JP2000277753A - Semiconductor accelerometer and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To weaken an unneccesary excess stress applied to a thin flexure part in a manufacturing process. SOLUTION: P-type impurities are diffused to form a gauge resistance 12. Silicon oxide films 13 are formed on both faces of a silicon wafer 11. In addition, a silicon nitride film 14 is formed. After that, a wiring electrode 15 and junction electrodes 16 are formed. A resist patterning operation, an etching operation and an anisotropic etching are performed by KOH to the rear surface of the silicon wafer 11. Regions which correspond to a flexure part 113 and a separation interval S in the silicon wafer 11 are made thin, down to about 10 μm. After that, the silicon oxide film 13 and the silicon nitride film 14 left on the rear surface of the silicon wafer 11 are removed. Then, a lower cap 17 is bonded to the silicon wafer 11, and a removal treatment is conducted in which a weight 111 and a peripheral thick part 112 are separated leaving the flexure part 113. After that, an upper cap 18 is bonded to the silicon wafer 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor acceleration sensor for use in, for example, automobiles, aircraft, and home electric appliances, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Generally, acceleration sensors have the following shapes.
A so-called cantilever system and a doubly supported system have been proposed. Further, the detection method includes a method of detecting mechanical strain as a change in electric resistance and a method of detecting mechanical strain as a change in capacitance.

FIG. 17 is a plan view of a conventional semiconductor acceleration sensor which employs a cantilever method and the former detection method, and FIG. 18 schematically shows a cross-sectional structure in a manufacturing process of the semiconductor acceleration sensor. FIG. However,
FIG. 18C schematically shows a cross-sectional structure taken along line AA in FIG. 17, and FIG. 18 shows only a cross-section.

As shown in FIGS. 17 and 18D, the semiconductor acceleration sensor 10 has a thick weight 11
1. Peripheral thick portion 112 provided apart from the periphery of weight portion 111, and peripheral thick portion 112 and weight portion 1
N-type silicon wafer 11 formed with a thin flexible portion 113 suspended between the silicon wafer 11 and the weight 111
A gauge resistor 12 formed on the upper surface of the bent portion 113 of the silicon wafer 11, a silicon oxide film 13 formed on the upper surface (front surface) of the silicon wafer 11, and formed on the upper surface of the silicon oxide film 13. The silicon nitride film 14, the wiring electrode 15 and the bonding electrode 16 formed on the upper surface of the silicon wafer 11, that is, the upper surface of the silicon nitride film 14, and the concave shape bonded on the lower surface (back surface) of the silicon wafer 11. It comprises a lower cap 17 and a concave upper cap 18 joined to the upper surface of the silicon wafer 11 at the junction electrode 16.

[0005] However, each of the lower cap 17 and the upper cap 18 has a damping effect in order to prevent the bending portion 113 from being greatly bent and broken when excessive acceleration is applied to the semiconductor acceleration sensor 10. In the example of FIG. 17 and FIG. 18, it is formed in a box shape with a single-sided opening, and the four sides which are the opening edges are on the surface (lower surface or upper surface) of the peripheral thick portion 112 of the silicon wafer 11. Upper). 17 and FIG.
S shown in FIG. 8 indicates a separated portion where the weight portion 111 and the peripheral thick portion 112 are separated.

Next, the semiconductor acceleration sensor 10 having the above configuration
First, a gauge resistor 12 is formed on the upper surface of a silicon wafer 11 by P-type impurity diffusion, and thereafter, a silicon oxide film 13 is formed on both surfaces of the silicon wafer 11 and a silicon nitride film 14 is further formed. Is formed (see FIG. 18A).

Next, resist patterning and etching are performed on the silicon oxide film 13 and the silicon nitride film 14 on the lower surface of the silicon wafer 11, and using this as a mask, anisotropic etching is performed from below the silicon wafer 11 with KOH. The area corresponding to the bent portion 113 and the separated portion S in the silicon wafer 11 is
Thin to about μm. Next, a contact window is formed and the wiring electrode 15 and the bonding electrode 16 are formed. After this,
Silicon oxide film 13 remaining on the lower surface of silicon wafer 11
Then, the silicon nitride film 14 is removed by etching (see FIG. 18B).

Next, as shown in FIG.
1 is removed from the peripheral thick portion 112 while leaving, for example, two bent portions 113. That is, the silicon oxide film 13, the silicon nitride film 14 and the silicon wafer 11 in the separated portion S are patterned and
It is removed by etching using E or the like (see FIG. 18C).

Next, the lower cap 17 and the upper cap 18 are bonded to the silicon wafer 11 (FIG. 18).
(D)). Thus, the semiconductor acceleration sensor 10 is formed.

Japanese Patent Application Laid-Open No. Hei 9-116171 discloses a first silicon substrate on which an action portion, a flexible portion for supporting the action portion, and a fixing portion for supporting the action portion are formed. An etching mask for preparing a supporting body to be supported and a second silicon substrate on which a weight body supported by the operation section is formed, and forming each of the operation section, the flexible section and the fixed section Is produced on the first silicon substrate, and a method of manufacturing a physical quantity sensor (acceleration sensor) for bonding the first silicon substrate and the second silicon substrate using the etching mask as a bonding layer is described. .

[0011]

In the conventional semiconductor acceleration sensor shown in FIGS. 17 and 18, a thin bent portion 113 is provided for detecting acceleration. In the case of such a structure, the sensitivity is increased. Therefore, it is necessary to further reduce the thickness of the bending portion 113 or increase the weight of the weight portion 111 so that the bending amount of the bending portion 113 increases. However, when the sensitivity is increased in this way, the bending portion is easily broken in the chucking by vacuum, the cleaning with liquid, and the etching process in the patterning process of the manufacturing process, which causes problems such as yield and contamination of the manufacturing equipment. I do.

The present invention has been made in view of the above circumstances, and provides a method of manufacturing a semiconductor acceleration sensor capable of weakening unnecessary excessive stress applied to a thin bending portion in a manufacturing process, and a method of manufacturing the semiconductor acceleration sensor. It is an object to provide a manufactured semiconductor acceleration sensor.

[0013]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the invention according to claim 1 is characterized in that a thick weight portion, a peripheral thick portion provided separately around the weight portion, and a peripheral portion thereof are provided. A semiconductor substrate having a thin flexible portion suspended between a thick portion and the weight portion for supporting the weight portion, a gauge resistor formed in the flexible portion of the semiconductor substrate, and the semiconductor substrate An electrode for extracting an electric signal formed on one surface of the semiconductor substrate, a concave first cap bonded on another surface of the semiconductor substrate, and a concave cap bonded on one surface of the semiconductor substrate. A method for manufacturing a semiconductor acceleration sensor comprising a second cap, wherein one of the first and second caps is joined to the semiconductor substrate, and after the joining, the weight portion and the peripheral thick portion are joined together. Is removed to separate the The other of the said first and second cap after sense is to perform bonding to the semiconductor substrate.

According to this method, the first and second caps are joined to one of the semiconductor substrates before the removal process for separating the weight portion and the peripheral thick portion, so that a thin wall is formed in the manufacturing process. It is possible to reduce unnecessary excessive stress applied to the bending portion.

The semiconductor substrate is made of silicon, a predetermined film having a low etching rate for anisotropic etching by TMAH is formed on one surface of the semiconductor substrate, and the electrode is formed on the surface of the predetermined film. For the semiconductor acceleration sensor to be performed, the first cap is bonded to the semiconductor substrate, and after this bonding, the predetermined film is removed at a distance between the weight portion and the peripheral thick portion, After the removal, anisotropic etching by TMAH is performed on the separated portion of the semiconductor substrate to perform a removal process for separating the weight portion and the peripheral thick portion. After the removal process, the removal process is performed. A method of bonding two caps to the semiconductor substrate may be used (claim 2). According to this method, by setting the step of removing the predetermined film before the step of the removal processing, it is possible to prevent a member or a liquid used for removing the predetermined film from flowing under the weight portion.

Further, the semiconductor substrate is made of silicon, a predetermined film having a low etching rate for anisotropic etching by TMAH is formed on one surface of the semiconductor substrate, and the electrode is formed on the surface of the predetermined film. For the semiconductor acceleration sensor to be performed, the predetermined film is removed at a distance between the weight portion and the peripheral thick portion, and after this removal, the first cap is joined to the semiconductor substrate, After this bonding, an anisotropic etching with TMAH is performed on the separated portion of the semiconductor substrate to perform a removing process for separating the weight portion and the peripheral thick portion, and after the removing process, the removing process is performed. A method of joining two caps to the semiconductor substrate may be used (claim 3). According to this method, for example, by setting the step of removing the predetermined film before the bonding of the first cap,
A patterning step for removing a predetermined film after the cap is joined becomes unnecessary.

Further, the semiconductor substrate is an SOI substrate, a predetermined film having a low etching rate for anisotropic etching by TMAH is formed on one surface of the semiconductor substrate, and the electrode is formed on the surface of the predetermined film. For the semiconductor acceleration sensor to be formed, the first cap is bonded to the semiconductor substrate, and after this bonding, the predetermined film is removed in a space between the weight portion and the peripheral thick portion. Performing anisotropic etching by TMAH on the separated portion of the semiconductor substrate after the removal,
After the anisotropic etching, an oxide film that is the remaining portion of the SOI substrate in the separated portion is removed by etching, thereby performing a removing process for separating the weight portion and the peripheral thick portion. A method of bonding the second cap to the semiconductor substrate later may be used (claim 4). According to this method, the TMAH below the bending portion
Can be prevented from wrapping around. As a result, it is possible to prevent the thickness of the bent portion from decreasing.

Further, the semiconductor substrate is an SOI substrate, a predetermined film having a low etching rate for anisotropic etching by TMAH is formed on one surface of the semiconductor substrate, and the electrode is formed on the surface of the predetermined film. For the semiconductor acceleration sensor to be formed, the predetermined film is removed at a portion where the weight portion and the peripheral thick portion are separated, and after this removal, the difference between the separated portion of the semiconductor substrate due to TMAH is removed. Performing anisotropic etching, bonding the first cap to the semiconductor substrate after the anisotropic etching, and removing an oxide film as a remaining portion of the SOI substrate in the separated portion after the bonding by etching; Then, a removing process for separating the weight portion and the peripheral thick portion is performed, and after the removing process, the semiconductor substrate of the second cap is removed. It may be of a method of performing joint (claim 5). According to this method, after joining the first cap, T
There is no need to perform anisotropic etching with MAH.

Further, the semiconductor substrate is an SOI substrate, a predetermined film having a low etching rate for anisotropic etching by TMAH is formed on one surface of the semiconductor substrate, and the electrode is formed on the surface of the predetermined film. For the semiconductor acceleration sensor to be formed, the predetermined film is removed at a portion where the weight portion and the peripheral thick portion are separated, and after this removal, the difference between the separated portion of the semiconductor substrate due to TMAH is removed. Performing anisotropic etching, bonding the second cap to the semiconductor substrate after the anisotropic etching, and removing an oxide film remaining as the remaining portion of the SOI substrate in the separated portion by etching after the bonding. Then, a removing process for separating the weight portion and the peripheral thick portion is performed, and after the removing process, the semiconductor substrate of the first cap is removed. It may be a way of performing bonding to (claim 6). According to this method, by performing the removal processing after the bonding of the second cap, the surface side of the semiconductor substrate in the second cap can be protected from the etching for removing the oxide film.

According to a seventh aspect of the present invention, there is provided a semiconductor acceleration sensor manufactured by the method for manufacturing a semiconductor acceleration sensor according to the sixth aspect, wherein the second cap is provided on the semiconductor substrate at all or a part of three sides. Are bonded on one surface. According to this structure, the flow of the etchant for removing the oxide film and the like is improved, and the etching accuracy and the cleaning property can be improved.

Note that, of the three sides, a part of one side sandwiched therebetween is joined to one surface of the semiconductor substrate, and all the remaining two sides are joined to one surface of the semiconductor substrate. A bonding structure may be used (claim 8). According to this structure,
While maintaining the bonding strength of the second cap to the semiconductor substrate,
It is possible to improve the etching accuracy and the cleaning property.

Further, a structure may be employed in which a part of each of the three sides is joined to one surface of the semiconductor substrate.
According to this structure, it is possible to improve the etching accuracy and the cleanability while maintaining the bonding strength of the second cap to the semiconductor substrate.

Further, the three sides may be separated from each other and bonded to one surface of the semiconductor substrate. According to this structure, it is possible to improve the etching accuracy and the cleanability while maintaining the bonding strength of the second cap to the semiconductor substrate. Further, it is possible to improve the flow of the liquid in the corner portion.

According to an eleventh aspect of the present invention, there is provided a semiconductor acceleration sensor manufactured by the method for manufacturing a semiconductor acceleration sensor according to the sixth aspect, wherein the second cap has one side of the semiconductor substrate at two sides facing each other. Are bonded on the surface. According to this structure, the flow of the etchant for removing the oxide film and the like is further improved, and the etching accuracy and the cleaning property can be improved.

In the invention described in claim 7, the second cap may have a structure in which a hole is formed (claim 1).
2). According to this structure, it is possible to more effectively maintain the bonding strength of the second cap to the semiconductor substrate while improving the etching accuracy and the cleaning property.

The holes may be formed at four corners of the second cap (claim 13). According to this structure, it is possible to improve the flow of the liquid in the corner portion.

[0027]

FIG. 1 is a view schematically showing a cross-sectional structure of a semiconductor acceleration sensor in a manufacturing process according to a method of manufacturing a semiconductor acceleration sensor according to a first embodiment of the present invention.
The first embodiment will be described below with reference to FIG.

First, the semiconductor acceleration sensor 10 to be manufactured is
The structure of the semiconductor acceleration sensor 10 will be described.
As shown in FIG. 1 (c), the thick weight portion 111,
Peripheral thick portion 112 provided separately around weight portion 111, and peripheral thick portion 112 and weight portion 111
And an n-type silicon wafer (semiconductor substrate) 11 having a thin flexible portion 113 for supporting the weight portion 111 suspended between the silicon wafer 11 and the flexible portion 113 of the silicon wafer 11.
A gauge resistor 12 formed on the upper surface of the silicon wafer 11, a silicon oxide film 13 formed on the upper surface of the silicon wafer 11, a silicon nitride film 14 formed on the upper surface of the silicon oxide film 13, and an upper surface of the silicon wafer 11. The wiring electrode 15 and the bonding electrode 16 formed on the upper surface of the silicon nitride film 14, the concave lower cap 17 (first cap) bonded on the lower surface of the silicon wafer 11, and the bonding electrode 16 With the concave upper cap 18 (second cap) joined to the upper surface of the silicon wafer 11, the configuration is the same as that of the semiconductor acceleration sensor shown in FIGS.

Next, a method of manufacturing the present semiconductor acceleration sensor will be described. First, a gauge resistor 12 is formed on the upper surface of a silicon wafer 11 by P-type impurity diffusion, and thereafter, a silicon oxide film is formed on both surfaces of the silicon wafer 11. 13
To form a silicon nitride film 14 (FIG. 1).
8 (a)).

Next, resist patterning and etching are performed on the silicon oxide film 13 and the silicon nitride film 14 on the lower surface of the silicon wafer 11, and using this as a mask, anisotropic etching is performed from below the silicon wafer 11 using KOH. The area corresponding to the bent portion 113 and the separated portion S in the silicon wafer 11 is
Thin to about μm. Next, a contact window is formed and the wiring electrode 15 and the bonding electrode 16 are formed. After this,
Silicon oxide film 13 remaining on the lower surface of silicon wafer 11
Then, the silicon nitride film 14 is removed by etching (see FIG. 18B).

Next, the lower cap 17 is bonded to the silicon wafer 11 (see FIG. 1A).

Next, the weight portion 111 and the peripheral thick portion 112
Is performed so as to separate them from each other while leaving the bending portion 113.
That is, the silicon oxide film 13, the silicon nitride film 14, and the silicon wafer 11 in the separated portion S are removed by resist patterning, etching, and resist removal (see FIG. 1B). Here, the lower cap 17
Since the downward movement of the weight portion 111 is restricted by this, unnecessary excessive stress (force) applied to the thin bending portion 113 can be reduced.

Next, the upper cap 18 is bonded to the silicon wafer 11 (see FIG. 1C).

As described above, according to the first embodiment, the weight 11
By bonding the lower cap 17 to the silicon wafer 11 before the removal process for separating the first and peripheral thick portions 112 from each other, it is possible to reduce unnecessary excessive stress applied to the thin bent portion 113 in the manufacturing process. Becomes possible.

FIG. 2 is a diagram schematically showing a cross-sectional structure of a semiconductor acceleration sensor in a manufacturing process according to a method for manufacturing a semiconductor acceleration sensor according to a second embodiment of the present invention. Will be described. However, the second
The semiconductor acceleration sensor to be manufactured in the embodiment is the first semiconductor acceleration sensor.
It is assumed that this is the same as the embodiment.

First, the silicon wafer 1 of the lower cap 17
The steps up to the joining to 1 are performed in the same steps as in the first embodiment (see FIG. 2A).

Thereafter, the silicon oxide film 13 in the space S between the weight portion 111 and the peripheral thick portion 112 is formed by resist patterning, etching and resist removal.
Then, the two layers (predetermined film) of the silicon nitride film 14 are removed (see FIG. 2B).

Next, using each material of the silicon oxide film 13, the silicon nitride film 14, the wiring electrode 15, and the bonding electrode 16 as a mask, the silicon at the separated portion S in the silicon wafer 11 is TMAH (tetramethyl ammoniu).
By performing anisotropic etching with m-hydroxide, a removal process for separating the weight portion 111 and the peripheral thick portion 112 is performed (see FIG. 2C). At this time, since the respective materials of the silicon oxide film 13, the silicon nitride film 14, the wiring electrode 15, and the bonding electrode 16 have a lower etching rate than silicon, the silicon in the separated portion S in the silicon wafer 11 is selectively removed. be able to.

Next, the upper cap 18 is bonded to the silicon wafer 11 (see FIG. 2D).

As described above, according to the second embodiment, it is possible to reduce unnecessary excessive stress applied to the thin bent portion 113 in the manufacturing process, and to remove the resist before the removal process. Is set, it is possible to prevent the resist material and the cleaning liquid from flowing under the weight portion 111.

FIG. 3 is a diagram schematically showing a cross-sectional structure of a semiconductor acceleration sensor in a manufacturing process according to a method of manufacturing a semiconductor acceleration sensor according to a third embodiment of the present invention. Will be described. However, the third
The semiconductor acceleration sensor to be manufactured in the embodiment is the first semiconductor acceleration sensor.
It is assumed that this is the same as the embodiment.

Up to the removal of the silicon oxide film 13 and the silicon nitride film 14 remaining on the lower surface of the silicon wafer 11 by etching, the same steps as in the first embodiment are performed (see FIG. 3A).

Thereafter, the silicon oxide film 13 in the space S between the weight portion 111 and the peripheral thick portion 112 is formed by resist patterning, etching and resist removal.
3 and the silicon nitride film 14 are removed (FIG.
(B)).

Next, the lower cap 17 is bonded to the silicon wafer 11 (see FIG. 3C).

Next, using the materials of the silicon oxide film 13, the silicon nitride film 14, the wiring electrode 15 and the bonding electrode 16 as masks, anisotropic etching by TMAH is performed on the silicon in the separated portion S of the silicon wafer 11 by using TMAH. Is performed to perform a removal process for separating the weight portion 111 and the peripheral thick portion 112 (see FIG. 3D).

Next, the upper cap 18 is bonded to the silicon wafer 11 (see FIG. 3E).

As described above, according to the third embodiment, it is possible to reduce unnecessary excessive stress applied to the thin bent portion 113 in the manufacturing process, and to perform a patterning process before joining the lower cap 17. By setting
A semiconductor acceleration sensor can be manufactured by a manufacturing process similar to the conventional one.

FIG. 4 is a diagram schematically showing a cross-sectional structure of a semiconductor acceleration sensor in a manufacturing process according to a method for manufacturing a semiconductor acceleration sensor according to a fourth embodiment of the present invention. Will be described.

First, the semiconductor acceleration sensor 20 to be manufactured is
The structure of the semiconductor acceleration sensor 20 will be described.
Has a cross-sectional structure similar to that of the semiconductor acceleration sensor 10 except that the SOI wafer 21 on which the oxide film 210 is formed as an intermediate layer is used as a semiconductor substrate, as shown in FIG.

Next, a method of manufacturing the present semiconductor acceleration sensor will be described.
The gauge resistor 12 is formed on the upper surface of the I wafer 21. Thereafter, the silicon oxide film 13 is formed on both surfaces of the SOI wafer 21 and the silicon nitride film 14 is further formed (FIG. 18).
(See (a)).

Next, resist patterning and etching are performed on the silicon oxide film 13 and the silicon nitride film 14 on the lower surface of the SOI wafer 21, and using this as a mask, anisotropic etching is performed from below the SOI wafer 21 with KOH. Thus, the region corresponding to the bent portion 113 and the separated portion S of the SOI wafer 21 is thinned to about 10 μm. Next, a contact window is formed and the wiring electrode 15 and the bonding electrode 16 are formed. After this, SOI
The silicon oxide film 13 and the silicon nitride film 14 remaining on the lower surface of the wafer 21 are removed by etching (FIG. 18).
(B)).

Next, the SOI wafer 2 of the lower cap 17
1 is joined to the lower surface (see FIG. 4A).

Next, the silicon oxide film 13 in the space S between the weight portion 111 and the peripheral thick portion 112 is formed by resist patterning, etching and resist removal.
4 and the silicon nitride film 14 are removed (FIG. 4).
(B)).

Next, using the materials of the silicon oxide film 13, the silicon nitride film 14, the wiring electrode 15, and the bonding electrode 16 as masks, anisotropic etching with TMAH is used to remove silicon in the separated portion S of the SOI wafer 21. (See FIG. 4C). Here, since it is difficult to accurately determine the etching completion time of the anisotropic etching by TMAH, the etching time is generally set somewhat longer. With this setting, TMAH
In some embodiments, the semiconductor substrate is the SOI wafer 21, so that the lower surface of the bent portion 113 is etched by the intermediate layer oxide film 210. TMAH down
Wraparound is prevented.

Next, the weight portion 111 and the peripheral thick portion 112
Is carried out to separate. That is, the separated portion S
Oxide film 210 remaining on SOI wafer 21 in FIG.
Is removed by etching with a mixed solution of hydrofluoric acid and ethylene glycol (see FIG. 4D). This mixture
Since the etching rate of the oxide film (silicon oxide film) 210 is higher than that of the silicon nitride film 14, the wiring electrode 15, and the bonding electrode 16, the oxide film 210 in the separated portion S of the SOI wafer 21 is selectively removed. Can be.

Next, the SOI wafer 2 of the upper cap 18
1. Joining to the upper surface is performed (see FIG. 4E).

As described above, according to the fourth embodiment, the same effect as that of the first embodiment can be obtained, and the TMAH can be prevented from wrapping under the bending portion 113.

FIG. 5 is a diagram schematically showing a sectional structure of a semiconductor acceleration sensor in a manufacturing process according to a method of manufacturing a semiconductor acceleration sensor according to a fifth embodiment of the present invention. Will be described. However, the fifth
The semiconductor acceleration sensor to be manufactured in the embodiment is the fourth type.
It is assumed that this is the same as the embodiment.

The steps up to the removal of the silicon oxide film 13 and the silicon nitride film 14 remaining on the lower surface of the SOI wafer 21 by etching are performed in the same steps as in the fourth embodiment.

Thereafter, the silicon oxide film 13 in the space S between the weight portion 111 and the peripheral thick portion 112 is formed by resist patterning, etching and resist removal.
And the silicon nitride film 14 is removed (FIG. 5).
(See (a)).

Next, using the respective materials of the silicon oxide film 13, the silicon nitride film 14, the wiring electrode 15, and the bonding electrode 16 as a mask, the silicon in the separated portion S of the SOI wafer 21 is removed by anisotropic etching using TMAH. (See FIG. 4B). At this time, since the lower layer of the bending portion 113 is the oxide film 210, the bending portion 113
Protected from anisotropic etching by H.

Next, the SOI wafer 2 of the lower cap 17
1 is joined to the lower surface (see FIG. 5C).

Next, the weight portion 111 and the peripheral thick portion 112
Is carried out to separate. That is, the separated portion S
Oxide film 210 remaining on SOI wafer 21 in FIG.
Is removed by etching with a mixed solution of hydrofluoric acid and ethylene glycol (see FIG. 5D). Here, until the above-described removal processing is performed, the movement of the weight portion 111 is not
Since it is limited by 0, it becomes possible to reduce unnecessary excessive stress applied to the thin-walled bent portion 113.

Next, the SOI wafer 2 of the upper cap 18
1. Bonding to the upper surface is performed (see FIG. 5E).

As described above, according to the fifth embodiment, it is possible to reduce unnecessary excessive stress applied to the thin bending portion 113 in the manufacturing process, and to reduce the lower cap 1.
It is not necessary to perform anisotropic etching by TMAH after the bonding of No. 7.

FIG. 6 is a view schematically showing a cross-sectional structure of a semiconductor acceleration sensor in a manufacturing process according to a method of manufacturing a semiconductor acceleration sensor according to a sixth embodiment of the present invention. Will be described. However, the sixth
The semiconductor acceleration sensor to be manufactured in the embodiment is the fourth type.
It is assumed that this is the same as the embodiment.

Until the silicon in the separated portion S is removed by anisotropic etching using TMAH, the same steps as in the fifth embodiment are performed (see FIG. 6A).

Thereafter, the SOI wafer 2 of the upper cap 18
1. Joining to the upper surface is performed (see FIG. 6B). Until this bonding is performed, the movement of the weight portion 111 is restricted by the oxide film 210, so that unnecessary excessive stress applied to the thin flexible portion 113 can be reduced.

Next, the weight portion 111 and the peripheral thick portion 112
Is carried out to separate. That is, the separated portion S
Oxide film 210 remaining on SOI wafer 21 in FIG.
Is removed by etching with a mixed solution of hydrofluoric acid and ethylene glycol (see FIG. 6C). After this removal processing, the upward movement of the weight portion 111 is restricted by the upper cap 18, so that unnecessary excessive stress applied to the thin-walled bent portion 113 can be reduced.

Next, the SOI wafer 2 of the lower cap 17
1 is joined to the lower surface (see FIG. 6D).

As described above, according to the sixth embodiment, it is possible to reduce unnecessary excessive stress applied to the thin-walled bent portion 113 in the manufacturing process and to reduce the upper cap 1.
By performing the above-described removal processing after the bonding of No. 8, the upper cap 1
8, the upper surface of the SOI wafer 21 can be protected from the etching by the mixed solution.

FIG. 7 is a diagram schematically showing a cross-sectional structure of a semiconductor acceleration sensor according to an embodiment of the present invention manufactured by the method for manufacturing a semiconductor acceleration sensor according to the sixth embodiment, and FIG. 7 is a front view of the semiconductor acceleration sensor in the process of manufacture, (b) is a diagram schematically showing a cross-sectional structure taken along line BB of (a), and (c) is a diagram schematically showing a cross-sectional structure taken along line CC of (a). The semiconductor acceleration sensor according to the present embodiment will be described below with reference to the drawings.

The semiconductor acceleration sensor 30 of the present embodiment is
As shown in FIG. 7 and FIG. 8, the configuration is the same as that of the semiconductor acceleration sensor 20 except that an upper cap 38 that joins all three sides is provided on the upper surface of the SOI wafer 21.

That is, in the semiconductor acceleration sensor 20,
For example, as shown in FIG. 6, the upper cap 18 is formed in a box shape with a one-sided opening, and is joined to the upper surface of the peripheral thick portion 112 of the SOI wafer 21 at four sides, which are opening edges. In contrast, the semiconductor acceleration sensor 3 of the present embodiment
8, the upper cap 38 is formed in a shape in which one side wall (the left side wall in the example of FIG. 7) of the upper cap 18 is removed, and the SOI wafer 2 is formed on all three sides of the opening edge.
1 is joined to the upper surface of the peripheral thick portion 112, and after this joining, it is structured to open to one side (left side in the example of FIG. 7).

Next, the reason why the structure in which the upper cap 38 is opened on one side will be described. In the manufacturing method according to the sixth embodiment, after the etching and cleaning steps for the oxide film 210, the upper cap 18 shown in FIG.
There is a possibility that an etching solution or a cleaning solution remains between the I-wafer 21 and the remaining solution causes corrosion or the like. In particular, the outlet from which the etching liquid and the cleaning liquid can flow out is shown in FIG.
In the example shown in (c), it is limited to the separated portion S.

Therefore, if the upper cap 38 is joined to the upper surface of the SOI wafer 21 on all three sides,
The etching liquid and the cleaning liquid easily flow out from between the upper cap 18 and the SOI wafer 21 (see the arrow showing the example of the flow of the liquid in FIG. 8A), and the above-mentioned problem that the etching liquid and the cleaning liquid remain is solved. can do. However, in the example shown in FIG. 8A, the bonding electrode 16 also has a U-shape corresponding to the upper cap 38.

FIG. 9 is a front view of a semiconductor acceleration sensor according to another embodiment of the present invention manufactured by the method for manufacturing a semiconductor acceleration sensor according to the sixth embodiment. The semiconductor acceleration sensor will be described.

The semiconductor acceleration sensor 40 of the present embodiment is
Of the three sides, a part of one side sandwiched between the SOI wafer 2
1 and the remaining two sides are all S
The configuration is the same as that of the semiconductor acceleration sensor 30 except that an upper cap 48 is provided on the upper surface of the OI wafer 21 for bonding.

That is, the upper cap 48 has a structure in which a plurality of recesses are further formed on the right side wall edge corresponding to one side sandwiched between the upper cap 38 shown in FIG. In the example of FIG. 9, a plurality of recesses are formed at three locations indicated by circles.

If the upper cap 48 having such a structure is employed, the flow of the liquid on the upper surface side of the SOI wafer 21 becomes even better than that of the upper cap 38 (see arrows flowing in the left and right directions in FIG. 9). No etching liquid or cleaning liquid remains between the cap 48 and the SOI wafer 21.
As a result, it is possible to improve the etching accuracy and the cleanability while maintaining the bonding strength. However, in the example shown in FIG. 9, the bonding electrode 16 also has a shape corresponding to the upper cap 48 (a shape in which the right bonding electrode is discontinuous).

FIG. 10 is a front view of a semiconductor acceleration sensor according to another embodiment of the present invention manufactured by the method of manufacturing a semiconductor acceleration sensor according to the sixth embodiment. The semiconductor acceleration sensor will be described.

The semiconductor acceleration sensor 50 according to the present embodiment
The semiconductor acceleration sensor 30 is configured in the same manner as the semiconductor acceleration sensor 30 except that a part of each of the three sides is provided with an upper cap 58 bonded to the upper surface of the SOI wafer 21.

That is, the upper cap 58 has a structure in which a recess is further formed at the center of each side wall edge of the upper cap 58 to be joined to the upper surface of the SOI wafer 21 with respect to the upper cap 38 shown in FIG. (See the circle in FIG. 10).

When the upper cap 58 having such a structure is employed, the flow of the liquid on the upper surface side of the SOI wafer 21 becomes even better than that of the upper cap 38 (see arrows flowing in three directions in FIG. 10). And SOI wafer 21
The etching liquid and the cleaning liquid do not remain between them. As a result, it is possible to improve the etching accuracy and the cleanability while maintaining the bonding strength. However, in the example shown in FIG. 10, the bonding electrode 16 also has a shape (discontinuous shape) corresponding to the upper cap 58.

FIG. 11 is a front view of a semiconductor acceleration sensor according to another embodiment of the present invention manufactured by the method of manufacturing a semiconductor acceleration sensor according to the sixth embodiment. The semiconductor acceleration sensor will be described.

The semiconductor acceleration sensor 60 of this embodiment is
The semiconductor acceleration sensor 30 is configured in the same manner as the semiconductor acceleration sensor 30 except that each of the three sides is provided with an upper cap 68 that is separated from each other and joined to the upper surface of the SOI wafer 21.

That is, the upper cap 68 has a structure in which recesses are further formed in the respective corners of the side walls of the upper cap 68 which are joined to the upper surface of the SOI wafer 21 with respect to the upper cap 38 shown in FIG. (Fig. 11
Circle).

If the upper cap 68 having such a structure is employed, the flow of the liquid on the upper surface side of the SOI wafer 21 becomes even better than that of the upper cap 38 (see arrows flowing in two directions in FIG. 11). And SOI wafer 21
The etching liquid and the cleaning liquid do not remain between them. As a result, it is possible to improve the etching accuracy and the cleanability while maintaining the bonding strength. In particular, liquid accumulation at corners can be prevented. However, in the example shown in FIG. 11, the bonding electrode 16 also has a shape (discontinuous shape) corresponding to the upper cap 58.

FIG. 12 is a front view of a semiconductor acceleration sensor according to another embodiment of the present invention manufactured by the method of manufacturing a semiconductor acceleration sensor according to the sixth embodiment. The semiconductor acceleration sensor will be described.

The semiconductor acceleration sensor 70 of this embodiment is
The semiconductor acceleration sensor 30 is configured in the same manner as the semiconductor acceleration sensor 30 except that an upper cap 78 that is joined to the upper surface of the SOI wafer 21 at two sides facing each other is provided. That is, the upper cap 78 has a structure in which the right side wall is further removed from the upper cap 38 shown in FIG. 7 (see FIG. 12).

If the upper cap 78 having such a structure is employed, the flow of the liquid on the upper surface side of the SOI wafer 21 becomes even better than that of the upper cap 38 (see the arrow in FIG. 12), and the upper cap 78 and the SOI wafer 21 The etching liquid and the cleaning liquid do not remain between them. As a result, it is possible to improve the etching accuracy and the cleanability while maintaining the bonding strength. However, in the example shown in FIG. 12, the bonding electrode 16 also has a shape corresponding to the upper cap 58 (a straight line facing each other).

FIG. 13 is a view schematically showing a sectional structure of a semiconductor acceleration sensor according to another embodiment of the present invention manufactured by the method for manufacturing a semiconductor acceleration sensor according to the sixth embodiment. FIG. With reference to the front views of the semiconductor acceleration sensor shown, another embodiment of the semiconductor acceleration sensor of the present invention will be described below with reference to these drawings.

The semiconductor acceleration sensor 80 of the present embodiment is
The configuration is the same as that of the semiconductor acceleration sensor 30 except that the hole 881 includes an upper cap 88 formed on the upper surface side. That is, as shown in FIGS. 13 and 14, the upper cap 88 has a structure in which a rectangular hole 881 is further formed on the upper surface side of the upper cap 38 shown in FIG.

When the upper cap 88 having such a structure is employed, the flow of the liquid on the upper surface side of the SOI wafer 21 becomes even better than that of the upper cap 38, and the etching liquid or the like is provided between the upper cap 78 and the SOI wafer 21. No cleaning liquid remains. As a result, by joining all three sides of the upper cap 88, it is possible to improve the etching accuracy and the cleaning property while effectively maintaining the joining strength.

FIG. 15 is a view schematically showing a cross-sectional structure of a semiconductor acceleration sensor according to another embodiment of the present invention manufactured by the method for manufacturing a semiconductor acceleration sensor according to the sixth embodiment. FIG. With reference to the front views of the semiconductor acceleration sensor shown, another embodiment of the semiconductor acceleration sensor of the present invention will be described below with reference to these drawings.

The semiconductor acceleration sensor 90 of this embodiment is
Upper cap 9 having holes 981 formed at four corners of the upper surface, respectively.
8, except that the semiconductor acceleration sensor 30 is provided. That is, the upper cap 98 has a structure in which holes 981 are further formed at four corners of the upper surface as shown in FIGS. 13 and 14, respectively, with respect to the upper cap 38 shown in FIG.

When the upper cap 98 having such a structure is employed, the flow of the liquid on the upper surface side of the SOI wafer 21 becomes even better than that of the upper cap 38, and an etching solution or the like is provided between the upper cap 98 and the SOI wafer 21. No cleaning liquid remains. As a result, it is possible to improve the etching accuracy and the cleanability while maintaining the bonding strength. In particular, it is possible to prevent liquid accumulation at corners.

In each of the embodiments of the semiconductor acceleration sensor shown in FIGS. 7 to 16, the structure for improving the flow of the liquid is employed for the upper cap, but the same structure is applied to the lower cap. May be.

[0099]

As is apparent from the above description, according to the first aspect of the present invention, the thick weight portion, the peripheral thick portion provided separately from the periphery of the weight portion, and the peripheral portion are provided. A semiconductor substrate having a thin flexible portion suspended between a thick portion and the weight portion for supporting the weight portion, a gauge resistor formed in the flexible portion of the semiconductor substrate, and the semiconductor substrate An electrode for extracting an electric signal formed on one surface of the semiconductor substrate, a concave first cap bonded on another surface of the semiconductor substrate, and a concave cap bonded on one surface of the semiconductor substrate. A method for manufacturing a semiconductor acceleration sensor comprising a second cap, wherein one of the first and second caps is joined to the semiconductor substrate, and after the joining, the weight portion and the peripheral thick portion are joined together. Is removed, and the removal process is performed. Since the bonding to the first and the other of the semiconductor substrate of the second cap after, it is possible to weaken unnecessary excessive stress applied to the thin-walled flexible portion in the manufacturing process.

According to the second aspect of the present invention, the semiconductor substrate is made of silicon, and a predetermined film having a low etching rate for anisotropic etching by TMAH is formed on one surface of the semiconductor substrate. For the semiconductor acceleration sensor in which the electrode is formed on the surface of the first cap, the first cap is bonded to the semiconductor substrate, and after this bonding, the first cap is separated from the weighted portion and the peripheral thick portion in the separated portion. The removal of the predetermined film is performed, and after the removal, an anisotropic etching using TMAH is performed on the separated portion of the semiconductor substrate to perform a removal process of separating the weight portion and the peripheral thick portion. Since the second cap is bonded to the semiconductor substrate after the removing process, it is possible to prevent a member used for removing the predetermined film or the liquid from flowing under the weight portion. It is possible.

According to the third aspect of the present invention, the semiconductor substrate is made of silicon, and a predetermined film having a low etching rate for anisotropic etching by TMAH is formed on one surface of the semiconductor substrate. For the semiconductor acceleration sensor in which the electrode is formed on the surface of the first cap, the predetermined film is removed at a portion where the weight portion and the peripheral thick portion are separated from each other, and after this removal, the first cap is removed. By performing bonding to a semiconductor substrate and performing anisotropic etching by TMAH on the separated portion of the semiconductor substrate after this bonding, a removal process for separating the weight portion and the peripheral thick portion is performed. Since the bonding of the second cap to the semiconductor substrate is performed after the removing process, for example, patterning for removing a predetermined film after the bonding of the first cap is performed. Degree is not required.

According to the fourth aspect of the present invention, the semiconductor substrate is an SOI substrate, and a predetermined film having a low etching rate for anisotropic etching by TMAH is formed on one surface of the semiconductor substrate. For a semiconductor acceleration sensor in which the electrode is formed on a surface of a film, the first cap is joined to the semiconductor substrate, and after this joining, a separation portion between the weight portion and the peripheral thick portion is formed. After the removal, the anisotropic etching by TMAH is performed on the separated portion of the semiconductor substrate after the removal, and the remaining portion of the SOI substrate at the separated portion after the anisotropic etching. By removing the oxide film by etching, a removal process for separating the weight portion and the peripheral thick portion is performed, and after the removal process, the second key is removed. Since the said junction to the semiconductor substrate-up allows flexure of the thickness-decreased prevented.

According to the fifth aspect of the present invention, the semiconductor substrate is an SOI substrate, and a predetermined film having a low etching rate for anisotropic etching by TMAH is formed on one surface of the semiconductor substrate. For a semiconductor acceleration sensor in which the electrode is formed on the surface of a film, the predetermined film is removed at a portion where the weight portion and the peripheral thick portion are separated, and after the removal, the semiconductor film is removed from the semiconductor substrate. Anisotropic etching by TMAH is performed on the separated portion, and after the anisotropic etching, the first cap is bonded to the semiconductor substrate. After the bonding, the remaining portion of the SOI substrate in the separated portion is formed. By removing the oxide film by etching, a removal process for separating the weight portion and the peripheral thick portion is performed, and after the removal process, the second key is removed. Since the said junction to the semiconductor substrate-up, there is no need to perform an anisotropic etching with TMAH after bonding of the first cap.

According to the present invention, the semiconductor substrate is an SOI substrate, and a predetermined film having a low etching rate for anisotropic etching by TMAH is formed on one surface of the semiconductor substrate. For a semiconductor acceleration sensor in which the electrode is formed on the surface of a film, the predetermined film is removed at a portion where the weight portion and the peripheral thick portion are separated, and after the removal, the semiconductor film is removed from the semiconductor substrate. Anisotropic etching by TMAH is performed on the separated portion, and after the anisotropic etching, the second cap is bonded to the semiconductor substrate. After the bonding, the remaining portion of the SOI substrate in the separated portion is formed. By removing the oxide film by etching, a removal process for separating the weight portion and the peripheral thick portion is performed, and after the removal process, the first key is removed. Since the said junction to the semiconductor substrate-up, it is possible to protect the surface of the semiconductor substrate in the second inner cap from the etching of the oxide layer removed.

According to a seventh aspect of the present invention, there is provided a semiconductor acceleration sensor manufactured by the method of manufacturing a semiconductor acceleration sensor according to the sixth aspect, wherein the second cap is provided at all or a part of three sides thereof. Since the bonding is performed on one surface of the semiconductor substrate, the etching accuracy and the cleaning property can be improved.

According to the eighth aspect of the invention, of the three sides, a part of one side sandwiched between the three sides is joined to one surface of the semiconductor substrate, and all of the remaining two sides are the same. Since the bonding is performed on one surface of the semiconductor substrate, it is possible to improve the etching accuracy and the cleaning property while maintaining the bonding strength of the second cap to the semiconductor substrate.

According to the ninth aspect of the present invention, since a part of each of the three sides is bonded to one surface of the semiconductor substrate, the second cap can maintain the bonding strength to the semiconductor substrate. In addition, the etching accuracy and the cleaning property can be improved.

According to the tenth aspect of the present invention, the three sides are separated from each other and are bonded to one surface of the semiconductor substrate, so that the bonding strength of the second cap to the semiconductor substrate is maintained. At the same time, the etching accuracy and the cleaning property can be improved. Further, it is possible to improve the flow of the liquid in the corner portion.

According to the eleventh aspect, the sixth aspect is provided.
12. A semiconductor acceleration sensor manufactured by the method for manufacturing a semiconductor acceleration sensor according to claim 10, wherein the second cap is bonded to one surface of the semiconductor substrate at two sides facing each other, so that etching for removing an oxide film is performed. The flow of the liquid and the like is further improved, and the etching accuracy and the cleaning property can be improved.

According to the twelfth aspect of the present invention, the second
Since the cap is formed with the holes, the etching accuracy and the cleaning property can be improved while more effectively maintaining the bonding strength of the second cap to the semiconductor substrate.

According to the thirteenth aspect, since the holes are formed at the four corners of the second cap, it is possible to improve the flow of the liquid at the corners.

[Brief description of the drawings]

FIG. 1 is a view schematically showing a cross-sectional structure of a semiconductor acceleration sensor in a manufacturing process according to a method for manufacturing a semiconductor acceleration sensor according to a first embodiment of the present invention.

FIG. 2 is a diagram schematically illustrating a cross-sectional structure of a semiconductor acceleration sensor in a manufacturing process according to a method of manufacturing a semiconductor acceleration sensor according to a second embodiment of the present invention.

FIG. 3 is a view schematically showing a cross-sectional structure of the semiconductor acceleration sensor in a manufacturing process according to the method for manufacturing a semiconductor acceleration sensor according to the first embodiment of the present invention.

FIG. 4 is a diagram schematically illustrating a cross-sectional structure of a semiconductor acceleration sensor in a manufacturing process according to a method of manufacturing a semiconductor acceleration sensor according to a fourth embodiment of the present invention.

FIG. 5 is a diagram schematically illustrating a cross-sectional structure of a semiconductor acceleration sensor in a manufacturing process according to a method of manufacturing a semiconductor acceleration sensor according to a fifth embodiment of the present invention.

FIG. 6 is a diagram schematically showing a cross-sectional structure of a semiconductor acceleration sensor in a manufacturing process according to a method for manufacturing a semiconductor acceleration sensor according to a sixth embodiment of the present invention.

FIG. 7 is a diagram schematically illustrating a cross-sectional structure of a semiconductor acceleration sensor according to an embodiment of the present invention manufactured by a method of manufacturing a semiconductor acceleration sensor according to a sixth embodiment.

8A is a front view of the semiconductor acceleration sensor in the course of manufacture shown in FIG. 7, FIG. 8B is a diagram schematically showing a cross-sectional structure taken along the line BB of FIG. 7A, and FIG. It is a figure which shows the cross-sectional structure in CC line typically.

FIG. 9 is a front view of a semiconductor acceleration sensor according to another embodiment of the present invention manufactured by the method of manufacturing a semiconductor acceleration sensor according to the sixth embodiment.

FIG. 10 is a front view of a semiconductor acceleration sensor according to another embodiment of the present invention manufactured by the method for manufacturing a semiconductor acceleration sensor according to the sixth embodiment.

FIG. 11 is a front view of a semiconductor acceleration sensor according to another embodiment of the present invention manufactured by the method of manufacturing a semiconductor acceleration sensor according to the sixth embodiment.

FIG. 12 is a front view of a semiconductor acceleration sensor according to another embodiment of the present invention manufactured by the method of manufacturing a semiconductor acceleration sensor according to the sixth embodiment.

FIG. 13 is a diagram schematically illustrating a cross-sectional structure of a semiconductor acceleration sensor according to another embodiment of the present invention manufactured by the method of manufacturing a semiconductor acceleration sensor according to the sixth embodiment.

14 is a front view of the semiconductor acceleration sensor shown in FIG.

FIG. 15 is a diagram schematically showing a cross-sectional structure of a semiconductor acceleration sensor according to another embodiment of the present invention manufactured by the method for manufacturing a semiconductor acceleration sensor according to the sixth embodiment.

16 is a front view of the semiconductor acceleration sensor shown in FIG.

FIG. 17 is a plan view of a conventional semiconductor acceleration sensor.

18 is a diagram schematically showing a cross-sectional structure in a manufacturing process of the semiconductor acceleration sensor shown in FIG.

[Explanation of symbols]

10, 20, 30, 40, 50, 60, 70, 80, 9
Reference Signs List 0 semiconductor acceleration sensor 11 silicon wafer 12 gauge resistor 13 silicon oxide film 14 silicon nitride film 15 wiring electrode 16 bonding electrode 17 lower cap 18, 38, 48, 58, 68, 78, 88, 98 upper cap 111 weight 112 peripheral meat Thick part 113 Flexure part

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroshi Saito 1048 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Works, Ltd. 72) Inventor Masashi Kataoka 1048 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Works Co., Ltd. 1048, Kadoma, Kadoma, Fumonma-shi Matsushita Electric Works Co., Ltd. F-term (reference) 4M112 AA02 BA01 CA23 CA36 DA04 DA12 DA18 EA02 EA18 GA01

Claims (13)

[Claims] 1. A thick weight portion, a peripheral thick portion provided to be spaced around the weight portion, and suspended between the peripheral thick portion and the weight portion to support the weight portion. A semiconductor substrate having a thin-walled bent portion formed thereon, a gauge resistor formed at a bent portion of the semiconductor substrate, an electrode for extracting an electric signal formed on one surface of the semiconductor substrate, and the semiconductor A method for manufacturing a semiconductor acceleration sensor, comprising: a concave first cap bonded to another surface of a substrate; and a concave second cap bonded to one surface of the semiconductor substrate, One of the first and second caps is joined to the semiconductor substrate, and after this joining, a removing process for separating the weight portion and the peripheral thick portion is performed. After the removing process, the first and second caps are removed. The other semiconductor substrate of the cap The method of manufacturing a semiconductor acceleration sensor for bonding. 2. The semiconductor substrate is made of silicon,
For a semiconductor acceleration sensor in which a predetermined film having a low etching rate for anisotropic etching by TMAH is formed on one surface of the semiconductor substrate, and the electrode is formed on the surface of the predetermined film, the first film is used. The cap is bonded to the semiconductor substrate, and after this bonding, the predetermined film is removed at a distance between the weight portion and the peripheral thick portion.After the removal, the predetermined film is removed from the semiconductor substrate at the distance. And performing an anisotropic etching by TMAH to remove the weight portion from the peripheral thick portion, and bonding the second cap to the semiconductor substrate after the removing process. 2. A method for manufacturing the semiconductor acceleration sensor according to 1. 3. The semiconductor substrate is made of silicon,
For a semiconductor acceleration sensor in which a predetermined film having a low etching rate with respect to anisotropic etching by TMAH is formed on one surface of the semiconductor substrate and the electrode is formed on the surface of the predetermined film, the weight portion may be used. And removing the predetermined film in a portion separated from the peripheral thick portion, and after the removal, bonding the first cap to the semiconductor substrate. After the bonding, the first cap is bonded to the separated portion in the semiconductor substrate. And performing an anisotropic etching by TMAH to remove the weight portion from the peripheral thick portion, and bonding the second cap to the semiconductor substrate after the removing process. 2. A method for manufacturing the semiconductor acceleration sensor according to 1. 4. The semiconductor substrate according to claim 1, wherein said semiconductor substrate is an SOI substrate,
A predetermined film having a low etching rate for anisotropic etching by MAH is formed on one surface of the semiconductor substrate;
For the semiconductor acceleration sensor in which the electrode is formed on the surface of the predetermined film, the first cap is joined to the semiconductor substrate, and after this joining, the weight portion and the peripheral thick portion are joined together. Performing the removal of the predetermined film in the separated portion;
After the removal, the anisotropic etching by TMAH is performed on the separated portion of the semiconductor substrate, and after the anisotropic etching, the SOI at the separated portion is removed.
By removing the oxide film that is the remaining portion of the substrate by etching, a removal process for separating the weight portion and the peripheral thick portion is performed. After the removal process, bonding of the second cap to the semiconductor substrate is performed. The method for manufacturing a semiconductor acceleration sensor according to claim 1, wherein the method is performed. 5. The semiconductor device according to claim 1, wherein the semiconductor substrate is an SOI substrate,
A predetermined film having a low etching rate for anisotropic etching by MAH is formed on one surface of the semiconductor substrate;
For a semiconductor acceleration sensor in which the electrode is formed on the surface of the predetermined film, the predetermined film is removed at a portion where the weight portion and the peripheral thick portion are separated, and after this removal, the semiconductor substrate is removed. TMA for the separated part in
H, anisotropic etching is performed, and after the anisotropic etching, the first cap is bonded to the semiconductor substrate. After the bonding, the SOI at the separated portion is removed.
By removing the oxide film that is the remaining portion of the substrate by etching, a removal process for separating the weight portion and the peripheral thick portion is performed. After the removal process, bonding of the second cap to the semiconductor substrate is performed. The method for manufacturing a semiconductor acceleration sensor according to claim 1, wherein the method is performed. 6. The semiconductor substrate according to claim 1, wherein said semiconductor substrate is an SOI substrate,
A predetermined film having a low etching rate for anisotropic etching by MAH is formed on one surface of the semiconductor substrate;
For a semiconductor acceleration sensor in which the electrode is formed on the surface of the predetermined film, the predetermined film is removed at a portion where the weight portion and the peripheral thick portion are separated, and after this removal, the semiconductor substrate is removed. TMA for the separated part in
H, anisotropic etching is performed, and after the anisotropic etching, the second cap is bonded to the semiconductor substrate. After the bonding, the SOI at the separated portion is removed.
By removing the oxide film that is the remaining portion of the substrate by etching, a removal process for separating the weight portion and the peripheral thick portion is performed. After the removal process, the first cap is bonded to the semiconductor substrate. The method for manufacturing a semiconductor acceleration sensor according to claim 1, wherein the method is performed. 7. A semiconductor acceleration sensor manufactured by the method for manufacturing a semiconductor acceleration sensor according to claim 6, wherein the second cap is provided on one surface of the semiconductor substrate in all or a part of three sides. A semiconductor acceleration sensor to be joined. 8. A part of one side sandwiched between the three sides is joined to one surface of the semiconductor substrate, and all the remaining two sides are joined to one surface of the semiconductor substrate. 8. The semiconductor acceleration sensor according to claim 7, wherein the sensor is joined. 9. The semiconductor acceleration sensor according to claim 7, wherein a part of each of the three sides is joined to one surface of the semiconductor substrate. 10. The semiconductor acceleration sensor according to claim 7, wherein each of the three sides is separated from each other and joined to one surface of the semiconductor substrate. 11. A semiconductor acceleration sensor manufactured by the method for manufacturing a semiconductor acceleration sensor according to claim 6, wherein the second cap is joined to one surface of the semiconductor substrate at two sides facing each other. Semiconductor acceleration sensor. 12. The semiconductor acceleration sensor according to claim 7, wherein the second cap has a hole. 13. The semiconductor acceleration sensor according to claim 12, wherein said holes are formed at four corners of said second cap.