Pressure sensor structure, pressure sensor device, and manufacturing method of pressure sensor structure

Abstract

This invention relates to a pressure sensor structure that detects changes in electrostatic capacitance between electrodes. The pressure sensor structure (1) comprises: a sensor body including a diaphragm plate (40) that functions as a sensing electrode, a base electrode (22) opposite to the diaphragm plate (40), and a sidewall layer (30) maintaining a gap (G) between the diaphragm plate (40) and the base electrode (22); and a conductive protective substrate (10) for supporting the sensor body. The sidewall layer (30) includes a protective electrode layer (32) and an upper protective insulating layer (31) and a lower protective insulating layer (33) that electrically insulate the protective electrode layer (32). An electrically insulating layer (21) that electrically insulates the protective substrate (10) is provided between the protective substrate (10) and the sensor body. The protective substrate (10) is electrically connected to the protective electrode layer (32) and functions as a protective electrode together with the protective electrode layer (32). With this structure, interference can be suppressed, and high-precision pressure measurement can be performed.

Description

Technical Field

[0001] This invention relates to a pressure sensor structure for measuring pressures such as air pressure and water pressure, and a pressure sensor device employing the same structure. Furthermore, this invention relates to a method for manufacturing the pressure sensor structure. Background Technology

[0002] Pressure sensors can be manufactured using MEMS (Micro-Electro-Mechanical Systems) technology, which applies semiconductor manufacturing techniques, enabling the creation of ultra-miniature sensors ranging from approximately 0.5 mm to 2 mm square. A typical pressure sensor has a capacitive structure with two electrodes, allowing pressure measurement by detecting changes in electrostatic capacitance caused by variations in ambient pressure.

[0003] Figure 9 (A) is a cross-sectional view showing an example of a conventional pressure sensor construction. Figure 9 (B) is its top view. This pressure sensor structure, as disclosed in Patent Document 1, comprises a diaphragm plate 87 acting as a sensing electrode, a base electrode 86 opposite to the diaphragm plate 87, and a sidewall layer 85. The sidewall layer 85 includes a protective electrode layer 83 and electrically insulating layers 82 and 84 disposed vertically. The base substrate 81 is formed of a conductive material and is conductive to the base electrode 86. The protective electrode layer 83 and the base electrode 86 are formed in the same layer, sandwiched between the upper diaphragm plate 87 and the lower base substrate 81, forming a three-layer electrode structure. This eliminates parasitic electrostatic capacitance independent of pressure changes.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: International Publication No. 2015 / 107453 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] Such a pressure sensor is constructed by forming many chips on a semiconductor wafer using MEMS technology and then cutting them into individual chips (monolithography). The resulting chips are fixed to a circuit board 90 using adhesive 91 (chip bonding) and housed together with an integrated circuit for signal processing in a housing, thereby completing the pressure sensor device.

[0009] In this case, although the back side of the substrate 81 is in close contact with the circuit board 90, the end face of the substrate 81 is exposed. Since the surrounding environment of the pressure sensor is open to the atmosphere, there is a possibility that liquids such as water Q may adhere to the end face of the substrate 81 due to condensation, immersion, etc. Sometimes, such liquid Q can bridge the diaphragm plate 87 and the substrate 81, causing changes in parasitic capacitance and resulting in a shift in the pressure output value. Furthermore, the diaphragm plate 87 and the base electrode 86 may sometimes be affected by external electromagnetic noise, causing a shift in the pressure output value.

[0010] The object of this invention is to provide a pressure sensor structure capable of suppressing the effects of interference and enabling high-precision pressure measurement, and a pressure sensor device employing this pressure sensor structure. A further object of this invention is to provide a method for manufacturing a pressure sensor structure capable of suppressing the effects of interference and enabling high-precision pressure measurement.

[0011] Solution for solving the problem

[0012] One technical solution of the present invention is a pressure sensor structure for detecting changes in electrostatic capacitance between electrodes. The pressure sensor structure comprises: a sensor body including a diaphragm plate that functions as a sensing electrode, a base electrode opposite the diaphragm plate, and a sidewall layer maintaining a gap between the diaphragm plate and the base electrode; and a conductive protective substrate for supporting the sensor body. The sidewall layer includes a protective electrode layer and an upper protective insulating layer and a lower protective insulating layer that electrically insulate the protective electrode layer. The protective substrate is electrically connected to the protective electrode layer and functions as a protective electrode together with the protective electrode layer.

[0013] Another pressure sensor device according to the present invention includes: the pressure sensor structure described above; an integrated circuit that processes signals from the pressure sensor structure; a circuit board on which the integrated circuit and the pressure sensor structure are mounted; and a housing member made of metal or synthetic resin that, together with the circuit board, houses the integrated circuit and the pressure sensor structure.

[0014] Another technical solution of the present invention is a method for manufacturing a pressure sensor structure for detecting changes in electrostatic capacitance between electrodes. The manufacturing method includes the following steps: a) forming a lower substrate including a base electrode; b) forming an upper substrate including a diaphragm plate that functions as a sensing electrode; c) bonding the lower substrate and the upper substrate; d) shaping the lower substrate and the upper substrate into a stepped shape; and e) forming a passivation film on the outer surfaces of the shaped lower substrate and the upper substrate. Step a) of forming the lower substrate includes the following steps: a1) sequentially forming a lower protective electrical insulating layer and a conductive layer on a conductive lower substrate; and a2) etching the conductive layer to form a base electrode and a protective electrode layer. Step b) of forming the upper substrate includes the following steps: b1) forming an electrical insulating layer on a conductive upper substrate; and b2) etching the electrical insulating layer to form an upper protective electrical insulating layer.

[0015] The effects of the invention

[0016] According to the present invention, the influence of interference can be suppressed and high-precision pressure measurement can be performed. Attached Figure Description

[0017] Figure 1 (A) is a cross-sectional view showing an example of the pressure sensor structure according to Embodiment 1 of the present invention. Figure 1 (B) is its top view.

[0018] Figure 2 (A) is a cross-sectional view showing an example of the pressure sensor structure according to Embodiment 2 of the present invention. Figure 2 (B) is its top view.

[0019] Figure 3 This is a cross-sectional view showing an example of the pressure sensor structure according to Embodiment 3 of the present invention.

[0020] Figure 4 This is a cross-sectional view showing an example of the pressure sensor construction according to Embodiment 4 of the present invention.

[0021] Figure 5 This is a cross-sectional view showing an example of the pressure sensor structure according to Embodiment 5 of the present invention.

[0022] Figure 6 This is a cross-sectional view showing various examples of the pressure sensor device according to Embodiment 6 of the present invention.

[0023] Figure 7 This is an explanatory diagram illustrating an example of a manufacturing method for a pressure sensor structure according to Embodiment 7 of the present invention.

[0024] Figure 8 This is an explanatory diagram illustrating an example of a manufacturing method for a pressure sensor structure according to Embodiment 7 of the present invention.

[0025] Figure 9 (A) is a cross-sectional view showing an example of a conventional pressure sensor construction. Figure 9 (B) is its top view.

[0026] Figure 10 This is a cross-sectional view showing an example of the pressure sensor structure according to Embodiment 8 of the present invention.

[0027] Figure 11 This is a cross-sectional view showing an example of the pressure sensor construction according to Embodiment 9 of the present invention.

[0028] Figure 12 This is a cross-sectional view showing an example of the pressure sensor structure of Embodiment 10 of the present invention.

[0029] Figure 13 This is a cross-sectional view showing an example of the pressure sensor structure according to Embodiment 11 of the present invention.

[0030] Figure 14 This is a cross-sectional view showing an example of the pressure sensor structure of Embodiment 12 of the present invention.

[0031] Figure 15 This is a cross-sectional view showing an example of the pressure sensor structure according to Embodiment 13 of the present invention.

[0032] Figure 16 This is a cross-sectional view showing an example of the pressure sensor construction of Embodiment 14 of the present invention.

[0033] Figure 17 This is a cross-sectional view showing an example of the pressure sensor construction according to Embodiment 15 of the present invention.

[0034] Figure 18 This is a cross-sectional view showing an example of the pressure sensor construction according to Embodiment 16 of the present invention.

[0035] Figure 19 (A) is a cross-sectional view showing an example of the pressure sensor structure according to Embodiment 17 of the present invention. Figure 19 (B) is its top view.

[0036] Figure 20 (A) is a cross-sectional view showing an example of the pressure sensor structure according to Embodiment 18 of the present invention. Figure 20 (B) is its top view.

[0037] Figure 21(A) is a cross-sectional view showing an example of the pressure sensor structure according to Embodiment 19 of the present invention. Figure 21 (B) is its top view.

[0038] Figure 22 (A) is a cross-sectional view showing an example of the pressure sensor structure of Embodiment 20 of the present invention. Figure 22 (B) is its top view.

[0039] Figure 23 This is a circuit diagram showing an example of a capacitance conversion circuit that can be connected to the sensor configuration of the present invention.

[0040] Figure 24 This is a circuit diagram showing an example of a capacitance conversion circuit that can be connected to the sensor configuration of the present invention.

[0041] Figure 25 This is a circuit diagram showing an example of a capacitance conversion circuit that can be connected to the sensor configuration of the present invention.

[0042] Figure 26 This is a circuit diagram showing an example of a capacitance conversion circuit that can be connected to the sensor configuration of the present invention.

[0043] Figure 27 This is a circuit diagram showing an example of a capacitance conversion circuit that can be connected to the sensor configuration of the present invention.

[0044] Figure 28 This is a circuit diagram showing an example of a capacitance conversion circuit that can be connected to the sensor configuration of the present invention. Detailed Implementation

[0045] One technical solution of the present invention is a pressure sensor structure for detecting changes in electrostatic capacitance between electrodes. The pressure sensor structure comprises: a sensor body including a diaphragm plate serving as a sensing electrode, a base electrode opposite the diaphragm plate, and a sidewall layer maintaining a gap between the diaphragm plate and the base electrode; and a conductive protective substrate for supporting the sensor body. The sidewall layer includes a protective electrode layer and an upper protective insulating layer and a lower protective insulating layer that electrically insulate the protective electrode layer. The protective substrate is electrically connected to the protective electrode layer and, together with the protective electrode layer, functions as a protective electrode.

[0046] According to this structure, the protective substrate is electrically connected to the protective electrode layer, thus functioning as a protective electrode. Therefore, even when liquids such as water adhere to the end face of the substrate, it is possible to suppress the potential change of the base electrode that could cause a shift in the pressure output value.

[0047] Furthermore, since the bottom protective substrate functions as a protective electrode, it is less susceptible to electromagnetic noise from the electronic circuitry located below the pressure sensor structure. Therefore, it can suppress pressure output value deviations caused by interference.

[0048] Furthermore, with multiple pressure sensor structures formed on a single wafer substrate, the diaphragm plate and base electrode of each pressure sensor structure are electrically separated. Therefore, the characteristics of each chip can be selected before chip cutting.

[0049] Preferably, an electrical insulating layer is provided between the protective substrate and the sensor body to electrically insulate the protective substrate.

[0050] This structure ensures electrical insulation between the protective substrate and the sensor body.

[0051] Preferably, a passivation film is provided on the outer surface of the sensor body and the protective substrate.

[0052] According to this structure, even when liquids such as water adhere to the outer surface of the pressure sensor structure due to condensation, immersion, etc., the passivation film can suppress the influence from the liquid.

[0053] Preferably, the base electrode and the protective electrode layer are disposed in the same layer and electrically isolated from the protective electrode layer.

[0054] This structure reduces the dimensional error of the gap between the diaphragm plate and the base electrode. Furthermore, since the base electrode and the protective electrode layer can be formed using the same layer forming process, the manufacturing process can be simplified and costs reduced.

[0055] Preferably, the second base electrode and the second protective electrode layer are disposed in the same layer between the electrical insulating layer and the sensor body, and are electrically isolated from each other.

[0056] According to this structure, the second protective electrode layer can function as a protective electrode together with the protective electrode layer. Therefore, the function of the protective electrode can be further enhanced.

[0057] Preferably, at least one of the diaphragm plate, the upper protective electrical insulation layer, the protective electrode layer, the lower protective electrical insulation layer, and the protective substrate is provided with a groove for stress mitigation.

[0058] According to this structure, the lifespan and reliability of the sensor structure can be improved because it can mitigate the stress applied to the sensor body and / or protective substrate.

[0059] Preferably, the lower protective electrical insulation layer, the protective electrode layer, and the upper protective electrical insulation layer are formed in a frame shape along the periphery of the diaphragm plate. The distances W1 between the inner edges and W6 between the outer edges of the lower protective electrical insulation layer, W2 between the inner edges and W5 between the outer edges of the protective electrode layer, and W3 between the inner edges and W4 between the outer edges of the upper protective electrical insulation layer satisfy the following formula:

[0060] W1 < W2 < W3 and W4 < W5 < W6.

[0061] According to this structure, the surface distance of the outer surface of the sensor body is increased. Therefore, the influence of external leakage current and parasitic electrostatic capacitance between the diaphragm plate and the base electrode on the pressure output value can be reduced.

[0062] Preferably, the lower protective electrical insulating layer is formed as a plate larger than the outer shape of the diaphragm plate, and the protective electrode layer and the upper protective electrical insulating layer are formed as a frame along the periphery of the diaphragm plate. The distance W6 between the outer edges of the lower protective electrical insulating layer, the distance W2 between the inner edges of the protective electrode layer and the distance W5 between the outer edges, and the distance W3 between the inner edges of the upper protective electrical insulating layer and the distance W4 between the outer edges satisfy the following formula:

[0063] W2 < W3 and W4 < W5 < W6.

[0064] According to this structure, due to the increased surface distance of the outer surface of the sensor body, the influence of external leakage current and parasitic electrostatic capacitance between the diaphragm plate and the base electrode on the pressure output value can be reduced.

[0065] Preferably, at least a portion of the upper protective electrical insulation layer and the lower protective electrical insulation layer are formed of silicon dioxide (SiO2).

[0066] Based on this structure, silicon dioxide is obtained through the oxidation process of silicon. Therefore, it is possible to simplify the manufacturing process and reduce costs.

[0067] Another pressure sensor device according to the present invention includes: the pressure sensor structure described above; an integrated circuit that processes signals from the pressure sensor structure; a circuit board on which the integrated circuit and the pressure sensor structure are mounted; and a housing member made of metal or synthetic resin that, together with the circuit board, houses the integrated circuit and the pressure sensor structure.

[0068] Based on this structure, a pressure sensor device can be realized that can suppress the effects of interference such as condensation, water immersion, and electromagnetic noise.

[0069] Another technical solution of the present invention is a method for manufacturing a pressure sensor structure for detecting changes in electrostatic capacitance between electrodes. The manufacturing method includes the following steps: a) forming a lower substrate including a base electrode; b) forming an upper substrate including a diaphragm plate that functions as a sensing electrode; c) bonding the lower substrate and the upper substrate; d) shaping the lower substrate and the upper substrate into a stepped shape; and e) forming a passivation film on the outer surfaces of the shaped lower substrate and the upper substrate. Step a) of forming the lower substrate includes the following steps: a1) sequentially forming a lower protective electrical insulating layer and a conductive layer on a conductive lower substrate; and a2) etching the conductive layer to form a base electrode and a protective electrode layer. Step b) of forming the upper substrate includes the following steps: b1) forming an electrical insulating layer on a conductive upper substrate; and b2) etching the electrical insulating layer to form an upper protective electrical insulating layer.

[0070] Based on this structure, it is possible to realize a pressure sensor construction that can suppress the effects of interference such as condensation, water immersion, and electromagnetic noise.

[0071] (Implementation Method 1)

[0072] Figure 1 (A) is a cross-sectional view showing an example of the pressure sensor structure 1 according to Embodiment 1 of the present invention. Figure 1 (B) is its top view. To facilitate understanding, in Figure 1 The passivation film illustration is omitted in (B).

[0073] The pressure sensor structure 1 includes a sensor body and a protective substrate 10 supporting the sensor body. The sensor body includes a diaphragm plate 40, a base electrode 22, and a sidewall layer 30.

[0074] The diaphragm plate 40, formed of a conductive material such as polycrystalline silicon, amorphous silicon, or monocrystalline silicon, functions as a sensing electrode capable of deforming according to the surrounding pressure difference. The diaphragm plate 40 can consist of one or more layers; for example, an electrically insulating layer can be provided on the upper surface of the diaphragm plate 40. The base electrode 22, formed of a conductive material such as polycrystalline silicon, amorphous silicon, or monocrystalline silicon, is disposed opposite to the diaphragm plate 40. The sidewall layer 30 is provided to maintain the gap G between the diaphragm plate 40 and the base electrode 22. The gap G is a sealed space relative to the outside, for example, sealed with an inactive gas and maintained at a constant pressure.

[0075] The diaphragm plate 40 and the base electrode 22 constitute a parallel plate capacitor. The electrostatic capacitance C between the electrodes is expressed as C = ε × S / d, using the dielectric constant ε of the gap G, the electrode area S, and the distance d between the electrodes. If the diaphragm plate 40 elastically deforms according to the pressure difference between the external environment and the gap G, the distance d between the electrodes changes, and the electrostatic capacitance C also changes accordingly.

[0076] The sidewall layer 30 is frame-shaped to surround the gap G and consists of at least three layers, including a protective electrode layer 32, an electrically insulating layer 31 disposed below the protective electrode layer 32, and an electrically insulating layer 33 disposed above the protective electrode layer 32. Although a three-layer structure is shown here, the sidewall layer 30 may also include four or more layers.

[0077] The protective substrate 10 is formed of a conductive material such as polycrystalline silicon, amorphous silicon, or monocrystalline silicon. The protective substrate 10 can be composed of one or more layers; for example, an electrically insulating layer can be provided on the lower surface of the protective substrate 10. An intermediate layer 20 is provided between the protective substrate 10 and the sidewall layer 30. The intermediate layer 20 is composed of at least two layers, including an electrically insulating layer 21 on the substrate side and the aforementioned base electrode 22 located on the electrically insulating layer 21. Although a two-layer structure is shown here, the intermediate layer 20 may also include three or more layers.

[0078] The protective electrode layer 32 is located between the upper diaphragm plate 40 and the lower base electrode 22. This eliminates parasitic electrostatic capacitance independent of pressure changes.

[0079] Furthermore, the protective substrate 10 is also electrically connected to the protective electrode layer 32, and together with the protective electrode layer 32, it functions as a protective electrode. The protective substrate 10 and the protective electrode layer 32 can be connected via via holes, wires, or other means within this structure, or they can be connected via external electronic circuits.

[0080] With this structure, even when liquids such as water adhere to the end face of the substrate, it is possible to suppress the pressure output value deviation caused by changes in the potential of the base electrode. Furthermore, since the protective substrate 10, which is set as the bottom layer, functions as a protective electrode (shielding electrode), it is not easily affected by electromagnetic noise from the electronic circuitry located below the pressure sensor structure, thus suppressing pressure output value deviation.

[0081] A passivation film 45 is provided on the outer surface of the sensor body, the electrical insulating layer 21, and the protective substrate 10. The passivation film 45 is, for example, made of SiN. x Electrically insulating materials such as SiO2 are used to form a protective structure for the pressure sensor.

[0082] (Implementation Method 2)

[0083] Figure 2(A) is a cross-sectional view showing an example of the pressure sensor structure 1 according to Embodiment 2 of the present invention. Figure 2 (B) is its top view. To facilitate understanding, in Figure 2 The passivation film illustration is omitted in (B). In this embodiment, with Figure 1 Compared to the previous structure, the base electrode 34 and the protective electrode layer 32 are disposed in the same layer instead of the base electrode 22.

[0084] The pressure sensor structure 1 includes a sensor body and a protective substrate 10 supporting the sensor body. The sensor body includes a diaphragm plate 40, a base electrode 34, and a sidewall layer 30.

[0085] The diaphragm plate 40, formed of a conductive material such as polycrystalline silicon, amorphous silicon, or monocrystalline silicon, functions as a sensing electrode capable of deforming according to the surrounding pressure difference. The diaphragm plate 40 can consist of one or more layers; for example, an electrically insulating layer can be provided on the upper surface of the diaphragm plate 40. The base electrode 34, formed of a conductive material such as polycrystalline silicon, amorphous silicon, or monocrystalline silicon, is disposed opposite to the diaphragm plate 40. The sidewall layer 30 is provided to maintain the gap G between the diaphragm plate 40 and the base electrode 34. The gap G is a sealed space relative to the outside, for example, sealed with an inactive gas and maintained at a constant pressure. The diaphragm plate 40 and the base electrode 34 constitute a parallel-plate capacitor.

[0086] The sidewall layer 30 is frame-shaped to surround the gap G and consists of at least three layers, including a protective electrode layer 32, an electrically insulating layer 31 disposed below the protective electrode layer 32, and an electrically insulating layer 33 disposed above the protective electrode layer 32. Although a three-layer structure is shown here, the sidewall layer 30 may also include four or more layers.

[0087] The base electrode 34 is disposed on the same layer as the protective electrode layer 32 above the electrically insulating layer 31, and is electrically isolated from the protective electrode layer 32 by means of a trench 34a. Using this structure, the height dimension of the gap G depends only on the thickness error of the electrically insulating layer 33. Figure 1 Compared to other structures, this allows for a higher precision structure. Furthermore, since the base electrode 34 and the protective electrode layer 32 can be formed using the same layer forming process, the manufacturing process can be simplified and costs reduced.

[0088] The protective substrate 10 is formed of a conductive material such as polycrystalline silicon, amorphous silicon, or monocrystalline silicon. The protective substrate 10 can be composed of one or more layers; for example, an electrically insulating layer can be provided on the lower surface of the protective substrate 10. An intermediate layer 20 is provided between the protective substrate 10 and the sidewall layer 30. The intermediate layer 20 is composed of at least two layers, including an electrically insulating layer 21 on the substrate side and a base conductive layer 23 located above the electrically insulating layer 21. The base conductive layer 23 is electrically connected to the base electrode 34. Although a two-layer structure is shown here, the intermediate layer 20 may also include three or more layers.

[0089] The protective electrode layer 32 is located between the upper diaphragm plate 40 and the lower substrate conductive layer 23. This eliminates parasitic electrostatic capacitance independent of pressure changes.

[0090] Furthermore, the protective substrate 10 is also electrically connected to the protective electrode layer 32, and together with the protective electrode layer 32, it functions as a protective electrode. The substrate 10 and the protective electrode layer 32 can be connected via vias, wires, or other means within this structure, or they can be connected via external electronic circuits.

[0091] With this structure, even when liquids such as water adhere to the end face of the substrate, it is possible to suppress the pressure output value deviation caused by changes in the potential of the base electrode. Furthermore, since the protective substrate 10, which is set as the bottom layer, functions as a protective electrode (shielding electrode), it is not easily affected by electromagnetic noise from the electronic circuitry located below the pressure sensor structure, thereby suppressing pressure output value deviation.

[0092] A passivation film 45 is provided on the outer surface of the sensor body, the conductive layer 23, the electrically insulating layer 21, and the protective substrate 10. The passivation film 45 is, for example, made of SiN. x Electrically insulating materials such as SiO2 are used to form a protective structure for the pressure sensor.

[0093] (Implementation Method 3)

[0094] Figure 3 This is a cross-sectional view showing an example of the pressure sensor structure 1 according to Embodiment 3 of the present invention. In this embodiment, with Figure 2 Compared to the previous structure, the second base electrode 25 and the second protective electrode layer 24 are disposed in the same layer instead of the base conductive layer 23.

[0095] The pressure sensor structure 1 includes a sensor body and a protective substrate 10 supporting the sensor body. The sensor body includes a diaphragm plate 40, a base electrode 34, and a sidewall layer 30.

[0096] The diaphragm plate 40, formed of a conductive material such as polycrystalline silicon, amorphous silicon, or monocrystalline silicon, functions as a sensing electrode capable of deforming according to the surrounding pressure difference. The diaphragm plate 40 can consist of one or more layers; for example, an electrically insulating layer can be provided on the upper surface of the diaphragm plate 40. The base electrode 34, formed of a conductive material such as polycrystalline silicon, amorphous silicon, or monocrystalline silicon, is disposed opposite to the diaphragm plate 40. The sidewall layer 30 is provided to maintain the gap G between the diaphragm plate 40 and the base electrode 34. The gap G is a sealed space relative to the outside, for example, sealed with an inactive gas and maintained at a constant pressure. The diaphragm plate 40 and the base electrode 34 constitute a parallel-plate capacitor.

[0097] The sidewall layer 30 is frame-shaped to surround the gap G and consists of at least three layers, including a protective electrode layer 32, an electrically insulating layer 31 disposed below the protective electrode layer 32, and an electrically insulating layer 33 disposed above the protective electrode layer 32. Although a three-layer structure is shown here, the sidewall layer 30 may also include four or more layers.

[0098] The base electrode 34 is disposed on the same layer as the protective electrode layer 32 above the electrically insulating layer 31, and is electrically isolated from the protective electrode layer 32 by means of a trench 34a. Using this structure, the height dimension of the gap G depends only on the thickness error of the electrically insulating layer 33. Figure 1 Compared to other structures, this allows for a higher precision structure. Furthermore, since the base electrode 34 and the protective electrode layer 32 can be formed using the same layer forming process, the manufacturing process can be simplified and costs reduced.

[0099] The protective substrate 10 is formed of a conductive material such as polycrystalline silicon, amorphous silicon, or monocrystalline silicon. The protective substrate 10 can be composed of one or more layers; for example, an electrically insulating layer can be provided on the lower surface of the protective substrate 10. An intermediate layer 20 is provided between the protective substrate 10 and the sidewall layer 30. The intermediate layer 20 is composed of at least two layers, including an electrically insulating layer 21 on the substrate side and a second base electrode 25 and a second protective electrode layer 24 located on the electrically insulating layer 21. Although a two-layer structure is shown here, the intermediate layer 20 may also include three or more layers. The second base electrode 25 and the second protective electrode layer 24 are disposed in the same layer and electrically isolated from each other by means of trenches 25a. The second base electrode 25 is electrically connected to the base electrode 34. Furthermore, the second protective electrode layer 24 is electrically connected to the protective electrode layer 32.

[0100] The protective electrode layer 32 and the second protective electrode layer 24 are located between the upper diaphragm plate 40 and the lower protective substrate 10. This eliminates parasitic electrostatic capacitance independent of pressure changes.

[0101] Furthermore, the protective substrate 10 is also electrically connected to the protective electrode layer 32, and together with the protective electrode layer 32, it functions as a protective electrode. The substrate 10 and the protective electrode layer 32 can be connected via vias, wires, or other means within this structure, or they can be connected via external electronic circuits.

[0102] With this structure, even when liquids such as water adhere to the end face of the substrate, it is possible to suppress the pressure output value deviation caused by changes in the potential of the base electrode. Furthermore, since the protective substrate 10, which is set as the bottom layer, functions as a protective electrode (shielding electrode), it is not easily affected by electromagnetic noise from the electronic circuitry located below the pressure sensor structure, thereby suppressing pressure output value deviation.

[0103] Furthermore, the second protective electrode layer 24 is also electrically connected to the protective electrode layer 32, and together with the protective electrode layer 32, it functions as a protective electrode. Therefore, the function of the protective electrode can be further enhanced.

[0104] A passivation film 45 is provided on the outer surface of the sensor body, the second protective electrode layer 24, the electrical insulating layer 21, and the protective substrate 10. The passivation film 45 is, for example, made of SiN. x Electrically insulating materials such as SiO2 are used to form a protective structure for the pressure sensor.

[0105] (Implementation Method 4)

[0106] Figure 4 This is a cross-sectional view showing an example of the pressure sensor structure 1 according to Embodiment 4 of the present invention. In this embodiment, the optimization of the width dimension of the sidewall layer 30 will be explained. Figure 1 In the pressure sensor structure 1 shown, the lower electrical insulating layer 31, the protective electrode layer 32, and the upper electrical insulating layer 33 constituting the sidewall layer 30 are formed in a frame shape along the periphery of the diaphragm plate 40, showing the cross-sectional shape of the so-called stepped pyramid structure.

[0107] Specifically, the distances W1 between the inner edges and W6 between the outer edges of the electrical insulating layer 31, W2 between the inner edges and W5 between the outer edges of the protective electrode layer 32, and W3 between the inner edges and W4 between the outer edges of the electrical insulating layer 33 preferably satisfy the following formula:

[0108] W1 < W2 < W3 and W4 < W5 < W6.

[0109] As specific numerical examples, W1, W2, and W3 can also be in the range of approximately 20 μm to 500 μm, and W4, W5, and W6 can also be in the range of approximately 50 μm to 1000 μm. The area of ​​the diaphragm plate 40 can also be approximately 0.5 mm². 2 ~2mm2 The thickness of the diaphragm plate 40 can also be in the range of approximately 0.5 μm to 10 μm. The thickness of the electrically insulating layer and the conductive layer can also be in the range of approximately 0.1 μm to 1 μm. The thickness of the protective substrate 10 can also be in the range of approximately 100 μm to 825 μm.

[0110] This structure increases the surface distance along the outer surface of the sensor body. Therefore, it reduces the impact of external leakage current and parasitic electrostatic capacitance between the diaphragm plate 40 and the base electrode 22 on the pressure output value.

[0111] (Implementation Method 5)

[0112] Figure 5 This is a cross-sectional view showing an example of the pressure sensor structure 1 according to Embodiment 5 of the present invention. In this embodiment, the optimization of the width dimension of the sidewall layer 30 will be explained. Figure 2 In the pressure sensor structure 1 shown, the lower electrical insulating layer 31 constituting the sidewall layer 30 is formed into a plate shape larger than the outer shape of the diaphragm plate 40. The protective electrode layer 32 constituting the sidewall layer 30 and the upper electrical insulating layer 33 are formed into a frame shape along the periphery of the diaphragm plate 40, showing the cross-sectional shape of a so-called stepped pyramid structure.

[0113] Specifically, the distance W6 between the outer edges of the electrical insulating layer 31, the distance W2 between the inner edges of the protective electrode layer 32 and the distance W5 between its outer edges, and the distance W3 between the inner edges of the electrical insulating layer 33 and the distance W4 between its outer edges preferably satisfy the following formula:

[0114] W2 < W3 and W4 < W5 < W6.

[0115] This structure increases the surface distance along the outer surface of the sensor body. Therefore, it reduces the impact of external leakage current and parasitic electrostatic capacitance between the diaphragm plate 40 and the base electrode 34 on the pressure output value.

[0116] (Implementation Method 6)

[0117] Figure 6 (A) Figure 6 (C) is a cross-sectional view showing various examples of the pressure sensor device 100 according to Embodiment 6 of the present invention.

[0118] The pressure sensor device 100 includes the aforementioned pressure sensor structure 1, integrated circuit 110, circuit board 120, and housing member 130. The integrated circuit 110, composed of an ASIC, FPGA, PLD, CPLD, etc., has the function of processing signals from the pressure sensor structure 1. The integrated circuit 110 is electrically connected to the pressure sensor structure 1 via terminals provided on its upper surface. The integrated circuit 110 is electrically connected to a conductor of the circuit board 120 via terminals provided on its lower surface. The electrical connection between the integrated circuit 110 and the pressure sensor structure 1 can also be made via the circuit board 120. Furthermore, the electrical connection between the integrated circuit 110 and the circuit board 120 can also be made using wires or the like via terminals provided on the upper surface of the integrated circuit 110.

[0119] The circuit board 120 has the function of mounting an integrated circuit 110 and a pressure sensor structure 1, including conductors for electrical connection with external circuits.

[0120] The housing component 130 is formed, for example, of metal or synthetic resin, and houses the circuit board 120, the integrated circuit 110, and the pressure sensor structure 1.

[0121] exist Figure 6 In the example shown in (A), the housing component 130 is formed in a stepped cylindrical shape and is fixed to the circuit board 120. An opening 131 for communicating with the atmosphere is provided at the upper part of the housing component 130. The interior of the housing component 130 may be filled with only air, or it may be filled with gel 132 as shown in the figure. The gel 132 can enhance the waterproofness, water resistance, corrosion resistance, etc. of the pressure sensor structure 1.

[0122] exist Figure 6 In the example shown in (B), the outer casing member 130 is formed into a hollow cylindrical shape, a hollow polygonal cylindrical shape, a hollow cuboid shape, etc., and is mounted on the circuit board 120. An opening 131 for communicating with the atmosphere is provided on the upper part of the outer casing member 130.

[0123] exist Figure 6In the example shown in (C), the housing member 130 is formed in the shape of a rectangular frame, a cylindrical frame, etc., and is resin-molded in a manner that allows it to be tightly attached to the side of the pressure sensor structure 1 and the circuit board 120. However, when the housing member 130 is formed of synthetic resin, there is a possibility that the housing member 130 may absorb water. In this case, there is a possibility that the end of the pressure sensor structure 1 becomes electrically connected to water, and the parasitic capacitance between the sensing potential and the base electrode potential in contact with the water-absorbed housing member 130 increases, leading to a change in characteristics. In this case, in conventional pressure sensor structures, since the base electrode is exposed, there is a possibility of characteristic changes, but in the pressure sensor structure of the present invention, since the base electrode is not exposed, characteristic changes can be prevented.

[0124] (Implementation Method 7)

[0125] Figure 7 and Figure 8 This is an explanatory diagram illustrating an example of a manufacturing method for a pressure sensor structure according to Embodiment 7 of the present invention. Although this example shows a completed... Figure 2 The pressure sensor configuration shown is case 1, but... Figure 1 and Figure 3 The pressure sensor shown in Figure 1 has the same construction.

[0126] First, the lower substrate of pressure sensor structure 1 will be described. For example... Figure 7 As shown in (A), a wafer substrate 50 with conductivity such as Si is prepared, and then an electrically insulating layer 51 such as SiO2 is formed on the wafer substrate 50 by an oxidation process. The wafer substrate 50 and the electrically insulating layer 51 are respectively coated with... Figure 2 The protective substrate 10 and the electrical insulating layer 21 shown correspond to each other.

[0127] Next, as Figure 7 As shown in (B), a conductive layer 52, such as polycrystalline silicon, is formed by sputtering, followed by an oxidation process to form an electrically insulating layer 53, such as SiO2, on top of the conductive layer 52. The conductive layer 52 and the electrically insulating layer 53 are respectively coated with... Figure 2 The conductive layer 23 and the electrically insulating layer 31 shown correspond to each other. Next, the electrically insulating layer 53 is processed into a desired pattern using photolithography and etching, at which point, for example, a via is formed.

[0128] Next, as Figure 7 As shown in (C), a conductive layer 54, such as polycrystalline silicon, is formed by sputtering. At this time, the conductive layer 54 is in a conductive state with the conductive layer 52 through a via. Next, if necessary, the conductive layer 54 may be subjected to mirror polishing.

[0129] Next, as Figure 7 As shown in (D), the conductive layer 54 is processed into a desired pattern using photolithography and etching to form... Figure 2 The protective electrode layer 32 and the base electrode 34 are shown. This forms the lower substrate LS of the pressure sensor structure 1.

[0130] Next, the upper substrate of pressure sensor structure 1 will be described. For example... Figure 7 As shown in (E), for example, a three-layer structure of conductive layer 62, electrically insulating layer 63, and conductive layer 64 is prepared using an SOI (Silicon on Insulator) substrate having a three-layer structure of Si / SiO2 / Si. Next, an electrically insulating layer 61 such as SiO2 is formed on the surface of conductive layer 62 by oxidation treatment, and an electrically insulating layer 65 such as SiO2 is formed on the surface of conductive layer 64.

[0131] Next, as Figure 7 As shown in (F), the electrically insulating layer 65 is processed into a desired pattern using photolithography and etching to form... Figure 2 The electrically insulating layer 33 is shown. This forms the upper substrate US of the pressure sensor structure 1.

[0132] Next, as Figure 8 As shown in (A), an upper substrate US is mounted on a lower substrate LS, and the two are bonded together using an adhesive or the like. Next, as... Figure 8 As shown in (B), the electrically insulating layer 61, conductive layer 62, and electrically insulating layer 63 are removed by grinding the upper substrate US until the conductive layer 64 is exposed. This conductive layer 64 and... Figure 2 The diaphragm plate 40 shown corresponds to this.

[0133] Next, as Figure 8 As shown in (C), photolithography and etching are used to shape the layers located above the wafer substrate 50 into a stepped pyramid shape. This completes the process. Figure 2 The diagram shows an electrically insulating layer 21, a substrate conductive layer 23, an electrically insulating layer 31, a protective electrode layer 32, an electrically insulating layer 33, and a diaphragm plate 40. Next, a first electrode pattern communicating with the diaphragm plate 40 is formed using sputtering, photolithography, and etching, and a second electrode pattern communicating with the substrate electrode 34 and the substrate conductive layer 23 is formed. The main components of the electrode patterns are Al or Au.

[0134] In this way, a plurality of pressure sensor structures are formed on a wafer substrate 50. In this state, the diaphragm plate 40 and the base electrode 34 of each pressure sensor structure are electrically separated. Therefore, the characteristics of each chip can be selected using a wafer tester before the chip is cut.

[0135] Next, as Figure 8 As shown in (D), by using sputtering, for example, to deposit SiN xA passivation film 45, such as SiO2, is formed on the surface and end face of the separator plate 40 to the electrically insulating layer 21 and on the upper surface of the wafer substrate 50. Then, the passivation film 45 is processed into a desired pattern by etching.

[0136] Next, as Figure 8 As shown in (E), the wafer substrate 50 is cut into individual chips (monolithization) by dicing. The wafer substrate 50 becomes Figure 2 The protective substrate 10 shown.

[0137] This allows for the suppression of interference from condensation, water immersion, and electromagnetic noise. Figure 2 The pressure sensor structure shown is 1.

[0138] (Implementation Method 8)

[0139] Figure 10 This is a cross-sectional view showing an example of the pressure sensor structure 1 according to Embodiment 8 of the present invention. This embodiment is similar to... Figure 9 The structures shown are similar, but they differ in that the bottom layer is set as a protective substrate 10.

[0140] The pressure sensor structure 1 includes a sensor body and a protective substrate 10 supporting the sensor body. The sensor body includes a diaphragm plate 40, a base electrode 34, and a sidewall layer 30.

[0141] The diaphragm plate 40, formed of a conductive material such as polycrystalline silicon, amorphous silicon, or monocrystalline silicon, functions as a sensing electrode capable of deforming according to the surrounding pressure difference. The diaphragm plate 40 can consist of one or more layers; for example, an electrically insulating layer can be provided on the upper surface of the diaphragm plate 40. The base electrode 34, formed of a conductive material such as polycrystalline silicon, amorphous silicon, or monocrystalline silicon, is disposed opposite to the diaphragm plate 40. The sidewall layer 30 is provided to maintain the gap G between the diaphragm plate 40 and the base electrode 34. The gap G is a sealed space relative to the outside, for example, sealed with an inactive gas and maintained at a constant pressure. The diaphragm plate 40 and the base electrode 34 constitute a parallel-plate capacitor.

[0142] The sidewall layer 30 is frame-shaped to surround the gap G and consists of at least three layers, including a protective electrode layer 32, an electrically insulating layer 31 disposed below the protective electrode layer 32, and an electrically insulating layer 33 disposed above the protective electrode layer 32. Although a three-layer structure is shown here, the sidewall layer 30 may also include four or more layers.

[0143] The base electrode 34 is disposed on the same layer as the protective electrode layer 32 above the electrically insulating layer 31, and is electrically isolated from the protective electrode layer 32 by means of a trench 34a. Using this structure, the height dimension of the gap G depends only on the thickness error of the electrically insulating layer 33. Figure 1Compared to other structures, a more precise structure can be obtained. In addition, since the base electrode 34 and the protective electrode layer 32 can be formed using the same layer forming process, the manufacturing process can be simplified and the cost reduced.

[0144] The protective substrate 10 is formed of a conductive material such as polycrystalline silicon, amorphous silicon, or monocrystalline silicon. The protective substrate 10 can be composed of one or more layers; for example, an electrically insulating layer can be provided on the lower surface of the protective substrate 10. An intermediate layer 20 is provided between the protective substrate 10 and the sidewall layer 30. The intermediate layer 20 is composed of at least two layers, including an electrically insulating layer 21 on the substrate side and a base conductive layer 23 located above the electrically insulating layer 21. The base conductive layer 23 is electrically connected to the base electrode 34. Although a two-layer structure is shown here, the intermediate layer 20 may also include three or more layers.

[0145] Furthermore, the protective substrate 10 is also electrically connected to the protective electrode layer 32, and together with the protective electrode layer 32, it functions as a protective electrode. The substrate 10 and the protective electrode layer 32 can be connected via vias, wires, or other means within this structure, or they can be connected via external electronic circuits.

[0146] With this structure, even when liquids such as water adhere to the end face of the substrate, it is possible to suppress the pressure output value deviation caused by changes in the potential of the base electrode. Furthermore, since the protective substrate 10, which is set as the bottom layer, functions as a protective electrode (shielding electrode), it is not easily affected by electromagnetic noise from the electronic circuitry located below the pressure sensor structure, thereby suppressing pressure output value deviation.

[0147] A passivation film 45 is provided on the outer surface of the sensor body and the protective substrate 10. The passivation film 45 is, for example, made of SiN. x Electrically insulating materials such as SiO2 are used to form a protective structure for the pressure sensor.

[0148] (Implementation Method 9)

[0149] Figure 11 This is a cross-sectional view showing an example of the pressure sensor structure 1 according to Embodiment 9 of the present invention. This embodiment is similar to... Figure 1 The structure shown is similar, but a groove 41 with a depth approximately half the thickness of the diaphragm plate 40 is formed at a position inside the edge of the diaphragm plate 40, for example, above the position of the sidewall layer 30. This can alleviate the stress applied to the diaphragm plate 40.

[0150] (Implementation Method 10)

[0151] Figure 12 This is a cross-sectional view illustrating an example of the pressure sensor structure 1 according to Embodiment 10 of the present invention. This embodiment is similar to... Figure 1The structure shown is similar, but a groove 42 extending to the back surface of the protective substrate 10 is formed at a position inside the edge of the protective substrate 10, for example, below the position of the sidewall layer 30. This can alleviate the stress applied to the protective substrate 10.

[0152] As an alternative, the groove 42 may also be formed in at least one of the protective substrate 10, the electrical insulating layer 21, the base electrode 22, the electrical insulating layer 31, the protective electrode layer 32, the electrical insulating layer 33, and the diaphragm plate 40, and may be exposed to the outside, or may not be exposed to the outside.

[0153] (Implementation Method 11)

[0154] Figure 13 This is a cross-sectional view illustrating an example of the pressure sensor structure 1 according to Embodiment 11 of the present invention. This embodiment is similar to... Figure 2 The structure shown is similar, but a groove 41 with a depth approximately half the thickness of the diaphragm plate 40 is formed at a position inside the edge of the diaphragm plate 40, for example, above the position of the sidewall layer 30. This can alleviate the stress applied to the diaphragm plate 40.

[0155] (Implementation Method 12)

[0156] Figure 14 This is a cross-sectional view illustrating an example of the pressure sensor structure 1 according to Embodiment 12 of the present invention. This embodiment is similar to... Figure 2 The structure shown is similar, but a groove 42 extending to the back surface of the protective substrate 10 is formed at a position inside the edge of the protective substrate 10, for example, below the position of the sidewall layer 30. This can alleviate the stress applied to the protective substrate 10.

[0157] As an alternative, the groove 42 may also be formed in at least one of the protective substrate 10, the electrical insulating layer 21, the base conductive layer 23, the electrical insulating layer 31, the protective electrode layer 32, the electrical insulating layer 33, and the diaphragm plate 40, and may be exposed to the outside, or may not be exposed to the outside.

[0158] (Implementation Method 13)

[0159] Figure 15 This is a cross-sectional view illustrating an example of the pressure sensor structure 1 according to Embodiment 13 of the present invention. This embodiment is similar to... Figure 3 The structure shown is similar, but a groove 41 with a depth approximately half the thickness of the diaphragm plate 40 is formed at a position inside the edge of the diaphragm plate 40, for example, above the position of the sidewall layer 30. This can alleviate the stress applied to the diaphragm plate 40.

[0160] (Implementation Method 14)

[0161] Figure 16 This is a cross-sectional view illustrating an example of the pressure sensor structure 1 according to Embodiment 14 of the present invention. This embodiment is similar to... Figure 3 The structure shown is similar, but a groove 42 extending to the back surface of the protective substrate 10 is formed at a position inside the edge of the protective substrate 10, for example, below the position of the sidewall layer 30. This can alleviate the stress applied to the protective substrate 10.

[0162] As an alternative, the groove 42 may also be formed in at least one of the protective substrate 10, the electrical insulating layer 21, the second protective electrode layer 24, the electrical insulating layer 31, the protective electrode layer 32, the electrical insulating layer 33, and the diaphragm plate 40, and may be exposed to the outside, or may not be exposed to the outside.

[0163] (Implementation Method 15)

[0164] Figure 17 This is a cross-sectional view illustrating an example of the pressure sensor structure 1 according to Embodiment 15 of the present invention. This embodiment is similar to... Figure 10 The structure shown is similar, but a groove 41 with a depth approximately half the thickness of the diaphragm plate 40 is formed at a position inside the edge of the diaphragm plate 40, for example, above the position of the sidewall layer 30. This can alleviate the stress applied to the diaphragm plate 40.

[0165] (Implementation Method 16)

[0166] Figure 18 This is a cross-sectional view illustrating an example of the pressure sensor structure 1 according to Embodiment 16 of the present invention. This embodiment is similar to... Figure 10 The structure shown is similar, but a groove 42 extending to the back surface of the protective substrate 10 is formed at a position inside the edge of the protective substrate 10, for example, below the position of the sidewall layer 30. This can alleviate the stress applied to the protective substrate 10.

[0167] As an alternative, the groove 42 may also be formed in at least one of the protective substrate 10, the electrical insulating layer 31, the protective electrode layer 32, the electrical insulating layer 33, and the diaphragm plate 40, and may be exposed to the outside, or may not be exposed to the outside.

[0168] (Implementation Method 17)

[0169] Figure 19 (A) is a cross-sectional view showing an example of the pressure sensor structure 1 according to embodiment 17 of the present invention. Figure 19 (B) is its top view. To facilitate understanding, in Figure 19 The passivation film illustration is omitted in (B). This embodiment is different from... Figure 1The structure shown is similar, but the edges of the electrical insulating layer 21 and the base electrode 22 are extended laterally, and the edge of the protective substrate 10 is also extended laterally. Openings are formed in the passivation film 45 disposed on the upper surfaces of the diaphragm plate 40, the base electrode 22, and the protective substrate 10, respectively, to which pad electrodes PA, PB, and PC are disposed. This facilitates the bonding operation of the pad electrodes PA, PB, PC and the wires.

[0170] (Implementation Method 18)

[0171] Figure 20 (A) is a cross-sectional view showing an example of the pressure sensor structure 1 according to embodiment 18 of the present invention. Figure 20 (B) is its top view. To facilitate understanding, in Figure 20 The passivation film illustration is omitted in (B). This embodiment is different from... Figure 2 The structure shown is similar, but the edges of the electrically insulating layer 21 and the base conductive layer 23 are extended laterally, and the edge of the protective substrate 10 is also extended laterally. Openings are formed in the passivation film 45 disposed on the upper surfaces of the diaphragm plate 40, the base conductive layer 23, and the protective substrate 10, and pad electrodes PA, PB, and PC are respectively disposed thereon. This facilitates the bonding operation of the pad electrodes PA, PB, PC and the wires.

[0172] (Implementation Method 19)

[0173] Figure 21 (A) is a cross-sectional view showing an example of the pressure sensor structure 1 according to embodiment 19 of the present invention. Figure 21 (B) is its top view. To facilitate understanding, in Figure 21 The passivation film illustration is omitted in (B). This embodiment is different from... Figure 3 The structure shown is similar, but the edges of the electrical insulating layer 21 and the second protective electrode layer 24 are extended laterally, and the edge of the protective substrate 10 is also extended laterally. Openings are formed in the passivation film 45 disposed on the upper surfaces of the diaphragm plate 40, the second protective electrode layer 24, and the protective substrate 10, respectively, to which pad electrodes PA, PB, and PC are disposed. This facilitates the bonding operation of the pad electrodes PA, PB, PC and the wires.

[0174] (Implementation Method 20)

[0175] Figure 22 (A) is a cross-sectional view showing an example of the pressure sensor structure 1 according to embodiment 20 of the present invention. Figure 22 (B) is its top view. To facilitate understanding, in Figure 22 The passivation film illustration is omitted in (B). This embodiment is different from... Figure 10The structure shown is similar, but the edges of the base electrode 34 and the protective electrode layer 32 are extended laterally, and the edge of the protective substrate 10 is extended laterally as well. Openings are formed in the passivation film 45 disposed on the upper surfaces of the diaphragm plate 40, the base electrode 34, and the protective substrate 10, and pad electrodes PA, PB, and PC are respectively disposed thereon. As a result, the bonding operation of the pad electrodes PA, PB, PC and the wires becomes easier.

[0176] The function of the protective electrode will now be explained. In the embodiments described above, the protective electrode layer 32 and the second protective electrode layer 24 function as protective electrodes.

[0177] The protective electrode can also be connected to a constant potential, preferably the ground or imaginary ground of the circuit connected to the sensor, or it can be connected to any of the other potentials described below, capable of separating the current flowing between the diaphragm plate and the protective electrode, and between the base electrode and the protective electrode, from the current flowing between the diaphragm plate and the base electrode. In other words, it can also be used to prevent the impedance between the diaphragm plate and the protective electrode, and between the base electrode and the protective electrode, from affecting the electrostatic capacitance measured between the diaphragm plate and the base electrode.

[0178] Figures 23-28 This is a circuit diagram illustrating various examples of capacitance conversion circuits that can be connected to the sensor configuration of the present invention. These capacitance conversion circuits include an operational amplifier OP, a base terminal TB for the base electrode, a diaphragm terminal TD for the diaphragm plate electrode, a protection terminal TG for the protection electrode, a voltage source CV or a current source CC, and a reference impedance RA. By using these capacitance conversion circuits, a voltage output representing the electrostatic capacitance between the diaphragm plate and the base electrode can be obtained while suppressing the effects of interference.

[0179] Figures 23-26 This represents an exemplary inverting operational amplifier circuit where the positive non-inverting input is connected to a common ground or zero-voltage terminal. Due to the requirement of a near-zero differential input voltage in the closed-loop feedback circuit, the potential of the inverting input is approximately equal to that of the non-inverting input, creating a hypothetical ground point VG.

[0180] exist Figure 23 In this configuration, the protective electrode maintains the same potential as the base electrode. For example... Figure 23As shown, the base terminal TB is connected to the imaginary ground point VG of the inverting input of amplifier OP, and the protection terminal TG is at ground potential. Therefore, the voltage and current between the protection electrode and the base electrode can be ignored, and will not have a substantial effect on the capacitance value measured between the base electrode and the diaphragm plate. The diaphragm terminal TD is connected to the voltage source CV in a manner that allows the current between the protection electrode and the diaphragm plate to be ignored and will not have a substantial effect on the capacitance value measured between the diaphragm plate and the base electrode. The electrostatic capacitance between the protection electrode and the base electrode is connected between ground and the imaginary ground point VG, and will not have a substantial effect on the capacitance value measured between the diaphragm plate and the base electrode.

[0181] Set the electrostatic capacitance between the base terminal TB and the diaphragm terminal TD to C. S Set the electrostatic capacitance between the base terminal TB and the protection terminal TG to C. L Furthermore, the voltage source CV is assumed to be the effective voltage U. i The AC voltage source, with the feedback circuit element RA assumed to be related to C F Given capacitors with equal electrostatic capacitance, assume the open-loop gain of amplifier OP is A. The output voltage U of amplifier OP. o As shown below.

[0182] [Formula 1]

[0183]

[0184] Thus, C L The effect is correspondingly reduced in terms of the amplifier's open-loop gain A. This is because the electrostatic capacitance between the diaphragm terminal TD and the protection terminal TG is also related to the voltage source U. i The voltage source U is connected in parallel. i As an ideal voltage source, it can supply current to the electrostatic capacitor without changing the voltage, thus not affecting the output voltage.

[0185] Next, in Figure 24 In this configuration, the protective electrode is maintained at approximately the same potential as the diaphragm plate. For example... Figure 24 As shown, the diaphragm terminal TD is connected to the imaginary ground point VG of the inverting input of amplifier OP, and the protection terminal TG is at ground potential. Therefore, the voltage and current between the protection electrode and the diaphragm plate can be ignored and will not have a substantial effect on the capacitance value measured between the base electrode and the diaphragm plate. The base terminal TB is connected to the voltage source CV in such a way that the current between the protection electrode and the base electrode will not have a substantial effect on the capacitance value measured between the diaphragm plate and the base electrode. Since the electrostatic capacitance between the protection electrode and the base electrode is connected between ground and the voltage source CV, it will not have a substantial effect on the capacitance value measured between the diaphragm plate and the base electrode.

[0186] Next, in Figure 25 In this configuration, the protective electrode is maintained at approximately the same potential as the diaphragm plate. For example... Figure 25 As shown, the diaphragm terminal TD is connected to the imaginary ground point of the inverting input of amplifier OP, and the protection terminal TG is at ground potential. Therefore, the voltage and current between the protection electrode and the diaphragm plate can be ignored, and will not have a substantial effect on the capacitance value measured between the base electrode and the diaphragm plate. The base terminal TB is connected to the output of amplifier OP in a manner that allows the current between the protection electrode and the base electrode to be ignored and will not have a substantial effect on the capacitance value measured between the diaphragm plate and the base electrode. Since the electrostatic capacitance between the protection electrode and the base electrode is connected between ground and the output of amplifier OP, it will not have a substantial effect on the capacitance value measured between the diaphragm plate and the base electrode.

[0187] Next, in Figure 26 In this configuration, the protective electrode is maintained at approximately the same potential as the base electrode. For example... Figure 26 As shown, the base terminal TB is connected to the imaginary ground point of the inverting input of amplifier OP, and the protection terminal TG is at ground potential. Therefore, the voltage and current between the protection electrode and the base electrode can be ignored, and will not have a substantial effect on the capacitance value measured between the base electrode and the diaphragm plate. The diaphragm terminal TD is connected to the output of amplifier OP in a manner that allows the current between the protection electrode and the diaphragm plate to be ignored and will not have a substantial effect on the capacitance value measured between the diaphragm plate and the base electrode. Since the electrostatic capacitance between the protection electrode and the base electrode is connected between ground and the imaginary ground point, it will not have a substantial effect on the capacitance value measured between the diaphragm plate and the planar substrate.

[0188] exist Figures 23-26 In this configuration, the protection terminal TG is connected to ground potential. The base terminal TB or diaphragm terminal TD provides the sensed electrostatic capacitance, and one of the sensor terminals is connected to the imaginary ground point of the amplifier circuit. This allows for the isolation of the current through the protection terminal TG and the current through the diaphragm terminal TD, while maintaining approximately the same voltage between the protection terminal TG and one of the sensor terminals.

[0189] Figure 27 and Figure 28 This illustrates an example of a non-inverting operational amplifier circuit. The operational amplifier OP is used as a voltage follower, and its output is directly connected to the original inverting input. The potential of the inverting input is approximately equal to that of the non-inverting input.

[0190] exist Figure 27 In this configuration, the protective electrode is maintained at approximately the same potential as the diaphragm plate. For example... Figure 27As shown, the diaphragm terminal TD is connected to the current source CC with a predetermined or known current. Furthermore, the current source CC can also be understood as a combination of current and voltage sources with internal impedance; in this case, the current is not constant, but is known, for example, through measurement using a shunt resistor or other known current measurement methods. Since the diaphragm plate and the protection electrode are at approximately the same potential here, there is substantially no current flowing between them. Because any leakage or capacitive current that might occur between the protection electrode and the base electrode is supplied by the amplifier OP without substantially affecting the output voltage, it also does not substantially affect the voltage or current between the diaphragm plate and the base electrode.

[0191] Set the electrostatic capacitance between the base terminal TB and the diaphragm terminal TD to C. S Let the electrostatic capacitance between the inverting (-) input and the non-inverting (+) input of the amplifier OP be C. i The electrostatic capacitance includes both the input electrostatic capacitance of the amplifier OP and the electrostatic capacitance between the diaphragm terminal TD and the protection terminal TG. Furthermore, the current source CC is assumed to be the effective current J at frequency f. i Given an AC source, assume the open-loop gain of amplifier OP is A. The output voltage U of amplifier OP. o As shown below.

[0192] [Formula 2]

[0193]

[0194] Thus, C i The effect is correspondingly reduced in terms of the amplifier's open-loop gain A. Since the electrostatic capacitance between the base terminal TB and the protection terminal TG is also connected between the amplifier's output terminal OP and the ground terminal, it has almost no effect on the output voltage, and therefore will not affect the output voltage either.

[0195] exist Figure 28 In this configuration, the protective electrode is maintained at approximately the same potential as the base electrode. For example... Figure 28 As shown, the base terminal TB is connected to the current source CC with a predetermined or known current. Since the base electrode and the protection electrode are at approximately the same potential here, there is no substantial current flowing between them. Because any leakage or capacitive current that might occur between the protection electrode and the diaphragm is supplied by the amplifier OP without substantially affecting the output voltage, it has no substantial effect on the voltage or current between the diaphragm and the base electrode.

[0196] exist Figure 27 and Figure 28Since the protection terminal TG is connected to the output of the amplifier OP, it is configured to follow the potential of one of the terminals of the sensor, thus maintaining a level where the current between the protection terminal TG and one of the terminals of the sensor can be ignored.

[0197] The invention has been fully described with reference to the accompanying drawings and in connection with preferred embodiments, but various modifications and variations will be apparent to those skilled in the art. Such modifications and variations are to be understood as included therein, provided they do not depart from the scope of the invention as defined by the claims.

[0198] Industrial availability

[0199] This invention enables the construction of a pressure sensor that can suppress the effects of interference and perform high-precision pressure measurements, and is therefore extremely useful in industry.

[0200] Explanation of reference numerals in the attached figures

[0201] 1. Pressure sensor structure; 10. Protective substrate; 21. Electrically insulating layer; 22. Base electrode; 23. Base conductive layer; 24. Second protective electrode layer; 25. Second base electrode; 30. Sidewall layer; 31, 33. Electrically insulating layer; 32. Protective electrode layer; 34. Base electrode; 25a, 34a. Trench; 40. Diaphragm plate; 45. Passivation film; G. Gap.

Claims

1. A pressure sensor configuration for detecting a change in electrostatic capacitance between electrodes, wherein the pressure sensor configuration comprises: a sensor main body including a diaphragm plate functioning as a sensing electrode, a base electrode opposite the diaphragm plate, and a side wall layer including a protective electrode layer and an upper side protective electrically insulating layer and a lower side protective electrically insulating layer electrically insulating the protective electrode layer, a gap between the diaphragm plate and the base electrode being maintained by the upper side protective electrically insulating layer; and a protective substrate of electric conductivity for supporting the sensor main body, the protective substrate being electrically connected to the protective electrode layer and functioning as a protective electrode together with the protective electrode layer, an electrically insulating layer electrically insulating the protective substrate being provided between the protective substrate and the sensor main body, the base electrode and the protective electrode layer being provided in the same layer and electrically isolated from each other, a second base electrode and a second protective electrode layer being provided in the same layer and electrically isolated from each other between the electrically insulating layer and the sensor main body, and the second base electrode being electrically connected to the base electrode.

2. The pressure sensor configuration according to claim 1, wherein a passivation film is provided on an outer surface of the sensor main body and the protective substrate.

3. The pressure sensor configuration according to claim 1, wherein a groove for relaxing stress is formed in at least one of the diaphragm plate, the upper side protective electrically insulating layer, the protective electrode layer, the lower side protective electrically insulating layer, and the protective substrate.

4. The pressure sensor configuration according to claim 1, wherein the lower side protective electrically insulating layer, the protective electrode layer, and the upper side protective electrically insulating layer are formed in a frame shape along a periphery of the diaphragm plate, a distance Wl between inner side edges and a distance W6 between outer side edges of the lower side protective electrically insulating layer, a distance W2 between inner side edges and a distance W5 between outer side edges of the protective electrode layer, and a distance W3 between inner side edges and a distance W4 between outer side edges of the upper side protective electrically insulating layer satisfy the following formulae: Wl < W2 < W3 and W4 < W5 < W6.

5. The pressure sensor configuration according to claim 1, wherein the lower side protective electrically insulating layer is formed in a plate shape larger than an outer shape of the diaphragm plate, the protective electrode layer and the upper side protective electrically insulating layer are formed in a frame shape along a periphery of the diaphragm plate, and a distance W6 between outer side edges of the lower side protective electrically insulating layer, a distance W2 between inner side edges and a distance W5 between outer side edges of the protective electrode layer, and a distance W3 between inner side edges and a distance W4 between outer side edges of the upper side protective electrically insulating layer satisfy the following formulae: W2 < W3 and W4 < W5 < W6.

6. The pressure sensor configuration according to claim 1, wherein at least a part of the upper side protective electrically insulating layer and the lower side protective electrically insulating layer is formed of silicon dioxide.

7. A pressure sensor device, wherein the pressure sensor device comprises: the pressure sensor configuration according to any one of claims 1 to 6. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ an integrated circuit that processes a signal from the pressure sensor configuration; a circuit substrate that mounts the integrated circuit and the pressure sensor configuration; and a housing member made of metal or synthetic resin that houses the integrated circuit and the pressure sensor configuration together with the circuit substrate.

8. A manufacturing method of a pressure sensor configuration according to any one of claims 1 to 6, wherein the manufacturing method comprises the following steps: a) forming a lower substrate including a base electrode; b) forming an upper substrate including a diaphragm sheet functioning as a sensing electrode; c) joining the lower substrate and the upper substrate; d) shaping the lower substrate and the upper substrate into a stepped shape; and e) forming a passivation film on an outer side surface of the lower substrate and the upper substrate after the shaping, the lower substrate forming step a) comprises the following steps: al) sequentially forming a lower-side protective electrically insulating layer and a conductive layer on a conductive lower substrate; and a2) etching the conductive layer to thereby form a base electrode and a protective electrode layer, the upper substrate forming step b) comprises the following steps: bl) forming an electrically insulating layer on a conductive upper substrate; and b2) etching the electrically insulating layer to thereby form an upper-side protective electrically insulating layer. ​

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