Ferroelectric switching device, method of preparation, method of control and three-dimensional memory

Abstract

A ferroelectric switching device comprises a ferroelectric layer, a first electrode and a second electrode arranged on both sides of the ferroelectric layer for applying voltage to the ferroelectric layer, an interlayer insulation layer arranged on the second electrode, a conductive layer arranged on the interlayer insulation layer, a first signal transmission end and a second signal transmission end arranged on the conductive layer respectively, a crack extending from the ferroelectric layer along a direction perpendicular to the ferroelectric layer and penetrating through the second electrode, the interlayer insulation layer and the conductive layer, the conductive layer being divided into two independent parts by the crack, the first signal transmission end and the second signal transmission end being arranged on the two independent parts of the conductive layer respectively, and the direction of the voltage applied to the ferroelectric layer being changed to control the separation and closure of the crack. The ferroelectric switching device has higher speed, lower energy consumption and smaller chip area, and has sudden switching behavior and high ON / OFF current ratio, low contact resistance and fast signal transmission speed.

Description

Technical Field

[0001] This disclosure relates to the field of integrated circuits, and in particular to a ferroelectric switching device, a fabrication method, a control method, and a three-dimensional memory. Background Technology

[0002] With the development of microelectronics technology, the feature size of transistors on integrated circuits is constantly approaching physical limits. Further reduction in device size would lead to serious leakage problems. However, functional devices based on electromechanical coupling, due to their mechanical "on" and "off" characteristics, effectively avoid leakage problems in the "off" state. Furthermore, compared to traditional semiconductor devices, microelectromechanical devices (MEMS) offer advantages such as a high switching ratio, low power consumption, and simple structure and manufacturing processes. These advantages hold enormous potential and application value in developing high-density, low-power, and high-stability memories, transistors, and logic devices. Summary of the Invention

[0003] The technical problem to be solved by the embodiments of this disclosure is to provide a ferroelectric switching device and its preparation method, control method and three-dimensional memory.

[0004] One embodiment of this disclosure provides a ferroelectric switching device, comprising: a ferroelectric layer; a first electrode and a second electrode disposed on opposite sides of the ferroelectric layer for applying a voltage to the ferroelectric layer; an interlayer insulating layer disposed on the second electrode; a conductive layer disposed on the interlayer insulating layer; a first signal transmission terminal and a second signal transmission terminal respectively disposed on the conductive layer; wherein a crack extends from the ferroelectric layer in a direction perpendicular to the ferroelectric layer and penetrates the second electrode, the interlayer insulating layer, and the conductive layer, the conductive layer being divided into two independent parts by the crack, the first signal transmission terminal and the second signal transmission terminal being respectively disposed on the two independent parts of the conductive layer divided by the crack, and changing the direction of the voltage applied to the ferroelectric layer can control the opening and closing of the crack.

[0005] In some embodiments, the ductility of the first electrode is greater than that of the second electrode and the conductive layer.

[0006] In some embodiments, the second electrode extends along a first lateral direction, and at least a portion of the second electrode has a width in the second lateral direction that is smaller than the width of other regions. The region of the second electrode with the smallest width in the second lateral direction is located between the first signal transmission end and the second signal transmission end, and the crack is located in the region of the second electrode with the smallest width in the second lateral direction. The crack separates or closes along the first lateral direction and extends along the second lateral direction.

[0007] In some embodiments, the second electrode includes a first segment and a second segment arranged along a first transverse direction. The orthographic projection of the second segment on the ferroelectric layer is located between the orthographic projection of the first signal transmission end on the ferroelectric layer and the orthographic projection of the second signal transmission end on the ferroelectric layer. The width of the second segment in the second transverse direction is smaller than the width of the first segment in the second transverse direction. The crack is located in the second segment.

[0008] In some embodiments, the boundary between the first segment and the second segment is located between the first signal transmission end and the second signal transmission end, and the crack is located at the boundary between the first segment and the second segment.

[0009] In some embodiments, the second electrode includes two first segments and one second segment, with the two first segments located at opposite ends of the second segment in a first transverse direction, and the crack located at the junction of the second segment and one of the first segments.

[0010] In some embodiments, the second segment includes a plurality of sub-segments with different widths in the second transverse direction, and the crack is located at the sub-segment with the smallest width.

[0011] In some embodiments, the interlayer insulating layer covers a portion of the surface of the second electrode, and a first conductive terminal is provided on the exposed surface of the second electrode.

[0012] In some embodiments, the second electrode is provided with two first conductive terminals, which are respectively disposed on both sides of the crack.

[0013] In some embodiments, the ferroelectric layer covers a portion of the surface of the first electrode, and a second conductive terminal is provided on the exposed surface of the first electrode.

[0014] In some embodiments, the orthogonal projection of the second electrode onto the ferroelectric layer overlaps the orthogonal projection of the conductive layer onto the ferroelectric layer.

[0015] In some embodiments, the material of the first electrode is the same as the material of the first signal transmission terminal and the second signal transmission terminal.

[0016] In some embodiments, the material of the second electrode is the same as the material of the conductive layer.

[0017] In some embodiments, the material of the conductive layer includes an intermetallic alloy.

[0018] In some embodiments, the intermetallic alloy material includes MnPt or FePt.

[0019] Another aspect of this disclosure provides a method for fabricating a ferroelectric switching device, comprising: providing a substrate; forming a first electrode, a ferroelectric layer, a second electrode, an interlayer insulating layer, a conductive layer, and a first signal transmission terminal and a second signal transmission terminal on the surface of the substrate, wherein the first signal transmission terminal and the second signal transmission terminal are both disposed on the conductive layer and are independent of each other; forming a crack, the crack extending from the ferroelectric layer in a direction perpendicular to the ferroelectric layer and penetrating the second electrode, the interlayer insulating layer, and the conductive layer between the first signal transmission terminal and the second signal transmission terminal, wherein the conductive layer is divided into two independent parts by the crack, and the first signal transmission terminal and the second signal transmission terminal are respectively disposed on the two independent parts of the conductive layer divided by the crack.

[0020] In some embodiments, the method of forming a crack includes: applying a polarization voltage to the ferroelectric layer via the first electrode and the second electrode, such that the polarization direction of the ferroelectric domains of the ferroelectric layer is the same as the direction of the polarization voltage; and applying a reversal voltage to the ferroelectric layer via the first electrode and the second electrode, wherein the reversal voltage is opposite in polarity to the polarization voltage.

[0021] In another aspect, this disclosure provides a control method for the ferroelectric switching device as described above, comprising: applying a first voltage to the ferroelectric layer via the first electrode and the second electrode to control the separation of the crack; applying a second voltage to the ferroelectric layer via the first electrode and the second electrode to control the closure of the crack; thereby achieving electrical insulation and electrical conduction between the first signal transmission terminal and the second signal transmission terminal, wherein the first voltage and the second voltage have opposite polarities.

[0022] In another aspect, embodiments of this disclosure also provide a three-dimensional memory, including the ferroelectric switching device described above.

[0023] In some embodiments, the three-dimensional memory includes a plurality of memory cells arrayed in a three-dimensional space to form a plurality of memory strings. Each memory string is correspondingly provided with the ferroelectric switching device, wherein the first electrode and the second electrode of the ferroelectric switching device are electrically connected to the corresponding drain selection line, the first signal transmission terminal is electrically connected to the bit line, and the second signal transmission terminal is electrically connected to the memory string; or, the first electrode and the second electrode of the ferroelectric switching device are electrically connected to the corresponding source selection line, the first signal transmission terminal is electrically connected to the memory string, and the second signal transmission terminal is electrically connected to the source line.

[0024] The conductive layer of the ferroelectric switching device provided in this embodiment is divided into two independent parts by a crack. The separation and closure of the crack can be controlled by changing the direction of the voltage applied to the ferroelectric layer, thereby realizing the "on" and "off" functions of the ferroelectric switching device. For example, applying a first voltage to the ferroelectric layer through the first and second electrodes can control the closure of the crack, and the first signal transmission end and the second signal transmission end can be electrically connected through the conductive layer to realize the "on" function of the ferroelectric switching device; applying a second voltage to the ferroelectric layer through the first and second electrodes can control the separation of the crack, and the first signal transmission end and the second signal transmission end can be electrically insulated through the conductive layer to realize the "off" function of the ferroelectric switching device.

[0025] The ferroelectric switching device provided in this disclosure utilizes the separation and closure of cracks to achieve "off" and "on" functions. Compared with traditional MOSFET switches, it has higher speed, lower energy consumption, and smaller chip area. Moreover, the manufacturing process is simple, compatible with Fe-NAND technology, low cost, and high economic benefits. Furthermore, the ferroelectric-crack-based ferroelectric switching device has abrupt switching behavior and a high ON / OFF current ratio. The large contact area of ​​the metal contact interface results in low contact resistance and fast signal transmission speed. Attached Figure Description

[0026] Figure 1 This is a top view schematic diagram of the ferroelectric switching device provided in the first embodiment of this disclosure;

[0027] Figure 2 It is along Figure 1 A schematic diagram of the cross-section of line C-C' shown;

[0028] Figure 3 This is another top view schematic diagram of the ferroelectric switching device provided in the first embodiment of this disclosure;

[0029] Figure 4 It is along Figure 3 A schematic diagram of the cross-section of line C-C' shown;

[0030] Figure 5 This is a top view schematic diagram of the ferroelectric switching device provided in the second embodiment of this disclosure;

[0031] Figure 6 This is a scanning electron microscope image of the ferroelectric switching device provided in the second embodiment of this disclosure when the second electrode is exposed;

[0032] Figure 7 This is a top view schematic diagram of the ferroelectric switching device provided in the third embodiment of this disclosure;

[0033] Figure 8This is an electric field intensity distribution diagram of the ferroelectric switching device with its second electrode exposed according to an embodiment of this disclosure, wherein (b) is an enlarged view of (a);

[0034] Figure 9 This is a schematic diagram of the steps in the fabrication method of the ferroelectric switching device provided in the embodiments of this disclosure;

[0035] Figures 10A to 10C This is a schematic diagram of the device structure formed by the main steps of the fabrication method of the ferroelectric switching device provided in the embodiments of the present invention;

[0036] Figure 11A This is a schematic diagram of a triangular cyclic voltage applied to a ferroelectric layer according to an embodiment of this disclosure;

[0037] Figure 11B This is a schematic diagram of a pulsed cyclic voltage applied to a ferroelectric layer according to an embodiment of this disclosure;

[0038] Figure 12 These are scanning electron microscope (SEM) images of the ferroelectric switching device provided in the embodiments of this disclosure, wherein (a) is an SEM image of crack closure and (b) is an SEM image of crack separation;

[0039] Figure 13 This is a schematic diagram illustrating an application of a ferroelectric switching device in a three-dimensional memory provided in this embodiment of the disclosure;

[0040] Figure 14 This is a top view schematic diagram of the ferroelectric switching device provided in the fourth embodiment of this disclosure. Detailed Implementation

[0041] To make the objectives, technical means, and effects of the embodiments of this disclosure clearer, the embodiments of this disclosure will be further described below with reference to the accompanying drawings. It should be understood that the embodiments described herein are merely some embodiments of this disclosure, not all embodiments, and are not intended to limit this disclosure. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without inventive effort are within the scope of protection of this disclosure.

[0042] Figure 1 and Figure 3 This is a top view schematic diagram of the ferroelectric switching device provided in the first embodiment of this disclosure. Figure 2 It is along Figure 1 A schematic diagram of the cross-section of line C-C' shown. Figure 4 It is along Figure 3 A schematic diagram of the cross-section of line C-C' shown.

[0043] Please see Figures 1-4The ferroelectric switching device includes a ferroelectric layer 10, a first electrode 20, a second electrode 30, an interlayer insulating layer 40, a conductive layer 50, a first signal transmission terminal 60, and a second signal transmission terminal 70. The first electrode 20 and the second electrode 30 are disposed on opposite sides of the ferroelectric layer 10 for applying voltage to the ferroelectric layer 10. The interlayer insulating layer 40 is disposed on the second electrode 30, and the conductive layer 50 is disposed on the interlayer insulating layer 40. The first signal transmission terminal 60 and the second signal transmission terminal 70 are respectively disposed on the conductive layer 50. The signal transmission terminal 60 is located perpendicular to the ferroelectric layer 10 (e.g., from the ferroelectric layer 10 along a direction perpendicular to the ferroelectric layer 10). Figure 2 A crack A extends (in the Z direction) through and penetrates the second electrode 30, the interlayer insulating layer 40, and the conductive layer 50 between the first signal transmission end 60 and the second signal transmission end 70, and the conductive layer 50 is divided into two independent parts by the crack A. The first signal transmission end 60 and the second signal transmission end 70 are respectively disposed on the two independent parts of the conductive layer 50 divided by the crack A. Changing the direction of the voltage applied to the ferroelectric layer 40 can control the opening and closing of the crack A, achieving electrical insulation and electrical conduction between the first signal transmission end 60 and the second signal transmission end 70, thereby realizing the opening and closing of the ferroelectric switching device.

[0044] The operation process of the ferroelectric switching device provided in this embodiment is as follows: Please refer to... Figure 1 and Figure 2 When a first voltage U1 is applied to the first electrode 20 and the second electrode 30, the crack A separates, and the conductive layer 50 is divided into two insulated parts. The first signal transmission terminal 60 and the second signal transmission terminal 70 are electrically insulated, thus realizing the "off" function of the ferroelectric switching device. Please refer to... Figure 3 and Figure 4 When a second voltage U2 is applied to the first electrode 20 and the second electrode 30, the crack A closes, the two parts of the conductive layer 50 come into contact, and the first signal transmission end 60 and the second signal transmission end 70 are electrically connected, thereby realizing the "on" function of the ferroelectric switching device.

[0045] Wherein, the first voltage U1 and the second voltage U2 have opposite polarities. For example, in some embodiments, the first voltage U1 is perpendicular to the device direction (e.g., Figure 2 The first voltage U1 is a positive voltage in the Z direction, and the second voltage U2 is a negative voltage in the direction perpendicular to the device. In other embodiments, the first voltage U1 is a negative voltage in the direction perpendicular to the device, and the second voltage U2 is a positive voltage in the direction perpendicular to the device.

[0046] The conductive layer 50 of the ferroelectric switching device provided in this embodiment is divided into two independent parts by a crack A. Changing the direction of the voltage applied to the ferroelectric layer 10 controls the separation and closure of the crack A, thereby realizing the "on" and "off" operation of the ferroelectric switching device. Compared to metal-oxide-semiconductor field-effect transistor (MOSFET) switches, the ferroelectric switching device provided in this embodiment has higher speed, lower power consumption, and smaller chip area. It also has a simple manufacturing process, is compatible with Fe-NAND flash memory technology, has low cost, and high economic benefits. Furthermore, the ferroelectric-crack based ferroelectric switching device exhibits abrupt switching behavior and a high ON / OFF current ratio. The entire conductive layer 50 serves as a conductive channel. At crack A, the metal contact interface (fracture surface) of the two separated parts of the conductive layer has a large contact area, resulting in low contact resistance and fast signal transmission speed.

[0047] In the direction perpendicular to the ferroelectric layer 10 (e.g.) Figure 2 In the Z-direction, the first electrode 20 is located below the ferroelectric layer 10, meaning the second electrode 20 is disposed on the lower surface of the ferroelectric layer 10. In this embodiment, the first electrode 20 is disposed on a substrate 100, so the first electrode 20 is located on the substrate 100, and the ferroelectric layer 10 is located on the first electrode 20.

[0048] If the first electrode 20 has good ductility, then when a crack forms, the crack will not extend to the first electrode 20, thereby maintaining the integrity of the first electrode 20 and improving the lifespan of the ferroelectric switching device. The first electrode 20 can be a metal electrode, such as a Pt, Au, Cu, or Ag electrode.

[0049] In the direction perpendicular to the ferroelectric layer 10 (e.g.) Figure 2 (in the Z direction), the second electrode 30 is located above the ferroelectric layer 10, that is, the second electrode 30 is disposed on the upper surface of the ferroelectric layer 10.

[0050] The second electrode 30 has lower ductility; specifically, the first electrode 20 has higher ductility than the second electrode 30. Therefore, when a crack forms, the crack will not extend to the first electrode 20, but will extend from the ferroelectric layer 10 and penetrate the second electrode 30, and further extend to the conductive layer 50. The material of the second electrode 30 can be an intermetallic alloy, such as MnPt or FePt.

[0051] The interlayer insulating layer 40 is located on the second electrode 30, that is, in the direction perpendicular to the ferroelectric layer 10 (e.g., Figure 2 (in the Z-direction), the interlayer insulating layer 40 is disposed on the upper surface of the second electrode 30. The interlayer insulating layer 40 includes, but is not limited to, oxide layers, nitride layers, high-k dielectric layers, etc. For example, the oxide layer may be an aluminum oxide layer. The interlayer insulating layer 40 serves to electrically isolate the second electrode 30 from the conductive layer 50. The ductility of the interlayer insulating layer 40 is less than that of the first electrode 30. Therefore, when a crack forms, the crack will also extend and penetrate the interlayer insulating layer 40, and further extend to the conductive layer 50.

[0052] The conductive layer 50 is located on the interlayer insulating layer 40, that is, in the direction perpendicular to the ferroelectric layer 10 (e.g., Figure 1 In the Z-direction, the conductive layer 50 is disposed on the upper surface of the interlayer insulating layer 40. If the ductility of the conductive layer 50 is less than that of the first electrode 20, then when crack A is formed, crack A will not extend to the first electrode 20, but will extend and penetrate the conductive layer 50, dividing the conductive layer 50 into two independent parts that are electrically isolated from each other. Furthermore, if the ductility of the conductive layer 50 is less than or equal to that of the second electrode 30, that is, if the ductility of the second electrode 30 is greater than or equal to that of the conductive layer 50, then when crack A is formed, crack A can extend from the ferroelectric layer 10 and penetrate the conductive layer 50.

[0053] The conductive layer 50 can be made of an intermetallic alloy, such as MnPt or FePt. In this embodiment, the material of the conductive layer 50 is the same as that of the second electrode 30, and since both have similar ductility, it is convenient to select an appropriate voltage to further ensure that the crack A can penetrate both the second electrode 30 and the conductive layer 50. In other embodiments of this disclosure, the conductive layer 50 may be made of a different material than the second electrode 30 but have similar ductility to further avoid the situation where the crack A only penetrates the second electrode 30 without penetrating the conductive layer 50.

[0054] In this embodiment, the first signal transmission terminal 60 serves as the input terminal of the electrical signal of the ferroelectric switching device, and the second signal transmission terminal 70 serves as the output terminal of the electrical signal of the ferroelectric switching device. The first signal transmission terminal 60 and the second signal transmission terminal 70 are independent of each other, meaning they are not directly connected. When the crack closes, the electrical signal that needs to be transmitted through the ferroelectric switching device is input through the first signal transmission terminal 60, conducted through the conductive layer 50, and then output through the second signal transmission terminal 70. When crack A separates, the electrical signal that needs to be transmitted through the ferroelectric switching device is input through the first signal transmission terminal 60. Due to the influence of crack A, the conductive layer 50 cannot conduct the electrical signal, so the electrical signal that needs to be transmitted through the ferroelectric switching device cannot be output through the second signal transmission terminal 70. In other embodiments, the first signal transmission terminal 60 can serve as the output terminal of the electrical signal of the ferroelectric switching device, and the second signal transmission terminal 70 can serve as the input terminal of the electrical signal of the ferroelectric switching device.

[0055] Furthermore, the first signal transmission terminal 60 and the second signal transmission terminal 70 can be metal terminals, and their materials include, but are not limited to, Pt, Au, Cu, or Ag. In this embodiment, the material of the first electrode 20 is the same as the material of the first signal transmission terminal 60 and the second signal transmission terminal 70. Therefore, the ductility of the first signal transmission terminal 60 and the second signal transmission terminal 70 is the same as that of the first electrode 20, which can further prevent crack A from penetrating the first signal transmission terminal 60 and the second signal transmission terminal 70, thereby improving the reliability and lifespan of the ferroelectric switching device.

[0056] Furthermore, in this embodiment, in order to ensure that the crack A can divide the conductive layer 50 into two completely broken parts, in the direction perpendicular to the ferroelectric layer (e.g., Figure 2 (in the opposite direction of the Z-direction), the orthogonal projection of the second electrode 30 on the ferroelectric layer 10 covers the orthogonal projection of the conductive layer 50 on the ferroelectric layer 10, that is, the orthogonal projection of the conductive layer 50 on the ferroelectric layer 10 is within the range of the orthogonal projection of the second electrode 30 on the ferroelectric layer 10. If the orthogonal projection of the conductive layer 50 on the ferroelectric layer 10 is outside the range of the orthogonal projection of the second electrode 30 on the ferroelectric layer 10, then in the second lateral direction (e.g., in the opposite direction of the Z-direction), the orthogonal projection of the second electrode 30 on the ferroelectric layer 10 covers the orthogonal projection of the conductive layer 50 on the ferroelectric layer 10, that is, the orthogonal projection of the conductive layer 50 on the ferroelectric layer 10 is within the range of the orthogonal projection of the second electrode 30 on the ferroelectric layer 10. Figure 1 Cracks A may exist in the Y direction (as shown) that only partially separate the conductive layer 50, but do not completely separate the conductive layer 50 into two broken parts, thus failing to achieve electrical isolation between the first signal transmission end 60 and the second signal transmission end 70.

[0057] Furthermore, in this embodiment, the interlayer insulating layer 40 covers a portion of the surface of the second electrode 30, meaning that the interlayer insulating layer 40 does not cover the entire surface of the second electrode 30, and a portion of the surface of the second electrode 30 is exposed. Therefore, the exposed surface of the second electrode 30 can serve as an electrical connection surface. For example, in some embodiments of this disclosure, a first conductive terminal 31 is provided on the exposed surface of the second electrode 30. The first conductive terminal 31 can be connected to a voltage supply circuit so that the voltage supply circuit provides a potential to the second electrode 30 through the first conductive terminal 31. In other embodiments of this disclosure, the first conductive terminal 31 may not be provided, and the voltage supply circuit may be directly connected to the exposed surface of the second electrode 30.

[0058] In this embodiment, a first conductive terminal 31 is provided on the exposed surface of the second electrode 30. In other embodiments of this disclosure, two first conductive terminals 31 are provided on the second electrode 30, and the two first conductive terminals 31 are respectively located on both sides of the crack A. For a detailed illustration, please refer to [the specific illustration]. Figure 14 Specifically, it can be determined whether crack A penetrates the second electrode 30 by applying voltage to the two first conductive terminals 31 and testing the current value between the two first conductive terminals 31.

[0059] Furthermore, in this embodiment, the ferroelectric layer 10 covers a portion of the surface of the first electrode 20. That is, the ferroelectric layer 10 does not cover the entire surface of the first electrode 20, and a portion of the surface of the first electrode 20 is exposed. The exposed surface of the first electrode 20 can then serve as an electrical connection surface. For example, in some embodiments of this disclosure, a second conductive terminal 21 is provided on the exposed surface of the first electrode 20. The second conductive terminal 21 is electrically connected to a voltage supply circuit, so that the voltage supply circuit provides a potential to the first electrode 20 through the second conductive terminal 21. In other embodiments of this disclosure, the second conductive terminal 21 may not be provided, and the voltage supply circuit may be directly connected to the exposed surface of the first electrode 20.

[0060] The inventors discovered that cracks in ferroelectric switching devices tend to appear in the narrower region of the second electrode. Through in-depth research, the inventors found that this phenomenon occurs because when a voltage is applied to the ferroelectric layer via the first and second electrodes, the electric field strength is higher at the narrower location of the second electrode, causing stress concentration in the ferroelectric layer at that location, making it prone to crack formation.

[0061] In view of the above reasons, in order to further control the location of cracks and improve the reliability of ferroelectric switching devices, some embodiments of this disclosure provide a ferroelectric switching device in which the second electrode extends along a first transverse direction, and at least a portion of the second electrode has a width in a second transverse direction that is smaller than the width of other regions. The region of the second electrode with the smallest width in the second transverse direction is located between the first signal transmission end and the second signal transmission end, and the crack is located in the region of the second electrode with the smallest width in the second transverse direction. The crack either separates or closes along the first transverse direction and extends along the second transverse direction.

[0062] Specifically, in some embodiments, the second electrode includes a first segment and a second segment arranged along a first transverse direction. The second segment is located between the first signal transmission end and the second signal transmission end. The orthographic projection of the second segment onto the ferroelectric layer is located between the orthographic projections of the first signal transmission end and the second signal transmission end onto the ferroelectric layer. The width of the second segment in a second transverse direction is smaller than the width of the first segment in the second transverse direction. The crack is located in the second segment. For example, please refer to... Figure 5 This is a top view schematic diagram of the ferroelectric switching device provided in the second embodiment of this disclosure. In this embodiment, the second electrode 30 includes two first segments 301 and one second segment 302. In the first transverse direction (X direction), the two first segments 301 are respectively located at both ends of the second segment 302, forming a bridge-shaped structure. The second segment 302 is located between the first signal transmission end 60 and the second signal transmission end 70. The width of the second segment 302 in the second transverse direction (Y direction) is smaller than the width of the first segment 301 in the second transverse direction (Y direction). The crack A is located in the region between the first signal transmission end 60 and the second signal transmission end 70 (e.g., Figure 5 (E region in the middle), and located on the second segment 302.

[0063] Furthermore, through long-term analysis and research, the inventors discovered that crack A tends to exist at the boundary between the narrowest segment of the second electrode 30 and its adjacent segment. For example, as... Figure 5 As shown, in this embodiment, the boundary between the first segment 301 and the second segment 302 is located in the area between the first signal transmission end 60 and the second signal transmission end 70 (e.g., Figure 5 In region E), the crack A is located at the boundary between the first segment 301 and the second segment 302. The boundary between the first segment 301 and the second segment 302 includes the position where the first segment 301 and the second segment 302 intersect and a portion of the second segment 302 adjacent to the intersection.

[0064] Once a crack is generated in the ferroelectric layer 10, it will not generate a second crack because the stress is released. Therefore, in this embodiment, the crack A is only located at the junction of the second segment 302 and one of the first segments 301, and there is no crack at the junction of the second segment 302 and the other first segment 301.

[0065] Figure 6 These are scanning electron microscope (SEM) images of the ferroelectric switching device provided in the second embodiment of this disclosure when the second electrode is exposed, wherein the scale bars of (a), (b), (c), (d), (e), and (f) are 10 micrometers, 5 micrometers, and 1 micrometer, respectively. In (c) and (e), the crack is not clear and is indicated by dashed lines. Figure 6 It can be seen that cracks will inevitably form in the area where the width of the second electrode is the smallest (as indicated by arrow A in the figure). The ferroelectric switching device provided in this embodiment has high reliability.

[0066] In the second embodiment, in the region between the first signal transmission end 60 and the second signal transmission end 70, the width of the second segment 302 is the same in the second transverse direction (Y direction). However, in other embodiments of this disclosure, in the region between the first signal transmission end 60 and the second signal transmission end 70, the second segment 302 includes multiple sub-segments with different widths in the second transverse direction (Y direction), and the crack A is located in the sub-segment with the smallest width. Figure 7 As shown, this is a top view of the ferroelectric switching device provided in the third embodiment of this disclosure. The second section 302 includes three sub-sections 302A, 302B and 302C arranged along the first transverse direction (X direction). The width of the sub-section 302B in the second transverse direction (Y direction) is smaller than the width of the sub-sections 302A and 302C in the second transverse direction (Y direction). The crack A is located at the junction of the sub-section 302B and the sub-section 302A. In other embodiments, the crack A may also be located at the junction of the sub-section 302B and the sub-section 302C.

[0067] It is understood that in some embodiments, in the region between the first signal transmission end 60 and the second signal transmission end 70, regardless of how the width of the second electrode 30 changes, it must be greater than or equal to the width of the conductive layer 50, so as to ensure that the conductive layer 50 can be completely separated by the crack.

[0068] In the above embodiments, the width of the second electrode 30 in the second transverse (Y direction) changes in the form of segments. In other embodiments of this disclosure, the width of the second electrode can also gradually decrease from both ends to the middle in the first transverse (X direction), as long as the width of the area of ​​the second electrode 30 located between the first signal transmission end 60 and the second signal transmission end 70 is less than the width of the area located outside the first signal transmission end 60 and the second signal transmission end 70.

[0069] Figure 8 This is an electric field intensity distribution diagram of the ferroelectric switching device with its second electrode exposed according to an embodiment of this disclosure, wherein (b) is an enlarged view of (a), from... Figure 8 It can be seen that the color is darker at the junction of different width sections of the second electrode, indicating that the electric field strength is strongest at that point (as shown in the area marked by the dashed ellipse in (b)). Cracks are more likely to occur in this area.

[0070] This disclosure also provides a method for fabricating the above-described ferroelectric switching device. Please refer to [link to relevant documentation]. Figure 9 This is a schematic diagram of the steps of a method for fabricating a ferroelectric switching device provided in an embodiment of this disclosure. The fabrication method includes: step S901, providing a substrate; step S902, forming a first electrode, a ferroelectric layer, a second electrode, an interlayer insulating layer, a conductive layer, and a first signal transmission terminal and a second signal transmission terminal on the surface of the substrate, wherein the first signal transmission terminal and the second signal transmission terminal are both disposed on the conductive layer and are independent of each other; step S903, forming a crack, wherein the crack extends from the ferroelectric layer in a direction perpendicular to the ferroelectric layer and penetrates the second electrode, the interlayer insulating layer, and the conductive layer between the first signal transmission terminal and the second signal transmission terminal, and the conductive layer is divided into two independent parts by the crack.

[0071] Figures 10A to 10C This is a schematic diagram of the device structure formed by the main steps of the fabrication method of the ferroelectric switching device provided in the embodiments of the present invention.

[0072] Please refer to step S901 and Figure 10A Substrate 100 is provided.

[0073] The substrate 100 can be a Si substrate, a Ge substrate, a SiGe substrate, an SOI (Silicon on Insulator) substrate, or a GOI (Germanium on Insulator) substrate, etc. In this embodiment, the substrate 100 is preferably a Si substrate, used to support the device structure thereon.

[0074] Please refer to step S902 and Figure 10BA first electrode 20, a ferroelectric layer 10, a second electrode 30, an interlayer insulating layer 40, a conductive layer 50, and a first signal transmission terminal 60 and a second signal transmission terminal 70 are formed on the surface of the substrate 100. The first signal transmission terminal 60 and the second signal transmission terminal 70 are both disposed on the conductive layer 50 and are independent of each other.

[0075] A first electrode material layer can be formed on the surface of the substrate 100 using processes such as chemical vapor deposition, atomic layer deposition, pulsed laser deposition, and molecular beam epitaxy. The first electrode material layer is then patterned using photolithography and etching processes to form the first electrode 20. The first electrode 20 can be a metal electrode, such as a Pt, Au, Cu, or Ag electrode.

[0076] A ferroelectric material layer can be formed on the surface of the first electrode 20 using processes such as chemical vapor deposition, atomic layer deposition, pulsed laser deposition, and molecular beam epitaxy. The ferroelectric material layer is then patterned using photolithography and etching processes to form the ferroelectric layer 10. In this embodiment, the material of the ferroelectric layer 10 is HfZrOx, which is suitable for hafnium-based complementary metal-oxide-semiconductor (CMOS) compatible ferroelectric NAND (Fe-NAND) flash memory, simplifying the fabrication process. In other embodiments of this disclosure, the material of the ferroelectric layer 10 can also be lead magnesium niobate-lead titanate (PMN-PT), lead zirconate titanate (PZT), lead indium niobate-lead titanate (PIN-PT), lead magnesium niobate-lead zirconate titanate-lead titanate (PMN-PZT-PT), BaTiO3 (BTO), etc.

[0077] A second electrode material layer can be formed on the surface of the ferroelectric layer 10 using processes such as chemical vapor deposition, atomic layer deposition, pulsed laser deposition, and molecular beam epitaxy. The second electrode material layer is then patterned using photolithography and etching processes to form the second electrode 30. The shape of the second electrode 30 can be the same as that described in the ferroelectric switching device. The material of the second electrode 30 can be an intermetallic alloy, such as MnPt or FePt. The ductility of the second electrode 30 is less than that of the first electrode 20.

[0078] An interlayer insulating material layer can be formed on the second electrode 30 using processes such as chemical vapor deposition, atomic layer deposition, pulsed laser deposition, and molecular beam epitaxy. Then, the interlayer insulating material layer is patterned using photolithography and etching processes to form an interlayer insulating layer 40. The interlayer insulating layer 40 may cover not only the second electrode 30 but also the exposed surface of the ferroelectric layer 10. The interlayer insulating layer 40 includes, but is not limited to, oxide layers, nitride layers, and high-k dielectric layers; for example, the oxide layer may be an aluminum oxide layer.

[0079] A conductive material layer can be formed on the interlayer insulating layer 40 using processes such as chemical vapor deposition, atomic layer deposition, pulsed laser deposition, and molecular beam epitaxy. The conductive material layer is then patterned using photolithography and etching processes to form a conductive layer 50. The material of the conductive layer 50 can be an intermetallic alloy, such as MnPt or FePt. The ductility of the conductive layer 50 is less than that of the first electrode 20. Further, in this embodiment, the material of the conductive layer 50 is the same as that of the second electrode 30. In other embodiments of this disclosure, the material of the conductive layer 50 may be different from that of the second electrode 30 but have similar ductility.

[0080] A signal transmission material layer can be formed on the conductive layer 50 using processes such as chemical vapor deposition, atomic layer deposition, pulsed laser deposition, and molecular beam epitaxy. The signal transmission material layer is then patterned using photolithography and etching processes to form a first signal transmission terminal 60 and a second signal transmission terminal 70. The first signal transmission terminal 60 and the second signal transmission terminal 70 are independent of each other.

[0081] Please refer to step S903 and Figure 10C Crack A is formed, and crack A originates from the ferroelectric layer 10 along a direction perpendicular to the ferroelectric layer 10 (e.g., ...). Figure 10C The crack extends in the Z direction and penetrates the second electrode 20, the interlayer insulating layer 40, and the conductive layer 50 between the first signal transmission end 60 and the second signal transmission end 70, and the conductive layer 50 is divided into two independent parts by the crack. The first signal transmission end 60 and the second signal transmission end 70 are respectively disposed on the two independent parts of the conductive layer 50 divided by the crack A.

[0082] This disclosure also provides a method for forming the crack, the method comprising the following steps:

[0083] Pre-polarization: A polarization voltage is applied to the ferroelectric layer 10 via the first electrode 20 and the second electrode 30, so that the polarization direction of the ferroelectric domains of the ferroelectric layer 10 is the same as the direction of the polarization voltage.

[0084] For the ferroelectric layer 10, when no polarization voltage is applied, i.e., no external electric field is applied, the ferroelectric domains are randomly distributed in the ferroelectric layer 10. However, when a polarization voltage is applied, i.e., an external electric field is applied, the ferroelectric domains along the direction of the electric field grow, the ferroelectric domains against the direction of the electric field disappear, and the ferroelectric domains distributed in other directions rotate to the direction of the electric field, eventually forming ferroelectric domains aligned with the direction of the electric field. The direction of the electric field is the same as the direction of the polarization voltage. In some embodiments, the electric field strength formed by the pre-polarization voltage is greater than the coercive field of the ferroelectric domains, forming ferroelectric domains aligned with the direction of the electric field.

[0085] Flip: A flip voltage is applied to the ferroelectric layer 10 via the first electrode 20 and the second electrode 30, the flip voltage being opposite in polarity to the polarization voltage.

[0086] When the voltage changes from the polarization voltage to the reversal voltage, the direction of the applied electric field changes because the reversal voltage has the opposite polarity to the polarization voltage. Consequently, the ferroelectric domains in the ferroelectric layer 10 also reverse. Due to the pinning effect of defects and dopants within the ferroelectric layer on the domain walls, stress is generated on the ferroelectric domain walls, leading to the formation of crack A at the stress concentration point. In some embodiments, the electric field strength generated by the reversal voltage is greater than the coercive field of the ferroelectric domains, enabling the ferroelectric domains to reverse.

[0087] The crack A penetrates the second electrode 30, the interlayer insulation layer 40, and the conductive layer 50, dividing the conductive layer 50 into two electrically isolated parts. When using the ferroelectric switching device, the connection and disconnection of the two parts of the conductive layer 50 are achieved by controlling the opening and closing of the crack, thereby realizing the electrical insulation and connection between the first signal transmission terminal 60 and the second signal transmission terminal 70, and thus realizing the "off" and "on" functions of the ferroelectric switching device.

[0088] The method for fabricating a ferroelectric switch device provided in this disclosure can fabricate a ferroelectric switch device with cracks. By changing the direction of the voltage applied to the ferroelectric layer 10, the separation and closure of the crack A can be controlled, thereby realizing the "on" and "off" of the ferroelectric switch device.

[0089] This disclosure also provides a control method for the above-mentioned ferroelectric switching device. The control method includes:

[0090] like Figure 2 As shown, a first voltage U1 is applied to the ferroelectric layer 10 via the first electrode 20 and the second electrode 30 to control the separation of the crack A. The conductive layer 50 is divided into two insulated parts. The first signal transmission terminal 60 and the second signal transmission terminal 70 are electrically insulated, realizing the "off" function of the ferroelectric switch device. When the first voltage U1 is applied to the ferroelectric layer 10 via the first electrode 20 and the second electrode 30, the direction of the applied electric field changes, and the ferroelectric domains in the ferroelectric layer 10 flip accordingly. Due to the pinning effect of defects and dopants in the ferroelectric layer on the domain walls, stress is generated on the ferroelectric domain walls. Crack A is formed at the stress concentration point, realizing the "off" function of the ferroelectric switch device.

[0091] like Figure 4As shown, a second voltage U2 is applied to the ferroelectric layer 10 via the first electrode 20 and the second electrode 30, controlling the closure of crack A. The two parts of the conductive layer 50 come into contact, and the first signal transmission terminal 60 and the second signal transmission terminal 70 are electrically connected, realizing the "on" function of the ferroelectric switching device. When the second voltage U2 is applied to the ferroelectric layer 10 via the first electrode 20 and the second electrode 30, the ferroelectric domains are flipped again, the stress originally present at the ferroelectric domain walls dissipates, crack A closes, and the "on" function of the ferroelectric switching device is realized.

[0092] Wherein, the first voltage U1 and the second voltage U2 have opposite polarities. For example, in some embodiments, the first voltage U1 is perpendicular to the device direction (e.g., Figure 2 The first voltage U1 is a positive voltage in the Z direction, and the second voltage U2 is a negative voltage in the direction perpendicular to the device. In other embodiments, the first voltage U1 is a negative voltage in the direction perpendicular to the device, and the second voltage U2 is a positive voltage in the direction perpendicular to the device.

[0093] In some embodiments, the electric field strength formed by the first voltage U1 and the second voltage U2 is greater than the coercive field of the ferroelectric domains, enabling the ferroelectric domains to flip.

[0094] In some embodiments, the polarity of the first voltage U1 is the same as the polarity of the switching voltage used in the fabrication of the ferroelectric switching device, and the polarity of the second voltage U2 is the same as the polarization voltage used in the fabrication of the ferroelectric switching device.

[0095] In some embodiments, a cyclic voltage can be applied to the ferroelectric layer 10 via the first electrode 20 and the second electrode 30 to control the separation and closure of the nanocracks, for example, a triangular cyclic voltage and a pulse voltage. Figure 11A This is a schematic diagram of a triangular cyclic voltage, where the forward voltage of the triangular cyclic voltage reaches a certain value, for example, the peak value U. 峰 Ferroelectric domain flipping generates stress and crack separation. When the negative voltage of the triangular cyclic voltage reaches a certain value, such as the valley value U... 谷 The ferroelectric domains are flipped again, the stress dissipates, and the crack closes. Figure 11B This is a schematic diagram of a pulsed cyclic voltage, which represents a periodic commutation pulse. When the positive pulse voltage U... 正 When a certain value is reached, the ferroelectric domains flip, generating stress and causing crack separation. When the negative pulse voltage U... 负 When a certain value is reached, the ferroelectric domains are flipped again, the stress dissipates, and the crack closes.

[0096] like Figure 12As shown, (a) is a scanning electron microscope image of crack closure of the ferroelectric switching device provided in the embodiment of the present disclosure, and (b) is a scanning electron microscope image of crack separation of the ferroelectric switching device provided in the embodiment of the present disclosure. When the positive pulse voltage applied by the voltage supply circuit is +100V (first voltage), the crack separates (as shown by the elliptical dashed line in the figure). When the negative pulse voltage applied by the external power supply is -100V (second voltage), the crack closes (as shown by the elliptical dashed line in the figure).

[0097] The control method for the ferroelectric switching device provided in this disclosure achieves the separation and closure of cracks penetrating the conductive layer by changing the polarity of the voltage, thereby realizing the "off" and "on" functions of the ferroelectric switching device. This method offers higher speed and lower energy consumption compared to traditional MOSFET switches. Furthermore, the ferroelectric-crack-based ferroelectric switching device exhibits abrupt switching behavior and a high ON / OFF current ratio, significantly reducing leakage current. Additionally, the entire conductive layer serves as a conductive channel; at the crack, the metal contact interface (fracture surface) of the two separated parts of the conductive layer has a large contact area, resulting in low contact resistance and fast signal transmission speed.

[0098] This disclosure also provides a three-dimensional memory. The three-dimensional memory includes the ferroelectric switching device described above. The ferroelectric switching device in the three-dimensional memory can replace traditional devices such as MOS transistors to achieve switching functions. The application of the ferroelectric switching device in the three-dimensional memory is illustrated below.

[0099] Figure 13 This is a schematic diagram illustrating an application of the ferroelectric switching device in a three-dimensional memory provided in this disclosure. Please refer to [link / reference]. Figure 13 In some embodiments of this disclosure, the three-dimensional memory includes a plurality of storage cells arranged in an array in three-dimensional space, the storage cells forming a plurality of storage strings. For example, the first storage string 130 is formed by serially connecting storage cells 1301 to 1305, and the second storage string 131 is formed by serially connecting storage cells 1311 to 1315.

[0100] Each memory string is equipped with the ferroelectric switching device, wherein the first electrode and the second electrode of the ferroelectric switching device are electrically connected to the corresponding drain selection line, the first signal transmission terminal is electrically connected to the bit line, and the second signal transmission terminal is electrically connected to the memory string.

[0101] For example, a ferroelectric switching device 1306 is disposed at the top of the first storage string 130, and the ferroelectric switching device 1306 serves as the string select transistor of the first storage string 130. The first electrode 20 of the ferroelectric switching device 1306 (e.g. Figure 1 and Figure 2 (as shown) and the second electrode 30 (as shown) Figure 1 and Figure 2(As shown) is electrically connected to the corresponding drain selection line DSL, and the first signal transmission terminal 60 (as shown) Figure 1 and Figure 2 (As shown) is electrically connected to bit line BL1, and the second signal transmission terminal 70 (as shown) is electrically connected to bit line BL1. Figure 1 and Figure 2 (As shown) is electrically connected to the first storage string 130. The storage cells 1301 to 1305 are also electrically connected to word lines WL1 to WL5.

[0102] For example, a ferroelectric switching device 1316 is provided at the top of the second storage string 131, and the ferroelectric switching device 1316 serves as the string select transistor of the second storage string 131. The first electrode 20 and the second electrode 30 of the ferroelectric switching device 1316 (e.g. Figure 1 and Figure 2 (As shown) is electrically connected to the corresponding drain selection line DSL, and the first signal transmission terminal 60 (as shown) Figure 1 and Figure 2 (As shown) is electrically connected to bit line BL2, and the second signal transmission terminal 70 (as shown) is electrically connected to bit line BL2. Figure 1 and Figure 2 (As shown) is electrically connected to the second storage string 131. The storage cells 1311 to 1315 are also electrically connected to word lines WL1 to WL5.

[0103] The drain selection line DSL can control the separation and closure of the cracks in the ferroelectric switching devices 1306 and 1316, thereby enabling the opening and closing of the ferroelectric switching devices and controlling the electrical connection between the bit lines BL1 and BL2 and the memory cell.

[0104] Furthermore, in some embodiments of this disclosure, the ferroelectric switching device is disposed at the bottom of each memory string as a source selection transistor.

[0105] For example, a ferroelectric switching device 1307 is disposed at the bottom of the first memory string 130, and the ferroelectric switching device 1307 serves as the source select transistor of the first memory string 130. The first electrode 20 of the ferroelectric switching device 1307 (e.g. Figure 1 and Figure 2 (as shown) and the second electrode 30 (as shown) Figure 1 and Figure 2 (As shown) is electrically connected to the corresponding source select line SSL, and the first signal transmission terminal 60 (as shown) Figure 1 and Figure 2 (As shown) is electrically connected to the first storage string 130, and the second signal transmission terminal 70 (as shown) is electrically connected to the first storage string 130. Figure 1 and Figure 2 (As shown) is electrically connected to the source line CSL.

[0106] For example, a ferroelectric switching device 1317 is disposed at the bottom of the second memory string 131, and the ferroelectric switching device 1317 serves as the source select transistor of the second memory string 131. The first electrode 20 and the second electrode 30 of the ferroelectric switching device 1317 (e.g. Figure 1 and Figure 2 (As shown) is electrically connected to the corresponding source select line SSL, and the first signal transmission terminal 60 (as shown) Figure 1 and Figure 2 (As shown) is electrically connected to the second storage string 131, and the second signal transmission terminal 70 (as shown) is electrically connected to the second storage string 131. Figure 1 and Figure 2 (As shown) is electrically connected to the source line CSL.

[0107] The source selection line SSL can control the separation and closure of the cracks in the ferroelectric switching devices 1306 and 1316, thereby enabling the opening and closing of the ferroelectric switching devices and controlling the electrical connection between the common source line CSL and the memory cell.

[0108] In other embodiments of this disclosure, a ferroelectric switching device may be used as the series select transistor, while a MOS transistor may be used as the source select transistor, or a ferroelectric switching device may be used as the source select transistor, while a MOS transistor may be used as the series select transistor.

[0109] The three-dimensional memory includes a storage array region and a peripheral circuit region. The storage array region is used to store information, while the peripheral circuit region can be located above, below, or around the storage array region. The peripheral circuit region is used to control the corresponding storage array region. The ferroelectric switching device can be located in the peripheral circuit region.

[0110] The ferroelectric switching device can also be applied to other microelectronic devices, such as non-volatile flash memory (NorFlash), and there are no specific limitations.

[0111] The above description is only a preferred embodiment of the present disclosure. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principle of the present disclosure, and these improvements and modifications should also be considered within the protection scope of the present disclosure.

Claims

1. A ferroelectric switching device, characterized in that, include: Ferroelectric layer; The first electrode and the second electrode are disposed on both sides of the ferroelectric layer and are used to apply voltage to the ferroelectric layer. An interlayer insulating layer is disposed on the second electrode; A conductive layer is disposed on the interlayer insulating layer; The first signal transmission terminal and the second signal transmission terminal are respectively disposed on the conductive layer; The ferroelectric layer extends perpendicularly to the ferroelectric layer and penetrates the second electrode, the interlayer insulating layer, and the conductive layer. The conductive layer is divided into two independent parts by the crack. The first signal transmission terminal and the second signal transmission terminal are respectively disposed on the two independent parts of the conductive layer divided by the crack. Changing the direction of the voltage applied to the ferroelectric layer can control the separation and closure of the crack. The ductility of the first electrode is greater than that of the second electrode and the conductive layer.

2. The ferroelectric switching device according to claim 1, characterized in that, The second electrode extends along the first transverse direction. At least a portion of the second electrode has a width in the second transverse direction that is smaller than the width of other regions. The region with the smallest width of the second electrode in the second transverse direction is located between the first signal transmission end and the second signal transmission end. The crack is located in the region with the smallest width of the second electrode in the second transverse direction. The crack separates or closes along the first transverse direction and extends along the second transverse direction.

3. The ferroelectric switching device according to claim 2, characterized in that, The second electrode includes a first segment and a second segment arranged along a first transverse direction. The orthographic projection of the second segment on the ferroelectric layer is located between the orthographic projection of the first signal transmission end on the ferroelectric layer and the orthographic projection of the second signal transmission end on the ferroelectric layer. The width of the second segment in the second transverse direction is smaller than the width of the first segment in the second transverse direction. The crack is located in the second segment.

4. The ferroelectric switching device according to claim 3, characterized in that, The boundary between the first segment and the second segment is located between the first signal transmission end and the second signal transmission end, and the crack is located at the boundary between the first segment and the second segment.

5. The ferroelectric switching device according to claim 4, characterized in that, The second electrode includes two first segments and one second segment. In the first transverse direction, the two first segments are located at the two ends of the second segment, and the crack is located at the junction of the second segment and one of the first segments.

6. The ferroelectric switching device according to claim 3, characterized in that, The second section includes multiple sub-segments with different widths in the second transverse direction, and the crack is located in the sub-segment with the smallest width.

7. The ferroelectric switching device according to claim 1, characterized in that, The interlayer insulating layer covers a portion of the surface of the second electrode, and a first conductive terminal is provided on the exposed surface of the second electrode.

8. The ferroelectric switching device according to claim 7, characterized in that, The second electrode is provided with two first conductive terminals, which are respectively located on both sides of the crack.

9. The ferroelectric switching device according to claim 1, characterized in that, The ferroelectric layer covers a portion of the surface of the first electrode, and a second conductive terminal is disposed on the exposed surface of the first electrode.

10. The ferroelectric switching device according to claim 1, characterized in that, The orthogonal projection of the second electrode onto the ferroelectric layer overlaps the orthogonal projection of the conductive layer onto the ferroelectric layer.

11. The ferroelectric switching device according to claim 1, characterized in that, The material of the first electrode is the same as the material of the first signal transmission end and the second signal transmission end.

12. The ferroelectric switching device according to claim 1, characterized in that, The material of the second electrode is the same as the material of the conductive layer.

13. The ferroelectric switching device according to claim 1, characterized in that, The conductive layer is made of an intermetallic alloy.

14. The ferroelectric switching device according to claim 13, characterized in that, The intermetallic alloy material includes MnPt or FePt.

15. A method for fabricating a ferroelectric switching device, characterized in that, include: Provide substrate; A first electrode, a ferroelectric layer, a second electrode, an interlayer insulating layer, a conductive layer, and a first signal transmission terminal and a second signal transmission terminal are formed on the surface of the substrate. The first signal transmission terminal and the second signal transmission terminal are both disposed on the conductive layer and are independent of each other. A crack is formed, which extends from the ferroelectric layer in a direction perpendicular to the ferroelectric layer and penetrates the second electrode, the interlayer insulating layer, and the conductive layer between the first signal transmission end and the second signal transmission end. The conductive layer is divided into two independent parts by the crack. The first signal transmission end and the second signal transmission end are respectively disposed on the two independent parts of the conductive layer divided by the crack. The ductility of the first electrode is greater than that of the second electrode and the conductive layer. The method for forming cracks includes: applying a polarization voltage to the ferroelectric layer through the first electrode and the second electrode, such that the polarization direction of the ferroelectric domains of the ferroelectric layer is the same as the direction of the polarization voltage; and applying a reversal voltage to the ferroelectric layer through the first electrode and the second electrode, wherein the reversal voltage is opposite in polarity to the polarization voltage.

16. A control method for a ferroelectric switching device according to any one of claims 1 to 14, characterized in that, include: A first voltage is applied to the ferroelectric layer via the first electrode and the second electrode to control the separation of the crack, and a second voltage is applied to the ferroelectric layer via the first electrode and the second electrode to control the closure of the crack, thereby achieving electrical insulation and electrical conduction between the first signal transmission terminal and the second signal transmission terminal, wherein the first voltage and the second voltage have opposite polarities.

17. A three-dimensional memory, characterized in that, Including the ferroelectric switching device as described in any one of claims 1 to 14.

18. The three-dimensional memory according to claim 17, characterized in that, The three-dimensional memory includes multiple storage cells arranged in an array in three-dimensional space, forming multiple storage strings. Each storage string is correspondingly equipped with the ferroelectric switching device. The first electrode and the second electrode of the ferroelectric switching device are electrically connected to the corresponding drain selection line, the first signal transmission terminal is electrically connected to the bit line, and the second signal transmission terminal is electrically connected to the memory string; or, the first electrode and the second electrode of the ferroelectric switching device are electrically connected to the corresponding source selection line, the first signal transmission terminal is electrically connected to the memory string, and the second signal transmission terminal is electrically connected to the source line.

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