A multilayer thin film capacitor based on strain effect

Abstract

The application discloses a multilayer thin film capacitor based on a strain effect, and relates to the technical field of multilayer thin film capacitors, which is prepared by a preparation method comprising the following steps: step S1, preparing a SrCa2Al2O6 sacrificial layer; step S2, depositing a SrRuO3 electrode; step S3, preparing an MLFC precursor solution; step S4, preparing an MLFC; step S5, preparing a multilayer MLFC; step S6, cutting; step S7, dissolving the sacrificial layer and an acrylic resin glue; and step S8, replacing a flexible substrate. The multilayer thin film capacitor based on the strain effect has a large capacity and a small loss, and can realize more convenient strain application and substrate strain transmission on the multilayer thin film capacitor.

Description

Technical Field

[0001] This invention relates to the field of multilayer thin-film capacitor technology, and more particularly to a multilayer thin-film capacitor based on strain effect. Background Technology

[0002] Thin-film capacitors have always been important components in microelectronics and optoelectronics. To meet the demands of microelectronics for miniaturization, integration, and planarization, research on multilayer thin-film capacitors has been undertaken both domestically and internationally. Multilayer thin-film capacitors use laminated ceramic thin films as layers, connected by coated electrodes. Essentially, this increases the capacitance area (S), resulting in advantages such as small size, large capacitance, high mechanical strength, low internal inductance, excellent high-frequency performance, and high reliability.

[0003] Multilayer thin-film capacitors (MLFCs) can significantly increase capacitance, but the thin-film ferroelectric material barium titanate often loses its dielectric constant, thus reducing its capacitance. Strain engineering, by applying compressive strain, can significantly improve the c / a ratio of the material, thereby increasing the dielectric response. However, MLFCs are often quite thick, and substrate clamping alone is not feasible. Furthermore, the presence of electrodes between different dielectric layers hinders the transfer of substrate-fitted strain. Therefore, achieving more convenient strain application and substrate strain transfer in multilayer thin-film capacitors is a pressing problem for researchers in the field.

[0004] In view of this, the present invention provides a multilayer thin film capacitor based on strain effect. The method for preparing this multilayer thin film capacitor enables more convenient strain application and substrate strain transfer on the multilayer thin film capacitor, resulting in a multilayer thin film capacitor with large capacitance and low loss. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a multilayer thin-film capacitor based on strain effect. The preparation method of this multilayer thin-film capacitor can realize more convenient strain application and substrate strain transfer on the multilayer thin-film capacitor, and the resulting multilayer thin-film capacitor has large capacitance and low loss.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is: a multilayer thin-film capacitor based on strain effect, manufactured by a preparation method including the following steps:

[0007] Step S1: Preparation of SrCa2Al2O6 sacrificial layer: Strontium source, calcium source and aluminum source are mixed according to stoichiometric ratio, ball-milled, dried and calcined; after calcination, ball-milled again, PVA glue is added to granulate and press into tablets, the pressed tablets are sintered to form a target material; SrCa2Al2O6 sacrificial layer is deposited on the substrate surface using pulsed laser deposition.

[0008] Step S2, Deposit SrRuO3 electrode: Deposit a SrRuO3 electrode on the SrCa2Al2O6 sacrificial layer prepared in step S1;

[0009] Step S3, Preparation of MLFC precursor solution: According to the following general chemical formula Bi 3.15 Nd 0.85 Ti3O 12 Bismuth nitrate, neodymium nitrate, and titanium nitrate were dissolved in an organic solvent and heated and stirred in a closed environment at 80-150°C for 1-3 hours. Then, the mixture was cooled to room temperature and stirred for another 1-3 hours to obtain a 0.1-0.4 M MLFC precursor solution.

[0010] Step S4, MLFC preparation: The MLFC precursor solution aged for 1-3 days is deposited on the surface of a SrRuO3 electrode by spin coating. The coated wet film is baked at 180-210℃ for 4-6 minutes, then pyrolyzed at 400-430℃ for 10-15 minutes, and finally crystallized by thermal annealing to form a deposited thin film; a monolayer MLFC is obtained; a silver electrode is magnetron sputtered at one end of the monolayer MLFC using a patterned mask.

[0011] Step S5: Preparation of multilayer MLFC: Repeat step S4 on the obtained single-layer MLFC until a certain number of MLFC layers are obtained; wherein, the silver electrode magnetron sputtering should be applied sequentially and alternately along the two ends of the long axis of the MLFC on the upper and lower MLFC layers.

[0012] Step S6, Cutting: After bonding the substrate with acrylic resin, cut along a pair of adjacent sides of the electrode to obtain the capacitor;

[0013] Step S7, Dissolution of sacrificial layer and acrylic resin adhesive: Immerse the capacitor in room temperature filtered deionized water to dissolve the SrCa2Al2O6 sacrificial layer and acrylic resin adhesive.

[0014] Step S8, Replacement of the flexible substrate: The capacitor after removing the sacrificial layer and acrylic resin adhesive in step S7 is transferred to the ideal flexible substrate to obtain a multilayer thin film capacitor based on the strain effect.

[0015] Preferably, the substrate in step S1 is any one of SrTiO3 substrate, Si substrate, DyScO3 substrate, TbScO3 substrate, and LaAlO3 substrate.

[0016] Preferably, the strontium source in step S1 is strontium carbonate; the calcium source is calcium carbonate; and the aluminum source is aluminum oxide.

[0017] Preferably, the calcination temperature in step S1 is 750-830℃ and the time is 1-3h.

[0018] Preferably, the sintering temperature in step S1 is 1300-1400℃ and the time is 8-10h.

[0019] Preferably, the specific parameters for pulsed laser deposition in step S1 are: oxygen pressure 2 × 10⁻⁶. -6 mbar, temperature 700℃, laser energy 1.5 J·cm -2 .

[0020] Preferably, the mass ratio of strontium source to PVA adhesive in step S1 is 100:(2-5).

[0021] Preferably, the organic solvent in step S3 is one or more of 2-methoxyethanol, propionic acid, ethylene glycol, and acetic acid.

[0022] Preferably, the crystallization temperature of the hot annealing process in step S4 is 650–780°C, and the holding time is 100–150 minutes.

[0023] Preferably, the multilayer MLFC in step S5 has 10 layers and a single layer thickness of 300 nm.

[0024] Preferably, the flexible substrate in step S8 is any one of PDMS, Al foil, and PET.

[0025] Due to the application of the above technical solutions, the present invention has the following beneficial effects: by depositing MLFC on a flexible substrate, applying compressive strain to improve the dielectric constant of the device, and through the reasonable selection and matching of the composition of ferroelectric thin film, sacrificial layer and electrode layer, the multilayer thin film capacitor produced has large capacitance and low loss. Detailed Implementation

[0026] The following description is intended to disclose the invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art.

[0027] Example 1

[0028] A multilayer thin-film capacitor based on strain effect is fabricated by a method comprising the following steps:

[0029] Step S1: Preparation of SrCa2Al2O6 sacrificial layer: Strontium source, calcium source and aluminum source are mixed according to stoichiometric ratio, ball-milled, dried and calcined; after calcination, ball-milled again, PVA glue is added to granulate and press into tablets, the pressed tablets are sintered to form a target material; SrCa2Al2O6 sacrificial layer is deposited on the substrate surface using pulsed laser deposition.

[0030] Step S2, Deposit SrRuO3 electrode: Deposit a SrRuO3 electrode on the SrCa2Al2O6 sacrificial layer prepared in step S1;

[0031] Step S3, Preparation of MLFC precursor solution: According to the following general chemical formula Bi 3.15 Nd 0.85 Ti3O 12 Bismuth nitrate, neodymium nitrate, and titanium nitrate were dissolved in an organic solvent and heated and stirred at 80°C in a closed environment for 1 hour. Then, the mixture was cooled to room temperature and stirred for another hour to obtain a 0.1 M MLFC precursor solution.

[0032] Step S4, MLFC preparation: The MLFC precursor solution aged for 1 day was deposited on the surface of SrRuO3 electrode by spin coating. The coated wet film was baked at 180°C for 4 minutes, then pyrolyzed at 400°C for 10 minutes, and finally crystallized by thermal annealing to form a deposited thin film; a monolayer MLFC was obtained; a patterned mask was used to magnetron sputter a silver electrode at one end of the monolayer MLFC.

[0033] Step S5: Preparation of multilayer MLFC: Repeat step S4 on the obtained single-layer MLFC until a certain number of MLFC layers are obtained; wherein, the silver electrode magnetron sputtering should be applied sequentially and alternately along the two ends of the long axis of the MLFC on the upper and lower MLFC layers.

[0034] Step S6, Cutting: After bonding the substrate with acrylic resin, cut along a pair of adjacent sides of the electrode to obtain the capacitor;

[0035] Step S7, Dissolution of sacrificial layer and acrylic resin adhesive: Immerse the capacitor in room temperature filtered deionized water to dissolve the SrCa2Al2O6 sacrificial layer and acrylic resin adhesive.

[0036] Step S8, Replacement of the flexible substrate: The capacitor after removing the sacrificial layer and acrylic resin adhesive in step S7 is transferred to the ideal flexible substrate to obtain a multilayer thin film capacitor based on the strain effect.

[0037] The substrate in step S1 is an SrTiO3 substrate; the strontium source in step S1 is strontium carbonate; the calcium source is calcium carbonate; the aluminum source is alumina; the calcination temperature in step S1 is 750℃ and the time is 1 hour; the sintering temperature in step S1 is 1300℃ and the time is 8 hours; the specific parameters for pulsed laser deposition in step S1 are: oxygen pressure 2 × 10⁻⁶. -6 mbar, temperature 700℃, laser energy 1.5 J·cm -2 The mass ratio of strontium source to PVA adhesive in step S1 is 100:2.

[0038] The organic solvent mentioned in step S3 is 2-methoxyethanol; the crystallization temperature of the thermal annealing process mentioned in step S4 is 650℃, and the holding time is 100 minutes; the number of layers of the multilayer MLFC mentioned in step S5 is 10 layers, and the thickness of a single layer is 300nm; the flexible substrate mentioned in step S8 is PDMS; the bending of the flexible substrate is r = -10mm.

[0039] Example 2

[0040] A multilayer thin-film capacitor based on strain effect is fabricated by a method comprising the following steps:

[0041] Step S1: Preparation of SrCa2Al2O6 sacrificial layer: Strontium source, calcium source and aluminum source are mixed according to stoichiometric ratio, ball-milled, dried and calcined; after calcination, ball-milled again, PVA glue is added to granulate and press into tablets, the pressed tablets are sintered to form a target material; SrCa2Al2O6 sacrificial layer is deposited on the substrate surface using pulsed laser deposition.

[0042] Step S2, Deposit SrRuO3 electrode: Deposit a SrRuO3 electrode on the SrCa2Al2O6 sacrificial layer prepared in step S1;

[0043] Step S3, Preparation of MLFC precursor solution: According to the following general chemical formula Bi 3.15 Nd 0.85 Ti3O 12 Bismuth nitrate, neodymium nitrate, and titanium nitrate were dissolved in an organic solvent and heated and stirred at 100°C in a closed environment for 1.5 hours. Then, the mixture was cooled to room temperature and stirred for another 1.5 hours to obtain a 0.2 M MLFC precursor solution.

[0044] Step S4, MLFC preparation: The MLFC precursor solution aged for 1.5 days was deposited on the surface of a SrRuO3 electrode by spin coating. The coated wet film was baked at 190°C for 4.5 minutes, then pyrolyzed at 410°C for 12 minutes, and finally crystallized by thermal annealing to form a deposited thin film; a monolayer MLFC was obtained; a silver electrode was magnetron sputtered at one end of the monolayer MLFC using a patterned mask.

[0045] Step S5: Preparation of multilayer MLFC: Repeat step S4 on the obtained single-layer MLFC until a certain number of MLFC layers are obtained; wherein, the silver electrode magnetron sputtering should be applied sequentially and alternately along the two ends of the long axis of the MLFC on the upper and lower MLFC layers.

[0046] Step S6, Cutting: After bonding the substrate with acrylic resin, cut along a pair of adjacent sides of the electrode to obtain the capacitor;

[0047] Step S7, Dissolution of sacrificial layer and acrylic resin adhesive: Immerse the capacitor in room temperature filtered deionized water to dissolve the SrCa2Al2O6 sacrificial layer and acrylic resin adhesive.

[0048] Step S8, Replacement of the flexible substrate: The capacitor after removing the sacrificial layer and acrylic resin adhesive in step S7 is transferred to the ideal flexible substrate to obtain a multilayer thin film capacitor based on the strain effect.

[0049] The substrate mentioned in step S1 is a Si substrate; the strontium source mentioned in step S1 is strontium carbonate; the calcium source is calcium carbonate; the aluminum source is alumina; the calcination temperature in step S1 is 770℃, and the time is 1.5h; the sintering temperature in step S1 is 1330℃, and the time is 8.5h; the specific parameters for pulsed laser deposition in step S1 are: oxygen pressure 2×10⁻⁶. -6 mbar, temperature 700℃, laser energy 1.5 J·cm -2 The mass ratio of strontium source and PVA adhesive in step S1 is 100:3.

[0050] The organic solvent mentioned in step S3 is propionic acid; the crystallization temperature of the thermal annealing process in step S4 is 680℃, and the holding time is 110 minutes; the number of layers of the multilayer MLFC mentioned in step S5 is 10 layers, and the thickness of a single layer is 300nm; the flexible substrate mentioned in step S8 is Al foil; the bending of the flexible substrate is r = -10mm.

[0051] Example 3

[0052] A multilayer thin-film capacitor based on strain effect is fabricated by a method comprising the following steps:

[0053] Step S1: Preparation of SrCa2Al2O6 sacrificial layer: Strontium source, calcium source and aluminum source are mixed according to stoichiometric ratio, ball-milled, dried and calcined; after calcination, ball-milled again, PVA glue is added to granulate and press into tablets, the pressed tablets are sintered to form a target material; SrCa2Al2O6 sacrificial layer is deposited on the substrate surface using pulsed laser deposition.

[0054] Step S2, Deposit SrRuO3 electrode: Deposit a SrRuO3 electrode on the SrCa2Al2O6 sacrificial layer prepared in step S1;

[0055] Step S3, Preparation of MLFC precursor solution: According to the following general chemical formula Bi 3.15 Nd 0.85 Ti3O 12 Bismuth nitrate, neodymium nitrate, and titanium nitrate were dissolved in an organic solvent and heated and stirred at 120°C in a closed environment for 2 hours. Then, the mixture was cooled to room temperature and stirred for another 2 hours to obtain a 0.25 M MLFC precursor solution.

[0056] Step S4, MLFC preparation: The MLFC precursor solution aged for 2 days was deposited on the surface of SrRuO3 electrode by spin coating. The coated wet film was baked at 195°C for 5 minutes, then pyrolyzed at 415°C for 13 minutes, and finally crystallized by thermal annealing to form a deposited thin film; a monolayer MLFC was obtained; a silver electrode was magnetron sputtered at one end of the monolayer MLFC using a patterned mask.

[0057] Step S5: Preparation of multilayer MLFC: Repeat step S4 on the obtained single-layer MLFC until a certain number of MLFC layers are obtained; wherein, the silver electrode magnetron sputtering should be applied sequentially and alternately along the two ends of the long axis of the MLFC on the upper and lower MLFC layers.

[0058] Step S6, Cutting: After bonding the substrate with acrylic resin, cut along a pair of adjacent sides of the electrode to obtain the capacitor;

[0059] Step S7, Dissolution of sacrificial layer and acrylic resin adhesive: Immerse the capacitor in room temperature filtered deionized water to dissolve the SrCa2Al2O6 sacrificial layer and acrylic resin adhesive.

[0060] Step S8, Replacement of the flexible substrate: The capacitor after removing the sacrificial layer and acrylic resin adhesive in step S7 is transferred to the ideal flexible substrate to obtain a multilayer thin film capacitor based on the strain effect.

[0061] The substrate in step S1 is a DyScO3 substrate; the strontium source is strontium carbonate; the calcium source is calcium carbonate; the aluminum source is alumina; the calcination temperature in step S1 is 790℃, and the time is 2 hours; the sintering temperature in step S1 is 1350℃, and the time is 9 hours; the specific parameters for pulsed laser deposition are: oxygen pressure 2 × 10⁻⁶. -6 mbar, temperature 700℃, laser energy 1.5 J·cm -2 The mass ratio of the strontium source to the PVA adhesive is 100:3.5.

[0062] The organic solvent mentioned in step S3 is ethylene glycol; the crystallization temperature of the thermal annealing process in step S4 is 720℃, and the holding time is 130 minutes; the number of layers of the multilayer MLFC mentioned in step S5 is 10 layers, and the thickness of a single layer is 300nm; the flexible substrate mentioned in step S8 is PET; the bending radius of the flexible substrate is r = -15mm.

[0063] Example 4

[0064] A multilayer thin-film capacitor based on strain effect is fabricated by a method comprising the following steps:

[0065] Step S1: Preparation of SrCa2Al2O6 sacrificial layer: Strontium source, calcium source and aluminum source are mixed according to stoichiometric ratio, ball-milled, dried and calcined; after calcination, ball-milled again, PVA glue is added to granulate and press into tablets, the pressed tablets are sintered to form a target material; SrCa2Al2O6 sacrificial layer is deposited on the substrate surface using pulsed laser deposition.

[0066] Step S2, Deposit SrRuO3 electrode: Deposit a SrRuO3 electrode on the SrCa2Al2O6 sacrificial layer prepared in step S1;

[0067] Step S3, Preparation of MLFC precursor solution: According to the following general chemical formula Bi 3.15 Nd 0.85 Ti3O 12 Bismuth nitrate, neodymium nitrate, and titanium nitrate were dissolved in an organic solvent and heated and stirred at 140°C in a closed environment for 2.5 hours. Then, the mixture was cooled to room temperature and stirred for another 2.5 hours to obtain a 0.1-0.4 M MLFC precursor solution.

[0068] Step S4, MLFC preparation: The MLFC precursor solution aged for 2.5 days was deposited on the surface of a SrRuO3 electrode by spin coating. The coated wet film was baked at 205°C for 5.5 minutes, then pyrolyzed at 425°C for 14 minutes, and finally crystallized by thermal annealing to form a deposited thin film; a monolayer MLFC was obtained; a silver electrode was magnetron sputtered at one end of the monolayer MLFC using a patterned mask.

[0069] Step S5: Preparation of multilayer MLFC: Repeat step S4 on the obtained single-layer MLFC until a certain number of MLFC layers are obtained; wherein, the silver electrode magnetron sputtering should be applied sequentially and alternately along the two ends of the long axis of the MLFC on the upper and lower MLFC layers.

[0070] Step S6, Cutting: After bonding the substrate with acrylic resin, cut along a pair of adjacent sides of the electrode to obtain the capacitor;

[0071] Step S7, Dissolution of sacrificial layer and acrylic resin adhesive: Immerse the capacitor in room temperature filtered deionized water to dissolve the SrCa2Al2O6 sacrificial layer and acrylic resin adhesive.

[0072] Step S8, Replacement of the flexible substrate: The capacitor after removing the sacrificial layer and acrylic resin adhesive in step S7 is transferred to the ideal flexible substrate to obtain a multilayer thin film capacitor based on the strain effect.

[0073] In step S1, the substrate is a TbScO3 substrate; the strontium source is strontium carbonate; the calcium source is calcium carbonate; the aluminum source is alumina; the calcination temperature is 820℃ for 2.5 hours; the sintering temperature is 1380℃ for 9.5 hours; and the specific parameters for pulsed laser deposition are: oxygen pressure 2 × 10⁻⁶. -6 mbar, temperature 700℃, laser energy 1.5 J·cm -2 The mass ratio of the strontium source to the PVA adhesive is 100:4.5.

[0074] The organic solvent in step S3 is acetic acid; the crystallization temperature of the thermal annealing process in step S4 is 770℃, and the holding time is 140 minutes; the number of layers of the multilayer MLFC in step S5 is 10, and the thickness of a single layer is 300nm; the flexible substrate in step S8 is PDMS; the bending of the flexible substrate is r = -10mm.

[0075] Example 5

[0076] A multilayer thin-film capacitor based on strain effect is fabricated by a method comprising the following steps:

[0077] Step S1: Preparation of SrCa2Al2O6 sacrificial layer: Strontium source, calcium source and aluminum source are mixed according to stoichiometric ratio, ball-milled, dried and calcined; after calcination, ball-milled again, PVA glue is added to granulate and press into tablets, the pressed tablets are sintered to form a target material; SrCa2Al2O6 sacrificial layer is deposited on the substrate surface using pulsed laser deposition.

[0078] Step S2, Deposit SrRuO3 electrode: Deposit a SrRuO3 electrode on the SrCa2Al2O6 sacrificial layer prepared in step S1;

[0079] Step S3, Preparation of MLFC precursor solution: According to the following general chemical formula Bi 3.15 Nd 0.85 Ti3O 12 Bismuth nitrate, neodymium nitrate, and titanium nitrate were dissolved in an organic solvent and heated and stirred at 150°C in a closed environment for 3 hours. Then, the mixture was cooled to room temperature and stirred for another 3 hours to obtain a 0.4 M MLFC precursor solution.

[0080] Step S4, MLFC preparation: The MLFC precursor solution aged for 3 days was deposited on the surface of SrRuO3 electrode by spin coating. The coated wet film was baked at 210°C for 6 minutes, then pyrolyzed at 430°C for 15 minutes, and finally crystallized by thermal annealing to form a deposited thin film; a monolayer MLFC was obtained; a silver electrode was magnetron sputtered at one end of the monolayer MLFC using a patterned mask.

[0081] Step S5: Preparation of multilayer MLFC: Repeat step S4 on the obtained single-layer MLFC until a certain number of MLFC layers are obtained; wherein, the silver electrode magnetron sputtering should be applied sequentially and alternately along the two ends of the long axis of the MLFC on the upper and lower MLFC layers.

[0082] Step S6, Cutting: After bonding the substrate with acrylic resin, cut along a pair of adjacent sides of the electrode to obtain the capacitor;

[0083] Step S7, Dissolution of sacrificial layer and acrylic resin adhesive: Immerse the capacitor in room temperature filtered deionized water to dissolve the SrCa2Al2O6 sacrificial layer and acrylic resin adhesive.

[0084] Step S8, Replacement of the flexible substrate: The capacitor after removing the sacrificial layer and acrylic resin adhesive in step S7 is transferred to the ideal flexible substrate to obtain a multilayer thin film capacitor based on the strain effect.

[0085] The substrate in step S1 is a LaAlO3 substrate; the strontium source is strontium carbonate; the calcium source is calcium carbonate; the aluminum source is alumina; the calcination temperature is 830℃ and the time is 3 hours; the sintering temperature is 1400℃ and the time is 10 hours; the specific parameters of the pulsed laser deposition are: oxygen pressure 2 × 10⁻⁶. -6 mbar, temperature 700℃, laser energy 1.5 J·cm -2 The mass ratio of the strontium source to the PVA adhesive is 100:5.

[0086] The organic solvent mentioned in step S3 is 2-methoxyethanol; the crystallization temperature of the thermal annealing process in step S4 is 780℃, and the holding time is 150 minutes; the number of layers of the multilayer MLFC mentioned in step S5 is 10 layers, and the thickness of a single layer is 300nm; the flexible substrate mentioned in step S8 is Al foil; the bending of the flexible substrate is r = -10mm.

[0087] Comparative Example 1

[0088] A multilayer thin-film capacitor based on strain effect is basically the same as in Example 1, except that the flexible substrate is not bent.

[0089] Comparative Example 2

[0090] A multilayer thin-film capacitor based on strain effect is basically the same as in Example 1, except that BaTiO3 is used instead of Bi. 3.15 Nd 0.85 Ti3O 12 .

[0091] To further illustrate the beneficial technical effects of the multilayer film capacitors based on strain effect involved in the various embodiments of the present invention, the capacitance and loss of the multilayer film capacitors based on strain effect involved in Examples 1-5 and Comparative Examples 1-2 were tested according to the current national standards of my country or conventional methods in the industry. The test results are shown in Table 1.

[0092] Table 1

[0093] Test Project Capacity loss unit uF ％ Example 1 1.25 0.72 Example 2 1.32 0.68 Example 3 1.36 0.62 Example 4 1.38 0.60 Example 5 1.41 0.57 Comparative Example 1 1.17 1.36 Comparative Example 2 1.12 1.03

[0094] As can be seen from Table 1, the multilayer thin-film capacitors based on strain effect involved in the embodiments of the present invention have larger capacitance and lower loss than the comparative product. 3.15 Nd 0.85 Ti3O 12 The use of flexible substrates and bending of flexible substrates have a beneficial effect on improving the above properties.

[0095] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A multilayer thin film capacitor based on strain effect, characterized in that, It is prepared by a method including the following steps: Step S1: Preparation of SrCa2Al2O6 sacrificial layer: Strontium source, calcium source and aluminum source are mixed according to stoichiometric ratio, ball-milled, dried and calcined; after calcination, ball-milled again, PVA glue is added to granulate and press into tablets, the pressed tablets are sintered to form a target material; SrCa2Al2O6 sacrificial layer is deposited on the substrate surface using pulsed laser deposition. Step S2, Deposit SrRuO3 electrode: Deposit a SrRuO3 electrode on the SrCa2Al2O6 sacrificial layer prepared in step S1; Step S3, Preparation of MLFC precursor solution: According to the following general chemical formula Bi 3.15 Nd 0.85 Ti3O 12 Bismuth nitrate, neodymium nitrate, and titanium nitrate were dissolved in an organic solvent and heated and stirred in a closed environment at 80-150°C for 1-3 hours. Then, the mixture was cooled to room temperature and stirred for another 1-3 hours to obtain a 0.1-0.4 M MLFC precursor solution. Step S4, MLFC preparation: The MLFC precursor solution aged for 1-3 days is deposited on the surface of a SrRuO3 electrode by spin coating. The coated wet film is baked at 180-210℃ for 4-6 minutes, then pyrolyzed at 400-430℃ for 10-15 minutes, and finally crystallized by thermal annealing to form a deposited thin film; a monolayer MLFC is obtained; a gold electrode is magnetron sputtered at one end of the monolayer MLFC using a patterned mask. Step S5: Preparation of multilayer MLFC: Repeat step S4 on the obtained single-layer MLFC until a certain number of MLFC layers are obtained; wherein, the silver electrode magnetron sputtering should be applied sequentially and alternately along the two ends of the long axis of the MLFC on the upper and lower MLFC layers. Step S6, Cutting: After bonding the substrate with acrylic resin, cut along a pair of adjacent sides of the electrode to obtain the capacitor; Step S7, Dissolution of sacrificial layer and acrylic resin adhesive: Immerse the capacitor in room temperature filtered deionized water to dissolve the SrCa2Al2O6 sacrificial layer and acrylic resin adhesive. Step S8, Replacement of the flexible substrate: The capacitor after removing the sacrificial layer and acrylic resin adhesive in step S7 is transferred to the ideal flexible substrate to obtain a multilayer thin film capacitor based on the strain effect.

2. The multilayer thin film capacitor based on strain effect according to claim 1, wherein, The substrate mentioned in step S1 is any one of SrTiO3 substrate, Si substrate, DyScO3 substrate, TbScO3 substrate, and LaAlO3 substrate.

3. The multilayer thin film capacitor based on strain effect according to claim 1, wherein, In step S1, the strontium source is strontium carbonate; the calcium source is calcium carbonate; and the aluminum source is aluminum oxide.

4. The multilayer thin film capacitor based on strain effect according to claim 1, wherein, The calcination temperature in step S1 is 750-830℃, and the time is 1-3h.

5. The multilayer thin film capacitor based on strain effect according to claim 1, wherein, The sintering temperature in step S1 is 1300-1400℃, and the time is 8-10h.

6. The multilayer thin-film capacitor based on strain effect according to claim 1, characterized in that, The specific parameters for pulsed laser deposition in step S1 are: oxygen pressure 2 × 10⁻⁶. -6 mbar, temperature 700℃, laser energy 1.5 J·cm -2 The mass ratio of strontium source to PVA adhesive in step S1 is 100:(2-5).

7. The multilayer thin film capacitor based on strain effect according to claim 1, wherein, The organic solvent mentioned in step S3 is one or more of 2-methoxyethanol, propionic acid, ethylene glycol, and acetic acid.

8. The multilayer thin film capacitor based on strain effect according to claim 1, wherein, The crystallization temperature of the hot annealing process in step S4 is 650-780℃, and the holding time is 100-150 minutes.

9. The multilayer thin film capacitor based on strain effect according to claim 1, wherein, The multilayer MLFC described in step S5 has 10 layers, and the thickness of a single layer is 300 nm.

10. The multilayer thin film capacitor based on strain effect according to claim 1, wherein, The flexible substrate mentioned in step S8 is any one of PDMS, Al foil, and PET.