JP2013141055A - Vibration piece manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration piece manufacturing method capable of accurately forming a groove part of a vibration piece.SOLUTION: In a vibration piece manufacturing method according to the present invention, a vibration piece comprising a base part, and a vibration arm formed to project from the base part is manufactured, a groove part is formed on the vibration arm. The method includes: a step of simultaneously patterning an outer shape of the vibration piece and the groove part to a photoresist film 60 covering a metal film 20 for deposition formed on a substrate 10; a step of removing the metal film 20 for depositing patterns of the outer shape of the vibration piece and the groove part, and the patterned photoresist film 60, and forming an opening 30 corresponding to the groove part; a step of forming a coating metal film 40 on the opening 30 to cover the opening 30; a step of forming the outer shape of the vibration piece by etching the substrate 10; a step of removing the coating metal film 40; and a step of forming a groove part 72 by etching the substrate 10.

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 resonator element disclosed in Patent Document 1, first, a metal mask is formed on the front surface and the back surface of a crystal wafer, a photoresist film is formed on the metal mask, and the photoresist film is patterned. Then, the metal mask is patterned in accordance with the pattern of the photoresist film. This pattern is designed according to the outer contour of the resonator element. Next, a photoresist film is formed on the metal mask pattern, and the photoresist film is patterned. The pattern of the photoresist film is designed according to the groove pattern of the resonator element. Next, the crystal wafer is etched in accordance with the pattern of the metal mask, and the outer contour of the resonator element is formed. Next, the metal mask is patterned in accordance with the groove pattern, and the groove is formed in the resonator element by etching.

  In the method of manufacturing a resonator element disclosed in Patent Document 2, first, a metal mask having a first opening is formed on a substrate. Then, a photoresist film is coated on the metal mask including the first opening. A second opening is formed in the photoresist film, and the outer contour of the resonator element is formed by etching the substrate. Then, after removing the photoresist film, the groove is formed by etching the substrate.

JP 2002-76806 A JP 2004-289217 A

  However, according to the manufacturing method of Patent Document 1, since the step of forming the outer shape of the resonator element and the step of forming the groove are performed in separate steps, a two-stage photoresist film is formed on the outer contour and the groove. The membrane must be done. When a photoresist film is formed on a metal mask in a later process, patterning is performed in accordance with the groove pattern of the metal mask, but it is difficult to accurately align the groove with the already formed outline. There was a problem. If the position of the groove 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.

  In addition, according to the method for manufacturing a resonator element of Patent Document 2, since the adhesion between the quartz crystal substrate and the photoresist film is generally poor, the photoresist film covering the metal mask including the first opening portion is etched when the outline is etched. It becomes easy to peel off. As a result, the etching solution partially flows into the first opening from which the photoresist film has been peeled, that is, the groove, and the groove is etched simultaneously with the etching of the outer shape. When the groove is formed on the front and back of the substrate, if the depth of the groove on the front and back is different or the groove on the front and back is not formed symmetrically, the balance of the vibrating arm will be poor and noise will be added to the frequency The resonance frequency of the resonator element deviates from the design value.

  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 metal film for film formation formed on a substrate Simultaneously patterning the outer shape of the vibrating piece and the groove portion on the photoresist film covering the substrate, removing the outer shape of the vibrating piece, the metal film for forming the groove portion, and the patterned photoresist film. A step of forming an opening corresponding to the groove, a step of forming a metal film for coating on the opening so as to cover the opening, a step of etching the substrate to form an outer shape of the vibrating piece, A method for manufacturing a resonator element, comprising: removing the metal film for coating; and etching the substrate to form the groove.

  With the above configuration, since the outer contour of the vibrating piece and the patterning of the groove portion can be performed simultaneously, the accuracy of the relative position between the outer contour of the vibrating piece and the groove portion can be increased. In addition, the opening corresponding to the groove portion of the metal film for film formation can be protected by the metal film for coating during the etching for forming the outer shape of the resonator element, and 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.

Application Example 2 The method for manufacturing a resonator element according to Application Example 1, wherein the metal film for film formation has a laminated structure in which a lower layer is a Cr film and an upper layer is an Au film.
With the above configuration, the etching processing time can be arbitrarily adjusted in the coating metal film removal step. Further, when the groove is etched, the etching processing time can be arbitrarily adjusted according to the groove depth.

Application Example 3 The method for manufacturing a resonator element according to Application Example 2, wherein the step of removing the metal film for coating also removes the Au film of the metal film for film formation at the same time.
With the above configuration, the removal process of the metal film for coating can be performed easily and easily. In addition, when the groove is etched, a Cr metal film can be used as a mask if the etching time is short. Therefore, it is particularly effective when the groove depth of the groove is shallow.

Application Example 4 The method for manufacturing a resonator element according to any one of Application Examples 1 to 3, wherein the substrate is a piezoelectric single crystal.
With the above configuration, a resonator element having a stable resonance frequency can be obtained without being affected by ambient temperature changes.

Application Example 5 The method for manufacturing a resonator element according to any one of Application Examples 1 to 4, wherein the groove is formed on one main surface and the other main surface of the substrate.
With the above-described configuration, the relative position between the outer contour and the groove can be formed with high accuracy even in the structure of the resonator element including the groove on one main surface and the other main surface.

In the manufacturing process of the vibration piece of this invention, it is explanatory drawing to the process of forming the metal film for a film on a board | substrate. In the manufacturing process of the resonator element according to the invention, it is an explanatory view from the step of removing the metal film for coating on the substrate. In the manufacturing process of the resonator element according to the invention, it is an explanatory view of a modified example from the process of removing the metal film for coating on the substrate. FIG. 6 is a perspective view of a resonator element according to an embodiment of the invention.

  A method for manufacturing a resonator element according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is an explanatory diagram up to the step of forming a metal film for coating on a substrate in the manufacturing process of the resonator element according to the invention.

  The substrate 10 shown in FIG. 1A is a plate shape (wafer shape) 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 film-forming metal film 20 to be a first metal film is formed on one main surface 12 and the other main surface 14 of the substrate 10. As a method for forming the metal film 20 for film formation, vapor deposition, sputtering, or the like can be used. The metal film 20 for film formation is desirably a material that is not eroded by etching that forms the outer shape of the resonator element in a later step. As an example, the metal film 20 for film formation of the present embodiment is a two-layer structure in which a Cr (chrome) film 22 is formed on the lower layer on the substrate 10 and an Au (gold) film 24 is stacked on the upper layer of the lower Cr film 22. A laminated structure is used. The Cr film 22 has excellent adhesion to the substrate 10 such as quartz. On the other hand, the Au film 24 has better etching corrosion resistance 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 film 60 is formed on the entire surface of the metal film 20 for film formation.

  Next, as shown in FIG. 1B, the photoresist film 60 is patterned by using a predetermined exposure unit so that the photoresist film 60 remains except for the outer shape and the groove of the vibrating piece, and the patterned photoresist film. 60 is formed. 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 for film formation on the substrate 10 on which the photoresist film 60 is not formed is removed by etching. As shown in FIG. 1 (c), the metal film 20 for film formation is removed step by step after the upper Au film 24 is removed, as shown in FIG. 1 (d). Removed. As a result, the substrate 10 is exposed at the portion where the metal film 20 for film formation has been removed.

  Next, as shown in FIG. 1E, all of the photoresist film 60 remaining on the metal film 20 for film formation is removed. Thereby, an opening 30 corresponding to the groove appears between the metal films 20 for film formation.

  Then, as shown in FIG. 1 (f), for the coating that becomes the second metal film so as to cover at least the opening 30 so as to cover the opening 30 between the film forming metal film 20 and the film forming metal film 20. A metal film 40 is formed. The coating metal film 40 can be formed by vapor deposition, sputtering, or the like, similar to the film forming metal film 20. The metal film for coating 40 is preferably made of a material that is not eroded by etching that forms the outer shape of the resonator element in a later step. In this embodiment, Au is used as the material. The coating metal film 40 formed so as to cover the openings 30 between the film forming metal films 20 has a convex shape from the opening 30 side toward the substrate 10 and is formed so as to fill the openings 30. Since the metal film for coating 40 having such a configuration has good adhesion to the substrate 10, it is possible to prevent the etching solution from flowing into the groove during the outer shape etching.

  FIG. 2 is an explanatory diagram from the step of removing the coating metal film 40 on the substrate 10 in the manufacturing process of the resonator element according to the invention. As shown in FIG. 2A, outer shape etching is performed. That is, only the inside 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. At this time, in the case where the photoresist film is formed in the opening corresponding to the groove portion of the vibrating piece between the metal films as in the prior art, the adhesion between the photoresist film and the substrate is poor. The photoresist film covering the corresponding opening is easily peeled off, and there is a possibility that the etching solution flows into the opening from which the photoresist film is peeled off and the groove portion is also etched. On the other hand, the opening 30 corresponding to the groove portion of the resonator element according to the invention is covered with a coating metal film 40 that is corrosion resistant to the etching solution. The coating metal film 40 has good adhesion to the deposition metal film 20. For this reason, the metal film for film 40 is not eroded by the etching solution during the etching of the outer shape, and the opening is not etched simultaneously with the etching of the outer shape. 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.

  Next, as shown in FIG. 2B, the coating metal film 40 is removed by etching. The removal of the coating metal film 40 takes the etching processing time so that only the coating metal film 40 formed on the deposition metal film 20 is removed in consideration of the film thickness, the etching progress time, and the like. Is adjusted. In this way, the metal film 20 for film formation is formed on the substrate 10 with the lower layer being the Cr film 22 and the upper layer being the Au film 24.

  Then, as shown in FIG. 2C, the opening corresponding to the groove is etched to a predetermined depth to form the groove 72. At this time, since the Au film 24 having corrosion resistance to the etching solution is formed on the substrate 10 in the etching of the groove portion 72, the metal film is not eroded even if the processing time is extended. For this reason, it is particularly effective for a vibrating piece having a deep groove 72.

  Finally, as shown in FIG. 2D, the metal film 20 for film formation is removed by etching. 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.

FIG. 3 is an explanatory view of a modified example from the step of removing the metal film for coating on the substrate in the manufacturing process of the resonator element according to the invention.
The outer shape etching shown in FIG. 3A is performed by the same process as the outer shape etching shown in FIG. That is, only the inside of the outer shape of the resonator element is left, and the outer shape is removed by etching.

  Then, as shown in FIG. 3B, the coating metal film 40 is removed by etching. Etching of the coating metal film 40 is performed so that the Cr film 22 of the metal film 20 for film formation remains. The removal of the metal film for film 40 constitutes the metal film for film 40 formed on the metal film for film formation 20 and the metal film for film formation 20 in consideration of the film thickness, the etching progress time, and the like. The etching processing time is adjusted so that the Au film 24 is removed. In this way, the metal film 20a for film formation composed only of the Cr film 22 is formed on the substrate 10. The metal film 20a for film formation composed only of the Cr film 22 has no fear that the etching solution may pass through the Cr film 22 and erode the substrate 10 if the processing time is short when the groove is etched. In addition, the etching process is easier than the etching process in which the Au film 24 of the metal film 20 for film formation is removed while removing the metal film 40 for film formation shown in FIG. be able to.

  Then, as shown in FIG. 3C, an opening corresponding to the groove is etched to a predetermined depth to form a groove 72. At this time, the etching of the groove 72 shortens the processing time because the Cr film 22 having a lower corrosion resistance to the etching solution than the Au film is formed on the substrate 10.

  Finally, as shown in FIG. 3D, the metal film 20 for film formation is removed by etching. 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.

  According to the process of the modification which removes such a metal film for a film, the removal process of the metal film for a film can be performed simply and easily. Further, when the groove is etched, a Cr metal film can be used as a mask for a short time. Therefore, this is particularly effective for a vibrating piece having a shallow groove depth.

  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, the opening corresponding to the groove portion of the metal film for film formation can be protected by the metal film for coating during the etching for forming the outer shape of the resonator element, and 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. 4 is a perspective view of the resonator element according to the 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, the opening corresponding to the groove portion of the metal film for film formation can be protected by the metal film for coating during the etching for forming the outer shape of the resonator element, and 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.

10 ......... Substrate, 12 ......... One main surface, 14 ......... Other main surface, 20 ......... Metal film for film formation, 22 ......... Cr film, 24 ...... Au film, 30 ... ...... Opening, 40 ......... Metal film for coating, 60 ......... Photoresist film, 70 ......... Vibrating arm, 72 ......... Groove, 74 ......... Vibrating piece, 80 ......... Vibrating piece, 82 ... ...... First main surface, 84 ......... Second main surface, 86 ......... Base, 88 ......... First vibrating arm, 89 ......... Second vibrating arm, 90 ......... Third vibrating arm, 91 ......... Fourth vibrating arm, 92 ......... Groove.

Claims (5)

In a method of manufacturing a resonator element comprising a base and a vibrating arm formed to protrude from the base, wherein a groove is formed in the vibrating arm.
Simultaneously patterning the outer shape of the resonator element and the groove with respect to a photoresist film covering the metal film for film formation formed on the substrate;
Removing the outer shape of the vibrating piece, the metal film for film formation in the groove and the patterned photoresist film, and forming an opening corresponding to the groove;
Forming a coating metal film on the opening so as to cover the opening;
Etching the substrate to form an outer shape of the resonator element;
Removing the metal film for coating;
Etching the substrate to form the groove;
A method of manufacturing a resonator element comprising:   The method for manufacturing a resonator element according to claim 1, wherein the metal film for film formation has a laminated structure in which a lower layer is a Cr film and an upper layer is an Au film.   The method of manufacturing a resonator element according to claim 2, wherein the step of removing the metal film for coating also removes the Au film of the metal film for film formation.   The method for manufacturing a resonator element according to claim 1, wherein the substrate is a piezoelectric single crystal.   5. 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. 6.