JPH05259800A - Crystal vibrator - Google Patents

Abstract

PURPOSE:To attain processing with high accuracy by forming a crystal from a XY' plane crystal substrate with respect to a Y' axis in which the Y axis is tilted by a specific angle in the Z axis direction around one side X axis of the crystal substrate, deciding the vibration frequency with the width in the Y' axis direction and forming the exciting electrode film onto the XZ' plane. CONSTITUTION:One side of a crystal substrate 11 cut off from a crystal ore is takes as the X axis, and the Y' axis is taken by tilting the Y axis toward the Z axis by 30-40 deg. around the X axis and the substrate is in parallel with the XY' plane. The photolithography or the etching processing is optimum to manufacture the crystal chip 13 formed to the substrate 11 and since the vibration frequency depends on the width W in the direction of the Y' axis, any shape is formed on the substrate 11. The electrode film 15 is formed to both side faces being the XZ' planes of the crystal chip 13, the crystal chip 13 is excited, and the speed of the chemical etching is nearly equal to that of a tuning fork crystal vibrator because the Z plate is used for the substrate 11. Since the vibration frequency depends on the width and the outer shape is formed flat, the crystal is processed with high accuracy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thickness-sliding quartz crystal unit, and more particularly to a quartz substrate and a quartz piece which can be made extremely small.

[Prior Art]

A description will be given below with reference to FIGS. 2 and 4.

One piece of the crystal substrate 21 shown in FIG.
The'-axis is an AT-cut quartz crystal substrate composed of an XZ 'plane tilted about the X-axis by 35 ° to 40 ° from the Z-axis. For example, a convex crystal piece 23 as shown in FIG. 4 is taken out from the crystal substrate 21, and the crystal piece 23 has a longitudinal direction of X axis, a width direction of Z ′ axis, and a thickness of Y ′ axis.

At this time, the excitation electrode is formed on the plane of the quartz substrate 21 having a thickness in the Y'axis direction, and this thickness shear vibration is composed of a displacement component parallel to the X axis as indicated by an arrow.

Generally, the vibration frequency of these AT-cut quartz crystal resonators is in the range of several MHz to 30 MHz in terms of the fundamental wave, and overtone is adopted above that. Further, in the fundamental wave region, the oscillator structure differs depending on the frequency band.

For example, like the crystal piece 43 shown in FIG. 4, in the several MHz band, it is formed into a convex shape (lens shape) or a bevel shape, and energy is confined in the center of the plate surface to reduce vibration loss. On the other hand, the vibration frequency is 15MHz
In the above, since the thickness is thin, the convex shape is unnecessary, and the predetermined characteristics can be obtained only with the rectangular plate shape.

[0007]

In recent years, various electronic products using crystal applied products have become more and more portable, and are becoming smaller, thinner and more sophisticated. Therefore, the crystal unit is not only small and thin, but also highly stable,
High frequency and surface mounting (SMD) are required.

In response to these requirements, when the crystal unit is miniaturized and the frequency is increased, it goes without saying that the container is also miniaturized, but it is not easy to make the crystal piece. For example, for a vibrator with a vibration frequency of several MHz, the convex shape or bevel shape shown in Fig. 4 is used. The processing method is to machine a plate-shaped crystal piece and then mix the abrasive grains and the crystal piece in a cylindrical container and rotate the container. Then, a method of scraping the end is used.

However, in this processing method, the processing time is as long as several tens of hours, and the surface roughness is rough. Moreover, the thickness (Y ′ axis) where the vibration frequency is determined has a large variation, and since the thickness is corrected by chemical etching, the overall dimension also has a large variation. Therefore, if the size is reduced, the variation in the characteristics is further increased.

On the other hand, in a high frequency oscillator having a vibration frequency of 15 MHz or more, the frequency is determined by the thickness as described above. Therefore, the crystal substrate 21 shown in FIG. 2 has a thickness of 100 microns or less, but this processing is extremely difficult.

Taking advantage of the thinner thickness, it is desired to adopt photolithography and etching for shape processing. However, in chemical etching, since the thickness direction of the quartz substrate 21 is the Y'axis, the etching rate is extremely slow. .. For this reason, shape processing by chemical etching is extremely difficult.

Further, when the photolithography and the etching process are adopted, the smaller the crystal piece and the larger the size of the substrate are, the larger the number of crystals that can be taken out from one substrate is. However, since the AT-cut crystal unit uses the Y rod artificial crystal, there is a problem that the size of the crystal substrate 21 cannot be increased.

Further, if the crystal piece is miniaturized, the following problems will occur.

As shown in FIG. 4, for example, when the frequency of the crystal piece 43 is 12.8 MHz, the thickness is calculated to be 130 microns, and the length and width are about several mm in consideration of the characteristics.

However, the crystal piece 43 has a structure in which the electrode film 45 is formed and floats in the space when assembled in a container. Generally, the end portion of the crystal piece 43 is supported and fixed by a conductive adhesive, but as described above, automatic assembly is difficult when the size is about several mm.

As described above, the crystal unit is required to be smaller and higher in frequency, but it is difficult to machine the thin plate of the crystal substrate 21 shown in FIG. 2 in the thickness direction where the vibration frequency is determined. It is difficult to get high frequency. Furthermore, if the size of the substrate is reduced, it is difficult to use photolithography and etching, so that a deformed crystal with a frame, which is advantageous for a supporting structure, cannot be formed.

An object of the present invention is to solve the above problems, to make a crystal unit from a large-sized crystal substrate, to which photolithography and etching processes can be applied, and further to make it easy to assemble into a container. It is to provide a small crystal unit.

[0018]

In order to achieve the above object, the present invention adopts the following constitution.

The crystal unit of the present invention comprises a crystal substrate cut out from a raw quartz stone, one side of which is the X axis, and further a Y ′ axis which is inclined about 30 to 40 with the Y axis as the Z axis. It is characterized in that the vibration frequency of the crystal piece made of the XY 'plane substrate is determined by the dimension width in the Y'axis direction, and the electrode film for excitation is formed on the XZ' plane. ..

[0020]

FIG. 2 is a perspective view for explaining an AT-cut quartz crystal resonator according to the conventional example. The vibration frequency of the quartz piece 23 is Y.
Axis, that is, determined by the thickness of the crystal substrate 21, the electrode film 25
Are formed on the plane of the quartz substrate 21 parallel to the Z ′ axis.
However, the crystal piece 23 is a crystal substrate 27 indicated by a chain line.
The present invention is focused on this point, since it is understood that the configuration is within the range.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing a crystal substrate of a crystal unit of the present invention.

The crystal substrate 11 is an XY 'plane substrate in which the Y axis is inclined 30 ° to 40 ° with respect to the Z axis with respect to the Z axis. This is the same content as the crystal substrate 27 of FIG.

However, there is a big difference in that the crystal substrate 21 of FIG. 2 is cut out from the Y rod artificial crystal, but the crystal substrate 11 shown in FIG. 1 of the present invention can be cut out from the Z plate artificial crystal. The difference between the two is that the Z plate artificial crystal is X
Others are basically the same as the Y-bar synthetic quartz in that the size is large. However, the ability to use a large-area Z-plate crystal for manufacturing a vibrator is a great merit such as the application of photolithography and etching.

The crystal piece 13 formed on the crystal substrate 11 can be machined if it is rod-shaped, but photolithography and etching are most suitable. That is, since the vibration frequency is determined by the width dimension (w) in the Y′-axis direction, once the width dimension is determined, the width dimension may be set on the plane of the crystal substrate 11. The outer shape can be any shape by photolithography.

The electrode films 15 are formed on both side surfaces of the crystal blank 13 which are XZ 'planes to excite the crystal blank 13.

Furthermore, since the quartz substrate 11 is the Z plate, the etching rate in the chemical etching, which has been a problem in the past, is almost the same as that of the tuning fork type crystal resonator, and the problem is solved.

In the present invention, photolithography and etching are not limited to chemical etching, but dry etching such as reactive ion etching or jetting with fine powder such as silicon carbide can be used for processing with a masking material. All are applicable.

A concrete embodiment of the thickness-sliding quartz crystal resonator according to the present invention will be described with reference to the perspective view of FIG.

The crystal piece 33 has a convex shape in the conventional name. The vibration frequency is determined by the dimension width in the Y'axis direction. Therefore, for example, at the vibration frequency of 12.8 MHz, the dimension width in the Y'axis direction is about 130 microns.

The support portion 35 has an integral structure with the frame 31, and the width of the support portion 35 is made as thin as several tens of microns.

The dimensional widths in the X-direction and Z'-axis direction are determined by the specifications in consideration of the oscillator characteristics. However, since the Z′-axis dimension is the thickness of the quartz substrate 11 in FIG.
00 microns is practical. However, since the variation in thickness does not affect the frequency, the crystal substrate 11 can be easily processed.

The electrode film 37 is formed on the side surface of the crystal piece 33, and the extraction electrode 39 is formed on the main surface. This crystal oscillator is similar to the AT-cut crystal oscillator, and is displaced and vibrated in the X-axis direction as shown by the arrow. In the embodiment shown in FIG.
Although the crystal piece has a convex shape, it may have a bevel shape or a rod shape.

A method of manufacturing the crystal unit according to the present invention as shown in FIG. 3 will be briefly described below with reference to FIGS. 6 and 7. FIG. 6 is a plan view of the crystal substrate 11 shown in FIG.
The thickness is set to the Z ′ axis, and a plurality of thickness-sliding quartz crystal resonators are created in the X and Y ′ directions.

The manufacturing process will be described with reference to the sectional view of FIG.

As shown in FIG. 7A, a quartz substrate 70 cut out from a rough quartz stone at a predetermined angle is lapped.
Alternatively, a polishing finish is performed to a predetermined thickness.

Next, as shown in FIG. 7B, a masking material 71 having the shape of the crystal piece 33 or the frame 31 as shown in FIG. 3 is patterned on the crystal substrate 70. The masking material 71 is formed on one side or both sides of the crystal substrate 70 by the crystal processing method. The material of the masking material 71 is a metal thin film or a photoresist.

Then, using the masking material 71 as a mask, a chemical etching method using hydrofluoric acid or the like, or CF
_As shown in FIG. 7C, the thickness of the quartz substrate 70 is changed by a reactive ion etching method using a fluorine-based gas such as ₄ or SF ₆ or a processing method of injecting fine powder of several microns such as silicon carbide. Process the direction.

Next, as shown in FIG. 7 (d), the masking material 71 is removed, and then the electrode film 37 on the side surface portion shown in FIG. Formed with a thickness of.

Then, the photoresist 7 is applied to the quartz substrate 70.
5 is formed. Then, the thin film 73 is etched using the photoresist 75 as an etching mask.

The electrode film 37 and the extraction electrode 3 shown in FIG.
9 is formed by disposing a metal mask on the crystal substrate 70,
It can also be formed by a vacuum vapor deposition method or a sputtering method.

Next, as shown in FIG. 7F, if the photoresist 75 remains, it can be removed to form an electrode.

The manufacturing process described above is an example,
A lift-off method or the like is also possible for forming the electrode film and the like. In the manufacturing process described above, description of frequency adjustment and the like is omitted.

Although the crystal resonator of the present invention has been described from the crystal substrate 11 in FIG. 1, another embodiment of the present invention will be described with reference to FIG.

The crystal resonator of the present invention shown in FIG. 5 is basically similar to the invention of FIG. 1, and is a crystal substrate 51 made of Y'Z '. In this case, the thickness is in the X-axis direction. However, the crystal substrate 1 of FIG.
Since the frequency of the crystal piece 53 is the same as that of the crystal board 5,
It is determined by the width of 1 in the Y′-axis direction. Other manufacturing methods are substantially the same as those described for the Z-plate crystal.

FIG. 8 is a perspective view showing a thickness sliding crystal oscillator according to another embodiment of the present invention.

As shown in FIG. 8, the crystal piece 81 is rod-shaped and has an electrode film 83 formed on its side surface, and the electrode film 83 is connected to the lead electrode 87 on the main surface. The crystal piece 81 and the frame 85 have an integral structure, and the width dimension of the support portion 89 is made thinner than the crystal piece 81.

[0047]

As is apparent from the above description, since the Z-plate synthetic quartz crystal can be adopted in the thickness sliding crystal oscillator according to the present invention, a large-sized quartz crystal substrate can be formed. The thickness direction of the crystal substrate is the direction in which the etching rate in chemical etching is high, and the frequency of the crystal and the oscillator and various shapes can be configured on the flat surface of the substrate, which enables highly accurate processing and the thickness of the crystal substrate. Is a crystal substrate and crystal oscillator that are optimal for photolithography, etching, and jetting because they do not affect the vibration frequency and are easy to process. In addition, since the processing accuracy is good,
The variation in the manufacturing process is reduced, and furthermore, a highly stable oscillator with little change over time can be easily produced, and the effect is extremely large.

[Brief description of drawings]

FIG. 1 is a perspective view showing a structure of a quartz substrate in an example of the present invention.

FIG. 2 is a perspective view showing a quartz substrate in a conventional example and an example of the present invention.

FIG. 3 is a perspective view showing a thickness-sliding quartz crystal resonator according to an embodiment of the present invention.

FIG. 4 is a perspective view showing a thickness-sliding quartz crystal resonator in a conventional example.

FIG. 5 is a perspective view showing a crystal substrate according to another embodiment of the present invention.

FIG. 6 is a plan view showing a quartz substrate in an example of the present invention.

FIG. 7 is a cross-sectional view showing the manufacturing method for forming the structure of the crystal resonator in the example of the present invention.

FIG. 8 is a perspective view showing a thickness sliding crystal oscillator according to another embodiment of the present invention.

[Explanation of symbols]

 11 crystal substrate 13 crystal piece 15 electrode film

Claims (2)

[Claims] 1. A crystal substrate, which is cut out from a raw quartz crystal, has one side as an X-axis, and the Y-axis is centered on the X-axis and directed toward the Z-axis.
It consists of a crystal substrate of XY 'plane composed of Y'axis inclined by -40, and the vibration frequency of the crystal piece made from the XY' plane substrate is determined by the dimension width in the Y'axis direction, and the electrode film for excitation is XZ. A crystal unit characterized by being formed on the surface. 2. A Y'Z 'plane composed of a Y'axis which has one side of a quartz substrate cut out from a raw quartz stone as an X axis, and is further tilted about the X axis by 30 to 40 degrees from the Y axis to the Z axis. And a vibration frequency of a crystal piece formed from a Y'Z 'plane substrate is determined by the dimension width in the Y'axis direction, and an electrode film for excitation is formed on the XZ' plane. Oscillator.