Thin films and methods of making for enhanced polarization and energy storage properties based on negative capacitance effect

Abstract

The application discloses a thin film based on negative capacitance effect for enhancing polarization and energy storage characteristics and a preparation method, relates to the technical field of semiconductor devices, and comprises a substrate, a bottom electrode layer and a top electrode layer. The bottom electrode layer is deposited on the surface of the substrate, and a plurality of first antiferromagnetic layers and second antiferromagnetic layers are alternately deposited between the bottom electrode layer and the top electrode layer. The material of the first antiferromagnetic layer comprises a PbZrO3 thin film, and the material of the second antiferromagnetic layer comprises a PLZS thin film. The application alleviates the technical problem of low energy storage efficiency caused by the large hysteresis width of the antiferromagnetic body in the prior art.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor devices, and in particular to a film with enhanced polarization and energy storage properties based on a negative capacitance effect and a preparation method thereof. Background Art

[0002] Compared with electrochemical capacitors and batteries, dielectric capacitors have ultra-high power density (10 8 W / kg) and ultra-fast charge-discharge capabilities (microseconds or even nanoseconds). This energy conversion process is physical, without mass transfer or oxidation-reduction reactions. This effectively avoids risks such as leakage and explosion, making it safer and more durable. Although dielectric energy storage capacitors are widely used, they are limited by their relatively low energy storage density. In typical power electronics and pulse power systems, capacitors account for as much as 23% of the total volume and 40% of the total weight, respectively. With the rapid advancement of electronic technology and devices, miniaturization and integration are the future development directions for dielectric capacitors. Therefore, developing energy storage capacitors with high energy density, high efficiency, and long service life has become a research priority in the field of pulse power technology.

[0003] The materials currently studied in dielectric energy storage can be divided into the following categories: (1) Linear dielectrics: The polarization strength is linearly related to the electric field strength, the dielectric constant is usually very small, and almost does not change with the electric field strength, and has good stability in environments with voltage, temperature, and frequency changes. The main disadvantage is that the polarization strength is not high; (2) Ferroelectrics: They usually have a high dielectric constant, but conventional ferroelectrics have a large residual polarization strength, showing large energy loss and low energy storage efficiency; (3) Relaxor ferroelectrics: They have a "slender" hysteresis loop and show high energy storage efficiency , this type of material needs to obtain a large energy storage density under a larger voltage excitation, which obviously does not meet the requirements of device integration and miniaturization for lower operating voltage; (4) Antiferroelectric: According to the lattice dynamics soft mode theory, under the action of an external electric field, the essence of the mutual transformation between antiferroelectric and ferroelectric phases is the result of the competition between short-range forces and long-range forces. Its energy storage principle is essentially to use the external field to induce the antiferroelectric-ferroelectric phase transition to complete the storage and release of energy. Antiferroelectrics have double hysteresis loops and smaller residual polarization strength, and theoretically have a larger energy storage density.

[0004] At present, domestic and foreign researchers have adopted a variety of research methods to improve energy storage properties, including: optimizing the synthesis process to improve density, constructing core-shell structures, introducing large bandgap materials, constructing polymorphic nanodomains, and combining linear dielectrics (or relaxor ferroelectrics) with ferroelectrics. However, the essence of these methods is to obtain high energy storage density by increasing the breakdown electric field. According to the dielectric energy storage calculation formula: J reco=∫EdP, where E and P are the electric field strength and polarization strength, respectively. While increasing the breakdown electric field is certainly an effective means of increasing energy storage density, large electric fields are accompanied by large strains. Literature has reported that the electrostrain of antiferroelectric films can reach over 1%, which is detrimental to device lifespan. Unfortunately, the impact of strain effects induced by large electric fields on device lifespan has been rarely reported. With the trend toward miniaturization and higher power, the demand for device operating voltages is decreasing. Therefore, achieving high energy storage density by increasing breakdown strength is not an ideal approach.

[0005] The optimal operating electric field for antiferroelectric energy storage capacitors should be near the antiferroelectric-ferroelectric phase transition field. By increasing the polarization intensity near the antiferroelectric-ferroelectric phase transition field, a high energy storage density is achieved. This effectively avoids the lifespan issues associated with high electric fields while also meeting the low operating voltage requirements of miniaturization. It is worth noting that although antiferroelectrics theoretically possess a high energy storage density, their large hysteresis width results in energy storage efficiencies generally below 90%. Low energy storage efficiency is a common problem with antiferroelectric energy storage. Summary of the Invention

[0006] In order to solve the above technical problems existing in the prior art, the embodiments of the present invention provide a film and a preparation method based on the negative capacitance effect to enhance polarization and energy storage properties. The technical solution is as follows:

[0007] On the one hand, a film with enhanced polarization and energy storage properties based on the negative capacitance effect is provided, comprising: a substrate, a bottom electrode layer and a top electrode layer, wherein the bottom electrode layer is deposited on the surface of the substrate, and multiple layers of first antiferroelectric layers and second antiferroelectric layers are alternately deposited between the bottom electrode layer and the top electrode layer; wherein the material of the first antiferroelectric layer comprises a PbZrO3 film; and the material of the second antiferroelectric layer comprises a PLZS film.

[0008] Furthermore, the chemical formula of the PLZS film includes: Pb 0.97 La 0.02 Zr 0.55 Sn 0.45 O3.

[0009] Furthermore, the material of the substrate includes SrTiO3; the material of the bottom electrode layer includes SrRuO3; and the material of the top electrode layer includes Pt.

[0010] Furthermore, the thickness of the bottom electrode layer is greater than 10 nm; the thickness of the top electrode layer is 50 nm; and the thickness of the first antiferroelectric layer or the second antiferroelectric layer is greater than 20 nm.

[0011] On the other hand, a method for preparing a thin film with enhanced polarization and energy storage characteristics based on the negative capacitance effect is also provided, comprising: attaching the substrate to a heating support, and depositing the bottom electrode layer on the substrate using a pulsed laser deposition coating method; using a pulsed laser deposition coating method, repeatedly and alternately growing the first antiferroelectric layer and the second antiferroelectric layer on the bottom electrode layer to form a multilayer heterogeneous antiferroelectric thin film structure; and based on a photolithography method, coating the top electrode layer on the topmost layer of the multilayer heterogeneous antiferroelectric thin film structure.

[0012] Furthermore, the substrate is attached to a heating support, and the bottom electrode layer is deposited on the substrate using a pulsed laser deposition coating method, including: attaching a (001) oriented SrTiO3 substrate to a heating support with silver glue, and then heating to 150-170°C to cure the resin for 10 minutes; placing the heating support into the PLD cavity, and evacuating to 10 -3 Pa, and then rapidly heated to 680° C. at a heating rate of 10-15° C. / min, the oxygen pressure inside the cavity was adjusted to 13 Pa, and SrRuO 3 was deposited in an oxygen atmosphere to form the bottom electrode layer.

[0013] Furthermore, a pulsed laser deposition coating method is used to repeatedly and alternately grow the first antiferroelectric layer and the second antiferroelectric layer on the bottom electrode layer to form a multilayer heterogeneous antiferroelectric thin film structure, including: switching the PLD cavity temperature to 590°C, and adjusting the oxygen pressure inside the PLD cavity to 11Pa; switching the target material to PbZrO3 to deposit a PZO film on the bottom electrode layer to form the first antiferroelectric layer; then switching to a PLZS target material to deposit a PLZS film to form the second antiferroelectric layer; repeatedly and alternately growing the first antiferroelectric layer and the second antiferroelectric layer to form the multilayer heterogeneous antiferroelectric thin film structure; finally, cooling at a rate of 5°C / min and annealing in a high-pressure oxygen atmosphere.

[0014] Furthermore, based on the photolithography method, the top electrode layer is plated on the top layer of the multi-layer heterogeneous antiferroelectric thin film structure, including: transferring the pattern of the top electrode by photolithography, using magnetron sputtering to plate a layer of Pt as the top electrode layer on the top layer of the multi-layer heterogeneous antiferroelectric thin film structure, and finally using a wet method to remove the photoresist.

[0015] The embodiment of the present invention provides a film and preparation method for enhancing polarization and energy storage characteristics based on the negative capacitance effect. A multilayer heterogeneous antiferroelectric film structure is designed. From the perspective of stabilizing the polarization charge transfer in the dielectric layer, the long-range order of the antiferroelectric is broken by optimizing the multilayer antiferroelectric film structure, and a "narrow oblique" hysteresis loop with relaxation characteristics is obtained. At the same time, the antiferroelectric "negative capacitance effect" is utilized to improve the dielectric constant and polarization strength, and finally a "narrow oblique" hysteresis loop with a large polarization strength is obtained. The energy storage density, energy storage efficiency and service life can be improved at the same time, and the technical problem of low energy storage efficiency caused by the large hysteresis width of the antiferroelectric body in the prior art is alleviated. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0017] Figure 1 Schematic diagram of the structure of a film with enhanced polarization and energy storage properties based on negative capacitance effect provided by an embodiment of the present invention;

[0018] Figure 2 The present invention provides a method for preparing a thin film with enhanced polarization and energy storage properties based on the negative capacitance effect.

[0019] Figure 3 Schematic diagram of electrical performance testing of a film with enhanced polarization and energy storage properties based on negative capacitance effect provided by an embodiment of the present invention;

[0020] Figure 4 This is an XRD pattern of a PZO / PLZS multilayer film provided by an embodiment of the present invention;

[0021] Figure 5 This is an AFM image of a PZO / PLZS multilayer film provided according to an embodiment of the present invention;

[0022] Figure 6 This is a dielectric spectrum diagram of a PZO / PLZS multilayer film provided by an embodiment of the present invention;

[0023] Figure 7 This is a PZO / PLZS multilayer thin film ferroelectric loop and energy storage result diagram provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0024] The technical solution of the present invention is described below in conjunction with the accompanying drawings.

[0025] In the embodiments of the present invention, words such as "exemplarily" and "for example" are used to indicate examples, illustrations, or explanations. Any embodiment or design described as an "exemplary" in the present invention should not be interpreted as being preferred or advantageous over other embodiments or designs. Rather, the use of the word "exemplary" is intended to present concepts in a concrete manner. Furthermore, in the embodiments of the present invention, "and / or" can mean both or either of the two.

[0026] In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0027] Example 1

[0028] Figure 1 FIG is a schematic structural diagram of a film based on a negative capacitance effect to enhance polarization and energy storage characteristics according to an embodiment of the present invention. Figure 1 As shown, the structure of the film includes: a substrate 1, a bottom electrode layer 2 and a top electrode layer 3. The bottom electrode layer 2 is deposited on the surface of the substrate 1, and multiple layers of first antiferroelectric layers 4 and second antiferroelectric layers 5 are alternately deposited between the bottom electrode layer 2 and the top electrode layer 3.

[0029] Specifically, the material of the first antiferroelectric layer 4 includes a PbZrO3 thin film;

[0030] The material of the second antiferroelectric layer 5 includes a PLZS thin film.

[0031] In an optional embodiment provided by the embodiment of the present invention, the chemical formula of the PLZS film includes: Pb 0.97 La 0.02 Zr 0.55 Sn 0.45 O3.

[0032] Preferably, in an embodiment of the present invention, the material of the substrate includes SrTiO3 (STO);

[0033] The materials of the bottom electrode layer include: SrRuO3 (SRO);

[0034] The material of the top electrode layer includes Pt.

[0035] In an optional implementation provided by an embodiment of the present invention, the thickness of the bottom electrode layer is greater than 10 nm; the thickness of the top electrode layer is 50 nm; and the thickness of the first antiferroelectric layer or the second antiferroelectric layer is greater than 20 nm.

[0036] Example 2

[0037] Figure 2 The present invention provides a method for preparing a film that enhances polarization and energy storage properties based on the negative capacitance effect. Figure 2As shown, the method specifically includes the following steps:

[0038] Step S202 : attaching the substrate to a heating tray and depositing a bottom electrode layer on the substrate using a pulsed laser deposition coating method.

[0039] In step S204 , a pulsed laser deposition coating method is used to repeatedly and alternately grow a first antiferroelectric layer and a second antiferroelectric layer on the bottom electrode layer to form a multi-layer heterogeneous antiferroelectric thin film structure.

[0040] Step S206 : depositing a top electrode layer on the top layer of the multi-layer heterogeneous antiferroelectric thin film structure based on a photolithography method.

[0041] The pulsed laser deposition (PLD) method used in the thin film preparation method provided in the embodiments of the present invention is a physical vapor deposition (PVD) technique for the epitaxial growth of high-quality thin films. It uses a laser to bombard a target material, depositing the resulting plasma onto a substrate to achieve epitaxial growth. Compared to sol-gel methods, chemical solution deposition, and atomic layer deposition, PLD can uniformly coat composite materials with complex chemical compositions, easily ensuring a stable stoichiometric ratio after coating, and can produce multi-component thin films with the desired stoichiometric ratio, i.e., exhibiting excellent composition retention.

[0042] Specifically, step S202 further includes the following steps:

[0043] Step S2021, affix the (001) oriented SrTiO3 substrate to a heating tray using silver glue, and then heat to 150-170°C to cure the resin for 10 minutes;

[0044] Step S2022: Place the heating tray into the PLD chamber and evacuate to 10 -3 Pa, and then rapidly heated to 680°C at a heating rate of 10-15°C / min, the oxygen pressure inside the cavity was adjusted to 13 Pa, and SrRuO3 was deposited in an oxygen atmosphere to form a bottom electrode layer.

[0045] In the embodiment of the present invention, in order to continue to grow multilayer films, the SRO thickness is required to be greater than 10nm and have good conductivity, and the SRO surface is flat (Rq<0.5nm) to ensure subsequent high-quality epitaxial growth of multilayer films.

[0046] Specifically, step S204 further includes the following steps:

[0047] Step S2041 , switching the PLD chamber temperature to 590° C. and adjusting the oxygen pressure inside the PLD chamber to 11 Pa;

[0048] Step S2042: Switch the target material to PbZrO3 and deposit a PZO thin film on the bottom electrode layer to form a first antiferroelectric layer. In the embodiment of the present invention, considering the size effect of the antiferroelectric, the thickness of the single-layer PZO thin film is greater than 20 nm.

[0049] Step S2043, then switching to a PLZS target to deposit a PLZS thin film to form a second antiferroelectric layer;

[0050] Step S2044, repeatedly growing the first antiferroelectric layer and the second antiferroelectric layer alternately multiple times to form a multi-layer heterogeneous antiferroelectric thin film structure;

[0051] Step S2045: Finally, the temperature is lowered at a rate of 5°C / min and annealed in a high-pressure oxygen atmosphere. Preferably, the pressure of the high-pressure oxygen atmosphere is 10,000 Pa.

[0052] Specifically, step S206 further includes the following steps: transferring the pattern of the top electrode by photolithography, plating a Pt layer as the top electrode layer on the top layer of the multi-layer heterogeneous antiferroelectric thin film structure by magnetron sputtering, and finally removing the photoresist by wet method.

[0053] Example 3

[0054] Figure 3 Schematic diagram of electrical performance test of a film based on the negative capacitance effect to enhance polarization and energy storage characteristics according to an embodiment of the present invention. Figure 3 The electrical performance of the film with enhanced polarization and energy storage characteristics based on the negative capacitance effect provided by the embodiment of the present invention was tested on the structure shown. The test results are as follows:

[0055] Figure 4 This is an XRD diagram of a PZO / PLZS multilayer film provided according to an embodiment of the present invention. Figure 5 : This is an AFM image of a PZO / PLZS multilayer film provided according to an embodiment of the present invention. Figure 4 and Figure 5 As shown, the film provided by the embodiment of the present invention based on the negative capacitance effect to enhance polarization and energy storage characteristics has good crystallinity and no stray peaks (such as Figure 4 As shown in Figure 2), the surface of the multilayer film is atomically flat, with a roughness of <0.6nm (as shown in Figure 2). Figure 5 shown).

[0056] Figure 6 This is a dielectric spectrum diagram of a PZO / PLZS multilayer film provided according to an embodiment of the present invention. Figure 7 1 is a PZO / PLZS multilayer thin film ferroelectric loop and energy storage result diagram provided according to an embodiment of the present invention. Figure 6 and Figure 7As shown, the film provided by the embodiment of the present invention based on the negative capacitance effect to enhance polarization and energy storage characteristics can greatly improve the dielectric constant (such as Figure 6 ) and polarization intensity (as Figure 7 The increase in polarization strength will help increase the energy storage density (by nearly 4 times).

[0057] From the above description, it can be seen that the embodiment of the present invention provides a film and preparation method based on the negative capacitance effect to enhance the polarization and energy storage characteristics, and utilizes the superposition effect of the antiferroelectric "negative capacitance effect" and the capacitance (dielectric constant) after the conventional linear dielectric is connected in series to design a multilayer heterogeneous antiferroelectric film (PbZrO3 / Pb 0.97 La 0.02 Zr 0.55 Sn 0.45 O3, abbreviated as PZO / PLZS) structure, which improves the dielectric constant of the capacitor while obtaining large polarization strength and high energy storage density.

[0058] It should be understood that in various embodiments of the present invention, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0059] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A film with enhanced polarization and energy storage properties based on negative capacitance effect, characterized in that: include: A substrate, a bottom electrode layer and a top electrode layer, wherein the bottom electrode layer is deposited on the surface of the substrate, and multiple layers of first antiferroelectric layers and second antiferroelectric layers are alternately deposited between the bottom electrode layer and the top electrode layer; wherein, The material of the first antiferroelectric layer includes a PbZrO3 thin film; The material of the second antiferroelectric layer includes a PLZS thin film; The chemical formula of the PLZS film includes: Pb 0.97 La 0.02 Zr 0.55 Sn 0.45 O3; The material of the substrate includes SrTiO3; The material of the bottom electrode layer includes: SrRuO3; The material of the top electrode layer includes Pt.

2. The film according to claim 1, characterized in that: The thickness of the bottom electrode layer is greater than 10 nm; the thickness of the top electrode layer is 50 nm; and the thickness of the first antiferroelectric layer or the second antiferroelectric layer is greater than 20 nm.

3. A method for preparing a film having enhanced polarization and energy storage properties based on negative capacitance effect according to claim 1, characterized in that: include: The substrate is attached to a heating support, and the bottom electrode layer is deposited on the substrate by a pulsed laser deposition coating method; Using a pulsed laser deposition coating method, repeatedly and alternately growing the first antiferroelectric layer and the second antiferroelectric layer on the bottom electrode layer to form a multi-layer heterogeneous antiferroelectric thin film structure; The top electrode layer is plated on the uppermost layer of the multi-layer heterogeneous antiferroelectric thin film structure based on a photolithography method.

4. The method according to claim 3, characterized in that The substrate is attached to a heating support, and the bottom electrode layer is deposited on the substrate using a pulsed laser deposition coating method, comprising: The (001) oriented SrTiO3 substrate was attached to a heating tray with silver glue, and then heated to 150-170°C to cure the resin for 10 min; Place the heating tray into the PLD chamber and evacuate to 10 -3 Pa, and then rapidly heated to 680° C. at a heating rate of 10-15° C. / min, the oxygen pressure inside the cavity was adjusted to 13 Pa, and SrRuO 3 was deposited in an oxygen atmosphere to form the bottom electrode layer.

5. The method according to claim 3, characterized in that The first antiferroelectric layer and the second antiferroelectric layer are repeatedly and alternately grown on the bottom electrode layer by using a pulsed laser deposition coating method to form a multilayer heterogeneous antiferroelectric thin film structure, comprising: The PLD chamber temperature was switched to 590°C and the oxygen pressure inside the PLD chamber was adjusted to 11 Pa; Switching the target material to PbZrO3, depositing a PZO thin film on the bottom electrode layer to form the first antiferroelectric layer; Then, the PLZS target is switched to deposit a PLZS thin film to form the second antiferroelectric layer; Repeatedly growing the first antiferroelectric layer and the second antiferroelectric layer alternately for multiple times to form the multi-layer heterogeneous antiferroelectric thin film structure; Finally, the temperature was lowered at a rate of 5°C / min and annealed in a high-pressure oxygen atmosphere.

6. The method according to claim 3, characterized in that The top electrode layer is plated on the top layer of the multi-layer heterogeneous antiferroelectric thin film structure based on a photolithography method, comprising: The pattern of the top electrode is transferred by photolithography, a Pt layer is plated on the top layer of the multi-layer heterogeneous antiferroelectric thin film structure as the top electrode layer by magnetron sputtering, and finally the photoresist is removed by wet method.

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