Storage unit and manufacturing method therefor, ferroelectric memory, and electronic device

Abstract

The present application provides a storage unit and a manufacturing method therefor, a ferroelectric memory, and an electronic device, for use in improving the performance of the ferroelectric memory. The storage unit comprises: a first electrode, a second electrode, and a ferroelectric layer, the ferroelectric layer being located between the first electrode and the second electrode. The oxygen vacancy concentration in the ferroelectric layer exhibits a gradient distribution in a first direction, the first direction being a direction from the first electrode to the second electrode. In embodiments of the present application, by setting the oxygen vacancy concentration in the ferroelectric layer to exhibit a gradient distribution in the first direction, a polarization orientation of an O-phase can also be distributed in the first direction, so as to greatly reduce randomness of the polarization orientation and improve the uniformity of the polarization orientation of the O-phase in the ferroelectric layer, thereby improving the performance of the ferroelectric memory.

Description

Storage unit, manufacturing method thereof, ferroelectric memory and electronic device

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office of the People's Republic of China on December 27, 2023, with application number 202311831799.4 and application name "A storage unit, its manufacturing method, ferroelectric memory and electronic device", the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the field of storage technology, and in particular to a storage unit, a manufacturing method thereof, a ferroelectric memory, and an electronic device. Background Art

[0004] Memories can be divided into volatile memories and non-volatile memories. Volatile dynamic random access memory (DRAM) has advantages such as fast read and write speeds and strong durability. However, DRAM has small storage capacity and high power consumption. With the rapid development of the Internet of Things, big data, and artificial intelligence, traditional DRAM can no longer meet the requirements.

[0005] New ferroelectric memories offer advantages such as high speed, excellent durability, and non-volatility. Their storage capacity, power consumption, and speed significantly improve over traditional dynamic random access memory. Hafnium oxide-based ferroelectric memories, with their superior polarization properties, excellent scalability, and high compatibility with complementary metal oxide semiconductor (CMOS) processes, hold broad application prospects in the next generation of highly integrated, low-power devices.

[0006] However, hafnium oxide films produced using the industry-proven atomic layer deposition (ALD) process naturally exhibit a polycrystalline structure, with inconsistent crystalline phases and orientations. Under current process conditions, most hafnium oxide films contain a coexistence of a ferroelectric phase (O-phase) and other non-ferroelectric phases, with the polarization orientation of the ferroelectric phase randomly distributed. This severely impacts the performance of hafnium oxide-based ferroelectric memory and hinders further optimization and improvement.

[0007] Summary of the Invention

[0008] Embodiments of the present application provide a memory cell, a manufacturing method thereof, a ferroelectric memory, and an electronic device to improve the performance of the ferroelectric memory.

[0009] In a first aspect, embodiments of the present application provide a memory cell. The memory cell provided by embodiments of the present application may include: a first electrode, a second electrode, and a ferroelectric layer, wherein the ferroelectric layer is located between the first electrode and the second electrode. The oxygen vacancy concentration in the ferroelectric layer is distributed in a gradient in a first direction. The first direction is the direction from the first electrode to the second electrode. In embodiments of the present application, the oxygen vacancy concentration in the ferroelectric layer is distributed in a gradient in the first direction, which can be understood as: the oxygen vacancies in the ferroelectric layer have a concentration difference in the first direction.

[0010] Because the oxygen vacancy concentration distribution in the ferroelectric layer is correlated with the polarization orientation of the ferroelectric phase, the built-in electric field formed by the difference in oxygen vacancy concentration has a strong template effect on the polarization orientation. Therefore, in the embodiments of the present application, the oxygen vacancy concentration in the ferroelectric layer is set to be distributed in a gradient along the first direction, which can form a built-in electric field consistent with the first direction. The formed built-in electric field can directly affect the polarization orientation of the ferroelectric phase, causing the polarization orientation of the ferroelectric phase to also be distributed along the first direction, thereby significantly reducing the randomness of the polarization orientation, improving the uniformity of the polarization orientation of the ferroelectric phase in the ferroelectric layer, and thus improving the performance of the ferroelectric memory.

[0011] The memory cell in the embodiment of the present application may be a hafnium oxide-based ferroelectric memory cell, i.e., the ferroelectric layer may include a hafnium oxide material, for example, the ferroelectric layer may include a zirconium-doped hafnium oxide (HfxZr1-xO, HZO) material. Of course, in some cases, the memory cell in the embodiment of the present application may also be a ferroelectric memory cell including other ferroelectric materials.

[0012] In a specific implementation, the memory cell in the embodiment of the present application may further include a substrate, which may serve as a carrier for the first electrode, the second electrode, and the ferroelectric layer. In the embodiment of the present application, the first electrode may be located between the substrate and the ferroelectric layer, and the second electrode may be located on a side of the ferroelectric layer facing away from the substrate. In some cases, the first electrode and the second electrode may be interchangeable and may be arranged as needed.

[0013] The above introduces the basic structure of the storage unit in the embodiment of the present application. The specific embodiment of the storage unit in the embodiment of the present application is described in detail below.

[0014] Example 1:

[0015] In some embodiments of the present application, the first electrode and the second electrode may have different oxygen vacancy generation energies, and the oxygen vacancy concentration of the ferroelectric layer at the first interface is different from the oxygen vacancy concentration at the second interface. The first interface is the interface between the ferroelectric layer and the first electrode, and the second interface is the interface between the ferroelectric layer and the second electrode. By setting the first electrode and the second electrode to have different oxygen vacancy generation energies, a difference in oxygen vacancy concentration can be formed in the ferroelectric layer at the first interface and the second interface, so that the oxygen vacancy concentration in the ferroelectric layer is gradiently distributed in the first direction, thereby forming a uniform built-in electric field inside the ferroelectric layer, thereby improving the uniformity of the polarization orientation of the ferroelectric phase in the ferroelectric layer and improving the performance of the ferroelectric memory.

[0016] During the manufacturing process, the first electrode and the second electrode can be fabricated using different chemical ratios, forming dangling bonds capable of oxygen absorption in one of the electrodes, thereby giving the first and second electrodes different oxygen vacancy generation energies. Taking the formation of dangling bonds capable of oxygen absorption in the second electrode as an example, after the first electrode, ferroelectric layer, and second electrode are sequentially formed on a substrate, the ferroelectric layer is treated using an annealing process to crystallize the ferroelectric material in the ferroelectric layer. For example, the ferroelectric layer can be treated using a rapid thermal annealing process. During the annealing process, the dangling bonds in the second electrode can absorb oxygen atoms in the ferroelectric layer, resulting in a higher number of oxygen vacancies in the ferroelectric layer at the second interface. Conversely, the first electrode will result in a lower number of oxygen vacancies in the ferroelectric layer at the first interface. This can result in a difference in oxygen vacancy concentration between the first and second interfaces in the ferroelectric layer, thereby forming a uniform built-in electric field in the ferroelectric layer. In specific implementations, the chemical ratios of the first and second electrodes can be appropriately set based on the specific materials of the first and second electrodes.

[0017] In one possible implementation, the first electrode and the second electrode may both comprise a compound material. Specifically, the first electrode and the second electrode may both comprise a first element and a second element, wherein the first element is a metal element and the second element is a non-metal element. The atomic count ratio of the first element to the second element in the first electrode is different from the atomic count ratio of the first element to the second element in the second electrode. This allows for different oxygen vacancy generation energies in the first and second electrodes. During the fabrication process, the first and second electrodes may be fabricated using different stoichiometric ratios to achieve different atomic count ratios of the first and second elements in the resulting first and second electrodes. For example, the first element may be Ti, Ta, Al, or the like, and the second element may be N, P, As, or the like. Optionally, the first electrode may comprise one or a combination of TiN, TaN, TiAlN, TiSiN, TaAlN, and TiAlCN, and the second electrode may comprise one or a combination of TiN, TaN, TiAlN, TiSiN, TaAlN, and TiAlCN.

[0018] In one embodiment, the materials of the first electrode and the second electrode can be the same. For example, the first electrode and the second electrode can both include TiN material, or the first electrode and the second electrode can both include TaN material. In another embodiment, the materials of the first electrode and the second electrode can also be different. For example, the first electrode can include TiN material and the second electrode can include TaN material; or the first electrode can include TiAlN material and the second electrode can include TiN material. In specific implementations, the materials of the first electrode and the second electrode can be set according to actual needs, and examples are not given here one by one.

[0019] In another possible implementation, the first electrode may include a metal material, and the second electrode may include a compound material. For example, the first electrode may include a metal material such as W, Al, Cu, and the second electrode may include: a first element and a second element, the first element being a metal element and the second element being a non-metal element. Exemplarily, the first element may be other metal elements such as Ti, Ta, Al, and the second element may also include other non-metal materials such as N, P, As. The second electrode may have dangling bonds of the first element; alternatively, the second electrode may have dangling bonds of the second element. In this way, the oxygen vacancy concentrations of the ferroelectric layer at the first interface and the second interface may be different.

[0020] Example 2:

[0021] In other embodiments of the present application, the ferroelectric layer may include: at least two stacked ferroelectric thin films, wherein the oxygen vacancy concentrations in adjacent two ferroelectric thin films are different. In practical applications, the number of ferroelectric thin films and the distribution pattern of the oxygen vacancy concentration in the ferroelectric layer can be set according to actual needs. In the embodiments of the present application, by providing at least two stacked ferroelectric thin films, wherein the oxygen vacancy concentrations in adjacent two ferroelectric thin films are different, the oxygen vacancy concentration in the ferroelectric layer can be made to have a gradient distribution (or chain distribution), thereby forming a uniform built-in electric field in the ferroelectric layer, wherein the direction of the built-in electric field is consistent with the first direction, thereby inducing the polarization direction of the ferroelectric phase to be arranged along the first direction.

[0022] During the fabrication process, an atomic layer deposition (ALD) process can be used to fabricate each ferroelectric thin film in the ferroelectric layer. During the deposition of each ferroelectric thin film, the oxygen dose (O-dose) can be controlled to form ferroelectric thin films with different oxygen vacancy concentrations. Specifically, the oxygen dose can be adjusted by controlling parameters such as the residence time, concentration, or flow rate of the oxygen element. For example, when the ferroelectric layer includes zirconium-doped hafnium oxide (HfxZr1-xO, HZO) material, the oxygen vacancy concentration in the ferroelectric thin film can be controlled by adjusting parameters such as the residence time, concentration, or flow rate of the oxygen (O), zirconium (Zr), and hafnium (Hf) elements.

[0023] In the embodiment of the present application, the thickness of the ferroelectric layer can be in the range of 5 nm to 15 nm, for example, the thickness of the ferroelectric layer can be 5 nm, 8 nm, 10 nm, 12 nm, or 15 nm. The thickness of a single ferroelectric thin film can be in the range of 0.5 nm to 2 nm, for example, the thickness of the ferroelectric thin film can be 0.5 nm, 1 nm, 1.5 nm, or 2 nm.

[0024] In one possible implementation, the oxygen vacancy concentration of each ferroelectric thin film in the ferroelectric layer can be distributed in a high-low alternating pattern in the first direction. For example, the oxygen vacancy concentration of each ferroelectric thin film in the ferroelectric layer can be distributed in a low-high-low-high-low pattern or a high-low-high-low-high-low pattern in the first direction. In another possible implementation, the oxygen vacancy concentration of each ferroelectric thin film in the ferroelectric layer can be distributed in a pattern that first decreases and then increases, or first increases and then decreases, in the first direction. In practical applications, the number of ferroelectric thin films in the ferroelectric layer and the distribution pattern of the oxygen vacancy concentration can be set according to actual needs.

[0025] In a second aspect, an embodiment of the present application further provides a method for manufacturing a memory cell. The method for manufacturing a memory cell provided by an embodiment of the present application may include:

[0026] Step 1: forming a first electrode on a substrate;

[0027] Step 2: depositing a ferroelectric layer on the first electrode;

[0028] Step 3: forming a second electrode on the ferroelectric layer; the first electrode and the second electrode have different oxygen vacancy generation energies;

[0029] Step 4: Use annealing process to treat the ferroelectric layer to move oxygen elements in the ferroelectric layer along the first direction so that the oxygen vacancy concentration in the ferroelectric layer is gradient distributed in the first direction, where the first direction is from the first electrode to the second electrode.

[0030] In an embodiment of the present application, by producing a first electrode and a second electrode with different oxygen vacancy generation energies, during the subsequent annealing process, the electrode with higher oxygen vacancy generation energy can absorb oxygen elements in the ferroelectric layer, causing the oxygen elements in the ferroelectric layer to move along the first direction, so that the oxygen vacancy concentration in the ferroelectric layer is gradiently distributed in the first direction, thereby forming a uniform built-in electric field inside the ferroelectric layer, thereby improving the uniformity of the polarization orientation of the ferroelectric phase in the ferroelectric layer and improving the performance of the ferroelectric memory.

[0031] The memory cell in the embodiment of the present application may be a hafnium oxide-based ferroelectric memory cell. In step 2 above, a hafnium oxide material may be used to form the ferroelectric layer. For example, a zirconium-doped hafnium oxide (HfxZr1-xO, HZO) material may be used to form the ferroelectric layer. Of course, in some cases, other ferroelectric materials may also be used to form the ferroelectric layer. In one possible implementation, the ferroelectric layer may be formed using an atomic layer deposition (ALD) process.

[0032] In the above steps 1 and 3, different chemical ratios can be used to make the first electrode and the second electrode, and dangling bonds capable of absorbing oxygen can be formed in one of the electrodes, so that the first electrode and the second electrode have different oxygen vacancy generation energies. Taking the formation of dangling bonds capable of absorbing oxygen in the second electrode as an example, in the above step 4, an annealing process is used to treat the ferroelectric layer so that the ferroelectric material in the ferroelectric layer is crystallized. For example, a rapid thermal annealing process can be used to treat the ferroelectric layer. During the annealing process, the dangling bonds in the second electrode can absorb oxygen atoms in the ferroelectric layer, so that the ferroelectric layer forms more oxygen vacancies at the second interface. On the contrary, the first electrode will cause the ferroelectric layer to have fewer oxygen vacancies at the first interface. As a result, a difference in oxygen vacancy concentration can be formed in the ferroelectric layer at the first interface and the second interface, so as to form a uniform built-in electric field in the ferroelectric layer.

[0033] The manufacturing method in the second aspect can produce the storage unit of the embodiment 1 in the above-mentioned first aspect. The specific implementation method of the manufacturing method in the second aspect can be implemented with reference to the specific implementation method of the storage unit of the embodiment 1 in the above-mentioned first aspect, and the repeated parts will not be repeated.

[0034] In a third aspect, an embodiment of the present application further provides a method for manufacturing a storage unit. The method for manufacturing a storage unit provided in an embodiment of the present application may include:

[0035] Step (1), forming a first electrode on the substrate;

[0036] Step (2), depositing at least two ferroelectric thin films sequentially on the first electrode, and making the oxygen vacancy concentrations in the two adjacent ferroelectric thin films different;

[0037] Step (3): forming a second electrode on at least two layers of ferroelectric thin films.

[0038] In an embodiment of the present application, by depositing at least two layers of ferroelectric films in sequence on the first electrode and making the oxygen vacancy concentrations in the two adjacent ferroelectric films different, the oxygen vacancy concentration in the ferroelectric layer can be distributed in a gradient, thereby forming a uniform built-in electric field in the ferroelectric layer. The direction of the built-in electric field is consistent with the first direction (the direction from the first electrode to the second electrode), thereby inducing the polarization direction of the ferroelectric phase to be arranged along the first direction.

[0039] The memory cell in the embodiment of the present application may be a hafnium oxide-based ferroelectric memory cell. In step (2) above, each ferroelectric thin film in the ferroelectric layer may be made of a hafnium oxide material. For example, the ferroelectric thin film may be made of zirconium-doped hafnium oxide (HfxZr1-xO, HZO). Of course, in some cases, other ferroelectric materials may also be used to make the ferroelectric thin film.

[0040] In step (2) above, an atomic layer deposition (ALD) process can be used to form each ferroelectric thin film. During the deposition of each ferroelectric thin film, the oxygen dose (O-dose) can be controlled to form ferroelectric thin films with different oxygen vacancy concentrations. Specifically, the oxygen dose can be adjusted by controlling parameters such as the residence time, concentration, or flow rate of the oxygen element. For example, when the ferroelectric layer includes a zirconium-doped hafnium oxide (HfxZr1-xO, HZO) material, the oxygen vacancy concentration in the ferroelectric thin film can be controlled by adjusting parameters such as the residence time, concentration, or flow rate of the oxygen (O), zirconium (Zr), and hafnium (Hf) elements.

[0041] Specifically, in step (2), the thickness of the deposited single-layer ferroelectric thin film can be in the range of 0.5 nm to 2 nm. For example, the thickness of the ferroelectric thin film can be 0.5 nm, 1 nm, 1.5 nm, or 2 nm. The total thickness of the ferroelectric layer obtained by stacking the ferroelectric thin films can be in the range of 5 nm to 15 nm. For example, the total thickness of the ferroelectric layer can be 5 nm, 8 nm, 10 nm, 12 nm, or 15 nm.

[0042] In one possible implementation, the oxygen vacancy concentration of each ferroelectric thin film in the ferroelectric layer can be distributed in a high-low alternating pattern in the first direction. For example, the oxygen vacancy concentration of each ferroelectric thin film in the ferroelectric layer can be distributed in a low-high-low-high-low pattern or a high-low-high-low-high-low pattern in the first direction. In another possible implementation, the oxygen vacancy concentration of each ferroelectric thin film in the ferroelectric layer can be distributed in a pattern that first decreases and then increases, or first increases and then decreases, in the first direction. In practical applications, the number of ferroelectric thin films in the ferroelectric layer and the distribution pattern of the oxygen vacancy concentration can be set according to actual needs.

[0043] The storage unit of the second embodiment of the first aspect can be manufactured by adopting the manufacturing method of the third aspect. The specific implementation of the manufacturing method in the third aspect can be implemented with reference to the specific implementation of the storage unit of the second embodiment of the first aspect, and the repeated parts will not be repeated.

[0044] In a fourth aspect, an embodiment of the present application further provides a ferroelectric memory. The ferroelectric memory in the embodiment of the present application may be a hafnium oxide-based ferroelectric memory. Of course, the ferroelectric memory in the embodiment of the present application may also be a ferroelectric memory comprising other ferroelectric materials. The ferroelectric memory in the embodiment of the present application may be various types of memory such as a ferroelectric random access memory (FeRAM or FRAM), a ferroelectric field effect transistor (FeFET) memory, or a ferroelectric tunnel junction (FTJ) memory.

[0045] The ferroelectric memory provided in an embodiment of the present application may include: a controller and any one of the memory cells described in the first aspect, wherein the memory cell is electrically connected to the controller. Because the polarization orientation of the ferroelectric phase in the memory cell described in the first aspect is highly uniform, the ferroelectric memory including the memory cell has excellent performance.

[0046] In a fifth aspect, an embodiment of the present application further provides an electronic device. The electronic device in the embodiment of the present application may be any electronic device with a storage function. For example, the electronic device in the embodiment of the present application may be a mobile phone, a tablet computer, a desktop computer, a smart wearable device, a vehicle-mounted device, a server, a processor, etc.

[0047] An electronic device provided by an embodiment of the present application may include: a circuit board and any ferroelectric memory according to the fourth aspect, wherein the ferroelectric memory is electrically connected to the circuit board. Since the ferroelectric memory according to the fourth aspect has high performance, the electronic device including the ferroelectric memory also has high performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] FIG1 is a schematic structural diagram of a storage unit provided in an embodiment of the present application;

[0049] FIG2 is a schematic diagram showing the relationship between oxygen vacancy concentration distribution and polarization orientation of ferroelectric domains;

[0050] FIG3 is another schematic structural diagram of a storage unit provided in an embodiment of the present application;

[0051] FIG4 is a schematic diagram of the chemical ratio of the first electrode and the second electrode in an embodiment of the present application;

[0052] FIG5 is another schematic diagram of the chemical ratio of the first electrode and the second electrode in an embodiment of the present application;

[0053] FIG6 a is another schematic structural diagram of a storage unit provided in an embodiment of the present application;

[0054] FIG6 b is a comparative example of a storage unit in the embodiment of the present application;

[0055] FIG7 is a schematic structural diagram of a ferroelectric layer in an embodiment of the present application;

[0056] FIG8 is another schematic structural diagram of the ferroelectric layer in an embodiment of the present application;

[0057] FIG9 is another schematic structural diagram of the ferroelectric layer in an embodiment of the present application;

[0058] FIG10 is a flow chart of a method for manufacturing a memory cell according to an embodiment of the present application;

[0059] FIG11 is a flow chart of another method for manufacturing a memory cell provided in an embodiment of the present application.

[0060] Reference numerals: 10 - substrate; 11 - first electrode; 12 - second electrode; 13 - ferroelectric layer; 131 - ferroelectric thin film; E - built-in electric field; P - polarization orientation; F1 - first direction; Q1 - first interface; Q2 - second interface. DETAILED DESCRIPTION

[0061] New ferroelectric memories offer advantages such as high speed, excellent durability, and non-volatility. Their storage capacity, power consumption, and speed significantly improve over traditional dynamic random access memory. Hafnium oxide-based ferroelectric memories, with their superior polarization properties, excellent scalability, and high compatibility with complementary metal oxide semiconductor (CMOS) processes, hold broad application prospects in the next generation of highly integrated, low-power devices.

[0062] However, hafnium oxide films produced using the industry's mature atomic layer deposition (ALD) process naturally exhibit a polycrystalline structure, with inconsistent crystalline phases and crystal orientations. Under current process conditions, most hafnium oxide films contain a coexistence of a ferroelectric phase (O-phase) and other non-ferroelectric phases, and the polarization orientation of the ferroelectric phase is randomly distributed. As hafnium oxide-based ferroelectric memories gradually develop towards high integration and miniaturization, their size is shrinking, and the polarization orientation uniformity of the ferroelectric phase is becoming increasingly poor. This results in a smaller difference in threshold voltages between program and erase operations, resulting in a lower degree of differentiation between program and erase operations. This severely impacts the performance of hafnium oxide-based ferroelectric memories and hinders their further optimization and improvement.

[0063] Based on this, the embodiment of the present application provides a storage unit, a method for making the same, a ferroelectric memory and an electronic device to improve the performance of the ferroelectric memory. The ferroelectric memory in the embodiment of the present application can be a hafnium oxide-based ferroelectric memory. Of course, the ferroelectric memory in the embodiment of the present application can also be a ferroelectric memory comprising other ferroelectric materials. The ferroelectric memory in the embodiment of the present application can be various types of memory such as ferroelectric random access memory (ferroelectric random access memory, FeRAM or FRAM), ferroelectric field effect transistor (ferroelectric filed effect transistor, FeFET) memory or ferroelectric tunnel junction (ferroelectric tunneling junction, FTJ) memory. The ferroelectric memory provided in the embodiment of the present application can be applied to various electronic devices with storage functions, for example, can be applied to electronic devices such as mobile phones, tablet computers, desktop computers, smart wearable devices, vehicle-mounted devices, servers, processors, etc.

[0064] In order to make the purpose, technical solutions and advantages of this application clearer, this application will be further described in detail below with reference to the accompanying drawings.

[0065] It should be noted that the same reference numerals in the drawings of this application represent the same or similar structures, and thus their repeated description will be omitted. The words expressing positions and directions described in this application are all explained using the drawings as examples, but they can be modified as needed, and such modifications are included in the scope of protection of this application. The drawings of this application are only for illustrating relative positional relationships and do not represent true proportions.

[0066] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of this application and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0067] FIG1 is a schematic structural diagram of a memory cell provided in an embodiment of the present application. As shown in FIG1 , the memory cell provided in an embodiment of the present application may include: a first electrode 11, a second electrode 12, and a ferroelectric layer 13, wherein the ferroelectric layer 13 is located between the first electrode 11 and the second electrode 12. The oxygen vacancy concentration in the ferroelectric layer 13 is distributed in a gradient along a first direction F1. The first direction F1 is the direction from the first electrode 11 to the second electrode 12, and the first direction F1 may be the vertically upward direction shown in FIG1 , or may be the vertically downward direction. In the embodiment of the present application, the oxygen vacancy concentration in the ferroelectric layer 13 is distributed in a gradient along the first direction F1, which can be understood as: the oxygen vacancies in the ferroelectric layer 13 have a concentration difference along the first direction F1. For example, in Figure 1, white circles represent oxygen vacancies, and black circles represent oxygen atoms. The ferroelectric layer 13 has more oxygen vacancies near the second electrode 12, and the oxygen vacancy concentration is higher. The ferroelectric layer 13 has more oxygen atoms near the first electrode 11, and the oxygen vacancy concentration is lower. The oxygen vacancies in the ferroelectric layer 13 have a concentration difference in the first direction F1, and the oxygen vacancy concentration is gradient distributed in the first direction F1.

[0068] The memory cell in the embodiment of the present application may be a hafnium oxide-based ferroelectric memory cell, i.e., the ferroelectric layer 13 may include a hafnium oxide material. For example, the ferroelectric layer 13 may include a zirconium-doped hafnium oxide (HfxZr1-xO, HZO) material. Of course, in some cases, the memory cell in the embodiment of the present application may also be a ferroelectric memory cell including other ferroelectric materials.

[0069] Figure 2 is a schematic diagram comparing the relationship between the oxygen vacancy concentration distribution and the polarization orientation of the ferroelectric domain. (1) in Figure 2 is a schematic diagram of the polarization orientation of the ferroelectric domain, and (2) in Figure 2 is a schematic diagram of the concentration distribution of oxygen vacancies. As shown in Figure 2, the two sides of the dotted line in Figure 2 are different ferroelectric domains. From (1) in Figure 2, it can be seen that the polarization orientation P within the same ferroelectric domain is basically the same, and the polarization orientation P of different ferroelectric domains is random. From (2) in Figure 2, it can be seen that the oxygen vacancy concentration is distributed in a gradient from high to low (as shown by the fill color from dark to light in the figure), and the difference in oxygen vacancy concentration can form a built-in electric field E. Comparing (1) and (2) in Figure 2, it can be clearly seen that although the polarization orientation P and oxygen vacancy concentration distribution of different ferroelectric domains have a certain degree of randomness, the distribution of polarization orientation P of different ferroelectric domains is basically consistent with the direction of the built-in electric field E in different ferroelectric domains. The built-in electric field E has a strong template effect on the polarization orientation P. Therefore, the concentration distribution of oxygen vacancies in the ferroelectric phase can directly affect the polarization orientation P.

[0070] In conjunction with Figures 1 and 2 , since the oxygen vacancy concentration distribution in the ferroelectric layer 13 is correlated with the polarization orientation P of the ferroelectric phase, the built-in electric field E formed by the difference in oxygen vacancy concentration has a strong template effect on the polarization orientation P. Therefore, in the embodiment of the present application, the oxygen vacancy concentration in the ferroelectric layer 13 is set to be distributed in a gradient in the first direction F1, which can form a built-in electric field E that is consistent with the first direction F1. The formed built-in electric field E can directly affect the polarization orientation P of the ferroelectric phase, causing the polarization orientation P of the ferroelectric phase to also be distributed along the first direction F1, thereby significantly reducing the randomness of the polarization orientation P, improving the uniformity of the polarization orientation P of the ferroelectric phase in the ferroelectric layer 13, and further improving the performance of the ferroelectric memory.

[0071] The above introduces the basic structure of the storage unit in the embodiment of the present application. The specific embodiment of the storage unit in the embodiment of the present application is described in detail below with reference to the accompanying drawings.

[0072] Example 1:

[0073] FIG3 is another schematic structural diagram of a memory cell provided in an embodiment of the present application. As shown in FIG3 , in some embodiments of the present application, the first electrode 11 and the second electrode 12 may have different oxygen vacancy generation energies, and the oxygen vacancy concentration of the ferroelectric layer 13 at the first interface Q1 is different from the oxygen vacancy concentration at the second interface Q2. The first interface Q1 is the interface between the ferroelectric layer 13 and the first electrode 11, and the second interface Q2 is the interface between the ferroelectric layer 13 and the second electrode 12. By configuring the first electrode 11 and the second electrode 12 to have different oxygen vacancy generation energies, a difference in oxygen vacancy concentration can be formed in the ferroelectric layer 13 at the first interface Q1 and the second interface Q2, so that the oxygen vacancy concentration in the ferroelectric layer 13 is gradiently distributed in the first direction F1, thereby forming a uniform built-in electric field within the ferroelectric layer 13, thereby improving the uniformity of the polarization orientation of the ferroelectric phase in the ferroelectric layer 13 and enhancing the performance of the ferroelectric memory.

[0074] In a specific implementation, the storage unit in the embodiment of the present application may further include: a substrate 10, which may serve to carry a first electrode 11, a second electrode 12 and a ferroelectric layer 13. In the various drawings of the present application, the first electrode 11 is located between the substrate 10 and the ferroelectric layer 13, and the second electrode 12 is located on the side of the ferroelectric layer 13 away from the substrate 10. In some cases, the first electrode 11 and the second electrode 12 may be interchangeable and may be arranged according to actual needs.

[0075] During the manufacturing process, the first electrode 11 and the second electrode 12 can be fabricated using different chemical ratios, forming dangling bonds capable of oxygen absorption in one of the electrodes, thereby giving the first electrode 11 and the second electrode 12 different oxygen vacancy generation energies. Taking the formation of dangling bonds capable of oxygen absorption in the second electrode 12 as an example, after the first electrode 11, the ferroelectric layer 13, and the second electrode 12 are sequentially formed on the substrate 10, the ferroelectric layer 13 is subjected to an annealing process to crystallize the ferroelectric material in the ferroelectric layer 13. For example, a rapid thermal annealing process can be used to treat the ferroelectric layer 13. During the annealing process, the dangling bonds in the second electrode 12 can absorb oxygen atoms in the ferroelectric layer 13, resulting in a high number of oxygen vacancies in the ferroelectric layer 13 at the second interface Q2. Conversely, the first electrode 11 reduces the number of oxygen vacancies in the ferroelectric layer 13 at the first interface Q1. Consequently, a difference in oxygen vacancy concentration can be formed in the ferroelectric layer 13 between the first interface Q1 and the second interface Q2, thereby forming a uniform built-in electric field in the ferroelectric layer 13.

[0076] In one possible implementation, the first electrode 11 and the second electrode 12 may both include a first element and a second element, where the first element is a metal element and the second element is a non-metal element. The atomic count ratio of the first element to the second element in the first electrode 11 is different from the atomic count ratio of the first element to the second element in the second electrode 12. This allows the oxygen vacancy generation energies of the first electrode 11 and the second electrode 12 to differ. During the fabrication process, the first electrode 11 and the second electrode 12 may be fabricated using different chemical ratios to achieve different atomic count ratios of the first element to the second element in the fabricated first and second electrodes 11 and 12. For example, the first element may be Ti, Ta, Al, or the like, and the second element may be N, P, As, or the like. Optionally, the first electrode 11 may include one or a combination of TiN, TaN, TiAlN, TiSiN, TaAlN, and TiAlCN, and the second electrode 12 may include one or a combination of TiN, TaN, TiAlN, TiSiN, TaAlN, and TiAlCN.

[0077] In one embodiment, the materials of the first electrode 11 and the second electrode 12 can be the same. Continuing with FIG. 3 , taking the example of both the first electrode 11 and the second electrode 12 being made of TiN, the first element can be Ti and the second element can be N. When fabricating the first electrode 11 and the second electrode 12, the chemical ratios of the Ti and N elements can be different. For example, when fabricating the first electrode 11, the atomic count ratio of the Ti and N elements can be lower than a target ratio, while when fabricating the second electrode 12, the atomic count ratio of the Ti and N elements can be higher than the target ratio. The target ratio can be the ratio at which Ti and N elements react completely. In other words, the first electrode 11 contains more N, while the second electrode 12 contains more Ti. This results in Ti dangling bonds in the fabricated second electrode 12. During the subsequent annealing process of the ferroelectric layer 13, these Ti dangling bonds absorb oxygen from the ferroelectric layer 13, resulting in a high oxygen vacancy content in the ferroelectric layer 13 at the second interface Q2. On the contrary, the first electrode 11 manufactured contains more N elements, which reduces the oxygen vacancy content of the ferroelectric layer 13 at the first interface Q1, thereby making the oxygen vacancy concentrations of the ferroelectric layer 13 different at the first interface Q1 and the second interface Q2.

[0078] FIG4 is a schematic diagram of the chemical ratio of the first electrode and the second electrode in an embodiment of the present application. For example, as shown in (1) in FIG4 , the first electrode 11 and the second electrode 12 can both include TiN material, that is, the first element can be Ti, and the second element can be N. During the manufacturing process, when manufacturing the first electrode 11, the atomic count ratio of the Ti element to the N element can be lower than the target ratio, and when manufacturing the second electrode 12, the atomic count ratio of the Ti element to the N element can be approximately the target ratio. In other words, there are more N elements in the first electrode 11, and there are basically no extra Ti elements and N elements in the second electrode 12. In this way, the oxygen vacancy content of the ferroelectric layer 13 at the second interface Q2 can also be higher. As shown in (2) in FIG4 , the first electrode 11 and the second electrode 12 can both include TaN material, that is, the first element can be Ta, and the second element can be N. During the manufacturing process, the atomic count ratio of the Ta element to the N element when manufacturing the first electrode 11 is lower than the atomic count ratio of the Ta element to the N element when manufacturing the second electrode 12. That is, the N element in the first electrode 11 is more, and the Ta element in the second electrode 12 is more. In this way, the oxygen vacancy content of the manufactured ferroelectric layer 13 at the second interface Q2 can be higher. As shown in (3) in Figure 4, the first electrode 11 and the second electrode 12 can both include TaAlN material, that is, the first element can be Al, and the second element can be N. During the manufacturing process, the atomic count ratio of the Al element to the N element when manufacturing the first electrode 11 is lower than the atomic count ratio of the Al element to the N element when manufacturing the second electrode 12. In this way, the oxygen vacancy content of the manufactured ferroelectric layer 13 at the second interface Q2 can be higher.

[0079] In another embodiment, the materials of the first electrode 11 and the second electrode 12 may be different. For example, the first electrode 11 may include a TiN material, and the second electrode 12 may include a TaN material; or the first electrode 11 may include a TiAlN material, and the second electrode 12 may include a TiN material. In specific implementations, the materials of the first electrode 11 and the second electrode 12 may be set according to actual needs, and examples are not given here one by one.

[0080] In conjunction with FIG3 and FIG4 , examples are provided above of specific implementations of using different chemical ratios to manufacture the first electrode 11 and the second electrode 12. In specific implementations, the chemical ratios of the first electrode 11 and the second electrode 12 can be appropriately set based on the specific materials of the first electrode 11 and the second electrode 12, and examples are not given here one by one. In the embodiments shown in FIG3 and FIG4 , the oxygen vacancy concentration of the ferroelectric layer 13 at the first interface Q1 is lower than the oxygen vacancy concentration at the second interface Q2. In specific implementations, the oxygen vacancy concentration of the ferroelectric layer 13 at the first interface Q1 can also be higher than the oxygen vacancy concentration at the second interface Q2, as long as the oxygen vacancy concentration in the ferroelectric layer 13 can be distributed in a gradient along the first direction F1.

[0081] In the above embodiment, the first electrode and the second electrode both include compound materials as an example. In another possible implementation, the first electrode may include a metal material, and the second electrode may include a compound material. Figure 5 is another schematic diagram of the chemical ratio of the first electrode and the second electrode in the embodiment of the present application. As shown in Figure 5, the first electrode 11 may include: a metal material. For example, the first electrode 11 may include metal W. Of course, the first electrode 11 may also include other metal materials such as Al and Cu. The second electrode 12 may include: a first element and a second element, the first element being a metal element and the second element being a non-metallic element. For example, the first element may be Ti, and the second element may be N. Of course, the first element may also include other metal elements such as Ta and Al, and the second element may also include other non-metallic materials such as P and As.

[0082] As shown in (1) in FIG5 , the second electrode 12 may have dangling bonds of the first element. During the manufacturing process, when the second electrode 12 is manufactured, the atomic count ratio of the first element to the second element is greater than the target ratio, so that the content of the first element in the manufactured second electrode 12 is relatively high. The second electrode 12 has dangling bonds of the first element. During the annealing process, the dangling bonds of the first element can absorb oxygen in the ferroelectric layer 13, so that the oxygen vacancy concentration of the ferroelectric layer 13 at the second interface Q2 is higher than the oxygen vacancy concentration at the first interface Q1. For example, in the figure, the second electrode 12 includes TiN material as an example. During the manufacturing process of the second electrode 12, the atomic count ratio of the Ti element to the N element can be higher than the target ratio, so that the second electrode 12 has Ti dangling bonds. During the annealing process, the Ti dangling bonds can absorb oxygen in the ferroelectric layer 13, so that the oxygen vacancy concentration of the ferroelectric layer 13 at the second interface Q2 is relatively high.

[0083] As shown in (2) of FIG. 5 , the second electrode 12 may have dangling bonds of the second element. During the manufacturing process, when manufacturing the second electrode 12, the atomic count ratio of the first element to the second element is less than the target ratio, so that the content of the second element in the manufactured second electrode 12 is relatively high. The second electrode 12 has dangling bonds of the second element. During the annealing process, the dangling bonds of the second element will reduce the oxygen vacancy concentration, so that the oxygen vacancy concentration of the ferroelectric layer 13 at the second interface Q2 is lower than the oxygen vacancy concentration at the first cross section Q1. Still taking the second electrode 12 comprising TiN material as an example, during the manufacturing process of the second electrode 12, the atomic count ratio of the Ti element to the N element can be lower than the target ratio, so that the manufactured second electrode 12 has N dangling bonds. During the annealing process, the N dangling bonds will reduce the oxygen vacancy concentration, so that the oxygen vacancy concentration of the ferroelectric layer 13 at the second interface Q2 is relatively low.

[0084] 5 takes the example that the first electrode 11 includes a metal material and the second electrode 12 includes a compound material. In a specific implementation, the first electrode 11 may also be configured to include a compound material and the second electrode 12 may be configured to include a metal material.

[0085] Example 2:

[0086] Figure 6a is another structural schematic diagram of a storage unit provided in an embodiment of the present application. As shown in Figure 6a, in some other embodiments of the present application, the ferroelectric layer 13 may include: at least two stacked layers of ferroelectric films 131, and the oxygen vacancy concentrations in two adjacent layers of ferroelectric films 131 are different. For example, in Figure 6a, the ferroelectric layer 13 includes four layers of ferroelectric films 131, and the oxygen vacancy concentrations of each ferroelectric film 131 in the ferroelectric layer 13 are distributed in a high-low pattern along the first direction F1 (taking the downward direction F1 as an example). In actual applications, the number of layers of ferroelectric films 131 in the ferroelectric layer 13 and the distribution pattern of oxygen vacancy concentration can be set according to actual needs. In the embodiment of the present application, by setting up at least two stacked layers of ferroelectric films 131, and the oxygen vacancy concentrations in the two adjacent layers of ferroelectric films 131 are different, the oxygen vacancy concentration in the ferroelectric layer 13 can be made to be gradient distributed (or called chain distribution), so that a uniform built-in electric field E can be formed in the ferroelectric layer 13, and the direction of the built-in electric field E is consistent with the first direction F1, thereby inducing the polarization direction of the ferroelectric phase to be arranged along the first direction F1.

[0087] FIG6b is a comparative example of a memory cell in an embodiment of the present application. As shown in FIG6b, when the oxygen vacancy concentration in the ferroelectric layer 13 is uniform, the built-in electric field E formed in the ferroelectric layer 13 is randomly distributed, and the polarization orientation of the ferroelectric phase is also randomly distributed. Comparing FIG6a and FIG6b, it can be seen that compared to the technical solution in which the oxygen vacancy concentration in the ferroelectric layer 13 is uniform, in the embodiment of the present application, by providing at least two stacked ferroelectric thin films 131, and the oxygen vacancy concentrations in the two adjacent ferroelectric thin films 131 are different, the oxygen vacancy concentration in the ferroelectric layer 13 can be made to form a gradient distribution along the first direction F1. In turn, the built-in electric field E formed by the difference in oxygen vacancy concentration is more uniformly distributed along the first direction F1, thereby inducing the polarization direction of the ferroelectric phase to be arranged along the first direction F1.

[0088] During the manufacturing process, an atomic layer deposition (ALD) process can be used to form each ferroelectric thin film 131 in the ferroelectric layer 13. During the deposition of each ferroelectric thin film 131, the oxygen dose (O-dose) can be controlled to form ferroelectric thin films 131 with different oxygen vacancy concentrations. Specifically, the oxygen dose can be adjusted by controlling parameters such as the residence time, concentration, or flow rate of the oxygen element. For example, when the ferroelectric layer 13 includes a zirconium-doped hafnium oxide (HfxZr1-xO, HZO) material, the oxygen vacancy concentration in the ferroelectric thin film 131 can be controlled by adjusting parameters such as the residence time, concentration, or flow rate of the oxygen (O), zirconium (Zr), and hafnium (Hf) elements.

[0089] In the embodiment of the present application, the thickness of the ferroelectric layer 13 can be in the range of 5 nm to 15 nm. For example, the thickness of the ferroelectric layer 13 can be 5 nm, 8 nm, 10 nm, 12 nm, or 15 nm. The thickness of the single-layer ferroelectric thin film 131 can be in the range of 0.5 nm to 2 nm. For example, the thickness of the ferroelectric thin film 131 can be 0.5 nm, 1 nm, 1.5 nm, or 2 nm.

[0090] FIG7 is a schematic diagram of the structure of the ferroelectric layer in an embodiment of the present application, (1) in FIG7 is a schematic diagram of the distribution pattern of the oxygen vacancy concentration of each ferroelectric thin film in the ferroelectric layer, and (2) in FIG7 is a schematic diagram of the built-in electric field strength at different positions in the ferroelectric layer. In the figure, the vertical axis E represents the built-in electric field strength, and the horizontal axis D represents the distance from the lower surface of the ferroelectric layer (the surface of the ferroelectric layer close to the first electrode). As shown in FIG7 , in one possible implementation, the oxygen vacancy concentration of each ferroelectric thin film 131 in the ferroelectric layer 13 can be distributed in a high-low alternating pattern in the first direction F1. For example, in FIG7 , the oxygen vacancy concentration of each ferroelectric thin film 131 in the ferroelectric layer 13 can be distributed in a high-low alternating pattern in the first direction F1 (taking the direction upward along the first direction F1 as an example). Figure 8 is another structural schematic diagram of the ferroelectric layer in an embodiment of the present application, (1) in Figure 8 is a schematic diagram of the distribution pattern of the oxygen vacancy concentration of each ferroelectric film in the ferroelectric layer, and (2) in Figure 8 is a schematic diagram of the built-in electric field strength at different positions in the ferroelectric layer. In the figure, the vertical axis E represents the built-in electric field strength, and the horizontal axis D represents the distance from the lower surface of the ferroelectric layer (the surface of the ferroelectric layer close to the first electrode). As shown in Figure 8, the oxygen vacancy concentration of each ferroelectric film 131 in the ferroelectric layer 13 in the first direction F1 (taking the upward direction F1 as an example) can also be distributed in a low-high-low-high-low-high pattern.

[0091] FIG9 is another structural schematic diagram of the ferroelectric layer in an embodiment of the present application. (1) in FIG9 is a schematic diagram of the distribution pattern of the oxygen vacancy concentration of each ferroelectric thin film in the ferroelectric layer. (2) in FIG9 is a schematic diagram of the built-in electric field strength at different positions in the ferroelectric layer. In the figure, the vertical axis E represents the built-in electric field strength, and the horizontal axis D represents the distance from the lower surface of the ferroelectric layer (the surface of the ferroelectric layer close to the first electrode). As shown in FIG9, the oxygen vacancy concentration of each ferroelectric thin film 131 in the ferroelectric layer 13 can be distributed in a regular pattern of first increasing and then decreasing in the first direction F1 (taking the direction upward along the first direction F1 as an example). Alternatively, the oxygen vacancy concentration of each ferroelectric thin film 131 in the ferroelectric layer 13 can also be distributed in a regular pattern of first decreasing and then increasing in the first direction F1.

[0092] The above, combined with Figures 7 to 9, introduces the distribution rules of oxygen vacancy concentration of each ferroelectric film 131 in several ferroelectric layers 13. In practical applications, the number of layers of ferroelectric films 131 in the ferroelectric layer 13 and the distribution rules of oxygen vacancy concentration can be set according to actual needs. Examples will not be given one by one here.

[0093] Based on the same technical concept, the present invention also provides a method for manufacturing a memory cell. FIG10 is a flow chart of the method for manufacturing a memory cell provided by the present invention. As shown in FIG10 , the method for manufacturing a memory cell provided by the present invention may include:

[0094] S101, forming a first electrode on a substrate;

[0095] S102, depositing a ferroelectric layer on the first electrode;

[0096] S103, forming a second electrode on the ferroelectric layer; the first electrode and the second electrode have different oxygen vacancy generation energies;

[0097] S104 , treating the ferroelectric layer with an annealing process to move oxygen elements in the ferroelectric layer along a first direction, so that the oxygen vacancy concentration in the ferroelectric layer is distributed in a gradient in the first direction, where the first direction is from the first electrode to the second electrode.

[0098] In an embodiment of the present application, by producing a first electrode and a second electrode with different oxygen vacancy generation energies, during the subsequent annealing process, the electrode with higher oxygen vacancy generation energy can absorb oxygen elements in the ferroelectric layer, causing the oxygen elements in the ferroelectric layer to move along the first direction, so that the oxygen vacancy concentration in the ferroelectric layer is gradiently distributed in the first direction, thereby forming a uniform built-in electric field inside the ferroelectric layer, thereby improving the uniformity of the polarization orientation of the ferroelectric phase in the ferroelectric layer and improving the performance of the ferroelectric memory.

[0099] The memory cell in the embodiment of the present application may be a hafnium oxide-based ferroelectric memory cell. In step S102, the ferroelectric layer may be made of a hafnium oxide material. For example, the ferroelectric layer may be made of a zirconium-doped hafnium oxide (HfxZr1-xO, HZO) material. Of course, in some cases, other ferroelectric materials may also be used to make the ferroelectric layer. In one possible implementation, the ferroelectric layer may be made using an atomic layer deposition (ALD) process.

[0100] Referring to Figure 3, in steps S101 and S103, the first electrode 11 and the second electrode 12 can be fabricated using different chemical ratios, forming dangling bonds capable of absorbing oxygen in one of the electrodes. This allows the first electrode 11 and the second electrode 12 to have different oxygen vacancy generation energies. Taking the formation of dangling bonds capable of absorbing oxygen in the second electrode 12 as an example, in step S104, the ferroelectric layer 13 is treated with an annealing process to crystallize the ferroelectric material in the ferroelectric layer 13. For example, a rapid thermal annealing process can be used to treat the ferroelectric layer 13. During the annealing process, the dangling bonds in the second electrode 12 can absorb oxygen atoms in the ferroelectric layer 13, resulting in a high number of oxygen vacancies in the ferroelectric layer 13 at the second interface Q2. Conversely, the first electrode 11 reduces the number of oxygen vacancies in the ferroelectric layer 13 at the first interface Q1. Consequently, a difference in oxygen vacancy concentrations can be formed in the ferroelectric layer 13 between the first interface Q1 and the second interface Q2, thereby forming a uniform built-in electric field in the ferroelectric layer 13.

[0101] In one possible implementation, the first electrode and the second electrode may both include compound materials. Specifically, the first electrode 11 and the second electrode 12 may both include: a first element and a second element, the first element being a metal element and the second element being a non-metal element. The atomic count ratio of the first element to the second element in the first electrode 11 is different from the atomic count ratio of the first element to the second element in the second electrode 12. In this way, the oxygen vacancy generation energy of the first electrode 11 and the second electrode 12 can be made different. In the above steps S101 and S103, different chemical ratios can be used to manufacture the first electrode 11 and the second electrode 12, so that the atomic count ratios of the first element to the second element in the manufactured first electrode 11 and the second electrode 12 are different. Exemplarily, the first element may be an element such as Ti, Ta, Al, and the second element may be an element such as N, P, As, etc. Optionally, the first electrode 11 may include one or a combination of TiN, TaN, TiAlN, TiSiN, TaAlN, and TiAlCN, and the second electrode 12 may include one or a combination of TiN, TaN, TiAlN, TiSiN, TaAlN, and TiAlCN.

[0102] In one embodiment, the materials of the first electrode 11 and the second electrode 12 can be the same. For example, the first electrode 11 and the second electrode 12 can both include TiN material, or the first electrode 11 and the second electrode 12 can both include TaN material. In another embodiment, the materials of the first electrode 11 and the second electrode 12 can also be different. For example, the first electrode 11 can include TiN material, and the second electrode 12 can include TaN material; or the first electrode 11 can include TiAlN material, and the second electrode 12 can include TiN material. In specific implementations, the materials of the first electrode 11 and the second electrode 12 can be set according to actual needs, and examples are not given here one by one.

[0103] In another possible implementation, the first electrode may include a metal material, and the second electrode may include a compound material. For example, the first electrode 11 may include a metal material such as W, Al, Cu, and the second electrode 12 may include: a first element and a second element, the first element being a metal element and the second element being a non-metal element. Exemplarily, the first element may be other metal elements such as Ti, Ta, Al, and the second element may also include other non-metal materials such as N, P, As. The second electrode may have dangling bonds of the first element; alternatively, the second electrode may have dangling bonds of the second element. In this way, the oxygen vacancy concentrations of the ferroelectric layer at the first interface and the second interface may be different.

[0104] The storage unit in the first embodiment above can be manufactured by the manufacturing method shown in FIG10 . The specific implementation of the manufacturing method shown in FIG10 can refer to the specific implementation of the storage unit in the first embodiment above, and the repeated parts will not be repeated.

[0105] Based on the same technical concept, the present invention also provides a method for manufacturing a memory cell. FIG11 is a flow chart of another method for manufacturing a memory cell provided by the present invention. As shown in FIG11 , the method for manufacturing a memory cell provided by the present invention may include:

[0106] S201, forming a first electrode on a substrate;

[0107] S202, sequentially depositing at least two ferroelectric thin films on the first electrode, and making the oxygen vacancy concentrations in the two adjacent ferroelectric thin films different;

[0108] S203 , forming a second electrode on at least two ferroelectric thin films.

[0109] In an embodiment of the present application, by depositing at least two layers of ferroelectric films in sequence on the first electrode and making the oxygen vacancy concentrations in the two adjacent ferroelectric films different, the oxygen vacancy concentration in the ferroelectric layer can be distributed in a gradient, thereby forming a uniform built-in electric field in the ferroelectric layer. The direction of the built-in electric field is consistent with the first direction (the direction from the first electrode to the second electrode), thereby inducing the polarization direction of the ferroelectric phase to be arranged along the first direction.

[0110] The memory cell in the embodiment of the present application may be a hafnium oxide-based ferroelectric memory cell. In step S202, each ferroelectric thin film in the ferroelectric layer may be made of a hafnium oxide material. For example, the ferroelectric thin film may be made of zirconium-doped hafnium oxide (HfxZr1-xO, HZO). Of course, in some cases, other ferroelectric materials may also be used to make the ferroelectric thin film.

[0111] 6a, in step S202, an atomic layer deposition (ALD) process may be used to form each ferroelectric thin film 131. During the deposition of each ferroelectric thin film 131, the oxygen dose (O-dose) may be controlled to form ferroelectric thin films 131 having different oxygen vacancy concentrations. Specifically, the oxygen dose may be adjusted by controlling parameters such as the residence time, concentration, or flow rate of the oxygen. For example, when the ferroelectric layer 13 comprises zirconium-doped hafnium oxide (HfxZr1-xO, HZO) material, the oxygen vacancy concentration in the ferroelectric thin film 131 may be controlled by adjusting parameters such as the residence time, concentration, or flow rate of the oxygen (O), zirconium (Zr), and hafnium (Hf) elements.

[0112] Specifically, in step S202, the thickness of the deposited single-layer ferroelectric thin film 131 can be in the range of 0.5 nm to 2 nm. For example, the thickness of the ferroelectric thin film 131 can be 0.5 nm, 1 nm, 1.5 nm, or 2 nm. The total thickness of the ferroelectric layer 13 obtained by stacking the ferroelectric thin films 131 can be in the range of 5 nm to 15 nm. For example, the total thickness of the ferroelectric layer 13 can be 5 nm, 8 nm, 10 nm, 12 nm, or 15 nm.

[0113] In one possible implementation, as shown in Figures 7 and 8 , the oxygen vacancy concentrations of the ferroelectric thin films 131 in the ferroelectric layer 13 can be distributed in an alternating pattern of high and low along the first direction F1. Referring to Figure 7 , the oxygen vacancy concentrations of the ferroelectric thin films 131 in the ferroelectric layer 13 can be distributed in an alternating pattern of high and low along the first direction F1 (for example, extending upward along the first direction F1). Alternatively, referring to Figure 8 , the oxygen vacancy concentrations of the ferroelectric thin films 131 in the ferroelectric layer 13 can be distributed in an alternating pattern of low and high, then low and high, along the first direction F1 (for example, extending upward along the first direction F1). In another possible implementation, referring to Figure 9 , the oxygen vacancy concentrations of the ferroelectric thin films 131 in the ferroelectric layer 13 can be distributed in an alternating pattern of first increasing and then decreasing along the first direction F1 (for example, extending upward along the first direction F1). Alternatively, the oxygen vacancy concentrations of the ferroelectric thin films 131 in the ferroelectric layer 13 can be distributed in an alternating pattern of first decreasing and then increasing along the first direction F1. In practical applications, the number of layers of the ferroelectric thin film 131 in the ferroelectric layer 13 and the distribution pattern of the oxygen vacancy concentration can be set according to actual needs, and examples are not given here one by one.

[0114] The storage unit in the second embodiment above can be manufactured by the manufacturing method shown in FIG11 . The specific implementation of the manufacturing method shown in FIG11 can refer to the specific implementation of the storage unit in the second embodiment above, and the repeated parts will not be repeated.

[0115] In summary, in the embodiments of the present application, by setting the oxygen vacancy concentration in the ferroelectric layer to be distributed in a gradient in a first direction (the first direction is the direction from the first electrode to the second electrode), the texture orientation of the ferroelectric domain can be changed, the uniformity of the polarization orientation of the ferroelectric phase in the ferroelectric layer can be improved, and the performance of the ferroelectric memory can be improved. For example, the coercive electric field (Ec) of the ferroelectric memory can be reduced, the remanent polarization (Pr) can be increased, and the uniformity of the performance of small-sized ferroelectric memory can be improved. In addition, the technical solution in the embodiments of the present application does not rely on specific electrode materials or the thickness of the ferroelectric film, has a wide range of applications, and has low process costs.

[0116] Based on the same technical concept, the embodiment of the present application also provides a ferroelectric memory. The ferroelectric memory in the embodiment of the present application can be a hafnium oxide-based ferroelectric memory. Of course, the ferroelectric memory in the embodiment of the present application can also be a ferroelectric memory including other ferroelectric materials. The ferroelectric memory in the embodiment of the present application can be various types of memory such as ferroelectric random access memory (FeRAM or FRAM), ferroelectric field effect transistor (FeFET) memory or ferroelectric tunnel junction (FTJ) memory.

[0117] The ferroelectric memory provided by the embodiment of the present application may include: a controller and any of the above-mentioned memory cells, wherein the memory cells are electrically connected to the controller. Since the polarization orientation of the ferroelectric phase in the above-mentioned memory cells is highly uniform, the ferroelectric memory including the above-mentioned memory cells has better performance.

[0118] Based on the same technical concept, an embodiment of the present application also provides an electronic device. The electronic device in the embodiment of the present application can be any electronic device with a storage function. For example, the electronic device in the embodiment of the present application can be a mobile phone, a tablet computer, a desktop computer, a smart wearable device, a vehicle-mounted device, a server, a processor, etc.

[0119] The electronic device provided by the embodiment of the present application may include: a circuit board and any of the above ferroelectric memories, wherein the ferroelectric memory is electrically connected to the circuit board. Due to the high performance of the above ferroelectric memories, the electronic device including the above ferroelectric memories also has good performance.

[0120] Although the preferred embodiments of the present application have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present application.

[0121] Obviously, those skilled in the art may make various changes and modifications to the embodiments of the present application without departing from the spirit and scope of the embodiments of the present application. Thus, if these modifications and variations of the embodiments of the present application fall within the scope of the claims of the present application and their equivalents, the present application also intends to include such modifications and variations.

Claims

1. A storage unit, characterized in that, Comprising: A first electrode, a second electrode, and a ferroelectric layer; The ferroelectric layer is located between the first electrode and the second electrode; The oxygen vacancy concentration in the ferroelectric layer is distributed in a gradient in a first direction, and the first direction is the direction from the first electrode pointing to the second electrode.

2. The memory cell according to claim 1, wherein The first electrode and the second electrode have different oxygen vacancy formation energies; The oxygen vacancy concentration at a first interface of the ferroelectric layer is different from that at a second interface; wherein, the first interface is the interface where the ferroelectric layer contacts the first electrode, and the second interface is the interface where the ferroelectric layer contacts the second electrode.

3. The memory cell according to claim 1 or 2, characterized in that, Both the first electrode and the second electrode comprise: a first element and a second element, the first element is a metal element, and the second element is a non-metal element; The atomic count ratio of the first element to the second element in the first electrode is different from that of the first element to the second element in the second electrode.

4. The memory cell according to claim 3, characterized in that, The first electrode comprises: one or a combination of TiN, TaN, TiAlN, TiSiN, TaAlN, TiAlCN; The second electrode comprises: one or a combination of TiN, TaN, TiAlN, TiSiN, TaAlN, TiAlCN.

5. The memory cell according to claim 1 or 2, characterized in that, The first electrode comprises: a metallic material; The second electrode comprises: a first element and a second element, the first element is a metal element, and the second element is a non-metal element; The second electrode has dangling bonds of the first element, or the second electrode has dangling bonds of the second element.

6. The memory cell according to any one of claims 1 to 5, characterized in that, The ferroelectric layer comprises: at least two ferroelectric thin films stacked; The oxygen vacancy concentrations in adjacent two ferroelectric thin films are different.

7. The memory cell according to claim 6, wherein The oxygen vacancy concentrations of the respective ferroelectric thin films in the ferroelectric layer are distributed in an alternating high and low pattern in the first direction.

8. The memory cell according to claim 6, wherein The oxygen vacancy concentrations of the respective ferroelectric thin films in the ferroelectric layer are distributed regularly in the first direction, first increasing and then decreasing or first decreasing and then increasing.

9. A ferroelectric memory, characterized in that, Comprising: A controller and a storage unit as described in any one of claims 1 to 8, the storage unit being electrically connected to the controller.

10. An electronic device, characterized in that, Comprising: A circuit board and a ferroelectric memory as described in claim 9, the ferroelectric memory being electrically connected to the circuit board.

11. A manufacturing method of a memory cell, characterized in that, Comprising: Forming a first electrode on a substrate; Depositing a ferroelectric layer on the first electrode; Forming a second electrode on the ferroelectric layer; The first electrode and the second electrode have different oxygen vacancy formation energies; Using an annealing process to process the ferroelectric layer so that oxygen elements in the ferroelectric layer move in a first direction, so that the oxygen vacancy concentration in the ferroelectric layer is distributed in a gradient in the first direction, and the first direction is the direction from the first electrode pointing to the second electrode.

12. A manufacturing method of a memory cell, characterized in that, Comprising: Forming a first electrode on the substrate; Sequentially depositing at least two ferroelectric thin films on the first electrode and making the oxygen vacancy concentrations in adjacent two ferroelectric thin films different; Forming a second electrode on the at least two ferroelectric thin films.

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