Ferroelectric device and method of fabrication

Abstract

The application discloses a ferroelectric device and a preparation method, relates to the technical field of microelectronics, and can improve the remanent polarization stability of the ferroelectric device, thereby prolonging the service life of the ferroelectric device. The ferroelectric device comprises a lower electrode, an upper electrode, a ferroelectric material layer and a non-ferroelectric material layer. The non-ferroelectric material layer is connected with the ferroelectric material layer and is used for having ferroelectricity by undergoing a crystal phase transition when an electric field is applied. The ferroelectric material layer and the non-ferroelectric material layer are both arranged between the lower electrode and the upper electrode, and the upper electrode and the lower electrode are used for applying an electric field to the ferroelectric material layer and the non-ferroelectric material layer.

Description

Technical Field

[0001] This application relates to the field of microelectronics technology, and in particular to a ferroelectric device and its fabrication method. Background Technology

[0002] Ferroelectric materials exhibit spontaneous polarization when no external electric field is applied, and the direction of this spontaneous polarization can be reversed or redirected by an applied electric field. Specifically, when a ferroelectric material is subjected to an external electric field, it can be controlled to possess one of two stable polarities. These two stable polarities can be used to store data corresponding to logic "0" and logic "1". Therefore, ferroelectric devices made from ferroelectric materials can be used in storage devices.

[0003] Current research on the durability of ferroelectric devices typically focuses on the limiting number of electrical cycles and uses complete breakdown as the criterion for failure. However, the residual polarization (Pr) of a ferroelectric device begins to degrade before breakdown. When ferroelectric devices are used as memory, Pr degradation can easily lead to misreading of stored information. Therefore, the stability of the residual polarization during electrical cycling affects the lifespan of the ferroelectric device. However, the Pr stability of existing ferroelectric devices is generally poor, resulting in short device lifespans in memory applications. Summary of the Invention

[0004] This application provides a ferroelectric device and its fabrication method, which can improve the stability of the residual polarization intensity of the ferroelectric device and thus improve its lifespan.

[0005] A first aspect of this application provides a ferroelectric device, comprising: Lower electrode; Upper electrode; Ferroelectric material layer; A non-ferroelectric material layer, wherein the non-ferroelectric material layer is connected to the ferroelectric material layer, and the non-ferroelectric material layer is used to undergo a crystal phase transition and thus acquire ferroelectricity when an electric field is applied; Both the ferroelectric material layer and the non-ferroelectric material layer are disposed between the lower electrode and the upper electrode, and the upper electrode and the lower electrode are used to apply an electric field to the ferroelectric material layer and the non-ferroelectric material layer.

[0006] In some embodiments, the nonferroelectric material layer is disposed between the lower electrode and the ferroelectric material layer.

[0007] In some embodiments, the nonferroelectric material layer is disposed between the upper electrode and the ferroelectric material layer.

[0008] In some embodiments, the number of nonferroelectric material layers is at least two; At least one layer of non-ferroelectric material is disposed between the lower electrode and the ferroelectric material layer; At least one layer of non-ferroelectric material is disposed between the upper electrode and the ferroelectric material layer.

[0009] In some embodiments, the thickness of the nonferroelectric material layer ranges from 1-3 nm; and / or, The thickness of the ferroelectric material layer ranges from 8 to 15 nm.

[0010] In some embodiments, the number of ferroelectric material layers is at least two; The non-ferroelectric material layer is disposed between the two ferroelectric material layers.

[0011] In some embodiments, the ferroelectric material layer comprises an orthorhombic crystalline phase, and the non-ferroelectric material layer comprises a tetragonal crystalline phase; The crystal phase transformation is described as the transformation from the tetragonal crystal phase to the orthorhombic crystal phase.

[0012] In some embodiments, the ferroelectric material layer comprises at least one of hafnium zirconium oxide and doped hafnium zirconium oxide, wherein the doped hafnium zirconium oxide is obtained by doping hafnium zirconium oxide with at least one of Si, Al, Y, Gd, La and Sr.

[0013] In some embodiments, the nonferroelectric material layer includes zirconium oxide.

[0014] In some embodiments, when the ferroelectric material layer comprises hafnium zirconium oxide, the molecular formula of the hafnium zirconium oxide is Hf. X Zr 1-X O2, where X ranges from 0.4 to 0.6.

[0015] In some implementations, X is 0.5.

[0016] In some embodiments, the method for fabricating the aforementioned ferroelectric device includes: Set the lower electrode; A ferroelectric material layer and a non-ferroelectric material layer are disposed on one side of the lower electrode, wherein the non-ferroelectric material layer is connected to the ferroelectric material layer, and the non-ferroelectric material layer is used to undergo a crystal phase transition and thus have ferroelectricity when an electric field is applied; A first device is obtained by setting an upper electrode, wherein the ferroelectric material layer and the non-ferroelectric material layer are both disposed between the lower electrode and the upper electrode; The first device is annealed to obtain a ferroelectric device.

[0017] The ferroelectric device and its fabrication method provided in this application, based on a ferroelectric material layer, incorporate a non-ferroelectric material layer that undergoes a crystal phase transition upon application of an electric field, thereby acquiring ferroelectricity. The wake-up effect caused by the phase transition continues until the fatigue effect begins, enhancing the wake-up effect of the ferroelectric device. Simultaneously, it effectively delays the fatigue effect, extending the stabilization phase and achieving a stable remanent polarization intensity over a longer electrical cycling time. This results in a slower degradation rate of the ferroelectric device, thereby improving the stability of the remanent polarization intensity and ultimately increasing the lifespan of the ferroelectric device. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of a ferroelectric device provided in an embodiment of this application; Figure 2 A schematic diagram showing the variation of the residual polarization intensity Pr of a ferroelectric device with the number of electrical cycles, provided in an embodiment of this application. Figure 3 A schematic diagram showing the degradation ratio of the residual polarization intensity Pr of a ferroelectric device provided in an embodiment of this application; Figure 4 This is a schematic flowchart illustrating a method for fabricating a ferroelectric device according to an embodiment of this application. Detailed Implementation

[0019] To better understand the technical solutions provided in the embodiments of this specification, the technical solutions of the embodiments of this specification will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments of this specification and the specific features in the embodiments are detailed descriptions of the technical solutions of the embodiments of this specification, rather than limitations on the technical solutions of this specification. In the absence of conflict, the embodiments of this specification and the technical features in the embodiments can be combined with each other.

[0020] In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, without necessarily requiring or implying any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. The term "two or more" includes two or more cases.

[0021] Ferroelectric materials exhibit spontaneous polarization even without an external electric field, and the direction of this spontaneous polarization can be reversed or redirected by an applied electric field. Specifically, when a ferroelectric material is subjected to an external electric field, it can be controlled to possess one of two stable polarities. These two stable polarities can be used to store data corresponding to logic "0" and logic "1," thus ferroelectric devices can be used in storage devices. Current research on the durability of ferroelectric devices typically focuses on the limit number of electrical cycles and uses complete breakdown as the criterion for failure. However, the residual polarization intensity of the device begins to degrade before breakdown. When the residual polarization intensity (Pr) of a ferroelectric device degrades, it can easily lead to misreading of stored information. Therefore, the stability of the residual polarization intensity during electrical cycling affects the lifespan of the ferroelectric device. However, the Pr stability of existing ferroelectric devices is generally poor.

[0022] In view of this, embodiments of this application provide a ferroelectric device and a method for its fabrication, which can improve the stability of the residual polarization intensity of the ferroelectric device and thus improve the lifespan of the ferroelectric device.

[0023] A first aspect of this application provides a ferroelectric device. Figure 1 This is a schematic diagram of the structure of a ferroelectric device provided in an embodiment of this application. Figure 1 As shown in the embodiments of this application, the ferroelectric device includes: a ferroelectric material layer 100, a non-ferroelectric material layer 200, a lower electrode 300, and an upper electrode 400; both the ferroelectric material layer 100 and the non-ferroelectric material layer 200 are disposed between the lower electrode 300 and the upper electrode 400; the upper electrode 400 and the lower electrode 300 are used to apply an electric field to the ferroelectric material layer 100 and the non-ferroelectric material layer 200. The non-ferroelectric material layer 200 is connected to the ferroelectric material layer 100, and the non-ferroelectric material layer 200 and the ferroelectric material layer 100 can be stacked together. The non-ferroelectric material layer 200 is used to undergo a crystal phase transition when an electric field is applied, thereby acquiring ferroelectricity. The non-ferroelectric material layer 200 normally does not possess ferroelectricity, but after an electric field is applied to the non-ferroelectric material layer 200, the non-ferroelectric material layer 200 undergoes an internal crystal phase transition, thereby acquiring ferroelectricity.

[0024] For example, Figure 1 The lower electrode 300 shown is a single electrode block, while the upper electrode 400 comprises multiple electrode blocks. Figure 1This is merely illustrative and not intended to be specific. The upper electrode 400 and lower electrode 300 can be fabricated using materials such as TiN, Pt, Pd, or Ru, and this application does not impose specific limitations. The ferroelectric device provided in this embodiment further includes a substrate layer 500, which includes a first substrate 510 and a second substrate 520, with the second substrate 520 disposed between the first substrate 510 and the lower electrode 300. The first substrate 510 can be fabricated using silicon, and the second substrate 520 can be fabricated using silicon oxide, and this application does not impose specific limitations. Using silicon oxide as the fabrication material for the second substrate 520 can enhance the adhesion of the film layer with the lower electrode 300, increasing the reliability of the film layer of the lower electrode 300.

[0025] The ferroelectric material layer 100 can be fabricated using ferroelectric materials and possesses ferroelectric properties. Ferroelectric devices typically operate under energized conditions. When an electric field is applied to the ferroelectric device, the polarity of the ferroelectric material layer 100 changes due to its ferroelectricity. By applying different electric fields, the ferroelectric material can be controlled to have two different polarities. These two stable polarities can be used to store data corresponding to logic "0" and logic "1". Therefore, ferroelectric devices fabricated from ferroelectric materials can be used in storage devices. When the ferroelectric device is in operation after an electric field is applied, and when the non-ferroelectric material layer 200 is stacked and connected to the ferroelectric material layer 100, the ferroelectricity of the non-ferroelectric material layer 200 after an electric field is applied, combined with the ferroelectricity of the ferroelectric material layer 100, can enhance the ferroelectric performance of the ferroelectric device. Specifically, during the use of ferroelectric devices, the remanent polarization intensity changes accordingly with the increase of the number of electric cycles. This change in remanent polarization intensity typically includes an initial stage, a stable stage, and a fatigue stage. In the initial stage, the ferroelectric device exhibits a wake-up effect, resulting in an increase in remanent polarization intensity. In the fatigue stage, the ferroelectric device exhibits a fatigue effect, resulting in a decrease in remanent polarization intensity. In the stable stage, the remanent polarization intensity remains relatively stable. The curves of remanent polarization intensity changing with the number of electric cycles differ among different ferroelectric materials. Remanent polarization intensity is an important property of ferroelectric devices or materials. After polarization treatment, the polarization intensity of the ferroelectric material does not become zero but remains at a certain value after the external electric field is removed; this value is called remanent polarization intensity Pr. The number of electric cycles can be understood as the number of polarization changes of the ferroelectric device after an applied electric field. Generally speaking, the larger the remanent polarization, the better the ferroelectric performance. Under the fatigue effect, the remanent polarization of ferroelectric devices gradually degrades. This degradation reduces the reliability of the ferroelectric device, especially for those used in memory, leading to misreading of stored information and reduced circuit robustness. Particularly when the remanent polarization drops below a certain value, stored information cannot be recognized. Adding a non-ferroelectric material layer 200 to the ferroelectric material layer 100 can moderately enhance the wake-up effect of the ferroelectric device and appropriately delay the fatigue effect, extending the stabilization phase. This results in a remanent polarization that is stable over a longer electrical cycle time. Therefore, the phase transition that occurs after applying an electric field through the non-ferroelectric material layer 200 enhances the wake-up effect of the ferroelectric device. The wake-up effect caused by the phase transition continues until the fatigue effect begins, and the two can cancel each other out, resulting in a slower degradation rate of the ferroelectric device.

[0026] The ferroelectric device provided in this application embodiment has ferroelectricity by adding a non-ferroelectric material layer 200 to the ferroelectric material layer 100. The phase transition that occurs after applying an electric field results in ferroelectricity. The wake-up effect caused by the phase transition will continue until the fatigue effect begins, which can enhance the wake-up effect of the ferroelectric device. At the same time, it can also appropriately delay the fatigue effect, prolong the stable phase, and obtain a stable residual polarization intensity over a longer electric cycling time. This leads to a slower degradation rate of the ferroelectric device, thereby improving the Pr stability of the ferroelectric device and thus increasing its lifetime.

[0027] In some implementations, such as Figure 1 As shown, the non-ferroelectric material layer 200 is disposed between the lower electrode 300 and the ferroelectric material layer 100. Figure 1 The positional relationship between the non-ferroelectric material layer 200 and the ferroelectric material layer 100 shown is merely illustrative and is not intended to limit the scope of this application.

[0028] In some embodiments, the non-ferroelectric material layer 200 may also be disposed between the upper electrode 400 and the ferroelectric material layer 100.

[0029] In the ferroelectric device provided in this application embodiment, the non-ferroelectric material layer 200 can be disposed on either side of the ferroelectric material layer 100, as long as it is in contact with the ferroelectric material layer 100 to achieve connection.

[0030] In some embodiments, the number of nonferroelectric material layers 200 is at least two; at least one nonferroelectric material layer 200 is disposed between the lower electrode 300 and the ferroelectric material layer 100; and at least one nonferroelectric material layer 200 is disposed between the upper electrode 400 and the ferroelectric material layer 100.

[0031] The ferroelectric device provided in this application embodiment has at least one non-ferroelectric material layer 200 on both sides of the ferroelectric material layer 100, that is, the ferroelectric material layer 100 is sandwiched between at least two non-ferroelectric material layers 200, which can further enhance the wake-up effect of the non-ferroelectric material layer 200 on the ferroelectric device, further delay the fatigue effect, and play a role in further delaying the degradation of the ferroelectric device.

[0032] In some embodiments, the number of ferroelectric material layers 100 is at least two; a non-ferroelectric material layer 200 is disposed between the two ferroelectric material layers 100.

[0033] The ferroelectric device provided in this application embodiment has a non-ferroelectric material layer 200 disposed between two ferroelectric material layers 100. This can further enhance the wake-up effect of the non-ferroelectric material layer 200 on the ferroelectric device, further delay the fatigue effect, and play a role in further delaying the degradation of the ferroelectric device.

[0034] In some implementations, the thickness of the nonferroelectric material layer 200 can range from 1 to 3 nm; and / or, The thickness of the ferroelectric material layer 100 can range from 8 to 15 nm.

[0035] It should be noted that in different film layer stacking schemes, for example, when the non-ferroelectric material layer 200 is disposed between two ferroelectric material layers 100 or when the ferroelectric material layer 100 is sandwiched between at least two non-ferroelectric material layers 200, different film layer thicknesses can be set according to different film layer stacking schemes. For example, when multiple ferroelectric material layers 100 are disposed, the sum of the thicknesses of all ferroelectric material layers 100 can be equal to the thickness of only one ferroelectric material layer 100, which can ensure the performance of the ferroelectric device while ensuring that the size of the ferroelectric device is not too large.

[0036] In some embodiments, the ferroelectric material layer 100 may include an orthorhombic crystal phase, and the non-ferroelectric material layer 200 may include a tetragonal crystal phase; the crystal phase transformation may be a transformation of the tetragonal crystal phase into an orthorhombic crystal phase.

[0037] The crystalline phase of the ferroelectric material layer 100 may include an orthorhombic phase (o phase). A three-dimensional crystalline phase can achieve ferroelectric properties. The ferroelectric material layer 100 may also include other crystalline phases, which are not specifically limited in this application. The non-ferroelectric material layer 200 may include a tetragonal phase (t phase). When an electric field is applied, the tetragonal phase can transform into a three-dimensional crystalline phase. The tetragonal phase is a crystalline phase that does not possess ferroelectric properties, but it can undergo a phase transition under specific conditions. These specific conditions can be electric field conditions, which are not specifically limited in this application.

[0038] The ferroelectric device provided in this application embodiment uses a tetragonal phase material to prepare a non-ferroelectric material layer 200. Furthermore, the tetragonal phase material undergoes a phase transformation when an electric field is applied, transforming from a tetragonal phase to an orthorhombic phase, thereby imparting ferroelectricity to the non-ferroelectric material layer 200. The ferroelectric non-ferroelectric material layer 200, after being subjected to an electric field, enhances the wake-up effect of the ferroelectric device through the ferroelectricity obtained from the phase transformation, while simultaneously delaying the fatigue effect, thus further delaying the degradation of the ferroelectric device, thereby improving the Pr stability of the ferroelectric device and extending its lifespan.

[0039] For example, the ferroelectric material layer 100 may include at least one of hafnium zirconium oxide, doped hafnium zirconium oxide, and hafnium silicon oxide. The doped hafnium zirconium oxide is obtained by doping hafnium zirconium oxide with at least one of Si, Al, Y, Gd, La, and Sr. The non-ferroelectric material layer 200 may include zirconium oxide or silicon. When the ferroelectric material layer 100 is prepared using hafnium zirconium oxide or doped hafnium zirconium oxide, the corresponding non-ferroelectric material layer 200 may be prepared using zirconium oxide; when the ferroelectric material layer 100 is prepared using hafnium silicon oxide, the non-ferroelectric material layer 200 may be prepared using silicon. This application does not specifically limit the application.

[0040] For example, hafnium zirconium oxide can be understood as hafnium oxide appropriately doped with zirconium oxide. Doping hafnium oxide with zirconium oxide can induce ferroelectricity. The crystal phases in hafnium zirconium oxide are mixed crystal phases, with the main crystal phase being the o phase, and also including a small amount of m phase and t phase. The crystal phases in zirconium oxide are mainly t phase. The t phase crystal phase in zirconium oxide, which serves as the non-ferroelectric material layer 200, can increase the proportion of the t phase crystal phase in the ferroelectric device. After applying an electric field, the t phase crystal phase can be transformed into the o phase crystal phase, so that the ferroelectric device has more o phase crystal phase, and thus more ferroelectricity, which can improve the Pr stability of the ferroelectric device and extend its lifespan.

[0041] When the ferroelectric material layer 100 includes hafnium zirconium oxide, the molecular formula of hafnium zirconium oxide is Hf X Zr 1-X O2, where X ranges from 0.4 to 0.6. For example, X can be 0.5, in which case the molar ratio of hafnium oxide to zirconium oxide is 1:1, which can achieve the maximum remanent polarization intensity. Other components with a ratio close to 1:1 can also be used, and this application does not make specific limitations.

[0042] For example, Figure 2 A schematic diagram showing the variation of the residual polarization intensity Pr of a ferroelectric device with the number of electrical cycles, provided in an embodiment of this application. Figure 3 This is a schematic diagram illustrating the degradation ratio of the residual polarization intensity Pr of a ferroelectric device provided in an embodiment of this application. Figure 2 As shown, the remanent polarization intensity Pr of the ferroelectric device provided in this embodiment and the existing ferroelectric device were tested under a test frequency of 1MHz, respectively, as a function of the number of electrical cycles. The unit of remanent polarization intensity Pr is μC / cm. 2 .like Figure 2As shown, the residual polarization intensity Pr exhibits two curves depending on the polarity of the ferroelectric device: a curve greater than 0 and a curve less than 0. In the curve greater than 0, the degradation of Pr is manifested as a decrease in the Pr value; in the curve less than 0, the degradation of Pr is manifested as an increase in the Pr value. Overall, the degradation of Pr is characterized by the Pr value tending towards 0. Existing ferroelectric devices with an electrical cycle number of 10... 5 At this time, the Pr value begins to approach 0. The ferroelectric device provided in this embodiment has an electrical cycle count of 10. 7 The Pr value only begins to approach 0 after a certain time, and compared to existing ferroelectric devices, the Pr value of the ferroelectric device provided in this embodiment exhibits a more gradual trend towards 0. For example... Figure 3 As shown, Figure 3 The initial, maximum, and final values ​​of the remanent polarization intensity Pr of the ferroelectric device provided in this embodiment and existing ferroelectric devices are shown. By comparing the initial and final values, the degradation rate of the remanent polarization intensity of the ferroelectric device can be calculated, which is also the degradation rate of the ferroelectric device. Figure 3 The data shown indicates that the degradation rate of the ferroelectric device provided in this embodiment is 4.6%, while the degradation rate of existing ferroelectric devices is 40.9%. The degradation rate of the ferroelectric device provided in this embodiment is much lower than that of existing ferroelectric devices, and the lower the degradation rate, the better.

[0043] The ferroelectric device provided in this application embodiment has ferroelectricity by adding a non-ferroelectric material layer 200 to the ferroelectric material layer 100. The phase transition that occurs after applying an electric field results in ferroelectricity. The wake-up effect caused by the phase transition will continue until the fatigue effect begins, which can enhance the wake-up effect of the ferroelectric device. At the same time, it can also appropriately delay the fatigue effect, prolong the stable phase, and obtain a stable residual polarization intensity over a longer electric cycling time. This leads to a slower degradation rate of the ferroelectric device, thereby improving the Pr stability of the ferroelectric device and thus increasing its lifetime.

[0044] A second aspect of this application provides a method for fabricating a ferroelectric device, used to fabricate the ferroelectric device as described in the first aspect. Figure 4 This is a schematic flowchart illustrating a method for fabricating a ferroelectric device according to an embodiment of this application. Figure 4 As shown in the embodiments of this application, the method for fabricating ferroelectric devices includes: S100: Set the lower electrode.

[0045] S200: A ferroelectric material layer and a non-ferroelectric material layer are disposed on one side of the lower electrode, wherein the non-ferroelectric material layer is connected to the ferroelectric material layer. The non-ferroelectric material layer is used to undergo a crystal phase transition and acquire ferroelectricity when an electric field is applied. The order in which the ferroelectric material layer or the non-ferroelectric material layer is disposed first can be determined based on the specific positional relationship between the ferroelectric material layer and the non-ferroelectric material layer; this step is not specifically limited.

[0046] S300: Set the upper electrode to obtain the first device, wherein the ferroelectric material layer and the non-ferroelectric material layer are both disposed between the lower electrode and the upper electrode.

[0047] S400: Anneal the first device to obtain a ferroelectric device.

[0048] Annealing transforms amorphous ferroelectric and nonferroelectric materials into crystalline states. For example, the ferroelectric material layer may include hafnium zirconium oxide, and the nonferroelectric material layer may include zirconium oxide. After annealing, the hafnium zirconium oxide changes from an amorphous state to a crystal containing the 'o' phase, and the zirconium oxide changes from an amorphous state to a crystal containing the 't' phase.

[0049] The method for fabricating ferroelectric devices provided in this application involves adding a non-ferroelectric material layer to a ferroelectric material layer. This non-ferroelectric material layer undergoes a phase transition upon application of an electric field, resulting in ferroelectricity. The wake-up effect caused by the phase transition continues until the fatigue effect begins, enhancing the wake-up effect of the ferroelectric device. Simultaneously, it effectively delays the fatigue effect, extending the stable phase and achieving a stable residual polarization intensity over a longer electrical cycling time. This slows down the degradation rate of the ferroelectric device, thereby improving its Pr stability and ultimately increasing its lifetime.

[0050] In some feasible implementations, combined with Figure 1 The fabrication method of the ferroelectric device provided in the embodiments of this application is illustrated below: A first substrate 510 and a second substrate 520 are sequentially arranged. The second substrate 520 is cleaned by immersing it in acetone and anhydrous ethanol for approximately 3 minutes each, then drying it, and finally immersing and rinsing it in deionized water for approximately 3 minutes before drying it again. The thickness of the second substrate 520 can range from 100 to 500 nm, specifically approximately 300 nm. The thickness of the first substrate 510 can range from 300 to 600 μm, specifically approximately 500 μm; this application does not impose a specific limitation.

[0051] A lower electrode 300 is disposed on the side of the second substrate 520 away from the first substrate 510. The lower electrode 300 can be made of TiN. If the lower electrode 300 is prepared by magnetron sputtering, a TiN target is used, the beam voltage is about 800V, the beam current can be about 46mA, the accelerating voltage can be about 160V, the buffer gas can be an Ar / N2 mixed gas with flow rates of 8sccm / 5sccm, and the thickness of the lower electrode 300 can be about 40nm.

[0052] A nonferroelectric material layer 200 is deposited on the side of the lower electrode 300 away from the first substrate 510. ZrO2 (zirconia) is prepared as the nonferroelectric material layer 200 using an ALD (atomic layer deposition) process, with a deposition temperature typically ranging from 280 to 300 °C. The Zr precursor is heated to 100–140 °C, deionized water is maintained at room temperature of 20 °C, and N2 can be selected as the carrier gas with a flow rate of 40–80 sccm. For example, the Hf precursor is tetra(ethylmethylamino)hafnium(IV) (also represented as TEMAH), with the chemical formula Hf(NCH3C2H5)4; the Zr precursor is tetra(ethylmethylamino)zirconia(IV) (also represented as TEMAZ), with the chemical formula Zr(NCH3CH5)4; deionized water is used as the oxygen source. The deposition rate is 0.72 Å / cycle, and the thickness of the deposited ZrO2 can be 2 nm.

[0053] A ferroelectric material layer 100 is deposited on the side of the non-ferroelectric material layer 200 away from the lower electrode 300. HZO (hafnium zirconium oxide) is prepared on ZrO2 using the ALD process, with TEMAH (tetrafnium) and TEMAZ (tetrazirconium) as precursors for Hf and Zr, and deionized water as the oxygen source. The deposition temperature is 280℃, the Zr and Hf precursors are heated to 120℃, the deionized water is maintained at room temperature (20℃), and N2 is selected as the carrier gas at a flow rate of 50 sccm. During deposition, a ZrO2 layer is grown first, followed by a HfO2 layer, and this cycle is repeated until a final ZrO2 layer caps the deposition. The deposition rate of ZrO2 is 0.72 Å / cycle (i.e., 0.72 Å per cycle), and the deposition rate of HfO2 is 0.75 Å / cycle (i.e., 0.75 Å per cycle), thus ensuring that the stoichiometric ratio of Hf and Zr is approximately 1:1, that is, the component ratio of Hf and Zr is 1:1. The ferroelectric material layer 100 is prepared by deposition to a thickness of 10 nm.

[0054] An upper electrode 400 is disposed on the side of the ferroelectric material layer 100 away from the lower electrode 300. A TiN lower electrode is fabricated on HZO using ion beam sputtering. The TiN target is set at a beam current of 800V and 46mA, with an accelerating voltage of 160V. The gas is an Ar / N2 mixture with flow rates of 8 sccm and 5 sccm, respectively. The thickness of the TiN upper electrode can be 40 nm. It should be noted that multiple electrode blocks of the upper electrode 400 can be obtained through exposure, development, and etching; this application does not impose specific limitations on this. The thickness range of both the upper electrode 400 and the lower electrode 300 can be 10-60 nm; this application also does not impose specific limitations on these variations.

[0055] The ferroelectric device was obtained by annealing at 500°C for 30 seconds under N2 atmosphere.

[0056] The steps and process parameters of the above preparation method are merely illustrative and are not intended to limit the scope of this application.

[0057] Although preferred embodiments have been described in this specification, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this specification.

[0058] Obviously, those skilled in the art can make various modifications and variations to this specification without departing from its spirit and scope. Therefore, if such modifications and variations fall within the scope of the claims and their equivalents, this specification is also intended to include such modifications and variations.

Claims

1. A ferroelectric device, characterized by, The change in the remanent polarization intensity of the ferroelectric device with increasing electrical cycling count includes an initial stage, a stable stage, and a fatigue stage. The ferroelectric device exhibits a wake-up effect in the initial stage and a fatigue effect in the fatigue stage. The ferroelectric device comprises: Lower electrode; The upper electrode comprises a plurality of electrode blocks arranged at intervals; A ferroelectric material layer, wherein the ferroelectric material layer comprises hafnium zirconium oxide; A non-ferroelectric material layer is connected to the ferroelectric material layer. The non-ferroelectric material layer is used to undergo a phase transition when an electric field is applied to acquire ferroelectric properties. The non-ferroelectric material layer includes zirconium oxide. The phase transition is a transformation from a tetragonal phase to an orthorhombic phase. The phase transition that occurs in the non-ferroelectric material layer when an electric field is applied is used to enhance the intensity of the wake-up effect of the ferroelectric device and delay the fatigue effect of the ferroelectric device. Both the ferroelectric material layer and the non-ferroelectric material layer are disposed between the lower electrode and the upper electrode. The non-ferroelectric material layer is disposed between the lower electrode and the ferroelectric material layer. The thickness of the ferroelectric material layer ranges from 8 to 15 nm, and the thickness of the non-ferroelectric material layer ranges from 1 to 3 nm. The upper electrode and the lower electrode are used to apply an electric field to the ferroelectric material layer and the non-ferroelectric material layer.

2. The ferroelectric device of claim 1, wherein, The ferroelectric material layer includes an orthorhombic crystalline phase, and the non-ferroelectric material layer includes a tetragonal crystalline phase.

3. The ferroelectric device of claim 1, wherein, The hafnium zirconium oxide has a molecular formula of Hf X Zr 1- X O2, wherein X is in a range of 0.4-0.

6.

4. The ferroelectric device of claim 3, wherein, The value of X is 0.

5.

5. A method of fabricating a ferroelectric device, characterized by, The method for preparing the ferroelectric device as described in any one of claims 1-4 comprises: Set the lower electrode; A ferroelectric material layer and a non-ferroelectric material layer are disposed on one side of the lower electrode, wherein the non-ferroelectric material layer is connected to the ferroelectric material layer, and the non-ferroelectric material layer is used to undergo a crystal phase transition and thus have ferroelectricity when an electric field is applied; A first device is obtained by setting an upper electrode, wherein the ferroelectric material layer and the non-ferroelectric material layer are both disposed between the lower electrode and the upper electrode; The first device is annealed to obtain a ferroelectric device.

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