JP2001077647A - Manufacture of piezoelectric vibrating reed - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the method for manufacturing a piezoelectric vibrating reed with high work efficiency. SOLUTION: In this method, corrosion resistant films 42 and 43 and a photoresist film 44 are formed on the substrate 41 of the piezoelectric vibrating reed the unwanted part of the photoresist film is exposed, developed and removed corresponding to the outer shape of the piezoelectric vibrating reed, the unwanted part of the corrosion resistant film corresponding to the outer shape of the piezoelectric vibrating reed is etched and removed, the unwanted part of the photoresist film is exposed, developed and removed corresponding to the center shape of the piezoelectric vibrating reed, the exposed part of the substrate is etched, the unnecessary part of the corrosion resistant film corresponding to the center shape of the piezoelectric vibrating reed is etched and removed, and the exposed part of the substrate is etched, thereby forming the shape containing the center part of the piezoelectric vibrating reed. Thus, the new photoresist film is dispensed with to be formed/peeled as in the conventional method, so that a process is simplified, work efficiency is improved, and work cost is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method of manufacturing a piezoelectric vibrating reed, and more particularly to a method of manufacturing a piezoelectric vibrating reed in which steps are simplified.

[0002]

2. Description of the Related Art The frequency of an AT vibrator is determined by the thickness of a piezoelectric vibrating reed. The thickness of the piezoelectric vibrating reed is inversely proportional to the frequency of the AT vibrator. For example, when the thickness of the piezoelectric vibrating reed is 100 μm, the frequency of the AT vibrator is 16.7 MHz.
When the thickness of the piezoelectric vibrating reed is 50 μm, the frequency of the AT vibrator is 33.4 MHz.

However, as the thickness of the piezoelectric vibrating reed becomes thinner, mechanical polishing becomes more difficult, the strength against vibration becomes weaker, and the piezoelectric vibrating reed is more likely to be damaged. For this reason, the piezoelectric vibrating reed of the high-frequency AT vibrator is manufactured in a so-called inverted mesa shape in which only the central portion is thinly processed and the outer peripheral portion is thickly processed as a reinforcing frame. The thinning of the central portion of the piezoelectric vibrating reed may be performed by mechanical polishing, but is mostly performed by etching.

FIGS. 11A and 11B are a perspective view showing an example of a general inverted-mesa type AT vibrating piece and a sectional view taken along line AA of FIG.

In this inverted-mesa AT vibrating reed, only a central portion of a piezoelectric vibrating reed 11 made of a quartz crystal having a rectangular plate shape is thinly processed as a vibrating portion 11a, and an outer peripheral portion is thickly processed as a reinforcing frame 11b. Excitation electrodes 12 are formed on the front and back surfaces of the vibrating portion 11a, and connection electrodes 13 for energizing the respective excitation electrodes 12 are formed on one end of the reinforcing frame 11b.

The following two methods are generally known as a method for manufacturing the piezoelectric vibrating reed 11 of such an inverted mesa type AT vibrating reed. In the first manufacturing method, a plurality of chips of a predetermined size are cut out from a wafer by dicing or the like, an etching pattern is formed on each chip by photolithography, and a central portion of each chip is etched to a predetermined thickness to perform piezoelectric vibration. This is a method for forming pieces 11. The second manufacturing method is a method in which a plurality of etching patterns are formed on a wafer by photolithography, etched to a predetermined thickness, and a plurality of chips are divided by etching or the like to form the piezoelectric vibrating reed 11.

FIGS. 12 to 14 are process diagrams showing details of a method for manufacturing a conventional inverted-mesa AT vibrating piece.

First, a crystal wafer 21 is prepared (FIG. 12).
(A)), a Cr film 22 is formed on both surfaces of the quartz wafer 21 by depositing or sputtering Cr to a thickness of 500 angstroms, and an Au film is formed by depositing or sputtering Au to a thickness of 1000 angstroms. 23 to form a corrosion resistant film of hydrofluoric acid (FIG. 1)
2 (B)). Then, a photoresist is applied to the surface of the Au film 23 and dried to form a photoresist film 24 (FIG. 12C).

Next, a photomask 25 on which an etching pattern for forming the outer shape of the piezoelectric vibrating reed 11 is drawn is arranged on the photoresist film 24, and is exposed to ultraviolet light to change the etching pattern of the photomask 25 to the photoresist. The image is transferred to the film 24 (FIG. 12D). Then, the photosensitive portion of the photoresist film 24 is removed by developing with a developer,
The Au film 23 is exposed (FIG. 12E).

Next, the exposed Au film 23 is etched with an etching solution for Au composed of, for example, an aqueous solution of iodine and potassium iodide to expose the Cr film 22, and further the exposed Cr film 22 is etched with a Cr etching solution. Etching with
The crystal wafer 21 is exposed (FIG. 13A). Then, the remaining photoresist film 24 is peeled off (FIG. 13B).

Subsequently, a photoresist is again applied so as to cover the exposed quartz wafer 21 and the remaining Cr film 22 and Au film 23, and dried to form a photoresist film 26.
Is formed (FIG. 13C).

Next, a photomask 27 on which an etching pattern for forming the outer shape of the piezoelectric vibrating reed 11 and the shape of the vibrating portion 11a is drawn on the photoresist film 26.
Is arranged and exposed to ultraviolet rays to transfer the etching pattern of the photomask 27 to the photoresist film 26 (FIG. 1).
3 (D)). Then, the photosensitive portion of the photoresist film 26 is developed and removed with a developing solution to expose the quartz wafer 21 and the Au film 23 (FIG. 14A).

Next, the exposed crystal wafer 21 is etched with an etching solution for crystal composed of, for example, a mixture of hydrofluoric acid and ammonium fluoride to form the outer shape of the piezoelectric vibrating reed 11 (FIG. 14B). )). Meanwhile, the exposed Au
The film 23 is etched with the above-described etching solution for Au to expose the Cr film 22, and further expose the exposed Cr film 22.
Is etched with the above-described etching solution for Cr to expose the quartz wafer 21 (FIG. 14C).

Next, the exposed crystal wafer 21 is half-etched with the above-described crystal etching solution to form the vibrating portion 11a of the piezoelectric vibrating reed 11 (FIG. 14).
(D)). Then, the remaining photoresist film 26
Then, the Cr film 22 and the Au film 23 are peeled off. Thereby, the plurality of piezoelectric vibrating reeds 1 having the vibrating portion 11a and the reinforcing frame 11b are provided.
1 is completed (FIG. 14E).

[0015]

In the above-described conventional method for manufacturing a piezoelectric vibrating reed, a photoresist film 24 is formed to form the outer shape of the piezoelectric vibrating reed 11, and the shape of the piezoelectric vibrating reed 11 is patterned. Later, the photoresist film 2
4 is once peeled off. Then, a photoresist film 26 is formed to form the shape of the vibrating portion 11a of the piezoelectric vibrating piece 11.
Is formed, and the photoresist film 26 is peeled off after patterning the shape of the vibrating portion 11a of the piezoelectric vibrating piece 11. As described above, the conventional method of manufacturing the piezoelectric vibrating reed has a disadvantage that the working efficiency is very poor because the photoresist film needs to be formed and peeled twice.

An object of the present invention is to provide a method of manufacturing a piezoelectric vibrating reed which solves the above-mentioned problems and has high working efficiency when manufacturing the piezoelectric vibrating reed.

[0017]

According to a first aspect of the present invention, there is provided a method of manufacturing a piezoelectric vibrating reed having a thin center portion, wherein a corrosion-resistant film and a photoresist film are formed on a substrate of the piezoelectric vibrating reed. The unnecessary portion of the photoresist film corresponding to the outer shape of the piezoelectric vibrating piece is exposed, developed and removed, and the unnecessary portion of the corrosion resistant film corresponding to the outer shape of the piezoelectric vibrating piece is removed by etching. An unnecessary portion of the photoresist film is exposed and developed and removed according to the shape of the central portion of the substrate, the exposed portion of the substrate is etched, and the corrosion-resistant film corresponding to the shape of the central portion of the piezoelectric vibrating reed is formed. Forming a shape including a central portion of the piezoelectric vibrating piece by etching away an unnecessary portion of the substrate and etching an exposed portion of the substrate.

The invention according to claim 4 is the invention according to claim 1, 2, or 3.
In the configuration described in the above, the etching process of the substrate of the piezoelectric vibrating reed, the outer shape of the piezoelectric vibrating reed is formed by etching from both sides of the substrate corresponding to the outer shape of the piezoelectric vibrating reed, and then the This is a method of manufacturing a piezoelectric vibrating reed in which half-etching is performed from both surfaces of the substrate corresponding to the shape of the central portion of the piezoelectric vibrating reed.

According to the first and fourth aspects of the present invention, the same photoresist film is used for forming the outer shape of the piezoelectric vibrating reed and the shape of the center portion thereof. This eliminates the need for film formation / separation, thereby simplifying the process, improving work efficiency, and reducing work cost.

According to a second aspect of the present invention, in the configuration of the first aspect, the piezoelectric vibration is performed such that the second exposure of the photoresist film is performed by increasing the exposure amount at the time of the first exposure of the photoresist film. This is a method for manufacturing a piece.

According to the second aspect of the present invention, since the exposure amount is increased in the second exposure from the exposure amount in the first exposure, the photosensitivity is deteriorated by the etching process. Exposure can be performed accurately even with a resist film.

According to a third aspect of the present invention, in the structure of the first aspect, the second exposure of the photoresist film is performed by removing a surface layer of the photoresist film after removing the first photoresist film. This is a method of manufacturing a piezoelectric vibrating reed performed from step (1).

According to the third aspect of the present invention, the second exposure is performed after removing the surface layer of the photoresist film whose photosensitivity has been deteriorated by the etching process. can do.

The invention of claim 5 is the invention of claim 1, 2 or 3
In the configuration described in the above, the etching process of the substrate of the piezoelectric vibrating reed, the outer shape of the piezoelectric vibrating reed is formed by etching from one surface of the substrate corresponding to the outer shape of the piezoelectric vibrating reed, and then the This is a method of manufacturing a piezoelectric vibrating reed in which half-etching is performed from one surface of the substrate corresponding to the shape of the central portion of the piezoelectric vibrating reed.

According to the fifth aspect of the present invention, since the etching pattern of the photomask is transferred only to the resist film on one side, there is no need to perform phase adjustment of the photomasks on both sides. Therefore, there is no risk of deterioration of the CI value and occurrence of spurious due to the displacement of the photomask.

The invention of claim 6 is the invention of claim 1, 2, or 3.
In the configuration described in the above, the etching process of the substrate of the piezoelectric vibrating piece is half-etched from both sides of the substrate corresponding to the outer shape of the piezoelectric vibrating piece, and then corresponds to the shape of the central portion of the piezoelectric vibrating piece. A method of manufacturing a piezoelectric vibrating reed in which half-etching is performed on both surfaces of the substrate at the same time, and etching is performed on both surfaces of the substrate in accordance with the external shape of the half-etched piezoelectric vibrating reed.

According to the sixth aspect of the present invention, the etching process for forming the outer shape of the piezoelectric vibrating piece is stopped once at the half-etching stage, and then the shape of the central portion of the piezoelectric vibrating piece is formed. And the etching process for forming the outer shape of the piezoelectric vibrating piece can be performed simultaneously and terminated almost simultaneously. Therefore, in addition to the effect of the invention of claim 4, it is possible to shorten the etching time of the substrate as compared with the conventional case. further,
Since the etching time of the substrate is shortened, chipping due to over-etching of the outer edge of the piezoelectric vibrating reed can be prevented, the central portion can be enlarged, and spurious can be suppressed.

The invention of claim 7 is the invention of claim 1, 2 or 3
In the configuration described in the above, the etching process of the substrate of the piezoelectric vibrating reed is half-etched from one surface of the substrate corresponding to the outer shape of the piezoelectric vibrating reed, and then corresponds to the shape of the central portion of the piezoelectric vibrating reed. A method of manufacturing a piezoelectric vibrating reed in which half-etching is performed from one surface of the substrate and simultaneously, etching is performed from one surface of the substrate according to the external shape of the piezoelectric vibrating reed that has been half-etched.

According to the seventh aspect of the present invention, the etching process for forming the outer shape of the piezoelectric vibrating reed is temporarily stopped at the half-etching stage, and then the shape of the central portion of the piezoelectric vibrating reed is formed. And the etching process for forming the outer shape of the piezoelectric vibrating piece can be performed simultaneously and terminated almost simultaneously. Therefore, in addition to the effect of the invention of claim 5, it is possible to shorten the etching time of the substrate as compared with the related art. further,
Since the etching time of the substrate is shortened, chipping due to over-etching of the outer edge of the piezoelectric vibrating reed can be prevented, the central portion can be enlarged, and spurious can be suppressed.

[0030] The invention of claim 8 is the invention of claim 1, 2 or 3.
In the configuration described in the above, the etching process of the substrate of the piezoelectric vibrating reed is half-etched from one surface of the substrate corresponding to the outer shape of the piezoelectric vibrating reed, and then corresponds to the shape of the central portion of the piezoelectric vibrating reed. A method of manufacturing a piezoelectric vibrating reed in which half etching is performed from one surface of the substrate and etching is performed from the entire other surface of the substrate at the same time.

According to the eighth aspect of the present invention, in addition to the effect of the seventh aspect of the present invention, since the etching process is performed from both sides of the substrate, the etching time of the substrate can be further reduced. Further, since both surfaces at the center are etched surfaces, the vibration characteristics can be improved.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1A and 1B are a perspective view showing an example of an inverted-mesa type AT vibrating piece manufactured by the method of manufacturing a piezoelectric vibrating piece according to the present invention, and a cross-sectional view taken along line AA thereof.

In this inverted-mesa AT vibrating reed, only the center portion of the piezoelectric vibrating reed 31 made of rectangular plate-shaped quartz is thinly processed as the vibrating portion 31a, and the outer peripheral portion is thickly processed as the reinforcing frame 31b. Excitation electrodes 32 are formed on the front and back surfaces of the vibrating portion 31a, and connection electrodes 33 are formed at one end of the reinforcing frame 31b to supply current to each excitation electrode 32.

FIGS. 2 to 4 are process diagrams showing a first embodiment of the method for manufacturing a piezoelectric vibrating reed according to the present invention.

First, a quartz wafer (substrate) 41 is prepared (FIG. 2A), and Cr is deposited on both sides of the quartz wafer 41 to a thickness of 5 mm.
Then, a Cr film 42 is formed by vapor deposition or sputtering until the thickness reaches 00 Å, and Au is further deposited to a thickness of 10 Å.
Deposit or sputter until Au reaches 00 °
The film 43 is formed as a corrosion-resistant film of hydrofluoric acid (FIG. 2)
(B)). Then, a photoresist is applied to the surface of the Au film 43 and dried to form a photoresist film 44 (FIG. 2C).

Next, a photomask 45 on which an etching pattern for forming the outer shape of the piezoelectric vibrating reed 31 is drawn is arranged on the photoresist film 44, and the photomask 45 is exposed to ultraviolet rays to change the etching pattern of the photomask 45 to photolithography. This is transferred to the resist film 44 (FIG. 2D). Then, the photosensitive portion of the photoresist film 44 is developed and removed with a developing solution to expose the Au film 43 (FIG. 2E).

Next, the exposed Au film 43 is etched with an Au etching solution composed of, for example, an aqueous solution of iodine and potassium iodide to expose the Cr film 42, and the exposed Cr film 42 is further etched with a Cr etching solution. Etching with
The crystal wafer 41 is exposed (FIG. 3A).

The steps so far are the same as the conventional steps shown in FIGS. 12A to 12E and FIG. 13A, but the steps of the present embodiment are shown in FIGS. 13B and 13C. It is characterized in that the conventional steps shown are omitted. That is, since the remaining photoresist film 44 is not exposed and can be exposed again by ultraviolet rays, the photoresist film 44 is used for forming the outer shape of the piezoelectric vibrating piece 31 and the shape of the vibrating portion 31a. Use again. As a result, it is not necessary to form and remove a new photoresist film 26 as in the related art, so that the process can be simplified, the operation efficiency can be improved, and the operation cost can be reduced.

However, since the photoresist film 44 is exposed to the etching solution for Au or the etching solution for Cr, the sensitivity of the photoresist film 44 is lowered. Therefore, when exposing the photoresist film 44 again with ultraviolet rays, the exposure time is made longer than usual, or the exposure power is made larger than usual to increase the exposure amount more than usual, thereby compensating for the decrease in the sensitivity of the photoresist film 44. To do. Alternatively, since the portion where the sensitivity is lowered is the surface layer of the photoresist film 44, the surface layer is removed with an alkali solution such as a developing solution to return the sensitivity of the photoresist film 44 to the original state.

Hereinafter, the subsequent steps of this embodiment will be described. A photomask 47 in which an etching pattern for forming the shape of the vibrating portion 31a is formed on the photoresist film 44 is arranged, and the photomask 47 is exposed to ultraviolet light.
Is transferred to the photoresist film 44 (FIG. 3B). Then, the photosensitive portion of the photoresist film 44 is developed and removed with a developing solution to expose the Au film 43 (FIG. 3C).

Next, the exposed crystal wafer 41 is etched with a crystal etching solution composed of, for example, a mixed solution of hydrofluoric acid and ammonium fluoride to form the outer shape of the piezoelectric vibrating reed 31 (FIG. 4A). )). On the other hand, the exposed Au film 43 is etched with the above-described Au etching solution,
The Cr film 42 is exposed, and the exposed Cr film 42 is etched with the above-described etching solution for Cr to expose the quartz wafer 41 (FIG. 4B).

Next, the exposed crystal wafer 41 is half-etched with the above-described etching liquid for crystal to form the vibrating portion 31a of the piezoelectric vibrating piece 31 (FIG. 4).
(C)). Then, the remaining photoresist film 44
Then, the Cr film 42 and the Au film 43 are peeled off. Thereby, the plurality of piezoelectric vibrating reeds 3 having the vibrating portion 31a and the reinforcing frame 31b are provided.
1 is completed (FIG. 4D).

FIG. 5 is a process chart showing a second embodiment of the method for manufacturing a piezoelectric vibrating reed according to the present invention. The steps of this embodiment are the same as the steps of FIGS. 2A to 2E and 3A to 3C of the steps of the first embodiment, so that the illustration and description are omitted, The following steps will be described. The first
Components that are the same as the components shown in the process diagrams of the embodiments are denoted by the same reference numerals.

The exposed portion of the photoresist film 44 is removed by developing with a developing solution to expose the Au film 43 (FIG. 5).
(A)) The exposed quartz wafer 41 is half-etched with the above-described quartz etchant (FIG. 5B).
On the other hand, the exposed Au film 43 is etched with the above-described etching solution for Au to expose the Cr film 42, and the exposed Cr film 42 is etched with the above-described etching solution for Cr to expose the quartz wafer 41. (FIG. 5
(C)).

Next, the half-etched quartz wafer 4
1 is etched with the above-described etching solution for quartz to form the outer shape of the piezoelectric vibrating piece 31, and at the same time, the exposed quartz wafer 41 is half-etched with the same etching solution for quartz to form the vibrating portion 31a of the piezoelectric vibrating piece 31. Is formed (FIG. 5D). Then, the remaining photoresist film 44, Cr film 42, and Au film 43 are removed. Thus, a plurality of piezoelectric vibrating reeds 31 having the vibrating portion 31a and the reinforcing frame 31b are completed (FIG. 5E).

According to the above-described method, in addition to the effect of the first embodiment, the etching process for forming the outer shape of the piezoelectric vibrating reed 31 is stopped at the half etching stage and is performed later. Since the etching process for forming the outer shape of the piezoelectric vibrating reed 31 and the etching process for forming the shape of the vibrating portion 31a of the piezoelectric vibrating reed 31 are made to proceed at the same time and almost finished at the same time. In comparison, the etching time of the quartz wafer 41 can be reduced.

For example, conventionally, the etching time for forming the shape of the piezoelectric vibrating reed 11 is two hours, and the etching time for forming the shape of the vibrating portion 11a of the piezoelectric vibrating reed 11 is one hour, ie, the whole time. 3 for etching time
In the present embodiment, it takes one hour to perform the etching process for forming the outer shape of the piezoelectric vibrating piece 31, and the etching process for forming the outer shape of the piezoelectric vibrating piece 31 is performed later. 1 hour for the shape of the vibrating portion 31a of the piezoelectric vibrating reed 31 including the above, that is, 2 hours for the etching process for the quartz wafer 41.

Further, since the etching time of the quartz wafer 41 is reduced, the reinforcing frame 31b of the piezoelectric vibrating reed 31 is reduced.
Can be prevented from being chipped due to over-etching of the outer edge portion of the above. Therefore, the vibration portion 31a can be enlarged by reducing the reinforcing frame 31b, and spurious can be suppressed.

In each of the above embodiments, the quartz wafer 41
Vibrating portion 31a having a shape etched from both sides
Although the method of manufacturing the piezoelectric vibrating reed 31 having the above has been described, the present invention can also be applied to a method of manufacturing a piezoelectric vibrating reed having a vibrating portion having a shape obtained by etching the crystal wafer 41 from one side, which will be described below.

FIGS. 6 to 8 are process diagrams showing a third embodiment of the method of manufacturing a piezoelectric vibrating reed according to the present invention in correspondence with FIGS. 2 to 4, and the same components are denoted by the same reference numerals.

First, a quartz wafer 41 is prepared (FIG. 6).
(A)), a Cr film 42 is formed on both surfaces of the quartz wafer 41 by depositing or sputtering Cr to a thickness of 500 angstroms, and an Au film is formed by depositing or sputtering Au to a thickness of 1000 angstroms. 43 to form a corrosion resistant film of hydrofluoric acid (FIG. 6)
(B)). Then, a photoresist is applied to the surface of the Au film 43 and dried to form a photoresist film 44 (FIG. 6C).

Next, a photomask 45 on which an etching pattern for forming the outer shape of the piezoelectric vibrating reed is formed is arranged on the photoresist film 44 on one side, and the etching pattern of the photomask 45 is exposed by ultraviolet rays. The image is transferred to the photoresist film 44 (FIG. 6D). Then, the photosensitive portion of the photoresist film 44 is developed and removed with a developing solution to expose the Au film 43 (FIG. 6E).

Next, the exposed Au film 43 is replaced with the Au film described above.
Then, the Cr film 42 is exposed by etching with an etching solution for etching, and the exposed Cr film 42 is further etched with the etching solution for Cr to expose the quartz wafer 41 (FIG. 6F).

Next, the photoresist film 4 remaining on one side
A photomask 47 on which an etching pattern for forming the shape of the vibrating portion of the piezoelectric vibrating reed is drawn is arranged on 4, and the exposure time is longer than usual, the exposure power is larger than usual, and the exposure amount of ultraviolet rays is increased. Exposure is performed by increasing the thickness of the photoresist layer 44, or the surface layer of the photoresist film 44 is removed with an alkaline solution such as a developing solution, and then exposed to ultraviolet light to form an etching pattern for forming the shape of the vibration portion 51a of the photomask 47. It is transferred to a photoresist film 44 (FIG. 7A). Then, the photosensitive portion of the photoresist film 44 is developed and removed with a developing solution to expose the Au film 43 (FIG. 7B).

Next, the exposed quartz wafer 41 is etched with the above-described quartz etchant to form the outer shape of the piezoelectric vibrating reed (FIG. 7C). Meanwhile, the exposed Au
The film 43 is etched with the above-described etching solution for Au, thereby exposing the Cr film 42, and further exposing the exposed Cr film 42.
Is etched with the above-described etching solution for Cr to expose the quartz wafer 41 (FIG. 8A).

Next, the exposed crystal wafer 41 is half-etched with the above-described etching liquid for crystal to form the shape of the vibrating portion of the piezoelectric vibrating reed (FIG. 8B). And
The remaining photoresist film 44 and Cr film 42, Au
The film 43 is peeled. Thus, a plurality of piezoelectric vibrating reeds 51 having the vibrating portion 51a and the reinforcing frame 51b are completed.
(C)).

According to the above method, the photoresist film 4
4 is used again to form the outer shape of the piezoelectric vibrating reed 51 and the shape of the vibrating portion 51a, so that it is not necessary to form and peel off a new photoresist film 26 as in the related art, thereby simplifying the process. Work efficiency can be improved and work costs can be reduced. Further, a photomask 47
Need only be transferred to the photoresist film 44 on one side, there is no need to perform the alignment of the photomasks 47 on both sides performed in the first embodiment, and the CI caused by the displacement of the photomask 47 is eliminated. Deterioration of the value, generation of spurious, and the like can be suppressed.

Although not shown, also in the case of the third embodiment, the etching process for forming the outer shape of the piezoelectric vibrating reed 51 is performed in the second embodiment shown in FIG. The etching is stopped at the stage of the half etching, and the etching process for forming the outer shape of the piezoelectric vibrating reed 51 and the etching process for forming the shape of the vibrating portion 51a of the piezoelectric vibrating reed 51 are performed simultaneously. It can be terminated almost simultaneously. According to this method, in addition to the effects of the second embodiment, it is possible to shorten the etching time of the quartz crystal wafer 41 as compared with the conventional case, and to cover the outer edge of the outer periphery of the reinforcing frame 51b of the piezoelectric vibrating reed 51. -Chipping due to etching can be prevented. Therefore, the vibrating portion 51a can be enlarged by reducing the reinforcing frame 51b,
Spurious can be suppressed.

In the above-described third embodiment, the etching process of the crystal wafer 41 is performed from one side. However, the etching process of the crystal wafer 41 may be performed from both surfaces, which will be described below.

FIGS. 9 and 10 are process diagrams showing a fourth embodiment of the method for manufacturing a piezoelectric vibrating reed according to the present invention. The process of this embodiment is the same as the process of the third embodiment shown in FIGS.
Since the steps up to (F) are the same, illustration and description are omitted, and the following steps will be described. The same components as those shown in the process diagrams of the third embodiment are denoted by the same reference numerals.

A photomask 47 in which an etching pattern for forming the shape of the vibrating portion 51a is formed on the photoresist film 44 remaining on one side is provided, and the exposure time is made longer than usual and the exposure power is made more than usual. Bigger,
Exposure is performed by increasing the exposure amount of ultraviolet light more than usual, or the surface layer of the photoresist film 44 is removed with an alkali solution such as a developing solution and then exposed to ultraviolet light, and the etching pattern of the photomask 47 is transferred to the photoresist film 44. I do.
At the same time, the entire surface of the other one side of the photoresist film 44 is also exposed to ultraviolet rays (FIG. 9A). Then, the photosensitive portion of the photoresist film 44 is developed and removed with a developing solution to expose the Au film 43 (FIG. 9B).

Next, the exposed crystal wafer 41 is half-etched with the above-described crystal etching solution (FIG. 9).
(C)). On the other hand, the exposed Au film 43 is etched with the above-described etching solution for Au to expose the Cr film 42, and the exposed Cr film 42 is etched with the above-described etching solution for Cr to expose the quartz wafer 41. (FIG. 10A).

Next, the half-etched quartz wafer 4
1 is etched from both sides with the above-mentioned etching solution for quartz to form the outer shape of the piezoelectric vibrating piece, and at the same time, the exposed quartz wafer 41 is half-etched from both sides with the same etching solution for quartz to make the vibration of the piezoelectric vibrating piece. The shape of the part is formed (FIG. 10B). Then, the remaining photoresist film 44, Cr film 42, and Au film 43 are removed. Thus, a plurality of piezoelectric vibrating reeds 51 having the vibrating portion 51a and the reinforcing frame 51b are completed (FIG. 10C). According to this method, in addition to the effects of the third embodiment, the etching time of the quartz wafer 41 can be further reduced, and the outer edge of the outer edge of the reinforcing frame 51b of the piezoelectric vibrating reed 51 is overetched. Can be prevented from being chipped. Therefore, the oscillating portion 5 is reduced by reducing the reinforcing frame 51b.
1a can be enlarged, and spurious can be suppressed. Further, since both surfaces of the vibrating portion 51a are etched surfaces, the vibration characteristics are improved.

[0065]

As described above, according to the present invention, when the same photoresist film is used for forming the outer shape of the piezoelectric vibrating reed and the shape of the vibrating portion, a new photoresist film is used as in the prior art. There is no need to form and peel off a film, so that the process can be simplified, the working efficiency can be improved, and the working cost can be reduced. In addition, the etching process for forming the outer shape of the piezoelectric vibrating reed is stopped at the half etching stage, and the etching process for forming the outer shape of the piezoelectric vibrating reed is performed later. In the case where the etching processes for forming the shape of the vibrating portion are simultaneously performed and almost simultaneously completed, the etching time of the quartz wafer can be reduced as compared with the related art. Further, since the etching time of the quartz crystal wafer is shortened, it is possible to prevent the outer edge of the reinforcing frame of the piezoelectric vibrating piece from being chipped by over-etching, and to reduce the size of the reinforcing frame and enlarge the vibrating portion. And spurs can be suppressed.

In the case where the etching pattern of the photomask is transferred only to the photoresist film on one side, it is not necessary to align the photomasks on both sides.
It is possible to suppress the deterioration of the CI value, the occurrence of spurious, and the like caused by the shift of the photomask. Also, when both surfaces of the vibrating part are etched surfaces, the vibration characteristics are good.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of an inverted-mesa AT vibrating piece manufactured by a method of manufacturing a piezoelectric vibrating piece according to the present invention, and FIG.
FIG.

FIG. 2 is a first process chart showing a first embodiment of a method for manufacturing a piezoelectric vibrating reed according to the present invention.

FIG. 3 is a second process chart showing the first embodiment of the method for manufacturing a piezoelectric vibrating reed according to the present invention.

FIG. 4 is a third process chart showing the first embodiment of the method for manufacturing a piezoelectric vibrating reed according to the present invention.

FIG. 5 is a process chart showing a second embodiment of the method for manufacturing a piezoelectric vibrating reed according to the present invention.

FIG. 6 is a first process chart showing a third embodiment of the method for manufacturing a piezoelectric vibrating reed according to the present invention.

FIG. 7 is a second process chart showing a third embodiment of the method for manufacturing a piezoelectric vibrating reed according to the present invention.

FIG. 8 is a third process diagram showing a third embodiment of the method for manufacturing a piezoelectric vibrating reed according to the present invention.

FIG. 9 is a first process chart showing a fourth embodiment of the method for manufacturing a piezoelectric vibrating reed according to the present invention.

FIG. 10 is a second process diagram showing a fourth embodiment of the method for manufacturing a piezoelectric vibrating reed according to the present invention.

FIG. 11 is a perspective view showing an example of a general inverted mesa AT vibrator and a cross-sectional view taken along line AA thereof.

FIG. 12 is a first process chart showing details of a conventional method for manufacturing an inverted-mesa AT vibrator.

FIG. 13 is a second process chart showing details of a method for manufacturing a conventional inverted-mesa AT vibrator.

FIG. 14 is a third process chart showing details of a method for manufacturing a conventional inverted-mesa AT vibrator.

[Explanation of symbols]

 31 piezoelectric vibrating piece 31a vibrating part 31b reinforcing frame 32 excitation electrode 33 connecting electrode 41 quartz wafer 42 Cr film 43 Au film 44 photoresist film 45 photomask 47 photomask 51 piezoelectric vibrating piece 51a vibrating part 51b reinforcing frame

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Osamu Iwamoto 3-3-5 Yamato, Suwa City, Nagano Prefecture Inside Seiko Epson Corporation (72) Inventor Fumitaka Kitamura 3-3-5 Yamato Suwa City, Nagano Prefecture Seiko Epson F term in reference (reference) 2H096 AA27 CA05 EA02 EA12 GA02 HA13 HA14 HA17 JA04 5J108 MM08

Claims (8)

[Claims] 1. A method of manufacturing a piezoelectric vibrating reed having a central portion made thinner, comprising: forming a corrosion-resistant film and a photoresist film on a substrate of the piezoelectric vibrating reed; An unnecessary portion of the photoresist film is exposed, developed and removed, an unnecessary portion of the corrosion-resistant film corresponding to the outer shape of the piezoelectric vibrating piece is removed by etching, and the photo corresponding to the shape of the central portion of the piezoelectric vibrating piece is removed. The unnecessary portion of the resist film is exposed, developed and removed, the exposed portion of the substrate is etched, and the unnecessary portion of the corrosion-resistant film corresponding to the shape of the central portion of the piezoelectric vibrating reed is removed by etching. A method for manufacturing a piezoelectric vibrating reed, wherein a shape including a central portion of the piezoelectric vibrating reed is formed by etching an exposed portion. 2. The method for manufacturing a piezoelectric vibrating reed according to claim 1, wherein the second exposure of the photoresist film is performed by increasing the exposure amount at the time of the first exposure of the photoresist film. 3. The manufacturing of the piezoelectric vibrating reed according to claim 1, wherein the second exposure of the photoresist film is performed after removing a surface layer of the photoresist film after the first removal of the photoresist film. Method. 4. An etching process for the substrate of the piezoelectric vibrating reed comprises forming the outer shape of the piezoelectric vibrating reed by etching from both sides of the substrate corresponding to the outer shape of the piezoelectric vibrating reed, and thereafter forming the piezoelectric vibrating reed. 4. The method of manufacturing a piezoelectric vibrating reed according to claim 1, wherein half-etching is performed on both surfaces of the substrate corresponding to the shape of the central portion of the vibrating reed. 5. An etching process for the substrate of the piezoelectric vibrating reed comprises forming an outer shape of the piezoelectric vibrating reed by etching from one surface of the substrate corresponding to an outer shape of the piezoelectric vibrating reed, and thereafter forming the piezoelectric vibrating reed. 4. The method of manufacturing a piezoelectric vibrating reed according to claim 1, wherein half-etching is performed from one surface of the substrate corresponding to a shape of a central portion of the vibrating reed. 6. The etching process of the substrate of the piezoelectric vibrating reed includes half-etching from both sides of the substrate corresponding to the outer shape of the piezoelectric vibrating reed, and then corresponding to the shape of the central portion of the piezoelectric vibrating reed. 4. The method of manufacturing a piezoelectric vibrating reed according to claim 1, wherein half-etching is performed from both surfaces of the substrate while simultaneously etching from both surfaces of the substrate corresponding to the outer shape of the piezoelectric vibrating reed that has been half-etched. 5. 7. The etching process of the substrate of the piezoelectric vibrating reed corresponds to half-etching from one surface of the substrate corresponding to the outer shape of the piezoelectric vibrating reed, and then corresponds to the shape of the central portion of the piezoelectric vibrating reed. 4. The method of manufacturing a piezoelectric vibrating reed according to claim 1, wherein half-etching is performed on one side of the substrate, and simultaneously, etching is performed on one side of the substrate corresponding to the external shape of the half-etched piezoelectric vibrating reed. 5. 8. The etching process for the substrate of the piezoelectric vibrating reed may be half-etched from one side of the substrate corresponding to the outer shape of the piezoelectric vibrating reed, and then may correspond to the shape of the central portion of the piezoelectric vibrating reed. 4. The method of manufacturing a piezoelectric vibrating reed according to claim 1, wherein half-etching is performed on one side of the substrate and etching is performed on the entire other side of the substrate at the same time.