CN115332442A - Ferroelectric switching device, preparation method, control method and three-dimensional memory - Google Patents

Abstract

A ferroelectric switching device comprising: a ferroelectric layer; the first electrode and the second electrode are arranged on two sides of the ferroelectric layer and used for applying voltage to the ferroelectric layer; an interlayer insulating layer disposed on the second electrode; the conductive layer is arranged on the interlayer insulating layer; the first signal transmission end and the second signal transmission end are respectively arranged on the conductive layer; the second electrode, the interlayer insulating layer, and the conductive layer are separated into two parts independent of each other by the crack, and the first signal transmitting terminal and the second signal transmitting terminal are respectively disposed on the two parts separated from each other by the crack. The ferroelectric switching device has higher speed, lower power consumption and smaller chip area, and has abrupt switching behavior and high ON/OFF current ratio, low contact resistance and fast signal transmission speed.

Description

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

Technical Field

The disclosure relates to the field of integrated circuits, in particular to a ferroelectric switching device, a preparation method, a control method and a three-dimensional memory.

Background

As microelectronic technology advances, the feature size of transistors on integrated circuits continues to approach the physical limit, and if device dimensions are further reduced, serious leakage problems exist. The functional device based on the electro-mechanical coupling has mechanical on and off characteristics, so that the problem of electric leakage in an off state is effectively avoided. Meanwhile, compared with the traditional semiconductor device, the micro-electromechanical device has the advantages of large switching ratio, low power consumption, simple structure and process and the like, and has huge development potential and application value in the aspects of developing high-density, low-power consumption and high-stability memories, transistors and logic devices.

Disclosure of Invention

The technical problem to be solved by the embodiments of the present disclosure is to provide a ferroelectric switching device, a method for manufacturing the same, a method for controlling the same, and a three-dimensional memory.

An aspect of an embodiment of the present disclosure provides a ferroelectric switching device, which includes: a ferroelectric layer; a first electrode and a second electrode provided on both 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; the first signal transmission end and the second signal transmission end are respectively arranged on the conducting layer; wherein a crack is formed extending from the ferroelectric layer in a direction perpendicular to the ferroelectric layer and penetrating through the second electrode, the interlayer insulating layer, and the conductive layer, the conductive layer is divided into two parts independent of each other by the crack, the first signal transmitting terminal and the second signal transmitting terminal are respectively provided on the two parts of the conductive layer divided into two parts independent of each other by the crack, and the separation and closure of the crack can be controlled by changing a direction of a voltage applied to the ferroelectric layer.

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

In some embodiments, the second electrode extends along a first transverse direction, the width of at least a partial region of the second electrode in the second transverse direction is smaller than the width of other regions, the region of the second electrode having the smallest width in the second transverse direction is located between the first signal conveying end and the second signal conveying end, and the crack is located in the region of the second electrode having the smallest width in the second transverse direction, the crack separates or closes along the first transverse direction and extends along the second transverse direction.

In some embodiments, the second electrode includes a first section and a second section arranged along a first transverse direction, an orthographic projection of the second section on the ferroelectric layer is between an orthographic projection of the first signal transmitting terminal on the ferroelectric layer and an orthographic projection of the second signal transmitting terminal on the ferroelectric layer, a width of the second section in the second transverse direction is smaller than a width of the first section in the second transverse direction, and the crack is located in the second section.

In some embodiments, the interface of the first and second segments is between the first and second signal conveying ends, and the crack is at the interface of the first and second segments

In some embodiments, the second electrode comprises two first segments and one second segment, the two first segments are respectively located at two ends of the second segment in the first transverse direction, and the crack is located at the intersection of the second segment and one of the first segments.

In some embodiments, the second section comprises a plurality of subsections of different widths in a second transverse direction, the crack being located at the subsection with the smallest width.

In some embodiments, the interlayer insulating layer covers a portion of a surface of the second electrode, and a first conductive terminal is disposed on an exposed surface of the second electrode.

In some embodiments, two first conductive terminals are disposed on the second electrode, and the two first conductive terminals are disposed on two sides of the crack.

In some embodiments, the ferroelectric layer covers a portion of the surface of the first electrode, and a second conductive terminal is disposed on an exposed surface of the first electrode.

In some embodiments, an orthographic projection of the second electrode on the ferroelectric layer covers an orthographic projection of the conductive layer on the ferroelectric layer.

In some embodiments, the material of the first electrode is the same as the material of the first and second signal conveying ends.

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

In some embodiments, the material of the conductive layer comprises an intermetallic alloy material.

In some embodiments, the intermetallic alloy material comprises MnPt or FePt.

In another aspect, an embodiment of the present disclosure further provides a method for manufacturing a ferroelectric switching device, including: providing a substrate; forming a first electrode, a ferroelectric layer, a second electrode, an interlayer insulating layer, a conductive layer, a first signal transmission end and a second signal transmission end on the surface of the substrate, wherein the first signal transmission end and the second signal transmission end are arranged on the conductive layer and are independent of each other; forming a 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 transmitting terminal and the second signal transmitting terminal, and the conductive layer being divided into two parts independent of each other by the crack, the first signal transmitting terminal and the second signal transmitting terminal being respectively provided on the two parts of the conductive layer divided into two parts independent of each other by the crack.

In some embodiments, a method of forming a crack comprises: applying a polarization voltage to the ferroelectric layer through the first electrode and the second electrode to make the polarization direction of the ferroelectric domain of the ferroelectric layer the same as the polarization direction of the polarization voltage; applying a switching voltage to the ferroelectric layer through the first electrode and the second electrode, the switching voltage being opposite in polarity to the polarization voltage.

Still another aspect of the embodiments of the present disclosure provides a method for controlling a ferroelectric switching device as described above, including: and applying a first voltage to the ferroelectric layer through the first electrode and the second electrode to control the separation of the crack, and applying a second voltage to the ferroelectric layer through the first electrode and the second electrode to control the closing of the crack to realize the electrical insulation and the electrical conduction of the first signal transmission terminal and the second signal transmission terminal, wherein the polarities of the first voltage and the second voltage are opposite.

Yet another aspect of the embodiments of the present disclosure provides a three-dimensional memory including the ferroelectric switching device as described above.

In some embodiments, the three-dimensional memory comprises a plurality of memory cells arranged in a three-dimensional space in an array manner to form a plurality of memory strings, wherein each memory string is provided with the ferroelectric switching device correspondingly, a first electrode and a second electrode of the ferroelectric switching device are respectively and electrically connected with a corresponding drain electrode selection line, a first signal transmission terminal is electrically connected with a bit line, and a second signal transmission terminal is electrically connected with the memory string; or the first electrode and the second electrode of the ferroelectric switching device are respectively electrically connected with the corresponding source selection lines, the first signal transmission end is electrically connected with the storage string, and the second signal transmission end is electrically connected with the source line.

The conductive layer of the ferroelectric switching device provided by the embodiment of the disclosure is divided into two parts independent of each other by the crack, and the separation and closing of the crack can be controlled by changing the direction of the voltage applied to the ferroelectric layer, so as to realize the on and off of the ferroelectric switching device. For example, a first voltage is applied to the ferroelectric layer through the first electrode and the second electrode, so that the closing of the crack can be controlled, and the first signal transmitting terminal and the second signal transmitting terminal can be electrically connected through the conductive layer, so that the opening function of the ferroelectric switching device is realized; and a second voltage is applied to the ferroelectric layer through the first electrode and the second electrode to control the separation of the cracks, and the first signal transmission end and the second signal transmission end can realize electric insulation through the conductive layer so as to realize the 'off' function of the ferroelectric switch device.

The ferroelectric switch device provided by the embodiment of the disclosure realizes the functions of 'on' and 'off' by utilizing the separation and closing of cracks, has higher speed, lower energy consumption and smaller chip area than the traditional MOSFET switch, has simple manufacturing process, is compatible with the Fe-NAND process, has low cost and great economic benefit; and the ferroelectric-crack based ferroelectric switching device has an abrupt switching behavior and a high ON/OFF current ratio; the contact area of the metal contact interface is large, so that the contact resistance is low, and the signal transmission speed is high.

Drawings

Fig. 1 is a schematic top view of a ferroelectric switching device provided in accordance with a first embodiment of the present disclosure;

FIG. 2 is a schematic cross-sectional view taken along line C-C' of FIG. 1;

figure 3 is another schematic top view of a ferroelectric switching device provided in accordance with a first embodiment of the present disclosure;

FIG. 4 is a schematic cross-sectional view taken along line C-C' of FIG. 3;

figure 5 is a schematic top view of a ferroelectric switching device provided in accordance with a second embodiment of the present disclosure;

fig. 6 is a scanning electron microscope image of a ferroelectric switching device exposing a second electrode provided by a second embodiment of the present disclosure;

fig. 7 is a schematic top view of a ferroelectric switching device provided in accordance with a third embodiment of the present disclosure;

fig. 8 is a distribution diagram of electric field intensity when a ferroelectric switching device exposes a second electrode according to an embodiment of the present disclosure, wherein (b) is an enlarged view of (a);

fig. 9 is a schematic step diagram of a method of making a ferroelectric switching device provided by an embodiment of the present disclosure;

fig. 10A to 10C are schematic structural diagrams of devices formed in main steps of a method for manufacturing a ferroelectric switching device according to an embodiment of the present invention;

fig. 11A is a schematic diagram of a triangular cycling voltage applied to a ferroelectric layer according to an embodiment of the present disclosure;

fig. 11B is a schematic diagram of a pulse cycling voltage applied to the ferroelectric layer according to an embodiment of the present disclosure;

fig. 12 is a scanning electron microscope image of a ferroelectric switching device provided by an embodiment of the present disclosure, wherein (a) is a scanning electron microscope image of crack closure and (b) is a scanning electron microscope image of crack separation;

FIG. 13 is a schematic diagram of an application of a ferroelectric switching device in a three-dimensional memory provided by an embodiment of the present disclosure;

figure 14 is a schematic top view of a ferroelectric switching device provided in a fourth embodiment of the present disclosure.

Detailed Description

In order to make the purpose, technical means and effect of the embodiments of the present disclosure more clear and definite, the embodiments of the present disclosure will be further described with reference to the accompanying drawings. It is to be understood that the embodiments described herein are only a few embodiments, not all embodiments, and are not intended to limit the present disclosure. All other embodiments, which can be derived by a person skilled in the art from the embodiments disclosed herein without making any creative effort, shall fall within the protection scope of the present disclosure.

Fig. 1 and 3 are schematic top views of ferroelectric switching devices according to a first embodiment of the present disclosure, fig. 2 is a schematic cross-sectional view taken along line C-C 'shown in fig. 1, and fig. 4 is a schematic cross-sectional view taken along line C-C' shown in fig. 3.

Referring to fig. 1 to 4, the 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 transmitting terminal 60, and a second signal transmitting terminal 70. The first electrode 20 and the second electrode 30 are disposed on two sides of the ferroelectric layer 10, and are used for applying a voltage to the ferroelectric layer 10, the interlayer insulating layer 40 is disposed on the second electrode 30, the conductive layer 50 is disposed on the interlayer insulating layer 40, and the first signal transmitting terminal 60 and the second signal transmitting terminal 70 are respectively disposed on the conductive layer 50. Wherein a crack a is formed in the conductive layer 50 extending from the ferroelectric layer 10 in a direction perpendicular to the ferroelectric layer 10 (e.g., Z direction in fig. 2) and penetrating through the second electrode 30, the interlayer insulating layer 40, and between the first signal transmitting terminal 60 and the second signal transmitting terminal 70, and the conductive layer 50 is divided into two parts independent of each other by the crack a, and the first signal transmitting terminal 60 and the second signal transmitting terminal 70 are respectively disposed on the two parts of the conductive layer 50 divided into two parts independent of each other by the crack a. Wherein, changing the direction of the voltage applied to the ferroelectric layer 40 can control the separation and closure of the crack a, achieve the electrical insulation and the electrical conduction of the first signal transmitting terminal 60 and the second signal transmitting terminal 70, and further achieve the separation and closure of the ferroelectric switching device.

The working process of the ferroelectric switching device provided by the embodiment of the disclosure is as follows: referring to fig. 1 and 2, when a first voltage U1 is applied to the first electrode 20 and the second electrode 30, the crack a separates, the conductive layer 50 is divided into two parts insulated from each other, and the first signal transmission terminal 60 is electrically insulated from the second signal transmission terminal 70, so as to realize the off function of the ferroelectric switching device. Referring to fig. 3 and 4, when a second voltage U2 is applied to the first electrode 20 and the second electrode 30, the crack a is closed, the two parts of the conductive layer 50 are in contact, and the first signal transmitting terminal 60 and the second signal transmitting terminal 70 are electrically conducted, so as to realize the "on" function of the ferroelectric switching device.

The first voltage U1 and the second voltage U2 have opposite polarities. For example, in some embodiments, the first voltage U1 is a positive voltage in a vertical device direction (e.g., Z direction in fig. 2), and the second voltage U2 is a negative voltage in the vertical device direction, and in other embodiments, the first voltage U1 is a negative voltage in the vertical device direction, and the second voltage U2 is a positive voltage in the vertical device direction.

The conductive layer 50 of the ferroelectric switching device provided by the embodiment of the present disclosure is divided into two parts independent from each other by the crack a, and the separation and closing of the crack a can be controlled by changing the direction of the voltage applied to the ferroelectric layer 10, thereby implementing the "on" and "off" of the ferroelectric switching device. Compared with a Metal-Oxide-Semiconductor Field Effect Transistor (MOSFET) switch, the ferroelectric switch device provided by the embodiment of the disclosure has the advantages of higher speed, lower energy consumption, smaller chip area, simple manufacturing process, compatibility with a Fe-Not AND flash memory (Fe-Not AND flash) process, low cost AND great economic benefit; also, ferroelectric-crack based ferroelectric switching devices have abrupt switching behavior and high ON/OFF current ratios. The whole layer of the conductive layer 50 is used as a conductive channel, and at the crack a, the contact area of the metal contact interface (fracture surface) of the two separated parts of the conductive layer is large, so that the contact resistance is low, and the signal transmission speed is high.

In a direction perpendicular to the ferroelectric layer 10 (e.g., Z direction in fig. 2), the first electrode 20 is located below the ferroelectric layer 10, i.e., the second electrode 20 is disposed on a lower surface of the ferroelectric layer 10. In the present embodiment, the first electrode 20 is disposed on a substrate 100, and the first electrode 20 is disposed on the substrate 100, and the ferroelectric layer 10 is disposed on the first electrode 20.

The ductility of the first electrode 20 is good so that when a crack is formed, the crack does not extend to the first electrode 20, thereby maintaining the integrity of the first electrode 20 and increasing the lifetime of the ferroelectric switching device. The first electrode 20 may be a metal electrode, such as a Pt, au, cu, or Ag electrode, and the like.

In a direction perpendicular to the ferroelectric layer 10 (e.g., Z direction in fig. 2), the second electrode 30 is located above the ferroelectric layer 10, i.e., the second electrode 30 is disposed on the upper surface of the ferroelectric layer 10.

The ductility of the second electrode 30 is small, and specifically, the ductility of the first electrode 20 is larger than that of the second electrode 30, so that when a crack is formed, the crack does not extend to the first electrode 20, but extends from the ferroelectric layer 10, penetrates through the second electrode 30, and further extends to the conductive layer 50. The material of the second electrode 30 may be an intermetallic alloy material, such as MnPt or FePt.

The interlayer insulating layer 40 is located on the second electrode 30, that is, in a direction perpendicular to the ferroelectric layer 10 (e.g., Z direction in fig. 2), 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, an oxide layer, a nitride layer, a high K dielectric layer, etc., for example, the oxide layer may be an aluminum oxide layer. The interlayer insulating layer 40 functions 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, and when a crack is formed, the crack also extends through the interlayer insulating layer 40 and further to the conductive layer 50.

The conductive layer 50 is located on the interlayer insulating layer 40, that is, in a direction perpendicular to the ferroelectric layer 10 (e.g., Z direction in fig. 1), the conductive layer 50 is disposed on the upper surface of the interlayer insulating layer 40. The ductility of the conductive layer 50 is less than that of the first electrode 20, and thus, when a crack a is formed, the crack a does not extend to the first electrode 20, but extends through the conductive layer 50 to divide the conductive layer 50 into two parts independent of each other, which are electrically isolated. Further, the ductility of the conductive layer 50 is less than or equal to the ductility of the second electrode 30, that is, the ductility of the second electrode 30 is greater than or equal to the ductility of the conductive layer 50, and when a crack a is formed, the crack a can extend from the ferroelectric layer 10 and penetrate through the conductive layer 50.

The material of the conductive layer 50 may be an intermetallic alloy material, such as MnPt or FePt. In this embodiment, the material of the conductive layer 50 is the same as the material of the second electrode 30, and the ductility of the two is the same, so that it is convenient to select an appropriate voltage to further ensure that the crack a can penetrate through both the second electrode 30 and the conductive layer 50. In other embodiments of the present disclosure, the conductive layer 50 may also be made of a different material but have a similar ductility as the second electrode 30, so as to further avoid the crack a from penetrating only the second electrode 30 and not the conductive layer 50.

In this embodiment, the first signal carrying terminal 60 serves as an input terminal for an electrical signal of the ferroelectric switching device, and the second signal carrying terminal 70 serves as an output terminal for the electrical signal of the ferroelectric switching device. The first signal carrying terminal 60 and the second signal carrying terminal 70 are independent of each other in the sense that there is no direct connection between the two. When the crack is closed, an electrical signal which is required to be transmitted by the external environment through the ferroelectric switching device is input through the first signal transmission terminal 60, is conducted through the conductive layer 50, and is output through the second signal transmission terminal 70. When the crack a is separated, an electrical signal that needs to be transmitted through the ferroelectric switch device from the outside is input through the first signal transmission terminal 60, and is affected by the crack a, the conductive layer 50 cannot transmit the electrical signal, and then the electrical signal that needs to be transmitted through the ferroelectric switch device from the outside cannot be output through the second signal transmission terminal 70. In other embodiments, the first signal carrying terminal 60 can serve as an output terminal for an electrical signal of the ferroelectric switching device, and the second signal carrying terminal 70 can serve as an input terminal for an electrical signal of the ferroelectric switching device.

Further, the first signal carrying terminal 60 and the second signal carrying terminal 70 can be metal terminals, including but not limited to Pt, au, cu or Ag, etc. In this embodiment, the material of the first electrode 20 is the same as the material of the first signal carrying terminal 60 and the second signal carrying terminal 70, and the ductility of the first signal carrying terminal 60 and the second signal carrying terminal 70 is the same as the ductility of the first electrode 20, so that the crack a can be further prevented from penetrating through the first signal carrying terminal 60 and the second signal carrying terminal 70, and the reliability and the service life of the ferroelectric switching device can be improved.

Further, in this embodiment, in order to ensure that the crack a can divide the conductive layer 50 into two completely broken portions, in a direction perpendicular to the ferroelectric layer (i.e. a direction opposite to the Z direction in fig. 2), an orthographic projection of the second electrode 30 on the ferroelectric layer 10 covers an orthographic projection of the conductive layer 50 on the ferroelectric layer 10, that is, the orthographic projection of the conductive layer 50 on the ferroelectric layer 10 is located within a range of the orthographic projection of the second electrode 30 on the ferroelectric layer 10. If the orthographic projection of the conductive layer 50 on the ferroelectric layer 10 is outside the range of the orthographic projection of the second electrode 30 on the ferroelectric layer 10, there may be a crack a separating only a portion of the conductive layer 50 in a second transverse direction (Y direction shown in fig. 1) without separating the conductive layer 50 into two portions that are completely broken, thereby failing to achieve electrical isolation between the first signal transmitting terminal 60 and the second signal transmitting terminal 70.

Further, in this embodiment, the interlayer insulating layer 40 covers a part of the surface of the second electrode 30, that is, the interlayer insulating layer 40 does not cover the entire surface of the second electrode 30, and a part of the surface of the second electrode 30 is exposed, so that the exposed surface of the second electrode 30 can be used as an electrical connection surface, for example, in some embodiments of the present disclosure, a first conductive terminal 31 is disposed on the exposed surface of the second electrode 30, and 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 the present 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.

In the present embodiment, one first conductive terminal 31 is disposed on the exposed surface of the second electrode 30, and in other embodiments of the present disclosure, two first conductive terminals 31 are disposed on the second electrode 30, and the two first conductive terminals 31 are disposed on two sides of the crack a, specifically referring to fig. 14. Whether the crack a penetrates through the second electrode 30 can be determined by applying a voltage to the two first conductive terminals 31 and testing a current value between the two first conductive terminals 31.

Further, in the present embodiment, the ferroelectric layer 10 covers a part 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 part of the surface of the first electrode 20 is exposed, the exposed surface of the first electrode 20 can be used as an electrical connection surface, for example, in some embodiments of the present disclosure, a second conductive terminal 21 is disposed on the exposed surface of the first electrode 20, and the second conductive terminal 21 is electrically connected to a voltage supply circuit, so that the voltage supply circuit provides an electric potential to the first electrode 20 through the second conductive terminal 21. In other embodiments of the present disclosure, the second conductive terminal 21 may not be disposed, and the voltage supply circuit may be directly connected to the exposed surface of the first electrode 20.

The inventors have found that cracks in the ferroelectric switching device tend to occur in regions where the width of the second electrode is narrow. As a result of the intensive studies by the inventors, when a voltage is applied to the ferroelectric layer via the first electrode and the second electrode, the electric field intensity at the position where the width of the second electrode is narrow is high, so that the stress of the ferroelectric layer is concentrated at the corresponding region, and cracks are easily generated at the position.

In view of the above, the reliability of the ferroelectric switching device is improved in order to further control the location of the crack. Some embodiments of the present disclosure provide a ferroelectric switching device, wherein the second electrode of the ferroelectric switching device extends along a first transverse direction, at least a partial region of the second electrode has a width in the second transverse direction smaller than widths of other regions, a region of the second electrode having a smallest width in the second transverse direction is located between the first signal transmitting terminal and the second signal transmitting terminal, and the crack is located in a region of the second electrode having a smallest width in the second transverse direction. Wherein the crack separates or closes in the first transverse direction and extends in the second transverse direction.

Specifically, in some embodiments, the second electrode includes a first section and a second section arranged along a first transverse direction, the second section is located between the first signal transmission end and a second signal transmission end, an orthographic projection of the second section on the ferroelectric layer is located between an orthographic projection of the first signal transmission end on the ferroelectric layer and an orthographic projection of the second signal transmission end on the ferroelectric layer, a width of the second section in the second transverse direction is smaller than a width of the first section in the second transverse direction, and the crack is located in the second section. For example, referring to fig. 5, which is a schematic top view of a ferroelectric switching device according to a second embodiment of the present disclosure, in this embodiment, the second electrode 30 includes two first sections 301 and one second section 302, and the two first sections 301 are respectively located at two ends of the second section 302 in the first transverse direction (X direction) to form a bridge-shaped structure. The second section 302 is located between the first signal carrying terminal 60 and the second signal carrying terminal 70, the width of the second section 302 in the second transverse direction (Y-direction) is smaller than the width of the first section 301 in the second transverse direction (Y-direction), and the crack a is located in the region between the first signal carrying terminal 60 and the second signal carrying terminal 70 (e.g., region E in fig. 5) and located on the second section 302.

Further, the inventors have found through long-term analysis and research that the crack a is liable to exist at the boundary between the narrowest section of the second electrode 30 and the adjacent section. For example, as shown in fig. 5, in the present embodiment, the boundary between the first section 301 and the second section 302 is located in the region between the first signal transmitting terminal 60 and the second signal transmitting terminal 70 (E region in fig. 5), and the crack a is located at the boundary between the first section 301 and the second section 302. Wherein, the boundary of the first section 301 and the second section 302 includes the position where the first section 301 and the second section 302 intersect and the part of the second section 302 adjacent to the position where the first section 301 and the second section 302 intersect.

After a crack is generated in the ferroelectric layer 10, the stress is released, and a second crack is not generated, so in this embodiment, the crack a is only located at the boundary between the second segment 302 and one of the first segments 301, and no crack is present at the boundary between the second segment 302 and the other first segment 301.

Fig. 6 is a scanning electron microscope image of a ferroelectric switching device according to a second embodiment of the present disclosure, in which scales of (a), (b), (c), (d), (e), and (f) are 10 micrometers, 5 micrometers, and 1 micrometer, respectively, and cracks are unclear in (c) and (e), and are marked with dotted lines. As can be seen from fig. 6, cracks are necessarily formed in the region where the width of the second electrode is the smallest (as indicated by arrow a in the figure), and the ferroelectric switching device provided by the embodiment of the present disclosure has higher reliability.

In the second embodiment, the width of the second section 302 in the second transverse direction (Y direction) is the same in the region between the first signal carrying terminal 60 and the second signal carrying terminal 70, while in other embodiments of the present disclosure, in the region between the first signal carrying terminal 60 and the second signal carrying terminal 70, the second section 302 includes a plurality of sub-sections having different widths in the second transverse direction (Y direction), and the crack a is located at the sub-section having the smallest width. As shown in fig. 7, which is a schematic top view of a ferroelectric switching device provided in a third embodiment of the present disclosure, the second segment 302 includes three sub-segments 302A, 302B and 302C arranged along a first transverse direction (X direction), a width of the sub-segment 302B in the second transverse direction (Y direction) is smaller than a width of the sub-segments 302A and 302C in the second transverse direction (Y direction), the crack a is located at an interface between the sub-segment 302B and the sub-segment 302A, and in other embodiments, the crack a may also be located at an interface between the sub-segment 302B and the sub-segment 302C.

It will be appreciated that in some embodiments, the area between the first and second signal carrying terminals 60, 70, regardless of the variation in the width of the second electrode 30, is necessarily greater than or equal to the width of the conductive layer 50 to ensure that the conductive layer 50 can be completely separated by a crack.

In the above embodiment, the width of the second electrode 30 in the second transverse direction (Y direction) varies in a segment form, but in other embodiments of the present disclosure, the width of the second electrode may also gradually decrease from two ends to the middle in the first transverse direction (X direction), as long as the width of the area of the second electrode 30 between the first signal transmission terminal 60 and the second signal transmission terminal 70 is ensured to be smaller than the width of the area outside the first signal transmission terminal 60 and the second signal transmission terminal 70.

Fig. 8 is a distribution diagram of electric field intensity when the ferroelectric switching device provided by the embodiment of the present disclosure exposes the second electrode, where (b) is an enlarged view of (a), and as can be seen from fig. 8, the color at the intersection of the sections with different widths of the second electrode is darker, which indicates that the electric field intensity is strongest at the intersection (as indicated by the dashed oval frame in (b)), cracks are easily generated in the area.

The embodiment of the disclosure also provides a preparation method of the ferroelectric switch device. Please refer to fig. 9, which is a schematic step diagram illustrating a method for manufacturing a ferroelectric switching device according to an embodiment of the present disclosure, the 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 transmitting end and a second signal transmitting end on the surface of the substrate, wherein the first signal transmitting end and the second signal transmitting end are both disposed on the conductive layer and are independent of each other; step S903 is to form a crack, where the crack extends from the ferroelectric layer in a direction perpendicular to the ferroelectric layer, and penetrates through 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 separated into two parts independent of each other by the crack.

Fig. 10A to 10C are schematic device structures formed in the main steps of a method for manufacturing a ferroelectric switching device according to an embodiment of the present invention.

Referring to step S901 and fig. 10A, a substrate 100 is provided.

The substrate 100 may be a Si substrate, a Ge substrate, a SiGe substrate, an SOI (silicon On Insulator) substrate, a GOI (Germanium On Insulator) substrate, or the like. In this embodiment, the substrate 100 is preferably a Si substrate for supporting device structures thereon.

Referring to step S902 and fig. 10B, a first electrode 20, a ferroelectric layer 10, a second electrode 30, an interlayer insulating layer 40, a conductive layer 50, and a first signal transmitting terminal 60 and a second signal transmitting terminal 70 are formed on the surface of the substrate 100, and the first signal transmitting terminal 60 and the second signal transmitting terminal 70 are disposed on the conductive layer 50 and are independent of each other.

A first electrode material layer may be formed on the surface of the substrate 100 by using chemical vapor deposition, atomic layer deposition, pulsed laser deposition, molecular beam epitaxy, and the like, and then patterned by using photolithography, etching, and the like, so as to form the first electrode 20. The first electrode 20 may be a metal electrode, such as a Pt, au, cu, or Ag electrode, and the like.

The ferroelectric layer 10 may be formed by forming a ferroelectric material layer on the surface of the first electrode 20 by using processes such as chemical vapor deposition, atomic layer deposition, pulsed laser deposition, molecular beam epitaxy, and the like, and patterning the ferroelectric material layer by using processes such as photolithography, etching, and the like. In the present embodiment, the material of the ferroelectric layer 10 is HfZrOx, so that it can be applied to a hafnium-based Complementary Metal Oxide Semiconductor (CMOS) compatible ferroelectric NAND (Fe-NAND) flash memory, so as to simplify the manufacturing process. In other embodiments of the present disclosure, the material of the ferroelectric layer 10 may also be lead magnesium niobate-lead titanate (PMN-PT), lead zirconate titanate (PZT), lead indium niobate-lead titanate (PIN-PT), or lead magnesium niobate-lead zirconate titanate-lead titanate (PMN-PZT-PT), baTiO ₃ (BTO) and the like.

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

An interlayer insulating material layer may be formed on the second electrode 30 by using processes such as chemical vapor deposition, atomic layer deposition, pulsed laser deposition, and molecular beam epitaxy, and then patterned by using processes such as photolithography and etching, so as to form the interlayer insulating layer 40. The interlayer insulating layer 40 may cover not only the second electrode 30 but also an exposed surface of the ferroelectric layer 10. The interlayer insulating layer 40 includes, but is not limited to, an oxide layer, a nitride layer, a high K dielectric layer, etc., for example, the oxide layer may be an aluminum oxide layer.

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

A signal transmission material layer may be formed on the conductive layer 50 by using chemical vapor deposition, atomic layer deposition, pulsed laser deposition, molecular beam epitaxy, and the like, and then patterned by using photolithography, etching, and the like, so as to form the first signal transmission terminal 60 and the second signal transmission terminal 70. The first signal carrying terminal 60 and the second signal carrying terminal 70 are independent of each other.

Referring to step S903 and fig. 10C, a crack a is formed, the crack a extends from the ferroelectric layer 10 along a direction perpendicular to the ferroelectric layer 10 (e.g., a Z direction in fig. 10C) and penetrates through the second electrode 20, the interlayer insulating layer 40, and the conductive layer 50 between the first signal transmitting terminal 60 and the second signal transmitting terminal 70, and the conductive layer 50 is divided into two parts independent of each other by the crack, and the first signal transmitting terminal 60 and the second signal transmitting terminal 70 are respectively disposed on the two parts of the conductive layer 50 separated into two parts independent of each other by the crack a.

Embodiments of the present disclosure also provide a method of forming the crack, the method including the steps of:

pre-polarization: a poling voltage is applied to the ferroelectric layer 10 through the first electrode 20 and the second electrode 30 such that a poling direction of ferroelectric domains of the ferroelectric layer 10 is the same as a direction of the poling voltage.

For the ferroelectric layer 10, when no polarization voltage is applied, that is, when no external electric field is applied, the ferroelectric domains are randomly distributed in the ferroelectric layer 10, and when a polarization voltage is applied, that is, when an external electric field is applied, the ferroelectric domains in the electric field direction grow, the ferroelectric domains in the opposite electric field direction disappear, the ferroelectric domains distributed in the other directions are shifted to the electric field direction, and finally, ferroelectric domains in accordance with the electric field direction are formed. The direction of the electric field is the same as the direction of the polarization voltage. In some embodiments, the pre-poling voltage forms a field with a strength greater than a coercive field of the ferroelectric domain, forming the ferroelectric domain aligned with the direction of the field.

Turning: a switching voltage is applied to the ferroelectric layer 10 via the first electrode 20 and the second electrode 30, the switching voltage being opposite in polarity to the polarization voltage.

When the voltage is changed from the polarization voltage to the switching voltage, the switching voltage has a polarity opposite to that of the polarization voltage, and the direction of the applied electric field is changed, so that the ferroelectric domains in the ferroelectric layer 10 are also switched, and stress is generated in the ferroelectric domain walls by pinning action of defects, dopants and the like in the ferroelectric layer on the domain walls, and the cracks a are generated at stress concentration positions. In some embodiments, the switching voltage forms an electric field strength greater than a coercive field of the ferroelectric domain such that the ferroelectric domain can be switched.

The crack a penetrates the second electrode 30, the interlayer insulating layer 40, and the conductive layer 50, and the crack a divides the conductive layer 50 into two parts, which are electrically isolated. When the ferroelectric switching device is applied, the two parts of the conductive layer 50 are connected and disconnected by controlling the separation and closing of the crack, so as to electrically insulate and connect the first signal transmission terminal 60 and the second signal transmission terminal 70, thereby realizing the functions of turning "off" and turning "on" of the ferroelectric switching device.

The ferroelectric switching device having cracks can be prepared by the method for preparing the ferroelectric switching device provided by the embodiment of the present disclosure, and the separation and the closing of the cracks a are controlled by changing the direction of the voltage applied to the ferroelectric layer 10, thereby realizing the "on" and "off" of the ferroelectric switching device.

The embodiment of the disclosure also provides a control method of the ferroelectric switching device. The control method comprises the following steps:

as shown in fig. 2, a first voltage U1 is applied to the ferroelectric layer 10 through 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 parts insulated from each other, and the first signal transmission terminal 60 is electrically insulated from the second signal transmission terminal 70, so as to realize an off function of the ferroelectric switching device. When a first voltage U1 is applied to the ferroelectric layer 10 through the first electrode 20 and the second electrode 30, the direction of an external electric field is changed, the ferroelectric domain in the ferroelectric layer 10 is inverted, and stress is generated in the ferroelectric domain wall due to pinning effects on the domain wall caused by defects, dopants, and the like in the ferroelectric layer, and the crack a is formed at the stress concentration position, thereby realizing the off function of the ferroelectric switch device.

As shown in fig. 4, a second voltage U2 is applied to the ferroelectric layer 10 via the first electrode 20 and the second electrode 30 to control the closing of the crack a, two portions of the conductive layer 50 are in contact, and the first signal transmitting terminal 60 and the second signal transmitting terminal 70 are electrically conducted, so as to realize the "on" function of the ferroelectric switching device. When a second voltage U2 is applied to the ferroelectric layer 10 through the first electrode 20 and the second electrode 30, the ferroelectric domain is inverted again, the stress originally existing at the ferroelectric domain wall is dissipated, the crack a is closed, and the "on" function of the ferroelectric switching device is realized.

Wherein the first voltage U1 and the second voltage U2 have opposite polarities. For example, in some embodiments, the first voltage U1 is a positive voltage in a vertical device direction (e.g., Z direction in fig. 2), and the second voltage U2 is a negative voltage in the vertical device direction, and in other embodiments, the first voltage U1 is a negative voltage in the vertical device direction, and the second voltage U2 is a positive voltage in the vertical device direction.

In some embodiments, the electric field intensity formed by the first voltage U1 and the second voltage U2 is greater than the coercive field of the ferroelectric domain, so that the ferroelectric domain can be inverted.

In some embodiments, the first voltage U1 has the same polarity as the inversion voltage used in the fabrication of the ferroelectric switching device, and the second voltage U2 has the same polarity as the polarization voltage used in the fabrication of the ferroelectric switching device.

In some embodiments, the separation and closure of the nanocractures may be controlled by applying a cycling voltage to the ferroelectric layer 10 via the first and second electrodes 20, 30, e.g., a triangular cycling voltage and a pulsed voltage. FIG. 11A is a schematic diagram of a triangular cyclic voltage, wherein the forward voltage of the triangular cyclic voltage reaches a value, such as a peak value U _Peak(s) Ferroelectric domain inversion, stress generation, crack separation, when the negative voltage of the triangular cyclic voltage reaches a value, e.g. the valley value U _Grain The ferroelectric domain is turned over again, the stress is dispersed, and the crack is closed; FIG. 11B is a schematic diagram of a pulse cycle voltage, which is a periodic commutation pulse, when a positive pulse voltage U is applied _{Is just} When a value is reached, the ferroelectric domain is inverted to generate stress and crack separation, and when a negative pulse voltage U is reached _{Negative pole} When a value is reached, the ferroelectric domain is turned over again, the stress is dissipated and the crack is closed.

As shown in fig. 12, where (a) is a scanning electron microscope image of crack closure of the ferroelectric switching device provided by the embodiment of the present disclosure, and (b) is a scanning electron microscope image of crack separation of the ferroelectric switching device provided by the embodiment of the present disclosure, when a positive pulse voltage applied by the voltage supply circuit is +100V (a first voltage), the crack is separated (as shown by an elliptic dotted line in the figure), and when a negative pulse voltage applied by the external power supply is-100V (a second voltage), the crack is closed (as shown by an elliptic dotted line in the figure).

According to the control method of the ferroelectric switching device, provided by the embodiment of the disclosure, the separation and the closing of the crack penetrating through the conductive layer are realized by changing the polarity of the voltage, so that the switching-off and switching-on functions of the ferroelectric switching device are realized, and the ferroelectric switching device has higher speed and lower energy consumption compared with a traditional MOSFET switch. Moreover, ferroelectric-crack-based ferroelectric switching devices have abrupt switching behavior and high ON/OFF current ratios, with greatly reduced leakage; in addition, the whole conductive layer is used as a conductive channel, and at the crack, the contact area of the metal contact interface (fracture surface) of the two separated parts of the conductive layer is large, so that the contact resistance is low, and the signal transmission speed is high.

The embodiment of the disclosure also provides a three-dimensional memory. The three-dimensional memory includes a ferroelectric switching device as described above. The ferroelectric switching device can replace the traditional MOS transistor and other devices in the three-dimensional memory to realize the switching function. The ferroelectric switching device is exemplified below for use in a three-dimensional memory.

Fig. 13 is a schematic diagram of an application of a ferroelectric switching device in a three-dimensional memory according to an embodiment of the present disclosure, and referring to fig. 13, in some embodiments of the present disclosure, the three-dimensional memory includes a plurality of memory cells arranged in an array in a three-dimensional space, where the memory cells form a plurality of memory strings. For example, the first memory string 130 is formed by serially connecting memory cells 1301 to 1305, and the second memory string 131 is formed by serially connecting memory cells 1311 to 1315.

The ferroelectric switching device is correspondingly arranged on each storage string, a first electrode and a second electrode of the ferroelectric switching device are respectively and electrically connected with the corresponding drain electrode selection lines, a first signal transmission end is electrically connected with a bit line, and a second signal transmission end is electrically connected with the storage strings.

For example, a ferroelectric switching device 1306 is disposed at a top end of the first memory string 130, and the ferroelectric switching device 1306 serves as a string selection pipe of the first memory string 130. The first electrode 20 (shown in fig. 1 and 2) and the second electrode 30 (shown in fig. 1 and 2) of the ferroelectric switching device 1306 are electrically connected to the corresponding drain select line DSL, the first signal transmission terminal 60 (shown in fig. 1 and 2) is electrically connected to the bit line BL1, and the second signal transmission terminal 70 (shown in fig. 1 and 2) is electrically connected to the first memory string 130. The memory cells 1301 to 1305 are also electrically connected to word lines WL1 to WL 5.

As another example, a ferroelectric switching device 1316 is disposed at the top of the second memory string 131, and the ferroelectric switching device 1316 serves as a string selection pipe of the second memory string 131. The ferroelectric switching device 1316 has a first electrode 20 and a second electrode 30 (shown in fig. 1 and 2) electrically connected to the corresponding drain select line DSL, a first signal carrying terminal 60 (shown in fig. 1 and 2) electrically connected to the bit line BL2, and a second signal carrying terminal 70 (shown in fig. 1 and 2) electrically connected to the second memory string 131. The memory cells 1311 to 1315 are also electrically connected to word lines WL1 to WL 5.

The drain select line DSL can control the separation and closing of cracks in the ferroelectric switching device 1306 and the ferroelectric switching device 1316, so as to control the on and off of the ferroelectric switching devices, and thus control the electrical connection between the bit lines BL1 and BL2 and the memory cells.

Further, in some embodiments of the present disclosure, the bottom of each memory string is provided with the ferroelectric switching device as a source select pipe.

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 a source select pipe of the first memory string 130. The first electrode 20 (shown in fig. 1 and 2) and the second electrode 30 (shown in fig. 1 and 2) of the ferroelectric switch device 1307 are electrically connected to the corresponding source select line SSL, the first signal transmission terminal 60 (shown in fig. 1 and 2) is electrically connected to the first memory string 130, and the second signal transmission terminal 70 (shown in fig. 1 and 2) is electrically connected to the source line CSL.

As another example, a ferroelectric switch device 1317 is disposed at the bottom of the second memory string 131, and the ferroelectric switch device 1317 serves as a source select pipe of the second memory string 131. The ferroelectric switch device 1317 has a first electrode 20 and a second electrode 30 (shown in fig. 1 and 2) electrically connected to a corresponding source select line SSL, a first signal transmission terminal 60 (shown in fig. 1 and 2) electrically connected to the second memory string 131, and a second signal transmission terminal 70 (shown in fig. 1 and 2) electrically connected to a source line CSL.

The source select lines SSL are capable of controlling the separation and closing of cracks of the ferroelectric switching devices 1306 and 1316, enabling the ferroelectric switching devices to be turned on and off, thereby controlling the electrical connection of the common source line CSL with the memory cells.

In other embodiments of the present disclosure, only the ferroelectric switching device may be used as the string select transistor and the MOS transistor may be used as the source select transistor, or only the ferroelectric switching device may be used as the source select transistor and the MOS transistor may be used as the string select transistor.

The three-dimensional memory comprises a memory Array (Array) area and a peripheral circuit (peripheral) area, wherein the memory Array area is used for storing information, the peripheral circuit area can be positioned above or below the memory Array area or positioned at the Periphery of the memory Array area, and the peripheral circuit area is used for controlling the corresponding memory Array area. The ferroelectric switching device may be disposed in a peripheral circuit region.

The ferroelectric switching device can also be applied to other microelectronic devices, such as, but not limited to, a non-volatile Flash memory (Nor Flash).

The foregoing is merely a preferred embodiment of the disclosed embodiments and it should be understood that numerous changes and modifications may be made by those skilled in the art without departing from the principles of the disclosed embodiments and that such changes and modifications are to be considered within the scope of the disclosed embodiments.

Claims (20)

1. A ferroelectric switching device, comprising:

a ferroelectric layer;

the first electrode and the second electrode are arranged on two sides of the ferroelectric layer and used for applying voltage to the ferroelectric layer;

an interlayer insulating layer disposed on the second electrode;

a conductive layer disposed on the interlayer insulating layer;

the first signal transmission end and the second signal transmission end are respectively arranged on the conducting layer;

wherein a crack is formed extending from the ferroelectric layer in a direction perpendicular to the ferroelectric layer and penetrating through the second electrode, the interlayer insulating layer, and the conductive layer, the conductive layer is divided into two parts independent of each other by the crack, the first signal transmitting terminal and the second signal transmitting terminal are respectively provided on the two parts of the conductive layer divided into two parts independent of each other by the crack, and the separation and closure of the crack can be controlled by changing a direction of a voltage applied to the ferroelectric layer.

2. A ferroelectric switching device according to claim 1, wherein the ductility of the first electrode is greater than the ductility of the second electrode and the conductive layer.

3. A ferroelectric switching device according to claim 1, wherein the second electrode extends in a first lateral direction, at least a portion of the second electrode has a width in the second lateral direction smaller than that of other regions, the region of the second electrode having the smallest width in the second lateral direction is located between the first and second signal transmission terminals, and the crack is located in the region of the second electrode having the smallest width in the second lateral direction, the crack being separated or closed in the first lateral direction and extending in the second lateral direction.

4. The ferroelectric switching device of claim 3, wherein the second electrode comprises a first segment and a second segment arranged along a first lateral direction, an orthographic projection of the second segment on the ferroelectric layer between an orthographic projection of the first signal delivery end on the ferroelectric layer and an orthographic projection of the second signal delivery end on the ferroelectric layer, a width of the second segment in the second lateral direction being smaller than a width of the first segment in the second lateral direction, the crack being located in the second segment.

5. The ferroelectric switching device of claim 4, wherein an interface of the first and second segments is located between the first and second signal carrying ends, the crack being located at the interface of the first and second segments.

6. A ferroelectric switching device as in claim 5, wherein said second electrode comprises two first segments and one second segment, said two first segments being located at respective ends of said second segment in a first lateral direction, said crack being located at an interface of said second segment and one of said first segments.

7. A ferroelectric switching device according to claim 4, wherein the second segment comprises a plurality of sub-segments of different widths in a second lateral direction, the crack being located at the sub-segment of smallest width.

8. The ferroelectric switch device of claim 1, wherein the interlayer insulating layer covers a portion of a surface of the second electrode, and a first conductive terminal is disposed on an exposed surface of the second electrode.

9. A ferroelectric switching device as in claim 8, wherein said second electrode has two of said first conductive terminals disposed thereon, said two first conductive terminals being disposed on opposite sides of said crack.

10. A ferroelectric switching device according to claim 1, wherein said ferroelectric layer covers a portion of a surface of said first electrode, and a second conductive terminal is provided on an exposed surface of said first electrode.

11. The ferroelectric switching device of claim 1, wherein an orthographic projection of the second electrode on the ferroelectric layer covers an orthographic projection of the conductive layer on the ferroelectric layer.

12. A ferroelectric switching device according to claim 1, wherein the material of the first electrode is the same as the material of the first and second signal carrying terminals.

13. A ferroelectric switching device according to claim 1, wherein the material of the second electrode is the same as the material of the conductive layer.

14. The ferroelectric switching device of claim 1, wherein the material of the conductive layer comprises an intermetallic alloy material.

15. The ferroelectric switching device of claim 14, wherein said intermetallic alloy material comprises MnPt or FePt.

16. A method of making 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, a first signal transmission end and a second signal transmission end on the surface of the substrate, wherein the first signal transmission end and the second signal transmission end are arranged on the conductive layer and are independent of each other;

forming a 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 transmitting terminal and the second signal transmitting terminal, and the conductive layer being divided into two parts independent of each other by the crack, the first signal transmitting terminal and the second signal transmitting terminal being respectively provided on the two parts of the conductive layer divided into two parts independent of each other by the crack.

17. The method of making a ferroelectric switching device of claim 16, wherein the method of forming cracks comprises: applying a polarization voltage to the ferroelectric layer through the first electrode and the second electrode to make the polarization direction of the ferroelectric domain of the ferroelectric layer the same as the polarization direction of the polarization voltage;

applying a switching voltage to the ferroelectric layer through the first electrode and the second electrode, the switching voltage being opposite in polarity to the polarization voltage.

18. A method of controlling a ferroelectric switching device as claimed in any one of claims 1 to 15, comprising: and applying a first voltage to the ferroelectric layer through the first electrode and the second electrode to control the separation of the crack, and applying a second voltage to the ferroelectric layer through the first electrode and the second electrode to control the closing of the crack to realize the electrical insulation and the electrical conduction of the first signal transmission terminal and the second signal transmission terminal, wherein the polarities of the first voltage and the second voltage are opposite.

19. A three-dimensional memory comprising a ferroelectric switching device according to any one of claims 1 to 15.

20. The three-dimensional memory according to claim 19, wherein the three-dimensional memory comprises a plurality of memory cells arranged in an array in a three-dimensional space to form a plurality of memory strings, each memory string being provided with the ferroelectric switching device,

a first electrode and a second electrode of the ferroelectric switching device are respectively and electrically connected with corresponding drain electrode selection lines, a first signal transmission end is electrically connected with a bit line, and a second signal transmission end is electrically connected with the storage string; or the first electrode and the second electrode of the ferroelectric switching device are respectively electrically connected with the corresponding source selection lines, the first signal transmission end is electrically connected with the storage string, and the second signal transmission end is electrically connected with the source line.

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