JP2000275272A - Semiconductor acceleration sensor and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor acceleration sensor capable of being easily miniaturized and having good linearlity of a characteristic and a high production yield and provide its manufacturing method. SOLUTION: This acceleration sensor is provided with a silicon substrate 10 formed with a moving electrode 10b supported by a beam and two glass substrates 12, 13 formed with fixed electrodes 18, 19 facing each other across the silicon substrate 10 on the surface. The glass substrates 12, 13 are provided with through holes 12b, 13b, and the fixed electrodes 18, 19 are connected to silicon, electrodes 26, 27 on the back faces of the glass substrates 12, 13 via the through holes 12b, 13b. Electric connection paths are extracted to the outside from the fixed electrodes 18, 19 without using the extracting electrode of the silicon substrate 10, thus the sensor is miniaturized, and the ohmic contact of a connection section can be easily ensured. The sensor can be manufactured with no glass fusion and no glass polishing applied.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a semiconductor acceleration sensor, and more particularly, to a structure and a manufacturing method of a capacitive acceleration sensor using a change in capacitance.

[0002]

2. Description of the Related Art A capacitive semiconductor acceleration sensor is an acceleration sensor that detects a force acting on the sensor during acceleration as a change in electric capacitance, and is used, for example, for controlling the attitude of an automobile and controlling the operation of an airbag system.

The structure and manufacturing method of a conventional typical capacitive semiconductor acceleration sensor is described in, for example, Japanese Patent Application Laid-Open No. 6-24193.
No. 2 discloses this. FIG. 6A is a plan view showing the capacitive semiconductor acceleration sensor, and FIG.
FIG. 4 is a cross-sectional view taken along line -A ′.

In a semiconductor acceleration sensor, a silicon substrate 10 having a hollow inside is generally made of glass substrates 12 and 13.
And the inside of the sensor is hollow. A movable electrode 10b supported by a beam 10a is formed inside the hollowed inside of the silicon substrate 10. On the other hand, the fixed electrodes 1 are provided on the inner surfaces of the glass substrates 12 and 13.
8 and 19 are formed, and the movable electrode 10b and the fixed electrodes 18 and 19 are arranged so as to face each other with an interval of several μm.

When the sensor is accelerated and a force corresponding to the acceleration is applied to the movable electrode 10b, the movable electrode 10b and the fixed electrode 1
The distance between 8 and 19 changes, thereby changing the capacitance value between the movable electrode and the fixed electrode. Therefore, the movable electrode 10b
The acceleration applied to the sensor can be measured by measuring the electric capacitance between the electrodes and the fixed electrodes 18 and 19.

In order to measure the electric capacitance value, it is necessary to draw an electric connection path to the outside from the movable electrode 10b and the fixed electrodes 18 and 19 arranged inside the sensor. on the other hand,
The air present inside the sensor acts as a damper and hinders the response of the movable electrode to acceleration, so that the inside of the sensor needs to be sealed under reduced pressure. Therefore, conventionally, the electrical connection path has been drawn out in the following manner.

An electrical connection path is drawn out from the movable electrode 10b to the outside through the beam 10a and the sealing portion 10e of the silicon substrate.

From the fixed electrodes 18 and 19, an electrical connection path is drawn out to the outside through the lead electrodes 10c and 10d and the metal electrode 22. The extraction electrodes 10 c and 10 d are electrodes formed in an island shape by etching inside the hollowed-out silicon substrate 10. The fixed electrodes 18 and 19 and the extraction electrodes 10c and 10d are
And the silicon substrate 10 are joined by pressure.

However, in the structure disclosed in Japanese Patent Laid-Open No. 6-241932, since the extraction electrodes 10c and 10d occupy a large area with respect to the entire sensor, it is difficult to reduce the size of the sensor. Further, since the fixed electrodes 18 and 19 and the extraction electrodes 10c and 10d are connected by pressure welding,
It has been difficult to stably obtain an ohmic contact between the fixed electrode and the extraction electrode. In particular, it has been difficult to ensure ohmic contact at the joints for all sensors formed in a plurality on the wafer substrate. When there is a portion that is not in ohmic contact in the electric connection path of the fixed electrode, the correlation between the electric capacity value and the current-voltage characteristic is disturbed, and the linearity of the sensor characteristic deteriorates.

Further, in order to form the extraction electrodes 10c and 10d on the silicon substrate, the silicon substrate is etched in an island shape leaving beams supporting the extraction electrodes, and after the silicon substrate 10 is bonded to the glass substrate 12, The beam supporting the extraction electrode must be cut. That is, a resist mask must be applied while leaving the beam, and etching must be performed. However, the extraction electrodes 10c and 10d
Since there is a step of 100 μm or more in the beam part supporting the resist, it is difficult to uniformly apply the resist mask. For this reason, there is a problem that the shape defect and the foreign matter defect of the silicon substrate 10 are easily generated.

Therefore, as a semiconductor acceleration sensor as an alternative, a sensor having a structure shown in FIG.
No. 65 is disclosed. FIG. 7A is a plan view of the semiconductor acceleration sensor, and FIG. 7C is a sectional view taken along line BB ′. FIG. 7B is a plan view of only the silicon substrate 10.

Similar to the sensor disclosed in Japanese Patent Application Laid-Open No. 6-241932, a silicon substrate 10 having a movable electrode 10b formed in the inside thereof is sandwiched between glass layers 30 and 31. Fixed electrode 1 on the surface of
8 and 19 are formed.

In this semiconductor acceleration sensor, an electric connection path is drawn out from the fixed electrodes 18 and 19 without passing through the drawing electrode. That is, the fixed electrodes 18, 19 are connected to the silicon plates 26, 27 provided on the back surfaces of the glass layers 30, 31.
Through the projections 26a and 27a, thereby drawing out an electrical connection path.

FIGS. 8 and 9 are schematic views showing a manufacturing process of the semiconductor acceleration sensor. Note that the process shown in FIG.
The process shown in FIG. First, the silicon substrate 10 is etched to form the beam 10a and the movable electrode 10b (FIGS. 8A to 8D). Next, two silicon plates 2
6 and 27 are prepared (FIG. 8E), and etching is performed using the resist 17 as a mask to form protrusions 26a and 27a on the silicon plates 26 and 27 (FIG. 8F). Next, molten glass is poured into the surfaces of the silicon plates 26 and 27 so as to completely cover the projections 26a and 27a, and then cooled, and the glass layers 30 and 31 are fused to the surfaces of the silicon plates 26 and 27 ( FIG. 8 (g)). Next, the fused glass layer 3
0 and 31 are polished to flatten the surface and expose the projections 26a and 27a of the silicon plate (FIG. 8 (h)).
Next, the projections 26a, 2a are formed on the surfaces of the fused glass layers 30, 31.
Metal films 18 and 19 are formed so as to cover 7a to form a fixed electrode (FIG. 8 (i)). Next, the silicon substrate 10 of FIG. 8D is bonded onto the glass layer 30 (FIG. 9).
(J)) Further, a glass layer 31 is formed on the silicon substrate 10.
(FIG. 9 (k)). Bonding can be performed by an anodic bonding method. The anodic bonding method is a bonding method performed by applying a DC bias voltage between glass and silicon.

In the semiconductor acceleration sensor disclosed in Japanese Patent Application Laid-Open No. 1-259265, miniaturization is easy because there is no need to provide a lead electrode on the silicon substrate, and the fixed electrodes 18, 19 are directly connected to the projections 26a of the silicon plate. , 27b, a good ohmic contact can be obtained.

However, when the glass layers 30 and 31 are fused (FIG. 8 (g)), bubbles are easily generated inside the glass layers. Further, since the thermal expansion coefficients of silicon and glass are different by one to two digits, when the glass layers 30 and 31 are cooled from the molten state on the silicon plate, they may be separated without being fused to the silicon plate. Further, a polishing step of the glass layers 30 and 31 (FIG. 8)
In (h)), there is also a problem that uniform polishing is difficult because the polishing rates of glass and silicon are different. That is,
Due to these problems, the manufacturing yield of the semiconductor acceleration sensor disclosed in Japanese Patent Application Laid-Open No. 1-259265 was not sufficient. Furthermore, since the polishing step is included, there is a problem that the manufacturing cost is high.

[0017]

As described above, Japanese Unexamined Patent Application Publication No.
The semiconductor acceleration sensor disclosed in Japanese Patent Laid-Open No. 241932 has problems that it is difficult to reduce the size and the linearity of the sensor characteristics is poor.
In the sensor disclosed in Japanese Patent Application Laid-Open No. H11-207, there is a problem that the production yield is low and the production cost is high.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a semiconductor acceleration sensor that can be easily miniaturized, has good linearity of characteristics, and has a high production yield, and a method of manufacturing the same.

[0019]

In order to achieve the above object, a semiconductor acceleration sensor according to the present invention comprises a first substrate facing a silicon substrate on which a movable electrode supported by a beam is formed. A first glass substrate having a fixed electrode formed on the surface thereof, and a second glass substrate having a second fixed electrode formed on the surface, wherein the first and second glass substrates have through holes, Silicon electrodes are formed on the back surfaces of the first and second glass substrates, and the first and second fixed electrodes are also formed inside the through holes and connected to the silicon electrodes on the back surfaces. Things.

According to this structure, since the electrical connection path is drawn from the fixed electrode without passing through the lead electrode of the silicon substrate, the sensor can be downsized and the ohmic contact of the connection can be easily secured. Further, it can be manufactured without performing glass fusion and glass polishing.

The first and second fixed electrodes are preferably metal films having a thickness of 3000 ° or more, so that the ohmic contact of the fixed electrode connecting portion can be further improved.

According to the method for manufacturing a semiconductor acceleration sensor of the present invention, (A) the first glass substrate and the second glass substrate are each provided with a through-hole and a silicon plate that covers one end of the through-hole. And (B) forming a conductive film on at least a part of the front surface and inside the through-hole on each of the first and second glass substrates, and connecting the first and second glass substrates to the silicon plate on the back surface. Forming a second fixed electrode; (C) etching a silicon substrate to form a movable electrode supported by a beam; and (D) forming the movable electrode with the first and second fixed electrodes. A step of bonding the first and second glass substrates to both surfaces of the silicon substrate so as to be sandwiched between the first and second glass substrates.

According to this manufacturing method, since the glass fusing step to silicon and the glass polishing step are not required, the manufacturing yield can be improved. In addition, since the electrical connection path can be drawn from the fixed electrode without using pressure contact, ohmic contact of the connection portion can be easily ensured, and the size of the sensor can be reduced.

In the above step (A), after a through-hole is formed in the first and second glass substrates, the silicon plate is anode-mounted on the first and second glass substrates so as to cover one end of the through-hole. It is preferable to join. Thereby, in the step of drilling a through-hole in the glass substrate, it is possible to suppress the occurrence of poor penetration of the silicon substrate.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a semiconductor acceleration sensor according to the present invention will be described with reference to the drawings. 1A is a plan view showing an example of a semiconductor acceleration sensor according to the present invention, and FIG. FIG. 1B is a plan view of only the silicon substrate.

The movable electrode 10b supported by the beam 10a
The first glass substrate 12 with the first fixed electrode 18 formed on the surface and the second glass substrate 13 with the second fixed electrode 19 formed on the surface face each other with the silicon substrate 10 on which the I have. Through holes 12b, 13b are formed in the first and second glass substrates 12, 13, and the first and second glass substrates 12, 13 are formed.
Silicon electrodes 26, 2
7 are formed. First and second fixed electrodes 18 and 19
Are also formed inside the through holes 12b and 13b and are connected to the silicon electrodes 26 and 27 on the back surface.

The sealing portion 10e of the silicon substrate 10 is bonded to the glass substrates 12 and 13, and the inside of the sensor is sealed under reduced pressure. In the present invention, the extraction of the electrical connection path from the electrode inside the sensor is performed as follows.
The electrical connection path from the movable electrode 10b is drawn out to the outside via the beam 10a and the sealing portion 10e. The electrical connection path from the first and second fixed electrodes 18 and 19 is a silicon electrode 2 connected to the first and second fixed electrodes via through holes.
Pull out outside through 6, 27.

The electric capacitance between the movable electrode 10b and the fixed electrodes 18 and 19 is measured from outside the sensor via these electric connection paths, and the acceleration is measured from a change in the electric capacitance value.

In the semiconductor acceleration sensor of the present invention, since the fixed electrodes 18 and 19 are directly connected to the silicon electrodes 26 and 27 outside the sensor without passing through the silicon substrate 10,
There is no need to form an extraction electrode on the silicon substrate 10, and the size of the sensor can be reduced. Further, a metal or the like is directly deposited on the silicon electrodes 26 and 27 to deposit the fixed electrodes 18 and 1.
Since 9 can be formed, good ohmic contact can be obtained.

The fixed electrodes 18 and 19 correspond to the glass substrate 1
It is connected to the silicon electrode via a step of several hundred μm corresponding to the thickness of 2 and 13. Therefore, in order to ensure good ohmic contact, it is preferable that the fixed electrodes 18 and 19 are formed of a metal film having a thickness of 3000 ° or more.

Further, as shown in FIG.
The bump 12a is provided on a portion facing the movable electrode 10b.
13a is preferably provided, so that the movable electrode 10b can be prevented from adhering to the fixed electrodes 18 and 19.

Further, FIG. 1 shows an example in which through holes 12a and 13a are provided on the opposite side of the beam 10a adjacent to the movable electrode 10b, but the position of the through holes is not limited to this. The through-hole may be provided anywhere as long as the connection with the fixed electrodes 18 and 19 can be secured. For example, the through-hole may be provided immediately above the beam 10a.

FIGS. 2 and 3 show an example of a manufacturing process of the semiconductor acceleration sensor of the present invention. The step shown in FIG. 3 is continuous with the step shown in FIG. First, the silicon substrate 10 is etched to form the movable electrode 10 supported by the beam 10a.
b is formed (FIGS. 2A to 2C). The movable electrode 1
For forming 0b, a general silicon substrate processing technique by photolithography and etching of a resist can be used.

Next, the first and second glass substrates 12, 1
3 is prepared (FIG. 2D). Although the type of the glass substrate is not particularly limited, for example, Pyrex glass or the like can be used.

Next, a mask layer 14 such as a Cr film is formed on the surfaces of the first and second glass substrates 12 and 13, and resist coating and patterning by Cr mixed acid etching are performed.
The mask layer 14 is formed so as to have a substantially rectangular opening except for portions where the bumps 12a and 13a are formed. The glass substrates 12, 13 are etched with hydrofluoric acid or the like using the mask layer 14 as an etching mask, and the bumps 12a, 1
3a is formed. (FIG. 2 (e)). Bumps 12a, 13
a serves to prevent the movable electrode from adhering to the fixed electrode.

Next, a mask layer 15 having substantially the same shape as the mask layer 14 except for the bumps 12a and 13a is formed.
The glass substrate is etched using the mask layer 15 as an etching mask to form a step for providing an interval between the movable electrode and the fixed electrode.

Next, a resist mask 17 is formed on the surfaces of the glass substrates 12 and 13 to form the through holes 12b and 13b. The resist mask 17 is preferably formed in a thickness of about 100 μm using a negative resist. Using the resist 17 as a mask, the through holes 12b and 13b are formed by sandblasting or the like (FIG. 2).
(G)). In addition, the glass substrate 1
In order to prevent the back surfaces of 2, 13 from being roughened, it is preferable to terminate the sandblasting process simultaneously with the completion of the perforation.

Next, silicon plates 26 and 27 are bonded to the back surfaces of the glass substrates 12 and 13 so as to cover one ends of the back surfaces of the through holes 12b and 13b (FIG. 2 (h)). The bonding is preferably performed by anodic bonding. Silicon plates 26, 27
May be formed on the entire back surface of the glass substrates 12 and 13 or on a part of the back surface. This silicon plate serves as a silicon electrode for drawing out electrical connection from the fixed electrode.

Next, the first and second glass substrates 12, 1
A conductive film is formed on the front surface of the substrate 3 and inside the through holes 12b and 13b to form first and second fixed electrodes connected to the silicon plate on the back surface (FIG. 2 (i)). The type of the conductive film is not particularly limited, but a Pt film is preferable from the viewpoint of oxidation resistance and the like. After the conductive film is formed by sputtering or the like, portions other than those required as fixed electrodes are removed by etching or the like.
Further, the thickness of the conductive film is preferably 3000 ° or more.

It should be noted that instead of the steps shown in FIGS. 2F to 2I, after bonding a silicon plate to the back surfaces of the glass substrates 12 and 13, the through holes 12b and
13b can also be perforated (FIG. 4 (a)-
(D)). However, in the case where the glass substrates 12 and 13 having the silicon plate bonded to the back surface are perforated by sandblasting (FIG. 4C), the sandblasting is completed simultaneously with the completion of the perforation of the glass substrate so that the silicon plate does not penetrate. There is a need to. However, since the perforation speed of the glass substrate by sandblasting has an in-plane distribution of the wafer, the silicon plates 26 and 27 are easily penetrated by excessive sandblasting. If the silicon plates 26 and 27 penetrate, the sensor cannot be maintained in a reduced pressure state, and the sensor becomes defective. Therefore, from the viewpoint of manufacturing yield, FIG.
It is preferable to perform the steps in the order of steps (f) to (i).

Next, the movable electrode 10b and the first fixed electrode 1
The silicon substrate 10 is bonded on the first glass substrate 12 so that the electrodes 8 face each other (FIG. 3 (j)).
The second glass substrate 13 is bonded onto the silicon substrate 10 so that the second fixed electrode 19 faces the second fixed electrode 19 (FIG. 3).
(K)). The bonding is preferably performed by anodic bonding. Further, it is preferable that the anodic bonding of the first and second glass substrates 12 and 13 and the silicon substrate 10 is performed under reduced pressure, and the inside of the sensor is sealed under reduced pressure. This is for suppressing the damper action of air and improving the response of the movable electrode 10b to the acceleration.

The method of manufacturing a semiconductor acceleration sensor according to the present invention does not require a glass fusing and glass polishing step, so that there are few occurrences of defects such as peeling of a silicon plate and a glass substrate, and it can be manufactured at low cost.

[0043]

EXAMPLE A semiconductor acceleration sensor according to the present invention was manufactured according to the manufacturing method of the present invention under the following conditions. First, Pyrex glass having a thickness of 0.4 mm was prepared as the first and second glass substrates 12 and 13, and 2000 μm was used as the mask layer 14.
A thick Cr film was formed. Using the Cr film 14 and the resist as an etching mask, the surfaces of the first and second glass substrates were etched by 1 μm with 10% diluted hydrofluoric acid. Further, using the Cr film 14 and a resist as the mask layer 15,
The surfaces of the first and second glass substrates were etched by 5 μm with 0% diluted hydrofluoric acid. A negative resist having a thickness of 100 μm is formed as a resist mask 16 on the first and second glass substrates, and the through holes 12 b and 13 are formed by sandblasting.
b was perforated. After anodically bonding 0.2 mm thick silicon plates 26 and 27 to the back surfaces of the first and second glass substrates 12 and 13, a 1 μm thick Pt film is formed as a fixed electrode on the surfaces of the glass substrates 12 and 13 by sputtering. did.

A movable electrode 10b is formed by alkali etching a silicon substrate having a thickness of 0.4 mm,
A semiconductor acceleration sensor was manufactured by anodic bonding with Nos. 2 and 13.

Fixed electrode 1 of manufactured semiconductor acceleration sensor
In order to evaluate the electrical contact between 8, 19 and the silicon electrodes 26, 27, the current-voltage characteristics between the fixed electrode and the silicon electrode were evaluated by a two-terminal method. FIG. 5 shows the evaluation results. From FIG. 5, it can be confirmed that in the semiconductor acceleration sensor of the present invention, good ohmic contact is made between the fixed electrode and the silicon electrode. To obtain the required sensor characteristics, the contact resistance between the fixed electrode and the silicon electrode needs to be 1 kΩ or less, but the measured resistance value is 270.
Ω. Further, when the resistance value of the silicon plate itself was subtracted, the contact resistance became 90Ω, and it was confirmed that the contact resistance was sufficiently small as a semiconductor acceleration sensor.

[0046]

The present invention has the following effects because it is configured as described above. In the semiconductor acceleration sensor of the present invention, the first and second glass substrates have through holes, and the first and second fixed electrodes are formed inside the through holes and connected to the silicon electrodes on the back surface. In addition, a lead electrode of the silicon substrate is unnecessary. Therefore, the size of the sensor can be reduced, and the ohmic contact of the connection portion can be easily ensured. Further, it can be manufactured without performing glass fusion and glass polishing.

Further, by using a metal film having a thickness of 3000 mm or more of the fixed electrode, the ohmic contact between the fixed electrode and the silicon electrode can be further improved.

According to the method for manufacturing a semiconductor acceleration sensor of the present invention, a through hole is formed in each of the glass substrates, and a silicon plate closing one end of the through hole is bonded to the glass substrate so as to be connected to the silicon plate on the back surface. Since a conductive film is formed on the surface of the substrate and inside the through-hole to form the fixed electrode, a glass fusing step to silicon and a glass polishing step are unnecessary. Therefore, a semiconductor acceleration sensor can be produced at low cost and high yield. In addition, since the electrical connection path from the fixed electrode can be drawn out to the outside without passing through the extraction electrode of the silicon substrate, ohmic contact of the connection portion can be easily secured, and the sensor can be downsized.

Further, by forming a through hole in a glass substrate and then bonding a silicon plate so as to cover one end of the through hole, it is possible to suppress the occurrence of a defect in which the silicon substrate penetrates, thereby reducing the production yield of the semiconductor acceleration sensor. Can be improved.

[Brief description of the drawings]

FIG. 1A is a plan view showing an example of a semiconductor acceleration sensor of the present invention, FIG. 1B is a plan view of only a silicon substrate,
(C) It is CC 'line sectional drawing.

FIG. 2 is a process chart showing an example of a manufacturing process of the semiconductor acceleration sensor of the present invention.

FIG. 3 is a process drawing showing a manufacturing process of the semiconductor acceleration sensor of the present invention, which is continuous to FIG. 2;

FIG. 4 is a process chart showing another example of a part of the manufacturing process shown in FIG. 2 of the semiconductor acceleration sensor of the present invention.

FIG. 5 is a graph showing measured values of current-voltage characteristics between a fixed electrode and a silicon electrode in the semiconductor acceleration sensor of the present invention.

6A is a plan view showing an example of a conventional semiconductor acceleration sensor, FIG. 6B is a plan view showing only a silicon substrate,
(C) It is a sectional view on the AA 'line.

7A is a plan view showing another example of a conventional semiconductor acceleration sensor, FIG. 7B is a plan view showing only a silicon substrate,
(C) It is a BB 'line sectional view.

FIG. 8 is a process chart showing a manufacturing process of the semiconductor acceleration sensor shown in FIG. 6;

9 is a process chart showing a manufacturing process of the semiconductor acceleration sensor shown in FIG. 6 which is continuous with FIG. 8;

[Explanation of symbols]

10 silicon substrate, 10a beam, 10b movable electrode,
10c and 10d extraction electrodes, 10e sealing portion, 1
2 First glass substrate, 13 Second glass substrate, 14
And 15 mask layers, 16 and 17 resist masks,
18 first fixed electrode, 19 second fixed electrode, 20
Through-holes, 22 and 24 Metal electrodes, 26 and 27 Silicon plates, 30 and 31 Glass layers.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Junichi Ichikawa 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Corporation F-term (reference) 4M112 AA02 BA07 CA26 DA04 DA09 DA18 EA02 EA13 GA01

Claims (4)

[Claims] 1. A silicon substrate on which a movable electrode supported by a beam is formed, a first glass substrate having a first fixed electrode formed on a surface thereof opposed to the silicon substrate, and a second fixed electrode A second glass substrate having a surface formed thereon, wherein the movable electrode and the first and second substrates sandwiching the movable electrode are provided.
A semiconductor acceleration sensor for detecting a change in capacitance between the first and second glass substrates, wherein the first and second glass substrates have a through hole;
And a silicon electrode is formed on the back surface of the second glass substrate, and the first and second fixed electrodes are also formed inside the through-hole and connected to the silicon electrode on the back surface. Sensor. 2. The method according to claim 1, wherein the first and second fixed electrodes have a thickness of 3 mm.
2. The semiconductor acceleration sensor according to claim 1, wherein the sensor is a metal film having a thickness of not less than 000 °. 3. A method for manufacturing a semiconductor acceleration sensor for detecting a change in capacitance between a movable electrode supported by a beam and a first fixed electrode and a second fixed electrode sandwiching the movable electrode. (A) a step of forming a through hole in each of the first glass substrate and the second glass substrate, and bonding a silicon plate closing one end of the through hole; and (B) the first and second glass substrates.
Forming a conductive film on at least a part of the front surface and inside the through holes on each of the glass substrates to form first and second fixed electrodes connected to the silicon plate on the back surface;
(C) a step of etching the silicon substrate to form a movable electrode supported by beams; and (D) both sides of the silicon substrate so that the movable electrode is sandwiched between the first and second fixed electrodes. Bonding the first and second glass substrates to each other. 4. In the step (A), after a through-hole is formed in the first glass substrate and the second glass substrate, silicon is formed on the first and second glass substrates so as to cover one end of the through-hole. 4. The method according to claim 3, wherein the plates are joined.