JP2007078444A - Pressure sensor and manufacturing method for pressure sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize both an absolute pressure sensor and a gauge pressure sensor of an equal structure. <P>SOLUTION: This pressure sensor 10 is equipped with a fixed substrate 20 and a movable substrate 30. A first electrode 40 formed on a front surface 21, a dielectric film 70 formed so as to cover the front surface of the first electrode 40, a first connection electrode 43, a second connection electrode 45 formed on a rear surface 22, and a through electrode 46 passing therethrough thicknesswise, are formed on the fixed substrate 20. A diaphragm 34 formed so as to confront the dielectric film 70, a second electrode 50 formed so as to have a space 60 between itself and the dielectric film 70 at a position confronting the first electrode 40 on a surface of the diaphragm 34, and a joint electrode 52 extended from the second electrode 50, are formed on the movable substrate 30. The fixed substrate 20 and the movable substrate 30 are integrated by jointing by the joint electrode 52. The through electrode 46 has a through hole 47. The through hole 47 communicates with the space 60. A sealing material 85 made of a metal seals the through hole 47 while connecting the first electrode 40 and the connection electrode 45. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a pressure sensor and a method for manufacturing the pressure sensor, and more particularly, to a structure of a touch mode capacitive pressure sensor and a method for manufacturing the pressure sensor.

  2. Description of the Related Art Conventionally, in a touch mode capacitive pressure sensor, a base body (fixed substrate) provided with a silicon structure (movable substrate) having a diaphragm, an electrode facing the diaphragm, and a dielectric film formed so as to cover the electrode. ) In a vacuum is known as a pressure sensor formed by heat welding or using an inorganic adhesive (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2002-214058 (5th page, FIG. 1)

According to such Patent Document 1, a movable substrate of a silicon structure having a diaphragm and a fixed substrate having a dielectric film and an electrode are bonded in a vacuum. Therefore, since the inside of the space provided between the silicon structure and the fixed substrate is also evacuated, this pressure sensor is an absolute pressure sensor. As a pressure sensor, in addition to an absolute pressure sensor, a gauge pressure sensor (relative pressure sensor) that makes the above-described space atmospheric pressure is used. In such a joining method, air or an inert gas is used after joining. Cannot be enclosed in space.
In general, when anodic bonding is performed in a vacuum state, abnormal discharge is likely to occur, and bonding conditions become very difficult.

  In addition, when an adhesive is used as the bonding material, it is predicted that gas is generated by heating. However, since the space described above is hermetically sealed at the time of bonding, this gas can be discharged. In addition, there is a problem that the diaphragm causes expansion distortion due to this gas, and accurate pressure measurement cannot be performed.

  SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned problems, and realizes both an absolute pressure sensor and a gauge pressure sensor with the same structure, and enables accurate pressure measurement, and manufacture of the pressure sensor. Is to provide a method.

  The pressure sensor of the present invention is a pressure sensor that measures a pressure by detecting a change in a contact area where a diaphragm receives pressure and contacts a dielectric film, and includes a first electrode formed on one surface, The dielectric film formed to cover the surface of the first electrode, the first connection electrode, the second connection electrode formed on the other surface, and the through electrode penetrating in the thickness direction are formed. A fixed substrate, the diaphragm formed to face the dielectric film, and a space between the dielectric film and a position on the surface of the diaphragm facing the first electrode are provided. A movable substrate formed with two electrodes and a bonding electrode extending from the second electrode and bonding with the fixed substrate, wherein the fixed substrate and the movable substrate are the bonding electrodes. Are joined and integrated, and the through electrode penetrates. Having a hole, the through hole communicating with the space, and a metal sealing material sealing the through hole and connecting the first electrode and the second connection electrode. Features.

  According to the present invention, since the through-hole communicating with the space provided by joining the movable substrate and the fixed substrate is provided, the absolute pressure sensor can be configured by evacuating the space, or in the space. Enclose air and make it possible to construct a gauge pressure sensor.

  Moreover, an inert gas such as nitrogen is sealed in this space to realize a gauge pressure sensor, and the first electrode and the second electrode inside the space are protected from corrosion, etc., and the performance of the pressure sensor is improved over a long period of time. Can be maintained.

  Further, since the first electrode in the space is connected to the external second connection electrode through the through electrode, the electrode traversing the bonding electrode is eliminated, and the movable substrate and the fixed substrate in a uniform state are removed. And since it joins with this joining electrode and the through-hole which a penetration electrode has is sealed with the metal sealing material, the airtightness in space can be hold | maintained in a favorable state.

In the present invention, the first connection electrode and the second electrode are connected via the junction electrode, the second connection electrode and the first electrode are connected via the through electrode, It is preferable that each of the 1 connection electrode and the second connection electrode is a connection part for connecting to an external circuit.
Here, although described in detail in an embodiment described later, the connection between the first connection electrode and the bonding electrode is connected to the outside of the side surface of the movable substrate, for example, by a connection member such as a conductive adhesive.

  In this case, the connection portion with the external circuit is connected to the outside of the movable substrate and the fixed substrate via the bonding electrode or the through electrode, respectively, so that the airtightness of the space described above is maintained, and the external circuit It is easy to connect with.

  In the present invention, it is preferable that a sealing auxiliary electrode for holding the sealing material is formed at a position facing the through hole on the surface of the movable substrate facing the fixed substrate.

  In this way, by providing the sealing auxiliary electrode at a position facing the through hole, the sealing material stays in the region of the sealing auxiliary electrode, the sealing material flows into the space, and the bonding electrode in the vicinity Short-circuiting or adhesion to the surface of the dielectric film can be prevented. Moreover, the effect that the adhesiveness of a sealing material and a movable substrate improves is also acquired.

  Further, it is desirable that the second connection electrode extends from a side surface of the fixed substrate to the one surface.

  The second connection electrode is formed on the back surface of the fixed substrate. Since the second connection electrode extends from the side surface of the fixed substrate to the surface (movable substrate side), the portion extending on the surface is connected to one external circuit. By using the connection part, it is possible to provide the connection part on the same surface of the fixed substrate together with the first connection electrode as the other connection part. Can be diversified.

  In the pressure sensor of the present invention, the first electrode formed on one surface, the dielectric film formed to cover the surface of the first electrode, and the first connection electrode are formed. A second substrate provided with a space between the fixed substrate, the diaphragm formed to face the dielectric film, and the dielectric on the surface of the diaphragm facing the first electrode. An electrode, a bonding electrode extending from the second electrode for bonding to the fixed substrate, a second connection electrode formed on a surface opposite to the bonding electrode, and a penetrating through in the thickness direction And a movable substrate on which the electrode is formed, the fixed substrate and the movable substrate are joined and integrated by the joining electrode, the through electrode is provided with a through hole, and the through hole is formed A sealing material made of metal that communicates with the space seals the through hole. While, characterized in that it connects the said second connection electrode and the first electrode.

According to this invention, the through electrode is provided on the movable substrate, and the first electrode is connected to the second connection electrode formed on the surface (outside) of the movable substrate via the through electrode. Therefore, in addition to the same effect as the structure in which the through electrode is provided on the fixed substrate side described above, since the through electrode is not provided in the fixed substrate, the fixed substrate has the first electrode and the first electrode on the same surface. Only one connection electrode and dielectric film need be formed, and the manufacturing process can be simplified.
Further, although described in detail in a method for manufacturing a pressure sensor, which will be described later, forming a through electrode on the movable substrate contributes to a reduction in manufacturing cost as a whole without increasing the manufacturing process.

  In the above-described structure, the first connection electrode and the second electrode are connected via the bonding electrode, the second connection electrode and the first electrode are connected via the through electrode, It is preferable that the first connection electrode and the second connection electrode are connection portions for connecting to an external circuit.

  Therefore, since the connection part with the external circuit can be provided in the same direction in the thickness direction of the pressure sensor, there is an effect that the connection work with the external circuit can be facilitated.

  Moreover, it is preferable that the said joining electrode is extended from the side surface of the said movable substrate to the same plane as the said 2nd connection electrode.

  According to this configuration, as described above, since the bonding electrode is connected to the second electrode, the electrode provided on the surface of the movable substrate serves as a connection portion with the external circuit. Therefore, two connection portions exist on the same surface of the movable substrate together with the second connection electrode, and the connection work with the external circuit can be facilitated. In addition, there is an effect that the number of options for the connection structure with the external circuit is increased. In this structure, the first connection electrode described above is not necessary, and the electrode configuration can be further simplified.

Further, it is preferable that the bonding electrode is formed thicker than the first electrode.
Since the lead electrode described above is formed by extending the first electrode, it has the same thickness. The lead electrode is wired in a gap between the fixed substrate and the movable substrate. And it joins between the joining electrode provided in a movable board | substrate, and a fixed board | substrate. If this joining means employs anodic bonding, anodic bonding becomes difficult when the lead electrode contacts the movable substrate. Therefore, by making the bonding electrode thicker than the first electrode (lead electrode), the movable substrate and the fixed substrate can be reliably bonded.

  Moreover, by doing in this way, the space | gap which connects the space mentioned above and the through-hole provided in the penetration electrode is securable.

  In the present invention, the movable substrate is made of quartz, the fixed substrate is made of glass, and the movable substrate and the fixed substrate are joined by anodic bonding.

Quartz is known to be easily formed into an accurate dimension by an etching method because of its crystal structure. Therefore, the diaphragm can be formed accurately. Further, since the fixed substrate is made of glass, it is a combination of materials preferable for anodic bonding with the bonding electrode provided on the movable substrate.
As the glass, for example, soda glass having a thermal expansion coefficient close to that of quartz is preferably used.

  The pressure sensor manufacturing method of the present invention is a pressure sensor manufacturing method for measuring pressure by detecting a change in contact area where the diaphragm receives pressure and contacts the dielectric film, and the manufacturing process of the movable substrate Includes a step of forming a diaphragm and a step of forming a second electrode and a bonding electrode on the surface of the diaphragm, and the manufacturing process of the fixed substrate includes the step of forming the first electrode on one surface and the first Forming a dielectric film on the surface of one electrode; forming a second connection electrode on the other surface; forming a through electrode that connects the first electrode and the second connection electrode; And the step of bonding the fixed substrate and the movable substrate includes a step of bonding the fixed substrate and a bonding electrode provided on the movable substrate by anodic bonding.

According to the present invention, it is possible to provide a pressure sensor that exhibits the effects described above. Further, this is a manufacturing method capable of downsizing the fixed substrate and the movable substrate, and a high-performance and inexpensive pressure sensor can be provided.
Moreover, the manufacturing method of each of the fixed substrate and the movable substrate described above can be manufactured with a facility for manufacturing a conventional crystal unit, and the materials of the bonding electrode and the fixed substrate (glass) are appropriately selected for anodic bonding. By selecting and combining, highly reliable hermetic sealing can be performed.

  The pressure sensor manufacturing method of the present invention is a pressure sensor manufacturing method for measuring pressure by detecting a change in contact area where the diaphragm receives pressure and contacts the dielectric film, and the manufacturing process of the movable substrate A step of forming a diaphragm, a step of forming a second electrode and a bonding electrode on the surface of the diaphragm, a step of forming a second connection electrode on the surface opposite to the bonding electrode, and the second connection electrode Forming a through electrode connected to the fixed substrate, and the manufacturing process of the fixed substrate includes forming a first electrode on one surface and forming a dielectric film on the surface of the first electrode; Forming a first connection electrode on the surface, and the bonding step of the fixed substrate and the movable substrate includes a step of bonding the fixed substrate and a bonding electrode provided on the movable substrate by anodic bonding. Features including To.

  According to the manufacturing method of the present invention, a pressure sensor having the above-described effects can be provided. Further, this is a manufacturing method capable of downsizing the fixed substrate and the movable substrate, and a high-performance and inexpensive pressure sensor can be provided.

In addition, since no through electrode is provided on the fixed substrate, it is only necessary to form the first electrode, the first connection electrode, and the dielectric film on the same surface of the fixed substrate, thereby simplifying the manufacturing process. it can.
Furthermore, even in the structure in which the through electrode is formed on the movable substrate, the manufacturing process does not increase, and the manufacturing cost is reduced as a whole.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 to 5 show a pressure sensor according to the first embodiment of the present invention, FIG. 6 shows a modification of the first embodiment, FIGS. 7 to 11 show a second embodiment, and FIG. 12 shows a modification of the second embodiment. is there.
(Embodiment 1)

1 to 5 show a pressure sensor according to Embodiment 1 and a method for manufacturing the pressure sensor.
1A and 1B show a schematic structure of a pressure sensor according to a first embodiment, where FIG. 1A is a plan view and FIG. 1B is a cross-sectional view schematically showing a cross-sectional structure. 1A and 1B, a pressure sensor 10 according to the present embodiment has a two-layer structure including a fixed substrate 20 made of glass and a movable substrate 30 laminated and bonded to the fixed substrate 20. It is a structure.

The fixed substrate 20 is made of glass, and a first electrode 40 having a rectangular planar shape is formed on one surface 21 on the side to which the movable substrate 30 is bonded. A lead electrode 41 is formed from one side of the first electrode 40. Has been extended. In addition, a through-hole 23 that penetrates from the front surface 21 to the back surface 22 of the fixed substrate 20 is opened at a position away from the first electrode 40 and within the range of the lead electrode 41. The through hole 23 is opened from the back surface direction by a processing means such as sandblasting, and has a taper with a small diameter on the opening side of the surface 21.
As the glass, soda glass having a thermal expansion coefficient close to that of quartz is adopted.

  A through electrode 46 is formed on the inner surface of the through hole 23. Since the through electrode 46 is formed only on the inner surface of the through hole 23, a through hole 47 that penetrates the thickness direction of the fixed substrate 20 is formed at the center. The lead electrode 41 is provided with a hole communicating with the through hole 47, and the through hole 47 communicates with a space 60 described later.

  An island-shaped first connection electrode 43 is formed at the end of the front surface 21 of the fixed substrate 20, while a second connection electrode 45 is formed on the other surface of the fixed substrate 20, that is, the back surface 22. . The second connection electrode 45 is formed to cover the periphery of the through electrode 46 and is connected to the through electrode 46. The first connection electrode 43 and the second connection electrode 45 are connection terminals for connection to an external circuit of a measuring instrument (not shown).

A dielectric film 70 is formed on the surface of the first electrode 40 so as to cover the first electrode 40. The dielectric film 70 is formed of a known insulator such as quartz glass, ceramic, silicon oxide (SiO ₂ ) or the like by means such as sputtering or CVD. The surface of the dielectric film 70 is finished smoothly.
The movable substrate 30 is laminated and bonded to the upper surface of the fixed substrate 20 configured as described above.

  The movable substrate 30 is made of quartz, and has a thin diaphragm 34 having a larger area than the first electrode 40 at a position facing the above-described first electrode 40 in a substantially central portion, and a semicircular notch in the outer peripheral portion. 35 is formed. Diaphragm 34 is formed by forming recesses 31 and 32 from both directions of front surface 30A and rear surface 30B of movable substrate 30, respectively. A second electrode 50 is formed on the bottom surface 33 of the recess 32 on the back surface side.

  The second electrode 50 is formed in substantially the same shape at a position facing the first electrode 40, passes through the slope of the bottom surface 33 of the recess 32, and extends by the lead electrode 51 to the bonding electrode 52 at the peripheral edge of the movable substrate 30. Has been. The second electrode 50 is a movable electrode that follows and bends when the diaphragm 34 is bent by receiving pressure from the outside. A part of the bonding electrode 52 formed on the outer peripheral portion extends to the side surface of the notch 35 to form the side electrode 53.

In addition, an island-shaped auxiliary sealing electrode 54 is formed on the back surface 30 </ b> B of the movable substrate 30. The auxiliary sealing electrode 54 is provided to prevent the flow of a sealing material 85 described later. Moreover, the effect that the adhesiveness of a sealing material and a movable substrate improves is also acquired.
Each of the electrodes described above is formed by sputtering or vapor deposition of Al or Au.

  The fixed substrate 20 and the movable substrate 30 are tightly bonded by anodic bonding using the bonding electrode 52 as a bonding material. Thus, a space 60 is formed between and around the dielectric film 70 and the second electrode 50, and the aforementioned through hole 47 communicates with the space 60. Since the bonding electrode 52 is formed thicker than the first electrode 40 and the lead electrode 41, there is a gap between the first electrode 40 and the lead electrode 41 and the back surface 30 </ b> B of the movable substrate 30.

Further, the sealing auxiliary electrode 54 provided on the movable substrate 30 is formed so as to be thinner than the bonding electrode 52 even if the thickness of the first electrode 40 is added. Accordingly, the movable substrate 30 and the fixed substrate 20 are bonded to each other only between the bonding electrode 52 and the glass surface.
The first connection electrode 43 provided on the fixed substrate 20 is exposed in the notch 35 of the movable substrate 30.

  After the fixed substrate 20 and the movable substrate 30 are joined, a sealing material 85 made of Au / Ge is welded into the through hole 47. At this time, the sealing material 85 connects the through electrode 46 and the lead electrode 41 (first electrode 40) and hermetically seals the through hole 47. In addition, the sealing material 85 stays in the range of the auxiliary sealing electrode 54 and flows to other parts, and prevents, for example, shorting with the bonding electrode 52 or adhesion to the surface of the dielectric film 70. Yes.

  In addition, if the sealing process with the sealing material 85 after joining is performed in a vacuum environment, the space 60 is evacuated to configure an absolute pressure sensor, and if performed in an atmospheric pressure environment, a gauge pressure sensor (relative pressure sensor) is configured. To do. In addition, an inert gas such as nitrogen can be sealed in the space 60 from the through hole 47 and hermetically sealed with the sealing material 85.

  The pressure sensor 10 integrated in this way connects the leads 90 and 91 to the first connection electrode 43 and the second connection electrode 45 using the conductive adhesive 80, and is connected to an external circuit of a measuring instrument (not shown).

The pressure sensor 10 configured according to the above-described embodiment is referred to as a touch mode capacitive pressure sensor among the capacitive pressure sensors. When this type of pressure sensor receives pressure, the diaphragm 34 bends in the direction of compressing the space 60, and the second electrode 50 contacts the dielectric film 70. When further pressure is applied, this contact area increases. At this time, the capacitance between the second electrode 50 and the first electrode 40 increases corresponding to the change in the contact area.
Then, the pressure can be detected by connecting to a measuring instrument (including an external circuit) (not shown), applying an AC voltage, and detecting a change in the resonance frequency or impedance.

  Therefore, the pressure sensor according to the first embodiment described above has the through-hole 47 that communicates with the space 60 provided by joining the movable substrate 30 and the fixed substrate 20, so that it is not necessary to perform the joining process in a vacuum. If the sealing process is performed in a vacuum environment with the same structure, the space 60 is evacuated to form an absolute pressure sensor, or if performed in an atmospheric pressure environment, a gauge pressure sensor (relative pressure sensor). Can be configured.

  In addition, an inert gas such as nitrogen is sealed in the space 60 to realize a gauge pressure sensor, and the first electrode 40 and the second electrode 50 in the space 60 are protected from corrosion and the like, and the pressure is maintained for a long time. The performance of the sensor 10 can be maintained.

  In addition, since the gas generated at the time of joining and staying in the above-described space 60 can be discharged from the through-hole 47, the expansion distortion of the diaphragm 34 can be suppressed.

  Further, since the first electrode 40 in the space 60 is connected to the external second connection electrode 45 through the through electrode 46, the electrode traversing the bonding electrode 52 is removed and bonded at the bonding electrode 52 portion. And since the through-hole 47 which the through-electrode 46 has is sealed with the metal sealing material 85, the airtightness in the space 60 can be hold | maintained in a favorable state.

  Further, the first connection electrode 43 and the second electrode 50 are connected by the conductive adhesive 80 through the bonding electrode 52, and the first electrode 40 and the second connection electrode 45 are connected through the through electrode 46. Therefore, the airtightness of the space 60 is maintained and the connection work with the external circuit is facilitated.

  Furthermore, by providing the sealing auxiliary electrode 54 at a position facing the through hole 47 on the back surface 30B of the movable substrate 30, the sealing material 85 remains in the region of the sealing auxiliary electrode 54, and the sealing material 85 flows. It is possible to prevent a short circuit with the bonding electrode 52 in the vicinity, and a flow into the space 60 to adhere to the surface of the dielectric film 70.

In addition, the movable substrate 30 is made of quartz, the fixed substrate 20 is made of glass, and these are joined by anodic bonding. Since quartz is easy to be formed into an accurate dimension by an etching method from its crystal structure, the diaphragm 34 can be formed with an accurate thickness. The material of the movable substrate 30 (bonding electrode 52) and the fixed substrate 20 is a combination of materials most preferable for anodic bonding. In addition, the fixed board | substrate 20 can reduce the distortion by the heat | fever in the case of joining by using soda glass with a thermal expansion coefficient close | similar to quartz.
(Method for Manufacturing Pressure Sensor According to Embodiment 1)

Next, an example of the pressure sensor manufacturing method according to the first embodiment will be described with reference to the drawings.
2 and 3 are a plan view and a cross-sectional view schematically showing main manufacturing steps of the movable substrate 30 according to the first embodiment, and FIGS. 4 and 5 are main views of the main manufacturing steps of the fixed substrate 20, respectively.
2A and 2B show a method for manufacturing the diaphragm and the outer shape of the movable substrate 30, wherein FIG. 2A is a plan view and FIG. 2B is a cross-sectional view taken along line BB in FIG. 2A and 2B, an outer shape including the diaphragm 34 is formed.

  First, the recesses 31 and 32 are formed by etching (dry etching or wet etching) from both the front and back surfaces of the front surface 30A and the back surface 30B of the movable substrate 30. At this time, the diaphragm 34 is formed as a remaining thickness portion of these concave portions. Since the movable substrate 30 is made of quartz, the etching characteristics are good, and the thickness of the diaphragm 34 can be managed with high accuracy.

The movable substrate 30 forms a large number of diaphragms 34 and forms an outer shape in the state of a quartz wafer (hereinafter sometimes simply referred to as a wafer). Here, the notch 35 is formed in the wafer state. The notch 35 is formed in a circular shape in the state of the wafer, and becomes a semicircular notch shape when the outer shape is formed into a single body. Each electrode described below is formed in batches in a wafer state, and then the outer shape is separated into a single movable substrate 30 having a rectangular shape by an etching method or the like. At this time, it is desirable to process by etching from both front and back sides.
Next, the second electrode 50 is formed.

  3A and 3B show a process of forming the second electrode 50, where FIG. 3A is a plan view showing a state viewed from the back surface 30B, and FIG. 3B is a cross-sectional view. 3A and 3B, the second electrode 50 made of Al, Au, or the like is formed on the back surface 30B of the movable substrate 30 by sputtering or vapor deposition. When the second electrode 50 is formed of Au, a Cr / Au layer may be formed in order to improve adhesion with the crystal.

The second electrode 50 continues from the bottom surface 33 through the slope of the recess 32 to the bonding electrode 52 over the entire circumference of the outer peripheral portion via the lead electrode 51. Further, the bonding electrode 52 extends to the inner side surface of the notch 35 to form a side electrode 53. The side electrode 53 can be formed at the same time as the bonding electrode 52 by oblique vapor deposition or the like obliquely from below in the drawing.
Further, the sealing auxiliary electrode 54 is formed at a position away from the recess 32 and away from other electrodes. The auxiliary sealing electrode 54 is made thinner than the other electrodes, and is performed in a process separate from the process of forming the second electrode 50.

After forming each electrode described above, the outer shape is processed by etching or the like to complete the movable substrate 30 alone.
In addition, after forming the external shape of the movable substrate 30, it can also be made into the process order which forms an electrode.

Next, a method for forming the fixed substrate 20 will be described with reference to the drawings.
4 and 5 show an example of the manufacturing process of the fixed substrate 20.
First, the through electrode 46, the first electrode 40, and the first connection electrode 43 are formed. 4A is a plan view, and FIG. 4B is a cross-sectional view. 4A and 4B, first, a through hole 23 penetrating from the rear surface 22 to the front surface 21 of the fixed substrate 20 made of glass is opened by means such as sandblasting. A through electrode 46 is formed on the inner surface of the through hole 23 by vapor deposition or the like. Since the through electrode 46 is formed along the inner surface of the through hole 23, a through hole 47 is formed at the center.

  In addition, since the through-hole 23 has a taper, the through-electrode 46 is easily attached to the entire inner surface leading to the front surface 21 by vapor deposition from the direction of the back surface 22.

  Subsequently, a first electrode 40 and a first connection electrode 43 made of Al or Au are formed on the surface 21 by sputtering or vapor deposition. The first electrode 40 extends from one side of the lead electrode 41, and the lead electrode 41 extends to a range including the above-described through hole 47. The lead electrode 41 has an opening having a diameter substantially the same as the inner diameter of the through hole 47. The through hole 47 also penetrates the lead electrode 41 and communicates both the front and back surfaces of the fixed substrate 20. The lead electrode 41 and the through electrode 46 are electrically connected at the periphery of the opening.

The first electrode 40, the lead electrode 41, and the first connection electrode 43 are formed in a range that does not overlap with the bonding electrode 52 (see FIG. 3) formed on the movable substrate 30 described above. Moreover, the 1st electrode 40 is formed in the substantially same shape (rectangular shape) in the position facing the 2nd electrode 50 mentioned above.
Next, the dielectric film 70 is formed on the surface of the first electrode 40.

FIG. 4C is a plan view showing a state in which the dielectric film 70 is formed (see also FIG. 5B). The dielectric film 70 is formed so as to cover the upper surface of the rectangular first electrode 40 by using a film forming means such as a sputtering method or a CVD method. The surface of the dielectric film 70 is preferably formed on the same smooth plane. The dielectric film 70 is made of a known material such as quartz glass, ceramic, silicon oxide (SiO ₂ ), or the like.
Subsequently, the second connection electrode 45 is formed on the back surface 22 of the fixed substrate 20.

  FIG. 5 shows a process of forming the second connection electrode 45. (A) is the top view visually recognized from the back surface 22 side, (b) is sectional drawing. In FIGS. 5A and 5B, the second connection electrode 45 is made of Al or Au, is formed by vapor deposition or sputtering, and has an opening having the same diameter as the opening on the back surface side of the through electrode 46. is doing. Here, the through electrode 46 and the second connection electrode 45 are connected at the periphery of the opening, and therefore the first electrode 40 and the second connection electrode 45 are electrically connected.

The fixed substrate 20 is a single rectangular fixed substrate that is scribed after the first electrode 40, the dielectric film 70, the through electrode 46, and the second connection electrode 45 are formed on a large glass substrate. Formed as.
The fixed substrate 20 and the movable substrate 30 formed as described above are joined by anodic bonding.

The state of anodic bonding is shown in FIG. Bonding of the fixed substrate 20 and the movable substrate 30 is performed by anodic bonding between the bonding electrode 52 formed on the back surface 30B of the movable substrate 30 and the fixed substrate 20 (glass). By joining, a space 60 is formed between the dielectric film 70 and the second electrode 50, and the space 60 communicates with the outside through a through hole 47.
In addition, after joining the fixed board | substrate 20 and the movable board | substrate 30, the method of cut | disconnecting to a predetermined external shape can be employ | adopted.
Thus, after bonding the fixed substrate 20 and the movable substrate 30, the through hole 47 is sealed with the sealing material 85.

  FIG. 1B shows a state where the through hole 47 is sealed. A sealing material 85 made of Au / Ge is embedded in the through hole 47 and welded. The sealing material 85 has a spherical shape before welding, and is melted and embedded in the through hole 47 by heating. At this time, the sealing material 85 connects the through electrode 46 and the lead electrode 41 (including the first electrode 40), and hermetically seals the through hole 47, that is, the space 60. The sealing material 85 stays in the range of the sealing auxiliary electrode 54 and flows to other parts, and prevents, for example, short-circuiting with the bonding electrode 52 or adhesion to the surface of the dielectric film 70. Thus, the first electrode 40 is connected to the second connection electrode 45 via the sealing material 85 and the through electrode 46.

  Therefore, even if the through electrode 46 described above is formed in the middle of not reaching the surface 21 of the fixed substrate 20, it may be formed as long as it can be connected to the sealing material 85.

If the sealing process with the sealing material 85 described above is performed in a vacuum environment, the space 60 is in a vacuum state, and an absolute pressure sensor is configured. If performed in atmospheric pressure, a gauge pressure sensor (also referred to as a relative pressure sensor). Is configured. In addition, an inert gas such as nitrogen can be sealed in the space 60.
The pressure sensor 10 configured as described above connects the first connection electrode 43 and the side electrode 53 with the conductive adhesive 80 and also connects the lead 90 and is connected to one terminal of an external circuit (not shown). The Also in the second connection electrode 45, the lead 91 is connected by the conductive adhesive 80 and is connected to the other terminal of the external circuit.

Therefore, according to the manufacturing method of the pressure sensor 10 which concerns on Embodiment 1 mentioned above, the pressure sensor 10 which has the effect mentioned above can be provided. In addition, the pressure sensor 10 is a manufacturing method capable of reducing the size of the fixed substrate 20 and the movable substrate 30, and can provide a high-performance and inexpensive pressure sensor 10.
In addition, the manufacturing method of each of the fixed substrate 20 and the movable substrate 30 described above can be manufactured by equipment for manufacturing a crystal resonator, and materials for the bonding electrode 52 and the fixed substrate 20 are appropriately selected for anodic bonding. In combination, highly reliable hermetic sealing can be performed.
(Modification of Embodiment 1)

Subsequently, a modification of the pressure sensor 10 according to the first embodiment will be described with reference to the drawings. This modification is characterized in that, based on the technical idea of the first embodiment described above, the configuration of the second connection electrode is changed and a connection portion with an external circuit is provided on the surface of the fixed substrate. Since this is the same as that of the first embodiment (see FIG. 1), description of the same part will be omitted, and the same part will be described with the same reference numeral.
FIG. 6 is a cross-sectional view schematically showing a pressure sensor 10 according to this modification. A plan view is omitted. In FIG. 6, the second connection electrode 45 formed on the back surface 22 of the fixed substrate 20 is provided with a connection portion 48 extending through the side surface of the fixed substrate 20 to a part of the front surface 21.

  Here, the movable substrate 30 is provided with a notch (not shown) having the same shape at a position apart from the above-described notch 35 (see FIG. 1A), and the connecting portion 48 is provided with the notch. And a range that does not contact the bonding electrode 52. The lead 91 is connected to the surface of the connection portion 48 by the conductive adhesive 80. Therefore, the connection between the external circuit and the pressure sensor 10 can be performed at substantially the same height on the surface of the fixed substrate 20 together with the leads 90.

  Further, since the connection portion 48 and the first connection electrode 43 with the external circuit are formed on the surface 21 of the fixed substrate 20, the connection with the external circuit is performed by wire bonding using a wire as a lead. You can also.

  Therefore, according to the above-described modification, the second connection electrode 45 has the portion extending to the surface 21 of the fixed substrate 20 as the connection portion 48 with one external circuit, so that the second connection electrode 45 serves as the other connection portion. Since the connection portion can be provided on the same surface 21 of the fixed substrate 20 together with the first connection electrode 43, the connection portion with the external circuit is facilitated, and the connection method can be diversified.

The connection portion 48 can be formed in the same process as the first connection electrode 43, and the formation of the electrode on the side surface connecting the connection portion 48 and the second connection electrode 45 can also be performed by forming the connection portion 48 or The second connection electrode 45 can be formed without increasing the number of steps by means of an oblique vapor deposition method or the like.
(Embodiment 2)

Subsequently, a pressure sensor according to Embodiment 2 of the present invention will be described with reference to the drawings. The second embodiment is characterized in that the through electrode is provided on the movable substrate as compared with the first embodiment described above. Description of the same or similar parts as those in the first embodiment may be omitted.
FIG. 7 schematically illustrates the structure of the pressure sensor 10 according to the second embodiment, where (a) is a plan view and (b) is a cross-sectional view. 7A and 7B, the fixed substrate 20 is made of a single glass plate, and the first electrode 40, the lead electrode 41, and the first connection electrode 43 are formed on the surface 21. A dielectric film 70 is formed so as to cover it. The first electrode 40, the lead electrode 41, the first connection electrode 43, and the dielectric film 70 are formed in substantially the same form as in the first embodiment (see FIG. 1), but the lead electrode 41 has an opening. There is no section.

A diaphragm 34 is formed on the movable substrate 30, and a second electrode 50, a lead electrode 51, and a bonding electrode 52 are extended from the front surface of the diaphragm 34 on the back surface 30 </ b> B side. In the bonding electrode 52, a side surface electrode 53 continuous in the notch 35 extends to the surface 30 </ b> A, and a surface connection electrode 55 is formed. A second connection electrode 56 is formed on the surface 30 </ b> A of the movable substrate 30 at a position separated from the surface connection electrode 55 described above.
The second connection electrode 56 is connected to a through electrode 57 that penetrates the front and back of the movable substrate 30.

  The through electrode 57 is formed along the inner surface of the through hole 36 penetrating the front and back of the movable substrate 30, and a through hole 58 is formed at the center thereof. The through electrode 57 and the second connection electrode 56 are electrically connected.

  The fixed substrate 20 and the movable substrate 30 formed as described above are joined by anodic bonding. After bonding, the through hole 58 communicates the space 60 with the outside, and the through hole 58 is welded and sealed with a sealing material 85 made of Au / Ge. At this time, the sealing material 85 reaches the lead electrode 41 extending from the first electrode 40, hermetically seals the through hole 58, and connects the through electrode 57 and the lead electrode 41. Therefore, the first electrode 40 and the second connection electrode 56 are connected by the sealing material 85.

  Therefore, according to the second embodiment described above, the through electrode 57 is provided on the movable substrate 30, and the first electrode 40 is connected to the second connection electrode 56 formed on the surface 30 </ b> A of the movable substrate 30 via the through electrode 57. Therefore, the same effect as the structure in which the through electrode 46 (see FIG. 1B) is provided on the fixed substrate 20 can be obtained.

In the structure of the second embodiment, the first connection electrode 43 and the second electrode 50 are connected via the bonding electrode 52, and the second connection electrode 56 and the first electrode 40 are connected via the through electrode 57. Since the first connection electrode 43, the second connection electrode 56, and the second connection electrode 56 are connected to connect to an external circuit, the connection to the external circuit is in the same direction in the thickness direction of the pressure sensor 10. Therefore, it is possible to facilitate connection work with an external circuit.
(Manufacturing method of pressure sensor according to Embodiment 2)

Then, an example of the manufacturing method of the pressure sensor 10 which concerns on Embodiment 2 is demonstrated with reference to drawings.
8 to 10 show a method for manufacturing the movable substrate 30 according to the second embodiment. First, the outer shape including the diaphragm of the movable substrate 30 is formed.
8A and 8B show the outer shape of the movable substrate 30, where FIG. 8A is a plan view and FIG. 8B is a cross-sectional view. 8A and 8B, first, recesses 31 and 32 are formed by etching (dry etching or wet etching) from both the front and back surfaces of the movable substrate 30. At this time, the diaphragm 34 is formed as a remaining thickness portion of these concave portions. Since the movable substrate 30 is made of quartz, the etching characteristics are good, and the thickness of the diaphragm 34 can be managed with high accuracy.

The movable substrate 30 forms a large number of diaphragms 34 and forms an outer shape from a quartz wafer (hereinafter sometimes simply referred to as a wafer). Here, the notch 35 and the through hole 36 are formed in the wafer state. The notch 35 is formed in a circular shape in the state of the wafer, and is formed into a semicircular notch shape when forming the outer shape as a single unit. At this time, the processing time can be shortened by processing from both the front and back surfaces.
Next, the surface connection electrode 55, the second connection electrode 56, and the through electrode 57 are formed on the surface 30 </ b> A of the movable substrate 30.

  FIG. 9 shows a process of forming the surface connection electrode 55, the second connection electrode 56, and the through electrode 57, where (a) is a plan view and (b) is a cross-sectional view. First, the through electrode 57 is formed on the inner surface of the through hole 36. A through hole 58 is formed at the center of the through electrode 57. Then, the second connection electrode 56 and the surface connection electrode 55 are formed on the surface 30A by sputtering or vapor deposition. An opening having the same diameter as the opening of the through hole 58 is formed in the second connection electrode 56. Here, the through electrode 57 and the second connection electrode 56 are connected, and when the surface connection electrode 55 is formed, the side electrode 53 is formed on the side surface in the notch 35.

Next, the second electrode 50 and the bonding electrode 52 are formed on the back surface 30B side of the movable substrate 30 by a sputtering method or a vapor deposition method.
FIG. 10 shows a process of forming the second electrode 50 and the bonding electrode 52. (A) is the top view visually recognized from the back surface 30B side, (b) is sectional drawing (in the figure, the upper side is the back surface 30B). 10A and 10B, the second electrode 50 is formed on the surface of the diaphragm 34 on the back surface 30 </ b> B of the movable substrate 30. A lead electrode 51 and a bonding electrode 52 extend from the second electrode 50, and a side electrode 59 is formed along the side surface in the notch 35. The side electrode 59 overlaps and is connected to a side electrode 53 extending from the surface 30A.

Then, the manufacturing method of the fixed board | substrate 20 is demonstrated with reference to drawings.
FIG. 11 shows a manufacturing process of the fixed substrate 20, (a) is a plan view viewed from the surface 21 side, and (b) is a cross-sectional view. 11A and 11B, the first electrode 40 and the first connection electrode 43 are formed on the surface 21 of the fixed substrate 20 by sputtering or vapor deposition. The first electrode 40 is formed to face the second electrode 50 of the movable substrate 30, and the lead electrode 41 extends. The lead electrode 41 extends to the periphery of the through electrode 57 formed on the movable substrate 30 (see FIG. 10).

  Then, a dielectric film 70 is formed so as to cover the surface of the first electrode 40. The material and forming method of the dielectric film 70 are formed according to the first embodiment described above.

The fixed substrate 20 and the movable substrate 30 thus formed are joined by anodic bonding. This joined state is shown in FIG. After the anodic bonding, a sealing material 85 made of Au / Ge is embedded in the through hole 58 and welded. The sealing material 85 connects the first electrode 40 (lead electrode 41) and the through electrode 57, and hermetically seals the space 60. Accordingly, the first electrode 40 is connected to the second connection electrode 56 through the through electrode 57.
Note that the sealing material 85 remains within the range of the lead electrode 41 in the space 60.

  Accordingly, the through electrode 57 described above may be formed within a range where it can be connected by the sealing material 85 even if it is formed before the back surface 30B of the movable substrate 30 is reached.

If the sealing step using the sealing material 85 described above is performed in a vacuum environment, the space 60 is in a vacuum state, and an absolute pressure sensor is configured. If performed in atmospheric pressure, a relative pressure sensor is configured.
The pressure sensor 10 configured as described above connects the first connection electrode 43 and the side electrode 53 with the conductive adhesive 80 and also connects the lead 90 and is connected to one terminal of an external circuit (not shown). The Also in the second connection electrode 56, the lead 91 is connected by the conductive adhesive 80 and is connected to the other terminal of the external circuit.

Therefore, according to the manufacturing method of the pressure sensor 10 according to the second embodiment described above, since the through electrode is not provided in the fixed substrate 20, the first electrode 40, the first connection electrode 43, It is only necessary to form the dielectric film 70, and the manufacturing process can be simplified.
Moreover, even if it is the structure which forms the penetration electrode 57 in the movable substrate 30, a manufacturing process does not increase and it contributes to the reduction of manufacturing cost as a whole.
(Modification of Embodiment 2)

Next, a modification of the pressure sensor 10 according to the second embodiment will be described with reference to the drawings. This modification is characterized in that, based on the technical idea of the second embodiment described above, the configuration of the first connection electrode is changed and a connection portion with an external circuit is provided on the upper surface of the movable substrate. Since the configuration is the same as that of the second embodiment (see FIG. 7), the description of the same part is omitted, and the same part is denoted by the same reference numeral.
FIG. 12 is a cross-sectional view schematically showing a pressure sensor 10 according to this modification. A plan view is omitted. In FIG. 12, the bonding electrode 52 provided on the movable substrate 30 is connected to the surface connection electrode 55 through the side surface of the movable substrate 30. The surface connection electrode 55 is used as a connection portion with an external circuit, and the lead 90 is connected by the conductive adhesive 80.

  In addition, although the formation method of the side electrode 53 can be formed by the same method as Embodiment 2 (refer FIG. 9, 10) mentioned above, the notch 35 does not necessarily need to be. Further, the first connection electrode 43 provided on the fixed substrate 20 is also unnecessary.

  Therefore, the pressure sensor 10 can be connected to an external circuit (not shown) by the lead 90 together with the lead 91 connected to the second connection electrode 56 as the other connection portion. Since the surface connection electrode 55 and the second connection electrode 56 are on the same surface of the surface 30A of the movable substrate 30, it is possible to connect to an external circuit by wire bonding using a wire as a lead. Yes.

  In addition, there is an effect that the number of options for the connection structure with the external circuit is increased. In this structure, the first connection electrode 43 described above is not necessary, and the electrode configuration can be further simplified. Further, the notch 35 (see FIGS. 7A and 7B) provided in the movable substrate 30 is not necessarily required, and the shape of the movable substrate 30 can be simplified.

It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
That is, although the present invention has been illustrated and described with particular reference to particular embodiments, it is not intended to depart from the technical spirit and scope of the invention. Various modifications can be made by those skilled in the art in terms of materials, combinations, other detailed configurations, and processing methods between manufacturing processes.

  Therefore, the description limited to the shape, material, manufacturing process and the like disclosed above is an example for easy understanding of the present invention, and does not limit the present invention. Descriptions of the names of members from which some or all of the limitations such as materials and combinations are removed are included in the present invention.

  Therefore, according to the first to second embodiments and the modification described above, the absolute pressure sensor and the gauge pressure sensor can be realized with the same structure, and accurate pressure measurement and performance can be maintained over a long period of time. And a manufacturing method capable of realizing the pressure sensor at low cost with a small number of steps.

The schematic structure of the pressure sensor which concerns on Embodiment 1 of this invention is shown, (a) is a top view, (b) is sectional drawing which shows a cross-sectional structure typically. The movable substrate diaphragm which concerns on Embodiment 1 of this invention and the manufacturing method of an external shape are shown, (a) is a top view, (b) is BB sectional drawing of (a). The formation process of the 2nd electrode which concerns on Embodiment 1 of this invention is represented, (a) is a top view showing the state visually recognized from the back surface, (b) is sectional drawing. FIGS. 4A and 4B show a manufacturing process of a fixed substrate according to Embodiment 1 of the present invention, FIG. 4A is a plan view, FIG. 4B is a cross-sectional view, and FIG. 4C is a plan view showing a state where a dielectric film is formed. The formation process of the 2nd connection electrode which concerns on Embodiment 1 of this invention is shown, (a) is the top view visually recognized from the back surface side, (b) is sectional drawing. Sectional drawing which shows typically the structure of the pressure sensor by the modification of Embodiment 1 of this invention. The structure of the pressure sensor which concerns on Embodiment 2 of this invention is shown, (a) is a top view, (b) is sectional drawing. The formation process of the external shape of the movable substrate which concerns on Embodiment 2 of this invention is shown, (a) is a top view, (b) is sectional drawing. The electrode formation process of the movable substrate which concerns on Embodiment 2 of this invention is shown, (a) is a top view, (b) is sectional drawing. The electrode formation process which concerns on Embodiment 2 of this invention is shown, (a) is the top view visually recognized from the back surface side, (b) is sectional drawing. The manufacturing process of the fixed board | substrate which concerns on Embodiment 2 of this invention is shown, (a) is the top view visually recognized from the surface side, (b) is sectional drawing. Sectional drawing which shows typically the pressure sensor by the modification of Embodiment 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Pressure sensor, 20 ... Fixed substrate, 21 ... Front surface of fixed substrate, 22 ... Back surface of fixed substrate, 30 ... Movable substrate, 34 ... Diaphragm, 40 ... First electrode, 43 ... First connection electrode, 45 ... Second Connection electrode, 46 ... through electrode, 47 ... through hole of the through electrode, 50 ... second electrode, 52 ... joining electrode, 60 ... space, 70 ... dielectric film.

Claims (11)

A pressure sensor for detecting pressure by detecting a change in a contact area where the diaphragm receives pressure and contacts the dielectric film;
A first electrode formed on one surface; the dielectric film formed to cover the surface of the first electrode; a first connection electrode; a second connection electrode formed on the other surface; A fixed substrate on which a through electrode penetrating in the thickness direction is formed;
The diaphragm formed to face the dielectric film; and a second electrode provided with a space between the dielectric film at a position facing the first electrode on the surface of the diaphragm; A movable substrate extending from the second electrode and formed with a bonding electrode for bonding to the fixed substrate;
The fixed substrate and the movable substrate are bonded and integrated by the bonding electrode,
The through electrode has a through hole, and the through hole communicates with the space.
A pressure sensor characterized in that a sealing material made of metal seals the through hole and connects the first electrode and the second connection electrode. The pressure sensor according to claim 1.
The first connection electrode and the second electrode are connected via the junction electrode, the second connection electrode and the first electrode are connected via the through electrode,
Each of said 1st connection electrode and said 2nd connection electrode is a connection part which connects with an external circuit, The pressure sensor characterized by the above-mentioned. The pressure sensor according to claim 1 or 2,
A pressure sensor, wherein a sealing auxiliary electrode for holding the sealing material is formed at a position facing the through hole on a surface of the movable substrate facing the fixed substrate. The pressure sensor according to claim 1 or 2,
The pressure sensor, wherein the second connection electrode extends from a side surface of the fixed substrate to the one surface. A fixed substrate on which a first electrode formed on one surface, the dielectric film formed to cover the surface of the first electrode, and a first connection electrode;
The diaphragm formed to face the dielectric film; a second electrode provided with a space between the dielectric and a position on the surface of the diaphragm facing the first electrode; A joining electrode extending from the second electrode for joining to the fixed substrate; a second connecting electrode formed on a surface opposite to the joining electrode; and a penetrating electrode penetrating in the thickness direction. A movable substrate to be formed, and
The fixed substrate and the movable substrate are bonded and integrated by the bonding electrode,
The through electrode is provided with a through hole, and the through hole communicates with the space.
A pressure sensor characterized in that a sealing material made of metal seals the through hole and connects the first electrode and the second connection electrode. The pressure sensor according to claim 5,
The first connection electrode and the second electrode are connected via the junction electrode, the second connection electrode and the first electrode are connected via the through electrode,
The pressure sensor, wherein the first connection electrode and the second connection electrode are connection terminals for connecting to an external circuit. The pressure sensor according to claim 6.
The pressure sensor, wherein the bonding electrode extends from a side surface of the movable substrate to the same plane as the second connection electrode. The pressure sensor according to any one of claims 1 to 7,
The pressure sensor, wherein the bonding electrode is formed thicker than the first electrode. The pressure sensor according to any one of claims 1 to 8,
The movable substrate is formed of quartz, the fixed substrate is formed of glass,
The pressure sensor, wherein the movable substrate and the fixed substrate are bonded by anodic bonding. A method of manufacturing a pressure sensor for measuring a pressure by detecting a change in a contact area where a diaphragm receives pressure and contacts a dielectric film,
The manufacturing process of the movable substrate includes a step of forming a diaphragm and a step of forming a second electrode and a bonding electrode on the surface of the diaphragm,
The manufacturing process of the fixed substrate includes a step of forming a first electrode on one surface, a step of forming a dielectric film on the surface of the first electrode, and a step of forming a second connection electrode on the other surface. Forming a through electrode that connects the first electrode and the second connection electrode,
The method of manufacturing a pressure sensor, wherein the bonding step of the fixed substrate and the movable substrate includes a step of bonding the fixed substrate and a bonding electrode provided on the movable substrate by anodic bonding. A method of manufacturing a pressure sensor for measuring a pressure by detecting a change in a contact area where a diaphragm receives pressure and contacts a dielectric film,
The manufacturing process of the movable substrate includes a step of forming a diaphragm, a step of forming a second electrode and a bonding electrode on the surface of the diaphragm, a step of configuring a second connection electrode on the surface opposite to the bonding electrode, Forming a through electrode connected to the second connection electrode,
The manufacturing process of the fixed substrate includes a step of forming a first electrode on one surface, a step of forming a dielectric film on the surface of the first electrode, and a step of forming a first connection electrode,
The method of manufacturing a pressure sensor, wherein the step of bonding the fixed substrate and the movable substrate includes a step of bonding the fixed substrate and a bonding electrode provided on the movable substrate by anodic bonding.

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