JP2010109527A - Crystal vibration chip and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a crystal vibration chip having a structure of suppressing the propagation of thickness-shear vibration which is main vibration to an outer peripheral part, and to provide a method of manufacturing it. <P>SOLUTION: An AT-cut crystal vibration chip 10 includes a so-called mesa structure for which projection parts 5A and 5B presenting a rectangular shape in the plane view are formed at positions facing each other on both main surfaces of an AT-cut crystal substrate. Excitation electrodes 15A and 15B are provided respectively on the respective projection parts 5A and 5B, and external connection electrodes 17A and 17B connected to the respective corresponding excitation electrodes 15A and 15B by inter-electrode wiring 16A and 16B are provided near one end side of the outer peripheral surfaces 6A and 6B of the thin outer peripheral part of the crystal substrate 1. On the outer periphery of the projection parts 5A and 5B, step parts 25A and 25B formed by being made thinner than the projection parts 5A and 5B are provided so as to frame the outer periphery of the respective projection parts 5A and 5B on the outer peripheral surfaces 6A and 6B and on the respective sidewalls of the projection parts 5A and 5B. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a quartz crystal vibrating piece and a manufacturing method thereof, and more particularly to a shape of a quartz crystal vibrating piece for preventing propagation of a thickness shear vibration as a main vibration to an outer peripheral portion, and a manufacturing method thereof.

  Conventionally, in various information / communication equipment, OA equipment, and electronic equipment such as consumer equipment, a piezoelectric device including a piezoelectric vibrator is widely used as a clock source of an electronic circuit. As a piezoelectric material used for the piezoelectric vibrator of such a piezoelectric device, for example, a single crystal crystal is adopted because stable frequency characteristics can be obtained. This quartz crystal vibrating piece consists of a quartz crystal wafer as a single crystal substrate cut out at a predetermined cutting angle from a quartz lambard in which a portion of an artificial quartz crystal is formed into a block shape with a clear crystal axis (optical axis). Formed using. Here, the predetermined cutting angle refers to a cutting angle inclined by a target angle with respect to the crystal axis of the crystal, for example, using a crystal wafer cut at a cutting angle of 35 ° 15 ′ from the crystal axis. The formed AT-cut quartz crystal vibrating piece has long been used as a piezoelectric vibrating piece having excellent temperature characteristics that can obtain a stable frequency in a wide temperature range.

  The thickness shear vibration, which is the main vibration of the AT-cut quartz crystal vibrating piece, is arranged such that the excitation electrode vibrates at the center of the vibrating piece, but the thickness shear vibration that vibrates at the center is Propagated to the outer periphery of A part of the outer periphery of the resonator element serves as a holding part that is secured to a storage container such as a package, so that the vibration propagated from the center part of the resonator element is suppressed, affecting the thickness shear vibration that is the main vibration. Alternatively, vibration energy leaks from the holding part, and crystal impedance (hereinafter referred to as “CI value”) decreases, or other vibration modes are induced to decrease the stability of the oscillation frequency.

In order to prevent the vibration propagated to the outer periphery of the vibrating piece as described above and prevent the leakage and stabilize the oscillation frequency, the vibrating piece is made into a convex shape by performing a convex process or the like. A method of concentrating vibration energy on the central portion of the main surface of the vibration piece by suppressing the propagation of vibration to the outer periphery of the vibration piece by using a thin outer peripheral portion has been implemented.
Conventionally, in order to form a vibrating piece having a convex shape in cross section, for example, a convex process using a barrel polishing machine has been performed. A barrel polishing machine puts hundreds to thousands of crystal element pieces cut out from a quartz base plate (crystal wafer) into a rectangular shape with a polishing agent into a pot together with an abrasive and puts the pot at a predetermined speed. By rotating for a time, a convex convex cross section is formed. However, the convex machining of the vibrating piece by the barrel polishing machine has a problem that it takes a long time, so that the manufacturing efficiency and productivity are low, and it is difficult to control the convex shape and it is difficult to obtain a desired machining accuracy.
As an alternative to the convex processing by such a barrel polishing machine, for example, in Patent Document 1, the cross-sectional convex shape of the quartz crystal vibrating piece is approximately replaced with a stepped shape to obtain the same vibration confinement effect as the cross-sectional convex shape, In addition, a method of manufacturing the resonator element having the staircase shape by photolithography in which the etching resist dimension is changed stepwise is disclosed.

The crystal vibrating piece (AT-cut crystal piece) described in Patent Document 1 is a plano section having a stepped cross section in which a central portion is thick and a plurality of steps that are thin toward both ends are formed. It has a cross-sectional shape that approximates a convex shape.
In addition, in such a method of manufacturing a quartz crystal resonator element having a stepped cross section, a corrosion resistant film made of, for example, an acid-resistant metal film is formed on both main surfaces of an AT-cut quartz substrate by sputtering or the like, and then a photoresist. Apply the coating, expose and develop the shape of the step on the most central side, immerse it in an etching solution, etch the portion of the corrosion-resistant film where the exposed photoresist is removed, and form the step on the most central side made of this corrosion-resistant film An etching mask is formed. Thereafter, the quartz substrate is etched by being immersed in an etching solution made of, for example, a hydrogen fluoride solution and an ammonium fluoride solution, thereby forming a step on the most central side of the quartz substrate. Thereafter, the photolithography process is repeated for the required number of steps to make the quartz substrate have a stepped cross section. Then, necessary electrodes such as excitation electrodes are formed by sputtering or the like.

JP 58-47316 A

  However, in the method of etching by changing the dimension of the etching resist made of the corrosion-resistant film step by step, like the method of manufacturing the crystal vibrating piece having a stepped cross section approximate to the cross-sectional convex shape described in Patent Document 1, the photolithography is performed by changing the dimensions of the etching resist stepwise. Since it is necessary to repeat the process many times, the process is complicated and takes a lot of man-hours, which may reduce the productivity and increase the manufacturing cost.

  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 the crystal resonator element according to this application example, a convex portion having a predetermined shape is provided on at least one main surface of both main surfaces of an AT-cut crystal base material, and an excitation electrode is provided on the convex portion. Is formed, and at least the X-axis (electric axis) side of the outer peripheral portion of the convex portion is provided with a step portion made of a deposit and having a thickness smaller than that of the convex portion.

According to this configuration, since the convex portion having the excitation electrode formed on the surface has a mesa structure, the thickness-shear vibration when the crystal vibrating piece is excited can be concentrated more under the excitation electrode. The stepped portion is provided on the X-axis side where at least the thickness-slip vibration is mainly propagated in the outer peripheral portion of each convex portion of the quartz crystal vibrating piece, thereby forming a cross-sectional staircase shape having a plurality of steps. A cross-sectional shape approximated to a convex lens-like plano convex shape is formed.
Therefore, the thickness-shear vibration is concentrated in the central part, and further, the propagation to the outer peripheral part is suppressed, so that the reduction of the CI value and the coupling with other vibration modes are suppressed, and a crystal vibrating piece with a stable frequency characteristic is obtained. Can be provided.

  Application Example 2 In the quartz crystal resonator element according to the above application example, the step portion is also provided on the Z-axis (optical axis) side of the quartz base material.

  According to this configuration, it is possible to more reliably suppress the propagation of the thickness shear vibration from the center of the crystal vibrating piece to the outer peripheral portion.

  Application Example 3 In the quartz crystal resonator element according to the application example described above, the step portion is made of the same material as the excitation electrode.

  According to this configuration, the step portion can be formed at the same time as the formation of the electrode such as the excitation electrode, so that the efficiency is high.

  Application Example 4 In the quartz crystal resonator element according to the application example, the step portion is formed in a region different from a region where the excitation electrode, the inter-electrode wiring drawn from the excitation electrode, and the external connection electrode are formed. It is characterized by.

  According to this configuration, it is possible to provide a quartz crystal resonator element having excellent frequency characteristics by preventing propagation of thickness shear vibration to the outer peripheral portion while avoiding electrical problems such as a short circuit.

  Application Example 5 The quartz crystal resonator element according to the application example described above is characterized in that a plurality of the convex portions provided with the step portions on the outer peripheral portion are provided so as to form a stepped cross section.

  According to this configuration, since a cross-sectional staircase shape having a large number of steps is formed, a crystal vibrating piece having a cross-sectional shape approximated by a plano-convex shape having a plano-convex lens shape can be obtained. Therefore, propagation of thickness shear vibration to the outer peripheral portion and coupling with spurious vibration are suppressed, and a quartz crystal resonator element having excellent frequency characteristics can be provided.

  [Application Example 6] In the method of manufacturing a quartz crystal resonator element according to this application example, at least one main surface of both main surfaces of the AT-cut crystal base material is provided with a convex portion having a predetermined shape, In the method of manufacturing a quartz crystal vibrating piece, the excitation electrode is formed on the outer peripheral portion of the convex portion, and at least the X-axis (electrical axis) side of the outer peripheral portion of the convex portion is provided with a step portion made of a deposit and having a smaller thickness than the convex portion. A step of forming an outer shape of the quartz crystal resonator element by photolithography, a step of etching a part of the AT-cut quartz crystal substrate by photolithography to form the convex portion, and a step of forming the convex portion. Thereafter, a step of forming an electrode including the excitation electrode and a step of forming the step portion by a thin film deposition method are included.

  According to this configuration, in addition to the convex portion formed by crystal etching having a long processing time, a multi-step cross-sectional step shape is formed by the step portion provided on the outer peripheral portion of the convex portion, and the outer periphery of the thickness shear vibration Accordingly, it is possible to efficiently manufacture a quartz crystal vibrating piece having excellent frequency characteristics while suppressing propagation to a part.

  Application Example 7 In the method for manufacturing a quartz crystal resonator element according to the application example described above, the step of forming the convex portion is performed after the step of forming the outer shape.

  According to this configuration, after the step of forming the outer shape of the quartz crystal vibrating piece, the convex portion is formed by using the corrosion-resistant film used in the step of forming the outer shape by adopting a route for forming the convex portion. Therefore, it is efficient because an etching resist can be formed.

  Application Example 8 In the method for manufacturing a quartz crystal resonator element according to the application example, the step of forming the electrode includes a step of forming the step portion, and the step portion is formed of the same material as the electrode. And

  According to this configuration, the step portion can be formed simultaneously with the formation of the electrode such as the excitation electrode, so that the manufacturing efficiency is improved.

  Hereinafter, an embodiment of an AT-cut quartz crystal resonator element and a manufacturing method thereof will be described with reference to the drawings.

(First embodiment)
First, an embodiment of an AT cut quartz crystal resonator element will be described.
1A and 1B schematically illustrate an AT-cut quartz crystal resonator element according to this embodiment. FIG. 1A is a plan view, FIG. 1B is a cross-sectional view taken along line AA in FIG. (A) BB sectional drawing, (d) is the elements on larger scale of the D section of (b). In FIG. 1, X, Y, and Z in the figure indicate the crystal axis directions of quartz, the X axis indicates the electrical axis, the Y axis indicates the mechanical axis, and the Z axis indicates the optical axis. Further, the hatched hatching applied in FIG. 1A is intended to facilitate identification of electrodes and wiring such as excitation electrodes, and does not indicate a cross section.

As shown in FIG. 1, the AT-cut quartz crystal resonator element 10 has a relative relationship between both main surfaces of a crystal base 1 formed by using an AT-cut crystal wafer cut at a cutting angle inclined by 35 ° 15 ′ from the crystal axis. It has a so-called mesa structure in which convex portions 5A, 5B having a rectangular shape in a plan view are formed at the facing positions.
The outer shape of the quartz substrate 1 having the mesa structure is precisely formed by wet etching the quartz substrate 1 (quartz wafer) with a hydrofluoric acid solution or the like by photolithography as will be described later. can do.

As shown in FIG. 1A, an excitation electrode 15 </ b> A that is a driving electrode is provided on one convex portion 5 </ b> A of the quartz crystal substrate 1. Further, on the surface of the quartz substrate 1 on the convex portion 5A side, an external connection electrode 17A connected to the excitation electrode 15A and the interelectrode wiring 16A is provided in the vicinity of one end side of the outer peripheral surface 6A of the thin outer peripheral portion. Yes. Similarly, an excitation electrode 15B is provided on the other convex portion 5B of the crystal base material 1 (see FIG. 1B), and a thin outer periphery is provided on the surface of the crystal base material 1 on the convex portion 5B side. The external connection electrode 17B provided in the vicinity of one end of the outer peripheral surface 6B of the part is connected by the inter-electrode wiring 16B. In the AT-cut crystal resonator element 10, the portions of the outer peripheral surface 6A and the outer peripheral surface 6B where the external connection electrodes 17A and the external connection electrodes 17B are provided are bonded onto the mount terminals of the package via a conductive adhesive or the like. When it is done, it becomes the support portion 11 that supports the AT-cut quartz crystal vibrating piece 10.
Such electrode patterns such as electrodes and wirings are formed by, for example, nickel (Ni) by vapor deposition or sputtering after the quartz substrate 1 (quartz wafer) is etched to form the outer shape of the AT-cut quartz crystal vibrating piece 10 having a mesa structure. ) Or chromium (Cr) as a base layer, a metal film made of, for example, gold (Au) is formed thereon, and then patterned using photolithography.

Further, as shown in FIG. 1A, the outer periphery of the convex portion 5A is formed on the outer peripheral surface 6A and on the side wall of the convex portion 5A and is made of an electrode forming metal and has a smaller thickness than the convex portion 5A. The step portion 25A is provided so as to border the outer periphery of the convex portion 5A. That is, the step portion 25A has two sides on the quartz substrate 1 that is AT-cut, the two sides facing the X-axis (electric axis) side of the convex portion 5A and the two sides facing the Z-axis (optical axis) side. All are provided so as to surround the convex portion 5A. Further, the step portion 25A of this embodiment is made of the same metal material as the excitation electrodes 15A and 15B, the external connection electrodes 17A and 17B, or the inter-electrode wirings 16A and 16B, and is formed at the same time.
Similarly, on the outer periphery of the convex portion 5B, a step portion 25B formed on the outer peripheral surface 6B and on the side wall of the convex portion 5B with a smaller thickness than the convex portion 5B borders the outer periphery of the convex portion 5B. (Refer to FIG. 1B and FIG. 1C).

As shown in FIG. 1 (d), in the vicinity of the side on the X-axis (electric axis) side of the convex portion 5A of the AT-cut quartz crystal vibrating piece (10), it is more than the convex portions 5A and 5A of the quartz base material 1. A cross-sectional staircase shape having three steps is formed by the outer peripheral surface 6A, which is a portion having a small thickness, and the step portion 25A formed on the outer peripheral surface 6A with a thickness smaller than the convex portion 5A. Similarly, in the vicinity of the side of the convex portion 5B on the X-axis (electrical axis) side, the convex portion 5B of the quartz base material 1, the outer peripheral surface 6B that is a portion having a smaller thickness than the convex portion 5B, and the outer peripheral surface 6B. The stepped portion 25B formed with a thickness smaller than the convex portion 5B forms a cross-sectional step shape having three steps.
Accordingly, a cross section approximated to one end side of a plano-convex shape of a plano-convex lens is formed on one X-axis (electric axis) side of each of the convex-formed portions 5A and 5B forming surfaces of the AT-cut quartz crystal vibrating piece (10). A shape is formed.

  Similarly, three steps are formed on the other X-axis (electric axis) side of the convex portions 5A and 5B and the two opposite sides of the convex portions 5A and 5B on the Z-axis (optical axis) side. Thus, the AT cut quartz crystal vibrating piece 10 has a cross-sectional shape approximated to a plano-convex shape of a plano-convex lens.

  As shown in FIG. 1 (a), the step portions 25A and 25B made of an electrode forming metal include excitation electrodes 15A and 15B, external connection electrodes 17A and 17B, and an interelectrode wiring 16A that connects them correspondingly. , 16B, etc., so as to be electrically insulated from the electrodes and the inter-electrode wirings.

According to the AT-cut quartz crystal resonator element 10 of the above embodiment, the mesa structure is provided by the convex portions 5A and 5B provided at the opposing positions of both main surfaces of the quartz base material 1 and having the excitation electrodes 15A and 15B respectively formed on the surface. Therefore, the thickness shear vibration when the AT-cut quartz crystal vibrating piece 10 is excited can be concentrated more under the excitation electrodes 15A and 15B. In addition, the stepped portions 25A and 25B provided on the outer circumferences of the convex portions 5A and 5B of the AT-cut quartz crystal vibrating piece 10 form a sectional step shape having three steps. Thereby, one convex part 5A, 5B which requires a long processing time is formed on each main surface, and each convex part 5A, 5B which can be formed relatively easily and corresponding step part 25A, 25B. By forming the cross-sectional staircase shape by combination, a cross-sectional shape that is efficiently approximated to a plano-convex shape of a plano-convex lens is formed.
In addition, since the AT cut quartz crystal resonator element 10 has a mesa structure, the thickness of the support portion 11 joined to the package or the like is reduced, so that leakage of vibration from the support portion 11 can be suppressed.
Therefore, the thickness-shear vibration is concentrated in the central part, and further, the propagation to the outer peripheral part is suppressed, so that the decrease in the CI value and the coupling with other vibration modes are suppressed, and the AT-cut crystal vibration with stable frequency characteristics. A piece 10 can be provided.

[Manufacturing method of AT-cut crystal vibrating piece]
Next, a method for manufacturing the AT-cut quartz crystal vibrating piece 10 will be described.
FIG. 2 is a flowchart for explaining a manufacturing process of the AT-cut quartz crystal resonator element according to this embodiment. 3 and 4 show the manufacturing process of the convex forming process in step S3 and the electrode and step forming process in step S4 in the flowchart of FIG. 2 in the manufacturing method of the AT-cut quartz crystal vibrating piece 10 of the present embodiment. It is a schematic cross section of a quartz crystal vibrating piece to be specifically described.

  In FIG. 2, in manufacturing the AT-cut quartz crystal vibrating piece 10, first, a wafer made of a large-sized quartz substrate that has been AT-cut is prepared (step S1). Specifically, a cutting angle inclined by 35 ° 15 ′ from the crystal axis of the quartz crystal by using a wire saw or band saw from a quartz lambard obtained by forming a part of an artificial quartz stone into a block shape with a clear crystal axis. An AT-cut quartz substrate wafer cut out with the aim of is obtained. Then, the cut wafer is polished so as to have a desired thickness and surface state while accurately correcting the cutting angle.

Next, as shown in step S2, the outer shape of one or a plurality of AT-cut quartz crystal vibrating pieces 10 is formed on the quartz substrate wafer by wet etching using photolithography. More specifically, first, a corrosion resistant film made of, for example, chromium (Cr) and gold (Au) serving as an etching mask is formed on both the main surfaces of the quartz substrate wafer by sputtering, and then a photoresist is applied. A mask for patterning the outer shape of the AT-cut quartz crystal vibrating piece 10 is placed on the photoresist.
Then, after the exposure, the exposed portion of the photoresist is developed and removed, and then immersed in an etching solution, and the corrosion-resistant film of the portion where the exposed photoresist is removed is etched to form an AT made of the corrosion-resistant film on the wafer. An etching mask for forming the outer shape of the cut quartz crystal vibrating piece 10 is formed.
Thereafter, the wafer on which the etching mask for forming the outer shape of the AT-cut quartz crystal vibrating piece 10 is formed is immersed in an etching solution made of, for example, a hydrogen fluoride solution and an ammonium fluoride solution, so that the outer shape of the AT-cut crystal vibrating piece 10 of the wafer is obtained. Etching is carried out until the portion corresponding to is penetrated.
Note that the outer shape of the AT-cut quartz crystal vibrating piece 10 is connected to the wafer by a perforated break-off portion so as not to be completely separated from the wafer. Thereby, after the subsequent steps are efficiently flowed in the wafer state, the individual AT-cut quartz crystal vibrating piece 10 can be obtained by finally folding the folding portion.

Next, as shown in step S3, the convex portions 5A and 5B are formed using photolithography.
More specifically, as shown in FIG. 3A, the crystal base material 1 after the outer shape formation in which the corrosion resistant film 95 is provided on both surfaces is prepared. In the present embodiment, the anticorrosion film 95 used as an etching mask in the outer shape forming step (step S2 in FIG. 2) of the AT cut quartz crystal vibrating piece 10 is used without being peeled off.

That is, in the convex forming step, first, as shown in FIG. 3B, a photoresist 97 is applied on the corrosion-resistant film 95, and then the convex (5A) pattern on the glass plate 81 is applied to the photoresist 97. The shape of each of the convex portions (5A, 5B) is exposed using the photomask 80A and the photomask 80B provided with the 85A and convex portion (5B) patterns 85B, respectively.
Next, as shown in FIG. 3C, the photoresist 97 is developed to obtain a convex portion (5A) pattern 97A and a convex portion (5B) pattern 97B.

Next, as shown in FIG. 3D, the corrosion-resistant film (95) is etched by using the photoresist convex part (5A) pattern 97A and convex part (5B) pattern 97B as an etching resist, and from the corrosion-resistant film (95). The convex portion (5A) pattern 95A and the convex portion (5B) pattern 95B are formed.
Next, as shown in FIG. 3E, the wafer is etched with, for example, a hydrogen fluoride solution and an ammonium fluoride solution using the convex portion (5A) pattern 95A and the convex portion (5B) pattern 95B as an etching mask. The protrusions 5A and 5B are formed by immersing in a predetermined time.
And as shown in FIG.3 (f), the convex part (5A) pattern 95A and convex part (5B) pattern 95B which consist of a corrosion-resistant film are peeled, and the crystal base material 1 with which convex part 5A, 5B was formed is shown. obtain.

  Returning to FIG. 2, next, as shown in step S4, the excitation electrodes 15A and 15B, the external connection electrodes 17A and 17B, and them are made to correspond to each other by using a vapor deposition method such as sputtering or vapor deposition or photolithography. An electrode and a step are formed to simultaneously form electrodes and wires such as the inter-electrode wires 16A and 16B to be connected and step portions 25A and 25B made of metal for forming these electrodes.

More specifically, as shown in FIG. 4 (a), nickel or chromium or the like is used as an underlayer by vapor deposition or sputtering on both sides of the quartz base material 1 on which the convex portions 5A and 5B are formed. A metal film 105 which is a metal film for forming an electrode in which is laminated is formed.
Next, as shown in FIG. 4B, after applying a photoresist 98 on the metal film 105, the excitation electrode (15A) pattern 86A and the stepped portion (25A) are applied to the photoresist 98 on the glass plate 83. ) Exciting electrodes 15A, 15B using photomask 82A provided with pattern 87A and photomask 82B provided with excitation electrode (15B) pattern 86B and step (25B) pattern 87B on another glass plate 83 Each shape of step part 25A, 25B is exposed (refer FIG.4 (c)).

  Next, as shown in FIG. 4D, the photoresist 98 is developed to remove the exposed portion of the photoresist, and the excitation electrode (15A) pattern 98Aa and stepped portion (25A) pattern 98Ab, and the excitation electrode are removed. (15B) A pattern 98Ba and a step (25B) pattern 98Bb are obtained.

Next, as shown in FIG. 4E, the excitation electrode (15A) pattern 98Aa and step (25A) pattern 98Ab of the photoresist, and the excitation electrode (15B) pattern 98Ba and step (25B) pattern 98Bb are formed. After etching the metal film (105) as an etching resist, as shown in FIG. 4F, the excitation electrode (15A) pattern 98Aa and step (25A) pattern 98Ab of the photoresist, the excitation electrode (15B) pattern 98Ba, and By peeling off the step (25B) pattern 98Bb, the excitation electrode 15A and the step 25A, and the excitation electrode 15B and the step 25B are obtained.
Although not shown in the drawings, in the above-described electrode and step portion forming step, the external connection electrodes 17A and 17B and the interelectrode wiring 16A that connects them in association with the excitation electrodes 15A and 15B and the step portions 25A and 25B. , 16B, and other electrodes and wiring patterns are formed simultaneously.

  Returning to FIG. 2, next, as shown in step S <b> 5, the individual AT-cut quartz crystal vibrating piece 10 is broken off from the quartz substrate wafer by the above-described folding unit to obtain individual AT-cut quartz crystal vibrating piece 10. Separation is performed, and a series of manufacturing steps of the AT-cut quartz crystal vibrating piece 10 is completed.

According to the manufacturing method of the AT-cut quartz crystal vibrating piece 10 of the above embodiment, the thickness-shear vibration is obtained by having the cross-sectional step shape formed by the convex portions 5A and 5B and the step portions 25A and 25B provided on the outer peripheral portions thereof. It is possible to manufacture the AT-cut quartz crystal vibrating piece 10 that suppresses the propagation to the outer periphery of the crystal.
Further, according to the manufacturing method, after the outer shape forming step of the AT cut quartz crystal vibrating piece 10, the process of forming the convex portions 5 </ b> A and 5 </ b> B is performed, so that the AT cut quartz crystal vibrating piece 10 is formed in the outer shape forming step. Since the etching resist for the convex portions 5A and 5B can be formed using the corrosion-resistant film used, the efficiency is high.

  The AT-cut quartz crystal resonator element and the manufacturing method thereof described in the above embodiment can be implemented as the following modifications.

(Modification)
In the AT-cut quartz crystal resonator element 10 of the above embodiment, one step portion made of the convex portions 5A and 5B formed by etching the crystal base material 1 and the step portions 25A and 25B made of metal for electrode formation. A cross-sectional staircase shape having three steps was formed. However, the present invention is not limited to this, and a stepped portion formed by etching the quartz base material and a plurality of stepped portions formed by depositing a metal for forming electrodes may be provided.
FIG. 5 is a cross-sectional view schematically illustrating an AT-cut quartz crystal vibrating piece provided with a plurality of step portions formed by etching a quartz crystal base material and a step portion formed by depositing a metal for forming an electrode, etc. FIG. FIG. 6 is a flowchart for explaining the manufacturing process of the AT-cut quartz crystal vibrating piece according to this modification.

In FIG. 5, the AT-cut quartz crystal vibrating piece 50 is a first protrusion having a rectangular shape in plan view at a position where both main surfaces of the quartz base material 41 formed by using an AT-cut quartz wafer are opposed to each other. The portions 46A and 46B are formed, and the second protrusions 45A and 45B are formed at opposite positions in the center of the first protrusions 46A and 46B.
The external shape having such a multistage mesa structure of the crystal base 41 is precisely formed by etching the crystal base 41 (crystal wafer) by photolithography.

An excitation electrode 55A is provided on one second convex portion 45A of the quartz base material 41, and an excitation electrode 55B is provided on the other second convex portion 45B.
Note that external connection electrodes respectively corresponding to the excitation electrodes 55A and 55B are provided on the outer peripheral surfaces 47A and 47B of the thinnest outer peripheral portion of the AT-cut crystal vibrating piece 50, similarly to the AT-cut crystal vibrating piece 10 of the above embodiment. However, illustration is omitted.

Further, on the outer periphery of one second convex portion 45A of the AT-cut quartz crystal vibrating piece 50, the first convex portion 46A and the side wall of the second convex portion 45A have a thickness larger than that of the second convex portion 45A. A stepped portion 65A formed with a small amount is provided so as to border the outer periphery of the second convex portion 45A. That is, the step portion 65A has two sides facing the X-axis (electric axis) side and the Z-axis (optical axis) side of the second convex portion 45A in the AT-cut quartz crystal base 41. All four sides are provided so as to surround the second convex portion 45A. The step portion 65A is made of the same material as the electrode forming metal material such as the excitation electrodes 55A and 55B and the external connection electrodes, and is formed at the same time.
Similarly, on the outer periphery of the other second convex portion 45B, the first convex portion 46B and the side wall of the second convex portion 45B are made of a metal material for electrode formation than the second convex portion 45B. A step portion 65B formed with a reduced thickness is provided so as to border the outer periphery of the second convex portion 45B.

Further, on the outer periphery of one first convex portion 46A of the AT-cut crystal vibrating piece 50, the outer peripheral surface 47A and the side wall of the first convex portion 46A are made thinner than the first convex portion 46A. A stepped portion 75A made of the formed electrode forming metal material is provided so as to border the outer periphery of the first convex portion 46A.
Similarly, on the outer periphery of the other first convex portion 46B, the electrode is formed on the outer peripheral surface 47B and on the side wall of the first convex portion 46B with a thickness smaller than that of the first convex portion 46B. A step portion 75B made of a metal material is provided so as to border the outer periphery of the first convex portion 46B.

As described above, in the cross section of the AT-cut quartz crystal vibrating piece 50 having the configuration described above, the second convex portion 45A and the second convex portion 46A of the quartz base material 41 are formed on the side where the excitation electrode 55A is formed. A cross-sectional staircase shape having five steps is formed by the step portion 65A formed with a thickness smaller than the convex portion 45A and the step portion 75A formed on the outer peripheral surface 47A with a thickness smaller than the first convex portion 46A. Has been.
Similarly, in the cross section of the AT cut quartz crystal vibrating piece 50, the second convex portion 45B of the quartz base material 41 and the second convex portion 45B on the first convex portion 46B are formed on the side where the excitation electrode 55B is formed. The stepped portion 65B formed with a smaller thickness and the stepped portion 75B formed on the outer peripheral surface 47B with a thickness smaller than that of the first convex portion 46B form a cross-sectional staircase shape having five steps. .
Thereby, the AT-cut quartz crystal vibrating piece 50 has a cross-sectional shape that is more approximate to the plano-convex shape of a plano-convex lens as compared with the AT-cut quartz crystal vibrating piece 10 of the above embodiment.

  Next, a method for manufacturing the AT-cut quartz crystal vibrating piece 50 of this modification will be described. In addition, since the manufacturing method of the AT cut quartz crystal vibrating piece 50 of the present modification is the same as the manufacturing method of the AT cut quartz crystal vibrating piece 10 of the above embodiment except that the convex forming process is repeated twice, the description thereof is omitted. To do.

  In FIG. 6, in the manufacturing method of the AT-cut quartz crystal resonator element 50, first, as shown in step S11, the AT-cut quartz substrate wafer cut out from the quartz lambard by the AT-cut is brought into a desired thickness and surface state. The wafer to be polished is prepared so as to be.

  Next, as shown in step S12, one or more AT-cut quartz crystal vibrations are formed on the quartz substrate wafer by wet etching using photolithography in the same manner as the outer shape forming step (step S2 in FIG. 2) of the above embodiment. The outer shape of the piece 50 is formed.

  Next, as shown in step S13 and step S14, the first protrusions 46A, 46A, and 46B are formed using photolithography in the same manner as the protrusion formation process in the above embodiment (see step S3 and FIG. 3 in FIG. 2). 46B and the second convex portions 45A and 45B are formed in this order. Specifically, the corrosion-resistant film used as an etching mask in the outer shape forming step in step S12 is used without being peeled off, and photolithography is repeated twice using the corrosion-resistant film as an etching mask. 46A, 46B and second convex portions 45A, 45B are formed sequentially.

  Next, as shown in step S15, the electrodes such as the excitation electrodes 55A and 55B, the external connection electrodes, and the inter-electrode wirings that connect them correspondingly by using a vapor deposition method such as sputtering or vapor deposition or photolithography. The electrodes and the step portions are simultaneously formed to form step portions 65A and 65B and step portions 75A and 75B made of metal for forming the electrodes and wiring.

  Then, as shown in step S16, individual AT-cut quartz crystal vibrating pieces 50 are separated from the quartz substrate wafer to obtain individual AT-cut quartz crystal vibrating pieces 50, and a series of AT-cut quartz crystal vibrating pieces are obtained. 50 manufacturing steps are completed.

According to the AT-cut quartz crystal vibrating piece 50 of the above modification, the two protrusions of the first protrusions 46A and 46B and the second protrusions 45A and 45B and the steps provided on the outer periphery of each of the two protrusions. The cross-sectional staircase shape having five steps is formed by the portions 75A and 75B and the step portions 65A and 65B. Accordingly, it is possible to efficiently form a cross-sectional shape that is more approximate to a plano-convex shape of a plano-convex lens than when a stepped cross-sectional shape is formed only by forming a convex portion that requires a long processing time.
Therefore, the AT-cut quartz crystal that can more effectively suppress the propagation of the vibration to the outer peripheral portion by attenuating the propagation of the thickness-shear vibration from the central portion toward the outer peripheral portion of the AT-cut crystal vibrating piece 50. The vibrating piece 50 can be provided.

  The embodiment of the present invention made by the inventor has been specifically described above, but the present invention is not limited to the above-described embodiment, and various modifications are made without departing from the scope of the present invention. Is possible.

  For example, in the above-described embodiment and the modification, by providing convex portions and step portions on both main surfaces of the AT-cut quartz crystal bases 1 and 41, an AT having a cross-sectional shape approximated to a plano-convex shape of a plano-convex lens shape Cut quartz crystal vibrating pieces 10 and 50 were formed. Not only this but the structure which provides a convex part and a step part in the one main surface side of a crystal base material has an effect which attenuates propagation of thickness shear vibration from the center part of an oscillation piece toward an outer peripheral part.

  Moreover, in the manufacturing method of the AT cut quartz crystal vibrating piece 10 of the above embodiment, the procedure for performing the convex portion forming step after the outer shape forming step has been described. The AT cut quartz crystal vibrating piece 10 of the above-described embodiment can be manufactured not only in this but also as a route for performing the convex portion forming step before the outer shape forming step.

  In the embodiment and the modification, the step portions 25A and 25B or the step portions 65A, 65B, 75A and 75B are formed simultaneously with the electrodes using a metal material for electrode formation such as an excitation electrode and an external connection electrode. Formed. However, the present invention is not limited to this, and for example, it may be a stepped portion made of a deposit of another material formed by depositing a liquid or paste-like resin or glass to form a film.

  Further, in the above embodiment and the modified example, the step portion 25A, 25A, 5B, the first convex portion 46A, 46B or the second convex portion such as the second convex portion 45A, 45B, 25B or step portions 65A, 65B, 75A, 75B were provided. However, the present invention is not limited to this, and the AT-cut quartz crystal bases 1 and 41 may be provided with stepped portions on at least two sides facing the X-axis (electric axis) side of the convex portion. Also by this, propagation of the thickness shear vibration to the outer peripheral portion of the AT-cut quartz crystal resonator piece mainly occurs on the X-axis side of the AT-cut quartz crystal bases 1 and 41, so that the thickness shear vibration is propagated to the outer peripheral portion. It can be effectively suppressed.

  Further, in the AT-cut quartz crystal vibrating piece 50 according to the above-described modified example, the two protrusions of the first protrusions 46A and 46B and the second protrusions 45A and 45B and the steps provided on the outer peripheral portion of each protrusion. By the portions 75A and 75B and the step portions 65A and 65B, an approximate cross-sectional step shape was formed by a plano-convex shape having a plano-convex lens shape. It is good also as a structure which provides not only this but three or more convex parts, and forms a step part in the outer peripheral part of each convex part.

(A) is a plan view schematically illustrating an AT-cut quartz crystal vibrating piece as a quartz crystal vibrating piece according to the present embodiment, (b) is a cross-sectional view taken along line AA in (a), and (c) is Sectional drawing of the BB line of (a), (d) is the elements on larger scale of the D section of (b). The flowchart explaining the manufacturing process of the AT cut quartz crystal vibrating piece of this embodiment. FIG. 4 is a schematic cross-sectional view of a quartz crystal resonator element that specifically explains a manufacturing process of a convex portion forming step, an electrode, and a step forming step in the method for manufacturing an AT-cut quartz crystal resonator element of the present embodiment. FIG. 4 is a schematic cross-sectional view of a quartz crystal resonator element that specifically explains a manufacturing process of a convex portion forming step, an electrode, and a step forming step in the method for manufacturing an AT-cut quartz crystal resonator element of the present embodiment. Sectional drawing which illustrates typically the modification of AT cut quartz crystal vibrating piece The flowchart explaining the manufacturing method of the AT cut quartz crystal vibrating piece of the modification.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,41 ... Crystal base material, 5A, 5B ... Convex part, 6A, 6B, 47A, 47B ... Outer peripheral surface, 10, 50 ... AT cut quartz crystal vibrating piece, 11 ... Support part, 15A, 15B, 55A, 55B ... Excitation Electrode, 16A, 16B ... interelectrode wiring, 17A, 17B ... external connection electrode, 25A, 25B, 65A, 65B, 75A, 75B ... stepped portion, 45A, 45B ... second convex portion, 46A, 46B ... first Convex part, 80A, 80B, 82A, 82B ... Photomask, 85A, 85B, 95A, 95B, 97A, 97B ... Convex part pattern, 86A, 86B, 98Aa, 98Ba ... Excitation electrode pattern, 87A, 87B, 98Ab, 98Bb ... Step pattern, 95 ... corrosion resistant film, 97,98 ... photoresist, 105 ... metal film.

Claims (8)

  A convex portion having a predetermined shape is provided on at least one main surface of both main surfaces of the AT-cut quartz crystal base material, an excitation electrode is formed on the convex portion, and at least the X-axis ( A quartz crystal resonator element, wherein a step portion made of a deposit and having a thickness smaller than that of the convex portion is provided on the electric axis) side. The quartz crystal resonator element according to claim 1,
The crystal resonator element, wherein the step portion is also provided on the Z-axis (optical axis) side of the crystal base material. The quartz crystal resonator element according to claim 1 or 2,
The stepped portion is made of the same material as that of the excitation electrode. The crystal resonator element according to claim 3,
The crystal resonator element according to claim 1, wherein the step portion is formed in a region different from a region where the excitation electrode, the inter-electrode wiring drawn from the excitation electrode, and the external connection electrode are formed. In the crystal vibrating piece according to any one of claims 1 to 4,
A quartz crystal vibrating piece, wherein a plurality of the convex portions provided with the step portions on an outer peripheral portion are provided so as to form a stepped cross section. A convex portion having a predetermined shape is provided on at least one main surface of both main surfaces of the AT-cut quartz crystal base material, an excitation electrode is formed on the convex portion, and at least the X-axis ( On the electric shaft) side, a quartz vibrating piece manufacturing method in which a step portion made of a deposit and having a thickness smaller than the convex portion is provided,
Forming the outer shape of the quartz crystal resonator element by photolithography,
Etching the part of the AT-cut quartz base material by photolithography to form the convex part;
A method of manufacturing a quartz crystal vibrating piece, comprising: a step of forming an electrode including the excitation electrode, and a step of forming the step portion by a thin film deposition method after the step of forming the convex portion. In the manufacturing method of the crystal vibrating piece according to claim 6,
A method of manufacturing a quartz crystal vibrating piece, comprising performing a step of forming the convex portion after the step of forming the outer shape. In the manufacturing method of the crystal vibrating piece according to claim 6 or 7,
Forming the electrode includes forming the step;
A method of manufacturing a quartz crystal vibrating piece, wherein the step is formed of the same material as the electrode.

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