JPH11248733A - Angular velocity sensor and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make possible the accurate detection of angular velocity. SOLUTION: An outer-side structural body 100 with beams 8a-8d to oscillate in a direction parallel with the surface of a silicon substrate 1 is partitioned by through holes formed in the substrate 1. An inner-side structural body 200 with beams 43 and 44 to move in an X direction intersecting an oscillating direction Y at right angles in parallel with the surface of the substrate 1 by angular velocity is partitioned by through holes 36-39 formed in the structural body 100. The fixed electrodes 48a-48f and 49a-49f for detecting angular velocity of the structural body 100 and the movable electrodes 46a-46c and 47a-47c for detecting angular velocity of the inner-side structural body 200 opposed to the fixed electrodes 48a-48f and 49a-49f of the structural body 100 are electrically separated by insulators 50a-50f, 51a-51f, 57, and 58 in the through holes formed in the structural body 100.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration type angular velocity sensor and a method of manufacturing the same.

[0002]

2. Description of the Related Art A vibration type angular velocity sensor is disclosed in Japanese Patent Laid-Open No. 9-335.
No. 57 is disclosed. This angular velocity sensor is shown in FIG.
This will be described with reference to FIGS. The sensor has a lower Si layer 3
01, a sacrifice layer 302, and an upper Si layer 303. Multilayer substrate 30
A vibrator 305 having a beam 304 is formed at the center of the zero, and the vibrator 305 excites (vibrates) in the Y direction in the figure. In the vibrator 305, an acceleration sensor element 307 having a beam 306 is formed by using a silicon surface micromachining technique. That is, the upper Si layer 3
03, and the sacrificial layer 302 thereunder is removed by etching.
7 are formed. The acceleration sensor element 307 is
It has movable electrodes 308 and 309 for detecting angular velocity, and these movable electrodes 308 and 309 are fixed electrodes 310 and 311 respectively.
And is facing. Then, X orthogonal to the excitation direction Y due to the angular velocity (Coriolis force) at the time of excitation of the vibrator 305
The movement of the angular velocity detecting movable electrodes 308 and 309 in the direction is detected as a change in capacitance between the electrodes 308 and 310 and between 309 and 311.

However, since the Coriolis force is very small,
In the angular velocity sensor, the reduction of noise is the most important issue, but the thickness t1 of the acceleration sensor element 307 (thickness of the upper Si layer 303) is reduced to, for example, 10 μm, so that the mass of the weight is small. , The areas of the counter electrodes 308 to 311 also become smaller. As a result, the output signal has been reduced.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide an angular velocity sensor capable of detecting an angular velocity with high accuracy by a novel configuration and a method of manufacturing the same.

[0005]

According to a first aspect of the present invention, there is provided an angular velocity sensor, wherein a through-hole formed in a semiconductor substrate defines an outer-side structure having beams and exciting in a direction parallel to the surface of the semiconductor substrate. Along with the through-hole formed in the outer-side structure, an inner-side structure having a beam and moving in a direction perpendicular to the excitation direction in a direction parallel to the surface of the semiconductor substrate at an angular velocity is further defined. The fixed electrode for angular velocity detection of the outer structure and the movable electrode for angular velocity detection of the inner structure opposed to the fixed electrode were electrically separated by an insulator in a through hole formed in the outer structure. It is characterized by:

Thus, the through holes formed in the semiconductor substrate form the outer and inner structures, and electrically separate the fixed and movable electrodes for detecting angular velocity. As a result, the thickness of the inner structure can be increased, so that the mass of the weight can be increased and the output signal can be increased. In addition, since the thickness of the inner and outer structures can be increased, the area of the counter electrode can be increased and the output signal can be increased.

Further, since the fixed electrode for angular velocity detection and the movable electrode are electrically separated by an insulator in the through hole formed in the outer structure, the fixed electrode for angular velocity detection and the movable electrode are separated from each other. Each can be freely insulated. That is, the comb-shaped electrodes and the like can be insulated in a free layout using the insulator in the through hole.

Here, in the invention according to claim 2, the movable electrode for detecting angular velocity of the inner-side structure according to claim 1 is comb-shaped, and the fixed electrode for detecting angular velocity of the outer-side structure is A first electrode opposed to one side surface of the movable electrode for angular velocity detection, and a second electrode opposed to the other side surface of the movable electrode for angular velocity detection;
Further, the first and second electrodes are electrically separated by an insulator in a through hole formed in the outer-side structure, and the first electrodes are electrically connected to each other by metal wiring, and each of the first and second electrodes is electrically connected to each other. The two electrodes are electrically connected by metal wiring.

Therefore, the first and second fixed electrodes for detecting angular velocity can be arranged at equal distances from both side surfaces of the movable electrode for detecting angular velocity. As a result, the angular velocity can be detected with higher accuracy.

In other words, in the conventional structure shown in FIGS. 11 and 12, the movable electrode (30
8, 309), it is difficult to dispose the first and second fixed electrodes for angular velocity detection 310, 311 at the same distance from each other. Therefore, when a servo mechanism is used, a rotational torque is generated in the angular velocity detecting movable electrodes 308 and 309, which causes noise, which causes a problem that the resolution of the angular velocity sensor is reduced. On the other hand, in the present invention, the first and second fixed electrodes for angular velocity detection can be arranged at equal distances on both sides of the movable electrode for angular velocity detection, and the rotational torque is reduced when performing servo control. It can hardly occur. In general, the use of a servo mechanism has advantages such as improvement of signal linearity and expansion of a dynamic range, and is advantageous in that performance is improved.

The fixed electrode for excitation has a comb-like shape, and a contact hole for electrically connecting to a metal wiring is formed on each fixed tooth of the comb-shaped fixed electrode. If a large number are formed at equal distances in the juxtaposition direction, each tooth becomes equipotential and the excitation direction is less likely to be inclined.

Further, as described in claim 4, the movable electrode for excitation has a comb-like shape, and a contact hole for electrically connecting to the metal wiring is formed on each tooth of the comb-like movable electrode. If a large number are formed at equal distances in the juxtaposition direction, each tooth becomes equipotential and the excitation direction is less likely to be inclined.

Further, when the metal wiring from the outer structure is extended on the beam in the outer structure as described in claim 5, wiring can be performed without using wire bonding. This is practically preferable.

According to a sixth aspect of the present invention, a comb-shaped first movable electrode for excitation is disposed on one side of the outer-side structure body having two parallel sides as a planar shape. On the other side parallel to the side in the outer-side structure body, a second movable electrode for excitation, which is electrically connected to the first movable electrode for excitation and forms a comb-like shape, is further arranged. When any of the movable electrodes is connected to the metal wiring, the excitation direction is unlikely to be inclined.

Further, when the back surface of the outer-side structure is covered with an insulating film, no surface leak occurs when dust or the like adheres to the back surface. In the method of manufacturing an angular velocity sensor according to claim 8, an insulator filling trench is formed in a predetermined region on a surface of the semiconductor substrate,
An insulating film is deposited on the surface of the semiconductor substrate, and the trench for filling the insulator is filled with the insulating film. Then, the insulating film is patterned to open a through-hole forming region of the substrate, and a metal wiring is formed on the insulating film. Further, a recess reaching the insulator filling trench groove is formed by anisotropic etching from the back surface of the semiconductor substrate, a thin portion is formed on the bottom surface of the recess, and a through hole is formed in the thin portion of the semiconductor substrate. ,
An outer-side structure that excites in a direction parallel to the surface of the semiconductor substrate and an inner-side structure that moves in a direction parallel to the surface of the semiconductor substrate by angular velocity in a direction perpendicular to the excitation direction are formed.

As a result, the angular velocity sensor according to the first aspect can be manufactured. In this case, in the apparatus shown in FIGS. 11 and 12, the process of etching the sacrificial layer was required, and the process was complicated. However, in the present invention, the process of etching the sacrificial layer was unnecessary, and the process was simplified.

Here, it is preferable that a silicon substrate be used as the semiconductor substrate. Furthermore, when the SOI substrate is used as the semiconductor substrate as described in claim 10, the back surface of the outer-side structure is covered with the insulating film as in the sensor described in claim 7.
Therefore, when dust or the like adheres to the back surface, surface leakage does not occur.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a plan view of a vibration type angular velocity sensor according to this embodiment. The vibration type angular velocity sensor includes a silicon substrate 1 as a semiconductor substrate.
Has an outer-side structure 100 at the center. FIG.
3 is an enlarged view of the outer-side structure 100. FIG. FIG.
FIG. 3A is a cross-sectional view taken along the line AA in FIG. 1, and FIG.
3 (c) is a cross-sectional view taken along the line CC of FIG.

In FIGS. 1 and 2, the insulating film 2 in FIG. 3 is omitted to make the figures easier to see. As shown in FIG. 1, the silicon substrate 1 has a square shape. FIG. 3 (a)
As shown in FIG. 1, an insulating film 2 is formed on the front surface (upper surface) of the silicon substrate 1, and a concave portion 3 is formed on the rear surface (lower surface) of the silicon substrate 1. Are formed. Further, a through hole 5 is formed in the thin portion 4.
Is formed in the through hole 5 as shown in FIG.
A square frame portion 6 composed of the four sides and an outer-side structure 100 are sectioned. Outer side structure 10
0 denotes a rectangular main body 7 and four beams 8a, 8b, 8
c, 8d, the first movable electrode 9, and the second movable electrode 10
Consists of The beams 8a, 8b, 8c, 8d are band-shaped and meandering. A rectangular main body 7 is located at the center of the silicon substrate 1, and beams 8a, 8b, 8c, 8d extend from four corners of the rectangular main body 7, and the other ends of the beams 8a, 8b, 8c, 8d. Are connected to the square frame 6 of the silicon substrate 1. Therefore, the main body 7 of the outer-side structure 100 has a structure that is supported so as to be movable in the Y direction in the orthogonal two-axis system coordinates (XY coordinates) parallel to the surface of the substrate 1 in FIG.

As shown in FIG. 1, one side of the main body 7 of the outer-side structure 100 has a driving first
A large number of movable electrodes (comb teeth) 9 are arranged in parallel.
On the other side of the main body 7 on the opposite side, a large number of second movable electrodes (comb teeth) 10 for driving are arranged in parallel. A large number of fixed electrodes (comb teeth) 13 for driving are also arranged in parallel in the rectangular frame portion 6 facing the first movable electrode 9. The movable electrode 9 and the fixed electrode 13 are alternately arranged. Similarly, the square frame portion 6 facing the second movable electrode 10
Also, a large number of fixed electrodes (comb teeth) 14 for driving are arranged in parallel. The movable electrode 10 and the fixed electrode 14 are alternately arranged.

The fixed electrode 13 having a comb-like structure for driving and the outer peripheral portion 15 at the root thereof are insulated by an insulator (eg, SiO ₂ ) 16 filled in the through hole.
That is, as shown in FIG. 4, they are electrically separated by the insulator 16 in the through hole 40 formed in the silicon substrate 1. A metal wiring (for example, Al, Ti, etc.) 17 extends on the insulating film 2 on the fixed electrode 13 in FIG. The fixed electrode 13 and the metal wiring 17 are electrically connected through contact holes (openings) 23 a to 23 e formed in the insulating film 2. Specifically, the contact holes 23 are equidistant in the direction in which the fixed electrodes 13 are arranged (X direction).
a to 23e are arranged. Further, the metal wiring 17 is electrically connected to an electrode terminal (pad) 18 disposed on the insulating film 2 in the outer peripheral portion 15 of the substrate.

Similarly, the fixed electrode 14 having a comb structure for driving
And the root of the outer peripheral portion 19 are insulated by an insulator (for example, SiO ₂ or the like) 20 filled in the through hole. That is, they are electrically separated by the insulator 20 in the through hole 40 in the same structure as in FIG. A metal wiring (for example, Al, Ti, etc.) 21 extends on the insulating film 2 on the fixed electrode 14 in FIG. Fixed electrode 1
4 and the metal wiring 21 are electrically connected through contact holes (openings) 24 a to 24 e formed in the insulating film 2. Specifically, the direction in which the fixed electrodes 14 are arranged (X direction)
The contact holes 24a to 24e are arranged at an equal distance from each other. In addition, the metal wiring 21 is connected to an electrode terminal (pad) 22 disposed on the insulating film 2 in the outer peripheral portion 19 of the substrate.
Is electrically connected to

As described above, the fixed electrodes 13 and 14 for excitation are used.
Are comb-shaped and have contact holes 23a to 23e and 24a to 2c for electrically connecting to the metal wirings 17 and 21.
A large number 4e are formed at equal distances in the direction in which the teeth of the comb-shaped fixed electrodes 13 and 14 are juxtaposed. As a result, the electrodes (teeth) 13 and 14 become equipotential. Note that, in FIG. 1, the number of the fixed electrodes 13 and 14 is "6" and the number of the contact holes 23a to 23e and 24a to 24e is "6", and Although the numbers of 23a to 23e and 24a to 24e are "5", for example, the number of electrodes may be "n" and the number of contact holes may be "n".

In the outer structure 100 shown in FIG.
A quadrangular insulator (for example, SiO 2)
₂ ) 30 are arranged, and the insulator 30 is filled in a rectangular annular through hole. That is, the inside and outside (the edge portion 31 and the central portion 32 in FIG. 2) are electrically separated (insulated) by the insulator 30 in the through hole 40 in the same structure as in FIG. In this manner, the movable electrodes 9 and 10 having the driving comb structure shown in FIG. Further, since two electrodes 9 and 10 are formed on the edge 31 of the main body 7, the two electrodes 9 and 10 are electrically connected.
Further, a metal wiring (for example, Al, Ti, or the like) 34 extends on the insulating film 2 on the edge portion 31 so that the movable electrode 1
0 and the metal wiring 34 are electrically connected through contact holes (openings) 33 a to 33 e formed in the insulating film 2. Specifically, the direction in which the movable electrodes 10 are arranged (X direction)
The contact holes 33a to 33e are arranged at an equal distance from each other. As shown in FIG. 5, the metal wiring 34 extends through the upper part of the beam 8c to the outer peripheral portion of the substrate as shown in FIG. 1, and is connected to an electrode terminal (pad) 35 arranged on the insulating film 2. It is electrically connected.

As described above, the first movable electrode 9 having a comb-like shape is arranged on one side of the outer-side structure body 7 having a rectangular planar shape. 7, a second movable electrode 10 for excitation, which is electrically connected to the first movable electrode 9 and has a comb-like shape, is arranged on another side parallel to the corresponding side of the movable electrode 10.
Are connected to the metal wiring. Therefore, both movable electrodes 9 and 10 can be arranged in parallel, and both movable electrodes 9 and 10 can be set to the same potential. The movable electrodes 9 and 10 for excitation have a comb-like shape and have contact holes 33 a to 33 e for electrically connecting to the metal wiring 34.
Are formed at equal distances in the direction in which the teeth of the comb-shaped movable electrodes 9 and 10 are arranged side by side. As a result, the electrodes (teeth) 9, 10 become equipotential. In the relationship between the number of comb-shaped movable electrodes 10 (the number of teeth) and the number of contact holes 33a to 33e, the number of movable electrodes 10 is "5" in FIG.
Although the number of the contact holes 33a to 33e is "5", the number of the electrodes may be "n" and the number of the contact holes may be "n-1".

In the outer structure 100 shown in FIG.
Through holes 36, 37, 38, and 39 are formed in the main body 7, and an inner-side structure 200 is defined at the center of the main body 7 by the through holes 36, 37, 38, and 39. The inner structure 200 includes the anchor portions 41 and 42.
, Beams 43, 44, band 45, and movable electrodes (comb teeth) 46 a, 46 b, 46 c, 47 a, 47 b, 4 for angular velocity detection
7c. The inner-side structure 200 can move in the X direction orthogonal to the excitation direction Y in a direction parallel to the surface of the substrate 1.

The inner structure 200 is described in detail.
A band 45 extends from the anchors 41 and 42 via the beams 43 and 44, and the band 45 has a linear shape extending linearly. Angular velocity detecting movable electrodes 46a, 46b and 46c are arranged in parallel on one side surface of the band portion 45. Similarly, the movable electrode 47 for detecting the angular velocity is provided on the opposite surface of the band portion 45.
a, 47b, 47c are arranged in parallel.

A fixed electrode (comb) 48a for angular velocity detection is provided on the outer structure 100 facing the movable electrodes 46a, 46b, 46c for angular velocity detection of the inner structure 200.
To 48f are juxtaposed in parallel. Here, the movable electrodes 46a for detecting angular velocity are interposed between the fixed electrodes 48a and 48b for detecting angular velocity and are arranged at an equal distance. In addition, fixed electrodes 48c and 48d for detecting angular velocity are used.
Between the movable electrode 46b for angular velocity detection,
In addition, they are arranged at an equal distance. The angular velocity detecting movable electrode 46c is interposed between the angular velocity detecting fixed electrodes 48e and 48f, and is disposed at an equal distance.

Similarly, a large number of angular velocity detecting fixed electrodes (comb teeth) 49a to 49f are provided in parallel on the outer structural body 100 facing the angular velocity detecting movable electrodes 47a, 47b, 47c of the inner structural body 200. It is juxtaposed. Here, the movable electrode 47a for angular velocity detection is interposed between the fixed electrodes 49a and 49b for angular velocity detection, and is disposed at an equal distance. A movable electrode 47b for detecting angular velocity is provided between the fixed electrodes 49c and 49d for detecting angular velocity.
And are arranged at an equal distance. Also, the angular velocity detection movable electrode 47c is sandwiched between the angular velocity detection fixed electrodes 49e and 49f, and
They are arranged equidistant.

In the outer structure 100, the bases of the fixed electrodes 48a to 48f and 49a to 49f are respectively provided with U-shaped insulators (eg, SiO ₂ ) 50a to 50f.
f, 51a to 51f are formed.
Reference numerals 0f and 51a to 51f are filled in U-shaped through holes. That is, they are electrically separated (insulated) by the insulators 50a to 50f and 51a to 51f in the through hole 40 in a structure similar to that of FIG. Further, the fixed electrode 48 of FIG.
a to 48f, 49a to 49f are metal wirings 52,
Each other is electrically connected by 53. That is, the fixed electrodes 48a, 48c, 48e, 49a, 49
c, 49e are electrically connected to the metal wiring 52, and the fixed electrodes 48b, 48d, 48f, 49b, 49
d and 49f are electrically connected to the metal wiring 53.
Thus, the fixed electrodes 48a to 48f, 49a to 49f
Are two sets of electrodes. These metal wiring 5
Numerals 2 and 53 are formed on the insulating film 2 and pass through upper portions of the outer beams 8d and 8b in FIG. 1 (see FIG. 5) and are connected to outer electrode terminals (pads) 54 and 55, respectively. However, in FIG. 1, between the end 52a of the metal wiring 52 (see FIG. 2) and the electrode terminal 54, the end 53 of the metal wiring 53 is provided.
a (see FIG. 2) and the metal wiring between the electrode terminal 55 are omitted.

As described above, the fixed electrodes 48a to 48f, 49a to 49f for detecting the angular velocity of the outer structure 100 and the movable electrodes 46a to 46c, 47a to 47c for detecting the angular velocity of the inner structure 200 opposed to the fixed electrodes.
Is a through hole (40) formed in the outer structure 100.
By the insulators 50a to 50f and 51a to 51f inside,
Electrically isolated. More specifically, the movable electrodes 46 a to 46 c and 4 for detecting the angular velocity of the inner-side structure 200.
7a to 47c are comb-shaped, and the outer side structure 100
Fixed electrodes 48a-48f, 49a-49 for detecting angular velocity
f is a comb-shaped, and the angular velocity detecting movable electrode 46
a-46c, 47a-47c, the first electrodes 48a, 48c, 48e, 49a, 49c, 49e facing one side surface.
And angular velocity detection movable electrodes 46a to 46c, 47a to 4
7c, the second electrodes 48b, 48d, 4 facing the other side surface.
8f, 49b, 49d, and 49f, and the first and second electrodes are connected to the outer structure 1
Insulators 50a to 50f, 51 in the through holes formed at 00
a to 51f, each first electrode 4
8 a, 48 c, 48 e, 49 a, 49 c, 49 e are electrically connected by the metal wiring 52, and each second electrode 48
b, 48d, 48f, 49b, 49d, 49f are electrically connected by a metal wiring 53. Therefore,
These fixed electrodes 48a to 48f and 49a to 49f can be freely insulated and can be freely connected to each other by using a metal wiring, and the layout is excellent.

In FIG. 2, the fixed electrodes 48a to 48a-4
8f and 49a to 49f are in electrical contact with metal wirings 52 and 53, respectively, by contact holes (one of which is indicated by reference numeral 56).

In FIG. 2, the outer structure 1
The U-shaped insulators (for example, SiO ₂ ) 57, 58 are formed at the roots of the anchor portions 41, 42 at 00, and the inner structure 2 is formed by the insulators 57, 58.
00 and its periphery are electrically insulated. That is, the insulators 57 and 58 are filled in the U-shaped through-holes, and are electrically separated by the insulators 57 and 58 in the through-holes 40 in the same structure as in FIG. . The movable electrodes 46a to 46c and 47a to 47c in FIG. 2 are electrically connected to the outer electrode terminals (pads) 60 in FIG. 1 by metal wires 59 (see FIG. 5) passing above the outer beams 8a. . However, in FIG. 1, the metal wiring between the end 59a of the metal wiring 59 (see FIG. 2) and the electrode terminal 60 is omitted.

As described above, in the present embodiment, the metal wirings 34, 52, 53, 59 from the outer-side structure 100 extend on the beams 8a to 8d of the outer-side structure 100, and No wire bonding is performed as a wiring structure from 100 to the pad.

Next, the operation of the angular velocity sensor will be described. The movable electrodes 9 and 10 having a comb structure for driving are connected to a ground potential (GND), and a sine-wave voltage with an offset is applied to one fixed electrode 13. Here, if the frequency of the sine wave voltage is made equal to the natural frequency of the vibration system, it is possible to drive with a small voltage. Further, since the driving voltage can cause noise, the resolution can be improved by making the frequency of the driving voltage equal to the natural frequency of the vibration system.

On the other hand, opposite-phase sine-wave voltages with the same offset are applied to the fixed electrode 14 on the opposite side. Thereby, the outer-side structure 100 vibrates in a direction parallel to the surface of the substrate 1 (Y direction in FIG. 1). That is, the outer-side structure 100 causes sinusoidal vibration. Here, if the entire system is placed in a vacuum, the Q value of resonance increases, so that it is possible to drive with a smaller voltage. Therefore, keeping the entire system in a vacuum leads to an improvement in resolution.

At this time, each of the electrodes 9, 10 and 13, 1
4 is contact holes 23a to 23e and 24a to 24
Since the potentials e and 33a to 33e are devised to be equal potentials, the excitation direction is unlikely to be inclined. In addition, since the movable electrodes 9 and 10 are arranged in parallel and equipotential on the parallel sides of the outer-side structure body 7, the excitation direction is unlikely to be inclined.

In this state, when an angular velocity is applied around an axis perpendicular to the surface of the substrate 1, a Coriolis force displaced sinusoidally in the X direction perpendicular to the vibration direction (Y direction) is applied. As a result, the inner-side structure 200 is moved in the X direction orthogonal to the excitation direction Y.
The capacitance between the angular velocity detecting movable electrodes (comb teeth) 46a to 46c and 47a to 47c and the angular velocity detecting fixed electrodes (comb teeth) 48a to 48f and 49a to 49f is sinusoidal. Changes to An electrostatic force against this is given. The change in the applied force is measured using, for example, a synchronous detection circuit. As a result, the magnitude of the angular velocity is measured.

That is, the first capacitor formed between the movable electrodes 46a to 46c (47a to 47c) of the inner structure 200 and the first fixed electrodes 48a, 48c, 48e (49a, 49c, 49e). Of the movable electrodes 46a to 46c (47a to 47c) and the second
Fixed electrodes 48b, 48d, 48f (49b, 49d,
49f), a voltage is applied so as to equalize the distance between the opposed electrodes of the second capacitor formed, and the magnitude of the applied voltage is measured to detect the angular velocity.

More specifically, the movable electrodes 46a-4a in FIG.
6c (47a-47c) are fixed electrodes 48a, 48 on both sides.
c, 48e (49a, 49c, 49e) and 48b, 48
d, 48f (49b, 49d, 49f), and the capacitances C1, C2 between the movable electrode and the fixed electrode are equal. When no angular velocity occurs, V1 = V2
The movable electrodes 46a to 46c (47a to 47c) are fixed electrodes 48a, 48c, 48e (49a, 49c, 4).
9e) and 48b, 48d, 48f (49b, 49d, 4
9f) with the same electrostatic force. From this state, the movable electrodes 46a to 46c (47
When a to 47c) are displaced, the distance between the movable electrode and the fixed electrode changes, and the capacitances C1 and C2 become unequal.
For example, the movable electrodes 46a to 46c (47a to 47c) are fixed electrodes 48a, 48c, 48e (49a, 49c, 4).
If it is displaced to the 9e) side, the voltage V1 decreases and the voltage V2 increases.

At this time, the applied voltage between the fixed electrodes 48a to 48f, 49a to 49f and the movable electrodes 46a to 46c, 47a to 47c in FIG. 2 is controlled so that the electrostatic force becomes equal. That is, the fixed electrode 48 is adjusted by adjusting the electrostatic force.
b, 48d, 48f (49b, 49d, 49f) are returned to the midpoint position. That is, the movable electrodes 46a to 46c
(47a-47c) return to the center position and the capacitances C1, C
2 are equal, the angular velocity and the electrostatic force are equally balanced. At this time, the fixed electrodes 48a to 48f, 4 in FIG.
9a to 49f and movable electrodes 46a to 46c, 47a to 47
The magnitude of the angular velocity can be obtained from the applied voltage between the two.

Thus, the servo mechanism (servo control)
Is adopted, the displacement of the structure due to the action of the angular velocity can be minimized, so that the reliability of the sensor can be improved.

Next, a method of manufacturing the vibration type angular velocity sensor according to the present embodiment will be described. 6 and 7 respectively show FIG.
13 is a cross-sectional view of the manufacturing process taken along the line AA in FIG. First, as shown in FIG. 6A, a silicon substrate (wafer) 1 having a plane orientation (100) is prepared. Then, an insulating film (SiO ₂ film) 71 is formed on the surface by thermal oxidation. The insulating film 71 is patterned to open a predetermined region and the insulating film 7 is formed.
Using 1 as a mask, an insulator filling trench 72 is formed at a predetermined position by anisotropic etching. This insulator filling trench groove 72 is formed in a through hole 4 shown in FIG.
It becomes 0. Note that an insulating film (S
Instead of forming the (iO ₂ film) 71, the trench 72 for filling the insulator may be formed at a similar position by using a direct mask.

Further, as shown in FIG.
An insulating film (SiO ₂ film) 2 is formed on the surface of the substrate and the trench 72 for filling the insulator is filled. The insulating film 2 filled in the trench 72 corresponds to the insulator 16 in the structure shown in FIG.
(20, 30, 50a to 50f, 51a to 51f, 5
7, 58).

Here, in the case where irregularities on the surface become a problem, the insulating film 2 is formed to have a thickness greater than the required thickness, and the surface is polished. Subsequently, as shown in FIG. 6C, the insulating film 2 is patterned to remove the insulating film 2 in a predetermined through-hole forming region P1. That is, the insulating film 2 in a predetermined region is removed so that through-holes (such as the through-holes 5 and 39 in FIG. 3A) can be formed by subsequent Si etching. Further, as shown in FIG. 7A, a metal wiring 73 of Al, Ti, or the like is formed on the insulating film 2 by sputtering or electron beam evaporation.
To form

Then, as shown in FIG.
An insulating film (SiO ₂ film) 74 is formed on the entire back surface of the substrate. Further, the insulating film 74 is patterned to open a predetermined region on the back surface. Then, using the insulating film 74 as a mask, the silicon substrate 1 is anisotropically etched to form the concave portion 3 reaching the insulator filling trench groove 72. The bottom surface of the recess 3 becomes the thin portion 4. At this time, it is important to protect the surface with wax, resin, or the like in order to avoid damage.

Further, the protection of the surface of the substrate 1 is removed. Thereafter, as shown in FIG. 3A, a predetermined region in the thin portion 4 of the substrate 1 is removed from the surface of the substrate 1 by anisotropic etching to remove the through-hole 5 (and 36 to 36 in FIG. 2).
39) is formed. As a result, the outer-side and inner-side structures 100 and 200 are sectioned.

Thus, the present structure is completed. The vibration type angular velocity sensor manufactured as described above has the following features.

In general, when servo control is used for the inner structure (acceleration sensor element) 200, there are merits such as improvement in linearity of a signal and an increase in a dynamic range. In the conventional angular velocity sensor shown in FIGS. 11 and 12, since the acceleration sensor element 307 is not provided with two sets of fixed electrodes alternately with respect to the movable electrode as in this example (for example, as compared to 46a in FIG. 2). 48a and 48b), when servo is applied, a rotational torque is generated in the acceleration sensor element (structure having a beam) 307, which causes a deterioration in resolution.
In the conventional angular velocity sensors shown in FIGS. 11 and 12, the movable part of the acceleration sensor element 307 is made by surface micromachining. That is, the upper layer S
The acceleration sensor element 307 is formed by penetrating the i-layer 303 and etching away the sacrificial layer 302 thereunder. Therefore, it is very difficult in process to arrange the two sets of fixed electrodes 310 and 311 alternately. In order to realize this, a process as described in Japanese Patent Application Laid-Open No. 9-211022 can be performed, but the process is complicated.

On the other hand, in the present embodiment, the driving electrodes (comb teeth) 9, 10, 13, 14 and the beam 8a shown in FIGS.
To 8d and detection electrodes (comb teeth) 46a to 46c, 47a
To 47c, 48a to 48f, 49a to 49f and beam 4
3, 44 are formed by penetrating the same substrate, and insulators (through holes) 16, 20, 30,
The 50a to 50f, 51a to 51f, 57 and 58 are formed using the trench isolation by the trench 72 of FIG. 6, and two sets of fixed electrodes 48a and 48 are formed by a simple process.
c, 48e, 49a, 49c, 49e and 48b, 48
d, 48f, 49b, 49d, and 49f can be arranged alternately. In addition, by arranging them at the same distance, when servo is applied to the inner-side structure 200, a rotational torque is hardly generated, and deterioration of resolution can be avoided.

Further, in the conventional device, as shown by t1 in FIG. 12, the electrode thickness can be secured only by the thickness of the upper Si layer 303 (for example, 10 μm). Can have a thickness of 50 to 100 μm. Therefore, the electrodes (comb teeth) 46a to 46c, 47a to 4
7c, 48a to 48f, and 49a to 49f have large electrode plate areas, so that the signal becomes large, which also causes the resolution to be improved. Further, the inner-side structure 20
The thickness of 0 can be made thicker than the apparatus of FIGS. 11 and 12, and the weight of the weight is increased to increase the signal. This can also improve the resolution.

As described above, the present embodiment has the following features. (A) Beam 8a formed by through hole 5 formed in silicon substrate 1
8d, the outer side structure 100 having the through-holes 36-
39, the inner side structure 20 having the beams 43 and 44
0, and the angular velocity detection fixed electrodes 48a to 48f and 49a to 49f of the outer structure 100 and the angular velocity detection movable electrode 46a of the inner structure 200.
To 46c and 47a to 47c are connected to the outer side structure 100.
Insulators 50a-50f, 51a-
51f, 57, and 58 electrically separated.

Thus, the through-holes 5, 36 to 39 formed in the silicon substrate 1 form the outer and inner structures 100, 200, and the fixed and movable electrodes 46a to 46c, 47a to 47c for detecting the angular velocity. 47
c, 48a to 48f and 49a to 49f are electrically separated. As a result, the thickness of the inner structure 200 is reduced to 50
Since the thickness can be increased to about 100 μm, the mass of the belt-like portion 45 as a weight can be increased, and the output signal can be increased. The inner and outer structures 10
Since the thickness of 0,200 can be increased to about 50 to 100 μm, the area of the counter electrode can be increased and the output signal can be increased.

The insulators 50a to 50f, 51a to 51f, 5 in the through holes formed in the outer structure 100
7, 58, the fixed electrode for detecting the angular velocity and the movable electrodes 46a to 46c, 47a to 4
7c, 48a to 48f, and 49a to 49f are electrically separated, so that the fixed electrode and the movable electrode for detecting angular velocity can be freely insulated from each other. That is, the insulators 50a to 50f, 51a to 51f, 57,
By using 58, the comb-shaped electrodes and the like can be insulated in a free layout. (B) As a more detailed electrode separation structure, movable electrodes 46a to 46c for detecting angular velocity of the inner side structure 200,
47a to 47c are comb-shaped, and the outer side structure 10
0 angular velocity detecting fixed electrodes 48a to 48f, 49a to 4
9f is a comb-shaped and movable electrode 4 for detecting angular velocity.
6a-46c, 47a-47c, and
Electrodes 48a, 48c, 48e, 49a, 49c, 49
e, angular velocity detecting movable electrodes 46a-46c, 47a-
47c, the second electrodes 48b, 48d,
48f, 49b, 49d, and 49f, and the first and second electrodes are connected to the outer-side structure 1
Insulators 50a to 50f, 51 in the through holes formed at 00
a to 51f, the first electrodes 4 are electrically separated.
8 a, 48 c, 48 e, 49 a, 49 c, 49 e are electrically connected by the metal wiring 52, and each second electrode 48
b, 48d, 48f, 49b, 49d, 49f were electrically connected by metal wiring 53.

Therefore, the angular velocity detecting movable electrodes 46a to 46a-4
The first and second fixed electrodes for angular velocity detection 48a to 48f, 49a to 49f are provided on both side surfaces of 6c and 47a to 47c.
Can be arranged at an equal distance. As a result, the angular velocity can be detected with higher accuracy.

In other words, in the conventional structure shown in FIGS. 11 and 12, the movable electrode (30
8, 309), it is difficult to dispose the first and second fixed electrodes for angular velocity detection 310, 311 at the same distance from both sides, and when a servo mechanism is used, the movable electrode for angular velocity detection is used. Rotational torque is generated at 308 and 309, which is likely to cause noise and lower the resolution. On the other hand, in the present embodiment, the movable electrodes 46a to 46
The first and second fixed electrodes for angular velocity detection 48a to 48f, 49a to 49f can be arranged at equal distances to both side surfaces of the first and second side surfaces c and 47a to 47c. It can hardly occur. (C) The fixed electrodes 13 and 14 for excitation shown in FIG. 1 have a comb-like shape, and contact holes 23a to 23e and 24a to 24e for electrically connecting to the metal wirings 17 and 21 are fixed to the comb-like fixed electrodes. Since a large number of the teeth 13 and 14 are formed at equal distances in the direction in which the teeth are juxtaposed, the respective comb teeth have the same potential and the excitation direction is unlikely to be inclined. (D) The movable electrode 10 for excitation shown in FIG. 2 has a comb-like shape, and contact holes 33a to 33e for electrically connecting to the metal wiring 34 are provided in parallel with each tooth of the comb-like movable electrode 10. Since many are formed at equal distances in the direction, the respective comb teeth have the same potential, and the excitation direction is unlikely to be inclined. (E) As shown in FIG. 5, the metal wiring (34) from the outer-side structure 100 is extended on the beams 8a to 8d in the outer-side structure 100, so that wiring is performed without using wire bonding. This is practically preferable. (F) As shown in FIG. 1, a first comb-shaped excitation movable electrode 9 is arranged on one side of an outer-side structure body 7 having two parallel sides as a planar shape, and the outer side. On the other side of the side structure body 7 parallel to the side, the second movable electrode 10 for excitation, which is electrically connected to the first movable electrode 9 for excitation and forms a comb shape, is further arranged.
Since the movable electrode 10 is connected to the metal wiring 21, the excitation direction is unlikely to be inclined. (G) As a method of manufacturing the angular velocity sensor, as shown in FIG. 6A, a trench groove 72 for filling an insulator is formed in a predetermined region on the surface of the silicon substrate 1, and as shown in FIG.
An insulating film 2 is deposited on the surface of the silicon substrate 1, and the insulating filling trench 72 is filled with the insulating film 2. And FIG.
7C, the insulating film 2 is patterned to open a through-hole forming region P1 of the substrate 1, and a metal wiring 73 is formed on the insulating film 2 as shown in FIG. Further, FIG.
As shown in FIG. 3B, a recess 3 reaching the insulator filling trench groove 72 is formed by anisotropic etching from the back surface of the silicon substrate 1, and a thin portion 4 is formed on the bottom surface of the recess 3 as shown in FIG.
As shown in (a), through-holes 5, 36 to 39 are formed in the thin portion 4 of the silicon substrate 1, and the outer-side structure 100 which excites in a direction parallel to the surface of the silicon substrate 1; Excitation direction Y in the direction parallel to the surface of
The inner-side structure 200 that moves in the X direction perpendicular to.

As a result, the angular velocity sensor described in (a) can be manufactured, and furthermore, the step of etching the sacrificial layer becomes unnecessary, and the process is simplified. (H) Since the silicon substrate 1 was used as the semiconductor substrate,
It will be preferable.

Hereinafter, an application example of the present embodiment will be described. Two such vibrators (two sets) may be connected and vibrated in opposite phases. By taking the difference between the outputs of the two vibrators, the disturbance acceleration can be filtered out. In this case, it is possible to measure the acceleration by taking the sum of the outputs (acceleration sensor elements) of the inner-side structure, and it is also possible to configure a sensor that simultaneously measures the acceleration and the angular velocity by signal processing. (Second Embodiment) Next, a second embodiment will be described with reference to the first embodiment.
The following description focuses on the differences from this embodiment.

FIG. 8 is a cross-sectional view of the vibration type angular velocity sensor according to the present embodiment, which replaces FIG. The plane structure is shown in Fig. 1,
Same as 2. The operation as the angular velocity sensor is the same as in the first embodiment, and a description of the operation will be omitted.

The vibration type angular velocity sensor according to the present embodiment is different from the first embodiment in that the substrate is SOI (Sil).
icon on Insulator) The main difference is that a substrate 83 is used. That is, as shown in FIG. 8A, a substrate in which a silicon layer 82 is formed on a silicon substrate 80 via an insulating film (SiO ₂ film) 81 is used. And
The back surface of the substrate 83 in the outer-side structure 100 is covered with the insulating film 81.

Next, a method of manufacturing the vibration type angular velocity sensor according to the present embodiment will be described. 9 (a), 9 (b),
(C) and FIGS. 10 (a) and (b) show the manufacturing process in the AA cross section of FIG.

First, as shown in FIG. 9A, an SOI substrate (wafer) 83 having a plane orientation (100) is prepared. Then, an insulating film (SiO ₂ film) 71 is formed on the surface by thermal oxidation.
Is formed. After opening a predetermined position of the film 71, a trench groove 72 for filling an insulator is dug at a predetermined position by anisotropic etching using the film as a mask. At this time, SiO ₂
The etching is terminated when the film 81 is exposed.

Note that, without forming the insulating film 71 on the surface, the trench 7 for filling the insulator is directly formed at the same position by using a mask.
You may dig 2. Then, as shown in FIG.
An insulating film (SiO ₂ film) 2 is formed on the surface of the substrate 83, and the trench 72 for filling the insulator is filled. Here, in the case where irregularities on the surface become a problem, the insulating film 2 is formed to have a required film thickness or more, and the surface is polished.

Further, as shown in FIG. 9C, a predetermined through-hole forming position P1 of the insulating film 2 is removed and an opening is formed.
Then, as shown in FIG. 10A, a metal wiring 73 of Al, Ti, or the like is formed on the insulating film 2 by sputtering, electron beam evaporation, or the like.

Subsequently, as shown in FIG. 10B, an insulating film (SiO ₂ film) 74 is formed on the entire back surface of the substrate and patterned. Then, the concave portion 3 is formed in a predetermined region on the back surface by anisotropic etching. At this time, the insulating film (Si
The etching is terminated when the O ₂ film 81 is exposed. At this time, it is important to protect the surface with wax, resin, or the like in order to avoid damage.

Further, as shown in FIG. 8 (a), after removing the surface-protected one, through holes (5, 39, etc.) are formed at predetermined positions from the surface by anisotropic etching to form the outer side and the outer side. The inner components 100 and 200 are formed. As a result, the present structure is completed.

In this embodiment, since the structure is formed by the SOI substrate 83, if the etching is terminated when the silicon substrate (silicon layer) 80 is completely removed in the process shown in FIG. , At this point S
Since the iO ₂ film 81 is hardly etched, it is relatively easy to make the thickness of the structure constant. Further, since the back surface is covered with the insulator film 81, even if dust or the like adheres to the back surface, surface leakage is avoided.

As described above, this embodiment has the following features. (A) Since the back surface of the outer-side structure 100 is covered with the insulating film 81, no surface leakage occurs when dust or the like adheres to the back surface. (B) In other words, SOI is used as a semiconductor substrate in the manufacturing process.
When the substrate 83 is used, the back surface of the outer-side structure is covered with the insulating film 81, and surface dust does not occur when dust or the like adheres to the back surface.

[Brief description of the drawings]

FIG. 1 is a plan view of a vibration type angular velocity sensor according to a first embodiment.

FIG. 2 is an enlarged view of FIG.

FIG. 3 is a sectional view of a vibration type angular velocity sensor.

FIG. 4 is a sectional view taken along the line DD of FIG. 1;

FIG. 5 is a partially enlarged view of a vibration type angular velocity sensor.

FIG. 6 is a cross-sectional view for explaining a manufacturing process.

FIG. 7 is a cross-sectional view for explaining a manufacturing process.

FIG. 8 is a sectional view of a vibration type angular velocity sensor according to a second embodiment.

FIG. 9 is a cross-sectional view for explaining a manufacturing process.

FIG. 10 is a sectional view for explaining a manufacturing process.

FIG. 11 is a plan view of a conventional vibration type angular velocity sensor.

FIG. 12 is a sectional view taken along line EE of FIG. 12;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Silicon substrate, 2 ... Insulating film, 3 ... Depression, 4 ... Thin part, 5 ... Through-hole, 7 ... Body part, 8a, 8b, 8c, 8d
... beams, 9 ... first movable electrode, 10 ... second movable electrode, 1
3: fixed electrode, 14: fixed electrode, 17: metal wiring, 21
... metal wiring, 23a to 23e ... contact holes, 24
a to 24e: contact holes, 33a to 33e: contact holes, 34: metal wiring, 36 to 39: through holes,
43 beam, 44 beam, 46a-46c movable electrode for detecting angular velocity, 47a-47c movable electrode for detecting angular velocity, 48
a to 48f: fixed electrodes for detecting angular velocity, 49a to 49f ...
Fixed electrodes for angular velocity detection, 50a to 50f ... insulator, 51
a to 51f: insulator, 52: metal wiring, 53: metal wiring, 57: insulator, 58: insulator, 72: trench groove for filling insulator, 73: metal wiring, 81: insulating film, 83: S
OI substrate, 100: outer structure, 200: inner structure

Claims (10)

[Claims] An outer-side structure having beams and exciting in a direction parallel to the surface of the semiconductor substrate is partitioned by a through-hole formed in the semiconductor substrate, and a through-hole formed in the outer-side structure defines An inner-side structure that has a beam and moves in a direction parallel to the surface of the semiconductor substrate in a direction parallel to the surface of the semiconductor substrate by angular velocity, and that further moves, and further includes a fixed electrode for detecting angular velocity of the outer-side structure and the fixed electrode; An angular velocity sensor characterized in that the movable electrode for detecting the angular velocity of the inner structure facing the inner structure is electrically separated by an insulator in a through hole formed in the outer structure. 2. The movable electrode for detecting angular velocity of the inner-side structure has a comb-like shape, and the fixed electrode for detecting angular velocity of the outer-side structure has a comb-like shape. It comprises a first electrode facing one side surface and a second electrode facing the other side surface of the movable electrode for detecting angular velocity, and the first and second electrodes are formed on the outer-side structure. 2. The angular velocity sensor according to claim 1, wherein each of the first electrodes is electrically connected by a metal wiring, and each of the second electrodes is electrically connected by a metal wiring. . 3. A fixed electrode for excitation has a comb-like shape, and contact holes for electrical connection with metal wiring are equidistant in a direction in which the teeth of the comb-like fixed electrode are arranged side by side. The angular velocity sensor according to claim 1, wherein a plurality of angular velocity sensors are formed. 4. A movable electrode for excitation has a comb-like shape, and contact holes for electrically connecting to a metal wiring are equidistant in a direction in which the teeth of the comb-like movable electrode are arranged side by side. The angular velocity sensor according to claim 1, wherein a plurality of angular velocity sensors are formed. 5. The angular velocity sensor according to claim 1, wherein a metal wiring from the outer-side structure extends on a beam in the outer-side structure. 6. A comb-shaped first movable electrode for excitation is arranged on one side of an outer-side structure body having two parallel sides as a planar shape, and the outer-side structure body in the outer-side structure body. On the other side parallel to the side, a second movable electrode for excitation, which is electrically connected to the first movable electrode for excitation and forms a comb-like shape, is arranged. The angular velocity sensor according to claim 1, wherein the angular velocity sensor is connected. 7. The angular velocity sensor according to claim 1, wherein a back surface of the outer structure is covered with an insulating film. 8. A step of forming an insulator filling trench in a predetermined region on a surface of the semiconductor substrate; and a step of depositing an insulating film on the surface of the semiconductor substrate and filling the insulator filling trench with an insulating film. Patterning the insulating film to open a through-hole forming region of the substrate; forming a metal wiring on the insulating film; and filling the insulator by anisotropic etching from the back surface of the semiconductor substrate. Forming a concave portion reaching the trench groove, forming a thin portion on the bottom surface of the concave portion, forming an through hole in the thin portion of the semiconductor substrate, and exciting the outer side structure in a direction parallel to the surface of the semiconductor substrate; Forming an inner-side structure that moves in the direction parallel to the surface of the semiconductor substrate in a direction parallel to the excitation direction by an angular velocity. 9. The method according to claim 8, wherein a silicon substrate is used as the semiconductor substrate. 10. The method according to claim 8, wherein an SOI substrate is used as the semiconductor substrate.