JP3980850B2 - Manufacturing method of crystal unit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a crystal resonator in an industrial technical field, and more particularly to a method for manufacturing a high-frequency crystal resonator in which the thickness of a vibration region is reduced by etching.
[0002]
[Prior art]
(Background of the Invention) A quartz resonator, for example, an AT cut type, is adopted in various electronic devices as a frequency and time reference source and a filter element. In recent years, a crystal piece having a small thickness is required with the increase of the communication frequency and the like. One such example is a crystal piece in which the thickness of the vibration region is reduced by etching, for example.
[0003]
(Example of Prior Art) FIG. 3 is a diagram of a crystal resonator for explaining one conventional example.
The crystal resonator is composed of a crystal piece 1 having an AT cut. The crystal piece 1 is composed of a central portion with a small thickness that becomes the vibration region 2 and an outer peripheral portion that becomes the non-vibration region 3 with a larger thickness. An excitation electrode 4 extends in the vibration region 2 on both main surfaces, and an extraction electrode 5 extends in the non-vibration region 3. In addition, the non-vibration area | region 3 of an outer peripheral part becomes a holding | maintenance area | region normally.
[0004]
In such a case, as shown in FIG. 4 (cross-sectional view), first, a metal film 6 as a mask is formed on both main surfaces of the flat crystal piece 1 by sputtering or the like to form a resist solution 7. “FIG. 4 (a)”. Then, the central portion of the resist solution 7 is removed by exposure “the same figure (b)”. Next, by etching the central portion of the metal film 6 "FIG (c)", to expose the main surface central portion of the crystal piece 1 to remove the resist solution 7 "the (d) of FIG."
[0005]
Next, the crystal piece 1 is put into HF (hydrogen fluoride) solution and etched from both main surface sides, so that the thickness of the central portion that becomes the vibration region 2 is smaller than the outer peripheral portion that becomes the non-vibration region 3. (E) ". Finally, the metal film 6 is removed and "figure (f)", the excitation electrode 4 is deposited at the center of both main surfaces as the vibration region 2, and the extraction electrode 5 is deposited at the outer peripheral portions at both ends as the non-vibration region 3. Extend by etc. Usually, after being formed in the state of a crystal wafer (not shown), it is divided individually.
[0006]
[Problems to be solved by the invention]
(Problems of the prior art) However, in the crystal resonator having the above-described configuration, since the formation and removal of the metal film 6 and the resist solution 7 are repeated, many manufacturing steps are required and there is a problem of poor productivity. Further, since various chemical solutions are used for removing the metal film 6 and the resist solution 7, there is a problem of waste solution.
[0007]
(Object of the Invention) An object of the present invention is to provide a method for producing a crystal resonator which can reduce the number of production steps to increase productivity and produce less waste liquid.
[0008]
[Means for Solving the Problems]
(Points of interest) The present invention has focused on the point that the etching rate of the BT cut, which is twinned with respect to the AT cut, is about 2/7.
[0009]
(Solution) The present invention is based on the above point of interest, and basically etches a non-vibration region twinned (BT cut) with respect to a vibration region (AT cut) of a crystal piece. And
[0010]
[Action]
In the present invention, since the non-vibration region is etched by twinning (BT cut), the etching rate of the vibration region (AT cut) is relatively increased, and a metal film (mask) and a resist solution are not required. . Hereinafter, an embodiment of the present invention will be described based on the manufacturing process.
[0011]
【Example】
FIG. 1 is a diagram of a crystal resonator illustrating one embodiment of the present invention. In addition, the same number is attached | subjected to the same part as a prior art example, and the description is simplified or abbreviate | omitted.
The quartz crystal resonator is composed of a crystal piece 1 having an AT-cut central portion (vibration region) having an AT cut as described above and an outer peripheral portion (non-vibration region) having a larger thickness ("previous FIG. 3"). In this embodiment, the laser P is irradiated to the outer peripheral portion of the flat crystal piece 1 as shown in FIG. 1 (a). Note that the Y ′ axis of the crystal axis (XY′Z ′) in AT cut is the thickness, and here the X axis is the width and the Z ′ axis is the length.
[0012]
Thus, the outer peripheral portion of the crystal piece 1 is twinned with respect to the central portion (FIG. 2B). That is, the X-axis direction of the outer peripheral portion is reversed to change from AT cut to approximately BT cut. However, the AT cut is maintained at the center as it is. Then, a twin crystal piece 1 having an AT cut at the center and a BT cut at the outer peripheral portion is put into the HF solution and etched as a whole.
[0013]
In such a case, since the outer peripheral portion of the crystal piece 1 is a twinned BT cut, the etching rate is about 2/7 slower than the single crystal portion in the central portion. For example, if the HF solution is at room temperature of 25 ° C., the etching rate is 0.07 μm / min for the AT cut in the center and 0.02 μm / min for the outer periphery. Therefore, the central portion of the crystal piece 1 is etched first from both main surface sides, and eventually the thickness of the central portion is processed smaller than the outer peripheral portion (FIG. 1 (c)).
[0014]
For example, when the thickness of a flat crystal piece made of AT cut is 16.7 μm (100 MHz), the outer peripheral portion is twinned and etched, and the central portion is 1.7 μm (≈1 GHz), the outer peripheral portion becomes 12.4 μm. Therefore, a high-frequency crystal resonator is obtained with the outer peripheral portion having sufficient holding strength.
[0015]
From these facts, the laser P is irradiated to the outer periphery of the crystal piece 1 to form twin crystals, and then the crystal piece is only exposed and etched as a whole, greatly simplifying the manufacturing process and increasing productivity. It is done. Moreover, since a metal film and a resist are unnecessary, the chemical liquid for removing these is excluded and waste liquid is reduced.
[0016]
[Other matters]
In the above embodiment, the crystal piece 1 is made the non-vibration region 3 by increasing the thickness of the entire outer periphery of the central portion that becomes the vibration region 2. For example, as shown in FIG. The non-vibration region 3 may be formed, and these shapes are arbitrary.
[0017]
【The invention's effect】
The present invention, since the etching of the non-vibration region with respect to the vibration region of the crystal blank which was AT-cut and twinned, increase productivity by reducing the manufacturing steps, manufacturing of the crystal resonator to be less production of waste Can provide a method .
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a crystal resonator (crystal piece) in each manufacturing process for explaining an embodiment of the present invention.
FIG. 2 is a diagram of a crystal resonator illustrating another embodiment of the present invention.
FIG. 3 is a diagram of a crystal resonator for explaining a conventional example.
FIG. 4 is a cross-sectional view of a crystal resonator in each manufacturing process for explaining a conventional example.
[Explanation of symbols]
1 crystal piece, 2 vibration region, 3 non-vibration region, 4 excitation electrode, 5 extraction electrode, 6 metal film, 7 resist solution.

Claims (1)

In a manufacturing method of a crystal resonator in which a thickness of a vibration region in an AT-cut crystal piece is made smaller than that in a non-vibration region by etching, the non-vibration region of the crystal piece is twinned with respect to the vibration region, and the crystal method for manufacturing a quartz resonator, characterized in that it wholly etched to expose the both main surfaces of the pieces to form large the non-vibrating region of thickness from the vibrating region.

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