JP2001349731A - Micro-machine device, angular acceleration sensor, and acceleration sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To unify a bonding direction and a bonding face to facilitate wire bonding in mounting. SOLUTION: All the bonding pats in a silicon side electrode and a glass side electrode are arranged on a silicon by providing a contact part in a silicon substrate side, and by clamping a lead wire end part of the glass substrate side electrode with the contact part. Since the bonding pats connected to an external circuit are formed on an identical plane irrespective of directions of the electrodes by this countermeasure hereinfefore, the wire bonding is very simplified and contribution to cost reduction is increased in mass-production.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an angular velocity sensor and an acceleration sensor used for, for example, controlling the attitude of a vehicle, calculating a traveling direction, preventing camera shake of a hand camera, and calculating a moving direction of a mobile phone.

[0002]

2. Description of the Related Art Various gyroscopes (hereinafter, referred to as gyroscopes) have been developed as sensors for detecting angular velocity. The types can be roughly classified into mechanical gyroscopes, optical fiber gyros, fluid gas rate gyros, and vibration gyros such as tuning forks.

In recent years, in response to demands for downsizing, power saving, and cost reduction of products, development of ultra-small angular velocity sensors formed by applying micromachining micromachining technology to materials such as single crystal silicon and quartz. Is also underway. Most of the micromachined angular velocity sensors belong to the vibrating gyroscope. The principle of detection is as follows.

When the vibrating weight rotates the weight about an axis perpendicular to the vibration direction, forces in the vibration direction and the rotation axis perpendicular to each other act on the weight. The displacement of the weight in the force direction due to this force is detected, and the angular velocity is calculated therefrom. This sensor requires a driving force for exciting vibration and a mechanism for detecting displacement of the weight. When the material of the sensor is a piezoelectric body or a part provided with a piezoelectric body, a distortion generated by applying a voltage to the piezoelectric body is used for driving, and an electric charge generated by the distortion applied to the piezoelectric body is detected.

[0005] Other methods use magnetism or electrostatic force. Of these, those using piezoelectrics
When a bulk piezoelectric body is used, fine processing is difficult. For example, when a piezoelectric body is formed on silicon, the formation itself requires a great deal of labor. In the use of magnetism, the hurdles that must be overcome for practical use are high, such as the effect on peripheral circuits due to the use of magnets and the difficulty in forming highly efficient fine coils. From these meanings, the development of a type using a silicon wafer as a material and using electrostatic force for both driving and detection has reached a practical stage. The driving using the electrostatic force applies a force of attracting parallel plate electrodes storing different electric charges to each other. Therefore, it is advantageous that the total area of the electrodes is larger.

On the other hand, in a parallel plate capacitor storing a fixed charge, the amount of displacement is determined by detecting a change in inter-electrode voltage due to a change in the inter-electrode distance.
Again, the larger the total area of the electrodes on the detection side, the more advantageous. In particular, since the displacement on the detection side is much smaller (two or three digits smaller) than the displacement of the drive vibration, higher precision processing and improved detection efficiency are required. In this type of micromachine angular velocity sensor, for example, a paper published by P. Greiff et al. (Silicon monolithic micromechanical
gyroscope, Transducers'99, P966-969) and a paper (MEMS'99) published by Murata Manufacturing in recent years. An example is also described in Japanese Unexamined Patent Publication No. 5-322576 “Angular velocity sensor”.

As described above, in the vibrating micromachine gyro, it is necessary to increase the electrode area in order to increase the driving efficiency and the detection efficiency. Therefore, in order to use the entire surface of the weight as an electrode or to enhance space efficiency, a structure such as a comb shape, a ladder shape, or a fishbone is employed. In order to improve the efficiency, it is also important to reduce the distance between the electrodes as well as to increase the area of the electrodes and to carry out the processing of the configuration accuracy. In order to meet these demands, reactive ion etching (hereinafter, referred to as RIE), which is a semiconductor process and is a kind of plasma etching, is used recently. By ultrafine processing by this technique, it is possible to produce a structure made of silicon with a pitch of several microns. However, in order to realize an angular velocity sensor having a main body of several mm square, a comb-shaped electrode structure having a pitch of about 2 μm must be frequently used, and it is not easy even with this RIE technology.

As a means of avoiding difficult ultrafine processing, there is a method of arranging an insulating substrate in parallel with the vibrating body and detecting the capacitance between a metal electrode formed on the substrate and the silicon vibrating body. . In this method, there is no need to convert the entire vibrating body into a comb-shaped electrode, and the processing is relatively easy.
Sensors with this structure are also being actively developed.

[0009]

In a sensor in which an insulating substrate is disposed in parallel with a silicon vibrating body and a metal electrode formed on the substrate and an electrostatic drive between the vibrating body and capacitance detection are used, ultra-fine processing is required. Although it is escaped from,
It had to be performed from a plurality of substrates on a silicon substrate and an insulator substrate. Because wire bonding is used to take out these terminals, taking out from multiple substrates increases the number of automation steps by increasing the number of bonding steps, and it is difficult to use an SOI wafer because the bonding direction differs between substrates, and a conversion connector is required. From restrictions such as
It had been a matter of mass production.

In view of the above problems, the present invention realizes bonding between a single direction and a single step, and realizes automation and
It is an object of the present invention to provide a method for taking out a terminal which can be easily mass-produced.

[0011]

According to a first aspect of the present invention, there is provided an insulator substrate having a metal thin film pattern, and one side of the insulating layer is an active layer showing conductivity and the other is insulating or high resistivity. Having a composite substrate composed of a support layer showing
In a micromachine device having a bonding surface in which a structure is formed in the active layer and a part of the insulating substrate and a part of the active layer are bonded, one of the metal thin film patterns formed on the bonding surface A contact portion depressed shallower than the thickness of the metal thin film pattern at a position on the active layer portion corresponding to the portion, and in a state where the insulator substrate and the active layer are joined, A part of the metal thin film pattern formed on the surface and the contact portion,
It is characterized by being electrically connected.

According to a second aspect of the present invention, in the micro machine device according to the first aspect, a groove is provided around the contact portion corresponding to the metal thin film pattern.

According to a third aspect of the present invention, in the micro machine device according to the first or second aspect, the metal thin film pattern is an electrode, and a part of the metal electrode formed on the bonding surface is electrically connected to the metal thin film pattern. A part of the active layer that is electrically bonded is an island-shaped part having a bonding pad and electrically insulated from the other part of the active layer, and the metal electrode on the insulator substrate and the outside are Is performed via the bonding pad provided on the island-shaped portion.

According to a fourth aspect of the present invention, in the micro machine device according to the first or second aspect, the metal thin film pattern formed on the insulating substrate is a bonding pad and a lead wire connected to the bonding pad. A part of the structure formed in the active layer is electrically connected to the lead wire portion on the bonding surface, and an electrical connection between the structure and the outside is formed by the metal thin film. It is performed through the bonding pad formed by a pattern.

The invention of claim 5 of the present application is directed to claims 1 to 4
In the micromachine device according to any of the above,
The active layer and the support layer are made of silicon, and the insulating layer between the active layer and the support layer uses SOI composed of SiO ₂ .

The invention of claim 6 of the present application is directed to claims 1 to 5
In the micromachine device according to any of the above,
It is characterized in that the insulator substrate is constituted by a glass substrate.

The invention of claim 7 of the present application is directed to claims 1 to 5
In the micromachine device according to any of the above,
It is characterized in that the insulator substrate is constituted by a silicon substrate having a SiO ₂ layer on the surface.

According to an eighth aspect of the present invention, in the micro machine device according to the sixth or seventh aspect, the junction between the insulator substrate and the active layer is an anodic junction.

The invention of claim 9 of the present application is directed to claims 1 to 8
Wherein the micromachine device is an angular velocity sensor.

According to a tenth aspect of the present invention, the micromachine device according to any one of the first to eighth aspects is an acceleration sensor.

[0021]

(Embodiment 1) An angular velocity sensor comprising a single crystal silicon SOI wafer and glass according to Embodiment 1 of the present invention will be described with reference to FIG. FIG. 1 is an exploded perspective view of the angular velocity sensor according to the first embodiment.

The sensors are an SOI substrate 101 and a glass substrate 1
Consists of twenty. The SOI substrate 101 has a three-layer structure including an active layer 102 having high conductivity, a support layer 104 having low conductivity, and an insulating layer 103 interposed between the active layer 102 and the support layer 104 to insulate them. The insulating layer 103 is made of SiO ₂ . A vibrating body 110 is formed at the center of the active layer 102 by RIE, which is a type of plasma etching. A weight 105 for detecting the angular velocity is provided at the center of the vibrating body 110, and driving electrodes 107 and 108 for driving the vibrating body 110 are arranged around the weight 105.

The driving electrode is divided into a left side portion 107 and a right side portion 108, each of which has a structure with a slit open. Weight 105 is four thin cantilevered detection beams 1
The weight 105 is supported only by the drive electrodes 107 and 108 via the reference numeral 06, and has a degree of freedom only in the substrate thickness direction. Further, the drive electrodes 107 and 108 have a beam-shaped support at both ends.
Supported by the frame 117 via the drive beam 109 of the book,
It has a degree of freedom only in the horizontal direction of the vibrating body.

The frame 11 is provided outside the driving beam 109.
7 are electrically insulated from the monitor electrode 111,
A parallel plate capacitor having a counter electrode near the center of the drive beam 109 is formed. The active layer 102 has a frame 1
An island 113 having a bonding pad 116 is formed so as to be electrically insulated from the bonding pad 17. This island 11
3 has a contact portion 114 which is recessed by etching from the upper surface of the frame 117, and a groove portion 115 which is further deeply etched around the contact portion 114.

A glass substrate 120, which is an insulating substrate, is disposed above the active layer 102 (the side opposite to the support layer 104), and corresponds to the Si-side bonding surface 112 which is a part of the Si-side frame 117. The glass-side bonding surface 125 is firmly fixed by anodic bonding. Anodic bonding is a technique in which clean and flat surfaces of a glass substrate and a Si substrate are brought into contact with each other, and a high voltage is applied at a high temperature to generate and fix an electrostatic force between the contact surfaces.

On the inside of the glass-side bonding surface 125, a gap portion 126 which is depressed by etching is formed, and on the bottom surface of the gap portion 126, an electrode pattern made of a metal thin film is formed. A detection electrode 123 is disposed at the center of the electrode pattern so as to face the weight 105, and glass-side drive electrodes 121 and 122 are disposed around the detection electrode 123. The glass-side drive electrodes 121 and 122 are a left-side drive electrode 107 and a right-side drive electrode 10 on the Si side, respectively.
8 is supported. A lead wire portion 124 is drawn out from the glass-side electrode pattern to the glass-side joint surface 125, and is electrically connected to the Si-side contact portion.

Here, the detailed structure of the contact portion 114 will be described with reference to FIG. Island portion 113 on Si substrate side
The contact portion 114 arranged at the center is etched lower by t2 than the bonding surface 112. Here, assuming that the thickness of the lead wire portion 124 of the metal thin film on the glass substrate 120 is t1, t1 and t2 are determined so that the relationship of t1> t2 is satisfied. At this time, t1-t
2 and a pressing margin occurs, and the bonding surface 125 on the glass side and S
There will be a gap between the i-side bonding surfaces 112,
Since the anodic bonding is performed at a high temperature, the glass is slightly softened, so that a slope is generated around the lead wire portion 124,
The joining surfaces 112 and 125 are normally joined. By setting the width of the groove 115 within the width of the groove 115 around the contact portion 114 so that the slope width can be accommodated, a wedge-shaped gap can be prevented from being generated between the joint surfaces 112 and 125, and the strength of the joint surface can be reduced. Can be improved.

Thus, the lead wire portion 1 of the electrode on the glass side
Since the bonding pad 116 on the same silicon substrate can be arranged regardless of the electrode direction by sandwiching the bonding layer 24 between the bonding surfaces 112 and 125, wire bonding can be performed very easily, which greatly contributes to cost reduction in mass production.

Next, the operation of the angular velocity sensor according to the first embodiment will be described. The active layer 102 includes, for example, S
Conductivity is imparted by doping an element such as b or As, and the potential is set to GND. Circuit side (not shown)
Is connected by wire bonding via a bonding pad 116 formed on the frame 117.

Further, the driving electrodes 121 and 122 on the glass side are used.
Include a bonding pad 116 and a contact portion 114
, The amplitude V applied with the bias voltage Vb
a, an AC voltage having a frequency f is applied. The relationship between the bias voltage Vb of the AC voltage and the AC amplitude Va has a relationship of Vb> Va, and when the drive signal applied to the drive electrode 121 is Vb + Va · Sin (2πft), the drive electrode 12
2 is Vb−Va · Sin (2πf
t).

Therefore, between the drive electrodes 121-107,
Since the electrostatic force acting between the driving electrodes 122 to 108 becomes an oscillating attractive force having a phase difference of 180 °, the vibrating body 11
0 vibrates in the direction of 130 in FIG. At this time, when a rotational motion about the direction 131 is applied to the vibrating body 110, 1
Coriolis force is generated in the direction of 32. The driving beam 109 is 1
The detection beam 106 which is soft in the direction of 30 but is hard in the direction of 132 is deformed in the direction of 132, and only the weight 105 moves in the direction of 132 in the vibrating body 110. Then, since the capacitance of the flat plate capacitor constituted by the weight 105 and the detection electrode 123 changes, the change in the capacitance is detected by a CV conversion circuit (not shown), and the Coriolis force is calculated. Detect the added rotation speed. At this time, the signal of the monitor electrode 111 is used to control the driving vibration of the vibrating body 110 in the 130 direction.
The principle by which the monitor electrode 111 detects the vibration of the vibrating body 110 is also an electrostatic method, similar to the detection of the movement amount of the weight 105 by the detection electrode 123.

(Embodiment 2) An angular velocity sensor made of single crystal silicon and glass according to Embodiment 2 of the present invention will be described with reference to FIG. The SOI substrate 101 is structurally similar to the angular velocity sensor of the first embodiment shown in FIG.
And the glass substrate 120 are anodically bonded at the bonding surfaces 112 and 125. Further, a vibrator 1 including a weight 105, a detection beam 106, drive electrodes 107 and 108, and a drive beam 109 is provided on the active layer 102 of the SOI substrate 101.
10 is formed in the same manner as in the first embodiment shown in FIG. 1, and a monitor electrode 111 is also formed beside the driving beam 109.

The glass substrate 120 bonded to the SOI substrate 101 is etched with a gap 126 in the same manner as in the first embodiment, and the bottom surface of the gap 126 is formed in the same manner as in the first embodiment. Electrode pattern 127
Is configured. The second embodiment is different from the first embodiment in that a bonding pad for extracting a terminal is provided on the glass substrate side. Lead wire portion 1 extending from electrode pattern 127 formed on the bottom surface of gap portion 126
24 is drawn out to the same plane as the bonding surface 125, and a bonding pad 302 is formed at an end.

On the active layer 102 side, the lead wire 12
An escape portion 309 is provided so that 4 does not contact the active layer 102. A bonding pad 30 for connecting the potential of the frame 117 to GND is provided on the glass substrate 120.
1 and the lead portion 303 following it and the monitor electrode 11
A bonding pad 304 for extracting one signal and a lead wire portion 305 are also formed. When the SOI substrate 101 and the glass substrate 120 are anodically bonded, the lead wire portions 303,
305 is a contact portion 30 provided on the active layer 102
8, 306 respectively.

The connection between the contact portion 306 and the lead wire portion 305 will be described with reference to FIG. A groove is provided around contact portion 306 as described in the first embodiment, and the slope generated in the glass substrate is absorbed by the width of the groove, and strong anodic bonding is realized. The relationship between the depth of the recess of the contact portion 306 and the thickness of the lead wire portion 305 is as follows.
This is the same as the relationship in FIG. 2 described in the first embodiment.

As described above, since the active layer 102 has conductivity, the monitor electrode 111 must be insulated from other active layer portions. Therefore, an escape portion 307 is provided so that the monitor electrode 111 does not come into contact with another portion of the active layer 102 via the lead wire portion 305, and the monitor electrode 111 is provided.
Insulation is ensured.

Although no groove is provided around the contact portion 308 in FIG. 3, this is because a large bonding area of the frame 117 can be obtained. Of course, the reliability can be further improved by providing the groove. I can do it.

As described above, the entire bonding pad group can be arranged not only on the active layer 102 but also on the glass substrate 120.
Since the bonding pads 116 on the same silicon substrate can be arranged irrespective of the electrode direction, wire bonding can be performed very easily, greatly contributing to cost reduction in mass production.

The movement of the angular velocity sensor according to the second embodiment is exactly the same as the movement of the vibrating body 110 and the method of applying a voltage to the drive electrode, and therefore the description is omitted.

(Embodiment 3) An acceleration sensor made of single crystal silicon and glass according to Embodiment 3 of the present invention will be described with reference to FIG. The configuration of the acceleration sensor is
Basically, the angular velocity sensor according to the first embodiment has a shape excluding a drive electrode and a drive beam.

The active layer 102 of the SOI substrate 101 has conductivity, a weight 401 is formed at the center, and the weight 401 is supported by the frame 117 via four thin detecting beams 402 from the periphery. On the frame 117, the GND of the circuit
A bonding pad 405 is provided for connection to the terminal. The island portion 113 has its periphery insulated from the frame 117 by etching, has a bonding pad 116 and a contact portion 114, and has a groove 115 around the contact portion 114. The glass substrate 120 facing the SOI substrate 101 has a gap 126, and a detection electrode 403 made of a metal film is provided on the bottom of the gap 126. A lead wire portion 404 is drawn out from the detection electrode 403, and its end is placed on the joint surface 125.

The SOI substrate 101 and the glass substrate 120 are anodically bonded at bonding surfaces 112 and 125, and a lead wire portion 404 is provided.
Is connected to the contact portion 114. Thus, the lead wire portion 404 of the electrode on the glass side is connected to the bonding surface 11.
Since the bonding pads 116 can be arranged on the same silicon substrate irrespective of the direction of the electrodes by sandwiching them between them, the wire bonding can be performed very easily, which greatly contributes to cost reduction in mass production.

Next, the operation of the acceleration sensor according to the third embodiment will be described. Weight 401 of GND potential and detection electrode 4
03 forms a plate capacitor. When acceleration in the 501 direction is applied to the weight 401, the detection beam 402 bends and the weight 40
1 and the detection electrode 403 change, and the capacitance changes. This change in capacitance is detected by an external circuit (not shown) via the contact portion 114 bonded to the detection electrode 403 and the bonding pad 116.

In the third embodiment, the bonding pad is provided on the active layer 102. However, as described in the second embodiment, the same effect can be obtained by providing the bonding pad on the glass substrate.

[0045]

As described above, according to the present invention, in a vibration type angular velocity sensor and an acceleration sensor, a bonding pad for connecting to an external circuit is formed on the same plane irrespective of the direction of an effective surface for electrode driving. As a result, wire bonding can be performed very easily, which greatly contributes to cost reduction in mass production.

[Brief description of the drawings]

FIG. 1 is a perspective view of an angular velocity sensor according to a first embodiment.

FIG. 2 is an enlarged sectional view of a lead wire portion of the angular velocity sensor according to the first embodiment.

FIG. 3 is a perspective view of an angular velocity sensor according to a second embodiment.

FIG. 4 is an enlarged sectional view of a lead wire portion of the angular velocity sensor according to the second embodiment.

FIG. 5 is a perspective view of an acceleration sensor according to a third embodiment.

DESCRIPTION OF SYMBOLS 101 SOI substrate 102 Active layer 103 Insulating layer (SiO ₂ layer) 104 Support layer 105 Weight 106 Detecting beam 107 Left driving electrode 108 Right driving electrode 109 Driving beam 110 Vibrator 111 Monitor electrode 112 Joint surface (Silicon side) 113 island-shaped part 114 contact part 115 groove part 116 bonding pad 117 frame 120 glass substrate 121 glass-side drive electrode (right side) 122 glass-side drive electrode (left side) 123 detection electrode 124 lead wire part 125 bonding surface (glass substrate side) 126 Gap part 301, 302, 304 Bonding pad 303, 305 Lead wire part 307, 309 Escape part 306, 308 Contact part 401 Weight 402 Detection beam 403 Detection electrode 404 Lead wire part 405 Bonding pad 501 Acceleration direction

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2F105 AA02 AA08 AA10 BB15 CC04 CD03 CD05 CD13 4M112 AA02 BA07 CA24 CA26 CA31 CA33 DA03 DA18 EA03 EA13

Claims (10)

[Claims] 1. A composite comprising an insulator substrate having a metal thin film pattern, a conductive active layer, an insulating or high resistivity support layer, and an insulating layer sandwiched between the active layer and the support layer. A micromachine device comprising a substrate, and having a bonding surface in which a part of the insulating substrate and a part of the active layer are bonded to the active layer having a structure formed thereon.
At a position on the active layer portion corresponding to a part of the metal thin film pattern formed on the bonding surface, a contact portion that is recessed shallower than the thickness of the metal thin film pattern is provided. A micromachine device, wherein a part of the metal thin film pattern formed on the bonding surface and the contact portion are electrically connected in a state where the active layer is bonded. 2. A composite comprising an insulator substrate having a metal thin film pattern, a conductive active layer, an insulating or high specific resistance support layer, and the active layer and an insulating layer sandwiched between the support layers. A micromachine device comprising a substrate, and having a bonding surface in which a part of the insulating substrate and a part of the active layer are bonded to the active layer having a structure formed thereon.
In the state where the contact portion is provided at a position on the active layer portion corresponding to a part of the metal thin film pattern formed on the joining surface, and the insulator substrate and the active layer are joined, In a micromachine device in which a part of the metal thin film pattern formed on the bonding surface and the contact portion are electrically connected, a groove is provided around the contact portion corresponding to the metal thin film pattern. A micromachine device. 3. The method according to claim 1, wherein the metal thin film pattern is an electrode, and a part of the active layer electrically connected to a part of the metal electrode formed on the bonding surface has a bonding pad. An island portion insulated from other portions of the active layer, and the connection between the metal electrode on the insulator substrate and the outside is performed via the bonding pad provided on the island portion. The micromachine device according to claim 1, wherein: 4. The method according to claim 1, wherein the metal thin film pattern formed on the insulating substrate forms a bonding pad and a lead wire portion connected to the bonding pad, and a part of the structure formed on the active layer is bonded to the bonding layer. 2. The structure according to claim 1, wherein the structure is electrically connected to the lead wire portion, and the structure is electrically connected to the outside via the bonding pad formed of the metal thin film pattern. Or the micromachine device according to 2. 5. The semiconductor device according to claim 1, wherein the active layer and the support layer are made of silicon, and the insulating layer between the active layer and the support layer is made of SOI made of Si02. Micromachine device. 6. The micromachine device according to claim 1, wherein the insulator substrate is formed of a glass substrate. 7. The micromachine device according to claim 1, wherein the insulator substrate is constituted by a silicon substrate having a SiO 2 layer on a surface. 8. The micromachine device according to claim 6, wherein the bonding between the insulator substrate and the active layer is anodic bonding. 9. An angular velocity sensor, wherein the micromachine device according to claim 1 is an angular velocity sensor. 10. An acceleration sensor, wherein the micromachine device according to claim 1 is an acceleration sensor.