JP2002310664A - Angular speed sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lower a sneaking drive signal appearing as noise in a detection signal in the case of a vibration-type angular speed sensor. SOLUTION: This angular speed sensor has a weight part 30 formed on a semiconductor substrate 12, so as to be vibratable in first and second directions normal to each other and detects an angular velocity by a change in capacitance, caused by the detection vibration of the weight part 30 in the second direction generated, when angular speed is imposed thereon, while the weight part 30 is driven to vibrate in the first direction, where a detection electrode comprises four divisional electrode parts 50a to 50d. When the detection vibration takes place, a difference is found between signals Va and Vb from the pair of adjoining electrode parts 50a and 50b, while a difference is found between signals Vc and Vd from the other pair of adjoining electrode parts 50c and 50d, then the difference is taken between differential signals Vab and Vcd from the two pairs, and used as a detection signal Vout.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming a weight portion as a vibrator and a detection electrode on a semiconductor substrate and, when an angular velocity is applied while driving the weight portion, the capacitance between the weight portion and the detection electrode. The present invention relates to a vibration type angular velocity sensor that detects a change.

[0002]

2. Description of the Related Art Conventionally, as an angular velocity sensor of this type, a weight portion capable of vibrating in a first direction and a second direction orthogonal to each other on a semiconductor substrate, and the weight portion is driven and vibrated in a first direction. Electrode for applying a periodically changing drive signal to the weight portion, a weight portion generated when an angular velocity is applied around an axis orthogonal to the first and second directions under the drive vibration There is a type in which a detection electrode for detecting a detection vibration caused by a Coriolis force in the second direction as a detection signal is formed.

[0003]

SUMMARY OF THE INVENTION The present inventor has conducted trial manufacture of the above-mentioned conventional vibration type angular velocity sensor. FIG. 5 is a schematic plan view showing an angular velocity sensor as a prototype manufactured by the inventor. This prototype can be manufactured using a known semiconductor manufacturing technique using an SOI (silicon-on-insulator) substrate in which two silicon substrates are bonded together via an oxide film.

FIG. 5 shows a plan view of one silicon substrate (semiconductor substrate) 12. On the one silicon substrate 12, each part is formed by forming a groove. The weight 30 is disposed on the opening 14 formed by partially removing the oxide film supporting the one silicon substrate 12 and the other silicon substrate.

The weight 30 is supported by the base 20 on the outer periphery of the weight 30 via a driving beam 33 that can be spring-deformed in the x direction and a detection beam 34 that can be spring-deformed in the y direction in the drawing.
The weight 30 is capable of vibrating in the x direction (first direction) and in the y direction (second direction) orthogonal to the x direction. At the portion where the outer peripheral portion of the weight portion 30 and the base portion 20 face each other, the following comb-shaped electrode portions are formed.

That is, a drive electrode 40 for applying a drive signal to the weight 30 to drive and oscillate the weight 30 in the x direction;
Both detection electrodes 150 and 160 are formed for detecting as a detection signal vibration in the y direction of the weight portion 30 generated when an angular velocity Ω is applied around the z axis orthogonal to the x and y directions. .

Here, the detection electrodes 150 and 160 are composed of a first detection electrode 150 and a second detection electrode 160 which face two different portions of the weight 30, respectively.
The electrodes 40, 150, and 160 correspond to the corresponding wire bonding pads 41, 151, and 16, respectively.
1 is formed.

FIG. 6 shows a detection circuit configuration of the sensor shown in FIG. 5, and a detection method will be described with reference to FIG. First, an AC voltage difference (drive signal) having a resonance frequency in the x-direction of the weight 30 is applied between the drive electrode 40 and the comb teeth 35 of the weight 30, and the drive beam 33 causes the weight 30 to move. Is driven and vibrated in the x direction. For example, a constant voltage is applied to the weight 30 side, and an AC voltage is applied to the drive electrode 40 fixed to the base 20.

When the angular velocity Ω is applied under the driving vibration of the weight 30, a Coriolis force is generated in the weight 30 in the y direction, and the weight 30 vibrates in the y direction by the detection beam 34 (FIG. Detection vibration). Then, the capacitance between the detection electrodes 150 and 160 and the comb portion 36 of the weight portion 30 changes due to the detection vibration.

Then, as shown in FIG. 6, the capacitance change in the first detection electrode 150 is converted into a voltage V1 by the C / V conversion circuits 152 and 162 and the differential circuit 170,
After converting the change in capacitance at the second detection electrode 160 into a voltage V2, these two signals V1 and V2 are differentially amplified and amplified.
By detecting this as the detection signal Vout, the magnitude of the angular velocity Ω can be obtained.

By the way, in the angular velocity sensor as shown in FIG. 5, the drive electrode 40 and the two detection electrodes 150, 160
There are parasitic capacitances such as a fringe capacitance between sensor patterns (between grooves) and a parasitic capacitance between bonding wires formed on the pads 41, 151 and 161 corresponding to each electrode.

The capacitance change signal in detection is a very small change in capacitance (for example, 1 aF to 1 fF) and is very sensitive to electrical noise. The AC component of the drive signal is very large, for example, ± several volts. Therefore, the AC component of the drive signal goes around the detection signal via these parasitic capacitances, and is output as noise.

In order to remove the sneak noise component of the drive signal, in the conventional angular velocity sensor, the detection electrodes are divided into a first detection electrode 150 and a second detection electrode 160 which are respectively opposed to two different portions of the weight 30. With this configuration, the differential detection as shown in FIG. 6 is performed.

Here, the mutual detection electrodes 150 and 160
Is processed so that the distance from the drive electrode 40 is equal and the shape thereof is also symmetrical, so that the wraparound of the drive signal is the same in both the detection electrodes 150 and 160. Can be canceled.

However, a certain degree of processing variation (such as etching variation) cannot be avoided.
In 50 and 160, the wraparound of the drive signal cannot be made identical to each other. For this reason, even if the signals V1 and V2 from the detection electrodes 150 and 160 are differentiated, the wraparound of the drive signal cannot be sufficiently reduced, and if amplified, the noise will be amplified to the amount of noise.

In view of the above problems, it is an object of the present invention to provide a vibration-type angular velocity sensor capable of reducing a sneak of a drive signal which appears as noise in a detection signal.

[0017]

In order to achieve the above object, according to the first aspect of the present invention, a semiconductor substrate (12) is provided.
A weight portion (30) capable of vibrating in first and second directions (x, y) orthogonal to each other, a drive electrode (40) for applying a drive signal to the weight portion, and detection vibration of the weight portion Detection electrodes (50a, 50b, 50c, 50) for detecting angular velocity from
d) In the angular velocity sensor formed with the above, the detection electrode is constituted by four or more divided electrode portions,
At the time of the detection vibration, a signal (Va, Vb) of a pair of adjacent electrode units (50a, 50b) of the plurality of electrode units is differentially determined, and another pair of adjacent electrode units is paired with each other. After taking the differential of the signals (Vc, Vd) of (50c, 50d), the differential signal (Vab) between the pair of electrode parts and the differential signal (Vcd) between the other pair of electrode parts are obtained. ).

Here, adjacent electrode units are those in which the distance between the electrode units in the same set in one set is shorter than the distance between the one set of electrode units and the other set of electrode units. It means there is.

In the present invention, the detection electrode is constituted by at least four divided electrode portions, and two electrode portions which are close to each other and close to each other in the degree of the wraparound of the drive signal are selected.
Then, in two sets of the selected two electrode sections, differential signals are taken from the electrode sections in each set.

Thus, it is possible to reduce the sneak of the drive signal in each of the differential signal between the one set of electrode parts and the differential signal between the other set of electrode parts. Therefore, if the detection signal is output by taking the difference between these two sets of differential signals, the sneak of the drive signal appearing as noise in the detection signal can be significantly reduced as compared with the related art.

Here, as in the invention described in claim 2,
The detection electrode is divided into four or more even-numbered electrode portions (50
a to 50d), the number of electrode portions can be configured to be sufficient or sufficient for the purpose of obtaining a signal difference in a set of adjacent electrode portions among the plurality of electrode portions. ,preferable.

Further, according to the third aspect of the present invention, the detection electrodes (50a to 50d) are comb-shaped, and the weight portions (3
0) is characterized in that comb teeth (36) are formed so as to be engaged with the detection electrodes and to face each other.

When the detection portion where the detection electrode and the weight portion face each other has a complicated shape such as a comb shape, the processing variation is relatively large, and the variation in the distance and the shape of the detection electrode from the drive electrode is small. Due to an increase in the size, the above-mentioned problem tends to be remarkable. Therefore, the present invention is particularly effective for an angular velocity sensor having a comb-shaped detection electrode.

Further, in the invention according to claim 4,
In order to perform differential detection, first detection electrodes (50a, 50a,
0b) and the second detection electrodes (50c, 50d) are each divided into a plurality of electrode portions (50a to 50d),
After each of the signals (Va, Vb, Vc, Vd) from the plurality of electrode units is differentially obtained at each of the second detection electrode and the second detection electrode, the differential signal (Vab) at the first detection electrode is compared with the differential signal (Vab) at the first detection electrode. 2
And a differential signal (Vcd) at the detection electrode is obtained.

According to the present invention, each of the first and second detection electrodes is constituted by at least two divided electrode portions, so that each of the first and second detection electrodes is driven by the other electrode portions. The degree of signal wraparound can be made smaller than the degree between the first detection electrode and the second detection electrode.

Therefore, after each of the first and second detection electrodes calculates the differential of the signal from each of the electrode portions, the signal is used as the differential signal of each of the detection electrodes. By taking the signal differential and using it as a detection signal, it is possible to greatly reduce the wraparound of the drive signal that appears as noise in the detection signal as compared with the related art.

According to the fifth aspect of the present invention, the first detecting electrode (50a, 50b) and the second detecting electrode (5
0c, 50d) have a comb shape, and the weight (30) has
A comb tooth (36) is formed so as to be engaged with each of the first and second detection electrodes and to face each other.

In the case where the detecting section has a complicated shape such as a comb-like shape as in the invention of the fifth aspect, if the invention of the fourth aspect is applied, the detection section described in the third aspect of the present invention will be described. It is particularly effective for the same reasons.

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.

[0030]

(First Embodiment) FIG. 1 is a plan view showing an angular velocity sensor S1 according to a first embodiment of the present invention, and FIG. 2 is a sectional view taken along line AA in FIG. is there. The angular velocity sensor S1 is, as shown in FIG.
Is fixed via an adhesive or the like. The same parts as those in FIG. 5 are denoted by the same reference numerals in the figure.

The angular velocity sensor S1 is formed by subjecting a semiconductor substrate to a known micromachining process. As shown in FIG. 2, a substrate constituting the sensor S1 is a second silicon substrate as a second semiconductor substrate on an oxide film 13 as an insulating layer on a first silicon substrate 11 as a first semiconductor substrate. The SOI substrate 10 is a rectangular SOI substrate 10 to which the substrates 12 are bonded.

Here, the second silicon substrate 12 is the semiconductor substrate referred to in the present invention, and a groove is formed in the second silicon substrate 12 by performing an etching process.
2 is a frame-like base 20 located on the peripheral side, and this base 2
0 and a movable weight portion 30 located on the inner peripheral side.

Here, in a portion corresponding to the weight portion 30, the first silicon substrate 11 and the oxide film 13 have been removed, and an opening 14 has been formed. And the base 20
Is formed at the edge of the opening 14 via the oxide film 13.
It is supported on a silicon substrate 11.

The weight portion 30 has a substantially rectangular first movable portion 31 located at the center of the second silicon substrate 12, and is disposed on both outer sides of the first movable portion 31 in the x direction (first direction). It comprises a columnar second movable portion 32 provided. And
In the weight part 30, the second movable part 32 is connected to the base 20 via a drive beam 33 having a substantially U-shape, and the first movable part 31 is connected to the second movable part via a detection beam. It is connected to the part 32.

The driving beam 33 has a degree of freedom substantially only in the x direction, and the driving beam 33 allows the entire weight 30 to vibrate in the x direction. on the other hand,
The detection beam 34 has a degree of freedom substantially only in the y-direction (second direction).
0, the first movable portion 31 can vibrate in the y direction.

In the second silicon substrate 12, the second
The opening 14 is provided on both outer sides of the movable portion 32 in the x direction.
The drive electrodes 40 (in the illustrated example, one by one) are formed in a comb-like shape and supported on the edge of the drive electrode 40. The drive electrode 40 is for applying a drive signal to the weight 30 in order to drive and vibrate the entire weight 30 in the x direction (first direction).

The drive electrode 40 is connected to the second movable part 3
The comb teeth (drive comb teeth) 35 protruding from the second gear 2 are arranged so as to face each other so that the respective comb teeth mesh with each other. Here, pads (drive electrode pads) 41 for electrically connecting to the circuit chip K1 by wire bonding or the like are formed of aluminum or the like on the drive electrodes 40.

The first silicon substrate 12 has the first
The opening 14 is provided on both outer sides of the movable portion 31 in the y direction.
Comb-shaped detection electrodes 50a, 50b supported on the edges of
50c and 50d are formed.

The detection electrodes 50a to 50d are connected to the weight 30
Of the weight portion 30 (first movable portion 32) in the y direction (second direction) generated when an angular velocity Ω is applied around the z axis orthogonal to the x and y directions under the driving vibration of (Detected vibration) is detected as a detection signal.

In the example shown in FIG. 1, the detection electrodes 50a to 50a
d is composed of a comb-shaped electrode portion divided into four. These electrode portions are a pair of two adjacent electrode portions 50a and 50b located on the upper side in the y direction of the first movable portion 31 and a lower side in the y direction of the first movable portion 31. And another pair of electrode portions 50c and 50d which are adjacent to each other.

Here, the adjacent electrode portions are such that the distance between the electrode portions in the same set in one set is shorter than the distance between the one set of electrode portions and the other set of electrode portions. This means that, as shown in FIG.
It is clear from the positional relationship between Oa and 50b and another set of electrode portions 50c and 50d.

The four electrode portions 50a to 50d
Is configured such that one set of electrode units 50a and 50b is used as a first detection electrode, and the other set of electrode units 50c and 50d is used as a second detection electrode. Signals from 50a and 50b and second detection electrodes 50c and 50c
The differential from the signal from 0d is taken and this is output as a detection signal.

For this reason, in the angular velocity sensor S1 of the present embodiment, the first detection electrodes 50a, 50a, 5
0b and the second detection electrodes 50c and 50d
It can also be said that the configuration is such that it is divided into individual electrode portions.

The first movable portion 3 of the weight 30
In one of the parts 1 facing the detection electrodes 50a to 50d,
A comb tooth portion (comb tooth portion for detection) 36 is formed to protrude, and each of the electrode portions 50a to 50d is connected to the comb tooth portion 36 for detection.
On the other hand, the comb teeth are opposed to each other so as to mesh with each other.

In this embodiment, as shown in FIG. 1, three comb teeth 36 are provided at both upper and lower ends of the first movable part 31 in the y direction, and the three comb teeth 36 and the base are provided. Two detection electrodes (electrode portions) 50a to 50d extending from
The comb teeth and the detection electrodes are arranged alternately.

Here, the electrode portions 50a to 50d shown in FIG.
The smaller one of the opposing distances between the sensor and the detection comb tooth portion 36 is the detection interval at which the capacitance detection is performed. And FIG.
As shown in FIG.
b, 50c and 50d, the positions of the detection intervals are upside down.

That is, when the first movable portion 31 vibrates in the y direction, one of the electrode portions 50a (50
In the detection interval between c) and the detection comb portion 36, the two approach each other and the capacitance value increases, while the other electrode portion 50b (50
In the detection interval between d) and the detection comb portion 36, the two are separated from each other and the capacitance value is reduced.

Each of the electrode portions 50a to 50d has a pad (detection electrode pad) 5 for being electrically connected to the circuit chip K1 by wire bonding or the like.
1a, 51b, 51c and 51d are formed of aluminum or the like.

The second silicon substrate 12 has the second
The opening 14 is provided on both outer sides of the movable portion 32 in the x direction.
Monitor electrodes 60 (two in the illustrated example) supported by the edges of the monitor electrodes 60 are formed. This monitor electrode 60
Is for monitoring the drive vibration of the weight 30 in the x direction and detecting the monitor signal.

The monitor electrode 60 is disposed so as to face the comb teeth (monitoring comb teeth) 37 protruding from the second movable portion 32 so that the comb teeth of the monitor electrode 60 mesh with each other. Here, a pad (monitor electrode pad) 61 for electrically connecting the monitor electrode 60 to the circuit chip K1 by wire bonding or the like is formed of aluminum or the like.

The base 20, the weight 30, the drive electrode 40, the detection electrodes 50a to 50d, and the monitor electrode 60
Each part formed on the second silicon substrate 12 is electrically insulated from each other by the groove.

In the angular velocity sensor S1, a periodically changing drive signal (AC voltage such as a sine wave voltage) is applied from the circuit chip K1 to the drive electrode 40 via the drive electrode pad 41, and the drive signal is applied to the drive signal. Comb portion 35 and drive electrode 4
Generates an electrostatic force between zero.

Here, specifically, signals having phases opposite to each other are input to both the left and right drive electrodes 40 in FIG.
As a result, at the frequency of the signal, the entire weight 30 is driven and vibrated in the x direction by the driving beam 33.

At this time, by examining the change in capacitance between the monitor electrode 60 and the monitor comb tooth 37, the weight 30
Monitor the frequency and amplitude of the driving vibration of the motor. Then, the monitored change in capacitance is fed back as a monitor signal from the monitor electrode pad 61 to the circuit chip K1, whereby the drive signal is adjusted, and the weight portion 30 can perform normal drive vibration.

When an angular velocity Ω is applied around the z-axis under the driving vibration of the weight 30, a Coriolis force proportional to the vibration speed is applied to the weight 30 in the y-direction. Of the first movable portion 31 is detected and vibrated in the y direction by the detection beam 34. Then, the capacitance between the detection electrodes 50a to 50d and the detection comb-teeth portion 36 changes due to the detection vibration. The magnitude of the angular velocity Ω is obtained by detecting the change in the capacitance with the circuit chip K. be able to.

Here, in the present embodiment, the following unique detection method is employed, and this detection method will be described with reference to FIG. FIG. 3 is an explanatory diagram illustrating the configuration of the detection circuit provided in the circuit chip K. In FIG. 3, the weight 30, the detection electrodes 50a to 50d, and the
6 is schematically shown.

As shown in FIG. 3, at the time of the detection vibration, the capacitance value of each of the four electrode portions 50a to 50d is C
/ V conversion (capacitance-voltage conversion) circuits 52a, 52b, 52
The signals are converted into voltages Va, Vb, Vc, and Vd by c and 52d.

Next, the differential circuits 53a and 53b and an amplifier circuit (not shown) perform differential / amplification of voltages Va and Vb of a pair of adjacent electrode portions 50a and 50b among the four electrode portions. , And a differential signal Vab, and a differential / amplification of the voltages Vc and Vd of another pair of adjacent electrode units 50c and 50d is performed, and the differential signal Vab is obtained.
cd.

Subsequently, by the differential circuit 53c at the subsequent stage,
The differential signal Vab between the pair of electrode units 50a and 50b and the differential signal Vcd between the other pair of electrode units 50c and 50d are differentiated, and the signal Vout obtained after the differential is calculated as an angular velocity. Is output as a detection signal. Thus, the angular velocity can be obtained.

As described in the “Problem” section, a sneak of a drive signal (noise due to a change in charge due to coupling capacitance) occurs with respect to the detection electrode. Is considered to be proportional to the parasitic capacitance between the drive electrode and the detection electrode. It is generally considered that the parasitic capacitance generated between the driving and detecting electrodes is smaller as the distance between the driving and detecting electrodes is larger.

Here, in the conventional angular velocity sensor,
Since the differential detection as shown in FIG. 6 is performed, in principle, the sneak signal should be canceled out. However, if the pair of differential detection electrodes has a sneak signal of a different value, the differential circuit will remain without being canceled well.

Since the angular velocity sensor, which is the object of the present invention, is manufactured by a semiconductor process, the structure of each electrode is formed in a very uniform shape, but the non-uniformity in various steps such as etching. Therefore, as the distance between the electrodes increases, the processing variation between the electrodes increases.

That is, in the conventional angular velocity sensor as shown in FIG. 5, the first detection electrode 150 and the second detection electrode 160 are separately disposed near both ends of the semiconductor substrate (chip) 12. As described above, when the distance between the two detection electrodes is long, the values of the sneak signal components between the two detection electrodes tend to greatly differ. Therefore, large noise due to the wraparound signal is likely to remain in the detection signal.

In this regard, in the present embodiment, the electrode portions 50a, 50b, 5
0c, 50d, two adjacent electrode portions are selected, and the selected two electrode portions 50a, 50b, 50
In two sets of c and 50d, differential signals are taken from the electrode units in each set.

The individual electrodes of the same set are close to each other and close to each other in drive signal. Therefore, in each of the differential signal Vab between the pair of electrode units 50a and 50b and the differential signal Vcd between the other pair of electrode units 50c and 50d, a wraparound signal (wraparound of a drive signal) is reduced. be able to.

In the present embodiment, since the detection signal Vout is output by taking the difference between these two sets of differential signals Vab and Vcd, the detection signal has noise as compared with the related art. The wraparound of the appearing drive signal can be greatly reduced.

An example of the degree of reduction of the wraparound of the drive signal in this embodiment will be described.
First, in the conventional angular velocity sensor shown in FIG. 6, a sine wave signal having a frequency of 2.5 ± 1.0 Vpp and a frequency of 3 kHz is input to both the left and right drive electrodes 40 so as to have opposite phases. At this time, since the drive resonance frequency is 5 kHz, the weight portion 30 does not vibrate, and only the wraparound of the drive signal is output to the detection electrode.

When the angular velocity Ω is applied, the first
The voltage V1 at the detection electrode 150 is, for example, 28.9.
0 mV, and the voltage V2 at the second detection electrode 160
Is, for example, 30.80 mV.
The differential signal of V2 was taken and the detection signal Vout when amplified about 10 times was 18.42 mV.

On the other hand, in the angular velocity sensor S1 of this embodiment shown in FIG. 3, when the same driving signal and the same angular velocity are used, the voltage Va and the voltage Vb of the pair of electrode parts 50a and 50b are 13. 66mV and 13.33mV, and these differential signals Vab are 3.26mV (amplification ratio 1
0 times).

On the other hand, another pair of electrode portions 50c, 50
The voltage Vc and the voltage Vd of d are 14.42 mV, respectively.
14.55 mV, and these differential signals Vcd are 1.55 mV.
It was 09 mV (amplification rate 10 times). The differential signal Vout obtained by taking the differential between the two differential signals Vab and Vcd and amplifying it about 10 times was 2.40 mV.

As in this example, in the present embodiment, the adjacent electrode portions 50a and 50b
(50c and 50d), the voltages Va and Vb of each other
(Vc and Vd) are higher than those of the prior art (that is, the voltage V
(Compared to the difference between 1 and V2), the degree of wraparound of the drive signal is close.

Then, by taking the differential within the same group,
Since the sneak of the drive signal can be greatly reduced in each of the differential signals Vab and Vcd, in the above example, the sneak of the drive signal in the detection signal is reduced to about 1/10 in the present embodiment as compared with the related art. It has been reduced to the extent.

In the example shown in FIG. 1, the detection electrode 50a
To 50d have a comb-tooth shape, and the weight portion 30 has a configuration in which the comb-tooth portions 36 which are arranged so as to mesh with the respective detection electrodes 50a to 50d and are opposed to each other are formed. It is not limited to the shape.

However, the detection electrodes 50a to 50d and the weight 3
In the case where the detection unit opposing 0 has a complicated shape such as a comb shape, the processing variation is relatively large, and the first detection electrodes 50a, 50b and the second detection electrodes 50c, 50
With d, variations in the distance from the drive electrode 40 and the mutual shape are likely to increase.

Then, it is difficult to sufficiently cancel the wraparound of the drive signal appearing as noise in the detection signal. However, according to the present embodiment, such a configuration using the above-mentioned electrode portion is employed. Problems can be properly prevented.

Further, according to the present embodiment, since the plurality of comb-tooth portions are opposed to one electrode portion, the comb extending in the x direction in each of the comb-tooth portions 36 and each of the electrode portions 50a to 50d. Even if the length of the teeth is shorter than that in FIG. 5, the detection capacity can be ensured, so that the bending rigidity of each comb tooth in the y direction can be increased. Therefore, a phenomenon (sticking) in which each comb tooth bends and adheres during vibration in the y direction can be easily prevented, which is preferable.

(Second Embodiment) FIG. 4 is a plan view showing an angular velocity sensor S2 according to a second embodiment of the present invention. The sensor S2 of the present embodiment is different from the angular velocity sensor S1 shown in FIG. 1 in that the shapes of the comb teeth 36 of the weight portion 30 (first movable portion 31) and the detection electrodes (electrode portions) 50a to 50d are different. It has been changed, and the other parts are the same.

In the sensor S1 shown in FIG. 1, three comb teeth 36 are provided at both upper and lower ends in the y direction of the first movable part 31 and extend from the three comb teeth 36 and the base 20. The two detection electrodes (electrode portions) 50a to 50d are arranged so that the comb portions and the detection electrodes are alternately located.

On the other hand, in the present embodiment, as shown in FIG. 4, one comb tooth portion 36 is provided at each of the upper and lower ends of the first movable portion 31 in the y direction. Detection electrodes (electrode portions) 50a to 50d are arranged on the left and right sides of the comb tooth portion 36 so as to face each other.

In such a configuration, the effect of increasing the bending rigidity of each comb tooth in the y direction is weaker than in the first embodiment, but otherwise, the same effect as in the first embodiment is obtained. can get.

(Other Embodiments) The number of electrode portions constituting the detection electrode may be more than four, and further divided into four or more even numbers (6, 8, 10,...). It is preferable to configure the electrode unit. Thus, the number of electrode portions can be configured without excess or deficiency for the purpose of obtaining a signal difference in a set of adjacent electrode portions among the plurality of electrode portions.

In the above embodiment, the opening 14 has a rectangular shape, but the opening 14 may have another geometrical shape without being rectangular. The opening 14 does not have to penetrate the oxide film 13 and the thickness direction of the first silicon substrate 11. For example, the oxide film 13 is removed by sacrifice layer etching or the like, and the first silicon substrate 11 is left. To form a recess, and the recess may be configured as an opening.

Further, the semiconductor substrate constituting the angular velocity sensor of the present invention is not limited to the above-mentioned SOI substrate 10.

[Brief description of the drawings]

FIG. 1 is a plan view showing an angular velocity sensor according to a first embodiment of the present invention.

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

FIG. 3 is an explanatory diagram showing a configuration of a detection circuit of the angular velocity sensor shown in FIG.

FIG. 4 is a plan view showing an angular velocity sensor according to a second embodiment of the present invention.

FIG. 5 is a schematic plan view showing an angular velocity sensor as a prototype manufactured by the inventor.

6 is an explanatory diagram showing a configuration of a detection circuit of the angular velocity sensor shown in FIG.

[Explanation of symbols]

12 ... second silicon substrate, 30 ... weight part, 36 ... comb part (comb part for detection), 40 ... drive electrode, 50a-50d ...
Detection electrode (electrode part).

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2F105 BB03 CC04 CD03 CD05 CD11 CD13 4M112 AA02 BA07 CA03 CA04 CA05 CA13 DA03 EA03 EA06 EA11 FA01

Claims (5)

[Claims] 1. A first direction (x) and a second direction (y) orthogonal to the first direction are applied to a semiconductor substrate (12).
A weight portion (30) capable of vibrating in the first direction; a driving electrode (40) for applying a periodically changing drive signal to the weight portion so as to drive and vibrate the weight portion in the first direction; Detected vibration of the weight in the second direction generated when an angular velocity is applied around an axis (z) orthogonal to the first and second directions under driving vibration as a detection signal. Detection electrodes (50a, 50b, 50c, 5
0d), and wherein the detection electrode is composed of four or more divided electrode portions, and is adjacent to the plurality of electrode portions during the detection vibration. The signal of one set of electrode units (50a, 50b) is differentially determined, and the other set of adjacent electrode units (50a, 50b) is
c, 50d), the differential between the differential signal between the pair of electrode units and the differential signal between the other pair of electrode units is obtained. Angular velocity sensor. 2. The angular velocity sensor according to claim 1, wherein the detection electrode includes four or more even-numbered electrode portions (50a to 50d). 3. The detection electrode (50a to 50d) has a comb shape, and the weight portion (30) is formed with a comb tooth portion (36) arranged so as to mesh with the detection electrode and face the detection electrode. The angular velocity sensor according to claim 1, wherein 4. A semiconductor substrate (12) having a first direction (x) and a second direction (y) orthogonal to the first direction.
A weight portion (30) capable of vibrating in the first direction; a driving electrode (40) for applying a periodically changing drive signal to the weight portion so as to drive and vibrate the weight portion in the first direction; Detected vibration of the weight in the second direction generated when an angular velocity is applied around an axis (z) orthogonal to the first and second directions under driving vibration as a detection signal. Detection electrodes (50a to 50d) for performing the operation, the first detection electrodes (50a, 50b) and the second detection electrodes respectively facing the two different portions of the weight portion. (50c, 50d), a signal based on a change in capacitance between the first detection electrode and the weight, and a signal between the second detection electrode and the weight during the detection vibration. Differential detection of a signal based on a change in capacitance of In the angular velocity sensor configured to detect a signal, the first detection electrode and the second detection electrode are each divided into a plurality of electrode units (50a to 50d), and the first and second detection electrodes After taking the differential of the signals from the plurality of electrode portions at each of the detection electrodes, the differential between the differential signal at the first detection electrode and the differential signal at the second detection electrode is calculated. An angular velocity sensor characterized in that: 5. The first detection electrode (50a, 50b)
And the second detection electrode (50c, 50d) has a comb shape, and is disposed on the weight portion (30) so as to mesh with each of the first detection electrode and the second detection electrode. The angular velocity sensor according to claim 4, wherein opposing comb teeth (36) are formed.