JPH06347475A - Acceleration sensor and manufacturing method thereof - Google Patents

Abstract

(57) [Abstract] [Purpose] Prevents dust from entering the fixed and movable parts that make up the acceleration sensor, extending the sensor life, and making the electrical connection to the signal processing circuit lineless. To detect accurately. When the mass portion 37 is displaced due to acceleration, the distance between the movable side comb-shaped electrode 38 electrode plate 38A and the fixed side comb-shaped electrode 33 electrode plate 33A is displaced, and this displacement is detected as a capacitance. Then, the fixed portion 32 and the movable portion 34
By covering and with the cover 39, it is possible to prevent dust, chips, water, and the like from entering and entering the fixed portion 32 and the movable portion 34. In addition, the capacitance is led out of the cover 39 via each extraction electrode 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acceleration sensor which is preferably used for detecting acceleration of a vehicle or the like and a method for manufacturing the same, and more particularly, an acceleration sensor which can improve the yield at the time of manufacturing and a method for manufacturing the same. Regarding

[0002]

2. Description of the Related Art Generally, an acceleration sensor used to detect the acceleration and the rotation direction of a vehicle or the like is one which detects it by utilizing the electrostatic capacitance between electrode plates.
No. 169 and Japanese Patent Laid-Open No. 232171/1987.

However, in these acceleration sensors, since the effective area between the electrodes of the fixed portion and the movable portion is small and the distance between them is large, the detection sensitivity is low and it is not possible to perform highly accurate acceleration detection. .

On the other hand, for example, in the acceleration sensor described in Japanese Patent Application Laid-Open No. 4-115165 (hereinafter referred to as "other prior art"), comb-shaped electrodes are used for the fixed electrode and the movable electrode to increase the effective area between the electrodes. The detection sensitivity is improved.

Another conventional acceleration sensor is a cantilever having one end fixed to a base and the other end serving as a weight capable of horizontally vibrating, and a movable side integrally formed with the cantilever. A comb-teeth-shaped electrode portion and a comb-teeth-shaped electrode portion on the fixed side, which is meshed with the comb-teeth-shaped electrode portion on the movable side in a non-contact manner, and includes a comb-teeth fixed plate fixed to the base. ing. Then, when acceleration is applied to the weight, the capacitance between the movable comb-teeth electrode portion and the fixed side comb-teeth electrode portion changes, so this change is detected as an electrostatic capacitance, and according to the acceleration. To obtain a detected signal.

[0006] However, in the other conventional techniques, when each comb-toothed electrode portion is formed by utilizing the silicon etching processing technique, the etching process is performed only from one side surface of the silicon, so that each etching is performed. If the surface is tilted and the distance between the electrode portions is reduced, the electrode portions may come into contact with the other side surface portion of silicon, and the distance between the electrode portions cannot be reduced.

That is, a silicon wafer having a thickness of several hundreds of μm is normally used, and if this thickness is used as it is as the thickness dimension of each electrode portion, the etching surface is inclined and the separation dimension is reduced for the above reason. Becomes difficult. On the other hand, it is conceivable to use a silicon wafer having a thickness of about several tens of μm from the beginning, but in this case, the strength of the silicon wafer becomes weak and it is damaged during transportation.

Therefore, in order to solve the above-mentioned problems of the prior art, the present inventor previously examined an acceleration sensor and a method of manufacturing the same as shown in FIGS.
"Prior art").

That is, in FIGS. 21 and 22, 1 is an acceleration sensor, 2 is a glass substrate as an insulating substrate constituting the acceleration sensor 1, and fixed parts 3, 3 and a movable part which will be described later are provided on the glass substrate 2. The part 5 is formed. Further, a rectangular concave groove 2A is formed in the glass substrate 2, and the mass portion 8 of the movable portion 5 and the movable comb-shaped electrode 9 located on the concave groove 2A are in the arrow A direction in which acceleration is applied. It can be displaced.

Reference numerals 3 and 3 denote a pair of fixing portions made of a low-resistance silicon material. The fixing portions 3 are located on the left and right sides of the glass substrate 2, and a plurality of fixing portions are provided on the inner surfaces facing each other. (For example, 5) thin plate-like electrode plates 4A, 4A, ...
Are formed in a protruding manner, and each of the electrode plates 4A constitutes fixed-side comb-shaped electrodes 4 and 4 as fixed electrodes.

Reference numeral 5 denotes a movable portion formed of a low resistance silicon material, and the movable portion 5 is separated from the front and rear of the glass substrate 2 by a supporting portion 6 fixed to the glass substrate 2.
6, a mass portion 8 supported by each of the supporting portions 6 via beams 7, 7 and arranged between the fixing portions 3 and formed to project from the mass portion 8 in the left and right directions, respectively. Multiple (eg 5
And the movable side comb-shaped electrodes 9 and 9 having thin plate-shaped electrode plates 9A, 9A ,.
Is formed in a thin plate shape so as to be displaced in the direction of arrow A. Then, each electrode plate 9A of each movable side comb-shaped electrode 9
Are arranged so as to face each electrode plate 4A of each fixed-side comb-shaped electrode 4 with a minute gap therebetween.

Further, 10, 10, ... Are the glass substrates 2
The extraction electrode formed above is shown, and each extraction electrode 10 is shown.
The signal processing circuit 25, which will be described later, is connected to each fixed portion 3 and each supporting portion 6 of the movable portion 5 on the proximal end side thereof, and the distal end side to the outside.
The electrode pad 10A is connected to.

23 to 27, a method of manufacturing the acceleration sensor 1 according to the prior art will be described.

First, in FIG. 23, reference numeral 11 denotes a silicon wafer as a silicon plate.
Is, for example, 7.5 to 15.5 (cm) in diameter and 300 μm in thickness
It is formed in a disk shape of about m.

Reference numeral 12 denotes a glass substrate as an insulating substrate, and the glass substrate 12 is formed in a disk shape having the same size as the silicon wafer 11.

Next, in the first etching step shown in FIG. 24, a groove 13 having a predetermined depth for separately forming the fixed portion 3 and the movable portion 5 is formed on one side surface of the silicon wafer 11. To this end, RIE (reactive ion etching) as dry etching or anisotropic etching using an alkaline aqueous solution as wet etching is performed from one side surface for a predetermined time.

On the other hand, the other side of the glass substrate 12 facing the one side of the silicon wafer 11 is subjected to glass etching (glass etching step) to form a rectangular groove 12A (2A) as shown in FIG. While being formed, extraction electrodes 10, 10, ... Are formed on the other side surface.

Next, in the bonding step shown in FIG. 25, one side surface of the silicon wafer 11 having the groove 13 formed in the first etching step and the glass substrate 12 having the groove 12A formed therein.
The silicon wafer 11 and the glass substrate 12 are integrated with each other by anodic bonding to the other side surface.

Furthermore, in the second etching step shown in FIG. 26, the thickness of the silicon wafer 11 is reduced.
By performing RIE or wet etching from the other side surface of the silicon wafer 11 and etching until the groove 13 penetrates (that is, the silicon wafer 11 is melted and removed from one side surface to the level of the groove 13).
A plurality of fixed portions 3 and movable portions 5 which will be the acceleration sensor 1 are separately formed on the glass substrate 12 (see FIG. 28). In addition,
In the separately formed movable portion 5, only the supporting portions 6 and 6 are fixed on the glass substrate 12, and the beams 7 and 7, the mass portion 8 and the movable side comb-shaped electrodes 9 and 9 are located on the concave groove 12A. However, the mass portion 8 and the like are movable by the beams 7 in the arrow A direction.

Then, in the cutting step shown in FIG. 27, each acceleration sensor 1 consisting of a plurality of sets of a fixed part 3 and a movable part 5 formed on the glass substrate 12 by a dicing device is cut into chips (about 5 mm square). Then, the plurality of acceleration sensors 1 are manufactured by cutting the glass substrate 12 shown in FIG.

In the acceleration sensor 1 of the prior art constructed as described above, when the acceleration in the direction of the arrow A is applied from the outside, the mass portion 8 is displaced with respect to each support portion 6 via each beam 7 and the movable side. Each electrode plate 9A of the comb-shaped electrode 9 approaches or separates from each electrode plate 4A of the fixed-side comb-shaped electrode 4. At this time,
The displacement of the distance between the electrode plates 4A and 9A is output to the external signal processing circuit 25 as a change in capacitance, and the signal processing circuit 25 outputs a voltage based on the change in capacitance.

In this acceleration sensor 1, the movable side comb-shaped electrode 9 and the fixed side comb-shaped electrode 4 are provided on the respective electrode plates 9A,
Acceleration is detected as a change in capacitance between 4A, and the electrode plates 9A and 4A are electrically connected in parallel. Therefore, the capacitance detected by the acceleration sensor 1 is equal to each electrode plate. It becomes a value obtained by adding the electrostatic capacities between 9A and 4A respectively, so that the detection sensitivity of the acceleration sensor 1 can be increased and the acceleration detection accuracy can be improved.

In the method of manufacturing the acceleration sensor 1 according to the prior art, for example, the fixed portion 3 and the movable portion 5 are formed by thinning the silicon wafer 11 having a thickness of 300 μm to several tens of μm in the second etching step. The groove 13 formed separately and formed in the first etching step
The thickness dimension of the fixed portion 3, the movable portion 5, etc. is determined based on the depth dimension of the. Therefore, by adjusting the depth of the groove 13, the effective area of each electrode plate 4A, 9A can be adjusted. Further, since the one side surface and the both side surfaces of the other side surface of the silicon wafer 11 are etched in the first and second etching steps, respectively, the thickness of the silicon wafer 11 can be reduced on the glass substrate 12, The distance between the electrode plates 4A and 9A of the comb-shaped electrodes 4 and 9 can be secured as a minute gap.

Next, the case where the acceleration sensor 1 is packaged will be described with reference to FIG.

In FIG. 29, reference numeral 21 denotes a casing for an acceleration sensor, and the casing 21 has a stem 22 formed of a metal material in a disk shape or a square shape, and a cylindrical metal material with a lid for covering the stem 22. And the insulating substrate 24 formed of glass epoxy or the like provided on the upper surface of the stem 22.
Terminal pins 22A, 22A, ... Are formed so as to protrude downward through insulating materials 22B, 22B ,. The size of the acceleration sensor casing 21 is considerably larger than the size of the circuit element and the sensor element.

Reference numeral 25 denotes a signal processing circuit provided on the stem 22, and the input side of the signal processing circuit 25 is a wire 26 formed by wire bonding to the acceleration sensor 1
Connected to the terminal pin 22 by a wire 27 on the output side.
It is connected to A.

By packaging the acceleration sensor 1 in this way, the signal processing circuit 25 can convert a change in capacitance with respect to the acceleration from the acceleration sensor 1 into a voltage change and output the voltage change.

[0028]

By the way, in the above-described prior art, in the final cutting step shown in FIG. 27, since each fixed part 3 and movable part 5 are opened to the upper side, the cutting generated during the cutting work is performed. Debris and the like enter between the electrode plates 4A of the fixed-side comb-shaped electrode 4 and the electrode plates 9A of the movable-side comb-shaped electrode 9 and mechanically stop operating, or the electrode plates 4
There is a problem that the A and 9A are electrically contacted with each other to cause malfunction of the acceleration sensor 1.

Moisture in the etching step and the cutting step infiltrates between the electrode plates 4A and 9A of the acceleration sensor 1 and between the electrodes 4 and 9 and the glass substrate 2 and the surface tension causes the electrode plate 4A and the electrode plate 4A. 9A and the electrodes 4, 9 and the glass substrate 2 may be dried and adhered in a state where they are close to each other. As a result, the mass part 8 of the movable part 5 cannot be moved and cannot be used as a product, so it must be discarded, and there is a problem that the yield in manufacturing the acceleration sensor 1 is reduced and the productivity is reduced.

Further, when packaged as shown in FIG. 29, since the acceleration sensor 1 and the signal processing circuit 25 are connected by the wire 26, the wire 26
Causes a stray capacitance due to vibration, and this stray capacitance is added to the electrostatic capacitance detected by the acceleration sensor 1. As a result,
Since a signal with noise is input to the signal processing circuit 25, there is a problem that accurate acceleration cannot be detected.

The present invention has been made in view of the above-mentioned problems of the prior art. For example, the yield when manufacturing an acceleration sensor from a silicon wafer can be improved, productivity is significantly increased, and the capacitance from the acceleration sensor is increased. It is an object of the present invention to provide an acceleration sensor capable of detecting stray acceleration by preventing stray capacitance from being applied to the sensor and a manufacturing method thereof.

[0032]

In order to solve the above-mentioned problems, an acceleration sensor according to a first aspect of the present invention provides an insulating substrate and an insulating substrate which are provided on the insulating substrate and which are formed by etching a silicon plate. A fixed part and a movable part that are formed separately are provided, and a fixed electrode is integrally formed on the fixed part, and the movable part is a supporting part fixed on an insulating substrate and the supporting part through a beam. Is provided so as to be opposed to each other through a minute gap between a mass part that is connected to the mass part and is displaced according to the acceleration when an acceleration acts on the mass part, and a fixed electrode formed on the mass part on the fixed part. And a movable electrode that is close to and separate from each other by the displacement of the mass part, and is integrally formed. The insulating substrate covers the periphery of the fixed part and the movable part. The ring provided on the insulating substrate as A peripheral wall, lies in the formation of the cover consisting of a cover portion covering the opening portion of the peripheral wall.

In this case, it is preferable that the cover has a peripheral wall and a lid integrally formed from the same member.

Further, in this case, it is preferable that the cover has a peripheral wall formed of a silicon plate, a lid portion formed of an insulating plate, and the peripheral wall and the lid portion joined together.

Further, it is preferable that the fixed electrode and the movable electrode are comb-like electrodes provided so as to project from the fixed portion and the mass portion, respectively.

Further, it is desirable that the cover is made of a silicon plate, and that the silicon plate is provided with a signal processing circuit for converting a change in electrostatic capacitance generated between the movable electrode and the fixed electrode into a voltage.

On the other hand, in the method of manufacturing an acceleration sensor according to a sixth aspect of the present invention, the silicon plate is etched from one side surface to form a groove for separating the fixed portion and the movable portion on the one side surface. A first etching step, a first joining step of joining one side surface of the silicon plate to an insulating substrate after forming the groove in the silicon plate, and a state of joining the silicon plate to the insulating substrate. A second etching step in which a fixed portion and a movable portion are separately formed on the silicon plate by performing an etching process from the other side surface of the silicon plate, and the fixed portion and the movable portion formed on the silicon plate. The second bonding step of bonding the covering cover onto the insulating substrate.

In this case, it is preferable that lead electrodes connected to the fixed portion and the movable portion are formed on the insulating substrate before the first joining step.

Further, in this case, the cover for covering the fixed portion and the movable portion formed in the second etching step may be formed by forming a recess in the insulating plate before the second joining step. desirable.

On the other hand, in the method of manufacturing an acceleration sensor according to a ninth aspect of the present invention, the silicon plate is etched from one side to form a groove for separating the fixed part, the movable part and the peripheral wall of the cover from the one side of the silicon plate. A first etching step of forming a side surface, and a first step of forming one side surface of the silicon plate on an insulating substrate after forming the groove in the silicon plate
Bonding step, a masking step of masking the portion of the silicon plate bonded to the insulating substrate from the other side surface of the silicon plate to the peripheral wall of the cover, and an etching treatment from the other side surface of the silicon plate, Secondly, the fixed part, the movable part and the peripheral wall of the cover are formed separately on the silicon plate.
And the second joining step of joining an insulating plate that covers the peripheral wall so as to cover a plurality of sets of fixed portions and movable portions formed on the silicon plate.

Before the first bonding step, it is desirable that lead electrodes connected to the fixed portion and the movable portion are formed on the insulating substrate.

[0042]

According to the above structure, when acceleration is applied, the mass portion of the movable portion is displaced against the beam, and this displacement displaces the distance between the movable electrode and the fixed electrode. Then, this change in the separation dimension can be detected as a change in capacitance. The acceleration sensor according to claim 1 of the present invention is
Since the fixed part and the movable part are covered with a cover,
It is possible to prevent dust and the like from entering from the outside.

By forming the movable electrode of the movable portion and the fixed electrode of the fixed portion as comb-shaped electrodes,
The effective area between the electrodes can be increased, and the respective electrode plates can be opposed to each other through a minute gap.

Further, by forming the cover from a silicon plate and providing the signal processing circuit on the cover, the acceleration sensor and the signal processing circuit can be electrically connected when the cover is joined to the insulating substrate. .

On the other hand, in the method of manufacturing an acceleration sensor according to the sixth aspect, the cover provided on the insulating substrate can be integrally formed of an insulating plate.

Further, in this case, since the extraction electrode connected to the fixed portion and the movable portion of the acceleration sensor is formed on the insulating substrate, the acceleration sensor and the signal processing circuit can be easily electrically connected. .

Further, in the method of manufacturing an acceleration sensor according to claim 9, the cover provided on the insulating substrate has a peripheral wall of the cover formed of a silicon plate and a lid portion formed of an insulating plate, and the peripheral wall and the lid portion. Can be formed by joining in the second joining step.

Since the cover formed on the insulating substrate by these manufacturing steps is provided so as to cover the fixed portion and the movable portion, chips are produced during the final cutting step when manufacturing a plurality of pieces at once. It is possible to prevent water and moisture from entering or entering the fixed portion and the movable portion.

[0049]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. In the embodiments, the same components as those of the above-described prior art are designated by the same reference numerals, and the description thereof will be omitted.

First, a first embodiment according to the present invention will be described with reference to FIGS.

In the figure, reference numeral 31 denotes an acceleration sensor according to the present embodiment, which has substantially the same structure as the acceleration sensor 1 according to the prior art and has a fixing portion 32, which will be described later, on a glass substrate 2 serving as an insulating substrate. , 32 and movable part 3
4 and the like are integrally formed.

Reference numerals 32 and 32 denote fixed portions, and each fixed portion 3
Reference numeral 2 has fixed-side comb-shaped electrodes 33, 33 as fixed electrodes, which are formed separately on the left and right sides of the glass substrate 2, and have a plurality of thin plate-shaped electrode plates 33A, 33 on the inner surfaces facing each other.
A, ... are projected.

Reference numeral 34 designates a movable portion, which is a support portion 35 which is arranged in front of and behind the glass substrate 2 so as to be separated from each other.
35, a mass portion 37 supported by the supporting portions 35 via beams 36, 36, and arranged between the fixing portions 32, and a thin plate protruding from the mass portion 37 in the left and right directions. Side comb-shaped electrode 3 having electrode plates 38A, 38A, ...
8 and 38 are integrally formed.

Reference numeral 39 denotes a cover of this embodiment, which is located on the glass substrate 2 and has a rectangular tubular shape made of a glass material so as to surround the fixed portion 32 and the movable portion 34 from the periphery. Peripheral wall 39A formed on the peripheral wall and the peripheral wall 3
It is composed of a lid portion 39B that covers the opening portion of 9A.

Further, the glass substrate 2 is formed with the recessed groove 2A and the extraction electrodes 10, 10, ... And the base end side of each extraction electrode 10 has the fixed portion 32 and the movable portion 34. The electrode pad 10A is connected to each of the support portions 35, and the tip side thereof is connected to the outside.

The acceleration sensor 31 of this embodiment has the above-mentioned structure. Next, a method of manufacturing the acceleration sensor 31 will be described with reference to FIGS.

First, in FIG. 3, 41 indicates a silicon wafer as a silicon plate on which the fixed portion 32 and the movable portion 34 are formed, and 42 indicates a glass plate as an insulating plate on which the cover 39 is formed. Further, the glass substrate 12 described in the prior art is used as the insulating substrate.

Next, in the first etching step shown in FIG. 4, one side surface of the silicon wafer 41 is subjected to RIE or anisotropic etching for a predetermined time. A groove 43 having a predetermined depth is formed to separate and form the fixed portion 32 and the movable portion 34.

On the other hand, a rectangular groove 12A (2A) is formed by glass etching on the other side of the glass substrate 12 facing the one side of the silicon wafer 41, and the other side of FIG. Extraction electrode 1 as shown in
0, 10, ... Are formed.

Further, a concave portion 44 to be the cover 39 is formed on one side surface of the glass plate 42 by glass etching.

Next, in the first bonding step shown in FIG. 5 and the second etching step shown in FIG. 6, as in the bonding step and the second etching step of the prior art, one side surface of the silicon wafer 41 and the glass are bonded. After anodic bonding with the other side surface of the substrate 12, RIE or anisotropic etching is performed from the other side surface of the silicon wafer 41 to reduce the thickness of the silicon wafer 41, and etching is performed until the groove 43 penetrates. I do. As a result, a plurality of sets of fixed portions 32 and movable portions 34 are separately formed on the glass substrate 12.

Further, in the second joining step shown in FIG. 7, each concave portion 44 of the glass plate 42 has a plurality of sets of fixing portions 32.
The other side surface of the glass substrate 12 and one side surface of the glass plate 42 are anodically bonded so as to cover the movable portion 34 and the movable portion 34, respectively, and are integrally formed.

Then, in the final cutting step, cutting is performed by the dicing device at cutting positions 45 and 46 shown by dotted lines in FIG. That is, first, the glass plate 42 is cut along the cutting positions 45, 45, ...
A plurality of sets of fixing portions 32 formed on the glass substrate 12 by cutting along the cutting positions 46, 46, ...
As shown in FIG. 8, each acceleration sensor 31 including the movable portion 34 and the movable portion 34 is cut into chips (about 5 mm square).
At this time, the recess 44 of the glass plate 42 serves as the cover 39, the side surface of the recess 44 serves as the peripheral wall 39A, and the bottom of the recess 44 serves as the lid 39B.

In the acceleration sensor 31 according to the present embodiment having the above-described structure, the movable comb-shaped electrode 38 and the fixed comb-shaped electrode 33 are formed by applying acceleration in the direction of arrow A, as in the prior art. The displacement between the electrode plates 38A and 33A can be detected as a change in capacitance.

Further, the acceleration sensor 31 according to the present embodiment is provided with a cover 39 which is not present in the prior art. As a result, as shown in FIG. 7, each acceleration sensor 31 (fixed portion 32 and movable portion 34) can be individually covered so as to be shielded from the outside before the cutting step, so that the glass plate 42 and the glass can be cut by the cutting step. It is possible to prevent chips generated when the substrate 12 is cut from entering between the fixed portion 32 and the movable portion 34. Furthermore, it is possible to prevent water generated during the cutting step from entering between the plurality of sets of the fixed portion 32 and the movable portion 34 which configure each acceleration sensor 31.

Therefore, the comb-shaped electrode 3 on the fixed side of the fixed portion 32
3 and the movable-side comb-shaped electrode 38 can be prevented from being electrically short-circuited by chips, and the electrode plates 33A and 38A of the electrodes 33 and 38 can be reliably prevented from adhering to each other by moisture. Thereby, the yield in the manufacturing process of the acceleration sensor 31 can be increased, and the productivity of the acceleration sensor 31 can be significantly improved.

On the other hand, each extraction electrode 10 formed on the glass substrate 2 of the acceleration sensor 31 has its base end side connected to each fixed part 32 and each support part 35 of the movable part 34, and the electrode pad on the tip side. 10A is a peripheral wall 39 of the cover 39
Since the glass substrate 2 is extended to the outside of A and the size of the glass substrate 2 is cut in the cutting process so as to be larger than the size of the lid portion 39B of the cover 39, each electrode pad 1
OA is exposed to the upper side as shown in FIG. Therefore, the capacitance detected by the acceleration sensor 31 can be easily taken out by each of the extraction electrodes 10.

Further, the acceleration sensor 31 according to the present embodiment.
In the above, since the fixed portion 32 for detecting the acceleration and the movable portion 34 are covered with the cover 39, it is possible to prevent intrusion of dust and the like from the outside and effectively extend the life of the sensor.

Next, a second embodiment according to the present invention will be described with reference to FIG.
As will be described with reference to FIGS. 17 to 17, the characteristic feature of this embodiment is that the peripheral wall of the cover is formed of a silicon plate, and the lid portion that covers the opening of the peripheral wall is formed of an insulating plate. In this embodiment, the same components as those in the first embodiment described above are designated by the same reference numerals, and the description thereof will be omitted.

In the figure, reference numeral 51 denotes an acceleration sensor according to the present embodiment, which has substantially the same structure as the acceleration sensor 31 according to the first embodiment and is fixed on the glass substrate 2 as an insulating substrate. The parts 32, 32 and the movable part 34 are integrally formed.

Reference numeral 52 denotes a cover of the present embodiment, which is located on the glass substrate 2 and has a rectangular ring shape made of silicon material so as to surround the fixed portion 32 and the movable portion 34 from the periphery. The formed peripheral wall 52A and the peripheral wall 52A
And a lid portion 52B formed in a plate shape by a glass material that covers the opening portion of the.

The acceleration sensor 51 according to this embodiment has the above-mentioned structure. Next, a method of manufacturing the acceleration sensor 51 will be described with reference to FIGS. 11 to 17.

First, in FIG. 11, 61 is a fixing portion 32.
And 62, a silicon wafer as a silicon plate on which the movable part 34 and the movable part 34 are formed, and 62 is a glass plate as an insulating plate serving as the lid part 52B of the cover 52. Further, the glass substrate 12 described in the first embodiment is used as the insulating substrate.

Next, in the first etching step shown in FIG. 12, etching is performed from one side surface of the silicon wafer 61 to form a groove having a predetermined depth for separately forming the fixed portion 32 and the movable portion 34. 63 and a peripheral wall forming groove 64 forming the peripheral wall 52A of the cover 52 are formed so as to cover the groove 63.

On the other hand, in the glass substrate 12, a rectangular concave groove 12A (2A) is formed by performing glass etching from the other side surface of the glass substrate 12, and the extraction electrodes 10 and 10 as shown in FIG. , ... are formed.

Next, in the first joining step shown in FIG.
One side surface of the silicon wafer 61 and the other side surface of the glass substrate 12 are anodically bonded and integrally formed.

Further, in the mask process shown in FIG. 14, the peripheral wall 52 of the cover 52 on the other side surface of the silicon wafer 61.
A mask film 65 of SiN or the like is formed on the portion to be A.

Then, in the next second etching step shown in FIG. 15, etching is performed from the other side surface of the silicon wafer 61 so as to reduce the thickness of the silicon wafer 61. As a result, a plurality of sets of fixed part 32 and movable part 34
And are separately formed on the glass substrate 12, and since the portion of the mask film 65 formed in the mask process is not etched, the peripheral wall 52A of the cover 52 is formed. The peripheral wall 52A of the cover 52 has a fixed portion 32 and a movable portion 3.
It is formed in an annular shape so as to surround 4 and 4. Further, the mask film 65 is removed after the second etching step.

Further, in the second bonding step shown in FIG. 16, the other side surface of the glass plate 62 is anodically bonded so as to cover the opening of the peripheral wall 52A of the cover 52 formed in the second etching step. To do. At this time, the fixed portion 32 and the movable portion 34 of each set are covered with the peripheral wall 52A and the lid portion 52B of the cover 52, respectively.

Then, in the final cutting step, cutting is performed by the dicing device at cutting positions 66 and 67 shown by dotted lines in FIG. That is, first, the glass plate 62 is cut along the cutting positions 66, 66, ...
2 is cut along the cutting positions 67, 67, ... As a result, each acceleration sensor 5 including a plurality of sets of fixed portions 32 and movable portions 34 formed on the glass substrate 12 is formed.
As shown in FIG. 17, 1 is cut into chips (about 5 mm square). At this time, the fixed portion 32 and the movable portion 34 of each set are covered with the cover 52.

Also in the acceleration sensor 51 of the present embodiment constructed as described above, it is possible to obtain the same effects as those of the first embodiment described above.

Next, a third embodiment according to the present invention will be described with reference to FIG.
20 to 25, the features of this embodiment are as follows.
The cover is formed of a high-resistance silicon plate, the signal processing circuit is formed on the silicon plate, and the cover is bonded to the insulating substrate so as to cover the fixed portion and the movable portion which are the detection portions of the acceleration sensor. In this embodiment, the same components as those in the first embodiment described above are designated by the same reference numerals, and the description thereof will be omitted.

In the figure, reference numeral 71 denotes a disc-shaped or square-shaped stem made of a metal material for holding the acceleration sensor 31, and the stem 71 has terminal pins 71A, 71A,
Is a cylindrical insulating material 71 made of a glass material
It is formed so as to protrude downward through B, 71B, ....

Reference numeral 72 denotes an acceleration sensor. The acceleration sensor 72 is manufactured by the manufacturing method described in the first embodiment. The glass substrate 73 is formed from the glass substrate 2 of the first embodiment as shown in FIG. Is also formed in a long rectangular shape. Further, a fixed portion 32 and a movable portion 34 and lead electrodes 10, 10, ... Connected to the fixed portion 32 and the movable portion 34 are formed on one side in the longitudinal direction of the glass substrate 73.

Reference numerals 74 and 74 denote a pair of extraction electrodes formed on the other end side in the longitudinal direction of the glass substrate 73. The extraction electrodes 74 and 74 are extraction electrodes 78 and 78 on the output side of a signal processing circuit 76 described later. And are connected to each other.

Reference numeral 75 denotes a cover formed of a high resistance silicon plate in a rectangular shape shorter than the glass substrate 73, and the fixing portion 32 is provided on one side in the longitudinal direction of the cover 75.
And a concave portion 75A that covers the movable portion 34 and
A signal processing circuit 76 is formed on the other side in the longitudinal direction.
Further, the signal processing circuit 76 is formed by etching processing of semiconductor manufacturing technology and converts the electrostatic capacitance detected by the acceleration sensor 72 into a voltage.
From 6 are formed input side extraction electrodes 77, 77 and output side extraction electrodes 78, 78 extending along the bottom surface of the cover 75. Incidentally, each of the extraction electrodes 10, 74, 7
The portion where 7, 78 and the cover 75 contact each other is insulated by an insulating film.

Since the output side extraction electrode 78 of the signal processing circuit 76 is connected to the terminal pin 71A via the wire 79, the voltage from the signal processing circuit 76 is output to the outside via the terminal pin 71A. It

The acceleration sensor 72 of this embodiment having the above-described structure can be manufactured by the same manufacturing process as that of the first embodiment, and the yield is improved as in the first embodiment. Productivity can be improved.

Further, since the acceleration sensor 72 is provided on the stem 71 so as to be covered with the cover 75, the can 23 as in the prior art can be eliminated and the acceleration sensor 72 can be easily packaged. In addition to being able to carry out, size reduction can be achieved.

Further, by connecting the acceleration sensor 72 and the signal processing circuit 76 with each of the extraction electrodes 10 and 77, wiring by wires can be eliminated, and the stray capacitance is the electrostatic capacitance detected by the acceleration sensor 72. It is possible to detect the accurate acceleration.

The acceleration sensor in the third embodiment may be resin-molded so as to cover the acceleration sensor 72 on the stem 71 and the cover 75.

In each of the above embodiments, the first and second
In the etching process, the above description is made by selecting either dry etching or wet etching, but it is preferable to use dry etching from the viewpoint of processing accuracy, and it is preferable to use wet etching from the viewpoint of cost. .

Further, the acceleration sensor 31 of each of the above-mentioned embodiments.
Describes that the fixed electrode of the fixed portion 32 is the fixed-side comb-shaped electrode 33, the movable electrode of the movable portion 34 is the movable-side comb-shaped electrode 38, and the electrode plates 33A and 38A are opposed to each other through a minute gap. However, the present invention is not limited to this, a general insulating substrate, a movable part having a base end side fixed on the insulating substrate, and a free end side having a mass part to be a movable electrode, and a moving direction of the mass part. You may use for the acceleration sensor which formed the fixed part used as a fixed electrode.

On the other hand, in the first and second embodiments,
A plurality of acceleration sensors 31 (5
Although 1) is described as being manufactured, the present invention is not limited to this, and only one may be manufactured, in which case the last cutting step is not necessary.

[0095]

As described above in detail, in the acceleration sensor according to the first aspect of the present invention, the acceleration is detected by the capacitance as the displacement of the distance between the fixed electrode and the movable electrode of the mass portion. By covering the movable portion having the portion and the fixed portion having the fixed electrode with the cover, it is possible to prevent dust and the like from entering from the outside and extend the life of the acceleration sensor.

By forming the movable electrode of the movable portion and the fixed electrode of the fixed portion as comb-shaped electrodes,
The effective area between the electrodes can be increased, and the respective electrode plates can be opposed to each other through a minute gap.

Further, by forming the cover from a silicon plate and providing a signal processing circuit on the cover, the acceleration sensor and the signal processing circuit can be electrically connected when the cover is joined to the insulating substrate. . Then, the acceleration sensor and the signal processing circuit can be connected by the extraction electrode, and the wire can be eliminated. As a result, the stray capacitance of the wire can be prevented from being added to the detected electrostatic capacitance, and the acceleration can be accurately detected.

On the other hand, in the method of manufacturing the acceleration sensor according to the sixth aspect of the present invention, the cover formed of the insulating plate can be manufactured in the step of manufacturing the acceleration sensor, and the cover allows the fixed portion and the movable portion to be manufactured. Can be cut off from the surroundings, and the life of the acceleration sensor can be extended.

Furthermore, in the method of manufacturing an acceleration sensor according to claim 9 of the present invention, the peripheral wall of the cover is formed of a silicon plate, the lid is formed of an insulating plate, and the peripheral wall and the lid are formed by the second joining step. A cover can be formed, and the fixed part and the movable part can be isolated from the surroundings by the cover, and the life of the acceleration sensor can be extended.

Each of the above-mentioned manufacturing methods can also be used when manufacturing a plurality of acceleration sensors at one time. In this case, the cover formed on the insulating substrate is movable with a plurality of sets of fixed parts. Since it is provided so as to cover the fixed portion and the movable portion, it is possible to prevent chips or moisture from entering or infiltrating into the fixed portion and the movable portion during the final cutting step of dividing each acceleration sensor. As a result, the yield in the manufacturing process can be increased and the productivity can be improved.

[Brief description of drawings]

FIG. 1 is a partially cutaway plan view showing an acceleration sensor according to a first embodiment of the present invention by cutting it at a position of a cover.

FIG. 2 is a vertical sectional view as seen from the direction of arrows II-II in FIG.

FIG. 3 is a vertical cross-sectional view showing a silicon wafer used for forming a fixed portion and a movable portion of an acceleration sensor, an insulating substrate, and a glass plate for forming a cover.

FIG. 4 is a vertical cross-sectional view showing a state in which a groove is formed on one side surface of a silicon wafer by a first etching step, a state in which a recess and an extraction electrode are formed in a glass substrate, and a state in which a groove for forming a cover is formed in a glass plate. It is a figure.

5 is a vertical cross-sectional view showing a state in which one side surface of the silicon wafer and the glass substrate are bonded by the first bonding step following the first etching step in FIG.

6 is a vertical cross-sectional view showing a state in which a fixed portion and a movable portion are formed on a silicon wafer by a second etching step following the joining step shown in FIG.

7 is a vertical cross-sectional view showing a state in which glass plates are joined so as to cover a fixed portion and a movable portion formed on a glass substrate by a second joining step that follows the second etching step shown in FIG. is there.

8 is a vertical cross-sectional view showing an acceleration sensor formed in plural by a cutting process following the second bonding process in FIG. 7.

FIG. 9 is a plan view showing an extraction electrode formed on a glass substrate.

FIG. 10 is a vertical sectional view showing an acceleration sensor according to a second embodiment of the present invention.

FIG. 11 is a vertical cross-sectional view showing a silicon wafer used to form a fixed portion, a movable portion, and a support portion for a cover of an acceleration sensor, an insulating substrate, and a glass plate for forming a cover.

FIG. 12 is a vertical cross-sectional view showing a state in which a groove is formed on one side surface of a silicon wafer and a state in which a recess and an extraction electrode are formed on a glass substrate by a first etching step.

13 is a vertical cross-sectional view showing a state in which one side surface of the silicon wafer and the glass substrate are bonded by the first bonding step following the first etching step in FIG.

FIG. 14 is a vertical cross-sectional view showing a state where one side surface of the silicon wafer is masked on a side part of the cover by a masking step following the joining step shown in FIG. 13;

FIG. 15 is a vertical cross-sectional view showing a state in which one side surface of the silicon wafer is edged to a side portion of the cover by the second etching step following the masking step in FIG.

16 is a vertical cross-sectional view showing a state in which a cover is formed by joining a glass plate to a peripheral wall by a second joining step that follows the second etching step shown in FIG.

17 is a vertical cross-sectional view showing a plurality of acceleration sensors formed by a cutting process following the second bonding process of FIG.

FIG. 18 is a partially cutaway external view showing a state in which an acceleration sensor according to a third embodiment of the present invention is attached to a stem.

FIG. 19 is a longitudinal sectional view showing an enlarged main part in FIG.

FIG. 20 is an exploded perspective view showing a state before the cover is joined to the insulating substrate.

FIG. 21 is a plan view showing an acceleration sensor according to the prior art.

22 is a vertical cross-sectional view as seen from the direction of arrows XXII-XXII in FIG. 21.

FIG. 23 is a vertical cross-sectional view showing a silicon wafer and a glass substrate used for forming a fixed portion and a movable portion of the acceleration sensor.

FIG. 24 is a vertical cross-sectional view showing a state where a groove is formed on one side surface of a silicon wafer by the first etching step and a state where a groove is formed on a glass substrate by the glass etching step.

FIG. 25 is a vertical cross-sectional view showing a state where one side surface of a silicon wafer and a glass substrate are bonded together.

FIG. 26 is a vertical cross-sectional view showing a state in which a fixed portion and a movable portion are formed on a silicon wafer by the second etching step following the joining step shown in FIG. 25.

27 is a vertical cross-sectional view showing a plurality of acceleration sensors formed by a cutting step following the second etching step of FIG.

FIG. 28 is a plan view showing a state in which a plurality of sets of fixed parts and movable parts are formed of a silicon wafer on a glass substrate.

FIG. 29 is a cross-sectional view showing a state in which the acceleration sensor is housed in a package.

[Explanation of symbols]

 2, 12, 73 Glass substrate (insulating substrate) 10 Extraction electrode 31, 51, 72 Acceleration sensor 32 Fixed part 33 Fixed side comb-shaped electrode (fixed electrode) 34 Movable part 35 Support part 36 Beam 37 Mass part 38 Movable side comb Electrodes (movable electrodes) 39, 52, 75 Covers 39A, 52A Peripheral walls 39B, 52B Lids 41, 61 Silicon wafers (silicon plates) 42, 62 Glass plates 43, 63 Grooves 44, 75A Recesses 76 Signal processing circuit

Claims (10)

[Claims] 1. An insulating substrate, provided on the insulating substrate,
A silicon plate is provided with a fixed portion and a movable portion which are formed separately by etching the silicon plate, and a fixed electrode is integrally formed on the fixed portion, and the movable portion is a support fixed on an insulating substrate. And a mass portion that is connected to the support portion via a beam and is displaced according to the acceleration when an acceleration acts, and a small gap between the fixed electrode formed on the fixing portion in the mass portion. In an acceleration sensor formed integrally with a movable electrode that is provided so as to face each other with the movable portion approaching and separating by the displacement of the mass portion, the insulating substrate includes a periphery of the fixed portion and the movable portion. An acceleration sensor, characterized in that a cover including an annular peripheral wall provided on the insulating substrate so as to cover the cover and a lid portion covering an opening portion of the peripheral wall is formed. 2. The acceleration sensor according to claim 1, wherein the cover has a peripheral wall and a lid integrally formed from the same member. 3. The acceleration sensor according to claim 1, wherein the cover has a peripheral wall made of a silicon plate, a lid part made of an insulating plate, and the peripheral wall and the lid part are joined to each other. 4. The acceleration sensor according to claim 1, wherein the fixed electrode and the movable electrode are comb-shaped electrodes provided so as to project from the fixed portion and the mass portion, respectively. 5. The cover is made of a silicon plate, and the silicon plate is provided with a signal processing circuit for converting a change in electrostatic capacitance generated between the movable electrode and the fixed electrode into a voltage. Or the acceleration sensor according to 4. 6. A first etching step of etching a silicon plate from one side surface to form a groove for separating a fixed portion and a movable portion on one side surface of the silicon plate, and the groove on the silicon plate. After forming a first bonding step of bonding one side surface of the silicon plate to the insulating substrate, and performing etching treatment from the other side surface of the silicon plate in a state where the silicon plate is bonded to the insulating substrate, A second etching step of separately forming a fixed portion and a movable portion on a silicon plate, and a second joining step of joining a cover covering the fixed portion and the movable portion formed on the silicon plate to the insulating substrate. A method of manufacturing an acceleration sensor, which comprises the steps of: 7. The method of manufacturing an acceleration sensor according to claim 6, wherein lead electrodes connected to the fixed portion and the movable portion are formed on the insulating substrate before the first joining step. 8. The cover for covering the fixed portion and the movable portion formed in the second etching step is formed by forming a recess in the insulating plate before the second joining step. 6. The method for manufacturing the acceleration sensor according to 6 or 8. 9. A first etching step of etching a silicon plate from one side surface to form a groove on one side surface of the silicon plate for separating a fixed part, a movable part and a peripheral wall of a cover, and the silicon plate. After forming the groove in
A first bonding step of bonding one side surface of the silicon plate to an insulating substrate; and a masking step of masking the portion of the silicon plate bonded to the insulating substrate to the peripheral wall of the cover from the other side surface of the silicon plate. And a second etching step in which the fixed portion, the movable portion and the peripheral wall of the cover are separated from each other by performing an etching treatment from the other side surface of the silicon plate, and a plurality of sets of the plurality of sets formed on the silicon plate. A method of manufacturing an acceleration sensor, comprising a second joining step of joining an insulating plate that covers the peripheral wall so as to cover the fixed portion and the movable portion. 10. The method of manufacturing an acceleration sensor according to claim 9, wherein lead electrodes connected to the fixed portion and the movable portion are formed on the insulating substrate before the first joining step.