JP2002365306A - Dynamic-response sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a sensor structure capable of improving the yield, while suppressing vibration in the direction different from the two axial directions, in a capacitive acceleration sensor having a movable electrode displacing depending on the application of acceleration and a fixed electrode facing the movable electrode having a detection space and capable of detecting the acceleration generated in the two axial directions. SOLUTION: A first and a second sensor chips 100 and 200, respectively, form comb like beam structural bodies having movable electrodes 120 and 220 and fixed electrodes 130, 140, 230 and 240 on a semiconductor substrate 10. Both sensor chips 100 and 200 are laminated on one circuit board 300, such that displacement direction X of the movable electrode 120 of the first sensor chip 100 is orthogonal to displacement direction Y of the movable electrode 220 of the second sensor chip 200.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a movable electrode which can be displaced in two axial directions, and a fixed electrode which is opposed to the movable electrode at a detection interval, and which is capable of detecting a dynamic quantity generated in the two axial directions. The present invention relates to a semiconductor physical quantity sensor capable of detecting a change based on a capacitance change between both electrodes.

[0002]

2. Description of the Related Art In recent years, there has been an increasing need for a semiconductor dynamic quantity sensor (hereinafter referred to as a biaxial sensor) capable of detecting dynamic quantities in two axial directions. For example, in an automobile airbag control system, it is necessary to detect accelerations (impacts) from two directions, a frontal collision and a side collision.

Here, conventionally, as a two-axis sensor,
In one chip composed of a semiconductor substrate such as an SOI substrate,
A type in which a movable electrode is formed as one mass part displaceable along two different axes (single mass type), and a type in which a plurality of movable electrodes (mass parts) are displaceable in different directions. (Multiple mass type). For example, the former is disclosed in JP-A-9-318649, and the latter is disclosed in JP-A-9-113534.

[0004]

However, in the case of the former single-mass type, although the area can be relatively small, one movable electrode can be formed in a biaxial direction, so that the movable electrode is supported. Due to the variation in the spring constant of the beam portion, vibration in the direction (oblique direction) between the two axial directions, that is, oblique vibration is likely to occur.

On the other hand, in the case of the latter multi-mass type, since each movable electrode (mass portion) can be displaced only in one axial direction, the above-described oblique vibration does not occur, and the detection accuracy can be increased. . However, in comparison with a single-mass type, there is a drawback that the yield is reduced as the chip area is increased, because the size is increased by the number of movable electrodes.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to realize a sensor configuration capable of improving the yield while suppressing vibration in an oblique direction when used in a two-axis sensor.

[0007]

In order to achieve the above object, according to the first aspect of the present invention, a first sensor chip (100) and a second sensor chip (2) for detecting a physical quantity are provided.
00) and a circuit board (300) for processing signals from both sensor chips,
The first and second sensor chips are respectively provided on the semiconductor substrate (10) in predetermined directions (X, Y) in accordance with the application of a physical quantity.
A movable electrode (120, 220) which is displaceable to the right and fixed electrodes (130, 140, 230, 240) forming detection capacitances (CS1 to CS4) between the movable electrode and the movable electrode. The second sensor chip and the second sensor chip are stacked on one circuit board, and change in detection capacitance due to displacement of the movable electrode of the first sensor chip and displacement of the movable electrode of the second sensor chip. It is characterized in that the applied dynamic quantity is detected based on a change in the detection capacity.

According to the present invention, by using two separate sensor chips having the same configuration in which a movable electrode and a fixed electrode are formed on a semiconductor substrate, each chip size can be reduced to a single-mass type level. Therefore, the yield does not decrease as the chip size increases.

In the present invention, the movable electrodes of the first and second sensor chips are arranged so that the directions of displacement of the movable electrodes are different from each other.
Even when the mechanical quantity in the axial direction can be detected, each sensor chip is of a single mass type and the movable electrode in each sensor chip is displaced only in one axial direction, so that the above-described oblique vibration does not occur.

Therefore, according to the present invention, when used in a two-axis sensor, it is possible to realize a sensor configuration capable of improving the yield while suppressing vibration in an oblique direction.

According to the third aspect of the present invention, each of the first sensor chip (100) and the second sensor chip (200) has a rectangular plate shape and has a displacement of the movable electrode. The direction is parallel to one side of the sensor chip, and one side (101) parallel to the displacement direction (X) of the movable electrode (120) in the first sensor chip.
And a side (201) parallel to the displacement direction (Y) of the movable electrode (220) in the second sensor chip is located on the same straight line.

According to this, in the physical quantity sensor according to the second aspect, the displacement directions of the movable electrodes in the first and second sensor chips are arranged so as to be orthogonal to each other. The arrangement of the first and second sensor chips can be facilitated.

Further, according to the invention described in claim 4, the first sensor chip (100) and the second sensor chip (20)
0), these two sensor chips are connected to the circuit board (300).
Marks (160, 26)
0) is formed.

According to this, it is possible to easily perform positioning when both sensor chips are arranged on one circuit board.

Note that the reference numerals in parentheses of the above means are examples showing the correspondence with specific means described in the embodiments described later.

[0016]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention. In the present embodiment, the present invention is applied to a differential capacitance type semiconductor acceleration sensor as a physical quantity sensor.

FIG. 1 shows a plan configuration of a semiconductor acceleration sensor (hereinafter, simply referred to as a sensor) S1, and FIG.
4 shows a schematic cross-sectional structure along the line A. This sensor S
1 can be applied to, for example, an automobile acceleration sensor or a gyro sensor for controlling the operation of an airbag, ABS, VSC, or the like.

The sensor S1 includes a first sensor chip 100 and a second sensor chip 200 for detecting a physical quantity, and one circuit board 300 for processing signals from both sensor chips 100 and 200.

First and second sensor chips 100 and 20
0 denotes movable electrodes 120, 2 which can be displaced in predetermined directions X and Y in a plane parallel to the semiconductor substrate 10 in response to application of acceleration (mechanical quantity) to the semiconductor substrate 10 (see FIG. 2).
20 and fixed electrodes 130, 140 forming detection capacitors CS1 to CS4 between the movable electrodes 120, 220;
230 and 240 are formed.

In this embodiment, the first sensor chip 1
The two sensor chips 100 and 200 are arranged so that the displacement direction X of the movable electrode 120 at 00 and the displacement direction Y of the movable electrode 220 at the second sensor chip 200 are orthogonal to each other. The X and Y mechanical quantities can be detected.
The shapes of 0 and 200 are the same.

The first and second sensor chips 10
0 and 200 are both formed by subjecting the semiconductor substrate 10 to a known micromachining process. In this example, as shown in FIG. 2, the semiconductor substrates constituting both sensor chips 100 and 200 include a first silicon substrate 11 as a first semiconductor layer and a second silicon substrate 12 as a second semiconductor layer. A rectangular SOI substrate 10 having an oxide film 13 as an insulating layer between them.

The structure of both sensor chips 100 and 200 will be described. By forming a groove in the second silicon substrate 12, the movable electrodes 120 and 220 and the fixed electrode 1 are formed.
A beam structure having a comb tooth shape including 30, 140, 230, and 240 is formed. A portion of the oxide film 13 and the first silicon substrate 11 corresponding to the region where the beam structure is formed is removed in a rectangular shape by anisotropic etching or dry etching of silicon to form an opening 13a. I have.

The movable electrodes 120 and 220 arranged so as to cross over the opening 13a have weights 121 and 221 and both ends of the weights 121 and 221 are anchored 123a and 1b.
23b, 223a, beam portion 12 integrally connected to 223b
2, 222. The anchor portion is made of an oxide film 13
And is supported on the first silicon substrate 11. As a result, the movable electrodes 120 and 220 (weight and beam) face the opening 13a.

Each of the beams 122 and 222 has a rectangular frame shape in which two beams are connected at both ends thereof, and has a spring function of being displaced in a direction orthogonal to the longitudinal direction of the beams. Specifically, the beam part 122 in the first sensor chip 100
Is such that when an acceleration including a component in the X direction in FIG. 1 is received, the weight portion 121 is displaced in the X direction (first direction) and restored to the original state in accordance with the disappearance of the acceleration. Has become.

On the other hand, when the beam portion 222 of the second sensor chip 200 receives an acceleration including a component in a Y direction orthogonal to the X direction in FIG. ), And restores the original state in response to the disappearance of the acceleration.

Therefore, the movable electrode 120 of the first sensor chip 100 is moved to the opening 1 by the application of acceleration.
3a, the movable electrode 220 in the second sensor chip 200 can be displaced in the displacement direction (X direction) of the beam portion 122. (Y direction).

In this embodiment, in the first sensor chip 100 and the second sensor chip 200, the displacement directions X and Y of the movable electrodes 120 and 220 are parallel to one side of the sensor chips 100 and 200. ing.

The movable electrodes 120 and 220 are connected to the beam 1
22 and 222 in a direction perpendicular to the displacement direction.
1, 221 are provided with a plurality of protruding electrodes 124, 224 integrally protruding in opposite directions from each other. In this example, the protruding electrodes 124 and 224 are
Each of the projecting electrodes 124 and 224 is formed in the shape of a beam having a rectangular cross section and faces the opening 13a.

As described above, each protruding electrode 124, 224
Is a beam part 122 as a part of the movable electrodes 120 and 220,
It is integrally formed with 222 and weight parts 121 and 221, and can be displaced in the displacement direction of beams 121 and 221 together with beam parts 122 and 222 and weight parts 121 and 221.

Fixed electrodes 130, 140, 230, 240
Are the anchor portions 123a, 123b, and 2 of the opposing sides of the opening edge of the opening 13a in the oxide film 13.
23a and 223b are supported on another pair of unsupported sides.

Here, in each of the sensor chips 100 and 200, the fixed electrodes 130, 140, 230 and 240 are
The first fixed electrode 13 is provided two with the weights 121 and 221 interposed therebetween and located on one side of the weights 121 and 221.
0, 230, and second fixed electrodes 140, 240 located on the other side of the weight portions 121, 221. The first fixed electrodes 130, 230 and the second fixed electrodes 140, 240 are electrically connected to each other. Independent.

Each of the fixed electrodes 130, 140, 230, 24
0 denotes a wiring portion 13 fixed to the opening edge of the opening 13 a in the oxide film 13 and supported by the first silicon substrate 11.
1, 141, 231, 241 and movable electrodes 120, 22
A plurality (three in the illustrated example) of the protruding electrodes 132, 142, 232, and 24 are disposed to face each other in a state of being parallel to the side surfaces of the zero protruding electrodes 124 and 224 at a predetermined detection interval.
2 is provided.

The protruding electrodes 132, 142, 2 of each fixed electrode
32, 242 are formed in a beam shape having a rectangular cross section, are in a state of being cantileverly supported by the wiring portions 131, 141, 231, 241 and face the opening 13a.

As shown by the capacitor symbol in FIG. 1, in the first sensor chip 100, the detection capacitance is set at the detection interval between the protruding electrode 132 of the first fixed electrode 130 and the protruding electrode 124 of the movable electrode 120. CS1, a detection capacitor CS2 is formed at a detection interval between the protruding electrode 142 of the second fixed electrode 140 and the protruding electrode 124 of the movable electrode 120.

On the other hand, in the second sensor chip 200, the detection capacitance CS is set at the detection interval between the protruding electrode 232 of the first fixed electrode 230 and the protruding electrode 224 of the movable electrode 220.
3. The detection capacitance CS2 is set at the detection interval between the protruding electrode 242 of the second fixed electrode 240 and the protruding electrode 224 of the movable electrode 220.
Are formed.

Further, each wiring portion 131, 14 of each fixed electrode
1, 231 and 241, fixed electrode pads 131a and 141a for wire bonding are respectively provided.
231a and 241a are formed.

In each of the sensor chips 100 and 200, wiring sections 125 and 225 for movable electrodes are formed in a state of being integrally connected to one of the anchor sections 123b and 223b. The movable electrode pad 125 for wire bonding is
a, 225a are formed. Each of the above electrode pads 1
31a, 141a, 231a, 241a, 125a, 2
25a is formed of, for example, aluminum.

Further, the weights 121 and 221 are provided with the opening 1.
A plurality of rectangular through-holes 50 penetrating from the 3a side to the opposite side are formed, and these through-holes 50 form a so-called ramen structure in which a plurality of rectangular frame portions are combined. Thereby, the weight of the movable electrodes 120 and 220 is reduced,
The torsional strength has been improved.

Further, as shown in FIG.
Reference numerals 00 and 200 are bonded and fixed to one circuit board 300 via an adhesive 310 on the back surface (the surface opposite to the oxide film 13) of the first silicon substrate 11. A detection circuit 400 (see FIG. 3) for processing signals from both sensor chips 100 and 200 described below is provided on the circuit board 300.
Is provided.

Then, the pad 320 made of aluminum or the like of the circuit board 300 and each of the electrode pads 13
1a, 141a, 231a, 241a, 125a, 22
5a is a wire W1, W2, W3, W4 formed by gold or aluminum wire bonding or the like.
They are electrically connected by W5 and W6.

Each of such sensor chips 100 and 200
Can be manufactured by using a well-known semiconductor manufacturing technique. An example of the manufacturing method will be briefly described. First, an SOI substrate 10 is prepared, and aluminum is deposited on the entire surface of the second silicon substrate 12. Thereafter, the above-mentioned electrode pads are formed by patterning the aluminum film using photolithography and etching.

From this state, a silicon nitride film deposited by, for example, a plasma CVD method on the surface side of the first silicon substrate 11 is patterned by using a photolithography technique and an etching technique. Thereby, the opening 1
A mask (mask for forming an opening) for forming 3a by etching is formed.

Thereafter, a resist having dry etching resistance is formed as a mask on the second silicon substrate 12 and each electrode pad portion, and dry etching is performed, so that a silicon oxide film is formed in the second silicon substrate 12. A groove reaching 13 is formed. With this groove, a pattern of the beam structure as shown in FIG. 1 is formed on the second silicon substrate 12.

From this state, the first silicon substrate 11 is formed, for example, on the first silicon substrate 11 by using, for example,
By performing etching using an OH aqueous solution or dry etching using a plasma etching apparatus, a silicon oxide film 13 is formed at a portion corresponding to the opening 13a.
To expose. Note that, with such dry etching, the opening forming mask is also removed at the same time.

Next, the opening 13a is formed by etching with an HF type etching solution to remove the silicon oxide film 13, and the movable electrode 12 is formed.
0, 220 and fixed electrodes 130, 140, 230, 24
Release 0. Then, a dicing cut or the like is performed, and each of the sensor chips 100 and 200 shown in FIGS.
Is completed.

Then, each sensor chip 100, 200
Is bonded to the circuit board 300 via the adhesive 310,
By performing wire bonding, the pad 320 of the circuit board 300 and the above-mentioned electrode pads 131a, 141a,
The wires 31a, 241a, 125a, and 225a are electrically connected by the wires W1 to W6. Thus, the sensor S1 is completed.

The operation of the sensor S1 will be described.
In the sensor S1, when an acceleration is applied in the first direction X, the movable electrode 1 in the first sensor chip 100
20 is displaced in the first direction X, and the detection capacitance CS at this time is
1. The applied acceleration is detected based on a change in CS2 (first detection capacitors CS1 and CS2).

On the other hand, when acceleration is applied in the second direction Y, the movable electrode 220 in the second sensor chip 200
Is displaced in the second direction Y, and the detection capacitance CS3 at this time is
The applied acceleration is detected based on a change in CS4 (second detection capacitors CS3, CS4).

The detection of the acceleration in the first direction X will be described more specifically. For example, if acceleration is applied in the right direction (+ X direction) in FIG. 1 along the first direction X, the movable electrode 120 in the first sensor chip 100
Is leftward in FIG. 1 along the first direction X (−X direction)
Is displaced.

With this displacement, the first sensor chip 10
0, the movable electrode 120 and the first fixed electrode 130
The detection interval between the two protruding electrodes 124 and 132 is reduced and the detection capacitance CS1 increases, and the detection interval between the two protruding electrodes 124 and 142 of the movable electrode 120 and the second fixed electrode 140 is widened and the detection capacitance CS2 decreases.

At this time, the detection capacitors CS1 and CS
2, the acceleration applied in the first direction X is detected. FIG. 3 is a diagram (detection circuit diagram) showing the detection circuit 400 in such a differential capacitance type sensor S1, and shows a case where acceleration in the first direction X is detected.

In the detection circuit 400, reference numeral 401 denotes a switched capacitor circuit (SC circuit). The SC circuit 401 includes a capacitor 402 having a capacitance of Cf, a switch 403, and a differential amplifier circuit 404. The difference (CS1-CS2) is converted into a voltage.
FIG. 4 shows an example of a timing chart for the detection circuit 400.

The first sensor chip 10 of the sensor S1
0, the carrier 1 (for example, at a frequency of 10) from the pad portion 131a corresponding to the first fixed electrode 130.
0 kHz, amplitude 0 to 5 V), and the phase with the carrier 1 is 18 from the pad portion 141a corresponding to the second fixed electrode 140.
A carrier 2 (for example, frequency 100 kHz, amplitude 5 to 0 V) shifted by 0 ° is input, and the switch 40 of the SC circuit 401 is
3 is opened and closed at the timing shown in FIG.

Thus, the first detection capacitors CS1, CS2
The acceleration applied along the first direction X is detected based on the voltage value output based on the difference between. At this time,
In the second sensor chip 200, the movable electrode 220
Is not displaced in the first direction X, so that the second detection capacitance C
Changes in S3 and CS4 can be ignored.

Next, detection of acceleration in the second direction Y will be described more specifically. For example, if acceleration is applied in the upward direction (+ Y direction) in FIG. 1 along the second direction Y, the movable electrode 2 in the second sensor chip 200
20 is displaced downward (−Y direction) in FIG. 1 along the second direction Y.

With this displacement, the second sensor chip 10
0, the movable electrode 220 and the first fixed electrode 230
, The detection interval between the two protruding electrodes 224 and 232 is reduced, and the detection capacitance CS3 is increased. The detection interval between the two protruded electrodes 224 and 242 of the movable electrode 220 and the second fixed electrode 240 is widened and the detection capacitance CS4 is reduced.

At this time, the detection capacitance CS3 and the detection capacitance CS
Then, the applied acceleration in the second direction Y is detected based on the difference from the fourth acceleration. The detection circuit 400 for detecting the acceleration in the second direction Y, as shown in FIG.
1 and CS2, respectively, to the second detection capacitors CS3 and CS4.
Is equivalent to The detection circuit 4
An example of a timing chart for 00 may be the same as that in FIG.

In the acceleration detection in the second direction Y, the capacitance difference (CS3-CS4) is subjected to CV conversion in the same manner as described above, so that the second detection capacitance CS
3, the applied acceleration along the second direction Y is detected as a voltage value output based on the difference between CS4 and CS4. At this time, in the second sensor chip 200, since the movable electrode 120 is not displaced in the second direction Y, the change in the first detection capacitors CS1 and CS2 can be ignored.

According to the present embodiment, the movable electrodes 120 and 220 and the fixed electrodes 130 and
By using two separate sensor chips 100 and 200 having the same configuration formed by forming 140, 230 and 240, each chip size can be set to a single-mass type level. The yield does not decrease with the increase.

In this embodiment, the movable electrode 12 in the first and second sensor chips 100 and 200 is used.
The displacement directions X and Y of 0, 220 are arranged so as to be different from each other, and the acceleration in the biaxial directions X, Y can be detected. However, the movable electrodes 120, 220 in each of the sensor chips 100, 200 Since the displacement occurs only in one axial direction, the above-described oblique vibration does not occur.

Therefore, according to the present embodiment, it is possible to realize a two-axis sensor capable of improving the yield while suppressing the vibration in the oblique direction.

Also, as in the present embodiment, the semiconductor substrate 1
0 sensor chips 100 and 200
In order to mount the sensor chip on the sensor chip, the sensor chip is usually mounted via a support substrate (pedestal) insulated from the electrode part of the sensor chip. In this example, the oxide film 13 of the SOI substrate 10 as a semiconductor substrate and the first silicon substrate 11 also serve as a support substrate.

For this reason, some parasitic capacitance is generated between the movable electrode and the fixed electrode and the supporting substrate, and this affects the offset variation of the sensor. However, as in the present embodiment, it is necessary to separate the sensor chip. Thereby, the influence of the parasitic capacitance on the offset variation of the sensor can be reduced as compared with the above-mentioned double mass type. This will be specifically described.

In this example, a parasitic capacitance is generated between the electrode portion (movable electrode, fixed electrode) of the sensor chip and the first silicon substrate 11 via the oxide film 13. In the first sensor chip 100, the parasitic capacitance CK1x between the first fixed electrode 130 and the first silicon substrate 11, and the parasitic capacitance CK2 between the second fixed electrode 140 and the first silicon substrate 11.
x, a parasitic capacitance CK3x is formed between the movable electrode 120 and the first silicon substrate 11, respectively.

On the other hand, in the second sensor chip 200, a parasitic capacitance CK1y is present between the first fixed electrode 230 and the first silicon substrate 11, and a parasitic capacitance CK1y is present between the second fixed electrode 240 and the first silicon substrate 11. Capacity CK2y, movable electrode 2
Between the first silicon substrate 11 and the parasitic capacitance CK3
y are formed respectively.

Here, FIG. 5 shows an equivalent circuit diagram including the detection capacitors CS1 and CS2 and the parasitic capacitors CK1x, CK2x and CK3x of the first sensor chip 100 in the sensor S1 of this embodiment. In the sensor S1 of this example, since the first sensor chip 100 and the second sensor chip 200 are separate, an equivalent circuit of the first sensor chip 100 is as shown in FIG.

In the first sensor chip 100, the first
The output V1 when the acceleration is applied in the direction X is expressed by the following equation 1 when the parasitic capacitances CK1x, CK2x, and CK3x are also taken into consideration.

[0068]

V1 = ｛(CS1-CS2) + (CK1x-C)
K2x) · CK3x / (CK1x + CK2x + CK3
x)｝ · Vcc / Cf where Cf in Equation 1 is the SC circuit 4 shown in FIG.
01, the capacity of the capacitor 402, Vcc is the operating voltage, which is the voltage between the first fixed electrode 130 and the second fixed electrode 140 during operation.

The output when the acceleration in the first direction X is 0 G, that is, the offset is obtained by setting CS1 = CS2 in the above equation 1, and is as shown in the following equation 2.

[0070]

V1 = ｛(CK1x−CK2x) · CK3x /
(CK1x + CK2x + CK3x)｝ · Vcc / Cf =
Za Next, if the first and second sensor chips 100,
When 200 is formed on the same chip to be a multi-mass type, the sensing unit corresponding to the first sensor chip includes:
Since the parasitic capacitance of the sensing unit corresponding to the second sensor chip 200 is coupled, the equivalent circuit diagram is as shown in FIG.

In the case of the multiple mass type shown in FIG. 6, the output V when the acceleration is applied in the first direction X
1 ′ is the parasitic capacitance CK1 to CK3x, CK1y, C
When K2y and CK3y are also taken into consideration, the following Equation 3 is obtained.

[0072]

V1 '= ｛(CS1-CS2) + (CK1x +
(CK1y-CK2x-CK2y) · (CK3x + CK3
y) / (CK1x + CK1y + CK2x + CK2y + C
K3x + CK3y)｝ · Vcc / Cf Then, the output when the acceleration in the first direction X is 0G,
That is, in Equation 3, CS1 =
CS2, as shown in the following Expression 4.

[0073]

V1 ′ = ｛(CK1x + CK1y−CK2x−
(CK2y) · (CK3x + CK3y) / (CK1x + C
K1y + CK2x + CK2y + CK3x + CK3y)｝
Vcc / Cf In this equation 4, tentatively, CK1x = CK1y, CK
Even when 2x = CK2y and CK3x = CK3y, the offset is as shown in the following Expression 5.

[0074]

V1 ′ = 2 · (CK1x−CK2x) · 2 · C
K3x / {2 · (CK1x ++ CK2x + CK3x)}
Vcc / Cf = 2Za That is, the above equation 2 (V = Za) and the above equation 5 (V ′ =
From the comparison with 2Za), simply, as in the present embodiment, when the sensor chips 100 and 200 are separate chips, the first and second sensor chips 100, 200
The offset variation can be reduced to about 約 as compared with the case where the 200 is formed on the same chip to be a multi-mass type.

Further, by forming the sensor chips 100 and 200 as separate chips, the sensor chips 10
Since it is easy to change the size of the comb teeth and the detection interval at 0 and 200, the mutual sensor chips 100 and 200
Are different from each other to realize a sensor S1 having different G ranges in the X direction and the Y direction.

Further, if the bonding area between the sensor chip and the circuit board is large, the semiconductor (silicon) and the adhesive (resin, etc.)
The warpage of the chip increases due to the difference in the coefficient of thermal expansion between them.
In this regard, in the present embodiment, the area of each of the sensor chips 100 and 200 can be reduced as compared with the multi-mass type, so that the bonding area with the circuit board can be reduced and the warpage of the chip can be suppressed. be able to.

Note that, as in the present embodiment, the first sensor chip 100 and the second sensor chip 200 each have a rectangular plate shape and have movable electrodes 120 and 22.
When the displacement directions X and Y of 0 are parallel to one side of the sensor chip, as shown in FIG.
0, one side parallel to the displacement direction X of the movable electrode 120
01 and the movable electrode 22 in the second sensor chip 200
One side 201 parallel to the zero displacement direction Y can be positioned on the same straight line (shown by a dashed line in the figure) B.

According to this, both sensor chips 100 and 200 are arranged such that the displacement directions X and Y of the movable electrodes 120 and 220 in the first and second sensor chips 100 and 200 are orthogonal to each other. Cheap.

As shown in FIG. 8, marks 160 and 260 are formed on the first sensor chip 100 and the second sensor chip 200 for positioning the two sensor chips on the circuit board 300. May be. In the illustrated example, the marks 160 and 260 are cross-shaped, and can be formed in the same manner as the formation of the above-mentioned electrode portion (beam structure) on the second silicon substrate 12.

According to this, these marks 160, 26
Positioning when the two sensor chips 100 and 200 are arranged on one circuit board 300 can be easily performed using 0 as a mark.

(Other Embodiments) Both sensor chips 1
The displacement directions of the movable electrodes 120 and 220 of 00 and 200 are as follows.
Even if they are not orthogonal to each other, they may be different in oblique directions, and may be in the same direction (parallel direction). For example, the sensor chips 100 and 200 may be arranged such that the displacement directions of the sensor chips 100 and 200 are both in the X direction.

[Brief description of the drawings]

FIG. 1 is a plan view showing a configuration of a semiconductor acceleration sensor according to an embodiment of the present invention.

FIG. 2 is a schematic sectional view taken along the line AA in FIG.

FIG. 3 is a detection circuit diagram of the acceleration sensor shown in FIG.

4 is a diagram showing an example of a timing chart for the detection circuit shown in FIG. 3;

5 is an equivalent circuit diagram including a detection capacitance and a parasitic capacitance of a first sensor chip in the acceleration sensor shown in FIG.

FIG. 6 is an equivalent circuit diagram including a detection capacitance and a parasitic capacitance in a multiple mass type as a comparative example.

FIG. 7 is a diagram showing a modification of the embodiment.

FIG. 8 is a diagram showing another modification of the embodiment.

[Explanation of symbols]

10 SOI substrate (semiconductor substrate), 100 first sensor chip, 120, 220 movable electrode, 130, 14
0, 230, 240: fixed electrode, 160, 260: mark, 200: second sensor chip, 300: circuit board.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2F051 AA01 AB06 DA02 4M112 AA02 BA07 CA03 CA04 CA05 CA06 CA11 CA13 CA15 DA02 DA03 DA04 DA06 EA03 EA06 EA11 FA20

Claims (4)

[Claims] 1. A first sensor chip (1) for detecting a physical quantity.
00) and the second sensor chip (200), and a circuit board (30) for processing signals from both sensor chips.
0), wherein the first and second sensor chips are respectively provided on the semiconductor substrate (10) in predetermined directions (X,
A movable electrode (120, 220) displaceable to Y) and fixed electrodes (130, 140, 230, 240) forming detection capacitors (CS1 to CS4) between the movable electrode and the movable electrode; The first and second sensor chips are stacked on one circuit board, and the change in the detection capacitance due to the displacement of a movable electrode of the first sensor chip, and the second sensor chip A dynamic quantity sensor configured to detect an applied dynamic quantity based on a change in the detection capacity accompanying a displacement of the movable electrode. 2. A displacement direction (X) of a movable electrode (120) in the first sensor chip (100) and a displacement direction (Y) of a movable electrode (220) in the second sensor chip (200). The physical quantity sensor according to claim 1, wherein the directions are different. 3. The first sensor chip (100) and the second sensor chip (200) each have a rectangular plate shape, and the direction of displacement of the movable electrode is parallel to one side of the sensor chip. And the movable electrode (12) in the first sensor chip.
A side (101) parallel to the displacement direction (X) of (0) and a side (201) parallel to the displacement direction (Y) of the movable electrode (220) in the second sensor chip are positioned on the same straight line. 3. The physical quantity sensor according to claim 2, wherein: 4. A mark (160) for positioning the first sensor chip (100) and the second sensor chip (200) when arranging both sensor chips on the circuit board (300). , 260) are formed. The dynamic quantity sensor according to any one of claims 1 to 3, wherein: