JP3262082B2 - Vibrating angular velocity detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an angular velocity detector which is formed by fine processing of a semiconductor and detects an angular velocity in relation to a Coriolis force generated in a vibrator.

[0002]

2. Description of the Related Art Conventionally, as this kind of angular velocity detector,
The detectors described in JP-A-7-43166 and JP-A-7-174569 are known. In this technique, a vibrating body is supported by a beam extending in one axial direction, thereby enabling the vibrating body to vibrate in a direction perpendicular to the axis of the beam. Then, the vibrator is oscillated in a direction perpendicular to the beam axis on a plane parallel to the substrate surface, that is, in the direction of the excitation axis, and in a direction perpendicular to the substrate, that is,
The angular velocity around the beam axis is detected by detecting a value related to the Coriolis force generated in the detection axis direction. When supporting the vibrator with a uniaxial beam,
Since the beam can oscillate in both directions of the excitation axis and the detection axis, an excitation component easily appears in the direction of the detection axis, causing a detection error of angular velocity. Further, since the detection axis is in the direction perpendicular to the substrate, it is necessary to dispose the detection electrodes along the direction perpendicular to the substrate. That is, it is necessary to provide a substrate, an electrode, a vibrator, and an electrode to form a multilayer by providing a gap, which complicates a processing step.

[0003] The inventors of the present invention have proposed in Japanese Patent Application No. 8-334337.
As described above, the inventors invented an angular velocity detector in which the excitation axis and the detection axis exist on the substrate surface. The structure is shown in FIGS.
Is shown in The paper surface is the substrate surface, and the z-axis is taken in a direction perpendicular to the substrate surface, and the x-axis and y-axis are taken on the substrate surface as shown in the figure.
This detector detects the angular velocity ω around the z axis, the x axis is the excitation axis, and the y axis is the detection axis. Beams 21, 22, 23, and 24 are provided on both sides of the mass section 10 so as to extend in the x-axis direction. The other ends of these beams 21, 22, 23, 24 are connected to beams 31, 32, 33, 34 extending in the y-axis direction. The other ends of the beams 31 and 33 are connected to a frame 41 extending in the x-axis direction.
Is connected to a frame 42 extending in the x-axis direction. Further, in order to support these frames 41, 42, beams 35, 36, 3 fixed at one end to a substrate are provided.
7, 38 are provided. With such a structure, the beams 31, 32, 33, 34, 35, 36, 37, 38
Is capable of bending in the x-axis direction, so that the floating body composed of the mass portion 10 and the beams 21, 22, 23, and 24 easily vibrates in the x-axis direction. However, beams 31, 32, 33,
Since 34, 35, 36, 37, and 38 extend in the y-axis direction, the rigidity in the y-axis direction is large, and the vibration in the y-axis direction is greatly suppressed. On the other hand, beams 21, 22, 23, 24
Is very easily bent in the y-axis direction because it extends in the x-axis direction. Therefore, when a Coriolis force that vibrates in the y-axis direction acts on the mass section 10, the mass section 10 easily vibrates in the y-axis direction.

In the excitation in the x-axis direction, an AC voltage is applied to a fixed comb electrode 74 which is an excitation electrode to generate an AC electrostatic force between the fixed comb electrode 74 and the movable comb electrode 73 engaged with the fixed comb electrode 74. This is done by letting At this time, the displacement of the excitation is detected by detecting the capacitance between the fixed comb electrode 76 and the movable comb electrode 75 which are the excitation detection electrodes, and the feedback control is performed so that the amplitude becomes constant. . The vibration component in the y-axis direction is the capacitance between the movable comb electrode 81 and the fixed comb electrodes 82 and 83 constituting the detection electrode, and the movable comb electrode 8
4 and a change in capacitance between the fixed comb electrodes 85 and 86.

[0005] With such a structure, the excitation component in the x-axis direction does not leak in the y-axis direction, and the response can be made sensitive to Coriolis force acting on the mass section 10 in the y-axis direction.
The present inventors have proposed an angular velocity detector having such a high detection accuracy, in which the excitation axis and the detection axis exist on the substrate surface.

[0006]

In the angular velocity detector described above, the fixed comb electrodes 82, 83, 85, and 8 serving as detection electrodes are provided.
6 needs to be wired. However, the movable electrode 7
In order to increase the rigidity in the y-axis direction so that the members 3 and 75 are not displaced in the y-axis direction, the frames 41 and 42 are arranged in the x-axis direction. For this reason, these frames 41 and 42 become obstacles, and wiring cannot be formed on a substrate by vapor deposition or a wiring layer. Therefore, it is necessary to bond the lead wires 101, 102, 103, 104 to the pads 111, 112, 113, 114 so as to straddle the frames 41, 42. That is, there is a problem that the manufacturing efficiency is poor due to the presence of an advanced bonding operation.

In order to improve the sensitivity of the angular velocity detector, it is necessary to increase the Q value of the vibration of the mass section 10. For this purpose, these functional element portions are preferably placed in a vacuum environment. As shown in FIGS. 19 and 20, the silicon substrate 1 is covered from above with a cap 91 made of a conductive material, and the internal space is evacuated. However, lead wire 10
It is necessary to take care that 1, 102, 103, and 104 do not contact the cap 91, and there is a problem that workability in the packaging process is not good. Further, when the space wiring is provided, an inertial force acts on the lead wire itself, and the lead wire may be disconnected, which causes a problem in reliability.

[0008] To solve the above problem, the frame 4
It is conceivable that the movable comb electrodes 73 and 75 and the mass portion 10 are supported only by the folded beam having one end fixed to the substrate 1 without the reference numerals 1 and 42. However, when it is considered that the movable comb electrodes 73 and 75 are equivalently supported on the substrate 1 by the spring in the x-axis direction and the y-axis direction by this beam structure, the spring constant in the x-axis direction is small. You can,
There is a problem that the spring constant in the y-axis direction is also reduced. Further, the distance between one tooth of the movable comb electrode 73 and the teeth of the fixed comb electrode 74 located on both sides of the movable comb electrode 73 is not completely equal due to the limitation of manufacturing accuracy. As a result, when exciting in the x-axis direction, a force acts on the movable comb electrode 73 also in the y-axis direction and vibrates in the y-axis direction. When it is easy to vibrate in the y-axis direction, the beams 31, 32, 35,
36 is deformed, and the movable comb electrode 73 makes an elliptical motion on the substrate surface. In an extreme case, the movable comb electrode 73
And the fixed comb electrode 74 come into contact with each other.

In the angular velocity detector having the above-described structure, the movable comb electrodes 73 and 75 need to have a beam structure which can be easily displaced in the x-axis direction but not easily displaced in the y-axis direction. . Therefore, an object of the present invention is to obtain a beam structure that can be easily displaced in the direction of the excitation axis and not easily displaced in the direction of the detection axis in the angular velocity detector.
It is to improve the detection accuracy. Another object of the present invention is to improve the quality of the product and to facilitate the production by realizing the wiring for the detection electrode by vapor deposition or a wiring layer on the substrate. Still another object is to facilitate the manufacture of the angular velocity detector having the cap by depositing or laminating the wiring for the detection electrode.

[0010]

According to a first aspect of the present invention, there is provided an image forming apparatus, comprising: an x-axis;
When the y-axis is taken perpendicular to the axis and the z-axis is taken perpendicular to the substrate surface, a mass portion oscillated with respect to the substrate is excited in the x-axis direction, and the angular velocity around the z-axis is taken as the y-axis. A first supporting beam extending in the x-axis direction from both sides of a mass portion in a vibrating angular velocity detector that detects an angular velocity by detecting a physical quantity related to a Coriolis force generated in the first direction; A free beam extending from the other end of the free beam and extending in the y-axis direction, and an arbitrary one of the free beams are provided at a predetermined interval in parallel with the free beam, and an end closer to the first support beam is provided. At least two fixed beams fixed to the substrate, and a second support beam comprising a link connecting the other end of the fixed beam and one end of the free beam and extending in the x-axis direction. I do.

According to a second aspect of the present invention, in the first aspect of the present invention, the free beam extending from the other end of the first support beam and extending in the y-axis direction is provided at a predetermined position. It is characterized in that it is a set of two or more free beams parallel to each other at intervals. In this case, the other end of the first support beam does not mean “end point” but means “near the end” in order to provide a predetermined interval between two or more sets of free beams.

[0012]

According to the first aspect of the present invention, each free beam is supported by at least two fixed beams parallel thereto. Therefore, since the free beam and the fixed beam are arranged at right angles (parallel to the y-axis) in the x-axis direction, which is the excitation direction, they can be easily bent in the excitation direction. However, since the free beam and the fixed beam extend in the y-axis direction, bending in the y-axis direction is suppressed. Also, since the first support beam extends in the x-axis direction, it can be easily bent in the y-axis direction, the mass in the y-axis direction, which is the detection axis, can be displaced, and the physical quantity related to the Coriolis force is detected. be able to. In this way, the free beam can be easily displaced only in the x-axis direction and the displacement in the y-axis direction can be extremely difficult, so that the detection accuracy of the angular velocity detector can be improved. The link only connects one end of the at least two fixed beams and one end of the free beam, and is not arranged parallel to the entire length of the first support beam. As a result, the wiring for the detection electrode for detecting the displacement of the mass portion in the y-axis direction can be formed by vapor deposition or lamination on the substrate, and the manufacturing process is simplified. further,
Since a detector using a cap for vacuum sealing does not require spatial wiring, the reliability of the product is improved and the manufacturing process is simplified.

Further, in the configuration of the present invention, each set of two or more free beams extending parallel to each other at a predetermined interval is supported by at least two fixed beams parallel to these. Have been. Therefore, similarly to the first aspect, the free beam can be easily displaced only in the x-axis direction and the displacement in the y-axis direction can be made extremely difficult, so that the detection accuracy of the angular velocity detector is improved. Can be done. Furthermore, by providing a prismatic structure in the vicinity of the end of the first support beam, a set of two or more free beams, and a link, it is possible to significantly suppress the rotation of the mass section around the center of gravity. Also, since the link is not arranged in parallel over the entire length of the first support beam, the wiring for the detection electrode for detecting the displacement of the mass portion in the y-axis direction should be formed by vapor deposition or lamination on the substrate. Since the manufacturing process is simplified, and a detector using a cap for vacuum sealing does not require a space wiring, the reliability of the product is improved and the manufacturing process is simplified.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on specific embodiments. FIG. 1 is a plan view of an angular velocity detector 100 according to a first specific example of the present invention, and FIG. 2 is a sectional view thereof. In FIG. 1, the paper surface is the substrate surface,
Z-axis in the direction perpendicular to the substrate surface, x on the substrate surface as shown
Axis, y axis. The detector 100 detects an angular velocity ω around the z axis, the x axis is the excitation axis, and the y axis is the detection axis. On the side 10a in the + x-axis direction of the mass portion 10, beams 21 and 22 constituting the first support beam are extended in the + x-axis direction. On the side 10b in the -x-axis direction of the mass portion 10,
Beams 23 and 24 constituting the first support beam extend in the −x-axis direction.

Next, the second support beam will be described.
The second support beam is composed of a free beam, a fixed beam, and a link connecting them. The other ends 21a and 22a of the beams 21 and 22 are free beams 3 extending in the y-axis direction.
1, 32. Similarly, beams 23, 24
Are connected to free beams 33 and 34 extending in the y-axis direction. One ends 31a, 32a of the free beams 31, 32 are fixed to links 41, 42, respectively, at the center thereof, and one ends 33a, 34a of the free beams 33, 34 are respectively connected to the links 43, 44, at the center thereof. It is fixed at.

Fixed beams 511 and 512 extend from both ends 41a and 41b of the link 41 in the + y-axis direction, respectively.
One end of 2 is fixed to the silicon substrate 1 by anchor portions 611 and 612. Similarly, both ends 42 of the link 42
a, 42b, respectively, fixed beams 521, 52
2 extend in the −y-axis direction, and one ends of the fixed beams 521 and 522 are fixed to the silicon substrate 1 by anchor portions 621 and 622. Similarly, from both ends 43a and 43b of the link 43, fixed beams 531 and 532 extend in the + y-axis direction, respectively, and one ends of the fixed beams 531 and 532 are connected to the anchor portion 6 respectively.
It is fixed to the silicon substrate 1 by 31 and 632.
Similarly, from both ends 44a and 44b of the link 44, fixed beams 541 and 542 are respectively extended in the −y-axis direction, and one ends of the fixed beams 541 and 542 are formed by anchor portions 641 and 642 by silicon. It is fixed to the substrate 1.

Also, the ends 21a, 22 of the beams 21, 22
a is connected by a link 71 extending in the y-axis direction, and ends 23a and 24a of the beams 23 and 24 are connected by a link 72 extending in the y-axis direction. The link 71 has teeth extending in the x-axis direction and a movable comb electrode 73 formed along the y-axis direction. A fixed comb electrode 74 is fixed to the silicon substrate 1 so as to mesh with the movable comb electrode 73. The movable comb electrode 73 and the fixed comb electrode 74 constitute an excitation electrode. Similarly, the link 72 has -x
A movable comb electrode 75 extends in the axial direction and extends in the y-axis direction. A fixed comb electrode 76 is fixed to the silicon substrate 1 so as to mesh with the movable comb electrode 75. The movable comb electrode 75 and the fixed comb electrode 76 constitute an excitation detection electrode. Then, the fixed comb electrode 74
Is connected to the wiring layer 77, and the fixed comb-tooth electrode 76 is connected to the wiring layer 7.
8 are connected.

A movable comb electrode 81 is provided at the end 10c of the mass section 10 on the + y axis side along the + x axis direction and extends along the + y axis direction. Fixed comb electrodes 82 and 83 are fixed to the silicon substrate 1 so as to mesh with the teeth on both sides of the silicon substrate 1. Similarly,-of the mass portion 10
At the end 10d on the y-axis side, movable comb-teeth electrodes 84 are disposed along the -x-axis direction with teeth extending in the ± x-axis direction, and are engaged with teeth on both sides of the movable comb-teeth electrode 84. The fixed comb electrodes 85 and 86 are fixed to the silicon substrate 1. The movable comb electrode 81 and the fixed comb electrodes 82 and 83 and the movable comb electrode 84 and the fixed comb electrodes 85 and 86 constitute an angular velocity detection electrode. In addition, fixed comb electrodes 82 and 83
Are connected to wiring layers 87 and 88, respectively, and fixed comb electrodes 85 and 86 are connected to wiring layers 89 and 90, respectively.

The substrate 1 having the above structure is covered with a square cap 91. In the above-described structure, the mass portion 10 is formed in a lattice shape with the links 41, 42, 43,
44, 71, and 72 are formed in a ladder shape to facilitate etching of the lower layer. Mass part 10, beam 2
1, 22, 23, 24, free beams 31, 32, 33,
34, links 41, 42, 43, 44, 71, 72, movable comb electrodes 73, 75, 81, 84, fixed beam 51
1, 512, 521, 522, 531, 532, 54
1,542 voids exist between the substrate 1 (referred to as "floating unit A ₁ 'the portion constituted with these), floating unit A ₁ is supported by levitation with respect to the substrate 1. The floating portions formed continuously with the mass portion 10 are anchor portions 611 and 61.
2,621,622,631,632,641,642
Is fixed to the substrate 1 only, and is floated and supported with respect to the substrate 1. Also, the movable comb electrode 73 and the fixed comb electrode 74
Is shown in FIG. The relationship between the other movable comb electrodes 75 and the fixed comb electrodes 76 is the same as that shown in FIG. Similarly, the relationship between the movable comb electrode 81 and the fixed comb electrodes 82 and 83 and the relationship between the movable comb electrode 84 and the fixed comb electrodes 85 and 86 that constitute the angular velocity detecting electrode is almost the same as the relationship shown in FIG. is there.

The angular velocity detector 100 having the above structure is manufactured as follows. This manufacturing method is manufactured by a semiconductor fine processing technology and is a known technology. As shown in FIG. 4A, a silicon oxide film 2 is formed on a silicon substrate 1, and a silicon layer 3 having conductivity by adding an impurity is formed on the silicon oxide film 2. Next, aluminum is vapor-deposited on the silicon layer 3 and patterned into a predetermined shape by photolithography as shown in FIG. 4B to form wiring layers 77, 78, 87 and 89 (FIG. 1). , 88, 90 (FIGS. 1, 4).

Next, in order to form a floating portion A _1, and uniformly applying a photoresist on the surface of the silicon layer 3 is patterned, as shown in FIG. 4 (c), a mask pattern 7 I do. Next, using the mask pattern 7 as a mask, the silicon layer 3 is etched by wet etching to pattern the silicon layer 3 into a desired shape.
Next, using the sacrificial layer etching technique, to remove the silicon oxide film 2 at the bottom of the floating unit A _1. In this sacrificial layer etching, the silicon oxide film 2 is removed by immersing the substrate 1 in a hydrofluoric acid solution. At this time, the anchor portions 611, 61
2, 621, 622, 632, 642 (above, see FIG. 1), 631, 641 (FIGS. 1 and 4 (e)) and the wiring layers 77, 78, 87, 88, 89, 90 have large areas. silicon oxide film 2 below is not removed, only the silicon oxide film 2 under the flying portion a ₁ and the fixed comb electrodes 74,76,82,83,85,86 are removed. For this removal of the lower silicon oxide film 2 of the silicon layer 3, as is easy penetration of the hydrofluoric acid solution, floating unit A ₁ larger mass portion 10 of the area in a grid pattern having a plurality of windows The links 41, 42, 43, 44, 71, 72 are formed in a ladder shape having a number of windows. Since the mass 10 requires a predetermined inertial mass, the total area of the opening cannot be made too large. Therefore, the thickness of the silicon film 3 of the mass portion 10 and the length of one side of each window are made substantially equal.

The material of the substrate 1 is not particularly limited. In addition to silicon, other semiconductors, ceramics, glass, and the like can also be used. As the etching sacrificial layer, a silicon nitride film, alumina, or the like can be used in addition to the silicon oxide film. Further, mainly, the functional layer for forming the floating portion A1 _only needs to have elasticity, and it may be a single crystal,
In addition to polycrystalline silicon, metals such as nickel and other elastic materials can be used. When silicon is used, the movable comb electrodes 73, 75, and 8 are formed by the silicon film 3.
1, 84, fixed comb-teeth electrodes 74, 76, 82, 83, 8
From the viewpoint of forming 5, 86, it is desirable that the electric conductivity is large, and it is desirable to add donor and acceptor impurities. Further, in recent years, a dry etching method using hydrofluoric acid vapor has also been used as a sacrificial layer etching technique for the silicon oxide film 2 to cope with sticking between the mass portion 10 and the substrate 1.

Next, the operation of the angular velocity detector 100 will be described. An AC voltage is applied to the fixed comb electrode 74 of the excitation electrode. Then, the electrostatic force of the alternating current between the fixed comb electrodes 74 and the movable comb electrodes 73 acts, floating unit A ₁ is vibrated in the x-axis direction. That is, as shown in FIG. 5, when the movable comb electrode 73 is attracted to the fixed comb electrode 74, the mass portion 10 is displaced to the + x axis side. At this time, the anchor 61
1 and 612, fixed beams 511 and 512 having one ends fixed to the substrate 1 directly, and fixed beams 521 and 52 having one ends fixed to the substrate 1 directly by anchor portions 621 and 622.
2 is convexly curved in the −x axis direction, and free beams 31 and 32
Is convexly curved in the + x-axis direction. Fixed beams 531 and 53
2 and free beam 33, fixed beams 541 and 542
The same is true for the relationship between and the free beam 34 (FIG. 5A).

Conversely, the movable comb electrode 73 is fixed to the fixed comb electrode 7.
When being rejected from 4, the mass unit 10 is displaced to the -x axis side. At this time, the fixed beams 511 and 512 and the fixed beams 521 and 522 are convexly curved in the + x axis direction, and the free beams 31 and 32 are convexly curved in the −x axis direction. Relationship between fixed beams 531 and 532 and free beam 33, fixed beam 5
The same applies to the relationship between 41 and 542 and the free beam 34 (FIG. 5B).

These fixed beams 511, 512, 52
1, 522, 531, 532, 541, and 542 have high flexibility in the x-axis direction, but have high rigidity in the y-axis direction. Therefore, the links 71 and 72 are easily displaced in the x-axis direction. Not easily displaced in the direction. Therefore, in the excited state, the fixed comb electrode 74 and the movable comb electrode 73
In addition, the gap between the fixed comb electrode 76 and the movable comb electrode 75 does not change, and they do not come into contact with each other.

With such a beam structure, the mass 10
Vibrates easily in the x-axis direction. The displacement x of this vibration is x =
If x ₀ sinαt (where α is the angular frequency of the voltage applied to the excitation electrode, x ₀ is the amplitude of the vibration in the x-axis direction), then the velocity V _x will be V _x = x ₀ αcosαt. In this vibration state, when the angular velocity ω acts around the z-axis, the mass 1
A Coriolis force F acts on 0 in the y-axis direction. This Coriolis force F is obtained by the following equation.

[0027]

F = 2mωV _x = 2mωx ₀ αcosαt (1) where m is the mass of the mass section 10.

Accordingly, the mass portion 10 is acted on in the y-axis direction by the force F of the formula (1), and vibrates in the y-axis direction at a frequency in the x-axis direction. The vibration displacement in the y-axis direction is detected by detecting the electrostatic force of one or both of the movable comb electrode 81 and the fixed comb electrodes 82 and 83, which are detection electrodes, and the movable comb electrode 84 and the fixed comb electrodes 85 and 86. It can be detected by a change in capacitance. Since the vibration displacement of the y-axis is proportional to the angular velocity ω given the Coriolis force F, it is proportional to the magnitude of the angular velocity ω.
Since the links 71 and 72 are fixed in the y-axis direction, the first beams 21 and 22 and the first beams 23 and 24 are curved in parallel and convexly in the ± y-axis direction, and the movable comb electrode 81 ,
84 is easily displaced in the y-axis direction.

[0029] The movable comb electrodes 75 are excitation detecting electrodes and the fixed comb electrodes 76 by displacement in the x-axis direction is detected, it is possible to detect the excitation amplitude x ₀ in the x-axis direction. As the excitation amplitude x ₀ is always a constant value, the magnitude of the voltage applied to the fixed electrode 74 is excitation electrodes by feedback control, always constant excitation amplitude in the x-axis direction of the mass portion 10 Can be

In the above embodiment, the displacement in the y-axis direction is determined by using either the average value of the outputs of the fixed comb electrodes 85 and 86 as the detection electrodes or the average value of the outputs of the fixed comb electrodes 82 and 83. One or both capacitance changes are detected. However, the displacement in the y-axis direction is detected from the average value of the output values of the fixed comb electrodes 82 and 83, and the displacement is always zero.
A voltage may be applied to the fixed comb electrodes 85 and 86, and the angular velocity ω may be detected from the amplitude of the voltage. That is,
An equivalent voltage is applied to the fixed comb-teeth electrodes 85 and 86 so that an external force that cancels the Coriolis force F expressed by the equation (1) is applied to the mass unit 10.

As described above, if the angular velocity ω is detected in a state where the displacement in the y-axis direction is 0, it is possible to eliminate the non-linear error.

Next, a second embodiment will be described. First
In the detector 100 of the embodiment, the fixed beams 511 and 512 are disposed on both sides of the free beam 31 connected to the link 71, and the fixed beams 521 and 522 are disposed on both sides of the free beam 32. 532 is the free beam 3
3 and fixed beams 541 and 542 are disposed on both sides of the free beam 34. However, the detector 200 of the second embodiment has a fixed beam 5 as shown in FIG.
11 and 512 are disposed on one side of the free beam 31 on the + x axis side, and the fixed beams 521 and 522 are
2 on one side of the + x-axis side. The fixed beams 531 and 532 are disposed on one side of the free beam 33 on the −x axis side, and the fixed beams 541 and 542 are disposed on one side of the free beam 34 on the −x axis side.

Next, a third embodiment will be described. Second
In the detector 200 of the third embodiment, each fixed beam is provided on the side (outside) far from the mass unit 10 with respect to the free beam, whereas in the detector 300 of the third embodiment, each fixed beam is It is provided on the side (inside) near the mass section 10 with respect to the free beam. That is, in the detector 300 of the third embodiment, as shown in FIG. 7, the fixed beams 511 and 512 are disposed on one side on the −x-axis side with respect to the free beam 31, and the fixed beams 521 and 522 are 32 are disposed on one side on the -x axis side. In addition, fixed beams 531 and 532 are disposed on one side of the free beam 33 on the + x axis side,
1, 542 are disposed on one side of the free beam 34 on the + x-axis side.

Next, the performance of the detectors of the first to third embodiments was evaluated as follows. In this detector, in order to improve the detection accuracy, it is necessary that the excitation vibration in the x-axis direction does not leak in the y-axis direction. As shown in FIG. 8, assuming that the force in the x-axis direction of one movable tooth 731 of the movable comb electrode 73 is g _x and the force in the y-axis direction is g _y , the respective forces g _x and g _y are as follows. Is expressed as follows.

[0035]

G _x = εwE ² / d (2)

G _y = ε wsE ² [1/2 (dy) ² −1/2 (d + y) ² ] (3) where ε is the dielectric constant of the gap, and d is the displacement in the y-axis direction is 0.
The distance between the movable teeth 731 and the fixed teeth 741 and 742 at the time of
y is displacement, E is applied voltage, w is movable tooth 731, fixed tooth 7
41, 742, the thickness s is the movable tooth 731 and the fixed tooth 74
1, 742 is the length of the overlapping portion in the x-axis direction. When the number of comb teeth is n, the forces G _x and G _y acting on the link 71 are n times the expressions (2) and (3).

In FIG. 8, free beams 31, 32,
33, 34, links 41, 42, 43, 44 and fixed beams 511, 512, 521, 522, 531, 532,
The folded beam consisting of 541 and 542, the x-axis, the y-axis direction displacement figure, the spring constant k _x, k _y
Is modeled by a spring having The force G _{x in} the x-axis direction and the force G _y in the y-axis direction acting on the link 71 are 10 ⁻³ N
Degree. The state of deformation of each beam when this external force was applied to the link 71 was analyzed by the finite element method. Then, the link 71 when external forces G _x and G _y are individually applied
The displacement x in the x-axis direction and the displacement y in the y-axis direction were determined. Then, the spring constant k _x in the _x -axis direction was determined by k _x = G _x / x, and the spring constant ky in the _y- axis direction was determined by _ky = G _y / y. First embodiment-
FIG. 11 shows how the beam is deformed in the angular velocity detector of the third embodiment. (A) and (b) are the first embodiment,
(C) and (d) show the beam structure of the second embodiment, and (e) and (f) show the beam structure of the third embodiment. And (a),
(C), (e) the case of applying only the external force G _x in the center of the link 71, (b), (d ), (f) is modified in the case of applying only the external force G _y in the middle of the link 71 figure Is shown.

In this model, as shown in FIG. 1, the width e of each beam is 3 μm, the length L is 233 μm, and the thickness w (the thickness of the silicon layer 3 in FIGS. 8 and 4) is 1
0 μm, the first support beams 21, 22, 23, 24 have a length of 203 μm, a width of 2 μm, and a mass of the mass section 10 of 3.6 × 1
0 and ^-10 kg. Also, the first embodiment, as shown in FIG. 1, the distance between the fixed beam 511 and 512 as 2H, the case of changing the distance H, computed spring constant k _x, a k _y. In the second and third embodiments, the distance between the fixed beams 511 and 512 and the free beam 31 is H. As the spring constant ratio R of the spring constant ky in the _y- axis direction to the spring constant k _x in the x-axis direction increases, the link 71 can be easily displaced in the x-axis direction.
This means that it is difficult to displace in the axial direction. Therefore, the larger the spring constant ratio R, the better the characteristics of the angular velocity detector. FIG. 9 shows a calculation result by this model, and FIG. 10 shows a graph of the calculation result.

The structure P3 of the first embodiment, that is, the structure P3 in which the fixed beam exists on both sides of the free beam, is the second embodiment, the third embodiment, that is, the structure in which two fixed beams are present on one side of the free beam. It is understood that the characteristics are better than those of the structures P6 and P7. However, the structures P6, P6 of the second and third embodiments
7, the spring constant ratio R is larger than the structure P1 in which the frame extending in the x-axis direction and one fixed beam on one side with respect to the free beam and the structure P2 in which the frame is not provided with respect to the structure. It is understood that the characteristics are good. further,
In the structure of the first embodiment, the interval H is 100 μm, 20 μm.
In the case of 0 μm, it is understood that the spring constant ratio R decreases as the interval H increases, and the characteristics deteriorate.

FIG. 12 is a plan view of an angular velocity detector 1000 according to a fourth specific example of the present invention. In the configuration of the angular velocity detector 1000, the same elements as those of the angular velocity detector 100 are denoted by the same reference numerals.

In FIG. 12, the paper surface is the substrate surface, the z-axis is in a direction perpendicular to the substrate surface, and the x-axis is on the substrate surface as shown in FIG.
Take the y-axis. The detector 1000 detects the angular velocity ω around the z axis, the x axis is the excitation axis, and the y axis is the detection axis.
Beams 21 and 22 constituting the first support beam extend in the + x-axis direction on the + x-axis direction side 10a of the mass section 10, and the −x-axis direction beam 10b of the mass section 10 extends in the −x axis direction. 1
Beams 23 and 24 constituting the support beam extend in the −x-axis direction.

Next, the second support beam will be described.
The second support beam is composed of a free beam, a fixed beam, and a link connecting them. The other ends 21a and 22a of the beams 21 and 22 are connected by a link 71 extending in the y-axis direction, and the other ends 23a and 24a of the beams 23 and 24 are connected to y
They are connected by a link 72 extending in the axial direction. Link 7
Reference numerals 1 and 72 are structures having a predetermined width in the x-axis direction.

The end faces of the link 71 having a width facing the -y axis direction are connected to free beams 311 and 312 extending in the -y axis direction at predetermined intervals in parallel with each other. The end faces of the link 71 having a width facing the + y-axis direction are connected to free beams 321 and 322 extending in the + y-axis direction at predetermined intervals in parallel with each other.
Similarly, end faces of the link 72 having widths facing the -y axis direction and the + y axis direction are free beams 331 extending in the -y axis direction and the + y axis direction at predetermined intervals in parallel with each other. And 332, 341 and 342.

One end 311 of the free beams 311 and 312
a and 312a are fixed to the link 41 near the center thereof, respectively. In exactly the same way, the ends 321a and 322a of the free beams 321 and 322, the free beam 33
One ends 331a and 332a of the first and third beams 332 and 341a and 342a of the free beams 341 and 342 are fixed to the links 42, 43 and 44, respectively, near the center thereof.

From both ends 41a and 41b of the link 41, fixed beams 511 and 512 extend in the + y-axis direction, respectively.
One end of 2 is fixed to the silicon substrate 1 by anchor portions 611 and 612. Similarly, from both ends 42a, 42b of the link 42, fixed beams 521,
522 extend in the −y-axis direction, and one ends of the fixed beams 521 and 522 are connected to the anchor portions 621 and 62.
2 fixed to the silicon substrate 1. Similarly, fixed beams 531 and 532 extend in the + y-axis direction from both ends 43a and 43b of the link 43, respectively, and one ends of the fixed beams 531 and 532 are connected to the silicon substrate by anchor portions 631 and 632, respectively. Fixed to 1. Similarly, from both ends 44a and 44b of the link 44, fixed beams 541 and 542 extend in the −y axis direction, respectively.
One end of 2 is fixed to the silicon substrate 1 by anchor portions 641 and 642.

The link 71 has teeth extending in the x-axis direction.
A movable comb electrode 73 is formed along the y-axis direction.
A fixed comb electrode 74 is fixed to the silicon substrate 1 so as to mesh with the movable comb electrode 73. The movable comb electrode 73 and the fixed comb electrode 74 constitute an excitation electrode. Similarly, the link 72 has teeth extending in the −x-axis direction, and the movable comb electrode 75 is formed along the y-axis direction. A fixed comb electrode 76 is fixed to the silicon substrate 1 so as to mesh with the movable comb electrode 75. The movable comb electrode 75 and the fixed comb electrode 76 constitute an excitation detection electrode. Then, the wiring layer 7 is provided on the fixed comb electrode 74.
7 is connected, and the wiring layer 78 is connected to the fixed comb electrode 76.

A movable comb electrode 81 is provided at the end 10c on the + y-axis side of the mass section 10 along the + x-axis direction. Fixed comb electrodes 82 and 83 are fixed to the silicon substrate 1 so as to mesh with the teeth on both sides of the silicon substrate 1. Similarly,-of the mass portion 10
At the end 10d on the y-axis side, movable comb-teeth electrodes 84 are disposed along the -x-axis direction with teeth extending in the ± x-axis direction, and are engaged with teeth on both sides of the movable comb-teeth electrode 84. The fixed comb electrodes 85 and 86 are fixed to the silicon substrate 1. The movable comb electrode 81 and the fixed comb electrodes 82 and 83 and the movable comb electrode 84 and the fixed comb electrodes 85 and 86 constitute an angular velocity detection electrode. In addition, fixed comb electrodes 82 and 83
Are connected to wiring layers 87 and 88, respectively, and fixed comb electrodes 85 and 86 are connected to wiring layers 89 and 90, respectively.

The substrate 1 having the above structure is covered with a square cap. In the above-described structure, the mass portion 10 is formed in a lattice shape with the links 41, 42, 43, 44,
Reference numerals 71 and 72 are formed in a ladder shape to facilitate etching of the lower layer. Mass part 10, beams 21, 2
2, 23, 24, free beams 311, 312, 321,
322, 331, 331, 341, 342, link 4
1, 42, 43, 44, 71, 72, movable comb electrode 7
3, 75, 81, 84, fixed beams 511, 512, 5
21, 522, 531, 532, 541, and 542 (the portion composed of these is referred to as a “floating part A ₂ ”) and the substrate 1, and the floating part A ₂ Floating and supported. The floating portions formed continuously with the mass portion 10 are anchor portions 611, 612, 621, and 62.
2, 631, 632, 641, and 642 are fixed to the substrate 1 and are floated and supported with respect to the substrate 1.

The relationship between the size of the movable comb electrode 73 and the fixed comb electrode 74 of the angular velocity detector 1000, the relationship between the movable comb electrode 75 and the fixed comb electrode 76, and the movable structure constituting the angular velocity detection electrode Comb electrode 81 and fixed comb electrodes 82, 83,
The relationship between the movable comb electrode 84 and the fixed comb electrodes 85 and 86 is substantially the same as the relationship between the electrodes of the angular velocity detector 100 shown in FIG.

The method of manufacturing the angular velocity detector 1000 having the above structure is exactly the same as the method of manufacturing the angular velocity detector 100, and is manufactured by a semiconductor fine processing technique.

The operation of the angular velocity detector 1000 is almost the same as the operation of the angular velocity detector 100 shown in FIG. That is, as shown in FIGS. 13A and 13B, when an AC voltage is applied to the fixed comb electrode 74 of the excitation electrode, an AC electrostatic force is applied between the fixed comb electrode 74 and the movable comb electrode 73. There acts, floating unit a ₂ is vibrated in the x-axis direction.

When the movable comb electrode 73 is attracted to the fixed comb electrode 74, the mass 10 is displaced toward the + x axis. At this time, the fixed beams 511 and 512 whose one ends are directly fixed to the substrate 1 by the anchor portions 611 and 612 and the fixed beams 521 and 522 whose one ends are directly fixed to the substrate 1 by the anchor portions 621 and 622 are −. The free beams 311 and 312, 321 and 322 are convexly curved in the x-axis direction, and are convexly curved in the + x-axis direction. Relationship between fixed beams 531 and 532 and free beams 331 and 332, fixed beams 541 and 54
The same applies to the relationship between 2 and the free beams 341 and 342 (FIG. 13A).

On the contrary, the movable comb electrode 73 is fixed to the fixed comb electrode 7.
4, the mass unit 10 is displaced toward the −x axis side,
Fixed beams 511 and 512 and fixed beams 521 and 52
2 is convexly curved in the + x axis direction, and the free beams 311 and 312, 321 and 322 are convexly curved in the −x axis direction. Fixed beams 531 and 532 and free beams 331 and 3
32, fixed beams 541 and 542 and free beam 3
The same applies to the relationship between 41 and 342 ((b) in FIG. 13).
These fixed beams 511, 512, 521, 522,
531, 532, 541, and 542 have high flexibility in the x-axis direction, but have high rigidity in the y-axis direction, so that the links 71 and 72 are easily displaced in the x-axis direction, but are easily displaced in the y-axis direction. Does not displace. Therefore, in the excitation state,
The gaps between the fixed comb electrode 74 and the movable comb electrode 73 and between the fixed comb electrode 76 and the movable comb electrode 75 do not change, and they do not come into contact with each other.

With such a beam structure, the mass 10
Easily vibrates in the x-axis direction, and the displacement x of this vibration is x = x
When _{0 sinαt (α} is the angular frequency of the voltage applied to the excitation electrodes, the amplitude of x ₀ is the vibration in the x-axis direction), the speed V _x is V _x =
x ₀ αcosαt. When an angular velocity ω acts around the z-axis in this vibration state, Coriolis force F acts on the mass portion 10 in the y-axis direction. Thus, the angular velocity detector 1000
Is exactly the same as the operation principle of the angular velocity detector 100 described above. Angular velocity detector 100 having such a structure
For 0, the gap between the free beams 311 and 312 and the performance of the detector indicated by “Gap” in FIG.
Evaluation was performed in the same manner as in the third example. Free beams 321 and 32
The interval between 2, 331 and 332, and the interval between 341 and 342 were made equal to the interval between the free beams 311 and 312. G
The spring constant k _x when ap is 9.5,11.5,21.5μm, k _y
FIG. 14 is a table showing calculation results of the horizontal rotation angle θ of the mass section 10, and FIGS. The horizontal rotation angle θ of the mass unit 10 is as shown in FIG. For comparison, a conventional angular velocity detector,
14 also shows the angular velocity detector 100 of the first embodiment.
It was shown to.

The first support beam has a length of 175 μm and a width of 2 μm.
m, each fixed beam and free beam are as described below, and other amounts are the same as those in FIG. 9 described above. (1) Conventional structure: length of fixed beam 35 and free beam 31 is 209 μm, width is 3.5 μm, and distance between fixed beam 35 and free beam 31 is 36 μm. (2) First embodiment: fixed beams 511 and 512, free beam 31 length 203 μm, width 3 μm, fixed beam 51
The distance between 1 and the fixed beam 512 is 72 μm. (3) Fourth embodiment: fixed beams 511 and 512, free beams 311 and 312, length 197 μm, width 2.7 μm,
The distance between the fixed beam 511 and the fixed beam 512 is 72 μm.

As shown in FIG. 14, the angular velocity detector 1000 has the conventional angular velocity detector and the angular velocity detector 1 of the first embodiment.
It can be seen that the spring constant ratio R is large and the horizontal rotation angle θ of the mass portion is extremely small as compared with 00. Also, the gap Gap between two parallel free beams is 9.5, 11.5, 21.5μ.
It can be seen that the spring constant ratio R increases and the horizontal rotation angle θ decreases as m increases. 15 and FIG. 16 show that, as the gap Gap increases,
It can be seen that the spring constant ratio R increases linearly, but the rate of decrease of the horizontal rotation angle θ of the mass decreases.

In the above embodiment, two fixed beams are used, but three or more fixed beams may be used. It is also understood that the smaller the distance 2H between the fixed beams is, the better the characteristics are in the mold of the first embodiment. From the results of FIG. 9, the H / L is about 0.3 to 0.1.
4 or less is desirable. In the case of P4, H / L is 0.43. As described in detail above, the present invention provides a beam length,
There is no particular limitation on the spacing, width, thickness, etc., and the free beam is supported on the substrate so as to be folded back by at least two fixed beams. With this beam structure, the free beam supporting the first support beam supporting the mass portion can be extremely easily displaced in the x-axis direction and hardly displaced in the y-axis direction. Therefore, since the excitation component in the x-axis direction does not leak in the detection axis direction, which is the y-axis direction, the detection accuracy of the angular velocity detector is improved.

Also, comparing with the case of one free beam,
By making a set of two or more free beams parallel to each other,
The spring constant in the y-axis direction was further increased, and the horizontal rotation of the mass portion was significantly reduced. Therefore, since the excitation component in the x-axis direction does not leak in the detection axis direction which is the y-axis direction, the detection accuracy of the angular velocity detector is further improved. When two free beams are used, the horizontal rotation of the mass can be suppressed by increasing the distance between the two beams.
In relation to the fixed beam spacing of the book,
0.3 is preferred. When Gap in FIG. 14 is 15.5 μm
0.22.

In the above embodiment, a semiconductor material is used. However, a dielectric material, in particular, a piezoelectric material may be used. In this case, PZT, LiTaO ₃ , LiNbO ₃ , quartz, and piezoelectric ceramics are suitable.

In the present invention, the operation has been described with reference to the embodiment based on the vibration type angular velocity detector.
The first essential part of the present invention is the fixed beams 511 and 51 connected to the free beam 31 and the free beam via the link 41.
2 that vibration is difficult in the y-axis direction and vibration resistance in the x-axis direction. The second essential part of the present invention is in the free beams 311 and 312 and the fixed beams 511 and 512 connected to the free beams via the link 41. That is, the horizontal direction rotation of the mass section 10 is suppressed by making the direction vibratory. Therefore, the beam structure of those main parts is not necessarily limited to the above-mentioned vibration type angular velocity detector, and is applied and developed as a general vibration type sensor for detecting various physical quantities, chemical quantities, or optical quantities described below. it can.

The first candidate is detection of the amount of acceleration. This is because, for a stable excitation state in which excitation is performed at a constant amplitude in the x-axis direction, the amplitude due to the movement of the mass section in the x-axis direction due to the inertial force of the mass section when acceleration in the same direction is applied. Is detected as a change in capacitance of the excitation or feedback electrode. As a second candidate, application to a stoichiometric sensor or the like that applies the principle that the mass changes when a gas adheres to a mass portion and thereby the resonance frequency of excitation changes. A third candidate is an application to sensing of optical quantity.
This means, for example, an application example applying a principle in which the resonance frequency of the vibrator is changed by the temperature change of the vibrator that is changed by irradiating the mass portion or the beam portion with the optical amount. Further, as a fourth candidate, application to a system for detecting a dynamic quantity such as a force or a pressure, which applies a principle in which an excitation amplitude or a resonance frequency is changed by an external force applied or transmitted to a vibrator, may be mentioned.

[Brief description of the drawings]

FIG. 1 is a plan view showing a configuration of an angular velocity detector according to a first specific example of the present invention.

FIG. 2 is a sectional view showing the configuration of the angular velocity detector according to the first embodiment.

FIG. 3 is an explanatory diagram showing a relationship between a movable comb electrode and a fixed comb electrode.

FIG. 4 is a sectional view showing a manufacturing process of the angular velocity detector according to the first embodiment.

FIG. 5 is an explanatory diagram showing a state of displacement of the angular velocity detector according to the first embodiment.

FIG. 6 is a plan view showing a configuration of an angular velocity detector according to a second embodiment.

FIG. 7 is a plan view showing a configuration of an angular velocity detector according to a third embodiment.

FIG. 8 is an explanatory diagram equivalently showing the relationship between a movable comb electrode, which is an excitation electrode, a fixed comb electrode, and a beam.

FIG. 9 shows the x-axis direction of the beam structure for each beam structure,
FIG. 10 is a table showing calculated values of a spring constant ratio indicating the degree of ease of deformation in the y-axis direction.

FIG. 10 is a graph showing calculated values of spring constant ratios indicating the ease of deformation of the beam structure in the x-axis direction and the y-axis direction for each beam structure.

FIG. 11 is an explanatory diagram showing a deformed state obtained when calculating a spring constant ratio for each beam structure.

FIG. 12 is a plan view showing a configuration of an angular velocity detector according to a fourth embodiment.

FIG. 13 is an explanatory diagram showing a state of displacement of an angular velocity detector according to a fourth embodiment.

FIG. 14 is a table showing calculated values of a spring constant ratio indicating the degree of ease of deformation of the beam structure in the x-axis direction and the y-axis direction for each beam structure, and a horizontal rotation angle of the mass portion.

FIG. 15 is a graph showing calculated values of spring constant ratios indicating the ease of deformation of the beam structure in the x-axis direction and the y-axis direction for each beam structure.

FIG. 16 is a graph showing calculated values of the horizontal rotation angle of the mass portion of the beam structure for each beam structure.

FIG. 17 is a plan view showing a configuration of a conventional angular velocity detector.

FIG. 18 is a sectional view showing a configuration of a conventional angular velocity detector.

FIG. 19 is a plan view showing the configuration of another conventional angular velocity detector.

FIG. 20 is a sectional view showing the configuration of another conventional angular velocity detector.

FIG. 21 is an explanatory view showing a deformed state of a beam when a frame is removed.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Silicon substrate 10 ... Mass part 21, 22, 23, 24 ... 1st support beam 31, 32, 33, 34, 311, 312, 321, 3
22, 331, 332, 341, 342 ... Free beams 511, 512, 521, 522, 531, 532, 5
41, 542: fixed beam 41, 42, 43, 44, 71, 72: link 73, 75, 81, 84: movable comb electrode 74, 76, 82, 83, 85, 86: fixed comb electrode 611, 612 , 621, 622, 631, 632, 6
41, 642 ... anchor part 87, 88, 89, 90 ... wiring layer 91 ... cap

Continuation of the front page (72) Inventor Hiroshi Nonomura 41-1, Yokomichi, Nagakute-cho, Aichi-gun, Aichi Prefecture Inside Toyota Central Research Laboratory Co., Ltd. (56) References JP-A-8-159776 (JP, A) 8-152327 (JP, A) JP-A-5-248872 (JP, A) JP-A-9-318649 (JP, A) JP-A-9-512106 (JP, A)

Claims (2)

(57) [Claims] 1. An x-axis and a y-axis perpendicular to the x-axis on a substrate surface, and a z-axis perpendicular to the substrate surface. In a vibrating angular velocity detector that detects the angular velocity by detecting a physical quantity related to the Coriolis force that generates the angular velocity around the z-axis in the y-axis direction,
A first support beam extending in the axial direction, a free beam extending from the other end of the first support beam and extending in the y-axis direction, and any one of the free beams is parallel to the free beam. At least a predetermined distance from each other, and an end closer to the first support beam is fixed to the substrate.
A fixed beam, a second support beam connecting the other end of the fixed beam and one end of the free beam, and comprising a link extending in the x-axis direction. vessel. 2. The free beam is a set of two or more free beams extending from the other end of the first support beam and extending in parallel with each other at a predetermined interval in the y-axis direction. The vibration angular velocity detector according to claim 1, wherein: