A micromechanical capacitance compensation structure and a method for producing the same

Abstract

The present application relates to a kind of micromechanical capacitance compensation structure and its preparation method, the capacitance compensation structure is in the shape of cylinder, cone, platform or inverted crater, be arranged in capacitor plate inside, for changing capacitance.When being arranged below the plate, recess is formed by depositing sacrificial layer and patterning on the lower plate structure layer;Depositing thin film material, etching to remove the surface medium thin film material of sacrificial layer, retaining the medium material in recess;Depositing capacitor upper plate structure layer thin film material, and patterning is formed release hole;After releasing the sacrificial layer through release hole, the compensation capacitance structure is obtained.When being arranged above the plate, convex structure is formed by etching to form thin film material on the lower plate structure layer of capacitor;Depositing and planarizing sacrificial layer;Depositing capacitor upper plate and patterning is formed release hole;After releasing the sacrificial layer through release hole, the compensation capacitance structure is obtained.The present application realizes capacitance matching and compensation, especially for differential capacitance structure, reaches the effect of upper and lower symmetrical capacitance structure.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of capacitive MEMS (Micro Electro Mechanical System) structure, in particular to a micro mechanical capacitor compensation structure and a preparation method thereof. BACKGROUND

[0002] Capacitive MEMS (Micro Electro Mechanical System) structure is widely used in various devices, in some application occasions, differential capacitor structure is adopted, which is beneficial to further improve the performance of the device. The motion structure of the differential capacitor often needs to be symmetrical on both sides in the static state, which is beneficial to the measurement and calculation of the differential capacitor in the movable structure movement process.

[0003] Generally, for solid capacitors, the capacitance can be increased by increasing the dielectric constant of the medium, and in the present application, the movable capacitor is mentioned, the medium is air, and the dielectric constant is usually fixed. The existing technology changes the method of changing the capacitor, but the area and distance of the electrode plate are often difficult to change due to the design requirements of the device in practical application. The method of changing the capacitor by increasing the capacitor compensation structure inside the electrode plate is more ingenious.

[0004] The prior art does not particularly add a composite layer capacitor compensation structure formed by a high dielectric constant material, the dimple structure is very short and is usually a single material, and often only serves as a structure to prevent sticking during movement.

[0005] The present application realizes capacitor compensation to obtain an upper and lower symmetrical capacitor structure by designing and manufacturing a capacitor compensation structure in the MEMS structure, and the structure can also be used as a dimple structure to prevent sticking during the movement of the electrode plate. SUMMARY

[0006] The present application aims to overcome the problem of asymmetry of the capacitor on both sides of the structure, thereby providing a micro mechanical capacitor compensation structure and a preparation method thereof. The present application can flexibly change the capacitance by setting compensation structures with different sizes, materials and densities inside the electrode plate without changing the area and distance of the capacitor electrode plate.

[0007] To solve the above technical problems, the technical scheme of the present application provides a micro mechanical capacitor compensation structure and a preparation method thereof.

[0008] The present application provides a micro mechanical capacitor compensation structure, which is in the shape of a column, a cone, a table or a reverse crater, and is made of a medium with a high dielectric constant and is arranged inside the electrode plate of a capacitor to change the capacitance.

[0009] As one of the improvements of the above technical solutions, the material of the capacitance compensation structure is silicon nitride (Si3N4) or a composite layer formed by wrapping silicon oxide (SiO2), borosilicate glass (BSG), phosphosilicate glass (PSG), borophosphosilicate glass (BPSG), aluminum oxide (Al2O3), yttrium oxide (Y2O3), lanthanum oxide (La2O3), tantalum pentoxide (Ta2O5), titanium dioxide (TiO2), hafnium dioxide (HfO2), zirconium oxide (ZrO) or one or more of the above materials.

[0010] As one of the improvements of the above technical solutions, the capacitance compensation structure is arranged below the upper electrode plate, above the lower electrode plate, above the middle electrode plate or below the middle electrode plate, so as to realize capacitance adjustment on one side or on both sides.

[0011] As one of the improvements of the above technical solutions, the distribution density of the capacitance compensation structure on the electrode plate is set as uniform distribution or dense on both sides and sparse in the middle.

[0012] As one of the improvements of the above technical solutions, the length of the capacitance compensation structure is set as the same length on the whole electrode plate or the length of the capacitance compensation structure in the middle of the electrode plate is shorter and the length of the capacitance compensation structure on both sides of the electrode plate is longer.

[0013] The present application provides a preparation method of a micromechanical capacitance compensation structure, which comprises the following steps when the capacitance compensation structure is arranged below the capacitance electrode plate:

[0014] a) depositing and patterning a sacrificial layer on the lower electrode plate adjacent to the capacitance electrode plate to form a recess for assisting the subsequent capacitance compensation structure;

[0015] b) depositing a thin film material with a dielectric constant greater than that of air to fill the recess and form a protruding structure; using the end-point detection (EPD) function, etching to remove the dielectric thin film material on the surface of the sacrificial layer and retaining the dielectric material in the recess;

[0016] c) depositing a thin film material of the capacitance electrode plate and patterning to form a release etching hole;

[0017] d) using wet etching or dry etching to release the sacrificial layer through the release hole to obtain the capacitance compensation structure.

[0018] As one of the improvements of the above technical solutions, the method for removing the dielectric thin film material on the surface of the sacrificial layer in step b) is chemical mechanical polishing (CMP), and the surface of the sacrificial layer is polished flat.

[0019] As another improvement of the above technical solution, the material of the capacitor plate is silicon, polysilicon, amorphous silicon, a composite layer of polysilicon and silicon nitride, or a composite layer of amorphous silicon and silicon nitride.

[0020] The present application provides a preparation method of a micromechanical capacitor compensation structure, when a capacitor compensation structure is arranged above a capacitor plate, the method comprises the following steps:

[0021] a) depositing a thin film material with a dielectric constant greater than that of air on the capacitor plate, and etching the thin film material to form a convex structure by photolithography;

[0022] b) depositing a sacrificial layer and planarizing the sacrificial layer by CMP;

[0023] c) depositing an upper plate adjacent to the capacitor plate and patterning the upper plate to complete the fabrication of the capacitor compensation structure.

[0024] As an improvement of the above technical solution, when the sacrificial layer is deposited, the material of the sacrificial layer is a single material of silicon oxide, boron-silicon glass (BSG), phosphorus-silicon glass (PSG), or boron-phosphorus-silicon glass (BPSG), or a composite material stacked randomly by at least two of the above materials, and the deposition method is chemical vapor deposition (CVD); the CVD includes low-pressure chemical vapor deposition (LPCVD), atmospheric pressure chemical vapor deposition (APCVD), sub-atmospheric pressure chemical vapor deposition (SACVD), or plasma-enhanced chemical vapor deposition (PECVD).

[0025] The technical effects achieved by the micromechanical capacitor compensation structure of the present application are as follows:

[0026] 1. Capacitor compensation is achieved, and the effect of symmetric capacitor structure is achieved;

[0027] 2. The capacitor compensation structure can also be used as a dimple to avoid adhesion between the movable structure and the adjacent structure;

[0028] 3. The capacitor compensation structure cooperates with CMP to achieve planarization of the structure layer, facilitating subsequent small-line patterning. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 FIG. 1 is a sectional view of a micromechanical capacitor compensation structure according to the present application arranged on a capacitor plate;

[0030] Figure 2 a), b), c), and d) are schematic diagrams of steps a), b), c), and d) of arranging the capacitor compensation structure according to the present application below a capacitor upper plate, respectively;

[0031] Figure 3a), b), c) are schematic diagrams of steps a), b), c) of arranging the capacitor compensation structure of the application above the lower plate of the capacitor in sequence, respectively;

[0032] Figure 4 It is a cross-sectional schematic diagram of embodiment 1 of the application: the lower capacitor (capacitor 1) has a small plate spacing, the upper capacitor (capacitor 2) has a large plate spacing, the capacitor compensation structure is arranged below the upper plate of the upper capacitor, and the upper and lower capacitors are equal;

[0033] Figure 5 It is a cross-sectional schematic diagram of embodiment 2 of the application: the lower capacitor (capacitor 1) has a plate spacing equal to that of the upper capacitor (capacitor 2), the capacitor compensation structure is arranged above the lower plate of the lower capacitor and below the upper plate of the upper capacitor, and the upper and lower capacitors are equal;

[0034] Figure 6 It is a cross-sectional schematic diagram of embodiment 3 of the application: the lower capacitor (capacitor 1) has a plate spacing equal to that of the upper capacitor (capacitor 2), the capacitor compensation structure is arranged below the upper plate of the lower capacitor and below the upper plate of the upper capacitor, and the upper and lower capacitors are equal;

[0035] Figure 7 It is a cross-sectional schematic diagram of embodiment 4 of the application: the lower capacitor (capacitor 1) has a plate spacing equal to that of the upper capacitor (capacitor 2), the capacitor compensation structure is arranged above the lower plate of the lower capacitor and below the upper plate of the upper capacitor, and the compensation structure has a non-uniform density distribution, with low density in the middle and high density at the edges, and the upper and lower capacitors are equal;

[0036] Figure 8 It is a cross-sectional schematic diagram of embodiment 5 of the application: the lower capacitor (capacitor 1) has a plate spacing equal to that of the upper capacitor (capacitor 2), the capacitor compensation structure is arranged below the upper plate of the lower capacitor and below the upper plate of the upper capacitor, and the compensation structure has a non-uniform density distribution, with low density in the middle and high density at the edges, and the upper and lower capacitors are equal;

[0037] Figure 9 It is a cross-sectional schematic diagram of embodiment 6 of the application: the lower capacitor (capacitor 1) has a plate spacing equal to that of the upper capacitor (capacitor 2), the capacitor compensation structure is arranged above the lower plate of the lower capacitor and below the upper plate of the upper capacitor, and the compensation structure has a non-uniform density distribution, with low density in the middle and high density at the edges, and the upper and lower capacitors are equal;

[0038] Figure 10The cross-sectional schematic view of the embodiment 7 of the present application is shown in the figure: the distance between the lower capacitor (capacitor 1) plates and the distance between the upper capacitor (capacitor 2) plates are equal, the capacitor compensation structure of single material is arranged below the upper plate of the lower capacitor and below the upper plate of the upper capacitor, the capacitor compensation structure has multiple different length distributions, the middle compensation structure has a short length, the two side edge compensation structures have a long length, and the upper and lower capacitors are equal;

[0039] Figure 11 The cross-sectional schematic view of the embodiment 8 of the present application is shown in the figure: the distance between the lower capacitor (capacitor 1) plates and the distance between the upper capacitor (capacitor 2) plates are equal, the capacitor compensation structure of composite material is arranged above the lower plate of the lower capacitor and below the upper plate of the upper capacitor, the capacitor compensation structure has multiple different length distributions, the middle compensation structure has a short length, the two side edge compensation structures have a long length, and the upper and lower capacitors are equal;

[0040] Figure 12 The cross-sectional schematic view of the embodiment 9 of the present application is shown in the figure: the distance between the lower capacitor (capacitor 1) plates and the distance between the upper capacitor (capacitor 2) plates are equal, the capacitor compensation structure of composite material is arranged below the upper plate of the lower capacitor and below the upper plate of the upper capacitor, the capacitor compensation structure has multiple different length distributions, the middle compensation structure has a short length, the two side edge compensation structures have a long length, and the upper and lower capacitors are equal;

[0041] Figure 13 The cross-sectional schematic view of the embodiment 10 of the present application is shown in the figure: the distance between the lower capacitor (capacitor 1) plates and the distance between the upper capacitor (capacitor 2) plates are equal, the capacitor compensation structure of single material is arranged below the upper plate of the lower capacitor and above the lower plate of the upper capacitor, the capacitor compensation structure has multiple different length distributions, the middle compensation structure has a short length, the two side edge compensation structures have a long length, and the upper and lower capacitors are equal;

[0042] Figure 14 The cross-sectional schematic view of the embodiment 11 of the present application is shown in the figure: the distance between the lower capacitor (capacitor 1) plates and the distance between the upper capacitor (capacitor 2) plates are equal, the capacitor compensation structure of composite material is arranged below the upper plate of the lower capacitor and above the lower plate of the upper capacitor, the capacitor compensation structure has multiple different length distributions, the middle compensation structure has a short length, the two side edge compensation structures have a long length, and the upper and lower capacitors are equal;

[0043] Figure 15 The cross-sectional schematic view of the embodiment 12 of the present application is shown in the figure: the distance between the lower capacitor (capacitor 1) plates is smaller than the distance between the upper capacitor (capacitor 2) plates, the capacitor compensation structure of single material is arranged on the upper plate of the upper capacitor, the capacitor compensation structure has an inverted crater shape, and the upper and lower capacitors are equal;

[0044] Figure 16The following is a cross-sectional schematic diagram of Embodiment 13 of the present invention: the spacing between the plates of the lower capacitor (capacitor 1) and the spacing between the plates of the upper capacitor (capacitor 2) are equal. A capacitor compensation structure of a single material is provided above the lower plate of the lower capacitor and below the upper plate of the upper capacitor. The capacitor compensation structure is cone-shaped and the upper and lower capacitors are equal.

[0045] Figure 17 The following is a cross-sectional schematic diagram of Embodiment 14 of the present invention: the spacing between the plates of the lower capacitor (capacitor 1) and the upper capacitor (capacitor 2) is equal. A capacitor compensation structure of a single material is provided below the upper plate of the lower capacitor and below the upper plate of the upper capacitor. The capacitor compensation structure is in the shape of a platform, and the upper and lower capacitors are equal. Detailed Implementation

[0046] The technical solutions provided by the present invention will be further illustrated below with reference to the embodiments.

[0047] like Figure 1 The diagram shows a cross-sectional view of the micromechanical capacitor compensation structure proposed in this invention, which is set on the capacitor plates. Based on the factors affecting the capacitance, including the area of ​​the plates facing each other, the distance between the plates, and the dielectric constant of the medium between the plates, the area and distance between the plates are fixed. By setting a micro-protrusion structure (Dimple structure) with a different dielectric constant from the original capacitor medium on the inner surface of the plates, the dielectric constant of the medium between the plates is changed, thereby changing the capacitance.

[0048] like Figure 2 As shown in a), b), c), and d), respectively, these are schematic diagrams of steps a), b), c), and d) of setting the capacitor compensation structure of the present invention below the capacitor plates, specifically including the following steps:

[0049] When a micro-capacitor compensation structure (Dimple) is installed below the capacitor plates,

[0050] a) After the lower capacitor structure is fabricated, a sacrificial layer is deposited and patterned to form a pit that helps to realize the subsequent Dimple structure.

[0051] b) A thin film material with a higher dielectric constant than air is deposited to fill the pits and form dimples. A high dielectric constant dielectric is used between the capacitors to increase the capacitance of the upper capacitor structure. The endpoint etching (EPD) function is used to etch away the dielectric film material on the surface of the sacrificial layer, retaining the dielectric material in the pits.

[0052] c) Deposit the structured thin film material and pattern it to form corrosion-releasing pores;

[0053] d) A movable capacitor structure is obtained by releasing the sacrificial layer through the release hole using wet or dry etching.

[0054] Preferably, the sacrificial layer is silicon oxide, borosilicate glass (BSG), phosphosilicate glass (PSG), borosilicate phosphosilicate glass (BPSG), or a composite material of at least two of these randomly stacked, and its deposition method is chemical vapor deposition (CVD), including low-pressure chemical vapor deposition (LPCVD), atmospheric pressure chemical vapor deposition (APCVD), sub-atmospheric pressure chemical vapor deposition (SACVD), or plasma-enhanced chemical vapor deposition (PECVD).

[0055] Preferably, the micro-bump structure is made of silicon nitride (Si3N4) or a composite layer formed by encapsulating silicon nitride (Si3N4) with one or more of the following materials: silicon oxide (SiO2), borosilicate glass (BSG), phosphosilicate glass (PSG), borosilicate phosphosilicate glass (BPSG), aluminum oxide (Al2O3), yttrium oxide (Y2O3), lanthanum oxide (La2O3), tantalum pentoxide (Ta2O5), titanium dioxide (TiO2), hafnium dioxide (HfO2), and zirconium oxide (ZrO).

[0056] Preferably, in b), the method for removing the dielectric film material from the surface of the sacrificial layer is chemical mechanical polishing (CMP), which grinds the surface of the sacrificial layer flatter.

[0057] Preferably, the upper structure is made of materials such as silicon, polycrystalline silicon, amorphous silicon, a composite layer of polycrystalline silicon and silicon nitride, or a composite layer of amorphous silicon and silicon nitride.

[0058] like Figure 3 As shown in a), b), and c), respectively, these are schematic diagrams of steps a), b), and c) of setting the capacitor compensation structure of the present invention above the capacitor plates, specifically including the following steps:

[0059] When a micro-capacitor compensation structure (Dimple) is placed above the capacitor plates,

[0060] a) After the lower electrode structure of the lower capacitor is fabricated, a thin film material with a dielectric constant greater than that of air is deposited, and photolithography is used to form a Dimple structure.

[0061] b) Deposited sacrificial layer and CMP planarized sacrificial layer;

[0062] c) Deposit and pattern the intermediate electrode of the capacitor to complete the fabrication of the lower capacitor structure;

[0063] Then, referring to the previous process of setting up the Dimple below the capacitor plate, the upper capacitor structure can be formed, and then the release can be arranged to form the overall differential capacitor structure.

[0064] Preferably, the sacrificial layer is silicon oxide, borosilicate glass (BSG), phosphosilicate glass (PSG), borosilicate phosphosilicate glass (BPSG), or a composite material of at least two of these randomly stacked, and its deposition method is chemical vapor deposition (CVD), including low-pressure chemical vapor deposition (LPCVD), atmospheric pressure chemical vapor deposition (APCVD), sub-atmospheric pressure chemical vapor deposition (SACVD), or plasma-enhanced chemical vapor deposition (PECVD).

[0065] Preferably, Dimple is a composite layer formed by encapsulating one or more of silicon nitride (Si3N4), such as silicon oxide (SiO2), borosilicate glass (BSG), phosphosilicate glass (PSG), borosilicate phosphosilicate glass (BPSG), aluminum oxide (Al2O3), yttrium oxide (Y2O3), lanthanum oxide (La2O3), tantalum pentoxide (Ta2O5), titanium dioxide (TiO2), hafnium dioxide (HfO2), and zirconium oxide (ZrO).

[0066] Preferably, after the sacrificial layer is deposited in step b), chemical mechanical polishing (CMP) is used to grind the sacrificial layer to the surface of the Dimple structure before depositing the sacrificial layer again, so that the surface of the sacrificial layer is flatter.

[0067] Preferably, the capacitor plate structure is made of materials such as silicon, polycrystalline silicon, amorphous silicon, a composite layer of polycrystalline silicon and silicon nitride, or a composite layer of amorphous silicon and silicon nitride.

[0068] like Figure 4 The image shown is a cross-sectional schematic diagram of Embodiment 1 of the present invention:

[0069] like Figure 2 Step d) shown is Example 1, where the upper and lower capacitors are equal, the spacing between the plates of the lower capacitor (capacitor 1) is small, and there is no capacitor compensation structure on the plates of the lower capacitor, while the spacing between the plates of the upper capacitor (capacitor 2) is large, and a capacitor compensation structure with a high dielectric constant is provided below the upper plate of the upper capacitor. The capacitor compensation structure is made of a single material or a composite material.

[0070] like Figure 5 The image shown is a cross-sectional schematic diagram of Embodiment 2 of the present invention:

[0071] The upper and lower capacitors are equal, and the spacing between the plates of the lower capacitor (capacitor 1) and the upper capacitor (capacitor 2) is equal. Both the lower plate of the lower capacitor and the upper plate of the upper capacitor have a Dimple structure with a high dielectric constant. The Dimple has the same length and can be made of a single material or a composite material.

[0072] like Figure 6As shown, this is a cross-sectional schematic diagram of Embodiment 3 of the present invention: the upper and lower capacitors are equal, the spacing between the plates of the lower capacitor (capacitor 1) and the upper capacitor (capacitor 2) is equal, and a capacitor compensation structure with a high dielectric constant is provided below the upper plate of the lower capacitor and below the upper plate of the upper capacitor. The capacitor compensation structures have the same length and are made of a single or composite material.

[0073] like Figure 7 The image shown is a cross-sectional schematic diagram of Embodiment 4 of the present invention:

[0074] The upper and lower capacitors are equal. The spacing between the plates of the lower capacitor (capacitor 1) and the upper capacitor (capacitor 2) is equal. High dielectric constant capacitor compensation structures are provided above the lower plate of the lower capacitor and below the upper plate of the upper capacitor. The capacitor compensation structures have the same length, but the density distribution is uneven. The density of the compensation structure in the middle is low, while the two sides have dense compensation structures. The capacitor compensation structure is made of a single material or a composite material.

[0075] like Figure 8 The image shown is a cross-sectional schematic diagram of Embodiment 5 of the present invention:

[0076] The upper and lower capacitors are equal. The spacing between the plates of the lower capacitor (capacitor 1) and the upper capacitor (capacitor 2) is equal. High dielectric constant capacitor compensation structures are provided below the upper plates of both the lower and upper capacitors. The capacitor compensation structures have the same length but uneven density distribution. The density of the compensation structure in the middle is low, while the two sides have dense compensation structures. The capacitor compensation structure is made of a single material or a composite material.

[0077] like Figure 9 The figure shown is a cross-sectional schematic diagram of Embodiment 6 of the present invention: (The dashed line in the figure refers to the boundary when the intermediate electrode plate vibrates)

[0078] The upper and lower capacitors are equal, and the spacing between the plates of the lower capacitor (capacitor 1) and the upper capacitor (capacitor 2) is equal. High dielectric constant capacitor compensation structures are provided above the lower plate of the lower capacitor and below the upper plate of the upper capacitor. The capacitor compensation structures have various length distributions, with the compensation structures on both sides being longer and the compensation structures in the middle being shorter. The capacitor compensation structures are made of a single material.

[0079] like Figure 10 The image shown is a cross-sectional schematic diagram of Embodiment 7 of the present invention:

[0080] The upper and lower capacitors are equal, and the spacing between the plates of the lower capacitor (capacitor 1) and the upper capacitor (capacitor 2) is equal. High dielectric constant capacitor compensation structures are provided below the upper plate of both the lower capacitor and the upper plate of the upper capacitor. The capacitor compensation structures have various length distributions, with the compensation structures on both sides being longer and the compensation structures in the middle being shorter. The capacitor compensation structures are made of a single material.

[0081] likeFigure 11 Figure 8 shows a cross-sectional schematic view of the embodiment 8 of the present application (the dashed line in the figure indicates the boundary when the middle plate vibrates)

[0082] The upper and lower capacitances are equal, the plate spacing of the lower capacitor (capacitor 1) and the plate spacing of the upper capacitor (capacitor 2) are equal, the upper plate of the lower capacitor and the lower plate of the upper capacitor are both provided with a capacitor compensation structure with high dielectric constant, the capacitor compensation structure has multiple different length distributions, the length of the compensation structure at the two edges is longer, the length of the compensation structure in the middle is shorter, and the capacitor compensation structure is of a single material.

[0083] As shown in Figure 9, it is a cross-sectional schematic view of the embodiment 9 of the present application: Figure 12

[0084] The upper and lower capacitances are equal, the plate spacing of the lower capacitor (capacitor 1) and the plate spacing of the upper capacitor (capacitor 2) are equal, the upper plate of the lower capacitor and the lower plate of the upper capacitor are both provided with a capacitor compensation structure with high dielectric constant, the capacitor compensation structure has multiple different length distributions, the length of the compensation structure at the two edges is longer, the length of the compensation structure in the middle is shorter, and the capacitor compensation structure is of a single material.

[0085] As shown in Figure 10, it is a cross-sectional schematic view of the embodiment 10 of the present application: Figure 13

[0086] The upper and lower capacitances are equal, the plate spacing of the lower capacitor (capacitor 1) and the plate spacing of the upper capacitor (capacitor 2) are equal, the upper plate of the lower capacitor and the lower plate of the upper capacitor are both provided with a capacitor compensation structure with high dielectric constant, the capacitor compensation structure has multiple different length distributions, the length of the compensation structure at the two edges is longer, the length of the compensation structure in the middle is shorter, and the capacitor compensation structure is of a single material.

[0087] As shown in Figure 11, it is a cross-sectional schematic view of the embodiment 11 of the present application: Figure 14

[0088] The upper and lower capacitances are equal, the plate spacing of the lower capacitor (capacitor 1) and the plate spacing of the upper capacitor (capacitor 2) are equal, the upper plate of the lower capacitor and the lower plate of the upper capacitor are both provided with a capacitor compensation structure with high dielectric constant, the capacitor compensation structure has multiple different length distributions, the length of the compensation structure at the two edges is longer, the length of the compensation structure in the middle is shorter, and the capacitor compensation structure is of a single material.

[0089] The capacitor compensation structure in the above embodiments 1-11 is in the shape of a cylinder.

[0090] As shown in Figure 12, it is a cross-sectional schematic view of the embodiment 12 of the present application: Figure 15

[0091] ​​​​The upper and lower capacitors are equal, the spacing between the plates of the lower capacitor (capacitor 1) is smaller than the spacing between the plates of the upper capacitor (capacitor 2), and a capacitor compensation structure with a high dielectric constant is provided below the upper plate of the upper capacitor. The capacitor compensation structure is shaped like an inverted volcano and is evenly distributed. The capacitor compensation structure is made of a single material or a composite material.

[0092] like Figure 16 The image shown is a cross-sectional schematic diagram of Embodiment 13 of the present invention:

[0093] The upper and lower capacitors are equal, and the spacing between the plates of the lower capacitor (capacitor 1) and the upper capacitor (capacitor 2) is equal. High dielectric constant capacitor compensation structures are provided above the lower plate of the lower capacitor and below the upper plate of the upper capacitor. The capacitor compensation structures are cone-shaped and evenly distributed. The capacitor compensation structures are made of single or composite materials.

[0094] like Figure 17 The image shown is a cross-sectional schematic diagram of Embodiment 14 of the present invention:

[0095] The upper and lower capacitors are equal, and the spacing between the plates of the lower capacitor (capacitor 1) and the upper capacitor (capacitor 2) is equal. High dielectric constant capacitor compensation structures are provided below the upper plates of both the lower and upper capacitors. The capacitor compensation structures are in the shape of a platform and are evenly distributed. The capacitor compensation structures are made of a single material or a composite material.

[0096] The fabrication method of the platform-shaped capacitor compensation structure can be based on Figure 2 After step a) depositing the sacrificial layer, photolithography is used to form a pit with a sloping side. Then, step b) forms a compensation structure in the shape of a platform.

[0097] The fabrication method of the cone-shaped capacitor compensation structure can be based on Figure 2 Step a) The deposition of the sacrificial layer is divided into two layers. First, the first sacrificial layer is deposited and photolithographically etched to form a pit with vertical or sloping sides. Next, the thickness of the second sacrificial layer is more than twice the width of the opening of the pit formed by the photolithographic etching of the first sacrificial layer. After step b), a cone-shaped compensation structure can be formed.

[0098] Correspondingly, if based on Figure 2 In step a) after depositing the sacrificial layer, photolithography is used to form a pit with vertical sides, and then b) a columnar compensation structure can be formed.

[0099] For the inverted crater-shaped capacitor compensation structure, it can be realized by twice sacrificial layers. After the first layer of sacrificial layer is deposited, a pit (with vertical inclined side) is formed by photolithography and etching, then the second layer of sacrificial layer is deposited, the thickness of the second sacrificial layer is less than half of the opening width of the pit formed by the photolithography and etching of the first layer of sacrificial layer, then the capacitor compensation structure film layer is deposited, then the capacitor plate film layer is deposited, and then corresponding etching is performed to form the inverted crater-shaped compensation structure.

[0100] Generally, the compensation structure of the column (or the platform, such as the circular platform formed by rotating a trapezoidal around the central axis) is relatively easy to prepare; the inverted crater-shaped compensation structure has the most excellent structural strength; and the adhesion prevention effect of the cone is the best. In actual application, the preparation can be selected according to the specific situation.

[0101] In addition, the present application is not limited to be applied to the dual-vibrating diaphragm silicon microphone, but can also be used in the dual-back electrode silicon microphone or the dual-capacitance sensor.

[0102] As can be seen from the above detailed description of the present application, the micro-mechanical capacitor compensation structure of the present application can realize the capacitor matching and compensation, especially for the differential capacitor structure, to achieve the effect of the upper and lower symmetrical capacitor structure, so that the movable capacitor plate can achieve the effect of differential capacitor sensing output when actuated, and the sensitivity and signal-to-noise ratio of the capacitor sensing device can be improved.

[0103] Finally, it should be pointed out that the above examples are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the examples, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the present application, and they should be covered in the scope of the claims of the present application.

Claims

1. A micro-mechanical capacitor compensation structure, characterized in that, the capacitor compensation structure is in the shape of a cylinder, a cone, a platform or an inverted crater, and is made of a high dielectric constant medium arranged inside the electrode plate of a capacitor to change the capacitance; the capacitor compensation structure is arranged on the inner surface of the electrode plate to change the dielectric constant of the medium between the electrode plates, thereby changing the capacitance; the capacitor compensation structure is arranged below the upper electrode plate, above the lower electrode plate, above the middle electrode plate or below the middle electrode plate to adjust the capacitance on one side or on both sides; the capacitor compensation structure is a composite layer formed by one or more of silicon nitride, silicon oxide, borosilicate glass, phosphosilicate glass, borophosphosilicate glass, aluminum oxide, yttrium oxide, lanthanum oxide, tantalum pentoxide, titanium dioxide, hafnium dioxide and zirconium oxide; the length of the capacitor compensation structure is set to be shorter in the middle of the electrode plate and longer on both sides of the electrode plate. 2.The micro-mechanical capacitor compensation structure of claim 1, characterized in that, the distribution density of the capacitor compensation structure on the electrode plate is set to be uniform or denser on both sides and looser in the middle. 3.A method for preparing the micro-mechanical capacitor compensation structure of claim 1, comprising the following steps when the capacitor compensation structure is arranged below the capacitor electrode plate: a) depositing a sacrificial layer on the lower electrode plate adjacent to the capacitor electrode plate and patterning the sacrificial layer to form a recess for assisting the subsequent capacitor compensation structure; b) depositing a thin film material with a dielectric constant greater than that of air, and using an end-point etching function to etch and remove the thin film material on the surface of the sacrificial layer, while retaining the thin film material in the recess; c) depositing a thin film material on the capacitor electrode plate and patterning the thin film material to form a release hole; d) releasing the sacrificial layer through the release hole by wet etching or dry etching to obtain the capacitor compensation structure.

4. The method of claim 3, wherein the method further comprises: In step b), the method for removing the thin film material on the surface of the sacrificial layer is chemical mechanical polishing (CMP), and the surface of the sacrificial layer is polished flat.

5. The method of claim 3, wherein the method further comprises: The material of the capacitor electrode plate is silicon, polysilicon, amorphous silicon, a composite layer of polysilicon and silicon nitride, or a composite layer of amorphous silicon and silicon nitride. 6.A method for preparing the micro-mechanical capacitor compensation structure of claim 1, comprising the following steps when the capacitor compensation structure is arranged above the capacitor electrode plate: a) depositing a thin film material with a dielectric constant greater than that of air on the capacitor electrode plate, and performing photolithography and etching to form a protruding structure; b) depositing a sacrificial layer and CMP planarizing the sacrificial layer; c) depositing an upper electrode plate adjacent to the capacitor electrode plate and patterning the upper electrode plate to complete the fabrication of the capacitor compensation structure.

7. The method of claim 3 or 6, wherein the method further comprises: In the step of depositing the sacrificial layer, the material of the sacrificial layer is a single material of silicon oxide, borosilicate glass, phosphosilicate glass or borophosphosilicate glass, or a composite material formed by randomly stacking at least two of the above materials, and the deposition method is chemical vapor deposition (CVD); the CVD includes low-pressure chemical vapor deposition (LPCVD), atmospheric pressure chemical vapor deposition (APCVD), sub-atmospheric pressure chemical vapor deposition (SACVD) or plasma-enhanced chemical vapor deposition (PECVD).

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