Chip for pressure sensor, pressure sensor, and manufacturing method thereof

Abstract

The present invention provides a chip for a pressure sensor that can integrate two diaphragms on the same chip without complicating the manufacturing process. The chip (20) for a pressure sensor includes: a base (25); a first layer (21) joined to the upper surface (25A) of the base (25) and having an opening (21B); a second layer (22) joined to the upper surface (21A) of the first layer (21); a third layer (23) joined to the upper surface (22A) of the second layer (22) and having an opening (23B); and a fourth layer (24) joined to the upper surface (23A) of the third layer (23) and having an opening (24B). The second layer (22) includes a first diaphragm (26) sandwiched between the opening (21B) and the opening (23B). The fourth layer (24) includes a second diaphragm (27) sandwiched between the opening (23B) and a space communicating with the outside. The upper end of the opening (24B) communicates with the outside. The lower end of the opening (24B) communicates with the opening (23B). The opening (21B) is sealed. The pressure in the opening (21B) is lower than the pressure in the opening (23B).

Description

Technical Field

[0001] The present invention relates to a chip for a pressure sensor for measuring pressure from the outside, a pressure sensor including the chip for a pressure sensor, and a method for manufacturing them. Background Art

[0002] As one type of pressure sensor, a differential pressure sensor for measuring the pressure difference between two pressures is known. For example, a differential pressure sensor is used to measure the pressure difference between the upstream and downstream of a throttling structure in a flow path tube having a throttling structure. According to the relational expression between the flow rate and the pressure difference described in JIS Z8762 of the JIS standard, the measured pressure difference can be converted into a flow rate.

[0003] However, in order to perform the above conversion, in addition to the pressure difference, static pressures such as gauge pressure based on atmospheric pressure and absolute pressure based on a vacuum state are also required.

[0004] Patent Document 1 discloses a pressure sensor including a differential pressure sensor chip capable of measuring a pressure difference and a static pressure sensor chip capable of measuring a static pressure.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2003-42878 Summary of the Invention

[0008] Problems to be Solved by the Invention

[0009] However, in the case of the pressure sensor disclosed in Patent Document 1, since the differential pressure sensor chip and the static pressure sensor chip are separated from each other, it becomes large-sized.

[0010] In order to miniaturize the pressure sensor, it is considered to integrate the differential pressure sensor and the static pressure sensor on the same chip. However, as described in Patent Document 1, there are the following problems with such integration.

[0011] In a pressure sensor, pressure is measured based on the amount of deflection of a diaphragm. The diaphragm provided in the static pressure sensor needs to have a thicker wall thickness than the diaphragm provided in the differential pressure sensor so as to withstand a larger pressure. In the pressure sensor disclosed in Patent Document 1, in order to integrate the differential pressure sensor and the static pressure sensor on the same chip, it is necessary to change the thickness of the diaphragm of the differential pressure sensor and the diaphragm of the static pressure sensor on the same semiconductor substrate. However, in order to form diaphragms of different thicknesses on the same semiconductor substrate, a complicated manufacturing process is required.

[0012] Therefore, in the pressure sensor disclosed in Patent Document 1, miniaturization is achieved by arranging the differential pressure sensor chip and the static pressure sensor chip close to each other on the same base. However, in the pressure sensor disclosed in Patent Document 1, since the differential pressure sensor chip and the static pressure sensor chip are different chips and not integrated on the same chip, there is a limit to the miniaturization of the pressure sensor.

[0013] Accordingly, an object of the present invention is to solve the above problems and provide a pressure sensor chip capable of integrating two diaphragms on the same chip without complicating the manufacturing process.

[0014] Solutions for Solving the Problems

[0015] To achieve the above object, the present invention is configured as follows.

[0016] A pressure sensor chip according to one aspect of the present invention includes a first diaphragm and a second diaphragm for pressure measurement, wherein

[0017] the pressure sensor chip includes:

[0018] a base;

[0019] a first layer joined to the base and having a first opening;

[0020] a second layer joined to the side of the first layer opposite to the side where the base is located;

[0021] a third layer joined to the side of the second layer opposite to the side where the first layer is located and having a second opening; and

[0022] a fourth layer joined to the side of the third layer opposite to the side where the second layer is located and having a third opening,

[0023] the second layer includes the first diaphragm sandwiched between the first opening and the second opening,

[0024] the fourth layer includes the second diaphragm sandwiched between the second opening and a space communicating with the outside,

[0025] a first end of the third opening communicates with the outside,

[0026] a second end of the third opening communicates with the second opening,

[0027] the first opening is sealed,

[0028] the pressure in the first opening is lower than the pressure in the second opening.

[0029] Effects of the Invention

[0030] According to the present invention, two diaphragms can be integrated on the same chip without complicating the manufacturing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a longitudinal sectional view of a pressure sensor according to the first embodiment of the present invention.

[0032] Figure 2 is Figure 1 a top view of a pressure sensor chip included in the pressure sensor.

[0033] Figure 3 is Figure 1 a sectional view taken along line A - A in

[0034] Figure 4 is Figure 1 a sectional view taken along line B - B in

[0035] Figure 5 is Figure 1 a sectional view taken along line C - C in

[0036] Figure 6 is a diagram showing Figure 1 the equivalent circuit of the pressure sensor chip.

[0037] Figure 7 is a longitudinal sectional view of a pressure sensor in which the thickness of the fourth layer is thinner than that of the second layer.

[0038] Figure 8 is a longitudinal sectional view of a pressure sensor according to the second embodiment of the present invention.

[0039] Figure 9 is Figure 8 a top view of a pressure sensor chip included in the pressure sensor.

[0040] Figure 10 is Figure 8 a sectional view taken along line D - D in

[0041] Figure 11 is Figure 8 a sectional view taken along line E - E in

[0042] Figure 12 is Figure 8 a sectional view taken along line F - F in

[0043] Figure 13 is a longitudinal sectional view of a pressure sensor according to the third embodiment of the present invention.

[0044] Figure 14 is a longitudinal sectional view of a pressure sensor according to the fourth embodiment of the present invention. Detailed implementation mode

[0045] The chip for a pressure sensor according to one technical solution of the present invention includes a first diaphragm and a second diaphragm for pressure measurement. Among them,

[0046] This chip for a pressure sensor includes:

[0047] A base;

[0048] A first layer, which is joined to the base and has a first opening;

[0049] A second layer, which is joined to the side of the first layer opposite to the side where the base is located;

[0050] A third layer, which is joined to the side of the second layer opposite to the side where the first layer is located and has a second opening; and

[0051] A fourth layer, which is joined to the side of the third layer opposite to the side where the second layer is located and has a third opening,

[0052] The second layer includes the first diaphragm sandwiched between the first opening and the second opening,

[0053] The fourth layer includes the second diaphragm sandwiched between the second opening and a space communicating with the outside,

[0054] A first end of the third opening communicates with the outside,

[0055] A second end of the third opening communicates with the second opening,

[0056] The first opening is sealed,

[0057] The pressure in the first opening is lower than the pressure in the second opening.

[0058] According to this structure, the first diaphragm is acted on by the pressure from the first opening and the pressure from the second opening. Thus, it is possible to measure the pressure based on the pressure in the sealed first opening by using the first diaphragm. In addition, the second diaphragm is acted on by the pressure from the second opening and the pressure from the outside. Thus, it is possible to measure the pressure difference between these two pressures by using the second diaphragm. That is to say, according to this structure, it is possible to measure the pressure difference between two pressures and the absolute pressure based on the vacuum state, etc. by using one chip for a pressure sensor. Moreover, two diaphragms are integrated on the same chip for a pressure sensor. Therefore, it is possible to miniaturize the chip for a pressure sensor.

[0059] According to this structure, the first diaphragm and the second diaphragm are provided in different layers. Therefore, the thicknesses of the second layer provided with the first diaphragm and the fourth layer provided with the second diaphragm can be set to different thicknesses without complicating the manufacturing process.

[0060] According to this structure, the interior of the first opening is vacuum or substantially vacuum. Therefore, the first diaphragm can function as a diaphragm for absolute pressure measurement.

[0061] The thickness of the fourth layer is thinner than that of the second layer. According to this structure, since the second diaphragm is thinner than the first diaphragm, the second diaphragm can be flexed by a small pressure difference. When the pressure in the first opening, which is the reference pressure of the first diaphragm, is low, the amount of flexure of the first diaphragm becomes large. Thus, the first diaphragm may rupture. According to this structure, since the first diaphragm is thicker than the second diaphragm, the possibility of the first diaphragm rupturing can be reduced.

[0062] The base, the second layer, and the fourth layer are conductors, and the first layer and the third layer are electrically insulating insulators. According to this structure, the pressure sensor chip can function as a capacitive type.

[0063] In a plan view, the first diaphragm does not overlap with the second diaphragm. According to this structure, the influence of the pressure in the first opening on the second diaphragm via the second layer and the second opening is suppressed. Thus, the measurement of the pressure difference achieved by the second diaphragm can be performed with high precision.

[0064] In a plan view, the first diaphragm overlaps with the second diaphragm. According to this structure, since the first diaphragm is larger, the sensitivity of the first diaphragm can be increased.

[0065] A pressure sensor according to one aspect of the present invention includes:

[0066] The pressure sensor chip; and

[0067] A covering portion that covers the pressure sensor chip,

[0068] The covering portion includes: a fourth opening that communicates the third opening with the outside; and a fifth opening that exposes the side of the fourth layer opposite to the side where the third layer is located to the outside,

[0069] The second diaphragm is sandwiched between the second opening and the fifth opening.

[0070] According to this structure, the pressure sensor chip can be protected by the covering portion.

[0071] The covering portion includes: a cylindrical first cap that protrudes from around the fourth opening portion so as to be separated from the pressure sensor chip; and a cylindrical second cap that protrudes from around the fifth opening portion so as to be separated from the pressure sensor chip. With this structure, it is possible to easily connect the pressure sensor to the outside by means of the first cap and the second cap.

[0072] A method for manufacturing a pressure sensor chip according to one aspect of the present invention includes:

[0073] A first step, in which a first layer having a first opening portion formed with a pattern is joined to a base;

[0074] A second step, in which a second layer is joined to a surface of the first layer on the side opposite to the side where the base is located;

[0075] A third step, in which a third layer having a second opening portion formed with a pattern is joined to a surface of the second layer on the side opposite to the side where the first layer is located so as to form a first diaphragm sandwiched between the first opening portion and the second opening portion in the second layer; and

[0076] A fourth step, in which a fourth layer having a third opening portion formed with a pattern is joined to a surface of the third layer on the side opposite to the side where the second layer is located, so that a first end portion of the third opening portion communicates with the outside, a second end portion of the third opening portion communicates with the second opening portion, and a second diaphragm sandwiched between the second opening portion and the outside space is formed in the fourth layer.

[0077] A method for manufacturing a pressure sensor according to one aspect of the present invention includes:

[0078] A first step, in which a first layer having a first opening portion formed with a pattern is joined to a base;

[0079] A second step, in which a second layer is joined to a surface of the first layer on the side opposite to the side where the base is located;

[0080] A third step, in which a third layer having a second opening portion formed with a pattern is joined to a surface of the second layer on the side opposite to the side where the first layer is located so as to form a first diaphragm sandwiched between the first opening portion and the second opening portion in the second layer;

[0081] A fourth step, in which a fourth layer having a third opening portion formed with a pattern is joined to a surface of the third layer on the side opposite to the side where the second layer is located so that the third opening portion communicates with the second opening portion; and

[0082] Step 5: In this step, a covering portion having a fourth opening and a fifth opening covers the base, the first layer, the second layer, the third layer, and the fourth layer, so that the fourth opening exposes the third opening to the outside, and the fifth opening exposes the surface of the fourth layer on the side opposite to the side where the third layer is located to the outside, thereby forming a second diaphragm sandwiched between the second opening and the fifth opening in the fourth layer.

[0083] By using these manufacturing methods, it is possible to manufacture a pressure sensor chip and a pressure sensor without using complicated processes such as changing the thickness within the same layer.

[0084] <First Embodiment>

[0085] Figure 1 It is a longitudinal sectional view of the pressure sensor according to the first embodiment of the present invention.

[0086] The pressure sensor 1 senses a minute pressure. As Figure 1 shown, the pressure sensor 1 includes two diaphragms (a first diaphragm 26 and a second diaphragm 27) described later. The first diaphragm 26 and the second diaphragm 27 sense pressure by flexing. That is, the pressure sensor 1 can measure two pressures.

[0087] As Figure 1 shown, the pressure sensor 1 includes a substrate 10, a pressure sensor chip 20, an application specific integrated circuit (ASIC) 30, a first covering portion 40, and a second covering portion 50. Hereinafter, the application specific integrated circuit 30 is referred to as ASIC 30.

[0088] The substrate 10 is a plate-like member. The substrate 10 is made of materials such as epoxy, phenolic resin, ceramics, or aluminum. On the outer surface of the substrate 10, a wiring pattern, pads, through holes, etc. formed of a metal such as copper are formed. The wiring pattern, pads, and through holes are electrically connected to each other.

[0089] Figure 2 is Figure 1 a top view of the pressure sensor chip included in the pressure sensor.

[0090] As Figure 1 shown, the pressure sensor chip 20 is mounted on the substrate 10. As mounting means, various well-known means can be adopted. In the first embodiment, the base 25 described later is pasted on the upper surface 10A using an adhesive, thereby mounting the pressure sensor chip 20 on the substrate 10.

[0091] As Figure 1 and Figure 2As shown, in the first embodiment, the pressure sensor chip 20 has a rectangular parallelepiped shape. Additionally, the pressure sensor chip 20 can also have a shape other than a rectangular parallelepiped, such as a cylindrical shape. The pressure sensor chip 20 is a device composed of MEMS (Micro Electro Mechanical Systems). The pressure sensor chip 20 has a structure formed by laminating multiple layers. The structure of the pressure sensor chip 20 will be described in detail later.

[0092] As Figure 1 shown, the ASIC 30 is mounted on the upper surface 10A of the substrate 10. Various well-known mounting means can be used. In the first embodiment, the ASIC 30 is adhered to the upper surface 10A using an adhesive.

[0093] The ASIC 30 is connected to the pressure sensor chip 20 by a conductive wire (such as Figure 1 the wire 31 shown) made of aluminum, copper, etc. The ASIC 30 is electrically connected to the pad 33 formed on the outer surface of the substrate 10 by a conductive wire 32, etc. made of aluminum, copper, etc.

[0094] The ASIC 30 has a function of processing the signal input from the pressure sensor chip 20 via wires such as the wire 31 and outputting it to the outside via wires such as the wire 32. The processing of the signal is at least one of the following processes.

[0095] For example, the processing of the signal is a conversion process of converting the signal input from the pressure sensor chip 20 from an analog value to a digital value. In the first embodiment, as will be described later, the signal input from the pressure sensor chip 20 is a current value based on the deflection amounts of the first diaphragm 26 and the second diaphragm 27. Additionally, for example, the processing of the signal is a filtering process of removing the high-frequency band noise component from the digital value obtained through the conversion process to obtain a low-frequency band signal. Additionally, for example, the processing of the signal is a correction process of correcting the input value through the operation of the input value from an external temperature sensor, the signal obtained through the filtering process, and a preset correction coefficient. The temperature sensor is installed, for example, near the pressure sensor chip 20 on the substrate 10. The correction coefficient is stored, for example, in the internal memory provided in the ASIC 30.

[0096] The first covering portion 40 and the second covering portion 50 are made of a resin such as epoxy resin. The first covering portion 40 and the second covering portion 50 are an example of covering portions.

[0097] The first covering portion 40 covers the chip 20 for the pressure sensor. In the present first embodiment, the first covering portion 40 covers the surfaces of the chip 20 for the pressure sensor other than the surface in contact with the substrate 10. The first covering portion 40 has two opening portions 41 and 42 penetrating through the first covering portion 40. The opening portions 41 and 42 expose a part of the chip 20 for the pressure sensor to the outside. The opening portion 41 is an example of the fourth opening portion. The opening portion 42 is an example of the fifth opening portion.

[0098] The second covering portion 50 is joined to the first covering portion 40. The second covering portion 50 is joined to the side of the first covering portion 40 opposite to the side in contact with the chip 20 for the pressure sensor. The second covering portion 50 has two cylindrical caps 51 and 52. In the present first embodiment, the caps 51 and 52 are cylindrical. The caps 51 and 52 project in a manner separated from the first covering portion 40 and the chip 20 for the pressure sensor. The internal space 53 of the cap 51 communicates with the opening portion 41. The internal space 54 of the cap 52 communicates with the opening portion 42. The cap 51 is an example of the first cap. The cap 52 is an example of the second cap.

[0099] Hereinafter, the structure of the chip 20 for the pressure sensor will be described in detail. In addition, in the following description, the directions of the respective sides of the cuboid chip 20 for the pressure sensor are defined as the length direction 2, the width direction 3, and the height direction 4. In Figure 1 it, the width direction 3 is Figure 1 the depth direction of the paper surface of

[0100] As Figure 1 shown, the chip 20 for the pressure sensor includes a first layer 21, a second layer 22, a third layer 23, a fourth layer 24, and a base 25.

[0101] The first layer 21 and the third layer 23 are electrically insulating insulators. In the present first embodiment, the first layer 21 and the third layer 23 are made of silicon dioxide. The second layer 22, the fourth layer 24, and the base 25 are conductors. In the present first embodiment, the second layer 22, the fourth layer 24, and the base 25 are made of silicon.

[0102] The base 25 is joined to the upper surface 10A of the substrate 10 using an adhesive or the like. The first layer 21 is joined to the upper surface 25A of the base 25. The second layer 22 is joined to the side of the first layer 21 opposite to the side where the base 25 is located, that is, joined to the upper surface 21A of the first layer 21. The third layer 23 is joined to the side of the second layer 22 opposite to the side where the first layer 21 is located, that is, joined to the upper surface 22A of the second layer 22. The fourth layer 24 is joined to the side of the third layer 23 opposite to the side where the second layer 22 is located, that is, joined to the upper surface 23A of the third layer 23. Based on the above, the pressure sensor chip 20 is formed by laminating the base 25, the first layer 21, the second layer 22, the third layer 23, and the fourth layer 24 in this order from below.

[0103] In this first embodiment, the thickness (the length in the height direction 4) of the first layer 21, the second layer 22, the third layer 23, and the fourth layer 24 is approximately 2 μm to 5 μm.

[0104] The portion of the pressure sensor chip 20 other than the lower surface of the base 25 joined to the substrate 10 is covered by the first covering portion 40. In other words, the first covering portion 40 covers the sides of the base 25, the first layer 21, the second layer 22, the third layer 23, and the fourth layer 24, and the upper surface 24A of the fourth layer 24.

[0105] Figure 3 is Figure 1 the A - A cross-sectional view in. As Figure 1 and Figure 3 shown, an opening 21B is formed in the first layer 21. The opening 21B penetrates the first layer 21 in the height direction 4. The opening 21B is an example of the first opening.

[0106] Figure 4 is Figure 1 the B - B cross-sectional view in. As Figure 1 and Figure 4 shown, no opening is formed in the second layer 22. As Figure 1 shown, the opening 21B of the first layer 21 is sandwiched between the base 25 and the second layer 22.

[0107] The upper end portion of the opening 21B is sealed by the second layer 22, and the lower end portion of the opening 21B is sealed by the base 25. As a result, the opening 21B is sealed. In this first embodiment, the inside of the opening 21B is vacuum.

[0108] In addition, the interior of the opening 21B is not limited to a perfect vacuum, and may also be a near-vacuum, i.e., a substantially vacuum state. For example, when the pressure inside the opening 21B is less than 3000 Pascals and greater than 0 Pascals, the interior of the opening 21B is in a substantially vacuum state. When the pressure inside the opening 21B is 0 Pascals, the interior of the opening 21B is in a vacuum state. In addition, the interior of the opening 21B may not be in a vacuum or substantially vacuum state. Regardless of the state of the interior of the opening 21B (vacuum, substantially vacuum, or a state other than vacuum and substantially vacuum), the pressure inside the opening 21B is lower than the pressure inside the opening 23B described below.

[0109] Figure 5 is Figure 1 a C-C cross-sectional view in. As Figure 1 and Figure 5 shown, an opening 23B is formed in the third layer 23. The opening 23B penetrates the third layer 23 in the height direction 4. The opening 23B is an example of the second opening.

[0110] As Figure 5 shown, the opening 23B has a first space 23Ba, a second space 23Bb, and a third space 23Bc. The first space 23Ba and the third space 23Bc are in communication. The third space 23Bc and the second space 23Bb are in communication.

[0111] When observing the pressure sensor chip 20 in the height direction 4, that is, in a top view, the first space 23Ba overlaps with the opening 21B of the first layer 21.

[0112] The portion of the second layer 22 that overlaps with the first space 23Ba and the opening 21B in a top view (see Figure 5 ), in other words, the portion of the second layer 22 sandwiched between the first space 23Ba and the opening 21B (see Figure 1 ) constitutes the first diaphragm 26 (see Figure 4 ). As Figure 1 shown, the first diaphragm 26 can flex in the height direction 4 by having spaces above and below it. In the present first embodiment, the first diaphragm 26 is rectangular in a top view, and each side of the rectangle is 200 μm to 500 μm.

[0113] As Figure 5 shown, in a top view, the second space 23Bb does not overlap with the opening 21B of the first layer 21. In the present first embodiment, the size and shape of the second space 23Bb in a top view are the same as those of the first space 23Ba. However, at least one of the size and shape of the second space 23Bb may be different from those of the first space 23Ba.

[0114] In the present first embodiment, the length of the third space 23Bc in the width direction 3 is shorter than the lengths of the first space 23Ba and the second space 23Bb in the width direction 3. That is to say, the width of the third space 23Bc is narrower than the widths of the first space 23Ba and the second space 23Bb. In the present first embodiment, in a plan view, the third space 23Bc does not overlap with the opening 21B of the first layer 21.

[0115] As Figure 1 and Figure 2 shown, an opening 24B is formed in the fourth layer 24. The opening 24B penetrates the fourth layer 24 in the height direction 4. The opening 24B is an example of the third opening.

[0116] As Figure 1 shown, the lower end portion of the opening 24B communicates with the first space 23Ba of the opening 23B of the third layer 23. That is to say, in a plan view, the opening 24B overlaps with the first space 23Ba. On the other hand, the upper end portion of the opening 24B communicates with the outside of the pressure sensor chip 20. The lower end portion of the opening 24B is an example of the second end of the third opening. The upper end portion of the opening 24B is an example of the first end of the third opening.

[0117] As described above, as Figure 1 shown, the surface of the fourth layer 24 on the side opposite to the side where the third layer 23 is located, that is, the upper surface 24A of the fourth layer 24, is covered by the first covering portion 40. The first covering portion 40 is in contact with the upper surface 24A.

[0118] The opening 41 of the first covering portion 40 is located directly above the opening 24B. Thus, the opening 41 exposes the opening 24B to the outside of the pressure sensor chip 20. In addition, the opening 23B and the opening 24B communicate with the outside of the pressure sensor 1 through the internal space 53 of the opening 41 and the cap 51 of the second covering portion 50.

[0119] The opening 42 of the first covering portion 40 is located directly above the fourth layer 24. However, in a plan view, the opening 42 does not overlap with the opening 24B. Thus, the opening 42 exposes the upper surface 24A of the fourth layer 24 to the outside of the pressure sensor chip 20. In addition, the upper surface 24A communicates with the outside of the pressure sensor 1 through the internal space 54 of the opening 42 and the cap 52 of the second covering portion 50.

[0120] In a plan view, the opening 42 overlaps with the second space 23Bb of the opening 23B of the third layer 23. As Figure 1 and Figure 2As shown, the portion of the fourth layer 24 that overlaps with the opening 42 and the second space 23Bb in a plan view, in other words, the portion of the fourth layer 24 sandwiched between the opening 42 and the second space 23Bb, constitutes the second diaphragm 27. The second diaphragm 27 can flex in the height direction 4 by having spaces above and below it. In the present first embodiment, the second diaphragm 27 is rectangular in a plan view, and the size of the second diaphragm 27 is substantially the same as that of the first diaphragm 26. Additionally, the size of the second diaphragm 27 can also be different from that of the first diaphragm 26.

[0121] Here, the opening 42 is a space outside the pressure sensor chip 20. That is to say, the second diaphragm 27 is sandwiched between the second space 23Bb and the space communicating with the outside of the pressure sensor chip 20. In addition, the opening 42 communicates with the outside of the pressure sensor 1 through the internal space 54 of the cap 52. That is to say, the second diaphragm 27 can be said to be sandwiched between the second space 23Bb and the space communicating with the outside of the pressure sensor 1.

[0122] As Figure 2 shown, in the present first embodiment, in a plan view, the second diaphragm 27 does not overlap with the first diaphragm 26.

[0123] The first diaphragm 26 and the second diaphragm 27 are used for pressure measurement. A detailed description will be given below.

[0124] As Figure 2 shown, one end portion of the fourth layer 24 at both end portions in the length direction 2 is provided with a convex portion 24D. The convex portion 24D is formed by cutting both end portions in the width direction 3 of this one end portion. A pad 24C is formed on the upper surface of the convex portion 24D. As Figure 1 shown, a wire 31 is connected to the pad 24C. Thus, the fourth layer 24 having the second diaphragm 27 is electrically connected to the ASIC 30.

[0125] As Figure 5 shown, the third layer 23 is cut in the same manner as the fourth layer 24. As Figure 4 shown, the second layer 22 is cut in the same manner as the fourth layer 24 and the third layer 23 only at one of the two cut portions of the fourth layer 24 and the third layer 23. As Figure 3 shown, the first layer 21 is cut in the same manner as the second layer 22.

[0126] Thus, as Figure 2As shown, on both sides in the width direction 3 of the convex portion 24D, the upper surface 22A of the second layer 22 and the upper surface 25A of the base 25 are exposed to the outside of the pressure sensor chip 20. A pad 22B is formed on the exposed upper surface 22A, and a pad 25B is formed on the exposed upper surface 25A. Each of the above pads 22B and 25B is electrically connected to the ASIC 30 by a wire (not shown) in the same manner as the pad 24C. Thus, the base 25 and the second layer 22 having the first diaphragm 26 are respectively electrically connected to the ASIC 30.

[0127] Figure 6 is a diagram showing Figure 1 the equivalent circuit of the pressure sensor chip.

[0128] As Figure 1 shown, the base 25 and the first diaphragm 26 of the second layer 22 face each other with the opening 21B therebetween. In addition, as described above, the base 25 and the second layer 22 are conductors. Thus, a capacitor C1 as Figure 6 shown is formed by the base 25 and the first diaphragm 26.

[0129] As Figure 1 shown, the second layer 22 and the second diaphragm 27 of the fourth layer 24 face each other with the second space 23Bb of the opening 23B therebetween. In addition, as described above, the second layer 22 and the fourth layer 24 are conductors. Thus, a capacitor C2 as Figure 6 shown is formed by the second layer 22 and the second diaphragm 27.

[0130] That is to say, the pressure sensor chip 20 constitutes Figure 6 the equivalent circuit as

[0131] The lower surface of the first diaphragm 26 faces the opening 21B. The upper surface of the first diaphragm 26 faces the opening 23B. As described above, the pressure inside the opening 21B is lower than the pressure inside the opening 23B. Therefore, the first diaphragm 26 flexes toward the opening 21B. The amount of flexure of the first diaphragm 26 changes corresponding to the pressure in the opening 23B. That is to say, the first diaphragm 26 is used to measure the pressure based on the pressure in the sealed opening 21B. In the present first embodiment, since the opening 21B is in a vacuum, the pressure in the opening 21B is the absolute pressure.

[0132] The lower surface of the second diaphragm 27 faces the opening 23B. The upper surface of the second diaphragm 27 faces the opening 42. Therefore, the greater the pressure difference between the pressure of the opening 23B and the pressure of the opening 42, the greater the amount of deflection of the second diaphragm 27, and the smaller the pressure difference between the pressure of the opening 23B and the pressure of the opening 42, the smaller the amount of deflection of the second diaphragm 27. Further, when the pressure of the opening 23B is greater than the pressure of the opening 42, the second diaphragm 27 deflects toward the opening 42, that is, upward. On the other hand, when the pressure of the opening 42 is greater than the pressure of the opening 23B, the second diaphragm 27 deflects toward the opening 23B, that is, downward.

[0133] In addition, in Figure 1 this state, since both the opening 23B and the opening 42 are open to the atmosphere via the caps 51 and 52, the pressure difference described above is zero. However, by connecting tubes or the like to the respective caps 51 and 52, fluids of different positions and types can be introduced into the respective caps 51 and 52. In this case, the pressure difference described above can become a value other than zero.

[0134] The greater the amount of deflection of the first diaphragm 26, the narrower the gap between the first diaphragm 26 and the base 25. As a result, the capacitance of the capacitor C1 increases. Conversely, the smaller the amount of deflection of the first diaphragm 26, the wider the gap between the first diaphragm 26 and the base 25. As a result, the capacitance of the capacitor C1 decreases.

[0135] The greater the amount of downward deflection of the second diaphragm 27, the narrower the gap between the second diaphragm 27 and the second layer 22. As a result, the capacitance of the capacitor C2 increases. Conversely, the smaller the amount of downward deflection of the second diaphragm 27 or the greater the amount of upward deflection, the wider the gap between the second diaphragm 27 and the second layer 22. As a result, the capacitance of the capacitor C2 decreases.

[0136] Signals corresponding to the states of the first diaphragm 26 and the second diaphragm 27 are output to the ASIC 30 via the pads 22B, 24C, and 25B. The ASIC 30 that has received this signal performs the above-described processing (processing such as conversion processing, filtering processing, and correction processing) and outputs the processed signal. The signal obtained by processing the signal corresponding to the state of the first diaphragm 26 in the ASIC 30 is a signal representing the absolute pressure of the fluid flowing in from the cap 51. The signal obtained by processing the signal corresponding to the state of the second diaphragm 27 in the ASIC 30 is a signal representing the pressure difference between the fluids flowing in from the caps 51 and 52.

[0137] Hereinafter, a method for manufacturing the above-described pressure sensor chip 20 will be described. The pressure sensor chip 20 is manufactured by performing the first to fourth processes described below.

[0138] First, a first layer 21 formed of silicon dioxide and having an opening 21B patterned thereon is bonded to the upper surface 25A of a base 25 formed of silicon. The process of bonding the first layer 21 to the base 25 is an example of a first process. In this process and the following processes, patterning is performed by well-known means such as etching. In addition, bonding is performed by well-known means such as high-temperature pressing.

[0139] Next, a second layer 22 formed of silicon is bonded to the upper surface 21A of the first layer 21. At this time, the second layer 22 is bonded to the upper surface 21A so as to cover the opening 21B. As a result, the opening 21B is sealed by the base 25 and the second layer 22. The process of bonding the second layer 22 to the first layer 21 is an example of a second process.

[0140] In the present embodiment, at least the second process among the first to fourth processes is performed in a vacuum state. As a result, the sealed opening 21B becomes a vacuum. Alternatively, the second process may be performed in a state other than a vacuum. In this case, the pressure in the opening 21B is set lower than the pressure in the opening 23B of the third layer 23 bonded in the third process.

[0141] Next, a third layer 23 formed of silicon dioxide and having an opening 23B patterned thereon is bonded to the upper surface 22A of the second layer 22. At this time, in a plan view, the third layer 23 is bonded to the second layer 22 such that a first space 23Ba of the opening 23B overlaps with the opening 21B. In other words, the third layer 23 is bonded to the second layer 22 such that a first diaphragm 26 sandwiched between the opening 21B and the opening 23B is formed on the second layer 22. In addition, at this time, in a plan view, the third layer 23 is bonded to the second layer 22 such that a second space 23Bb of the opening 23B does not overlap with the opening 21B. The process of bonding the third layer 23 to the second layer 22 is an example of a third process.

[0142] Next, a fourth layer 24 formed of silicon and having an opening 24B patterned thereon is bonded to the upper surface 23A of the third layer 23. In a state where the fourth layer 24 is bonded to the third layer 23, the upper surface 24A of the fourth layer 24 is exposed to the outside. Therefore, the upper end portion of the opening 24B communicates with the outside.

[0143] At this time, in a plan view, the fourth layer 24 is bonded to the third layer 23 such that the opening 24B overlaps with the opening 23B. In other words, the fourth layer 24 is bonded to the third layer 23 such that the lower end portion of the opening 24B communicates with the opening 23B.

[0144] In addition, at this time, when viewed from above, the fourth layer 24 is joined to the third layer 23 in such a manner that any part of the fourth layer 24 other than the opening 24B overlaps with the second space 23Bb of the opening 23B when viewed from above. In other words, the fourth layer 24 is joined to the third layer 23 in such a manner that the second diaphragm 27 is formed in the fourth layer 24, which is sandwiched by the space (external space) facing the upper surface 24A and the opening 23B.

[0145] The process of joining the fourth layer 24 to the third layer 23 is an example of the fourth process.

[0146] The pressure sensor chip 20 is manufactured by performing the first process to the fourth process.

[0147] Next, the pressure sensor chip 20 manufactured by performing the above-described processes is mounted on the substrate 10. In addition, components such as the ASIC 30 and resistors are mounted on the substrate 10 as needed. The pressure sensor chip 20 and the above-described components are mounted on the substrate 10 by well-known means such as surface mounting and via mounting. In the first embodiment, for the pressure sensor chip 20 and the ASIC 30, they are pasted on the substrate 10 by applying an adhesive (not shown) to the lower surface.

[0148] Next, each wire such as the wires 31 and 32 is wired by well-known means. In the first embodiment, the wires 31 and 32 are wired by wire bonding. Both end portions of the wire 31 are respectively connected to the ASIC 30 and the pad 24C formed in the fourth layer 24. Other wires connecting the pressure sensor chip 20 and the ASIC 30 are also wired in the same manner as the wire 31. Both end portions of the wire 32 are respectively connected to the ASIC 30 and the pad 33 formed on the upper surface of the substrate 10.

[0149] Next, the upper surface 10A of the substrate 10 and the pressure sensor chip 20 and the ASIC 30 mounted on the upper surface 10A are covered with the first covering portion 40 made of resin. The portion of the pressure sensor chip 20 other than the lower surface of the base 25 (the sides of the first layer 21, the second layer 22, the third layer 23, and the fourth layer 24 and the upper surface 24A of the fourth layer 24) is covered.

[0150] The first covering portion 40 covers the upper surface 10A of the substrate 10 and the like by well-known means such as injection molding. In the present first embodiment, the first covering portion 40 is injected toward the upper surface 10A of the substrate 10 in a softened state. At this time, openings 41 and 42 penetrating the first covering portion 40 in the height direction 4 are formed in the first covering portion 40 by using a mold. The openings 41 and 42 are formed directly above the upper surface 24A of the fourth layer 24. The opening 41 is formed at a position that overlaps with the opening 24B in a top view. Thus, the opening 24B is exposed to the outside through the opening 41. The opening 42 is formed at a position that overlaps with the second space 23Bb of the opening 23B in a top view. Thus, a portion of the upper surface 24A of the fourth layer 24 located directly above the second space 23Bb is exposed to the outside through the opening 42. In addition, the second diaphragm 27 becomes a portion sandwiched between the opening 42 and the second space 23Bb.

[0151] Next, the upper surface 40A of the first covering portion 40 is covered with a second covering portion 50 made of resin. The second covering portion 50 covers the upper surface of the first covering portion 40 by well-known means in the same manner as the first covering portion 40. At this time, caps 51 and 52 are formed in the second covering portion 50 by using a mold. In the present first embodiment, the caps 51 and 52 are each in a cylindrical shape protruding upward. The cap 51 is formed directly above the opening 41. Thus, the opening 41 communicates with the outside through the internal space 53 of the cap 51. The cap 52 is formed directly above the opening 42. Thus, the opening 42 communicates with the outside through the internal space 54 of the cap 52.

[0152] The process of covering the pressure sensor chip 20 with the first covering portion 40 and the second covering portion 50 is an example of the fifth process.

[0153] According to the present first embodiment, pressure from the opening 21B and pressure from the opening 23B act on the first diaphragm 26. Thus, it is possible to measure the pressure based on the pressure in the closed opening 21B by using the first diaphragm 26. In addition, pressure from the opening 23B and pressure from the outside act on the second diaphragm 27. The pressure from the outside acts on the upper surface 24A of the fourth layer 24 via the internal space 54 of the cap 52 and the opening 42. Thus, it is possible to measure the pressure difference between these two pressures by using the second diaphragm 27. That is to say, according to the present first embodiment, it is possible to measure the pressure difference between two pressures and the pressure based on the pressure in the opening 21B by using one pressure sensor chip 20. Moreover, two diaphragms (the first diaphragm 26 and the second diaphragm 27) are integrated on the same pressure sensor chip 20. Therefore, it is possible to miniaturize the pressure sensor chip 20.

[0154] According to the first embodiment, the first diaphragm 26 and the second diaphragm 27 are provided in different layers. Therefore, the thicknesses of the second layer 22 provided with the first diaphragm 26 and the fourth layer 24 provided with the second diaphragm 27 can be set to different thicknesses without complicating the manufacturing process.

[0155] In the first embodiment, the inside of the opening 21B is a vacuum. Therefore, the first diaphragm 26 can function as a diaphragm for measuring the absolute pressure.

[0156] According to the first embodiment, the pressure sensor chip 20 can function as a capacitive type.

[0157] According to the first embodiment, the first diaphragm 26 does not overlap the second diaphragm 27 in a plan view. Therefore, the influence of the pressure in the opening 21B on the second diaphragm 27 via the second layer 22 and the opening 23B is suppressed. Thus, the measurement of the pressure difference realized by the second diaphragm 27 can be performed with high precision.

[0158] According to the first embodiment, the pressure sensor chip 20 can be protected by the first covering portion 40.

[0159] According to the first embodiment, the connection between the pressure sensor 1 and the outside can be easily performed by means of the caps 51 and 52.

[0160] By using the manufacturing method of the pressure sensor chip 20 and the pressure sensor 1 according to the first embodiment, the pressure sensor chip 20 and the pressure sensor 1 can be manufactured without using complex processes such as changing the thickness within the same layer.

[0161] The shapes of the openings 21B, 23B, 24B of the pressure sensor chip 20, the openings 41, 42 of the first covering portion 40, and the caps 51, 52 of the second covering portion 50 are not limited to the shapes of the first embodiment.

[0162] For example, in the first embodiment, the shapes of the opening 21B, the first space 23Ba of the opening 23B, the second space 23Bb of the opening 23B, and the opening 24B are rectangular in a plan view, but they can also be other shapes such as circular.

[0163] The positions and sizes of the openings 21B, 23B, 24B of the pressure sensor chip 20, the openings 41, 42 of the first covering portion 40, and the caps 51, 52 of the second covering portion 50 are not limited to the positions and sizes of the first embodiment. However, the following four conditions need to be satisfied.

[0164] The first condition is that at least a part of the opening 21B overlaps with at least a part of the opening 23B when viewed from above. The first diaphragm 26 is the part of the second layer 22 where the opening 21B overlaps with the opening 23B when viewed from above. The second condition is that at least a part of the opening 24B overlaps with a part of the opening 23B when viewed from above. Thus, the opening 23B can communicate with the outside through the opening 24B. The third condition is that at least a part of the opening 24B overlaps with at least a part of the opening 41 when viewed from above. The fourth condition is that the opening 24B does not overlap with the opening 42 when viewed from above.

[0165] For example, in the present first embodiment, the opening 24B only overlaps with the first space 23Ba in the opening 23B when viewed from above. However, the opening 24B may overlap with the third space 23Bc instead of the first space 23Ba when viewed from above, or may overlap with both the first space 23Ba and the third space 23Bc in addition to overlapping with the first space 23Ba.

[0166] In the present first embodiment, as Figure 5 shown, in the opening 23B, the width of the third space 23Bc is narrower than the widths of the first space 23Ba and the second space 23Bb. However, the position, size, and shape of the third space 23Bc are not limited to Figure 5 the position, size, and shape shown. For example, the width (the length in the width direction 3) of the third space 23Bc may be longer than Figure 5 the width shown, or may be shorter than Figure 5 the width shown. In addition, the third space 23Bc may extend obliquely to either side in the width direction 3 with respect to the length direction 2. Additionally, the third space 23Bc preferably extends straight without bending or kinking.

[0167] In the present first embodiment, the thicknesses (the lengths in the height direction 4) of the first layer 21, the second layer 22, the third layer 23, and the fourth layer 24 are the same as each other as Figure 1 shown, but they may also be different from each other.

[0168] For example, as Figure 7 shown, the thickness of the fourth layer 24 may be thinner than the thickness of the second layer 22. In this case, since the second diaphragm 27 is thinner than the first diaphragm 26, the second diaphragm 27 can be flexed with a small pressure difference. In addition, since the opening 21B is a vacuum, the pressure in the opening 21B is low, so the amount of flexure of the first diaphragm 26 is large. Thus, there is a possibility that the first diaphragm 26 may rupture. However, since the first diaphragm 26 is thicker than the second diaphragm 27, the possibility of the first diaphragm 26 rupturing can be reduced.

[0169] The first layer 21 and the third layer 23 may also be composed of multiple layers. In this case, the opening 21B penetrates the first layer 21 composed of multiple layers in the height direction 4. In addition, the opening 23B penetrates the third layer 23 composed of multiple layers in the height direction 4.

[0170] In the first embodiment, in the pressure sensor chip 20, the capacitor C1 is formed by using the base 25 and the first diaphragm 26. The capacitor C2 is formed by using the second layer 22 and the second diaphragm 27 (see Figure 6 ). That is, the pressure sensor chip 20 functions as a capacitive type. However, the pressure sensor chip 20 is not limited to the capacitive type. For example, it may be that by forming strain gauges on the first diaphragm 26 and the second diaphragm 27, the pressure sensor chip 20 functions as a piezoelectric type.

[0171] <Second Embodiment>

[0172] Figure 8 is a longitudinal sectional view of the pressure sensor according to the second embodiment of the present invention. Figure 9 is Figure 8 a top view of the pressure sensor chip included in the pressure sensor. Figure 10 is Figure 8 a D - D sectional view in Figure 11 is Figure 8 an E - E sectional view in Figure 12 is Figure 8 an F - F sectional view in

[0173] The difference between the pressure sensor of the second embodiment and the pressure sensor of the first embodiment is that the first diaphragm and the second diaphragm overlap when viewed from above and the shape of the opening in the third layer is rectangular.

[0174] The opening 21B of the second embodiment (see Figure 10 ) is larger than the opening 21B of the first embodiment (see Figure 3 ). As shown in Figure 8 , the opening 21B of the first layer 21 is formed in the range from directly below the opening 41 to directly below the opening 42. Thus, the first diaphragm 26 of the second embodiment (see Figure 11 ) is larger than the first diaphragm 26 of the first embodiment (see Figure 4 ). In addition, thus as shown in Figure 9 , the first diaphragm 26 and the second diaphragm 27 overlap when viewed from above.

[0175] As shown in Figure 12As shown, the width of the third space 23Bc of the opening 23B (the length in the width direction 3) is the same as the lengths in the width direction 3 of the first space 23Ba and the second space 23Bb. In this case, the opening 23B is rectangular. In Figure 12 The boundary between the third space 23Bc and the first space 23Ba and the second space 23Bb is shown by a dashed line in

[0176] According to this second embodiment, since the first diaphragm 26 is larger than that of the first embodiment, the sensitivity of the first diaphragm 26 can be improved compared to the first embodiment.

[0177] <Third Embodiment>

[0178] Figure 13 is a longitudinal sectional view of the pressure sensor according to the third embodiment of the present invention.

[0179] The pressure sensor according to this third embodiment is different from the pressure sensor according to the first embodiment in that the pressure sensor chip is mounted on the ASIC.

[0180] The ASIC 30 of the third embodiment (refer to Figure 13 ) is larger than the ASIC 30 of the first embodiment (refer to Figure 1 ). As Figure 13 shown, the pressure sensor chip 20 is mounted on the upper surface of the ASIC 30. The pressure sensor chip 20 is fixed to the upper surface of the ASIC by well-known means, for example, by adhesion using an adhesive.

[0181] <Fourth Embodiment>

[0182] Figure 14 is a longitudinal sectional view of the pressure sensor according to the fourth embodiment of the present invention.

[0183] The pressure sensor according to this fourth embodiment is different from the pressure sensor according to the first embodiment in that the second covering portion and the first covering portion are integrated and the shape of the internal space of the cap is different.

[0184] As Figure 14 shown, in this fourth embodiment, the second covering portion 50 of the first embodiment is integrated with the first covering portion 40. Hereinafter, in the fourth embodiment, the first covering portion 40 integrated with the second covering portion 50 is denoted as the covering portion 60.

[0185] The covering portion 60 includes caps 61 and 62. The cap 61 has substantially the same structure as the cap 51 of the first embodiment. The cap 62 has substantially the same structure as the cap 52 of the first embodiment. In the fourth embodiment, the caps 61 and 62 are each cylindrical in shape. However, the internal spaces 63 and 64 of the caps 61 and 62 are different from the internal spaces 53 and 54 of the caps 51 and 52 of the first embodiment. That is, the inner diameters of the internal spaces 63 and 64 become smaller as going downward (in other words, as approaching the pressure sensor chip 20). In addition, the internal space 63 of the cap 61 communicates with the opening 24B of the fourth layer 24. The internal space 64 of the cap 62 is located directly above the portion of the fourth layer 24 other than the opening 24B.

[0186] In the manufacturing process of the pressure sensor chip 20, the covering portion 60 covers the upper surface 10A of the substrate 10 by well-known means such as injection molding in the same manner as the first covering portion 40 of the first embodiment. At this time, the caps 61 and 62 are formed in the covering portion 60 using a mold. As described above, since the inner diameters of the internal spaces 63 and 64 of the caps 61 and 62 become smaller as going downward, they can be formed using a mold. In addition, the shapes of the internal spaces 63 and 64 of the caps 61 and 62 and the external shapes of the caps 61 and 62 are not limited to Figure 14 the shapes shown.

[0187] In addition, by appropriately combining any of the various embodiments, the effects possessed by each can be achieved.

[0188] The present invention has been fully described with appropriate reference to the drawings and in association with preferred embodiments, but various variations and modifications will be apparent to those skilled in the art. Such variations and modifications should be understood to be included therein as long as they do not depart from the scope of the present invention defined by the appended claims.

[0189] Explanation of Reference Signs

[0190] 20, pressure sensor chip; 21, first layer; 21B, opening (first opening); 22, second layer; 23, third layer; 23B, opening (second opening); 24, fourth layer; 24B, opening (third opening); 25, base; 26, first diaphragm; 27, second diaphragm; 40, first covering portion (covering portion); 41, opening (fourth opening); 42, opening (fifth opening); 50, second covering portion (covering portion); 51, cap (first cap); 52, cap (second cap).

Claims

1. A chip for a pressure sensor, which includes a first diaphragm and a second diaphragm for pressure measurement. Wherein, The chip for the pressure sensor includes: A base; A first layer, which is joined to the base and has a first opening; A second layer, which is joined to the side of the first layer opposite to the side where the base is located; A third layer, which is joined to the side of the second layer opposite to the side where the first layer is located and has a second opening; and A fourth layer, which is joined to the side of the third layer opposite to the side where the second layer is located and has a third opening, The second layer includes the first diaphragm sandwiched between the first opening and the second opening, The fourth layer includes the second diaphragm sandwiched between the second opening and a space communicating with the outside, A first end of the third opening communicates with the outside, A second end of the third opening communicates with the second opening, The first opening is sealed, The pressure in the first opening is lower than the pressure in the second opening.

2. The chip for a pressure sensor according to claim 1, Wherein, The inside of the first opening is vacuum or substantially vacuum.

3. The chip for a pressure sensor according to claim 1 or 2, Wherein, The thickness of the fourth layer is thinner than the thickness of the second layer.

4. The chip for a pressure sensor according to claim 1 or 2, Wherein, The base, the second layer and the fourth layer are conductors, The first layer and the third layer are electrically insulating insulators.

5. The chip for a pressure sensor according to claim 1 or 2, Wherein, The first diaphragm does not overlap with the second diaphragm in a top view.

6. The chip for a pressure sensor according to claim 1 or 2, Wherein, The first diaphragm overlaps with the second diaphragm in a top view.

7. A pressure sensor, Wherein, The pressure sensor includes: The chip for a pressure sensor according to any one of claims 1 to 6; and A covering portion that covers the chip for a pressure sensor, The covering portion includes: A fourth opening that communicates the third opening with the outside; and A fifth opening that exposes the side of the fourth layer opposite to the side where the third layer is located to the outside, The second diaphragm is sandwiched between the second opening and the fifth opening.

8. The pressure sensor according to claim 7, Wherein, The covering portion includes: A cylindrical first cap that protrudes from around the fourth opening in a manner separated from the chip for a pressure sensor; and A cylindrical second cap that protrudes from around the fifth opening in a manner separated from the chip for a pressure sensor.

9. A manufacturing method of a chip for a pressure sensor, Wherein, The manufacturing method of the chip for a pressure sensor includes: A first process, in which the first layer with a patterned first opening is joined to the base; A second process, in which the second layer is joined to the surface of the first layer opposite to the side where the base is located; The third step, in which the third layer with the second opening patterned is joined to the surface of the second layer on the side opposite to the side where the first layer is located in such a way that a first diaphragm sandwiched between the first opening and the second opening is formed in the second layer; and The fourth step, in which the fourth layer with the third opening patterned is joined to the surface of the third layer on the side opposite to the side where the second layer is located, so that the first end of the third opening communicates with the outside, the second end of the third opening communicates with the second opening, and a second diaphragm sandwiched between the second opening and the outside space is formed in the fourth layer, the first opening is sealed, the pressure in the first opening is lower than the pressure in the second opening.

10. A method for manufacturing a pressure sensor, wherein, the method for manufacturing the pressure sensor includes: The first step, in which the first layer with the first opening patterned is joined to the base; The second step, in which the second layer is joined to the surface of the first layer on the side opposite to the side where the base is located; The third step, in which the third layer with the second opening patterned is joined to the surface of the second layer on the side opposite to the side where the first layer is located in such a way that a first diaphragm sandwiched between the first opening and the second opening is formed in the second layer; The fourth step, in which the fourth layer with the third opening patterned is joined to the surface of the third layer on the side opposite to the side where the second layer is located in such a way that the third opening communicates with the second opening; and The fifth step, in which the base, the first layer, the second layer, the third layer and the fourth layer are covered with a covering part having a fourth opening and a fifth opening, so that the fourth opening exposes the third opening to the outside, and the fifth opening exposes the surface of the fourth layer on the side opposite to the side where the third layer is located to the outside, thereby forming a second diaphragm sandwiched between the second opening and the fifth opening in the fourth layer, the first opening is sealed, the pressure in the first opening is lower than the pressure in the second opening.

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