JP2013214638A - Manufacturing method of vibration piece - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a vibration piece which prevents a formation region of a groove on a substrate from being concurrently etched when an outer shape of a vibration piece is formed on the substrate by etching, in a manufacturing method of the vibration piece having the groove.SOLUTION: In a manufacturing method of a vibration piece 1, a Cr film 20, an Au film 30, a Ni film 40, and a first resist film 50 are sequentially deposited on a substrate 10 and the first resist film 50 is patterned into an outer shape and a shape of a groove of the vibration piece 1. A portion of the Ni film 40 which does not overlap with the patterned first resist film 50 is etched. An second resist film 60 is deposited on the Au film 30 exposed by etching. The second resist film 60 is patterned into the outer shape of the vibration piece 1. Then, the Cr film 20, the Au film 30, and the substrate 10 which does not overlap with the patterned second resist film 60 are etched to form the outer shape of the vibration piece 1 on the substrate 10. The second resist film 60 is peeled, and the Cr film 20 and the Au film 30, which correspond to the groove, are etched. The substrate 10, which corresponds to the groove, is etched to form the groove on the substrate 10.

Description

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

  There is a tuning fork type piezoelectric vibrating piece as one of the vibrating pieces. The tuning fork-type piezoelectric vibrating piece has a base portion and two vibrating arms formed so as to protrude from the base portion. The vibrating arm is often formed with a groove for the purpose of obtaining a small size and high reliability. By forming the groove in the vibrating arm, the vibration loss of the vibrating arm is reduced, and the CI (crystal impedance) value can be kept low, so that excellent vibration characteristics can be obtained even if the size is reduced. An example of a conventional method for manufacturing such a resonator element is disclosed in Patent Documents 1 and 2.

  In the manufacturing method of the resonator element disclosed in Patent Document 1, first, a metal mask in which a quartz substrate is formed with a first opening corresponding to a groove pattern and a second opening corresponding to an outer contour of the resonator element. And further coated with a photoresist film. In this state, the photoresist film is in close contact with the quartz substrate exposed to the first opening and the second opening and the metal mask. Next, the photoresist film is patterned so that the second opening is exposed, and the substrate of the second opening exposed from the patterned photoresist film is etched, whereby the outer shape of the resonator element is formed on the substrate. Form. Next, the photoresist film is removed, and the groove portion is formed by etching the substrate of the first opening exposed from the metal mask.

  In the method of manufacturing a resonator element disclosed in Patent Document 2, first, a metal film is formed on a quartz substrate, a photoresist film is formed on the metal film, and an outer contour of the resonator element is patterned on the photoresist film. Then, the metal film is etched according to the photoresist film to pattern the outer contour of the resonator element, and then the photoresist film is peeled off. Next, a new photoresist film is formed on the quartz substrate, and the photoresist film is patterned into an outer shape and a groove shape. Next, the substrate is etched according to the outer pattern of the photoresist film and the metal film, and the outer shape of the resonator element is formed on the substrate. Next, a groove pattern is formed in the metal film according to the groove pattern of the photoresist film, and the substrate is etched according to the groove pattern of the photoresist film and the metal film, thereby forming the groove.

JP 2004-289217 A JP 2002-76806 A

  However, in the method of manufacturing a resonator element disclosed in Patent Document 1, since the adhesion between the quartz substrate and the photoresist film is poor, the photo that covers the quartz substrate exposed in the first opening is etched when the outer shape is etched. In some cases, the resist film is peeled off and the etching solution flows into the quartz substrate. Since the quartz substrate exposed in the first opening is a groove forming region, if the groove forming region is etched during the outer shape etching, the groove portions on the front and back sides are formed when the groove is formed on the front and back of the substrate. There are problems that the depths of the grooves are different and the shapes of the groove portions on the front and back sides are not symmetrical. As a result, there is a problem that the balance of the vibrating arm is deteriorated, noise is added to the frequency, and the resonance frequency of the resonator element deviates from the design value.

  In the manufacturing method disclosed in Patent Document 2, the step of forming the outer shape of the resonator element and the step of forming the groove are separate steps, and the outer pattern is formed on the metal film with the photoresist film for outer shape formation. After that, it is necessary to peel off the photoresist film and newly form a photoresist film for forming a groove. When a groove pattern is formed on the photoresist film formed in the subsequent process and the groove pattern is formed on the metal film in accordance with the groove pattern, the groove pattern is accurately added to the external pattern formed on the metal film in the previous process. There was a problem that it was difficult to align. If the position of the groove is not formed as designed, there is a problem that the balance of the vibrating arm is poor and the vibration is not stable, the frequency stability is deteriorated, or the resonance frequency of the resonator element deviates from the design value. there were.

Therefore, in order to solve the problems of the prior art, the present invention relates to a method for manufacturing a resonator element having a groove portion. When the outer shape of the resonator element is formed on the substrate by etching, the formation region of the groove portion on the substrate is simultaneously etched. It is an object of the present invention to provide a method for manufacturing a resonator element that prevents it from being damaged.
It is another object of the present invention 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 A method for manufacturing a resonator element having a groove, in which a first metal film, a second metal film, a third metal film, and a first resist film are sequentially formed on a substrate. A step of patterning the first resist film into the outer shape of the vibrating piece and the shape of the groove, and a portion of the third metal film that does not overlap the patterned first resist film. An etching step, a step of forming a second resist film on the second metal film exposed by the etching, a step of patterning the second resist film on the outer shape of the vibrating piece, and the patterning Etching the first metal film, the second metal film, and the substrate that do not overlap the second resist film formed to form an outer shape of the resonator element on the substrate; 2 resist film The step of peeling, the step of etching the first metal film and the second metal film corresponding to the groove, and the substrate corresponding to the groove are formed to form the groove on the substrate. And a process for manufacturing the resonator element.

  According to the above invention, since the first metal film is formed on the substrate without directly forming the resist film having poor adhesion to the substrate on the substrate, the outer shape of the resonator element is etched on the substrate. It is possible to prevent the first metal film from being peeled from the substrate and the groove formation region on the substrate is etched.

  In addition, since the outer shape is etched in a state where the region for forming the groove on the substrate is covered with the three layers of the first metal film, the second metal film, and the second resist film, the outer shape is etched. Further, the region on the substrate where the groove is formed is not etched. Therefore, the groove portion of the vibrating piece can be formed with high accuracy.

  Further, the outer shape of the vibrating piece is formed by patterning the outer shape of the vibrating piece and the shape of the groove on the third metal film, and forming the outer shape of the vibrating piece and forming the groove based on the pattern of the third metal film. The accuracy of the relative position between the groove portion and the groove portion can be increased.

[Application Example 2] In the application example 1, the first metal film is a chromium film, the second metal film is a gold film, and the third metal film is a nickel film. Method of manufacturing a vibrating piece.

  According to the said invention, adhesiveness with a board | substrate can be improved by forming a chromium film | membrane on a board | substrate. Further, by using the second metal film as a gold film, the corrosion resistance against the etching solution can be improved and the chromium film can be protected. In addition, when the third metal film is a nickel film, the film can be easily formed, and the etching rate is slower than that of chromium. Therefore, the third metal film can be used instead of the resist film.

Application Example 3 The method for manufacturing a resonator element according to Application Example 1 or 2, wherein the substrate is a piezoelectric single crystal.
According to the above invention, characteristics such as vibration characteristics can be improved.

Application Example 4 The method for manufacturing a resonator element according to any one of Application Examples 1 to 3, wherein the groove is formed on one main surface side and the other main surface side of the substrate.
According to the above invention, the CI value can be reduced, and excellent vibration characteristics can be obtained even if the size is reduced.

It is explanatory drawing of the manufacturing method of the vibration piece which concerns on embodiment of this invention. It is a figure which shows an example of the vibration piece which can apply the manufacturing method of the vibration piece which concerns on embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is an explanatory diagram of a process of forming an outer shape and a groove portion of a vibrating piece on a substrate in a method for manufacturing a vibrating piece according to an embodiment of the present invention. FIG. 1 is a schematic cross-sectional view of the substrate 10 in each process. Although FIG. 1 shows the step of forming a groove on one main surface side of the substrate 10, the groove can be formed on the other main surface side of the substrate 10 in the same manner. In the present embodiment, a groove is formed in the central portion of the substrate 10 shown in FIG.

  First, a plate-like (wafer-like) substrate 10 polished to a predetermined thickness is prepared. As a material of the substrate 10, a piezoelectric single crystal such as crystal, lithium niobate single crystal, lithium tantalate single crystal, lithium niobate-lithium tantalate solid solution single crystal, lithium borate single crystal, or langasite single crystal is used. Can do. By using such a piezoelectric single crystal as the substrate 10, it is possible to manufacture a resonator element having a stable resonance frequency without being affected by ambient temperature changes.

  In step 1, a Cr (chrome) film 20 as a first metal film, an Au (gold) film 30 as a second metal film, a Ni (nickel) film 40 as a third metal film on the main surface of the substrate 10 in this order. Form a film.

  In the present embodiment, the Cr film 20 and the Au film 30 are formed by sputtering, and the Ni film 40 is formed by vapor deposition. However, the film formation method is not limited to this, and vapor deposition, sputtering, etc. Any film forming method may be used.

  Here, the Cr film 20 has excellent adhesion to the substrate 10 such as quartz and is inexpensive. On the other hand, the Au film 30 is less soluble in hydrofluoric acid contained in the etchant than the Cr film 20 and is excellent in corrosion resistance to the etchant.

In step 2, a first resist film 50 is formed on the Ni film 40.
In step 3, the first resist film 50 is covered with a mask for forming the outer shape of the vibrating piece and the shape of the groove portion, exposed and developed, and the inside of the outer shape outline of the vibrating piece and the region other than the region where the groove portion is formed Then, the first resist film 50 is patterned so that the first resist film 50 remains.

  In step 4, the Ni film 40 on the substrate 10 that does not overlap with the patterned first resist film 50 is removed by etching. As a result, the outer shape of the resonator element and the shape of the groove are patterned on the Ni film 40 at the same time, and the Au film 30 is exposed at the portion where the Ni film 40 is removed. As described above, by simultaneously patterning the outer shape of the vibrating piece and the shape of the groove on the Ni film 40, the outer shape of the vibrating piece is compared with the case of patterning the outer shape of the vibrating piece and the shape of the groove in separate steps. The accuracy of the relative position between the groove portion and the groove portion can be increased.

In step 5, the first resist film 50 is removed.
In step 6, a second resist film 60 is formed on the substrate 10 (on the Au film 30 exposed by etching of the Ni film 40 and on the Ni film 40).

  In step 7, the outer shape of the resonator element is patterned on the second resist film 60 by performing exposure and development while covering the second resist film 60 with a mask for forming an outer shape.

  In step 8, the Cr film 20 and the Au film 30 that do not overlap with the patterned second resist film 60 are removed by etching.

In step 9, the substrate 10 exposed by etching the Cr film 20 and the Au film 30 is etched to form the outer shape of the resonator element on the substrate 10.
At the time of this etching, the region for forming the groove on the substrate 10 is covered with the three layers of the Cr film 20, the Au film 30 and the second resist film 60. All three layers of the film are not eroded by the etching solution, and therefore, the region on the substrate 10 where the groove is formed is not eroded by the etching solution. In addition, since the Cr film 20 is formed on the substrate 10 and the Cr film 20 has good adhesion to the substrate 10, the Cr film 20 is not peeled off from the substrate 10, and the substrate 10 is etched during the outer shape etching. The etching solution does not enter the region where the upper groove is formed. Furthermore, since the Au film 30 that is corrosion resistant to the etching solution is laminated on the Cr film 20, the region for forming the groove on the substrate 10 is sufficiently protected and is eroded by the etching solution. Never happen.

  In step 10, the second resist film 60 is stripped. As a result, the Au film 30 is exposed in the opening corresponding to the groove pattern patterned on the Ni film 40.

  In step 11, the Au film 30 exposed from the Ni film 40 by peeling off the second resist film 60 and the Cr film 20 under the Au film 30 are removed by etching. At this time, the thickness of each of the films 20, 30, and 40 and the etching solution are adjusted so that the Au film 30 and the Cr film 20 exposed from the Ni film 40 are all removed.

  In step 12, the groove portion 92 is formed in the substrate 10 by half-etching the substrate 10 exposed by removing the Au film 30 and the Cr film 20 to a predetermined depth. At this time, on the substrate 10 other than the region where the groove 92 is to be formed, the Ni film 40 whose etching rate is slower than Cr from the upper layer, the Au film 30 that is corrosion resistant to the etching solution, and the Cr that has good adhesion to the substrate 10 Therefore, even if the processing time is increased to form the deep groove portion 92, all of these three layers are not eroded, and therefore the substrate 10 under the three layers is eroded. It will not be done.

Finally, although not shown, the Ni film 40, the Au film 30, and the Cr film 20 are removed. Thereby, the board | substrate 10 which has the groove part 92 and the external shape of a vibration piece is obtained.
According to such a method of manufacturing a vibrating piece, the Ni film 40 is patterned into the outer shape of the vibrating piece and the shape of the groove, and the outer shape of the vibrating piece is formed without peeling off the Ni film 40 to form the groove. Therefore, the accuracy of the relative position between the outer shape of the resonator element and the groove can be increased.

  In addition, since the Cr film 20 is formed on the substrate 10 without directly forming the resist film having poor adhesion with the substrate 10 on the substrate 10, the substrate 10 is etched when the outer shape of the resonator element is etched on the substrate 10. It is possible to prevent the Cr film 20 from being peeled off from 10 and the groove forming region on the substrate 10 being etched.

  Further, since the outer shape is etched in a state where the region for forming the groove portion on the substrate 10 is covered with the three layers of the Cr film 20, the Au film 30, and the second resist film 60, the outer shape is etched. The region on the substrate 10 where the groove is to be formed is not etched. Therefore, the groove portion of the vibrating piece can be formed with high accuracy.

  In the above-described embodiment, the first metal film is a chromium film, the second metal film is a gold film, and the third metal film is a nickel film. However, the present invention is not limited to this. The first metal film only needs to be a metal having adhesion to the substrate 10, the second metal film only needs to be a metal that is corrosion resistant to the etching solution, and the third metal film. Any metal may be used as long as it has a slower etching rate than Cr. When another metal is used, the film thickness and the etching solution may be adjusted in consideration of the etching rate of the metal to be used.

  FIG. 2 is a perspective view of the resonator element 1 to which the manufacturing method according to the embodiment of the invention can be applied. As shown in the figure, the resonator element 1 extends in a plane composed of an X-axis (second axis) and a Y-axis (first axis) perpendicular to the X-axis in a plane, and is opposed to each other. 82 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 resonator element 1, a first vibrating arm 88 and a second vibrating arm 89 extend from the base 86 in the + Y direction, and a third vibrating arm 90 and a fourth vibrating arm 91 extend in the −Y direction. The base 86, the first vibrating arm 88, and the second vibrating arm 89 constitute one tuning fork type vibrating piece, and the base 86, the third vibrating arm 90, and the fourth vibrating arm 91 constitute one tuning fork type vibrating piece. Yes. The vibrating piece 1 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 1 according to this 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. In each of the first to fourth vibrating arms 88, 89, 90, 91, an elongated groove portion 92 is formed on the first main surface 82 and the second main surface 84. The manufacturing method described above can be applied to the manufacture of such an H-shaped vibrating piece 1.

  In the resonator element 1 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 1 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 1 can be detected.

DESCRIPTION OF SYMBOLS 1 ......... Vibration piece, 10 ......... Substrate, 20 ......... Cr film, 30 ......... Au film, 40 ......... Ni film, 50 ......... First resist film, 60 ......... Second Resist film 82... First main surface 84... Second main surface 86 86 base portion 88 first vibration arm 89 second vibration arm 90 90 Third vibrating arm, 91... Fourth vibrating arm, 92.

Claims (4)

A method of manufacturing a resonator element having a groove,
A step of sequentially forming a first metal film, a second metal film, a third metal film, and a first resist film on a substrate;
Patterning the first resist film into the outer shape of the resonator element and the shape of the groove;
Etching the portion of the third metal film that does not overlap the patterned first resist film;
Forming a second resist film on the second metal film exposed by the etching;
Patterning the second resist film on the outer shape of the resonator element;
Etching the first metal film, the second metal film, and the substrate that do not overlap the patterned second resist film, and forming an outer shape of the resonator element on the substrate;
Stripping the second resist film;
Etching the first metal film and the second metal film corresponding to the groove;
Etching the substrate corresponding to the groove to form the groove in the substrate;
A method of manufacturing a resonator element comprising:   2. The resonator element according to claim 1, wherein the first metal film is a chromium film, the second metal film is a gold film, and the third metal film is a nickel film. Method.   The method for 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 side and the other main surface side of the substrate.

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