JP2013150236A - Manufacturing method of vibration piece - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a vibration piece which accurately forms grooves of the vibration piece.SOLUTION: A vibration piece includes: a base part; and vibration arms which are formed protruding from the base part, and grooves are formed in the vibration arms. A manufacturing method of the vibration piece includes the steps of: concurrently forming an external form pattern of the vibration piece and a pattern, in which film thicknesses of photo resist films 60a corresponding to the grooves are set so as to be thinner than a photo resist film 60 of an internal form of the vibration piece, on the photo resist film 60 covering a metal film 20 formed on a substrate 10; etching the substrate 10 to form an external form of the vibration piece; eliminating the photo resist films 60a corresponding to the grooves to expose the metal film 20; eliminating portions of the metal film 20 corresponding to the grooves; and etching the substrate to form the grooves.

Description

  The present invention particularly relates to a method for manufacturing a resonator element having a groove.

  A tuning fork-type piezoelectric vibrating piece as an example of a vibrating piece has a base portion and two vibrating arms formed so as to protrude from the base portion. A groove is formed in the vibrating arm, and the groove is provided on the front and back of the vibrating arm. For this reason, the cross-sectional shape of the vibrating arm is formed in a substantially H shape. Such a tuning-fork type piezoelectric vibrating piece has a low vibration loss of the vibrating arm and a low CI value, and can reduce the overall shape of the vibrating piece. Conventionally, Patent Documents 1 and 2 can be cited as an example of a method for manufacturing such a resonator element.

  In the method of manufacturing a piezoelectric vibrating piece disclosed in Patent Document 1, first, a corrosion-resistant film is formed on the front surface and the back surface of a quartz wafer, a photoresist film is formed on the corrosion-resistant film, and a first patterning of the photoresist film is performed. . Then, according to the pattern of the photoresist film, the corrosion resistant film is exposed and etched to process the outer shape of the resonator element. Next, the remaining photoresist film is subjected to the second patterning to expose the corrosion-resistant film corresponding to the recessed shape, and the quartz wafer is exposed by etching. This quartz wafer is half-etched to thin it, and the concave shape of the vibration part is processed.

  In the method for manufacturing a crystal resonator disclosed in Patent Document 2, a photoresist film having a predetermined thickness is formed on a quartz substrate, and exposure is performed using a mask with a controlled transmittance, thereby forming photoresist shapes having different thicknesses. Forming. Then, the quartz crystal substrates are collectively dry-etched to form quartz plates having different thicknesses following the photoresist shape.

JP 2002-261557 A Japanese Patent Laid-Open No. 2005-6248

  However, according to the manufacturing method of Patent Document 1, in order to form the outer shape and the recessed shape in separate processes while using the first photoresist film as it is, the two-step patterning of the outer shape and the recessed shape must be performed. I must. When patterning a photoresist film corresponding to the concave shape, there is a problem that it is difficult to accurately align the concave shape with the already formed outer shape. If the position of the recessed shape is not formed as designed, the balance of the vibrating arm is poor and the vibration becomes unstable. For this reason, the stability of the frequency deteriorates, or the resonance frequency of the resonator element deviates from the design value.

Further, according to the manufacturing method of Patent Document 2, a photoresist film is formed directly on a quartz substrate, and this is dry-etched. If it is a concave of about several μm formed in a quartz substrate as in Patent Document 2, it can be formed by dry etching. However, the groove formed in the vibrating arm may have a depth of several tens of μm. It is time consuming and inefficient to form such a groove by dry etching. Also, dry etching has a slow reaction rate and takes time for etching, and is not suitable for mass production. Furthermore, when ions or radicals hit the quartz substrate, there is a problem that alteration is likely to occur, the stability of the frequency is deteriorated, the breakdown current is lowered, and a long-term change in frequency is increased.
Therefore, in order to solve the problems of the prior art, an object of the present invention is to provide a method for manufacturing a resonator element that can accurately form a groove portion of the resonator element.

SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.
Application Example 1 In a method of manufacturing a resonator element including a base portion and a vibrating arm that protrudes from the base portion, and a groove portion is formed on the vibrating arm, a photo that covers a metal film formed on a substrate Simultaneously forming an external pattern of the vibrating piece on the resist film and a pattern in which the film thickness of the photoresist film corresponding to the groove is thinner than that of the photoresist film corresponding to the inner shape of the vibrating piece; Etching the substrate to form the outer shape of the resonator element; removing the photoresist film corresponding to the groove to expose the metal film; and removing the metal film corresponding to the groove And a step of etching the substrate to form the groove.

  Thereby, since the external contour of the vibrating piece and the patterning of the groove portion can be performed simultaneously, the accuracy of the relative position of the outer contour of the vibrating piece and the groove portion can be improved. In addition, since the region corresponding to the groove is covered with the metal film during the etching for forming the outer shape of the resonator element, the groove is not etched simultaneously with the formation of the outer shape. Therefore, the groove portion of the vibrating piece can be formed with high accuracy.

Application Example 2 The method for manufacturing a resonator element according to Application Example 1, wherein the photoresist film corresponding to the groove is removed by exposure to expose the metal film.
As a result, the thin photoresist film corresponding to the groove can be removed easily and in a short time, and the metal film corresponding to the groove can be exposed.

  Application Example 3 The method for manufacturing a resonator element according to Application Example 1, wherein the photoresist film corresponding to the groove is removed by dry etching to expose the metal film.

  As a result, the thin photoresist film corresponding to the groove can be accurately removed, and the metal film corresponding to the groove can be exposed. In addition, since a metal film is formed under the photoresist film, there is no possibility that the substrate is altered by dry etching.

Application Example 4 In the application, the photoresist film corresponding to the groove is removed by exposure using a photomask having an opening larger than the photoresist film to expose the metal film. A method for manufacturing the resonator element according to Example 1.
Accordingly, the thin photoresist film corresponding to the groove portion can be reliably exposed to ultraviolet rays, and the groove portion of the resonator element can be formed with high accuracy.

[Application Example 5] In the application example 1, the photoresist film corresponding to the groove portion is further removed by development after the step of forming the outer shape of the vibrating piece to expose the metal film. Method of manufacturing a vibrating piece.
As a result, the thin photoresist film corresponding to the groove can be removed easily and in a short time, and the metal film corresponding to the groove can be exposed.

Application Example 6 The method for manufacturing a resonator element according to any one of Application Examples 1 to 5, wherein the substrate is a piezoelectric single crystal.
As a result, a resonator element having a stable resonance frequency can be obtained without being affected by ambient temperature changes.

Application Example 7 The method for manufacturing a resonator element according to any one of Application Examples 1 to 6, wherein the groove is formed on one main surface and the other main surface of the substrate.
Thereby, even if it is the structure of the vibration piece which provided the groove part in one main surface and the other main surface, the relative position of an outline and a groove part can be formed with sufficient precision.

In the manufacturing process of the resonator element according to the invention, it is an explanatory view from the substrate to the step of etching the outer shape of the resonator element. In the manufacturing process of the resonator element according to the invention, it is an explanatory diagram of the removal process of the photoresist film corresponding to the groove. FIG. 11 is an explanatory diagram of a first modification of the photoresist film removal step corresponding to the groove in the manufacturing process of the resonator element according to the invention. FIG. 10 is an explanatory diagram of a second modification of the photoresist film removal process corresponding to the groove in the manufacturing process of the resonator element according to the invention. FIG. 11 is an explanatory diagram of a third modification of the photoresist film removal process corresponding to the groove in the manufacturing process of the resonator element according to the invention. In the manufacturing process of the vibration piece of this invention, it is explanatory drawing from the process of removing the metal film of a groove part to formation of a vibration piece. FIG. 6 is a perspective view of a resonator element according to an embodiment of the invention.

  An embodiment of a method for manufacturing a resonator element according to the invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is an explanatory diagram from the substrate to the step of etching the outer shape of the resonator element in the resonator element manufacturing process of the present invention.

  A substrate 10 shown in FIG. 1A is a plate-like (wafer-like) member polished to a predetermined thickness, and it is desirable to use a piezoelectric single crystal as a material. Examples of the material of the substrate 10 include a piezoelectric single crystal made of crystal, lithium niobate single crystal, lithium tantalate single crystal, lithium niobate-lithium tantalate solid solution, lithium borate single crystal, langasite single crystal, and the like. Can be used. By using such a piezoelectric single crystal for the substrate 10, it is possible to obtain a resonator element having a stable resonance frequency without being affected by ambient temperature changes.

Next, a metal film 20 is formed on one main surface 12 and the other main surface 14 of the substrate 10. The metal film 20 can be formed using vapor deposition or sputtering. The metal film 20 is preferably made of a material that is not corroded by, for example, hydrofluoric acid, which is an etching solution for the substrate 10 that forms the outer shape of the resonator element in a later step. As an example, the metal film 20 of the present embodiment has two layers (a lower layer is a Cr film 22) in which a Cr (chrome) film 22 is formed on the upper layer of the substrate 10 and an Au (gold) film 24 is stacked on the upper layer of the Cr film 22. A laminated structure in which the upper layer is an Au film 24) is employed. The Cr film 22 has excellent adhesion to the substrate 10 such as quartz. On the other hand, the Au film 24 is more excellent in corrosion resistance of the etching solution of the substrate 10 than the Cr film 22. In addition, a laminated structure in which Ti (titanium), W (tungsten), or the like is combined may be employed.
A photoresist is applied to the entire surface of the metal film 20 and dried to form a photoresist film 60 having a predetermined thickness.

  Next, as shown in FIG. 1A, a photomask 64 on which an etching pattern corresponding to the outer shape of the resonator element is drawn is disposed on the photoresist film 60 on both main surfaces of the substrate 10. The photomask 64 includes an opening that exposes an area corresponding to the outer portion of the vibrating piece with ultraviolet rays, and an exposure control unit 65 such as a mesh designed so that ultraviolet rays are partially transmitted only in the area corresponding to the groove portion of the vibrating piece. Is formed. The region corresponding to the inner shape of the other resonator element is configured to shield ultraviolet rays. Then, the etching pattern is transferred by exposing to ultraviolet rays.

  Then, as shown in FIG. 1B, the photosensitive portion of the photoresist film 60 is removed by developing with a developing solution to expose the metal film 20 corresponding to the outer shape of the vibrating piece. Here, the photoresist film 60a corresponding to the groove is also removed in a concave shape following the shape of the groove. As described above, the photoresist film 60 of the present invention can be formed so that the thickness of the photoresist film 60a corresponding to the groove portion is thinner than the thickness of the photoresist film 60 corresponding to the inner shape of the resonator element.

  In the method for manufacturing a resonator element according to the present invention, since the outer shape of the resonator element and the formation position of the groove portion are simultaneously patterned, the vibration piece is more vibrated than the conventional method of patterning the outer shape of the resonator element and the groove portion formation position in separate steps. The precision of the relative position of the external shape of a piece and a groove part can be raised.

  Then, the metal film 20 on the substrate 10 on which the photoresist film 60 is not formed is removed by etching with a predetermined etching solution. The metal film 20 is removed after the upper Au film 24 is removed and then the lower Cr film 22 is removed stepwise. Thereby, the substrate 10 is exposed in the portion where the metal film 20 is removed.

  Next, as shown in FIG. 1C, the outer shape of the resonator element is etched. That is, only the inner shape (inner side of the outer shape) of the resonator element is left, and the outer shape is removed by etching. As the etching process, for example, dry etching, wet etching, or the like can be used. Here, the region corresponding to the groove of the substrate 10 of the present invention is covered with the metal film 20. For this reason, even if the thickness of the photoresist film 60a corresponding to the groove portion is thin, there is no possibility that the substrate 10 in the region corresponding to the groove portion is eroded by the etching solution during etching of the outer shape, and the groove portion is etched simultaneously with the etching of the outer shape. There is nothing. Therefore, the outer shape and the position of the groove when the photoresist film 60 is patterned can be maintained, and the relative position accuracy can be improved.

  FIG. 2 is an explanatory diagram of a step of removing a photoresist film corresponding to the groove in the manufacturing process of the resonator element according to the invention. In the step of removing the photoresist film 60a corresponding to the groove portion of this embodiment, exposure is used as a method for removing the photoresist film. As shown in FIG. 2A, the entire area of the substrate 10 that has been subjected to outer shape etching is exposed to ultraviolet rays. The exposure is performed until the photoresist film 60a corresponding to the groove is exposed, and is stopped before the photoresist film corresponding to the inner shape of the resonator element is completely exposed. The exposure of the photoresist film proceeds uniformly. For this reason, even if the photoresist film 60a corresponding to the thin groove portion is completely exposed, the photoresist film 60 corresponding to the inner shape of the vibrating piece has a film thickness of the photoresist film 60a corresponding to the groove portion. It progresses only to the film thickness corresponding to.

  Next, as shown in FIG. 2B, the photosensitive portion of the photoresist film 60 is developed and removed with a developer. As a result, the metal film corresponding to the groove portion of the resonator element is exposed.

  According to such a removal method using exposure, the thin photoresist film corresponding to the groove can be removed easily and in a short time, and the metal film in the region corresponding to the groove can be exposed. Further, by adjusting the exposure processing time, a photoresist film corresponding to the inner shape of the resonator element can be left. For this reason, it is not necessary to pattern the region corresponding to the groove portion again, and the manufacturing process can be simplified, and the outer shape of the resonator element and the relative position of the groove portion can be ensured.

FIG. 3 is an explanatory view of Modification 1 of the photoresist film removal process corresponding to the groove in the manufacturing process of the resonator element according to the invention. In the removal process of the photoresist film 60a corresponding to the groove portion of the first modification, dry etching is used as a method for removing the photoresist film. As shown in FIG. 3A, dry etching is performed on the entire area of the substrate 10 that has been externally etched. In the dry etching process, first, the substrate 10 is accommodated in a vacuum chamber. A freon gas and oxygen gas supply means and an exhaust pipe are connected to the vacuum chamber. The inside of the vacuum chamber is evacuated to a predetermined degree of vacuum, freon gas and oxygen gas are sent, and plasma is generated when a DC voltage is applied while the mixed gas is filled up to a predetermined atmospheric pressure. To do. A mixed gas containing ionized particles hits the photoresist film 60 of the substrate 10. Due to this impact, the photoresist film 60 is physically scraped and scattered, and etching of the photoresist film 60 proceeds. The dry etching is performed until the photoresist film 60a corresponding to the groove is scraped off, and is stopped before the photoresist film 60 corresponding to the inner shape of the vibrating piece is completely scraped off. Since the progress rate of dry etching is slower than the progress rate of wet etching, the etching process can be easily stopped after completely removing the photoresist film 60a corresponding to the groove.
As a result, as shown in FIG. 3B, the photoresist film corresponding to the groove of the vibrating piece is removed, and the metal film 20 is exposed.

  According to such a removal method using dry etching, the thin photoresist film corresponding to the groove can be accurately removed, and the metal film in the region corresponding to the groove can be exposed. In addition, since a metal film is formed under the photoresist film, there is no possibility that the substrate is altered by dry etching. Further, by adjusting the etching processing time, a photoresist film corresponding to the inner shape of the resonator element can be left. For this reason, it is not necessary to pattern the region corresponding to the groove portion again, and the manufacturing process can be simplified, and the outer shape of the resonator element and the relative position of the groove portion can be ensured.

  FIG. 4 is an explanatory diagram of a second modification of the process of removing the photoresist film corresponding to the groove in the manufacturing process of the resonator element according to the invention. In the removal process of the photoresist film 60a corresponding to the groove portion of the second modification, partial exposure is used as a method for removing the photoresist film. As shown in FIG. 4A, an ultraviolet ray is applied to a region corresponding to the groove portion of the substrate 10 subjected to outer shape etching using a photomask 66 having an opening 68 larger than the outer shape of the photoresist film 60a corresponding to the groove portion. To expose. Since the photomask 66 has an opening 68 larger than the photoresist film 60a corresponding to the groove portion, it is sufficient that the photoresist film 60a corresponding to the groove portion fits in the opening 68, and the photo corresponding to the opening 68 and the groove portion is formed. The alignment of the resist film 60a can be easily performed. In addition, the opening 68 of the photomask 66 is larger than the photoresist film 60a corresponding to the groove portion, and the thick photoresist film 60 corresponding to the inner shape of the resonator element is also partially exposed. However, the exposure is performed until the photoresist film 60a corresponding to the groove is completely exposed and then stopped. For this reason, the thick photoresist film is not completely exposed.

  Next, as shown in FIG. 4B, the exposed portion of the photoresist film 60 is removed by development with a developer. As a result, the metal film 20 corresponding to the groove portion of the resonator element is exposed.

  According to such a partial exposure removal method, the thin photoresist film corresponding to the groove can be reliably exposed, and the groove of the vibrating piece can be formed with high accuracy. In addition, since the photoresist film corresponding to the inner shape of the resonator element can be left, it is not necessary to pattern the region corresponding to the groove portion again, simplifying the manufacturing process, and securing the outer shape of the resonator element and the relative position of the groove portion. be able to.

  FIG. 5 is an explanatory view of a third modification of the photoresist film removing step corresponding to the groove in the manufacturing process of the resonator element according to the invention. In the removal process of the photoresist film 60a corresponding to the groove portion of the third modification, an additional development process is used for the removal method of the photoresist film. By exposure of the etching pattern of the resonator element shown in FIG. 1A, the side surface of the photoresist film 60 indicated by arrow a in FIG. 5A and the region corresponding to the groove portion of the photoresist film 60 indicated by arrow b are exposed to light. Range. Therefore, after the outer shape etching step of the resonator element shown in FIG.

  As a result, as shown in FIG. 5B, the photoresist film 60a corresponding to the groove of the resonator element and a part of the side surface of the photoresist film 60 are removed, and the metal film 20 is exposed.

  Further, since the photoresist film 60 is exposed to the etching solution due to the outer shape etching of the resonator element, the surface layer portion may be altered. Therefore, as a pretreatment of the development process, the substrate 10 is placed in a chamber, oxygen plasma is generated by discharge in a vacuum or a reduced pressure environment, and is caused to act on the surface of the photoresist film 60, so that the altered layer on the photoresist film surface is formed. It can be removed by ashing. As a result, the photoresist film 60 whose reaction with the developing solution has deteriorated due to the alteration can be removed, and the photoresist film 60a corresponding to the groove portion can be reliably removed.

  According to such a removal method by development, the thin photoresist film corresponding to the groove portion can be easily and quickly removed, and the metal film in the region corresponding to the groove portion can be exposed.

FIG. 6 is an explanatory diagram from the step of removing the metal film in the groove portion to the formation of the resonator element in the resonator element manufacturing process of the present invention.
As shown in FIG. 6A, the metal film 20 exposed between the photoresist films 60 is removed by etching with a predetermined etching solution. The metal film 20 is removed after the upper Au film 24 is removed and then the lower Cr film 22 is removed stepwise.

  As shown in FIG. 6B, the substrate 10 is exposed at the portion where the metal film is removed. The remaining photoresist film 60 is exposed to ultraviolet rays. And it develops with a developing solution and the photoresist film of the board | substrate 10 is removed (FIG.6 (c)).

Next, as shown in FIG. 6D, the substrate 10 corresponding to the groove is half-etched to a predetermined depth with an etching solution to form the groove 72.
Finally, as shown in FIG. 6E, the metal film 20 is completely removed by etching with an etching solution. In this way, the vibrating piece 74 having the groove 72 on one main surface and the other main surface of the vibrating arm 70 is obtained.

  As mentioned above, although the manufacturing method of the vibration piece of this embodiment was demonstrated with the structure of the vibration piece which provided the groove part in one main surface and the other main surface of a board | substrate, the structure of a groove part is not restricted to this, One side of a board | substrate The present invention can also be applied to a method for manufacturing a resonator element having a groove on only the main surface or the other main surface.

  According to the method for manufacturing a resonator element of the present invention, since the outer contour of the resonator element and the patterning of the groove can be performed at the same time, the accuracy of the relative position of the outer contour of the resonator element and the groove can be improved. In addition, since the region corresponding to the groove portion of the metal film is protected by the metal film during the etching for forming the outer shape of the resonator element, the groove portion is not etched simultaneously with the formation of the outer shape. Therefore, the groove portion of the vibrating piece can be formed with high accuracy.

  FIG. 7 is a perspective view of a resonator element according to an embodiment of the invention. As shown in the figure, the resonator element 80 extends in a plane composed of an X-axis (second axis) and a Y-axis (first axis) perpendicular to the X-axis in a planar shape, and is opposed to each other. And a second main surface 84. An axis perpendicular to the first main surface 82 and the second main surface 84 is taken as a Z axis. In the vibrating piece 80, the first vibrating arm 88 and the second vibrating arm 89 extend from the base 86 in the + Y-axis direction, and the third vibrating arm 90 and the fourth vibrating arm 91 extend in the −Y-axis direction. . The base 86, the first vibrating arm 88, and the second vibrating arm 89 constitute a tuning fork type vibrating piece, and the base 86, the third vibrating arm 90, and the fourth vibrating arm 91 constitute a tuning fork type vibrating piece. A vibrating piece 80 having such a configuration in which two tuning fork type vibrating pieces are coupled to the base 86 and the extending directions of the vibrating arms of the two tuning fork type vibrating pieces are separated from each other is referred to as an H type vibrating piece.

  The first vibrating arm 88 and the second vibrating arm 89 are parallel to each other and have the same length and the same sectional shape, and the third vibrating arm 90 and the fourth vibrating arm 91 are parallel to each other and have the same length and the same sectional shape. It consists of In the resonator element 80 according to the present embodiment, the first vibrating arm 88 and the second vibrating arm 89 constitute a driving arm (excitation arm), and the third vibrating arm 90 and the fourth vibrating arm 91 constitute a detection arm. Yes. Each of the first to fourth vibrating arms 88, 89, 90, 91 is formed with an elongated groove portion 92 on the first main surface 82 and the second main surface 84, and is used for manufacturing such an H-shaped vibrating piece 80. The manufacturing method of the invention can be applied.

  In the vibrating piece 80 having such a configuration, when an excitation signal is input to an electrode (not shown), the first vibrating arm 88 and the second vibrating arm 89 bend and vibrate in the ± X directions. At this time, when the resonator element 80 is rotated around the Y axis (detection axis), a Coriolis force is generated in a direction perpendicular to the vibration direction (in-plane vibration) of the first vibrating arm 88 and the second vibrating arm 89, The third vibrating arm 90 (detection arm) and the fourth vibrating arm 91 (detection arm) vibrate out of plane in the ± Z-axis direction. By measuring the amount of charge generated by this out-of-plane vibration, the angular velocity acting on the vibrating piece 80 can be detected.

  Also in the manufacturing method of such an H-shaped vibrating piece 80, since the outer contour of the vibrating piece and the patterning of the groove can be performed simultaneously, the accuracy of the relative position of the outer contour of the vibrating piece and the groove can be improved. In addition, since the region corresponding to the groove is covered with the metal film at the time of etching for forming the outer shape of the resonator element, the groove is not etched simultaneously with the formation of the outer shape. Therefore, the groove portion of the vibrating piece can be formed with high accuracy.

10 ......... Substrate, 12 ......... One main surface, 14 ......... Other main surface, 20 ......... Metal film, 22 ......... Cr film, 24 ...... Au film, 60 ...... Photo Resist film, 64... Photomask, 65... Exposure control section, 66... Photomask, 68... Opening, 70... Vibrating arm, 72. , 80... Vibrating piece, 82... 1st main surface, 84... 2nd main surface, 86... Base, 88. 90 ......... third vibrating arm, 91 ......... fourth vibrating arm, 92 ......... groove.

Claims (7)

In a method of manufacturing a resonator element, comprising: a base portion; and a vibrating arm formed to protrude from the base portion, wherein a groove portion is formed in the vibrating arm.
The photoresist film corresponding to the inner shape of the vibrating piece in the outer shape pattern of the vibrating piece and the film thickness of the photoresist film corresponding to the groove with respect to the photoresist film covering the metal film formed on the substrate Forming a thinner pattern at the same time;
Etching the substrate to form an outer shape of the resonator element;
Removing the photoresist film corresponding to the groove to expose the metal film;
Removing the metal film corresponding to the groove;
Etching the substrate to form the groove;
A method of manufacturing a resonator element comprising:   2. The method for manufacturing a resonator element according to claim 1, wherein the photoresist film corresponding to the groove is removed by exposure to expose the metal film.   The method for manufacturing a resonator element according to claim 1, wherein the photoresist film corresponding to the groove is removed by dry etching to expose the metal film.   2. The resonator element according to claim 1, wherein the photoresist film corresponding to the groove is removed by exposure using a mask having an opening larger than the photoresist film to expose the metal film. Manufacturing method.   2. The resonator element according to claim 1, wherein after the step of forming the outer shape of the resonator element, the photoresist film corresponding to the groove is further removed by development to expose the metal film. Method.   The method of manufacturing a resonator element according to claim 1, wherein the substrate is a piezoelectric single crystal.   The method for manufacturing a resonator element according to claim 1, wherein the groove is formed on one main surface and the other main surface of the substrate.