JP4820590B2 - Capacitive pressure sensor element - Google Patents

Description

  The present invention relates to a capacitance-type pressure sensor element that detects a change in pressure by measuring a change in capacitance between a pair of electrodes.

In a conventional capacitance type pressure sensor, wiring is formed by connecting wires to a pair of electrodes that are opposed to each other with a fine space in an airtight chamber partitioned by a diaphragm, and a signal line is taken out from both electrodes. Since it is necessary, the sensor element is constituted by processing glass and a silicon substrate individually, and anodic bonding and integrating them with electrode formation and wiring.
In this type of capacitance-type pressure sensor, a silicon substrate and a glass substrate that is anodically bonded to the silicon substrate and provided with a through hole that communicates with an airtight chamber formed between the silicon substrate, A silicon electrode plate fixed to the inner surface of the glass substrate by anodic bonding and closing the inner end opening of the through-hole in an airtight state; a conductor disposed in the through-hole and guiding a signal from the silicon electrode plate to the outside; There is known a pressure sensor having a configuration including: (See Patent Document 1)

As another example of a pressure sensor having another configuration, a step of forming a predetermined electrode pattern on a diaphragm made of an electrically insulating material and a fixed substrate, and the diaphragm and the fixed substrate are held and bonded at a constant interval. Forming a bonding layer on a peripheral edge of the diaphragm and the electrode of the fixed substrate; and bonding the diaphragm and the fixed substrate through the bonding layer and applying a load to fire and sinter the diaphragm and the fixed substrate. Capacitive type produced by a process of holding and bonding at a constant interval, and a process of baking the adhesive layer by high-temperature treatment with the load removed, and then gradually cooling to remove internal stress in the adhesive layer Pressure sensors and their manufacturing methods are known. (See Patent Document 2)
JP 2000-28463 A JP 9-318476 A

In a capacitance type pressure sensor manufactured by anodically bonding a glass substrate to the silicon substrate, it is necessary to use Pyrex (registered trademark) glass containing Na as an essential substrate for anodic bonding. Since Pyrex (registered trademark) glass is expensive and inevitably increases the manufacturing cost of the pressure sensor, the pressure sensor cannot be manufactured at a low cost.
In addition, when performing anodic bonding using Pyrex (registered trademark) glass, it is necessary to apply a high voltage to both the glass substrate and the Si substrate to bond them, so that the electrodes or wirings arranged with a gap are weak. There is a problem that sparks occur in the part or corrosive gas is generated during anodic bonding, and there is a high risk that a product with unstable capacity will be produced, and it is difficult to improve the product yield. .

The present invention has been made in view of the above circumstances, and can be obtained at low cost without using an expensive glass substrate such as Pyrex (registered trademark) glass, and without using a technique of anodic bonding in which yield improvement is difficult. The present invention relates to a technology capable of obtaining a capacitive pressure sensor that can be manufactured at low cost.
In addition, the present invention fundamentally reviewed the conventional structure that required anodic bonding, and was able to dispose the diaphragm layer opposite to the electrode without performing anodic bonding. An object of the present invention is to provide a capacitive pressure sensor element.

  The present invention has been made in view of the above circumstances, and at least a substrate having a surface portion made insulating, and an extraction electrode portion and a lower electrode formed separately from the insulating surface portion in a plan view. And at least part of the lower electrode part, at least part of the extraction electrode part, on the insulation part of the lower electrode part, and on the insulating surface part A spacer member made of a conductive material formed in a three-dimensional shape and electrically connected to the extraction electrode portion, and a predetermined gap between the insulating surface portion of the substrate and the lower electrode portion on the spacer member The diaphragm layer itself is made of a conductive material, or an electrode layer is formed on the diaphragm layer so as to face the lower electrode portion. A partial electrode portion is formed, the diaphragm layer is also formed to extend outside the spacer member, and the outer portion of the spacer member is covered by the extending portion of the diaphragm layer, and the terminal of the extraction electrode portion A through hole for terminal connection is formed in the extending part of the diaphragm layer corresponding to the electrode part, and a through hole for terminal connection is formed in the extending part of the diaphragm layer corresponding to the terminal electrode part of the lower electrode part It is characterized by being made.

In the capacitive pressure sensor element of the present invention, when the diaphragm layer provided on the spacer member is deformed by receiving pressure, the diaphragm layer itself or an upper electrode on the lower surface thereof and a lower electrode portion opposed thereto are disposed. Since the electrode interval changes, the capacitance changes. The pressure can be detected by detecting the change in capacitance. Further, even if the spacer member is disposed on the insulating portion of the lower electrode portion, the lower electrode portion and the spacer member do not conduct, and the spacer member is electrically joined only with the extraction electrode portion. The spacer member and the diaphragm layer are electrically connected to form one conduction path. On the other hand, since the lower electrode portion constitutes a pair of electrodes facing the diaphragm layer, a capacitive pressure sensor element having a configuration in which the pair of electrodes are disposed to face each other is formed.
By covering the peripheral side of the spacer member with the extended portion of the diaphragm layer, the electrodes and wirings around the spacer member can be physically protected. In addition, if a through hole for connecting a terminal is provided in the extended part of the diaphragm layer, wiring for connecting an external control device is applied to both electrodes on the diaphragm layer side and the lower electrode side through these through holes. Can be easily done.

The present invention is characterized in that the diaphragm layer is made of a Si substrate, and the spacer member is made of a metal material capable of eutectic bonding with Si.
By heating the Si substrate while being in contact with the spacer member, the spacer member and the Si substrate are bonded by causing eutectic bonding at the contact interface. This makes it possible to form a diaphragm layer without performing anodic bonding, which was essential by the combination of a conventional Si substrate and Pyrex (registered trademark) glass, so a high voltage must be applied to the wiring and electrode portions. The eutectic bonding between the diaphragm layer and the spacer member can be performed without heat, and the spacer member and the diaphragm layer can be bonded without damaging or damaging the wiring and electrode parts, which improves the manufacturing yield and increases the capacitance. As a pressure sensor element, it is possible to provide a high-quality product with little variation in capacitance change.
Further, the diaphragm layer can be composed of a Si substrate, and the surface insulating substrate need not be a Pyrex (registered trademark) glass substrate, and another general insulating substrate having an insulating layer may be used. Therefore, the cost of the substrate can be reduced, and the cost of the capacitive pressure sensor element itself can be reduced.
If Au is contained in the spacer member, the diaphragm layer and the spacer member can be reliably bonded by AuSi eutectic bonding.

The present invention has been made in view of the above circumstances, and the spacer member is annular so as to pass at least over at least a part of the extraction electrode part, the insulating part of the lower electrode part, and the insulating surface part. It is formed in these.
Since the spacer member is formed in an annular shape, the portion that supports the diaphragm layer becomes an annular shape, and the deformation followability of the diaphragm layer accompanying a change in pressure is improved, so that the pressure detection performance is improved.

The present invention has been made in view of the above circumstances, and both the extraction electrode portion and the lower electrode portion are embedded in the insulating surface portion, and the insulating portion is embedded in the lower electrode portion. In addition, the upper surface of the surface portion, the upper surface of the extraction electrode portion, the upper surface of the lower electrode portion, and the upper surface of the insulating portion are formed to be flush with each other.
Since the upper surface of the extraction electrode portion, the upper surface of the lower electrode portion, and the upper surface of the insulating portion are all flush with each other, the height of the upper surface of the spacer member formed thereon can be made constant. As a result, when the diaphragm layer is provided on the spacer member, the diaphragm layer and the spacer member can be in close contact with each other without any gap, and good bondability can be easily obtained. In particular, when an airtight structure is formed by the diaphragm layer, the annular spacer member, and the surface portion of the substrate, the airtightness of the portion surrounded by these can be easily ensured.
Further, when the diaphragm layer is made of a Si substrate and the spacer member is made of a metal material capable of eutectic bonding with Si, the eutectic bonding with Si is satisfactorily performed without any gap.

The present invention has been made in view of the above circumstances, and a part of the extraction electrode portion is extended to the outside in a plan view of the diaphragm layer along the surface portion to form one terminal electrode portion, and the lower electrode The portion is extended to the outside of the diaphragm layer along the surface portion to form the other terminal electrode portion.
By arranging a part of the extraction electrode part and a part of the lower electrode part outside the diaphragm layer, wiring connectivity such as wire bonding work to a part of the extraction electrode part and a part of the lower electrode part becomes good. Wiring connectivity with an external drive control device is improved.

The present invention has been made in view of the above circumstances, and is characterized in that the substrate is composed of a composite substrate in which a surface portion made of glazed alumina is formed on a base made of aluminum oxide.
Since the composite substrate having the surface portion of the glazed alumina is available at a low cost and much cheaper than the Pyrex (registered trademark) glass, the main material cost for manufacturing the capacitive pressure sensor element is reduced, and is low. Cost can be surely achieved.

  According to the present invention, it is possible to manufacture a diaphragm layer structure bonded to and supported by a spacer member without using an anodic bonding technique, and to manufacture a highly reliable product with high yield as a capacitive pressure sensor element. The structure which becomes possible can be provided.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to the embodiments described below. Further, in the drawings for explaining the following embodiments, the scales of the respective constituent parts are described by changing the scale for each constituent part so as to be easily described in the drawings.
FIG. 1 is a cross-sectional view showing an example of a capacitive pressure sensor element according to the present embodiment. FIG. 2 is a cross-sectional view for explaining an example of a method for manufacturing the capacitive pressure sensor element. FIG. 3 is a plan view for explaining an example of a method for manufacturing the same capacitive pressure sensor element.
The capacitive pressure sensor element 1 of this embodiment includes a substrate 3 having a glassy insulating surface portion 2 on the upper surface, and an extraction electrode portion 5 disposed on the surface portion 2 so as to be spaced apart in plan view. And on the surface portion 2 in an annular shape so as to pass over the lower electrode portion 6, the insulating portion 7 partially embedded in the lower electrode portion 6, and the extraction electrode portion 5 and the lower electrode portion 6. The spacer member 8 made of a conductive material and the diaphragm layer 9 made of a disc-like Si substrate formed on the spacer member 8 are roughly constituted.

The substrate 3 is made of a glazed alumina (Al ₂ O ₃ ) substrate having a rectangular shape in plan view and having a glassy insulating surface portion 2 on the surface. For example, the size of the capacitive pressure sensor element of this form Is formed in a size of about 2 × 2 mm.
The extraction electrode portion 5 is formed in a strip shape so as to be embedded in the left surface portion 2 of the substrate 3 shown in FIG. 1, and the upper surface 5A of the extraction electrode portion 5 is flush with the upper surface 2A of the surface portion 2. It is formed as follows. The lower electrode portion 6 has a circular lower electrode main body portion 6a formed so as to be embedded in the surface portion 2 in the central portion in plan view of the surface portion 2 shown in FIG. 1, and a flat surface on the right end side of the lower electrode main body portion 6a. It is formed in an outer shape keyhole shape in plan view composed of a strip-shaped lower electrode lead-out terminal portion 6b that is extended and formed so as to be embedded in the surface portion 2 facing outwardly from the visual side.

In this embodiment, the lower electrode portion 6 is formed so as to be embedded in the surface portion 2, and its upper surface 6 </ b> A is formed flush with the upper surface 2 </ b> A of the surface portion 2. The extraction electrode portion 5 and the lower electrode portion 6 formed in the shapes described above are formed to have a thickness of about several thousand mm, for example, about 2000 mm.
Further, the materials constituting these electrode parts 5 and 6 are Ti layer / Ta layer / Au layer / Ta layer laminated structure as an example, and other laminated structure examples are Ti layer / Ta layer / Au layer, Ta layer Layer / Au layer / Ta layer, Ta layer / Au layer, Cr layer / Au layer / Ta layer, Cr layer / Au layer, Cr layer / Ta layer / Au layer / Ta layer, Cr layer / Ta layer / Au layer, etc. However, the present invention is not limited to these examples.

On the other hand, it is embedded in the formation part of the lower electrode lead-out terminal part 6b, and is rectangular in plan view so as to protrude to both ends in the width direction of the lower electrode lead-out terminal part 6b having a strip shape in plan view and slightly spread to the surface part 2. An insulating portion 7 having a shape is formed. The insulating portion 7 is made of an insulating material such as SiO ₂ , Al ₂ O ₃ , or SiN _x and is formed thinner than the lower electrode portion 6 and is embedded in the lower electrode lead terminal portion 6 b. For example, it is formed to a thickness of about 1000 mm. The insulating portion 7 is embedded in the lower electrode leading terminal portion 6b and the surface portion 2 with the upper surface 7A being flush with the upper surface 6A of the lower electrode leading terminal portion 6b and the upper surface 2A of the surface portion 2.

Next, on the upper surface side of the surface portion 2, a spacer member 8 having an annular shape (doughnut shape) in plan view partially passes over the extraction electrode portion 5, and the other portion of the insulating portion 7. It is formed to pass over.
The spacer member 8 is made of Au or Au alloy, or a laminate of Au and another conductive material layer, for example, a conductive material having a two-layer structure of Ti layer / Au layer or a two-layer structure of Cr layer / Au layer. The spacer member 8 is formed to a thickness of about 0.7 to 2.0 μm by sputtering or plating, and the thickness (height) of the spacer member 8 forms a gap between the upper and lower electrodes described later. When the spacer member 8 has a two-layer structure of Ti layer / Au layer or a two-layer structure of Cr layer / Au layer, for example, the lower layer side is about 0.2 μm and the upper layer side is about 0.5-2.0 μm. be able to.
A diaphragm layer 9 made of a disk-like Si substrate is supported on the spacer member 8 in parallel with the upper surface 2A of the surface portion 2 with the outer periphery supported by the spacer member 8, and the diaphragm layer 9 is The gap between the diaphragm layer 9 and the lower electrode portion 6 is a gap between the upper and lower electrodes, and the diaphragm layer 9 is deformed by the pressure received by the diaphragm layer 9, so that the lower electrode portion 6 The capacitance is changed by changing the gap.

The diaphragm layer 9 is composed of a Si substrate having a thickness of about 40 to 80 μm, and is pressed with Au and Si, which will be described later (for example, vacuum heated to a high temperature of about 400 ° C. and pressed with a pressure of about 20 kg / cm ^2. Are joined and integrated by the joining method using the AuSi eutectic produced in the above.
In the first embodiment, since the diaphragm layer 9 made of the Si substrate is used, the diaphragm layer 9 itself has conductivity, and the diaphragm layer 9 also serves as the upper electrode portion. When a diaphragm layer made of an insulating substrate made of another material is used instead of the Si substrate, an upper electrode portion made of a conductive material is separately formed on the lower surface side of the diaphragm layer so as to conduct to the spacer member 8. What is necessary is just to comprise.

A portion of the extraction electrode portion 5 extending toward the outside of the spacer member 8 and the diaphragm layer 9 is formed with one extraction electrode portion 10 for wire bonding connection, and the lower electrode extraction terminal portion 6b. The other lead electrode portion 11 for wire bonding connection is formed in a portion extending toward the outside of the spacer member 8 and the diaphragm layer 9 in FIG.
These lead electrode portions 10 and 11 are preferably formed simultaneously with the same material when forming the previous spacer member 8, but separately formed with a conductive material different from the spacer member 8. Also good.

In order to manufacture the capacitive pressure sensor element 1 having the above-described configuration, the embedded extraction electrode portion 5 and the lower electrode portion 6 are formed on the surface portion 2 of the substrate 3 and the insulating portion 7 is formed. The spacer member 8 is formed so as to bridge over them, and then, as shown in FIG. 2, a Si substrate 9A having a thickness of about 40 to 80 μm is applied and pressed, and a pressure of about 20 kg / mm ² or more is applied. When heated to a high temperature of about 400 ° C., AuSi eutectic bonding occurs at the interface of the portion of the Si substrate 9 A pressed against the upper surface of the spacer member 8, so that the diaphragm layer 9 can be firmly bonded onto the spacer member 8.
If the diaphragm layer 9 is joined to the spacer member 8 in this way, only the necessary part as the sensor element is left and the other part is subjected to a dicing operation using a cutting grindstone or the like, for example, by E1 and E2 in FIG. The capacitive pressure sensor element 1 having a cross-sectional structure shown in FIG. 1 can be obtained by cutting along the cutting line shown in FIG.

  As described above, by using AuSi eutectic bonding, the spacer member 8 and the Si substrate 9A are bonded to form the diaphragm layer 9, so that a high voltage can be applied without performing anodic bonding which is necessary in the conventional structure. The diaphragm layer 9 can be bonded to the spacer member 8 without application, and the capacitance type pressure sensor element 1 can be manufactured without performing anodic bonding with a high risk of occurrence of wiring short-circuit, so that the yield can be improved. Therefore, it is possible to obtain a high-performance capacitive pressure sensor element 1 with little capacitance variation and high reliability.

Next, in manufacturing the capacitance type pressure sensor element 1 having the above-described structure, a method of manufacturing each electrode part in the case where the extraction electrode part 5 and the lower electrode part 6 are formed in an embedded type with respect to the surface part 2 is described. An example will be described.
When the capacitance type pressure sensor element 1 of the present invention is manufactured using the substrate 3 having the insulating surface portion 2, as shown in FIGS. 4 to 7 by a method using a lift-off resist described below. The extraction electrode portion 5 and the lower electrode portion 6 can be formed in the surface portion 2 in a buried manner.
As shown in FIG. 4, a lift-off resist is formed on the upper surface side of the surface portion 2 so as to surround the region 20 where the target extraction electrode portion 5 or the lower electrode portion 6 is to be formed from the peripheral side. Layers 21 and 21 are formed.
The lift-off resist layer 21 has a hole portion 22, and the extraction electrode portion 5 or the lower electrode portion 6 having a desired shape is formed in the surface portion 2 located below the hole portion 22.
In order to form the target lift-off resist layer 21, the lift-off resist layer is once formed on the entire upper surface of the surface portion 2, and then the hole 22 is formed by performing exposure and development on necessary portions.

If lift-off resist layers 21 and 21 having holes 22 are formed, they are not surrounded by lift-off resist layer 21 by ion milling, plasma etching, or wet etching using the lift-off resist layer 21 as a mask as shown in FIG. A hole 23 is formed in the surface portion 2 of the region.
Next, an electrode layer is formed on the upper surface of the surface portion 2 and the upper surfaces of the lift-off resist layers 21 and 21 by a film forming method such as a sputtering method or an ion beam film forming method. By this film forming process, the electrode layer 25 can be formed on the upper surface of the lift-off resist layers 21 and 21 as shown in FIG. It is preferable that the film thickness when this film formation is performed is such that the hole 23 can be filled.

  Next, the surface portion 2 and the electrode layers 25 and 26 are not affected, but the lift-off resist is obtained by immersing the entire portion in this chemical solution using a chemical solution capable of peeling the lift-off resist layer 21 from the surface portion 2 of the substrate 3. By separating the layer 21 from the surface portion 2 and lifting off, a structure in which the electrode layer 26 is embedded in the hole 23 formed in the upper surface of the insulating surface portion 2 as shown in FIG. 7 can be obtained. 4 to 7, the shape of the hole 23 is shown in a simplified manner for the sake of simplicity, but the shape of the hole 23 is a shape that matches the target extraction electrode portion 5 or the lower electrode portion 6. And

By applying the manufacturing method using the lift-off resist described above, the extraction electrode portion 5 or the lower electrode portion 6 can be embedded in the surface portion 2. Moreover, according to the above-described method, the hole 23 can be uniformly and almost completely embedded in the electrode layer 26 by adjusting the film thickness when the electrode layer 26 is formed in the hole 23. The upper surface of the electrode layer 26 can be formed substantially flush with the upper surface of the surface portion 2. Therefore, as shown in FIG. 1 and FIG. 2, the extraction electrode portion 5 and the lower electrode portion 6 of the type embedded in the insulating surface portion 2, and the upper surface 5 </ b> A of the extraction electrode portion 5 and the lower electrode portion 6. The upper surface 6A can be formed substantially flush with the upper surface 2A of the surface portion 2.
In addition, by forming the upper surface 5A of the extraction electrode portion 5 and the upper surface 6A of the lower electrode portion 6 substantially flush with the upper surface 2A of the surface portion 2, spacers formed on them in the subsequent steps are formed. Since the upper surface of the member 8 can be formed substantially flush, in that case, the Si substrate 9A can be uniformly pressed against the upper surface of the spacer member 8, and uniform bonding can be achieved, which is more uniform when bonding using AuSi eutectic. It is preferable in terms of obtaining bondability.
In addition, when a glazed alumina substrate is used in the above-described structure, it can be obtained at about 1/5 to 1/10 as a general commercial unit price compared to a Pyrex (registered trademark) glass substrate having a conventional structure. Can be manufactured at a lower cost.

8 and 9 are diagrams for explaining a second embodiment of the capacitive pressure sensor element according to the present invention. FIG. 8 is a sectional view, and FIG. 9 is a sectional view before the Si substrate is joined in the manufacturing process. is there.
In the capacitance type pressure sensor element 30 of the second embodiment, an extension portion 9c is formed on the outside of the diaphragm layer 9 so that the diaphragm layer 9 is extended, and the peripheral portion of the spacer member 8 is the extension portion 9c. The extension portion 9a is also bonded to the bonding auxiliary portion 32 that is covered and formed on the surface portion 2 on the peripheral side of the substrate 3, and the through holes 9a and 9b formed in the extension portion 9c are provided. It is located above extraction electrode parts 10 and 11, and extraction electrode parts 10 and 11 are constituted so that it can be seen through penetration holes 9a and 9b from the outside side of extension part 9c.

In the capacitive pressure sensor element 30 having the above-described configuration, the extraction electrode portions 10 and 11 are formed of the same film simultaneously with the film forming process in the case of forming the spacer member 8, and further, the same film is formed around them. The bonding auxiliary portion 32 is also formed, and when the Au substrate is bonded by covering the Si substrate 9A as shown in FIG. 9, the extension portion 9c of the Si substrate 9 is formed simultaneously with the bonding between the spacer member 8 and the diaphragm layer 9. AuSi eutectic bonding can be performed on the bonding auxiliary portion 32, whereby the Si substrate 9A is integrated on the surface portion 2 side of the substrate 3 with higher bonding properties.
In the capacitance type pressure sensor element 30 according to the second embodiment, the other configuration is the same as that of the capacitance type pressure sensor element 1 according to the first embodiment, and hence the description of the equivalent parts is omitted. To do.

In the structure of the second embodiment, if the Si substrate 9A is bonded to the surface portion 2 side of the substrate 3 in the same manner as in the first embodiment, dicing is performed along the cutting lines E3 and E4 shown in FIG. Unnecessary parts are deleted by such methods Thereby, the capacitive pressure sensor element 30 having the target structure shown in FIG. 8 can be obtained.
In the structure of the second embodiment, since the through holes 9a and 9b for wiring connection are formed in the extending portion 9c on the outer side of the diaphragm layer 9, the wiring is connected to an external control device for the sensor element. For example, since the extending portion 9c does not get in the way during wire bonding, the wiring work is not hindered.
Further, when the Si substrate 9A is AuSi eutectic bonded, the upper surface of the bonding auxiliary portion 32 can be used in addition to the upper surface of the spacer member 8, so that a stronger bonding structure can be obtained.
Furthermore, the capacitance type pressure sensor element 30 of the second embodiment has a structure in which the upper surface is covered and protected by a single Si substrate 9A, so that the surface is smooth and easy to handle. Have.

By the way, in the capacitance type pressure sensor elements 1 and 30 of the first and second embodiments, the diaphragm layer 9 is formed using a uniform thickness as the Si substrate 9A. Alternatively, an Si substrate in which only a portion to be a diaphragm layer is etched and thinned, and a portion other than the diaphragm layer forming portion is formed thicker than that to improve the substrate strength may be used.
Further, since the substrate used in the present invention can be a substrate having at least an insulating surface portion, for example, a substrate that is entirely an insulator can be used, and of course, a region deeper than the surface portion. Of course, for example, a substrate having an insulating layer up to about half the thickness of the substrate or an arbitrary depth may be used.

Using a glazed alumina substrate having a glazed alumina layer having a thickness of 0.25 to 0.80 mm and a thickness of 20 to 60 μm on the upper surface of Al ₂ O ₃ , a novolac-based lift-off resist is formed on the glazed alumina layer. The layer is patterned (extraction electrode portion 5 and lower electrode portion 6 formation pattern), exposed and developed to form holes corresponding to the extraction electrode portion and the lower electrode portion, and a lift-off resist around these hole portions A hole having a depth of 2000 mm was formed in the glazed alumina layer by ion milling using the layer as a mask. Since this hole is formed by ion milling, it is possible to form a hole having a uniform depth without any irregularities with an accuracy of 10 to 20 mm on the bottom surface of the hole.
Thereafter, an electrode layer having a three-layer structure of Ti layer / Au layer / Ta layer (each layer thickness of 200 mm / 1500 mm / 300 mm) is laminated in the hole by ion beam sputtering, and then, with an NMP resist stripping solution The lift-off resist layer was removed to obtain a substrate in which the extraction electrode portion and the lower electrode portion were embedded in the hole portion in the glazed alumina layer.

Next, a rectangular hole in a plan view (0.05 to 0.4 × 0.05 to 0.4 mm) reaching the glazed alumina layer as a pattern using the same lift-off resist layer is formed, and then An insulating portion of SiO _{2 having} a rectangular shape in plan view was formed in the hole portion (formation of insulating portion 7).
Next, a plating seed (Ti layer / Au layer) is formed on the entire surface of the glazed alumina layer of the substrate, followed by Au partial plating of 0.5 to 2.0 μm as a pattern spacer member, and then unnecessary portions. The gold plating seed is removed to form a three-layered annular spacer member (outer diameter 1.0 mm, inner diameter 0.8 mm, height 1.0 μm) and each extraction electrode part of Ti layer / Au / Au layer did.

Next, an Si substrate having a thickness of 80 μm is prepared, a through hole is formed in a portion corresponding to the extraction electrode portion, and the Si substrate is placed on the previously-glazed alumina substrate and is vacuumed while being pressurized at a pressure of 20 kg / mm ^2. It was heated to 400 ° C. for 2 hours and joined.
By this bonding process, the Si substrate is AuSi eutectic bonded to the upper surface of the annular spacer member, a diaphragm layer having a thickness of 80 μm is bonded onto the annular spacer member, the upper electrode is formed of the diaphragm layer, and the lower electrode is A capacitive pressure sensor element having an electrode structure having a pair of upper and lower electrode gaps of 1.0 μm composed of a lower electrode portion having a three-layer structure of Ti layer / Au layer / Ta layer in the hole was obtained.
When a pressurization test applying an air pressure of 100 to 500 MPa was performed on the obtained sample of the capacitance type pressure sensor element, it was confirmed that a change in capacitance occurred, and this sample was a capacitance type. It was confirmed that it functions as a pressure sensor element.

  The present invention is a technology capable of providing a small and light capacitive pressure sensor element having a size of several mm square, for the purpose of detecting air pressure of an automobile tire on which high G acts, or other general gas. It can be widely applied in various fields for pressure detection, such as a pressure sensor and a fluid pressure sensor.

FIG. 1 is a sectional view showing an embodiment of a capacitive pressure sensor element according to the present invention. FIG. 2 is a cross-sectional view showing a state before the Si substrate is pressed against the spacer member when the capacitive pressure sensor element of the embodiment is manufactured. FIG. 3 is a plan view in which the diaphragm layer portion of the capacitive pressure sensor element of the embodiment is omitted. FIG. 4 is a cross-sectional view showing a state in which a lift-off resist layer is formed on the surface portion in the method for forming the electrode portion of the capacitive pressure sensor element of the same embodiment. FIG. 5 is a cross-sectional view showing a state in which a hole is formed in the surface portion using the lift-off resist layer as a mask in the method of forming the electrode portion of the capacitive pressure sensor element of the embodiment. FIG. 6 is a cross-sectional view showing a state in which the electrode portion is formed in the hole portion shown in FIG. 5 in the method for forming the electrode portion of the capacitive pressure sensor element of the same embodiment. FIG. 7 is a cross-sectional view showing a state where the lift-off resist layer is removed in the method of forming the electrode portion of the capacitive pressure sensor element of the same embodiment. FIG. 8 is a sectional view of a second embodiment of the capacitive pressure sensor element according to the present invention. FIG. 9 is a cross-sectional view showing a state before bonding of the Si substrate when the capacitive pressure sensor element of the same form is manufactured.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Capacitance type pressure sensor element 2 Surface part 3 Substrate 5 Extraction electrode part 5A Upper surface 6 Lower electrode part 6A Upper surface 6a Lower electrode main body part 6b Lower electrode extraction terminal part 7 Insulation part 7A Upper surface 8 Spacer member 9 Diaphragm layers 9a, 9b Through-hole 9c Extension part 10, 11 Extraction electrode part 30 Capacitive pressure sensor element

Claims (6)

Formed on at least part of the lower electrode part, a substrate having at least a surface part made insulating, an extraction electrode part and a lower electrode part formed separately from the insulating surface part in a plan view. And at least a portion of the extraction electrode portion, the insulation portion of the lower electrode portion, and the insulating surface portion, and is electrically connected to the extraction electrode portion. A spacer member made of a conductive material, and a diaphragm layer provided on the spacer member via a predetermined gap from the insulating surface portion of the substrate and the lower electrode portion, or diaphragm layer itself is composed of a conductive material, or Ri Na and upper electrode portion opposed to the lower electrode portion electrode layer is formed is formed in the diaphragm layer, said diaphragm layer An outer portion of the spacer member is formed so as to extend outside the spacer member, and the outer portion of the spacer member is covered with the extending portion of the diaphragm layer, and the extended portion of the diaphragm layer corresponding to the terminal electrode portion of the extraction electrode portion A capacitance type pressure characterized in that a through hole for terminal connection is formed, and a through hole for terminal connection is formed in an extension portion of the diaphragm layer corresponding to the terminal electrode portion of the lower electrode portion. Sensor element. The capacitive pressure sensor element according to claim 1, wherein the diaphragm layer is made of a Si substrate, and the spacer member includes a metal material capable of eutectic bonding with Si. 2. The spacer member according to claim 1, wherein the spacer member is formed in an annular shape so as to pass through at least a part of the extraction electrode part, an insulating part of the lower electrode part, and an insulating surface part. Or the capacitance type pressure sensor element according to 2; Both the extraction electrode portion and the lower electrode portion are embedded in the insulating surface portion, the insulating portion is embedded in the lower electrode portion, and the upper surface of the surface portion and the upper surface of the extraction electrode portion capacitive pressure sensor element according to any one of claims 1 to 3, and the lower electrode upper surface and the insulating upper surface is characterized by comprising formed flush. A part of the extraction electrode portion is extended to the outside in a plan view of the diaphragm layer along the surface portion to be one terminal electrode portion, and the lower electrode portion is outside the diaphragm layer along the surface portion. capacitive pressure sensor element according to any one of claims 1 to 4, extending issued by, characterized in that formed by the other terminal electrode portion. Capacitive pressure sensor element according to any one of claims 1 to 5, characterized in that the substrate is composed of a composite substrate surface portion is formed consisting of glazed alumina on a substrate made of aluminum oxide.

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