JPH1096633A - Angular speed detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease an air damping generated between a vibrator and a substrate and increase vibration of the vibrator and prevent noises from excitation means from leaking to displacement detection means. SOLUTION: A plurality of communicating holes 30 are formed in a portion placed on a downward side of a vibrator 33 on a substrate 22. Thereby, when the vibrator 33 vibrates, an air existing between the vibrator 33 and the substrate 22 passes through each communicating hole 30 and flows out to a reverse face side of the substrate 22. Therefore, an air damping can be reduced. Further, a recessed part 28 is provided in the substrate 22 and a portion located on a downward side of a displacement detection electrode 37 on the substrate 22 is made as a thin part 29 only comprising an insulating film 24.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an angular velocity detecting device for detecting an angular velocity, which is used for a gyro mounted on, for example, an automobile or a camera.

[0002]

2. Description of the Related Art FIG.
A description will be given based on FIG.

In FIG. 19, reference numeral 1 denotes an angular velocity detecting device manufactured by a micromachining technique. 2 is a substrate made of, for example, a high-resistance single-crystal silicon material,
As shown in FIG. 20, an insulating layer 2A is formed on the substrate 2 by oxidizing the surface.

[0004] Reference numerals 3 and 3 denote support portions provided on the substrate 2 via the insulating layer 2A. Reference numeral 4 denotes a vibrator provided at a distance from the surface of the substrate 2, and the vibrator 4 is supported by the support portion 3 via four support beams 5, 5,. Direction, and can be displaced in the orthogonal direction. The vibrator 4 has a length dimension of, for example, about 800 μm,
It is formed in a thin plate shape having a width of about 400 μm and a thickness of about 5 μm. Further, as shown in FIG. 20, the distance S between the vibrator 4 and the substrate 2 is very small, for example, about 1 μm.

Further, the support portions 3, the vibrator 4, and the support beams 5, for example, are formed by etching low-resistance polysilicon doped with impurities such as P, B, and Sb.

Reference numerals 6, 6,... Denote a large number of etching holes formed in the vibrator 4. Each of the etching holes 6 is formed so as to penetrate between the front side and the back side of the vibrator 4.

Here, each of the etching holes 6 is formed to surely remove the sacrificial layer formed between the vibrator 4 and the substrate 2 by using an etching solution when the angular velocity detecting device 1 is manufactured. Things.

That is, in order to provide the vibrator 4 in a state of being floated from the surface of the substrate 2 by a small distance so as to secure the separation distance S between the vibrator 4 and the substrate 2, first,
A sacrificial layer is formed thereon, and polysilicon for forming the vibrator 4 is laminated on the sacrificial layer. Next, the vibrator 4 is formed by removing a part of the polysilicon by etching. Then, the sacrificial layer between the vibrator 4 and the substrate 2 is removed with an etching solution. At this time, the separation distance S between the vibrator 4 and the substrate 2 is small and the etching solution is difficult to flow, so that it is easy to reliably remove the sacrificial layer between the vibrator 4 and the substrate 2 within a predetermined time. Not.

Therefore, when a large number of etching holes 6 are formed in the vibrator 4 and the sacrificial layer between the vibrator 4 and the substrate 2 is removed by an etching solution, this etching solution is passed through each of the etching holes 6. A large amount is circulated between the vibrator 4 and the substrate 2. This allows
The sacrificial layer between the vibrator 4 and the substrate 2 can be reliably removed.

Reference numerals 7, 7 denote electrode supporting portions located on both sides of the vibrator 4 and provided on the substrate 2 via the insulating layer 2A.
Reference numerals 8 and 8 denote excitation electrodes as excitation means for vibrating the vibrator 4 in the direction indicated by the arrow X. Each of the excitation electrodes 8 is formed in a comb-like manner on each of the electrode support portions 7 so as to mesh with electrode plates 8A, 8A,... Provided on the vibrator 4 in a state of being separated from the respective electrode plates 8A. .. Are provided. Further, each of the electrode support portions 7 and the electrode plate 8
A and 8B are formed, for example, by etching low-resistance polysilicon doped with impurities such as P, B, and Sb.

Reference numeral 9 denotes a lower part of the vibrator 4.
A displacement detection electrode as displacement detection means provided on the surface of the substrate 2 so as to face
For example, it is formed to have conductivity by doping the surface of the substrate 2 with impurities such as P and Sb at a high density. The displacement detecting electrode 9 detects the amount of displacement when the vibrator 4 is displaced in the direction indicated by the arrow Z due to Coriolis force.

Numerals 10 and 10 denote excitation electrode pads fixed on the respective electrode supporting portions 7, and the respective electrode pads 10 are electrically connected to the respective electrode plates 8B provided on the respective electrode supporting portions 7. Conducted. An oscillation circuit or the like (not shown) for applying an excitation signal as a vibration signal to each electrode plate 8B of each excitation electrode 8 is connected to each electrode pad 10.

Reference numeral 11 denotes a detection electrode pad fixed on the support portion 3, and reference numeral 12 denotes a detection electrode pad connected to the displacement detection electrode 9 via a lead wire 12A. Is connected to a detection circuit or the like (not shown) for detecting a change in capacitance between the vibrator 4 and the displacement detection electrode 9.

The angular velocity detecting device according to the prior art has the above-described configuration, and its operation will now be described.

When excitation signals having opposite phases are applied to the respective electrode plates 8B of the respective excitation electrodes 8 from the oscillation circuit via the respective electrode pads 10, the vibrator 4 moves in the direction parallel to the substrate 2 (arrow X). Direction). When a rotation about the rotation axis Y acts in this state, a Coriolis force corresponding to the angular velocity of the rotation is generated, so that the vibrator 4 is displaced in a direction perpendicular to the substrate 2 (Z direction indicated by an arrow). When the vibrator 4 is displaced in the direction indicated by the arrow Z, the distance between the vibrator 4 and the displacement detection electrode 9 provided below the vibrator 4 changes. The capacitance with the displacement detection electrode 9 changes. This change in capacitance is detected by the electrode pads 11 and 1.
The angular velocity applied to the angular velocity detector 1 is detected by a detection circuit connected to the angular velocity detector 2.

[0016]

In the angular velocity detecting device 1 according to the prior art described above, the vibrator 4 and the substrate 2
Since the smaller the distance S from the distance is, the higher the detection sensitivity of the angular velocity is, the distance S is set to a minute value, for example, about 1 μm.

However, when the distance S between the vibrator 4 and the substrate 2 is set to a small value, the vibrator 4 is moved by arrow Z due to Coriolis force.
When vibrating in the direction, air damping (flow resistance of air) between the vibrator 4 and the substrate 2 increases. For this reason, there is a problem that the vibration of the vibrator 4 in the arrow Z direction is hindered by the air resistance existing between the vibrator 4 and the substrate 2, and the vibrator 4 cannot be largely displaced. As a result,
Even if the angular velocity acts, there is a problem that the change in the capacitance between the vibrator 4 and the substrate 2 becomes small, and the detection sensitivity of the angular velocity decreases.

Since a large number of etching holes 6 are formed in the vibrator 4, and each of the etching holes 6 penetrates the vibrator 4, when the vibrator 4 vibrates in the arrow Z direction, Some of the air existing between the substrate 4 and the substrate 2 is
After passing through each of the etching holes 6, it flows out to the surface side of the vibrator 4. Therefore, it can be considered that air damping can be reduced by the etching holes 6.

However, each of the etching holes 6 is a hole through which an etching solution flows when the vibrator 4 is formed, and has a small hole diameter.
Is small and escapes to the surface side of the vibrator 4. Further, it is difficult to increase the diameter of the etching holes 6 or increase the number of the etching holes 6 in order to maintain the strength of the vibrator 4. As a result, in practice, the air damping between the vibrator 4 and the substrate 2 cannot be sufficiently reduced only by the etching holes 6.

On the other hand, in the angular velocity detecting device 1 according to the prior art described above, a displacement detecting electrode 9 is formed on the surface of the substrate 2 and
When the vibrator 4 is displaced in the direction indicated by the arrow Z due to Coriolis force, a change in capacitance between the vibrator 4 and the substrate 2 is detected, and the angular velocity is determined.

However, in order to vibrate the vibrator 4 in the direction indicated by the arrow X, the excitation signal applied from the oscillation circuit to each electrode plate 8B of each excitation electrode 8 via each electrode pad 10 is shown in FIG. As indicated by the arrow A, the substrate 2 may be transmitted to leak to the displacement detection electrode 9. Then, the leaked excitation signal becomes a noise when detecting a change in capacitance between the vibrator 4 and the substrate 2, causing a problem that the detection sensitivity of the angular velocity is reduced.

The substrate 2 is made of a high-resistance single-crystal silicon material, and each electrode support 7 is provided on the substrate 2 via an insulating layer 2A. As a result, the current of the excitation signal leaking in the direction indicated by the arrow A in FIG. 20 is very small. However, since the change in the capacitance between the vibrator 4 and the substrate 2 due to the displacement of the vibrator 4 in the arrow Z direction is also small,
When detecting the angular velocity by amplifying the minute change in capacitance by the detection circuit or the like, even if a minute leakage current flows into the displacement detection electrode 9, it becomes a relatively nonnegligible noise. Is a factor that lowers the detection sensitivity.

The present invention has been made in view of the above-described problems of the prior art. The present invention reduces the damping (flow resistance) of a gas between a vibrator and a substrate so that the angular velocity can be reduced. It is another object of the present invention to provide an angular velocity detecting device in which a vibrator can be displaced in a direction perpendicular to a substrate without resistance.

Another object of the present invention is to provide an angular velocity detecting device capable of preventing noise from an exciting means or the like from leaking to a displacement detecting means via a substrate.

[0025]

Means for Solving the Problems In order to solve the above-mentioned problems, the invention according to claim 1 comprises a substrate, a support portion fixedly provided on the surface of the substrate, and a base end provided on the support portion. A supporting beam provided, a vibrator supported on the distal end side of the supporting beam in a state separated from the surface of the substrate and displaceable with respect to the substrate, and excitation means for vibrating the vibrator in a constant excitation direction And displacement detection for detecting that the vibrator is displaced in a direction perpendicular to the excitation direction in accordance with the angular velocity when an angular velocity acts while the vibrator is vibrated in the excitation direction by the excitation means. Means.

A feature of the invention according to claim 1 is that a communication hole communicating between the front surface side and the rear surface side of the substrate is provided at a position of the substrate facing the vibrator, and the communication hole is used for the communication hole. The configuration is such that a gas flows between the front side and the back side of the substrate.

According to the above configuration, when an angular velocity acts while the vibrator is vibrated in a constant excitation direction by the excitation means, the vibrator is displaced in a direction orthogonal to the excitation direction by Coriolis force. Here, when the excitation direction of the vibrator is parallel to the substrate, the vibrator is displaced in a direction perpendicular to the substrate by Coriolis force. On the other hand, when the excitation direction of the vibrator is orthogonal to the substrate, the vibrator is displaced in a direction parallel to the substrate by Coriolis force.

In any of the above cases, when the vibrator is displaced in the direction perpendicular to the substrate, the gas present between the vibrator and the substrate flows through the communication hole toward the front surface of the substrate. From the back side. Accordingly, damping (flow resistance) of gas between the vibrator and the substrate is reduced, and the vibrator is easily displaced in a direction orthogonal to the substrate.

According to a second aspect of the present invention, a concave portion is provided on the back side of the substrate such that a portion of the substrate facing the vibrator is a thin portion, and the thin portion is provided with a front surface side of the substrate. A communication hole that communicates with the back surface side is provided, and the communication hole allows gas to flow between the front surface side and the back surface side of the substrate.

According to the above configuration, by providing the communication hole in the thin portion of the substrate, the distance from the inlet to the outlet of the communication hole is reduced. Accordingly, the flow path of the air from the front surface side to the back surface side (inside the concave portion) of the substrate is shortened. Therefore, when the vibrator is displaced in a direction perpendicular to the substrate, the air exists between the vibrator and the substrate. The air can easily flow out to the back side of the substrate.

According to a third aspect of the present invention, there is provided a substrate having an insulating film on a surface thereof, a supporting portion fixedly provided on the surface of the substrate, a supporting beam having a base end provided on the supporting portion, and A vibrator supported on the tip side of the support beam in a state separated from the surface of the substrate and displaceable with respect to the substrate; excitation means for vibrating the vibrator in a constant excitation direction; and opposing the vibrator Is provided on the surface of the substrate as described above, and when an angular velocity acts while the vibrator is vibrated in the excitation direction by the excitation means, the vibrator moves in a direction orthogonal to the excitation direction in accordance with the angular velocity. A configuration including displacement detection means for detecting displacement is employed.

A feature of the invention according to claim 3 is that a concave portion is provided on the back surface side of the substrate so that a portion of the substrate facing the vibrator is a thin portion made of only an insulating film. Is provided with a communication hole that communicates the front side and the back side of the substrate, and the communication hole allows gas to flow between the front side and the back side of the substrate.

With the above configuration, the excitation means converts an electrical vibration signal output from, for example, an oscillation circuit or the like into mechanical vibration using electrostatic force or the like, and vibrates the vibrator in a constant excitation direction. Things. Further, the displacement detecting means detects that the vibrator is displaced in the direction orthogonal to the excitation direction due to the Coriolis force as a change in capacitance between the vibrator and the displacement detecting means, etc., and based on the detected angular velocity, Is what you want.

Here, when the excitation direction of the vibrator is parallel to the substrate, the displacement detecting means is, for example, a conductor (electrode) provided on the surface of the substrate below the vibrator.
It is. In this case, since the lower side of the portion of the substrate where the displacement detecting means is provided is a thin portion made of only an insulating film, the output from the exciting means is used to vibrate the vibrator in a direction parallel to the substrate. Even if the excitation signal and the like leaked to the substrate side, the excitation signal and the like leaked to the substrate side are not transmitted to the substrate and flow into the displacement detecting means. That is, the excitation signal or the like leaked to the substrate side can be cut off by the thin portion.

On the other hand, when the excitation direction of the vibrator is perpendicular to the substrate, the excitation means is, for example, a conductor (electrode) provided on the surface of the substrate under the vibrator.
In this case, since the lower side of the portion of the substrate where the excitation means is provided is a thin portion made of only the insulating film, the excitation signal output from the excitation means can be cut off by the thin portion.

[0036]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIGS. 1 to 3 show an angular velocity detecting device according to a first embodiment of the present invention.

In FIG. 1, reference numeral 21 denotes an angular velocity detecting device according to the present embodiment. Reference numeral 22 denotes a substrate, and the substrate 22 includes
As shown in FIG. 2, a substrate main body 23 made of, for example, a single-crystal silicon material or a glass material having high resistance, an insulating film 24 made of, for example, silicon oxide (SiO ₂ ) formed on the substrate main body 23, And a silicon film 25 made of a high-resistance silicon material formed on the insulating film 24.

The silicon film 25 is formed on the substrate 22
Of these, a portion provided with each support portion 31, each electrode support portion 35, and the electrode pad 40, which will be described later, and a portion formed only below the vibrator 33 are provided. It has been removed by etching during the manufacturing process. On the silicon film 25, a silicon nitride film 26 made of silicon nitride (SiN) is formed.

Further, as shown in FIG. 2, a silicon film 25 formed on the lower side of the vibrator 33 and a silicon film 25 formed on a portion where each electrode support 35 is provided.
Are formed between them, and the silicon films 25 are separated via the grooves 27. Thereby, the silicon film 25 formed at the lower position of the vibrator 33 can be insulated from the silicon film 25 formed at the portion where the electrode support portions 35 are provided. Therefore, the displacement detection electrodes 37 formed on the silicon film 25 located below the vibrator 33 are completely separated from the electrode support portions 35 to which an excitation signal for vibrating the vibrator is applied. Can be insulated. Similarly, the vibrator 33
The silicon film 25 formed on the lower side of the
Grooves 27 are also formed between the silicon film 25 and the silicon film 25 formed at the portion where the first film 1 is provided, and the respective silicon films 25 are separated via the groove 27.

Reference numeral 28 denotes a concave portion formed on the back surface side of the substrate 22. The concave portion 28 allows the substrate main body 23 located below the portion where the displacement detection electrode 37 is provided to be hydroxylated as an etchant. Tetramethylammonium aqueous solution (T
MAH) or the like. That is, the lower portion of the substrate 22 where the displacement detection electrode 37 is provided is the thin portion 29 made of only the insulating film 24.

Are positioned below the vibrator 33 so as to be opposed to the vibrator 33.
9 shows a large number of communication holes, each communication hole 30
The substrate 22 is formed so as to communicate between the front side and the back side. More specifically, in a portion of the substrate 22 located below the vibrator 33, a concave portion 28 is formed as shown in FIG. 3, and the substrate main body 23 is removed. Therefore, the communication holes 30 are formed to penetrate through the silicon nitride film 26, the silicon film 25, and the insulating film 24 of the substrate 22 so as to communicate between the surface side of the substrate 22 and the inside of the recess 28. Have been.

Each of the communication holes 30 is a hole for allowing air to flow between the front surface and the back surface of the substrate 22 in the direction indicated by arrow B in FIG. The hole diameter is set to a size that allows air to flow and maintains the strength of the substrate 22. Further, since each communication hole 30 is formed in the thin portion 29 of the substrate 22, the distance from the inlet to the outlet of each communication hole 30 is short.

Numerals 31 denote supporting portions fixedly provided on the substrate 22 with the silicon film 25 and the silicon nitride film 26 interposed therebetween. Are arranged so as to oppose each other.

.. Denote four support beams whose base ends are supported by the respective support portions 31 and whose distal ends extend in the direction parallel to the substrate 22 toward the vibrator 33. A vibrator 33 is integrally formed on the distal end side of 32. Each of the support beams 32 is formed in a straight rod shape, and when an excitation signal is applied to each electrode plate 36B of the excitation electrode 36 described later, each of the support beams 32 slightly bends, and
To vibrate.

Reference numeral 33 denotes a vibrator supported on the tip end of each of the support beams 32 in a state separated from the surface of the substrate 22.
The vibrator 33 is formed in a thin plate shape having a length of about 800 μm, a width of about 400 μm, and a thickness of about 5 μm, for example. The distance between the vibrator 33 and the surface of the substrate 22 (the surface of the insulating film 24) is, for example, about 1 μm. The length, width, and thickness of the vibrator 33 and the distance between the vibrator 33 and the surface of the substrate 22 are not limited to the above numerical values.

When an excitation signal is applied to each electrode plate 36B of the excitation electrode 36, the vibrator 33 vibrates in a direction parallel to the substrate 22 (the direction indicated by the arrow X). Further, when an angular velocity about the rotation axis Y acts while the vibrator 33 vibrates in the parallel direction, the vibrator 33 vibrates in a direction perpendicular to the substrate 22 (Z direction indicated by an arrow) due to Coriolis force. .

The vibrator 33 has a large number of etching holes 34, 34,... Each of the etching holes 34 is formed so as to penetrate between the front surface side and the back surface side of the vibrator 33, similarly to the respective etching holes 6 formed in the vibrator 4 according to the related art.

Reference numerals 35, 35 denote electrode support portions fixedly provided on the substrate 22 via the silicon film 25 and the silicon nitride film 26. The electrode support portions 35 are located on both sides of the vibrator 33. It is arranged.

Reference numeral 36 denotes an excitation electrode as excitation means for causing the vibrator 33 to vibrate in a direction parallel to the substrate 22 (X direction indicated by an arrow). The excitation electrode 36 is provided on the vibrator 33 in a comb shape. The electrode plates 36A, 36A,...
The electrode plates 36B, 36B,... Provided on each of the electrode support portions 35 so as to be engaged with each other in a state of being separated from 6A. Then, by applying an excitation signal as a vibration signal from an oscillation circuit (not shown) provided externally to the excitation electrode 36, an electrostatic force is generated between the electrode plates 36A and 36B. The vibrator 33 is vibrated in the X direction indicated by the arrow.

Here, the above-mentioned respective support portions 31, the respective support beams 32, the vibrator 33, the respective electrode support portions 35, and the electrode plates 36A and 36B of the excitation electrode 36 contain impurities such as P, B and Sb. It is formed by etching a doped low-resistance polysilicon.

Reference numeral 37 denotes a displacement detection electrode as a displacement detection means formed on the silicon film 25 on the substrate 22. The displacement detection electrode 37 is located below the vibrator 33 so as to face the vibrator 33. Are located. The displacement detection electrode 37 is formed so as to have conductivity by doping the silicon film 25 with an impurity such as P or Sb. The displacement detection electrode 37 is connected to the vibrator 3
When 3 is displaced in the direction indicated by the arrow Z due to Coriolis force, the amount of displacement is detected as a change in capacitance between the vibrator 33 and the displacement detection electrode 37.

Reference numerals 38, 38 denote excitation electrode pads fixed on the respective electrode support portions 35, and the respective electrode pads 38 are formed of a metal material such as Au, for example, and are provided on the respective electrode support portions 35. Electrically connected to the respective electrode plates 36B. An oscillation circuit or the like (not shown) for applying an excitation signal to each excitation electrode 36 is connected to each electrode pad 38.

Reference numeral 39 denotes an electrode pad fixed on the support portion 31, and reference numeral 40 denotes a detection electrode pad connected to the displacement detection electrode 37 via a lead wire 40A.
9 and 40 are, for example, Au, similarly to the electrode pad 38.
And the like. Further, a detection circuit or the like (not shown) for detecting a change in capacitance between the vibrator 33 and the displacement detection electrode 37 is connected to the electrode pads 39 and 40.

The angular velocity detecting device 21 according to the present embodiment has the above-described configuration. Next, a method of manufacturing the angular velocity detecting device 21 will be described with reference to FIGS.

First, in the substrate processing step shown in FIG. 4, an insulating film 24 is formed by oxidizing the surface of a substrate main body 23 made of a single crystal silicon material. Then, a silicon film 25 made of a silicon material is formed on the insulating film 24, and a substrate 22 of the angular velocity detecting device 21 is formed.

Next, in a displacement detecting electrode forming step shown in FIG. 5, an impurity such as P, B, Sb or the like is diffused at a predetermined position of the silicon film 25 to form a displacement detecting electrode 37. Thereafter, a silicon nitride film 26 made of silicon nitride is formed on the silicon film 25.

Next, in the communication hole forming step shown in FIG. 6, the silicon nitride film 26 is masked with a resist and RIE is performed.
The communication holes 30, 30,... Are formed at predetermined positions of the substrate 22 by (reactive ion etching). At this time, each communication hole 30 penetrates through the silicon nitride film 26, the silicon film 25, and the insulating film 24 from the surface side of the substrate 22, and is formed halfway through the substrate body 23. Further, a part of the silicon film 25 and the silicon nitride film 26 is
To form grooves 27, 27. After that, a silicon oxide film 51 is formed on the inner side surface of each communication hole 30 and each groove 27.

Next, in the sacrificial layer forming step shown in FIG. 7, when the angular velocity detecting device 21 is completed, the vibrator 33 is
In order to form the sacrifice layer 52 (PS) made of phosphorus-doped silicon oxide on the portion of the substrate 22 where the vibrator 33, each support beam 32, and the like are located,
G film) is formed by means such as CVD. Then, a silicon oxide film 53 is formed on the sacrificial layer 52.

Next, in a polysilicon film forming step shown in FIG. 8, a polysilicon film 54 doped with, for example, P, B, Sb or the like is formed on the substrate 22 and the sacrificial layer 52.

Next, in the vibrator forming step shown in FIG. 9, a part of the polysilicon film 54 is removed by dry etching or wet etching, and as shown in FIG. The vibrator 33, the electrode support portions 35, and the electrode plates 36A and 36B are formed. Thereafter, the upper and side surfaces of the polysilicon film 54 and the silicon film 25
The silicon oxide film 55 is formed on the side surface of the substrate and on the back surface of the substrate body 23. Further, a part of the silicon oxide film 55 formed on the polysilicon film 54 forming the electrode support portions 35 and the like is removed, and the electrode pads 38, 38 are formed on the respective electrode support portions 35.
To form Similarly, the electrode pads 39 and 40 are formed at predetermined positions.

Next, in the recess forming step shown in FIG.
After the silicon oxide film mask 56 is formed on the back surface of the substrate body 23, a part of the substrate body 23 is
Etching is performed with an aqueous solution of tetramethylammonium hydroxide (TMAH) or the like. That is, the substrate main body 23 located below the portion where the displacement detection electrode 37 is formed is removed, and etching is performed until the insulating film 24 and the silicon oxide film 51 are exposed when viewed from the back side of the substrate 22. As a result, a concave portion 28 is formed on the back surface side of the substrate 22 and the substrate 2
The thin portion 29 is formed at a lower position where the displacement detection electrode 37 is formed. Then, the sacrificial layer 52 and the silicon oxide films 51, 53, 55, and 56 are removed with a hydrofluoric acid compound, so that the angular velocity detecting device 21 shown in FIG.
Is completed.

Next, the angular velocity detecting device 21 according to the present embodiment
The operation of detecting the angular velocity and the operation of each communication hole 30 formed in the substrate 22 will be described.

When excitation signals of opposite phases are applied to the respective electrode plates 36 B of the respective excitation electrodes 36 from the oscillation circuit via the respective electrode pads 38, the vibrator 33 vibrates in the direction indicated by the arrow X with respect to the substrate 22. . When rotation about the rotation axis Y acts in this state, a Coriolis force corresponding to the angular velocity of the rotation is generated, and the vibrator 33 vibrates (displaces) with respect to the substrate 22 in the direction indicated by the arrow Z. When the vibrator 33 vibrates in the direction indicated by the arrow Z, the separation distance between the vibrator 33 and the displacement detection electrode 37 provided below the vibrator 33 changes. The capacitance with the displacement detection electrode 37 changes. This change in capacitance is detected by the electrode pad 3.
Detected by a detection circuit connected to 9, 40, the angular velocity acting on the angular velocity detecting device 21 is obtained.

Here, as shown in FIG. 3, a large number of communication holes 30 are formed in the substrate 22 below the vibrator 33. Thus, when the vibrator 33 vibrates in the Z direction indicated by the arrow due to Coriolis force, the vibrator 33 and the substrate 2
The air existing in the gap between the substrate 22 and the air flows through each communication hole 30 into the recess 28 located on the back surface side of the substrate 22.

As described above, since each communication hole 30 serves as an escape route for air between the vibrator 33 and the substrate 22, the vibrator 33
The air damping (flow resistance) that occurs when vibrates in the Z direction indicated by the arrow can be significantly reduced. Accordingly, when the vibrator 33 vibrates, the air resistance acting on the vibrator 33 is greatly reduced, so that the vibrator 33 can be vibrated largely in the arrow Z direction. When the vibration in the Z direction indicated by the arrow of the vibrator 33 increases, the vibrator 33
The displacement amount of the gap between the sensor 33 and the displacement detection electrode 37 increases, and the change amount of the capacitance between the vibrator 33 and the displacement detection electrode 37 increases.

Further, each communication hole 30 is formed in the thin portion 29 of the substrate 22, and the distance between the inlet and the outlet of each communication hole 30 is short. Therefore, the air between the vibrator 33 and the substrate 22 easily flows out into the recess 28. As a result, air damping can be further reduced,
The vibrator 33 can be further vibrated in the direction indicated by the arrow Z.

Next, the angular velocity detecting device 21 according to the present embodiment
The point that the leakage of the excitation signal is prevented by the recessed portion 28 and the thin portion 29 provided in the first embodiment will be described.

The vibrator 33 vibrates in the direction indicated by the arrow X when an excitation signal output from the oscillation circuit is applied. That is, the excitation signal output from the oscillation circuit is supplied from the oscillation circuit to each electrode plate 36B of each excitation electrode 36 through each electrode pad 38 and each electrode support 35. At this time,
Since the excitation signal is a high-frequency AC signal, there is a case where the excitation signal slightly leaks to the substrate body 23 side through the silicon nitride film 26 and the insulating film 24 which are insulators.

However, the concave portion 2 is formed on the back side of the substrate 22.
8 is formed, and the substrate 22 located below the displacement detection electrode 37 is a thin portion 29 composed of only the insulating film 24. For this reason, the displacement detection electrode 37 is largely separated from the substrate main body 23, and
Is completely insulated from its surroundings.

As a result, even if the excitation signal leaks to the substrate body 23 side, the leaked excitation signal is transmitted to the displacement detecting electrode 37.
Will not flow into That is, the excitation signal leaked to the substrate main body 23 side is surely cut off by the thin portion 29 composed of only the insulating film 24. Therefore, when detecting the capacitance between the vibrator 33 and the displacement detection electrode 37, noise due to the excitation signal can be reliably removed from the detection signal.

Further, as shown in FIG.
The silicon film 25 provided between the substrate 5 and the substrate 22 and the silicon film 25 on which the displacement detection electrode 37 is formed under the vibrator 33 are separated via the groove 27,
Each silicon film 25 is insulated by the groove 27. Accordingly, even if the excitation signal leaks to the silicon film 25 provided between each electrode support 35 and the substrate 22, the leaked excitation signal is transmitted to the silicon film 25 on which the displacement detection electrode 37 is formed, The flow into the displacement detection electrode 37 can be reliably prevented.

Thus, according to the present embodiment, a large number of communication holes 30 are provided in the substrate 22 at positions facing the vibrator 33.
The vibrator 33 is provided by Coriolis force.
Vibrates in the Z direction indicated by the arrow when the vibrator 33 and the substrate 22
Can be reduced, and the vibrator 33 can be largely vibrated in the arrow Z direction. Therefore, when the angular velocity acts, the vibrator 33
It is possible to increase the change in capacitance between the electrode and the displacement detection electrode 37, and to improve the angular velocity detection sensitivity.

Furthermore, since each communication hole 30 is formed in the thin portion 29 and the length of each communication hole 30 is shortened, the flow of air can be improved. Thereby, the air damping can be further reduced, and the vibration of the vibrator 33 can be further increased. Therefore, the angular velocity detection sensitivity can be further improved.

Further, since a large number of communication holes 30 are provided in the substrate 22, the following effects can be obtained when the angular velocity detecting device 21 is manufactured.

That is, in the vibrator forming step shown in FIG. 9, the vibrator 33 and the electrode support 35
When forming the recesses 28 in the substrate 22 in the recess forming step shown in FIG.
After performing the wet etching, the etching solution is washed with pure water and dried. At this time,
Pure water may remain, and the vibrator 33 may adhere to the surface of the substrate 22 due to the surface tension of the remaining pure water.

In such a case, the gas is sent between the substrate 22 and the vibrator 33 from the back surface side of the substrate 22 through each communication hole 30, so that the vibrator 33 is separated from the surface of the substrate 22. be able to. Therefore, the yield of the angular velocity detecting device 21 can be improved.

Next, an angular velocity detecting device according to a second embodiment of the present invention will be described with reference to FIG. In this embodiment, the same components as those of the first embodiment described above are denoted by the same reference numerals, and description thereof will be omitted.

That is, the angular velocity detecting device 61 according to this embodiment
Is the configuration of the substrate 22, the recess 2 formed in the substrate 22.
8, the thin portion 29 and the communication hole 30 are the same as those of the angular velocity detecting device 21 according to the first embodiment. Also, the substrate 2
The shapes of the support, the support beam, the vibrator 33, and the electrode support 35 provided on the upper surface 2 are the same as those of the angular velocity detecting device 21 according to the first embodiment.

However, in the angular velocity detecting device 61 according to the present embodiment, the electrode located on the lower side of the vibrator 33 and formed on the surface of the substrate 22 becomes the excitation electrode 62, and the vibrator 33 and the electrode support portions 35 The electrodes formed between them are the displacement detection electrodes 63, 63.

The angular velocity detecting device 61 according to the present embodiment has the above-described configuration. Next, the basic operation of the angular velocity detecting device 61 and the operation of the communication hole 30 will be described.

That is, by applying an excitation signal to the excitation electrode 62, the vibrator 33 vibrates in a direction perpendicular to the substrate 22 (Z direction indicated by an arrow). When the vibrator 33 vibrates in the direction indicated by the arrow Z and an angular velocity around the rotation axis similar to the rotation axis Y shown in FIG. 1 acts, the vibrator 33 is parallel to the substrate 22 by Coriolis force. Vibrates in the direction (X direction indicated by arrow). As a result, the electrode plate 63A provided on the vibrator 33 and the electrode plate 6 provided on the electrode support 35 are provided.
Since the capacitance between the capacitor 3B and the capacitor 3B changes, the angular velocity is determined by detecting the change in the capacitance.

Here, a large number of communication holes 30 are formed in the substrate 22 at positions below the vibrator 33. Thereby, when the vibrator 33 vibrates in the Z direction indicated by the arrow by the excitation electrode 62, air existing in the gap between the vibrator 33 and the substrate 22 passes through each communication hole 30 and passes through the back surface of the substrate 22. It flows out into the recess 28 located on the side.

As described above, since each communication hole 30 serves as an escape route for air between the vibrator 33 and the substrate 22, the vibrator 33
The air damping that occurs when vibrates in the Z direction indicated by the arrow can be significantly reduced. Thereby, the vibrator 33 can be largely vibrated in the arrow Z direction by reducing the air resistance. When the vibration of the vibrator 33 in the arrow Z direction increases, the vibrator 33 vibrates largely in the arrow X direction when an angular velocity acts. Accordingly, the displacement of the separation distance between the electrode plate 63A provided on the vibrator 33 and the electrode plate 63B provided on the electrode support portion 35 increases, and the capacitance of the electrode plates 63A and 63B decreases. The change amount becomes large. Therefore, the angular velocity detection sensitivity can be improved.

Next, the angular velocity detecting device 61 according to this embodiment
The point that the leakage of the excitation signal is prevented by the recessed portion 28 and the thin portion 29 provided in the first embodiment will be described.

An excitation signal, which is a high-frequency AC signal, is applied to the excitation electrode 62 in order to cause the vibrator 33 to vibrate. Here, the recessed portion 28 is located below the excitation electrode 62.
Is formed, and the substrate 2 located at a lower position of the excitation electrode 62 is formed.
Reference numeral 2 denotes a thin portion 29 composed of only the insulating film 24.
Thereby, even if the excitation signal is applied to the excitation electrode 62,
This excitation signal is cut off by the thin portion 29 and does not leak outside the excitation electrode 62. Therefore, it is possible to reliably prevent the excitation signal from leaking toward the support portion and the electrode support portion 35, and to ensure that the detection signal (capacitance) output from the displacement detection electrode 63 includes noise due to the excitation signal. Can be prevented.

Thus, with the angular velocity detecting device 61 according to the present embodiment, substantially the same effects as those of the angular velocity detecting device 21 according to the first embodiment can be obtained.

Next, an angular velocity detecting device according to a third embodiment of the present invention will be described with reference to FIG. The feature of this embodiment is that the recess is not provided on the back surface side of the substrate as in the first embodiment, thereby simplifying the manufacturing process and improving the strength of the substrate. In this embodiment, the same components as those of the first embodiment described above are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 12, reference numeral 71 denotes an angular velocity detecting device according to the present embodiment. Reference numeral 72 denotes a substrate.
The substrate body 7 made of a high-resistance single-crystal silicon material, like the angular velocity detecting device 21 according to the first embodiment.
3, an insulating film 74 made of silicon oxide, and a silicon film 75 made of a high-resistance single crystal silicon material. A silicon nitride film 76 is formed on the silicon film 75. Further, the silicon film 7
5, grooves 77, 77 are formed similarly to the angular velocity detecting device 21 according to the first embodiment.

.., 78 represent a large number of communication holes provided in the substrate 72 under the vibrator 33 so as to be opposed to the vibrator 33. It is formed so as to communicate between the front side and the back side.
More specifically, each communication hole 78 is provided with the substrate 72.
By penetrating through the silicon nitride film 76, the silicon film 75, the insulating film 74, and the substrate main body 73, the substrate 72 is formed so as to communicate between the front side and the back side.

Each communication hole 78 is a hole for allowing air to flow in the direction of arrow D in FIG. 11 between the front side and the back side of the substrate 72. The hole diameter is
The size is set to allow air to flow and to maintain the strength of the substrate 72. Further, the angular velocity detecting device 71 according to the present embodiment differs from the angular velocity detecting device 21 according to the first embodiment described above in that no concave portion is provided on the back surface side of the substrate 72. Accordingly, the strength of the substrate 72 of the angular velocity detecting device 71 according to the present embodiment is higher than that of the angular velocity detecting device 21 according to the first embodiment. This allows
The hole diameter of each communication hole 78 formed in the substrate 72 is larger than the hole diameter of each communication hole 30 of the angular velocity detecting device 21 according to the first embodiment.

Next, the angular velocity detecting device 71 according to the present embodiment is described.
Will be described with reference to FIGS.

First, in the substrate processing step shown in FIG. 13, an insulating film 74 is formed by oxidizing the surface of a substrate body 73 made of a single crystal silicon material. A silicon film 75 made of a silicon material is formed on the insulating film 74.
Is formed, and the substrate 72 of the angular velocity detecting device 71 is formed.

Next, in the displacement detection electrode forming step shown in FIG. 14, for example, P, B, Sb
And the like are diffused to form the displacement detection electrode 37.
Thereafter, a silicon nitride film 76 is formed on the silicon film 75.

Next, in the communication hole forming step shown in FIG.
By masking the silicon nitride film 76 with a resist, RI
Communication holes 78, 78,... Are formed at predetermined positions on the substrate 72 by E (reactive ion etching). At this time, the communication holes 78 are formed so as to penetrate the silicon nitride film 76, the silicon film 75, the insulating film 74, and the substrate body 73 from the surface side of the substrate 22. Further, a part of the silicon film 75 and the silicon nitride film 76 is
E is removed to form grooves 77, 77. Then, a silicon oxide film 81 is formed on the inner side surface of each communication hole 78 and each groove 77.
To form

Next, in the sacrifice layer forming step shown in FIG.
When the angular velocity detecting device 71 is completed, the vibrator 33 is
The substrate 72 is formed to be spaced from the surface of the substrate 2.
A sacrifice layer 82 is formed on a portion where the vibrator 33, each support beam 32, and the like are located.

Next, in the polysilicon film forming step shown in FIG. 17, for example, P, B, Sb is formed on the substrate 72 and the sacrificial layer 82.
Then, a polysilicon film 83 doped with, for example, is formed.

Next, in the vibrator forming step shown in FIG.
A portion of the polysilicon film 83 is removed by dry etching or wet etching to form the vibrator 33, the electrode support 35, and the like. Then, the polysilicon film 83
The electrode pads 38, 38 and the like are formed thereon. Further, by removing the sacrificial layer 82 and the silicon oxide film 81 with a hydrofluoric acid compound, the angular velocity detecting device 7 shown in FIG.
1 is completed.

The angular velocity detecting device 71 according to the present embodiment has the above-described configuration, and the operation of detecting the angular velocity is the same as that of the angular velocity detecting device 21 according to the first embodiment.

However, by providing the communication holes 78 in the substrate 72, it is possible to reduce the air damping generated between the oscillator 33 and the substrate 72 when the oscillator 33 vibrates in the arrow Z direction. Accordingly, the vibrator 33 can be largely vibrated in the direction indicated by the arrow Z. Therefore, the vibrator 33
It is possible to increase the change in the capacitance between the electrode and the displacement detection electrode 37, thereby improving the angular velocity detection sensitivity.

In this embodiment, unlike the angular velocity detector 21 of the first embodiment, no recess is provided on the back surface of the substrate 72, and each communication hole 78 is formed from the front surface of the substrate 72 to the back surface. Since the through holes are formed, the manufacturing process can be simplified and the strength of the substrate 72 can be improved.

In each of the above embodiments, the excitation electrode 36
It has been described that the (displacement detection electrode 63) is constituted by the comb-shaped electrode plates 36A (63A) provided on both sides of the vibrator 33 and the comb-shaped electrode plates 36B (63B) provided on the electrode support 35. However, the present invention is not limited to this, and the electrode plates 36A (63A), 36B (63B)
, The side surface of the vibrator 33 and the side surface of the electrode support portion 35 may be formed in a planar shape.

In each of the above embodiments, the substrate 22 (7
2) A pair of support portions 31 are provided on the upper surface, and a total of four support beams 3 are provided.
Although the configuration is such that the vibrator 33 is supported by 2, the present invention is not limited to this. For example, a single support is provided on the substrate, and one or two support beams are provided on the support. The present invention can also be applied to a so-called cantilevered angular velocity detecting device that supports a vibrator by using it.

[0104]

As described above in detail, according to the first aspect of the present invention, a communication hole communicating between the front side and the back side of the substrate is formed at the position of the substrate facing the vibrator. Provided,
Since the communication hole allows the gas to flow between the front surface side and the back surface side of the substrate, when the vibrator vibrates in a direction perpendicular to the substrate, the gas exists between the vibrator and the substrate. Gas can escape to the back side of the substrate. Thereby, damping (flow resistance) of gas between the vibrator and the substrate can be reduced, and the vibrator can be vibrated largely in the direction perpendicular to the substrate without resistance.
Therefore, the angular velocity detection sensitivity can be improved.

According to the second aspect of the present invention, a concave portion is provided on the back surface side of the substrate so that a portion of the substrate facing the vibrator is a thin portion, and the thin portion is provided on the front surface side of the substrate. A communication hole communicating with the back surface side is provided, and since the communication hole allows the gas to flow between the front surface side and the back surface side of the substrate, the distance from the inlet to the outlet of the communication hole is reduced. It is possible to shorten the length of the air passage, and it is possible to shorten the air passage from the front surface side of the substrate to the back surface side (inside the concave portion). This facilitates the flow of air through the communication hole, so that the damping of gas generated when the vibrator vibrates in the direction perpendicular to the substrate can be further reduced. Therefore, the vibrator can be vibrated much more without any resistance in the direction perpendicular to the substrate, and the detection sensitivity of the angular velocity can be further improved.

According to the third aspect of the present invention, on the rear surface of the substrate, the portion of the substrate facing the vibrator is a thin portion made of only an insulating film formed on the surface of the substrate. The concave portion is provided, and the thin portion is provided with a communication hole that communicates between the front side and the back side of the substrate and allows a gas to flow between the front side and the back side of the substrate. It is possible to prevent an excitation signal or the like applied to the excitation means for causing the element to vibrate in the excitation direction from leaking and acting as noise on the displacement detection means. Therefore, noise when detecting a change in capacitance between the vibrator and the displacement detecting means can be significantly reduced, and the detection sensitivity of the angular velocity can be improved.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an angular velocity detecting device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of the angular velocity detecting device in FIG. 1 as viewed from the direction of arrows II-II.

FIG. 3 is an enlarged sectional view showing a main part of the angular velocity detecting device in FIG. 2;

FIG. 4 is a cross-sectional view showing a substrate processing step in the method of manufacturing the angular velocity detecting device applied to the first embodiment.

FIG. 5 is a cross-sectional view showing a state where a displacement detection electrode is formed on a substrate in a displacement detection electrode formation step.

FIG. 6 is a cross-sectional view showing a state where communication holes and the like are formed in the substrate in the communication hole forming step.

FIG. 7 is a cross-sectional view showing a state in which a sacrifice layer is formed on a substrate in a sacrifice layer formation step.

FIG. 8 is a sectional view showing a state in which a polysilicon film is formed in a polysilicon film forming step.

FIG. 9 is a cross-sectional view showing a state in which a vibrator, an electrode support, and the like are formed on a substrate in a vibrator forming step of the first embodiment.

FIG. 10 is a cross-sectional view showing a state where a recess is formed in the substrate in the recess forming step of the first embodiment.

FIG. 11 is a sectional view showing an angular velocity detecting device according to a second embodiment of the present invention at the same position as in FIG. 2;

FIG. 12 is a sectional view showing an angular velocity detecting device according to a third embodiment of the present invention at the same position as in FIG. 2;

FIG. 13 is a cross-sectional view showing a substrate processing step in a method of manufacturing an angular velocity detection device applied to the third embodiment.

FIG. 14 is a cross-sectional view showing a state where a displacement detection electrode is formed on a substrate in a displacement detection electrode formation step.

FIG. 15 is a cross-sectional view showing a state where communication holes and the like are formed in the substrate in the communication hole forming step.

FIG. 16 is a cross-sectional view showing a state in which a sacrifice layer is formed on a substrate in a sacrifice layer formation step.

FIG. 17 is a cross-sectional view showing a state where a polysilicon film is formed in a polysilicon film forming step.

FIG. 18 is a cross-sectional view showing a state in which a vibrator, an electrode support, and the like are formed on a substrate in a vibrator forming step.

FIG. 19 is a cross-sectional view showing an angular velocity detecting device according to a conventional technique.

20 is a cross-sectional view of the angular velocity detection device in FIG. 19 as viewed from the direction of arrows XX-XX.

[Explanation of symbols]

 21, 61, 71 Angular velocity detecting device 22, 72 Substrate 23, 73 Substrate main body 24, 74 Insulating film 28 Depressed portion 29 Thin portion 30, 78 Communication hole 31 Support portion 32 Support beam 33 Vibrator 36 Excitation electrode (excitation means) 37 Displacement detection electrode (displacement detection means)

Claims (3)

[Claims] A supporting member fixedly provided on a surface of the substrate; a supporting beam having a base end provided on the supporting portion; and a supporting beam separated from the surface of the substrate. A vibrator supported on the tip side and displaceable with respect to the substrate, excitation means for vibrating the vibrator in a constant excitation direction, and an angular velocity in a state where the vibrator is vibrated in the excitation direction by the excitation means. A displacement detecting means for detecting when the vibrator is displaced in a direction orthogonal to the excitation direction in response to the angular velocity, wherein the substrate has a position facing the vibrator. Characterized in that a communication hole communicating between the front side and the back side of the substrate is provided on the substrate, and a gas is circulated between the front side and the back side of the substrate by the communication hole. apparatus. 2. A substrate, a support portion fixedly provided on a surface of the substrate, a support beam having a base end side provided on the support portion, and a support beam separated from the surface of the substrate. A vibrator supported on the tip side and displaceable with respect to the substrate, excitation means for vibrating the vibrator in a constant excitation direction, and an angular velocity in a state where the vibrator is vibrated in the excitation direction by the excitation means. A displacement detecting means for detecting when the vibrator is displaced in a direction orthogonal to an excitation direction in response to the angular velocity, wherein the substrate has a portion opposed to the vibrator. A concave portion is provided on the back surface side of the substrate so as to be a thin portion, and a communication hole communicating the front surface side and the back surface side of the substrate is provided in the thin portion,
An angular velocity detecting device, wherein a gas is circulated between the front surface side and the back surface side of the substrate by the communication hole. 3. A substrate having an insulating film on a surface thereof, a supporting portion fixedly provided on the surface of the substrate, a supporting beam provided on the supporting portion on a base end side, and separated from the surface of the substrate. A vibrator supported on the distal end side of the support beam in a state and displaceable with respect to the substrate; excitation means for vibrating the vibrator in a constant excitation direction; and a surface of the substrate facing the vibrator. When an angular velocity is applied in a state where the vibrator is vibrated in the excitation direction by the excitation means, it is detected that the vibrator is displaced in a direction orthogonal to the excitation direction in accordance with the angular velocity. In the angular velocity detecting device comprising a displacement detecting means, the substrate is provided with a concave portion on the back surface side of the substrate so that a portion facing the vibrator is a thin portion made of only an insulating film, and the thin portion has Communicates the front and back sides of the substrate The communication hole is provided, an angular velocity detecting device is characterized in that a structure for circulating the gas between the front and rear sides of the substrate by the communicating hole.