JPH06213703A - Vibration detecting element - Google Patents

Abstract

PURPOSE:To allow continuous measurement of vibration by providing a first conductive substrate having a conical recess, a second conductive substrate arranged oppositely thereto while covering the recess, and an insulation film sandwiched by the first and second substrates while containing a metal ball in the recess, thereby forming a capacitor structure between the first and second substrates. CONSTITUTION:A lower substrate 1 has a concave part 1a and made of silicon serving as a lower electrode. An upper substrate 2 is bonded onto the lower substrate 1 to cover the concave part 1a and made of silicon serving as an upper electrode. An insulation film 3 is formed between the upper and lower substrates thus forming a capacitor structure between them. In such vibration detecting element, a metal ball 4 rolls on the inner face of the concave part 1a upon application of vibration and the upper and lower substrates substantially approache each other thus varying the capacitance of the capacitor. The capacitance represents the magnitude of the acceleration of vibration.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration detecting element for detecting vibration generated when an object moves, for example.

[0002]

2. Description of the Related Art Conventionally, as a vibration detecting element for detecting a vibration when an object moves, as shown in a front view, a side view and a bottom view in FIGS. Four conductive rods 32, half of which are conductive portions 32a and half of which are insulating portions 32b, are arranged in a rectangular shape around the sex sphere 31, and the sphere 31 rolls when there is vibration, Three
1 and the conductive portion 32a of the rod 32 come into contact with each other,
Electrical continuity was obtained, by which vibrations were detected. In FIG. 4, 33 is four conductive bars 32.
Is a plate that supports a rectangular shape, and 34 is an inclined portion that positions the spherical body 31 in one direction. A vibration detecting element having such a structure is disclosed in, for example, Japanese Patent Laid-Open No. 61-187621.

Further, as other elements for detecting the magnitude of vibration, for example, a vibration displacement detecting element, a vibration velocity detecting element and an acceleration detecting element have been proposed. As a vibration detecting element of this type, for example, a miniaturized acceleration detecting element has a movable electrode 43 which acts as a weight at the tip of a cantilever 42 by etching the silicon plate 41 from both sides as shown in the sectional view of FIG. The glass plates 46 and 47 formed and having the fixed electrodes 44 and 45 formed on the surfaces thereof are adhered to both surfaces of the silicon plate 41, and the vertical displacement generated according to the acceleration component in the direction of the arrow Y is caused by the movable electrode 43 and the fixed electrode 44. , 4
The differential capacitance was obtained by detecting the change in the capacitance between the sensor and the vibration, and the vibration was detected. In addition,
In FIG. 5, reference numeral 48 is a groove-shaped through groove, and 49 is the movable electrode 4.
3 extraction electrode. The vibration detecting element having such a structure is disclosed in, for example, Japanese Patent Application Laid-Open No. 1-152369.

[0004]

However, the former vibration detecting element described above not only has a large element structure, but also has a problem in that the cost is high because each of the constituent parts must be assembled one by one. It was Further, the sphere 31 comes into contact only when it exceeds a predetermined design value, and if it exceeds the predetermined design value, the sphere 31 is always in contact with the sphere 31 and there is a problem that the magnitude of vibration cannot be known. Further, in order to know the magnitude of vibration, a plurality of detecting elements in which the size of the sphere 31 is changed are required, which is not practical in terms of size and cost. Further, the vibration detecting element using a conductive liquid instead of the sphere 31 has the same problem. Further, the latter capacitive vibration detection element described above has a complicated structure because a linear relationship is provided between the magnitude of vibration and the output, which complicates the manufacturing process, and thus can be configured in a small size. There was a problem that the cost could not be reduced.

Therefore, the present invention has been made in order to solve the above-mentioned conventional problems, and an object of the present invention is to provide a small-sized and low-cost vibration that can obtain a vibration magnitude with a continuous value within a certain range. It is to provide a detection element.

[0006]

In order to achieve such an object, a first invention is a first conductive substrate having a mortar-shaped recess, and a mortar-shaped recess on the first conductive substrate. A second conductive substrate disposed so as to cover the first conductive substrate, a metallic sphere housed in a mortar-shaped recess of the first conductive substrate, the first conductive substrate and the second conductive substrate. An insulating film is provided between the first conductive substrate and the second conductive substrate, and a capacitor structure is formed between the first conductive substrate and the second conductive substrate. The second invention is the first invention having a mortar-shaped recess.
A non-magnetic substrate, a second non-magnetic substrate which is disposed on the first non-magnetic substrate so as to face the mortar-shaped recess, and is housed in the mortar-shaped recess of the first non-magnetic substrate. A magnetic sphere and a magnetic sensor formed on the surface of the second non-magnetic substrate facing the mortar-shaped recess are provided. A third invention is a first non-magnetic substrate having a mortar-shaped recess, and a second non-magnetic substrate arranged on the first non-magnetic substrate so as to face the mortar-shaped recess. This first
The magnetic fluid contained in the mortar-shaped recess of the non-magnetic substrate and the magnetic sensor formed on the surface of the second non-magnetic substrate facing the mortar-shaped recess are provided.

[0007]

In the first aspect of the present invention, the metallic spheres housed in the mortar-shaped recesses of the first conductive substrate are rolled, whereby the first conductive substrate and the second conductive substrate are separated from each other. The capacitance value of the capacitor structure formed between them changes. In the second invention, the magnetic spheres housed in the mortar-shaped recesses of the first non-magnetic substrate roll, so that the magnetic sensor arranged to face the second non-magnetic substrate senses its magnetism. .

[0008]

Embodiments of the present invention will now be described in detail with reference to the drawings. (Embodiment 1) FIG. 1 is a cutaway perspective view showing the structure of an embodiment of a vibration detecting element according to the present invention. In FIG. 1, reference numeral 1 denotes a lower substrate made of silicon also serving as a lower electrode having a mortar-shaped curved portion 1a formed on one surface, and 2 denotes a lower substrate 1 on which the curved portion 1a is closed. An upper substrate 3 made of silicon and also serving as an upper electrode bonded and arranged is an insulating film formed on a surface facing the lower substrate 1 of the upper substrate 2.

Reference numeral 4 denotes a metallic sphere that is rollably accommodated in the curved portion 1a of the lower substrate 1, 5 is an output terminal formed at one end of the lower substrate 1, and 6 is an upper side. It is an output terminal formed on the substrate 2. A capacitor structure that forms a capacitance is formed between the lower substrate 1 and the upper substrate 2.

In the vibration detecting element constructed as described above, when vibration is applied, the metallic sphere 4 rolls on the inner surface of the curved portion 1a, so that substantially the lower substrate 1 becomes the upper substrate. 2, the capacitance value of the capacitor structure changes. The magnitude of this capacitance value is obtained as the magnitude of vibration acceleration.

Next, a method of manufacturing the vibration detecting element having the above structure will be described. FIGS. 2A to 2F are views showing steps of an example of the method for manufacturing the vibration detecting element described in FIG. In this example, a case where an n-type silicon substrate with an oxide film is used as the upper substrate will be described. First, as shown in the cross section of FIG. 2A, a silicon nitride film is formed as a mask material for forming a groove on the other surface of the n-type silicon substrate 12 having the oxide film 11 formed on one surface. . Next, an ultraviolet-sensitive resist is applied on the silicon nitride film to form a resist film, and a mask that blocks ultraviolet light is placed on the resist film, and ultraviolet light is irradiated.

Next, after developing this resist film, the silicon nitride film is etched by dry etching using, for example, CF ₄ gas to form a silicon nitride film 13. Next, after removing the resist film, the silicon substrate 12 is etched using the silicon nitride film 13 as a mask material. This silicon substrate 12
There is a method of using an etching solution mainly containing KOH, but in this case, the resistance of the oxide film 11 to KOH is about 3 to 10 times stronger when the oxide film is 1. Therefore, it is necessary to make it difficult for the etching solution to come into contact with the oxide film 11. For this reason, although not shown, for example, a resist film is formed on the surface of the oxide film 11 and immersed in an etching solution mainly containing KOH to form a groove 14 in the silicon substrate 12 as shown in FIG. 2B. To do.

Next, the silicon nitride film 13 on the silicon substrate 12 is peeled off to complete the upper substrate 15. After that, output terminals are formed on the end portions of the silicon substrate 12. Since the silicon substrate 12 is a conductive substrate,
Although the output terminal can be formed directly, a metal film can be formed using a thin film forming technique such as vapor deposition in order to improve stability.

Next, the lower substrate is formed. In this embodiment, a case where an n-type silicon substrate without an oxide film is used as the lower substrate will be described. First, as shown in the cross section in FIG. 2C, a resist is applied on the n-type silicon substrate 16 to form a resist film, and a predetermined mask pattern 17 is formed on the resist film by using the transfer technique described above. Next, the silicon substrate 16 is etched using the resist pattern 17 as a mask material. If an isotropic etchant represented by, for example, a mixed solution of sulfuric acid and hydrofluoric acid is used as the etchant, a mortar-shaped recess 18 as shown in FIG. 2C is used.
Is formed. Then, the resist pattern 17 is peeled off to complete the lower substrate 19 as shown in FIG.

Next, as shown in FIG. 2E, the lower substrate 19
The metallic spheres 4 are housed in the respective mortar-shaped recesses 18 of the above, and the upper substrate 15 is placed on the lower substrate 19 with the oxide film 11 surface side facing each other, and heated to 400 to 500 ° C., Further, there are several 10s between the upper substrate 15 and the lower substrate 19.
A voltage of 0 V is applied and the upper substrate 15 and the lower substrate 19 are bonded and fixed by an anodic bonding method.

Next, as shown in the perspective view of FIG. 2 (f), a dicing saw is used to divide the pieces one by one along a predetermined dividing line 20 in the vertical and horizontal directions. After the division, it is completed through a packaging process similar to the semiconductor manufacturing process.

According to such a method, since the semiconductor manufacturing technique of manufacturing a large amount on a silicon substrate at the same time can be used, the semiconductor device can be formed with a simple structure, so that the manufacturing process can be simplified and the cost can be reduced.

(Embodiment 2) FIG. 3 is a cutaway perspective view showing the structure of a vibration detecting element according to another embodiment of the present invention. The same parts as those in FIG. 1 described above are designated by the same reference numerals. In the figure, 7 is a magnetized magnetic sphere housed in the curved portion 1a of the lower substrate 1, and 8 is a magnetic element formed of, for example, a magnetoresistive element formed on the surface of the upper substrate 2 facing the curved portion 1a. The sensors 9a and 9b are magnetic sensors 8 formed on one end of the lower substrate 1 via an insulating film (not shown).
Is an output electrode terminal of. The output electrode terminals 9a and 9b of the magnetic sensor 8 are also formed on the upper substrate 2 via an insulating film (not shown). Also in this case,
The lower substrate 1 is configured to be grounded.

In the vibration detecting element thus constructed, when the magnetic sphere 7 rolls in the bending portion 1a when vibration is applied, the distance between the magnetic sensor 8 and the magnetic sphere 7 changes and the magnetic sensor 8 becomes magnetic. It senses that the sphere 7 has rolled. In this case, the output waveform differs depending on the location of the magnetic sensor 8. For example, in FIG. 3, the magnetic sensor 8 is on the left side, and when this vibration detecting element moves to the right, the magnetic sphere 7 moves to the left. At this time, since the magnetic sphere 7 approaches the magnetic sensor 8, the output becomes large. The magnetic sensor 8 does not have to be arranged at one place, and a plurality of magnetic sensors 8 may be arranged to form a bridge circuit, for example.

Further, since the vibration detecting element thus constructed utilizes magnetism to detect vibration, the lower substrate 1
The insulating film 3 for obtaining insulation between the upper substrate 2 and the upper substrate 2 may or may not be provided. When the oxide film 3 is present, anodic bonding is possible, but when the oxide film 3 is not present, direct bonding is performed between the substrates. When the substrate is silicon, the substrates can be joined together by heating to a temperature of a few thousand and several hundreds.

In the embodiment thus constructed, the magnetic sensor 8 is provided on the upper substrate 2 and the output electrode terminals 9a and 9b are formed on the lower substrate 1. Electrical connections must be made in place. In this case, when the upper substrate 2 and the lower substrate 1 are joined, the joining may be performed by providing an overlapping portion.

Further, in the above-mentioned embodiment, the bending portion 1
When the rolling of the metallic spheres 4 and the magnetic spheres 7 housed in a is too fast, the degree of rolling can be changed by containing a viscous fluid in the bending portion 1a. This means changing the frequency characteristic of the vibration detecting element. In the case of Example 1, it is necessary to use an insulating fluid, and in the case of Example 2, it is necessary to use a non-magnetic fluid.

In addition, in the above-described embodiment, the gas existing in the curved portion 1a expands to heat the substrates during the bonding. Depending on the bonding temperature, this expansive force acts to break the bond. As a countermeasure against the strong expansion force, it is possible to solve the problem by providing a passage for allowing the gas in the curved portion 1a to escape to the outside in at least one of the lower substrate and the upper substrate.

Further, in the above-mentioned embodiment, the case where the metallic sphere 4 and the magnetic sphere 7 are perfect spheres having substantially the same diameter has been described, but the present invention is not limited to this and, for example, an ellipse. It is needless to say that the same effect as described above can be obtained by using a spherical body (elliptical sphere).

In the above-described embodiment, the case where the magnetic sphere 7 is housed in the curved portion 1a of the lower substrate 1 has been described, but the present invention is not limited to this, and the magnetic sphere 7 is not limited to this. It goes without saying that the same effect as described above can be obtained even if a magnetic fluid is contained instead of the above. Also in this case, the magnetic fluid may have a spherical shape, an elliptic spherical shape, or various shapes.

[0026]

As described above, according to the present invention,
With a simple configuration, the magnitude of vibration can be obtained as a continuous value within a certain range, and an extremely excellent effect such that the vibration detection element can be made compact and at low cost can be obtained.

[Brief description of drawings]

FIG. 1 is a cutaway perspective view showing a configuration of an embodiment of a vibration detecting element according to the present invention.

2A to 2D are process diagrams illustrating a method for manufacturing the vibration detection element shown in FIG.

FIG. 3 is a cutaway perspective view showing a structure of a vibration detecting element according to another embodiment of the present invention.

FIG. 4 is a diagram illustrating a configuration of a conventional vibration detecting element.

FIG. 5 is a cross-sectional view illustrating the configuration of a conventional vibration detecting element.

[Explanation of symbols]

 1 Lower Substrate 1a Curved Part 2 Upper Substrate 3 Insulating Film 4 Metallic Sphere 5 Output Terminal 6 Output Terminal 7 Magnetic Sphere 8 Magnetic Sensor 9a Electrode Terminal 9b Electrode Terminal

Claims (3)

[Claims] 1. A first conductive substrate having a mortar-shaped recess, a second conductive substrate disposed on the first conductive substrate so as to cover the recess, and the first conductive substrate. A metallic sphere housed in the recess of the conductive substrate; and an insulating film disposed between the first conductive substrate and the second conductive substrate, the first conductive substrate A vibration detecting element having a capacitor structure formed between a substrate and a second conductive substrate. 2. A first non-magnetic substrate having a mortar-shaped recess, a second non-magnetic substrate arranged on the first non-magnetic substrate so as to face the recess, and a first non-magnetic substrate. A vibration detecting element, comprising: a magnetic sphere housed in the recess of the non-magnetic substrate; and a magnetic sensor formed on a surface of the second non-magnetic substrate facing the recess. 3. A first non-magnetic substrate having a mortar-shaped recess, a second non-magnetic substrate arranged on the first non-magnetic substrate so as to cover the recess, and a first non-magnetic substrate. A vibration detecting element, comprising: a magnetic fluid housed in the recess of a non-magnetic substrate; and a magnetic sensor formed on a surface of the second non-magnetic substrate facing the recess.