Adjustable capacitor structure and forming method thereof

Abstract

The invention provides an adjustable capacitor structure and a forming method thereof. The adjustable capacitor structure comprises a substrate; a plurality of electrode layers formed on the substrate; a plurality of dielectric layers, wherein each dielectric layer is respectively formed between two electrode layers in the plurality of electrode layers; the plurality of window holes are respectively formed above each electrode layer except the outermost electrode layer in the plurality of electrode layers and penetrate to each electrode layer, and the outermost electrode layer is the electrode layer farthest from the substrate in the plurality of dielectric layers; the insulating layer is formed on the surface of the outermost electrode layer and the side surface of each window hole; and the plurality of metal electrodes are respectively formed in the window holes and are conductively connected with the corresponding electrode layers in the window holes. According to the invention, the capacitor structure which is small in size, high in reliability and adjustable in capacitance and withstand voltage can be provided, and the capacitor structure is simple in technological process, high in customizable degree and high in adaptability.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to an adjustable capacitor structure and a forming method thereof. Background Art

[0002] At present, the existing adjustable capacitors are mainly divided into three categories: the first category is to change the capacitance value by physically adjusting the distance between the metal plates, which is usually achieved by rotating a knob or changing the electric field strength; the second category is to adjust the capacitance value by pressure changes, and this design utilizes the elastic deformation of the medium; the third category is to adjust the capacitance value by changing the voltage applied between the electrodes, which requires the cooperation of external excitation conditions.

[0003] However, existing adjustable capacitor structures have some limitations. For example, although large-volume metal shell capacitors can achieve linear adjustment of capacitance, they are large in size and low in precision, which limits their use in miniaturization and high-precision applications. In addition, although the capacitor design using elastic deformable media can adjust the capacitance by changing the thickness of the medium by extrusion method, it also faces the problem of large volume. In addition, the capacitor design that adjusts the capacitance by changing the applied voltage has high requirements on the adaptability of the system, which may increase the complexity of circuit design. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes an adjustable capacitor structure and a method for forming the same, the capacitor structure has a small size, high reliability, and adjustable capacitance and withstand voltage, and the capacitor structure has a simple process, a high degree of customization, and high adaptability.

[0005] Specifically, the present invention is achieved through the following technical solutions: In a first aspect, the present invention provides an adjustable capacitor structure, the adjustable capacitor structure comprising: a substrate; A plurality of electrode layers are formed on the substrate; a plurality of dielectric layers, each of which is formed between two electrode layers among the plurality of electrode layers; a plurality of window holes are formed above each electrode layer except the outermost electrode layer among the plurality of electrode layers and penetrate through each electrode layer, wherein the outermost electrode layer is the electrode layer farthest from the substrate among the plurality of dielectric layers; an insulating layer is formed on the surface of the outermost electrode layer and on the side of each window hole; and a plurality of metal electrodes are formed in each window hole and are conductively connected to the corresponding electrode layer in each window hole.

[0006] Furthermore, the surface of the outermost electrode layer includes a reserved area not covered by the insulating layer, and an outermost metal electrode conductively connected to the outermost electrode layer is formed on the reserved area.

[0007] Furthermore, the material of the substrate is a non-conductive material, and the non-conductive material includes high-resistance silicon or glass.

[0008] Furthermore, the material of the substrate is a conductive material, and the adjustable capacitor structure further includes a metal electrode layer, which is formed on the other side of the substrate opposite to the side where the multiple electrode layers are formed, and is conductively connected to the electrode layer adjacent to the substrate through the substrate.

[0009] Furthermore, the conductive material is low-resistance silicon.

[0010] Furthermore, the material of the multiple electrode layers is polysilicon.

[0011] Furthermore, the material of the insulating layer is an insulating material, and the insulating material includes silicon dioxide.

[0012] Furthermore, the plurality of electrode layers and the plurality of dielectric layers are respectively formed on the substrate by a chemical vapor deposition process.

[0013] Furthermore, a window hole penetrating to each electrode layer is formed above each electrode layer by an etching process.

[0014] In a second aspect, the present invention provides a method for forming an adjustable capacitor structure, the method comprising: forming a plurality of electrode layers and a plurality of dielectric layers on a substrate by a chemical vapor deposition process, so that each dielectric layer is formed between two electrode layers; forming a window hole penetrating to each electrode layer above each electrode layer except an outermost electrode layer among the plurality of electrode layers by an etching process, wherein the outermost electrode layer is the electrode layer farthest from the substrate among the plurality of dielectric layers; forming an insulating layer on the surface of the outermost electrode layer and on the side of each window hole; forming a metal electrode in each window hole, so that each metal electrode is connected to the corresponding electrode layer; and forming a reserved area on the surface of the outermost electrode layer that is not covered by the insulating layer and forming an outermost metal electrode conductively connected to the outermost electrode layer on the reserved area.

[0015] The present invention provides an adjustable capacitor structure and a method for forming the same. By providing multiple electrode layers and multiple metal electrodes conductively connected to the multiple electrode layers in the adjustable capacitor structure, required capacitance indicators can be integrated into a capacitor, thereby providing a capacitor structure with a small size, high reliability, and adjustable capacitance and withstand voltage. The capacitor structure has a simple process, a high degree of customization, and high adaptability.

[0016] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 is a top view of an adjustable capacitor structure according to a first embodiment of the present invention; Figure 2 is a cross-sectional view of an adjustable capacitor structure according to a first embodiment of the present invention; Figure 3 is a top view of an adjustable capacitor structure according to a second embodiment of the present invention; Figure 4 is a cross-sectional view of an adjustable capacitor structure according to a second embodiment of the present invention; Figure 5 is a flow chart of a method for forming an adjustable capacitor structure according to an embodiment of the present invention. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] Figure 1 is a top view of an adjustable capacitor structure according to a first embodiment of the present invention, Figure 2 is a cross-sectional view of an adjustable capacitor structure according to a first embodiment of the present invention.

[0021] Reference Figure 1 and Figure 2 The adjustable capacitor structure according to the present invention may include a substrate, a plurality of electrode layers, a plurality of dielectric layers, a plurality of window holes, an insulating layer and a plurality of metal electrodes PAD1-PAD4.

[0022] In this embodiment, the material of the substrate is a non-conductive material that is resistant to high temperatures. For example, the non-conductive material includes high-resistance silicon or glass.

[0023] like Figure 2As shown, multiple electrode layers are formed on a substrate, and dielectric layers are formed between each of the multiple electrode layers. The material of the electrode layer can be polysilicon, and the dielectric layer is formed of an insulating material to ensure the insulation between the electrode layers. Multiple electrode layers and multiple dielectric layers can be formed on the substrate respectively by a chemical vapor deposition (LPCVD) process. In addition, the capacitance corresponding to different electrode PADs can be defined by defining different area sizes of the electrode layer (polysilicon layer) and different thicknesses of the dielectric layer by photolithography and etching.

[0024] Each of the plurality of window holes can be formed by a photolithography process above each electrode layer except the outermost electrode layer among the plurality of electrode layers and penetrates each electrode layer, wherein the outermost electrode layer is the electrode layer farthest from the substrate among the plurality of dielectric layers. Figure 2 The top electrode layer 4 is the outermost electrode layer. The dielectric layer and the electrode layer (polysilicon layer) at the window position can be etched cleanly by an etching process, and the etching process can be dry etching or wet etching.

[0025] The insulating layer is formed on the surface of the outermost electrode layer 4 and the side of each window hole. Specifically, the surface of the outermost electrode layer 4 (except the reserved area) is covered with an insulating layer, and the side of each window hole is also covered with an insulating layer, but the bottom surface of each window hole is not covered with an insulating layer, so that the metal electrode PAD in the window hole is conductively connected to the electrode layer through which the window hole passes. The surface of the outermost electrode layer 4 includes a reserved area not covered with the insulating layer, and the outermost metal electrode PAD1 conductively connected to the outermost electrode layer 4 is formed on the reserved area. In addition, the material of the insulating layer can be silicon dioxide SiO2. The insulating layer is formed to ensure that when the metal electrode PAD is deposited, the metal electrode PAD is only conductively connected to the polysilicon layer without oxide layer protection to avoid short circuit with other polysilicon layers. In addition to the insulating effect, the insulating layer also serves to isolate water vapor.

[0026] A plurality of metal electrodes PAD1-PAD4 are formed in each window hole, and are conductively connected to the corresponding electrode layer in each window hole, for example, metal electrode PAD1 is conductively connected to electrode layer 1, metal electrode PAD2 is conductively connected to electrode layer 2, metal electrode PAD3 is conductively connected to electrode layer 3, and metal electrode PAD4 is conductively connected to electrode layer 4. It should be noted that although Figure 1 and Figure 2 Four metal electrodes PAD1 - PAD4 are shown, but the adjustable capacitor structure of the present invention is not limited thereto, and any number of metal electrodes PAD can be provided as required.

[0027] According to the principle of capacitance, the capacitance value is related to the dielectric constant, the plate area, and the dielectric layer thickness, and the dielectric withstand voltage is related to the dielectric material and dielectric thickness. Therefore, different layers of dielectrics can be designed with different materials and thicknesses according to actual use requirements to realize a capacitor. By connecting different metal electrodes PAD in the orthogonal combination of metal electrodes PAD1-PAD4, different capacitance values ​​and different withstand voltages can be achieved, realizing the function of adjustable capacitance.

[0028] Figure 3 is a top view of an adjustable capacitor structure according to a second embodiment of the present invention, Figure 4 is a cross-sectional view of an adjustable capacitor structure according to a second embodiment of the present invention.

[0029] Reference Figure 3 and Figure 4 , which is different from the first embodiment in that, in the second embodiment, the material of the substrate is a conductive material (e.g., low-resistance silicon), and the metal electrode PAD4 of the adjustable capacitance structure is formed as a metal electrode layer PAD4, which is formed on the other side of the substrate opposite to the side where the multiple electrode layers PAD1-PAD3 are formed, and is conductively connected to the electrode layer adjacent to the conductive substrate through the conductive substrate. For example, in Figure 4 In FIG. 1 , the metal electrode layer PAD4 is shown as the bottom layer of the structure. The upper metal electrodes PAD1-PAD3 are optional for adjustable capacitance. It should be noted that although Figure 3 and Figure 4 Three upper metal electrodes PAD1 - PAD3 and one metal electrode layer PAD4 are shown, but the adjustable capacitor structure of the present invention is not limited thereto, and any number of upper metal electrodes PAD can be provided as required.

[0030] The adjustable capacitor structure involved in the present invention has a small volume (capacitor size is in the order of mm) compared with the existing large-volume, plate spacing-adjustable adjustable capacitor technology; the electrode film layer and the dielectric film layer are manufactured using semiconductor technology, the photolithography accuracy is in the order of μm, and the capacitance accuracy is high (can reach the order of pF); the film layer is deposited at a high temperature, and the product reliability is high; and both the capacitance value and the dielectric withstand voltage index can be adjusted.

[0031] Figure 5 FIG. 1 is a flow chart of a method for forming an adjustable capacitor structure according to an embodiment of the present invention. Figure 5 According to an embodiment of the present invention, the method for forming an adjustable capacitor structure may include the following steps: Step 1: forming a plurality of electrode layers and a plurality of dielectric layers on the substrate by chemical vapor deposition process, so that each dielectric layer is formed between two electrode layers; Step 2: forming a window hole penetrating to each electrode layer above each electrode layer except the outermost electrode layer among the multiple electrode layers by an etching process, wherein the outermost electrode layer is the electrode layer farthest from the substrate among the multiple dielectric layers; Step 3: forming an insulating layer on the surface of the outermost electrode layer and the side of each window hole; Step 4: forming a metal electrode in each window hole so that each metal electrode is connected to a corresponding electrode layer; and Step 5: forming a reserved area not covered by the insulating layer on the surface of the outermost electrode layer and forming an outermost metal electrode conductively connected to the outermost electrode layer on the reserved area.

[0032] The adjustable capacitor structure according to the present invention can be formed by the adjustable capacitor structure forming method. The process of the method is simple, and the obtained capacitor structure is highly customizable and adaptable.

[0033] In summary, the present invention provides an adjustable capacitor structure and a method for forming the same. By setting multiple electrode layers and multiple metal electrodes conductively connected to the multiple electrode layers in the adjustable capacitor structure, the required capacitance indicators can be integrated into a capacitor, thereby providing a capacitor structure with a small size, high reliability, and adjustable capacitance and withstand voltage. The process for forming the capacitor structure is simple, highly customizable, and highly adaptable.

[0034] In addition, in the present invention, the description with reference to the terms "embodiment", "present embodiment", "another embodiment", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples, unless they are contradictory.

[0035] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An adjustable capacitor structure, characterized in that: include: substrate; A plurality of electrode layers are formed on the substrate; A plurality of dielectric layers, each dielectric layer being formed between two electrode layers among the plurality of electrode layers; A plurality of window holes are respectively formed above each electrode layer except the outermost electrode layer among the plurality of electrode layers and penetrate each electrode layer, wherein the outermost electrode layer is the electrode layer farthest from the substrate among the plurality of dielectric layers; An insulating layer formed on the surface of the outermost electrode layer and the side of each window hole; as well as A plurality of metal electrodes are formed in each window hole, respectively, and are conductively connected to the corresponding electrode layer in each window hole.

2. The adjustable capacitor structure according to claim 1, characterized in that: The surface of the outermost electrode layer includes a reserved area not covered by the insulating layer, and an outermost metal electrode conductively connected to the outermost electrode layer is formed on the reserved area.

3. The adjustable capacitor structure according to claim 2, characterized in that: The substrate is made of non-conductive material, and the non-conductive material includes high-resistance silicon or glass.

4. The adjustable capacitor structure according to claim 2, characterized in that: The material of the substrate is a conductive material, and the adjustable capacitor structure further includes a metal electrode layer, which is formed on the other side of the substrate opposite to the side where the multiple electrode layers are formed, and is conductively connected to the electrode layer adjacent to the substrate through the substrate.

5. The adjustable capacitor structure according to claim 4, characterized in that: The conductive material is low-resistance silicon.

6. The adjustable capacitor structure according to claim 3 or 4, characterized in that: The material of the plurality of electrode layers is polysilicon.

7. The adjustable capacitor structure according to claim 6, characterized in that: The insulating layer is made of insulating material, and the insulating material includes silicon dioxide.

8. The adjustable capacitor structure according to claim 7, characterized in that: The plurality of electrode layers and the plurality of dielectric layers are respectively formed on the substrate by a chemical vapor deposition process.

9. The adjustable capacitor structure according to claim 8, characterized in that: A window hole penetrating through each electrode layer is formed above each electrode layer by an etching process.

10. A method for forming an adjustable capacitor structure, characterized in that: include: Forming a plurality of electrode layers and a plurality of dielectric layers on the substrate respectively by a chemical vapor deposition process, so that each dielectric layer is formed between two electrode layers; Forming a window hole penetrating to each electrode layer above each electrode layer except the outermost electrode layer among the plurality of electrode layers by an etching process, wherein the outermost electrode layer is the electrode layer farthest from the substrate among the plurality of dielectric layers; forming an insulating layer on the surface of the outermost electrode layer and the side of each window hole; forming a metal electrode in each window hole so that each metal electrode is connected to a corresponding electrode layer; as well as A reserved area not covered by the insulating layer is formed on the surface of the outermost electrode layer, and an outermost metal electrode conductively connected to the outermost electrode layer is formed on the reserved area.

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