin films and MIM capacitors based on composite dielectric thin films:

[0102] Both polyimide and composite films were prepared using a self-built tubular atomic layer deposition / molecular layer deposition system. The polyimide molecular layer deposition process used ethylenediamine (EDA) and pyromellitic dianhydride (PMDA) as precursors; the alumina atomic layer deposition process used trimethylaluminum (TMA) and water vapor as precursors. Polyimide films were prepared separately using this molecular layer deposition process, while composite films were prepared by alternating molecular layer deposition and atomic layer deposition in the same reactor. During these processes, the ethylenediamine, trimethylaluminum, and water vapor reagents were volatilized at room temperature, while the pyromellitic dianhydride was placed in a hot air chamber and sublimated at 163°C. Purified nitrogen was used as the purge and precursor transport auxiliary gas in the process. The purge gas pressure was 1 Torr. The reaction chamber temperature was set at 165°C, slightly higher than the sublimation temperature of pyromellitic dianhydride, to prevent condensation of pyromellitic dianhydride within the chamber. The polyimide molecular layer deposition process employed a "valve-off" mode, with exposures of 0.033 and 0.063 Torr·s for the pyromellitic dianhydride and ethylenediamine precursors, respectively, and a 100-s purge time. The alumina atomic layer deposition process employed a "flow-through" mode, with exposures of 0.014 and 0.064 Torr·s for the trimethylaluminum and water vapor precursors, respectively. The molecular layer deposition / atomic layer deposition composite process for depositing the composite film was constructed using a "supercycle" approach. Each supercycle consisted of 10 consecutive polyimide molecular layer deposition cycles followed by 3 atomic layer deposition cycles, for a total of 13 supercycles.

[0103] The film thickness was measured using an ellipsometry (M-2000, JA Woollam) with polarized light incident angles of 65°, 70°, and 75°. The measured spectra were fitted using a Cauchy model to extract the thickness values. The composition of the composite film was also analyzed using Rutherford backscattering (RBS) characterization, with incident particles of 2 MeV He. + The beam inlet angle is 152°.

[0104] PET-ITO substrates were used to fabricate metal-insulated-gate dielectric-metal (MIM) capacitors. A 20nm ITO thin film pre-fabricated on the substrate served as the bottom electrode of the device. The insulating gate dielectric layer was fabricated using the following process: 20 cycles of alumina atomic layer deposition (forming an approximately 2nm buffer layer), 13 super-cycle composite deposition (forming an approximately 35nm composite thin film), and 30 cycles of alumina atomic layer deposition (forming an approximately 3nm buffer layer). Finally, 110nm copper was fabricated as the top electrode by vapor deposition and patterning using a mask. The electrical characterization of the MIM capacitors was performed using a probe station and a semiconductor performance tester (B1500A, Keysight). The test voltage range is shown in the test results. The relative permittivity / dielectric loss-frequency response of the MIM capacitors was accurately measured using an LCR source meter (E4980A, Keysight) with a test bias of 0V and an alternating signal amplitude of 20mV.

[0105] Results and Discussion:

[0106] Figure 7 These are the growth characteristic curves of the composite dielectric thin film. Figure 7 A is the curve showing the change in thin film deposition rate with different exposure levels of pyromellitic dianhydride precursors. Figure 7 B is the curve showing the change in thin film deposition rate with different ethylenediamine precursor exposure levels.

[0107] The composite process demonstrated in Example 2 retains good self-limiting properties. The composite dielectric film deposited by the composite process has a saturation growth rate of 28.3 Å per supercycle, with 2 pulses of ethylenediamine and 10 pulses of pyromellitic dianhydride precursor exposure required to reach saturation.

[0108] Figure 8 These are the Rutherford backscattering test results for the composite dielectric thin film. Figure 8 A is the Rutherford backscattering spectrum of the composite dielectric thin film. Figure 8 B represents the measured Al:N atomic ratio and film mass density in the composite dielectric film.

[0109] like Figure 8 A and Figure 8 As shown in Figure B, the composite process demonstrated in Example 2 achieved the composite of alumina and polyimide components, with an Al:N atomic ratio of 0.62 and a film density of 1.19 g. cm −3 .

[0110] Figure 9 These are the test results of the electrical properties of the composite dielectric thin film. Among them... Figure 9 A is the voltage-current curve of the composite dielectric film. Figure 9B is the relative permittivity / dielectric loss-frequency response of the composite dielectric film.

[0111] like Figure 9 As shown in Figure A, the composite film presented in Example 2 possesses certain insulating properties, 1 MVcm −1 The leakage current under the electric field strength is 5.58 × 10⁻⁶. −6 Acm −2 .like Figure 9 As shown in B, the composite film shown in Example 2 has a relative permittivity of 6.8 (1 kHz), but it decays significantly with increasing frequency; its dielectric loss is high (about 2% at high frequencies) and close to 5% at low frequencies.

[0112] Example 3

[0113] Fabrication and characterization of composite dielectric thin films and MIM capacitors based on composite dielectric thin films:

[0114] Both polyimide and composite films were prepared using a self-built tubular atomic layer deposition / molecular layer deposition system. The polyimide molecular layer deposition process used ethylenediamine (EDA) and pyromellitic dianhydride (PMDA) as precursors; the alumina atomic layer deposition process used trimethylaluminum (TMA) and water vapor as precursors. Polyimide films were prepared separately using this molecular layer deposition process, while composite films were prepared by alternating molecular layer deposition and atomic layer deposition in the same reactor. During these processes, the ethylenediamine, trimethylaluminum, and water vapor reagents were volatilized at room temperature, while the pyromellitic dianhydride was placed in a hot air chamber and sublimated at 163°C. Purified nitrogen was used as the purge and precursor transport auxiliary gas in the process. The purge gas pressure was 1 Torr. The reaction chamber temperature was set at 165°C, slightly higher than the sublimation temperature of pyromellitic dianhydride, to prevent condensation of pyromellitic dianhydride within the chamber. The polyimide molecular layer deposition process employed a "valve-off" mode, with exposures of 0.033 and 0.063 Torr·s for the pyromellitic dianhydride and ethylenediamine precursors, respectively, and a purge time of up to 100 s. The alumina atomic layer deposition process employed a "flow-through" mode, with exposures of 0.014 and 0.064 Torr·s for the trimethylaluminum and water vapor precursors, respectively. The molecular layer deposition / atomic layer deposition composite process for depositing the composite film was constructed using a "supercycle" approach. Each supercycle consisted of five consecutive polyimide molecular layer deposition cycles followed by three atomic layer deposition cycles, for a total of 17 supercycles.

[0115] The film thickness was measured using an ellipsometry (M-2000, JA Woollam) with polarized light incident angles of 65°, 70°, and 75°. The measured spectra were fitted using a Cauchy model to extract the thickness values. The composition of the composite film was also analyzed using Rutherford backscattering (RBS) characterization, with incident particles of 2 MeV He. + The beam inlet angle is 152°.

[0116] PET-ITO substrates were used to fabricate metal-insulating-gate dielectric-metal (MIM) capacitors. A 20nm ITO thin film pre-fabricated on the substrate served as the bottom electrode of the device. The insulating gate dielectric layer was fabricated using the following process: 20 cycles of alumina atomic layer deposition (forming an approximately 2nm buffer layer), 17 super-cycle composite deposition (forming an approximately 35nm composite thin film), and 30 cycles of alumina atomic layer deposition (forming an approximately 3nm buffer layer). Finally, 110nm copper was fabricated as the top electrode by vapor deposition and patterning using a mask. The electrical characterization of the MIM capacitors was performed using a probe station and a semiconductor performance tester (B1500A, Keysight). The test voltage range is shown in the test results. The relative permittivity / dielectric loss-frequency response of the MIM capacitors was accurately measured using an LCR source meter (E4980A, Keysight) with a test bias of 0V and an alternating signal amplitude of 20mV.

[0117] Results and Discussion:

[0118] Figure 7 These are the growth characteristic curves of the composite dielectric thin film. Figure 7 A is the curve showing the change in thin film deposition rate with different exposure levels of pyromellitic dianhydride precursors. Figure 7 B is the curve showing the change in thin film deposition rate with different ethylenediamine precursor exposure levels.

[0119] The composite process demonstrated in Example 3 retains good self-limiting properties. The composite dielectric film deposited by the composite process has a saturation growth rate of 20.0 Å per supercycle, with 2 pulses of ethylenediamine and 10 pulses of pyromellitic dianhydride precursor exposure required to reach saturation.

[0120] Figure 8 These are the Rutherford backscattering test results for the composite dielectric thin film. Figure 8 A is the Rutherford backscattering spectrum of the composite dielectric thin film. Figure 8 B represents the measured Al:N atomic ratio and film mass density in the composite dielectric film.

[0121] like Figure 8 A and Figure 8As shown in B, the composite process demonstrated in Example 3 achieved the composite of alumina and polyimide components, with an Al:N atomic ratio of 0.82 in the film and a film density of 1.50 g. cm −3 .

[0122] Figure 9 These are the test results of the electrical properties of the composite dielectric thin film. Among them... Figure 9 A is the voltage-current curve of the composite dielectric film. Figure 9 B is the relative permittivity / dielectric loss-frequency response of the composite dielectric film.

[0123] like Figure 9 As shown in Figure A, the composite film presented in Example 3 possesses certain insulating properties, 1 MVcm −1 The leakage current under the field strength is 1.61 × 10⁻⁶. −6 Acm −2 .like Figure 9 As shown in B, the composite film shown in Example 3 has a relative permittivity of 6.4 (1 kHz) and does not show significant attenuation with frequency; its dielectric loss is less than 1% at high frequencies, but slightly higher than 1% at low frequencies.

[0124] Example 4.

[0125] Fabrication and characterization of composite dielectric thin films and MIM capacitors based on composite dielectric thin films:

[0126] Both polyimide and composite films were prepared using a self-built tubular atomic layer deposition / molecular layer deposition system. The polyimide molecular layer deposition process used ethylenediamine (EDA) and pyromellitic dianhydride (PMDA) as precursors; the alumina atomic layer deposition process used trimethylaluminum (TMA) and water vapor as precursors. Polyimide films were prepared separately using this molecular layer deposition process, while composite films were prepared by alternating molecular layer deposition and atomic layer deposition in the same reactor. During these processes, the ethylenediamine, trimethylaluminum, and water vapor reagents were volatilized at room temperature, while the pyromellitic dianhydride was placed in a hot air chamber and sublimated at 163°C. Purified nitrogen was used as the purge and precursor transport auxiliary gas in the process. The purge gas pressure was 1 Torr. The reaction chamber temperature was set at 165°C, slightly higher than the sublimation temperature of pyromellitic dianhydride, to prevent condensation of pyromellitic dianhydride within the chamber. The polyimide molecular layer deposition process employed a "valve-off" mode, with exposures of 0.033 and 0.063 Torr·s for the pyromellitic dianhydride and ethylenediamine precursors, respectively, and a purge time of up to 100 s. The alumina atomic layer deposition process employed a "flow-through" mode, with exposures of 0.014 and 0.064 Torr·s for the trimethylaluminum and water vapor precursors, respectively. The molecular layer deposition / atomic layer deposition composite process for depositing the composite film was constructed using a "supercycle" approach, with each supercycle consisting of one polyimide molecular layer deposition cycle followed by three atomic layer deposition cycles, for a total of 57 supercycles.

[0127] The film thickness was measured using an ellipsometry (M-2000, JA Woollam) with polarized light incident angles of 65°, 70°, and 75°. The measured spectra were fitted using a Cauchy model to extract the thickness values. The composition of the composite film was also analyzed using Rutherford backscattering (RBS) characterization, with incident particles of 2 MeV He. + The beam inlet angle is 152°.

[0128] PET-ITO substrates were used to fabricate metal-insulated gate dielectric-metal (MIM) capacitors. A 20 nm ITO thin film pre-fabricated on the substrate served as the bottom electrode of the device. The insulating gate dielectric layer was fabricated using the following process: 20 cycles of alumina atomic layer deposition (forming an approximately 2 nm buffer layer), 57 super-cycle composite deposition (forming an approximately 35 nm composite thin film), and 30 cycles of alumina atomic layer deposition (forming an approximately 3 nm buffer layer). Finally, 110 nm copper was fabricated as the top electrode by vapor deposition and patterning using a mask. The electrical characterization of the MIM capacitors was performed using a probe station and a semiconductor performance tester (B1500A, Keysight). The test voltage range is shown in the test results. The relative permittivity / dielectric loss-frequency response of the MIM capacitors was accurately measured using an LCR source meter (E4980A, Keysight) with a test bias of 0 V and an alternating signal amplitude of 20 mV.

[0129] Results and Discussion:

[0130] Figure 7 These are the growth characteristic curves of the composite dielectric thin film. Figure 7 A is the curve showing the change in thin film deposition rate with different exposure levels of pyromellitic dianhydride precursors. Figure 7 B is the curve showing the change in thin film deposition rate with different ethylenediamine precursor exposure levels.

[0131] The composite process demonstrated in Example 4 retains good self-limiting properties. The composite dielectric film deposited by the composite process has a saturation growth rate of 6.7 Å per supercycle, with 2 pulses and 8 pulses of ethylenediamine and pyromellitic dianhydride precursor exposures required to reach saturation.

[0132] Figure 8 These are the Rutherford backscattering test results for the composite dielectric thin film. Figure 8 A is the Rutherford backscattering spectrum of the composite dielectric thin film. Figure 8 B represents the measured Al:N atomic ratio and film mass density in the composite dielectric film.

[0133] like Figure 8 A and Figure 8 As shown in B, the composite process demonstrated in Example 4 achieved the composite of alumina and polyimide components, with an Al:N atomic ratio of 2.15 and a film density of 1.79 g. cm −3 .

[0134] Figure 9 These are the test results of the electrical properties of the composite dielectric thin film. Among them... Figure 9 A is the voltage-current curve of the composite dielectric film. Figure 9B is the relative permittivity / dielectric loss-frequency response of the composite dielectric film.

[0135] like Figure 9 As shown in Figure A, the composite film presented in Example 4 exhibits excellent insulation properties, 1 MV cm −1 The leakage current is 2.30 under the electric field strength. × 10 −8 A cm −2 .like Figure 9 As shown in B, the composite film shown in Example 4 has a relative permittivity of 4.8 (1 kHz) and does not show significant attenuation with frequency; its dielectric loss is significantly lower than 1% and does not change with frequency.

[0136] In this application, an innovative composite dielectric material based on polyimide and alumina is first prepared and studied using a molecular layer deposition (MLD) / atomic layer deposition (ALD) composite process. In the composite film, the polyimide polymer component provides intrinsic flexibility, while the alumina component significantly optimizes the film quality and electrical properties. The MLD / ALD composite process used in the material preparation is a vapor-phase thin film deposition process with large-area uniformity and excellent conformal properties, thus possessing inherent advantages in large-area thin film preparation, thickness control, and process integration. In the composite process, MLD and ALD processes are performed alternately, achieving the alternating deposition of sub-nanometer-level organic and inorganic "layers," thereby obtaining a homogeneous composite dielectric film.

[0137] This composite dielectric film was subsequently integrated into the fabrication process of an all-carbon nanotube thin-film transistor, realizing a thin-film transistor device with intrinsic flexibility. This thin-film transistor exhibits excellent device performance, and the fabrication process also demonstrates top-tier large-area uniformity and device yield. Statistical analysis of the device characteristic parameters shows that the composite dielectric-all-carbon nanotube thin-film transistor has a performance of −0.67±0.14. V's small threshold voltage, 10 4.54±0.26 High on / off ratio, 0.26±0.05 V dec −1 Low subthreshold swing, and below 20 fA μm −2The device exhibits low leakage current density and excellent mechanical flexibility, maintaining consistent transistor characteristics after 2000 bends at a bending radius of 3.4 mm. Building upon the composite dielectric-all-carbon nanotube thin-film transistor, various fundamental digital circuit units with superior characteristics, including inverters, ring oscillators, and logic gates, were further demonstrated. The inverter circuit achieved a record-breaking gain of 342.5 and maintained consistent output characteristics even after being subjected to a 3.1% tensile strain; its drive voltage requirement was as low as 50 mV, demonstrating strong application potential in low-voltage, low-power circuits. The inverter's excellent performance consistency allows for further integration, enabling the fabrication of larger-scale ring oscillators. Beyond digital circuit applications, this high-gain, low-voltage driven inverter also demonstrates excellent performance in analog signal amplification, amplifying millivolt-level input signals by 100 times. In summary, molecular layer deposition / atomic layer deposition composite dielectric deposition technology and all-carbon nanotube flexible circuit technology have broad application prospects and potential in the coming "Internet of Things" era, especially in real-time health monitoring and wearable devices.

[0138] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for preparing a composite dielectric film based on polyimide-inorganic oxide, characterized in that, include: Polyimide molecular layer deposition and inorganic oxide atomic layer deposition are performed alternately in the same reactor. The inorganic oxide is alumina. The molecular layer deposition / atomic layer deposition composite process for depositing composite films is carried out by supercycle. Each supercycle consists of 1 to 10 consecutive polyimide molecular layer deposition cycles followed by 1 to 3 consecutive atomic layer cycles. Up to 3 consecutive atomic layer depositions can achieve efficient alumina doping and prevent the formation of continuous alumina films.

2. The method for preparing a composite dielectric film based on polyimide-inorganic oxide as described in claim 1, characterized in that, The polyimide molecular layer deposition uses at least one diamine selected from ethylenediamine, propylenediamine, butanediamine, pentanediamine, hexanediamine, phenylenediamine, and 4,4'-diaminodiphenyl ether, and at least one dianhydride selected from pyromellitic dianhydride and naphthalenetetracarboxylic dianhydride as a precursor.

3. The method for preparing a composite dielectric film based on polyimide-inorganic oxide as described in claim 1, characterized in that, Alumina atomic layer deposition uses at least one metal compound selected from aluminum trichloride, trimethylaluminum, triethylaluminum, dimethylisopropoxyaluminum, methyldiisopropoxyaluminum, triisopropoxyaluminum, diethylaluminum chloride, tridimethylaminoaluminum, and tridiethylaminoaluminum, as well as at least one oxidant selected from water vapor, hydrogen peroxide, ozone, air, and oxygen plasma as a precursor.

4. The method for preparing a composite dielectric film based on polyimide-inorganic oxide as described in claim 1, characterized in that, During the process, each reaction precursor is allowed to volatilize naturally at room temperature or is heated to volatilize.

5. The method for preparing a composite dielectric film based on polyimide-inorganic oxide as described in claim 4, characterized in that, The precursor is heated and volatilized using at least one of the following heating devices: heating belt, heating jacket, and hot air box.

6. The method for preparing a composite dielectric film based on polyimide-inorganic oxide as described in claim 1, characterized in that, Purified nitrogen or purified argon is used as the purging and precursor transport auxiliary gas.

7. The method for preparing a composite dielectric film based on polyimide-inorganic oxide as described in claim 6, characterized in that, The pressure of the purging gas is 0.05 Torr ~ 50 Torr; the purging time is 1 ~ 1000 s.

8. The method for preparing a composite dielectric film based on polyimide-inorganic oxide as described in claim 1, characterized in that, The reaction chamber temperature is set to 150°C ~ 220°C.

9. The method for preparing a composite dielectric film based on polyimide-inorganic oxide as described in claim 1, characterized in that, The reaction chamber temperature is set to 160°C ~ 200°C.

10. The method for preparing a composite dielectric film based on polyimide-inorganic oxide as described in claim 1, characterized in that, The reaction chamber temperature is set to 165°C ~ 180°C.

11. The method for preparing a composite dielectric film based on polyimide-inorganic oxide as described in claim 1, characterized in that, The polyimide molecular layer deposition process employs either a "valve-off" or "flow-through" mode.

12. The method for preparing a composite dielectric film based on polyimide-inorganic oxide as described in claim 2, characterized in that, The exposure amounts of dianhydride and diamine precursors were 0.001–10 Torr·s, respectively.

13. The method for preparing a composite dielectric film based on polyimide-inorganic oxide as described in claim 2, characterized in that, The exposure levels of dianhydride and diamine precursors were 0.01–0.5 Torr·s, respectively.

14. The method for preparing a composite dielectric film based on polyimide-inorganic oxide as described in claim 2, characterized in that, The exposure levels of dianhydride and diamine precursors were 0.03–0.08 Torr·s, respectively.

15. The method for preparing a composite dielectric film based on polyimide-inorganic oxide as described in claim 1, characterized in that, The oxide atomic layer deposition process employs either a "valve-off" or "flow-through" mode.

16. The method for preparing a composite dielectric film based on polyimide-inorganic oxide as described in claim 3, characterized in that, The exposure levels of metal compounds and oxidant precursors ranged from 0.001 to 10 Torr·s, respectively.

17. The method for preparing a composite dielectric film based on polyimide-inorganic oxide as described in claim 3, characterized in that, The exposure levels of metal compounds and oxidant precursors were 0.01–1 Torr·s, respectively.

18. The method for preparing a composite dielectric film based on polyimide-inorganic oxide as described in claim 3, characterized in that, The exposure amounts of metal compounds and oxidant precursors were 0.01–0.5 Torr·s and 0.02–1 Torr·s, respectively.

19. A composite dielectric film based on polyimide-inorganic oxide prepared by any one of the preparation methods according to claims 1-18, characterized in that, It includes a polyimide layer formed by molecular layer deposition on a substrate and an inorganic oxide layer formed by atomic layer deposition, wherein the inorganic oxide is aluminum oxide.

20. The composite dielectric film based on polyimide-inorganic oxide as described in claim 19, characterized in that, The polyimide layer formed by molecular layer deposition and the inorganic oxide layer formed by atomic layer deposition have thicknesses ranging from nanometer to sub-nanometer.

21. The composite dielectric film based on polyimide-inorganic oxide as described in claim 19, characterized in that, The total thickness of the composite dielectric film is controlled at the nanoscale by super-cycle formulation and quantity, thereby achieving a minimum precision of 0.1 nm.

22. The composite dielectric film based on polyimide-inorganic oxide as described in claim 19, characterized in that, The total thickness of the composite dielectric film is 0.1 nm to 1000 nm.

23. The composite dielectric film based on polyimide-inorganic oxide as described in claim 19, characterized in that, The composite dielectric film has the following characteristics: density 1.0 g / cm³. -3 ~3.5gcm -3 Dielectric constant 3~9, resistivity 1×10 3 MΩcm ~ 1×10 9 MΩcm, with a root mean square surface roughness of 0.1nm ~ 3.0nm.

24. The composite dielectric film based on polyimide-inorganic oxide as described in claim 19, characterized in that, The composite dielectric film has the following characteristics: density 1.2 g / cm³. -3 ~1.8gcm -3 Dielectric constant 5~9, resistivity 1×10 7 MΩcm ~ 1×10 9 MΩcm, with a root mean square surface roughness of 0.2nm ~ 0.5nm.

25. The composite dielectric film based on polyimide-inorganic oxide as described in claim 19, characterized in that, At least one diamine selected from ethylenediamine, propylenediamine, butanediamine, pentanediamine, hexanediamine, phenylenediamine, and 4,4'-diaminodiphenyl ether, and at least one dianhydride selected from pyromellitic dianhydride and naphthalenetetracarboxylic dianhydride, are used as precursors for polyimide.

26. The composite dielectric film based on polyimide-inorganic oxide as described in claim 19, characterized in that, The substrate is a single-crystal silicon substrate, a thermally oxidized silicon substrate, a glass substrate, a polyethylene terephthalate (PET) substrate, a polyethylene naphthalate substrate, or a polyimide substrate.

27. A flexible thin-film transistor, characterized in that, The composite dielectric film according to any one of claims 19-26 or the composite dielectric film prepared by the preparation method according to any one of claims 1-18 is used as the insulating gate dielectric layer in a flexible thin film transistor.

28. The thin-film transistor as claimed in claim 27, characterized in that, The flexible thin-film transistor is an all-carbon nanotube thin-film transistor.

29. A flexible electronic circuit, characterized in that, It includes the flexible thin-film transistor as described in claim 27 or 28.

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