JP6687197B2 - Pressure sensor - Google Patents

Description

  The present invention relates to a pressure sensor.

  As a pressure sensor, an electrostatic capacitance type pressure sensor is known which detects pressure by a change in electrostatic capacitance between electrodes.

  Such a capacitance type pressure sensor has a structure in which the diaphragm portion is sandwiched by a pair of insulators. Voids are formed between the diaphragm portion and the one insulator and between the diaphragm portion and the other insulator, respectively. Further, an electrode is formed on the surface of each insulator facing the diaphragm. In order to introduce the measurement pressure into the gap formed between the diaphragm portion and the one insulator, the measurement pressure introducing hole is formed in the one insulator. Moreover, in order to introduce the reference pressure into the gap formed between the diaphragm portion and the other insulator, the reference pressure introducing hole is formed in the other insulator. (For example, see Patent Document 1)

JP-A-8-189870

  In order to improve the detection accuracy of the capacitance type pressure sensor, it is necessary to keep the reference pressure constant. In order to ensure that the reference pressure is kept constant, it is conceivable to fill the reference pressure introducing hole with an electrode material and hermetically seal it. However, it takes time and labor to fill the reference pressure introducing hole with the electrode material, and the manufacturing cost increases. Further, if the reference pressure introducing hole is filled with the electrode material, the surface of the electrode material may be roughened. Therefore, if a wiring is formed so as to be connected to the surface, poor conduction may occur.

  An object of the present invention is to provide a pressure sensor that has improved detection accuracy at low cost.

  A pressure sensor according to the present invention includes a first insulating layer, a conductive layer, a second insulating layer, a first detection electrode portion, a second detection electrode portion, and a lead electrode portion. The conductive layer is stacked on the first insulating layer. The second insulating layer is laminated on the conductive layer, and the first through hole and the second through hole that penetrate in the thickness direction are formed. The first detection electrode portion is arranged on a part of the surface of the first insulating layer facing the conductive layer. The second detection electrode portion is arranged so as to extend from a part on a surface of the second insulating layer facing the conductive layer to a wall surface surrounding the first through hole. The extraction electrode portion is arranged on the wall surface surrounding the second through hole of the second insulating layer. The conductive layer includes a diaphragm portion and an island portion. The diaphragm portion forms a reference pressure space with the first insulating layer and a measurement pressure space communicating with the first through hole between the diaphragm portion and the second insulating layer. And the thickness is thin. The island portion is located at a position overlapping the second through hole when seen in a plan view, at a position apart from the diaphragm portion, and is surrounded by an annular space that penetrates in the thickness direction. The first detection electrode portion is connected to the end portion of the island portion on the first insulating layer side. The extraction electrode portion is connected to the end portion of the island portion on the second insulating layer side.

  In the pressure sensor of the present invention, the reference pressure space is formed between the first insulating layer and the diaphragm portion. By doing so, a closed space surrounded by the first insulating layer and the diaphragm portion is formed, and the reference pressure can be reliably kept constant. As a result, the detection accuracy of the pressure sensor can be improved.

  Further, in the pressure sensor of the present invention, the conductive layer includes an island portion surrounded by an annular space penetrating in the thickness direction. Then, the end portion of the island portion is connected to the first detection electrode portion and the extraction electrode portion. By doing so, the lead-out electrode portion and the first detection electrode portion can be connected via the island portion without providing the through hole in the first insulating layer and burying the through hole in the first insulating layer. As a result, it is possible to suppress the occurrence of conduction failure while suppressing the manufacturing cost.

  As described above, according to the pressure sensor of the present invention, it is possible to provide a pressure sensor with improved detection accuracy at low cost.

  In the pressure sensor, the pressure in the reference pressure space may be less than atmospheric pressure. More specifically, it may be 30 kPa or more and 100 kPa or less. By doing so, it is possible to provide a pressure sensor capable of measuring a pressure below atmospheric pressure.

  In the above pressure sensor, the conductive layer may be made of silicon to which conductivity is imparted by introducing impurities. Silicon to which conductivity is imparted by introducing impurities is suitable as a material forming the conductive layer of the present invention.

  In the above pressure sensor, the first insulating layer and the second insulating layer may be made of glass substrates. The glass substrate is suitable as a material forming the first insulating layer and the second insulating layer.

  According to the pressure sensor, it is possible to provide a pressure sensor with improved detection accuracy at low cost.

It is a schematic sectional drawing which shows an example of a structure of a pressure sensor. FIG. 7 is a schematic cross-sectional view for explaining the method for manufacturing the pressure sensor. FIG. 7 is a schematic cross-sectional view for explaining the method for manufacturing the pressure sensor. FIG. 7 is a schematic cross-sectional view for explaining the method for manufacturing the pressure sensor. FIG. 7 is a schematic cross-sectional view for explaining the method for manufacturing the pressure sensor. FIG. 7 is a schematic cross-sectional view for explaining the method for manufacturing the pressure sensor. FIG. 7 is a schematic cross-sectional view for explaining the method for manufacturing the pressure sensor. FIG. 7 is a schematic cross-sectional view for explaining the method for manufacturing the pressure sensor. FIG. 7 is a schematic cross-sectional view for explaining the method for manufacturing the pressure sensor. FIG. 7 is a schematic cross-sectional view for explaining the method for manufacturing the pressure sensor. FIG. 7 is a schematic cross-sectional view for explaining the method for manufacturing the pressure sensor. FIG. 7 is a schematic cross-sectional view for explaining the method for manufacturing the pressure sensor. FIG. 7 is a schematic cross-sectional view for explaining the method for manufacturing the pressure sensor. FIG. 7 is a schematic cross-sectional view for explaining the method for manufacturing the pressure sensor.

[Details of Embodiment of Present Invention]
Next, an embodiment of a pressure sensor according to the present invention will be described below with reference to the drawings. In the following drawings, the same or corresponding parts will be denoted by the same reference numerals and the description thereof will not be repeated.

  With reference to FIG. 1, the pressure sensor 1 according to the first embodiment includes a first insulating layer 10, a conductive layer 30, a second insulating layer 20, a first detection electrode section 40, and a second detection electrode section 50. And a lead electrode portion 60. The first insulating layer 10 has a flat plate shape. Specifically, the first insulating layer 10 is a parallel plate glass substrate. The conductive layer 30 is laminated on and in contact with the one main surface 11 of the first insulating layer 10. The conductive layer 30 is directly bonded to the one main surface 11 of the first insulating layer 10. Specifically, the conductive layer 30 is made of silicon to which conductivity is imparted by introducing impurities.

  The conductive layer 30 includes a diaphragm portion 301 and a support portion 303. The diaphragm portion 301 has a disc shape. The support portion 303 is arranged so as to surround the outer periphery of the diaphragm portion 301. The support part 303 includes an island part 302.

  The diaphragm portion 301 is formed to be thinner than other portions of the conductive layer 30. One end surface 303A of the support portion 303 in the thickness direction is in contact with and connected to the first insulating layer 10. One end surface 303A of the support portion 303 in the thickness direction is directly bonded to the first insulating layer 10. The other end surface 303B of the support portion 303 in the thickness direction is in contact with and connected to the second insulating layer 20. The other end surface 303B of the support portion 303 in the thickness direction is directly joined to the second insulating layer 20. The electrode portion 80 is formed on a part of the other end surface 303B of the support portion 303 in the thickness direction. The electrode portion 80 is formed separately from the second detection electrode portion 50 and the extraction electrode portion 60. A reference pressure space 91 is formed between the diaphragm portion 301 and the first insulating layer 10. A measurement pressure space 92 is formed between the diaphragm portion 301 and the second insulating layer 20.

  The island portion 302 has a columnar shape (for example, a cylindrical shape). The island portion 302 is arranged at a position apart from the diaphragm portion 301. The island portion 302 is surrounded by an annular space 95 penetrating in the thickness direction of the support portion 303. One end surface 302A of the island portion 302 is in contact with and connected to the first insulating layer 10. One end surface 302A of the island portion 302 is directly bonded to the first insulating layer 10. The other end surface 302B of the island portion 302 is in contact with and connected to the second insulating layer 20. The other end surface 302B of the island portion 302 is directly bonded to the second insulating layer 20.

  The second insulating layer 20 is laminated by being in contact with the surface of the conductive layer 30 opposite to the side in contact with the first insulating layer 10. The second insulating layer 20 is directly bonded to the surface of the conductive layer 30 on the side opposite to the side in contact with the first insulating layer 10.

  A first through hole 93 that penetrates the second insulating layer 20 in the thickness direction is formed in the second insulating layer 20. The first through hole 93 has a truncated cone shape. The first through hole 93 is formed so that the diameter becomes smaller toward the conductive layer 30 side. The first through hole 93 and the measurement pressure space 92 communicate with each other.

  A second through hole 94 is formed in the second insulating layer 20 so as to penetrate the second insulating layer 20 in the thickness direction. The second through hole 94 is formed separately from the first through hole 93. The second through hole 94 has a truncated cone shape. The second through hole 94 is formed so that the diameter becomes smaller toward the conductive layer 30 side. The second through hole 94 is formed at a position overlapping the island portion 302 when seen in a plan view. That is, the other end surface 302B of the island portion 302 is formed so as to be exposed in the second through hole 94.

  The first detection electrode portion 40 is formed on a part of the main surface 11 of the first insulating layer 10. The first detection electrode portion 40 is formed on a part of the surface facing the diaphragm portion 301 with the reference pressure space 91 interposed therebetween. One end of the first detection electrode portion 40 is connected to the one end surface 302A of the island portion 302. The other end of the first detection electrode portion 40 is located in a region on the surface of the first insulating layer 10 corresponding to the reference pressure space 91. The first detection electrode portion 40 extends from a region on the surface of the first insulating layer 10 corresponding to the reference pressure space 91 to a region connected to the one end surface 302A of the island portion.

  The second detection electrode portion 50 extends from a part on the surface 21 of the second insulating layer 20 facing the diaphragm portion 301 to the wall surface 23 surrounding the first through hole 93 with the measurement pressure space 92 interposed therebetween. It is formed. One end of the second detection electrode portion 50 is located in a region on the surface of the second insulating layer 20 corresponding to the measurement pressure space 92, and the other end thereof is different from the conductive layer 30 of the second insulating layer 20. Located on the opposite surface 22. The second detection electrode portion 50 extends from a region on the surface of the second insulating layer 20 corresponding to the measurement pressure space 92 to a region on the surface 22 of the second insulating layer 20 opposite to the conductive layer 30.

  The lead electrode portion 60 is formed on the wall surface 24 surrounding the second through hole 94 of the second insulating layer 20. One end of the lead electrode portion 60 is connected to the other end 302B of the island portion 302. The other end of the lead electrode portion 60 is located on the surface 22 of the second insulating layer 20 opposite to the conductive layer 30. The lead electrode portion 60 extends from a region connected to the other end 302B of the island portion 302 to a region on the surface 22 of the second insulating layer 20 opposite to the conductive layer 30.

  Next, the operation of the pressure sensor 1 will be described. In the pressure sensor 1, the reference pressure space 91 taken into the first insulating layer 10 and the diaphragm portion 301 is kept constant at the reference pressure. The pressure in the reference pressure space 91 is, for example, less than atmospheric pressure. More specifically, it is 30 kPa or more and 100 kPa or less. When the measurement pressure space 92 is brought into a state of communicating with the space whose pressure is to be measured via the first through hole 93, the diaphragm portion 301 elastically deforms so as to bend. For example, when the pressure in the measurement pressure space 92 is higher than the pressure in the reference pressure space 91, the diaphragm portion 301 elastically deforms so as to curve toward the first insulating layer 10 side.

  The elastic deformation of the diaphragm portion 301 changes the distance between the diaphragm portion 301 and the first detection electrode portion 40 and the distance between the diaphragm portion 301 and the second detection electrode portion 50. As a result, the capacitance C1 between the diaphragm portion 301 and the first detection electrode portion 40 and the capacitance C2 between the diaphragm portion 301 and the second detection electrode portion 50 change. The capacitance C2 between the diaphragm portion 301 and the second detection electrode portion 50 is measured by the second detection electrode portion 50 and the electrode portion 80. The first detection electrode section 40 is electrically connected to the island section 302. The island portion 302 is electrically connected to the lead electrode portion 60. Therefore, the capacitance C1 between the diaphragm portion 301 and the first detection electrode portion 40 is measured by the extraction electrode portion 60 and the electrode portion 80.

  The rate of change of the electrostatic capacitance C1 between the diaphragm portion 301 and the first detection electrode portion 40 and the electrostatic capacitance C2 between the diaphragm portion 301 and the second detection electrode portion 50 (for example, the electrostatic capacitance C1 and the electrostatic capacitance C1). The pressure can be detected by calculating the difference between the capacitance C2 and the sum of the capacitance C1 and the capacitance C2. Further, pressure detection can also be performed by measuring the amount of change between the voltage between the diaphragm portion 301 and the first detection electrode portion 40 and the voltage between the diaphragm portion 301 and the second detection electrode portion 50. it can.

  Here, in the pressure sensor 1 of the present embodiment, the reference pressure space 91 is formed between the first insulating layer 10 and the diaphragm portion 301. By doing so, a closed space surrounded by the first insulating layer 10 and the diaphragm portion 301 is formed, and the reference pressure can be reliably kept constant. As a result, the detection accuracy of the pressure sensor 1 can be improved.

  Further, in pressure sensor 1 of the present embodiment, conductive layer 30 includes an island portion 302 surrounded by an annular space that penetrates in the thickness direction. Then, the ends of the island portion 302 are connected to the first detection electrode portion 40 and the extraction electrode portion 60. By doing so, it is possible to connect the lead electrode portion 60 and the first detection electrode portion 40 via the island portion 302 without providing a through hole in the first insulating layer 10 and burying the through hole in the first insulating layer 10. it can. As a result, it is possible to suppress the occurrence of conduction failure while suppressing the manufacturing cost.

  Next, an outline of a method of manufacturing the pressure sensor 1 will be described. Referring to FIG. 2, first, second insulating layer 20 made of a glass substrate is prepared. More specifically, heat resistant glass such as borosilicate glass is prepared.

  Next, referring to FIGS. 2 and 3, first through hole 93 and second through hole 94 are formed in second insulating layer 20. The first through hole 93 and the second through hole 94 have openings corresponding to the shapes of the first through hole 93 and the second through hole 94, for example, on one main surface 22 of the second insulating layer 20. It can be formed by forming a mask layer and then performing etching.

  3 and 4, wall surface 23 surrounding one main surface 22 of the second insulating layer, the other main surface 21 of the second insulating layer, and first through hole 93 of second insulating layer 20. The second detection electrode portion 50 is formed on the top. The second detection electrode portion 50 has, for example, a mask layer having an opening corresponding to the shape of the second detection electrode portion 50 on one main surface 22 of the second insulating layer 20 and the other main surface 21 of the second insulating layer 20. Can be formed by performing sputtering after forming.

  Next, referring to FIG. 5, a first insulating layer 10 made of a glass substrate is prepared. More specifically, heat resistant glass such as borosilicate glass is prepared. Then, referring to FIGS. 5 and 6, the first detection electrode portion 40 is formed on the one main surface 11 of the first insulating layer 10. The first detection electrode portion 40 is formed by, for example, forming a mask layer having an opening corresponding to the shape of the first detection electrode portion 40 on one main surface 11 of the first insulating layer 10 and then performing sputtering. Can be formed.

  Next, referring to FIG. 7, a conductive layer made of silicon to which conductivity is imparted by introducing impurities is prepared. More specifically, a silicon substrate having boron introduced as a P-type impurity and a silicon substrate having arsenic introduced as an N-type impurity are prepared. Then, referring to FIGS. 7 and 8, recess 33 is formed in a part of one main surface 31 of conductive layer 30. The recess 33 can be formed, for example, by forming a mask layer having an opening corresponding to the shape of the recess 33 on a part of the one main surface 31 of the conductive layer 30 and then performing etching.

  Next, referring to FIGS. 8, 4 and 9, second insulating layer 20 shown in FIG. 4 is bonded onto one main surface 31 of conductive layer 30. More specifically, the other main surface 21 of the second insulating layer 20 and one main surface 31 of the conductive layer 30 are bonded by the anodic bonding method.

  Next, referring to FIGS. 9 and 10, the other main surface 32 of conductive layer 30 is processed so that the thickness of conductive layer 30 is reduced. Further, referring to FIGS. 10 and 11, a recess 34 is formed in a part of the other main surface 32 of conductive layer 30. The recess 34 is formed at a position corresponding to the recess 33 formed on the one main surface 31 side of the conductive layer. The recess 34 can be formed, for example, by forming a mask layer having an opening corresponding to the shape of the recess 34 on a part of the other main surface 32 of the conductive layer 30 and then performing etching.

  Next, referring to FIGS. 11 and 12, island portion 302 surrounded by annular space 95 is formed in conductive layer 30. The island portion 302 can be formed, for example, by forming a mask layer having an opening corresponding to the annular space 95 on the other main surface 32 of the conductive layer 30 and then performing etching.

  Next, referring to FIGS. 12, 6 and 13, first insulating layer 10 shown in FIG. 6 is bonded onto the other main surface 32 of conductive layer 30. More specifically, the other main surface 32 of the conductive layer 30 and one main surface 11 of the first insulating layer 10 are bonded by the anodic bonding method.

  Next, referring to FIGS. 13 and 14, the extraction electrode portion 60 is formed on the one main surface 22 of the second insulating layer 20, the wall surface 24 surrounding the second through hole, and the other end surface 302B of the island portion 302. To be done. Further, the electrode portion 80 is formed on a part of the one main surface 31 of the conductive layer 30. For the extraction electrode portion 60 and the electrode portion 80, for example, a mask layer having openings corresponding to the extraction electrode portion 60 and the electrode portion 80 is formed on one main surface 22 of the second insulating layer 20, and then sputtering is performed. Can be formed. The pressure sensor 1 of the present embodiment can be manufactured by the above procedure.

  It should be understood that the embodiments disclosed this time are exemplifications in all respects and are not restrictive in any way. The scope of the present invention is defined not by the above description but by the scope of the claims, and is intended to include meanings equivalent to the scope of the claims and all modifications within the scope.

  The pressure sensor of the present invention can be particularly advantageously applied to a pressure sensor that requires high detection accuracy at low cost.

  DESCRIPTION OF SYMBOLS 1 pressure sensor, 10 1st insulating layer, 11 main surface, 20 2nd insulating layer, 21 main surface, 22 main surface, 23 wall surface, 24 wall surface, 30 conductive layer, 31 main surface, 32 main surface, 33 concave part, 34 Recessed portion, 301 diaphragm portion, 302 island portion, 302A end surface, 302B end surface, 303 support portion, 303A end surface, 303B end surface, 40 first detection electrode portion, 50 second detection electrode portion, 60 lead electrode portion, 80 electrode portion, 91 Reference pressure space, 92 measurement pressure space, 93 first through hole, 94 second through hole, 95 space.

Claims (4)

A first insulating layer,
A conductive layer laminated on the first insulating layer,
A second insulating layer laminated on the conductive layer, in which a first through hole and a second through hole penetrating in the thickness direction are formed;
A first detection electrode portion arranged on a part of a surface of the first insulating layer facing the conductive layer;
A second detection electrode portion arranged so as to extend from a part of a surface of the second insulating layer facing the conductive layer to a wall surface surrounding the first through hole;
An extraction electrode portion arranged on a wall surface surrounding the second through hole of the second insulating layer;
Equipped with
The conductive layer is
By forming a reference pressure space with the first insulating layer and a measuring pressure space communicating with the first through hole with the second insulating layer, compared to other portions. With a thin diaphragm part,
A position overlapping with the second through hole when seen in a plan view, arranged at a position away from the diaphragm part, and including an island part surrounded by an annular space penetrating in the thickness direction,
The first detection electrode portion is connected to an end portion of the island portion on the first insulating layer side,
The lead-out electrode portion is a pressure sensor connected to an end portion of the island portion on the second insulating layer side.   The pressure sensor according to claim 1, wherein the pressure in the reference pressure space is less than atmospheric pressure.   The pressure sensor according to claim 1, wherein the conductive layer is made of silicon to which conductivity is imparted by introducing impurities.   The pressure sensor according to any one of claims 1 to 3, wherein the first insulating layer and the second insulating layer are made of glass substrates.

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