JP3328411B2 - Manufacturing method of crystal unit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a crystal unit by forming a semiconductor layer having a predetermined electrode shape on a quartz substrate by a spray pyrolysis method or the like and performing electroless plating under a predetermined condition. is there.

[0002]

2. Description of the Related Art Quartz, which is known as a typical piezoelectric crystal, is artificially mass-produced by a hydrothermal synthesis method, and products utilizing its characteristics are used in various fields.

[0003] For example, a quartz oscillator is a product utilizing the characteristic that when a voltage is applied to a thin quartz plate by applying an electrode, crystal oscillation is excited by the piezoelectric inverse effect of the quartz.

[0004] A quartz resonator utilizes the fact that when an AC electric field having a frequency equal to the natural frequency determined by the shape of the crystal piece or the like is applied, the resonator vibrates and keeps vibrating at a stable single frequency. Used in many oscillation circuits.

[0005] In order to manufacture a quartz oscillator, it is necessary to attach electrodes to a quartz substrate. Conventional electrode attachment is performed using a vacuum deposition method. The steps are described below.

First, the α-quartz crystal is cut (cut) in accordance with the purpose of use of the vibrator, and the surface of the quartz substrate finished to a predetermined size is degreased and then washed with a strong acid (aqua regia).

[0007] Next, an electrode film is vacuum-deposited on the cleaned quartz substrate by using an unmasked mask having an electrode film shape. Further, by finely adjusting the thickness of the electrode film, the oscillation frequency of the formed quartz oscillator is adjusted to a predetermined oscillation frequency.

The above-described vacuum deposition method is best known as a technique for forming a thin film and is widely used, but has the following problems.

(1) Since the electrode film formed by the vacuum evaporation method has poor adhesion to the quartz substrate, the electrode film is formed on the quartz substrate during soldering during wiring or when a voltage is applied to the quartz oscillator. Peels off from

(2) Since the vacuum evaporation method is a batch process, the processing quantity is limited, and when the processing quantity is further increased, the distance from the metal deposition source (target) to each quartz substrate becomes different. For this reason, the thickness of the electrode film formed on each quartz substrate varies, and the oscillation frequency of the quartz oscillator cannot be standardized. Therefore, it is necessary to finely adjust the thickness of each electrode film in order to match a predetermined oscillation frequency.

(3) In the formation of an electrode film by the vacuum evaporation method, when there is unevenness on the substrate surface, a shadow is easily formed, and disconnection occurs at a step, so that the thickness of each electrode film is not uniform in the plane. turn into.

(4) In order to form electrodes on each quartz substrate by a vacuum evaporation method, it is necessary to manually apply a stripped mask having a predetermined electrode shape on the quartz substrate. Further, since the mask must be removed after film formation, the process is complicated and requires attention.

As described above, there are various problems in the vacuum deposition method, and an alternative method of attaching electrodes is required. As a candidate thereof, an electroless plating method can be cited.

In the electroless plating method, a uniform metal thin film can be formed even on a material surface having no electric conductivity, and has been rapidly growing as a conductive metal film coating technique in recent years. In comparison, there are advantages of low cost as a wet method and high mass productivity.

Further, the present invention is characterized in that a uniform conductive metal thin film having good adhesion to a substrate can be obtained by electroless plating. As an example of the prior art, a process of electroless plating on ceramics is shown in FIG. As shown in this figure, conventional electroless plating requires the following steps.

(1) Degreasing the surface of the ceramic substrate.

(2) The surface is roughened by etching using a hydrofluoric acid-based etchant.

(3) Adjusting the surface (making the surface hydrophilic or sensitive).

(4) Applying a catalyst to the surface.

(5) Activate the catalyst.

(6) Perform electroless plating.

As described above, in order to perform electroless plating on a ceramic substrate, four pretreatment steps (2) to (5) are required.

The coating of the conductive metal film using the electroless plating method can be applied to a material having no electric conductivity, and has good adhesion between the deposited film and the substrate and has a small thickness. Because of its uniformity, it is expected as a field of thin film technology. In particular, the electroless plating method has been applied to materials such as plastics and ceramics, and has been developed as a technique for producing a functional plating film in the field of electronic components.

However, quartz is a material having poor adhesion, and it is difficult to apply a metal film coating on quartz using the above-described electroless plating method as it is.

Therefore, a method of attaching electrodes using a spray pyrolysis method is currently being studied.

In the spray pyrolysis method, first, an atomized semiconductor solution is brought into contact with a suitably heated quartz substrate to form a semiconductor layer on the quartz substrate, and then the semiconductor layer is metalized with a PdCl ₂ aqueous solution or the like. Activate with a nucleus. Thereafter, the activated semiconductor layer is brought into contact with a metal salt solution to deposit a metal layer on the semiconductor layer.

When the electrodes are attached to the crystal unit, the electrodes are attached using an electrode metal as the metal deposited on the activated semiconductor layer.

[0028]

However, when a quartz oscillator is manufactured by electrode attachment using the above-mentioned spray pyrolysis method, the oscillation frequency of each manufactured quartz oscillator is set to a predetermined oscillation frequency as in the case of the vacuum evaporation method. Need to fine-tune to frequency. Therefore, it is necessary to further perform a complicated fine adjustment process after the electrodes are attached, and the cost remains high.

The present invention has been made under the above-mentioned background, and a technique for forming an electrode film on a quartz substrate includes:
It is an object of the present invention to provide a method of manufacturing a crystal oscillator that can easily and at low cost control the oscillation frequency of the crystal oscillator.

[0030]

According to the present invention, a semiconductor layer is formed on a quartz substrate by spraying an atomized semiconductor solution onto the quartz substrate to contact the atomized semiconductor solution. A method for manufacturing a crystal resonator, comprising: an electrode film forming step of contacting a metal salt solution after activating the semiconductor layer to deposit the metal on the semiconductor layer, wherein the crystal substrate of the atomized semiconductor solution is used. The thickness of the semiconductor layer by controlling the spray distance
A method for manufacturing a crystal resonator, comprising an oscillation frequency adjustment step of adjusting the oscillation frequency of the crystal resonator.

A semiconductor layer is formed on the quartz substrate by spraying the atomized semiconductor solution on the quartz substrate, and the semiconductor layer is activated and then brought into contact with a metal salt solution to activate the semiconductor layer. In a method for manufacturing a crystal resonator having an electrode film forming step of depositing the metal on a semiconductor layer, the thickness of the semiconductor layer is controlled by controlling a spray distance of the atomized semiconductor solution to the crystal substrate.
Adjusted to also provides a method for producing a quartz oscillator, characterized by having an aging characteristic adjusting step of adjusting the aging characteristics of the crystal resonator.

Preferably, a zinc oxide layer is used as the semiconductor layer.

According to the present invention, when the semiconductor solution is sprayed onto the crystal unit, the oscillation frequency of the crystal unit can be adjusted by controlling the spray distance, and the aging characteristics of the crystal unit can also be adjusted. It was found that the crystal resonator could be manufactured.

More specifically, when a semiconductor layer is formed by using a spray pyrolysis method and then electroless plating is performed,
The oscillation frequency of the crystal oscillator was controlled by controlling the spray distance. When the spraying distance is short, the oscillation frequency of the crystal resonator is greatly reduced as compared with the oscillation frequency of the original substrate, and when the spraying distance is long, the oscillation frequency of the crystal resonator is not so low.

Therefore, in the case of a crystal unit using an electrode film formed by a vacuum deposition method, a step of adjusting the resonance frequency of the crystal unit is required. Since the oscillation frequency of the child can be controlled,
The manufacturing process of the crystal unit can be simplified.

When the spray distance is increased, the aging characteristic is improved, and the original oscillation frequency is maintained for a long period. If the spray distance is too long, it becomes difficult to form a semiconductor layer on the quartz substrate.Therefore, the spray distance should be set longer for a quartz substrate whose resonance frequency is not much higher than the resonance frequency of the target quartz resonator. It is preferable to manufacture a quartz oscillator.

Hereinafter, the present invention will be described in more detail.

In the case of a poorly adherent material such as quartz, Sn ^{2+, which} is often used in the catalyzing process, is hardly adsorbed, and it is difficult to use the conventional two-part catalyst method or mixed catalyst solution. The problem is solved by forming a semiconductor layer on a quartz substrate as described above.

When the semiconductor layer is immersed in an activating solution such as an aqueous solution of palladium chloride, a part of the metal (or) metalloid in the semiconductor layer is easily ionized and dissolved, while the metal ions in the activating solution are reduced. As a result, a metal nucleus or a metal layer is formed on the semiconductor layer having a predetermined electrode shape, and the surface becomes catalytically active for electroless plating.

In the present specification, a metalloid such as gallium and a metal such as Zn are collectively described as a metal. When Pd ions are used as the activating solution, Pd deposited on the semiconductor layer forms a metal nucleus that becomes a highly active catalyst for electroless plating. Further, when the metal ions themselves have an autocatalytic function in the activating liquid, they are continuously deposited, so that a metal layer is formed on the semiconductor. Further, by immersing a quartz substrate having a predetermined electrode-shaped portion having a catalytically active surface in an electroless plating bath, a plating film can be selectively and continuously formed on the catalytically active surface portion on the quartz substrate.

The conductive metal film coating using the electroless plating method can be mass-produced at low cost, has good adhesion between the deposited film and the substrate, and has a uniform film thickness. Therefore, peeling of the electrode film, variation in the thickness of the electrode film, and the like are suppressed as compared with the vacuum evaporation method. Further, the processing quantity can be easily increased.

[0042]

Embodiments of the present invention will be described below in detail with reference to the drawings. The present invention is not limited to the following examples.

FIG. 2 shows a flowchart of a method for manufacturing a crystal resonator according to the present invention. As shown in this figure,
In the method of forming an electrode film for a crystal unit according to the present invention, degreasing and cleaning of a crystal substrate, semiconductor layer formation, a catalyzing process, and electroless plating are performed.

FIG. 1 is an explanatory view of an electrode attaching step in this method of manufacturing a crystal resonator.

In FIG. 1, 1 is a quartz substrate, 2 is a semiconductor layer, 3 is a mask, 4 is a deposited metal nucleus layer of Pd or the like serving as a catalyst for electroless plating, and 5 is a conductive metal layer formed by electroless plating. Is shown.

First, the α-quartz crystal is cut (cut) in accordance with the purpose of use of the vibrator, and the surface of the quartz substrate finished to a predetermined size is degreased and then washed with a strong acid (aqua regia).

Next, a mask 3 having a predetermined shape is applied on the quartz substrate 1 and set on a hot plate. The semiconductor layer 2 is formed by applying ultrasonic waves to the zinc metal salt aqueous solution and spraying it (spray pyrolysis method) on the exposed electrode-shaped portions of the quartz substrate. At this time, the hot plate was heated to 450 ° C.

Further, the distance between the nozzle and the quartz substrate can be freely adjusted. As described above, the semiconductor layer is formed by applying a supersonic wave to the aqueous solution of the metal salt for preparing a semiconductor and spraying the mist.

Further, the quartz substrate on which the semiconductor layer is formed is immersed in an activating liquid to catalyze the surface of the semiconductor layer. At this time, the metal ions in the semiconductor layer are dissolved, while the metal ions in the activation liquid are reduced to form a metal core or a metal layer for electroless plating on the semiconductor layer.

The quartz substrate having the semiconductor layer catalytically activated as described above is immersed in an electroless plating bath to form a conductive metal layer 5.
To form

In this embodiment, artificial quartz is used for the quartz substrate 1, zinc oxide (ZnO) is used for the semiconductor layer 2, a stripped mask having a predetermined electrode shape is used for the mask 3, and metal nuclei 4 serving as a catalyst for electroless plating are used. Ni was used for Pd and the conductive metal layer 5.

Each of the artificial quartz substrates used had a resonance frequency of 10.080 MHz. The thickness of the formed zinc oxide semiconductor layer is 10 nm to 50 nm.
0 nm (0.01 μm to 0.5 μm), and each film thickness was uniform in the plane. Furthermore, the adhesion between the zinc oxide semiconductor layer and the quartz substrate was good, and the zinc oxide semiconductor layer was not damaged even when rubbed with a pencil lead having a hardness of 2H.

Each of the quartz substrates on which the zinc oxide semiconductor layer having a predetermined electrode shape was formed under the above conditions was subjected to electroless plating as follows. First, each quartz substrate was subjected to 0.001 (mol / l) Pd
The catalyst was immersed in Cl ₂ for 1 minute to catalyze, thereby forming a Pd metal nucleus serving as a Ni plating catalyst on the zinc oxide semiconductor layer.

Further, each of the above quartz substrates was immersed in an electroless plating bath (Top Chemalloy 66 (pH = 6.5) manufactured by Okuno Pharmaceutical Co., Ltd.) (pH = 6.5) maintained at 60 ° C. for 60 seconds to obtain a conductive property. A Ni plating layer was formed.

First, in the above manufacturing process, the concentration of zinc acetate to be sprayed was set to 0.0125 (mol / l), 0.0250 (mol / l), and 0.0500 (m / l).
ol / l) and the distance (spray distance) between the spray outlet of the sprayed mist and the quartz substrate (spray distance) was 6 (cm), 12 (cm), and 18 (cm), respectively, to produce a quartz oscillator.

Table 1 shows the results of measuring the oscillation frequency of each crystal resonator. In addition, a graph showing the correlation between the concentration of the aqueous zinc acetate solution and the resonance frequency was created. This graph is shown in FIG.
Shown in

[0057]

[Table 1]

As shown in Table 1 and FIG. 3, the oscillation frequency of the formed quartz oscillator is lower than the resonance frequency of the artificial quartz substrate, and the oscillation frequency decreases as the concentration of the aqueous zinc acetate solution increases. Also, at any concentration, the resonance frequency increases as the spray distance increases.

Since the zinc oxide layer becomes thicker as the concentration of the aqueous zinc acetate solution increases, it is considered that the oscillation frequency decreases as the thickness of the zinc oxide layer increases. Further, as the spray distance increases, the amount of zinc acetate per unit area decreases, and the thickness of the zinc oxide layer also increases. Therefore, it can be considered that the oscillation frequency decreases as the thickness of zinc oxide increases.

From the above results, regardless of the concentration of the aqueous solution of zinc acetate, a decrease in the oscillation frequency of the quartz oscillator can be suppressed by increasing the spray distance. In order to obtain a desired oscillation frequency, a crystal oscillator having an oscillation frequency higher than the desired value is used, and the spray distance is appropriately controlled so that the oscillation frequency becomes lower to the desired value. A crystal unit having a frequency can be manufactured.

Next, in the above-described method for manufacturing a quartz oscillator, the concentration of the aqueous zinc acetate solution was set to 0.025 mol, the spray distance was set to 12 (cm), and the quartz oscillator 1 was used by using a quartz substrate of 10.08000 MHz.
2, 3, and 4 were produced. Similarly, quartz oscillators 5, 6, 7, and 8 were manufactured with a spray distance of 18 (cm).

Tables 2 and 3 show the resonance frequencies, equivalent series resistances, and Q values of the quartz oscillators 1-4 and 5-8, respectively.

[0063]

[Table 2]

[0064]

[Table 3]

The aging characteristics of the quartz oscillators 1 to 4 are shown in FIGS.

As shown in FIG. 4, the spray distance is set to 12 (c
In the crystal oscillators 1 to 4 of m), the frequency decreases as time passes.

On the other hand, as shown in FIG.
It can be seen that in the quartz oscillators 5 to 8 (cm), a change in frequency is hardly observed even with the passage of time.

From the above results, it is understood that the aging characteristics are improved by increasing the spray distance. In particular, by setting the spray distance to about 18 (cm), stable aging characteristics can be obtained.

In this embodiment, N is used as the electrode metal.
i have adopted. The Ni film has resistance to hydrofluoric acid-based etchant commonly used as an etchant for quartz, and it is not necessary to protect the electrode portion during etching, and the etching can be performed easily.

As the aqueous solution to be sprayed, an aqueous solution containing a zinc metal salt such as zinc acetate, zinc nitrate and zinc chloride can be used. In this embodiment, zinc acetate was used.

In this embodiment, since the mist is generated and sprayed by applying ultrasonic waves to the aqueous zinc metal salt solution, the aqueous zinc metal salt solution can be used efficiently. By using this spray method, a semiconductor layer having an arbitrary shape can be easily formed.

Further, since the trigonal α-quartz exhibiting piezoelectricity loses its piezoelectricity due to a phase transition to hexagonal β-quartz at 573 (° C.) or more, the quartz substrate during the spray pyrolysis is removed. Was set to 500 ° C. or less (300 to 500 ° C.).

[0073]

According to the present invention, since the oscillation frequency of the quartz oscillator is adjusted by controlling the spray distance when the zinc oxide semiconductor layer is formed, the quartz oscillator having the required oscillation frequency is formed. The child can be easily manufactured.

In particular, since the oscillation frequency can be adjusted in the electrode attaching step, there is no need to provide a new oscillation frequency adjustment step, which is advantageous in terms of cost.

Further, since the aging characteristic is improved when the spray distance is increased, it is possible to manufacture a crystal resonator having stable characteristics even for long-term use.

[Brief description of the drawings]

FIG. 1 is a schematic view of a process of forming a conductive metal layer on artificial quartz.

FIG. 2 is a process chart of a method for forming a conductive metal layer.

FIG. 3 is a diagram showing the oscillation frequency of a quartz oscillator formed by setting the concentration of a zinc acetate aqueous solution and the spraying time.

FIG. 4 is a graph showing aging characteristics of a quartz oscillator manufactured with a spray distance of 12 (cm).

FIG. 5 is a graph showing aging characteristics of a quartz oscillator manufactured with a spray distance of 18 (cm).

FIG. 6 is a process chart of an electroless plating method for ceramics.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Quartz substrate 2 ... Semiconductor layer 3 ... Mask 4 ... Catalyst metal core layer for electroless plating 5 ... Conductive metal layer

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Go Yanagita 2-1-1-17 Osaki, Shinagawa-ku, Tokyo Inside Meidensha Co., Ltd. (56) References JP-A-5-294623 (JP, A) JP-A-5-294 294622 (JP, A) JP-A-57-119505 (JP, A) JP-A-59-54309 (JP, A) JP-A-51-62985 (JP, A) JP-A-6-318835 (JP, A) JP-A-6-318834 (JP, A) JP-B 64-5763 (JP, B1) JP-B 64-4366 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) H03H 3/00-3/10 C01G 9/00-9/02

Claims (2)

(57) [Claims] 1. An atomized semiconductor solution is sprayed on a quartz substrate.
Forming a semiconductor layer on the quartz substrate by contacting by fogging, activating the semiconductor layer, and then contacting with a metal salt solution to deposit the metal on the semiconductor layer. In the method of manufacturing a vibrator, the thickness of the semiconductor layer is adjusted by controlling a spray distance of the atomized semiconductor solution to the quartz substrate.
And an oscillation frequency adjusting step of adjusting the oscillation frequency of the crystal unit. 2. An atomized semiconductor solution is sprayed on a quartz substrate.
Forming a semiconductor layer on the quartz substrate by contacting by fogging, activating the semiconductor layer, and then contacting with a metal salt solution to deposit the metal on the semiconductor layer. In the method of manufacturing a vibrator, the thickness of the semiconductor layer is adjusted by controlling a spray distance of the atomized semiconductor solution to the quartz substrate.
And a aging characteristic adjusting step of adjusting the aging characteristic of the crystal unit.