TWI626669B - Thin film capacitor and manufacturing method thereof - Google Patents

Abstract

The present disclosure provides a thin film capacitor and a manufacturing method thereof. The thin film capacitor includes a dielectric layer and a pair of graphene layers, which are respectively disposed on opposite sides of the dielectric layer to serve as electrodes of the thin film capacitor. The electrode may further include a pair of metal layers outside the graphene layer. The present disclosure can solve the problem that the conventional thin film capacitor has a poor capacitor effect due to the diffusion of metal ions into the dielectric layer due to high temperature during the manufacturing process.

Description

Film capacitor and manufacturing method thereof

The present disclosure relates to a thin film capacitor and a manufacturing method thereof, and more particularly, to a thin film capacitor having a graphene structure and a manufacturing method thereof.

At present, thin film capacitors have been widely used in various electronic products, such as for storing energy, coupling or decoupling signals, and electronic filtering. Generally, a thin film capacitor is formed by providing a dielectric layer between two conductive plates, wherein the dielectric layer can form electrical insulation between the two conductive plates. When a voltage is applied, charges accumulate on the conductive plate and generate an electric field. When the applied voltage is removed, the charge remains on the two conductive plates to achieve the effect of storing energy.

Please refer to FIG. 1, which shows a structure diagram of a conventional thin film capacitor 10. The thin film capacitor 10 includes a first metal layer 11, a second metal layer 12, and a dielectric layer 13, wherein the dielectric layer 13 is disposed between the first metal layer 11 and the second metal layer 12. Since the first metal layer 11 and the second metal layer 12 disposed at both ends of the dielectric layer 13 are made of a metal material, the first metal layer 11 and the first metal layer 11 and The metal ions in the two metal layers 12 diffuse into the dielectric layer 13, and further, diffusion regions 14 are formed in portions of the metal layer dielectric layer 13 close to the first metal layer 11 and the second metal layer 1, respectively. However, the formation of the diffusion region 14 may cause the dielectric constant of the dielectric layer 13 to decrease, leading to a problem of poor capacitor performance (such as a decrease in capacitance value).

In view of this, it is necessary to provide a thin film capacitor and a manufacturing method thereof to solve the problems existing in the conventional technology.

In order to solve the above technical problems, an object of the present disclosure is to provide a thin film capacitor and a manufacturing method thereof, which can improve the problem of poor capacitor performance due to metal ion diffusion into the dielectric layer during the manufacturing process.

In order to achieve the above object, the present disclosure provides a thin film capacitor, including: a dielectric layer; and a pair of graphene layers respectively disposed on opposite sides of the dielectric layer as electrodes of the thin film capacitor.

In one preferred embodiment of the present disclosure, the thickness of each graphene layer is between 0.3 nm and 10 microns.

In one of the preferred embodiments of the present disclosure, the electrode of the thin film capacitor further includes a pair of metal layers disposed on two opposite outer sides of the pair of graphene layers, so that one of the graphene layers is disposed on the dielectric. Layer and one of the metal layers.

In one preferred embodiment of the present disclosure, the thickness of each metal layer is between 1 micrometer and 30 micrometers.

In one preferred embodiment of the present disclosure, the thickness of the dielectric layer is between 200 nm and 800 nm.

In one preferred embodiment of the present disclosure, the material of the dielectric layer is selected from BaTiO ₃ , Ta ₂ O ₅ , TiO ₂ , HfO ₂ , ZrO ₂ , Al ₂ O ₃ , La ₂ O ₃ , and Pr _2. O ₃ and any one of the above.

The present disclosure also provides a method for manufacturing a thin film capacitor, including forming a first stone. An inkene layer; forming a dielectric layer on the first graphene layer; and forming a second graphene layer on the dielectric layer so that the dielectric layer is positioned between the first graphene layer and the second graphene layer Between graphene layers.

In one preferred embodiment of the present disclosure, the step of forming the first graphene layer further includes: forming a first metal layer; and forming the first graphene layer on the first metal layer.

In one of the preferred embodiments of the present disclosure, the step of forming the first metal layer further includes: providing an insulating substrate; forming a metal layer on the insulating substrate; and performing a photolithography process on the metal layer to The first metal layer is formed.

In one preferred embodiment of the present disclosure, after forming the second graphene layer, the method further includes: forming a second metal layer on the second graphene layer.

Compared with the conventional technology, the present disclosure uses a graphene layer as an electrode layer of a thin film capacitor, or arranges the graphene layer between a dielectric layer and a metal layer so that the graphene layer and the metal layer work together. The electrode layer of the thin film capacitor can further solve the problem that the metal ion diffuses into the dielectric layer due to high temperature during the manufacturing process, resulting in a poor capacitor effect.

1‧‧‧ insulating substrate

10, 20, 30‧‧‧ film capacitors

11‧‧‧ first metal layer

12‧‧‧Second metal layer

13‧‧‧ Dielectric layer

14‧‧‧ proliferation zone

21, 31‧‧‧ Dielectric layer

22, 32‧‧‧ the first graphene layer

23, 33‧‧‧ second graphene layer

34’‧‧‧metal layer

34‧‧‧ first metal layer

35‧‧‧Second metal layer

D1, D2, D3, D4, D5, D6, D7, D8‧‧‧thickness

Fig. 1 shows a schematic structural diagram of a conventional thin film capacitor; Fig. 2 shows a schematic structural explosion diagram of a thin film capacitor according to a first preferred embodiment of the present disclosure; Figs. 3A to 3C are a series of cross-sectional views, FIG. 2 shows a manufacturing process of a thin film capacitor. FIG. 4 shows an exploded view of a structure of a thin film capacitor according to a second preferred embodiment of the present disclosure. Intent; and FIGS. 5A to 5F are a series of cross-sectional views showing the manufacturing process of the thin film capacitor of FIG. 4.

In order to make the above and other objects, features, and advantages of the present disclosure more comprehensible, the following describes the preferred embodiments of the present disclosure and the accompanying drawings in detail, as follows.

Please refer to FIG. 2, which illustrates a schematic diagram of an exploded structure of a thin film capacitor 20 according to a first preferred embodiment of the present disclosure. The thin film capacitor 20 includes a dielectric layer 21, a first graphene layer 22, and a second graphene layer 23. The first graphene layer 22 and the second graphene layer 23 are respectively disposed on opposite sides of the dielectric layer 21. In the first preferred embodiment of the present disclosure, the first graphene layer 22 and the second graphene layer 23 are used as electrodes of the thin film capacitor 20. Utilizing the good characteristics of graphene itself, it can effectively enhance the service life and electrical characteristics of the thin film capacitor 20, improve the capacitor storage capacity, and reduce the overall impedance generated when applied to high-speed signal measurement. In addition, the effects of improving the heat dissipation capability of the thin film capacitor 20 and miniaturizing the overall configuration of the thin film capacitor 20 can be effectively achieved. That is, in the present disclosure, using the first graphene layer 22 and the second graphene layer 23 as the electrodes of the thin film capacitor 20 is a main factor that increases the performance of the thin film capacitor 20 and is beneficial to the application of the thin film capacitor 20 to the product. Body circuit wiring or embedded capacitors.

In detail, graphene is a planar two-dimensional structure with a hexagonal ring honeycomb structure composed of single-layer carbon atoms bonded to each other with sp ² orbital domains, and possesses various superior physical properties. For example, the thermal conductivity of graphene is as high as 5300W / m‧K. With this feature, the heat dissipation capacity of the thin film capacitor 20 can be greatly improved. Therefore, when the film capacitor 20 is applied as an energy storage element, the service life of the element in a high-temperature working environment can be improved. In addition, graphene is a hard nano material, has a very high Young's coefficient (about 1100 GPa), and its mechanical strength is much higher than metal materials such as steel. With this feature, the first graphene layer 22 and the second When the graphene layer 23 is used as an electrode of the thin film capacitor 20, it can also have a protective effect.

Furthermore, the thickness of single-layer graphene is only about 0.3 nm, and the resistivity of graphene at room temperature is only about 10 ^-6 Ω · cm, which is lower than that of copper or silver. In addition, graphene has a high specific surface area (about 2,630 m ² g ^-1 ) and has a rich mesoporous structure. The mesoporous structure facilitates the rapid migration of charge to the surface of graphene. That is, graphene is a thin and highly conductive material. Therefore, by using the first graphene layer 22 and the second graphene layer 23 with a high specific surface area as the electrode layers of the thin film capacitor 20, not only the charge storage of the dielectric layer 21 can be accelerated so that the thin film capacitor 20 has higher energy The density and charge / discharge rate can also make the overall configuration thinner and thinner, so as to achieve the purpose of miniaturizing the component. In addition, as shown in FIG. 2, the signal is transmitted through electrodes made of the first graphene layer 22 and the second graphene layer 23. Because graphene has a thin thickness, high specific surface area, and excellent electrical performance, it has a relatively short electron transmission path and a low capacitance impedance effect, which is beneficial for high-frequency signal transmission.

In addition, the conventional thin film capacitors adopt a structure in which a metal electrode directly contacts a dielectric material. Therefore, during the manufacturing process, metal ions will diffuse into the dielectric material due to high temperature, which will cause the dielectric constant of the dielectric material. Degradation, resulting in poor capacitor performance. In contrast, in the present disclosure, since graphene itself has stable physical and chemical properties, it does not cause ion diffusion problems after contacting with other materials, so it has the effect of optimizing the electrical properties of the interface. Therefore, the structure in which the dielectric layer 21 is in direct contact with the first graphene layer 22 and the second graphene layer 23 with good stability can effectively solve the problem of ion diffusion into the dielectric layer 21 to achieve optimization Thin film capacitor 20 performance.

Please refer to FIGS. 3A to 3C, which are a series of cross-sectional views showing the manufacturing process of the thin film capacitor 20 of FIG. First, as shown in FIG. 3A, an insulating substrate 1 is provided, and a first graphene layer 22 is formed on the insulating substrate 1. The thickness D1 of the first graphene layer 22 is between 0.3 nm and 10 μm. Next, as shown in FIG. 3B, a dielectric layer 21 is formed on the first graphene layer 22, wherein the thickness D2 of the dielectric layer 21 is between 200 nm and 800 nm. The dielectric layer 21 is made of a high-k material. Preferably, the material of the dielectric layer 21 is selected from BaTiO ₃ , Ta ₂ O ₅ , TiO ₂ , HfO ₂ , ZrO ₂ , Al ₂ O ₃ , La ₂ O ₃ , Pr ₂ O ₃ and any combination thereof. one. Next, as shown in FIG. 3C, a second graphene layer 23 is formed on the dielectric layer 21, wherein the thickness D3 of the second graphene layer 23 is between 0.3 nm and 10 μm. As shown in FIG. 3B, the dielectric layer 21 is located between the first graphene layer 22 and the second graphene layer 23. Finally, the insulating substrate 1 is removed, and the manufacturing of the thin film capacitor 20 is completed.

Please refer to FIG. 4, which shows a structural explosion diagram of a film capacitor 30 according to a second preferred embodiment of the present disclosure. The thin film capacitor 30 includes a dielectric layer 31, a first graphene layer 32, a second graphene layer 33, a first metal layer 34, and a second metal layer 35, wherein the first graphene layer 32 and the second graphene layer 33 are respectively The first and second metal layers 34 and 35 are disposed on opposite sides of the dielectric layer 31, and the first and second metal layers 34 and 33 are disposed on opposite sides of the first and second graphene layers 32 and 33, respectively. That is, the first graphene layer 32 is disposed between the dielectric layer 31 and the first metal layer 34, and the second graphene layer 33 is disposed between the dielectric layer 31 and the second metal layer 35. Compared with the first preferred embodiment, in the second preferred embodiment, the first graphene layer 32 and the second graphene layer 33 together with the first metal layer 34 and the second metal layer 35 serve as the thin film capacitor. 30 electrodes, and the first graphene layer 32 and the second graphene layer 33 can be further used as a barrier layer between the dielectric layer 31 and the metal layers 34 and 35, which can effectively increase the performance of the thin film capacitor 30, Such as increasing the charge and discharge rate, Load storage capacity and reducing the impact of capacitive impedance at the frequency of use.

In the second preferred embodiment, applying the graphene to the thin film capacitor 30 can also exert the advantages listed above, which are described in detail below. As shown in FIG. 4, the current is transmitted through the first metal layer 34 and the second metal layer 35, and then is conducted to the dielectric layer 31 through the first graphene layer 32 and the second graphene layer 33. Due to the high specific surface area of graphene and its rich mesoporous structure, the mesoporous structure helps to quickly transfer charge from the first metal layer 34 and the second metal layer 35 to the first graphene layer 32 and the second graphene layer. 33 surface, thereby increasing the rate of charge storage of the dielectric layer 31. Therefore, compared with a commercially available capacitor using an activated carbon material as an electrode, in the present disclosure, a structure in which the metal layers 34 and 35 are combined with the graphene layers 32 and 33 and used as an electrode of the thin film capacitor 30 can obtain a higher Energy density and faster charge and discharge rates.

In addition, as shown in FIG. 4, the signal of the thin film capacitor 30 is transmitted through electrodes formed by combining the metal layers 34 and 35 and the graphene layers 32 and 33. Because graphene has a thin thickness, a high specific surface area, and excellent electrical performance, it has a relatively short electronic transmission path and a low capacitance impedance effect, which is beneficial to the application of the thin film capacitor 30 in high frequency signal transmission.

In addition, since the thickness of the single-layer graphene is only about 0.3 nm, even if the first and second metal layers 34 and 35 and the dielectric layer 31 are added, the first and second graphene layers 32 and 33 are added. , Does not have an adverse effect on the overall component thickness. And because the graphene surface has Van der Waals force, it can provide a good bonding force between the first metal layer 34 and the second metal layer 35 and the dielectric layer 31, which is beneficial to reducing the size of the device.

In addition, the biggest problem with conventional thin film capacitors is the interface effect between the metal electrode and the dielectric material. The bonding between the two will cause metal ions to diffuse into the dielectric material, leading to problems such as a decrease in dielectric constant and capacitance performance. In contrast, in the second preferred embodiment of the present disclosure, Since the first graphene layer 32 and the second graphene layer 33 having stable physical and chemical characteristics are used as the barrier layer between the dielectric layer 31 and the metal layers 34 and 35. It can effectively avoid the problem of ion diffusion, so as to optimize the electrical properties of the junction and thus achieve the good electrical performance of the thin film capacitor 30.

In addition, the thermal conductivity of graphene is as high as 5300 W / m‧K, which can realize efficient heat dissipation between the dielectric layer 31 and the environment. Therefore, when the film capacitor 20 is applied as an energy storage element, the service life of the element in a high-temperature working environment can be improved.

Please refer to FIGS. 5A to 5F, which are a series of cross-sectional views showing the manufacturing process of the thin film capacitor of FIG. First, as shown in FIG. 5A, an insulating substrate 1 is provided, and a metal layer 34 ′ is formed on the insulating substrate 1. Next, as shown in FIG. 5B, a photolithography process is performed on the metal layer 34 ′ to form a first metal layer 34 having a specific size, wherein the thickness D4 of the first metal layer 34 is between 1 μm and 30 μm. . Preferably, the material of the first metal layer 34 is selected from copper or nickel. Next, as shown in FIG. 5C, a first graphene layer 32 is formed on the first metal layer 34, wherein the thickness D5 of the first graphene layer 32 is between 0.3 nm and 10 μm. Next, as shown in FIG. 5D, a dielectric layer 31 is formed on the first graphene layer 32, wherein the thickness D6 of the dielectric layer 31 is between 200 nm and 800 nm. The dielectric layer 21 is made of a high-k material. Preferably, the material of the dielectric layer 21 is selected from BaTiO ₃ , Ta ₂ O ₅ , TiO ₂ , HfO ₂ , ZrO ₂ , Al ₂ O ₃ , La ₂ O ₃ , Pr ₂ O ₃ and any combination thereof. one. It should be noted that, in this step, since the first graphene layer 32 functions as a barrier layer, the metal ions of the first metal layer 34 will not diffuse to the dielectric layer 21 in a high-temperature manufacturing environment. Next, as shown in FIG. 5E, a second graphene layer 33 is formed on the dielectric layer 31, wherein the thickness D7 of the second graphene layer 33 is between 0.3 nm and 10 μm. Next, as shown in FIG. 5F, a second metal layer 35 is formed on the second graphene layer 33, wherein the thickness D8 of the second metal layer 35 is between 1 micrometer and 30 micrometers. Preferably, the material of the second metal layer 35 is selected from copper or nickel. It should be noted that, in this step, since the second graphene layer 33 functions as a barrier layer, metal ions of the second metal layer 35 will not diffuse to the dielectric layer 21 in a high-temperature manufacturing environment. As shown in FIG. 5F, the first graphene layer 32 is disposed between the dielectric layer 31 and the first metal layer 34, and the second graphene layer 33 is disposed between the dielectric layer 31 and the second metal layer 35. between. Finally, the insulating substrate 1 is removed, and the manufacturing of the thin film capacitor 30 is completed.

In summary, the present disclosure uses a graphene layer as an electrode layer of a thin film capacitor, or a graphene layer is disposed between a dielectric layer and a metal layer so that the graphene layer and the metal layer work together as the electrode layer. The electrode layer of a thin film capacitor can further solve the problem of poor capacitor performance due to metal ion diffusion into the dielectric layer during the manufacturing process. Furthermore, by applying graphene to the thin film capacitors disclosed herein, the thin film capacitors have better charging rates, charge storage, and charge and discharge capabilities. In addition, the good characteristics of graphene can enhance the service life and charge transfer speed of electrodes of thin film capacitors, improve the capacity of capacitor storage, and reduce the overall impedance generated when applied to high-speed signal measurement.

Although the present disclosure has been disclosed as above with the preferred embodiment, it is not intended to limit the present disclosure. Those with ordinary knowledge in the technical field to which this disclosure belongs can make various changes and modifications without departing from the spirit and scope of this disclosure. Retouching, therefore, the scope of protection of this disclosure shall be determined by the scope of the attached patent application.

Claims (7)

A thin film capacitor includes: a dielectric layer; a pair of graphene layers respectively disposed on opposite sides of the dielectric layer to serve as electrodes of the thin film capacitor; and a pair of metal layers respectively disposed on the pair of graphene The two opposite sides of the layer are such that one of the graphene layers is disposed between the dielectric layer and one of the metal layers to prevent metal ions of the metal layer from diffusing into the dielectric layer. The thin film capacitor according to item 1 of the scope of the patent application, wherein the thickness of each graphene layer is between 0.3 nm and 10 microns. The thin film capacitor according to item 1 of the scope of patent application, wherein the thickness of each metal layer is between 1 micrometer and 30 micrometers. The thin film capacitor according to item 1 of the scope of patent application, wherein the thickness of the dielectric layer is between 200 nm and 800 nm. The thin film capacitor according to item 1 of the scope of patent application, wherein the material of the dielectric layer is selected from BaTiO ₃ , Ta ₂ O ₅ , TiO ₂ , HfO ₂ , ZrO ₂ , Al ₂ O ₃ , La ₂ O ₃ , Pr ₂ O ₃ and any one of the above combinations. A method for manufacturing a thin film capacitor includes: forming a first metal layer; forming a first graphene layer on the first metal layer; forming a dielectric layer on the first graphene layer; and the first graphene A layer is interposed between the first metal layer and the dielectric layer to prevent metal ions of the first metal layer from diffusing into the dielectric layer; forming a second graphene layer on the dielectric layer so that the dielectric An electrical layer is located between the first graphene layer and the second graphene layer; and a second metal layer is formed on the second graphene layer, the second graphene layer is interposed between the second metal layer and the Between the dielectric layers, metal ions of the second metal layer are prevented from diffusing into the dielectric layer. The method for manufacturing a thin film capacitor according to item 6 of the scope of patent application, wherein the step of forming the first metal layer further includes: providing an insulating substrate; forming a metal layer on the insulating substrate; and performing a metal layer Photolithography process to form the first metal layer.