Heterogeneous laminated film capacitor and preparation method and application thereof

Abstract

The invention provides a heterogeneous laminated film capacitor and a preparation method and application thereof, the heterogeneous laminated film capacitor comprises a substrate, a dielectric layer, at least one composite layer and an electrode layer which are sequentially laminated, or the heterogeneous laminated film capacitor comprises a substrate, at least one composite layer and an electrode layer which are sequentially laminated; the composite layer comprises a ferroelectric layer and a dielectric layer which are stacked, the ferroelectric layer is close to the substrate, and the dielectric layer and the ferroelectric layer are coherent. According to the heterogeneous laminated film capacitor, through the arrangement of the ferroelectric and dielectric laminated structure, the homogeneity of the film capacitor can be improved in a simple and convenient manner, so that the linetype is optimized, and the energy storage density, efficiency and breakdown voltage of the heterogeneous laminated film capacitor are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of capacitors, and relates to a heterogeneous laminated thin film capacitor, a preparation method thereof and an application thereof. Background Art

[0002] With the miniaturization of mobile communication devices and the high-speed development of CPUs, the demand for multilayer ceramic capacitors (MLCCs) has gradually increased. A multilayer ceramic capacitor has a structure in which dielectric layers and internal electrode layers are alternately laminated. Since it is a thin-layered high-dielectric constant dielectric layer, although its volume is small, it still has a large capacitance, and the energy storage density needs to be improved.

[0003] The traditional method for improving the energy storage density of thin film capacitors is to solid-solve and construct relaxor ferroelectrics. The advantage of this method is low cost, but the disadvantage is that it is difficult to control the elements and micro-morphology of the capacitor. For the dielectric of the laminated structure, the electric field strength applied to each layer becomes higher, and the influence of fine defects in the dielectric layer becomes larger, which may cause a decrease in insulation resistance (IR) or insulation breakdown, thereby impairing the reliability. When the insulation resistance is insufficient, leakage current will be generated and the dielectric loss will become larger. In addition, when insulation resistance decreases or insulation breakdown occurs during actual operation, there will be a problem of shortened lifespan.

[0004] It can be seen that the quality loss brought about by the traditional solid-solution method needs to be avoided, and it is important to ensure the reliability of multilayer ceramic capacitors in promoting the thinning of dielectric layers. Summary of the Invention

[0005] The purpose of the present invention is to provide a heterogeneous laminated thin film capacitor, a preparation method thereof and an application thereof. Through the setting of the ferroelectric and dielectric laminated structure, the heterogeneous laminated thin film capacitor can improve the homogeneity of the thin film capacitor in a simple manner, thereby optimizing the linear type and enhancing its energy storage density, efficiency and breakdown voltage.

[0006] To achieve the purpose of this invention, the following technical solutions are adopted in the present invention:

[0007] In the first aspect, the present invention provides a heterogeneous laminated thin film capacitor, which includes a substrate, a dielectric layer, at least one composite layer and an electrode layer laminated in sequence, or the heterogeneous laminated thin film capacitor includes a substrate, at least one composite layer and an electrode layer laminated in sequence;

[0008] The composite layer includes a ferroelectric layer and a dielectric layer laminated, wherein the ferroelectric layer is close to the substrate, and the dielectric layer and the ferroelectric layer are coherent.

[0009] Preferably, the number of layers of the composite layer is 1-7 layers.

[0010] Preferably, the dielectric layer comprises a first substrate material, the ferroelectric layer comprises a second substrate material, and the lattice constant of the second substrate material is 98.5-101.5% of the lattice constant of the first substrate material.

[0011] Preferably, the first substrate material comprises SrTiO 3 , KTaO 3 , CaTiO 3 , DyScO 3 or LaAlO 3 or a combination of any one or at least two of them.

[0012] Preferably, the second substrate material comprises BiFeO 3 , KNbO 3 , BaTiO 3 or PbTiO 3 or a combination of any one or at least two of them.

[0013] Preferably, the thickness of the dielectric layer is 5-100 nm, preferably 5-25 nm.

[0014] Preferably, the thickness of the ferroelectric layer is 5-100 nm, preferably 5-25 nm.

[0015] Preferably, the substrate comprises LaAlO 3 , SrTiO 3 or DyScO 3 or a combination of any one or at least two of them.

[0016] In a second aspect, the present invention provides a method for preparing a heterostacked thin film capacitor as described in the first aspect, and the preparation method comprises the following steps:

[0017] Deposit a dielectric layer and at least one composite layer on the surface of the substrate in sequence, or deposit at least one composite layer on the surface of the substrate, and then set an electrode layer to obtain the heterostacked thin film capacitor;

[0018] Depositing the composite layer comprises depositing a ferroelectric layer and a dielectric layer in sequence.

[0019] Preferably, the deposition method comprises pulsed laser deposition.

[0020] Preferably, the dielectric layer is deposited and prepared using the first substrate material.

[0021] Preferably, the ferroelectric layer is deposited and prepared using the second substrate material.

[0022] In a third aspect, the present invention provides an electronic device, and the electronic device comprises a heterostacked thin film capacitor as described in the first aspect.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] By constructing a stacked ferroelectric layer and dielectric layer, and introducing periodic open boundary conditions to the ferroelectric layer, the present invention refines the shape of the hysteresis loop, improves the energy storage density and efficiency of the thin film capacitor, and the stacked structure of the present invention can increase the interface density, hinder the carrier migration, and improve the breakdown voltage. Description of the Drawings

[0025] Figure 1 Schematic diagram of the structure of the hetero - stacked thin film capacitor according to a specific embodiment of the present invention;

[0026] Figure 2 Hysteresis loop diagram of the hetero - stacked thin film capacitor according to Embodiment 1 of the present invention;

[0027] Figure 3 Energy storage performance diagram of the hetero - stacked thin film capacitor according to Embodiment 1 of the present invention;

[0028] Wherein, 1 - substrate, 2 - dielectric layer, 3 - ferroelectric layer. Specific Embodiments

[0029] The technical solution of the present invention will be further described below through specific embodiments.

[0030] In a specific embodiment, a hetero - stacked thin film capacitor is provided. The hetero - stacked thin film capacitor includes a substrate, a dielectric layer, at least one composite layer, and an electrode layer stacked in sequence, or the hetero - stacked thin film capacitor includes a substrate, at least one composite layer, and an electrode layer stacked in sequence;

[0031] The composite layer includes a ferroelectric layer and a dielectric layer stacked together. Among them, the ferroelectric layer is close to the substrate, and the dielectric layer and the ferroelectric layer are coherent.

[0032] The hetero - stacked thin film capacitor of the present invention includes a composite layer composed of a ferroelectric layer and a dielectric layer. By alternately stacking multiple ferroelectric layers and multiple dielectric layers, and introducing periodic open boundary conditions to the ferroelectric layer, the shape of the line is refined, the energy storage density and efficiency of the thin film capacitor are improved, and the stacked structure of the present invention can increase the interface density, hinder the carrier migration, and improve the breakdown voltage.

[0033] The coherence of the dielectric layer and the ferroelectric layer in the present invention means that the grain boundaries of the dielectric layer and the ferroelectric layer are coherent, which can construct a high - quality polarization discontinuity at the ferroelectric / dielectric interface, and this polarization gradient will not be shielded by charged defects, so as to more effectively induce the topological structure of the ferroelectric layer and improve the energy storage density.

[0034] The composite layer of the present invention can be directly disposed on a substrate to form a structure including a substrate, a ferroelectric layer, a dielectric layer... a ferroelectric layer, a dielectric layer, and an electrode layer. Alternatively, a dielectric layer can be first disposed on the substrate, and then the ferroelectric layer and the dielectric layer are repeatedly disposed to form a structure such as Figure 1 shown in FIG. 1, including a substrate 1, a dielectric layer 2, a ferroelectric layer 3, a dielectric layer 2, a ferroelectric layer 3, a dielectric layer 2... a ferroelectric layer 3, a dielectric layer 2, a ferroelectric layer 3, a dielectric layer 2, and an electrode layer. Preferably, a dielectric layer is first disposed on the substrate in the present invention, and then the composite layer including the ferroelectric layer and the dielectric layer is repeatedly disposed, which can fully induce the topological polarization structure of each ferroelectric layer, thereby refining the hysteresis loop and increasing the energy storage density.

[0035] Preferably, the number of layers of the composite layer is 1-7 layers. For example, it can be 1 layer, 2 layers, 3 layers, 4 layers, 5 layers, 6 layers, or 7 layers, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0036] Exemplarily, when the number of layers of the composite layer of the present invention is 1 layer, the heterostructure thin film capacitor includes a substrate, a dielectric layer, a ferroelectric layer, a dielectric layer, and an electrode layer stacked in sequence. Alternatively, the heterostructure thin film capacitor includes a substrate, a ferroelectric layer, a dielectric layer, and an electrode layer stacked in sequence. When the number of layers of the composite layer of the present invention is 3 layers, the heterostructure thin film capacitor includes a substrate, a dielectric layer, a ferroelectric layer, a dielectric layer, a ferroelectric layer, a dielectric layer, a ferroelectric layer, a dielectric layer, and an electrode layer stacked in sequence. Alternatively, the heterostructure thin film capacitor includes a substrate, a ferroelectric layer, a dielectric layer, a ferroelectric layer, a dielectric layer, a ferroelectric layer, a dielectric layer, and an electrode layer stacked in sequence.

[0037] Preferably, the dielectric layer includes a first substrate material, the ferroelectric layer includes a second substrate material, and the lattice constant of the second substrate material is 98.5-101.5% of the lattice constant of the first substrate material. For example, it can be 98.5%, 99%, 99.5%, 100%, 100.5%, 101%, or 101.5%, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0038] When the lattice constants of the first substrate material and the second substrate material of the present invention satisfy the above range, the dielectric layer and the ferroelectric layer are coherent; the lattice constant of the second substrate material is 98.5-101.5% of the lattice constant of the first substrate material, which means that all lattice constants of the first substrate material and the second substrate material correspondingly satisfy the above range, that is, the lattice constant a of the second substrate material is 98.5-101.5% of the lattice constant a of the first substrate material, the lattice constant b of the second substrate material is 98.5-101.5% of the lattice constant b of the first substrate material, and the lattice constant c of the second substrate material is 98.5-101.5% of the lattice constant c of the first substrate material.

[0039] Preferably, the first substrate material comprises a paraelectric.

[0040] Preferably, the second substrate material comprises a ferroelectric, and the first substrate material and the second substrate material are different compounds.

[0041] Preferably, the first substrate material comprises SrTiO 3 , KTaO 3 、CaTiO 3 ,DyScO 3 or LaAlO 3 Any one or a combination of at least two of the following.

[0042] Preferably, the second substrate material comprises BiFeO 3 , KNbO 3 、BaTiO 3 or PbTiO 3 Any one or a combination of at least two of the following.

[0043] Preferably, the thickness of the dielectric layer is 5-100nm, for example, it can be 5nm, 10nm, 15nm, 20nm, 25nm, 30nm, 35nm, 40nm, 45nm, 50nm, 55nm, 60nm, 65nm, 70nm, 75nm, 80nm, 85nm, 90nm, 95nm or 100nm, but is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable, preferably 5-25nm.

[0044] Preferably, the thickness of the ferroelectric layer is 5-100 nm, for example, it can be 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 55 nm, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm or 100 nm, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable, preferably 5-25 nm.

[0045] Preferably, the thicknesses of the dielectric layer and the ferroelectric layer in the present invention are within 5-25 nm, which can make the influence of the polarization gradient on the ferroelectric layer greater, and better construct the continuous ferroelectric polarization topology in the ferroelectric layer, thereby achieving the invention effect.

[0046] Preferably, the substrate includes any one or a combination of at least two of LaAlO 3 , SrTiO 3 or DyScO 3 .

[0047] In a specific embodiment, a method for preparing the heterostructured thin-film capacitor is provided. The preparation method includes the following steps:

[0048] Deposit a dielectric layer and at least one composite layer on the surface of the substrate in sequence, or deposit at least one composite layer on the surface of the substrate, and then set an electrode layer to obtain the heterostructured thin-film capacitor;

[0049] Depositing the composite layer includes depositing a ferroelectric layer and a dielectric layer in sequence.

[0050] In the present invention, the existing solid solution method is replaced by a layer-by-layer deposition method to improve the homogeneity of the thin-film capacitor in a simple way, thereby optimizing the line type and improving its energy storage density, efficiency and breakdown voltage.

[0051] Preferably, the deposition method includes pulsed laser deposition.

[0052] Preferably, a first substrate material is used for depositing and preparing the dielectric layer.

[0053] Preferably, a second substrate material is used for depositing and preparing the ferroelectric layer.

[0054] In a specific embodiment, an electronic device is provided. The electronic device includes the heterostructured thin-film capacitor.

[0055] The technical solution of the present invention will be further described below through specific examples. Those skilled in the art should understand that the examples are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0056] Example 1

[0057] This embodiment provides a heterogeneous laminated thin-film capacitor. The heterogeneous laminated thin-film capacitor includes a substrate, a dielectric layer, a ferroelectric layer, a dielectric layer, and an electrode layer stacked in sequence (the composite layer is 1 layer);

[0058] The dielectric layer and the ferroelectric layer are coherent. The thickness of the dielectric layer is 10 nm, and the thickness of the ferroelectric layer is 10 nm;

[0059] The dielectric layer includes a first substrate material, and the first substrate material is SrTiO 3 (cubic crystal system, lattice constant ), the ferroelectric layer includes a second substrate material, and the second substrate material is BiFeO 3 (lattice constant ), and the lattice constant of the second substrate material is 101.4% of the lattice constant of the first substrate material;

[0060] The substrate includes LaAlO 3 ;

[0061] The preparation method of the heterogeneous laminated thin-film capacitor includes the following steps:

[0062] Using pulsed laser deposition, the dielectric layer, the ferroelectric layer, and the dielectric layer are sequentially deposited on the surface of the substrate by using the first substrate material and the second substrate material, and then the electrode is evaporated to obtain the heterogeneous laminated thin-film capacitor. The polarization hysteresis loop diagram of the heterogeneous laminated thin-film capacitor is as shown in Figure 2 shown. It can be seen from Figure 2 that the homogeneity of the heterogeneous laminated thin-film capacitor is improved, so the linearity of the polarization curve under different electric fields is also optimized; the energy storage performance diagram of the heterogeneous laminated thin-film capacitor is as shown in Figure 3 shown. It can be seen from Figure 3 that both the energy storage density and the energy storage efficiency of the heterogeneous laminated thin-film capacitor are improved.

[0063] Example 2

[0064] This embodiment provides a heterogeneous laminated thin-film capacitor. The heterogeneous laminated thin-film capacitor includes a substrate, a dielectric layer, a ferroelectric layer, a dielectric layer, a ferroelectric layer, a dielectric layer, a ferroelectric layer, a dielectric layer, and an electrode layer stacked in sequence (the composite layer is 3 layers);

[0065] The dielectric layer and the ferroelectric layer are coherent. The thickness of the dielectric layer is 10 nm, and the thickness of the ferroelectric layer is 10 nm;

[0066] The dielectric layer includes a first substrate material, and the first substrate material is SrTiO 3 (cubic crystal system, lattice constant ), the ferroelectric layer includes a second substrate material, and the second substrate material is BiFeO 3 (lattice constant ), and the lattice constant of the second substrate material is 101.4% of the lattice constant of the first substrate material;

[0067] The substrate includes SrTiO 3 ;

[0068] The method for preparing the heterostructured thin film capacitor includes the following steps:

[0069] Using pulsed laser deposition, depositing a dielectric layer, a ferroelectric layer, a dielectric layer, a ferroelectric layer, a dielectric layer, a ferroelectric layer, and a dielectric layer on the surface of the substrate in sequence with the first substrate material and the second substrate material, and then evaporating electrodes to obtain the heterostructured thin film capacitor.

[0070] Example 3

[0071] This example provides a heterostructured thin film capacitor, which includes a substrate, a dielectric layer, a ferroelectric layer, a dielectric layer, and an electrode layer (the composite layer is 1 layer) stacked in sequence;

[0072] The dielectric layer and the ferroelectric layer are coherent, the thickness of the dielectric layer is 10 nm, and the thickness of the ferroelectric layer is 10 nm;

[0073] The dielectric layer includes a first substrate material, and the first substrate material is KTaO 3 (cubic crystal system, lattice constant ), the ferroelectric layer includes a second substrate material, and the second substrate material is BiFeO 3 (cubic crystal system, lattice constant ), and the lattice constant of the second substrate material is 99.65% of the lattice constant of the first substrate material;

[0074] The substrate includes DyScO 3 ;

[0075] The method for preparing the heterostructured thin film capacitor includes the following steps:

[0076] Using pulsed laser deposition, depositing a dielectric layer, a ferroelectric layer, and a dielectric layer on the surface of the substrate in sequence with the first substrate material and the second substrate material, and then evaporating electrodes to obtain the heterostructured thin film capacitor.

[0077] Example 4

[0078] This embodiment provides a heterogeneous laminated thin-film capacitor. Except for including a substrate, a dielectric layer, a ferroelectric layer, a dielectric layer, a ferroelectric layer, a dielectric layer, a ferroelectric layer, a dielectric layer, a ferroelectric layer, a dielectric layer, a ferroelectric layer, a dielectric layer, a ferroelectric layer, a dielectric layer, a ferroelectric layer, a dielectric layer, and an electrode layer (the composite layer is 7 layers) which are sequentially laminated, the rest are the same as those in Embodiment 1.

[0079] Embodiment 5

[0080] This embodiment provides a heterogeneous laminated thin-film capacitor. Except for including a substrate, a ferroelectric layer, a dielectric layer, and an electrode layer which are sequentially laminated, the rest are the same as those in Embodiment 1.

[0081] Embodiment 6

[0082] This embodiment provides a heterogeneous laminated thin-film capacitor. Except that the thicknesses of both the dielectric layer and the ferroelectric layer are 5 nm, the rest are the same as those in Embodiment 1.

[0083] Embodiment 7

[0084] This embodiment provides a heterogeneous laminated thin-film capacitor. Except that the thicknesses of both the dielectric layer and the ferroelectric layer are 25 nm, the rest are the same as those in Embodiment 1.

[0085] Embodiment 8

[0086] This embodiment provides a heterogeneous laminated thin-film capacitor. Except that the thicknesses of both the dielectric layer and the ferroelectric layer are 50 nm, the rest are the same as those in Embodiment 1.

[0087] Embodiment 9

[0088] This embodiment provides a heterogeneous laminated thin-film capacitor. Except that the thicknesses of both the dielectric layer and the ferroelectric layer are 100 nm, the rest are the same as those in Embodiment 1.

[0089] Comparative Example 1

[0090] This comparative example provides a relaxor ferroelectric solid-solution capacitor. The solid solution includes 50% BiFeO 3 and 50% SrTiO 3 , with a film thickness of 100 nm, and is grown on a SrTiO 3 substrate by laser pulse deposition.

[0091] Comparative Example 2

[0092] This comparative example provides a heterogeneous laminated thin-film capacitor. Except that the first substrate material is Al2 O 3 The second substrate material is BiFeO 3 Except that the dielectric layer and the ferroelectric layer are incommensurate, the rest are the same as in Example 1.

[0093] The capacitors obtained from the above examples and comparative examples were tested for energy storage density and efficiency, and the test results are shown in Table 1:

[0094] Table 1

[0095] <![CDATA[Energy storage density (J·cm -3 )]]> Efficiency (%) Example 1 170 95 Example 2 144 88 Example 3 105 84 Example 4 99 89 Example 5 64 69 Example 6 84 79 Example 7 112 86 Example 8 77 94 Example 9 65 95 Comparative Example 1 39 49 Comparative Example 2 69 68

[0096] As can be seen from Table 1:

[0097] From Examples 1-9 and Comparative Example 1, it can be seen that by constructing a stacked structure of a ferroelectric layer and a dielectric layer, the present invention is not only simpler than the solid solution construction of a relaxor ferroelectric in Comparative Example 1, but also can improve the energy storage density and efficiency of the capacitor; from Examples 1-9 and Comparative Example 2, it can be seen that the present invention selects commensurate dielectric layer and ferroelectric layer materials, thereby significantly improving the performance of the capacitor; from Example 1 and Examples 4-5, it can be seen that the present invention preferably sets a dielectric layer on the base layer first, and then repeats the setting of the ferroelectric layer and the dielectric layer; from Example 1 and Examples 6-9, it can be seen that the present invention optimizes the thickness of the capacitor for the dielectric layer and the ferroelectric layer, improves the performance of the capacitor while saving the internal space of the capacitor, and is helpful for application in various miniaturized electronic scenarios.

[0098] In summary, the present invention provides a heterogeneous laminated thin film capacitor, a preparation method and an application thereof. By setting a laminated structure, the heterogeneous laminated thin film capacitor can improve the homogeneity of the thin film capacitor in a simple manner, thereby optimizing the linear type and improving its energy storage density, efficiency and breakdown voltage.

[0099] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by any person skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A heterogeneous laminated film capacitor, characterized in that: The heterogeneous laminated film capacitor comprises a substrate, a dielectric layer, at least one composite layer and an electrode layer which are stacked in sequence, or the heterogeneous laminated film capacitor comprises a substrate, at least one composite layer and an electrode layer which are stacked in sequence; The composite layer includes a ferroelectric layer and a dielectric layer which are stacked, wherein the ferroelectric layer is close to the substrate, and the dielectric layer and the ferroelectric layer are coherent.

2. The heterogeneous laminated film capacitor according to claim 1, characterized in that: The number of layers of the composite layer is 1-7.

3. The heterogeneous laminated film capacitor according to claim 2, characterized in that: The dielectric layer includes a first substrate material, and the ferroelectric layer includes a second substrate material, wherein the lattice constant of the second substrate material is 98.5-101.5% of the lattice constant of the first substrate material.

4. The heterogeneous laminated film capacitor according to claim 3, characterized in that: The first substrate material includes any one of SrTiO3, KTaO3, CaTiO3, DyScO3 or LaAlO3, or a combination of at least two thereof.

5. The heterogeneous laminated film capacitor according to claim 4, characterized in that: The second substrate material includes any one of BiFeO3, KNbO3, BaTiO3 or PbTiO3, or a combination of at least two thereof.

6. The heterogeneous laminated film capacitor according to any one of claims 1 to 5, characterized in that: The thickness of the dielectric layer is 5-100 nm, preferably 5-25 nm; Preferably, the thickness of the ferroelectric layer is 5-100 nm, preferably 5-25 nm; Preferably, the substrate comprises any one of LaAlO3, SrTiO3 or DyScO3 or a combination of at least two thereof.

7. A method for preparing a heterogeneous laminated film capacitor according to any one of claims 1 to 6, characterized in that: The preparation method comprises the following steps: Depositing a dielectric layer and at least one composite layer on the surface of a substrate in sequence, or depositing at least one composite layer on the surface of a substrate and then providing an electrode layer, to obtain the heterogeneous laminated film capacitor; Depositing the composite layer includes sequentially depositing a ferroelectric layer and a dielectric layer.

8. The preparation method according to claim 7, characterized in that: The deposition method includes pulsed laser deposition; Preferably, the method of providing the electrode layer includes evaporation.

9. The preparation method according to claim 7 or 8, characterized in that: Using a first substrate material to deposit and prepare the dielectric layer; Preferably, the ferroelectric layer is prepared by depositing a second substrate material.

10. An electronic device, characterized in that: The electronic device comprises the heterogeneous laminated film capacitor according to any one of claims 1 to 6.

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