Epitaxial hafnium oxide-based ferroelectric capacitor and atomic layer deposition preparation method thereof

Abstract

The invention provides an epitaxial hafnium oxide-based ferroelectric capacitor and an atomic layer deposition preparation method thereof, and the preparation method comprises the steps: providing a substrate layer, and depositing a zirconia epitaxial buffer layer on the substrate layer through employing an atomic layer deposition technology; forming a hafnium oxide-based epitaxial ferroelectric layer on the zirconium oxide epitaxial buffer layer by adopting an atomic layer deposition process; photoresist is spin-coated on the hafnium oxide-based epitaxial ferroelectric layer, exposure and development are carried out, and the shape of a top electrode is defined; preparing a top electrode on the hafnium oxide-based epitaxial ferroelectric layer; and annealing by adopting a rapid annealing process to realize the ferroelectricity of the hafnium oxide-based epitaxial ferroelectric layer. According to the application, the zirconium oxide epitaxial buffer layer is arranged between the ferroelectric layer and the substrate layer, so that the hafnium oxide-based epitaxial ferroelectric layer grown through ALD presents a highly oriented epitaxial lattice structure, the leakage current of the hafnium oxide-based ferroelectric capacitor can be reduced, and the cycle performance of the capacitor is improved.

Description

Technical Field

[0001] This application relates to the field of integrated circuit devices, specifically to an epitaxial hafnium oxide-based ferroelectric capacitor and its atomic layer deposition preparation method. Background Technology

[0002] In the era of big data driven by artificial intelligence and the Internet of Things, the mismatch between the computing speed of logic devices and the storage speed of memory devices has brought considerable inconvenience and constraints to the development of related industries. Among them, problems such as slow read and write speeds, high operating voltages, limited cycle counts, and size scaling limits are the main challenges currently faced by advanced non-volatile memory devices. Therefore, to achieve higher speed, lower power consumption, and higher density non-volatile memory devices, new breakthroughs are urgently needed in materials, principles, and architecture.

[0003] Among these, utilizing the polarization and reversal properties of ferroelectric materials to fabricate non-volatile memory devices and creating an integrated circuit design that combines the speed and durability of main memory with large-scale non-volatile memory has become an important research topic. Commonly used ferroelectric memories, such as Fe-RAM, have been around for 30 years since their introduction by Ramtron and Fujitsu in 1996. These memories offer high processing speed, low power consumption, high retention, and durability. However, because the process temperatures required for traditional ferroelectric materials far exceed those of typical CMOS processes, their process nodes are difficult to further reduce, making them unsuitable for large-scale integrated circuits. Furthermore, various emerging memories, such as ferroelectric field-effect transistors (Fe-FETs) and ferroelectric tunnel junctions (FTJs), are also limited by process temperature and other factors, and no mass-produced products have yet emerged.

[0004] In 2011, a team at Qimonda AG in Germany first confirmed the existence and transformation process of hafnium oxide-based ferroelectric phases and discovered their excellent miniaturization properties. Therefore, hafnium oxide-based ferroelectric memory devices are a promising next-generation non-volatile semiconductor memory. However, their self-flipping exhibits a high coercive electric field Ec, leading to reduced material reliability. Improving material reliability, especially cycle life, is crucial for the practical application of hafnium oxide-based materials. Currently, most commonly used hafnium oxide-based thin films are polycrystalline, and numerous lattice defects easily lead to rapid degradation and breakdown of the crystal structure during cyclic testing. Therefore, introducing high-quality epitaxial thin films has become a potential option. However, current epitaxial thin film preparation methods mostly employ physical vapor deposition (PVD), which requires high deposition temperatures and is not suitable for large-area wafer fabrication, making it unsuitable for large-scale production lines in wafer fabs.

[0005] A search revealed that patent application CN119815842A discloses a La-doped hafnium oxide-based ferroelectric thin film, a capacitor, and a method for their preparation. The preparation method involves first epitaxially growing a buffer layer with consistent orientation on a (111) oriented perovskite substrate, and then epitaxially growing a La-doped hafnium oxide-based ferroelectric thin film layer on the surface of the buffer layer to obtain a La-doped hafnium oxide-based ferroelectric thin film. The film thickness can be precisely controlled to optimize the performance of the La-doped hafnium oxide-based ferroelectric thin film and meet the needs of electronic devices for high-performance ferroelectric thin films.

[0006] Patent application CN115786855A discloses an epitaxial yttrium-doped hafnium-based ferroelectric thin film material and its growth method. The ferroelectric thin film material, from top to bottom, consists of an SrTiO3 (STO) substrate and a La... 0.7 Sr 0.3 MnO3 (LSMO) buffer layer and yttrium-doped hafnium oxide (YHO) ferroelectric thin film.

[0007] Both of the above patents use the laser pulse deposition (PLD) method in PVD to prepare hafnium-based thin films. However, this method is only applicable to small wafers with millimeter-sized wafers and has low production efficiency. Therefore, it is necessary to develop process methods that can be adapted to large-scale production lines. Summary of the Invention

[0008] In view of the deficiencies in the prior art, the purpose of this application is to provide an epitaxial hafnium oxide-based ferroelectric capacitor and a method for preparing the same by atomic layer deposition.

[0009] A first aspect of this application provides a method for preparing an epitaxial hafnium oxide-based ferroelectric capacitor by atomic layer deposition, comprising:

[0010] A substrate layer is provided, on which a zirconium oxide epitaxial buffer layer is deposited using an atomic layer deposition process;

[0011] A hafnium oxide-based epitaxial ferroelectric layer is formed on the zirconium oxide epitaxial buffer layer using an atomic layer deposition process;

[0012] Photoresist is spin-coated onto the hafnium oxide-based epitaxial ferroelectric layer and then exposed and developed to define the shape of the top electrode.

[0013] A top electrode is fabricated on the hafnium oxide-based epitaxial ferroelectric layer;

[0014] The ferroelectricity of the hafnium oxide-based epitaxial ferroelectric layer is achieved by annealing using a rapid annealing process.

[0015] Optionally, a substrate layer is provided, on which a zirconium oxide epitaxial buffer layer is deposited using an atomic layer deposition process, wherein: the deposition temperature is 200-500°C, the deionized water is kept at room temperature of 25°C, the Zr precursor is selected from any one of ZrCl4, TEMAZ, and TDMAZ, and the oxygen source is any one of water, ozone, and hydrogen peroxide.

[0016] Optionally, a substrate layer is provided, on which a zirconia epitaxial buffer layer is deposited using an atomic layer deposition process, wherein the thickness of the zirconia epitaxial buffer layer is 0-30 nm.

[0017] Optionally, the hafnium oxide-based epitaxial ferroelectric layer is formed on the zirconium oxide epitaxial buffer layer using an atomic layer deposition process, wherein the deposition temperature is 200–500°C.

[0018] Optionally, a hafnium oxide-based epitaxial ferroelectric layer is formed on the zirconium oxide epitaxial buffer layer using an atomic layer deposition process, wherein the thickness of the hafnium oxide-based epitaxial ferroelectric layer is 0-300 nm.

[0019] Optionally, a top electrode is fabricated on the hafnium oxide-based epitaxial ferroelectric layer, wherein the top electrode is a monolayer structure formed from any one of TiN, W, Mo, Al, Ru and RuO2, or a stacked structure formed from at least two of TiN, W, Mo, Al, Ru and RuO2.

[0020] Optionally, a top electrode is fabricated on the hafnium oxide-based epitaxial ferroelectric layer, wherein the top electrode is formed by magnetron sputtering.

[0021] Optionally, the annealing process is used to achieve the ferroelectricity of the hafnium oxide-based epitaxial ferroelectric layer, wherein the annealing temperature is 300-1000℃ and the process gas is any one of O2, N2, and Ar.

[0022] Optionally, a substrate layer is provided, on which a zirconium oxide epitaxial buffer layer is deposited, wherein: the substrate layer comprises a single-crystal substrate and a bottom electrode, the single-crystal substrate is a monolayer structure formed from any one of SrTiO3 (STO), LaAlO3 (LAO), YSZ, MgO, Si, and Al2O3, and an epitaxial conductive structure is formed on the single-crystal substrate as the bottom electrode, the bottom electrode being made of TiN, ITO, Nb:SrTiO3 (Nb:STO), La... x Sr 1-x A single-layer single-crystal structure formed by epitaxy of any one of MnO3 (LSMO) on a single-crystal substrate.

[0023] A second aspect of this application provides an epitaxial hafnium oxide-based ferroelectric capacitor prepared by the method, comprising, from bottom to top, a substrate, a bottom electrode, a zirconium oxide epitaxial buffer layer, a hafnium oxide-based epitaxial ferroelectric layer, and a top electrode.

[0024] The atomic layer deposition method for preparing epitaxial hafnium oxide-based ferroelectric capacitors provided in this application involves setting a zirconium oxide epitaxial buffer layer between the ferroelectric layer and the substrate layer. This allows the hafnium oxide-based epitaxial ferroelectric layer grown by ALD to exhibit a highly oriented epitaxial lattice structure, which can reduce the leakage current of the hafnium oxide-based ferroelectric capacitor and improve the cycle performance of the capacitor. Furthermore, the ALD method can realize a large-area wafer deposition process, which is beneficial for the mass production of capacitors.

[0025] Other technical effects resulting from the additional features will be further illustrated in the corresponding embodiments. Attached Figure Description

[0026] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0027] Figure 1 This is a flowchart illustrating an atomic layer deposition method for fabricating an epitaxial hafnium oxide-based ferroelectric capacitor according to an exemplary embodiment;

[0028] Figure 2 This is a schematic diagram of the structure of an epitaxial hafnium oxide-based ferroelectric capacitor according to an exemplary embodiment;

[0029] Figure 3 High-resolution transmission electron microscopy imaging of an epitaxial zirconia buffer layer according to an exemplary embodiment;

[0030] Figure 4 This is a high-resolution X-ray 2θ-ω scan of an epitaxial hafnium oxide functional layer according to an exemplary embodiment;

[0031] Figure 5 A comparison of leakage current between an epitaxial ferroelectric thin film shown according to an exemplary embodiment and a conventional polycrystalline ferroelectric thin film;

[0032] Figure 6 A comparison of the cycling performance of an epitaxial hafnium oxide-based ferroelectric capacitor according to an exemplary embodiment with that of a conventional polycrystalline ferroelectric capacitor;

[0033] Figure 7 A comparison of the dielectric constant of an epitaxial hafnium oxide-based ferroelectric capacitor according to an exemplary embodiment with that of a conventional polycrystalline ferroelectric capacitor;

[0034] Figure 8A comparison of hysteresis curves for epitaxial hafnium oxide-based functional layers of different thicknesses, according to an exemplary embodiment;

[0035] In the figure: 1 is the substrate, 2 is the bottom electrode, 3 is the zirconium oxide epitaxial buffer layer, 4 is the hafnium oxide-based epitaxial ferroelectric layer, and 5 is the top electrode. Detailed Implementation

[0036] The present application will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present application, but do not limit the present application in any way. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present application, and these all fall within the protection scope of the present application. Parts not described in detail in the following embodiments can be implemented using existing technology.

[0037] Existing methods for preparing epitaxial thin films for ferroelectric capacitors primarily employ physical vapor deposition (PVD), which is unsuitable for large-scale production lines in wafer fabs. Based on these issues, and to adapt to the large-scale process conditions required by industry, it is necessary to research deposition methods such as atomic layer deposition (ALD) to prepare epitaxial hafnium oxide-based ferroelectric thin films. This application provides a method for preparing hafnium oxide-based ferroelectric capacitors using ALD deposition, thereby addressing the aforementioned problems.

[0038] Reference Figure 1 As shown in one embodiment of this application, the method for preparing an epitaxial hafnium oxide-based ferroelectric capacitor by atomic layer deposition includes the following steps:

[0039] S1. Provide a substrate layer, and deposit a zirconium oxide epitaxial buffer layer on the substrate layer using an atomic layer deposition process;

[0040] S2. An atomic layer deposition process is used to form a hafnium oxide-based epitaxial ferroelectric layer on the zirconium oxide epitaxial buffer layer;

[0041] S3. Spin-coat photoresist onto the hafnium oxide-based epitaxial ferroelectric layer and expose and develop it to define the shape of the top electrode;

[0042] S4. Fabricate a top electrode on a hafnium oxide-based epitaxial ferroelectric layer;

[0043] S5. A rapid annealing process is used to anneal the hafnium oxide-based epitaxial ferroelectric layer to achieve ferroelectricity.

[0044] Specifically, the numerous grain boundaries and voids in polycrystalline HZO thin films easily form conductive filaments, which become conductive channels. Preparing epitaxial thin films can reduce the defect content in the films. This application aims to achieve Hf using ALD (Alternating Discharge) technology. x Zr 1-xO2 epitaxial film growth is possible because the ALD method is a mature process in current FAB processes, and compared to physical vapor deposition (PVD), ALD is more suitable for large-area wafer deposition, facilitating mass production and significantly reducing the thermal budget required for the deposition process. Depositing a ZrO2 epitaxial buffer layer using the same ALD steps simplifies the process flow, as its deposition conditions are consistent with those of the subsequent hafnium-based functional layer, and it possesses high epitaxial properties, serving as a template for the epitaxial growth of the hafnium-based ferroelectric layer. Based on this, the hafnium-based film continues to grow, resulting in an epitaxial film with fewer defects.

[0045] By pre-depositing a zirconium oxide epitaxial buffer layer using the ALD method, and then further depositing an epitaxial hafnium oxide-based ferroelectric layer on this buffer layer using the ALD method, a highly oriented epitaxial phase structure and better cycling performance can be obtained.

[0046] In the above embodiments of this application, a zirconium oxide epitaxial buffer layer is provided between the ferroelectric layer and the substrate layer, so that the hafnium oxide-based epitaxial ferroelectric layer grown by ALD exhibits a highly oriented epitaxial lattice structure, which can reduce the leakage current of the hafnium oxide-based ferroelectric capacitor and improve the cycle performance of the capacitor.

[0047] In order to achieve the pre-deposition of the zirconium oxide epitaxial buffer layer, in some specific embodiments of this application, in S1, an atomic layer deposition process is used, the deposition temperature is 200-500°C, the deionized water is kept at room temperature of 25°C, the carrier gas is N2, the gas flow rate is 10-40 sccm, the Zr precursor is any one of ZrCl4, TEMAZ, and TDMAZ, and the oxygen source is any one of water, ozone, and hydrogen peroxide.

[0048] It should be noted that the deposition parameters in this step are mainly limited by the operating conditions of the ALD equipment used and the thin film reaction conditions. Taking temperature as an example, setting it to 200 to 500°C is constrained by the upper limit of the reaction chamber temperature of the equipment and the precursor reaction temperature.

[0049] In some specific embodiments of this application, the thickness of the zirconium oxide epitaxial buffer layer is 0-30 nm.

[0050] Preferably, the thickness of the zirconium oxide epitaxial buffer layer is 1-10 nm.

[0051] For example, the thickness of the zirconium oxide epitaxial buffer layer is 3 nm.

[0052] It should be noted that the thickness of the zirconia epitaxial buffer layer needs to take into account the actual operating voltage. If the film is too thick, the operating voltage will be too high and will not meet the usage requirements; if it is too thin, it will be difficult to form a crystalline film.

[0053] In some specific embodiments of this application, in S2, the thickness of the hafnium oxide-based epitaxial ferroelectric layer is 0-300 nm.

[0054] Preferably, the thickness of the hafnium oxide-based epitaxial ferroelectric layer is 1-10 nm. More preferably, the thickness of the hafnium oxide-based epitaxial ferroelectric layer is 4-10 nm, and this thickness of film has high remanent polarization.

[0055] It should be noted that the thickness of the hafnium oxide-based epitaxial ferroelectric layer mainly affects the ferroelectric polarization performance of the thin film. A lower thickness makes it easier to form an antiferroelectric phase, while a higher thickness makes it easier to form more paraelectric phases, which is detrimental to the residual polarization required by the memory device.

[0056] Preferably, the hafnium oxide-based epitaxial ferroelectric layer is a hafnium oxide ferroelectric thin film doped with any one of the elements Zr, Y, Si, Ge, La, Sr, Ce and Al, and the doping concentration is given as needed.

[0057] For example, the material of the hafnium oxide-based epitaxial ferroelectric layer is a Zr-doped HfO2 thin film (HZO). Other elements can also be used for doping, as long as the HfO2 thin film exhibits ferroelectricity.

[0058] In order to achieve the deposition of hafnium oxide-based epitaxial ferroelectric layers, in some specific embodiments of this application, the deposition temperature in S2 is 200-500°C, the deionized water is kept at 25°C, the carrier gas is N2, and the gas flow rate is 10-40 sccm.

[0059] For example, for Zr-doped HfO2 thin films, the Hf precursor can be any one of HfCl4, TEMAH, or TDMAH, the Zr precursor can be either TEMAZ or TDMAZ, and the oxygen source can be any one of water, ozone, or hydrogen peroxide.

[0060] In S3, the top electrode is patterned using a lift-off process, and the remover used for lift-off can be an NMP solution.

[0061] In some specific embodiments of this application, in S4, the top electrode is a single-layer structure formed from any one of TiN, W, Mo, Al, Ru, and RuO2, or a stacked structure formed from at least two of TiN, W, Mo, Al, Ru, and RuO2. The top electrode is formed by magnetron sputtering.

[0062] For example, the top electrode adopts a stacked structure of TiN and W.

[0063] To form a top electrode with a TiN and W stacked structure, in some specific embodiments of this application, magnetron sputtering is used. The sputtering power of the Ti target is 250W, the process gas is a mixture of Ar and N2, the Ar gas flow rate is 50 sccm, the N2 gas flow rate is 4 sccm, and the working pressure is 0.5 Pa. The sputtering power of the W target is 80W, the process gas is Ar, the gas flow rate is 30-50 sccm, and the working pressure is 0.5-0.9 Pa.

[0064] In order to achieve the ferroelectricity of the hafnium oxide-based epitaxial ferroelectric layer, in some specific embodiments of this application, in S5, the annealing temperature is 300-1000°C, the annealing time is 1s-30min, and the process gas is any one of O2, N2, and Ar.

[0065] It should be noted that if the annealing time and temperature are too low, the leakage current of the film will be lower, and the content of the tetragonal phase (T phase) in the film will be higher, and the number of ferroelectric orthorhombic phases (O phase) will be less. Conversely, the leakage current will be higher, and an excessively long annealing time may lead to further conversion into the paraelectric monoclinic phase (M phase), resulting in a reduction in ferroelectricity.

[0066] In the above embodiments of this application, the capacitor is annealed using a rapid annealing process to achieve the ferroelectricity of the ferroelectric layer.

[0067] In some specific embodiments of this application, a substrate layer is provided, on which a zirconium oxide epitaxial buffer layer is deposited. The substrate layer includes a substrate and a bottom electrode. Preferably, the substrate is a single-crystal substrate, on which an epitaxial monolayer single-crystal structure is formed as the bottom electrode. The single-crystal substrate is a monolayer structure formed from any one of SrTiO3 (STO), LaAlO3 (LAO), YSZ, MgO, Si, and Al2O3. An epitaxial conductive structure is formed on the single-crystal substrate as the bottom electrode. The bottom electrode is formed from TiN, ITO, Nb:SrTiO3 (Nb:STO), La... x Sr 1-x A single-layer single-crystal structure formed by epitaxy of any one of MnO3 (LSMO) on a single-crystal substrate.

[0068] Specifically, the ferroelectric layer includes a substrate and a bottom electrode, with the substrate located below the bottom electrode. The substrate can be a semiconductor substrate or an oxide substrate. The single-crystal substrate (i.e., a semiconductor substrate or oxide substrate) is a monolayer structure formed from any one of the following single crystals: SrTiO3 (STO), LaAlO3 (LAO), YSZ, MgO, Si, and Al2O3. The bottom electrode is formed from TiN, ITO, Nb:SrTiO3 (Nb:STO), or La... x Sr 1-xA single-layer single-crystal conductive structure formed by epitaxy on a single-crystal substrate using either MnO3 (LSMO) or IGZO serves as the seed layer for epitaxy.

[0069] Specifically, the bottom electrode material is mainly a single-crystal semiconductor or conductor with high conductivity, and can be epitaxially formed on a single-crystal substrate (with low lattice mismatch rate). It serves two purposes: as the bottom electrode of the capacitor structure, and as a template for the epitaxy of the zirconium oxide buffer layer and hafnium-based functional layer.

[0070] For example, TiN is used as the bottom electrode, and for ease of testing, TiN is also used as the symmetrical top electrode. Since TiN is easily oxidized, a W protective layer needs to be added. Furthermore, TiN is more likely to induce the formation of the ferroelectric O phase during annealing; therefore, the top electrode can adopt a TiN plus W stacked structure.

[0071] The epitaxial hafnium oxide-based ferroelectric capacitor prepared using the above method comprises, from bottom to top, a substrate, a bottom electrode, a zirconium oxide epitaxial buffer layer, a hafnium oxide-based epitaxial ferroelectric layer (i.e., the ferroelectric functional layer), and a top electrode. The epitaxial hafnium oxide-based ferroelectric thin film prepared by the ALD method in this application can achieve a highly oriented epitaxial structure while reducing the leakage current of the hafnium oxide-based thin film and improving the film's cycling performance, thereby optimizing indicators such as polarization intensity, leakage current, cycling performance, and dielectric constant.

[0072] The preferred features in the above embodiments can be used individually in any embodiment, or in any combination thereof, provided they do not conflict with each other. Furthermore, parts not described in detail in the embodiments can be implemented using existing technologies.

[0073] In one specific application example, an epitaxial hafnium oxide-based ferroelectric capacitor with a highly oriented lattice structure is provided. For example... Figure 2 As shown, this is a hafnium oxide-based ferroelectric capacitor with an MFM (metal-ferroelectric functional layer-metal) structure, which includes, from bottom to top, a substrate 1, a bottom electrode 2, a zirconium oxide epitaxial buffer layer 3, a hafnium oxide-based epitaxial ferroelectric layer 4, and a top electrode 5.

[0074] Substrate 1 is a single crystal substrate of MgO.

[0075] The bottom electrode 2 uses a TiN single crystal conductive layer with a thickness of 80 nm. The TiN single crystal layer can be prepared by methods such as ALD or magnetron sputtering, and the thickness of the TiN single crystal layer can be controlled.

[0076] The zirconium oxide epitaxial buffer layer 3 is made of zirconium oxide, and its thickness can be controlled between 1 and 10 nm. Its epitaxial properties can be confirmed by the periodic matching of the ZrO2 lattice and the TiN lattice in its high-resolution transmission electron microscopy image (e.g., Figure 3For example, the thickness of the zirconium oxide epitaxial buffer layer is 3 nm.

[0077] The hafnium oxide-based epitaxial ferroelectric layer 4 is a Zr-doped HfO2 thin film (HZO) with a 1:1 molar ratio of Hf to Zr, exhibiting strong ferroelectricity. Furthermore, the thickness of the ferroelectric layer can be controlled. It should be noted that an excessively thin ferroelectric layer will result in an antiferroelectric capacitor. For example, an HZO thin film with a thickness of 4–10 nm is used.

[0078] The top electrode 5 is made of a TiN and W stack structure, wherein the thickness of both the TiN and W metal layers is 10–30 nm. The W metal layer is deposited on top of the TiN metal layer to prevent oxidation of the TiN electrode in air. For example, both the TiN and W metal layers are 30 nm thick, and rapid thermal annealing in an N2 atmosphere is performed after TiN and W deposition to achieve the ferroelectricity of the ferroelectric layer.

[0079] The following is an exemplary fabrication process of the epitaxial hafnium oxide-based ferroelectric capacitor with the MFM structure, specifically including the following steps:

[0080] Step 1: A zirconium oxide layer is prepared on the TiN single crystal bottom electrode using atomic layer deposition. The deposition temperature range is 200-300℃, the deionized water is kept at room temperature of 25℃, the carrier gas is N2, the gas flow rate is 10-40 sccm, the Zr precursor is TEMAZ or TDMAZ, the oxygen source is water, ozone or hydrogen peroxide, and the deposition thickness is 3nm.

[0081] Step 2: On the zirconium oxide layer, an HZO ferroelectric layer is prepared using atomic layer deposition. The deposition ratio of Hf to Zr is 1:1, the deposition temperature range is 200-300℃, the deionized water is kept at room temperature of 25℃, the carrier gas is N2, the gas flow rate is 10-40 sccm, the precursor of Hf is selected as TEMAH or TDMAH, the precursor of Zr is selected as TEMAZ or TDMAZ, the oxygen source is water, ozone or hydrogen peroxide, and the deposition thickness of the ferroelectric layer is 7-10 nm.

[0082] Step 3: Spin-coat photoresist LOR10A and AZ5124 onto the HZO ferroelectric layer and expose and develop them to define the shape of the top electrode;

[0083] Step 4: A top electrode is fabricated on the HZO ferroelectric functional layer using magnetron sputtering. The top electrode is a stacked structure of TiN and W. The TiN is fabricated using reactive radio frequency magnetron sputtering, with a sputtering power of 250W for the Ti target, a process gas mixture of Ar and N2, an Ar gas flow rate of 50 sccm, an N2 gas flow rate of 4 sccm, and a working pressure of 0.5 Pa. The W is sputtered with a power of 80W, using Ar as the process gas, a gas flow rate of 30–50 sccm, and a working pressure of 0.5–0.9 Pa. The top electrode is patterned using a lift-off process, with NMP solution used as the resist remover.

[0084] Step 5: Annealing is performed using a rapid annealing process to achieve the ferroelectricity of the ferroelectric layer. The annealing temperature is 300–1000℃ and the process gas is N2.

[0085] This capacitor is based on atomic layer deposition technology. By inserting a ZrO2 buffer layer (3nm), hafnium oxide-based epitaxial thin film is grown on a single crystal MgO substrate, which overcomes the shortcomings of traditional physical vapor deposition (PVD) technology, such as high preparation temperature and unsuitability for large-size wafers.

[0086] The embodiments described above in this application can grow hafnium oxide-based epitaxial ferroelectric thin films with highly oriented lattice structures by inserting a ZrO2 epitaxial buffer layer between the ferroelectric layer and the substrate. Their epitaxial characteristics can be confirmed by their single out-of-plane diffraction peak and the periodic X-ray reflection intensity oscillations on both sides of the peak. Figure 4 As shown. The performance is compared with that of polycrystalline hafnium oxide-based ferroelectric capacitors, for example... Figure 5 , Figure 6 and Figure 7 As shown. Compared with polycrystalline hafnium oxide-based ferroelectric capacitors, the leakage current level of the capacitor in this application is reduced by an order of magnitude overall, and by nearly two orders of magnitude in the range of 0.5 to 1 MV / cm; the cycle performance is improved by two orders of magnitude, from 1e6 to 1e8, as can be seen from the polarization intensity characterization of the cycle performance. Figure 6 The vertical axis represents the polarization intensity of the ferroelectric thin film. The dielectric constant increased from 31 for polycrystalline hafnium-based thin films to 58.

[0087] By placing a zirconium oxide epitaxial buffer layer between the ferroelectric layer and the bottom electrode layer, the hafnium oxide-based ferroelectric layer is induced to crystallize and form an epitaxial thin film. Furthermore, the above embodiments of this application can achieve the control of properties from antiferroelectric to ferroelectric by adjusting the thickness of the functional layer, such as... Figure 8As shown, thickness primarily affects the ferroelectric polarization performance of thin films. Lower thicknesses tend to form antiferroelectric phases, while higher thicknesses tend to form more paraelectric phases, which is detrimental to the remanent polarization required by memory devices. Thin films in the 4–10 nm range exhibit high remanent polarization, and the antiferroelectric to ferroelectric properties of the thin film can be adjusted within this range by regulating the thickness.

[0088] In the description of the embodiments in this application, "multiple" means two or more, unless otherwise explicitly specified. In this application, unless otherwise explicitly specified and limited, the terms "installed," "connected," "linked," "fixed," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0089] The terms "comprising" and "having," and any variations thereof, in the embodiments of this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such processes, methods, products, or devices.

[0090] The accompanying drawings illustrate various structural schematics according to embodiments of this application. These drawings are not to scale, and some details have been enlarged for clarity, while others may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed, all of which fall within the scope of protection of this application.

[0091] The foregoing has described some specific embodiments of this application. It should be understood that this application is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the substantive content of this application. The above-described preferred features can be used in any combination without conflict.

Claims

1. A method of atomic layer deposition for epitaxial hafnium oxide based ferroelectric capacitor fabrication, comprising: The application relates to a hafnium oxide-based epitaxial ferroelectric layer and a preparation method thereof. Providing a substrate layer, depositing a zirconium oxide epitaxial buffer layer on the substrate layer by using an atomic layer deposition process; Forming a hafnium oxide-based epitaxial ferroelectric layer on the zirconium oxide epitaxial buffer layer by using an atomic layer deposition process; Spinning photoresist on the hafnium oxide-based epitaxial ferroelectric layer and carrying out exposure and development to define the shape of a top electrode; Preparation of the top electrode on the hafnium oxide-based epitaxial ferroelectric layer; Annealing by using a rapid annealing process to realize the ferroelectricity of the hafnium oxide-based epitaxial ferroelectric layer.

2. The method of claim 1, wherein the method is performed in a single chamber atomic layer deposition system. The substrate layer is provided, and the zirconium oxide epitaxial buffer layer is deposited on the substrate layer by using an atomic layer deposition process, wherein the deposition temperature is 200-500 DEG C, the deionized water is kept at room temperature of 25 DEG C, the Zr precursor is selected from any one of ZrCl4, TEMAZ and TDMAZ, and the oxygen source is any one of water, ozone and hydrogen peroxide.

3. The method of claim 1, wherein the method is performed in a single chamber atomic layer deposition system. The substrate layer is provided, and the zirconium oxide epitaxial buffer layer is deposited on the substrate layer by using an atomic layer deposition process, wherein the thickness of the zirconium oxide epitaxial buffer layer is 0-30 nm.

4. The method of claim 1, wherein the method is performed by atomic layer deposition. The hafnium oxide-based epitaxial ferroelectric layer is formed on the zirconium oxide epitaxial buffer layer by using an atomic layer deposition process, wherein the deposition temperature is 200-500 DEG C.

5. The method of claim 1, wherein the method is performed by atomic layer deposition. The hafnium oxide-based epitaxial ferroelectric layer is formed on the zirconium oxide epitaxial buffer layer by using an atomic layer deposition process, wherein the Hf precursor of the hafnium oxide-based epitaxial layer is selected from HfCl4, TEMAH or TDMAH, and the oxygen source is any one of water, ozone and hydrogen peroxide.

6. The method of claim 1, wherein the method is performed by atomic layer deposition. The hafnium oxide-based epitaxial ferroelectric layer is formed on the zirconium oxide epitaxial buffer layer by using an atomic layer deposition process, wherein the doping element of the hafnium oxide-based epitaxial layer is any one of Zr, Y, Al, Si, Ge, La, Sr and Ce.

7. The method of claim 1, wherein the method is performed by atomic layer deposition. The hafnium oxide-based epitaxial ferroelectric layer is formed on the zirconium oxide epitaxial buffer layer by using an atomic layer deposition process, wherein the thickness of the hafnium oxide-based epitaxial ferroelectric layer is 0-300 nm.

8. The method of claim 1, wherein the method is performed by atomic layer deposition. The top electrode is prepared on the hafnium oxide-based epitaxial ferroelectric layer, wherein the top electrode is a single-layer structure formed by any one of TiN, W, Mo, Al, Ru and RuO2, or is a laminated structure formed by at least two of TiN, W, Mo, Al, Ru and RuO2.

9. The method of claim 1, wherein the method is performed by atomic layer deposition. The top electrode is prepared on the hafnium oxide-based epitaxial ferroelectric layer, wherein the top electrode is formed by using a magnetron sputtering mode.

10. The method of claim 1, wherein the method is an atomic layer deposition method for epitaxial hafnium oxide-based ferroelectric capacitor, and the method comprises: providing a substrate; providing a first precursor; providing a second precursor; and providing a third precursor. The hafnium oxide-based epitaxial ferroelectric layer is annealed by using a rapid annealing process to realize the ferroelectricity of the hafnium oxide-based epitaxial ferroelectric layer, wherein the annealing temperature is 300-1000 DEG C, and the process gas is any one of O2, N2 and Ar.

11. The method of claim 1, wherein the method is an atomic layer deposition method for epitaxial hafnium oxide-based ferroelectric capacitor, and the method comprises: providing a substrate; providing a first precursor; providing a second precursor; and providing a third precursor. The method comprises the steps of providing a substrate layer, and depositing a zirconium oxide epitaxial buffer layer on the substrate layer, wherein the substrate layer comprises a single crystal substrate and a bottom electrode, the single crystal substrate is a single-layer structure formed by any one of single crystals of SrTiO3, LaAlO3, YSZ, MgO, Si, Al2O3, and an epitaxial conductive structure is formed on the single crystal substrate as the bottom electrode, the bottom electrode is a single-layer single crystal structure formed by any one of TiN, ITO, Nb:SrTiO3, La x Sr 1-x MnO3 on the single crystal substrate.

12. An epitaxial hafnium oxide based ferroelectric capacitor prepared by the method of any one of claims 1-11, wherein, From bottom to top, the application sequentially comprises a substrate, a bottom electrode, a zirconium oxide epitaxial buffer layer, a hafnium oxide-based epitaxial ferroelectric layer and a top electrode.

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