JPH09292409A - Accelerometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an accelerometer which is low-cost, whose mass-productivity and reliability are enhanced and whose surface mounting operation is performed easily by a method, wherein a cap is bonded onto mumerous G microsensors formed on a silicon wafer and a detection part is arranged in an airtight space. SOLUTION: An acceleration detection part 2 and a signal processing circuit part 3 are formed on a silicon plate 1, and a cap 13 is bonded by an adhesive 4 onto the silicon plate 1, in such a way that both are arranged inside an airtight space. In the detection part 2, a movable mask 8 which comprises slits 7 is supported by four beams 6, and end parts on one side of the beams 6 are formed so as to be fixed and bonded into the silicon plate 1 by fixation ends 5. Then, in the circuit part 3, a change on sizes of gaps 14, 15 conesponsing to the magnitude of an acceleration Gz is converted into an output signal which is proportional to the acceleration. Then, since the space 43 surrounding the detection part 2 is maintained airtight, it is possible top prevent dust particles from creeping into a gap part when a G microsensor is diced on a silicon wafer. In addition, when pads 9 are formed on the silicon plate 1, the surface mounting operation of an accelerometer to various substrates can be performed easily.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acceleration sensor for detecting acceleration, and more particularly to an acceleration sensor used in an automobile air bag system or the like.

[0002]

2. Description of the Related Art Conventionally, a movable mass supported by a beam and having a function of a movable electrode, an acceleration detecting portion composed of a fixed electrode arranged so as to face the movable mass, and a movement of the movable mass displaced in accordance with the acceleration. Acceleration sensor integrated with a signal processing circuit unit for converting into an acceleration signal on a silicon plate
(Hereinafter referred to as "micro G sensor") is known in the August 1991 issue of ELECTRONIC DESIGN, pages 45-56 and others.

[0003]

The above-described micro G sensor has the following drawbacks because the detection portion having a minute gap between the movable mass and the fixed electrode has a non-airtight structure. That is, after the wafer process is completed, each micro G
When dicing into the sensor, there were problems in mass productivity and reliability, such as dust entering the voids and the beam supporting the movable mass being destroyed. Further, since the detection unit has a non-hermetic structure, the micro G sensor cannot be directly surface-mounted on the module substrates of various systems, and it is necessary to hermetically seal the metal can package or the ceramic package. As a result, it has been a factor of increasing the cost of the micro G sensor. In addition, there is a problem that accelerations of two or more orthogonal components cannot be detected.

An object of the present invention is to solve the above problems,
An object of the present invention is to provide an integrated micro G sensor which is low in cost and excellent in mass productivity and reliability. Another object of the present invention is to provide an integrated micro G sensor that can be easily surface-mounted and can simultaneously detect accelerations of two or more orthogonal components.

[0005]

A movable mass supported by a beam and having a function of a movable electrode, an acceleration detecting portion composed of a fixed electrode arranged facing the movable mass, and a movement of the movable mass displaced according to acceleration. After forming a large number of micro G sensors integrated on a silicon plate with a signal processing circuit section for converting the acceleration signal into an acceleration signal on the silicon wafer, at least the acceleration detection section is arranged on the silicon wafer so as to be arranged in an airtight space. Join the cap to. By dicing into the sensing device of each micro G sensor after joining the caps, it is possible to solve problems relating to mass productivity and reliability, such as dust in the voids and breakage of the beam supporting the movable mass. .

By forming at least the detection portion in an airtight structure, it becomes unnecessary to hermetically seal a metal can package, a ceramic package or the like. By forming pads that can be mounted with solder on a silicon plate, the micro G sensor can be directly surface-mounted with solder balls on module boards of various systems. As a result, the factor that increases the cost of the micro G sensor can be eliminated.

By providing a pair of fixed electrodes arranged so as to face the movable mass and be orthogonal to each other, accelerations of two or more orthogonal components can be simultaneously detected.

[0008]

1 is a plan view of an embodiment of a micro G sensor according to the present invention. An acceleration detection unit 2 and a signal processing circuit unit 3 are formed on a semiconductor substrate, for example, a silicon plate 1, and the acceleration detection unit 2 and the signal processing circuit unit 3 are arranged on the silicon plate 1 so as to be arranged in an airtight space. The adhesive 4 for joining the cap 13 as the covering material is shown. The acceleration detecting unit 2 is composed of a movable mass 8 which is a movable mass member supported by four beams 6 which are supports, and one end of the beam 6 is fixed on the silicon plate 1 at a fixed end 5. Has been done. For the purpose of smoothing the movement of the movable mass itself, the movable mass 8 is provided with a slit 7 for improving the fluidity of air in the gap between the silicon plate 1 and the movable mass 8. Further, the silicon plate 1 is provided with a pad 9 which is a terminal as a micro G sensor. The pads 9 are power terminals,
Used as output terminal, diagnostic terminal, etc.

A cross-sectional view of an embodiment of the micro G sensor according to the present invention is shown in FIG. The previous figure shows a plan view of the silicon plate 1 in this figure, and this figure shows a cross-sectional view of the micro G sensor at the position AA in the previous figure. It should be noted that in the drawings shown after this figure, the same elements and elements having the same function are assigned the same reference numerals for description.
This is a micro G sensor in which an acceleration detection unit is manufactured by using an SOI substrate in which a silicon plate 1 for element formation and a silicon plate 10 for a support substrate are bonded via a thermal oxide film 11. After the signal processing circuit unit 3 is formed on the silicon plate 1 by a well-known semiconductor process, the acceleration detection including the movable mass 8 supported by the beam is performed by dry etching of the silicon plate 1 and sacrifice layer etching of the thermal oxide film 11. To form a part. The signal processing circuit unit 3 is passivated with an insulating layer 12 such as a thermal oxide film. A cap 13 made of a silicon plate is bonded onto the silicon plate 1 via an adhesive material 4.
The surface of the thermal oxide film 12 and the cap 13 is preliminarily Ti /
If a two-layer thin film of Ni is formed, at least one of the Ti / Ni thin films is formed by sputtering or the like.
An insert material composed of a thin film is used as the adhesive material 4. According to our experiment, the cap 13 is attached to the silicon plate 1
After stacking on top of the
When a load of 1 kg per square millimeter was applied for 15 minutes, the cap 13 and the silicon plate 1 were airtightly and strongly bonded. In addition to Ag, a metal thin film such as Au was also effective. As a result, the space 43 that surrounds the acceleration detecting portion composed of the movable mass 8 supported by the beam is kept airtight. Therefore, even if a large number of micro G sensors are formed on a silicon wafer and then the dicing is performed on the sensing device of each micro G sensor with a dicer or the like, dust may enter the voids or the beam that supports the movable mass may be destroyed. No problem occurred.

The micro G sensor shown in the figure detects an acceleration component Gz in a direction perpendicular to the surface of the silicon plate 1. That is, when the gaps between the movable mass 8 and the cap 13 and the silicon plate 10 are 14 and 15, respectively, the dimensions of the gaps 14 and 15 change according to the magnitude of the acceleration Gz, and the capacitance of the gap changes. Therefore, the signal processing circuit unit 3 can convert this into an output signal proportional to the acceleration.

A plan view of another embodiment of the micro G sensor according to the present invention is shown in FIG. Two pairs of fixed electrodes are fixed on the thermal oxide film on the silicon plate 1 so as to face the movable mass 8 supported by the four beams. That is, the fixed electrode 16
And 16a and a fixed electrode pair made up of fixed electrodes 18 and 18a. The present micro G sensor is capable of detecting acceleration components Gx and Gy in a direction parallel to the surface of the silicon plate 1. The acceleration component Gx is calculated from the change in the capacitance of the gaps 17 and 17a between the movable mass 8 and the fixed electrode pair 16 and 16a, and the acceleration component Gx is calculated from
The acceleration component Gy orthogonal to the acceleration component Gx can be detected from the change in the capacitance of the gaps 19 and 19a between 8 and 18a. Note that the silicon plate 1 shown in the next figure is arranged so that the beam supporting the movable mass 8 can also be moved similarly to the movable mass 8.
Floating from zero.

A cross-sectional view of another embodiment of the micro G sensor according to the present invention is shown in FIG. This figure shows a cross-sectional view of the micro G sensor at the position BB in FIG. The fixed electrodes 16 and 16 a arranged via the movable mass 8 and the gaps 17 and 17 a are firmly fixed on the thermal oxide film 11. When the cap 13 is made of a silicon plate, the adhesive material 4 is an insert material made of an Ag thin film as in FIG. In the case of this figure, since it is not necessary to detect the change in the gap size between the movable mass 8 and the cap 13, an insulating material such as glass may be used for the cap 13. In this case, an insulating layer 12 such as a thermal oxide film is used as an adhesive.
The cap 13 can be airtightly bonded to the silicon plate 1 by well-known anodic bonding if the polycrystalline silicon film is formed on the silicon plate 1.

A sectional view of another embodiment of the micro G sensor according to the present invention is shown in FIG. Similar to the micro G sensor shown in FIG. 2, this embodiment is a sensor for detecting an acceleration component Gz in a direction perpendicular to the surface of the silicon plate 1, and differs from that shown in FIG. 2 in the following points. After the signal processing circuit unit 3 is formed on the silicon plate 1 by a well-known semiconductor process,
The dry mass of the polycrystalline silicon layer formed on the insulating layer 12 such as the thermal oxide film of the silicon plate 1 and the sacrificial layer etching of the insulating film are supported by the beam made of polycrystalline silicon and the movable mass made of polycrystalline silicon. 8 forming. The signal processing circuit section 3 is an insulating layer 1 such as a thermal oxide film.
2 is passivated, and a cap 13 made of a silicon plate is bonded onto the silicon plate 1 via an adhesive 4. As described above, the present embodiment is characterized in that the acceleration detecting portion composed of the movable mass 8 is formed by the polycrystalline silicon layer provided on the silicon plate 1 without using the SOI substrate.

FIG. 6 shows a sectional view of another embodiment of the micro G sensor according to the present invention. This embodiment is a sensor for detecting the acceleration component Gx in the direction parallel to the surface of the silicon plate 1 similarly to the micro G sensor shown in FIG. 4, and is different from the one shown in FIG. 4 in the following points. After the signal processing circuit unit 3 is formed on the silicon plate 1 by a well-known semiconductor process,
The movable mass 8 made of polycrystalline silicon and the fixed electrodes 16, 16a are formed by dry etching of the polycrystalline silicon layer formed on the insulating layer 12 such as a thermal oxide film of the silicon plate 1 or etching of the insulating film. ing. The signal processing circuit unit 3 is passivated with an insulating layer 12 such as a thermal oxide film, and the cap 1 is placed on the silicon plate 1 via an adhesive 4.
3 is joined. As described above, the present embodiment is characterized in that the acceleration detecting portion including the movable mass 8, the fixed electrodes 16 and 16a and the beam is formed by the polycrystalline silicon layer provided on the silicon plate 1 without using the SOI substrate. There is.

FIG. 7 shows a plan view of another embodiment of the micro G sensor according to the present invention. A pair of fixed electrodes 25, 25 a is fixed on the thermal oxide film on the silicon plate 1 so as to face the movable mass 22 supported by the two beams 23 having the fixed ends 24. Movable mass 22 and fixed electrodes 25, 25
The acceleration component Gy parallel to the surface of the silicon plate 1 can be detected from the change in the capacitance of the gaps 26, 26a between a. When the acceleration detecting unit 20 is arranged orthogonal to the acceleration detecting unit 21 of the acceleration component Gy, the acceleration detecting unit 20 can detect the acceleration component Gx orthogonal to the acceleration component Gy. As described above, the present embodiment is capable of detecting acceleration components in the biaxial directions parallel to the surface of the silicon plate 1, that is, Gx and Gy. Although each acceleration detection unit shows one movable mass supported by the beam, a plurality of movable masses are arranged in parallel and a pair of fixed electrodes is provided facing each movable mass. May be. In this case, it goes without saying that the greater the number of movable masses, the higher the sensitivity of the acceleration detection unit. The acceleration detection units 20 and 2
If it is manufactured so that the spring constant of the beam supporting one movable mass is different, it is possible to detect accelerations of two or more orthogonal components with different sensitivities, and a micro G suitable for an airbag system.
A sensor can be provided. That is, a single micro G sensor can simultaneously detect a frontal collision and a side collision of an automobile with different sensitivities.

A plan view of another embodiment of the micro G sensor according to the present invention is shown in FIG. The fixed electrode is arranged on the silicon plate 1 below the movable mass 8 so as to face the movable mass 8 supported by the four beams 6 having the fixed ends 5.
The acceleration component Gx parallel to the surface of the and the acceleration component Gy orthogonal to the acceleration component Gx are detected. In this embodiment, similarly to the previous figure, the acceleration component in the biaxial directions parallel to the surface of the silicon plate 1 is detected. The movable mass 8
The slit 27 and the slit 28 are provided in the. Here, since the slit 27 detects the acceleration component Gx,
The slit 28 is provided to detect the acceleration component Gy. C- of the micro G sensor shown in this figure
An example of a C sectional view is shown in FIGS. 9 and 10.

FIG. 9 shows the fixed electrode facing the movable mass 8 as S
This is an example in which the OI substrate is provided on the supporting substrate silicon plate 10. That is, the remaining projections 30 formed by engraving the slits 29 on the silicon substrate 10 for supporting substrate are used as fixed electrodes. As shown in the figure, the slit 29 is not directly under the slit 27 formed in the movable mass 8 and is formed so that the positions of both slits overlap each other by about half. And it is a micro G sensor in which the movable mass 8 and the signal processing circuit section 3 are formed on the element forming silicon plate 1. The gap 31 between the fixed electrode composed of the movable mass 8 and the protrusion 30 is obtained by etching the thermal oxide film 11 as a sacrificial layer, and as a result, the movable mass 8 is parallel to the substrate surface of the silicon plate 10. It can be displaced according to the directional acceleration. Then, the facing area between the movable mass 8 and the protrusion 30 changes according to the magnitude of the acceleration Gx, and the capacitance of the gap 31 changes. Therefore, the magnitude of the acceleration component Gx can be detected by measuring the change in the capacitance with the signal processing circuit 3.

Similarly, FIG. 10 also shows an example in which a fixed electrode facing the movable mass 8 is provided on a silicon substrate 10 for a supporting substrate of an SOI substrate. In the present embodiment, the pn junction isolation region 32 provided on the supporting substrate silicon plate 10 is used as a fixed electrode. The position of the pn junction isolation region 32 and the slit 27 provided in the movable mass 8 are formed so as to overlap each other by about half. The pn junction isolation region 32 is formed by diffusing impurities such as boron into the silicon plate 10 or by ion implantation.

Another embodiment of the CC sectional view of the micro G sensor shown in FIG. 8 is shown in FIGS. The embodiment shown in FIGS. 11 and 12 is different from the embodiment shown in FIGS. 9 and 10 in the following points. That is, the movable mass 8 is formed of polycrystalline silicon formed on the surface of the silicon plate 1 without using the SOI substrate, and the protrusions 30 and the pn junction isolation regions 32 serving as fixed electrodes are formed on the silicon plate 1. different.

A plan view of another embodiment of the micro G sensor according to the present invention is shown in FIG. In this figure, a cap is bonded to the silicon plate 1 with an adhesive 4 so that only the acceleration detection unit 2 is arranged in the airtight space. Again,
After forming a large number of micro G sensors on a silicon wafer, even if dicing is performed on the sensing device of each micro G sensor with a dicer, dust may enter the voids,
Problems such as the beam supporting the movable mass being broken can be solved.

FIG. 14 shows a sectional view of another embodiment of the micro G sensor according to the present invention. The previous figure shows the silicon plate 1 of this figure.
2 is a plan view of the micro G sensor at the position D-D in the previous figure. A cap 13 made of a silicon plate is bonded onto the silicon plate 1 via an adhesive material 4. As described above, the insert material made of the Ag thin film is used as the adhesive material 4.

A cross-sectional view of another embodiment of the micro G sensor according to the present invention is shown in FIG. This figure shows position D-D in FIG.
3 is a cross-sectional view of the micro G sensor in FIG. If a polycrystalline silicon thin film formed on the insulating layer 12 such as a thermal oxide film is used as the adhesive layer 34, the acceleration detecting unit 2 is arranged in the airtight space by the well-known anodic bonding with the cap 33 made of glass. be able to. Pad 9,
They may be arranged on both sides of the silicon plate 1 as shown by 9a. Further, a glass material having a low melting point may be used for the adhesive layer 34. Needless to say, glass can be used as the cap material even when both the signal processing circuit unit and the acceleration detection unit are arranged in the airtight space.

FIG. 16 shows a method of mounting the micro G sensor according to the present invention. This figure shows a method of surface mounting the micro G sensor 38 on the module substrate 37 of various systems. Pads 9 and 9a of the micro G sensor 38
And conductor portions 36, 3 formed on the surface of the module substrate 37
6a is joined with ball-shaped solder 35, 35a. As described above, since the acceleration detection unit has the airtight structure, the micro G sensor can be directly surface-mounted on the module substrates of various systems. Further, it becomes unnecessary to hermetically seal a metal can package or a ceramic package, which can contribute to the cost reduction of the micro G sensor.

Another embodiment of the micro G sensor according to the present invention is shown in FIG. In the acceleration detection unit 2 of this figure, only the portion excluding the movable mass supported by the beam is shown.
That is, the fixed electrode 39 for detecting the acceleration component Gx and the fixed electrode 40 for detecting the acceleration component Gy are formed on the surface of the silicon plate 1 in the pn junction isolation region, and the fixed electrode 39 is formed.
It is electrically connected to. Although not shown in the figure, a movable mass supported by a beam via a gap is formed on the fixed electrodes 39 and 40. In this case, it is not necessary to dispose the fixed electrodes 25 and 25a as shown in FIG. 7 on both sides of the movable mass 22.

Another embodiment of the micro G sensor according to the present invention is shown in FIG. This figure schematically shows a plan view of the silicon plate 1 of the micro G sensor shown in FIGS. 8 and 12. Similar to the previous figure, the acceleration detection unit 2 shows only the portion excluding the movable mass supported by the beam. That is, a fixed electrode 41 for detecting the acceleration component Gx and a fixed electrode 42 for detecting the acceleration component Gy are formed on the surface of the silicon plate 1 in a pn junction isolation region and electrically connected to the signal processing circuit section 3. Is. Although not shown in the figure,
On the fixed electrodes 41 and 42, a movable mass supported by a beam via a gap is constructed as shown in FIG.

Another embodiment of the micro G sensor according to the present invention is shown in FIG. This figure shows a three-dimensional micro G sensor capable of detecting acceleration components Gx, Gy, Gz in the directions of three axes orthogonal to each other. Movable mass 4 for detecting acceleration components Gx and Gy in a direction parallel to the surface of the silicon plate 1.
3 and the acceleration component Gz in the direction perpendicular to the surface of the silicon plate 1.
The movable mass 44 for detecting the acceleration is arranged in the acceleration detection unit 2. Although the fixed electrodes facing each other with a gap in the movable masses 43 and 44 are not shown in the figure, the movable masses 4 and
It is formed on the surface of the silicon plate 1 below 3 and 44 in the form of a pn junction isolation region.

FIG. 20 shows the cross-sectional shape of the beam supporting the movable mass of the three-dimensional micro G sensor of the previous figure. FIG.
20A is a sectional shape of the beam 6a supporting the movable mass 43, and FIG. 20B is a beam 6b supporting the movable mass 44.
The cross-sectional shape of is shown. The beams 6a and 6b are formed by etching the thermal oxide film 12 with a sacrifice layer, with a gap on the surface of the silicon plate 1 excluding the fixed ends of the beams, as shown in the figure. The beam 6a has a thickness that is at least several times thicker than its width, and the beam 6b has a width that is at least several times thicker than its thickness. As a result, the beam 6a and the movable mass 43 can move in the direction parallel to the surface of the silicon plate 1, but cannot move in the direction perpendicular to the surface of the silicon plate 1. vice versa,
The beam 6b and the movable mass 44 can move in a direction perpendicular to the surface of the silicon plate 1, but cannot move in a direction parallel to the surface of the silicon plate 1.

FIG. 21 shows a schematic manufacturing process of the micro G sensor according to the present invention. FIG. 21A shows a method of starting from an SOI substrate or a simple silicon substrate. First, a signal processing circuit portion is manufactured by a well-known semiconductor integrated circuit process, and then a sacrifice layer such as a dry etching of a silicon plate or a thermal oxide film. The acceleration detection part is formed by making full use of etching.
Then, after electrically connecting the circuit unit and the detection unit, a cap is bonded to the upper portion of the silicon plate so that at least the acceleration detection unit can be sealed in the airtight space. Next, a silicon wafer having a large number of micro G sensors formed therein is diced into each micro G sensor using a dicer or the like. Then, after the micro G sensor is incorporated into an appropriate substrate or package according to the intended use, the sensitivity and offset are adjusted to complete the process. FIG. 21B shows a method of starting from an SOI substrate having a void portion. In this case, an acceleration detecting portion can be manufactured without performing sacrifice layer etching.
An SOI substrate having a void is obtained by directly bonding a silicon plate for a support substrate and a silicon plate for forming an element, which have no thermal oxide film, in advance to a portion to be the void.

[0029]

Since the acceleration detecting portion has an airtight structure, it is possible to obtain an integrated micro G sensor which is low in cost and excellent in mass productivity and reliability. Further, a micro G sensor capable of simultaneously detecting accelerations of two or more orthogonal components can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a plan view of an embodiment of an acceleration sensor (micro G sensor) according to the present invention.

FIG. 2 is a diagram showing a cross-sectional view of the previous embodiment.

FIG. 3 is a diagram showing a plan view of another embodiment of the micro G sensor according to the present invention.

FIG. 4 is a diagram showing a cross-sectional view of the previous embodiment.

FIG. 5 is a diagram showing a cross-sectional view of another embodiment of the micro G sensor according to the present invention.

FIG. 6 is a diagram showing a cross-sectional view of another embodiment of the micro G sensor according to the present invention.

FIG. 7 is a diagram showing a plan view of another embodiment of the micro G sensor according to the present invention.

FIG. 8 is a diagram showing a plan view of another embodiment of the micro G sensor according to the present invention.

FIG. 9 is a diagram showing a cross-sectional view of another embodiment of the micro G sensor according to the present invention.

FIG. 10 is a diagram showing a cross-sectional view of another embodiment of the micro G sensor according to the present invention.

FIG. 11 is a diagram showing a cross-sectional view of another embodiment of the micro G sensor according to the present invention.

FIG. 12 is a diagram showing a cross-sectional view of another embodiment of the micro G sensor according to the present invention.

FIG. 13 is a diagram showing a plan view of another embodiment of the micro G sensor according to the present invention.

FIG. 14 is a diagram showing a cross-sectional view of the previous embodiment.

FIG. 15 is a diagram showing a cross-sectional view of another embodiment of the micro G sensor according to the present invention.

FIG. 16 is a diagram showing a mounting method of a micro G sensor according to the present invention.

FIG. 17 is a diagram showing a plan view of another embodiment of the micro G sensor according to the present invention.

FIG. 18 is a diagram showing the shape of a fixed electrode portion of the micro G sensor shown in FIGS. 8 and 12.

FIG. 19 is a diagram showing a plan view of a three-dimensional micro G sensor according to the present invention.

FIG. 20 is a diagram showing a beam shape of a three-dimensional micro G sensor according to the present invention.

FIG. 21 is a diagram showing a schematic manufacturing process of the micro G sensor according to the present invention.

[Explanation of symbols]

1 ... Silicon plate, 2, 20, 21 ... Acceleration detector, 3 ...
Signal processing circuit section, 4 ... Adhesive material, 5, 24 ... Fixed end, 6,
6a, 6b, 23 ... Beam, 7, 27, 28, 29 ... Slit, 8, 22, 43, 44 ... Movable mass, 9, 9a ...
Pads, 10 ... Silicon plate for supporting substrate, 11 ... Thermal oxide film, 12 ... Insulating layer such as thermal oxide film, 13, 33 ... Cap, 14, 15, 17, 17a, 19, 19a, 26,
26a, 31 ... Voids, 16, 16a, 18, 18a, 2
5, 25a, 39, 40, 41, 42 ... Fixed electrode, 30
... protrusions, 32 ... pn junction isolation region, 34 ... adhesive layer, 3
5, 35a ... Solder, 36, 36a ... Conductor part, 37 ... Module substrate, 38 ... Micro G sensor, 43 ... Space.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Satoshi Shimada, Satoshi Shimada, 7-1, 1-1 Omika-cho, Hitachi-shi, Ibaraki Hitachi, Ltd. Hitachi Research Laboratory (72) Inventor, Hitoshi Onuki 7-chome, Omika-cho, Hitachi-shi, Ibaraki No. 1 Incorporated company Hitachi, Ltd., Hitachi Research Laboratory (72) Inventor, Akira Koide, 502, Jinritsucho, Tsuchiura City, Ibaraki Prefecture, Ltd., Institute of Mechanical Research, Hiritsu Manufacturing Co., Ltd. (72) Inventor, Yasuhiro Mochizuki, 7-chome, Omikacho, Hitachi City, Ibaraki Prefecture No. 1 Hitachi Ltd. Hitachi Research Laboratory (72) Inventor Norio Ichikawa 2477 Takaba, Hitachinaka City, Ibaraki Prefecture Hitachi Car Engineering Ltd. (72) Inventor Junichi Horie 2520 Takaba, Hitachinaka City, Ibaraki Prefecture (72) Inventor Terumi Nakazawa Hitachi Ltd., Hitachi, Ltd. 2520 Address Company Hitachi Automotive Systems Division (72) Inventor Masanori Kubota 2477 Takaba, Hitachinaka City, Ibaraki Prefecture Hitachi Car Engineering Co., Ltd. (72) Keiji Hanzawa 2477 Takaba, Hitachinaka City, Ibaraki Prefecture Stock Association Inside Hitachi Car Engineering

Claims (22)

[Claims] 1. A movable mass body which is supported by a support body and has a function of a movable electrode, an acceleration detection section which is composed of a fixed electrode which is arranged so as to face the movable mass body, and the movable body which is displaced in accordance with acceleration. A signal processing circuit unit for converting movement of a mass body into an acceleration signal, and an acceleration sensor integrated on a semiconductor substrate, wherein at least the acceleration detection unit is placed in an airtight space by a covering material bonded onto the semiconductor substrate. An acceleration sensor characterized by being arranged. 2. The semiconductor substrate according to claim 1, wherein the semiconductor substrate is formed by laminating an element forming silicon plate and a supporting substrate silicon plate.
An acceleration sensor comprising an OI group, wherein the movable mass body supported by the support body on the element forming silicon plate is integrated together with the signal processing circuit. 3. The acceleration sensor according to claim 1, wherein the support and the movable mass body are formed from polycrystalline silicon film formed on a surface of the semiconductor substrate on which a signal processing circuit is formed. 4. The fixed electrode facing the movable mass body supported by the support according to claim 2, wherein the fixed electrode is a silicon plate for element formation of an SOI substrate, a silicon plate for a support substrate of an SOI substrate, or a silicon plate. An acceleration sensor characterized by being formed of polycrystalline silicon formed on the surface, a silicon plate having a circuit formed thereon, or the above-mentioned coating material bonded onto the silicon plate. 5. The fixed electrode according to claim 1 or 2, wherein the fixed electrode facing the movable mass body overlaps the semiconductor substrate under the movable mass body with a part of the movable mass body and the fixed electrode. An acceleration sensor characterized by being formed. 6. An acceleration sensor according to claim 1, wherein a fixed electrode is provided facing the movable mass body so that accelerations of two orthogonal components can be detected. 7. The acceleration sensor according to claim 6, wherein the movable mass body supported by the support body is at least one or more. 8. The acceleration sensor according to claim 6, wherein the fixed electrode comprises a protrusion obtained by finely processing the semiconductor substrate or a pn junction isolation region formed on the semiconductor substrate. 9. The acceleration according to claim 6, wherein terminals are formed on the semiconductor substrate on which the signal processing circuit section is formed so that the module substrate can be directly surface-mounted by means of solder or the like. Sensor. 10. The SO according to claim 1, wherein a space between the movable mass body and the fixed electrode is formed in advance.
An acceleration sensor characterized by processing an acceleration detection unit using an I substrate. 11. A movable mass body, which is supported by a support body and has a function of a movable electrode, an acceleration detection section composed of a fixed electrode which is arranged so as to face the movable mass body, and the movable body which is displaced in accordance with acceleration. In an acceleration sensor in which a signal processing circuit unit that converts the movement of a mass body into an acceleration signal is integrated on a semiconductor substrate, at least two or more movable mass bodies are provided, and one movable mass body is provided on the surface of the semiconductor substrate. An acceleration sensor, wherein another movable mass body can be displaced according to an acceleration parallel to a surface direction of a semiconductor substrate according to an acceleration in a vertical direction. 12. The acceleration sensor according to claim 11, which is capable of detecting acceleration in a three-dimensional direction. 13. The surface of the semiconductor substrate according to claim 11, wherein the thickness of the support for supporting the movable mass body that is displaced according to the acceleration in the direction perpendicular to the surface of the semiconductor substrate is smaller than the width thereof. An acceleration sensor, characterized in that a thickness of a support body that supports a movable mass body that is displaced according to an acceleration parallel to a direction is larger than its width. 14. An acceleration sensor according to claim 11, wherein at least the acceleration detecting portion is arranged in an airtight space by a covering material bonded on the semiconductor substrate. 15. A movable mass body, which is supported by a support body and has a function of a movable electrode, an acceleration detection section composed of a fixed electrode arranged to face the movable mass body, and the movable body which is displaced in accordance with acceleration. In an acceleration sensor in which a signal processing circuit unit that converts the movement of a mass body into an acceleration signal is integrated on a semiconductor substrate, the fixed electrode facing the movable mass body is connected to the semiconductor substrate below the movable mass body, An acceleration sensor, wherein a movable mass body and a part of the fixed electrode are formed to overlap each other. 16. The acceleration sensor according to claim 15, wherein a fixed electrode is provided facing the movable mass body so as to detect accelerations of two orthogonal components. 17. The acceleration sensor according to claim 16, wherein the movable mass body supported by the support body is at least one or more. 18. The acceleration sensor according to claim 15, wherein the fixed electrode comprises a protrusion obtained by finely processing a semiconductor substrate or a pn junction isolation region formed on the semiconductor substrate. 19. The cap according to claim 1, wherein the cap is Ag or A.
An acceleration sensor characterized by being joined by an insert material made of a metal thin film such as u. 20. A movable mass body, which is supported by a support body and has a function of a movable electrode, an acceleration detection section made up of a fixed electrode arranged so as to face the movable mass body, and the movable body which is displaced in accordance with acceleration. An acceleration sensor in which a signal processing circuit unit for converting movement of a mass body into an acceleration signal is integrally integrated on a semiconductor substrate, the acceleration sensor being capable of detecting acceleration of at least two orthogonal components. 21. The acceleration sensor according to claim 20, which is capable of detecting accelerations of two or more orthogonal components with different sensitivities. 22. At least two sets of the movable mass body and the support body supporting the movable mass body are provided, and the spring constant of the support body is set so that accelerations of two or more orthogonal components can be detected with different sensitivities. Acceleration sensor characterized by being different.