High dielectric constant ceramic substrate and preparation method thereof

Abstract

The invention discloses a high-dielectric-constant ceramic substrate and a preparation method thereof, and relates to the technical field of ceramic substrate preparation, in particular to a semi-conductive SrTiO3 ceramic substrate and an insulating film. Insulating films are arranged on two opposite planes of the SrTiO3 ceramic substrate; wherein pure aluminum is sputtered to two surfaces of the SrTiO3 ceramic substrate through magnetron vacuum sputtering to form aluminum films, and then heat treatment is carried out; forming an Al2O3 layer on the surface of the aluminum thin film and forming a doped interface layer on an interface between the aluminum thin film and the SrTiO3 ceramic substrate; the Al2O3 layer and the doped interface layer form an insulating film; the thickness of the Al2O3 layer of the insulating film is increased along with the heat treatment time, so that the higher the insulation and voltage resistance of the ceramic substrate with the high dielectric constant performance is, the lower the dielectric loss is; on a single-layer ceramic dielectric capacitor, a high capacitance and volume ratio is achieved, and the technical problems that an existing single-layer ceramic dielectric capacitor is low in capacitance and volume ratio and high in dielectric loss are solved.

Description

Technical Field

[0001] The invention relates to the technical field of ceramic substrate preparation, and in particular to a high dielectric constant ceramic substrate and a preparation method thereof. Background Art

[0002] Ceramic capacitors are widely used electronic components in modern electronic technology, especially in the fields of high-speed signal processing, high-frequency circuits, overvoltage protection, etc. They are of irreplaceable importance. As a type of ceramic capacitor, single-layer ceramic capacitors have been widely used in many applications due to their simple structure and high voltage resistance.

[0003] Advantages of single-layer ceramic capacitors:

[0004] High voltage resistance: Single-layer ceramic capacitors have higher voltage resistance than multilayer ceramic capacitors.

[0005] Good stability: Due to its simple structure and mature manufacturing process, single-layer ceramic capacitors have good stability.

[0006] Small size, suitable for high-frequency applications: Single-layer ceramic capacitors are relatively small in size and are suitable for high-frequency circuits. They can effectively filter signal noise and ensure stable operation of the circuit.

[0007] High reliability: Due to its simple structure, single-layer ceramic capacitors rarely have problems such as internal short circuits, so their failure rate is low and their reliability is high, making them suitable for use in electronic products that require high stability.

[0008] However, as electronic devices become increasingly multifunctional, the performance requirements for capacitors are constantly increasing. Single-layer ceramic capacitors face a series of technical challenges in their development. Currently, single-layer ceramic capacitors mainly have the following problems:

[0009] 1. Small capacitance: The capacitance of single-layer ceramic capacitors is usually small, which limits their use in some applications that require higher capacitance, such as high-power power supply filtering or energy storage.

[0010] 2. Larger size: Compared with multilayer ceramic capacitors, single-layer ceramic capacitors have a larger volume at the same capacitance; as the demand for miniaturization of electronic equipment increases, single-layer ceramic capacitors are not as advantageous as multilayer ceramic capacitors in designs with limited space.

[0011] 3. High dielectric loss: Although single-layer ceramic capacitors have good high-frequency characteristics, their dielectric loss is still high under certain high-frequency working conditions, which may affect their performance. Especially in high-frequency pulse signals, the problem of high dielectric loss may cause the capacitor to heat up and affect the stability of the circuit.

[0012] 4. Material dependence: Single-layer ceramic capacitors usually rely on specific ceramic materials (such as barium titanate, etc.), which may experience performance degradation under high temperature or other extreme working conditions, affecting the long-term stability and reliability of the capacitor.

[0013] As an important type of ceramic capacitor, single-layer ceramic capacitors occupy an important position in modern electronic technology due to their advantages such as high voltage resistance, strong stability and high reliability. However, with the advancement of technology and changes in application requirements, single-layer ceramic capacitors still face challenges in terms of capacitance, volume and dielectric loss.

[0014] In summary, it is found that the prior art has at least the following technical problems:

[0015] Existing single-layer ceramic capacitors have technical problems of low capacitance to volume ratio and high dielectric loss. Summary of the invention

[0016] The object of the present invention is to provide a high dielectric constant ceramic substrate and a preparation method thereof, so as to solve the technical problems of low capacitance to volume ratio and high dielectric loss in existing single-layer ceramic capacitors.

[0017] The various technical effects that can be produced by the preferred technical solutions among the various technical solutions provided by the present invention are described in detail below.

[0018] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0019] The invention provides a high dielectric constant ceramic substrate, comprising a semiconducting SrTiO3 ceramic substrate and an insulating film, wherein the insulating film is arranged on two opposite planes of the SrTiO3 ceramic substrate; wherein pure aluminum is sputtered onto two surfaces of the SrTiO3 ceramic substrate to form aluminum films on the two surfaces of the SrTiO3 ceramic substrate; the thickness of the aluminum film increases with the sputtering time, and the thickness of the aluminum film is 0.1 to 3.0 μm; the SrTiO3 ceramic substrate sputtered with the aluminum film is placed in a muffle furnace, heated to a heat treatment temperature within 30 minutes, and then heat-insulated to achieve heat treatment; after the heat treatment is completed, the SrTiO3 ceramic substrate ... The SrTiO3 ceramic substrate is naturally cooled to room temperature; thereby an Al2O3 layer is formed on the surface of the aluminum film, and a doped interface layer is formed at the interface between the aluminum film and the SrTiO3 ceramic substrate; the Al2O3 layer and the doped interface layer constitute the insulating film; the SrTiO3 ceramic substrate and the two layers of the insulating film arranged opposite to each other constitute a high dielectric constant performance ceramic substrate; the thickness of the insulating film on the SrTiO3 ceramic substrate is 0.1 to 3.0 um; the thickness of the Al2O3 layer of the insulating film increases with the heat treatment time, so that the insulating withstand voltage performance of the high dielectric constant performance ceramic substrate is higher and the dielectric loss is lower.

[0020] In one of the embodiments, the thickness of the SrTiO3 ceramic substrate is 0.1-0.3 mm.

[0021] In one embodiment, the pure aluminum is 90.0% to 99.9% aluminum.

[0022] In one of the embodiments, the sputtering time of the SrTiO3 ceramic substrate is controlled within 1 min to 30 min.

[0023] In one embodiment, the heat treatment temperature is 450°C to 650°C.

[0024] In one embodiment, the heat preservation operation time is 0.5 hours to 4 hours.

[0025] A preparation method is also provided, comprising the following steps: S1, using SrTiO3 powder, adding a binder and a solvent, and preparing a semiconducting SrTiO3 ceramic substrate by ball milling, tape casting, lamination, cutting, debinding, and reduction sintering;

[0026] S2, ultrasonically cleaning the semiconducting SrTiO3 ceramic substrate in S1 with pure water and ethanol in turn;

[0027] S3, drying the SrTiO3 ceramic substrate cleaned in S2 for later use;

[0028] S4: sputter coating onto SrTiO3 ceramic substrate;

[0029] S4.1. Place the SrTiO3 ceramic substrate obtained in S3 on a magnetron vacuum sputtering machine carrier and into a receiving chamber of the magnetron vacuum sputtering machine, and evacuate the receiving chamber to a pressure of less than 6.0E-4Pa;

[0030] S4.2, filling the containing chamber of S4.1 with argon gas, so that the gas pressure of the containing chamber reaches 1.0E-2Pa;

[0031] S4.3, using pure aluminum, using a magnetron vacuum sputtering machine to perform target sputtering, the sputtering time is controlled within 1min to 30min, so that a layer of aluminum film is deposited on the surface of the SrTiO3 ceramic substrate, and the thickness of the aluminum film is controlled within 0.1 to 3.0um;

[0032] S4, taking out the SrTiO3 ceramic substrate sputtered in S3 from the magnetron vacuum sputtering machine carrier;

[0033] S5, placing the sputtered SrTiO3 ceramic substrate into a muffle furnace, heating it to the heat treatment temperature within 30 minutes under air environment, and then keeping it at this temperature for 0.5 to 4 hours;

[0034] Wherein, the heat treatment temperature of the SrTiO3 ceramic substrate in the muffle furnace is 450°C to 650°C;

[0035] S6, naturally cooling the SrTiO3 ceramic substrate after the heat treatment in S5 to room temperature;

[0036] Through the heat treatment step S5, an Al2O3 layer is formed on the surface of the aluminum film of the SrTiO3 ceramic substrate, and a doped interface layer is formed at the interface between the aluminum film and the SrTiO3 ceramic substrate.

[0037] The beneficial effects of the present invention are as follows:

[0038] 1. By sputtering an aluminum film on the surface of a semiconducting SrTiO3 ceramic substrate, a ceramic / aluminum film acceptor doping interface is formed through heat treatment, an Al2O3 layer is formed on the surface of the aluminum film, and a doped interface layer is formed on the interface between the aluminum film surface and the SrTiO3 ceramic substrate. The doped interface layer and the Al2O3 layer form an insulating film.

[0039] The thickness of the insulating film is mainly affected by the heat treatment temperature and time. The higher the heat treatment temperature and the longer the time, the thicker the Al2O3 layer will be. The higher the insulation withstand voltage performance of the high dielectric constant ceramic substrate will be, and its dielectric loss will be reduced.

[0040] The high dielectric constant ceramic substrate of the present invention can be used to produce single-layer ceramic capacitors with larger capacity of the same size or smaller size of the same capacity, thereby achieving a higher capacitance-to-volume ratio of the single-layer ceramic capacitor and miniaturization in volume. At the same time, the single-layer ceramic capacitor can maintain a higher insulation withstand voltage performance, thereby solving the technical problems of the existing single-layer ceramic capacitors with a low capacitance-to-volume ratio and high dielectric loss.

[0041] 2. Existing technology: (1) A mixture of various oxides, mainly copper oxide, is used to coat a semiconducting SrTiO3 ceramic substrate, which is then sintered at about 1000°C to form a grain boundary layer structure ceramic substrate. The dielectric constant produced by this process is generally 12000-45000. The dielectric constant is sensitive to the oxidation sintering process parameters and the atmosphere of the support plate, and the quality stability of the production batch is poor.

[0042] (2) Silver paste is applied on the semiconducting BaTiO3 ceramic substrate and sintered. Ag is doped on the surface of the semiconducting ceramic substrate to form an interface insulating layer. This ceramic has low insulation resistance and poor withstand voltage, and is only suitable for use in very low operating voltage environments, such as 3.3V.

[0043] Compared with the prior art, the high dielectric constant ceramic substrate of the present invention has simple manufacturing process, low heat treatment temperature, good quality of the formed insulating film, and high batch quality stability of the high dielectric constant ceramic substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use in the implementation mode will be briefly introduced below. Obviously, the drawings described below are only some implementation modes of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0045] Figure 1 It is a schematic structural diagram of the high dielectric constant performance ceramic substrate of the present invention.

[0046] The reference numerals are as follows:

[0047] 00. High dielectric constant performance ceramic substrate;

[0048] 1. SrTiO3 ceramic substrate;

[0049] 2. Insulating film; 21. Al2O3 layer; 22. Doped interface layer. DETAILED DESCRIPTION

[0050] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0051] A specific embodiment provides a high dielectric constant ceramic substrate and a preparation method thereof, wherein a high dielectric constant ceramic substrate is formed by a semiconducting SrTiO3 ceramic substrate and an insulating film; the insulating film is arranged on two opposite planes of the SrTiO3 ceramic substrate; wherein pure aluminum is sputtered onto two surfaces of the SrTiO3 ceramic substrate by magnetron vacuum sputtering to form an aluminum film, which is then subjected to heat treatment; an Al2O3 layer is formed on the surface of the aluminum film, and a doped interface layer is formed at the interface between the aluminum film and the SrTiO3 ceramic substrate; the Al2O3 layer and the doped interface layer constitute an insulating film; the thickness of the Al2O3 layer of the insulating film increases with the heat treatment time, so that the insulating withstand voltage performance of the high dielectric constant performance ceramic substrate is higher and the dielectric loss is lower; a higher capacitance to volume ratio is achieved on a single-layer ceramic capacitor; the technical problems of low capacitance to volume ratio and high dielectric loss in existing single-layer ceramic capacitors are effectively solved.

[0052] In addition, all the contents of the configurations shown in the following embodiments are not necessarily limited to the solutions of the invention described in the claims.

[0053] An example of a high dielectric constant ceramic substrate is Figure 1 As shown, it includes a semiconducting SrTiO3 ceramic substrate 1 and an insulating film 2, wherein the insulating film 2 is arranged on two opposite planes of the SrTiO3 ceramic substrate 1; wherein pure aluminum is sputtered onto the two surfaces of the SrTiO3 ceramic substrate 1 to form aluminum films on the two surfaces of the SrTiO3 ceramic substrate 1; the SrTiO3 ceramic substrate 1 sputtered with the aluminum film is sent into a muffle furnace, heated to a heat treatment temperature within 30 minutes, and then subjected to a heat preservation operation to achieve heat treatment; after the heat treatment, the SrTiO3 ceramic substrate 1 is naturally cooled to room temperature; thereby, an Al2O3 layer 21 is formed on the surface of the aluminum film, and a doped interface layer 22 is formed at the interface between the aluminum film and the SrTiO3 ceramic substrate; the Al2O3 layer 21 and the doped interface layer 22 constitute the insulating film 2; the SrTiO3 ceramic substrate 1 and the two layers of the insulating films 2 arranged opposite to each other constitute a ceramic substrate with high dielectric constant performance, i.e., a high dielectric constant performance ceramic substrate 00.

[0054] Regarding the aluminum content of the above-mentioned pure metallic aluminum, the pure metallic aluminum is 90.0% to 99.9% aluminum.

[0055] The parameter requirements for the SrTiO3 ceramic substrate 1 are as follows: the SrTiO3 ceramic substrate 1 has a thickness of 0.1-0.3 mm, a square shape, and a length and width of 38 mm by 38 mm.

[0056] The parameter requirements for the aluminum film are: the sputtering time of the SrTiO3 ceramic substrate 1 is between 1 minute and 30 minutes; the thickness of the aluminum film increases with the sputtering time, and the thickness of the aluminum film is between 0.1 and 3.0 um.

[0057] Regarding the above-mentioned heat treatment temperature and heat preservation operation time, the heat treatment temperature is 450° C. to 650° C., and the heat preservation operation time is 0.5 hour to 4 hours.

[0058] The Al2O3 layer 21 formed during the heat treatment, the thickness of the insulating film 2 on the SrTiO3 ceramic substrate 1 is 0.1~3.0um; the thickness of the Al2O3 layer 21 of the insulating film 2 increases with the heat treatment time, so that the higher the insulation withstand voltage performance of the high dielectric constant performance ceramic substrate 00, the greater the dielectric loss.

[0059] Based on the structure of the above embodiment of the high dielectric constant ceramic substrate, a preparation method is provided, comprising the following steps: S1, using SrTiO3 powder, adding a binder and a solvent, and preparing a semiconducting SrTiO3 ceramic substrate by ball milling, tape casting, lamination, cutting, debinding, and reduction sintering;

[0060] S2, ultrasonically cleaning the semiconducting SrTiO3 ceramic substrate in S1 with pure water and ethanol in turn;

[0061] S3, drying the SrTiO3 ceramic substrate cleaned in S2 for later use;

[0062] S4: sputter coating onto SrTiO3 ceramic substrate;

[0063] S4.1. Place the SrTiO3 ceramic substrate obtained in S3 on a magnetron vacuum sputtering machine carrier and into a receiving chamber of the magnetron vacuum sputtering machine, and evacuate the receiving chamber to a pressure of less than 6.0E-4Pa;

[0064] S4.2, filling the containing chamber of S4.1 with argon gas, so that the gas pressure of the containing chamber reaches 1.0E-2Pa;

[0065] S4.3, using pure aluminum, using a magnetron vacuum sputtering machine to perform target sputtering, the sputtering time is controlled within 1min to 30min, so that a layer of aluminum film is deposited on the surface of the SrTiO3 ceramic substrate, and the thickness of the aluminum film is controlled within 0.1 to 3.0um;

[0066] S4, taking out the SrTiO3 ceramic substrate coated in S3 from the magnetron vacuum sputtering machine carrier;

[0067] S5, placing the coated SrTiO3 ceramic substrate into a muffle furnace, heating it to the heat treatment temperature within 30 minutes under air environment, and then keeping it warm for 0.5 hour to 4 hours;

[0068] Wherein, the heat treatment temperature of the SrTiO3 ceramic substrate in the muffle furnace is 450°C to 650°C;

[0069] S6, naturally cooling the SrTiO3 ceramic substrate after the heat treatment in S5 to room temperature;

[0070] Through the heat treatment step S5, an Al2O3 insulating layer is formed on the surface of the aluminum film of the SrTiO3 ceramic substrate, and a doped interface layer is formed at the interface between the aluminum film and the SrTiO3 ceramic substrate.

[0071] Experiment 1 was performed based on the high dielectric constant ceramic substrate of the above embodiment and the method for preparing the high dielectric constant ceramic substrate of the embodiment:

[0072] (1) The semiconducting SrTiO3 ceramic substrate was trimmed into a square substrate with a length x width of 38 mm x 38 mm and a thickness of T1 = 0.3 mm, and ultrasonically cleaned with pure water and ethanol in turn to remove oil and particles on the surface. After cleaning, it was dried in an oven for later use.

[0073] (2) The SrTiO3 ceramic substrate processed in (1) is placed on a magnetron vacuum sputtering machine carrier and sent into a containing chamber of the magnetron vacuum sputtering machine. The chamber is evacuated until the pressure is less than 6.0E-4Pa, and argon gas is filled until the pressure in the containing chamber reaches 1.0E-2Pa. Pure aluminum is sputtered through a target for 1 minute to deposit an aluminum film with a thickness of about 0.1 um on the surface of the SrTiO3 ceramic substrate.

[0074] (3) Take out the SrTiO3 ceramic substrate that has been sputtered in (2), put the SrTiO3 ceramic substrate into a muffle furnace, raise the temperature in the furnace to 450°C within 30 minutes under air environment, and then keep it warm for 0.5 hours. After the heat treatment, naturally cool the SrTiO3 ceramic substrate to room temperature, thereby manufacturing a high dielectric constant ceramic substrate.

[0075] (4) A Ti / Au conductive layer was fabricated on the high dielectric constant ceramic substrate processed in (3) by using a magnetron vacuum sputtering process, and then cut into a first test piece having a length x width of 0.8 mm x 0.8 mm.

[0076] (5) Conduct an electrical performance test on the first test piece.

[0077] The electrical performance test results of the first test piece are shown in the following table:

[0078] Performance Project Capacitance Cp Loss DF Insulation IR Withstand voltage BDV Test conditions 1.0V, 1KHz 1.0V, 1KHz 25V, 60s 10V / s, boost Test value 3835pF 120×10-4 1.8GΩ 96V

[0079] The calculated dielectric constant is K1=Cp*T1*113.3 / S1=3835*0.30*113.3 / (38*38)=203674.

[0080] Wherein, T1 is the thickness of the SrTiO3 ceramic substrate in the first experiment, S1 is the area of ​​the first test piece, and Cp is the electrostatic capacitance.

[0081] Experiment 2 was conducted based on the high dielectric constant ceramic substrate of the above embodiment and the method for preparing the high dielectric constant ceramic substrate of the embodiment:

[0082] (1) The semiconducting SrTiO3 ceramic substrate was trimmed into a square substrate with a length x width of 38 mm x 38 mm and a thickness of T2 = 0.20 mm, and ultrasonically cleaned with pure water and ethanol in turn to remove oil and particles on the surface. After cleaning, it was dried in an oven for later use.

[0083] (2) The SrTiO3 ceramic substrate processed in (1) is placed on a magnetron vacuum sputtering machine carrier and sent into a containing chamber of the magnetron vacuum sputtering machine. The chamber is evacuated until the pressure is less than 6.0E-4Pa, and argon gas is filled until the pressure in the containing chamber reaches 1.0E-2Pa. Pure aluminum is sputtered through a target for 15 minutes to deposit an aluminum film with a thickness of about 1.5 um on the surface of the SrTiO3 ceramic substrate.

[0084] (3) Take out the SrTiO3 ceramic substrate that has been sputtered in (2), put the SrTiO3 ceramic substrate into a muffle furnace, raise the temperature in the furnace to 500°C within 30 minutes under air environment, and then keep it warm for 2 hours. After the heat treatment, naturally cool the SrTiO3 ceramic substrate to room temperature, thereby making a high dielectric constant ceramic substrate.

[0085] (4) A Ti / Au conductive layer was fabricated on the high dielectric constant ceramic substrate processed in (3) by using a magnetron vacuum sputtering process, and then cut into a second test piece having a length x width of 0.8 mm x 0.8 mm.

[0086] (5) Conduct electrical performance test on the second test piece.

[0087] The electrical performance test results of the second test piece are shown in the following table:

[0088] Performance Project Capacitance Cp Loss DF Insulation IR Withstand voltage BDV Test conditions 1.0V, 1KHz 1.0V, 1KHz 25V, 60s 10V / s boost Test value 4750pF 85×10-4 6.9GΩ 158V

[0089] The calculated dielectric constant is K2=Cp*T2*113.3 / S2=4750*0.2*113.3 / (38*38)=168179.

[0090] Wherein, T2 is the thickness of the SrTiO3 ceramic substrate in Experiment 2, S2 is the area of ​​the second test piece, and Cp is the electrostatic capacitance.

[0091] Experiment 3 was performed based on the high dielectric constant ceramic substrate of the above embodiment and the method for preparing the high dielectric constant ceramic substrate of the embodiment:

[0092] (1) The semiconducting SrTiO3 ceramic substrate was trimmed into a square substrate with a length x width of 38 mm x 38 mm and a thickness of T3 = 0.12 mm, and ultrasonically cleaned with pure water and ethanol in turn to remove oil and particles on the surface. After cleaning, it was dried in an oven for later use.

[0093] (2) The SrTiO3 ceramic substrate processed in (1) is placed on a magnetron vacuum sputtering machine carrier and sent into a containing chamber of the magnetron vacuum sputtering machine. The chamber is evacuated until the pressure is less than 6.0E-4Pa, and argon gas is filled until the pressure in the containing chamber reaches 1.0E-2Pa. Pure aluminum is sputtered through a target for 30 minutes to deposit an aluminum film with a thickness of about 3 um on the surface of the SrTiO3 ceramic substrate.

[0094] (3) Take out the SrTiO3 ceramic substrate that has been sputtered in (2), put the SrTiO3 ceramic substrate into a muffle furnace, raise the temperature in the furnace to 650°C within 30 minutes under air environment, and then keep the temperature for 4 hours. After the heat treatment, naturally cool the SrTiO3 ceramic substrate to room temperature, thereby manufacturing a high dielectric constant ceramic substrate.

[0095] (4) A Ti / Au conductive layer was fabricated on the high dielectric constant ceramic substrate processed in (3) by using a magnetron vacuum sputtering process, and then cut into a third test piece having a length x width of 0.8 mm x 0.8 mm.

[0096] (5) Conduct electrical performance test on the third test piece.

[0097] The electrical performance test results of the third test piece are shown in the following table:

[0098] Performance Project Capacitance Cp Loss DF Insulation IR Withstand voltage BDV Test conditions 1.0V, 1KHz 1.0V, 1KHz 25V, 60s 10V / s, boost Test value 4924pF 78×10-4 8.9GΩ 267V

[0099] The calculated dielectric constant is K3=Cp*T3*113.3 / S3=4924*0.12*113.3 / (38*38)=113321.

[0100] Wherein, T3 is the thickness of the SrTiO3 ceramic substrate in Experiment 3, S3 is the area of ​​the third test piece, and Cp is the electrostatic capacitance.

[0101] In the prior art, high dielectric constant ceramic substrates are generally made of a mixture of various oxides, mainly copper oxide, coated on a semiconducting SrTiO3 ceramic substrate, which is sintered at about 1000°C to form a grain boundary layer structure ceramic substrate. The dielectric constant produced by this process is generally 12000-45000. Its dielectric constant is sensitive to the oxidation sintering process parameters and the atmosphere of the setter, and the production batch stability is poor.

[0102] There is also a method of coating silver paste on a semiconducting BaTiO3 ceramic substrate and sintering it. Ag is doped on the surface of the semiconducting ceramic substrate to form an interface insulating layer. This ceramic sheet has low insulation resistance and poor withstand voltage, and is only suitable for use in very low operating voltage situations, such as 3.3V.

[0103] From the above three experiments, it can be seen that by sputtering the aluminum film on the surface of the semiconducting SrTiO3 ceramic substrate, a ceramic / aluminum film acceptor doping interface will be formed through heat treatment, an Al2O3 layer will be formed on the surface of the aluminum film, and a doped interface layer will be formed on the interface between the aluminum film surface and the SrTiO3 ceramic substrate, and the doped interface layer and the Al2O3 layer will form an insulating film.

[0104] The thickness of the insulating film is mainly affected by the heat treatment temperature and time. The higher the heat treatment temperature and the longer the time, the thicker the Al2O3 layer will be, the higher the insulation withstand voltage performance of the ceramic substrate will be, and its dielectric loss will be reduced.

[0105] The high dielectric constant ceramic substrate of the present invention can realize the manufacture of single-layer ceramic capacitors with larger capacity or smaller size with the same capacity of the same size, so that the single-layer ceramic capacitors maintain higher insulation withstand voltage performance.

[0106] Moreover, compared with the prior art, the high dielectric constant ceramic substrate of the present invention has a simple manufacturing process, a low heat treatment temperature, and a formed insulating film of good quality, so that the product batch quality stability of the high dielectric constant ceramic substrate is high.

[0107] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described.

Claims

1. A high dielectric constant ceramic substrate, characterized in that: It includes a semiconducting SrTiO3 ceramic substrate and an insulating film, wherein the insulating film is arranged on two opposite planes of the SrTiO3 ceramic substrate; wherein pure aluminum is sputtered onto the two surfaces of the SrTiO3 ceramic substrate by magnetron vacuum sputtering to form aluminum films on the two surfaces of the SrTiO3 ceramic substrate; The thickness of the aluminum film increases with the sputtering time, and the thickness of the aluminum film is 0.1 to 3.0 um; The SrTiO3 ceramic substrate sputtered with the aluminum film is placed in a muffle furnace, heated to a heat treatment temperature within 30 minutes, and then kept warm to achieve heat treatment; after the heat treatment, the SrTiO3 ceramic substrate is naturally cooled to room temperature; thereby forming an Al2O3 layer on the surface of the aluminum film and forming a doped interface layer at the interface between the aluminum film and the SrTiO3 ceramic substrate; The Al2O3 layer and the doped interface layer constitute the insulating film; the SrTiO3 ceramic substrate and the two layers of the insulating films arranged opposite to each other constitute a ceramic substrate with high dielectric constant performance; The thickness of the insulating film on the SrTiO3 ceramic substrate is 0.1-3.0 um; the thickness of the Al2O3 layer of the insulating film increases with the heat treatment time, so that the insulating withstand voltage performance of the high dielectric constant ceramic substrate is higher and the dielectric loss is lower.

2. The high dielectric constant ceramic substrate according to claim 1, characterized in that: The thickness of the SrTiO3 ceramic substrate is 0.1-0.3 mm.

3. The high dielectric constant ceramic substrate according to claim 1, characterized in that: The pure aluminum is 90.0% to 99.9% aluminum.

4. The high dielectric constant ceramic substrate according to claim 1, characterized in that: The sputtering time of the SrTiO3 ceramic substrate is controlled within 1 min to 30 min.

5. The high dielectric constant ceramic substrate according to claim 1, characterized in that: The heat treatment temperature is 450°C to 650°C.

6. The high dielectric constant ceramic substrate according to claim 5, characterized in that: The heat preservation operation time is 0.5 hours to 4 hours.

7. A method for preparing a high dielectric constant ceramic substrate according to claim 1, characterized in that: The following steps are involved: S1. SrTiO3 powder is added with a binder and a solvent to prepare a semiconducting SrTiO3 ceramic substrate by ball milling, tape casting, lamination, cutting, debinding and reduction sintering. S2, ultrasonically cleaning the semiconducting SrTiO3 ceramic substrate in S1 with pure water and ethanol in turn; S3, drying the SrTiO3 ceramic substrate cleaned in S2 for later use; S4: sputter coating onto SrTiO3 ceramic substrate; S4.

1. Place the SrTiO3 ceramic substrate obtained in S3 on a magnetron vacuum sputtering machine carrier and into a receiving chamber of the magnetron vacuum sputtering machine, and evacuate the receiving chamber to a pressure of less than 6.0E-4Pa; S4.2, filling the containing chamber of S4.1 with argon gas, so that the gas pressure of the containing chamber reaches 1.0E-2Pa; S4.

3. Use pure aluminum and use a magnetron vacuum sputtering machine to perform target sputtering. The sputtering time is controlled within 1min to 30min to deposit a layer of aluminum film on the surface of the SrTiO3 ceramic substrate. The thickness of the aluminum film is controlled within 0.1 to 3.0um. S4, taking out the SrTiO3 ceramic substrate sputtered in S3 from the magnetron vacuum sputtering machine carrier; S5, placing the sputtered SrTiO3 ceramic substrate into a muffle furnace, heating it to the heat treatment temperature within 30 minutes under air environment, and then keeping it at this temperature for 0.5 to 4 hours; Wherein, the heat treatment temperature of the SrTiO3 ceramic substrate in the muffle furnace is 450°C to 650°C; S6, naturally cooling the SrTiO3 ceramic substrate after the heat treatment in S5 to room temperature; Through the heat treatment step S5, an Al2O3 layer is formed on the surface of the aluminum film of the SrTiO3 ceramic substrate, and a doped interface layer is formed at the interface between the aluminum film and the SrTiO3 ceramic substrate.

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