JP2002141760A - Crystal oscillator - Google Patents

Abstract

(57) [Summary] [Object] To provide a crystal resonator that can easily adjust a vibration frequency and increase productivity. The present invention has a configuration in which an ionized element is injected from a main surface of a crystal blank and the vibration frequency of the crystal blank is adjusted from a higher frequency to a lower frequency by adding the mass of the element. Further, an ionized element is implanted from the main surface of the quartz piece to form an amorphized layer, and the amorphized layer is reduced by etching to adjust the vibration frequency of the quartz piece from a lower one to a higher one. Configuration. Further, an amorphized layer is formed on the main surface of the crystal blank, and the vibration frequency of the crystal blank is adjusted from low to high by reducing the amorphized layer by etching.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an industrial technical field of a high-frequency crystal resonator, and more particularly, to a mass-added layer obtained by implanting an ionized element (hereinafter referred to as an ionized element) into a main surface of a crystal blank. Alternatively, the present invention relates to a crystal resonator in which an amorphized layer including vapor deposition or the like is provided to facilitate frequency adjustment.

[0002]

2. Description of the Related Art Quartz resonators are used in various electronic devices, including communication devices, as oscillators serving as frequency and time reference sources and as filter elements for passing only predetermined frequency ranges. . In recent years, a crystal resonator having a vibration frequency of, for example, 100 MHz or more has been demanded by information communication such as digitization.

(Example of Prior Art) FIGS. 10 and 11 are views for explaining a conventional example. FIG. 10 is a cross-sectional view of a crystal unit, and FIG. 11 is a plan view of a crystal blank. The quartz oscillator is formed from, for example, an AT-cut quartz piece, and is first cut out from an artificial quartz (not shown) with a certain thickness. Then, it is processed into a thickness responsive to the vibration frequency by mechanical polishing or chemical or electronic etching.

These are formed in the state of individual crystal blanks, in the state of crystal wafers divided into individual crystal blanks, or in the state of crystal wafers having concave portions corresponding to a large number of crystal blanks (not shown). In AT cut, thickness shear vibration is generally applied, and the vibration frequency is inversely proportional to the thickness.
The smaller the thickness, the higher.

Then, as shown in FIG. 11, an excitation electrode 2 (ab) for exciting thickness-shear vibration on both main surfaces of the crystal blank.
And the extraction electrode 3 (ab) connected thereto is extended to both sides of one end. These are usually formed integrally by vapor deposition. Next, on the bottom surface of the concave container 4 made of, for example, a laminated ceramic, the outer peripheral portions of both ends of the crystal piece extending from the extraction electrode 3 (ab) are fixed with a conductive adhesive 5 or the like, and electrically and mechanically connected. (FIG. 10). Reference numeral 6 in the figure is a mounting electrode, and reference numeral 7 is a terminal electrode.

Next, the excitation electrode 2 on the upper surface side of the crystal blank 1
A metal for adjustment (not shown) is added on a from the direction of the arrow, for example, by vapor deposition, and the vibration frequency is finely adjusted from the higher to the lower to obtain the target vibration frequency. Alternatively, the excitation electrode 2
Irradiating the ion beam on a, the thickness thereof is reduced, and the vibration frequency is finely adjusted from a lower one to a higher one to obtain a target vibration frequency. In short, the vibration frequency is adjusted by the mass load effect accompanying the addition or reduction of the mass.

Finally, a cover (not shown) is joined to the opening surface of the concave container 4 by seam welding, beam welding, glass sealing, resin sealing, or the like to hermetically enclose the crystal blank 1.

[0008]

[Problems to be Solved by the Invention]
However, the crystal resonator having the above configuration has the following problem with the increase in the vibration frequency, for example, 100 MHz or more. That is, as described above, the thickness of the crystal blank decreases as the vibration frequency increases. By the way, if the vibration frequency is 100 MHz, it becomes about 17 μ. Therefore, as the vibration frequency increases, the processing accuracy of the thickness of the crystal blank 1 is required, and as the thickness decreases, the influence of the processing error (absolute amount) on the vibration frequency increases.

For these reasons, when the processing accuracy does not satisfy a certain standard, the fine adjustment of the vibration frequency becomes impossible. That is, the vibration frequency basically depends on the thickness of the crystal piece, and the frequency range in which fine adjustment can be performed is limited. Incidentally, assuming that the vibration frequency is 100 MHz, even when the adjustment metal film is added and when the excitation electrode 2 (ab) is reduced, the vibration frequency is at most about 200 KHz. For these reasons, the conventional quartz resonator has a problem that productivity is reduced.

(Object of the Invention) It is an object of the present invention to provide a crystal resonator which can easily adjust the vibration frequency and can increase the productivity.

[0011]

According to the present invention, there is provided a fundamentally first solution in which the vibration frequency of a quartz piece is adjusted from a higher frequency to a lower frequency by mass addition by an ionized element injected from a main surface. (Claim 1). According to the present invention, a fundamental second solution is that the amorphized layer formed by the ionized element implanted from the main surface is reduced by etching, and the vibration frequency of the crystal piece is adjusted from a lower one to a higher one. (Claim 2). According to the present invention, the third solution is to reduce the amorphized layer formed on the main surface by etching and adjust the oscillation frequency of the quartz piece from a lower one to a higher one. 3).

[0012]

In the first solution, the vibration frequency of the quartz piece is adjusted by adding the mass of the ionized element, so that the vibration frequency can be controlled by the mass at the atomic level. In the second solution, the number of the amorphized layers formed by the ionized elements is reduced, so that the thickness of the crystal blank can be increased and the processing can be facilitated. The amorphized layer makes it easier to control the thickness by etching than the crystalline layer. In the third solution, since the number of amorphized layers provided on the main surface is reduced, the thickness can be easily controlled by etching as described above. Hereinafter, each embodiment of the present invention will be described based on manufacturing steps.

[0013]

First Embodiment FIGS. 1 to 3 are cross-sectional views, particularly of a crystal unit, for explaining a first embodiment of the present invention together with manufacturing steps. The same parts as those in the prior art are denoted by the same reference numerals, and description thereof will be simplified or omitted. The crystal unit is composed of an AT-cut crystal piece 1 cut out from artificial quartz as described above. Then, in this embodiment, the quartz crystal blank 1 is processed to a specified thickness by polishing or etching, and the vibration frequency of the crystal blank 1 is measured (FIG. 1). Here, the specified thickness is set to a thickness that is higher than a target vibration frequency (that is, a thickness smaller than the target).

As described above, these are formed in the state of individual crystal blanks, the state of a crystal wafer, or the state of a crystal wafer having a large number of concave portions. Next, the vibration frequency of each crystal blank 1 is measured. Then, according to the frequency difference between the actually measured vibration frequency and the target frequency, an ionized element such as O +, Si +, Ar +, etc. is implanted from one main surface of the crystal blank 1. In short, the mass addition layer 8 is formed on the main surface of the crystal blank, and the vibration frequency of the crystal blank itself is adjusted from higher to lower (FIG. 2).

Next, the excitation electrode 2 (ab) and the extraction electrode 3 (ab) are formed on both main surfaces of the crystal blank 1 as described above (FIG. 3). Finally, the crystal blank 1 is held on the bottom surface of the concave container 4, and the vibration frequency is finely adjusted by vapor deposition or beam irradiation (see FIG. 10).

With such a configuration, the ionizing element is implanted into one main surface of the crystal blank 1 to add mass at the atomic weight level, so that the vibration frequency (substantial thickness) of the crystal blank itself is strictly set. Can be controlled. Therefore, the thickness of the crystal blank 1 can be controlled within a certain value. That is, processing can be performed to a thickness that allows fine adjustment of the vibration frequency by vapor deposition or beam irradiation (mass load effect). From these, the crystal blank 1
A crystal resonator which can easily adjust the vibration frequency of the crystal and enhance the productivity can be obtained.

[0017]

Second Embodiment FIGS. 4 to 7 are cross-sectional views of a crystal unit for explaining a second embodiment of the present invention together with manufacturing steps. The same parts as those in the previous embodiment are denoted by the same reference numerals, and description thereof will be omitted. The crystal unit is composed of an AT-cut crystal piece 1 cut out from artificial quartz as described above.
In this embodiment, the thickness of the crystal blank 1 by polishing or etching is set to a thickness lower than the target vibration frequency (that is, a thickness larger than the target), contrary to the first embodiment (fourth). Figure).

Next, an ionizing element is implanted at a constant depth from one main surface in accordance with the vibration frequency of the crystal blank 1. Here, one main surface of the crystal blank is made amorphous by the ionizing element, that is, the crystal structure of the crystal blank 1 is destroyed to form the amorphous layer 9 (FIG. 5). It should be noted that the ionized element has a higher density than that of the first embodiment and is implanted in a large amount.

Next, the amorphized layer 9 on one main surface is scraped off by etching and processed to a thickness near the target vibration frequency (FIG. 6). Then, as described above, the excitation electrode 2 (ab) and the extraction electrode 3 (ab) are provided on both main surfaces of the crystal blank 1.
Is formed (FIG. 7). Finally, the crystal blank 1 is held in the concave container 4, and the vibration frequency is finely adjusted by vapor deposition or beam irradiation (see FIG. 10).

With such a configuration, the one main surface of the crystal blank 1 is made amorphous and the amorphized layer 9 is scraped off by etching, so that the etching speed is higher than the etching of the crystal plane (layer). And the amount can be controlled with high precision. Therefore, the thickness of the crystal blank 1 can be processed to a constant value, that is, a thickness that allows fine adjustment of the vibration frequency by vapor deposition or beam irradiation.

Further, in this embodiment, the thickness of the crystal blank 1 can be formed larger than the target thickness of the vibration frequency, so that the control thereof is also facilitated. From these facts, it is possible to obtain a crystal resonator that facilitates adjustment of the vibration frequency and increases productivity.

[0022]

Third Embodiment FIGS. 8 and 9 are cross-sectional views of a crystal oscillator illustrating a third embodiment of the present invention together with manufacturing steps.
The description of the same parts as in the previous embodiment is omitted. In the third embodiment, contrary to the previous second embodiment, the thickness of the crystal blank 1 is processed by polishing or etching so as to be smaller in advance than the thickness at the target frequency. Then, an amorphous layer 9 is formed on one main surface of the crystal blank 1 (FIG. 8). The amorphization layer 9 is made of, for example, an amorphous Si oxide film, and is made of TEOS (Tetrametoxys).
ilane) by PCVD (Plasma chemical vapor depositio)
n).

Next, in the same manner as described above, the amorphized layer 9 on one main surface is scraped off by etching, and is processed to a thickness near the target vibration frequency. As before, the excitation electrode 2 (ab) and the extraction electrode 3
(Ab) is formed (FIG. 9), and the thickness of the excitation electrode 3 (ab) is controlled by holding the crystal blank 1 in the concave container 4 and finely adjusted to the target vibration frequency (the previous FIG. 10). ).

With this structure, as in the second embodiment, the amorphized layer 9 provided on one main surface of the crystal blank 1 is removed by etching, so that the etching rate and amount can be controlled with high precision. it can. Therefore, the thickness of the crystal blank 1 can be processed to a constant value, that is, a thickness that allows fine adjustment of the vibration frequency by vapor deposition or beam irradiation, and the adjustment of the vibration frequency can be facilitated to increase the productivity.

[0025]

[Others] In the first embodiment, the ionized element is implanted into one main surface of the crystal blank, but it may be implanted into both main surfaces. Also,
In the second and third embodiments, the amorphizing layer is provided on one main surface of the crystal blank and etching is performed. However, the etching amount (depth) from each main surface is reduced by dispersing the crystallizing layer on the main surface. May be.
In the second embodiment, the amorphous layer 9 is formed by PCVD.
However, PVD or CVD may be used, and the means is not limited. Further, one end of the crystal blank 1 extended from the extraction electrode 3 (ab) is held on the bottom surface of the concave container 4.
(Ab) may be extended to both ends of the crystal blank 1 to hold both ends, and these holding forms can be arbitrarily formed including a container or the like.

[0026]

According to the present invention, there is provided a crystal resonator and a method for manufacturing the same, which have an amorphized layer for adjusting the vibration frequency on the main surface of the crystal blank, thereby facilitating the adjustment of the vibration frequency and improving the productivity. Can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a crystal unit in a manufacturing process illustrating a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of the crystal unit in a manufacturing process illustrating a first embodiment of the present invention.

FIG. 3 is a cross-sectional view of the crystal unit in a manufacturing process illustrating a first embodiment of the present invention.

FIG. 4 is a cross-sectional view of a crystal unit in a manufacturing process illustrating a second embodiment of the present invention.

FIG. 5 is a cross-sectional view of a crystal unit in a manufacturing process illustrating a second embodiment of the present invention.

FIG. 6 is a cross-sectional view of a crystal unit in a manufacturing process illustrating a second embodiment of the present invention.

FIG. 7 is a cross-sectional view of a crystal unit in a manufacturing process illustrating a second embodiment of the present invention.

FIG. 8 is a cross-sectional view of a crystal unit in a manufacturing process illustrating a third embodiment of the present invention.

FIG. 9 is a cross-sectional view of a crystal unit in a manufacturing process illustrating a third embodiment of the present invention.

FIG. 10 is a cross-sectional view of a crystal unit illustrating a conventional example.

FIG. 11 is a plan view of a crystal blank for explaining a conventional example.

[Explanation of symbols]

1 crystal blank, 2 excitation electrode, 3 extraction electrode, 4 concave container, 5 conductive adhesive, 6 mounting electrode, 7 terminal electrode,
8 Mass addition layer, 9 Amorphous layer.

Claims (3)

[Claims] 1. A crystal resonator wherein an ionized element is injected from a main surface of a crystal element, and the vibration frequency of the crystal element is adjusted from high to low by adding the mass of the element. 2. An amorphous layer is formed by injecting an ionized element from a main surface of a quartz piece, and the amorphized layer is reduced by etching to increase the vibration frequency of the quartz piece from the lower side to the higher side. A quartz oscillator characterized by having been adjusted toward. 3. An amorphous layer is formed on a main surface of a crystal blank, and the vibration frequency of the crystal blank is adjusted from low to high by reducing the amorphous layer by etching. And a quartz oscillator.