JP2001066319A - Semiconductor accelerometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a very small crack in which a wiring resistance is increased slightly and to detect a crack which is generated in a plumb hob part outside a cantilever. SOLUTION: A crack detecting interconnection 1 as a system separate from a bridge circuit constituted of a plurality of gage resistances 111a is installed with reference to an accelerometer chip 11. The chip 11 is formed in a shape wherein a chip body 110 comprising a hole 110a is provided, a pair of cantilevers 111 which are extended to the right side from the left of the hole 110a are provided, and a plumb hob part 112 which is formed integrally on tip sides of the respective cantilevers 111 and which is supported at the inside of one side is provided. The crack detecting interconnection is drawn inside the plumb hob 112 so as to be a state that it advances by a prescribed distance into the plumb hob 112 along the right and left directions from the boundary between the cantilever 111 in the lower part and the plumb hob 112, that it advances up to a position corresponding to the cantilever 111 in the upper part so as to be directed inward along the up-and-down directions at right angles to the right and left directions, and that it advances to the cantilever 111 in the upper part along the right and left directions.

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 detecting an acceleration by an electric signal proportional to the acceleration.

[0002]

2. Description of the Related Art FIG. 11 is a sectional view showing an example of a conventional semiconductor acceleration sensor, and FIG. 12 is a top view of the acceleration sensor chip shown in FIG.

The semiconductor acceleration sensor shown in FIG. 11 belongs to a so-called cantilever type, and has an acceleration sensor chip 91 formed by a silicon substrate 91a and an upper glass stopper 1 bonded on the upper surface of the acceleration sensor chip 91.
2 and the lower glass stopper 13 joined to the lower surface of the acceleration sensor chip 91. Note that W
Is a wire by wire bonding.

As shown in FIG. 11, the acceleration sensor chip 91 has a cross-sectional structure in which an oxide film 91b is laminated on an upper surface of a silicon substrate 91a, and a nitride film 91c is laminated thereon. As shown in FIG. 12, a chip body 910 having a rectangular hole 110a formed in a square shape and formed in the center thereof, and one direction from the left of the hole 110a in the chip body 910 (left and right in the figure) A pair of elastic cantilevers 111 extending to the right of the cantilever 111, and a weight portion 1 integrally formed on the distal end side of each of these cantilevers 111 and supported inside one side.
12 is formed.

[0005] In the example of FIG.
11, acceleration (α) of force (F) received by weight portion 112
= F / m; m is the mass of the weight portion 112), and two gauge resistors 111a are formed as sensing elements for taking out a voltage proportional to the output. On the other hand, on the left end side on the upper surface of the chip body 910, five pads 110b are arranged at regular intervals from each other so as to extend in a direction orthogonal to the one direction, that is, in FIG. I have. And the upper four pads 1 of them
10b denotes a plurality of gauge resistors 1 forming a bridge circuit.
11a is electrically connected. Specifically, each pad 110b connected to the bridge circuit is connected to a contact portion 110d via an aluminum wiring 110c, and each contact portion 110d is connected to a wiring 1 of the P + diffusion layer of the main body.
It is electrically connected to the gauge resistor 111a via 10e. Further, a diaphragm is formed on the lower surface side of the gauge resistor 111a (see FIG. 11).

FIGS. 13 and 14 show an enlarged view of a connection portion between each pad and the gauge resistor and a circuit configuration diagram of the connection portion, respectively. However, for identification, as shown in FIG. 13, for the four pads 110b connected to the bridge circuit, the symbols p1 to p4 in parentheses are used in order from the top, and the four gauge resistors 111a are used. For R1
Use ~ R4.

In the example of FIG. 13, the pad 110b (p1)
A gauge resistor 111a through an aluminum wiring 110c, a contact 110d and a wiring 110e of a P + diffusion layer.
(R1) and 111a (R4).
Similarly, the pad 110b (p4) is
c, contact portion 110d and wiring 11 of P + diffusion layer
Gauge resistance 111a (R2), 111a
(R3). The other end of the gauge resistor 111a (R1) is connected to the wiring 110 of the P + diffusion layer.
e, a contact 110d and a pad 110b (p2) via a contact 110d and an aluminum wiring 110c.
11a (R2) and 111a (R4) are connected to a separate P + diffusion layer wiring 110e and a common contact 110, respectively.
d and pad 110b via aluminum wiring 110c
(P3). Also, the gauge resistance 111a
The other end of (R3) is connected to a contact 110d on the pad 110b (p2) side via a wiring 110e of a P + diffusion layer, a contact 110d, and an aluminum wiring 110c. Therefore, the circuit constituted by these connections becomes the bridge circuit shown in FIG.
A constant voltage source is connected to (p1) and 110b (p4), and pads 110b (p2) and 110b (p3) are connected to R1 to R4.
Is an output terminal that outputs a voltage that fluctuates according to a change in the resistance value.

Returning to FIG. 11, the upper glass cap 12
Is made of heat-resistant glass having a thermal expansion coefficient substantially equal to that of the silicon substrate, and is formed in a plate-like shape having a concave portion 12 a in the center of the lower surface facing the acceleration sensor chip 91. Similarly, the lower glass cap 13
Is made of heat-resistant glass having a thermal expansion coefficient substantially equal to that of the silicon substrate, and is formed in a plate-like shape having a concave portion 13 a in the center of the upper surface facing the acceleration sensor chip 91. In the bottom surfaces of the concave portions 12a and 13a of the upper glass cap 12 and the lower glass cap 13 facing the acceleration sensor chip 11, projections 12 for regulating the movement of the weight portion 112 when receiving acceleration.
b and 13b are formed two each.

Next, a method of manufacturing a semiconductor acceleration sensor having the above structure will be described. First, a silicon single crystal wafer having a (100) crystal plane is oxidized to form an oxide film, and then the cantilever 111 and the weight are formed. Only the oxide film in the region where the portion 112 is to be formed is removed by photolithography.
Subsequently, silicon is etched using the oxide film as an etching mask. At this time, the etching depth is generally set to about 6 to 30 μm.

Thereafter, an oxidation process is performed again to form a P + diffusion layer for making contact with aluminum.
Subsequently, two gauge resistors (diffusion gauge resistors) 111a are formed on the two cantilevers 111 by ion implantation so as to form a bridge structure with each other.

Thereafter, the P connected to the gauge resistor 111a
The aluminum wiring 110c connects between the contact portion 110d of the + diffusion wiring 110e and the pad 110b corresponding to the contact portion 110d. And each pad 11
0b, the power supply wiring of the external terminal, and the output wiring are connected by wire bonding.

After that, passivation is performed with a nitride film as a protective film for the aluminum wiring 110c. Subsequently, an aluminum thin film 110f to be joined to the upper glass stopper 12 is formed, and the nitride film of the protective film is passivated. Then, the cantilever 111 is thinned from the back surface of the acceleration sensor chip 91 by alkali anisotropic etching, and a slit-shaped hole is formed around the weight portion 112 while leaving a pair of cantilevers 111. After this, the pad 110b,
The nitride film formed on the aluminum wiring 110c and the aluminum thin film is removed.

The upper glass stopper 12 is provided on the upper and lower surfaces of the acceleration sensor chip 91 thus configured.
Then, the lower glass stopper 13 is bonded by anodic bonding.

As a result, an air damping structure is formed, so that the cantilever 111 can be prevented from being broken (broken) when subjected to excessive acceleration. In the example of FIG.
The wiring 110e of the P + diffusion layer on the side of the pads 110b (p1) and 110b (p4) is connected to the upper cantilever 1 respectively.
11 and the lower cantilever 111, the cantilever 11 as shown in FIGS.
1 can be detected. As a result, it is possible to provide a semiconductor acceleration sensor which can be used for detecting acceleration of an airbag of an automobile, has high reliability, and has a failure diagnosis function capable of clearly determining the cause of failure.

A semiconductor acceleration sensor of this type is disclosed, for example, in Japanese Patent Application Laid-Open No. Hei 9-166618.

[0016]

However, FIG.
In the wiring structure as shown in the figure, if the crack is very small without breaking, that is, if the wiring resistance slightly increases in the state where there is a risk of breaking if shock or vibration is applied in the future, Since the increase can only be regarded as a slight change in the offset voltage of the bridge circuit,
It is not possible to determine whether it is due to an initial strain on the acceleration sensor chip or to a crack. Further, when a crack occurs in a weight portion outside the cantilever, the crack cannot be detected.

The present invention has been made in view of the above circumstances, and it is possible to detect a minute crack whose wiring resistance slightly increases and to detect a crack generated in a weight outside the cantilever. It is intended to provide a sensor.

[0018]

According to a first aspect of the present invention, there is provided a semiconductor acceleration sensor, comprising: a pair of elastic cantilevers extending in one direction; and a tip of each of these cantilevers. The acceleration sensor chip having a weight portion formed at the center and integrally formed on one side and supported on the inside on one side, and a pair of piezoresistors are formed on each of the pair of cantilevers, and these plural cantilevers are formed. A piezo resistor forms a bridge circuit, and is electrically connected to the plurality of piezo resistors at a predetermined position outside the weight portion in the acceleration sensor chip, and is connected to one of the systems separate from the bridge circuit. A plurality of electrode pads connected to the crack detection wiring are formed, and the crack detection wiring is formed of one of the plurality of electrode pads from one electrode pad side. While the pass through of the Chireba,
The wire is routed so as to enter the weight portion, passes through the other cantilever, and is in a wiring state reaching another electrode pad side.

In this structure, since one crack detection wiring of a different system from the bridge circuit is provided, by monitoring the increase in the resistance of the crack detection wiring, the wiring resistance may be slightly increased. Detection of minute cracks becomes possible. Further, since the crack detection wiring is routed so as to enter the weight portion, the crack generated in the weight portion outside the cantilever can be detected.

In the semiconductor acceleration sensor according to the first aspect of the present invention, the crack detection wiring is routed in the weight portion along the one direction from a boundary between the one cantilever and the weight portion. A predetermined distance, proceed inward along a direction orthogonal to the one direction to a position corresponding to the other cantilever, and may be in a state of facing the other cantilever along the one direction. (Claim 2). According to this (wiring) structure, it is possible to detect a crack in the cantilever and also to detect a crack around a communication portion with a weight outside the cantilever.

Further, in the semiconductor acceleration sensor according to the present invention, the wiring of the crack detection wiring in the weight portion may be performed in a direction orthogonal to the one direction from a vicinity of a boundary between the one cantilever and the weight portion. Proceed outward along the vicinity of the edge of the weight portion, advance along the one direction into the weight portion a predetermined distance, and inward along the orthogonal direction to the vicinity of another edge of the weight portion. The structure may be such that it advances, returns to the predetermined distance along the one direction, and faces the other cantilever along the orthogonal direction (claim 3). According to this structure, it is possible to detect a crack generated in the weight portion outside the cantilever more preferably than in the second aspect of the invention.

Further, in the semiconductor acceleration sensor according to the present invention, the crack detection wiring in the weight portion is routed from a vicinity of a boundary between the one cantilever and the weight portion in a direction orthogonal to the one direction. Proceeding outward along the vicinity of the corner of the weight portion, proceeding along the one direction to another corner of the weight portion, and proceeding along the orthogonal direction to another corner of the weight portion, A structure may be adopted in which the vehicle travels along one direction to the vicinity of another corner of the weight portion and is directed toward the other cantilever along the orthogonal direction (claim 4). According to this structure, it is possible to detect a crack generated in the weight portion outside the cantilever more suitably than the invention according to the third aspect.

Further, in the semiconductor acceleration sensor according to claim 1, the crack detection wiring in the weight portion extends from a vicinity of a boundary between the one cantilever and the weight portion in a direction orthogonal to the one direction. Advancing inward along the vicinity of the center between the pair of cantilevers, turning outward along the orthogonal direction and proceeding near the corner of the weight portion, and another corner of the weight portion along the one direction Proceed to the vicinity, proceed to the vicinity of another corner of the weight portion along the orthogonal direction, proceed to the vicinity of another corner of the weight portion along one direction, and along the direction orthogonal to the one direction. The structure may be such that it advances inward to near the center between the pair of cantilevers, turns outward along the orthogonal direction, and is directed toward the other cantilever. Section 5). According to this structure, a crack generated in the weight outside the cantilever can be detected more suitably than the invention described in claim 4.

[0024]

FIG. 1 is a top view of an acceleration sensor chip provided in a semiconductor acceleration sensor according to a first embodiment of the present invention, and FIG. 2 is a sectional view of the semiconductor acceleration sensor.
The first embodiment will be described with reference to these drawings.

As shown in FIG. 2, the present semiconductor acceleration sensor includes an acceleration sensor chip 11 formed of a silicon substrate 11a, an upper glass stopper 12 bonded on the upper surface of the acceleration sensor chip 11, And a lower glass stopper 13 joined to the lower surface of the lower glass 11. W is a wire formed by wire bonding.

As shown in FIG. 2, in the acceleration sensor chip 11, an oxide film (natural oxide film) 11b is laminated on an upper surface of a silicon substrate 11a, and a nitride film 1 is formed thereon.
1c is formed in a cross-sectional structure such as lamination, and as shown in FIG. 1, a rectangular hole 110 formed in a square shape (rectangular shape in the figure) and formed in the center.
a chip body 110 having a
And a pair of elastic cantilevers 111 extending to the right in one direction (left-right direction in the figure) from the left side of the hole 110a, and are integrally formed on the tip side of each of these cantilevers 111 and are formed inside one side. It is formed in a shape having a supported weight portion 112. However, since the rectangular hole 110a becomes a slit-shaped hole shown in FIG. 1 due to the presence of the pair of cantilevers 111 and the weight portion 112 therein, when the acceleration sensor chip 11 is manufactured, Needless to say, the slit-shaped holes may be formed.

In the example of FIG. 1, each cantilever 11
In FIG. 1, two gauge resistors 111a are formed as sensing elements for extracting, as an output, a voltage proportional to the acceleration of the force received by the weight portion 112. On the other hand, the left end on the upper surface of the chip body 110 is electrically connected to the plurality of gauge resistors 111a and is connected to a different system from the bridge circuit configured by the plurality of gauge resistors 111a.
A plurality (five in the example in the figure) of pads 110b (electrode pads) connected to the crack detection wiring 1 are spaced at regular intervals from each other along a direction orthogonal to the one direction, that is, in FIG. They are arranged along the direction. Each pad (pad for wire bonding) 110b connected to the bridge circuit is an aluminum wiring 110c.
, And each contact portion 110d is electrically connected to the gauge resistor 111a via the wiring 110e of the P + diffusion layer of the main body (see FIG. 2). The bridge circuit is configured in the same manner as in FIGS.

Further, an aluminum thin film 1 for bonding the upper glass cap 12 is provided outside the hole 110 a on the upper surface of the chip body 110, that is, on the bonding surface with the upper glass cap 12.
10f is formed. Similarly, an aluminum thin film (not shown) for bonding the lower glass cap 13 is formed on a bonding surface of the lower surface of the chip body 110 with the lower glass cap 13.

The upper glass cap 12 is made of heat-resistant glass having a thermal expansion coefficient substantially equal to that of the silicon substrate, and is formed in a plate-like shape having a concave portion 12a at the center of the lower surface facing the acceleration sensor chip 11. You. Similarly, the lower glass cap 13 is formed of a heat-resistant glass having a thermal expansion coefficient substantially equal to that of the silicon substrate in a plate-like shape having a concave portion 13a at the center of the upper surface facing the acceleration sensor chip 11. Be composed. As shown in FIG. 2, the movement of the weight 112 when receiving acceleration is restricted in the bottom surfaces of the concave portions 12 a and 13 a of the upper glass cap 12 and the lower glass cap 13 facing the acceleration sensor chip 11. Projection 12
b and 13b are formed two each. Each of these projections is set at a height lower than the depth of the recess. And
The upper glass cap 12 is fixed to the upper surface of the acceleration sensor chip 11 by anodic bonding on the four outer sides of the concave portion 12a via the aluminum thin film 110f. It is fixed to the lower surface of the sensor chip 11 by anodic bonding.

Here, a method of manufacturing the semiconductor acceleration sensor having the above structure will be described. First, a silicon single crystal wafer having a (100) crystal plane is oxidized to form an oxide film, and then the cantilever 111 and the weight are formed. Only the oxide film in the region where the portion 112 is to be formed is removed by photolithography.
Subsequently, silicon is etched using the oxide film as an etching mask. At this time, the etching depth is generally set to about 6 to 30 μm.

Thereafter, an oxidation process is performed again, and a P + diffusion layer is formed to make contact with aluminum.
Subsequently, two gauge resistors (diffusion gauge resistors) 111a are formed on the two cantilevers 111 by ion implantation so as to form a bridge structure with each other.

Thereafter, aluminum sputtering and sintering (about 450 ° C.) are performed to
b, an aluminum wiring 110c and an aluminum thin film are formed.
At this time, the contact portion 110 is connected to the P + (boron) diffusion wiring 110e connected to the gauge resistor 111a.
d, the aluminum wiring 110c is connected.
10c is a pad 11 formed on the acceleration sensor chip 11.
0b.

Thereafter, a nitride film or a resist is passivated on the aluminum, and the cantilever 111 is made thinner by alkali anisotropic etching from the back surface (lower surface) of the acceleration sensor chip 11, and the weight portion 1 is formed.
The slit-shaped hole described above is formed around pair 12 with a pair of cantilevers 111 left.

Thereafter, the pad 110b, the aluminum wiring 11
The nitride film or resist formed on Oc and the aluminum thin film is removed with a plasma asher, buffered hydrofluoric acid, an organic solvent, or the like.

Thereafter, the upper glass stopper 12 and the lower glass stopper 13 are bonded to the upper and lower surfaces of the acceleration sensor chip by anodic bonding, respectively. Accordingly, an air damping structure is formed, and it becomes possible to prevent the cantilever 111 from being broken (broken) when receiving excessive acceleration.

FIG. 3 is a diagram showing an example of a crack that can be detected by the crack detection wiring 1. The first example will be described with reference to FIG.
The wiring structure of the crack detection wiring 1 which is a feature of the embodiment will be described. The crack detection wiring 1 is the wiring 1 of the P + diffusion layer.
As shown in FIG. 1, as shown in FIG. 1, among the plurality of pads 110 b, the lowermost pad 110 b is routed so as to pass through the lower cantilever 111 and enter the weight portion 112, and A wiring state passing through the pad 111 and reaching the uppermost pad 110b side;
That is, the uppermost pad 110 via a high-concentration diffusion resistor (or a high-resistance polysilicon resistor) 110g, a contact portion 110d and an aluminum wiring 110c.
It is in the state of wiring connected to b. The crack detection wiring 1 in the weight portion 112 is routed from the boundary between the lower cantilever 111 and the weight portion 112.
A position corresponding to the upper cantilever 111 in the above-mentioned one direction, that is, in FIG. 1, travels a predetermined distance into the weight portion 112 in the left-right direction, and goes inward (upward in FIG. 1) along the up-down direction orthogonal to the left-right direction. To the upper cantilever 111 along the left-right direction. In the example of FIG. 1, the predetermined distance is set to a value that allows the crack detection wiring 1 to enter a position corresponding to the outer periphery of the bottom surface 112a of the weight portion 112. The crack detection wiring 1 may have a structure in which a part is formed of aluminum wiring. Needless to say, the system between the uppermost and lowermost pads 110b is separate from the bridge circuit.

As described above, by arranging the crack detection wiring 1 of a different system from the bridge circuit so as to cover a part of the weight portion 112 which is thinned by anisotropic etching and is liable to crack, for example, as shown in FIG. As shown in the figure, a crack C11 extending from near the boundary between the upper cantilever 111 and the weight 112 toward the center of the weight 112.
Or a crack C extending downward from between the pair of cantilevers 111 to a position slightly beyond the lower cantilever 111.
When 12 occurs, the crack detection wiring 1 is disconnected or its resistance value increases. Therefore, in the wiring example of FIG. 1, for example, by monitoring a voltage change between both the uppermost and lowermost pads 110b, the crack C11 is monitored. , C12 can be detected, and a crack can be detected around the communicating portion of the cantilever 111 with the weight portion 112. This makes it possible to detect a minute crack such that the wiring resistance of the crack detection wiring 1 slightly increases, and also to detect a crack generated in a weight portion outside the cantilever.

Further, since only four wires are required in each cantilever 111 (five in the conventional example of FIG. 13), the width of each cantilever 111 can be reduced, and the sensitivity of the semiconductor acceleration sensor can be improved. Become.

In the first embodiment, the lowermost pad 110b is used exclusively for the crack detection wiring 1, and the uppermost pad 110b is configured to be shared by the bridge circuit and the crack detection wiring 1. Not limited to this,
A structure in which two pads dedicated to the crack detection wiring 1 are provided in addition to the four pads for the bridge circuit may be used. FIG. 4 shows an example of this structure. The acceleration sensor chip 21 shown in FIG.
Has the same configuration as the acceleration sensor chip 11 except for the chip body 210. On the left end side on the upper surface of the chip body 210, one crack detection wiring 2 which is electrically connected to the plurality of gauge resistors 111a and which is separate from the bridge circuit formed by the plurality of gauge resistors 111a, Six pads 210b to be connected are arranged at equal intervals from each other and along the vertical direction. Of these six pads 210b, the uppermost and lowermost pads 21
0b is provided for the crack detection wiring 2, and the other four pads 210b are provided for the bridge circuit and are connected to the contact part 210d via the aluminum wiring 210c. It is electrically connected to the gauge resistor 111a via the wiring 210e of the diffusion layer. And the crack detection wiring 2 is P +
It is formed similarly to the wiring 210e of the diffusion layer, passes through the lower cantilever 111 from the lowermost pad 210b,
In the same manner as described above, the wiring is drawn so as to enter the weight portion 112, passes through the upper cantilever 111, and reaches the uppermost pad 210b, that is, the wiring connected to the uppermost pad 210b. With this structure, it is also possible to detect cracks around the communicating portion of the cantilever 111 with the weight portion 112 as described above. Further, such a structure is also applicable to the following second to fourth embodiments.

FIG. 5 is a top view of an acceleration sensor chip provided in a semiconductor acceleration sensor according to a second embodiment of the present invention, and FIG. 6 is a diagram showing an example of a crack that can be detected by the crack detection wiring shown in FIG. The second embodiment will be described with reference to these drawings.

The present semiconductor acceleration sensor includes an upper glass stopper 12 and a lower glass stopper 1 as in the first embodiment.
In addition to the configuration shown in FIG. 5, an acceleration sensor chip 31 is provided as a different point from the first embodiment.

The acceleration sensor chip 31 has a weight 1
The acceleration sensor chip 11 according to the first embodiment, except that the crack detection wiring 3 in which the wiring is different from that of the first embodiment is formed on the acceleration sensor chip 31.
It is configured similarly to. Therefore, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

The wiring structure of the crack detection wiring 3 which is a feature of the second embodiment will be described. The wiring of the crack detection wiring 3 in the weight portion 112 is performed from the vicinity of the boundary between the lower cantilever 111 and the weight portion 112. The weight 112 extends outward (downward) in a direction perpendicular to the above-described one direction, that is, in a vertical direction perpendicular to the horizontal direction in FIG.
Of the weight portion 112 along the left-right direction, proceeding in the vertical direction inward (upward) to the vicinity of another edge of the weight portion 112, and moving along the left-right direction. It returns to the predetermined distance and is in a state of heading toward the upper cantilever 111 along the vertical direction. In the example of FIG. 5, the predetermined distance is set to a value that allows the crack detection wiring 3 to enter a position corresponding to the outer periphery of the bottom surface 112 a of the weight portion 112.

As described above, the crack detection wiring 3 is routed so as to cover a part of the weight portion 112 which is thinned by the anisotropic etching and is liable to crack, and extends around both upper and lower ends of the weight portion 112. For example,
The racks C11 and C12 shown in FIG. 5 can be detected, and as shown in FIG.
1 from the corner of the weight 112 to the weight 112
When a crack C31 extending toward the center of
Since the crack detection wiring 3 is disconnected or its resistance value increases, the crack C31 can be detected.

FIG. 7 is a top view of an acceleration sensor chip provided in a semiconductor acceleration sensor according to a third embodiment of the present invention, and FIG. 8 is a diagram showing an example of a crack that can be detected by the crack detection wiring shown in FIG. The third embodiment will be described with reference to these drawings.

The present semiconductor acceleration sensor includes an upper glass stopper 12 and a lower glass stopper 1 as in the first embodiment.
7 and an acceleration sensor chip 41 as a difference from the first embodiment as shown in FIG.

The acceleration sensor chip 41 includes the weight 1
The acceleration sensor chip 11 according to the first embodiment is different from the first embodiment except that the crack detection wiring 4 in which the inside of the wiring 12 is different from that of the first embodiment is formed on the acceleration sensor chip 41.
It is configured similarly to. Therefore, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

To explain the wiring structure of the crack detection wiring 4 which is a feature of the third embodiment, the wiring of the crack detection wiring 4 in the weight portion 112 starts from the vicinity of the boundary between the lower cantilever 111 and the weight portion 112. The weight 112 extends outward (downward) in a direction perpendicular to the above-described one direction, that is, in a vertical direction perpendicular to the horizontal direction in FIG.
, Near the corner (lower left corner), along the left and right direction to near another corner (lower right corner) of the weight portion 112, along the up and down direction to near another corner (upper right corner) of the weight portion 112, The state progresses to the vicinity of another corner (upper left corner) of the weight portion 112 along the left-right direction, and is directed toward the upper cantilever 111 along the vertical direction.

As described above, by arranging the crack detection wiring 4 so as to go around the four corners of the weight portion 112, for example, the cracks C11 and C1 shown in FIGS.
8, C31 can be detected, and as shown in FIG. 8, when a crack C41 extending from the right end of the weight 112 facing the cantilevers 111 toward the upper end of the weight 112 is generated, a crack detection wiring 4 is disconnected or its resistance increases, so that the crack C41
Can be detected. The opposite side of the cantilever 111 in the weight portion 112 has a large stress that the upper and lower surfaces of the weight portion 112 contact the protrusion formed in the concave portion of the glass stopper, and the opposite side may be chipped when excessive acceleration or vibration is applied. However, it is possible to detect such chipping.

Further, since the crack detection wiring 4 is provided along the outer periphery of the weight portion 112, cracking and chipping, which are likely to occur particularly at the thin outer edge portion of the weight portion 112, as well as etching failure can be detected. .

FIG. 9 is a top view of an acceleration sensor chip provided in a semiconductor acceleration sensor according to a fourth embodiment of the present invention, and FIG. 10 is a diagram showing an example of a crack that can be detected by the crack detection wiring shown in FIG. , The fourth
An embodiment will be described.

The present semiconductor acceleration sensor includes an upper glass stopper 12 and a lower glass stopper 1 as in the first embodiment.
9 and an acceleration sensor chip 51 as a difference from the first embodiment as shown in FIG.

The acceleration sensor chip 51 includes the weight 1
The acceleration sensor chip 11 according to the first embodiment is different from the acceleration sensor chip 51 in that the crack detection wiring 5 in which the wiring is different from the first embodiment is formed on the acceleration sensor chip 51.
It is configured similarly to. Therefore, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

Therefore, the wiring structure of the crack detection wiring 5 which is a feature of the fourth embodiment will be described. The wiring of the crack detection wiring 5 in the weight 112 is carried out from the vicinity of the boundary between the lower cantilever 111 and the weight 112. In the direction perpendicular to the above-mentioned one direction, that is, in FIG. 9, in the vertical direction perpendicular to the left-right direction, the inward (upward) inward (upward) travels to the vicinity of the center between the pair of cantilevers 111, and the outward (downward) along the up-down direction It returns to the direction, advances to the vicinity of the corner (lower left corner) of the weight portion 112, advances to the vicinity of another corner (lower right corner) of the weight portion 112 along the left-right direction, and moves along the weight portion 11 along the vertical direction.
2 to the vicinity of another corner (upper right corner), proceed along the left and right direction to the vicinity of another corner (upper left) of the weight portion 112, and inward (down) in the vertical direction near the center between the pair of cantilevers 111. , And is turned outward (upward) along the up-down direction to reach the upper cantilever 111.

As described above, the crack detection wiring 5 is routed so as to go around the four corners of the weight portion 112 and to return to the vicinity of the center between the pair of cantilevers 111 to be folded, for example, as shown in FIGS. 3, 6, and 8. Cracks C11, C12, C31, and C41 can be detected and, as shown in FIG.
Crack C extending from inside to the inside of weight portion 112
When 51 occurs, the crack detection wiring 5 is disconnected or its resistance value increases, so that the crack C51 can be detected.

[0056]

As is apparent from the above, according to the first aspect of the present invention, a pair of elastic cantilevers extending in one direction, and one end of each of these cantilevers are integrally formed. An acceleration sensor chip having a weight portion formed at the center and supported on one side inside,
A pair of piezoresistors are formed on each of the pair of cantilevers, and the plurality of piezoresistors constitute a bridge circuit.The predetermined number of piezoresistors are provided at predetermined positions outside the weight portion in the acceleration sensor chip. And is electrically connected to the bridge circuit.
A plurality of electrode pads connected to the plurality of crack detection wirings are formed, and the crack detection wiring passes through one of the pair of cantilevers from one electrode pad side of the plurality of electrode pads, and Since it is in a wiring state where it is drawn so as to enter the part and passes through the other cantilever and reaches the other electrode pad side, it is possible to detect minute cracks such as a slight increase in wiring resistance, Cracks generated at the weight outside the cantilever can also be detected.

According to the second aspect of the present invention, in the semiconductor acceleration sensor according to the first aspect, the wiring of the crack detection wiring in the weight portion is performed from a boundary between the one cantilever and the weight portion. A predetermined distance into the weight portion along the direction of the arrow, advance inward along a direction orthogonal to the one direction to a position corresponding to the other cantilever, and head toward the other cantilever along the one direction. In this state, cracks in the cantilever can be detected, and cracks in the vicinity of the communicating portion with the weight outside the cantilever can be detected.

According to the third aspect of the present invention, in the semiconductor acceleration sensor according to the first aspect, the routing of the crack detection wiring in the weight portion is performed from a vicinity of a boundary between the one cantilever and the weight portion. Proceed outward along the direction orthogonal to the one direction to the vicinity of the edge of the weight portion, advance a predetermined distance into the weight portion along the one direction, and inward along the orthogonal direction. 3 to the vicinity of another edge of the portion, return to the predetermined distance along the one direction, and head toward the other cantilever along the orthogonal direction. It is possible to suitably detect a crack generated in a weight portion outside the cantilever.

According to the fourth aspect of the present invention, in the semiconductor acceleration sensor according to the first aspect, the wiring of the crack detection wiring in the weight portion is performed from a vicinity of a boundary between the one cantilever and the weight portion. Proceed outward to a vicinity of a corner of the weight portion along a direction perpendicular to the one direction, proceed to a vicinity of another corner of the weight portion along the one direction, and proceed along the perpendicular direction to the weight portion. 4, so as to proceed to the vicinity of another corner of the weight portion, proceed to the vicinity of another corner of the weight portion along one direction, and head toward the other cantilever along the orthogonal direction. Cracks generated in the weight outside the cantilever can be detected more suitably than the invention.

According to a fifth aspect of the present invention, in the semiconductor acceleration sensor according to the first aspect, the crack detection wiring is routed in the weight portion from near a boundary between the one cantilever and the weight portion. Proceed inward along the direction perpendicular to the one direction to the vicinity of the center between the pair of cantilevers, turn outward along the perpendicular direction, proceed to the vicinity of the corner of the weight, and follow the one direction. Advance to the vicinity of another corner of the weight portion, proceed along the orthogonal direction to the vicinity of another corner of the weight portion,
Proceed along one direction to the vicinity of another corner of the weight portion, proceed inward along a direction perpendicular to the one direction to the vicinity of the center between the pair of cantilevers, and outward along the perpendicular direction. In this state, the crack is generated toward the other cantilever, so that a crack generated in the weight portion outside the cantilever can be detected more suitably than the invention according to the fourth aspect.

[Brief description of the drawings]

FIG. 1 is a top view of an acceleration sensor chip provided in a semiconductor acceleration sensor according to a first embodiment of the present invention.

FIG. 2 is a sectional view of the semiconductor acceleration sensor according to the first embodiment.

FIG. 3 is a diagram showing an example of a crack that can be detected by the crack detection wiring shown in FIG.

FIG. 4 is a diagram showing a structural example of an acceleration sensor chip provided with two pads dedicated to crack detection wiring.

FIG. 5 is a top view of an acceleration sensor chip provided in a semiconductor acceleration sensor according to a second embodiment of the present invention.

FIG. 6 is a diagram showing an example of a crack that can be detected by the crack detection wiring shown in FIG.

FIG. 7 is a top view of an acceleration sensor chip provided in a semiconductor acceleration sensor according to a third embodiment of the present invention.

FIG. 8 is a diagram illustrating an example of a crack that can be detected by the crack detection wiring illustrated in FIG. 7;

FIG. 9 is a top view of an acceleration sensor chip provided in a semiconductor acceleration sensor according to a fourth embodiment of the present invention.

FIG. 10 is a diagram showing an example of a crack that can be detected by the crack detection wiring shown in FIG.

FIG. 11 is a sectional view showing an example of a conventional semiconductor acceleration sensor.

FIG. 12 is a top view of the acceleration sensor chip shown in FIG.

FIG. 13 is an enlarged view of a connection portion between each pad and a gauge resistor.

FIG. 14 is a circuit configuration diagram of a connection unit shown in FIG.

FIG. 15 is a diagram showing an example of a crack that can be detected by the wiring structure shown in FIG.

16 is a diagram showing another example of a crack that can be detected by the wiring structure shown in FIG.

17 is a diagram showing another example of a crack that can be detected by the wiring structure shown in FIG.

[Explanation of symbols]

 1, 2, 3, 4, 5 crack detection wiring 11, 21, 31, 41, 51 acceleration sensor chip 11a silicon substrate 11b oxide film 11c nitride film 12 upper glass stopper 12a recess 12b projection 13 lower glass stopper 13a recess 13b projection 110 , 210 Chip body 110a Hole 110b, 210b Pad 110c, 210c Aluminum wiring 110d, 210d Contact part 110e, 210e P + wiring of diffusion layer 110f Aluminum thin film 110g Diffusion resistance 111 Cantilever 111a Gauge resistance 112 Weight 112a Bottom

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Takuro Ishida 1048 Kadoma Kadoma, Osaka Pref.Matsushita Electric Works, Ltd. (72) Inventor Masashi Kataoka 1048 Kadoma Kadoma, Kadoma, Osaka Pref.Matsushita Electric Works, Ltd. (72) Inventor Hironori Kami 1048 Kadoma, Kadoma, Osaka Prefecture Inside Matsushita Electric Works Co., Ltd. (72) Inventor Takashi Saijo 1048, Odaka Kadoma, Kadoma City, Osaka Prefecture Inside Matsushita Electric Works Co., Ltd. (72) Inventor Makoto Saito Osaka 1048 Kadoma, Kamon, Fumonma-shi Matsushita Electric Works, Ltd.

Claims (5)

[Claims] 1. A central portion having a pair of elastic cantilevers extending in one direction, and a weight portion integrally formed on the distal end side of each of these cantilevers and supported inside one side. A pair of piezoresistors are formed on each of the pair of cantilevers, and the plurality of piezoresistors constitute a bridge circuit; at a predetermined position outside the weight portion in the acceleration sensor chip. A plurality of electrode pads electrically connected to the plurality of piezoresistors and connected to one crack detection wiring of a different system from the bridge circuit; Of the electrode pads, one of the electrode pads passes through one of the pair of cantilevers, is routed so as to enter the weight portion, and the other is A semiconductor acceleration sensor in a wiring state that passes through the cantilever and reaches the other electrode pad side. 2. The routing of the crack detection wiring in the weight portion proceeds a predetermined distance into the weight portion along the one direction from a boundary between the one cantilever and the weight portion, and The semiconductor acceleration sensor according to claim 1, wherein the semiconductor acceleration sensor advances inward along a direction orthogonal to a position corresponding to the other cantilever, and is directed toward the other cantilever along the one direction. 3. The routing of the crack detection wiring in the weight portion, the edge of the weight portion being directed outward from a vicinity of a boundary between the one cantilever and the weight portion along a direction orthogonal to the one direction. Proceeding to the vicinity of the portion, proceeding a predetermined distance into the weight portion along the one direction, proceeding inward along the orthogonal direction to near the other edge of the weight portion, and proceeding along the one direction. The semiconductor acceleration sensor according to claim 1, wherein the semiconductor acceleration sensor returns to a predetermined distance and heads toward the other cantilever along the orthogonal direction. 4. The routing of the crack detection wiring in the weight portion, wherein a corner of the weight portion is directed outward from a vicinity of a boundary between the one cantilever and the weight portion along a direction orthogonal to the one direction. Proceed to the vicinity, proceed along the one direction to the vicinity of another corner of the weight portion, proceed along the orthogonal direction to another corner of the weight portion, and proceed along the one direction of the weight portion. 2. The semiconductor acceleration sensor according to claim 1, wherein the semiconductor acceleration sensor advances to a position near another corner and moves toward the other cantilever along the orthogonal direction. 5. The routing of the crack detection wiring in the weight portion, between the vicinity of a boundary between the one cantilever and the weight portion, between the pair of cantilevers inward along a direction orthogonal to the one direction. Proceed to the vicinity of the center, return outward along the orthogonal direction, proceed to the vicinity of the corner of the weight portion, proceed along the one direction to the vicinity of another corner of the weight portion, and proceed along the orthogonal direction. Near the other corner of the weight portion, proceed along one direction to the vicinity of another corner of the weight portion, and inward along a direction orthogonal to the one direction, near the center between the pair of cantilevers. 2. The semiconductor acceleration sensor according to claim 1, wherein the semiconductor acceleration sensor travels to the other cantilever, and turns back outward along the orthogonal direction. 3.