Pressure Sensors

Abstract

The present invention provides a pressure sensor having a plurality of detection parts in a stacking direction and having improved detection accuracy. The pressure sensor (10) of the present invention comprises: a membrane (22) that generates deformation corresponding to pressure; a first measurement layer (40) formed on the membrane (22); an intermediate insulating layer (50) formed on the first measurement layer (40); and a second measurement layer (60) formed on the intermediate insulating layer (50). The first measurement layer (40) and the second measurement layer (60) respectively include a first detection part (42) and a second detection part (62) for detecting deformation of the membrane. The distance from the surface of the membrane (22) to the second detection part (62) is within 30 μm.

Description

Technical Field

[0001] The present invention relates to a pressure sensor for detecting pressure based on deformation of a membrane. Background Art

[0002] There is a known pressure sensor that uses the piezoresistive effect to detect the strain of a membrane (also called a diaphragm) by a change in resistance. In such a pressure sensor, the strain caused by the deformation of the membrane is detected by a change in resistance of a resistor provided on the membrane.

[0003] In order to improve the reliability of such a pressure sensor, for example, Patent Document 1 listed below proposes stacking a plurality of pressure detection units.

[0004] However, in the conventional pressure sensor in which a plurality of detection parts are stacked, the detection parts are formed on the surface of a rigid plate, and the rigid plates are stacked to form the pressure sensor. This does not take into account the distance from the membrane surface to the detection part, and thus there is a problem in detection accuracy.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2018-40726 Summary of the invention

[0008] Problems to be solved by the invention

[0009] The present invention has been made in view of such actual circumstances, and an object of the present invention is to provide a pressure sensor having a plurality of detection sections in a stacking direction and having improved detection accuracy.

[0010] Technical solutions to solve problems

[0011] The present inventors conducted intensive studies on a pressure sensor having a plurality of detection sections in a stacking direction and having improved detection accuracy, and as a result, found that the detection accuracy can be improved by shortening the distance from the surface of the membrane to the detection section of the second gauge layer, thereby completing the present invention.

[0012] That is, the present invention provides a pressure sensor having:

[0013] a membrane that deforms in response to the pressure;

[0014] a first measurement layer formed on the film;

[0015] an intermediate insulating layer formed on the first measurement layer; and

[0016] a second measurement layer formed on the intermediate insulating layer,

[0017] The first measurement layer and the second measurement layer include a first detection unit and a second detection unit for detecting deformation of the film, respectively.

[0018] The distance from the surface of the film to the second detection portion is within 30 μm.

[0019] According to the experiment conducted by the inventors, if the distance from the surface of the film to the second detection unit is within 30 μm, the distance from the surface of the film to the first detection unit is also within 30 μm, and the stress (strain) detected by these detection units becomes approximately the same. As a result, the output of the detection signal detected by both the first and second detection units becomes approximately the same. Therefore, for example, by comparing and monitoring the first detection signal detected by the first detection unit and the second detection signal detected by the second detection unit, it is possible to easily detect a failure of one detection unit and to achieve an improvement in detection accuracy.

[0020] In addition, in the pressure sensor of the present invention, the first measuring layer, the intermediate insulating layer, and the second measuring layer can be easily formed thinly by a thin film forming method such as sputtering or vapor deposition, thereby achieving miniaturization and cost reduction of the pressure sensor.

[0021] Preferably, the thickness of each of the first measurement layer, the intermediate insulating layer, and the second measurement layer is 10 μm or less. By setting such a thickness relationship, it becomes easy to set the distance from the surface of the film to the second detection part within 30 μm.

[0022] When the film is made of a conductive material such as metal, it is preferred that a base insulating layer having a thickness of 10 μm or less is formed between the film and the first measurement layer. By forming the base insulating layer, the insulation between the first measurement layer and the film is ensured, and the detection accuracy of the first detection unit of the first measurement layer is improved.

[0023] An electrode layer covering and connecting a portion of the first measurement layer and a portion of the second measurement layer may also be formed on the film, and the thickness of the electrode layer is preferably 10 μm or less. By forming an electrode layer having such a structure, at least a portion of the wiring used to be individually taken out from each measurement layer can be shared, and the take-out wiring can be simplified.

[0024] Alternatively, when viewed from the normal direction of the film, the pattern configuration of the first measurement layer and the pattern configuration of the second measurement layer are substantially the same. With this configuration, the position of the first detection portion of the first positioning portion and the position of the second detection portion of the second positioning portion are substantially the same, the stress caused by the pressure applied to the film is detected at substantially the same position, and the accuracy of the detection signal is further improved.

[0025] Alternatively, the pattern arrangement of the first measurement layer and the pattern arrangement of the second measurement layer may be offset in the rotation direction when viewed from the normal direction of the film. This arrangement makes it easy to offset the position of the electrode portion for extracting the detection signal from each measurement layer.

[0026] Alternatively, the pressure sensor of the present invention further comprises: a comparison unit that compares and monitors a first detection signal detected by the first detection unit and a second detection signal detected by the second detection unit. By using the comparison unit to compare the first detection signal and the second detection signal, a failure of one detection unit can be easily detected, and the detection accuracy can be improved.

[0027] Alternatively, the pressure sensor of the present invention may further include: a switching unit that switches and outputs a first detection signal detected by the first detection unit and a second detection signal detected by the second detection unit. By configuring in this way, for example, when a detection unit of one measurement layer fails, the detection unit of another measurement layer is switched, thereby improving the durability and redundancy of the pressure sensor.

[0028] In addition, it is also possible that other measurement layers are stacked on the second measurement layer via another intermediate insulating layer. By configuring in this way, the durability and redundancy of the pressure sensor are further improved. Preferably, the distance from the surface of the membrane to the detection portion of the other measurement layer is within 50 μm. If the distance to the detection portion is within the range of the specified distance, the stress (strain) detected by the detection portion is not significantly different from the stress (strain) detected by the first detection portion and the second detection portion, and can be detected with higher accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic cross-sectional view of a pressure sensor according to an embodiment of the present invention.

[0030] Figure 2A yes Figure 1 An enlarged cross-sectional view of the portion shown in II.

[0031] Figure 2B Another embodiment of the present invention is Figure 2A The corresponding part is an enlarged cross-sectional view.

[0032] Figure 2C Another embodiment of the present invention is Figure 2A The corresponding part is an enlarged cross-sectional view.

[0033] Figure 3 It is shown along Figure 2A A schematic diagram of the pattern arrangement of the first measurement layer along line III-III is shown.

[0034] Figure 4A It is shown along Figure 2A A schematic diagram of the pattern arrangement of the second measurement layer for line IV-IV is shown.

[0035] Figure 4B This is a schematic diagram showing a pattern arrangement of a second measurement layer according to another embodiment of the present invention.

[0036] Figure 5 This is a graph showing the relationship between the distance (position) from the film surface and the stress according to an experiment conducted by the present inventors.

[0037] Figure 6 This is a circuit diagram showing an example of use of the pressure sensor according to one embodiment of the present invention.

[0038] Figure 7 This is a circuit diagram showing an example of use of a pressure sensor according to another embodiment of the present invention. DETAILED DESCRIPTION

[0039] Hereinafter, the present invention will be described based on the embodiments shown in the drawings.

[0040] First embodiment

[0041] like Figure 1 As shown, the pressure sensor 10 has a membrane 22 that generates deformation corresponding to the pressure. In the present embodiment, the membrane 22 is formed by an end wall formed at one end of a hollow cylindrical core column (steam) 20. The other end of the core column 20 is an open end of the hollow portion, which is connected to the flow path 12b of the connecting member 12, and the fluid introduced into the flow path 12b is guided from the hollow portion of the core column 20 to the inner surface 22a of the membrane 22, and the fluid pressure acts on the membrane 22. The core column 20 is made of metal such as stainless steel.

[0042] Around the open end of the stem 20, a flange portion 21 is formed in a manner protruding outward from the axial core of the stem 20, and the flange portion 21 is sandwiched between the connecting member 12 and the pressing member 14, and the flow path 12b leading to the inner surface of the membrane 22 is sealed. The connecting member 12 has a threaded groove 12a for fixing the pressure sensor 10 to a pressure chamber or the like in which a fluid to be measured is sealed. By fixing the pressure sensor 10 to the pressure chamber or the like via the threaded groove 12a, the flow path 12b formed inside the connecting member 12 is airtightly connected to the inside of the pressure chamber in which the fluid to be measured exists.

[0043] On the upper surface of the pressing member 14, a circuit board 16 is mounted around the stem 20. The circuit board 16 has built-in components such as Figure 6 The comparators (comparison units) 80, 82, 84, Figure 7The switching switch (switching unit) 90 shown, or a circuit for outputting a detection signal, etc.

[0044] like Figure 1 As shown, the laminated sensor body 18 is formed on the outer surface 22b of the film 22. The laminated sensor body 18 and the circuit board 16 are connected via an intermediate wiring 72 (for example, wire bonding).

[0045] Next, the stacked sensor body 18 will be described. Figure 2A As shown, the laminated sensor body 18 includes a base insulating layer 30 formed in close contact with the outer surface 22 b of the film 22 , and a first gauge layer 40 formed in a predetermined pattern on the base insulating layer 30 .

[0046] The base insulating layer 30 is formed to cover substantially the entire outer surface 22b of the film 22, and is composed of, for example, silicon oxide, silicon nitride, silicon oxynitride, etc. The thickness of the base insulating layer 30 is preferably 10 μm or less, and more preferably 1 to 5 μm. The base insulating layer 30 can be formed on the outer surface 22b of the film 22 by, for example, a vapor deposition method such as CVD. In addition, when the outer surface 22b of the film 22 has insulating properties, the base insulating layer 30 may not be formed, and the first measurement layer 40 may be directly formed on the outer surface 22b of the film 22.

[0047] In the present embodiment, the stacked sensor body 18 further includes an intermediate insulating layer 50 formed in a predetermined pattern on the first measurement layer 40 , and a second measurement layer 60 formed in a predetermined pattern on the intermediate insulating layer 50 .

[0048] like Figure 3 As shown, the first measurement layer 40 has a first detection unit 42. The first detection unit 42 has first to fourth resistors R1 to R4, and these first to fourth resistors R1 to R4 are connected to form a Wheatstone bridge circuit via a first wiring layer 44. Figure 6 or Figure 7 2 shows a circuit diagram of the first detection unit 42 which is constituted by a Wheatstone bridge circuit formed by the first to fourth resistors R1 to R4.

[0049] like Figure 3 As shown, first electrode layers 46a to 46d are formed on the first wiring layer 44 between the first resistor R1 and the second resistor R2, between the second resistor R2 and the third resistor R3, between the third resistor R3 and the fourth resistor R4, and between the fourth resistor R4 and the first resistor R1, respectively.

[0050] The first to fourth resistors R1 to R4, the wiring layer 44, and the first electrode layers 46a to 46d can all be formed by patterning a conductive layer of the same material, and they constitute the first measurement layer 40. The first measurement layer 40 can be composed of, for example, Ni-Cr alloy, chromium oxide, chromium nitride, etc. The thickness of the first measurement layer 40 is preferably 10 μm or less, and more preferably 0.1 to 1 μm. The first measurement layer 40 can be formed by a thin film method such as sputtering.

[0051] The first to fourth resistors R1 to R4 are formed, for example, by patterning a conductor layer into a zigzag shape. The first wiring layer 44 is formed by patterning the conductor layer into a straight line or a curve. The first electrode layers 46 a to 46 d are obtained by patterning the conductor layer in a manner wider than the first wiring layer 44 .

[0052] The first to fourth resistors R1 to R4 are mounted on Figure 2A The film 22 shown is configured such that the resistance value changes according to the amount of strain at the position where the film 22 is deformed and strained by the fluid pressure. The electrode layers 46a to 46d do not necessarily have to be provided at the position where the film 22 is strained.

[0053] like Figure 2A As shown, the intermediate insulating layer 50 formed on the first measurement layer 40 is made of the same material as the base insulating layer 30, but it is not necessary to be made of the same material. For example, by making the base insulating layer 30 of silicon oxide and the intermediate insulating layer 50 of silicon nitride, there is a tendency that silicon oxide has stress in a compressive direction and silicon nitride has tensile stress, respectively. Therefore, by setting such a structure, there is an advantage that stress of each layer can be eliminated and defects such as film peeling can be reduced. The intermediate insulating layer 50 can be formed by the same method as the base insulating layer 30.

[0054] The intermediate insulating layer 50 is preferably patterned. This is because a portion of the surface of the first measurement layer 40 needs to be exposed. Figure 3 The resistors R1 to R4 of the first detection portion 42 of the first measurement layer 40 shown are preferably Figure 2A The intermediate insulating layer 50 shown covers all of the Figure 3 At least a portion of the first electrode layers 46a to 46d shown in FIG. 4 is preferably not covered by the intermediate insulating layer 50. The reason for this is that Figure 3 At least a portion of the first electrode layers 46a to 46d shown is formed via Figure 2A The extraction electrode layer 70 shown is connected to an intermediate wiring layer 72 .

[0055] The thickness of the intermediate insulating layer 50 is preferably 10 μm or less, and more preferably 1 to 5 μm. The thickness of the intermediate insulating layer 50 may be the same as or different from the thickness of the base insulating layer 30. For example, the thickness of the intermediate insulating layer 50 may be thinner than the thickness of the base insulating layer 30. By making the thickness different, insulation of at least one insulating layer is ensured, and redundancy is improved.

[0056] A second measurement layer 60 is formed on the intermediate insulating layer 50. In this embodiment, Figure 4A As shown, the second measurement layer 60 has a second detection unit 62. The second detection unit 62 has first to fourth resistors R11 to R14 similarly to the first detection unit 42, and these first to fourth resistors R11 to R14 are connected to form a Wheatstone bridge circuit via a second wiring layer 64. Figure 6 or Figure 7 2 shows a circuit diagram of the second detection unit 62 which is constituted by a Wheatstone bridge circuit formed by the first to fourth resistors R11 to R14.

[0057] like Figure 4A As shown, second electrode layers 66a to 66d are formed on the second wiring layer 64 between the first resistor R11 and the second resistor R12, between the second resistor R12 and the third resistor R13, between the third resistor R13 and the fourth resistor R14, and between the fourth resistor R14 and the first resistor R11, respectively.

[0058] The first to fourth resistors R11 to R14, the wiring layer 64, and the second electrode layers 66a to 66d can all be formed by patterning a conductive layer of the same material, and they constitute the second measurement layer 60. The second measurement layer 60 is made of, for example, the same material as the first measurement layer 40, but it is not necessarily the same material. By making the second measurement layer 60 and the first measurement layer 40 of the same material, there is an advantage that a detection unit with substantially the same characteristics is easily formed and manufacturing becomes easy, and by making the second measurement layer 60 and the first measurement layer 40 of different materials, there is an advantage that redundancy is improved.

[0059] The thickness of the second measurement layer 60 is preferably 10 μm or less, and more preferably 0.1 to 1 μm. The thickness of the second measurement layer 60 is preferably the same as the thickness of the first measurement layer 40, but may be different. By making the thickness of the second measurement layer 60 and the first measurement layer 40 the same, there is an advantage of easily forming a detection unit with substantially the same characteristics, and by making the thickness of the second measurement layer 60 and the first measurement layer 40 different, there is an advantage of improved redundancy.

[0060] The second measurement layer 60 can be formed by the same thin film method as the first measurement layer 40, but it is not necessarily the same method. By making the second measurement layer 60 and the first measurement layer 40 the same method, there is an advantage that it is easy to form a detection unit with substantially the same characteristics and manufacturing becomes easy, and by making the second measurement layer 60 and the first measurement layer 40 different methods, there is an advantage that redundancy is improved.

[0061] The first to fourth resistors R11 to R14 are formed, for example, by patterning a conductor layer into a zigzag shape. The second wiring layer 64 is formed by patterning the conductor layer into a straight line or a curved line. The second electrode layers 66 a to 66 d are obtained by patterning the conductor layer in a manner wider than the second wiring layer 64 .

[0062] The first to fourth resistors R11 to R14 are mounted on Figure 2A The film 22 shown is deformed and strained by the fluid pressure, and is configured so that the resistance value changes according to the amount of strain. The electrode layers 66a to 66d do not necessarily have to be installed at the position where the film 22 is strained.

[0063] In this embodiment, if Figure 3 and Figure 4A As shown, from Figure 2A The normal direction of the film 22 shown (with Figure 3 and Figure 4A When viewed from the direction perpendicular to the paper surface, the first resistor R1 of the first detection unit 40 and the first resistor R11 of the second detection unit 60 are arranged at substantially the same position. Figure 2A When viewed in the normal direction of the film 22 shown, the second resistor R2 of the first detection section 40 and the second resistor R12 of the second detection section 60 are arranged at substantially the same position.

[0064] Moreover, from Figure 2A When viewed from the normal direction of the film 22 shown in FIG. 1 , the third resistor R3 of the first detection unit 40 and the third resistor R13 of the second detection unit 60 are arranged at substantially the same position. Figure 2A When viewed in the normal direction of the film 22 shown, the fourth resistor R4 of the first detection section 40 and the fourth resistor R14 of the second detection section 60 are arranged at substantially the same position.

[0065] In addition, in the present embodiment, the substantially same position refers to the substantially same position, and may not necessarily be the completely same position, and may be located closer than the resistors located at adjacent positions connected by the wiring layer 44 or 64. For example, the resistors R4 and R14 are located closer than the resistors R1, R11, R3, and R13 located at adjacent positions, and can be called substantially the same position.

[0066] In this embodiment, if Figure 2A As shown, an extraction electrode layer 70 that covers and connects a portion of the first measurement layer 40 and a portion of the second measurement layer 60 is formed on the film 22. The extraction electrode layer 70 is connected to an intermediate wiring 72.

[0067] The extraction electrode layer 70 is composed of a metal (including alloys) containing at least one of Au, Pt, W, Al, and Ni, and can be formed by a thin film method such as sputtering. Since it is not necessary to form a film thinner than the measurement layers 40 and 60, it can also be formed by a plating method. The thickness of the extraction electrode layer 70 is preferably 0.1 to 4 μm.

[0068] In addition, a contact layer may be interposed between the first electrode layers 46a to 46d and the extraction electrode layer 70. As the contact layer, a metal layer containing at least one of Ti, Cr, Ni, and Mo may be exemplified. The thickness of the contact layer may be sufficiently thinner than the thickness of the electrode layer 70. In addition, the extraction electrode layer 70 may not be used and the wiring layer 72 may be connected to the electrode layer 70. Figure 3 The first electrode layers 46a-46d are shown to be directly connected.

[0069] like Figure 6 As shown, in this embodiment, the resistors R1 to R4 of the first detection unit 42 are connected in a manner to form a Wheatstone bridge circuit, and the resistors R11 to R14 of the second detection unit 62 are also connected in a manner to form a Wheatstone bridge circuit. The resistors R1 and R2 of the first detection unit 42 are connected to the power line VDD, and the resistors R11 and R12 of the second detection unit 62 are also connected to the power line VDD.

[0070] The resistor R2 and the resistor R3 of the first detection unit 42 are connected to the ground GND, and the resistor R12 and the resistor R13 of the second detection unit 62 are also connected to the ground GND. In addition, the resistor R1 and the resistor R2 of the first detection unit 42 are connected to one input terminal of the first comparator 80 as a comparison unit, and the resistor R3 and the resistor R4 of the first detection unit 42 are connected to the other input terminal of the first comparator 80.

[0071] Similarly, the resistors R11 and R12 of the second detection unit 62 are connected to one input terminal of the second comparator 82 as a comparison unit, and the resistors R13 and R14 of the second detection unit 62 are connected to the other input terminal of the second comparator 82. The output terminal of the first comparator 80 and the output terminal of the second comparator 82 are respectively connected to two input terminals of the third comparator 84 as a comparison unit. The output terminal of the third comparator 84 is connected to a control device or the like as a pressure detection unit, which is not shown in the figure.

[0072] like Figure 3As shown in FIG. 4 , an electrode layer 46 b is connected between the resistor R2 and the resistor R3 of the first detection unit 42 via the wiring layer 44. Figure 4A As shown, the electrode layer 66b is connected between the resistor R12 and the resistor R13 of the second detection unit 62 via the wiring layer 64. Figure 6 As shown, the resistor R2 and the resistor R3 of the first detection unit 42 are connected to the ground GND, and the resistor R12 and the resistor R13 of the second detection unit 62 are also connected to the ground GND. Therefore, the electrode layer 46b of the first measurement layer 40 and the electrode layer 66b of the second measurement layer 60 can also be connected by, for example Figure 2A The extraction electrode layer 70 shown is directly connected to the Figure 1 The circuit board 16 shown is connected to ground GND.

[0073] In addition, similarly, Figure 3 As shown in FIG. 4 , an electrode layer 46d is connected between the resistor R1 and the resistor R4 of the first detection unit 42 via the wiring layer 44. Figure 4A As shown, an electrode layer 66d is connected between the resistor R11 and the resistor R14 of the second detection unit 62 via the wiring layer 64. Figure 6 As shown, the resistor R1 and the resistor R4 of the first detection unit 42 are connected to the power line VDD, and the resistor R11 and the resistor R14 of the second detection unit 62 are also connected to the power line VDD. Therefore, the electrode layer 46d of the first measurement layer 40 and the electrode layer 66d of the second measurement layer 60 can also be connected through, for example Figure 2A The extraction electrode layer 70 shown is directly connected to the Figure 1 The circuit board 16 shown is connected to the power supply line VDD.

[0074] Figure 3 and Figure 4A The other electrode layers 46a, 46c, 66a, 66c shown are Figure 1 The intermediate wirings 72 shown are connected to each other and are connected to the circuit board 16. Figure 6 The input terminals of the comparators 80, 82 are shown connected.

[0075] Next, Figure 1 The manufacturing method of the pressure sensor 10 shown in FIG. 1 is described below. First, a stem 20 is prepared. The stem 20 is made of, for example, stainless steel such as SUS316. Figure 2A As shown, the laminated sensor body 18 is formed on the outer surface 22 b of the membrane 22 of the stem 20 .

[0076] To form the stacked sensor body 18, first, the base insulating layer 30 is formed with a predetermined thickness by a thin film method such as CVD or sputtering on the outer surface 22b of the film 22 so as to cover the film 22. The base insulating layer 30 may be a silicon oxide film or a silicon nitride film.

[0077] Next, the first measurement layer 40 is formed in a predetermined pattern on the surface of the base insulating layer 30. The first measurement layer 40 includes a pressure detection portion (first detection portion 42), Figure 3 The resistors R1 to R4, the first wiring layer 44, and the first electrode layers 46a to 46d are shown. In this embodiment, the resistors R1 to R4, the first wiring layer 44, and the first electrode layers 46a to 46d are composed of Ni-Cr alloy films, etc., which can be single films or multilayer films, and the total thickness is less than 10μm.

[0078] The first measurement layer 40 is formed by a thin film method such as evaporation or sputtering. The first measurement layer 40 is patterned so as to form resistors R1 to R4, a first wiring layer 44, and first electrode layers 46a to 46d. Photolithography is used as a method for patterning. Specifically, a method such as peeling off, milling, and etching is used.

[0079] Next, an intermediate insulating layer 50 is formed on the patterned first measurement layer 40. The intermediate insulating layer 50 is formed to a predetermined thickness by a thin film method such as CVD or sputtering. The intermediate insulating layer 50 may be made of the same material as that of the base insulating layer 30, but it is not necessarily necessary to be the same.

[0080] Next, the second measurement layer 60 is formed in a predetermined pattern on the intermediate insulating layer 50. The second measurement layer 60 includes: a pressure detection unit (second detection unit 62); Figure 4A The resistors R11 to R14, the second wiring layer 64, and the second electrode layers 66a to 66d are shown. The material and formation method of the second measurement layer 60 are the same as those of the first measurement layer 40, but they do not necessarily have to be the same.

[0081] On the intermediate insulating layer 50, before or after the second measurement layer 60 is formed in a predetermined pattern, the intermediate insulating layer 50 is patterned to expose at least a portion of the electrode layers 46a to 46d formed on the first measurement layer 40. The method for patterning is the same as that for the base insulating layer 30, but it is not necessarily the same.

[0082] like Figure 2AAs shown, in a state where a portion of the first measurement layer 40 is exposed, an extraction electrode layer 70 is formed on the second measurement layer 60 of a prescribed pattern. The extraction electrode layer 70 may also connect a portion of the first measurement layer 40 and a portion of the second measurement layer 60, or may be formed only on a portion of the first measurement layer 40.

[0083] The extraction electrode layer 70 may be formed by a thin film method such as sputtering, but since it does not need to be formed thinner than the measurement layers 40 and 60 , it may be formed by a plating method or the like.

[0084] The surface of the laminated sensor body 18 thus formed may be covered with a protective layer except for the intermediate wiring 72. The protective layer may be, for example, an insulating layer formed by a thin film method or a resin coating.

[0085] In the pressure sensor 10 of the present embodiment, as Figure 2A As shown, the thickness of each of the base insulating layer 30, the first measurement layer 40, and the intermediate insulating layer 50 is 10 μm or less. Therefore, the distance from the outer surface 22 b of the film 22 to the second detection portion 62 of the second measurement layer 60 (in the normal direction of the film 22) can be set to 30 μm or less. In addition, the distance from the outer surface 22 b of the film 22 to the first detection portion 42 of the first measurement layer 42 is also within 10 μm and less than 30 μm.

[0086] According to the experimental results of the present inventors Figure 5 If the distance in the normal direction from the surface of the film 22 (outer surface 22b) toward the outside is less than 30 μm (0.03 mm), the stress acting on the laminated film formed on the surface of the film 22 is almost unchanged. Figure 3 The stress (strain) detected by the first detection portion 42 of the first measurement layer 40 shown in FIG. Figure 4A The stress (strain) detected by the second detection portion 62 of the second measurement layer 60 shown is almost the same.

[0087] As a result, the outputs of the detection signals detected by the first detection unit 42 and the second detection unit 62 are substantially the same. Figure 6 In the comparator 84 as the comparison unit shown, it is possible to compare and monitor the first detection signal detected by the first detection unit 42 and the second detection signal detected by the second detection unit 62. For example, when the difference between the input signals detected by the comparator 84 is greater than a predetermined value, a failure of one of the detection units 42 or 62 can be easily detected, and the detection accuracy can be improved.

[0088] Moreover, in the pressure sensor 10 of this embodiment, since the first measurement layer 40, the intermediate insulating layer 50 and the second measurement layer 60 can be easily formed thinly by a thin film forming method such as sputtering or evaporation, it becomes easy to achieve miniaturization and cost reduction of the pressure sensor 10.

[0089] Furthermore, in this embodiment, a base insulating layer 30 having a thickness of 10 μm or less is formed between the film 22 made of a conductive material such as metal and the first measurement layer 40. By forming the base insulating layer 30, the insulation between the first measurement layer 40 and the film 22 is ensured, and the detection accuracy of the first detection unit 42 of the first measurement layer 40 is improved.

[0090] Furthermore, in this embodiment, if Figure 2A As shown, by forming the extraction electrode layer 70 preferably with a thickness of 10 μm or less, at least a part of the wiring for extracting from each measurement layer 40 , 60 can be shared, and the extraction wiring 72 can be simplified.

[0091] In addition, in this embodiment, when viewed from the normal direction of the film 22, Figure 3 The pattern configuration of the first detection portion 42 of the first measurement layer 40 and Figure 4A The pattern arrangement of the second detection portion 62 of the second measurement layer 60 shown is substantially the same. With this configuration, each resistor R1 to R4 or R11 to R14 detects stress caused by pressure applied to the film 22 at substantially the same position, and the accuracy of the detection signal is further improved.

[0092] Furthermore, in the above-mentioned embodiment, when viewed from the normal direction of the film 22, Figure 3 The pattern arrangement of the first detection portion 42 of the first measurement layer 40 (arrangement of the resistors R1 to R4) and Figure 4A The pattern arrangement of the second detection portion 62 of the second measurement layer 60 shown (arrangement of the resistors R11 to R14 ) is slightly shifted.

[0093] However, in this embodiment, it is also possible to Figure 3 The pattern arrangement of the first detection part 42 of the first measurement layer 40 shown in FIG. 1 is substantially identical to the arrangement of the second detection part 62 of the second measurement layer 60. Figure 3 The second detection portion of the second measurement layer is formed by the same arrangement as the pattern arrangement of the first detection portion 42 of the first measurement layer 40 shown. However, in this case, it is preferable to stagger the arrangement pattern of the first electrode layer 46a to 46d and the arrangement pattern of the second electrode layer 66a to 66d. The purpose is to connect the extraction electrode 70 or the intermediate wiring 72 to each electrode layer 46a to 46d and 66a to 66d.

[0094] Second embodiment

[0095] like Figure 2B As shown, in the pressure sensor 10a of this embodiment, only the structure and function of the stacked sensor body 18a are different from those of the first embodiment, and the other structures and functions are the same as those of the first embodiment, and the description of the common parts is omitted.

[0096] like Figure 2B As shown, in this embodiment, the pattern of the second measurement layer 60 is different from that of the first embodiment, and a portion of the second measurement layer 60 is directly connected to a portion of the first measurement layer 40. As an example of a portion where a portion of the second measurement layer 60 is directly connected to a portion of the first measurement layer 40, for example, Figure 6 The electrode layer 46b of the first measurement layer 40 and the electrode layer 66b of the second measurement layer 60 are connected to the ground GND. In addition, as an example of a portion of the second measurement layer 60 directly connected to a portion of the first measurement layer 40, for example Figure 6 The electrode layer 46d of the first measurement layer 40 and the electrode layer 66d of the second measurement layer 60 are shown as portions connected to the power supply line VDD.

[0097] In this embodiment, it is not necessary to directly connect the electrode layer 46 b and the electrode layer 46 d of the first measurement layer 40 to the extraction electrode layer 70 or the intermediate wiring 72 , and it is sufficient to connect the electrode layer 66 b and the electrode layer 66 d of the second measurement layer 60 to the extraction electrode layer 70 or the intermediate wiring 72 .

[0098] Figure 3 and Figure 4A The other electrode layers 46a, 46c, 66a, 66c shown are Figure 1 The intermediate wirings 72 shown are connected to each other and are connected to the circuit board 16. Figure 6 The input terminals of the comparators 80, 82 are shown connected.

[0099] Third embodiment

[0100] like Figure 2C As shown, in the pressure sensor 10b of this embodiment, only the structure and function of the stacked sensor body 18b are different from those of the first embodiment, and the other structures and functions are the same as those of the first embodiment, and the description of the common parts is omitted.

[0101] like Figure 2CAs shown, in this embodiment, the pattern of the intermediate insulating layer 50 or the pattern of the extraction electrode layer 70 is different so that the first measurement layer 40 and the second measurement layer 60 are insulated. That is, in this embodiment, inside the stacked sensor body 18b, the first measurement layer 40 and the second measurement layer 60 are not directly connected, and are not indirectly connected via the extraction electrode layer 70. Therefore, relative to Figure 3 and Figure 4A Each of the electrode layers 46a-46d and 66a-66d shown is formed by Figure 2C The extraction electrode layer 70 shown may or may not be connected to an intermediate wiring 72 therethrough.

[0102] Fourth embodiment

[0103] like Figure 4B As shown, in the pressure sensor 10c of this embodiment, only the pattern arrangement of the second measurement layer 60a is different from that of the first embodiment, and the other structures and functions are the same as those of the first to third embodiments, and the description of the common parts is omitted.

[0104] like Figure 4B As shown, in this embodiment, from the film 22 (refer to Figure 1 ), the pattern configuration of the first detection unit 42 of the first measurement layer 40 and the pattern configuration of the second detection unit 62 of the second measurement layer 60a are offset in the rotation direction. In the present embodiment, the pattern configuration of the second measurement layer 60a is the same as the pattern configuration of the first measurement layer 40 except that the rotation angle is offset by a predetermined angle (approximately 90 degrees).

[0105] That is, in Figure 4B In FIG. 1 , if the second measurement layer 60a is rotated counterclockwise by a predetermined angle (approximately 90 degrees), the electrode layers 46a to 46d of the first measurement layer 40 overlap with the electrode layers 66a to 66d of the second measurement layer 60, and the resistors R1 to R4 of the first measurement layer 40 overlap with the resistors R11 to R14 of the second measurement layer 60. In addition, the wiring layer 44 also overlaps with the wiring layer 64. Figure 4B In the example shown, the pattern configuration of the second measurement layer 60a is displaced by a rotation angle of about 90 degrees relative to the pattern configuration of the first detection portion 42 of the first measurement layer 40, but is not limited to about 90 degrees. The rotation angle of the dislocation can also be freely changed within the range of 0 to 180 degrees, but in the case of a large dislocation, it is preferably about 60 to 120 degrees.

[0106] In this embodiment, the positions of the electrode layers 46a to 46d for extracting the detection signal from the detection unit 42 of the first measurement layer 40 and the positions of the electrode layers 66a to 66d for extracting the detection signal from the detection unit 62 of the second measurement layer 60a can be offset in the rotation direction. Therefore, wiring from each electrode layer 46a to 46d and 66a to 66d becomes easy.

[0107] Fifth embodiment

[0108] like Figure 7 As shown, the pressure sensor of this embodiment has no Figure 6 Except for the comparators 82 and 84 shown in the figure and the switch (switching means) 90, the above are the same as those in the first to fourth embodiments, and the description of the common parts will be omitted.

[0109] like Figure 7 As shown, in this embodiment, the resistor R1 and the resistor R2 of the first detection unit 42 are connected to the first input terminal 91 of the switch 90, and the resistor R3 and the resistor R4 of the first detection unit 42 are connected to the third input terminal 93 of the switch 90. Similarly, the resistor R11 and the resistor R12 of the second detection unit 62 are connected to the second input terminal 92 of the switch 90, and the resistor R13 and the resistor R14 of the second detection unit 62 are connected to the fourth input terminal 94 of the switch 90.

[0110] In the switching switch 90, the first output terminal 95 is connected to one input terminal of the comparator 80, and the second output terminal 96 is connected to the other input terminal of the comparator 80. The switching switch 90 can simultaneously realize the connection between the first input terminal 91 and the first output terminal 95 and the connection between the third input terminal 93 and the second output terminal 96. In addition, the switching switch 90 is built into, for example Figure 1 The control circuit of the circuit substrate 16 shown in the figure is controlled and can be controlled from Figure 7 The state shown in FIG. 1 is switched to a state in which the second input terminal 92 and the first output terminal 95 are connected and the fourth input terminal 94 and the second output terminal 96 are connected. Figure 1 The control circuit of the circuit board 16 shown can also perform reverse switching of the switches.

[0111] In the present embodiment, the first detection signal detected by the first detection unit 42 and the second detection signal detected by the second detection unit 62 can be switched by the switch 90 and input to the comparator 80. With such a configuration, for example, when a detection unit 42 or 62 of one measurement layer 40 or 60 fails, the detection unit of the other measurement layer is switched, thereby improving the durability and redundancy of the pressure sensor.

[0112] In addition, the present invention is not limited to the above-mentioned embodiment, and various changes can be made within the scope of the present invention.

[0113] For example, other measurement layers may be stacked on the second measurement layer 60 or 60a via another intermediate insulating layer 50. By configuring in this way, the durability and redundancy of the pressure sensor are further improved. In this case, it is preferred that the distance from the outer surface 22b of the membrane 22 to the detection portion of the other measurement layer is within 50 μm.

[0114] like Figure 5 As shown, if the distance (position) from the membrane surface is less than 50 μm (0.05), the stress (strain) detected by the detection unit has no significant difference (within 1%) from the stress (strain) detected by the first detection unit 42 and the second detection unit 62, and detection can be performed with higher accuracy.

[0115] Explanation of symbols

[0116] 10, 10a, 10b…pressure sensor

[0117] 12…Connecting components

[0118] 12a…Thread groove

[0119] 12b…Flow path

[0120] 14…Pressing member

[0121] 16…Circuit board

[0122] 18, 18a, 18b…Laminated sensor body

[0123] 20…Heart Pillar

[0124] 21…Flange

[0125] 22…Membrane

[0126] 22a…Inner surface

[0127] 22b…Outer surface

[0128] 30…Base insulation layer

[0129] 40…First measurement layer

[0130] 42…First detection unit

[0131] 44…First wiring layer

[0132] 46a to 46d ... first electrode layer

[0133] 50…Intermediate insulation layer

[0134] 60, 60a…Second measurement layer

[0135] 62…Second detection unit

[0136] 64…Second wiring layer

[0137] 66a~66d...second electrode layer

[0138] 70…Remove the electrode layer

[0139] 72…Intermediate wiring

[0140] 80, 82, 84…Comparator (comparison unit)

[0141] 90...Switch (switching unit)

[0142] R1, R11…first resistor

[0143] R2, R12…second resistor

[0144] R3, R13…the third resistor

[0145] R4, R14...the fourth resistor.

Claims

1. A pressure sensor, wherein: have: a membrane that deforms in response to the pressure; a first measurement layer formed on the film; an intermediate insulating layer formed on the first measurement layer; as well as a second measurement layer formed on the intermediate insulating layer, The first measurement layer and the second measurement layer include a first detection unit and a second detection unit for detecting deformation of the film, respectively. The distance from the surface of the film to the second detection part is within 30 μm, The device further includes an electrode layer that contacts an upper surface of the first measurement layer and an upper surface of the second measurement layer that are exposed from the intermediate insulating layer and the second measurement layer, and connects the first measurement layer and the second measurement layer.

2. The pressure sensor according to claim 1, wherein: The thickness of each of the first measurement layer, the intermediate insulating layer, and the second measurement layer is 10 μm or less.

3. The pressure sensor according to claim 1 or 2, wherein: The film is conductive, and a base insulating layer having a thickness of 10 μm or less is formed between the film and the first measurement layer.

4. The pressure sensor according to claim 1 or 2, wherein: The thickness of the electrode layer is less than 10 μm.

5. The pressure sensor according to claim 1 or 2, wherein: When viewed from a normal direction of the film, the pattern configuration of the first measurement layer and the pattern configuration of the second measurement layer are substantially the same.

6. The pressure sensor according to claim 1 or 2, wherein: When viewed from the normal direction of the film, the pattern configuration of the first measurement layer and the pattern configuration of the second measurement layer are offset in the rotation direction.

7. The pressure sensor according to claim 1 or 2, wherein: The device further includes a comparison unit that compares and monitors a first detection signal detected by the first detection unit and a second detection signal detected by the second detection unit.

8. The pressure sensor according to claim 1 or 2, wherein: The device further includes a switching unit that switches and outputs a first detection signal detected by the first detection unit and a second detection signal detected by the second detection unit.

9. The pressure sensor according to claim 1 or 2, wherein: Another measurement layer is stacked on the second measurement layer via another intermediate insulating layer, and the distance from the surface of the film to the detection portion of the other measurement layer is within 50 μm.

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