JP2005156164A - Pressure sensor, and manufacturing method for pressure sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pressure sensor of high performance having a wide pressure measuring range, and a manufacturing method therefor. <P>SOLUTION: This pressure sensor concerned consists of a sensor chip 2 having a frame 6 surrounding a diaphragm 5 and a periphery of the diaphragm 5, and having a diffusion type strain gage resistance 8 for detecting pressure applied to the diaphragm 5, and of a pedestal 3 joined to form a pressure reference chamber 4 in pressure detection with respect to the sensor chip 2 therebetween. In the pressure sensor, the diaphragm 5 is brought into a convex shape in view from the pressure reference chamber 4 when the second pressure value is equal to the first pressure value, and is brought into a flat shape in the view from the pressure reference chamber 4 when the second pressure value is pressure in an initial state of the pressure sensor, where the first pressure value is pressure of the pressure reference chamber 4 and where the second pressure value is atmospheric pressure in the periphery of the pressure sensor. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a pressure sensor that includes, for example, a diaphragm and a pressure reference chamber, and detects an absolute pressure such as atmospheric pressure or biological pressure, and a method of manufacturing the pressure sensor.

  For example, as shown in FIG. 9A and FIG. 9B, a conventional pressure sensor includes a diaphragm 5 obtained by processing a part of a semiconductor substrate into a thin shape, and a thick frame 6 surrounding the periphery of the diaphragm 5. And a sensor chip 2 having a diffusion strain gauge resistor 8, a diffusion lead resistor 9, and an electrode pad 10 as a pressure detector for detecting pressure applied to the diaphragm 5 on the surface, and the frame 6 Examples thereof include a base 3 made of glass, silicon or the like that is hermetically bonded in a substantially vacuum.

  Here, the closed space closed by the sensor chip 2 and the pedestal 3 is substantially vacuum, and functions as a pressure reference chamber 4 for detecting the pressure as an absolute pressure (for example, Patent Document 1, Patent Document). 2).

As another conventional pressure sensor, as shown in FIG. 9C, a fixed electrode 50 and a movable electrode 60 are formed on the opposing surfaces of the pedestal 3 and the diaphragm 5, respectively, without using strain gauge resistance. An electrostatic drive type that detects pressure as the capacitance between the electrodes 50 and 60 can also be mentioned. Note that “substantially vacuum” means not an absolute vacuum but a vacuum generally referred to in a semiconductor process.
Japanese Patent Laid-Open No. 5-149815 JP-A-6-213742

  However, in the pressure sensor as described above, when the operating atmosphere is, for example, approximately 1 atm, the pressure reference chamber, which is a closed space, is in a substantially vacuum, so that a differential pressure is generated above and below the diaphragm, and the diaphragm is initially There was a possibility of significant deformation in the state. Here, if the diaphragm deformation becomes too large, the linearity between the pressure detected by the pressure detection unit and the amount of deformation of the diaphragm is impaired, and the amount of deformation per unit pressure is also reduced, and the performance as a pressure sensor is reduced. to degrade. Therefore, when the diaphragm is greatly deformed in the initial state, there is a problem that the pressure measurement range is narrowed or the performance as the pressure sensor is deteriorated as compared with the case where the diaphragm is not deformed. .

  The present invention has been made to remedy the above problems, and an object of the present invention is to provide a high-performance pressure sensor having a large pressure measurement range and a manufacturing method of the pressure sensor.

  In order to achieve the above object, a pressure sensor according to claim 1 of the present invention includes a first substrate having a diaphragm, a frame surrounding the periphery of the diaphragm, and a pressure detection unit that detects pressure applied to the diaphragm. And a second substrate joined to form a closed space which becomes a pressure reference chamber at the time of pressure detection with the first substrate, wherein the first pressure value is a pressure of the closed space. When the second pressure value is the ambient pressure around the pressure sensor, the diaphragm has a convex shape when viewed from the closed space when the second pressure value is equal to the first pressure value, and the second pressure value When the pressure value is the pressure in the initial state of the pressure sensor, the pressure value is substantially flat when viewed from the closed space.

  A pressure sensor according to a second aspect of the present invention is the pressure sensor according to the first aspect, wherein at least the diaphragm includes a first layer having a compressive stress or a tensile stress with respect to the first substrate.

  The pressure sensor according to claim 3 of the present invention is the pressure sensor according to claim 2, wherein the first layer is in direct contact with the closed space when the first layer has a compressive stress with respect to the first substrate. Install on the outside.

  A pressure sensor according to a fourth aspect of the present invention is the pressure sensor according to the third aspect, wherein the first sensor has a tensile stress with respect to the first substrate, and the absolute value of the tensile stress is included in the first layer. A second layer smaller than the absolute value of the compressive stress is provided on the first layer.

  The pressure sensor according to a fifth aspect of the present invention is the pressure sensor according to the second aspect, wherein the first layer is in direct contact with the closed space when the first layer has a tensile stress with respect to the first substrate. On the inner side.

  A pressure sensor according to a sixth aspect of the present invention is the pressure sensor according to the fifth aspect, wherein the pressure sensor has a compressive stress with respect to the first substrate, and an absolute value of the compressive stress has the first layer. A second layer smaller than the absolute value of the tensile stress is provided between the first layer and the first substrate.

  The pressure sensor according to a seventh aspect of the present invention is the pressure sensor according to any one of the second to sixth aspects, wherein the first layer is a thin film layer or an impurity doped layer.

  A pressure sensor manufacturing method according to an eighth aspect of the present invention includes a first substrate having a diaphragm, a frame surrounding the periphery of the diaphragm, and a pressure detection unit that detects pressure applied to the diaphragm, and the first substrate. A pressure sensor manufacturing method comprising: a second substrate joined to form a closed space that serves as a pressure reference chamber for pressure detection with a substrate, wherein the first pressure value is the pressure of the closed space When the second pressure value is the ambient pressure around the pressure sensor, the second pressure value is equal to the first pressure value, and the diaphragm has a convex shape when viewed from the closed space. A step of bonding the substrate and the second substrate, and a step of setting the second pressure value to a pressure in an initial state of the pressure sensor and making the diaphragm substantially flat when viewed from the closed space.

  In the pressure sensor having such a configuration, when the first pressure value is the pressure in the closed space that is the pressure reference chamber and the second pressure value is the atmospheric pressure around the pressure sensor, the second pressure value is the first pressure value. If the diaphragm has a convex shape when viewed from the closed space when equal, and the second pressure value is the pressure in the initial state of the pressure sensor, the pressure is detected by making the diaphragm have a substantially flat shape when viewed from the closed space. In addition to ensuring a wide region in which linearity is obtained between the pressure detected by the section and the deformation amount of the diaphragm, the deformation amount of the diaphragm per unit pressure can also be increased. That is, a high-performance pressure sensor having a large pressure measurement range can be provided. Further, the above-described pressure sensor can be provided by the manufacturing method of the pressure sensor having such a configuration.

  Embodiments according to the present invention will be described below with reference to the drawings. In addition, in each figure, the structure which attached | subjected the same code | symbol shows that it is the same structure, The description is abbreviate | omitted.

  1st Embodiment of this invention is described based on FIG.1 and FIG.2. FIG. 1A is a cross-sectional view showing the sensor chip 2 before the base 3 is joined, and FIG. 1B is a cross-sectional view showing the pressure sensor 1 in a substantially vacuum, which will be described later. c) is a cross-sectional view showing the pressure sensor 1 in an initial state to be described later. FIG. 2 is a cross-sectional view showing a modification of the present embodiment.

  In the present embodiment, the pressure sensor 1 includes a sensor chip 2 which is a first substrate having a diaphragm 5 obtained by processing a part of a semiconductor substrate into a thin shape and a thick frame 6 surrounding the periphery of the diaphragm 5; A pedestal 3 that is a second substrate, a pressure reference chamber 4 that is a closed space formed between the sensor chip 2 and the pedestal 3, and has a compressive stress on the sensor chip 2 and is in direct contact with the pressure reference chamber 4. And a silicon oxide film 7 as a first layer provided on the outer side.

  The sensor chip 2 includes a diffusion-type strain gauge resistor 8 that is a pressure detection unit that detects the pressure of the diaphragm 5 on the surface of the diaphragm 5, and further includes a diffusion-type lead resistor 9 and an electrode pad 10. . The diffusion type strain gauge resistor 8, the diffusion type lead resistor 9, and the electrode pad 10 are electrically connected to each other. The first substrate is, for example, a silicon substrate, and the second substrate is, for example, a glass substrate or a silicon substrate. Here, in the present embodiment, the first layer is provided so as to cover the diaphragm 5 and the frame 6 on the outer side without directly contacting the pressure reference chamber 4, but so as to cover at least the diaphragm 5. Any configuration may be used. Note that “substantially vacuum” means not an absolute vacuum but a vacuum generally referred to in a semiconductor process.

  FIG. 1 shows an embodiment in which a surface opposite to the surface side of the sensor chip 2 provided with the diffusion strain gauge resistor 8, the diffusion lead resistor 9, and the electrode pad 10 is joined to the base 3. FIG. 2 shows an embodiment in which a diffusion strain gauge resistor 8, a diffusion lead resistor 9, and an electrode pad 10 are joined to a pedestal 3 on the surface side of a sensor chip 2.

  Below, an example of the manufacturing process of the pressure sensor 1 is demonstrated based on FIG. The first pressure value is the pressure in the pressure reference chamber 4 and the second pressure value is the ambient pressure around the pressure sensor 1. In addition, the initial state of the pressure sensor 1 means that the diffusion strain gauge resistor 8 that is a pressure detection unit is in an unloaded state.

  First, as shown in FIG. 1 (a), a diffusion type strain gauge resistor 8 and a diffusion type lead resistor 9 are formed on the sensor chip 2, and then the surface of the sensor chip 2 that is not in contact with the pressure reference chamber 4 is applied. Then, a silicon oxide film 7 having a compressive stress is formed on the sensor chip 2, and the diaphragm 5 is deformed in advance so as to be convex when viewed from the pressure reference chamber 4 side. Then, the frame 6 of the sensor chip 2 and the base 3 are hermetically bonded and joined so as to form the pressure reference chamber 4 in a substantially vacuum atmosphere. In this case, the first pressure value is substantially vacuum. In addition, when the base 3 is a glass substrate, for example, the sensor chip 2 and the base 3 are joined by anodic bonding.

  Then, the electrode pad 10 is connected to the diffusion type lead resistor 9. In a state where the sensor chip 2 and the pedestal 3 are joined in a vacuum atmosphere, the diaphragm 5 is convex as in the state shown in FIG. 1A, as shown in FIG. Here, the diaphragm 5 of the pressure sensor 1 has a pressure difference between the first pressure value and the second pressure value, for example, when the atmospheric pressure (substantially 1 atm) is used as an operating atmosphere. Deformation in the direction (hereinafter referred to as deformation A). Since the deformation A direction and the deformation (hereinafter referred to as deformation B) direction of the diaphragm 5 by the silicon oxide film 7 are opposite to each other, the deformation A and the deformation B have substantially the same absolute value. By adjusting the thickness of the silicon oxide film 7 in advance, the shape of the diaphragm 5 in the initial state of the pressure sensor 1 becomes substantially flat as shown in FIG.

  Here, the shape of the diaphragm 5 being substantially flat means that it is completely flat or flat within a range in which linearity is not impaired between the pressure detected by the pressure detector and the deformation amount of the diaphragm 5. Yes.

  For example, when the diaphragm 5 has a square shape of about 1 mm square and a thickness of about 30 μm, the deformation amount of the diaphragm 5 in an atmosphere of 1 atm is formed by forming the silicon oxide film 7 about 0.8 μm. Can be reduced to half or less of the deformation when the silicon oxide film 7 is not formed.

  The pressure sensor 1 according to this embodiment includes a silicon oxide film 7 in which the diaphragm 5 has a compressive stress with respect to the sensor chip 2, and is viewed from the pressure reference chamber 4 when the first pressure value is equal to the pressure of the second pressure value. When the diaphragm 5 has a convex shape and the second pressure value is the pressure in the initial state, the diaphragm 5 has a substantially flat shape as viewed from the pressure reference chamber 4, so that the pressure detected by the pressure detector It is possible to secure a wide region in which linearity is obtained between the deformation amount of the diaphragm 5 and to increase the deformation amount of the diaphragm 5 per unit pressure. That is, a high-performance pressure sensor having a large pressure measurement range can be provided.

  In addition, since the variation in the deformation amount of the diaphragm 5 can be reduced, the variation in sensor characteristics can be reduced, and the yield can be improved. That is, if the performance is the same, a small and low-cost pressure sensor can be provided. Moreover, using the silicon oxide film 7 which is a thin film as the first layer and using the silicon oxide film 7 for adjusting the deformation amount of the diaphragm 5 makes the shape of the diaphragm 5 substantially flat without increasing the number of manufacturing steps. Can be Note that the silicon oxide film 7 as the first layer also functions as a surface protective film. Further, as in this embodiment, for example, a thin film having electrical insulation such as the silicon oxide film 7 is used as the first layer, so that electrical insulation between the pressure detection unit and the first layer is achieved. There is no need to consider.

  In the present embodiment, the case where the first pressure value is approximately vacuum and the second pressure value changes from the first pressure value to approximately 1 atmosphere is exemplified, but the first pressure value and the second pressure value (or The range is not limited to these values. For example, when the sensor chip 2 and the pedestal 3 are joined at atmospheric pressure (approximately 1 atm) and the initial state of the pressure sensor is 2 atm, the first pressure value is approximately 1 atm, and the second pressure The value changes from approximately 1 atm to 2 atm.

Here, in the first embodiment, for example, the thin silicon oxide film 7 having a compressive stress with respect to the sensor chip 2 is used as the first layer. However, the first layer has a compressive stress with respect to the first substrate. For example, it is not limited to the silicon oxide film, and an impurity doped layer (not shown) such as a boron doped layer having a compressive stress with respect to the silicon substrate as the first substrate may be used. The diaphragm 5 is formed by forming a boron-doped layer having an impurity concentration of about 1.0 × 10 ²⁰ cm ⁻³ and a diffusion depth of about 3 μm, for example, when the planar shape is a square of about 1 mm square and the thickness is about 30 μm. The amount of deformation of the diaphragm 5 in an atmosphere of 1 atm can be reduced to half or less of the amount of deformation when there is no boron-doped layer. Since the impurity-doped layer is formed by diffusing impurities in the substrate, the stress can be adjusted without increasing the thickness of the diaphragm 5 by designing in consideration of electrical insulation with the diffusion strain gauge resistor 8. .

  Next, an embodiment in which a second layer to be described later is provided on the silicon oxide film 7 in the first embodiment will be described as a second embodiment of the present invention with reference to FIGS. FIG. 3A is a cross-sectional view showing the sensor chip 2 before the base 3 is joined, and FIG. 3B is a cross-sectional view showing the pressure sensor 1 in the initial state. FIG. 4 is a cross-sectional view showing a modification of the present embodiment. Here, FIG. 3 corresponds to the modification of FIG. 1 in the first embodiment, and FIG. 4 corresponds to the modification of FIG. 2 in the first embodiment.

  In this embodiment, the difference from the first embodiment is that, as shown in FIGS. 3 and 4, a second layer (to be described later) is formed outside the pressure reference chamber 4 of the silicon oxide film 7 as the first layer. It is a point provided.

  Here, the second layer has a tensile stress on the sensor chip 2 and the material is not particularly limited as long as the absolute value of the tensile stress is smaller than the absolute value of the compressive stress of the silicon oxide film 7. However, in the present embodiment, for example, the silicon nitride film 11 which is a thin film is used. Further, the first layer has a tensile stress with respect to the sensor chip 2 as the first substrate, and the absolute value of the tensile stress is smaller than the absolute value of the compressive stress of the silicon oxide film 7 as the first layer. By adjusting the film thicknesses of the silicon oxide film 7 and the silicon nitride film 11 so that the diaphragm 5 is bonded to the sensor chip 2 and the pedestal 3 in the same manner as in the first embodiment, It can be deformed so as to be convex in advance when viewed from the reference chamber 4 side.

  In the present embodiment, the silicon oxide film 7 and the silicon nitride film 11 are formed by, for example, thermal oxidation or low pressure CVD. In this case, the thickness of the silicon oxide film 7 is equal to that of the silicon nitride film 11. 4 times. The silicon oxide film 7 as the first layer and the silicon nitride film 11 as the second layer function as a surface protective film.

  Here, regarding the manufacturing process of the pressure sensor 1, after the diffusion strain gauge resistor 8 and the diffusion lead resistor 9 are formed on the sensor chip 2, the surface of the sensor chip 2 that is not in contact with the pressure reference chamber 4 is Since the steps after forming the silicon oxide film 7 and the silicon nitride film 11 and deforming the diaphragm 5 so as to be convex in advance when viewed from the pressure reference chamber 4 side are the same as those in the first embodiment, the description is omitted. Omitted.

  In the pressure sensor according to the present embodiment, the silicon oxide film 7 that is the first layer is further provided with the silicon nitride film 11 that is the second layer, so that the total thickness of the silicon oxide film 7 and the silicon nitride film 11 is increased. The stress on the diaphragm 5 can be maintained at an appropriate value while increasing the function as a surface protective film by increasing the thickness. Further, by changing the film thickness of the silicon nitride film 11 in accordance with the film thickness of the silicon oxide film 7, the stress value for the diaphragm 5 can be easily adjusted.

  Next, an embodiment in which the first layer is provided so as to be in direct contact with the pressure reference chamber 4 in the first embodiment will be described as a third embodiment of the present invention with reference to FIGS. 5 and 6. FIG. 5A is a cross-sectional view showing the sensor chip 2 before joining the pedestal 3, and FIG. 5B is a cross-sectional view showing the pressure sensor 1 in the initial state. FIG. 6 is a cross-sectional view showing a modification of the present embodiment.

  In this embodiment, as shown in FIG. 5, the pressure sensor 1 has a tensile stress with respect to the first substrate instead of the first layer in the first embodiment, and is in direct contact with the pressure reference chamber 4. The first layer is provided on the inner side of the pressure reference chamber 4.

  In this embodiment, for example, the silicon nitride film 12 is used as the first layer. However, the first layer is not limited to the silicon nitride film 12 as long as it has a compressive stress with respect to the first substrate.

  Hereinafter, an example of the manufacturing process of the pressure sensor 1 will be described with reference to FIG. 5, but the description of common parts in the first embodiment is omitted for the sake of simplicity. As shown in FIG. 5A, after the diffusion strain gauge resistor 8 and the diffusion lead resistor 9 are formed on the sensor chip 2, the diaphragm 5 on the side in direct contact with the pressure reference chamber 4 and the surface of the frame 6 are in contact with each other. Then, a silicon nitride film 12 having tensile stress is formed on the sensor chip 2 (however, the silicon nitride film 12 is not provided on the joint surface with the base 3), and the diaphragm 5 is viewed from the pressure reference chamber 4 side. It is deformed in advance so as to be convex. In the use atmosphere, as shown in FIG. 5B, the thickness of the silicon nitride film 12 is adjusted in advance to make the shape of the diaphragm 5 substantially flat.

  For example, when the planar shape is a square of about 1 mm square and the thickness is about 30 μm, the deformation amount of the diaphragm 5 in an atmosphere of 1 atm is obtained by forming the silicon nitride film 12 about 0.2 μm. Can be reduced to less than half the amount of deformation when the silicon nitride film 12 is not formed.

  In FIG. 5, the surface (surface provided with the first layer) opposite to the surface side of the sensor chip 2 provided with the diffusion strain gauge resistor 8, the diffusion lead resistor 9, and the electrode pad 10 is the base 3. FIG. 6 shows an embodiment in which the diffusion strain gauge resistor 8, the diffusion lead resistor 9, and the electrode pad 10 are bonded to the base 3 on the surface side of the sensor chip 2. . As shown in FIG. 5, the silicon nitride film 12 is not provided at the location where the sensor chip 2 and the base 3 are joined.

Here, in the third embodiment, the silicon nitride film 12 having a tensile stress with respect to the first substrate is used as the first layer, but a boron doped layer having a tensile stress with respect to the silicon substrate as the first substrate. An impurity doped layer (not shown) may be used. The diaphragm 5 is formed by forming a boron-doped layer having an impurity concentration of about 1.0 × 10 ²⁰ cm ⁻³ and a diffusion depth of about 3 μm, for example, when the planar shape is a square of about 1 mm square and the thickness is about 30 μm. The amount of deformation of the diaphragm 5 in an atmosphere of 1 atm can be reduced to half or less of the amount of deformation when there is no boron-doped layer.

  The pressure sensor 1 according to this embodiment includes a silicon nitride film 12 in which the diaphragm 5 has a compressive stress with respect to the sensor chip 2, and is viewed from the pressure reference chamber 4 when the first pressure value is equal to the pressure of the second pressure value. When the diaphragm 5 has a convex shape and the second pressure value is the pressure in the initial state, the diaphragm 5 has a substantially flat shape as viewed from the pressure reference chamber 4, so that the pressure detected by the pressure detector It is possible to secure a wide region in which linearity is obtained between the deformation amount of the diaphragm 5 and to increase the deformation amount of the diaphragm 5 per unit pressure. That is, a high-performance pressure sensor having a large pressure measurement range can be provided.

  In addition, since the variation in the deformation amount of the diaphragm 5 can be reduced, the variation in sensor characteristics can be reduced, and the yield can be improved. That is, if the performance is the same, a small and low-cost pressure sensor can be provided. Moreover, using the silicon nitride film 12 which is a thin film as the first layer and using the silicon nitride film 12 for adjusting the deformation amount of the diaphragm 5 makes the shape of the diaphragm 5 substantially flat without increasing the number of manufacturing steps. Can be Note that the silicon nitride film 12 as the first layer also functions as a surface protective film. Further, as in the present embodiment, by using a thin film having electrical insulation such as the silicon nitride film 12 as the first layer, electrical insulation between the pressure detection unit and the first layer is achieved. There is no need to consider.

  Next, an embodiment in which a second layer (to be described later) is provided between the silicon nitride film 12 as the first layer and the sensor chip 2 in the third embodiment will be described as a fourth embodiment of the present invention with reference to FIGS. Based on FIG. 7A is a cross-sectional view showing the sensor chip 2 before the base 3 is joined, and FIG. 7B is a cross-sectional view showing the pressure sensor 1 in the initial state. FIG. 7 is a cross-sectional view showing a modification of the present embodiment. Here, FIG. 7 corresponds to the modification of FIG. 5 in the third embodiment, and FIG. 8 corresponds to the modification of FIG. 6 in the first embodiment.

  This embodiment is different from the third embodiment in that a second layer is provided between the sensor chip 2 and the silicon nitride film 12 as shown in FIGS. 7 corresponds to the modification of FIG. 5 in the third embodiment, and FIG. 8 corresponds to the modification of FIG. 6 in the third embodiment.

  Here, the second layer has a compressive stress with respect to the sensor chip 2, and the material is not particularly limited as long as the absolute value of the compressive stress is smaller than the absolute value of the tensile stress of the silicon nitride film 12. However, in this embodiment, for example, the silicon oxide film 13 which is a thin film is used.

  Each of the silicon nitride film 12 and the silicon oxide film 13 has a thickness that the silicon oxide film 13 has a compressive stress on the sensor chip 2, and the absolute value of this compressive stress is the tensile stress of the silicon nitride film 12. By adjusting so as to be smaller than the absolute value, the diaphragm 5 becomes convex in advance as seen from the pressure reference chamber 4 side before joining the sensor chip 2 and the pedestal 3 as in the third embodiment. Can be deformed.

  In this embodiment, the silicon nitride film 12 and the silicon oxide film 13 are formed by, for example, thermal oxidation or low pressure CVD. In this case, the film thickness of the silicon oxide film 13 is equal to the film thickness of the silicon nitride film 12. 4 times or more.

  The description of the manufacturing process of the pressure sensor 1 is omitted because it is common to the process described in any of the first to third embodiments. As shown in FIGS. 7 and 8, the silicon nitride film 12 and the silicon oxide film 13 are not provided on the joint surface between the sensor chip 2 and the pedestal 3.

  In the pressure sensor according to the present embodiment, the silicon nitride film 12 that is the second layer is further provided with the silicon oxide film 13 that is the second layer, so that the total thickness of the silicon nitride film 12 and the silicon oxide film 13 is increased. The stress on the diaphragm 5 can be maintained at an appropriate value while increasing the function as a surface protective film by increasing the thickness. Further, by changing the film thickness of the silicon nitride film 12 in accordance with the film thickness of the silicon oxide film 13, the stress value for the diaphragm 5 can be easily adjusted. Further, as in this embodiment, for example, by using a thin film having electrical insulation such as the silicon oxide film 13 as the second layer, electrical insulation between the pressure detection unit and the second layer is achieved. There is no need to consider.

  Here, in the first embodiment to the fourth embodiment, the pressure sensor 1 has a configuration using the strain gauge resistor 8, but may be an electrostatic drive type.

It is sectional drawing which shows the pressure sensor and sensor chip which concern on 1st Embodiment of this invention. It is sectional drawing which shows the deformation | transformation form of the pressure sensor which concerns on 1st Embodiment of this invention, and a sensor chip. It is sectional drawing which shows the pressure sensor and sensor chip which concern on 2nd Embodiment of this invention. It is sectional drawing which shows the deformation | transformation form of the pressure sensor which concerns on 2nd Embodiment of this invention, and a sensor chip. It is sectional drawing which shows the pressure sensor and sensor chip which concern on 3rd Embodiment of this invention. It is sectional drawing which shows the deformation | transformation form of the pressure sensor which concerns on 3rd Embodiment of this invention, and a sensor chip. It is sectional drawing which shows the pressure sensor and sensor chip which concern on 4th Embodiment of this invention. It is sectional drawing which shows the deformation | transformation form of the pressure sensor which concerns on 4th Embodiment of this invention, and a sensor chip. It is sectional drawing which shows the pressure sensor which concerns on a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pressure sensor 2 Sensor chip 3 Base 4 Pressure reference chamber 5 Diaphragm 6 Frame 7, 13 Silicon oxide film 8 Gauge resistance 9 Diffusion-type lead resistance 10 Electrode pad 11, 12 Silicon nitride film

Claims (8)

A first substrate having a diaphragm, a frame surrounding the periphery of the diaphragm, and a pressure detection unit for detecting pressure applied to the diaphragm, and a closed space serving as a pressure reference chamber for pressure detection between the first substrate and the first substrate. A pressure sensor comprising a second substrate joined to form a pressure sensor,
When the first pressure value is the pressure of the closed space and the second pressure value is the ambient pressure around the pressure sensor,
The diaphragm is
When the second pressure value is equal to the first pressure value, the second pressure value is convex when viewed from the closed space;
When the second pressure value is a pressure in an initial state of the pressure sensor, the pressure sensor has a substantially flat shape when viewed from the closed space.   The pressure sensor according to claim 1, wherein at least the diaphragm includes a first layer having compressive stress or tensile stress with respect to the first substrate.   The pressure sensor according to claim 2, wherein the first layer is provided on the outer side without directly contacting the closed space when the first layer has a compressive stress with respect to the first substrate.   4. The second layer according to claim 3, wherein a second layer having a tensile stress with respect to the first substrate and having an absolute value of the tensile stress smaller than an absolute value of the compressive stress of the first layer is provided on the first layer. Pressure sensor.   The pressure sensor according to claim 2, wherein the first layer is provided on an inward side so as to be in direct contact with the closed space when having a tensile stress with respect to the first substrate.   A second layer having a compressive stress with respect to the first substrate and having an absolute value of the compressive stress smaller than an absolute value of the tensile stress of the first layer is interposed between the first layer and the first substrate. The pressure sensor according to claim 5 provided.   The pressure sensor according to any one of claims 2 to 6, wherein the first layer is a thin film layer or an impurity doped layer. A first substrate having a diaphragm, a frame surrounding the periphery of the diaphragm, and a pressure detection unit for detecting pressure applied to the diaphragm, and a closed space serving as a pressure reference chamber for pressure detection between the first substrate and the first substrate. A method of manufacturing a pressure sensor comprising a second substrate joined to form a pressure sensor,
When the first pressure value is the pressure of the closed space and the second pressure value is the ambient pressure around the pressure sensor,
Bonding the first substrate and the second substrate so that the second pressure value is equal to the first pressure value, and the diaphragm has a convex shape when viewed from the closed space;
And a step of making the second pressure value a pressure in an initial state of the pressure sensor and making the diaphragm substantially flat when viewed from the closed space.

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