JP3290756B2 - Sticking type piezoelectric vibrator and manufacturing method thereof - 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 vibrator suitable as an ultra-high frequency oscillator and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, clock signals employed in various electronic devices have shifted to higher frequency regions with the advancement of high frequency technology. In order to provide such clock signals, crystal oscillators and piezoelectric elements have also been used. There is a demand for processing into an ultra-thin shape so as to enable higher frequency vibration.

FIG. 5 schematically shows a conventional piezoelectric vibrator operating at a relatively high frequency, wherein 1 is a disk-shaped piezoelectric element made of quartz or the like, and 2A and 2B are attached to both sides of the piezoelectric element. Shows the electrodes that are present. Such a piezoelectric vibrator can be used as an oscillating element of several tens MHz by making the thickness d of the piezoelectric element several tens of μm by ultra-fine processing. For example, if the thickness of the piezoelectric element is polished to 30 μm or less, It becomes very susceptible to cracking during operation, resulting in extremely poor product yield.

Therefore, as shown in the cross-sectional view of FIG. 2, an element using an inverted mesa type piezoelectric element 3 as a vibrator has been developed.
That is, the center of the relatively thick piezoelectric element 3 is scraped off by dry etching or mechanochemical polishing to form a recess 3A, and the bottom surface 3B of the recess 3A and the thickness d of the back surface of the piezoelectric element 3 are several tens μm or less. Process so that it becomes. The electrodes 4A and 4B are attached to the bottom surface 3B of the recess 3A and the surface of the piezoelectric element 3, respectively.

[0005]

Since such a piezoelectric vibrator is mounted on a machine with the peripheral portion 3C of the piezoelectric element 3 relatively thick, the handling of the piezoelectric element is easy and the possibility of breakage is small. The advantage is expected. However, the dry etching method uses a semiconductor circuit or SA.
Attempts have been made with W elements, but the processing method is complicated,
In addition, there is a problem that the cost is increased because it is not suitable for mass production. Processing by dry etching until the bottom surface 3B of the concave portion 3A becomes a predetermined thickness has not been applied to the processing technology of quartz or the like, so it takes a long time to obtain the accurate vibration frequency characteristics. There is a problem that the processing of is required.

The present invention has been made in order to solve such a problem.
When processing an ultra-thin piezoelectric vibrator using a double-sided polishing machine that has been used in the past, a stick-type vibrator that prevents cracking of the piezoelectric vibrator and facilitates its handling, and a manufacturing method therefor It is intended to provide.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides an auxiliary piezoelectric plate having an opening formed in a central portion, the same material as the auxiliary piezoelectric plate, and the thickness thereof. The main piezoelectric vibrating plate which is formed thinner than the auxiliary piezoelectric plate is bonded, and the surface of the auxiliary piezoelectric plate and the surface of the main piezoelectric vibrating plate are simultaneously polished to a predetermined size by a double-side polishing machine. It is. In this bonding, the vibration characteristics can be stabilized against a temperature change by setting the directions in which the crystal axes coincide with each other. In addition, since the thickness of the auxiliary piezoelectric plate and the thickness of the main piezoelectric diaphragm are set in advance so that the thickness of the main piezoelectric diaphragm becomes constant by the double-side polishing, a desired frequency is obtained. Work becomes easier.

[0008]

Since the peripheral portion of the main piezoelectric vibrating plate for setting the oscillation frequency is strengthened by the relatively thick auxiliary piezoelectric plate, the handling of the piezoelectric element becomes easy and a manufacturing method with a high yield can be established. In addition, since mass production becomes possible, costs can be reduced.

[0009]

1 is an explanatory view showing a method of manufacturing a pasted type piezoelectric vibrator according to the present invention. Reference numeral 10 denotes an auxiliary piezoelectric plate made of a quartz plate or the like having a predetermined size; FIG. In the auxiliary piezoelectric plate 10, for example, a plurality of openings 11 having a radius of r (4 in this embodiment).
Openings 11A, 11B, 11C, and 11D are pre-drilled.
0 is attached to the upper surface of the main piezoelectric vibration plate 20.

FIG. 2 shows a cross section when the auxiliary piezoelectric plate 10 and the main piezoelectric vibrating plate 20 are bonded and cut along Y'-Y 'as described above. This bonding is generally performed by bonding. For example, various types of commercially available adhesives such as an instant adhesive having a small surface tension can be used. Further, in the case of the present invention, a glass frit or the like is useful, but a method using a pressure welding method or various bonding methods using water bonding can also be applied.

The bonding of the auxiliary piezoelectric plate 10 and the main piezoelectric vibration plate 20 can be performed by cutting and bonding such that their crystal axes (x, y ', z') are in the same direction. This is important in securing stable frequency characteristics with respect to temperature changes. That is, in the case of a quartz plate, the linear expansion coefficients of the X axis and the Z axis are 13.41 × 10 ^{−6 /} ° C. and 7.48, respectively.
Since it is × 10 ⁻⁶ / ° C., which is almost twice as large depending on the crystal axis, the difference in the coefficient of thermal expansion causes deterioration of vibration characteristics due to distortion after manufacturing.

Next, after lamination, FIGS. 2 (A) and 2 (B)
Polished by A and B-sides simultaneously polishing machine (wrapping machine) as shown in, but scuffing amount R _e since opening 11 is provided mainly piezoelectric diaphragm 20 of the auxiliary piezoelectric plate 10 increases against the scuff amount of R _o. Therefore, as shown in FIG.
_e respect, the thickness h _o of the main piezoelectric vibrating plate 20 is set to be h _e> h _o, the thickness of the main piezoelectric diaphragm 20 when the total thickness of h _e + h _o is polished to a predetermined size There is so desired thickness becomes H _o. Opening 11 of auxiliary piezoelectric plate 10
The surface area, excluding the area A _e, the surface area of the main piezoelectric vibrating plate 20 is taken as _{A o, (A o / A} e) = (h e / h
It is presumed that the amount of wear (R) of both piezoelectric vibrating plates becomes the same by adopting _o ).

In general, in consideration of workability after polishing and polishing, it is considered that the thickness of the pasted piezoelectric vibrator before polishing is 0.1 mm to 0.5 mm in the prior art. Therefore, if you set the thickness of the main piezoelectric vibrating plate 20 so as to 0.02mm after polishing, A _o /
If _Ae is 4 in the above embodiment, the thickness of the auxiliary piezoelectric plate 10 is 0.08 mm. Therefore, A _o
In the case of / A _e = N, the thickness of the auxiliary piezoelectric plate 10 may be set to be N times the thickness of the main piezoelectric vibration plate 20.

However, in the final polishing or polishing step after completion, it is preferable that the total thickness be 0.1 mm to 0.5 mm in consideration of workability. Therefore, the dimension before double-side polishing is N = 4. In the case of, for example, it is conceivable to set the following values. Before polishing (h) After polishing (H) Polishing amount (R) Main piezoelectric vibrating plate 0.1mm 0.02mm 0.08mm Auxiliary piezoelectric plate 0.6mm 0.28mm 0.32mm

When processing is performed in the above-described embodiment, the initial total thickness dimension is 0.7 mm, and the main piezoelectric vibrating plate reaches 0.02 mm (20 μm) by polishing this bonded diaphragm. Since the total thickness at that time can be set to 0.3 mm, it can be easily handled as a vibrator that is not cracked or damaged in the subsequent adjustment processing, electrode processing, and sealing processing.

FIG. 3A shows a piezoelectric element wafer 30 after polishing of the pasted piezoelectric element as described above, and shows the thickness of the main piezoelectric vibrating plate 10, that is, the bottom surface of the opening 11. And those in which the thickness of the outer surface is polished to predetermined dimensions. The piezoelectric element wafer 30 is cut at each opening as shown by a dashed line, and (B)
As shown in FIG. 7, a plurality of piezoelectric element chips 30A are provided.
Then, the outer periphery of the piezoelectric element chip 30A is cut so as to have a circular shape (C), and in this state, fine adjustment polishing similar to that of a conventional vibrator is performed. Then, on the chip processed to generate the desired oscillation frequency, the electrodes 40 are formed on the bottom surface of the opening 11 and the bottom surface of the chip by vapor deposition or pasting as shown in FIG. The piezoelectric vibrator is completed.

FIG. 4 shows an embodiment in which a plurality of vibrators are formed on the piezoelectric element wafer 30. The electrode element 40 is vapor-deposited in each opening 11 in the state of the piezoelectric element wafer 30. It is a perspective view. In the case of this embodiment, when the double-side polishing is performed and the total thickness of the piezoelectric element wafer 30 reaches a predetermined dimension, for example, an electrode for measurement is inserted into one of the openings, and An oscillation circuit using the region as a vibrator is formed. Then, while measuring the oscillation frequency, the double-side polishing is repeated so that the oscillation frequency becomes a desired value, and the double-side polishing is stopped when the desired frequency is obtained.

By this fine polishing adjustment, the vibrator portion formed by the other opening can be regarded as a vibrator providing the same frequency. Therefore, as shown in FIG. The electrodes 40 are formed in the portions by using the printed wiring technology. Thereafter, as described above, the piezoelectric element wafer 30 is cut out around the openings 11 (A, B, C, and D) and processed to form the chip-shaped piezoelectric vibrator shown in FIG. . At the time of the frequency measurement, polishing may be performed by a dry edging method for each opening so that a more accurate vibration frequency may be obtained.

[0019]

As described above, the pasting type piezoelectric vibrator according to the present invention comprises a main piezoelectric vibrating plate having a specific thickness and an auxiliary piezoelectric plate having a plurality of openings perforated by a predetermined number. Since the two-side polishing is performed so that the piezoelectric element wafer in the bonded state has a desired thickness, the main piezoelectric vibration plate can be polished so as to have an extremely thin vibration frequency. An excellent effect that the operation becomes easy and the workability is improved can be obtained. In addition, since polishing can be performed in the state of the piezoelectric element wafer, there is an advantage that mass production is possible and cost can be reduced.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a production process of a pasted type piezoelectric vibrator of the present invention.

FIG. 2 is a cross-sectional view when an auxiliary piezoelectric plate and a main piezoelectric vibration plate are attached.

FIG. 3 is a diagram showing a piezoelectric element wafer that has been polished on both sides and a state of cutting out the piezoelectric element wafer.

FIG. 4 is a perspective view when electrodes are directly formed on a piezoelectric element wafer.

FIG. 5 is a structural view of a conventional micro crystal unit.

FIG. 6 is a sectional view of a vibrator using an inverted-mesa type piezoelectric element.

[Explanation of symbols]

 Reference Signs List 10 auxiliary piezoelectric plate 20 main piezoelectric vibration plate 11 opening 30 piezoelectric element wafer 40 electrode

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H03H 9/17 H03H 3/02

Claims (5)

(57) [Claims] 1. An opening is formed in a central portion., Surface area S
_Two , Its thickness is H _Two MadeAn auxiliary piezoelectric plate, made of the same material as the auxiliary piezoelectric plate, andSurface area S
₁ , Its thickness is H ₁ age,Its thickness is smaller than that of the auxiliary piezoelectric plate.
Main piezoelectric vibrating plate formed thinAnd Said surface area and
The thickness is H ₁ / H _Two = 1 (S _Two / S ₁ ) To 8 (S _Two / S ₁ ) And the respective crystal axes are almost the same.
So that The surface of the auxiliary piezoelectric plate and the surface of the main piezoelectric diaphragm are both
Polished to a predetermined size by a surface polishing machine,
The thickness of the main piezoelectric diaphragm has been adjusted to the desired size.
A method for producing a pasted piezoelectric vibrator, characterized by the following. 2. The at least two openings are formed.
2. The sticking form according to claim 1, wherein
A method for manufacturing a piezoelectric vibrator. (3)An opening is formed in the center and the surface area is S
_Two , Its thickness is H _Two An auxiliary piezoelectric plate, The auxiliary piezoelectric plate is made of the same material and has a surface area of S
₁ , Its thickness is H ₁ And the thickness is smaller than that of the auxiliary piezoelectric plate.
With the main piezoelectric diaphragm Said surface area and
The thickness is H ₁ / H _Two = 1 (S _Two / S ₁ ) To 8 (S _Two / S ₁ ) And the respective crystal axes are almost the same.
Like ,The surface of the auxiliary piezoelectric plate and the surface of the main piezoelectric diaphragm are both
Polished to a predetermined size by a surface polishing machine,
Formed so that the thickness of the main piezoelectric diaphragm is the desired size
A pasted type piezoelectric vibrator characterized by being performed. 4. At least two openings are formed.
4. The sticking form according to claim 3, wherein
Piezoelectric vibrator. 5. The pasted-type piezoelectric vibrator according to claim 3 , wherein electrodes are formed on a bottom surface of said main piezoelectric vibrating plate and a surface region corresponding to said opening by vapor deposition or the like.