JPH11271064A - Angular velocity sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the detection sensitivity of the angular velocity, by adjusting the oscillation frequency of an oscillator at a high accuracy for a short time. SOLUTION: A first oscillator 6 supported by a first support beam 5 so as to be capable of oscillation in a Y-axis direction parallel to a base 2 and second oscillator 8 supported horizontally in the first oscillator 6 through a second support beam 7 so as to be capable of oscillating in a Z-axis direction perpendicular to the Y-axis and base 2, are mounted on the base, the second support beam 7 has a protrusion 7A, and a notch 9 is provided at the middle of the protrusion 7A to equalize a first resonance frequency of the first oscillator 6 oscillating in the Y-axis direction to a second resonance frequency of the second oscillator 8 oscillating in the Z-axis direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an angular velocity sensor suitable for detecting, for example, the rotational direction and attitude of a vehicle or an aircraft.

[0002]

2. Description of the Related Art Recently, a vibration type angular velocity sensor has been developed as a relatively small angular velocity sensor manufactured by a fine processing technique. This type of angular velocity sensor electrically detects displacement acting on a vibrating body as an angular velocity using a piezoelectric material, utilizing the fact that the Coriolis force is proportional to the angular velocity.

A conventional angular velocity sensor of this kind is
In order to increase the sensitivity, it is required to increase the amplitude of the vibrating body that vibrates due to the Coriolis force. Further, in order to keep the sensitivity of each angular velocity sensor constant, it is necessary to keep the frequency at which the vibrating body vibrates.

[0004] However, since it is difficult to manufacture the vibrators with completely the same shape and size and mass, there is a problem that the sensitivity and noise characteristics vary among the angular velocity sensors. For this reason, for example, Japanese Patent Application Laid-Open No. 8-114460 discloses that the frequency of the vibrating body is adjusted to be high and low by slightly increasing and decreasing the mass of the vibrating body.

[0005]

In the angular velocity sensor according to the prior art described above, in order to increase the mass of the vibrating body, a substance is attached to the vibrating body by vapor deposition or the like.
In order to reduce the mass of the vibrating body, it is necessary to remove a substance attached in advance using a laser beam or the like. As described above, since a relatively long time is required to attach and remove a substance to and from the vibrating body, there is a problem that the productivity of the angular velocity sensor is reduced.

For example, in the angular velocity sensor, a vibrating body provided so as to be capable of vibrating in the horizontal and vertical directions with respect to the substrate is vibrated in the horizontal direction with respect to the substrate by vibration generating means.
There is a type that detects a displacement amount when the vibrating body is displaced in the vertical direction in this state. In this type of angular velocity sensor, the displacement of the vibrating body increases when the resonance frequency when the vibrating body vibrates in the horizontal direction and the resonance frequency when the vibrating body vibrates in the vertical direction become substantially equal, and the detection accuracy is reduced. It is known to improve.

However, in the case of this type of angular velocity sensor, by increasing or decreasing the mass of the vibrating body, the frequency at which the vibrating body vibrates in the vertical direction is raised and lowered, and when the vibrating body is adjusted to be lower, the vibrating body becomes horizontal The frequency when oscillating in the direction also increases and decreases. For this reason, only the frequency at which the vibrating body vibrates in the vertical direction cannot be adjusted, and there is a problem that it is difficult to adjust the horizontal resonance frequency and the vertical resonance frequency of the vibrating body to substantially equal values. .

The present invention has been made in view of the above-mentioned problems of the prior art, and provides an angular velocity sensor capable of adjusting the frequency at which a vibrating body vibrates with high accuracy in a short time and improving the angular velocity detection accuracy. The purpose is to:

[0009]

According to a first aspect of the present invention, there is provided a semiconductor device comprising: a substrate; and the substrate is supported by the substrate via a support beam, and can vibrate horizontally and vertically with respect to the substrate. A vibrating body, a vibration generating means for vibrating the vibrating body in a horizontal direction with respect to the substrate, and when the vibrating body is displaced in a vertical direction in a state where vibration is given by the vibration generating means. In an angular velocity sensor comprising a displacement amount detecting means for detecting a displacement amount, the support beam is provided with a frequency reduction unit for lowering a resonance frequency when the vibrating body vibrates in a vertical direction.

[0010] With this configuration, the spring constant of the support beam can be reduced by the frequency reduction section, and the resonance frequency when the vibrating body vibrates in the vertical direction of the substrate can be reduced. For this reason, the vertical resonance frequency of the vibrating body is adjusted, and the amount of vertical displacement of the vibrating body when an angular velocity is applied is increased while the vibrating body is vibrating in the horizontal direction of the substrate by the vibration generating means. can do.

According to a second aspect of the present invention, there is provided a substrate, a first vibrator supported on the substrate via a first support beam, and provided to be capable of vibrating in a horizontal direction with respect to the substrate. A second vibrator horizontally supported by the first vibrator via a second support beam and provided to be capable of vibrating in the horizontal and vertical directions with respect to the substrate.
A vibrating body, vibration generating means for vibrating the first vibrating body in a horizontal direction with respect to the substrate, and the second vibrating body is displaced in a vertical direction while the vibration generating means is applying vibration. In the angular velocity sensor comprising a displacement amount detecting means for detecting a displacement amount when the second vibrating body vibrates in a vertical direction, the second supporting beam has a frequency reducing unit for lowering a resonance frequency when the second vibrating body vibrates in a vertical direction. It is characterized by having been provided.

[0012] With such a configuration, the spring constant of the second support beam is reduced by the frequency reduction section, and the second support beam is reduced.
Resonance frequency when the vibrating body vibrates in the vertical direction of the substrate can be reduced. For this reason, the vertical vibration frequency of the second vibrating body is adjusted, and the second vibration when an angular velocity is applied in a state where the first vibrating body is vibrating in the horizontal direction of the substrate by the vibration generating means. The vertical displacement of the body can be increased.

According to a third aspect of the present invention, the second support beam is provided with a protruding portion extending between the first vibrator and the second vibrator, and the frequency reducing portion is provided with the protruding portion. The notch is formed by notching in the middle of the ridge.

In this case, the spring constant of the second support beam can be determined by the ridge extending between the first and second vibrators. Since the notch is formed in the middle of the ridge, the spring constant of the second support beam can be reduced by the notch. For this reason, the vertical resonance frequency of the second vibrating body can be raised or lowered by the notch.

According to a fourth aspect of the present invention, the first vibrating body is a frame supported at both ends via a first support beam, and the second vibrating body is provided inside the first vibrating body. And a plate-like body that is supported in a cantilever manner via a second support beam.

Thus, by providing the frequency reduction portion on the second support beam that cantileverly supports the second vibrator, the spring constant of the second support beam is reduced, and the resonance frequency of the second vibrator is reduced. Can be lowered.

According to a fifth aspect of the present invention, in the polygonal frame of the first vibrating body, a second vibrating body composed of a polygon is disposed, and the second support beam is provided by the first vibrating body. And a plurality of vibrators are arranged along each side between the vibrators to form a multi-point support structure.
The frequency reduction section is provided for each of the second support beams.

Thus, the second vibrating body can be supported at multiple points so that it can vibrate in the vertical direction by the plurality of second supporting beams, and the frequency reducing section provided for each of the second supporting beams. Accordingly, the spring constant of the second support beam can be reduced, and the resonance frequency of the second vibrator can be reduced.

Further, the invention of claim 6 is that the first and second support beams and the first and second vibrators are integrally formed of a single crystal silicon material.

With this configuration, the first and second support beams and the first and second vibrators can be formed by using fine processing techniques such as isotropic etching and anisotropic etching. By irradiating the focused ion beam to the second support beam, a frequency reduction section can be formed.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an angular velocity sensor according to an embodiment of the present invention will be described in detail with reference to FIGS.

FIGS. 1 to 11 relate to a first embodiment of the present invention, in which 1 is an angular velocity sensor manufactured by using a micromachining technique, and 2 is a glass material so as to form a main body of the angular velocity sensor 1. The substrate 2 is formed in a rectangular plate shape. As shown in FIGS. 1 to 3, the substrate 2 has a recess 2A for accommodating a detection electrode 14 described later. Is formed. Here, for convenience, the longitudinal direction of the substrate 2 is defined as an X-axis direction, a direction orthogonal to the longitudinal direction is defined as a Y-axis direction, and a thickness direction is defined as a Z-axis direction. And
The X-axis direction and the Y-axis direction are both horizontal to the substrate 2, and the Z-axis direction is vertical to the substrate 2.

Reference numeral 3 denotes a movable portion formed on the substrate 2, and the movable portion 3 includes a support portion 4, a first support beam 5, a first vibrator 6, a second support beam 7, and a second support beam 4, which will be described later. Are arranged on the same plane. Also,
The movable portion 3 is integrally formed of, for example, a single crystal silicon material.

Reference numerals 4 and 4 denote support portions for supporting the movable portion 3 on the substrate 2. The support portions 4 are arranged to face each other in the X-axis direction and are fixed on the substrate 2.

Reference numerals 5, 5,... Denote first supporting beams that constitute a first vibration system together with the first vibrating body 6, and the supporting beams 5 support the four corners of the vibrating body 6 to support the four corners. Part 4 and vibrating body 6
, Two in each case, a total of four in total.
For this reason, the base end side of the support beam 5 is a fixed end connected to the support portion 4, and the distal end side is a free end connected to a first vibrator 6 described later. Thereby, these support beams 5 support the vibrating body 6 at both ends.

The first support beams 5 are provided above the substrate 2 at a distance from each other, and extend in parallel in the X-axis direction. And the first support beam 5 is
As shown in FIG. 2, it has a length L1 extending in the X-axis direction and a width L2 in the Y-axis direction. Therefore, the support beam 5
Has a first spring constant K1 substantially determined by a length dimension L1 and a width dimension L2, and allows the first vibrating body 6 to be displaced in the Y-axis direction, and to be displaced in the X-axis direction and the Z-axis direction. It regulates displacement.

Reference numeral 6 denotes a first vibrating body supported by four support beams 5 so as to be displaceable in the Y-axis direction. The vibrating body 6 is formed of a substantially rectangular frame, and the frame includes a first vibrator to be described later. A second vibrator 8 supported by two support beams 7 is provided. The first vibrating body 6 includes first vibrating members at both ends in the X-axis direction.
The supporting beams 5 are connected, and movable comb electrodes 10, 10 described later are provided at both ends in the Y-axis direction.

The first vibration system satisfies the following equation 1 by the spring constant K1 of the support beam 5 and the mass m1 obtained by adding the masses of the first and second vibrators 6 and 8. It has a resonance frequency f1.

[0029]

(Equation 1)

Reference numerals 7 and 7 denote second supporting beams which constitute a second vibration system together with the second vibrating body 8, and the supporting beams 7 are provided in the first vibrating body 6 and are provided with the first vibrating body. The second vibrating body 8 is supported by the cantilever in the body 6 so as to be horizontal with the substrate 2. For this reason, the base end of the support beam 7 is a fixed end connected to the first vibrating body 6, and the front end is a free end extending toward the center of the substrate 2. A second vibrating body 8 is connected to the distal end of the support beam 7. In addition, the support beam 7
The vibrating body 8 is provided above and separated from the substrate 2, and the two supporting beams 7 are separated in the X-axis direction and extend in parallel in the Y-axis direction.

The second support beam 7 is shown in FIGS.
As shown in the figure, the length L3 extends in the X-axis direction and the height L4 in the Z-axis direction. For this reason, the support beam 7 has a second spring constant K2 substantially determined by the length L3 and the height L4, and allows the second vibrating body 8 to be displaced in the Z-axis direction. The displacement in the axial direction and the Y-axis direction is restricted.

As shown in FIG. 4, each support beam 7 is provided with a ridge 7A projecting upward, which is away from the substrate 2, and the ridge 7A is provided on the support beam 7. Extending in the X-axis direction, both end sides of the ridge 7A are connected to the first and second vibrators 6 and 8, respectively. The protruding ridge 7A has a substantially triangular cross-sectional shape, and the tip thereof has a sharp pointed end 7A.
B.

Reference numeral 8 denotes a second vibrating member which is located in the first vibrating member 6 and is supported by two supporting beams 7 so as to be displaceable in the Z-axis direction. The vibrating member 8 is formed in a substantially rectangular shape. And the substrate 2
Is disposed facing the detection electrode 14 provided in the recess 2A.

The second vibration system has a second resonance frequency f2 that satisfies the following expression 2 by the spring constant K2 of the support beam 7 and the mass m2 of the second vibrating body 8.

[0035]

(Equation 2)

A notch 9 is provided in the second support beam 7 as a frequency reducing portion. The notch 9 is formed by notching a point 7B of a ridge 7A and extends in the X-axis direction. It is provided in the middle of the ridge 7A. Notch 9
Is the length L5 in the Y-axis direction as shown in FIGS.
And a depth L6 recessed from the pointed end 7B of the ridge 7A. The notch 9 has a length L5,
By increasing the depth dimension L6, the support beam 7
Is reduced, and the second resonance frequency f2 is lowered.

Reference numerals 10 and 10 denote movable comb-shaped electrodes formed on both end surfaces of the first vibrating body 6 in the Y-axis direction. The movable comb-shaped electrodes 10 are plural as shown in FIGS. Of the electrode plates 10A, 10A. The movable comb electrode 10 and the fixed comb electrode 12 to be described later constitute a vibration generator 13.

Reference numerals 11 and 11 denote a pair of fixed portions provided on both ends of the vibrating body 6 in the Y-axis direction, and the fixed portions 11 are fixed on the substrate 2. On the end face of each fixed portion 11, fixed-side comb-shaped electrodes 12, 12 each composed of a plurality of electrode plates 12A, 12A,... Are formed. Meshing and facing.

Numerals 13 and 13 denote vibration generating sections as vibration generating means. Each of the vibration generating sections 13 is composed of a movable comb electrode 10 and a fixed comb electrode 12. And
A drive signal having a frequency f0 is alternately applied to each of the vibration generators 13 to generate an electrostatic attraction between one of the electrode plates 10A and 12A and the other of the electrode plates 10A and 12A alternately. Thus, the vibration generating unit 13 causes the first vibrating body 6 to vibrate in the Y-axis direction along the arrow A in FIG. 2 together with the second vibrating body 8.

Reference numeral 14 denotes a detection electrode fixed in the recessed portion 2A of the substrate 2. The detection electrode 14 is located below the second vibrating body 8 and is arranged at a distance from the vibrating body 8. The detection electrode 14 constitutes a displacement detecting means together with the lower surface of the second vibrating body 8 facing the detecting electrode 14, and the vibrating body 8
The change in the distance between the sensor and the detection electrode 14 in the Z-axis direction is detected as a change in capacitance between the two.

Reference numerals 15 and 15 denote vibration-driving electrode pads fixed to the respective fixing portions 11, respectively.
5 is electrically connected to each fixed-side comb-shaped electrode 12.
Reference numeral 16 denotes a detection electrode pad fixed on the substrate 2, and the electrode pad 16 is electrically connected to the detection electrode 14.

The angular velocity sensor according to the present embodiment has the above-described configuration. Next, a method of manufacturing the angular velocity sensor will be described with reference to FIGS.

First, a concave portion 2A is formed in a substrate 2 made of a glass material, and a detection electrode 14 is fixed to the concave portion 2A. Then, in the bonding step shown in FIG. 6, a silicon layer 17A, 1 made of a single crystal silicon material is
7B, an oxide film layer 17C made of a silicon oxide material, and an SOI (Silicon on Insul).
a) The substrate 17 is bonded using a method such as anodic bonding.

At this time, for example, the thickness of the substrate 2 is 5
A silicon layer 17A of 0 μm is bonded, and this silicon layer 17A becomes an active layer for forming the first and second support beams 5 and 7, the first and second vibrators 6 and 8, and the like. .

Next, in the ridge mask forming step shown in FIGS. 7 and 8, the silicon layer 17A and the oxide film layer 17C are interposed by performing wet etching or dry etching with an aqueous alkali solution such as KOH. Then, the upper silicon layer 17B bonded on the substrate 2 is removed.

Then, a resist is applied on the oxide film layer 17C, pattern-formed, and etched. As a result, openings 18 and 18 as shown in FIG. 8 are formed on the upper side of the silicon layer 17A to be the protrusion 7A.

Next, in the ridge portion forming step, the oxide film layer 17 is formed.
Using C as a mask, isotropic etching is performed from the opening 18. As a result, the portion of the silicon layer 17A that becomes the second support beam 7 becomes thinner to the height L4, and the silicon layer 17A has a cross-sectional shape that is pointed upward as shown by a two-dot chain line in FIG. A ridge 7A is formed.

In the step of forming a movable portion mask shown in FIGS. 9 and 10, the oxide film layer 17C is removed by etching and a new resist 19 is applied. In this case, the resist 19 includes the first and second support beams 5,
7, pattern forming is performed so that portions where the first and second vibrators 6 and 8 are formed remain. At this time, as shown in FIG. 10, the resist 19 remains on the ridge 7A.

Next, in the movable portion forming step, the resist 19
Is used as a mask, anisotropic etching for selectively etching the silicon layer 17A in the Z-axis direction of the substrate 2 is performed. As a result, the silicon layer 17A is processed in the Z-axis direction up to the substrate 2, and the support portion 4, as shown in FIGS.
First and second support beams 5, 7, first and second vibrators 6, 8
And the fixing portion 11 and the like are formed. At this time, the first and second vibration systems are set so that the resonance frequency f2 of the second vibration system is slightly higher than the resonance frequency f1 of the first vibration system.
The second support beams 5, 7 and the first and second vibrators 6, 8 are formed. After the movable portion forming step, the drive electrode pad 15 is formed on the fixed portion 11.

Finally, in the frequency adjustment step shown in FIG. 11, a focused ion beam S capable of narrowing the beam spot diameter to about 0.1 μm, for example, is irradiated to the vicinity of the tip 7B of the ridge 7A of the support beam 7. Then, the focused ion beam S is reciprocated in the direction indicated by the arrow B in FIG. 11, which is the Y-axis direction of the substrate 2, so that the ridge 7A is notched and trimmed to form the notch 9. As a result, the resonance frequency f2 of the second vibration system is reduced, and the first and second resonance frequencies f2 are reduced.
1, f2 can be set to approximately equal frequencies.

In particular, the vicinity of the tip 7B of the ridge 7A is trimmed by the focused ion beam S and cut out, so that damage to the substrate 2, the detection electrode 14, and the like located below the support beam 7 is prevented. And the time required for adjusting the resonance frequency f2 can be shortened.

For example, as in the first comparative example shown in FIG. 12, a second support beam 20 is formed in a rectangular cross section, and this support beam 20 is irradiated with a focused ion beam S. Is cut out over the entire width in the arrow B direction. In this case, although the resonance frequency f2 of the second vibration system can be lowered, the focused ion beam S is also applied to the substrate 2 or the like to form the groove 21 and may damage the substrate 2 or the like.

On the other hand, in the present embodiment, the support beam 7
The focused ion beam S only needs to be irradiated to the vicinity of the tip 7B of the ridge 7A, so that the focused ion beam S is not irradiated to portions other than the support beam 7, and damage to the substrate 2 and the like can be prevented. it can.

Further, as in the second comparative example shown in FIG. 13, the focused ion beam S is applied only to the vicinity of the center in the Y-axis direction of the support beam 20 having a rectangular cross section to form the concave portion 22. A method of processing the support beam 20 into a U-shaped cross section is also conceivable. According to this method, although the damage of the substrate 2 and the like can be prevented, the spring constant K2 of the support beam 20 is hardly changed. For this reason, in order to lower the resonance frequency f2, a larger concave portion 22 is required, and the resonance frequency f2 is reduced.
A large amount of processing time is required to perform the adjustment 2, and the productivity is reduced.

On the other hand, in the present embodiment, the support beam 7
The height L4 of the support beam 7 is reduced even if the vicinity of the tip 7B of the ridge 7A is slightly cut away.
Can easily be reduced, the processing time required for adjusting the resonance frequency f2 can be shortened, and the productivity can be improved.

The angular velocity sensor according to the present embodiment is manufactured in this manner, and then has an angular velocity Ω around the X axis.
The basic detection operation in the case of adding is described.

First, when a drive signal having a frequency f0 is applied to each of the vibration generators 13, the respective vibration generators 13
The first vibrating body 6 is vibrated together with the second vibrating body 8 in the direction indicated by the arrow A in FIG. 2 which is the Y-axis direction (horizontal direction) of the substrate 2 by the electrostatic attraction generated between 0A and 12A. At this time, in order to further increase the amplitude of the first vibrating body 6 and the like,
The frequency f0 is set to a value substantially equal to the resonance frequency f1 of the first vibration system.

When an angular velocity Ω is applied around the X axis in a state where the first and second vibrators 6 and 8 are vibrating in the direction of arrow A, as shown in FIG. In the direction (vertical direction), a Coriolis force F (inertial force) shown in the following Expression 3 is generated.

[0059]

F = 2 m 2 Ωv, where v: velocity of the second vibrating body 8 in the Z-axis direction

The second Coriolis force F causes the second
Vibrator 8 vibrates in the Z-axis direction. At this time, the notch 9 provided in the second support beam 7 adjusts the resonance frequency f1 of the first vibration system and the resonance frequency f2 of the second vibration system to be substantially equal. Resonance frequency f1
, F2 are different from each other, the amplitude of the second vibrating body 8 in the Z-axis direction is increased by resonance. For this reason, since the displacement amount of the second vibrating body 8 can be increased, the angular velocity Ω applied around the X axis can be detected with high accuracy.

Thus, according to the present embodiment, since the notch 9 is provided in the second support beam 7, the notch 9 can reduce the spring constant K2 of the second support beam 7.
The second resonance frequency f2 when the second vibrator 8 vibrates in the Z-axis direction can be reduced. Thereby, the first resonance frequency f1 when the first vibrating body 6 vibrates in the Y-axis direction and the second resonance frequency f1 when the vibrating body 8 vibrates in the Z-axis direction.
Can be made substantially equal to the resonance frequency f2 of
Vibration due to the Coriolis force F is amplified and increased, and the detection accuracy of the angular velocity Ω applied around the X axis can be improved.

The second support beam 7 is provided with a ridge 7A, and the ridge 7A extending between the first and second vibrators 6 and 8 is provided.
Since the notch 9 is provided in the middle of A, by providing the notch 9 slightly depressed from the pointed end 7B of the ridge 7A,
The second resonance frequency f2 can be easily reduced.

Further, the second vibrating body 8 is
And cantilever supported by the second support beam 7, the number of support beams 7 can be reduced to at least one as compared with a case where the second vibrating body 8 is supported at both ends, for example. Since the number of locations where the cutouts 9 are provided can be reduced, the time for adjusting the second resonance frequency f2 can be shortened.

Further, since the first and second support beams 5, 7 and the first and second vibrators 6, 8 are integrally formed in the same plane using a single crystal silicon material, a fine processing technique is used. A plurality of angular velocity sensors can be easily manufactured from a silicon wafer of the same material using the same material, an angular velocity sensor having uniform characteristics can be effectively mass-produced, and the cost can be significantly reduced. Also, by performing isotropic etching and anisotropic etching, the ridge portion 7A can be easily formed on the second support beam 7.

Next, FIG. 14 shows a second embodiment of the present invention. The feature of this embodiment is that the second vibrating body is held in a horizontal state with respect to the substrate and in a direction perpendicular to the substrate. That is, the second vibrating body is supported by four second supporting beams so as to be able to vibrate. In this embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

Reference numeral 31 denotes a movable portion according to the present embodiment. Like the movable portion 3 according to the first embodiment, the movable portion 31 includes a first support beam 32, a first vibrating body 33, and a second The movable part 3 is constituted by a support beam 34, a second vibrating body 35, and the like.
Numerals 1 are arranged on the substrate 2 at intervals.

Are first support beams for supporting the first vibrating body 33 on both sides, and the support beams 32 are respectively two from two support portions (not shown). Extend four,
It is connected to both ends of the first vibrating body 33.

Reference numeral 33 denotes a first vibrating body. The vibrating body 33 is formed of a substantially square frame and is supported by four first support beams 32 so as to be able to vibrate horizontally with respect to the substrate 2. Supported.

Reference numerals 34, 34,... Denote second support beams, which are located within the frame of the first vibrating body 33 and support the second vibrating body 35 so as to be able to vibrate vertically with respect to the substrate 2. The four beams 34 are arranged between the first and second vibrators 33 and 35 and extend four along each side of the first vibrator 33 to form a four-point support structure. The supporting beam 34 has a base end on the vibrating body 33.
And the front end side is connected to four corners of the second vibrating body 35.

Each of the four support beams 34 has a first
A protrusion 34A similar to the protrusion 7A according to the embodiment is formed so as to protrude in a direction away from the substrate 2, and the protrusion 34A is formed.
A is formed over the entire length of the support beam 34 extending along the vibrating body 33.

Reference numeral 35 denotes a second vibrator disposed within the frame of the first vibrator 33. The vibrator 35 is formed in a substantially square plate shape and has the same length as one side thereof. The substrate 2 is supported at four points so as to be able to vibrate in the vertical direction with respect to the substrate 2 by a second support beam 34 having a total length of the order. The second vibrating body 3
Numerals 5 are arranged at an interval in a state where they are kept horizontal with respect to the substrate 2, and a detection electrode 14 is fixed to the substrate 2 between the second vibrating body 35 and the substrate 2.

.. Are notches for adjusting the spring constant of the second support beam 34. The notch 36 extends over the entire length of the support beam 34 in the same manner as the notch 9 according to the first embodiment. It is provided in the middle of the protruding ridge portion 34A and has a relatively long length along the support beam 34.

The notch 36 has a resonance frequency in the horizontal direction when the first vibrator 33 and the like vibrates in the horizontal direction with respect to the substrate 2 and the second vibrator 35 vibrates in the vertical direction with respect to the substrate 2. The vertical resonance frequency at that time is adjusted so as to be substantially equal to the resonance frequency.

Numerals 37, 37 denote movable comb-shaped electrodes formed on both end faces of the first vibrating body 33.
Numeral 7 comprises a plurality of electrode plates 37A similarly to the movable comb electrode 10 of the first embodiment, and the fixed comb electrode 1
2. The movable-side comb-shaped electrode 37 and the fixed-side comb-shaped electrode 12 constitute a vibration generator 38.

Thus, in the embodiment of the present invention configured as described above, substantially the same operation and effect as those of the first embodiment can be obtained. However, in the embodiment of the present invention, the second embodiment has the following advantages. Since the vibrating body 35 is configured to be supported at four points by the four second supporting beams 34, Coriolis force causes
In a state where the second vibrating body 35 is horizontal with respect to the substrate 2,
Since it can be displaced in the vertical direction with respect to the substrate 2,
The capacitance can be changed more accurately in proportion to the distance between the second vibrating body 35 and the detection electrode 14 than when the second vibrating body 35 is cantilevered. For this reason,
As compared with the case where the second vibrating body 35 is cantilevered, the angular velocity can be detected easily and accurately from the capacitance between the second vibrating body 35 and the detection electrode 14.

The length of the second support beam 34 is set to the second
Since the length of one side of the vibrator 35 is set to be substantially the same as the length of one side of the vibrator 35, the second vibrator 35 can be vibrated more in the vertical direction, and the detection accuracy of the angular velocity can be improved.

Next, FIG. 15 shows a third embodiment of the present invention. The feature of this embodiment is that the vibrating body is supported by four supporting beams so as to be able to vibrate horizontally and vertically with respect to the substrate. It is in. In this embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

Reference numeral 41 denotes a movable portion of the present embodiment. The movable portion 41 includes a support portion 42, a support beam 43, a vibrating body 44, and the like, which will be described later.
The support members 42 are arranged on the substrate 2 at intervals.

Reference numerals 43, 43,... Denote support beams for supporting the vibrating body 44 at both ends. The supporting beams 43 extend from the two supporting portions 42, two in total, four in total, and the vibrating body 4 has a rectangular shape.
4 are connected to both ends in the longitudinal direction. The support beam 43 supports the vibrating body 44 so as to be able to vibrate in the horizontal and vertical directions with respect to the substrate 2.

Each of the four support beams 43 has a first
A ridge 43A similar to the ridge 7A according to the embodiment is formed so as to protrude in a direction away from the substrate 2, and the ridge 43A is formed.
A is formed so as to extend substantially linearly over the entire length of the support beam 43.

Reference numeral 44 denotes a vibrating body. The vibrating body 44 is formed in a substantially rectangular plate shape, and is supported at both ends by four support beams 43 so as to be capable of vibrating in the horizontal and vertical directions with respect to the substrate 2. .

Are cutouts for adjusting the spring constant of the support beam 43 when the vibrating body 44 vibrates in the direction perpendicular to the substrate 2, and the cutouts 45 are cutouts according to the first embodiment. Like the portion 9, it is provided in the middle of a ridge 43 A extending over the entire length of the support beam 43, and has a relatively long length along the support beam 43.

The notch 45 is provided so that the vibrating body 44
In contrast, the resonance frequency in the horizontal direction when vibrating in the horizontal direction and the resonance frequency in the vertical direction when the vibrating body 44 vibrates in the vertical direction with respect to the substrate 2 are adjusted to have substantially the same value.

Reference numerals 46, 46 denote movable comb-shaped electrodes formed on both end faces in the direction orthogonal to the longitudinal direction of the vibrating body 44. The movable comb-shaped electrodes 46 are the movable comb-shaped electrodes of the first embodiment. It is composed of a plurality of electrode plates 46A similarly to the electrode 10,
It faces the fixed-side comb-shaped electrode 12. The movable-side comb-shaped electrode 46 and the fixed-side comb-shaped electrode 12 constitute a vibration generator 47.

Thus, also in the embodiment of the present invention configured as described above, it is possible to obtain substantially the same operation and effect as those of the above embodiments.

In the first embodiment, the second vibrating member 8 is cantilevered by the second support beam 7. However, the second vibrating member 8 is supported from both sides and is supported by both ends. A beam type configuration may be used.

Further, in the second embodiment, the rectangular second frame 33 is provided inside the first vibrating body 33 formed of a rectangular frame.
Is disposed, and the second vibrating body 35 having the rectangular shape is disposed.
Is supported at four points by the four second support beams 34. For example, a pentagonal second vibrator is disposed inside a first vibrator composed of a pentagonal frame, and the pentagonal The second vibrator may be supported at five points by five second support beams, or may be configured to support other polygonal second vibrators at multiple points.

In each of the above embodiments, the notch 9
(36, 45) is provided in the middle of the ridge 7A (34A, 43A) extending over the entire length of the support beam 7 (34, 43). The notch may be formed by removing the pointed end of the ridge over the entire length.

Further, in each of the above embodiments, the case of using as an independent single angular velocity sensor has been described as an example. However, the present invention is not limited to this, and for example, a part of another substrate mounted on a vehicle may be used. A plurality of angular velocity sensors may be formed.

[0090]

As described above in detail, according to the first aspect of the present invention, since the frequency reduction portion is provided on the support beam, the spring constant in the vertical direction of the support beam can be reduced by the frequency reduction portion. Can be reduced in the vertical direction when the substrate vibrates in the direction perpendicular to the substrate. As a result, the resonance frequency in the horizontal direction and the resonance frequency in the vertical direction when the vibrating body vibrates in the horizontal direction can be set to substantially the same value. Can be improved.

According to the second aspect of the present invention, since the frequency reduction unit is provided on the second support beam, the spring constant of the second support beam can be reduced by the frequency reduction unit.
The second resonance frequency when the vibrating body vibrates in the direction perpendicular to the substrate can be reduced. Thereby, the first resonance frequency and the second resonance frequency when the first vibrating body or the like vibrates in the horizontal direction can be set to substantially the same value, and the vibration due to the Coriolis force is amplified and increased. Angular velocity detection accuracy can be improved.

According to the third aspect of the present invention, the second support beam is provided with a ridge, and a frequency reduction portion is provided in the middle of the ridge extending between the second support beam and the first and second vibrators. Since the notch portion is provided, the second resonance frequency when the second vibrating body vibrates in the vertical direction can be easily reduced by providing the notch portion in which the tip of the ridge portion is slightly notched. it can.

According to the fourth aspect of the present invention, the second vibrating body is constituted by a plate-like body which is positioned inside the first vibrating body and is cantilevered via the second supporting beam. Therefore, the number of locations where the frequency reduction unit is provided can be reduced, and the time for adjusting the second resonance frequency can be shortened.

According to the fifth aspect of the present invention, since the second vibrator is supported at multiple points by the plurality of second support beams, the second vibrator is mounted on the substrate by Coriolis force. On the other hand, when the second vibrator is cantilevered, the capacitance can be more accurately changed since the second vibrator can be displaced in the vertical direction with respect to the substrate in a horizontal state. Therefore, the angular velocity can be detected easily and accurately as compared with a case where the second vibrating body is cantilevered.

Furthermore, according to the invention of claim 6, according to the first,
Since the first support beam and the first and second vibrators are integrally formed of a single crystal silicon material, an angular velocity sensor having uniform characteristics can be effectively mass-produced, and the cost can be reduced. Further, by performing isotropic etching and anisotropic etching, the ridge portion can be easily formed on the second support beam.

[Brief description of the drawings]

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

FIG. 2 is an enlarged front view showing first and second support beams, first and second vibrators, and the like in FIG. 1;

FIG. 3 is a longitudinal sectional view showing the first and second support beams, the first and second vibrators, and the like, as viewed from the direction of arrows III-III in FIG. 2;

FIG. 4 is an enlarged perspective view showing a part a in FIG. 3;

FIG. 5 is an enlarged view of a second support beam, which is indicated by an arrow V- in FIG.
It is sectional drawing seen from the V direction.

FIG. 6 is a longitudinal sectional view showing a bonding step between a substrate and an SOI substrate.

FIG. 7 is a vertical cross-sectional view showing a ridge mask forming step following the joining step.

FIG. 8 is a cross-sectional view as seen from the direction of arrows VIII-VIII in FIG.

FIG. 9 is a longitudinal sectional view showing a mask forming step for a movable portion.

FIG. 10 is a cross-sectional view as seen from the direction of arrows XX in FIG. 9;

FIG. 11 is a cross-sectional view of the same position as FIG. 5 showing a state in which a notch is formed in a second support beam by a frequency adjustment step.

FIG. 12 is a cross-sectional view of the same position as FIG. 5 showing a state in which a notch is formed in a second support beam as a first comparative example.

FIG. 13 is a cross-sectional view of a position similar to FIG. 5 showing a state in which a notch is formed in a second support beam as a second comparative example.

FIG. 14 shows a second example of the angular velocity sensor according to the second embodiment.
FIG. 5 is an enlarged front view showing a support beam, a second vibrating body, and the like of FIG.

FIG. 15 is a front view of the angular velocity sensor according to the third embodiment at the same position as in FIG. 2;

[Explanation of symbols]

 2 Substrate 5, 32 First support beam 6, 33 First vibrator 7, 34 Second support beam 7A, 34A, 43A Ridge 8, 35 Second vibrator 9, 36, 45 Notch 13 , 38, 47 Vibration generator (vibration generator) 14 Detection electrode 43 Support beam 44 Vibrator

Claims (6)

[Claims] 1. A substrate, a vibrator supported on the substrate via a support beam, and provided to be capable of vibrating in horizontal and vertical directions with respect to the substrate, and vibrating the vibrator in a horizontal direction with respect to the substrate. An angular velocity sensor comprising: a vibration generating means for causing the vibration body to vibrate, and a displacement amount detecting means for detecting a displacement amount when the vibrating body is displaced in a vertical direction. An angular velocity sensor provided with a frequency reduction section for lowering a resonance frequency when the vibrating body vibrates in a vertical direction. 2. A substrate, a first vibrator supported on the substrate via a first support beam, and provided so as to be capable of vibrating in a horizontal direction with respect to the substrate, and a first vibrator provided on the first vibrator. A second vibrator supported horizontally via the second support beam and capable of vibrating in the horizontal and vertical directions with respect to the substrate; and vibrating the first vibrator in the horizontal direction with respect to the substrate. An angular velocity sensor comprising: a vibration generating unit; and a displacement amount detecting unit that detects a displacement amount when the second vibrating body is displaced in a vertical direction while the vibration generating unit is applying vibration. The angular velocity sensor according to claim 2, wherein the second support beam is provided with a frequency reduction unit that lowers a resonance frequency when the second vibrator vibrates in the vertical direction. 3. The second support beam is provided with a ridge extending between the first vibrator and the second vibrator, and the frequency reducing section is cut in the middle of the ridge. The angular velocity sensor according to claim 2, wherein the angular velocity sensor is a notch formed by notching. 4. The first vibrating body comprises a frame body supported at both ends via a first support beam, and the second vibrating body is located inside the first vibrating body. The angular velocity sensor according to claim 2, wherein the angular velocity sensor is formed of a plate-like body that is cantilevered via two support beams. 5. A polygonal second vibrator is disposed within a polygonal frame of the first vibrator, and the second support beam includes a first vibrator and a second vibrator. 4. The angular velocity sensor according to claim 2, wherein a plurality of the plurality of support members are arranged along each side between the second support beams, and the frequency reduction section is provided for each of the second support beams. 6. The angular velocity sensor according to claim 2, wherein the first and second support beams and the first and second vibrators are formed integrally from a single crystal silicon material.