JPH0241924B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a longitudinally vibrating piezoelectric vibrator, in which a main vibrating part that vibrates longitudinally and a supporting part of the main vibrating part are integrally formed by photoetching.

Conventionally, a longitudinal vibration type piezoelectric vibrator as shown in FIG. 1 has been used as a piezoelectric vibrator for a frequency band of several 100 KHz to around 1 MHz. FIG. 1 is a perspective view, in which an oscillating piece 1 having electrodes 2 and 3 formed on its front and back surfaces is fixedly supported at the center of gravity of the oscillating piece 1 by soldering to thin hanging wires 4 and 4'. shows.
The vertical vibration type piezoelectric vibrator has the following characteristics: 1. There are large variations in CI value, vibration leakage, etc. due to variations in the positional accuracy and solder amount of fixing and supporting the oscillating piece on the hanging wire, 2. The connection strength between the hanging wire and the oscillating piece is weak. 3. Fixing and supporting the hanging wire and the oscillating piece requires skill, resulting in high manufacturing costs; and 4. The shape of the hanging wire makes the container large.

Another conventional example of a longitudinal vibration type piezoelectric vibrator is shown in a perspective view in FIG. In the figure, the longitudinally vibrating piezoelectric vibrator of this example has a main vibrating part 5 that vibrates vertically, connecting parts 6, 6', and supporting parts 7, 7' that are integrally formed by photoetching, and furthermore, It is supported by a fixing part 8 which is a separate member shaped like a tuning fork.

Furthermore, a conventional example of a vertical vibration type piezoelectric vibrator produced by another photoetching process is shown in a perspective view in FIG. 3A. In the figure, the longitudinal vibration type piezoelectric vibrator of this example includes a main vibrating part 9, double frames 10 and 11 surrounding the main vibrating part 9, and a connecting part 1 connecting them.
2, 12', 13, and 13' are integrally formed by photo-etching.

All of the three conventional examples described above employ various measures to suppress the leakage of main vibration energy, but the effects are not sufficient, and they also have drawbacks in terms of manufacturing cost and dimensions. There is.

The applicant has solved the conventional drawbacks mentioned above,
We have previously applied for a longitudinal vibration type piezoelectric vibrator with a structure that suppresses leakage of main vibration energy and is suitable for downsizing and cost reduction.

The first embodiment is shown in a perspective view in FIG. 4A. In the figure, the present invention includes a main vibrating part 14 that vibrates longitudinally, connecting parts 15 and 15' provided in the width direction of the main vibrating part 14 at a position where the vibration displacement of the main vibrating part 14 is the smallest, A supporting portion 1 is connected from both ends of the connecting portions 15, 15' in parallel with one of the main vibrating portions 14.
6 and 16' are extended, and the support parts 16 and 16' are provided with a base part 17 so that the support part excluding the main vibrating part 14 constitutes a tuning fork shape, and the length L of the base part 17 is set to correspond to the tuning fork arm. 2 of the width W of the supporting parts 16, 16'
This is a longitudinal vibration type piezoelectric vibrator having the above configuration, which is more than twice as large. In this example, the longitudinal vibration type piezoelectric vibrator is such that the supporting part and the connecting part corresponding to the tuning fork arms perform bending vibration in response to the vibration in the short side direction caused by the longitudinal vibration of the main vibrating part. . The longitudinal vibration type piezoelectric vibrator has a tuning fork shape in the part that supports the main vibrating part, so it has a structure suitable for downsizing and cost reduction, and has the advantage of effectively suppressing leakage of vibration energy. ing. By the way, in the conventional longitudinal vibration type piezoelectric vibrator shown in FIGS. 2 and 3, for example, as shown in FIG. 3B, the Z
The plate was rotated 20° to 45° around the Y axis and -5° to +5° around the X' axis (not shown), and was formed by photoetching from a so-called NT cut crystal wafer. ing. For excitation of longitudinal vibration, an electric field E is generated by two electrodes 18 and 19 formed on the front and back sides of the main vibrating section 9, that is, on the Z' plane.
The X component Ex of the electric field E becomes an effective component for excitation, and is directed in the Y-axis direction, that is, in the length direction of the main vibrating section 9. Therefore, the configuration is such that only the conductive thin films formed on the front and back surfaces of the piezoelectric wafer can serve as both a corrosion-resistant film and an electrode film during etching of the external shape. On the other hand, in the longitudinal vibration type piezoelectric vibrator shown in FIG. It is formed by photo-etching so that the width direction is the X axis and the length direction is the Y axis. FIG. 4B is a cross-sectional view taken along Q-Q' in FIG. , 21 are formed on a plane perpendicular to the X-axis, that is, on a side surface of the main vibration section 14. Therefore, compared to other conventional longitudinal vibration type piezoelectric vibrators shown in Figs. 2 and 3, it has the advantage of high electric field excitation efficiency. This method has the drawback that it is necessary to form electrodes at the same time.
A so-called masking method is generally used to form electrodes on the side surfaces. FIG. 5 is an explanatory diagram of the masking method. In the same figure,
22 is a longitudinal vibration type piezoelectric vibrator, which includes a main vibration part 23, connecting parts 24, 24', connecting parts 25, 25', and a base part 26.
Electrodes 27 and 28 are formed on the surface of the conductive thin film. Reference numeral 29 denotes a frame for connecting a plurality of vertically vibrating piezoelectric vibrators 22 on the same wafer, and the frame 29 and the vertical piezoelectric vibrators 22 are coupled by a coupling portion 30 .
The electrodes are formed on the side surface of the main vibrating section 23 by using a mask 103 having openings 101 and 102 for forming a conductive thin film in close contact with the longitudinal vibrating piezoelectric vibrator 22. A conductive thin film can be sputtered to form side electrodes that are electrically connected to previously formed planar electrodes 27, 28. Further detailed explanation of electrode formation is shown in the cross-sectional view of FIG.
A to H in the figure indicate the order of processing steps, and A to H in the figure
3 is a step of forming conductive thin films 32, 32' that are resistant to corrosion against the etching solution of the piezoelectric wafer on the front and back surfaces of the piezoelectric wafer 31, and FIG. A step of forming photoresists 33, 33' in the external shape of a vibrating piezoelectric vibrator, C in the figure shows photoresists 33, 33'
The process of etching the conductive thin films 32, 32' into the external shape of a vertical vibrator using the conductive thin films 32, 32' as anti-corrosion films is shown in FIG. The process of etching the photoresists 33, 33' in the shape of planar electrodes is shown in FIG.
1 is a process of etching the conductive thin films 32, 32' into a planar electrode shape using the photoresists 33, 33' as anti-corrosion films;
The step of peeling off the mask 33', H in the same figure shows the mask 36, 3.
6' is a step of forming side electrodes 35, 35' by the above-described masking method. Incidentally, in the order of the processing steps described above, it is also possible to perform the step of forming the photoresists 33, 33' having the electrode shapes shown in FIG. 6E after the step shown in FIG. 6C. The side electrode forming method using the conventional masking method described above has the following drawbacks.

1. The piezoelectric vibrator and the mask must be aligned with a misalignment accuracy of 10 μm or less, and furthermore, both must be placed in close contact with each other in the thin film forming apparatus, which requires a lot of manufacturing man-hours.

2. If alignment accuracy is not ensured, thin film adhesion to the shot or side surface between the two electrodes will be insufficient, resulting in a decrease in processing yield. Further, variations in characteristics are likely to occur.

Therefore, the present invention aims to eliminate such drawbacks, and its purpose is to provide a method for manufacturing a longitudinal vibration type piezoelectric vibrator that facilitates electrode formation and can be manufactured at low cost. It is in.

The gist of the method for manufacturing a longitudinally vibrating piezoelectric vibrator according to the present invention is to produce a longitudinally vibrating piezoelectric vibrator in which a main vibrating part that vibrates longitudinally and a supporting part of the main vibrating part are integrally formed by photo-etching. In the manufacturing method, a step of etching a piezoelectric wafer into the external shape of the vertical vibration type piezoelectric vibrator, a step of forming a conductive thin film on substantially the entire surface of the vertical vibration type piezoelectric vibrator, and a step of etching the piezoelectric wafer into the external shape of the vertical vibration type piezoelectric vibrator, It is characterized by comprising a step of etching a part of the electrode to form an electrode.

Embodiments of the present invention will be described in detail below based on the drawings. FIG. 7 shows a cross-sectional view of an embodiment of the present invention. In this figure, the processing steps shown in FIGS. 6A to 6D showing the conventional example described above, that is, the step of etching a piezoelectric wafer into the external shape of a piezoelectric vibrator, are omitted because they are the same, and the processing steps related to the present invention are omitted. E
~H. The figure E shows the step of forming a conductive thin film 37 on almost the entire surface of the vibrator part (indicated by the main vibrating part 31 in the figure) which has been etched into the external shape, and the figure F shows the photoresist 38, 38' in the shape of electrodes. G in the figure is a step of etching the conductive thin films 32, 32', 37 using the photoresists 38, 38' as corrosion-resistant films;
H in the figure is a step of peeling off the photoresists 38, 38'. Incidentally, in the order of the processing steps described above, the step of forming the conductive thin film 37 shown in FIG. 7E may be performed after the conductive thin films 32, 32' are peeled off in advance. According to the above processing steps, the following advantages can be obtained.

1. Manufacturing costs can be reduced because there is no need for complicated mask alignment and only a photo etching process is required.

2. Since the electrodes are formed by a photo-etching process, the shape accuracy is good and there is little variation in characteristics. Furthermore, in the manufacturing method of the present invention, it is necessary to form a photoresist on the side surface as shown in FIG. This can be easily achieved by In the embodiments of the present invention, a vertically vibrating piezoelectric vibrator using a Z-plate of a quartz crystal plate has been described, but in a vertically vibrating piezoelectric vibrator using another crystal plate, the supporting portion is shaped like a tuning fork. The present invention can be applied to any longitudinal vibration type piezoelectric vibrator that has a main electrode on its side surface. Regarding the conductive thin films 32, 32', 37,
Although the illustration shows a single layer, it is also possible to apply the invention to multilayer films such as two or three layers.

[Brief explanation of drawings]

FIGS. 1 to 3 show a conventional example of a longitudinal vibration type piezoelectric vibrator. FIG. 4 shows an example of a longitudinal vibration type piezoelectric vibrator that was filed in the applicant's earlier application. FIG. 5 is an explanatory diagram of a masking method for forming side electrodes on the longitudinal vibration type piezoelectric vibrator shown in FIG. 4. FIG. 6 is a more detailed explanatory diagram of FIG. 5. FIG. 7 shows an embodiment of the present invention. 14... Main vibration part, 15... Connection part, 16...
Support part, 17... Base, 20, 21... Electrode, 2
2... Longitudinal vibration type piezoelectric vibrator, 23... Main vibration part,
24... Connection portion, 25... Support portion, 26... Base, 27, 28... Electrode, 29... Frame, 30...
Bonding portion, 31... Piezoelectric wafer, 32... Conductive thin film, 33... Photoresist, 35... Side electrode, 36... Mask, 37... Conductive thin film, 38
... Photoresist, 101, 102 ... Opening, 103 ... Mask.

Claims (1)

[Claims] 1 From the crystal wafer, which rotates the Z plate of the crystal plate in the range of -5° to +5° around the In a method for manufacturing a longitudinal vibration type piezoelectric vibrator whose parts are integrally formed by photoetching,
etching a longitudinally vibrating piezoelectric vibrator from the crystal wafer using the first conductive thin film as a mask, in which the length in the width direction of the main vibrating part is shorter than the length in the thickness direction, which is the etching direction; forming a second conductive thin film on almost the entire surface of the main vibrating section including the first conductive thin film; 1. A method for manufacturing a longitudinally vibrating piezoelectric vibrator, comprising the steps of forming side electrodes facing each other by etching along the direction.