JP3258070B2 - Crystal oscillator - Google Patents

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 resonator, and more particularly to a quartz substrate and a quartz piece which can be miniaturized.

[Prior art]

Description will be made below with reference to FIGS.

[0003] A quartz substrate 21 shown in FIG.
The 'axis' is an AT-cut quartz substrate made of an XZ' plane inclined at 35 ° to 40 ° from the Z axis about the X axis. For example, a convex-shaped crystal piece 23 as shown in FIG. 4 is taken out from the crystal substrate 21. The crystal piece 23 has an X axis in the longitudinal direction, a Z 'axis in the width direction, and a Y' axis in the thickness.

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 the thickness-shear vibration is composed of a displacement component parallel to the X-axis as shown by an arrow.

[0005] Normally, the oscillation frequency of these AT-cut quartz resonators is in the range of several MHz to 30 MHz as a fundamental wave, and overtones are used above that. In the fundamental wave region, the vibrator structure differs depending on the frequency band.

For example, as shown in a crystal piece 43 shown in FIG. 4, a convex shape (lens shape) or a bevel shape is used in a few MHz band, energy is confined at the center of the plate surface, and vibration loss is reduced. On the other hand, the vibration frequency is 15 MHz
In the above, since the thickness is thin, a convex shape is unnecessary, and a predetermined characteristic can be obtained only with a rectangular plate shape.

[0007]

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

In response to these demands, when the size and the frequency of the crystal unit are reduced, the size of the container is, of course, reduced, but the production of a crystal piece is not easy. For example, a vibrator with a vibration frequency of several MHz has a convex shape or bevel shape as shown in Fig. 4. The processing method is to process a plate-shaped quartz piece, mix the abrasive grains and the quartz piece in a cylindrical vessel, and rotate the vessel. A method is used in which the edge is cut off.

However, in this processing method, the processing time is as long as several tens of hours, and the surface is rough. In addition, the thickness (Y 'axis), at which the vibration frequency is determined, has large variations, and since the thickness is corrected by chemical etching, the overall dimensions also have large variations. Therefore, if the size is reduced, the variation in characteristics is further increased.

On the other hand, in a high-frequency vibrator having a vibration frequency of 15 MHz or more, the frequency is determined by the thickness as described above. For this reason, the thickness of the quartz substrate 21 shown in FIG. 2 is less than 100 microns, but this processing is extremely difficult.

Taking advantage of the thinner point, photolithography and etching should be used for the shape processing. However, in chemical etching, since the thickness direction of the quartz substrate 21 is the Y 'axis, the etching rate is extremely low. . For this reason, shape processing by chemical etching is extremely difficult.

Further, when photolithography and etching are employed, the smaller the crystal blank and the larger the size of the substrate, the more the crystal piece can be taken out from one substrate. However, since the AT-cut quartz crystal uses Y-bar artificial quartz, there is a problem that the size of the quartz substrate 21 cannot be increased.

Further, when the size of the crystal blank is reduced, the following problem occurs.

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

However, the crystal piece 43 forms an electrode film 45, and has a structure floating in space when assembled in a container. Generally, the end of the crystal piece 43 is supported and fixed with a conductive adhesive. However, as described above, it is difficult to automatically assemble a crystal having a size of about several mm.

As described above, the crystal oscillator is required to be further reduced in size and higher in frequency. However, it is difficult to process the thin plate of the crystal substrate 21 shown in FIG. 2 in the thickness direction in which the oscillation frequency is determined. It is difficult to increase the frequency. In addition, if the substrate is reduced in size, it is difficult to employ photolithography and etching, so that there is a problem that a framed irregular shaped crystal advantageous for the support structure cannot be formed.

An object of the present invention is to solve the above-mentioned problems and to produce a quartz oscillator from a large quartz substrate, to which photolithography and etching can be applied, and furthermore, to make it easy to assemble into a container. An object of the present invention is to provide a small crystal resonator.

[0018]

In order to achieve the above object, the present invention employs the following construction.

The quartz resonator according to the present invention comprises a crystal substrate cut out of a rough quartz crystal, one side of which is an X axis, and a Y 'axis which is inclined by 30 to 40 with the Y axis directed to the Z axis about the X axis. It is composed of an XY 'plane crystal substrate, and the vibration frequency of a crystal piece formed from 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 resonator in a conventional example.
′ Axis, that is, the thickness of the quartz substrate 21,
Is formed on a plane of the quartz substrate 21 parallel to the Z ′ axis.
However, the quartz piece 23 is a quartz substrate 27 indicated by a dashed line.
, And the present invention focuses on this point.

[0021]

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

The quartz substrate 11 is an XY 'plane substrate whose Y axis is inclined by 30.degree. To 40.degree. Around the X axis toward the Z axis. This is the same content as the crystal substrate 27 in FIG.

However, there is a great difference. The quartz substrate 21 shown in FIG. 2 is cut out from a Y-bar artificial quartz, but the quartz substrate 11 shown in FIG. 1 in the present invention can be cut out from a Z-plate artificial quartz. The difference between the two is that
The other points are basically the same as the Y-bar artificial quartz in that the dimensions are large. However, the fact that a Z-plate quartz crystal having a large area can be used for manufacturing a vibrator is a great merit such as application of photolithography and etching.

The quartz piece 13 formed on the quartz substrate 11 can be machined as long as it is rod-shaped, but photolithography and etching are optimal. That is, since the vibration frequency is determined by the width dimension (w) in the Y′-axis direction, when the width dimension is determined, the width dimension may be set to the plane of the quartz substrate 11. Any external shape can be obtained by photolithography.

The electrode film 15 is formed on both sides of the crystal blank 13 which is the XZ 'plane to excite the crystal blank 13.

Further, the etching rate in the chemical etching, which has been a problem in the prior art, is substantially the same as that of the tuning-fork type quartz resonator because the quartz substrate 11 is a Z plate, and the problem is solved.

In the present invention, photolithography and etching are not limited to chemical etching, but may be a method using a masking material such as dry etching such as reactive ion etching or injection processing using fine powder such as silicon carbide. All applicable.

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

The support 35 is formed integrally with the frame 31, and the width of the support 35 is reduced to about several tens of microns.

The dimension widths in the X direction and the Z 'axis direction are determined according to the specifications in consideration of the characteristics of the vibrator. However, since the Z ′ axis dimension is the thickness of the quartz substrate 11 in FIG.
00 microns is practical. However, since the thickness variation does not affect the frequency, the processing of the quartz substrate 11 becomes easy.

The electrode film 37 is formed on the side surface of the crystal piece 33, and the lead electrode 39 is formed on the main surface. This crystal resonator is similar to the AT-cut crystal resonator, and vibrates while being displaced in the X-axis direction as indicated by an arrow. In the embodiment shown in FIG.
Although the shape of the crystal piece is a convex shape, it may be a bevel shape or a rod shape.

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

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

As shown in FIG. 7A, a quartz substrate 70 cut from a rough quartz crystal at a predetermined angle is subjected to a lapping method.
Alternatively, it is polished to a predetermined thickness.

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

Thereafter, using the masking material 71 as a mask, a chemical etching method using hydrofluoric acid or the like, or CF
Reactive ion etching with a fluorine-based gas such as ₄ or SF _6, or by a processing method for injecting a fine powder of several microns, such as silicon carbide, as shown in FIG. 7 (c), the thickness of the quartz substrate 70 Processing direction.

Next, as shown in FIG. 7D, the masking material 71 is removed, and thereafter, the thin film 73 serving as the electrode film 37 and the extraction electrode 39 on the side surface shown in FIG. Formed with a thickness of

Thereafter, a photoresist 7 is formed on the quartz substrate 70.
5 is formed. Thereafter, 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 quartz substrate 70,
It can also be formed by a vacuum evaporation 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 can be used for forming the electrode film. In the manufacturing process described above, description of frequency adjustment and the like is omitted.

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

The quartz resonator of the present invention shown in FIG. 5 is basically similar to the one shown in FIG. 1, and is a quartz substrate 51 made of Y'Z '. In this case, the thickness is in the X-axis direction. However, the Y'-axis direction is the quartz substrate 1 of FIG.
1 and the frequency of the crystal blank 53 is
1 in the Y′-axis direction. Other manufacturing methods and the like are almost the same as those described for the Z-plate quartz crystal.

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

As shown in FIG. 8, the crystal piece 81 has a rod shape, and an electrode film 83 is formed on the side surface. 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 of the support portion 89 is smaller than that of the crystal piece 81.

[0047]

As is apparent from the above description, since the thickness-sliding quartz crystal resonator according to the present invention can employ a Z-plate artificial quartz, a large quartz crystal substrate can be formed. The thickness direction of the quartz substrate is the direction in which the etching rate in chemical etching is high, and the frequency and various shapes of quartz and vibrator can be configured on the flat part of the substrate, so that it can be processed with high precision and the thickness of the quartz substrate Since it is not involved in the vibration frequency, the crystal substrate and the crystal resonator are most suitable for photolithography, etching, and blasting because they are easy to process. In addition, because the processing accuracy is good,
Variations in the manufacturing process are reduced, and a highly stable vibrator with little change over time can be easily produced, and the effect is extremely large.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a structure of a quartz substrate according to an embodiment of the present invention.

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

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

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

FIG. 5 is a perspective view showing a quartz 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 illustrating a manufacturing method for forming the structure of the crystal resonator according to the embodiment of the present invention.

FIG. 8 is a perspective view showing a thickness-slip quartz crystal resonator according to another embodiment of the present invention.

[Explanation of symbols]

 11 crystal substrate 13 crystal piece 15 electrode film

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-61-30736 (JP, A) JP-A-53-84592 (JP, A) JP-A-52-137991 (JP, A) JP-A 52-17991 90289 (JP, A) JP-A-54-43489 (JP, A) JP-A-2-30635 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H03H 9 / 00-9 / 215 H03H 9/54-9/60

Claims (2)

(57) [Claims] 1. A quartz resonator having a thickness shear vibration.
There are, quartz substrate of the crystal oscillator, the side is referred to as an X-axis, further the X-axis 30 ° angle θ toward the Y axis to the Z axis around a 40
DEG consisting board of XY' plane consisting Y'-axis is tilted, the electrode film for excitation is formed on XZ' surface, to vibrate the crystal oscillator field added to the Y'-axis direction
Crystal oscillator, characterized in that that. 2. A quartz resonator having a thickness shear vibration.
There are, quartz substrate of the crystal oscillator, the side is referred to as an X-axis, further wherein X
Shaft center to be the Y-axis from the base plate of Y'Z' plane consisting Y'-axis angle θ is tilted 30 ° to 40 ° toward the Z-axis, the electrode film for excitation formed XZ' surface and, it is not vibrate the crystal oscillator field added to the Y'-axis direction
Crystal oscillator, characterized in that that.