JPH10111310A - Manufacture of semiconductor acceleration sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of efficiently manufacturing a semiconductor acceleration sensor of such constitution that protective members for suppressing excessive deformation of a thin-walled part is fixed to a peripheral thick-walled part. SOLUTION: A semiconductor acceleration sensor is provided with a detector 10 having at least a thin-walled part deformed in response to imparted acceleration and a peripheral thick-walled part formed around the thin-walled part, and protective members 50 fixed to the peripheral thick-walled part so as to suppress excessive deformation of the thin-walled part. In a method of manufacturing such a semiconductor acceleration sensor, each of the predetermined number of protective members 50 is placed on a placing base 60 in correspondence with a target area where the peripheral thick-walled part of each sensor is formed, and each of the protective members 50 placed on the placing base 60 is almost simultaneously jointed to the corresponding target area of peripheral thick-walled part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor acceleration sensor and a method for manufacturing the same.

[0002]

2. Description of the Related Art A semiconductor acceleration sensor is known as one of detectors used to grasp the movement of an object. A conventional semiconductor acceleration sensor has, for example, a configuration as shown in FIG. The semiconductor acceleration sensor includes a first substrate 10, a second substrate 20, a third substrate 30, and a fourth substrate 40, and has a four-layer structure. The first substrate 10 includes a central thick portion 14, a thin portion 13 formed around the central thick portion 14, and a peripheral thick portion 15 formed around the thin portion 13.
And functions as a detector for detecting acceleration. In the thin portion 13, a plurality of resistance portions 11 whose electric resistance changes according to the amount of bending of the thin portion 13 are formed at predetermined positions. On the lower surface of the central thick part 14,
The weight body 22 is joined. A support 21 is joined to the lower surface of the peripheral thick portion 15. The fourth substrate 40 is a pedestal for restricting the movement of the weight body 22. Weight 2
As shown in FIG. 2, 2 includes a second substrate portion 220 located on the detection body side and a third substrate portion 320 joined to the lower surface of the second substrate portion 220. The support 21 also
Similarly, a second substrate unit 210 located on the detection body side and a second
And a third substrate portion 310 joined to the lower surface of the substrate portion 210.

For example, when a lateral acceleration acts on the semiconductor acceleration sensor having such a configuration, the weight body 22 performs a rotational movement with reference to the center of the upper part of the central thick part 14. Accordingly, the thin portion 13 is deformed. Each resistance portion 11 embedded in the thin portion 13
Changes the electrical resistance according to the deformation. The acceleration sensor detects the change in the electric resistance,
The direction and magnitude of the acceleration are calculated.

On the other hand, when excessive lateral acceleration acts on the semiconductor acceleration sensor, as shown in FIG. 9A, the third substrate 320 of the weight body 22 and the support 2
The movement of the weight body 22 is restricted by the contact with the first third substrate portion 310. That is, the third substrate portion 32 of the weight body 22
The portion between the 0 side surface and the side surface of the third substrate portion 310 of the support 21 functions as a stopper gap of the weight body 22.

In the semiconductor acceleration sensor, the first substrate 10 is a silicon substrate, the second substrate 20 is a glass substrate, the third substrate 30 is a silicon substrate, and the fourth substrate 40
As a glass substrate.

That is, in the semiconductor acceleration sensor, when the weight body 22 and the support body 21 are separated from each other,
At the same time, the silicon substrate 30 having a lower cutting resistance than the glass substrate 20 is cut.

Therefore, as compared with an acceleration sensor of a type that cuts only the glass substrate 20, the stopper gap can be narrowed. If the stopper gap can be reduced, the movement of the weight body 22 can be more finely restricted.

[0008] However, this type of semiconductor acceleration sensor has a stopper function against excessive lateral acceleration, but when excessive acceleration acts in the vertical direction, as shown in FIG. In addition, there is a problem that the movement of the weight body 22 cannot be restricted.

Therefore, in the semiconductor acceleration sensor shown in FIG. 10, even when an excessive acceleration acts in the horizontal direction (see FIG. 10A), the acceleration in the vertical direction acts. (FIG. 10B) also includes a protection member 50 so that excessive deformation of the thin portion 13 can be suppressed. The protection member 50 is fixed to the peripheral thick portion 15.

[0010]

The semiconductor acceleration sensor shown in FIG. 10 is not usually manufactured one by one when manufacturing the semiconductor acceleration sensor. That is, a plurality of substrates as described above are bonded in advance and integrated, and a required number of semiconductor acceleration sensors are cut out from this.

Therefore, in manufacturing the semiconductor acceleration sensor, first, in order to obtain a plurality of detectors from one semiconductor substrate, a plurality of sets each including a thin portion and a peripheral thick portion are formed on the semiconductor substrate.

The protective members 50 are fixed one by one to the corresponding peripheral thick portions.

However, if the protection members 50 are fixed one by one as described above, the workability is poor and the cost is high.

In view of such problems, an object of the present invention is to efficiently produce a semiconductor acceleration sensor in which a protective member for suppressing excessive deformation of a thin portion is fixed to a peripheral thick portion. It is an object of the present invention to provide a method of manufacturing a semiconductor acceleration sensor, which is capable of:

[0015]

According to one aspect of the present invention, there is provided a thin portion deformed in response to an applied acceleration, and a peripheral thick portion formed around the thin portion. A manufacturing method for manufacturing a semiconductor acceleration sensor comprising: a detection body having at least a portion formed therein; and a protection member fixed to the peripheral thick portion and suppressing excessive deformation of the thin portion. A semiconductor acceleration for forming a set of the thin portion and the peripheral thick portion on the semiconductor substrate by the same number as the predetermined number in order to obtain a predetermined number of the detection bodies from one semiconductor substrate; In the method for manufacturing a sensor, before forming the thin portion and the peripheral thick portion, each of the protection members having the same number as the predetermined number is aligned with a target region where the peripheral thick portion is formed. On the mounting table Can each substantially simultaneously protecting member placed in the mounting table, a method of manufacturing a semiconductor acceleration sensor, characterized in that joined to the target area of the corresponding peripheral thick portion is provided.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for manufacturing a semiconductor acceleration sensor according to the present invention will be described below with reference to the drawings.

In this embodiment, first, a silicon substrate is prepared, and a silicon epitaxial layer is grown on the upper surface of the silicon substrate. Subsequently, for example, a silicon nitride film is formed on both sides of the substrate. The silicon nitride film on the back surface is subjected to an etching process (FIG. 1).
(Step (b)). For the formation of the silicon nitride film, for example, an LP-CVD technique (low-pressure chemical vapor deposition technique) can be used.

Thereafter, the silicon nitride film existing on the above-mentioned epitaxial layer is peeled off to expose the epitaxial layer. For example, a silicon oxide film is grown on the exposed epitaxial layer. The silicon oxide film is subjected to predetermined patterning using photolithography, and predetermined impurities are diffused into the epitaxial layer through the patterned silicon oxide film, and a plurality of resistance portions (specifically,
Piezoresistors) are formed at predetermined positions. A metal wire connected to a piezo resistor or the like is also wired at the same time. By changing the number and arrangement of the resistance parts, it is possible to detect any one to three axes of acceleration as an acceleration sensor. On the other hand, an etching mask pattern is formed on the silicon nitride film left on the back surface of the silicon substrate by photolithography.

The silicon substrate that has gone through the above steps is shown in FIG.
This is shown in FIG. Since each of the above steps is already well known, the description using the drawings is omitted, but the present invention is not limited to these steps. The above-mentioned silicon substrate is hereinafter referred to as a first substrate 1
Call it 0. Also, in FIG.
Denotes a resistance part, and 12 denotes an etching mask. The crystal plane of the first substrate (silicon substrate) 10 is (100), which is parallel to the plane A perpendicular to the plane of the drawing. FIG.
1 (a) and FIG. 1 (b) to FIG. 1 (e) to be described later, a portion corresponding to one sensor is extracted and illustrated. In the present embodiment, there are 84).

Next, etching is performed from the back surface of the first substrate 10 with a strong alkaline aqueous solution (for example, aqueous potassium hydroxide solution), and the etching is advanced to the back side of the epitaxial layer 16 in which the resistance portion 11 is embedded. FIG.
(B) shows a state in which the etching has been completed. The first substrate 10 has a central thick portion 14 and a peripheral thick portion 1.
5 and a thin portion 13 are formed. The detection circuit (not shown) including the resistance section 11 is protected by a predetermined jig during etching.

Subsequently, a substrate in which a glass substrate (second substrate) 20 and a silicon substrate (third substrate) 30 are bonded in advance is prepared, and this is bonded to the first substrate 10 by anodic bonding. The anodic bonding is a method in which a high voltage is applied between members to be bonded and both members are pressed and bonded. As shown in FIG. 1C, the second substrate 20 is in a state of being cut into the weight body portion 220 and the support portion 210 on the third substrate 30 in advance.

Subsequently, as shown in FIG. 1D, the protection member 50 is fixed to the peripheral thick portion 15. In FIG. 1, as described above, since attention is paid to the sensor alone, here,
Although only one protection member 50 is shown, in practice, such a fixing operation must be performed for each sensor.

Therefore, in this embodiment, the work of fixing the protection member 50 is efficiently performed using the mounting table 60 shown in FIG. FIG. 5A is a top view of the mounting table 60, and FIG.
Is a schematic sectional view of a central portion of the mounting table 60. FIG.
4A is a top view of the protection member 50, and FIG. 4B is a schematic cross-sectional view of a central portion of the protection member 50. Protection member 5
Reference numeral 0 denotes a glass member having a concave cross section (Pyrex glass in the present embodiment), as shown in both figures. Mounting table 60
The concave portion 60a in which each protection member 50 is disposed has
Are formed in a predetermined positional relationship. This positional relationship is determined in accordance with a region (a target region in claims) in which a peripheral thick portion of each sensor is to be formed on the first substrate 10. The material of the mounting table 60 is not limited as long as the mounting table 60 has a property of a small chemical bonding force to the protection member 50 which is a glass member. Therefore, the mounting table 60 may be manufactured using, for example, stainless steel or quartz glass.

Each of the 84 protection members 50 is shown in FIG.
As shown in FIG.

After the protection member 50 is disposed in each recess 60a, as shown in FIG.
0, 20, 30), the protection members 50 of the respective concave portions 60a are brought into close contact with the substrate group almost simultaneously, and anodic bonding is performed.

When such a joining operation is performed, not only can the plurality of protective members 50 be fixed to the first substrate 10 at the same time, but also the positioning operation of each protective member 50 (the operation of arranging the protective member 50 in each concave portion 60a). While performing, the substrate 1
0, the board | substrate 20, and the joining operation | work of the board | substrate 30 can be advanced.

After the joining operation of the protection member 50 is completed, FIG.
As shown in (e), a cutting operation of the third substrate 30 is performed. As a result, the weight body 22 and the support body 21 are completely separated from each other, but since the third substrate 30 is a silicon substrate, the cutting resistance is small, and cutting with a relatively thin dicing blade is possible. . The cut groove formed by the cutting functions as a stopper gap of the weight body 22 as it is. If the stopper gap can be narrowed, the fine movement of the weight body 22 can be restricted accordingly.

After the stopper gap is formed, a pedestal 40 made of glass or ceramics is joined to the back surface of the support 21. The pedestal 40 may be, for example, the mounting surface of the package in which the acceleration sensor is stored. The third substrate 30 and the fourth substrate 40 can be joined by an anodic bonding method.

FIG. 2 shows a semiconductor acceleration sensor completed through the above steps. FIG. 2A is a top view of the semiconductor acceleration sensor, and FIG. 2B is a cross-sectional view of the semiconductor acceleration sensor.

That is, the semiconductor acceleration sensor includes a detector 10, a weight 22, and a support 21. The detector 10 has a central thick portion 14, a thin portion 13 formed therearound, The weight body 22 is joined to the lower surface of the central thick portion 14, the support 21 is joined to the lower surface of the peripheral thick portion 15, and the thin portion 13 is formed around the thick portion 15.
Is formed with a resistance portion 11 whose electric resistance changes according to the amount of bending of the thin portion 13.

The protective member 50 is provided so as to face the thin portion 13 with a gap therebetween.
As shown in (a) and (b), when a large acceleration acts, the thin portion is brought into contact with the thin portion and excessive deformation of the thin portion is suppressed.

Next, another embodiment of the method for manufacturing a semiconductor acceleration sensor according to the present invention is shown in FIG. FIG. 3A has the same contents as FIG. 1A.

In this embodiment, before the peripheral thick portion 15, the central thick portion 14, and the thin portion 13 are formed on the first substrate 10, the protection member 50 is fixed (FIG. 3).
(B)). Of course, the protection member 50 may be fixed in this order. In fixing the protection member 50, the mounting table 60 shown in FIG. 5 will be used.

After the work of fixing the protection member 50 is completed, the peripheral thick portion 15, the central thick portion 14, and the thin portion 13 are formed on the first substrate 10 by etching, and then the second substrate 20 is formed.
The third substrate 30 is integrated with the peripheral thick portion 15 (the second substrate 20 is separated in advance into the weight body portion 220 and the support portion 210). Thereafter, the third substrate 30 is cut by a dicing blade as described above.

FIG. 3 (c) shows a semiconductor acceleration sensor having undergone these steps.

Thereafter, as shown in FIG. 3D, a fourth substrate 40 functioning as a pedestal is bonded to the third substrate 30.

With the above, the manufacture of the semiconductor acceleration sensor of the present embodiment is completed.

[0038]

According to the method of manufacturing a semiconductor acceleration sensor according to the present invention, it is possible to efficiently perform a work of joining a protective member for suppressing excessive deformation of a thin portion, thereby reducing manufacturing costs. Can be reduced.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing each manufacturing process of an embodiment of the present invention.

FIG. 2A is a top view of a semiconductor acceleration sensor completed through the respective manufacturing steps shown in FIG. FIG. 2B is a schematic cross-sectional view of the semiconductor acceleration sensor completed through the respective manufacturing steps shown in FIG.

FIG. 3 is an explanatory view showing each manufacturing process of another embodiment of the present invention.

FIG. 4 (a): a top view of a protective member used in each of the two embodiments of the present invention. FIG. 4B is a schematic sectional view of a protection member used in each of the two embodiments of the present invention.

FIG. 5 (a) is a top view of a mounting table used in a protection member joining operation performed in each of the two embodiments of the present invention. FIG. 5B is a schematic cross-sectional view of a mounting table used in the protection member joining operation performed in each of the two embodiments of the present invention.

FIG. 6 is an explanatory diagram showing a state where each protection member is actually arranged on a mounting table used in each of the two embodiments of the present invention.

FIG. 7 is an explanatory view schematically showing an operation of joining each protection member arranged on the mounting table of FIG. 6 to a substrate group.

FIG. 8 is a configuration diagram showing an example of a conventional semiconductor acceleration sensor.

FIG. 9A is an explanatory diagram showing the movement of the weight body when excessive lateral acceleration acts on the conventional semiconductor acceleration sensor shown in FIG. 8; FIG. 9B is an explanatory diagram showing the movement of the weight body when excessive vertical acceleration acts on the conventional semiconductor acceleration sensor shown in FIG. 8.

FIG. 10A is an explanatory diagram showing the movement of a weight body when excessive lateral acceleration acts on another conventional semiconductor acceleration sensor. FIG. 10B is an explanatory diagram showing the movement of the weight body when excessive vertical acceleration acts on another conventional semiconductor acceleration sensor.

[Explanation of symbols]

 10: first substrate, 11: resistance portion, 12: etching mask, 13: thin portion, 14: central thick portion, 15: peripheral thick portion, 16: epitaxial layer, 20: second substrate, 21: support Reference numeral 22: weight, 30: third substrate, 40: fourth substrate, 210: second substrate portion of the support, 220: second substrate portion of the weight, 310: third substrate of the support, 320: third substrate part of the weight body

Claims (5)

[Claims] 1. A detector having at least a thin portion deformed in response to a given acceleration, a peripheral thick portion formed around the thin portion, and a detector fixed to the peripheral thick portion, A protection member for suppressing excessive deformation of the thin portion, and a manufacturing method for manufacturing a semiconductor acceleration sensor comprising: a predetermined number of the detection bodies from one semiconductor substrate; In a method of manufacturing a semiconductor acceleration sensor, wherein a set of a thin portion and the peripheral thick portion is formed on the semiconductor substrate by the same number as the predetermined number, before forming the thin portion and the peripheral thick portion, The same number of the protection members as the predetermined number is placed on a mounting table in accordance with a target area where the respective peripheral thick portions are formed, and each of the protection members placed on the mounting table is At about the same time,
A method for manufacturing a semiconductor acceleration sensor, wherein the semiconductor acceleration sensor is bonded to a target region of a corresponding peripheral thick portion. 2. A detector having at least a thin portion deformed in response to a given acceleration, a peripheral thick portion formed around the thin portion, and a detector fixed to the peripheral thick portion; A protection member for suppressing excessive deformation of the thin portion, and a manufacturing method for manufacturing a semiconductor acceleration sensor comprising: a predetermined number of the detection bodies from one semiconductor substrate; In the method of manufacturing a semiconductor acceleration sensor, wherein a set of a thin portion and the peripheral thick portion is formed on the semiconductor substrate by the same number as the predetermined number, the protection member having the same number as the predetermined number is provided. After placing the thin portion and the peripheral thick portion on the mounting table in accordance with the target area where each of the peripheral thick portions is formed, the protection members placed on the mounting table are substantially formed. At the same time, corresponding A method for manufacturing a semiconductor acceleration sensor, wherein the method is joined to a peripheral thick portion. 3. The method according to claim 1, wherein each of the protective members is a member having a concave cross section, and the mounting table has a plurality of concave portions in which the protective members are arranged. A method for manufacturing a semiconductor acceleration sensor. 4. The apparatus according to claim 1, wherein the protective member is formed of glass, and the mounting table is formed of a member having a small chemical bonding force to the glass. Of manufacturing a semiconductor acceleration sensor. 5. The weight body according to claim 1, 2, 3, or 4, wherein the semiconductor acceleration sensor further includes a weight and a support, the detection body further includes a central thick portion, Is connected to a lower surface of the central thick portion, the support is bonded to a lower surface of the peripheral thick portion, and the thin portion has a resistance whose electric resistance changes according to a bending amount of the thin portion. The manufacturing method of the semiconductor acceleration sensor characterized in that the portion is formed.