JP2001251156A - Piezoelectric vibrating reed, its manufacture and its device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric vibrating reed whose oscillation frequency can be adjusted while measuring the oscillation frequency and whose oscillation frequency can be adjusted by a large quantity, and to provide its manufacturing method and device. SOLUTION: Anodic oxidation films 34 are formed on the exciting electrodes of a piezoelectric vibrating reed 30 provided a vibrating part 31 whose center is made thin and the exciting electrodes 32 formed at the vibrating part. Because the anodic oxidation films are piled up gradually on the vibrating part in this way to increase its thickness and the piezoelectric vibrating reed is manufactured by measuring the oscillation frequency of the vibrating part each time the anodic oxidation film is piled up, the piezoelectric vibrating reed in which the oscillation frequency of the vibrating part accurately meets a prescribed value can be manufactured. Furthermore, because the oscillation frequency of the vibrating part is adjusted simply by piling up the anodic oxidation films, the adjustment quantity of the oscillation frequency can be made large.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a piezoelectric vibrating reed and a method and an apparatus for manufacturing the same, and more particularly, to a piezoelectric vibrating reed whose vibration frequency is adjusted with high precision, and a method and an apparatus for manufacturing the same.

[0002]

2. Description of the Related Art A piezoelectric vibrating reed is generally constituted by a vibrating portion, an excitation electrode and an extraction electrode. The vibration frequency of the piezoelectric vibrating reed having such a configuration is determined by the thickness of the vibrating portion. The thickness of the vibrating part and the vibration frequency are in inverse proportion,
For example, when the thickness of the vibrating part is 100 μm, the vibration frequency is 17.5 MHz, and when the thickness of the vibrating part is 50 μm, the vibration frequency is 35 MHz.

However, as the thickness of the vibrating portion becomes thinner,
Mechanical polishing becomes difficult, the strength against vibration is weakened, and the vibrating part is easily damaged. For this reason, the high-frequency piezoelectric vibrating reed is manufactured in a so-called inverted mesa shape in which only the central portion of the vibrating portion is thinned and the outer peripheral portion is thickened as a reinforcing frame. The thinning of the central portion of the vibrating portion may be performed by mechanical polishing, but is mostly performed by wet etching.

FIGS. 10A and 10B are a perspective view showing an example of a general inverted-mesa type piezoelectric vibrating piece and a sectional view taken along line AA of FIG.

The inverted-mesa type piezoelectric vibrating reed 10 has a rectangular plate-shaped vibrating portion 11 which is thinly processed only at its central portion and whose outer peripheral portion is thickly processed. Excitation electrodes 12 are formed on the front and back surfaces at the center of the vibrating portion 11, and a lead electrode 13 for energizing each excitation electrode 12 is formed at one end of the outer peripheral portion.

As a method of manufacturing such an inverted mesa type piezoelectric vibrating reed 10, a plurality of etching patterns are formed on a substrate by photolithography, wet-etched to a predetermined thickness, and a plurality of chips are divided by wet etching or the like. To form the vibrating section 11. Then, a method is known in which the excitation electrode 12 and the extraction electrode 13 are formed by sputtering or the like to obtain the final inverted mesa type piezoelectric vibrating piece 10.

[0007]

As a method for adjusting the vibration frequency of the above-mentioned conventional inverted-mesa type piezoelectric vibrating piece 10 to a predetermined value, a method for reducing the thickness of the vibrating portion 11 by wet etching or the like, A method of reducing the thickness of the substrate 12 by polishing or the like is employed.

However, in the method of reducing the thickness of the vibrating portion 11 by wet etching or the like, since an etching solution is used, the vibration frequency of the inverted mesa type piezoelectric vibrating piece 10 cannot be adjusted to a predetermined value while being measured. For this reason, the wet etching of the vibrating part 11 and the measurement of the vibration frequency of the inverted mesa type piezoelectric vibrating piece 10 must be alternately repeated until the vibration frequency of the inverted mesa type piezoelectric vibrating piece 10 reaches a predetermined value. There is a disadvantage that it takes a lot of adjustment man-hours.

Further, in the method of reducing the thickness of the excitation electrode 12 by polishing or the like, since the thickness of the excitation electrode 12 is extremely thin, the amount of adjustment of the vibration frequency of the inverted mesa type piezoelectric vibrating piece 10 is limited, and the predetermined amount is reduced. There was a drawback that the value could not be adjusted.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to make it possible to adjust while measuring the vibration frequency of a piezoelectric vibrating piece, and to obtain a large amount of adjustment of the vibration frequency, and to manufacture the same. It is to provide a method and an apparatus.

[0011]

According to a first aspect of the present invention, there is provided a piezoelectric vibrating reed comprising a vibrating portion having a thin central portion and an exciting electrode formed on the vibrating portion. A piezoelectric vibrating reed characterized by having an anodic oxide film formed thereon.

According to the first aspect of the present invention, the piezoelectric vibrating reed is manufactured by gradually accumulating the anodic oxide film on the vibrating portion to increase the thickness and measuring the vibration frequency of the vibrating portion each time the vibrating portion is stacked. A piezoelectric vibrating reed in which the vibration frequency of the vibrating part exactly matches the predetermined value can be obtained. Further, since the adjustment of the vibration frequency of the vibrating portion is performed only by stacking the anodic oxide films, a large adjustment amount of the vibration frequency can be adopted.

According to a second aspect of the present invention, in a method of manufacturing a piezoelectric vibrating reed in which a central portion of a vibrating portion is thinned and an exciting electrode is formed in a central portion of the vibrating portion, at least the exciting electrode is formed. The central part of the vibrating part is immersed in an anodic oxide solution, a DC voltage is supplied to the excitation electrode to form an anodic oxide film on the excitation electrode, and an AC voltage is supplied to the excitation electrode to vibrate the vibration part. And measuring the vibration frequency and repeating the formation of the anodic oxide film and the measurement of the vibration frequency until the measured vibration frequency reaches a predetermined value.

According to the second aspect of the present invention, an anodic oxide film is provided on a part of the excitation electrode of the piezoelectric vibrating piece which has been prepared in advance so that the vibration of the vibrating part is higher than a predetermined vibration frequency. After the film is formed to have a thickness, the vibration frequency of the vibrating part is measured and compared with the target vibration frequency. For this reason, a piezoelectric vibrating reed having a highly accurate vibration frequency can be manufactured.

According to a third aspect of the present invention, there is provided an apparatus for manufacturing a piezoelectric vibrating reed in which a central portion of a vibrating portion is thinned and an excitation electrode is formed on the vibrating portion, wherein an anodizing solution for immersing the piezoelectric vibrating reed is provided. A storage unit that stores a DC voltage to the excitation electrode, a measurement unit that measures a vibration frequency of the vibration unit, a connection terminal of the excitation electrode of the power supply unit, and the measurement unit. A switching unit that switches a connection terminal with an excitation electrode; and a control unit that controls switching of the switching unit in accordance with a measurement signal of the measuring unit. A piezoelectric vibrating reed manufacturing apparatus, wherein an anodic oxide film is formed on at least a part of the excitation electrode by a part.

According to the third aspect of the present invention, an anodic oxide film having a predetermined thickness is formed on a part of the excitation electrode of the piezoelectric vibrating reed, and the process of measuring the vibration frequency of the vibrating portion is switched. Can be easily performed. For this reason, manufacturing efficiency can be improved and manufacturing cost can be reduced.

According to a fourth aspect of the present invention, in the configuration according to the third aspect, the control unit repeats the switching by the switching unit until the vibration frequency measured by the measuring unit reaches a predetermined value. It is.

According to the fourth aspect of the present invention, the process of forming the anodic oxide film on at least a part of the excitation electrode by the power supply unit while measuring the vibration frequency of the vibrating unit by the measuring unit is performed by setting the measured vibration frequency to a predetermined value Can be automatically performed by the control unit until. Therefore, the manufacturing efficiency can be further improved, and the manufacturing cost can be further reduced.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1A and 1B are a perspective view showing an inverted-mesa type piezoelectric vibrating piece which is an embodiment of the piezoelectric vibrating piece of the present invention, and a cross-sectional view taken along line AA.

In the inverted-mesa type piezoelectric vibrating piece 30, only the central portion of the vibrating portion 31 having a rectangular plate shape is processed to be thin, and the outer peripheral portion is processed to be thick. Excitation electrodes 32 are formed on the front and back surfaces of the central portion of the vibrating portion 31, and a lead electrode 33 for energizing each excitation electrode 32 is formed on one end of the outer peripheral portion. An anodic oxide film 34 is formed on the excitation electrode 32 while measuring the vibration frequency of the vibration part 31.

The vibrating section 31 is made of, for example, quartz, but may be made of, for example, lithium niobate (LiNbO 3).
And lead zirconate titanate (PZT: Pb (ZrTi) O
3) or the like. The excitation electrode 32 and the extraction electrode 33 are formed of, for example, aluminum (Al), and are further formed of, for example, A containing 0.1% by weight of copper (Cu).
1 and the like. The anodic oxide film 34 may be any film in which an oxide on the metal surface of the anode in the aqueous electrolyte solution is passivated.
O3).

The inverted-mesa type piezoelectric vibrating piece 30 is formed by gradually stacking the anodic oxide film 34 on the vibrating portion 31 to increase the thickness, and measuring the vibration frequency of the vibrating portion 31 every time the piezoelectric vibrating portion 31 is stacked. Since it is a piece, the vibration frequency of the vibration part 31 can be accurately adjusted to a predetermined value. Further, since the adjustment of the vibration frequency of the vibration section 31 is performed only by stacking the anodic oxide films 34, the adjustment amount of the vibration frequency can be large.

FIGS. 2 to 8 are process diagrams showing an embodiment of the method for manufacturing a piezoelectric vibrating reed according to the present invention.

First, the size is 30 mm × 30 mm × 0.
An AT-cut substrate (a Y-plate rotated at 35 ° 15 minutes) 21 made of 1 mm crystal is prepared and its surface is polished (FIG. 2A). Then, Cr is sputtered or vapor-deposited on both sides of the AT-cut substrate 21 to a thickness of 0.05 μm to form a Cr film 22, and Au is further sputtered or vapor-deposited to a thickness of 0.1 μm to form Au. The film 23 is formed into a corrosion-resistant film of hydrofluoric acid (FIG. 2)
(B)). Then, a photoresist is applied to the surface of the Au film 23 and dried to form a photoresist film 24 (FIG. 2C).

Next, the vibrating portion 3 is formed on the photoresist film 24.
A photomask 25 on which an etching pattern for forming the outer shape 1 is drawn is arranged, and is exposed to ultraviolet rays to transfer the etching pattern of the photomask 25 to the photoresist film 24 (FIG. 2D). Then, the photosensitive portion of the photoresist film 24 is developed and removed with a developing solution to expose the Au film 23 (FIG. 2E).

Next, the exposed Au film 23 is made of an aqueous solution of, for example, iodine (I2) and potassium iodide (KI).
The Cr film 22 is exposed by etching with an etching solution for u, and the exposed Cr film 22 is further etched with an etching solution for Cr to expose the AT cut substrate 21 (FIG. 3A). Then, the remaining photoresist film 24 is stripped (FIG. 3B). Then, exposed A
T-cut substrate 21 and remaining Cr film 22 and Au film 2
Then, a photoresist is applied again so as to cover all the layers 3 and dried to form a photoresist film 26 (FIG. 3C).

Next, the vibrating portion 3 is formed on the photoresist film 26.
A photomask 27 on which an etching pattern for forming the shape 1 is drawn is arranged, and is exposed to ultraviolet rays to transfer the etching pattern of the photomask 27 to the photoresist film 26 (FIG. 3D). Then, the exposed portion of the photoresist film 26 is developed and removed with a developing solution to expose the AT cut substrate 21 and the Au film 23 (FIG. 4).
(A)).

Next, the exposed AT-cut substrate 21 is made of, for example, hydrofluoric acid (HF) and ammonium fluoride (NH 4).
F) is a 1: 1 mixed solution (buffered hydrofluoric acid) for a crystal etching solution at 50 ° C., and is etched for 1 hour to form a vibrating portion 31 having a size of 3 mm × 2 mm (FIG. 4).
(B)). On the other hand, the exposed Au film 23 is etched with the above-described etching solution for Au to expose the Cr film 22, and the exposed Cr film 22 is etched with the above-described etching solution for Cr to expose the AT cut substrate 21. (FIG. 4C).

Next, the exposed AT-cut substrate 21 is half-etched with the above-described etching solution for quartz to form a central portion of the vibrating portion 31 to a thickness of 8 μm (FIG. 4).
(D)). Then, the remaining photoresist film 26
Then, the Cr film 22 and the Au film 23 are peeled off. Thus, the plurality of vibrating sections 31 are completed (FIG. 4E). At this time, the thickness of the vibrating part 31 is made thinner in advance so as to be higher than the target vibration frequency.

Next, the excitation electrodes 32 are provided on both surfaces of the vibrating section 31.
Then, a mask 28 on which an electrode pattern for forming the extraction electrode 33 is drawn is arranged (FIG. 5A), and Al is formed on both surfaces of the vibrating part 31 by sputtering until the thickness becomes 300 nm. Thus, the excitation electrode 32 and the extraction electrode 33 are formed (FIG. 5B).

Next, while measuring the vibration frequency of the vibrating section 31 using a manufacturing apparatus 40 as shown in FIG.
An anodic oxide film 34 is formed thereon. Al2O at this time
Since the weight of the anodic oxide film 34 made of No. 3 is larger than that of the excitation electrode 32 made of Al, the vibration frequency of the vibrating part 31 decreases as the thickness of the anodic oxide film 34 increases.

The apparatus 40 for manufacturing a piezoelectric vibrating reed comprises a storage section 42 for storing an anodic oxidizing solution 41 for immersing the piezoelectric vibrating piece 30 and a power supply section 4 for supplying a DC voltage to the excitation electrode 32.
3. The measuring unit 44 for measuring the vibration frequency of the vibrating unit 31, the negative connection terminal 43a of the power supply unit 43 with the excitation electrode 32, and the connection terminals 44a and 44b of the positive connection terminal 43b with the excitation electrode 32 of the measurement unit 44. A switching section 45 for switching and a control section 46 for controlling switching of the switching section 45 in accordance with a measurement signal of the measuring section 44 are provided.

The storage unit 4 of the manufacturing apparatus 40 having such a configuration is described.
At least the central portion of the vibrating portion 31 where the excitation electrode 32 is formed and the negative electrode bar 47 are immersed in the anodic oxidizing solution 41 stored in the inside 2. As the anodizing solution 41, for example, ammonium dihydrogen phosphate (NH4H2PO4)
) And diammonium hydrogen phosphate ((NH4) 2HP
O4) is used. As the negative electrode rod 47,
For example, a rod made of platinum (Pt) is used. Then, each excitation electrode 32 and each connection terminal 45a, 45b of the switching unit 45
And the negative electrode rod 47 and the negative connection terminal 43a of the power supply unit 43 are connected.

Next, the control unit 46, as shown in FIG.
By operating the switching unit 45, each connection terminal 45a of the switching unit 45,
45b, the negative connection terminal 43a of the power supply unit 43, and the positive connection terminal 4
3b. As a result, a DC voltage of, for example, 60 V is supplied from the power supply unit 43 to each excitation electrode 32, and the anodic oxide film 34 is formed on each excitation electrode 32.

When the supply of the DC voltage has passed for a predetermined time, the control unit 46 switches the switching unit 4 as shown in FIG.
5 is operated to connect the connection terminals 45a and 45b of the switching unit 45 to the connection terminals 44a and 44b of the measurement unit 44.
As a result, the AC voltage is supplied from the measuring unit 44 to each excitation electrode 32 to vibrate the vibrating unit 31, and the measuring unit 44 measures the vibration frequency at that time.

Here, if the supply time of the DC voltage is too short, current flows between the excitation electrodes 32 due to the anodic oxidizing liquid 41, and the vibration frequency may not be measured. After the oxide film 34 is formed to some extent, for example, the supply of DC voltage is 5 sec to 1 sec.
It is better after 0 seconds have elapsed.

Then, the control section 46 reads the measured vibration frequency from the measuring section 44 and compares it with the target vibration frequency stored in advance. When the measured vibration frequency does not reach the target vibration frequency, As shown in FIG.
5, the connection terminals 45a and 45b of the switching unit 45 are connected again to the negative connection terminal 43a and the positive connection terminal 43b of the power supply unit 43, and the anodic oxide film 34 is formed again. As described above, the control unit 46 repeats the formation of the anodic oxide film 34 and the measurement of the vibration frequency until the measured vibration frequency reaches the predetermined value, thereby obtaining the final inverted mesa type piezoelectric vibrating piece 30.

At this time, the supply time of the DC voltage by the power supply unit 43, that is, the anodic oxidation time (sec) and the measurement unit 44
The relationship with the vibration frequency (MHz) measured by
When the DC voltage supplied by the power supply unit 3 is 30 V, the voltage is gentle as shown by a black circle in FIG. 9, but when the DC voltage supplied by the power supply unit 43 is 60 V, the voltage becomes steep as shown by a black square in FIG. Therefore, when shortening the anodic oxidation time (sec) and increasing the accuracy of the vibration frequency adjustment are performed, the supply DC voltage may be increased in the initial stage and the supply DC voltage may be decreased in the final stage. .

As described above, the anodic oxide film 34 is provided on a part of the excitation electrode 32 of the inverted mesa type piezoelectric vibrating piece 30 which has been manufactured in advance so that the vibration of the vibrating part 31 is higher than the predetermined vibration frequency. Is formed with a predetermined thickness, and the vibration frequency of the vibration section 31 is measured and compared with the target vibration frequency. Therefore, it is possible to manufacture the inverted-mesa type piezoelectric vibrating piece 30 having a high-precision vibration frequency.

An anodic oxide film 34 having a predetermined thickness is formed on a part of the excitation electrode 32 of the inverted mesa type piezoelectric vibrating piece 30, and the process for measuring the vibration frequency of the vibration section 31 is switched. The control can be easily performed by the control unit 46 until the measured vibration frequency reaches a predetermined value. For this reason, manufacturing efficiency can be improved and manufacturing cost can be reduced.

[0042]

As described above, according to the present invention, the thickness of the anodic oxide film is gradually increased on the vibrating portion to increase the thickness, and the vibration frequency of the vibrating portion is measured each time the vibration is accumulated. A large amount of adjustment of the vibration frequency of the part can be taken to be precisely adjusted to a predetermined value, and a highly accurate piezoelectric vibrating reed can be obtained.

Since the anodic oxide film is formed with a predetermined thickness, the vibration frequency of the vibrating portion is measured and compared with the target vibration frequency. The piezoelectric vibrating reed can be manufactured, and furthermore, these processes can be easily performed by the switching unit and automatically performed by the control unit.
Manufacturing costs can be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an inverted mesa type piezoelectric vibrating reed which is an embodiment of the piezoelectric vibrating reed of the present invention, and a cross-sectional view taken along line AA of FIG.

FIG. 2 is a first process chart showing an embodiment of a method of manufacturing a piezoelectric vibrating reed according to the present invention.

FIG. 3 is a second process diagram showing an embodiment of the method of manufacturing a piezoelectric vibrating reed according to the present invention.

FIG. 4 is a third process chart showing an embodiment of the method for manufacturing a piezoelectric vibrating reed according to the present invention.

FIG. 5 is a fourth process chart showing an embodiment of the method for manufacturing a piezoelectric vibrating reed according to the present invention.

FIG. 6 is a fifth process chart showing an embodiment of a manufacturing method using the embodiment of the apparatus for manufacturing a piezoelectric vibrating reed according to the present invention.

FIG. 7 is a sixth process chart showing an embodiment of the method for manufacturing a piezoelectric vibrating reed according to the present invention.

FIG. 8 is a seventh process chart showing an embodiment of the method for manufacturing a piezoelectric vibrating reed according to the present invention.

FIG. 9 is a diagram showing a relationship between an etching time (sec) by a dry etching device and a change in vibration frequency (MHz) measured by a vibration frequency measurement device in the method of manufacturing a piezoelectric vibrating reed according to the present invention.

FIG. 10 is a perspective view showing an example of a conventional inverted-mesa type piezoelectric vibrating reed, and a cross-sectional view taken along line AA thereof.

[Explanation of symbols]

 10, 30 Inverted mesa type piezoelectric vibrating piece 11, 31 Vibrating part 12, 32 Exciting electrode 13, 33 Connecting electrode 34 Anodized film 21 AT cut substrate 22 Cr film 23 Au film 24, 26 Photoresist film 25, 27 Photomask 28 Mask 40 Piezoelectric vibrating reed manufacturing apparatus 41 Anodizing solution 42 Storage unit 43 Power supply unit 43a Negative connection terminal 43b Positive connection terminal 44 Frequency measurement unit 44a, 44b Connection terminal 45 Switching unit 45a, 45b Connection terminal 46 Control unit 47 Negative rod

Claims (4)

[Claims] 1. A piezoelectric vibrating reed comprising a vibrating portion having a thinned central portion and an exciting electrode formed on the vibrating portion, wherein an anodic oxide film is formed on the exciting electrode. Piezoelectric vibrating reed. 2. A method for manufacturing a piezoelectric vibrating reed in which a central portion of a vibrating portion is thinned and an exciting electrode is formed in a central portion of the vibrating portion, wherein at least a center of the vibrating portion on which the exciting electrode is formed. The part is immersed in an anodizing solution, a DC voltage is supplied to the excitation electrode to form an anodic oxide film on the excitation electrode, and an AC voltage is supplied to the excitation electrode to vibrate the vibrating part to reduce the vibration frequency. Measuring the vibration frequency until the measured vibration frequency reaches a predetermined value, and repeating the measurement of the vibration frequency. 3. A manufacturing apparatus for a piezoelectric vibrating reed in which a central part of a vibrating part is thinned and an excitation electrode is formed on the vibrating part, wherein a storage part for storing an anodic oxidizing liquid for immersing the piezoelectric vibrating reed. A power supply unit that supplies a DC voltage to the excitation electrode; a measurement unit that measures a vibration frequency of the vibration unit; and a connection terminal between the excitation electrode of the power supply unit and the excitation electrode of the measurement unit. A switching unit for switching a terminal; and a control unit for controlling switching of the switching unit in accordance with a measurement signal of the measuring unit, wherein the measuring unit measures a vibration frequency of the vibrating unit, and the power supply unit measures at least the excitation. An apparatus for manufacturing a piezoelectric vibrating reed, wherein an anodic oxide film is formed on an electrode. 4. The apparatus according to claim 3, wherein the control unit repeats switching by the switching unit until the vibration frequency measured by the measuring unit reaches a predetermined value.