Crystal vibrating piece, crystal oscillator, sensor, oscillator, and method for manufacturing crystal vibrating piece

Abstract

To provide an excitation electrode that can reliably suppress the occurrence of frequency fluctuation without being affected by heat in the process or usage environment, can be miniaturized, and has excellent productivity at low cost, and a crystal vibrating piece, a crystal vibrator, a sensor, an oscillator, and a method for manufacturing the crystal vibrating piece.SOLUTION: In a crystal vibrating piece 3, excitation electrodes 41 and 42 are arranged on the outer surface of a crystal plate 30. The excitation electrodes 41 and 42 apply an electric field to the crystal plate 30 to excite the crystal plate 30. The excitation electrodes 41 and 42 have a single-layer structure made of a two-dimensional layered material, and are arranged in pairs so as to face each other with the crystal plate 30 interposed therebetween.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present disclosure relates to an excitation electrode, a quartz crystal resonator element, a quartz crystal unit, a sensor, an oscillator, and a method for manufacturing the quartz crystal resonator element. [Background technology]

[0002] For example, in electronic devices such as mobile phones and personal digital assistants, crystal-based oscillators have traditionally been used as devices used as time sources, timing sources for control signals, reference signal sources, etc. Known examples of this type of crystal oscillator include one in which a crystal resonator element is hermetically sealed in a package with a cavity formed therein.

[0003] An example of such a quartz crystal vibrating piece is one that includes a quartz crystal blank having a base and a pair of vibrating arms extending parallel to each other from the base, and excitation electrodes arranged on the surfaces of the pair of vibrating arms (see, for example, Patent Documents 1 and 2). When a voltage is applied to the excitation electrodes, the quartz crystal vibrating piece vibrates at a predetermined resonant frequency, with each of the pair of vibrating arms vibrating toward or away from each other from their base ends (the portions connected to the base).

[0004] Conventionally, as for the excitation electrode provided on the surface of a quartz crystal blank in a quartz crystal vibrating piece, as in Patent Documents 1 and 2, a contact layer placed between the quartz crystal blank and the excitation electrode is made of chromium, nickel, or titanium, which has excellent adhesion as a base, and a main layer on top of that is made of chemically stable gold or silver. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2018-129729 [Patent Document 2] Japanese Patent Application Laid-Open No. 2003-017975 Summary of the Invention [Problem to be solved by the invention]

[0006] On the other hand, gold and silver, which have traditionally been used as the main layer of excitation electrodes, are very expensive metal materials, which has the problem of significantly affecting the cost of quartz crystal resonators and various devices using them, such as quartz crystal resonators.

[0007] Furthermore, metals such as chromium, nickel, and titanium that have traditionally been used in the contact layer of excitation electrodes have the problem that, when aged due to the effects of heat in the usage environment, they undergo alloying with the gold or silver that constitutes the main layer, causing a change in the frequency of the vibrator. This thermal effect tends to be particularly pronounced as the quartz crystal resonator element becomes smaller, which has been an obstacle to achieving further miniaturization of quartz crystal resonator elements and various devices, which is in line with market demand.

[0008] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide an excitation electrode, a quartz crystal vibrating piece, a quartz crystal resonator, a sensor, an oscillator, and a method for manufacturing a quartz crystal vibrating piece that can reliably suppress frequency fluctuations without being affected by heat during processing or in the usage environment, can be miniaturized, and is low-cost and has excellent productivity. [Means for solving the problem]

[0009] In order to solve the above problems, the excitation electrode, quartz crystal vibrating piece, quartz crystal resonator, sensor, oscillator, and method of manufacturing the quartz crystal vibrating piece according to the present disclosure employ the following configuration.

[0010] [1] A quartz crystal vibrating piece according to one aspect of the present disclosure includes a quartz crystal blank having a pair of vibrating arms, an electrode film disposed on the outer surface of the quartz crystal blank, and A quartz crystal resonator element havingThe electrode film is arranged on the outer surface of the pair of vibrating arms and has a pair of excitation electrodes that apply an electric field to the quartz blank to excite the quartz blank, and the excitation electrodes have a single-layer structure made of a two-dimensional layered material and are arranged in pairs facing each other across the quartz blank, making this a quartz vibrating piece.

[0011] According to this aspect, the excitation electrode has a single-layer structure made of a thermally and chemically stable two-dimensional layered material. Therefore, even if the excitation electrode is subjected to heat during manufacturing, such as high-temperature reflow, or heat in the usage environment, alloying due to metal diffusion or the like does not occur. Therefore, it is possible to prevent frequency fluctuations in a quartz crystal vibrating piece using this excitation electrode. Furthermore, by using a thermally and chemically stable two-dimensional layered material for the excitation electrode, improved aging resistance is also expected. Furthermore, by constructing the entire excitation electrode as a single-layer structure made of an inexpensive two-dimensional layered material, excellent productivity can be achieved and costs can be reduced. Furthermore, by using a single-layer structure made of a two-dimensional layered material, the thickness can be reduced, which makes it possible to miniaturize quartz crystal vibrating pieces using the excitation electrode and quartz crystal resonators using the same, and also provides excellent impact resistance. Furthermore, since the excitation electrode has a single-layer structure, there is no need for interlayer bonding, as is the case with multi-layer electrodes, and therefore the generation of harmful gases, etc. can be prevented. Furthermore, since the crystal structure of the quartz crystal and the two-dimensional layered material layer are similar, the adhesion of the excitation electrode to the quartz crystal blank is good, resulting in excellent electrical characteristics and mechanical strength characteristics. Furthermore, it is possible to reduce the size of the entire crystal resonator element, and it is also possible to reduce the size of a crystal resonator or the like that uses this crystal resonator element.

[0012] [2] The above [1] aspect crystal vibrating piece In the above, the two-dimensional layered material is preferably a single layer or multiple layer film of graphene containing carbon atoms as a main element.

[0013] This embodiment crystal vibrating pieceAccording to the above, the two-dimensional layered material is composed of a single layer or multiple layer of graphene, which is a sheet-like material having a hexagonal lattice structure made up of carbon atoms and their bonds. This reliably prevents frequency fluctuations as described above, while further improving the adhesion of the excitation electrode to the quartz crystal blank, resulting in superior electrical properties and mechanical strength properties.

[0014] [3] The above [1] aspect crystal vibrating piece In the above, the two-dimensional layered material may be any one of silicene, germanene, stanene, and plumbene.

[0015] This embodiment crystal vibrating piece According to the publication, by using silicene, germanene, stanene, or plumbene, in which the carbon atoms in graphene are replaced with any of silicon, germanium, tin, and lead, as a two-dimensional layered material, it is possible to reliably prevent frequency fluctuations, as in the case of using graphene, while further improving the adhesion of the excitation electrode to the quartz crystal blank, resulting in excellent electrical properties and mechanical strength characteristics.

[0016] [4] Any of the above [1] to [3] aspects crystal vibrating piece In the above, the two-dimensional layered material is preferably doped with an impurity made of a Group 13 element or a Group 15 element.

[0017] This embodiment crystal vibrating piece According to the document, the two-dimensional layered material constituting the excitation electrode is doped with an impurity consisting of a group 13 element or a group 15 element, thereby forming a film with improved electrical conductivity, which can reliably prevent frequency fluctuations and has excellent electrical properties.

[0018] [5] The above [4] aspect crystal vibrating piece In the above, the impurity is more preferably phosphorus or nitrogen.

[0019] This embodiment crystal vibrating pieceAccording to the method, the two-dimensional layered material constituting the excitation electrode is doped with phosphorus or nitrogen as an impurity, thereby forming a film with further improved electrical conductivity, which can reliably prevent frequency fluctuations and obtain very excellent electrical characteristics.

[0020] [6] Any of the above [1] to [5] aspects crystal vibrating piece In the above, the two-dimensional layered material may have a honeycomb structure having electrical conductivity.

[0021] This embodiment crystal vibrating piece According to the publication, the two-dimensional layered material has a conductive honeycomb structure, which further stabilizes the thermal, chemical, and electrical properties of the two-dimensional layered material, and also improves mechanical properties such as expansion and contraction. This reliably prevents frequency fluctuations and further improves the adhesion of the excitation electrode to the quartz crystal blank, resulting in excellent electrical properties and mechanical strength.

[0022] [7] Any of the above [1] to [5] aspects crystal vibrating piece In the above, the two-dimensional layered material may have a mille-feuille structure having electrical conductivity.

[0023] This embodiment crystal vibrating piece According to the method described above, the two-dimensional layered material has a conductive mille-feuille structure, which further stabilizes the thermal, chemical, and electrical properties of the two-dimensional layered material. This effectively prevents frequency fluctuations and further improves the adhesion of the excitation electrode to the quartz crystal blank, resulting in excellent electrical and mechanical properties.

[0024] [8] In the case of the above [6] or [7] crystal vibrating piece In the above, the two-dimensional layered material may be a material exhibiting a band gap structure of a metal or a semimetal.

[0025] This embodiment crystal vibrating pieceAccording to the paper, when the two-dimensional layered material is made of a material exhibiting a metal or semimetal band gap structure, the electrical conductivity of the two-dimensional layered material is improved, thereby reducing the threshold voltage, thereby reliably preventing frequency fluctuations and achieving very good electrical properties.

[0028]

[10] A quartz crystal resonator according to one aspect of the present disclosure is a quartz crystal resonator comprising the quartz crystal resonator element according to aspect [9] above, and a package that hermetically seals the quartz crystal resonator element.

[0029] According to this aspect, the quartz crystal resonator includes a quartz crystal resonator piece having the excitation electrodes according to the present disclosure, so similarly to the above, alloying of the excitation electrodes due to thermal influences does not occur, frequency fluctuations can be prevented, the electrical characteristics are excellent, and the overall size of the quartz crystal resonator can be reduced.

[0030]

[11] A sensor according to one aspect of the present disclosure is a sensor characterized by using the quartz crystal resonator according to the aspect

[10] above.

[0031] According to this aspect, the sensor is provided with the quartz crystal resonator according to the present disclosure, so similarly to the above, alloying of the excitation electrodes due to thermal effects on the quartz crystal resonator element does not occur, frequency fluctuations can be prevented, the electrical characteristics are excellent, and the overall sensor can be made smaller.

[0032]

[12] An oscillator according to one aspect of the present disclosure is an oscillator comprising the quartz crystal resonator according to aspect

[10] above, wherein the quartz crystal resonator is electrically connected to an integrated circuit as an oscillator.

[0033] According to this aspect, since the oscillator is equipped with the quartz crystal resonator according to the present disclosure, similarly to the above, alloying of the excitation electrodes due to thermal effects on the quartz crystal resonator element does not occur, frequency fluctuations can be prevented, and the oscillator has excellent electrical characteristics.

[0034]

[13] A method for manufacturing a quartz crystal vibrating piece according to one embodiment of the present disclosure is characterized by comprising an electrode film formation process including: an electrode film formation process for forming a single-layer electrode film made of a two-dimensional layered material on the outer surface of a quartz crystal blank having a pair of vibrating arms; and a patterning process for patterning the electrode film to form a pair of excitation electrodes arranged opposite each other via the quartz crystal blank on the outer surface of each of the pair of vibrating arms.

[0035] According to this aspect, the electrode film deposition process involves depositing a single-layer electrode film made of a two-dimensional layered material on the outer surface of the crystal blank, and then patterning the electrode film to form a pair of excitation electrodes arranged opposite each other across the crystal blank. This simplifies the electrode film deposition process and shortens the process time. Therefore, frequency fluctuations can be reliably suppressed without being affected by heat during the process or in the usage environment, as described above, and small crystal vibrating pieces can be manufactured at low cost and with high productivity.

[0036]

[14] In the method for manufacturing a quartz crystal vibrating piece according to the aspect

[13] above, it is preferable that the electrode film deposition process employs a method of depositing the electrode film on the outer surface of the quartz crystal blank by chemical vapor deposition (CVD) or atomic layer deposition (ALD).

[0037] According to this embodiment of the method for manufacturing a quartz crystal vibrating piece, in the electrode film formation process, a single-layer electrode film made of a two-dimensional layered material is formed on the outer surface of the quartz crystal blank using a CVD method or an ALD method, thereby making it possible to form an electrode film with excellent electrical properties, adhesion to the quartz crystal blank, and mechanical strength properties at low cost and with good productivity.

[0038]

[15] In the method for manufacturing a quartz crystal vibrating piece according to the above aspect

[13] or

[14] , the electrode film forming step preferably forms the electrode film using graphene, which is mainly composed of carbon atoms, as the two-dimensional layered material, and the patterning step preferably employs a method of forming a resist on the electrode film by photolithography, and then removing at least a portion of the electrode film by plasma ashing, thereby patterning the electrode film.

[0039] According to the manufacturing method of the quartz crystal resonator element of this embodiment, the electrode film is formed using graphene in the electrode film formation process, and then a resist is formed by photolithography in the patterning process. Then, a portion of the electrode film is removed by plasma ashing to perform patterning. By controlling ashing conditions such as ashing time, it is possible to selectively remove a portion of the electrode film that is thinner than the resist with high precision. This allows excitation electrodes with high dimensional precision to be formed at low cost and with good productivity. [Effects of the Invention]

[0040] According to the present disclosure, by providing the above configuration, it is possible to reliably suppress frequency fluctuations without being affected by heat during the process or in the usage environment, and to achieve miniaturization, and it is also possible to provide an excitation electrode, a quartz crystal vibrating piece, a quartz crystal resonator, a sensor, an oscillator, and a method for manufacturing a quartz crystal vibrating piece that are low-cost and highly productive. [Brief explanation of the drawings]

[0041] [Figure 1] 1 is a plan view illustrating a schematic diagram of an oscillator including a quartz crystal resonator having a quartz crystal resonator element to which an excitation electrode according to an embodiment of the present disclosure is applied; [Figure 2] 1 is a perspective view illustrating a crystal resonator including a crystal resonator element to which an excitation electrode according to an embodiment of the present disclosure is applied; [Figure 3] 3 is a diagram for schematically explaining the quartz crystal resonator according to the embodiment of the present disclosure, and is a plan view showing the quartz crystal resonator shown in FIG. 2 with the sealing plate removed. FIG. [Figure 4] 4 is a diagram for schematically explaining a quartz crystal resonator according to an embodiment of the present disclosure, and is a cross-sectional view taken along line IV-IV in FIG. 3. FIG. [Figure 5] FIG. 3 is a diagram for schematically explaining a quartz crystal resonator according to an embodiment of the present disclosure, and is an exploded perspective view of the quartz crystal resonator shown in FIG. 2. [Figure 6] 1 is a plan view schematically illustrating a quartz crystal vibrating piece to which an excitation electrode according to an embodiment of the present disclosure is applied. [Figure 7] 7 is a cross-sectional view taken along line VII-VII in FIG. 6, schematically illustrating a quartz crystal vibrating piece to which an excitation electrode according to an embodiment of the present disclosure is applied. FIG. [Figure 8] 8 is a cross-sectional view taken along line VIII-VIII in FIG. 6, schematically illustrating a quartz crystal vibrating piece to which an excitation electrode according to an embodiment of the present disclosure is applied. FIG. [Figure 9] 1 is a flowchart illustrating each step of a method for manufacturing a quartz crystal vibrating piece according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0042] Hereinafter, embodiments of the excitation electrode, quartz crystal vibrating piece, quartz crystal resonator, sensor, oscillator, and method of manufacturing the quartz crystal vibrating piece of the present disclosure will be described, with appropriate reference to Figures 1 to 9. Note that the drawings used in the following description may show enlarged, characteristic portions for the sake of clarity in order to make the features of the excitation electrode, quartz crystal vibrating piece, quartz crystal resonator, sensor, and oscillator of the present disclosure easier to understand, and the dimensional ratios of each component may differ from the actual ones. Furthermore, the materials, dimensions, etc. exemplified in the following description are merely examples, and the present disclosure is not limited thereto. Appropriate modifications may be made within the scope of the present disclosure.

[0043] FIG. 1 is a plan view schematically illustrating an oscillator including a quartz crystal resonator having a quartz crystal resonator element to which the excitation electrode of this embodiment is applied. FIG. 2 is a perspective view illustrating a quartz crystal resonator having a quartz crystal resonator element to which the excitation electrode of this embodiment is applied. FIG. 3 is a plan view illustrating the quartz crystal resonator shown in FIG. 2 with the sealing plate removed. FIG. 4 is a cross-sectional view taken along line IV-IV of the quartz crystal resonator shown in FIG. 3. FIG. 5 is an exploded perspective view of the quartz crystal resonator shown in FIG. 2. FIG. 6 is a plan view illustrating a quartz crystal resonator element to which the excitation electrode of this embodiment is applied. FIG. 7 is a cross-sectional view taken along line VII-VII of FIG. 6. FIG. 8 is a cross-sectional view taken along line VIII-VIII of FIG. 6. FIG. 9 is a flowchart illustrating each step included in the method for manufacturing a quartz crystal resonator element of this embodiment.

[0044] In the following description, in the excitation electrodes, quartz crystal vibrating pieces, quartz crystal vibrators, sensors, and oscillators of this embodiment, components having the same or similar functions will be given the same symbols, and descriptions of parts common to each of these components may be omitted.

[0045] 6 and other figures, the excitation electrodes of this embodiment are excitation electrodes 41 and 42 that are arranged on the outer surface of the quartz crystal plate 30 and apply an electric field to the quartz crystal plate (quartz crystal blank) 30 to excite the quartz crystal plate 30. The excitation electrodes 41 and 42 of this embodiment have a single-layer structure made of a two-dimensional layered material, and are arranged in pair to face each other across the quartz crystal plate 30.

[0046] <Oscillator> As shown in FIG. 1, the oscillator 100 of this embodiment is generally configured by electrically connecting a quartz crystal resonator 1, which will be described in detail later, to an integrated circuit 103 as an oscillator, the quartz crystal resonator 1 including a quartz crystal resonator piece 3 to which excitation electrodes 41, 42 (see FIG. 6, etc.) of this embodiment are applied.

[0047] Specifically, the oscillator 100 of this embodiment includes a substrate 101, an electronic component 102, an integrated circuit 103, and a crystal unit 1. The electronic component 102 is, for example, a capacitor, and is mounted on the substrate 101 . The integrated circuit 103 is, for example, a semiconductor circuit for an oscillator, and is mounted on the substrate 101. The integrated circuit 103 is electrically connected to the crystal resonator 1 and the electronic component 102 via wiring not shown. As described above, the quartz crystal resonator 1 includes a quartz crystal resonator piece 3 to which the excitation electrodes 41 and 42 of this embodiment are applied, and is mounted, for example, near an integrated circuit 103 on a substrate 101, and functions as an oscillator in the oscillator 100 of this embodiment. The excitation electrodes 41 and 42, the quartz crystal vibrating piece 3, and the quartz crystal vibrator 1 of this embodiment will be described in detail later. At least a portion of the oscillator 100 of this embodiment may be molded with a resin (not shown) as appropriate.

[0048] In the oscillator 100, when power is supplied to the crystal unit 1, the crystal vibrating piece 3 (see FIGS. 3 and 5) of the crystal unit 1 vibrates. The vibration of the crystal unit 3 is converted into an electrical signal by the piezoelectric properties of the crystal unit 3. This electrical signal is output from the crystal unit 1 to the integrated circuit 103. The integrated circuit 103 performs various processes on the electrical signal output from the crystal unit 1 to generate a frequency signal.

[0049] The oscillator 100 can be applied to, for example, a single-function oscillator for a clock, a timing control device that controls the operation timing of various devices such as a computer, or a device that provides time or a calendar. The integrated circuit 103 is configured in accordance with the functions required of the oscillator 100, and may include a so-called RTC (real-time clock) module.

[0050] The oscillator 100 of this embodiment is equipped with a quartz crystal resonator 1 including a quartz crystal vibrating piece 3 to which the excitation electrodes 41, 42 of this embodiment are applied, as will be described in detail later. Therefore, alloying of the excitation electrodes 41, 42 (see FIG. 6) due to thermal effects on the quartz crystal vibrating piece 3 does not occur, frequency fluctuations can be prevented, and the oscillator 100 has excellent electrical characteristics.

[0051] <Crystal unit (including a crystal resonator element with an excitation electrode)> 2 to 5, the crystal resonator 1 of this embodiment is a so-called ceramic package type surface mount type resonator. The crystal resonator 1 is generally configured with a package 2 having an airtightly sealed cavity C therein, and a crystal resonator piece 3 housed in the cavity C. The crystal resonator 1 in the illustrated example has a generally rectangular parallelepiped outer shape. In this embodiment, in a plan view, the longitudinal direction of the quartz crystal resonator 1 is referred to as the longitudinal direction L, the lateral direction is referred to as the width direction W, and the direction perpendicular to the longitudinal direction L and the width direction W is referred to as the thickness direction T.

[0052] The package 2 has a package body 5 and a sealing plate 6 that is joined to the package body 5 and forms a cavity C between the package body 5 and the sealing plate 6. The package body 5 has a first base substrate 10 and a second base substrate 11 that are bonded together in a stacked state, and a seal ring 12 that is bonded onto the second base substrate 11.

[0053] The first base substrate 10 is a ceramic substrate having a rectangular shape in a plan view seen in the thickness direction T. The upper surface of the first base substrate 10 forms the bottom of the cavity C. A pair of external electrodes 21A, 21B are formed on the lower surface of the first base substrate 10 with a gap therebetween in the longitudinal direction L. The external electrodes 21A, 21B are formed, for example, from a single-layer film made of a single metal formed by vapor deposition, sputtering, or the like, or from a laminated film in which different metals are laminated.

[0054] The second base substrate 11 is a ceramic substrate having the same outer shape as the first base substrate 10 in a plan view, and is bonded integrally to the first base substrate 10 by a method such as sintering while being stacked on top of the first base substrate 10. Here, examples of ceramic materials that can be used for each of first and second base substrates 10 and 11 include alumina-made high temperature co-fired ceramic (HTCC) and glass ceramic-made low temperature co-fired ceramic (LTCC).

[0055] As shown in FIGS. 3 to 5, the second base substrate 11 has a through portion 11a formed therein that penetrates the second base substrate 11 in the thickness direction T. The through portion 11a has a rounded rectangular shape in a plan view. Mounting portions 14A and 14B that protrude inward in the width direction W are formed individually on the inner surface of the through portion 11a at portions located on both sides in the width direction W. The mounting portions 14A and 14B are located in the center of the second base substrate 11 in the longitudinal direction L.

[0056] A pair of electrode pads 20A, 20B are formed on the mounting portions 14A, 14B as connection electrodes with the quartz crystal vibrating piece 3. Like the external electrodes 21A, 21B described above, the electrode pads 20A, 20B are composed of a single-layer film made of a single metal formed by vapor deposition, sputtering, or the like, or a laminated film made of different metals. The electrode pads 20A, 20B and the external electrodes 21A, 21B are electrically connected to each other via through-wirings (not shown) that penetrate each of the first base substrate 10 and the second base substrate 11 in the thickness direction T.

[0057] At the four corners of each of the first and second base substrates 10 and 11, cutout portions 15 having a quarter-circular arc shape in a plan view are formed over the entire thickness direction T of the first and second base substrates 10 and 11. The first and second base substrates 10 and 11 are fabricated, for example, by stacking and bonding two wafer-like ceramic substrates, forming a plurality of through-holes penetrating both ceramic substrates in a matrix pattern, and cutting both ceramic substrates into a grid pattern using each through-hole as a reference. At this time, the through-holes are divided into four, thereby forming the above-mentioned cutout portions 15.

[0058] The seal ring 12 is a conductive frame-shaped member that is slightly smaller than the outer shapes of the first and second base substrates 10 and 11, and is bonded to the upper surface of the second base substrate 11. Specifically, the seal ring 12 is bonded to the second base substrate 11 by baking with a brazing material such as silver brazing or a solder material, or by welding to a metal bonding layer formed on the second base substrate 11. The seal ring 12, together with the inner surface of the second base substrate 11 (the through portion 11a), constitutes the side wall of the cavity C. In the illustrated example, the inner surface of the seal ring 12 is disposed flush with the inner surface of the second base substrate 11.

[0059] The material of the seal ring 12 may be, for example, a nickel-based alloy, and more specifically, may be appropriately selected from the group consisting of Kovar, Elinvar, Invar, 42-alloy, etc. In particular, it is preferable to select a material for the seal ring 12 that has a thermal expansion coefficient close to that of the first and second base substrates 10 and 11, which are made of ceramic. For example, if the first and second base substrates 10 and 11 have a thermal expansion coefficient of 6.8×10 -6 When alumina with a thermal expansion coefficient of 5.2×10 / °C is used, the seal ring 12 has a thermal expansion coefficient of 5.2×10 -6 / ℃ Kovar and thermal expansion coefficient 4.5~6.5×10 -6 It is preferable to use 42-alloy with a temperature of 1000 K / °C.

[0060] The sealing plate 6 is made of a conductive substrate and is joined onto the seal ring 12 to airtightly seal the inside of the package body 5. The space defined by the seal ring 12, the sealing plate 6, and the first and second base substrates 10 and 11 is a hermetically sealed cavity C.

[0061] The quartz crystal vibrating piece 3 is housed in a cavity C of a hermetically sealed package 2. The quartz crystal vibrating piece 3 includes a quartz crystal plate 30 made of quartz crystal. The quartz crystal plate 30 has a pair of vibrating arms 31 and 32 and a pair of supporting arms 33 and 34. The quartz crystal vibrating piece 3 is mounted in the package 2 by supporting the support arms 33, 34 on the mounting portions 14A, 14B of the package 2 with a conductive adhesive (not shown) within the cavity C. This allows the quartz crystal vibrating piece 3 to be supported in the cavity C with the vibrating arms 31, 32 floating above the base substrates 10, 11. Two systems of excitation electrodes 41, 42 (see FIG. 6) are arranged on the outer surfaces of the vibrating arms 31, 32, which vibrate the pair of vibrating arms 31, 32 when a predetermined voltage is applied.

[0062] To operate the quartz crystal resonator 1, first, a predetermined voltage is applied to the external electrodes 21A and 21B (see FIG. 2). This causes a current to flow through the excitation electrodes 41 and 42, generating an electric field between them. Due to the inverse piezoelectric effect caused by the electric field generated between the excitation electrodes 41 and 42, each of the pair of vibrating arms 31 and 32 vibrates at a predetermined resonant frequency, for example, in a direction in which they approach or move away from each other (width direction W). The vibration of each of the vibrating arms 31 and 32 can be used as a time source, a timing source for a control signal, a reference signal source, or the like.

[0063] The quartz crystal resonator 1 of this embodiment includes a quartz crystal resonator element 3 to which the excitation electrodes 41, 42 of this embodiment are applied, as will be described in detail later. Therefore, alloying of the excitation electrodes 41, 42 (see FIG. 6) due to thermal effects on the quartz crystal resonator element 3 does not occur, frequency fluctuations can be prevented, the electrical characteristics are excellent, and the entire quartz crystal resonator 1 can be made smaller.

[0064] [Crystal vibrating piece (including excitation electrode)] The quartz crystal vibrating piece 3 including the excitation electrodes 41 and 42 of this embodiment, which constitutes the quartz crystal vibrator 1 of this embodiment described above, will be described in detail below. As shown in FIG. 6, the quartz crystal vibrating piece 3 of this embodiment includes a quartz crystal plate 30 and an electrode film 40 disposed on the outer surfaces of the quartz crystal plate 30, including the front and back surfaces. The longitudinal direction, width direction, and thickness direction of the quartz crystal vibrating piece 3 of this embodiment coincide with the longitudinal direction L, width direction W, and thickness direction T of the quartz crystal resonator 1 of this embodiment described above. Therefore, in the following description of the quartz crystal vibrating piece 3, the longitudinal direction L, width direction W, and thickness direction T of the quartz crystal resonator 1 will be used in detail, as above.

[0065] (crystal plate) The quartz plate 30 includes a base 35, a pair of vibrating arms 31, 32 (first vibrating arm 31 and second vibrating arm 32) extending from the base 35 in the longitudinal direction L, and a pair of support arms 33, 34 (first support arm 33 and second support arm 34) located on either side of the base 35 in the width direction W. The quartz plate 30 is formed so that its planar shape, as viewed in the thickness direction T, is approximately symmetrical with respect to a central axis O along the longitudinal direction L.

[0066] The first vibrating arm 31 and the second vibrating arm 32 are arranged parallel to each other in the width direction W. The first and second vibrating arms 31 and 32 each have a base end on the base portion 35 side as a fixed end and a tip end as a free end, and vibrate in a direction in which they move toward and away from each other (the width direction W). The first and second vibrating arms 31 and 32 each have a main body 36 extending from the base end of each of the first and second vibrating arms 31 and 32 toward the tip, and a weight 38 located at the tip of each of the first and second vibrating arms 31 and 32.

[0067] 6 and 7, grooves 37 are formed in the main body 36. The grooves 37 are recessed in the thickness direction T on both main surfaces of the main body 36 and extend along the longitudinal direction L. The grooves 37 are formed from near the base ends of the first and second vibrating arms 31 and 32 to near the tip ends of the main body 36.

[0068] 6, the weights 38 each extend in the longitudinal direction L from the tip of the main body 36. The weights 38 are rectangular in plan view and are wider in the width direction W than the main body 36. This makes it possible to increase the mass of the tip of each of the first and second vibrating arms 31 and 32 and the moment of inertia during vibration, and allows the lengths of the first and second vibrating arms 31 and 32 to be shorter than in a quartz crystal vibrating piece that does not have the weights 38.

[0069] The first and second support arms 33 and 34 are each configured in an L-shape in a plan view, and are arranged to surround the base 35 and the first and second vibrating arms 31 and 32 (main body 36) from the outside in the width direction W. Specifically, the first and second support arms 33 and 34 are each provided to protrude outward in the width direction W from both end surfaces of the base 35 in the width direction W, and then extend parallel to the first and second vibrating arms 31 and 32 along the longitudinal direction L. Here, the first support arm 33 is arranged on the same side as the first vibrating arm 31 with respect to the central axis O. Furthermore, the second support arm 34 is arranged on the same side as the second vibrating arm 32 with respect to the central axis O.

[0070] (Electrode film: Electrode film including excitation electrodes) The electrode film 40 is composed of excitation electrodes 41 and 42, mount electrodes 43 and 44, and connection wiring 45.

[0071] The excitation electrodes 41, 42 are provided in two systems on the outer surface of the main body 36 of the vibrating arms 31, 32. The excitation electrodes 41, 42 are patterned on the outer surface of the main body 36 so as to be electrically insulated from each other. The excitation electrodes 41, 42 of this embodiment are composed of a first excitation electrode 41 and a second excitation electrode 42. Of these, the first excitation electrode 41 is formed on both side surfaces facing the width direction W of the main body 36 of the first vibrating arm 31 and on the grooves 37 of the second vibrating arm 32. In addition, the second excitation electrodes 42 are formed on the grooves 37 of the first vibrating arm 31 and on both side surfaces of the main body 36 of the second vibrating arm 32. These excitation electrodes 41 and 42 vibrate each of the first and second vibrating arms 31 and 32 in the width direction W when a predetermined drive voltage is applied between the excitation electrodes 41 and 42. In this embodiment, the first excitation electrode 41 and the second excitation electrode 42 may be simply referred to as excitation electrodes 41, 42 for convenience of explanation.

[0072] The mount electrodes 43, 44 are provided as mount portions when the quartz crystal vibrating piece 3 is mounted in the package 2. The mount electrodes 43, 44 are provided on the main surfaces (rear surfaces) at the tips of the first and second support arms 33, 34, respectively. Specifically, the mount electrodes 43, 44 are composed of a first mount electrode 43 arranged on the first support arm 33 and a second mount electrode 44 arranged on the second support arm 34. Of these, the first mount electrode 43 is electrically connected to the first excitation electrode 41. Furthermore, the second mount electrode 44 is electrically connected to the second excitation electrode 42. These mount electrodes 43, 44 are electrically connected to the electrode pads 20A, 20B of the package 2 via a conductive adhesive.

[0073] The connection wiring 45A and 45B connect the excitation electrodes 41 and 42 to each other on the tip side of each of the first and second vibrating arms 31 and 32. The connection wiring 45 is composed of a first connection wiring 45A connected to the first excitation electrode 41 and a second connection wiring 45B connected to the second excitation electrode 42. Of these, the first connection wiring 45A electrically connects the first excitation electrodes 41 on both side surfaces of the first vibrating arm 31 to each other. In addition, the second connection wiring 45B electrically connects the second excitation electrodes 42 on both side surfaces of the second vibrating arm 32 to each other. Since the first connection wiring 45A and the second connection wiring 45B are formed with similar shapes and sizes, in the following description, when there is no need to distinguish between the first connection wiring 45A and the second connection wiring 45B, they will simply be referred to as connection wiring 45.

[0074] Each connection wiring 45 has a side portion 46, a front portion 47, and a back portion 48. The side portion 46 is disposed on the entire end surface of each of the first and second vibrating arms 31, 32, closer to the tip than the groove portion 37 of each of the first and second vibrating arms 31, 32. The end surface is a surface connecting the main surfaces and includes a tip surface facing the longitudinal direction L and a side surface facing the width direction W. The front portion 47 is disposed on the surface 64 of each of the first and second vibrating arms 31, 32, closer to the tip than the groove portion 37 of each of the first and second vibrating arms 31, 32. The front portion 47 is disposed so as to be spaced apart from the excitation electrodes 41, 42 in the longitudinal direction L. The front portion 47 extends across the boundary between the main body portion 36 and the weight portion 38 of each of the first and second vibrating arms 31, 32. Furthermore, a side edge of the front portion 47 is connected to the side portion 46. The back portion 48 is disposed on the back surface 63 of each of the first and second vibrating arms 31, 32, closer to the tip end than the groove portion 37 of the first and second vibrating arms 31, 32. The back portion 48 is disposed so as to be spaced apart from the excitation electrodes 41, 42 in the longitudinal direction L. The back portion 48 also extends so as to straddle the boundary between the main body portion 36 and the weight portion 38 of the first and second vibrating arms 31, 32. Furthermore, a side edge of the back portion 48 is connected to the side portion 46.

[0075] 6 and 8, the back portion 48 of each connection wiring 45 is arranged so as to cover the entire back surface 63 of the first and second vibrating arm portions 31 and 32. In the illustrated example, the back portion 48 is formed so as to cover the tip edge 63t of the back surface 63 of the first and second vibrating arm portions 31 and 32, as well as a pair of side edges 63s extending from the tip edge 63t to the base end sides of the first and second vibrating arm portions 31 and 32.

[0076] The front portion 47 of the connection wiring 45 is arranged so as to cover the entire surface 64 of the first and second vibrating arms 31 and 32. In the illustrated example, the front portion 47 is formed so as to cover the tip edge 64t of the surface 64 of the first and second vibrating arms 31 and 32, as well as a pair of side edges 64s extending from the tip edge 64t to the base end sides of the first and second vibrating arms 31 and 32.

[0077] Although detailed illustrations are omitted in Figures 6 and 8, the back portion 48 and the front portion 47 of the connection wiring 45 are spaced apart to prevent electrical short-circuiting by providing a slight gap near the tip edge 63t or the tip edge 64t.

[0078] Next, as described above, the excitation electrodes 41 and 42 of this embodiment have a single-layer structure made of a two-dimensional layered material, and are used by being arranged in pairs so as to face each other via the quartz crystal plate 30. That is, the excitation electrodes 41 and 42 of this embodiment have a structure consisting only of a main layer made of a two-dimensional layered material. Furthermore, the "two-dimensional layered material" described in this embodiment refers to a material that has a two-dimensional structure at the atomic level.

[0079] As described above, the excitation electrodes 41 and 42 of this embodiment are used by sandwiching the quartz crystal plate 30 between the pair of excitation electrodes 41 and 42, thereby forming a quartz crystal vibrating piece used in a so-called AT vibrator.

[0080] As described above, the excitation electrodes 41, 42 are single-layer excitation electrodes made of a thermally and chemically stable two-dimensional layered material. Therefore, even if they are subjected to thermal influences during manufacturing, such as high-temperature reflow, or in the usage environment (including exposure to high-temperature environments), alloying due to metal diffusion or the like, as occurs in conventional excitation electrodes with a multi-layer structure, is not generated. This has the effect of preventing frequency fluctuations in the quartz crystal vibrating piece 3 using these excitation electrodes 41, 42. Furthermore, the use of a thermally and chemically stable two-dimensional layered material for the excitation electrodes 41, 42 is expected to improve aging resistance.

[0081] Furthermore, by constructing the entire excitation electrodes 41, 42 as a single-layer structure made of an inexpensive two-dimensional layered material without using expensive precious metals, excellent productivity can be achieved and costs can be reduced. Furthermore, by making the excitation electrodes 41, 42 a single-layer structure made of a two-dimensional layered material, the thickness can be reduced, which makes it possible to miniaturize the quartz crystal vibrating piece 3 using the excitation electrodes 41, 42 and the quartz crystal resonator 1 using this quartz crystal vibrating piece 3, and also to provide excellent impact resistance. Furthermore, since the excitation electrodes 41, 42 have a single-layer structure, there is no need for interlayer bonding, as is the case with multi-layer electrodes, which prevents the generation of harmful gases and enables a safe manufacturing process.

[0082] Furthermore, since the crystal structures of quartz crystal and the two-dimensional layered material layer are similar, the excitation electrodes 41 and 42 adhere well to the quartz crystal plate 30, further improving the electrical and mechanical strength characteristics of the resulting quartz crystal vibrating piece 3.

[0083] The excitation electrodes 41 and 42 of this embodiment may be made of a thermally and chemically stable two-dimensional layered material, such as a single-layer or multi-layer film of graphene, which is primarily composed of carbon atoms. Graphene is a sheet-like material with a hexagonal lattice structure composed of carbon atoms and their bonds. That is, the excitation electrodes 41 and 42 of this embodiment have a single-layer structure made of a two-dimensional layered material that does not include a metal film such as a contact layer, and the two-dimensional layered material itself can be a single-layer or multi-layer film of graphene as described above.

[0084] In this way, the two-dimensional layered material constituting the excitation electrodes 41, 42 is made of a single layer or multiple layer of graphene, which reliably prevents frequency fluctuations while further improving the adhesion of the excitation electrodes 41, 42 to the quartz plate 30, resulting in superior electrical properties and mechanical strength properties.

[0085] Furthermore, the two-dimensional layered material forming the excitation electrodes 41 and 42 is not limited to the above-mentioned graphene, and for example, any one of silicene, germanene, stanene, and plumbene can also be used. Among these, silicene is a graphene-like substance having a lattice-like crystal structure in which the carbon atoms of the above-mentioned graphene are replaced with silicon elements. Germanene is a graphene-like substance having a lattice-like crystal structure in which the carbon atoms of the above-mentioned graphene are replaced with germanium elements. Stanene is a graphene-like substance having a lattice crystal structure in which the carbon atoms of the above-mentioned graphene are replaced with tin elements. Plumbene is a graphene-like material having a lattice crystal structure in which the carbon atoms of the above-mentioned graphene are replaced with lead elements.

[0086] In this embodiment, the two-dimensional layered material constituting the excitation electrodes 41, 42 is one of the graphene-like materials, silicene, germanene, stanene, or plumbene, as described above. This provides thermal and chemical stability, similar to the case of graphene, thereby reliably preventing frequency fluctuations. Furthermore, similar to the case of graphene being used as the two-dimensional layered material, the adhesion of the excitation electrodes 41, 42 to the quartz crystal plate 30 is further improved, resulting in superior electrical and mechanical strength characteristics.

[0087] Furthermore, the two-dimensional layered material constituting the excitation electrodes 41, 42 is preferably doped with an impurity consisting of a Group 13 element or a Group 15 element adjacent to the Group 14 element. By doping the two-dimensional layered material constituting the excitation electrodes 41, 42 with the above-mentioned elements as impurities, the film becomes one with improved electrical conductivity. This reliably prevents frequency fluctuations and further improves electrical characteristics. Examples of the Group 13 element or Group 15 element to be doped into the two-dimensional layered material constituting the excitation electrodes 41 and 42 include phosphorus (P) and nitrogen (N). In particular, when graphene is used as the two-dimensional layered material, it is more preferable to dope the two-dimensional layered material with nitrogen, which is located next to carbon (C) on the periodic table, into the two-dimensional layered material, since carbon can be easily substituted for nitrogen.

[0088] The structure of the two-dimensional layered material constituting the excitation electrodes 41, 42 is not particularly limited, but may be, for example, a material having a conductive honeycomb structure, such as the above-mentioned graphene. The honeycomb structure described in this embodiment refers to a structure in which, for example, regular hexagons or regular hexagonal prisms are arranged without gaps, and is a structure that can reduce the material required to form the film without losing strength.

[0089] In this way, the two-dimensional layered material that makes up the excitation electrodes 41, 42 has a conductive honeycomb structure, which further stabilizes the thermal, chemical, and electrical properties of the two-dimensional layered material, and also improves mechanical properties such as expansion and contraction. This reliably prevents frequency fluctuations while further improving the adhesion of the excitation electrodes 41, 42 to the quartz plate 30, thereby further improving the electrical properties and mechanical strength properties.

[0090] Furthermore, the structure of the two-dimensional layered material constituting the excitation electrodes 41, 42 is not limited to the above-described honeycomb structure, and may be, for example, a conductive mille-feuille structure. The mille-feuille structure described in this embodiment refers to a layered structure made up of, for example, a hard layer in which atoms are strongly bonded and a soft layer in which atoms are relatively weakly bonded.

[0091] In this way, even when a conductive mille-feuille structure is used for the two-dimensional layered material constituting the excitation electrodes 41, 42, the thermal, chemical, and electrical properties of the two-dimensional layered material are further stabilized, as in the honeycomb structure described above. This, as described above, reliably prevents frequency fluctuations while further improving the adhesion of the excitation electrodes 41, 42 to the quartz plate 30, thereby further improving the electrical properties and mechanical strength properties.

[0092] Furthermore, in the excitation electrodes 41, 42 of this embodiment, the two-dimensional layered material having the above-described conductive honeycomb structure or mille-feuille structure may be a material exhibiting a metal or semimetal bandgap structure. In this way, when the two-dimensional layered material constituting the excitation electrodes 41, 42 is a material exhibiting a metal or semimetal bandgap structure, the electrical conductivity of the two-dimensional layered material is improved, thereby reducing the threshold voltage. Therefore, as described above, frequency fluctuations can be reliably prevented, and excellent electrical characteristics can be obtained.

[0093] In this embodiment, as long as the excitation electrodes 41 and 42 have a single-layer structure made of a two-dimensional layered material as described above, there are no limitations on the structures or materials of the other electrodes constituting the electrode film 40, i.e., the first and second mount electrodes 43 and 44 and the connection wiring 45. Therefore, for the first and second mount electrodes 43 and 44 and the connection wiring 45, for example, a conventionally known laminated film in which gold (Au) is laminated on a chromium (Cr) base can be used.

[0094] On the other hand, it is more preferable to use a single-layer structure made of a two-dimensional layered material for the first and second mount electrodes 43, 44 and the connecting wiring 45, similar to the excitation electrodes 41, 42, in order to improve the electrical characteristics and mechanical strength characteristics of the entire electrode film 40, and to allow the entire electrode film 40 to be formed in the same process, thereby improving productivity and reducing production costs.

[0095] Furthermore, the excitation electrodes 41 and 42 of this embodiment can be used in various vibrators, such as piezoelectric vibrators, that are disposed inside a vacuum package.

[0096] In this embodiment, an example is given in which excitation electrodes 41, 42 having a single layer structure made of a two-dimensional layered material are applied to a tuning-fork type (side-arm type) quartz crystal vibrating piece 3 as shown in Fig. 6 etc. However, the quartz crystal vibrating pieces to which the excitation electrodes 41, 42 of this embodiment can be applied are not limited to this example. The excitation electrodes 41, 42 of this embodiment can also be applied to quartz crystal vibrating pieces having shapes other than those shown in the illustrated example.

[0097] Furthermore, the vibrators to which the excitation electrodes 41, 42 of this embodiment can be applied are not limited to the quartz vibrating piece 3 using quartz as described above, but can also be applied to piezoelectric vibrating pieces using alumina (AlN) or lead zirconate titanate (PZT), for example.

[0098] <Sensor> By using the quartz crystal resonator 1 including the quartz crystal resonator piece 3 to which the excitation electrodes 41 and 42 of this embodiment are applied as described above, various sensors can be configured. Although not shown, sensors that can be configured using such a quartz crystal resonator 1 include, for example, a pressure sensor, an acceleration sensor, a tilt sensor, a gyro sensor, a temperature sensor, a biosensor, a mass sensor, and a strain sensor.

[0099] As described above, by constructing various sensors using the quartz crystal resonator 1 of this embodiment, alloying of the excitation electrodes 41, 42 due to thermal effects on the quartz crystal resonator piece 3 does not occur, and frequency fluctuations can be prevented, so that excellent electrical characteristics can be obtained and the entire sensor can be made smaller.

[0100] <Manufacturing method of crystal vibrating piece (including manufacturing method of excitation electrode)> A method for manufacturing the quartz crystal vibrating piece 3 having the excitation electrodes 41, 42 of this embodiment will be described below with reference to the flowchart in FIG. 9 as needed, and details of each component will be described with reference to FIGS. 6 to 8 as needed, as described above.

[0101] The method for manufacturing a quartz crystal vibrating piece 3 having excitation electrodes 41, 42 of this embodiment is a method for manufacturing a quartz crystal vibrating piece 3 as shown in FIG. 6, and as shown in the flowchart of FIG. 9, is a method that includes at least an electrode film formation process (S20) that includes the following steps (1) and (2). (1) An electrode film forming step (S21) of forming an electrode film 40 having a single layer structure made of a two-dimensional layered material on the outer surface of a quartz crystal plate 30 having a pair of vibrating arm portions 31, 32. (2) A patterning step (S22) of patterning the electrode film 40 to form a pair of excitation electrodes 41, 42 arranged on the outer surfaces of each of the pair of vibrating arms 31, 32 so as to face each other with the quartz plate 30 interposed therebetween.

[0102] In the manufacturing method of this embodiment, all of the electrodes constituting the electrode film 40, i.e., the mount electrodes 43, 44 and the connection wiring 45, are formed as a single layer structure made of a two-dimensional layered material, similar to the excitation electrodes 41, 42, and a method of simultaneously forming the film in the electrode film formation process (S21) will be described as an example.

[0103] In the manufacturing method of this embodiment, first, an outer shape forming step (S10) is performed. In the outer shape forming step (S10), the quartz crystal wafer is cut out to form a quartz crystal plate 30, which is a quartz crystal blank. In this case, first, a mask having a shape corresponding to the shape of the quartz plate 30 in plan view is formed on the surface of the quartz wafer by photolithography. Next, the quartz wafer is lowered using wet etching to selectively remove the unmasked areas of the quartz wafer, and the quartz wafer is shaped into the planar shape of a quartz plate 30 having first and second vibrating arm portions 31, 32, etc., as shown in Figure 6.

[0104] Next, in the outer shape forming step (S10), grooves 37 are further formed on both main surfaces (front and back surfaces) of the first and second vibrating arm portions 31 and 32. Specifically, first, a mask having a shape corresponding to the shape of the groove 37 is formed on both main surfaces of the quartz crystal wafer using photolithography technology. Next, the quartz crystal wafer is half-etched by wet etching to the extent that the grooves 37 do not penetrate all the way through the wafer, thereby forming the quartz crystal plate 30 having the grooves 37.

[0105] Next, the electrode film forming step (S20) is carried out. In the electrode film formation step (S20), electrode films 40 are arranged on the front and back surfaces of the quartz plate 30. As described above, the electrode film formation step (S20) provided in the manufacturing method of this embodiment includes an electrode film formation step (S21) of forming an electrode film 40 having a single layer structure made of a two-dimensional layered material on the outer surface of the quartz plate 30, and a patterning step (S22) of patterning the electrode film 40 to form a pair of excitation electrodes 41, 42 arranged opposite each other via the quartz plate 30 on the outer surfaces of each of the pair of vibrating arms 31, 32.

[0106] In the electrode film deposition process (S21), a single-layer electrode film 40 made of a two-dimensional layered material is deposited on the front, back, and end faces of the quartz plate 30, for example, by chemical vapor deposition (CVD) or atomic layer deposition (ALD).

[0107] Next, in the patterning process (S22), the electrode film 40 is patterned to form a mask made of a resist material on the outer surface of the quartz plate 30 in a shape corresponding to the outer shapes of the two excitation electrodes 41, 42, the first and second mount electrodes 43, 44, and the first and second connection wirings 45A, 45B. Next, the electrode film 40 is etched to selectively remove the electrode film 40 in areas not masked by the resist, thereby forming the excitation electrodes 41 and 42, the first and second mount electrodes 43 and 44, and the first and second connection wirings 45A and 45B on the outer surface of the quartz crystal plate 30.

[0108] In the manufacturing method of this embodiment, it is more preferable to employ a method in which, in the electrode film formation step (S21), the electrode film 40 is formed using graphene containing carbon as a main element as the two-dimensional layered material, and then, in the patterning step (S22), at least a portion of the electrode film 40 is removed by plasma ashing, thereby patterning the electrode film 40. Plasma ashing is a method in which, for example, oxygen gas converted into plasma by non-ionizing radiation such as visible light is reacted with the object to be removed, thereby vaporizing and removing the object to be removed. In this way, by adopting a method of patterning by removing a portion of the electrode film 40 made of graphene by plasma ashing, it is possible to selectively remove a portion of the electrode film that is thinner than the resist with high precision by controlling ashing conditions such as the ashing time, which makes it possible to form the excitation electrodes 41 and 42 with high dimensional precision at low cost and with good productivity.

[0109] By performing the steps described above, a quartz crystal vibrating piece 3 having excitation electrodes 41 and 42 as shown in FIG. 6 can be obtained.

[0110] According to the manufacturing method of the quartz crystal resonator 1 having the excitation electrodes 41, 42 of this embodiment, as described above, in the electrode film formation step (S21), a single-layer electrode film 40 made of a two-dimensional layered material is formed on the outer surface of the quartz crystal plate 30, and then in the patterning step (S22), the electrode film 40 is patterned to form the pair of excitation electrodes 41, 42 arranged opposite each other across the quartz crystal plate 30. This simplifies the electrode film formation step (S21) and reduces the process time. Therefore, as described above, frequency fluctuations can be reliably suppressed without being affected by heat during the process or in the usage environment, and it becomes possible to manufacture the small quartz crystal resonator piece 3 at low cost and with good productivity.

[0111] Furthermore, according to the manufacturing method of this embodiment, in the electrode film formation process (S21), a single-layer electrode film 40 made of a two-dimensional layered material is formed on the outer surface of the quartz plate 30 by CVD or ALD, making it possible to form an electrode film 40 with excellent electrical properties, adhesion to the quartz plate 30, and mechanical strength properties at low cost and with good productivity.

[0112] Furthermore, according to the manufacturing method of this embodiment, in the electrode film formation step (S21), the electrode film 40 is formed using graphene, and then in the patterning step (S22), a resist is formed by photolithography, and then part of the electrode film 40 made of graphene is removed by plasma ashing for patterning. This makes it possible to form excitation electrodes 41, 42 with high dimensional accuracy at low cost and with good productivity.

[0113] <Other Aspects of the Disclosure> Although the preferred embodiments of the present disclosure have been described in detail above, the present disclosure is not limited to the specific embodiments described above, and various modifications, substitutions, and alterations are possible within the scope of the gist of the present disclosure as set forth in the claims. [Industrial Applicability]

[0114] As described above, the excitation electrode of the present disclosure can reliably suppress frequency fluctuations without being affected by heat during processing or in the usage environment, can be miniaturized, and is low-cost and highly productive. Therefore, a quartz crystal vibrating piece to which the excitation electrode of the present disclosure is applied, a quartz crystal resonator including this quartz crystal vibrating piece, and a sensor and oscillator including this quartz crystal resonator are highly suitable as devices used as a time source, a timing source for control signals, a reference signal source, etc. in electronic devices such as mobile phones and personal digital assistants. [Explanation of symbols]

[0115] 1...Crystal resonator 2. Package 5...Package body 10...First base substrate 21A, 21B...External electrodes (a pair of external electrodes) 11...Second base substrate 12...Seal ring 6...Sealing plate C...cavity 3...Crystal vibrating piece 30...Crystal plate (crystal blank) 31...First vibrating arm (vibrating arm) 32...Second vibrating arm (vibrating arm) 33...First support arm 34…Second support arm 35...Base 36...Main body 37...Groove 38… Weight part 40...electrode film 41...First excitation electrode (excitation electrode) 42...Second excitation electrode (excitation electrode) 43...First mount electrode (mount electrode) 44...Second mount electrode (mount electrode) 45...Connection wiring 45A…1st connection wiring 45B...Second connection wiring 46...Side 47…Front part 48...Back 63…Back side 63s…Side edge 63t...Tip edge 64…Surface 64t...Tip edge 100...Oscillator 101... Circuit board 102...Electronic components 103...Integrated Circuits

Claims

1. a crystal blank having a pair of vibrating arms; an electrode film disposed on the outer surface of the crystal blank; A quartz crystal resonator element having the electrode film is disposed on the outer surfaces of the pair of vibrating arms and has a pair of excitation electrodes that apply an electric field to the crystal blank to excite the crystal blank; The quartz crystal vibrating piece is characterized in that the excitation electrodes have a single layer structure made of a two-dimensional layered material, and are used in pairs arranged opposite each other across the quartz crystal blank.

2. 2. The quartz crystal vibrating piece according to claim 1, wherein the two-dimensional layered material is a single-layer film or a multi-layer film of graphene, which contains carbon atoms as a main element.

3. 2. The quartz crystal resonator element according to claim 1, wherein the two-dimensional layered material is one of silicene, germanene, stanene, and plumbene.

4. 4. The quartz crystal resonator element according to claim 1, wherein the two-dimensional layered material is doped with an impurity made of a group 13 element or a group 15 element.

5. 5. The quartz crystal resonator element according to claim 4, wherein the impurities are phosphorus or nitrogen.

6. 6. The quartz crystal vibrating piece according to claim 1, wherein the two-dimensional layered material has a conductive honeycomb structure.

7. 6. The quartz crystal vibrating piece according to claim 1, wherein the two-dimensional layered material has a conductive mille-feuille structure.

8. 8. The quartz crystal resonator element according to claim 6, wherein the two-dimensional layered material is a material exhibiting a band gap structure of a metal or a semimetal.

9. The quartz crystal vibrating piece according to claim 8, a package that hermetically seals the crystal resonator element; A quartz crystal resonator comprising:

10. A sensor using the quartz crystal resonator according to claim 9.

11. A crystal unit comprising: the crystal unit according to claim 9; An oscillator characterized in that the crystal unit is electrically connected to an integrated circuit as an oscillator.

12. an electrode film deposition process for depositing a single-layer electrode film made of a two-dimensional layered material on the outer surface of a quartz crystal blank having a pair of vibrating arms; a patterning step of patterning the electrode film to form a pair of excitation electrodes arranged on the outer surfaces of each of the pair of vibrating arms so as to face each other via the quartz crystal blank; 4. A method for manufacturing a quartz crystal vibrating piece, comprising: forming an electrode film comprising:

13. 13. The method for manufacturing a quartz crystal resonator piece according to claim 12, wherein the electrode film forming step forms the electrode film on the outer surface of the quartz crystal blank by chemical vapor deposition (CVD) or atomic layer deposition (ALD).

14. the electrode film forming step includes forming the electrode film using graphene containing carbon atoms as the two-dimensional layered material; 14. The method for manufacturing a quartz crystal vibrating piece according to claim 12, wherein the patterning step comprises forming a resist on the electrode film by photolithography, and then removing at least a portion of the electrode film by plasma ashing, thereby patterning the electrode film.

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