Structure and preparation method of ferroelectric thin film capacitor

Abstract

The embodiment of the present application provides a ferroelectric thin film capacitor and a preparation method of the ferroelectric thin film capacitor, the structure of the ferroelectric storage capacitor provided by the present application comprises: a first metal electrode; a second metal electrode; a ferroelectric layer, which is arranged between the first metal electrode and the second metal electrode; wherein the material of the ferroelectric layer is a zirconium-doped hafnium dioxide material, and the zirconium-doped hafnium dioxide material is doped with nitrogen elements, the ferroelectric thin film capacitor can passivate oxygen vacancies generated under the influence of high temperature in the process of thin film deposition by in-situ injection of nitrogen elements in the zirconium-doped hafnium dioxide ferroelectric layer; in addition, in the process of using the ferroelectric thin film capacitor, the electric defects can be reduced by filling oxygen vacancies in the ferroelectric layer, so that the ferroelectric thin film imprinting effect and the breakdown phenomenon caused by the accumulation of oxygen vacancies are improved, and the performance and service life of the ferroelectric thin film capacitor are improved.

Description

TECHNICAL FIELD

[0001] Embodiments of the present application relate to the technical field of semiconductor devices, and in particular to a structure of a ferroelectric thin film capacitor and a preparation method thereof. BACKGROUND

[0002] With the development of electronic technology, data storage technology has been rapidly improved. Ferroelectric random access memory (FRAM, also known as "ferroelectric memory") has been widely concerned due to its fast read and write speed, non-volatility and other characteristics. FRAM is a device that uses the unique non-volatile electrical properties of ferroelectric materials to save data. Hafnium zirconium oxide (HfZrOx) ferroelectric material has become a research direction due to its low crystallization temperature, high integration, and compatibility with CMOS process.

[0003] However, in the existing FRAM technology, the ferroelectric thin film capacitor used for storing data in the FRAM is usually formed by arranging a ferroelectric thin film between two metal electrodes, that is, a sandwich structure of "metal-ferroelectric layer-metal". In this structure, when the ferroelectric layer adopts a hafnium zirconium oxide ferroelectric thin film, under the action of an electric field, high temperature, etc., the hafnium zirconium oxide ferroelectric thin film is prone to oxidation with the metal, resulting in the generation of oxygen vacancies at the contact surface between the metal and the ferroelectric layer and inside the ferroelectric layer. Long-term accumulation of oxygen vacancies leads to problems such as polarization reversal voltage shift or breakdown of the hafnium zirconium oxide ferroelectric thin film. Therefore, when the hafnium zirconium oxide ferroelectric thin film is used in the FRAM, how to improve the stability of the ferroelectric thin film capacitor becomes a problem to be solved. SUMMARY

[0004] By adopting the structure and preparation method of the ferroelectric thin film capacitor shown in the present application, the performance and service life of the ferroelectric thin film capacitor can be improved.

[0005] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0006] In a first aspect, the embodiments of the present application provide a structure of a ferroelectric thin film capacitor, which comprises: a first metal electrode; a second metal electrode; a ferroelectric layer arranged between the first metal electrode and the second metal electrode; wherein the material of the ferroelectric layer is a hafnium zirconium oxide material, and the hafnium zirconium oxide material is doped with nitrogen elements.

[0007] The ferroelectric thin film capacitor provided by the embodiments of the present application can passivate oxygen vacancies generated by high temperature in a thin film deposition process by in-situ injection of nitrogen elements in a zirconium-doped hafnium dioxide ferroelectric layer. In addition, in the use of the ferroelectric thin film capacitor, the oxygen vacancies can be filled to reduce electrical defects in the ferroelectric layer, thereby improving the ferroelectric thin film imprint effect and breakdown phenomenon caused by the accumulation of oxygen vacancies, and improving the performance and service life of the ferroelectric thin film capacitor.

[0008] In a possible implementation, the first region of the ferroelectric layer close to the first metal electrode is doped with the nitrogen element at a higher concentration than the second region of the ferroelectric layer away from the first metal electrode.

[0009] In a possible implementation, the third region of the ferroelectric layer close to the second metal electrode is doped with the nitrogen element at a higher concentration than the second region.

[0010] Generally, the edge region of the ferroelectric layer in contact with the first metal electrode and the second metal electrode has a high oxygen vacancy concentration and a large number of oxygen ion dispersion; the region of the ferroelectric layer away from the metal electrode has a low oxygen vacancy concentration and a small number of oxygen ion dispersion. Therefore, in the embodiments of the present application, the region of the ferroelectric layer close to the first metal electrode and the second metal electrode is doped with a higher concentration of N element to fill the high-concentration oxygen vacancies, and the region of the ferroelectric layer away from the first metal electrode and the second metal electrode is doped with a lower concentration of N element to fill the low-concentration oxygen vacancies.

[0011] In a possible implementation, a fourth region is further arranged between the first region and the second region, and the fourth region is not doped with the nitrogen element.

[0012] In a possible implementation, a fifth region is further arranged between the second region and the third region, and the fifth region is not doped with the nitrogen element.

[0013] In a possible implementation, the material of the first metal electrode and the second metal electrode is titanium nitride.

[0014] In a second aspect, the embodiments of the present application provide a method for preparing a ferroelectric thin film capacitor, which comprises: preparing a first metal electrode by using an atomic deposition process; forming a ferroelectric layer on the first metal electrode, wherein the material of the ferroelectric layer is a zirconium-doped hafnium dioxide material, and the zirconium-doped hafnium dioxide material is doped with nitrogen elements; and forming a second metal electrode on the first metal electrode.

[0015] In a possible implementation, the forming of the ferroelectric layer on the first metal electrode comprises: depositing a first zirconium-doped hafnium oxide ferroelectric film on a surface of the first metal electrode, the first zirconium-doped hafnium oxide ferroelectric film being doped with a first concentration of nitrogen elements; depositing a second zirconium-doped hafnium oxide ferroelectric film on a surface of the first zirconium-doped hafnium oxide ferroelectric film, the first zirconium-doped hafnium oxide ferroelectric film being not doped with nitrogen elements; depositing a third zirconium-doped hafnium oxide ferroelectric film on a surface of the second zirconium-doped hafnium oxide ferroelectric film, the third zirconium-doped hafnium oxide ferroelectric film being doped with a second concentration of nitrogen elements; depositing a fourth zirconium-doped hafnium oxide ferroelectric film on a surface of the third zirconium-doped hafnium oxide ferroelectric film, the fourth zirconium-doped hafnium oxide ferroelectric film being not doped with nitrogen elements; and depositing a fifth zirconium-doped hafnium oxide ferroelectric film on a surface of the fourth zirconium-doped hafnium oxide ferroelectric film, the fifth zirconium-doped hafnium oxide ferroelectric film being doped with the first concentration of nitrogen elements.

[0016] In a possible implementation, the material of the first metal electrode and the second metal electrode is titanium nitride.

[0017] In a third aspect, an embodiment of the present application provides a ferroelectric memory, comprising a plurality of memory cells arranged in an array; each of the plurality of memory cells comprises a transistor and a ferroelectric film capacitor as described in the first aspect. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the description of the embodiments of the present application. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative labor based on these drawings.

[0019] Figures 1A-1B is a structure of a ferroelectric film capacitor in the prior art;

[0020] Figure 2 is a structure diagram of a ferroelectric film capacitor provided by an embodiment of the present application;

[0021] Figure 3 is a process flow diagram for preparing a ferroelectric film capacitor as shown in Figure 2 ;

[0022] Figure 4 is another structure diagram of a ferroelectric film capacitor provided by an embodiment of the present application;

[0023] Figure 5 is a process flow diagram for preparing a ferroelectric film capacitor as shown inFigure 4 A process flow diagram of a ferroelectric thin film capacitor is shown in FIG. 1.

[0024] Figure 6 FIG. 1 is a structural diagram of a ferroelectric memory according to an embodiment of the present application. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be clearly and completely described with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of protection of the present application.

[0026] The terms "first", "second", and similar terms used herein do not denote any order, quantity, or importance, but are used to distinguish different components. Similarly, the terms "one" or "a" or similar terms do not denote a quantity restriction, but denote the existence of at least one.

[0027] In the embodiments of the present application, the words "exemplary" or "for example" are used to mean example, instance, or illustration. Any embodiment or design presented as "exemplary" or "for example" in the embodiments of the present application should not be construed as preferred or advantageous over other embodiments or design solutions. Rather, the use of "exemplary" or "for example" is intended to present concepts in a particular manner. In the description of the embodiments of the present application, the meaning of "plurality" is two or more, unless otherwise specified.

[0028] Reference should be made to Figure 1A , Figure 1A FIG. 1 is a structural diagram of a ferroelectric thin film capacitor in the prior art according to an embodiment of the present application. In Figure 1A , the ferroelectric thin film capacitor includes two layers of metal and a ferroelectric layer disposed between the two layers of metal. The material of the two layers of metal is titanium nitride (TiN), and the material of the ferroelectric layer is hafnium oxide doped with zirconium. As shown in Figure 1A the ferroelectric thin film capacitor, under the action of an electric field, high temperature, etc., the titanium nitride material and the hafnium oxide doped with zirconium ferroelectric thin film undergo an oxidation reaction, in which the hafnium oxide doped with zirconium ferroelectric thin film acts as an oxygen ion donor, and the titanium nitride material acts as an oxygen ion acceptor. After the oxidation reaction, oxygen ion vacancies with positive charges are generated in the ferroelectric layer and on the surface where the metal layer contacts the ferroelectric layer. Long-term accumulation of oxygen vacancies causes the polarization reversal voltage of the hafnium oxide doped with zirconium ferroelectric thin film to shift or causes the ferroelectric thin film to break down, etc. Thus, the performance and service life of the ferroelectric thin film capacitor are affected, and in turn the performance of the FRAM prepared from the ferroelectric thin film capacitor is affected.

[0029] When the zirconium-doped hafnium oxide ferroelectric thin film is used in the ferroelectric thin film capacitor, in order to avoid the problems such as polarization reversal voltage offset or breakdown of the ferroelectric thin film, the industry further proposes to replace the materials of the upper and lower metal layers in contact with the ferroelectric layer with inert metals such as ruthenium (Ru) and platinum (Pt). When the inert metal is used as the upper and lower metal layers of the ferroelectric thin film capacitor, in the integrated process of forming the ferroelectric memory of the ferroelectric thin film capacitor, some processes need to etch the inert metal. However, due to the low reactivity of the inert metal, it is not easy to react with the cleaning gas, which may cause the inert metal to remain in the reaction chamber, causing metal contamination problems.

[0030] In addition, the industry further proposes the structure of the ferroelectric thin film capacitor as shown in Figure 1B In Figure 1B , the upper and lower metal layers in the ferroelectric thin film capacitor do not directly contact the zirconium-doped hafnium oxide ferroelectric layer, but a metal oxide layer is arranged between the metal layer and the zirconium-doped hafnium oxide ferroelectric layer as an overlayer between the metal layer and the ferroelectric layer. The metal oxide layer is titanium oxide (TiO2) as shown in Figure 1B When the metal layer is oxidized, the oxygen ions of the metal oxide layer react with the metal layer first, thereby slowing down the charge imbalance in the zirconium-doped hafnium oxide ferroelectric layer. However, the newly introduced metal oxide layer has a large difference in thermal expansion coefficient and crystallization temperature from the zirconium-doped hafnium oxide ferroelectric layer, which is easy to cause "mismatch strain" problems with the zirconium-doped hafnium oxide ferroelectric layer during the crystallization process, causing the lattice of the zirconium-doped hafnium oxide to be dislocated and more defects to be generated.

[0031] As can be seen from the prior art described above, the problem of oxygen vacancy accumulation of the zirconium-doped hafnium oxide ferroelectric thin film when the zirconium-doped hafnium oxide ferroelectric thin film is used in the ferroelectric thin film capacitor has not been effectively solved in the prior art. The ferroelectric thin film capacitor provided by the embodiments of the present application can passivate the oxygen vacancies generated by high temperature during thin film deposition by in-situ injection of nitrogen elements in the zirconium-doped hafnium oxide ferroelectric layer. In addition, during the use of the ferroelectric thin film capacitor, the electric defects can be reduced by filling the oxygen vacancies in the ferroelectric layer, thereby improving the imprint effect and breakdown phenomenon of the ferroelectric thin film caused by the accumulation of oxygen vacancies, and improving the performance and service life of the ferroelectric thin film capacitor. The ferroelectric thin film capacitor provided by the embodiments of the present application will be described in more detail below in combination with the embodiments shown in Figures 2-5

[0032] Please refer to Figure 2 , Figure 2 is a structural schematic diagram of the ferroelectric thin film capacitor 100 provided by the embodiments of the present application. As shown in Figure 2 ​As shown, the ferroelectric thin-film capacitor 100 includes a metal electrode M1, a metal electrode M2, and a ferroelectric layer F disposed between the metal electrodes M1 and M2. The ferroelectric layer F is formed of a zirconium-doped hafnium dioxide ferroelectric thin film. Nitrogen is doped into the zirconium-doped hafnium dioxide ferroelectric thin film. That is, in the ferroelectric layer F, nitrogen ions and oxygen ions together provide free electrons to the zirconium-doped hafnium dioxide ferroelectric thin film.

[0033] In this embodiment, the materials of metal electrodes M1 and M2 can be made of various metal materials. Preferably, the materials of metal electrodes M1 and M2 are titanium nitride (TiN). By setting the materials of metal electrodes M1 and M2 to TiN, this embodiment improves the compatibility of ferroelectric thin-film capacitors with CMOS process flows. In an optional implementation, the thicknesses of metal electrodes M1 and M2 are both 40 nm.

[0034] As can be seen from the above, the ferroelectric thin-film capacitor 100 provided in this application, by doping nitrogen into the zirconium-doped hafnium dioxide ferroelectric layer, can promptly fill the oxygen vacancies in the zirconium-doped hafnium dioxide ferroelectric thin film during the deposition of the ferroelectric thin film and the data access from the ferroelectric thin-film capacitor, thus ensuring the performance of the ferroelectric layer F, without changing the material of the metal electrode. The material used for the metal electrode in conventional technology can be used, making the integration process of the ferroelectric thin-film capacitor 100 into a ferroelectric memory easy to implement; furthermore, with Figure 1B Compared with the prior art shown, the embodiments of this application do not require the placement of metal oxide materials between the ferroelectric layer F and each metal electrode, thereby avoiding the "mismatch strain" problem between the metal oxide layer and the zirconium-doped hafnium dioxide ferroelectric layer during crystallization, which can effectively reduce the difficulty of process integration and the preparation cost.

[0035] based on Figure 2 The ferroelectric thin-film capacitor 100 shown in the embodiment of this application also provides a method for preparing such a ferroelectric thin-film capacitor. Figure 2 The process flow for the ferroelectric thin-film capacitor 100 is shown below. Please refer to it. Figure 3 , Figure 3 Is it to prepare such Figure 2 A process flow 200 for the ferroelectric thin-film capacitor 100 shown includes the following steps:

[0036] Step 301: Prepare metal electrode M1 using atomic deposition process.

[0037] The metal electrode M1 can be made of TiN or W, etc. The following description uses a TiN-based metal electrode M1 as an example.

[0038] In the embodiment of the present application, TiN can be prepared based on the principle that TiCl4 reacts with NH3 to generate TiN. In a specific process, TiCl4 is used as a precursor of Ti ion, NH3 is used as a precursor of N ion, a cycle ratio of TiCl4 to NH3 is 1:1, atomic deposition technology is used to deposit TiCl4 material and NH3 material respectively. TiN is generated by the reaction between the deposited TiCl4 material and NH3 material. When the thickness of the TiN material reaches a preset thickness (for example, 40 nm), the deposition of TiCl4 material and NH3 material is stopped. In this way, the metal electrode M1 of TiN material is prepared.

[0039] In step 302, a ferroelectric layer F is formed on the metal electrode M1, wherein the material of the ferroelectric layer F is zirconium-doped hafnium dioxide material, and the zirconium-doped hafnium dioxide material is uniformly doped with nitrogen elements. The in-situ doping of nitrogen elements in the zirconium-doped hafnium dioxide material is obtained by continuously injecting NH3 during the formation of the zirconium-doped hafnium dioxide ferroelectric thin film.

[0040] In a specific process, 1 nm hafnium oxide (HfOx), 5 cycles of NH3, 1 nm zirconium oxide (ZrOx) and 5 cycles of NH3 are used as a basic deposition cycle by using atomic deposition technology, and the basic deposition cycle is repeated for multiple cycles to obtain a ferroelectric layer F with a preset thickness. For example, the ferroelectric layer F with a thickness of 8 nm can be obtained by repeating the basic deposition cycle for 4 cycles. It should be noted that each region of the ferroelectric layer F is doped with N elements.

[0041] In step 303, a metal electrode M2 is formed on the ferroelectric layer F.

[0042] The step of forming the metal electrode M2 on the ferroelectric layer F is the same as the step of preparing the metal electrode M1 in step 301, and the description of step 301 is referred to for details, which will not be repeated here.

[0043] After steps 301-303, the ferroelectric thin film capacitor 100 as shown in Figure 2 is prepared.

[0044] Figure 2As shown in the ferroelectric thin film capacitor 100, each region of the ferroelectric layer F is doped with N elements, and the concentration of N elements doped in each region is the same. However, the edge region of the ferroelectric layer F in contact with the metal electrode M1 and the metal electrode M2 has a high concentration of oxygen vacancies and a large number of oxygen ion loss; the region inside the ferroelectric layer F away from the metal electrode has a low concentration of oxygen vacancies and a small number of oxygen ion loss. Based on this, in one possible implementation of the embodiments of the present application, based on the concentration of oxygen vacancies in each region of the ferroelectric layer F, different regions of the ferroelectric layer F can be doped with different concentrations of nitrogen elements. For example, the region of the ferroelectric layer F close to the metal electrode can be provided with a higher concentration of N elements to fill the high concentration of oxygen vacancies, and the region of the ferroelectric layer F away from the metal electrode can be provided with a lower concentration of N elements to fill the low concentration of oxygen vacancies. Please refer to Figure 4 , Figure 4 is a structural schematic diagram of a ferroelectric thin film capacitor 300 provided by the embodiments of the present application.

[0045] In Figure 4 , the ferroelectric thin film capacitor 100 includes a metal electrode M1, a metal electrode M2, and a ferroelectric layer F disposed between the metal electrode M1 and the metal electrode M2. The specific structure and the material used of the metal electrode M1 and the metal electrode M2 are the same as those of the metal electrode M1 and the metal electrode M2 in the ferroelectric thin film capacitor 100 shown in Figure 2 . For details, please refer to the relevant description, which will not be repeated here. The ferroelectric layer F of the ferroelectric thin film capacitor 300 is a zirconium-doped hafnium dioxide ferroelectric material, and the zirconium-doped hafnium dioxide ferroelectric material is further doped with nitrogen elements. Unlike the ferroelectric thin film capacitor 100 shown in Figure 2 , the ferroelectric layer F of the ferroelectric thin film capacitor 300 is not uniformly doped with nitrogen elements. Figure 4 As shown in the ferroelectric thin film capacitor 300, the concentration of nitrogen elements doped in different regions of the ferroelectric layer F is different. Specifically, Figure 4 As shown in the ferroelectric layer F, the region 1 is the region close to the metal electrode M1, the region 2 is the region close to the metal electrode M2, and the region 3 is the region inside the ferroelectric layer F away from the metal electrode M1 and the metal electrode M2. In addition, the region 4 between the region 1 and the region 3, and the region 5 between the region 2 and the region 3, the zirconium-doped hafnium dioxide ferroelectric material is not doped with nitrogen elements. In addition, the concentration of nitrogen elements doped in the zirconium-doped hafnium dioxide ferroelectric film in the region 1 and the region 2 is the same, and the concentration of nitrogen elements doped in the zirconium-doped hafnium dioxide ferroelectric film in the region 3 is less than the concentration of nitrogen elements doped in the zirconium-doped hafnium dioxide ferroelectric film in the region 1 and the region 2.

[0046] Based on the structure of the ferroelectric thin film capacitor 400 shown in Figure 4 , the embodiments of the present application further provide a method for preparing the ferroelectric thin film capacitor 400 as shown in Figure 4The process flow for the ferroelectric thin-film capacitor 400 is shown below. Please refer to it. Figure 5 , Figure 5 Is it to prepare such Figure 4 A process flow 400 for the ferroelectric thin-film capacitor 300 shown includes the following steps:

[0047] Step 501: Prepare metal electrode M1 using atomic deposition process.

[0048] The steps for preparing the metal electrode M1 are similar to... Figure 3 The steps for preparing the metal electrode M1 in step 301 are the same as those shown in the figure. Please refer to the description of step 301 for details, and they will not be repeated here.

[0049] Step 502: A ferroelectric layer F is formed on the metal electrode M1. The material of the ferroelectric layer F is zirconium-doped hafnium dioxide material, and nitrogen element is doped in the zirconium-doped hafnium dioxide material. The concentration of nitrogen element doped in the region of the ferroelectric layer F near the metal electrode is higher than the concentration of nitrogen element doped in the central region of the ferroelectric layer F.

[0050] In the specific process, tetramethylethylaminohafnium (TDMA-Hf) can be used as a precursor for Hf, tetramethylethylaminozirconium (TDMA-Zr) as a precursor for Zr, O3 as an oxygen source, and NH3 as an implantation factor to prepare N-implanted zirconium-doped hafnium dioxide ferroelectric thin films. The preparation of the ferroelectric layer F includes the following steps:

[0051] First, a zirconium-doped hafnium dioxide ferroelectric thin film A1 is deposited on the surface of the metal electrode M1. This zirconium-doped hafnium dioxide ferroelectric thin film A1 is doped with a first concentration of nitrogen. Specifically, a basic deposition cycle of 1 cycle TDMA-Hf, 1 cycle O3, 1 cycle TDMA-Zr, 1 cycle O3, and 5 cycles NH3 can be used to prepare the zirconium-doped hafnium dioxide ferroelectric thin film A1. When the thickness of the zirconium-doped hafnium dioxide ferroelectric thin film A1 reaches a preset thickness (e.g., 1 nm), the preparation of the zirconium-doped hafnium dioxide ferroelectric thin film A1 doped with the first concentration of nitrogen is complete.

[0052] Second, a zirconium-doped hafnium dioxide ferroelectric thin film A2 is prepared on the surface of the zirconium-doped hafnium dioxide ferroelectric thin film A1. The zirconium-doped hafnium dioxide ferroelectric thin film A2 is not doped with nitrogen. Specifically, 1 cycle of TDMA-Hf, 1 cycle of O3, 1 cycle of TDMA-Zr, and 1 cycle of O3 can be used as the basic deposition cycles to prepare the zirconium-doped hafnium dioxide ferroelectric thin film A2. When the deposition thickness of the zirconium-doped hafnium dioxide ferroelectric thin film A2 reaches a preset thickness (e.g., 2.5 nm), the zirconium-doped hafnium dioxide ferroelectric thin film A2 with a first concentration of nitrogen doped is prepared.

[0053] Third, a zirconium-doped hafnium dioxide ferroelectric thin film A3 is prepared on the surface of the zirconium-doped hafnium dioxide ferroelectric thin film A2. The zirconium-doped hafnium dioxide ferroelectric thin film A3 is doped with a second concentration of nitrogen elements. The second concentration is less than the first concentration. Specifically, 1 cycle TDMA-Hf, 1 cycle O3, 1 cycle TDMA-Zr, 1 cycle O3 and 1 cycle NH3 can be used as the basic deposition cycle to prepare the zirconium-doped hafnium dioxide ferroelectric thin film A3. When the deposition thickness of the zirconium-doped hafnium dioxide ferroelectric thin film A3 reaches a preset thickness (e.g., 1 nm), the zirconium-doped hafnium dioxide ferroelectric thin film A3 doped with the second concentration of nitrogen elements is prepared.

[0054] Fourth, a zirconium-doped hafnium dioxide ferroelectric thin film A4 is prepared on the surface of the zirconium-doped hafnium dioxide ferroelectric thin film A3. The zirconium-doped hafnium dioxide ferroelectric thin film A4 is not doped with nitrogen elements. Specifically, 1 cycle TDMA-Hf, 1 cycle O3, 1 cycle TDMA-Zr and 1 cycle O3 can be used as the basic deposition cycle to prepare the zirconium-doped hafnium dioxide ferroelectric thin film A4. When the deposition thickness of the zirconium-doped hafnium dioxide ferroelectric thin film A4 reaches a preset thickness (e.g., 2.5 nm), the zirconium-doped hafnium dioxide ferroelectric thin film A3 doped with the second concentration of nitrogen elements is prepared.

[0055] Fifth, a zirconium-doped hafnium dioxide ferroelectric thin film A5 is prepared on the surface of the zirconium-doped hafnium dioxide ferroelectric thin film A4. The zirconium-doped hafnium dioxide ferroelectric thin film A4 is doped with a first concentration of nitrogen elements. Specifically, 1 cycle TDMA-Hf, 1 cycle O3, 1 cycle TDMA-Zr, 1 cycle O3 and 5 cycle NH3 can be used as the basic deposition cycle to prepare the zirconium-doped hafnium dioxide ferroelectric thin film A5. When the deposition thickness of the zirconium-doped hafnium dioxide ferroelectric thin film A5 reaches a preset thickness (e.g., 1 nm), the zirconium-doped hafnium dioxide ferroelectric thin film A5 doped with the second concentration of nitrogen elements is prepared.

[0056] After the first to fifth steps, the ferroelectric layer F is prepared, which includes the zirconium-doped hafnium dioxide ferroelectric thin films A1-A5.

[0057] Step 503, a metal electrode M2 is formed on the ferroelectric layer F.

[0058] The step of forming the metal electrode M2 on the ferroelectric layer F is the same as the step of preparing the metal electrode M1 in step 301. For details, refer to the description of step 301, which will not be repeated here.

[0059] After step 301 to step 303, the metal electrode M1 and the ferroelectric layer F are prepared. Figure 2The ferroelectric thin film capacitor 200 shown.

[0060] Based on the ferroelectric thin film capacitor as described in the above embodiments, the embodiments of the present application further provide a ferroelectric memory 500, as shown in the following figure. Figure 6 The ferroelectric memory 500 includes a plurality of memory cells 501, 502, …, 50n arranged in an array. Each memory cell includes a transistor M and a ferroelectric thin film capacitor C. The ferroelectric thin film capacitor C can be the ferroelectric thin film capacitor 100 as shown in the following figure or the ferroelectric thin film capacitor 200 as shown in the following figure. Figure 2 Figure 4 In addition, the ferroelectric memory 500 further includes a plurality of word lines WL0, WL1, …, WLm and a plurality of bit lines BL0, BL1, …, BLn. Each of the memory cells is connected to one of the bit lines and one of the word lines. For example, the memory cell 501 is connected to the bit line BL0 and the word line WL0. The gate of the transistor M is connected to the word line WL0, the source of the transistor M is connected to the bit line BL0, the drain of the transistor M is connected to one end of the capacitor C, and the other end of the capacitor C is connected to the plate line PL.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit the same. Although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements to some or all of the technical features. Such modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.​

Claims

1. A structure of a ferroelectric thin film capacitor, characterized by comprising: Comprising: a first metal electrode; a second metal electrode; a ferroelectric layer disposed between the first metal electrode and the second metal electrode; wherein the material of the ferroelectric layer is a zirconium-doped hafnium dioxide material, and the zirconium-doped hafnium dioxide material is doped with nitrogen elements; a first region of the ferroelectric layer, which is closer to the first metal electrode, has a higher concentration of the nitrogen elements than a second region of the ferroelectric layer, which is farther away from the first metal electrode; a third region of the ferroelectric layer, which is closer to the second metal electrode, has a higher concentration of the nitrogen elements than the second region.

2. The structure of claim 1, wherein A fourth region is further disposed between the first region and the second region, and the fourth region is not doped with the nitrogen elements.

3. The structure of claim 2, wherein A fifth region is further disposed between the second region and the third region, and the fifth region is not doped with the nitrogen elements.

4. The structure of claim 1, wherein The material of the first metal electrode and the second metal electrode is titanium nitride.

5. A method for making a ferroelectric thin film capacitor, characterized by, Comprising: preparing a first metal electrode using an atomic deposition process; forming a ferroelectric layer on the first metal electrode, wherein the material of the ferroelectric layer is a zirconium-doped hafnium dioxide material, and the zirconium-doped hafnium dioxide material is doped with nitrogen elements; forming a second metal electrode on the first metal electrode; a first region of the ferroelectric layer, which is closer to the first metal electrode, has a higher concentration of the nitrogen elements than a second region of the ferroelectric layer, which is farther away from the first metal electrode; a third region of the ferroelectric layer, which is closer to the second metal electrode, has a higher concentration of the nitrogen elements than the second region.

6. The method of claim 5, wherein, The forming of the ferroelectric layer on the first metal electrode comprises: depositing a first zirconium-doped hafnium dioxide ferroelectric thin film on the surface of the first metal electrode, the first zirconium-doped hafnium dioxide ferroelectric thin film is doped with a first concentration of nitrogen elements; depositing a second zirconium-doped hafnium dioxide ferroelectric thin film on the surface of the first zirconium-doped hafnium dioxide ferroelectric thin film, the first zirconium-doped hafnium dioxide ferroelectric thin film is not doped with nitrogen elements; depositing a third zirconium-doped hafnium dioxide ferroelectric thin film on the surface of the second zirconium-doped hafnium dioxide ferroelectric thin film, the third zirconium-doped hafnium dioxide ferroelectric thin film is doped with a second concentration of nitrogen elements, wherein the first concentration is higher than the second concentration; depositing a fourth zirconium-doped hafnium dioxide ferroelectric thin film on the surface of the third zirconium-doped hafnium dioxide ferroelectric thin film, the fourth zirconium-doped hafnium dioxide ferroelectric thin film is not doped with nitrogen elements; depositing a fifth zirconium-doped hafnium dioxide ferroelectric thin film on the surface of the fourth zirconium-doped hafnium dioxide ferroelectric thin film, the fifth zirconium-doped hafnium dioxide ferroelectric thin film is doped with the first concentration of nitrogen elements.

7. The method of claim 5, wherein, The material of the first metal electrode and the second metal electrode is titanium nitride.

8. A ferroelectric memory, comprising: The ferroelectric memory comprises a plurality of memory cells arranged in an array; each of the plurality of memory cells comprises a transistor and a ferroelectric thin film capacitor structure as claimed in any one of claims 1-4.

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