Transistor with mechanical sensing and memory functions and preparation method and application thereof

Abstract

The invention relates to the technical field of semiconductors, in particular to a transistor with mechanical sensing and memory functions and a preparation method and application of the transistor. The semiconductor thin film layer is arranged on one side, close to the groove, of the substrate and covers the groove; the ferroelectric thin film layer is arranged on one side, deviating from the groove, of the semiconductor thin film layer and covers right above the groove; and the first electrode and the second electrode are respectively arranged at two ends of the semiconductor film layer and are in contact with the substrate. External force is applied to the ferroelectric film layer arranged right above the groove, so that an equivalent flexoelectric field induced by a strain gradient generated by the ferroelectric film layer under the action of the external force forms a force grid, and ferroelectric polarization of the ferroelectric film can be regulated and controlled through a flexoelectric effect; and due to the non-volatility of ferroelectric polarization in the ferroelectric film layer and the arrangement of the bottom groove, the characteristic of sensing memory response is realized, so that the transistor with the structure has mechanical sensing and memory functions at the same time.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a transistor with mechanical sensing and memory functions, and a preparation method and application thereof. Background Art

[0002] As the feature size of integrated circuits continues to shrink, Moore's Law has reached its limit, and how to design a new transistor device with integrated sensing, computing and storage has become a focus of attention. The traditional ferroelectric field-effect transistor (FeFET) is based on the direct modulation of the channel current by the electric gate. Its basic principle is to use the electric gate to flip the polarization of the ferroelectric layer and then modulate the channel current. However, the above field effect transistors all need to set an electric gate to modulate the channel current, and cannot sense changes in external mechanical signals.

[0003] At the same time, although the flexoelectric transistors designed by researchers in recent years based on the flexoelectric effect can sense mechanical signals, they cannot remember changes in mechanical loads, which seriously limits the development of the application of integrated sensing, computing and storage devices.

[0004] Therefore, the prior art still needs to be improved and developed. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, an object of the present invention is to provide a transistor with mechanical sensing and memory functions and a preparation method and application thereof, aiming to solve the problem that the existing transistors cannot memorize mechanical loads.

[0006] The technical solution of the present invention is as follows:

[0007] A transistor with mechanical sensing and memory functions, comprising:

[0008] a substrate having a groove;

[0009] A semiconductor thin film layer is disposed on a side of the substrate close to the groove and covers the groove;

[0010] A ferroelectric thin film layer is arranged on a side of the semiconductor thin film layer away from the groove and covers directly above the groove; the ferroelectric thin film layer and the semiconductor thin film layer are arranged crosswise;

[0011] The electrode layer includes a first electrode and a second electrode; the first electrode and the second electrode are respectively arranged at two ends of the semiconductor thin film layer and contact the substrate.

[0012] The transistor with mechanical sensing and memory functions, wherein the groove is filled with a soft elastomer or air with a Young's modulus lower than 1 GPa; the pore size of the groove is between 1 μm and 10 μm, and the depth of the groove is between 100 nm and 1000 μm.

[0013] In the transistor with mechanical sensing and memory functions, the thickness of the semiconductor film layer is 0.6nm-1μm; the thickness of the ferroelectric film layer is 0.7nm-3μm.

[0014] In the transistor with mechanical sensing and memory functions, the ferroelectric film layer is cross-arranged on the side of the semiconductor film layer away from the groove, and the ferroelectric film layer is arranged in contact with the substrate.

[0015] The transistor with mechanical sensing and memory functions, wherein the material of the semiconductor thin film layer includes one of molybdenum disulfide, molybdenum ditelluride, and indium selenide; the material of the ferroelectric thin film layer includes one of copper indium phosphide, barium titanate, lead titanate, lead zirconate titanate, and zirconium-doped hafnium oxide.

[0016] In the transistor with mechanical sensing and memory functions, the cross-sectional shape of the groove along the width direction is one of circular, square, rectangular, elliptical and polygonal.

[0017] The transistor with mechanical sensing and memory functions, wherein a portion of the first electrode covers the substrate, and another portion covers one end of the semiconductor thin film layer; a portion of the second electrode covers the substrate, and another portion covers the other end of the semiconductor thin film layer.

[0018] The transistor with mechanical sensing and memory functions, wherein the transistor with mechanical sensing and memory functions further includes a base layer arranged on a side of the substrate away from the groove; the base layer is an oxide thin film material.

[0019] A method for preparing a transistor with mechanical sensing and memory functions, comprising the steps of:

[0020] providing a substrate having a groove;

[0021] Disposing a semiconductor thin film layer on one side of the substrate and covering the groove;

[0022] Disposing a ferroelectric thin film layer just above the groove, crossing the semiconductor thin film and contacting the substrate;

[0023] A first electrode and a second electrode are respectively arranged at two ends of the semiconductor film layer relative to the groove, and both the first electrode and the second electrode are in contact with the substrate, thereby obtaining a transistor with mechanical sensing and memory functions.

[0024] The invention discloses an application of a transistor with mechanical sensing and memory functions in a sensing, computing and storage integrated device.

[0025] Beneficial effects: The present invention provides a transistor with mechanical sensing and memory functions, and a preparation method and application thereof. The transistor with mechanical sensing and memory functions comprises: a substrate with a groove; a semiconductor film layer, which is arranged on a side of the substrate close to the groove and covers the groove; a ferroelectric film layer, which is arranged on a side of the semiconductor film layer away from the groove and covers directly above the groove; the ferroelectric film layer and the semiconductor film layer are arranged crosswise; an electrode layer, comprising a first electrode and a second electrode; the first electrode and the second electrode are respectively arranged at two ends of the semiconductor film layer and in contact with the substrate. The present invention applies an external force to the ferroelectric film layer arranged directly above the groove, so that the ferroelectric film layer generates an equivalent flexoelectric field induced by the strain gradient under the action of the external force to form a "force gate", which can regulate the ferroelectric polarization of the ferroelectric film through the flexoelectric effect, and then regulate the carrier concentration of the semiconductor film layer to regulate the conductivity between the first electrode and the second electrode without the need to set up an additional gate; and due to the non-volatility of the ferroelectric polarization in the ferroelectric film layer and the setting of the bottom groove, the characteristics of sensing memory mechanical response are achieved, so that the transistor of this structure has both mechanical sensing and memory functions. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the structure of a transistor with mechanical sensing and memory functions according to the present invention;

[0027] Figure 2 A schematic diagram of a top view of a transistor with mechanical sensing and memory functions according to the present invention;

[0028] Figure 3 Another schematic diagram of the structure of a transistor with mechanical sensing and memory functions according to the present invention;

[0029] Figure 4 Schematic diagram of the initial ferroelectric polarization of the transistor;

[0030] Figure 5 Schematic diagram of ferroelectric polarization of transistor under external force;

[0031] Figure 6 is a double potential well curve diagram;

[0032] Figure 7This is a schematic diagram of the ferroelectric polarization of the transistor when the external force is removed;

[0033] Figure 8 The source-drain current diagram of the transistor before and after the force is applied;

[0034] Fig. 9 Phase field simulation diagram and experimental result diagram of polarization evolution of ferroelectric thin film layer in transistor;

[0035] Explanation of the reference numerals: substrate 10 , groove 11 , semiconductor thin film layer 20 , ferroelectric thin film layer 30 , electrode layer 40 , first electrode 41 , second electrode 42 , base layer 50 . DETAILED DESCRIPTION

[0036] The present invention provides a transistor with mechanical sensing and memory functions and a preparation method and application thereof. In order to make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0037] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as generally understood by those skilled in the art in the art to which the present invention belongs. It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless specifically defined as herein.

[0038] like Figure 1 and Figure 2 As shown, the present invention provides a transistor with mechanical sensing and memory functions, comprising:

[0039] A substrate 10 having a groove 11;

[0040] A semiconductor thin film layer 20 is disposed on a side of the substrate 10 close to the groove 11 and covers the groove 11;

[0041] The ferroelectric thin film layer 30 is disposed on a side of the semiconductor thin film layer 20 away from the groove 11 and covers directly above the groove 11; the ferroelectric thin film layer 30 and the semiconductor thin film layer 20 are disposed crosswise;

[0042] The electrode layer 40 includes a first electrode 41 and a second electrode 42 . The first electrode 41 and the second electrode 42 are respectively disposed at two ends of the semiconductor thin film layer 20 and in contact with the substrate 10 .

[0043] In this embodiment, the semiconductor film layer is covered on the surface of the substrate on the side where the groove is provided, and both ends of the semiconductor film layer are covered on the substrate outside the groove, and then a ferroelectric film layer is arranged in a cross-stacked form on the side of the semiconductor film layer away from the groove, and the ferroelectric film layer is covered directly above the groove covered by the existing semiconductor film layer and contacts the substrate, and finally a first electrode and a second electrode are respectively arranged at both ends of the semiconductor film layer, and the first electrode and the second electrode are not in contact with the ferroelectric film layer; in the transistor of this structure, the ferroelectric polarization of the ferroelectric film layer directly above the groove is configured to be regulated by an equivalent flexural electric field under an external force load, thereby modulating the conductivity between the first electrode and the second electrode of the bottom semiconductor film, so that the transistor provided by the present invention can realize mechanical force control to control the conduction state of the transistor without the use of an additional electric gate, and realize a non-volatile transistor structure integrating sensing, computing and storage, thereby solving the volatility problem of the transport properties of the flexural electric regulation transistor in the past.

[0044] Specifically, the semiconductor film is covered on the groove part in the form of a long strip slightly wider than the groove part, and both ends of the semiconductor film layer are covered on the substrate outside the groove part; the long strip ferroelectric film layer slightly wider than the hole groove part is covered in a cross manner directly above the semiconductor film with the groove part, and the first electrode and the second electrode are arranged on both sides of the groove, the first electrode and the second electrode are respectively in contact with the two ends of the semiconductor film layer, and all electrodes are not in contact with the ferroelectric film layer; by applying an external force to the ferroelectric film layer arranged directly above the groove, the strain gradient induced equivalent flexoelectric field generated by the ferroelectric film layer under the action of the external force is used to form a "force gate", which can regulate the ferroelectric polarization of the ferroelectric film through the flexoelectric effect, and then regulate the carrier concentration of the semiconductor film layer to regulate the conductivity between the first electrode and the second electrode, without the need to set up an additional gate; and due to the non-volatility of the ferroelectric polarization in the ferroelectric film layer and the setting of the bottom groove, the characteristics of sensing memory mechanical response are achieved, so that the transistor of this structure has both mechanical sensing and memory functions.

[0045] In some embodiments, the groove is filled with a soft elastic body with a Young's modulus lower than 1 GPa or air; the pore size of the groove is between 1 μm and 10 μm, and the depth of the groove is between 100 nm and 1000 μm. Filling the groove with a soft elastic body with a Young's modulus lower than 1 GPa can make the elastic recovery of the semiconductor film layer and the ferroelectric film layer disposed directly above the groove better, and if not filled, it is assumed to be air. Setting the pore size and depth of the groove within the above range can provide sufficient space for mechanical sensing and regulation.

[0046] Specifically, when the cross section of the groove is circular, the aperture size of the groove is controlled between 1 μm and 10 μm. The range of adjustable force and flexoelectric effect calculated within this size range are strong enough to meet the subsequent regulation function. When the cross section of the groove is square, the side length of the groove is between 1 μm and 10 μm, which also has the same effect.

[0047] In a preferred embodiment, the aperture of the groove is between 3 μm and 6 μm, and the depth of the groove is between 100 nm and 10 μm.

[0048] In some embodiments, the soft elastomer may be but is not limited to polydimethylsiloxane (PDMS). Filling the groove with the soft elastomer PDMS can help the elastic recovery of the semiconductor film layer and the ferroelectric film layer, and can significantly improve the fatigue resistance of the ferroelectric field effect transistor.

[0049] In some embodiments, the thickness of the semiconductor film layer is 0.6nm-1μm, and the semiconductor film layer of this thickness can ensure that the carriers can be effectively controlled under the electric field of this thickness; the thickness of the ferroelectric film layer is 0.7nm-3μm, and the ferroelectric film layer of this thickness can ensure that the ferroelectric film has sufficiently stable ferroelectricity, and the thicker the thickness of the ferroelectric film layer, the better the stability of the ferroelectricity. The specific thickness can be selected according to the type of ferroelectric film layer material.

[0050] In a preferred embodiment, the thickness of the semiconductor thin film layer is greater than 0.6 nm but not more than 50 nm. The thinner the thickness of the semiconductor thin film layer is, the better, so that effective control of carriers under the depolarization field can be achieved.

[0051] In some embodiments, the ferroelectric film layer is cross-arranged on the side of the semiconductor film layer away from the groove, and the ferroelectric film layer is arranged in contact with the substrate. The ferroelectric film layer and the semiconductor film layer are cross-arranged, and the ferroelectric film layer is arranged in contact with the substrate, so that the semiconductor film layer serves as the channel layer of the transistor, and the ferroelectric film layer serves as the gate layer of the transistor; on the one hand, the ferroelectric polarization can be regulated by the equivalent flexural electric field generated by the ferroelectric film layer under the action of an external force, and the conductivity between the first electrode and the second electrode can be regulated by further regulating the carrier concentration of the semiconductor film layer by the polarization state of the ferroelectric film, without the need to set up an additional electric gate, so that the structure of the transistor can be simplified; on the other hand, due to the non-volatility of the ferroelectric polarization in the ferroelectric film layer and the elastic recovery of the air or soft elastic body filled in the bottom groove, the characteristics of the perceptual memory mechanical response are achieved.

[0052] Specifically, the spontaneous polarization of the ferroelectric film layer is related to the stress condition, loading sequence and thermal annealing condition of the area above the groove; wherein, the loading sequence and thermal annealing will affect the actual conduction state of the transistor. When the external force on the ferroelectric film layer is greater than a predetermined threshold, the ferroelectric polarization inside the ferroelectric film layer is flipped by the equivalent flexural electric field, and the conductivity of the transistor is improved. When the external force is removed, the ferroelectric polarization inside the ferroelectric film layer continues to be maintained, and the conductivity of the transistor is still in an improved state, and the switching state of the transistor is close to 80 times.

[0053] In some embodiments, the material of the semiconductor thin film layer includes but is not limited to one of the common narrow bandgap semiconductors such as molybdenum disulfide (MoS2), molybdenum ditelluride (MoTe2), indium selenide (InSe), etc. The semiconductor thin film layer of this material can ensure that there are sufficient carriers for external field regulation; the material of the ferroelectric thin film layer includes but is not limited to one of the commonly used ferroelectric thin films such as copper indium phosphide (CuInP2S6), barium titanate (BaTiO3), lead titanate (PbTiO3), lead zirconate titanate (PZT), zirconium-doped hafnium oxide (HfZrO4), etc. The ferroelectric thin film layer selected from this type of material has a certain stability, which is convenient for subsequent mechanical regulation, and can ensure the stability of ferroelectricity while meeting the thickness requirements.

[0054] In a preferred embodiment, the material of the semiconductor thin film layer is molybdenum disulfide (MoS2), and the material of the ferroelectric thin film layer is copper indium phosphide (CuInP2S6).

[0055] In some embodiments, the cross-sectional shape of the groove along the width direction is, but not limited to, one of a circle, a square, a rectangle, an ellipse, and a polygon. The cross-sectional shape can provide sufficient space for mechanical sensing and regulation.

[0056] In some embodiments, the cross-sectional shape of the groove along the width direction is circular, and the semiconductor thin film layer is a long strip slightly wider than the radius of the groove. At this time, the two ends of the semiconductor thin film layer are the two ends of the long strip semiconductor, and the top of the groove on the substrate is completely covered with the semiconductor thin film layer.

[0057] In another embodiment, when the semiconductor thin film layer is circular, the two ends of the semiconductor thin film layer are two arc segments on the semiconductor thin film layer; it should be noted that the semiconductor thin film layer can also be other appropriate shapes, such as an elliptical shape, which can also achieve the same effect.

[0058] In some embodiments, a portion of the first electrode covers the substrate, and another portion covers one end of the semiconductor thin film layer; a portion of the second electrode covers the substrate, and another portion covers the other end of the semiconductor thin film layer.

[0059] Specifically, the first electrode is a source electrode, the second electrode is a drain electrode, a portion of the source electrode is covered on the substrate, and another portion contacts one end of the semiconductor thin film layer, a portion of the drain electrode is covered on the substrate, and another portion contacts the other end of the semiconductor thin film layer; that is, the first electrode and the second electrode are arranged at the two ends of the semiconductor thin film layer relative to the groove, and do not contact the ferroelectric thin film layer. In some other embodiments, the first electrode may also be a drain electrode, and the second electrode may also be a source electrode. By covering a portion of the first electrode and the second electrode at the two ends of the semiconductor thin film layer respectively, the end of the semiconductor thin film can be fixed, so that the elastic recovery of the semiconductor thin film layer can be better achieved.

[0060] In another embodiment, the first electrode and the second electrode may also completely cover both ends of the semiconductor thin film layer, so as to better fix the semiconductor thin film layer; in addition, the first electrode and the second electrode may not cover the semiconductor thin film layer, for example, they may be arranged between the semiconductor thin film layer and the substrate or in contact with the semiconductor thin film layer.

[0061] In some embodiments, the material of the substrate is but not limited to a silicon-based material, and the silicon-based material includes but is not limited to one of single crystal silicon, silicon dioxide, silicon nitride, and silicon carbide.

[0062] In some embodiments, Figure 3 As shown, the transistor with mechanical sensing and memory functions further includes a base layer 50 disposed on a side of the substrate 10 away from the groove 11; the base layer is an oxide thin film material.

[0063] In some embodiments, the shape and size of the base layer are adapted to the shape and size of the transistor, and is used to support the substrate. The base layer can be a base material retained when manufacturing the transistor, or an insulating layer formed on the base material by vacuum evaporation, vapor deposition, spin coating, etc., which is not limited here.

[0064] In some embodiments, the oxide thin film material includes but is not limited to one of silicon dioxide, hafnium oxide, and aluminum oxide.

[0065] In some embodiments, the substrate is formed on the base layer, and a groove is formed on the substrate. For example, the substrate can be first formed on the base layer, and then the groove is formed on the substrate by etching; the substrate with the groove can also be directly formed on the base layer, for example, by growing the substrate with the groove on the base layer by chemical vapor deposition (metal-organicchemical vapor deposition, MOCVD) or molecular beam epitaxy (molecular beamepitaxy, MBE). By setting the substrate and the base layer, the groove can be formed on the substrate in a variety of ways, so that the groove portion can be formed on the substrate more conveniently.

[0066] In summary, the present invention arranges a groove under the semiconductor film layer, fills the groove with air or a soft elastomer that can provide elastic recovery, and then arranges a ferroelectric sensing memory storage layer (i.e., a ferroelectric film layer) on the side of the semiconductor film layer away from the groove, further highlighting the advantages of the integrated sensing, computing and storage device; further, the sensing memory storage function of the ferroelectric film layer is reflected in the polarization direction of the ferroelectric film layer, that is, the upward polarization can be regarded as 1, and the downward polarization can be regarded as 0, and the two different directions can be maintained inside the material after the external electric field or external force is removed.

[0067] In some implementations, after the transistor exceeds the ferroelectric Curie temperature once, the entire memory storage state will be restored to the initial state, ie, annealing reset, which is also within the scope of the embodiments of the present application.

[0068] In addition, the present invention also provides a method for preparing a transistor with mechanical sensing and memory functions, comprising the steps of:

[0069] Step S10: providing a substrate having a groove;

[0070] Step S20: disposing a semiconductor thin film layer on one side of the substrate and covering the groove;

[0071] Step S30: disposing a ferroelectric thin film layer directly above the groove, crossing the semiconductor thin film and contacting the substrate;

[0072] Step S40: a first electrode and a second electrode are respectively arranged at two ends of the semiconductor thin film layer relative to the groove, and both the first electrode and the second electrode are in contact with the substrate, so as to obtain a transistor with mechanical sensing and memory functions.

[0073] In this embodiment, the semiconductor film layer is covered on the surface of the substrate on the side where the groove is provided, and both ends of the semiconductor film layer are covered on the substrate outside the groove, and then a ferroelectric film layer is arranged in a cross-stacked form on the side of the semiconductor film layer away from the groove, and the ferroelectric film layer is covered directly above the groove covered by the existing semiconductor film layer and contacts the substrate, and finally a first electrode and a second electrode are respectively arranged at both ends of the semiconductor film layer, and the first electrode and the second electrode are not in contact with the ferroelectric film layer; in the transistor of this structure, the ferroelectric polarization of the ferroelectric film layer directly above the groove is configured to be regulated by an equivalent flexural electric field under an external force load, thereby modulating the conductivity between the first electrode and the second electrode of the bottom semiconductor film, so that the transistor provided by the present invention can realize mechanical force control to control the conduction state of the transistor without the use of an additional electric gate, and realize a non-volatile transistor structure integrating sensing, computing and storage, thereby solving the volatility problem of the transport properties of the flexural electric regulation transistor in the past.

[0074] In the present invention, the transistor with mechanical sensing and memory function, when no external force is applied, has an initial ferroelectric polarization schematic diagram as shown in Figure 4 As shown; when an external force is applied to the ferroelectric thin film layer, the schematic diagram of the ferroelectric polarization of the transistor under the external force is shown in Figure 5 shown.

[0075] Specifically, the ferroelectric film bends under the action of external force, and there are two typical states: the entire film bends downward or bends upward. In this embodiment, an atomic force probe indentation is used, and the film bends downward; the bent configuration will form a huge strain gradient-induced flexoelectric field inside the ferroelectric film. The strain gradient can be written as follows:

[0076]

[0077] In cylindrical coordinates (r, θ, z), w is the deflection of the circular suspended sheet with fixed support edges, P is the magnitude of the applied tip force, a is the actual radius of the aperture in the concave area, and D is the bending stiffness of the entire film. The flexoelectric field E induced by the lateral strain gradient can be further written as T

[0078] E T =f 3113 (εrr,z+εθθ,z) (1.3)

[0080] where f 3113is the transverse flexoelectric coefficient. For the CIPS (CuInP2S6) ferroelectric film used, the direction of the flexoelectric field is perpendicular to the direction of the curved convex surface of the ferroelectric film. In short, the flexoelectric field corresponding to the downward-bending film points downward, and the flexoelectric field corresponding to the upward-bending film points upward.

[0081] In order to further understand the effect of flexoelectric field on ferroelectric polarization, the total free energy function F of ferroelectric thin film CIPS is introduced. The total free energy F is given by the Landau energy density (f land ), gradient energy density (f grad ), elastic energy density (f elas ), electrostrictive energy density (f es ), flexural electric energy density (f flexo ) and electrostatic energy density (f elec ) Points obtained

[0082] F = ∫ V {f land +f grad +f elas +f es +f flexo +f elec}dV(1.4)

[0083] The Landau free energy density function of the ferroelectric thin film CIPS is expanded as follows:

[0084] f land =α3(TT C )P3 2 +α 33 P3 4 +α 333 P3 6 (1.5)

[0086] Among them, α3, α 33 , α 333 is the Landau energy coefficient, T is the actual temperature, T C is the Curie temperature, which is 302 K in the simulation. Similarly, the spatial derivative of the in-plane polarization component is neglected, and the simplified gradient energy density is written as

[0087]

[0088] The Voigt symbol of the gradient coefficient is g 33 =g 3333 , g 44 =g 3232 , g 55 =g 3131The subscripts “,1,,2,,3” are represented by “,i”, and the subscript “,i” represents the coordinate x i The density functions of elastic energy, electrostrictive energy, and flexoelectric energy can be written as

[0089]

[0090] where c ijkl is the elastic constant, ε ij represents strain, q ijkl and f ijkl Represent the electrostrictive and flexoelectric coupling coefficients respectively. ijkl ,q ijkl and f ijkl Since the in-plane polarization component is much smaller than the out-of-plane component, the terms P1, P2, and the spatial derivative P are ignored in the same way as above. 1,i , P 2,i (i=1,2,3) second-order terms. In addition, only the strain gradient ε is considered in the phase field model. 11,3 , ε 22 ,3,ε 33,3 and ε 13,3 , because the other magnitudes are too small to be ignored. The last term is the electrostatic energy density, obtained by Legendre transformation, which can be expressed as

[0091]

[0092] Where κ0 is the dielectric constant of vacuum, κ ij Relative dielectric constant, E i is the electric field intensity component. According to electrostatics theory, the electric field intensity component It is the electric potential.

[0093] To understand the flipping effect of the flexoelectric field on polarization, the total free energy F can be written as a function of the independent variable polarization P3, and the corresponding F-P3 energy curve can be plotted as Figure 6 In the double potential well curve form of (a), under the introduction of the flexoelectric field, the overall double potential well will tilt, and the corresponding polarization will flip. In short, the downward bending film induces a downward flexoelectric field, which makes the double potential well tilt in the downward direction of polarization, and the polarization turns more to the downward direction, as shown in Figure 1. Figure 6 (b) in Fig. 2; Similarly, the upwardly bent film induces an upward flexoelectric field, which causes the double potential well to tilt in the upward direction of polarization, and the polarization is more turned to the upward direction, as shown in Fig. Figure 6 Middle (c).

[0094] In this embodiment, the schematic diagram of the ferroelectric polarization of the transistor when the external force is removed is as follows: Figure 7 As shown, after the force is removed, due to the hysteresis characteristics of ferroelectric polarization, the flipped polarization state will not change due to the removal of the force.

[0095] In addition, the present invention also provides an application of a transistor with mechanical sensing and memory functions in a sensing, computing and storage integrated device.

[0096] The following examples are further given to illustrate the present invention in detail. It should also be understood that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention belong to the scope of protection of the present invention.

[0097] Example 1

[0098] The specific parameters of the transistor are as follows: the diameter of the groove is 3 μm, the depth is 300 nm; the length of the semiconductor film layer is 25 μm, the width is 5 μm; the length of the ferroelectric film layer is 18 μm, the width is 4 μm; the width of the first electrode and the second electrode are both 10 μm, and the length is 100 μm. The material of the semiconductor film layer is molybdenum disulfide, the material of the ferroelectric film layer is copper indium phosphorus sulfur, and the substrate is a silicon-based material.

[0099] A force is applied to the transistor of this embodiment, and the source-drain current diagram before and after the force is applied is as follows: Figure 8 As shown in the figure, with -1V as the working voltage, the ratio of the source-drain current under the applied force to the source-drain current in the initial state is nearly 80 times, and it can still be maintained after the force is removed. The experimental process is as follows: Place the prepared silicon wafer with transistors on the scanning platform of the atomic force microscope, lead out the electrodes by bonding, connect them to the source meter, and ground the source. The initial structure of the ferroelectric domain of the ferroelectric film layer is characterized by the piezoelectric force response module of the atomic force microscope, and the position of the transistor hole depression is determined by the difference in resonant frequency. Then, the tip is used to apply force, including the process of pressing the tip down and lifting the tip. At the same time, the source meter is used to record the change in current. Finally, the ferroelectric domain structure of the ferroelectric film layer is characterized by the piezoelectric force response module.

[0100] In addition, the phase field simulation diagram and experimental result diagram of the polarization evolution of the ferroelectric thin film layer in the transistor are provided as follows Fig. 9 As shown, Fig. 9 (a) is the simulated initial domain structure, (b) is the simulated domain structure after force is applied, (c) is the amplitude of the initial domain structure, (d) is the phase of the initial domain structure, (e) is the amplitude of the domain structure after force is applied, and (f) is the phase of the domain structure after force is applied.

[0101] Specifically, the ferroelectric domain structure and its evolution process of CIPS are simulated according to the phase field model, in which the polarization P iThe spatiotemporal evolution of (i=1,2,3) is controlled by the time-dependent Ginzburg-Landau (TDGL) equations

[0102]

[0103] Where L is the kinetic coefficient that controls the mobility of domain evolution, F represents the total free energy of the entire system, r and t represent the spatial position vector and time respectively. The total free energy F is shown in Equation 1.4.

[0104] In addition to TDGL, the mechanical equilibrium equation also includes the contribution of the strain gradient

[0105]

[0106] and Maxwell's equations

[0107] where σ ij and t ijl are stress and higher-order stress components, ε ij,l is the strain gradient component, D i is the electric displacement component, and the ferroelectric material satisfies the conditions of no body force, negligible inertia and no body charge.

[0108] Finally, the ferroelectric film bends under the action of external force, and the corresponding polarization evolution result is as follows Fig. 9 As shown in (a) and (b) in .

[0109] Comparison of domain structures of ferroelectric thin film before and after testing Fig. 9 As shown in (c)-(f) in the figure, part of the upward polarization is flipped to downward polarization under the action of the needle tip force (corresponding to the increase of the downward area). Due to the limited force applied (to prevent device damage), the corresponding change in source-drain current is only 80 times. If a larger force is applied later to make more polarization flip, the change in source-drain current can be greater.

[0110] Therefore, the domains in the ferroelectric thin film layer in the initially prepared ferroelectric field effect transistor are in randomly distributed islands, corresponding to the general electrical conduction state in the semiconductor thin film layer; and under the action of external force at a certain threshold, the ferroelectric thin film layer bends, and the equivalent flexural electric field induced by the internal strain gradient flips the ferroelectric polarization, thereby regulating the polarization charge distribution of the semiconductor thin film layer, resulting in a negative potential near the interface of the semiconductor thin film layer, which can attract holes near the interface and form a certain concentration of carriers in the semiconductor thin film layer, and finally show a higher conductivity in the source-drain current result, as shown in Fig. 9 The ferroelectric polarization flipped in this process is shown as Figure 6As shown in Figure 2, the results of phase field simulation are basically consistent with the piezoelectric force response results of the experimental piezoelectric force microscope test; after the external force is removed, the domains originally in the ferroelectric film layer continue to maintain the same direction after being unified under the external force, and the corresponding source-drain current results continue to show higher conductivity, as shown in Figure 2. Fig. 9 shown.

[0111] In summary, the present invention provides a transistor with mechanical sensing and memory functions, and a preparation method and application thereof. The transistor with mechanical sensing and memory functions includes: a substrate with a groove; a semiconductor film layer, which is arranged on a side of the substrate close to the groove and covers the groove; a ferroelectric film layer, which is arranged on a side of the semiconductor film layer away from the groove and covers directly above the groove; the ferroelectric film layer and the semiconductor film layer are arranged crosswise; an electrode layer, including a first electrode and a second electrode; the first electrode and the second electrode are respectively arranged at two ends of the semiconductor film layer and in contact with the substrate. The present invention applies an external force to the ferroelectric film layer arranged directly above the groove, so that the ferroelectric film layer generates an equivalent flexoelectric field induced by the strain gradient under the action of the external force to form a "force gate", which can regulate the ferroelectric polarization of the ferroelectric film through the flexoelectric effect, and then regulate the carrier concentration of the semiconductor film layer to regulate the conductivity between the first electrode and the second electrode without the need to set up an additional gate; and due to the non-volatility of the ferroelectric polarization in the ferroelectric film layer and the setting of the bottom groove, the characteristics of sensing memory mechanical response are achieved, so that the transistor of this structure has both mechanical sensing and memory functions.

[0112] It should be understood that the application of the present invention is not limited to the above examples. For ordinary technicians in this field, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A transistor with mechanical sensing and memory functions, characterized in that: include: a substrate having a groove; A semiconductor thin film layer is disposed on a side of the substrate close to the groove and covers the groove; A ferroelectric thin film layer is disposed on a side of the semiconductor thin film layer away from the groove and covers directly above the groove; The ferroelectric thin film layer and the semiconductor thin film layer are arranged crosswise; The electrode layer includes a first electrode and a second electrode; the first electrode and the second electrode are respectively arranged at two ends of the semiconductor thin film layer and contact the substrate.

2. The transistor with mechanical sensing and memory functions according to claim 1, characterized in that: The groove is filled with a soft elastic body with a Young's modulus lower than 1 GPa or air; the pore size of the groove is between 1 μm and 10 μm, and the depth of the groove is between 100 nm and 1000 μm.

3. The transistor with mechanical sensing and memory functions according to claim 1, characterized in that: The thickness of the semiconductor thin film layer is 0.6nm-1μm; the thickness of the ferroelectric thin film layer is 0.7nm-3μm.

4. The transistor with mechanical sensing and memory functions according to claim 1, characterized in that: The ferroelectric film layer is cross-arranged on a side of the semiconductor film layer away from the groove, and the ferroelectric film layer is contacted with the substrate.

5. The transistor with mechanical sensing and memory functions according to claim 1, characterized in that: The material of the semiconductor film layer includes one of molybdenum disulfide, molybdenum ditelluride, and indium selenide; the material of the ferroelectric film layer includes one of copper indium phosphide, barium titanate, lead titanate, lead zirconate titanate, and zirconium-doped hafnium oxide.

6. The transistor with mechanical sensing and memory functions according to claim 1, characterized in that: The cross-sectional shape of the groove along the width direction is one of circular, square, rectangular, elliptical and polygonal.

7. The transistor with mechanical sensing and memory functions according to claim 1, characterized in that: A portion of the first electrode covers the substrate, and another portion covers one end of the semiconductor thin film layer; a portion of the second electrode covers the substrate, and another portion covers the other end of the semiconductor thin film layer.

8. The transistor with mechanical sensing and memory functions according to claim 1, characterized in that: The transistor with mechanical sensing and memory functions also includes a base layer arranged on a side of the substrate away from the groove; the base layer is an oxide thin film material.

9. A method for preparing a transistor with mechanical sensing and memory functions as claimed in any one of claims 1 to 8, characterized in that: Includes steps: providing a substrate having a groove; Disposing a semiconductor thin film layer on one side of the substrate and covering the groove; Disposing a ferroelectric thin film layer just above the groove, crossing the semiconductor thin film and contacting the substrate; A first electrode and a second electrode are respectively arranged at two ends of the semiconductor film layer relative to the groove, and both the first electrode and the second electrode are in contact with the substrate, thereby obtaining a transistor with mechanical sensing and memory functions.

10. Application of the transistor with mechanical sensing and memory functions as claimed in any one of claims 1 to 8 in a sensing, computing and storage integrated device.

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