JP5465573B2 - Manufacturing method of tuning fork type crystal piece - Google Patents

Description

  The present invention relates to a method for manufacturing a tuning fork type crystal piece used in an electronic apparatus.

Conventionally, a piezoelectric vibrator or a piezoelectric oscillator is mounted as an electronic component in an electronic device such as a computer, a mobile phone, or a small information device. This piezoelectric vibrator or piezoelectric oscillator is used as a reference signal source or a clock signal source. In addition, piezoelectric vibrators and piezoelectric oscillators are equipped with a piezoelectric vibration element made of quartz.
Hereinafter, a piezoelectric vibration element using quartz as a piezoelectric material will be described.
As shown in FIG. 8, a tuning fork-type bending crystal resonator element 400 that is one of piezoelectric resonator elements includes a crystal resonator element 410, an excitation electrode, a connection electrode, and a frequency provided on the surface of the crystal resonator element 410. It is roughly constituted by an adjustment metal film and a conductive wiring pattern.

The quartz crystal vibrating piece 410 has a tuning fork shape, and is roughly constituted by a base portion 411 and a pair of vibrating arm portions 412 extending from the base portion 411. The vibrating arm portion 412 is provided with an excitation electrode 421 having the same polarity on opposing planes.
The base 411 is a substantially rectangular flat plate in plan view. The vibrating arm portion 412 includes a first vibrating arm portion 412a and a second vibrating arm portion 412b. The first vibrating arm portion 412a and the second vibrating arm portion 412b are extended in the same direction from one side of the base portion 411, and the length direction of the first vibrating arm portion 412a and the second vibrating arm portion 412b. Each is provided with a groove GL. The groove portion GL is formed on both main surfaces of the first vibrating arm portion 412a and the second vibrating arm portion 412b from the boundary portion with the base portion 411 toward the tip of the vibrating arm portion 412 in the longitudinal direction. Are provided in parallel with each other at a predetermined length. In such a quartz crystal vibrating piece 410, the base portion 411 and the vibrating arm portion 412 are integrally formed into a tuning fork shape, and is manufactured by a photolithography technique, a chemical etching technique, and a film forming technique.

  The electrode provided on the first vibrating arm portion 412 a is composed of an excitation electrode 421 and a frequency adjusting metal film 423. The excitation electrode 421 is provided on one main surface including the inner surface of the groove portion GL of the first vibrating arm portion 412a and the other main surface including the inner surface of the groove portion GL of the first vibrating arm portion 412a. The excitation electrode 421 has a different polarity between the inner side surface of the first vibrating arm portion 412a facing the second vibrating arm portion 412b and the outer side surface of the first vibrating arm portion 412a facing the side surface. It is provided to become. The frequency adjusting metal film 423 is provided on both main surfaces of the distal end portion of the first vibrating arm portion 412a.

  The electrode provided on the second vibrating arm portion 412 b is composed of an excitation electrode 421 and a frequency adjusting metal film 423. The excitation electrode 421 is provided on one main surface including the inner surface of the groove portion GL of the second vibrating arm portion 412b and the other main surface including the inner surface of the groove portion GL of the second vibrating arm portion 412b. . The excitation electrode 421 has a different polarity between the inner side surface of the second vibrating arm portion 412b facing the first vibrating arm portion 412a and the outer side surface of the second vibrating arm portion 412b facing the side surface. It is provided to become. The frequency adjusting metal film 423 is provided on both main surfaces of the distal end portion of the second vibrating arm portion 412a.

The base 411 is provided with two pairs of connection electrodes 422. One connection electrode 422 is provided from one corner end of the side opposite to the side where the vibrating arm portion 412 of the base 411 is formed and from one main surface of the base 411 to the other main surface. Yes. The other connection electrode 422 is provided from the other corner end of the side opposite to the side where the vibrating arm portion 412 of the base 411 is formed and from one main surface of the base 411 to the other main surface. It has been.
The base portion 411 and the vibrating arm portion 412 are provided with a conductive wiring pattern 424 for electrically connecting predetermined electrodes.

  One connection electrode 422 is electrically connected to an excitation electrode 421 provided on one main surface of the first vibrating arm portion 412a by a conductive wiring pattern 424 provided on one main surface of the base 411. In addition, it is electrically connected to the excitation electrode 421 provided on the outer side surface of the second vibrating arm portion 412b. In addition, the excitation electrode 421 provided on the outer side surface of the second vibrating arm portion 412b is electrically connected to the excitation electrode 421 provided on the inner side surface of the second vibrating arm portion 412b. Furthermore, the excitation electrode 421 provided on one main surface of the first vibrating arm portion 412 is connected to the first vibrating arm portion by the conductive wiring pattern 424 provided on the inner side surface of the first vibrating arm portion 412. It is electrically connected to an excitation electrode 421 provided on the other main surface of 412a.

  The other connection electrode 422 is electrically connected to the excitation electrode 421 provided on the other main surface of the second vibrating arm portion 412b by a conductive wiring pattern provided on the other main surface of the base portion 411. And, it is electrically connected to the excitation electrode 421 provided on the outer side surface of the first vibrating arm portion 412a. In addition, the excitation electrode 421 provided on the outer side surface of the first vibrating arm portion 412a is electrically connected to the excitation electrode 421 provided on the inner side surface of the first vibrating arm portion 412a. Further, the excitation electrode 421 provided on the other main surface of the second vibrating arm portion 412a is connected to the first vibrating arm portion by the conductive wiring pattern 424 provided on the inner side surface of the second vibrating arm portion 412b. It is electrically connected to an excitation electrode 421 provided on one main surface of 412a.

  The excitation electrode 421, the connection electrode 422, the frequency adjusting metal film 423, and the conductive wiring pattern 424 are formed by sputtering, vapor deposition, or photolithography, and a laminated structure in which an Au layer is provided on a Cr layer. It has become.

  When the crystal vibrating piece 410 is vibrated, an alternating voltage is applied to the connection electrode 422. When an electrical state after application is instantaneously captured, the excitation electrodes 421 provided on both main surfaces of the first vibrating arm portion 412a have a positive potential, and the excitation electrodes 421 provided on both side surfaces are negative. An electric field is generated from positive to negative. At this time, the excitation electrodes 421 on both main surfaces of the second vibrating arm portion 412b have a negative potential, and the excitation electrodes 421 provided on both side surfaces have a positive potential, the excitation electrodes 421 of the first vibrating arm portion 412. The polarity is opposite to the polarity generated in, and an electric field is generated from plus to minus. The electric field generated by the alternating voltage causes an expansion / contraction phenomenon in the first vibrating arm portion 412a and the second vibrating arm portion 412b, and a bending vibration mode having a resonance frequency set in the vibrating arm portion 412 is set. The resonance frequency can be adjusted by increasing or decreasing the amount of metal constituting the frequency adjusting metal film 423 provided on the crystal vibrating piece 410 (see, for example, Patent Document 1 or 2).

Further, in the manufacturing method of such a tuning fork-type bending crystal resonator element 400, first, the crystal resonator element 410 is formed on the tuning fork type, and then the electrodes are formed.
For example, a corrosion resistant film (not shown) such as Cr or Cr + Au is formed on the front and back of a quartz wafer (not shown) by sputtering.

  Next, a photosensitive resist (positive type) is formed on both sides of the anticorrosion film, and after drying, exposure, development, drying (patterning) and anticorrosion other than the tuning fork shape so that the anticorrosion film on the front and back sides remains. Etch the film.

  Next, a photosensitive resist (positive type) is patterned on the front and back corrosion-resistant films in order to determine the shape of the electrodes. Here, a part of the photosensitive resist is provided so as to cover a connection portion between the vibrating arm portion and the base portion.

Next, the exposed crystal portion is etched. At this time, the shape of the groove and the shape of the crystal vibrating piece 410 are formed simultaneously.
Next, the corrosion-resistant film exposed on the back surface is etched to obtain a crystal surface. Next, an electrode film is formed on the entire surface by a vapor deposition technique.
Next, the photosensitive resist formed on the front and back and the electrode film formed thereon are peeled off. This can be easily removed by immersing it in a solution for dissolving the photosensitive resist. However, the anticorrosion film that remains in the lower portion remains. Next, the remaining corrosion-resistant film is etched.
In this way, electrodes are formed on the crystal vibrating piece 410 (see Patent Document 1).

It is known that the tuning fork-type bending crystal resonator element 400 manufactured in this way has a complicated cross-sectional shape of the groove formed in the vibrating arm (see, for example, Patent Document 3).
For example, the groove portion provided in the vibrating arm portion has a depth in the thickness direction from the edge portion in the length direction, and is substantially U-shaped by four slopes having gradients.
In addition, a tuning fork-type bending crystal resonator element in which the cross-sectional shape of the groove portion is substantially V-shaped has been proposed (see, for example, Patent Document 4). In such a tuning-fork type bending crystal resonator element, a groove is formed separately from the formation of the outer shape.

JP 2007-329879 A JP 2004-248237 A JP 2006-148856 A JP 2007-329879 A

However, the tuning fork type quartz crystal resonator element 400 having a groove portion having a substantially U-shaped cross section passes through the center of two short sides located at both ends of the groove portion in the length direction of the groove portion. Since the cross-sectional shape is asymmetric with respect to the center line extending along the length direction, the vibration balance is deteriorated.
Further, in the tuning fork-type bending quartz crystal vibration element 400 having a groove portion having a substantially U-shaped cross section, when an alternating voltage is applied to the excitation electrode provided in the groove portion and the excitation electrode provided on the side surface of the vibration arm portion, The slopes of different slopes forming the grooves may cause the electric field generated in the vibrating arm portion to be non-uniform, thereby losing the vibration balance and increasing the CI (crystal impedance) value.
As described above, when the sectional shape of the groove portion is asymmetric with respect to the center line, the conventional tuning-fork type bending crystal resonator element 400 changes its frequency when subjected to a drop impact, and the tuning-fork type bending quartz crystal 400 The frequency temperature characteristics of the vibration element may be deteriorated.

  Accordingly, the present invention provides a method for manufacturing a tuning-fork type bending crystal resonator element that solves the above-described problems, improves the symmetry of the cross-sectional shape of the groove portion provided in the vibrating arm portion, and can be easily manufactured. Let it be an issue.

In order to solve the above problems, the present invention is a method of manufacturing a tuning fork type crystal piece having a structure including a base portion and a vibrating arm portion extending from the base portion, the vibrating arm portion having a groove portion in a length direction. The direction in which the vibrating arm portion of the tuning-fork type crystal piece is extended is the Y′-axis direction, the direction orthogonal to the Y′-axis and the arrangement of the vibrating arm portions is the X-axis direction, and the crystal axis of the crystal Corrosion-resistant film forming step for forming a corrosion-resistant film on the front and back of the quartz wafer , where one direction perpendicular to a certain Y-axis is the + X-axis and the other direction is the -X-axis, and on the corrosion-resistant film A photosensitive resist forming step for forming a photosensitive resist; and exposure, development, and the like so that the photosensitive resist in a groove portion is removed while leaving the photosensitive resist in a tuning fork shape after the photosensitive resist is dried. Exposure and development process for drying, and resistance to resist remaining in the groove portion. A patterning step for removing the corrosion film and a corrosion-resistant film other than a tuning fork shape, a photosensitive resist removal step for removing the photosensitive resist, and a wet etching step for wet etching the exposed crystal portion of the crystal wafer. In the exposure and development process, the photosensitive resist in the portion that becomes the groove portion becomes the groove portion from one edge portion facing the + X-axis side in the length direction of the portion that becomes the groove portion to the other edge portion. In the patterning step, the corrosion-resistant film in the portion to be the groove portion is removed in a state where the oblique pattern portion provided obliquely in parallel with the Y′-axis direction is left. It is removed, leaving a diagonal pattern portions provided obliquely in the portion serving as the groove over the edge portion on the side facing the edge portion facing the + X-axis side in the longitudinal direction, the wet In the etching process, the exposed quartz in the portion that becomes the groove portion in the shape including the corrosion-resistant film left as the oblique pattern portion is removed, and the quartz in the portion protected by the corrosion-resistant film left as the oblique pattern portion The tuning-fork type crystal piece is characterized by being also removed.

According to such a method of manufacturing a tuning fork type crystal piece of the present invention, in the exposure and development process, the photosensitive resist in the portion to be the groove portion is changed from one edge portion in the length direction of the portion to be the groove portion to the other. The portion of the corrosion-resistant film in the portion that becomes the groove portion is removed in a patterning process, leaving the oblique pattern portion provided obliquely in the portion that becomes the groove portion over the edge portion of the groove portion. In the wet etching step, the oblique pattern portion is removed while leaving the oblique pattern portion provided obliquely in the portion that becomes the groove portion from one edge portion in the length direction to the other edge portion. Since the exposed quartz in the portion that becomes the groove is removed in the shape including the corrosion-resistant film left as a portion, the portion of the quartz protected by the corrosion-resistant film left as the oblique pattern portion is also removed. So that the crystal portion to be protected by the corrosion-resistant film left as over emission portion is removed in a state of being side-etched.
Thereby, the number of the slopes which form a groove part decreases, and a groove part can be formed in the cross-sectional shape in which the symmetry was improved.

  Further, in the patterning step, the extending direction of the vibrating arm portion of the tuning-fork type crystal piece is the Y′-axis direction, the direction orthogonal to the Y′-axis and the vibrating arm portion is arranged is the X′-axis direction, and When one direction perpendicular to the Y axis, which is the crystal axis of quartz, is the + X axis and the other direction is the -X axis, the corrosion-resistant film left in the groove portion is the groove portion. Since it remains as an oblique pattern portion provided obliquely in the portion that becomes the groove portion from the edge portion facing the + X axis side in the length direction of the portion to the opposite edge portion, wet etching in the groove portion It is possible to prevent an increase in slopes having different slopes by suppressing the progression of the slope. Thereby, the number of the slopes which form a groove part decreases, and a groove part can be formed in the cross-sectional shape in which the symmetry was improved.

(A) is a perspective view which shows an example of a tuning fork type crystal piece, (b) is AA sectional drawing of (a), (c) is a conceptual diagram which shows an axial direction. (A) is a conceptual diagram which shows a quartz wafer, (b) is a conceptual diagram which shows the state in which the corrosion-resistant film was formed. (A) is a conceptual diagram which shows the state in which the photosensitive resist was formed, (b) is a conceptual diagram which shows an example of the state which exposed and developed. (A) is the elements on larger scale which expanded a part of Drawing 3 (b), and (b) is a key map showing other examples of the state of an oblique pattern part. (A) is a conceptual diagram which shows the state which removed the corrosion-resistant film | membrane which exposes, (b) is a conceptual diagram which shows the state which removed the photosensitive resist. (A) is a conceptual diagram which shows the state of the crystal wafer after wet etching is completed. It is a figure which shows the cross-sectional shape of the groove part provided in the vibration arm part. It is a perspective view which shows an example of the conventional tuning fork type bending crystal vibration element.

  The best mode for carrying out the present invention (hereinafter referred to as “embodiment”) will be described in detail with reference to the drawings as appropriate. Note that each component is exaggerated for easy understanding of the state.

(Tuning fork crystal piece)
As shown in FIG. 1, the tuning fork type crystal piece 110 has a tuning fork shape, and is roughly constituted by a base portion 111 and a pair of vibrating arm portions 112 extending from the base portion 111.

  In addition, when the crystal axes of the quartz are the X axis, the Y axis, and the Z axis, the new axes when the X axis is rotated within a range of ± 5 ° within the plane including the Z axis and the Y axis are set as the rotation axes. The Y ′ axis. Further, the extending direction of the vibrating arm portion 112 of the tuning fork type crystal piece 110 is the Y′-axis direction, and the direction in which the vibrating arm portion 112 is aligned is orthogonal to the Y′-axis, and the X-axis direction is orthogonal to the Y′-axis. One direction is the + X axis, and the other direction is the -X axis.

The base 111 is a flat plate having a substantially rectangular shape in plan view.
The vibrating arm portion 112 includes a first vibrating arm portion 112a and a second vibrating arm portion 112b.
The first vibrating arm portion 112a and the second vibrating arm portion 112b extend in the same direction from one side of the base 111, and the length direction of the first vibrating arm portion 112a and the second vibrating arm portion 112b. Each is provided with a groove GL.

The groove portion GL is formed on both main surfaces of the first vibrating arm portion 112a and the second vibrating arm portion 112b in the length direction of the vibrating arm portion 112 from the boundary portion with the base 111 toward the tip of the vibrating arm portion 112. For example, two are provided in parallel with each other at a predetermined length.
Such a tuning fork type crystal piece 110 has a base 111 and a vibrating arm portion 112 integrally formed into a tuning fork shape, and is manufactured by a photolithography technique, a chemical etching technique, and a film forming technique.

(Tuning fork type crystal piece manufacturing method)
Next, a method for manufacturing a tuning fork type crystal piece according to an embodiment of the present invention will be described.
A method for manufacturing a tuning fork crystal piece according to an embodiment of the present invention includes a corrosion-resistant film forming step, a photosensitive resist forming step, an exposure development step, a patterning step, a photosensitive resist removing step, and a wet etching step. ing.

(Corrosion-resistant film formation process)
The corrosion resistant film forming step is a step of forming a corrosion resistant film 20 on the front and back of the crystal wafer 10 as shown in FIGS. 2 (a) and 2 (b).
For example, a corrosion resistant film 20 such as Cr or Cr + Au is formed on the front and back of the quartz wafer 10 by sputtering, for example.
2B shows a state where the corrosion resistant film 20 is provided on the crystal wafer 10. In FIG.

(Photosensitive resist formation process)
The photosensitive resist forming step is a step of forming a photosensitive resist 30 on the corrosion resistant film 20 as shown in FIG.
The photosensitive resist 30 is, for example, a positive type and is formed on both main surfaces of the crystal wafer 10 on which the corrosion resistant film 20 is provided.

(Exposure development process)
In the exposure and development process, as shown in FIG. 3B, after the photosensitive resist 30 is dried, the photosensitivity in the portion P that becomes the groove portion GL (see FIG. 1A) is left in a tuning fork shape. The resist 30 is removed in a state where an oblique pattern portion 31 provided obliquely is left in the portion P that becomes the groove portion GL from one edge portion in the length direction of the portion P that becomes the groove portion GL to the other edge portion. It is the process of performing exposure, development, and drying as described. In this exposure and development process, the photosensitive resist 30 in the portion P that becomes the groove portion GL is obliquely provided in the portion P that becomes the groove portion GL from the edge portion in the length direction of the portion P that becomes the groove portion GL. It will be removed with 31 left.

  The photosensitive resist 30 left in the portion P that becomes the groove portion GL remains as an oblique pattern portion 31 in the portion P that becomes the groove portion from the edge portion located on the + X-axis side in the length direction of the portion P that becomes the groove portion GL. Has been.

  A plurality of the oblique pattern portions 31 of the photosensitive resist are provided side by side with a predetermined interval in the length direction of the groove portion GL.

  Here, the + X axis direction, the −X axis direction, and the Y ′ direction exist in three directions because the crystal is a three-fold symmetric crystal as shown in FIG. Thereby, the photosensitive resist 30 left as the direction of the oblique pattern portion provided obliquely is provided in parallel with the Y axis among the Y axes existing in the three directions.

  In other words, as shown in FIG. 4A, the extending direction of the vibrating arm portion 112 extending from the base portion 111 is along one Y-axis direction among the three directions. In this case, the oblique pattern portion 31 is provided in parallel with any one of the two Y′-axis directions passing through the groove GL (see FIG. 4B). Therefore, the direction of the photosensitive resist 30 left as the oblique pattern portion 31 provided in the portion P that becomes the groove portion GL is inclined with respect to the length direction of the portion P that becomes the groove portion GL.

(Patterning process)
As shown in FIG. 5A, the patterning step is a step of removing the corrosion-resistant film 20 remaining in the portion P that becomes the groove GL and the corrosion-resistant film 20 other than the tuning fork shape.
In this patterning step, the corrosion-resistant film 20 in the portion that becomes the groove portion GL is slanted into the portion P that becomes the groove portion GL from one edge portion in the length direction of the portion P that becomes the groove portion GL to the other edge portion. It is removed while leaving the oblique pattern portion 31 provided.

(Photosensitive resist removal process)
The photosensitive resist removal step is a step of removing the photosensitive resist 30 (see FIG. 5A) as shown in FIG.
From this photosensitive resist removing step, the corrosion resistant film 20 is exposed.

(Wet etching process)
The wet etching process is a process of wet etching the exposed crystal portion of the crystal wafer 10.
In the wet etching process, the outer shape is formed into a tuning fork shape, and the exposed quartz crystal in the shape including the anticorrosive film left as the oblique pattern portion 31 is removed, and the oblique pattern portion 31 is removed. The remaining portion of the quartz protected by the corrosion-resistant film is also removed, and the tuning-fork type crystal piece 110 (see FIGS. 1 and 6) is formed together with the groove GL.

Here, the tuning fork type crystal piece 110 manufactured by the method for manufacturing a tuning fork type crystal piece according to the embodiment of the present invention is in a state in which the cross-sectional shape of the groove portion GL is formed in a substantially V shape.
As shown in FIG. 1B, the cross section is in a state of being cut between two side surfaces in the length direction of the vibrating arm portion 112. In the cut shape of the vibrating arm portion 112 in this cut state, one groove portion GL is formed by two slopes, and one slope is formed with a gentler slope than the other slope. Accordingly, the cross-sectional shape of the groove portion GL is formed in a substantially V-shape that is simplified, so that the cross-sectional shape with improved symmetry with respect to the center line CL (see FIG. 3B) (see FIG. 7). Thus, the vibration balance can be improved.

By configuring the method for manufacturing a tuning fork crystal piece in this way, the photosensitive resist 30 in the portion P that becomes the groove portion GL becomes one edge portion in the length direction of the portion P that becomes the groove portion GL in the exposure development process. Is removed while leaving the oblique pattern portion 31 provided obliquely in the portion P that becomes the groove portion GL across the other edge portion, and in the patterning step, the corrosion-resistant film 20 in the portion that becomes the groove portion GL becomes the groove portion. The wet etching is performed while leaving the oblique pattern portion 31 provided obliquely in the portion P that becomes the groove portion GL from one edge portion in the length direction of the portion P that becomes the GL to the other edge portion. The portion protected by the corrosion-resistant film left as the oblique pattern portion 31 while removing the exposed quartz of the portion P that becomes the groove GL in the shape including the corrosion-resistant film left as the oblique pattern portion 31 in the process Crystal also the monkey removed, so that the crystal portion to be protected by the corrosion-resistant film left as a diagonal pattern portion 31 is removed in a state of being side-etched.
As a result, the number of slopes forming the groove GL is reduced, and the groove GL can be formed in a cross-sectional shape with improved symmetry.

  In addition, since the tuning fork type crystal piece manufacturing method is configured as described above, the extending direction of the vibrating arm portion 112 of the tuning fork type crystal piece is in the Y′-axis direction and is orthogonal to the Y′-axis in the patterning step. Then, when the direction in which the vibrating arms 112 are arranged is the X-axis direction, one direction perpendicular to the Y-axis that is the crystal axis of the crystal is the + X-axis, and the other direction is the -X-axis, the groove GL The photosensitive resist 30 left in the portion P becomes a diagonal pattern portion provided obliquely in the portion P that becomes the groove portion GL from the edge portion F on the + X-axis side in the length direction of the portion P that becomes the groove portion GL. Since it remains, the progress of the wet etching in the groove GL can be suppressed, and an increase in slopes with different slopes can be prevented. As a result, the number of slopes forming the groove GL is reduced, and the groove GL can be formed in a cross-sectional shape with improved symmetry.

In addition, although embodiment of this invention was described, this invention can be changed suitably.
For example, the wet etching process may be performed while leaving the photosensitive resist without performing the photosensitive resist removing process. Even if comprised in this way, there exists an effect similar to embodiment of this invention.
Further, the tuning fork type quartz crystal element may be configured by providing an excitation electrode on the tuning fork type crystal piece manufactured by the method of manufacturing a tuning fork type crystal piece according to the embodiment of the present invention.

DESCRIPTION OF SYMBOLS 10 Quartz wafer 20 Corrosion-resistant film 30 Photosensitive resist 31 Diagonal pattern part 110 Tuning fork type crystal piece 111 Base part 112 Vibration arm part 112a 1st vibration arm part 112b 2nd vibration arm part GL Groove part

Claims (1)

A structure comprising a base and a vibrating arm extending from the base, the vibrating arm having a groove in the length direction, and a method for producing a tuning fork crystal piece,
The direction in which the vibrating arm portion of the tuning fork type crystal piece is extended is the Y′-axis direction, the direction orthogonal to the Y′-axis and the arrangement of the vibrating arm portions is the X-axis direction, and Y is the crystal axis of the crystal When one direction perpendicular to the axis is + X axis and the other direction is -X axis,
A corrosion-resistant film forming process for forming a corrosion-resistant film on both sides of the quartz wafer;
A photosensitive resist forming step of forming a photosensitive resist on the corrosion-resistant film;
An exposure and development step of performing exposure, development, and drying so that the photosensitive resist in a groove portion is removed while leaving the photosensitive resist in a tuning fork shape after the photosensitive resist is dried;
A patterning step of removing the corrosion-resistant film remaining in the groove portion and the corrosion-resistant film other than the tuning fork shape;
A photosensitive resist removing step for removing the photosensitive resist;
A wet etching step of wet etching the exposed crystal portion of the crystal wafer;
Including
In the exposure and development process, the photosensitive resist in the portion that becomes the groove portion is in the portion that becomes the groove portion from one edge portion facing the + X axis side in the length direction of the portion that becomes the groove portion to the other edge portion. In addition, it is removed in a state where an oblique pattern portion provided obliquely in parallel with the Y′-axis direction is left,
In the patterning step, the anticorrosion film in the portion that becomes the groove portion is in the portion that becomes the groove portion from the edge portion facing the + X axis side in the length direction of the portion that becomes the groove portion to the edge portion on the opposite side . Is removed with the oblique pattern portion provided obliquely left,
In the wet etching step, the exposed quartz in the portion that becomes the groove portion in a shape including the corrosion-resistant film left as the oblique pattern portion is removed, and the portion protected by the corrosion-resistant film left as the oblique pattern portion A method for producing a tuning fork type crystal piece, wherein the crystal is also removed.

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