JP3296158B2 - Piezoelectric thin film vibrator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric thin film vibrator using a semiconductor crystal substrate or the like, which is used for, for example, an acceleration sensor or an angular velocity sensor.

[0002]

2. Description of the Related Art For example, a piezoelectric thin film vibrator using a semiconductor crystal substrate is used as a piezoelectric thin film vibrator used for an acceleration sensor, an angular velocity sensor or the like. FIG. 4 shows an example of the piezoelectric thin film vibrator. It is shown. FIG. 4 shows the one described in Japanese Patent Application Laid-Open No. 1-71208. FIG. 4A is a plan view of the piezoelectric thin film vibrator, and FIG. 2) is a sectional view taken along line AA. In these figures, a thin oxide film 2 as a first insulating film is formed on a semiconductor crystal substrate 1.
A void 8 is formed between the two ends of the oxide film 2 at the center between the oxide film 2 and the substrate 1, thereby forming a diaphragm formation region floating above the oxide film 2 from the substrate 1. The upper side of the diaphragm forming region of the oxide film 2, that is,
A lower electrode 3 is formed at a position corresponding to the gap 8, and a lead electrode 13 and a lower electrode connection pad (connection pad) 4 are formed in this order on one end side (right side in the figure) of the substrate 1. The lower electrode connection pad 4 is a lead electrode 13
And is electrically connected to the lower electrode 3 via the.

A piezoelectric thin film 5 is formed on the upper side of the lower electrode 3 so as to cover the left end side of the figure from the center of the oxide film 2. A facing upper electrode 6 is formed, and an upper electrode connection pad (connection pad) 7 is connected to the upper electrode 6 via a lead-out electrode 16.
Are electrically connected. The piezoelectric thin film vibrator has an oxide film 12 having contact holes 9a and 9b formed on the upper side of a region where the upper electrode connection pad 7 and the lower electrode connection pad 4 are formed (not shown in FIG. ) Is formed,
Almost the entire area on the upper side of the piezoelectric thin film 5 and the oxide film 2 excluding the formation areas of the contact holes 9a and 9b is covered with the oxide film 12. Note that the oxide film 12 functions as a second insulating film.

[0004] Such a piezoelectric thin-film vibrator is connected between the upper electrode 6 and the lower electrode 3 by voltage applying devices (not shown) connected to the upper electrode connecting pad 7 and the lower electrode connecting pad 4 respectively. When a voltage is applied to the diaphragm, the piezoelectric thin film 5 sandwiched between the upper electrode 6 and the lower electrode 3 expands and contracts by this voltage, and the diaphragm forming region vibrates in the vertical direction in FIG.

A voltage detecting device (not shown) is connected to the upper electrode connecting pad 7 and the lower electrode connecting pad 4,
For example, if the piezoelectric thin-film vibrator is provided in a sensor or the like, an acceleration or the like is applied to the sensor or the like, whereby the diaphragm forming region vibrates, and at that time, the piezoelectric thin film 5 expands and contracts. Upper electrode 6 that changes with expansion and contraction of the piezoelectric thin film 5
If the voltage between the electrode and the lower electrode 3 is detected by the voltage detecting device, the acceleration can be detected.

However, in the piezoelectric thin-film vibrator as shown in FIG. 4, the substrate 1 functions as a virtual electrode unless the substrate resistance is infinite, and the substrate 1 is connected to the lead electrodes 13, 16 and the upper electrode connection. Since a parasitic capacitance is generated between the pad 7 and the lower electrode connection pad 4, there is a problem that the resonance characteristics are deteriorated.

On the other hand, as a means for solving such a problem, Japanese Patent Application Laid-Open No. 1-71208 proposes a piezoelectric thin film vibrator as shown in FIG. In this piezoelectric thin film vibrator, a gap 8 is formed between both ends of an oxide film 2 formed on a substrate 1.

That is, in the piezoelectric thin-film vibrator shown in FIG. 5, the sacrifice layer is etched at a position corresponding to the space 8 immediately below the upper electrode connecting pad 7, the lower electrode connecting pad 4, and the lead electrodes 13 and 16. In this manner, the gap 8 is formed not only in the formation region of the upper electrode 6 and the lower electrode 3 but also in the position corresponding to the upper electrode connection pad 7, the lower electrode connection pad 4, and the lead electrodes 13 and 16.
, The electrodes 3, 6, 13, 16 and the connection pads 4, 7 are insulated from the substrate 1 so that the electrodes 3, 6, 13, 16 and the connection pads 4, 7 and the substrate 1 To reduce the parasitic capacitance and prevent deterioration of resonance characteristics.

The piezoelectric thin-film vibrator of this type applies a voltage between the upper electrode 6 and the lower electrode 3 like the piezoelectric thin-film vibrator shown in FIG. The piezoelectric thin film 5 sandwiched between the electrodes expands and contracts, and the diaphragm forming region vibrates. If this piezoelectric thin-film vibrator is provided in a sensor or the like, the voltage between the upper electrode 6 and the lower electrode 3 that changes with the expansion and contraction of the piezoelectric thin film 5 is detected by a voltage detection device, so that the sensor output is obtained. Can be detected.

[0010]

However, in the above-described conventional piezoelectric thin-film vibrator, the extraction electrode
Since the gaps 8 are formed at positions corresponding to the portions 13 and 16 and the lower electrode connection pads 4 and the upper electrode connection pads 7, resonance characteristics can be improved, but on the other hand, the substrate 1 and the oxide film 2 can be improved. There is a problem in that the oxide film 2 corresponding to the formation region of the lower electrode connection pad 4 and the upper electrode connection pad 7 may be broken due to the stress due to the difference in thermal expansion between them.

Also, since consideration has been given to reducing the temperature coefficient of the resonance frequency, the lower electrode connection pad 4
Since the thickness of the oxide film 2 immediately below is as thin as several μm,
When wire bonding is performed and pressed to the lower side of the lower electrode connection pad 4 formation region, there is a problem that the lower electrode connection pad 4 formation region may be broken.

Further, in the above piezoelectric thin film vibrator,
Since the upper electrode connection pad 7 is formed directly on the piezoelectric thin film 5, there is also a problem that the wire bonding damages the piezoelectric thin film 5 below the upper electrode connection pad 7 formation region.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to connect electrodes by a stress due to a difference in thermal expansion between a substrate and an insulating film formed on the substrate or a stress of wire bonding. An object of the present invention is to provide a piezoelectric thin-film vibrator having excellent resonance characteristics without destruction of a pad formation region.

[0014]

Means for Solving the Problems To achieve the above object, the present invention provides means for solving the problems by the following constitution. That is, the present invention comprises a substrate, a first insulating film of the thin formed on the base <br/> board, said first
Both ends of the insulating film are laminated in close contact with the surface of the substrate
Together with the local site across the form die <br/> Afuramu formation region had floating from the substrate, a lower electrode formed on the upper surface of the 該Da diaphragm and forming region, the top surface of the lower electrode
And almost a piezoelectric thin film the whole covering area, and an upper electrode formed to face the front Symbol lower electrode on the upper surface of the piezoelectric thin film, an upper surface of the upper electrode of the upper surface of the first insulating film
And a second insulating film covering substantially the entire region of the upper surface of the piezoelectric thin film, before Symbol substrate and the first insulating film and the piezoelectric thin film and the second upper surface of the adhesion laminated portion of the insulating film Previous
A connection pad for the lower electrode formed on one end side of the second insulating film; and a second pad on an upper surface of the close-stacked portion.
A connection pad for the upper electrode formed on the other end of the insulating film, the piezoelectric thin film on one end of the second insulating film,
A second exposing the lower electrode formed on the second insulating film;
1 contact hole and the other end of the second insulating film.
Exposing the upper electrode formed on the second insulating film;
A second contact hole, and the first contact hole.
Provided to connect to the lower electrode via a tool,
Lower drawer formed on the upper surface of the second insulating film
An electrode and the upper portion via the second contact hole.
An electrode is provided for connection with an electrode, and is provided on the second insulating film.
An upper extraction electrode formed on the surface of the
The lower electrode is connected to the lower electrode connecting pad by the lower electrode.
An electrical connection via a lead electrode and the upper electrode
And the connection pad for the upper electrode are connected to the upper
It is configured to be electrically connected via a pole .

Further, the upper electrode is formed of two electrodes arranged at intervals from each other, and these two upper electrodes are provided with separate extraction electrodes and connection pads, respectively. Wherein the substrate is formed of a semiconductor crystal, a recess is formed in the substrate, and a first insulating film is formed on the surface on which the recess is formed. I have.

In the present invention having the above-described structure, the connection pad for each electrode for applying a voltage to the upper electrode and the lower electrode is a diaphragm of the second insulating film covering substantially the entire upper side of the piezoelectric thin film. They are provided separately from each other at positions avoiding the formation region, and this position is the first position on the substrate.
Since it is on the close-contact laminate of the insulating film, the piezoelectric thin film, and the second insulating film, the strength against stress is high, and the first insulating film formed through a gap as in the related art is formed on the first insulating film. Unlike the case where connection pads are formed on the connection pad, even if stress due to a difference in thermal expansion between the substrate and the first insulating film, stress due to wire bonding, or the like is applied to the connection pad formation region, Will not be destroyed.

Further, the connection pad for the lower electrode and the connection pad for the upper electrode are formed on the close-contact laminate of the first insulating film, the piezoelectric thin film, and the second insulating film on the substrate as described above. Since two insulating films are interposed between each connection pad and the substrate, the parasitic capacitance between the connection pad and the substrate is reduced by the two insulating films and almost insulated. As a result, deterioration of the resonance characteristics is prevented, and the piezoelectric thin-film vibrator having excellent resonance characteristics is obtained.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. In the description of the present embodiment, the same reference numerals are given to the same parts as those in the conventional example, and the overlapping description will be omitted. FIG. 1 shows a first embodiment of a piezoelectric thin film vibrator according to the present invention, and FIG.
2A is a plan view of the piezoelectric thin film vibrator, and FIG. 2B is a cross-sectional view taken along line AA of FIG. As shown in the figure, in this embodiment, a thin oxide film 2 is formed on a semiconductor crystal substrate 1 as in the conventional example. An air gap 8 is formed only in a local portion on the center side between the two ends of 2, and this local portion forms a diaphragm formation region.

A lower electrode 3 is formed above the diaphragm formation region of the oxide film 2, and a piezoelectric thin film 5 is formed on the upper side of the lower electrode 3 so as to cover almost the entire upper region of the oxide film 2. ing. An upper electrode 6 facing the lower electrode 3 is formed on the upper side of the piezoelectric thin film 5 in the diaphragm formation region, and an oxide film covering almost the entire upper side of the piezoelectric thin film 5 is formed on the upper side of the upper electrode 6. 12 are formed.

Further, in this embodiment, on the close-contact laminated body of the oxide film 2, the piezoelectric thin film 5, and the oxide film 12 on the substrate 1, which is formed at a position avoiding the diaphragm formation region on the upper side of the oxide film 12. A lower electrode connection pad 4 electrically connected to the lower electrode 3 via the extraction electrode 13 and an upper electrode connection pad 7 electrically connected to the upper electrode 6 via the extraction electrode 16 are separately formed. ing. As described above, in the present embodiment, the lower electrode connection pad 4 and the upper electrode connection pad 7 are formed at positions avoiding the diaphragm formation region on the upper side of the oxide film 12, whereby the lower electrode connection pad 4 and the upper electrode connection pad 7 are formed. The most characteristic feature of the present embodiment is that the connection pads 4 and the upper electrode connection pads 7 are provided on the close-contact laminate of the oxide film 2, the piezoelectric thin film 5, and the oxide film 12 on the substrate 1, respectively. is there.

In this embodiment, both the lower electrode connection pad 4 and the upper electrode connection pad 7 are formed on the oxide film 12, and the lead electrodes 13 and 16 connect the lower electrode 3 and the upper electrode to each other. For connection, a contact hole 9a for inserting the extraction electrode 16 is formed in the oxide film 12, and a contact hole 9b for inserting the extraction electrode 13 is formed in the oxide film 12 and the piezoelectric thin film 5. . Further, in the present embodiment, the lower electrode connection pad 4 and the upper electrode connection pad 7 are provided on each end side of the substrate 1 (the lower electrode connection pad 4 is on the right side in the figure, and the upper electrode connection pad 7 is on the left side in the figure). Are formed separately. It should be noted that FIG. 1A also shows a state in which the oxide film 12 is omitted in FIG.

The present embodiment is configured as described above, and performs the same operation as the conventional example. Next, a manufacturing process of the piezoelectric thin film vibrator of the embodiment will be described. First,
A sacrificial layer is formed at a central local portion of the semiconductor crystal on the substrate 1 so as to correspond to a region where the void 8 is formed, and an oxide film 2 having a thickness of several μm is formed on the sacrificial layer. Almost the entire region of the semiconductor device 1 is covered with the oxide film 2. next,
The sacrifice layer is etched to form a gap 8 between the oxide film 2 and the substrate 1, and a diaphragm formation region floating from the substrate 1 is formed at a local portion on the center side of the oxide film 2.

Next, the lower electrode 3 is formed on the upper side of the diaphragm forming region of the oxide film 2, and the piezoelectric thin film 5 is formed on the upper side of the lower electrode 3, and almost the entire area on the upper side of the oxide film 2 is formed. It is covered by the piezoelectric thin film 5. Then, a hole for a contact hole 9b for electrically connecting the lower electrode 3 and the lower electrode connection pad 4 is formed in the piezoelectric thin film 5.

Next, the piezoelectric thin film 5 in the diaphragm forming region
An upper electrode 6 is formed on the upper side of the piezoelectric thin film 5 so as to face the lower electrode 3, and an oxide film 12 is formed on the upper side of the upper electrode 6. Cover it. A hole for a contact hole 9b for electrically connecting the lower electrode 3 to the lower electrode connection pad 4 and a contact hole 9a for electrically connecting the upper electrode 6 to the upper electrode connection pad 7 are formed. Open in oxide film 12. And, finally, by performing wire bonding, the lower electrodes 3 connected to the lower electrode contact pad 4 by the extraction electrode 13 via the contact hole 9b, the lead-out electrode 16 and the upper electrode 6 through the contact hole 9a connected to the upper electrode contact pad 7.

The present embodiment is manufactured as described above. Like the conventional example, the lower electrode connection pad 4 is formed.
The lead electrodes 13 and 16 are respectively connected by wire bonding to the upper electrode connection pad 7 and the upper electrode connection pad 7. In this embodiment, the formation regions of the lower electrode connection pad 4 and the upper electrode connection pad 7 are: Since it is located at a position avoiding the diaphragm formation region and is on a close-adhesion laminate of the oxide film 2 and the piezoelectric thin film 5 on the substrate 1 and the oxide film 12, the strength against stress is high, and the substrate is floated from the conventional substrate 1. Unlike the case where the oxide film 2 is pressed from above, the connection pad formation region is not broken even when the stress due to wire bonding is applied to the connection pad formation region.
Destruction of the connection pad formation region can be reliably suppressed.

Further, in the present embodiment, since the formation regions of the lower electrode connection pads 4 and the upper electrode connection pads 7 are formed on the close-contact laminate as described above, they are floated from the substrate 1. Unlike the conventional example in which the connection pad formation region is provided on the upper side of the oxide film 2, even if a stress is generated due to a difference in thermal expansion between the substrate 1 and the oxide film 2, the oxide film 2 is broken by the stress. Can also be suppressed.

Further, in this embodiment, as described above, the formation regions of the lower electrode connection pad 4 and the upper electrode connection pad 7 are formed on the close-contact laminate,
Substrate 1, lower electrode connection pad 4, upper electrode connection pad 7
The two oxide films 2 and 12 functioning as first and second insulating films and the piezoelectric thin film 5
Are provided, the parasitic capacitance between the substrate 1 and the lower electrode connection pad 4 and the parasitic capacitance between the substrate 1 and the upper electrode connection pad 7 are both smaller than the capacitance between the lower electrode 3 and the upper electrode 6. Very small, and the lower electrode connection pad 4
And the capacitance between the upper electrode connecting pad 7 and the upper electrode connecting pad 7 is also reduced. For this reason, the parasitic characteristics between the extraction electrodes 13 and 16, the lower electrode connection pad 4, the upper electrode connection pad 7, and the substrate 1 in portions avoiding the diaphragm formation region may cause deterioration of resonance characteristics such as a decrease in impedance response. However, a piezoelectric thin-film vibrator having excellent resonance characteristics can be obtained.

Further, according to the present embodiment, the lower electrode connection pad 4 and the upper electrode connection pad 7 are both formed on the oxide film 12, and the connection pads 4 and 7 and the piezoelectric thin film 5 Since the oxide film 12 is interposed therebetween, unlike the conventional example in which the upper electrode connection pad 7 is formed directly on the piezoelectric thin film 5, damage to the piezoelectric thin film 5 is suppressed, and the piezoelectric thin film vibrator is formed. The yield at the time of manufacturing can be improved, and the durability can be improved.

Further, according to the present embodiment, the substrate 1 is formed of a semiconductor crystal substrate, and the piezoelectric thin film vibrator is formed using the semiconductor crystal substrate 1. Therefore, the conventional piezoelectric thin film vibrator is used. Similarly to the above, it is possible to reduce the size of the element, and it is also possible to integrate the element with a peripheral circuit, and it can be easily incorporated into sensors such as an acceleration sensor and other various devices to be widely applied. .

FIGS. 2A and 2B are plan views of a piezoelectric thin-film vibrator according to a second embodiment of the present invention.
-A is shown by the sectional view (b). This embodiment is different from the first embodiment in that the upper electrode 6 has two electrodes 6a,
6b, and these two upper electrodes 6
a, 6b have separate extraction electrodes 16a, 16b, respectively.
And upper electrode connection pads 7a and 7b.

Although not shown in the figure, in this embodiment, as in the first embodiment,
The lower electrode connection pad is formed at a position avoiding the diaphragm formation region on the upper side of the oxide film 12, and the upper electrode is formed on the close-contact laminate of the oxide film 2, the piezoelectric thin film 5, and the oxide film 12 on the substrate 1. the connection pad 7 are formed separately, it is conductively connected via the lead electrode (not shown) and the lower electrode contact pad and the lower electrode 3. In FIG. 2A, the oxide film 12 is omitted.

The present embodiment is configured as described above, and the piezoelectric thin-film vibrator of this embodiment is manufactured by substantially the same manufacturing steps as the piezoelectric thin-film vibrator of the first embodiment. In the present embodiment, two upper electrodes 6a, 6a are provided on the upper side of the piezoelectric thin film 5 in order to provide two upper electrodes 6.
The contact holes 9a ₁ for electrically connecting the upper electrodes 6a, 6b and the upper electrode connection pads 7a, 7b are formed in the oxide film 12 formed on the upper side of the upper electrodes 6a, 6b. , drilling holes for 9a _2. Then, each upper electrode 6 is contacted via the contact holes 9a ₁ and 9a _2.
a, 6b are connected to the respective upper electrode connection pads 7a, 7b by the lead electrodes 16a, 16b.

The present embodiment is manufactured as described above, performs the same operation as that of the first embodiment, and can provide the same effect.

According to this embodiment, the upper electrode 6
Is formed by two upper electrodes 6a and 6b, and separate extraction electrodes 16a and 16b and upper electrode connection pads 7 are respectively provided.
a and 7b, for example, one upper electrode 6
a side is a driving electrode for vibration of the diaphragm forming region,
If the upper electrode 6b on the other side is used as a detection electrode and the upper electrode 6a drives the vibration of the diaphragm forming region based on the detection voltage detected by the upper electrode 6b for detection, vibration frequency control and the like are performed. It can be easier.

FIG. 3 is a plan view of a third embodiment of the piezoelectric thin film vibrator according to the present invention, and FIG.
-A is shown by the sectional view (b). This embodiment is different from the first embodiment in that a recess 11 is formed in a substrate 1 of a semiconductor crystal, and an oxide film 2 is formed on a surface on which the recess 11 is formed. That is, a diaphragm forming region was formed in a local portion on the center side. In the present embodiment, as in the first and second embodiments, a gap 8 is formed between the substrate 1 and the oxide film 2 so that the diaphragm formation region floating from the substrate 1 in the oxide film 2 is formed. Unlike the case where the oxide film 2 is formed, the oxide film 2 is formed on the concave portion forming surface of the substrate 1 so that the oxide film 2 is floated from the substrate 1. The surface on which the piezoelectric thin film 5 is formed is a flat surface.

Other than the above, the structure of this embodiment is the same as that of the first embodiment. Next, the manufacturing process of this embodiment will be described. First, a semiconductor crystal substrate 1 having a flat front surface 14 and a rear surface 10 is prepared, an oxide film 2 is formed on the entire surface 14 of the substrate 1, and a concave portion 11 is formed on the rear surface 10 of the substrate 1. An oxide film (not shown) for an etching mask is formed in a region excluding the region (the central portion of the substrate 1). Then, using the oxide film for the etching mask as a mask, the substrate 1 is anisotropically etched to form the concave portion 11, and thereafter, the oxide film for the etching mask is removed. Then, the oxide film 2 is formed on the surface of the substrate 1 on which the concave portion is formed (the surface 14 side).
A diaphragm formation region is formed at a position corresponding to the recess 11.

Next, a lower electrode 3 is formed on the upper side of the diaphragm formation region of the oxide film 2, and thereafter, a piezoelectric element as shown in FIG. A thin film oscillator is formed.

The present embodiment is manufactured as described above, performs the same operation as that of the first embodiment, and can provide the same effect.

According to this embodiment, the first,
Unlike the second embodiment, it is possible to omit the labor of forming a sacrifice layer on the substrate 1, forming the oxide film 2 on the sacrifice layer, and then etching the sacrifice layer to form the void 8. In addition, since the concave portion 11 can be formed by a method that is very easy to process and has excellent processing accuracy, such as anisotropic etching of the semiconductor crystal substrate 1, the diaphragm formation region can be formed very easily. A thin-film vibrator can be manufactured.

The present invention is not limited to the above-described embodiment, but can adopt various embodiments. For example,
In the third embodiment, the recess 11 is formed by anisotropic etching of the semiconductor crystal substrate 1. However, the method of forming the recess 11 is not necessarily limited to the anisotropic etching of the substrate 1, but the anisotropic etching. Other than, for example, concave by cutting
11 may be formed.

In the third embodiment, the recess 11
Is a penetrating recess from the front surface 14 side to the back surface 10 side of the substrate 1. However, the concave portion 11 is not necessarily a penetrating concave portion. For example, the concave portion 11 is formed so that the cross-sectional shape of the substrate 1 becomes U-shaped.
11 may be formed, and the oxide film 2 may be formed on the concave portion forming surface to form a diaphragm forming region.

Further, in the above embodiment, the first and second
Although the oxide films 2 and 12 are formed as the insulating films, the first and second insulating films are not necessarily formed of an oxide film, and may be formed of a film having an insulating property other than the oxide film. Good.

Further, the lower electrode connection pad 4 and the upper electrode connection pad 7 provided on the piezoelectric thin film vibrator of the present invention
The first insulating film (the oxide film 2 in the above-described embodiment), the piezoelectric thin film 5 and the second insulating film on the substrate 1 avoiding the diaphragm formation region on the upper side of the second insulating film such as the oxide film 12. The lower electrode connection pad 4 and the upper electrode connection pad 7 may be provided at appropriate positions on the laminated body with the film, for example, at positions corresponding to the corners of the substrate 1.

Further, in the above-described embodiment, the diaphragm forming region is formed at a local portion at the center between both ends of the oxide film 2, but the diaphragm forming region is not necessarily formed at the center between the both ends of the oxide film 2. Not limited to this, it may be formed at a position shifted from the center to the end. Further, the gaps 8 and the recesses 11 longer in the longitudinal direction of the substrate 1 than the gaps 8 and the recesses 11 formed in the above-described embodiment are formed, thereby forming a diaphragm forming region longer in the longitudinal direction of the substrate 1. Good. Even in such a case, according to the present invention, the lower electrode connecting pad 4 and the upper electrode connecting pad 7 avoid the diaphragm formation region, and the substrate 1, the oxide film 2, and the piezoelectric thin film 5 are formed.
And the oxide film 12 are formed on the close-stacked body, so that the same effects as those of the above embodiment can be obtained.

[0045]

According to the present invention, the lower electrode and the upper electrode connection pad electrically connected to the upper electrode and the lower electrode via the lead-out electrode are formed at positions avoiding the diaphragm formation region. By forming the first insulating film, the piezoelectric thin film, and the second insulating film on the close contact laminated body, the strength of the connection pad formation region with respect to stress can be increased. Even if stress is applied to the connection pad formation region by performing wire bonding, it is possible to prevent the insulating film, the piezoelectric thin film, and the connection pad itself in the connection pad formation region from being broken. Further, by forming a region for forming a connection pad for the upper electrode and the lower electrode on the close-contact laminate, a connection pad is formed on the upper side of the substrate 1 and the first insulating film formed via a gap. Unlike the formed conventional piezoelectric thin-film vibrator, even if a stress is generated due to a difference in thermal expansion between the substrate and the first insulating film, it is possible to prevent the first insulating film and the like from being broken.

Further, according to the present invention, the connection pads for the upper electrode and the lower electrode are formed on the upper side of the second insulating film, and the second insulating film is interposed between the connection pads and the piezoelectric thin film. Unlike conventional piezoelectric thin film resonators, in which pads for direct connection are formed on the piezoelectric thin film, the yield of the piezoelectric thin film resonator is improved without damaging the piezoelectric thin film. Can be done.

Further, according to the present invention, as described above, the connection pads for the upper electrode and the lower electrode are formed on the close-contact laminate of the first insulating film, the piezoelectric thin film, and the second insulating film on the substrate. Formed between the connection pads and the substrate.
And the second two insulating films interposed therebetween, the capacitance between each connection pad and each lead electrode and the substrate on the close-contact laminated body is much smaller than the capacitance between the upper electrode and the lower electrode. Therefore, like the conventional piezoelectric thin-film vibrator in which a gap is provided between the first insulating film and the substrate to reduce the parasitic capacitance between the connection pad and the extraction electrode and the substrate, It is possible to reduce the parasitic capacitance, thereby preventing the deterioration of the resonance characteristics, and to form a piezoelectric thin-film vibrator excellent in the resonance characteristics.

Also in the present invention, the substrate is formed of a semiconductor crystal substrate, and the piezoelectric thin-film vibrator is formed using this substrate, thereby being integrated with the peripheral circuit in the same manner as the conventional piezoelectric thin-film vibrator. This makes it possible to easily incorporate the sensor into sensors such as an acceleration sensor and an angular velocity sensor and various other devices, and can be widely applied to various devices.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of a piezoelectric thin-film vibrator according to the present invention.

FIG. 2 is a configuration diagram showing a second embodiment of a piezoelectric thin film vibrator according to the present invention.

FIG. 3 is a configuration diagram showing a third embodiment of a piezoelectric thin-film vibrator according to the present invention.

FIG. 4 is an explanatory view showing an example of a conventional piezoelectric thin-film vibrator.

FIG. 5 is an explanatory view showing another example of a conventional piezoelectric thin film vibrator.

[Explanation of symbols]

1 substrate 2, 12 oxide film 3 lower electrode 4 lower electrode contact pad 5 the piezoelectric thin film 6 upper electrode 7 upper electrode connecting pads _{9a, 9b, 9a 1, 9a} 2 contact hole 11 recess

Claims (3)

(57) [Claims] 1. A substrate and, a first insulating film of the thin formed on said substrate, said ends of the first insulating film above the substrate
Together are laminated in close contact with the surface of the local sites across the form a diaphragm forming region had floating from the substrate,
A lower electrode formed on the upper surface of the 該Da diaphragm and forming region, and a piezoelectric thin film that covers almost the entire area of the upper surface and the upper surface of the first insulating film of the lower electrode, before the upper surface of the piezoelectric thin film An upper electrode formed to face the lower electrode, an upper surface of the upper electrode and an upper portion of the piezoelectric thin film;
A second insulating film covering substantially the entire area of the surface, the prior SL substrate and <br/> the first insulating film and the piezoelectric thin film and the upper surface of the adhesion lamination portion between the second insulating film first On one end of the insulating film
And connecting pads formed the lower electrode, the adhesion product
The upper surface of the layer portion is formed on the other end side of the second insulating film.
A connection pad for the upper electrode ,
Formed on the piezoelectric thin film and the second insulating film on one end side
A first contact hole exposing the lower electrode;
Formed on the second insulating film on the other end side of the second insulating film;
Second contact hole exposing said upper electrode
And the lower electrode via the first contact hole.
And an upper surface of the second insulating film.
A lower extraction electrode formed on the surface, and the second contour
Provided to connect to the upper electrode through a via hole
And an upper pull-up formed on the upper surface of the second insulating film.
And a contact electrode between the lower electrode and the lower electrode.
Connection to the connection pad via the lower lead electrode
And a connection pad between the upper electrode and the upper electrode.
The piezoelectric thin film resonator, wherein the head through the upper extraction electrode and this <br/> for electrical connection. 2. The upper electrode is formed by two electrodes arranged at an interval from each other, and each of the two upper electrodes is provided with a separate extraction electrode and a connection pad. The piezoelectric thin film vibrator according to claim 1, wherein: Wherein the substrate is formed by semiconductor crystal, a recess is formed on the substrate, also claim 1, characterized in that the first insulating film on the concave portion forming surface is formed
Is a piezoelectric thin-film vibrator according to claim 2 .