Flexible neuroretinal device and method of manufacturing thereof

Abstract

The present application discloses a flexible neural retina device and a preparation method thereof. The flexible neural retina device comprises: a flexible substrate; an isolation layer formed on the flexible substrate at a certain interval; a bottom gate electrode formed on the flexible substrate in the interval of the isolation layer; an organic ferroelectric polymer thin film formed on the structure; an inorganic hafnium-based ferroelectric thin film formed on the organic ferroelectric polymer thin film; a p-type two-dimensional semiconductor material layer and an n-type oxide semiconductor layer, both of which are overlapped with each other to form a pn junction type channel layer with photoelectric response, formed on the inorganic hafnium-based ferroelectric thin film and above the bottom gate electrode; and an electrode material stack formed on both sides of the p-type two-dimensional semiconductor material layer and the n-type oxide semiconductor layer, respectively.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor technology, in particular to a flexible neural retina device and a preparation method thereof. BACKGROUND

[0002] With the development of portable electronics, wearable smart electronic devices have gradually penetrated into daily life. However, traditional integrated circuit chips are all based on silicon wafer substrates, and due to the rigid characteristics of silicon wafers, it is difficult to be applied to wearable application scenarios. Therefore, it is necessary to develop flexible semiconductor materials, processes and circuits to improve the impact resistance, bendability and other technical characteristics of wearable devices.

[0003] Ferroelectric memory is a stable storage electronic device, but the traditional material system is mostly based on barium titanate, lead zirconate titanate and other perovskite oxides, which not only contains lead and other environmentally unfriendly heavy metal elements, but also has difficulty in miniaturization, and cannot adapt to the size miniaturization development route of integrated circuits. On the other hand, new hafnium-based ferroelectric materials represented by HfZrOx, HfAlOx and HfSiOx can produce ferroelectric properties at a thickness of 10 nm, and have excellent CMOS process compatibility. However, hafnium-based ferroelectric materials are still difficult to work stably on flexible substrates, and thin films face problems such as bending and cracking, almost no photoresponse, and the like, and there is an urgent need to develop high-flexibility ferroelectric material systems and supporting channel materials to realize flexible electronic applications with excellent photoelectric response.

[0004] Traditional integrated circuit devices face the problem of separation of storage units and computing units, and the improvement of computing efficiency is bottlenecked, so it is necessary to develop more advanced computing systems. The human brain system is a highly efficient storage and computing integrated system that can consume very little energy to complete various complex computing tasks, and is considered a promising computing architecture. Using electronic devices to simulate the computing mode of the human brain has great development potential. Further, the electronic device simulating the human brain can only realize the function of storage and computing integration, and can only accept signal transmission from information sensing elements, and cannot interfere with the collection of signals, resulting in limited efficiency improvement of information sensing elements and signal transmission process. The retina is a unit that can sense optical image signals and utilize neurons to realize signal processing and storage, and plays a crucial role in signal sensing, processing and storage of the human body. Therefore, developing neural retina devices with bionic characteristics has great application value. SUMMARY

[0005] The application discloses a pn junction type flexible neural retina photoelectric device based on organic-inorganic heterojunction and a preparation scheme thereof.

[0006] The flexible neural retina device comprises a flexible substrate, an isolation layer formed on the flexible substrate at intervals, a bottom gate electrode formed on the flexible substrate in the intervals of the isolation layer, an organic ferroelectric polymer thin film formed on the structure, an inorganic hafnium-based ferroelectric thin film formed on the organic ferroelectric polymer thin film, a p-type two-dimensional semiconductor material layer and an n-type oxide semiconductor layer which are overlapped with each other to form a pn junction type channel layer with photoelectric response, and an electrode material stack formed on both sides of the p-type two-dimensional semiconductor material layer and the n-type oxide semiconductor layer.

[0007] In the flexible neural retina device, the flexible substrate is preferably white mica.

[0008] In the flexible neural retina device, the isolation layer is preferably a high-k oxide dielectric.

[0009] In the flexible neural retina device, the organic ferroelectric polymer thin film is preferably P(VDF-TrFE).

[0010] In the flexible neural retina device, the p-type two-dimensional semiconductor material layer is preferably MoTe2, and the n-type oxide semiconductor layer is preferably IGZO.

[0011] The preparation method of the flexible neural retina device comprises the following steps: forming an isolation layer on a flexible substrate at intervals; forming a bottom gate electrode on the flexible substrate in the intervals of the isolation layer; forming an organic ferroelectric polymer on the structure, annealing in an inert gas atmosphere to form an organic ferroelectric polymer thin film; forming an inorganic hafnium-based ferroelectric material on the organic ferroelectric polymer thin film, and performing rapid thermal annealing treatment to obtain an inorganic hafnium-based ferroelectric thin film with ferroelectricity; forming a p-type two-dimensional semiconductor material layer and an n-type oxide semiconductor layer which are overlapped with each other on the inorganic hafnium-based ferroelectric thin film and above the bottom gate electrode as a pn junction type channel layer with photoelectric response; and forming an electrode material stack on both sides of the p-type two-dimensional semiconductor material layer and the n-type oxide semiconductor layer.

[0012] Preferably, in the flexible neural retina device preparation method, the organic ferroelectric polymer film is P(VDF-TrFE).

[0013] Preferably, in the flexible neural retina device preparation method, the annealing temperature of the organic ferroelectric polymer film is 150-300 DEG C, and the annealing time is 6-8 hours.

[0014] Preferably, in the flexible neural retina device preparation method, the p-type two-dimensional semiconductor material layer is MoTe2, and the n-type oxide semiconductor layer is IGZO.

[0015] Preferably, in the flexible neural retina device preparation method, the p-type two-dimensional semiconductor material layer is prepared on the inorganic hafnium-based ferroelectric film by mechanical exfoliation, with a thickness of 0.2-1 nm; the n-type oxide semiconductor layer is connected to one side of the p-type two-dimensional semiconductor material layer by electron beam lithography and physical vapor deposition, with a thickness of 20-40 nm; and rapid thermal annealing at 500-600 DEG C in an inert gas atmosphere is used to realize the crystallization of the n-type oxide semiconductor and improve the contact interface between the p-type two-dimensional semiconductor material layer and the n-type oxide semiconductor layer.

[0016] Advantages:

[0017] (1) The organic-inorganic heterostructure is used to improve the bending resistance of the pure hafnium-based oxide film, prevent performance failure caused by the rupture of the traditional oxide film under bending conditions, improve the flexibility of the device in a bending environment, and have more advantages when applied to flexible electronics.

[0018] (2) The p-type two-dimensional semiconductor material and the n-type oxide semiconductor material are connected to form a pn junction type photoelectric response channel, which can maximize the rectification characteristics under light excitation and improve the photoelectric sensitivity of the device, laying a foundation for the construction of neural retina devices.

[0019] (3) The integration of the ferroelectric dielectric layer and the pn junction channel is used to realize the preparation of the flexible neural retina device, and a diversified material combination is used to construct a new type of electronic device, providing a low-power, low-cost, and high-performance development idea for flexible neural retina devices. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a flowchart of the flexible neural retina device preparation method.

[0021] Figures 2 to 8 is a structural schematic diagram of each stage of the flexible neural retina device preparation method. DETAILED DESCRIPTION

[0022] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. It should be understood that the specific embodiments described herein are only used to explain the present application and not to limit the present application. The described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of the present application.

[0023] In the description of the present application, it should be noted that the terms "upper", "lower", "vertical", "horizontal" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0024] In addition, many specific details of the present application are described below, such as the structure, material, size, processing and technology of the device, in order to more clearly understand the present application. However, as those skilled in the art can understand, the present application can be implemented without these specific details. Unless specifically indicated below, each part in the device can be composed of materials known to those skilled in the art, or materials with similar functions developed in the future can be used.

[0025] Figure 1 is a flowchart of a flexible neural retinal device preparation method. As shown in Figure 1 , the flexible neural retinal device preparation method comprises the following steps:

[0026] Step S1, a 2cm x 2cm white mica substrate 100 is prepared for preparing a flexible neural retinal device. The surface of the substrate 100 is treated with oxygen plasma at a power of 150W-300W to improve the contact and enhance the surface adhesion.

[0027] Step S2, HfAlOx, HfZrOx, HfSiOx or HfLaOx high-k oxide material with a pitch of 30nm-50nm is defined and grown on the white mica substrate 100 as an isolation layer 101 by electron beam lithography and physical vapor deposition, atomic layer deposition, chemical vapor deposition and the like. The resulting structure is shown in Figure 2 . The growth temperature is 200℃-250℃, and the thickness is 5nm-10nm.

[0028] Step S3, using electron beam evaporation, thermal evaporation, physical vapor deposition, inkjet printing and other techniques to grow a bottom gate electrode 102 with a thickness of 5nm to 10nm and a width of 30-50nm in the gap between the isolation layers 101, as shown in FIG. Figure 3 As shown. The electrode material can be Pd, Ru, Co, etc.

[0029] Step S4, using a solution spin coating method or inkjet printing method to prepare a P (VDF-TrFE) organic ferroelectric polymer on the above structure, setting the temperature range to 150 ° C to 300 ° C in an atmosphere of an inert gas such as nitrogen, and baking for 6 hours to 8 hours to obtain an organic ferroelectric polymer film 103 with a thickness of 10nm to 30nm, as shown in FIG. Figure 4 shown.

[0030] Step S5, using atomic layer deposition, physical vapor deposition, etc. to grow an inorganic hafnium-based ferroelectric material such as HfAlOx, HfZrOx, HfSiOx or HfLaOx with a thickness of 5nm to 8nm on the organic ferroelectric polymer film 103, the growth temperature is 200℃ to 250℃, and a rapid thermal annealing furnace is used to achieve crystallization of the inorganic hafnium-based ferroelectric material in the temperature range of 400℃ to 500℃ to obtain an inorganic hafnium-based ferroelectric film 104 with ferroelectricity, such as Figure 5 shown.

[0031] Step S6, as Figure 6 As shown, a p-type MoTe2 or other two-dimensional semiconductor material 105 is prepared on an inorganic hafnium-based ferroelectric film by mechanical stripping as a channel layer with a thickness of 0.2nm to 1nm, so that it is located above the bottom gate electrode. It is further preferred that it covers half of the length of the bottom electrode in the vertical direction, that is, its projection in the horizontal direction coincides with half of the bottom electrode.

[0032] Step S7, using electron beam lithography and physical vapor deposition methods to overlap n-type IGZO or other oxide semiconductor layer 106 on the right side of the p-type MoTe2 or other two-dimensional semiconductor material, such as Figure 7 As shown, the thickness is 20nm to 40nm, and a rapid thermal annealing furnace is used to realize the crystallization of the n-type oxide semiconductor in the temperature range of 500℃ to 600℃ and improve the contact interface between the p-type two-dimensional material and the n-type oxide material. The gas atmosphere is an inert gas such as nitrogen to form a pn junction channel layer with photoelectric response.

[0033] Step S8, as Figure 8As shown, the electrode material Ti / Al / Ni / Au stack 107 is grown on both sides of the p-type MoTe2 and other two-dimensional semiconductor materials and n-type oxide materials by electron beam lithography and electron beam evaporation, thermal evaporation, physical vapor deposition, inkjet printing and other technologies, with thicknesses of 3-5 nm / 8-10 nm / 8-10 nm / 30-50 nm, respectively, for improving the ohmic contact between the electrode and the semiconductor material, and completing the preparation of the flexible neuromorphic retina device.

[0034] As shown in the figure, Figure 8 As shown, the flexible neural retina device includes: a flexible substrate 100; an isolation layer 101 formed on the flexible substrate 100 at a certain interval; a bottom gate electrode 102 formed on the flexible substrate 100 in the interval of the isolation layer 101; an organic ferroelectric polymer thin film 103 formed on the above structure; an inorganic hafnium-based ferroelectric thin film 104 formed on the organic ferroelectric polymer thin film 103; a p-type two-dimensional semiconductor material layer 105 and an n-type oxide semiconductor layer 106, which are overlapped with each other to form a pn junction type channel layer with photoelectric response, formed on the inorganic hafnium-based ferroelectric thin film 104 and located above the bottom gate electrode 102; and an electrode material stack 107 formed on both sides of the p-type two-dimensional semiconductor material layer 105 and the n-type oxide semiconductor layer 106, respectively.

[0035] The present application improves the bending flexibility of the device by modifying the hafnium-based ferroelectric material with organic ferroelectric polymers, solves the problem of easy breaking of traditional oxide functional layers under bending conditions, and greatly improves the ferroelectric storage performance of the device by hetero-integration of the two ferroelectric functional layers. The p-type two-dimensional semiconductor material and the n-type oxide semiconductor material are used to construct a pn junction type transistor device, which realizes the rectification effect of negative closing and positive conduction. Further, the pn junction constructed by the selected p-type two-dimensional semiconductor material and n-type oxide semiconductor material has excellent photoelectric response to optical stimulation signals in the ultraviolet and visible light bands, and the device can break through the single storage function of traditional memories, realize optical signal sensing, data storage and information processing functions similar to the human eye retina, and improve the flexibility and functionality of the device.

[0036] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical scope disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A flexible neural retinal device, characterized in that: include: Flexible substrate; an isolation layer formed on the flexible substrate at certain intervals; a bottom gate electrode formed on the flexible substrate in the gap of the isolation layer; an organic ferroelectric polymer thin film formed on the structure; an inorganic hafnium-based ferroelectric thin film formed on the organic ferroelectric polymer thin film; A p-type two-dimensional semiconductor material layer and an n-type oxide semiconductor layer are overlapped to form a pn junction channel layer with photoelectric response, formed on the inorganic hafnium-based ferroelectric thin film and located above the bottom gate electrode; Electrode material stacks are formed on both sides of the p-type two-dimensional semiconductor material layer and the n-type oxide semiconductor layer, respectively, wherein one of the electrode material stacks contacts one end of the p-type two-dimensional semiconductor material layer, and the other electrode material stack contacts one end of the n-type oxide semiconductor layer.

2. The flexible neural retinal device according to claim 1, characterized in that The flexible substrate is muscovite.

3. The flexible neural retinal device according to claim 1, characterized in that The isolation layer is a high-k oxide medium.

4. The flexible neural retinal device according to claim 1, characterized in that The organic ferroelectric polymer film is P(VDF-TrFE).

5. The flexible neural retinal device according to claim 1, characterized in that The p-type two-dimensional semiconductor material layer is MoTe2, and the n-type oxide semiconductor layer is IGZO.

6. A method for preparing a flexible neural retinal device, characterized in that: The following steps are involved: forming isolation layers at predetermined intervals on the flexible substrate; forming a bottom gate electrode on the flexible substrate in the gap of the isolation layer; forming an organic ferroelectric polymer on the structure, and annealing the polymer in an inert gas atmosphere to form an organic ferroelectric polymer thin film; forming an inorganic hafnium-based ferroelectric material on the organic ferroelectric polymer film, and performing a rapid thermal annealing process to obtain an inorganic hafnium-based ferroelectric film having ferroelectricity; forming a p-type two-dimensional semiconductor material layer and an n-type oxide semiconductor layer overlapping each other on the inorganic hafnium-based ferroelectric thin film and above the bottom gate electrode as a pn junction channel layer with photoelectric response; Electrode material stacks are formed on both sides of the p-type two-dimensional semiconductor material layer and the n-type oxide semiconductor layer, One of the electrode material stacks is in contact with one end of the p-type two-dimensional semiconductor material layer, and the other electrode material stack is in contact with one end of the n-type oxide semiconductor layer.

7. The method for preparing a flexible neural retinal device according to claim 6, wherein: The organic ferroelectric polymer film is P(VDF-TrFE).

8. The method for preparing a flexible neural retinal device according to claim 7, wherein: The annealing temperature of the organic ferroelectric polymer film is 150° C. to 300° C., and the annealing time is 6 hours to 8 hours.

9. The method for preparing a flexible neural retinal device according to claim 6, wherein: The p-type two-dimensional semiconductor material layer is MoTe2, and the n-type oxide semiconductor layer is IGZO.

10. The method for preparing a flexible neural retinal device according to claim 6, wherein: A p-type two-dimensional semiconductor material layer with a thickness of 0.2nm to 1nm is prepared on an inorganic hafnium-based ferroelectric film by mechanical exfoliation. An n-type oxide semiconductor layer is overlapped on one side of the p-type two-dimensional semiconductor material layer by using electron beam lithography and physical vapor deposition methods, with a thickness of 20nm to 40nm; The crystallization of the n-type oxide semiconductor is achieved by rapid thermal annealing at 500° C. to 600° C. in an inert gas atmosphere, and the contact interface between the p-type two-dimensional semiconductor material layer and the n-type oxide semiconductor layer is improved.

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