Capacitive pressure sensor

Abstract

The utility model discloses a capacitive pressure sensor which comprises a plurality of capacitive pressure sensor cells, each capacitive pressure sensor cell comprises a supporting structure, a detection capacitor, a reference capacitor and a supporting structure, the detection capacitor and the reference capacitor are located on the same substrate, and the supporting structure comprises a first supporting structure and a second supporting structure. The first support structure and the second support structure surround the detection capacitance and the reference capacitance. And the detection capacitor and the reference capacitor are formed on the same substrate, so that the process is simpler to implement. The reference capacitor and the detection capacitor form a differential capacitive pressure sensor, so that the sensitivity of the capacitive pressure sensor can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of semiconductor device manufacturing, and more particularly, to a capacitive pressure sensor. BACKGROUND

[0002] A capacitive pressure sensor is a sensor that measures pressure changes by detecting changes in capacitance. This sensor typically contains two parallel electrodes, one or both of which can be displaced by changes in external pressure, resulting in a change in capacitance value. There is a certain relationship between the change in capacitance value and the applied pressure, and through this relationship, the change in capacitance can be converted into a pressure value, thereby achieving accurate measurement of pressure.

[0003] Capacitive pressure sensors are mainly used in medical devices, industrial automation, automotive manufacturing, aerospace, environmental monitoring and other fields, especially in applications that require high precision and high reliability. For example, in medical devices, capacitive pressure sensors can be used to monitor physiological parameters such as blood pressure and respiration; in industrial automation, it can be used to detect changes in pressure within pipelines to ensure the safety and stability of the production process; in automotive manufacturing, such sensors can be used in tire pressure monitoring systems to improve driving safety; in the field of aerospace, capacitive pressure sensors can be used to measure the altitude and speed of aircraft; in environmental monitoring, it can be used to measure atmospheric pressure to help predict weather changes, etc.

[0004] Existing capacitive pressure sensors have some limitations in design, such as sensitivity decline caused by uneven stress distribution of the pressure-sensitive membrane, etc. These problems limit the application of capacitive pressure sensors in high-precision measurement fields. UTILITY MODEL CONTENT

[0005] Therefore, the present application provides a capacitive pressure sensor to solve the above problems.

[0006] According to an aspect of the present application, a capacitive pressure sensor is provided, comprising a plurality of capacitive pressure sensor cells, the capacitive pressure sensor cell comprising:

[0007] a support structure, a detection capacitor, and a reference capacitor, the support structure, the detection capacitor, and the reference capacitor being located on the same substrate,

[0008] the support structure comprising a first support structure and a second support structure, the first support structure and the second support structure surrounding the detection capacitor and the reference capacitor.

[0009] Optionally, further comprising:

[0010] a substrate;

[0011] an insulating layer on the substrate;

[0012] a stop layer on the insulating layer;

[0013] a first conductive layer including a first conductive region, the second conductive region, and the third conductive region;

[0014] a first corrosion-resistant layer on the second conductive region and at least part of the third conductive region;

[0015] a second conductive layer including a fourth conductive region, the fifth conductive region, and the sixth conductive region, the fifth conductive region and the sixth conductive region being separated from the second conductive region and the third conductive region respectively by the first corrosion-resistant layer;

[0016] a second corrosion-resistant layer on at least part of the sixth conductive region;

[0017] a third conductive layer including a seventh conductive region, an eighth conductive region, and a ninth conductive region, the seventh conductive region being movable, the seventh conductive region and the eighth conductive region being connected to each other, the seventh conductive region and the eighth conductive region being connected to the fourth conductive region and the fifth conductive region respectively by a plurality of interconnection structures, the eighth conductive region and the ninth conductive region being immovable, and the ninth conductive region being separated from the eighth conductive region;

[0018] wherein the second conductive region, the fifth conductive region, and the eighth conductive region constitute a reference capacitor, the first conductive region, the fourth conductive region, and the seventh conductive region constitute a detection capacitor, and the reference capacitor and the detection capacitor form a differential capacitive pressure sensor.

[0019] Optionally, the fourth conductive region is circular in shape, and the fifth conductive region is annular in shape and surrounds the fourth conductive region.

[0020] Optionally, the second conductive layer includes a sacrificial layer release channel, the sacrificial layer release channel including a plurality of arc-shaped openings extending along a circumferential direction of the circle and a plurality of straight-line openings extending along a radial direction of the circle.

[0021] Optionally, the plurality of arc-shaped openings and the plurality of straight-line openings of the sacrificial layer release channel are in communication with each other.

[0022] Optionally, the plurality of arc-shaped openings and the plurality of straight-line openings of the sacrificial layer release channel separate the fourth conductive region and the fifth conductive region from each other.

[0023] Optionally, the method further comprises:

[0024] a sealing layer above the third conductive layer, the sealing layer comprising an opening corresponding to the seventh conductive region of the third conductive layer, and a peripheral portion surrounding the opening,

[0025] wherein the opening of the sealing layer allows movement of the seventh conductive region along the vertical direction, and the peripheral portion of the sealing layer restricts movement of the eighth and ninth conductive regions along the vertical direction.

[0026] Optionally, further comprising:

[0027] a passivation layer above the sealing layer.

[0028] Optionally, the first corrosion-resistant layer between the second conductive region and the fifth conductive region is configured to restrict movement of the fifth conductive region along the vertical direction, and the first corrosion-resistant layer between the third conductive region and the sixth conductive region surrounds the first and second conductive regions to form a first gap between the first and second conductive layers.

[0029] Optionally, the first corrosion-resistant layer between the second conductive region and the fifth conductive region forms a gap between a lower plate of the reference capacitor and an upper plate of the reference capacitor.

[0030] Optionally, the second corrosion-resistant layer surrounds the fourth and fifth conductive regions to form a second gap between the second and third conductive layers.

[0031] Optionally, the seventh and eighth conductive regions of the third conductive layer are formed with a corrugated structure comprising a plurality of annular grooves on upper surfaces of the seventh and eighth conductive regions, and a plurality of annular flanges on lower surfaces of the seventh and eighth conductive regions corresponding to the grooves.

[0032] Optionally, at least a portion of the plurality of annular flanges of the seventh and eighth conductive regions extend to a surface of the second conductive layer to form the plurality of interconnection structures.

[0033] Optionally, the first and second conductive regions are spaced apart from each other and connected to respective conductive contacts via respective conductive channels.

[0034] Optionally, the seventh and eighth conductive regions are connected to respective conductive contacts.

[0035] Optionally, the fourth conductive region is displaced with deformation of the seventh conductive region.

[0036] Optionally, an area of the fourth conductive region is greater than an area of the seventh conductive region, and an area of the first conductive region is greater than an area of the seventh conductive region, so as to improve sensitivity of the capacitive pressure sensor.

[0037] Optionally, further comprising:

[0038] A third corrosion-resistant layer located on a lower surface of the second conductive layer, wherein a surface of the third corrosion-resistant layer located on a lower surface of the fourth conductive region of the second conductive layer has a plurality of convex point structures.

[0039] Optionally, further comprising:

[0040] A first sacrificial layer located between the first conductive layer and the second conductive layer, and at least part of the first sacrificial layer is removed to form a first gap between the first conductive layer and the second conductive layer.

[0041] A second sacrificial layer located between the second conductive layer and the third conductive layer, and at least part of the second sacrificial layer is removed to form a second gap between the second conductive layer and the third conductive layer.

[0042] Optionally, the third conductive region, the first sacrificial layer, the sixth conductive region, the second sacrificial layer, and the ninth conductive region are in contact and serve as the support structure.

[0043] Optionally, the capacitive pressure sensor cell is 2n, and n is a positive integer greater than or equal to 1.

[0044] Optionally, the 2n capacitive pressure sensor cells are arranged side by side.

[0045] Optionally, the capacitive pressure sensor comprises a first capacitive pressure sensor unit and a second capacitive pressure sensor unit, the first capacitive pressure sensor unit and the second capacitive pressure sensor unit form a Wheatstone bridge, the first capacitive pressure sensor unit comprises a detection capacitor of the first capacitive pressure sensor unit and a reference capacitor of the first capacitive pressure sensor unit, and the second capacitive pressure sensor unit comprises a detection capacitor of the second capacitive pressure sensor unit and a reference capacitor of the second capacitive pressure sensor unit.

[0046] The upper plate of the detection capacitor of the first capacitive pressure sensor unit is electrically connected to the upper plate of the reference capacitor of the first capacitive pressure sensor unit and forms a first terminal, the lower plate of the detection capacitor of the first capacitive pressure sensor unit is electrically connected to the lower plate of the reference capacitor of the second capacitive pressure sensor unit and forms a second terminal, the lower plate of the reference capacitor of the first capacitive pressure sensor unit is electrically connected to the lower plate of the detection capacitor of the second capacitive pressure sensor unit and forms a third terminal, and the upper plate of the detection capacitor of the second capacitive pressure sensor unit is electrically connected to the upper plate of the reference capacitor of the second capacitive pressure sensor unit and forms a fourth terminal.

[0047] The capacitive pressure sensor provided by the application has the advantages that the detection capacitor and the reference capacitor in the capacitive pressure sensor cell are formed on the same substrate, and the process is simple. Further, the support structure in the capacitive pressure sensor cell includes a first support structure and a second support structure, the first support structure and the second support structure surround the detection capacitor and the reference capacitor, the reference capacitor and the detection capacitor form a half-bridge or full-bridge differential structure, and the sensitivity of the capacitive pressure sensor can be improved.

[0048] Further, the fourth conductive region in the second conductive layer of the capacitive pressure sensor is circular. Further, the seventh conductive region of the third conductive layer is circular. The radial symmetry of the stress of the support structure can be maintained, and the reliability of the movable structure in the capacitive pressure sensor is improved. Further, at least the seventh conductive region in the third conductive layer forms a corrugated structure, the stress of the third conductive layer can be effectively reduced, and the sensitivity of the capacitive pressure sensor is further improved.

[0049] Further, the capacitive pressure sensor further includes a first corrosion-resistant layer between the first conductive layer and the second conductive layer, the first corrosion-resistant layer between the second conductive region and the fifth conductive region is used to limit the movement of the fifth conductive region along the vertical direction, to form a gap between the lower plate of the reference capacitor and the upper plate of the reference capacitor, and the first corrosion-resistant layer between the third conductive region and the sixth conductive region surrounds the first conductive region and the second conductive region, to form a first gap between the first conductive layer and the second conductive layer. That is, the first corrosion-resistant layer serves as both the support structure and the dielectric layer of the reference capacitor, and the integration of the capacitive pressure sensor is improved.

[0050] Further, the capacitive pressure sensor further includes a third corrosion-resistant layer on the lower surface of the second conductive layer, and the surface of the third corrosion-resistant layer on the lower surface of the fourth conductive region of the second conductive layer has a plurality of convex structures, to prevent the second conductive layer from adhering, and the reliability of the capacitive pressure sensor is improved.

[0051] Further, the area of the fourth conductive region of the second conductive layer of the capacitive pressure sensor is greater than the area of the seventh conductive region, and the area of the first conductive region of the first conductive layer is greater than the area of the seventh conductive region, so as to increase the area of the movable electrode plate of the detection capacitor and further improve the sensitivity of the capacitive pressure sensor.

[0052] Further, the first capacitive pressure sensor unit and the second capacitive pressure sensor unit constituting the Wheatstone bridge have similar structures, can be obtained at the same time in the manufacturing process without introducing other material layers, and manufacturing costs are saved. BRIEF DESCRIPTION OF DRAWINGS

[0053] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only related to some embodiments of the present disclosure, and not a limitation on the present disclosure.

[0054] Figure 1a A plan view of a second conductive layer in a capacitive pressure sensor of the first embodiment of the present application is shown.

[0055] Figure 1b Another plan view of a second conductive layer in a capacitive pressure sensor of the first embodiment of the present application is shown.

[0056] Figure 1c A cross-sectional view of a capacitive pressure sensor of the first embodiment of the present application is shown.

[0057] Figure 1d A plan view of a capacitive pressure sensor of the first embodiment of the present application is shown.

[0058] Figure 1e An equivalent circuit schematic diagram of a capacitive pressure sensor of the first embodiment of the present application is shown.

[0059] Figure 1f A structure schematic diagram of a third conductive layer in a capacitive pressure sensor of the first embodiment of the present application is shown.

[0060] Figures 2a to 2f Cross-sectional views of a capacitive pressure sensor of the first embodiment of the present application at various stages are shown.

[0061] Figure 3 A cross-sectional view of a capacitive pressure sensor of the second embodiment of the present application is shown.

[0062] Figure 4a A plan view of a second conductive layer in a capacitive pressure sensor of the third embodiment of the present application is shown.

[0063] Figure 4b A cross-sectional view of a capacitive pressure sensor according to the third embodiment of the present application is shown. DETAILED DESCRIPTION

[0064] The present application will be described in more detail with reference to the accompanying drawings. In the drawings, like reference numerals are used to indicate like elements. For the sake of clarity, not all parts of the apparatus are shown to scale. Furthermore, some constructions can not be shown to scale. For the sake of simplicity, a semiconductor device obtained after a number of steps can be described in one figure.

[0065] Many specific details of the present application are described below in order to provide a thorough understanding of the present application. However, as will be readily understood by one skilled in the art, the present application can be practiced without incorporating these specific details.

[0066] The present application can take form in various aspects of which the following descriptions are provided as example embodiments.

[0067] Figure 1a A plan view of a second conductive layer in a capacitive pressure sensor according to the first embodiment of the present application is shown. Figure 1b A plan view of another second conductive layer in a capacitive pressure sensor according to the first embodiment of the present application is shown. Figure 1c A cross-sectional view of a capacitive pressure sensor according to the first embodiment of the present application is shown. Figure 1d A plan view of a capacitive pressure sensor according to the first embodiment of the present application is shown. Figure 1e An equivalent circuit diagram of a capacitive pressure sensor according to the first embodiment of the present application is shown. Figure 1f A structural view of a third conductive layer in a capacitive pressure sensor according to the first embodiment of the present application is shown. In this view, Figure 1c For example, along Figure 1b The cross-sectional view of the dashed line.

[0068] The capacitive pressure sensor provided by the present application includes a plurality of capacitive pressure sensor cells. Further, the capacitive pressure sensor cells are 2n, where n is a positive integer greater than or equal to 1. Exemplarily, the 2n capacitive pressure sensor cells are arranged side by side.

[0069] As Figure 1dAs shown, the capacitive pressure sensor includes a first capacitive pressure sensor unit and a second capacitive pressure sensor unit, taking n = 1 as an example. Exemplarily, one capacitive pressure sensor cell is included in each of the first capacitive pressure sensor unit and the second capacitive pressure sensor unit. The first capacitive pressure sensor unit includes a detection capacitor Cm-1 of the first capacitive pressure sensor unit and a reference capacitor Cref-1 of the first capacitive pressure sensor unit, and the second capacitive pressure sensor unit includes a detection capacitor Cm-2 of the second capacitive pressure sensor unit and a reference capacitor Cref-2 of the second capacitive pressure sensor unit.

[0070] As shown, Figure 1e The first capacitive pressure sensor unit and the second capacitive pressure sensor unit in the capacitive pressure sensor form a Wheatstone bridge to obtain a differential capacitive pressure sensor, which can improve the sensitivity of the capacitive pressure sensor.

[0071] The upper plate of the detection capacitor Cm-1 of the first capacitive pressure sensor unit is electrically connected to the upper plate of the reference capacitor Cref-1 of the first capacitive pressure sensor unit and forms a first terminal D, the lower plate of the detection capacitor Cm-1 of the first capacitive pressure sensor unit is electrically connected to the lower plate of the reference capacitor Cref-2 of the second capacitive pressure sensor unit and forms a second terminal E, the lower plate of the reference capacitor Cref-1 of the first capacitive pressure sensor unit is electrically connected to the lower plate of the detection capacitor Cm-2 of the second capacitive pressure sensor unit and forms a third terminal C, and the upper plate of the detection capacitor Cm-2 of the second capacitive pressure sensor unit is electrically connected to the upper plate of the reference capacitor Cref-2 of the second capacitive pressure sensor unit and forms a fourth terminal F.

[0072] As shown, Figure 1c The capacitive pressure sensor cell in the capacitive pressure sensor 100 includes a support structure, a detection capacitor and a reference capacitor on the same substrate 101. The support structure includes a first support structure 151 and a second support structure 152, and the first support structure 151 and the second support structure 152 surround the detection capacitor and the reference capacitor.

[0073] Furthermore, the capacitive pressure sensor cell also includes: a substrate 101; an insulating layer 102 located on the substrate 101; a stop layer 103 located on the insulating layer 102; a first conductive layer 104, the first conductive layer including mutually independent first conductive regions 104a, second conductive regions 104b, and third conductive regions 104c; a first corrosion-resistant layer 121 located on the second conductive region 104b and at least a portion of the third conductive region 104c; and a second conductive layer 106, including mutually independent fourth conductive regions 106a, fifth conductive regions 106b, and sixth conductive regions 106c, the fifth conductive regions 106b and sixth conductive regions 106c being respectively connected to the second conductive region 106a through the first corrosion-resistant layer 121. Electrical region 104b and third conductive region 104c are separated from each other; a second corrosion-resistant layer 131 is located on at least a portion of the sixth conductive region 106c; a third conductive layer 109 includes a seventh conductive region 109a, an eighth conductive region 109b and a ninth conductive region 109c, the seventh conductive region 109a is movable, the seventh conductive region 109a and the eighth conductive region 109b are interconnected, the seventh conductive region 109a and the eighth conductive region 109b are interconnected with the fourth conductive region 106a and the fifth conductive region 106b respectively through multiple interconnection structures, the eighth conductive region 109b and the ninth conductive region 109c are immovable, and the ninth conductive region 109c and the eighth conductive region 109b are separated. The second conductive region 104b, the fifth conductive region 106b, and the eighth conductive region 109b constitute a reference capacitor, and the first conductive region 104a, the fourth conductive region 106a, and the seventh conductive region 109a constitute a detection capacitor. The reference capacitor and the detection capacitor together form a differential capacitive pressure sensor.

[0074] Furthermore, the fourth conductive region 106a of the second conductive layer 106 is circular in shape, and the fifth conductive region 106b is annular around the fourth conductive region 106a. Furthermore, the seventh conductive region 109a of the third conductive layer 109 is circular in shape. In other embodiments, the eighth conductive layer 109b of the third conductive layer 109 is annular around the seventh conductive region 109a.

[0075] Furthermore, combined Figure 1a , Figure 1b As shown, the second conductive layer 106 includes a sacrificial layer release channel 141, which includes a plurality of arc-shaped openings extending in a circular circumferential direction and a plurality of straight openings extending in a circular radial direction. Further, the plurality of arc-shaped openings and the plurality of straight openings of the sacrificial layer release channel 141 are interconnected. Further, the plurality of arc-shaped openings and the plurality of straight openings of the sacrificial layer release channel 141 separate the fourth conductive region 106a and the fifth conductive region 106b from each other.

[0076] Further, the ninth conductive region 109c includes a release hole 142. The capacitive pressure sensor further includes a sealing layer 110 above the third conductive layer 109 to seal the release hole 142. The sealing layer 110 includes an opening 161 corresponding to the seventh conductive region 109a of the third conductive layer 109, and a peripheral portion surrounding the opening 161. Wherein, the opening 161 of the sealing layer 110 allows the movement of the seventh conductive region 109a along the vertical direction, and the peripheral portion of the sealing layer 110 limits the movement of the eighth conductive region 109b and the ninth conductive region 109c along the vertical direction.

[0077] Further, the capacitive pressure sensor further includes a passivation layer 111 above the sealing layer 110.

[0078] Further, the first corrosion-resistant layer 121b between the second conductive region 104b and the fifth conductive region 106b is used to limit the movement of the fifth conductive region 106b along the vertical direction, and the first corrosion-resistant layer 121a between the third conductive region 104c and the sixth conductive region 106c surrounds the first conductive region 104a and the second conductive region 104b to form a first gap 171 between the first conductive layer 104 and the second conductive layer 106.

[0079] Further, the first corrosion-resistant layer 121b between the second conductive region 104b and the fifth conductive region 106b forms a gap between the lower plate of the reference capacitor and the upper plate of the reference capacitor.

[0080] Further, the second corrosion-resistant layer 131 surrounds the fourth conductive region 106a and the fifth conductive region 104b to form a second gap 172 between the second conductive layer 104 and the third conductive layer 106.

[0081] Further, in combination with Figure 1f As shown, at least the seventh conductive region 109a and the eighth conductive region 109b in the third conductive layer 109 are formed with a corrugated structure. The corrugated structure includes a plurality of annular grooves 109d on the upper surface of the seventh conductive region 109a and the eighth conductive region 109b, and a plurality of annular flanges 109e on the lower surface of the seventh conductive region 109a and the eighth conductive region 109b corresponding to the grooves 109d.

[0082] Further, at least part of the plurality of annular flanges 109e of the seventh conductive region 109a and the eighth conductive region 109b extend to the surface of the second conductive layer 106 to form a plurality of interconnection structures.

[0083] Further, the first conductive region 104a and the second conductive region 104b are separated from each other and connected to the corresponding conductive contact C / E via the corresponding conductive channel 124.

[0084] Further, the seventh conductive region 109a and the eighth conductive region 109b are connected to the corresponding conductive contact D / F.

[0085] Further, the fourth conductive region 106a is displaced with the deformation of the seventh conductive region 109a.

[0086] Further, the capacitive pressure sensor further comprises a first sacrificial layer 105 and a second sacrificial layer 106. At least part of the first sacrificial layer 105 between the first conductive layer 104 and the second conductive layer 106 is removed to form a first gap 171 between the first conductive layer 104 and the second conductive layer 106. At least part of the second sacrificial layer 107 between the second conductive layer 106 and the third conductive layer 109 is removed to form a second gap 172 between the second conductive layer 106 and the third conductive layer 109.

[0087] Further, the third conductive region 104c, the first sacrificial layer 105, the sixth conductive region 106c, the second sacrificial layer 107, and the ninth conductive region 109c are in contact and serve as a support structure.

[0088] Figures 2a to 2f The cross-sectional schematic diagrams of a capacitive pressure sensor according to the first embodiment of the present application are shown at different stages.

[0089] Figures 2a to 2f The cross-sectional schematic diagrams of a capacitive pressure sensor according to the first embodiment of the present application are shown at different stages. Figure 1c The cross-sectional schematic diagrams of a capacitive pressure sensor according to the first embodiment of the present application are shown at different stages. It can be understood that the manufacturing method of the capacitive pressure sensor cell and the structure connecting adjacent cells provided by other embodiments of the present application are also applicable to the above manufacturing method.

[0090] As shown in FIG. 1, an isolation layer and a first conductive layer 101 are formed on a substrate 101. Figure 2a

[0091] Further, the substrate 101 comprises a first surface and a second surface opposite to each other. The isolation layer and the first conductive layer 104 are sequentially formed on the first surface of the substrate 101, and the isolation layer electrically isolates the first conductive layer 104 from the substrate 101. Exemplarily, the isolation layer comprises an insulating layer 102 on the first surface of the substrate 101 and a stop layer 103 on the surface of the insulating layer. The first conductive layer 104 is located on the surface of the stop layer 103. The first conductive layer 104 comprises a first conductive region 104a, a second conductive region 104b, and a third conductive region 104c which are independent of each other.

[0092] ​For example, in the crystal orientation is <100> An insulating layer 102 is formed on a substrate 101, for example, by thermal oxidation, low-pressure chemical vapor deposition (LPCVD), or plasma-enhanced chemical vapor deposition (PECVD). The substrate 101 is, for example, a silicon substrate. The insulating layer 102 is, for example, a silicon dioxide layer, to electrically isolate the subsequently formed first conductive layer 104 from the substrate 101. The thickness of the insulating layer 102 is 0.5 μm to 3 μm. Next, a stop layer 103 is formed on the surface of the insulating layer 102, for example, by low-pressure chemical vapor deposition (LPCVD) or plasma-enhanced chemical vapor deposition (PECVD). The stop layer 103 is, for example, a silicon nitride layer, a silicon-rich silicon nitride layer, or an aluminum oxide layer, to serve as a stop layer for the release of the sacrificial layer in a subsequent capacitive pressure sensor. Next, a conductive material layer is deposited on the surface of the stop layer 103, and the conductive material layer is photolithographically and etched to form a first conductive layer 104 including a first conductive region 104a, a second conductive region 104b, and a third conductive region 104c that are independent of each other. The first conductive layer 104 is, for example, a doped polysilicon layer.

[0093] like Figure 2b As shown, a patterned first sacrificial layer 105 is formed on the surface of the first conductive layer 104 and the exposed stop layer 103, and a first corrosion-resistant layer 121 is formed on the second conductive region 104b and at least a portion of the third conductive region 104c.

[0094] For example, a silicon dioxide layer is deposited on the surface of the first conductive layer 104, for example, by low-pressure chemical vapor deposition (LPCVD) or plasma-enhanced chemical vapor deposition (PECVD), and the silicon dioxide layer is photolithographically etched to form a first sacrificial layer 105. The first sacrificial layer 105 includes a first via 133 reaching the surface of the first conductive layer 104. Then, silicon nitride or silicon-rich silicon nitride is filled in the first via 133 located on the second conductive region 104b and at least a portion of the third conductive region 104c using low-pressure chemical vapor deposition (LPCVD) or plasma-enhanced chemical vapor deposition (PECVD), and a first corrosion-resistant layer 121 is formed using CMP, photolithography, and etching processes. Furthermore, the first corrosion-resistant layer 121b located between the second conductive region 104b and the fifth conductive region 106b is used to restrict the movement of the fifth conductive region 106b in the vertical direction, and the first corrosion-resistant layer 121a located between the third conductive region 104c and the sixth conductive region 106c surrounds the first conductive region 104a and the second conductive region 104b to form a first gap 171 between the first conductive layer 104 and the second conductive layer 106. The unfilled first through-hole 133 located on the third conductive region 104c is used to form a conductive channel in the future.

[0095] like Figure 2cAs shown, the second conductive layer 106 is formed to include the fourth conductive region 106a, the fifth conductive region 106b, and the sixth conductive region 106c which are independent from each other.

[0096] Further, in combination with Figure 1a , Figure 1b As shown, the second conductive layer 106 includes a sacrificial layer release channel 141, which includes a plurality of arc-shaped openings extending along the circumferential direction of the circle and a plurality of straight-line openings extending along the radial direction of the circle. Further, the plurality of arc-shaped openings and the plurality of straight-line openings of the sacrificial layer release channel 141 are in communication with each other. Further, the plurality of arc-shaped openings and the plurality of straight-line openings of the sacrificial layer release channel 141 separate the fourth conductive region 106a and the fifth conductive region 106b from each other.

[0097] Exemplarily, a layer of doped polysilicon is deposited on the surface of the first sacrificial layer 105 and the first corrosion-resistant layer 121 by a low-pressure chemical vapor deposition (LPCVD) or epitaxy method, and the thickness of the polysilicon is generally 1.0um~3.0um. Then, the second conductive layer 106 including the fourth conductive region 106a, the fifth conductive region 106b, the sixth conductive region 106c, and the connection structure 127 of the conductive channel to be formed later is formed by a photolithography and etching process, and the second via hole 128 is formed on the second conductive layer 106 by a photolithography and etching process to divide the second conductive layer 106 into a grid shape and separate part of the second conductive layer 106 into a plurality of block-shaped conductive layers 129.

[0098] As shown, the patterned second sacrificial layer 107 is formed on the second conductive layer 106. Figure 2d

[0099] Exemplarily, a layer of silicon dioxide is formed on the surface of the second conductive layer 106 and in the second via hole 128 by a low-pressure chemical vapor deposition (LPCVD) or plasma-enhanced chemical vapor deposition (PECVD) method to form the second sacrificial layer 107. The second via hole 128 is filled with the silicon dioxide layer to form the sacrificial layer release channel 141, and part of the sacrificial layer release channel 141 serves as a passage for the etching liquid or gas when the sacrificial layer is released. Then, the third via hole 137 reaching the surface of the second conductive layer 106 is formed in the second sacrificial layer 107 by a photolithography and etching process.

[0100] As shown, the second corrosion-resistant layer 131 is formed. Figure 2e

[0101] ​​Exemplarily, the isotropic etching gas is used to hollow the bulk conductive layer 129 through the third via hole 137 to form the cavity 135. Then, the second sacrificial layer 107 is thickened by low pressure chemical vapor deposition (LPCVD) or plasma enhanced chemical vapor deposition (PECVD), and the thickness of the thickened second sacrificial layer 107 is 1.0 μm~4.0 μm. Then, the second sacrificial layer 107 is subjected to photoetching and etching to form the fourth via hole 139 and the fifth via hole 138 reaching the connecting structure 127 and the sixth via hole for forming the corrugated structure later. Then, the corrosion-resistant material is filled in the sixth via hole to form the second corrosion-resistant layer 131 on at least part of the sixth conductive region 106c. The second corrosion-resistant layer 131 surrounds the fourth conductive region 106a and the fifth conductive region 104b to form the second gap 172 between the second conductive layer 104 and the third conductive layer 106.

[0102] As shown in Figure 2f , the third conductive layer 109 is formed. The third conductive layer 109 comprises a seventh conductive region 109a, an eighth conductive region 109b and a ninth conductive region 109c, the seventh conductive region 109a is movable, the seventh conductive region 109a and the eighth conductive region 109b are connected to each other, the seventh conductive region 109a and the eighth conductive region 109b are connected to the fourth conductive region 106a and the fifth conductive region 106b respectively through a plurality of interconnection structures, the eighth conductive region 109b and the ninth conductive region 109c are immovable, and the ninth conductive region 109c is separated from the eighth conductive region 109b.

[0103] Further, the releasing hole 142 is formed in the ninth conductive region 109c.

[0104] Exemplarily, the third conductive layer 109 is formed by depositing a layer of doped polysilicon on the surface of the second sacrificial layer 107 and the second corrosion-resistant layer 131 and in the fourth via hole 139 by low pressure chemical vapor deposition (LPCVD) or epitaxy. The fifth via hole 138 is filled with doped polysilicon to form the conductive channel 124. The releasing hole 142 is formed in the ninth conductive region 109c by photoetching and etching process. The thickness of the polysilicon is generally 1.0 μm~3.0 μm. Further, the second conductive region 104b, the fifth conductive region 106b and the eighth conductive region 109b constitute a reference capacitor, the first conductive region 104a, the fourth conductive region 106a and the seventh conductive region 109a constitute a detection capacitor, and the reference capacitor and the detection capacitor form a differential capacitive pressure sensor.

[0105] Further, in combination with Figure 1fAs shown, at least the seventh conductive region 109a and the eighth conductive region 109b of the third conductive layer 109 are formed with a corrugated structure. The corrugated structure includes a plurality of annular grooves 109d on the top surface of the seventh conductive region 109a and the eighth conductive region 109b, and a plurality of annular ridges 109e on the bottom surface of the seventh conductive region 109a and the eighth conductive region 109b corresponding to the grooves 109d.

[0106] Further, at least a portion of the plurality of annular ridges 109e of the seventh conductive region 109a and the eighth conductive region 109b extend to the surface of the second conductive layer 106 to form a plurality of interconnection structures.

[0107] Further, the first conductive region 104a and the second conductive region 104b are separated from each other, and are connected to the corresponding conductive contacts C / E via the corresponding conductive channels 124.

[0108] Then, at least a portion of the second sacrificial layer 107 and the first sacrificial layer 105 are removed by using a selective wet etching HF acid or BOE solution / gas through the release holes 142 to form a first gap 171 between the first conductive layer 104 and the second conductive layer 106, and a second gap 172 between the second conductive layer 104 and the third conductive layer 106.

[0109] Further, the third conductive region 104c, the first sacrificial layer 105, the sixth conductive region 106c, the second sacrificial layer 107, and the ninth conductive region 109c are in contact and serve as a support structure. The support structure includes a first support structure 151 and a second support structure 152.

[0110] Then, as shown in FIG. 1G, a sealing layer 110 is formed on the surface of the third conductive layer 109 to seal the release holes 142. Figure 1c

[0111] Further, the sealing layer 110 includes an opening 161 corresponding to the seventh conductive region 109a of the third conductive layer, and a peripheral portion surrounding the opening 161. The opening 161 of the sealing layer 110 allows the seventh conductive region 109a to move along the vertical direction, and the peripheral portion of the sealing layer 110 limits the movement of the eighth conductive region 109b and the ninth conductive region 109c along the vertical direction.

[0112] Further, a passivation layer 111 is also formed above the sealing layer 110.

[0113] ​Then, the sealing layer 110 is subjected to photoetching and etching to form a lead hole, and then a metal layer is deposited by sputtering or evaporation and subjected to photoetching to form a conductive contact. The conductive contact can be Au or Al, or an alloy such as Cr+Au or Ti+Pt+Au, or a metal such as pure Al, Al-Si (1%), or Ti+TiN+Al-Si, and the thickness of the conductive contact is generally 0.5 μm to 2 μm.

[0114] Then, a passivation layer 111 is formed by a plasma enhanced chemical vapor deposition (PECVD) method and patterning, and the passivation layer 111 can be silicon nitride or silicon-rich silicon nitride or aluminum oxide. The passivation layer 111 is located on the sealing layer 110 and exposes the conductive contact.

[0115] Figure 3 A cross-sectional view of a capacitive pressure sensor according to a third embodiment of the present application is shown.

[0116] As shown in Figure 3 , the capacitive pressure sensor according to the third embodiment further includes a third corrosion-resistant layer 601 located on the lower surface of the second conductive layer 106.

[0117] Further, the surface of the third corrosion-resistant layer 601 located on the lower surface of the fourth conductive region 106a of the second conductive layer 106 has a plurality of convex structures 602.

[0118] The capacitive pressure sensor further includes a third corrosion-resistant layer located on the lower surface of the second conductive layer, and the surface of the third corrosion-resistant layer located on the lower surface of the fourth conductive region of the second conductive layer has a plurality of convex structures, which can prevent the second conductive layer from adhering and improve the reliability of the capacitive pressure sensor.

[0119] Figure 4a A plan view of a second conductive layer in a capacitive pressure sensor according to a third embodiment of the present application is shown. Figure 4b A cross-sectional view of a capacitive pressure sensor according to the third embodiment of the present application is shown.

[0120] As shown in Figure 4a , Figure 4b , the fourth conductive region 106a of the second conductive layer in the capacitive pressure sensor according to the third embodiment is circular, and the fifth conductive region 106b is located in the fourth conductive region 106a and is annular.

[0121] Correspondingly, in the present embodiment, the area of the fourth conductive region 106a is greater than the area of the seventh conductive region 109a, and the area of the first conductive region 104a is greater than the area of the seventh conductive region 109a.

[0122] Further, the area of the fourth conductive region of the second conductive layer of the capacitive pressure sensor is larger than the area of the seventh conductive region, and the area of the first conductive region of the first conductive layer is larger than the area of the seventh conductive region, so as to increase the area of the movable electrode plate of the detection capacitor and further improve the sensitivity of the capacitive pressure sensor.

[0123] The capacitive pressure sensor provided by the application has the advantages that the detection capacitor and the reference capacitor in the capacitive pressure sensor cell are formed on the same substrate, and the process is simpler. Further, the support structure in the capacitive pressure sensor cell includes a first support structure and a second support structure, the first support structure and the second support structure surround the detection capacitor and the reference capacitor, the reference capacitor and the detection capacitor form a half-bridge or full-bridge differential structure, and the sensitivity of the capacitive pressure sensor can be improved.

[0124] Further, the fourth conductive region of the second conductive layer of the capacitive pressure sensor is circular. Further, the seventh conductive region of the third conductive layer is circular. The radial symmetry of the stress of the support structure can be maintained, and the reliability of the movable structure in the capacitive pressure sensor is further improved. Further, at least the seventh conductive region of the third conductive layer forms a corrugated structure, the stress of the third conductive layer can be effectively reduced, and the sensitivity of the capacitive pressure sensor is further improved.

[0125] Further, the capacitive pressure sensor further includes a first corrosion-resistant layer between the first conductive layer and the second conductive layer. The first corrosion-resistant layer between the second conductive region and the fifth conductive region is used to limit the movement of the fifth conductive region along the vertical direction, so as to form a gap between the lower electrode plate of the reference capacitor and the upper electrode plate of the reference capacitor. The first corrosion-resistant layer between the third conductive region and the sixth conductive region surrounds the first conductive region and the second conductive region, so as to form a first gap between the first conductive layer and the second conductive layer. That is, the first corrosion-resistant layer serves as both the support structure and the dielectric layer of the reference capacitor, and the integration of the capacitive pressure sensor is improved.

[0126] Further, the capacitive pressure sensor provided by the application includes a first capacitive pressure sensor unit and a second capacitive pressure sensor unit, which form a Wheatstone bridge. The first capacitive pressure sensor unit and the second capacitive pressure sensor unit have similar structures, can be obtained at the same time in the manufacturing process without introducing other material layers, and the manufacturing cost is saved.

[0127] In the above description, the patterning, etching and other technical details of each layer are not described in detail. However, those skilled in the art should understand that the layers, regions and the like with the required shape can be formed by various technical means. In addition, those skilled in the art can also design methods that are not exactly the same as the methods described above in order to form the same structure. In addition, although each embodiment is described above, this does not mean that the measures in each embodiment cannot be used advantageously in combination.

[0128] The embodiments of the application described above are intended to be illustrative only. The application is not limited in its scope to the embodiments of the application described herein. The scope of the application is defined by the claims and equivalents thereof. Various alternatives and modifications to the embodiments of the application described herein will be apparent to those skilled in the art in view of the foregoing description. It is intended that the application encompass all such alternatives, modifications and variations as falling within the scope of the claims.

Claims

1. A capacitive pressure sensor, characterized in that, It includes a plurality of capacitive pressure sensor cells, wherein the capacitive pressure sensor cells include: The system includes a support structure, a detection capacitor, and a reference capacitor, all located on the same substrate. The support structure includes a first support structure and a second support structure, which surround the detection capacitor and the reference capacitor.

2. The capacitive pressure sensor according to claim 1, characterized in that, Also includes: Substrate; An insulating layer located on the substrate; A stop layer, the stop layer being located on the insulating layer; A first conductive layer, comprising a first conductive region, a second conductive region, and a third conductive region that are independent of each other; A first corrosion-resistant layer is located on the second conductive region and at least a portion of the third conductive region; The second conductive layer includes a fourth conductive region, a fifth conductive region, and a sixth conductive region that are independent of each other. The fifth conductive region and the sixth conductive region are separated from the second conductive region and the third conductive region by a first corrosion-resistant layer, respectively. A second corrosion-resistant layer is located on at least a portion of the sixth conductive region; The third conductive layer includes a seventh conductive region, an eighth conductive region, and a ninth conductive region. The seventh conductive region is movable, and the seventh and eighth conductive regions are interconnected. The seventh and eighth conductive regions are interconnected with the fourth and fifth conductive regions respectively through multiple interconnection structures. The eighth and ninth conductive regions are immovable and are separated from the eighth conductive region. The second conductive region, the fifth conductive region, and the eighth conductive region constitute a reference capacitor, and the first conductive region, the fourth conductive region, and the seventh conductive region constitute a detection capacitor. The reference capacitor and the detection capacitor together form a differential capacitive pressure sensor.

3. The capacitive pressure sensor according to claim 2, characterized in that, The fourth conductive region is circular in shape, and the fifth conductive region is annular around the fourth conductive region.

4. The capacitive pressure sensor according to claim 3, characterized in that, The second conductive layer includes a sacrificial layer release channel, which includes a plurality of arc-shaped openings extending in the circumferential direction of the circle and a plurality of straight openings extending in the radial direction of the circle.

5. The capacitive pressure sensor according to claim 4, characterized in that, The plurality of arc-shaped openings and the plurality of straight openings of the sacrificial layer release channel are interconnected.

6. The capacitive pressure sensor according to claim 4, characterized in that, The plurality of arc-shaped openings and the plurality of straight openings of the sacrificial layer release channel separate the fourth conductive region and the fifth conductive region from each other.

7. The capacitive pressure sensor according to claim 2, characterized in that, Also includes: A sealing layer located above the third conductive layer, the sealing layer including an opening corresponding to the seventh conductive region of the third conductive layer, and a peripheral portion surrounding the opening. The opening in the sealing layer allows the seventh conductive region to move in the vertical direction, while the peripheral portion of the sealing layer restricts the movement of the eighth and ninth conductive regions in the vertical direction.

8. The capacitive pressure sensor according to claim 7, characterized in that, Also includes: A passivation layer located above the sealing layer.

9. The capacitive pressure sensor according to claim 2, characterized in that, The first corrosion-resistant layer located between the second conductive region and the fifth conductive region is used to restrict the movement of the fifth conductive region in the vertical direction. The first corrosion-resistant layer located between the third conductive region and the sixth conductive region surrounds the first conductive region and the second conductive region to form a first gap between the first conductive layer and the second conductive layer.

10. The capacitive pressure sensor according to claim 9, characterized in that, The first corrosion-resistant layer located between the second conductive region and the fifth conductive region forms the gap between the lower electrode and the upper electrode of the reference capacitor.

11. The capacitive pressure sensor according to claim 2, characterized in that, The second corrosion-resistant layer surrounds the fourth conductive region and the fifth conductive region to form a second gap between the second conductive layer and the third conductive layer.

12. The capacitive pressure sensor according to claim 2, characterized in that, The seventh and eighth conductive regions of the third conductive layer are formed with a pleated structure, which includes a plurality of annular grooves on the upper surface of the seventh and eighth conductive regions and a plurality of annular flanges on the lower surface of the seventh and eighth conductive regions corresponding to the grooves.

13. The capacitive pressure sensor according to claim 12, characterized in that, At least a portion of the plurality of annular flanges of the seventh and eighth conductive regions extends to the surface of the second conductive layer to form the plurality of interconnect structures.

14. The capacitive pressure sensor according to claim 2, characterized in that, The first conductive region and the second conductive region are separated from each other and connected to the corresponding conductive contacts via corresponding conductive channels.

15. The capacitive pressure sensor according to claim 2, characterized in that, The seventh and eighth conductive regions are connected to the corresponding conductive contacts.

16. The capacitive pressure sensor according to claim 2, characterized in that, The fourth conductive region is displaced as the seventh conductive region deforms.

17. The capacitive pressure sensor according to claim 2, characterized in that, The area of ​​the fourth conductive region is larger than the area of ​​the seventh conductive region, and the area of ​​the first conductive region is larger than the area of ​​the seventh conductive region, so as to improve the sensitivity of the capacitive pressure sensor.

18. The capacitive pressure sensor according to claim 2, characterized in that, Also includes: A third corrosion-resistant layer is located on the lower surface of the second conductive layer, wherein the surface of the third corrosion-resistant layer located on the lower surface of the fourth conductive region of the second conductive layer has a plurality of bump structures.

19. The capacitive pressure sensor according to claim 2, characterized in that, Also includes: A first sacrificial layer is located between the first conductive layer and the second conductive layer, and at least a portion of the first sacrificial layer is removed to form a first gap between the first conductive layer and the second conductive layer; A second sacrificial layer is located between the second conductive layer and the third conductive layer, and at least a portion of the second sacrificial layer is removed to form a second gap between the second conductive layer and the third conductive layer.

20. The capacitive pressure sensor according to claim 19, characterized in that, The third conductive region, the first sacrificial layer, the sixth conductive region, the second sacrificial layer, and the ninth conductive region are in contact and serve as the supporting structure.

21. The capacitive pressure sensor according to any one of claims 1-20, characterized in that, The capacitive pressure sensor has 2n cells, where n is a positive integer greater than or equal to 1.

22. The capacitive pressure sensor according to claim 21, characterized in that, The 2n capacitive pressure sensor cells are arranged side by side.

23. The capacitive pressure sensor according to claim 21, characterized in that, The capacitive pressure sensor includes a first capacitive pressure sensor unit and a second capacitive pressure sensor unit, which form a Wheatstone bridge. The first capacitive pressure sensor unit includes a detection capacitor and a reference capacitor, and the second capacitive pressure sensor unit includes a detection capacitor and a reference capacitor. The upper plate of the detection capacitor of the first capacitive pressure sensor unit is electrically connected to the upper plate of the reference capacitor of the first capacitive pressure sensor unit to form a first terminal. The lower plate of the detection capacitor of the first capacitive pressure sensor unit is electrically connected to the lower plate of the reference capacitor of the second capacitive pressure sensor unit to form a second terminal. The lower plate of the reference capacitor of the first capacitive pressure sensor unit is electrically connected to the lower plate of the detection capacitor of the second capacitive pressure sensor unit to form a third terminal. The upper plate of the detection capacitor of the second capacitive pressure sensor unit is electrically connected to the upper plate of the reference capacitor of the second capacitive pressure sensor unit to form a fourth terminal.

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