Vibrator and method for manufacturing vibrator

Abstract

To provide a vibrator capable of suppressing the occurrence of failure of a vibration element due to frequency adjustment.SOLUTION: The resonator element includes a resonator element 30, excitation electrodes 31 that are provided on a front surface 30a portion of the resonator element 30, excitation electrodes 32 that are provided on a front surface 30a portion on a side opposite to the front surface 30b portion of the resonator element 30 and have at least a recessed portion 32a, extraction electrodes 41 that are electrically connected to the excitation electrodes 31, extraction electrodes 42 that are electrically connected to the excitation electrodes 32, and a protective film 52 that is provided on front surfaces of the extraction electrodes 42.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a vibrator and a method for manufacturing a vibrator. [Background technology]

[0002] A known method for adjusting the frequency of a quartz crystal vibration element is described in Patent Document 1. In the method described in Patent Document 1, a negative potential is applied to the surface electrode of the quartz crystal vibration element to generate plasma around the surface electrode, ionize argon gas, and etch the surface electrode with the ionized argon gas, thereby adjusting the frequency of the quartz crystal vibration element. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-185971 Summary of the Invention [Problem to be solved by the invention]

[0004] As a result of adjusting the frequency of the vibration element of the present invention, the inventors of the present invention found that there was a risk of malfunction occurring in the vibration element of the present invention. For example, there was a risk that the extraction electrode of the vibration element of the present invention would be damaged by ionized argon gas. [Means for solving the problem]

[0005] A vibrator according to one aspect of the present application comprises a vibrating element having a piezoelectric substrate, a first electrode provided on a first surface of the piezoelectric substrate, a second electrode provided on a second surface opposite the first surface of the piezoelectric substrate and having at least a thin film portion, a first extraction electrode electrically connected to the first electrode, a second extraction electrode electrically connected to the second electrode, and a first protective film provided on a surface of the second extraction electrode.

[0006] A method for manufacturing a vibrator according to one embodiment of the present application is a method for manufacturing a vibrator including a vibrating element having a piezoelectric substrate, a first electrode provided on a first surface of the piezoelectric substrate, a second electrode provided on a second surface opposite the first surface of the piezoelectric substrate and having at least a thin film portion, a first extraction electrode electrically connected to the first electrode, a second extraction electrode electrically connected to the second electrode, and a protective film provided on a surface of the second extraction electrode, the method comprising the steps of: forming the protective film on the surface of the second extraction electrode; and adjusting the frequency of the vibrating element by applying a predetermined voltage to the second electrode and etching the surface of the second electrode with ions. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a perspective view of a vibrator according to a first embodiment. [Figure 2] Cross-sectional view of the vibrator taken along line AA in Figure 1. [Figure 3] FIG. [Figure 4] FIG. 4 is a perspective view of the vibration element of FIG. 3 as viewed from the back side. [Figure 5] 10 is a flowchart showing a manufacturing process of a vibrator. [Figure 6] 6 is a flowchart showing details of the vibration element preparation step in FIG. 5. [Figure 7] 7 is a flowchart showing details of the frequency adjustment process of FIG. 6. [Figure 8] 1A to 1C are cross-sectional views showing one embodiment of a manufacturing process. [Figure 9] 1A to 1C are cross-sectional views showing one embodiment of a manufacturing process. [Figure 10] FIG. 1 is a conceptual diagram showing an overview of a frequency adjustment device. [Figure 11A] 1A to 1C are cross-sectional views showing one embodiment of a manufacturing process. [Figure 11B] FIG. 10 is a cross-sectional view showing another embodiment in the manufacturing process. [Figure 12] FIG. 10 is a perspective view of a vibration element according to a second embodiment. [Figure 13] FIG. 13 is a perspective view of the vibration element of FIG. 12 as viewed from the back side. DETAILED DESCRIPTION OF THE INVENTION

[0008] In the embodiments of the present invention, components shown in the drawings may be shown with different scales for clarity. In the drawings, three mutually perpendicular axes, the X-axis, Y-axis, and Z-axis, may be illustrated. In the following explanation, the tip end of the arrows on the three axes may be referred to as the "plus side," and the base end of the arrow may be referred to as the "minus side." The direction parallel to the X-axis may be referred to as the "X-axis direction," the direction parallel to the Y-axis may be referred to as the "Y-axis direction," and the direction parallel to the Z-axis may be referred to as the "Z-axis direction."

[0009] The term "top surface" of a certain structure refers to the surface on the positive side of the Z axis direction of the structure, for example, "top surface of a substrate" refers to the surface on the positive side of the Z axis direction of a movable body. The term "bottom surface" of a certain structure refers to the surface on the negative side of the Z axis direction of the structure, for example, "bottom surface of a substrate" refers to the surface on the negative side of the Z axis direction of a movable body. Reference to a surface of a structure is intended to refer to the outer surface of the structure.

[0010] 1. Embodiment 1 1.1. Oscillator configuration Fig. 1 is a perspective view of a vibrator 1 according to this embodiment, and Fig. 2 is a cross-sectional view of the vibrator 1 taken along line AA in Fig. 1.

[0011] The resonator 1 shown in Fig. 1 is an oscillator, and more specifically, a crystal oscillator in which a resonator element 3 made of quartz crystal and an oscillation circuit 7 are packaged together. The resonator 1 is mounted on a circuit board 100 of electronic devices such as quartz watches, communication devices, computers, display devices, printing devices, industrial robots, automobiles, and aircraft, and is used for timing control, frequency control, etc. of the electronic devices.

[0012] The vibrator 1 has a base 10 , a cover 20 , and a vibrating element 3 . The base 10 includes a substrate 11 and an oscillator circuit 7 . The substrate 11 is a silicon substrate. The substrate 11 may be made of a semiconductor material other than silicon, such as Ge, GaP, GaAs, or InP. An oscillator circuit 7 is provided on the upper surface of the substrate 11. The oscillator circuit 7 is a semiconductor circuit including an element 700, a wiring layer 14, a terminal layer 17, insulating layers 13 and 15, and a passivation layer 16. The oscillator circuit 7 is electrically connected to the vibration element 3 via a bonding member B, and is also electrically connected to an external terminal 18 via a through electrode 18v. An insulating layer 12 is provided between the external terminals 18 and the substrate 11 and between the through electrodes 18v and the substrate 11.

[0013] In this embodiment, the oscillator circuit 7 is provided on the vibration element 3 side of the substrate 11, but the oscillator circuit 7 may also be provided on the circuit board 100 side of the substrate 11. The oscillator circuit 7 may also be in the form of a semiconductor chip. In this case, the semiconductor chip on which the oscillator circuit 7 is mounted may be mounted inside or outside the vibrator 1, or may be mounted on the circuit board 100 and electrically connected to the vibrator 1. In other words, in this embodiment, the vibrator 1 may be configured without the oscillator circuit 7, in other words, may be configured such that only the vibration element 3 is housed in a package.

[0014] The lid 20 has a recess 20r. The lid 20 is joined to the outer periphery of the upper surface of the base 10 via a joining portion 60, and a storage space S is formed between the lid 20 and the base 10. The vibration element 3 is accommodated in the accommodation space S. The accommodation space S is airtight and in a reduced pressure state, preferably a state closer to a vacuum. This reduces viscous resistance and improves the oscillation characteristics of the vibration element 3. However, the atmosphere in the accommodation space S is not particularly limited.

[0015] 1.2. Vibration element configuration Fig. 3 is a perspective view of the vibration element 3 according to this embodiment. Fig. 4 is a perspective view of the vibration element 3 of Fig. 3 as seen from the back side.

[0016] The vibration element 3 includes a vibration element 30, excitation electrodes 31 and 32, extraction electrodes 41 and 42, and protective films 51 and 52. In this embodiment, an AT-cut quartz crystal vibrating piece that vibrates in a thickness-shear vibration mode is used as a suitable example of the vibrating piece 30. The AT-cut quartz crystal vibrating piece has a third-order frequency-temperature characteristic, and therefore can form a vibrating element 3 with excellent temperature characteristics.

[0017] The excitation electrode 31 is arranged on the surface 30a of the vibrating bar 30. The excitation electrode 32 is arranged on the surface 30b of the vibrating bar 30. The surface 30a is the upper surface of the vibrating bar 30, and the surface 30b is the lower surface of the vibrating bar 30. In this embodiment, the vibrating bar 30 is an example of a piezoelectric substrate. The surface 30a is an example of a first surface, and the surface 30b is an example of a second surface. The excitation electrode 31 is an example of a first electrode, and the excitation electrode 32 is an example of a second electrode.

[0018] The excitation electrodes 31 and 32 are each a metal thin film made up of two layers of metal film. The lower metal film of the metal thin films, in other words, the metal film on the vibrating bar 30 side, is made of chromium (Cr), titanium (Ti), or the like. The upper metal film of the metal thin films, in other words, the metal film on the surface side, is made of gold (Au), silver (Ag), or the like. The metal film on the surface side functions as a frequency adjustment film for adjusting the resonance frequency of the vibration element 3 in a frequency adjustment process described later.

[0019] The vibration element 3 may be configured as a mesa type in which the vibration region sandwiched between the excitation electrodes 31 and 32 protrudes from its surroundings, or conversely, as an inverted mesa type in which the vibration region is recessed from its surroundings. In addition, the vibration element 3 may be subjected to bevel processing in which the periphery of the vibration element 30 is ground, or convex processing in which the upper and lower surfaces are made convex.

[0020] The vibration element 3 is not limited to vibrating in a thickness-shear vibration mode. For example, it may be a vibration element in which multiple vibrating arms vibrate in an in-plane direction. That is, the vibration element 30 is not limited to being formed from an AT-cut quartz crystal vibrating element, but may be formed from a quartz crystal vibrating element other than an AT-cut quartz crystal vibrating element, such as an X-cut quartz crystal vibrating element, a Y-cut quartz crystal vibrating element, a Z-cut quartz crystal vibrating element, a BT-cut quartz crystal vibrating element, an SC-cut quartz crystal vibrating element, or an ST-cut quartz crystal vibrating element. In the present embodiment, the vibration element 30 is made of quartz crystal, but is not limited thereto. For example, the vibration element 30 may be made of a piezoelectric single crystal such as lithium niobate, lithium tantalate, lithium tetraborate, langasite, potassium niobate, or gallium phosphate, or may be made of other piezoelectric single crystals. Furthermore, the vibration element 3 is not limited to a piezoelectrically driven vibration element, but may also be an electrostatically driven vibration element using electrostatic force.

[0021] The extraction electrode 41 is provided on the surface 30a of the vibrating bar 30, and electrically connects the excitation electrode 31 and the bonding member B. The extraction electrode 42 is provided on the surface 30b of the vibrating bar 30, and electrically connects the excitation electrode 32 and the bonding member B. In this embodiment, the extraction electrode 41 is an example of a first extraction electrode, and the extraction electrode 42 is an example of a second extraction electrode.

[0022] The extraction electrode 41 includes a terminal portion 41a and a connection portion 41b. The terminal portion 41a is provided on the surface 30b of the vibrating element 30 and is electrically connected to the bonding member B. The connection portion 41b is provided on the surface 30a, the side surface 30c, and the surface 30b of the vibrating element 30 and electrically connects the terminal portion 41a and the excitation electrode 31.

[0023] The extraction electrode 42 includes a terminal portion 42a and a connection portion 42b. The terminal portion 42a is provided on the surface 30b of the vibrating element 30 and is electrically connected to the bonding member B. The connection portion 42b is provided on the surface 30b of the vibrating element 30 and electrically connects the terminal portion 42a and the excitation electrode 32.

[0024] The extraction electrodes 41 and 42 are formed using the same process and materials as the excitation electrodes 31 and 32, respectively. Therefore, the extraction electrodes 41 and 42 are configured in the same manner as the excitation electrodes 31 and 32, respectively.

[0025] 1.3.Protective Film A protective film 51 is provided on a surface 41s of the extraction electrode 41. A protective film 52 is provided on a surface 42s of the extraction electrode 42. The protective films 51 and 52 function as masks that protect the extraction electrodes 41 and 42 from damage caused by collisions with argon ions in a frequency adjustment process described below. In this embodiment, the protective film 52 is an example of a first protective film.

[0026] In this embodiment, the protective film 51 and the protective film 52 are provided for the following two main reasons. The first reason is that a larger DC bias is applied to the extraction electrodes 41 and 42 than to the excitation electrodes 31 and 32. In the frequency adjustment process, a negative DC voltage is applied to the excitation electrodes 31 and 32. This negative DC voltage is applied to the excitation electrodes 31 and 32 via the extraction electrodes 41 and 42, so the potential of the excitation electrodes 31 and 32 becomes higher than the potential of the extraction electrodes 41 and 42. In other words, the potential of the extraction electrodes 41 and 42 becomes lower than the potential of the excitation electrodes 31 and 32. That is, the DC bias of the extraction electrodes 41 and 42 is greater than that of the excitation electrodes 31 and 32. Therefore, the number of ions colliding with the extraction electrodes 41 and 42 per unit area is greater, and the extraction electrodes 41 and 42 are more likely to be etched than the excitation electrodes 31 and 32.

[0027] 3 and 4, the extraction electrodes 41 and 42 are narrower and have a smaller area than the excitation electrodes 31 and 32. Therefore, the extraction electrodes 41 and 42 are more affected by etching than the excitation electrodes 31 and 32.

[0028] The protective film 51 is provided so as to cover the terminal portion 41a and the connection portion 41b of the extraction electrode 41. As described above, the connection portion 41b is provided along the surface 30a, the side surface 30c, and the surface 30b of the vibrating element 30, and therefore the protective film 51 is also provided along the surface 30a, the side surface 30c, and the surface 30b of the vibrating element 30.

[0029] 3 and 4, the connection portion 41b is narrower and has a smaller area than the terminal portion 41a. Therefore, protection of the connection portion 41b takes priority over protection of the terminal portion 41a in the extraction electrode 41. In other words, the protective film 51 is provided at least on the surface 41bs of the connection portion 41b.

[0030] When only the excitation electrode 32 is used as the frequency adjustment film, the protective film 51 of the extraction electrode 41 arranged on the surface 30a side of the vibrating element 30 may be omitted. In this case, the surface 30a side of the vibrating element 30 is treated so as to suppress etching in the frequency adjustment process.

[0031] The protective film 52 is provided to cover the terminal portion 42a and the connecting portion 42b of the extraction electrode 42. As shown in Figures 3 and 4, the connecting portion 42b is narrower and has a smaller area than the terminal portion 42a. Therefore, in the extraction electrode 42, protection of the connecting portion 42b takes priority over protection of the terminal portion 42a. In other words, the protective film 52 is provided on at least the surface 42bs of the connecting portion 42b.

[0032] The protective film 51 has a through hole 51h that exposes the extraction electrode 41. The protective film 52 has a through hole 52h that exposes the extraction electrode 42. Bonding members B are disposed in the through holes 51h and 52h, respectively.

[0033] 1.4. Protective film materials 1.4.1.Examples of protective film materials The protective films 51 and 52 are preferably formed of a material having a lower ion etching rate than the extraction electrodes 41 and 42. More specifically, the protective films 51 and 52 are preferably formed of a material having a lower sputtering rate than the metal film on the surface side of the extraction electrodes 41 and 42, in other words, the metal film on the surface side that is the frequency adjustment film of the excitation electrodes 31 and 32.

[0034] When the metal layers on the surface side of the extraction electrodes 41 and 42 are made of gold or silver, the protective films 51 and 52 are made of chromium, nickel (Ni), aluminum (Al), or tungsten (W).

[0035] In this way, the extraction electrodes 41 and 42 are covered with the protective films 51 and 52, respectively, so that they are less likely to be damaged in the frequency adjustment process described below, and the occurrence of defects such as high resistance and disconnection due to thinning of the film thickness is avoided. Furthermore, the protective films 51 and 52 are made of a metal material such as chromium or nickel, so they function as part of the extraction electrodes 41 and 42, contributing to the reduction of the resistance of the extraction electrodes 41 and 42.

[0036] 1.4.2.Other examples of protective film materials The protective films 51 and 52 may be formed of an insulating material such as silicon oxide (SiO2). The protective films 51 and 52 made of an insulating material have a lower ion etching rate in the frequency adjustment process than the protective films 51 and 52 made of a metal material such as chromium or nickel, and therefore the protective films 51 and 52 can be made thinner, thereby reducing the size and weight of the vibrating element 3. Furthermore, the protective films 51 and 52 made of an insulating material have a lower ion etching rate in the frequency adjustment process than the protective films 51 and 52 made of a metal material such as chromium or nickel, and therefore the adjustment range in the frequency adjustment process can be increased and the adjustment time can be lengthened.

[0037] 1.5.Vibrator manufacturing method 5 to 11B are diagrams illustrating a method for manufacturing the vibrator 1 of this embodiment. FIG. 5 is a flowchart showing the manufacturing process of the vibrator 1. FIG. 6 is a flowchart showing details of the vibrating element preparation step S2 in FIG. 5. FIG. 7 is a flowchart showing details of the frequency adjustment step S24 in FIG. 6. FIG. 8 is a cross-sectional view showing one embodiment of the electrode formation step S22 in FIG. 6. FIG. 9 is a cross-sectional view showing one embodiment of the protective film formation step S23 in FIG. 6. FIG. 10 is a conceptual diagram showing an overview of the frequency adjustment device 8. FIG. 11A is a cross-sectional view showing one embodiment of the etching step S243 in FIG. 7. FIG. 11B is a cross-sectional view showing another embodiment of the etching step S243 in FIG. 7. FIGS. 8, 9, and 11A show cross sections at a position corresponding to line AA in FIG. 1.

[0038] As shown in FIG. 5, the method for manufacturing the vibrator 1 includes a semiconductor substrate preparation step S1, a vibrating element preparation step S2, a mounting step S3, and a sealing step S4.

[0039] In the semiconductor substrate preparation step S1, a base 10 having an oscillation circuit 7 is prepared as shown in FIG. In the vibration element preparation step S2, the vibration element 3 is prepared, which has the protective film 51 and the protective film 52 on the extraction electrode 41 and the extraction electrode 42, respectively, as shown in Figures 3 and 4. The vibration element preparation step S2 will be described in detail later. In the mounting step S3, the vibration element 3 is mounted on the base 10 as shown in FIG. In the sealing step S4, as shown in FIG. 2, the lid 20 is joined to the outer periphery of the upper surface of the base 10 via a joint 60, thereby sealing the vibration element 3 in the accommodation space S.

[0040] 1.5.1. Vibration element preparation process As shown in FIG. 6, the vibration element preparation step S2 includes a vibration piece preparation step S21, an electrode formation step S22, a protective film formation step S23, and a frequency adjustment step S24.

[0041] In the vibrator element preparation step S21, the vibrator element 30, which is an AT-cut quartz crystal substrate, is prepared. In the electrode formation step S22, as shown in FIG. 8, the excitation electrode 31 and the extraction electrode 41, as well as the excitation electrode 32 and the extraction electrode 42, are formed on the surfaces 30a and 30b of the vibrator element 30.

[0042] In this embodiment, the excitation electrode 31 and the extraction electrode 41, and the excitation electrode 32 and the extraction electrode 42 are each made of two layers of metal film. The lower metal film is a chromium film, and the upper metal film is a gold film.

[0043] In the electrode formation process S22, a chromium film is formed on the surfaces of the vibrating element 30, including the surfaces 30a, 30b, and side surfaces 30c, by a vapor deposition method such as vacuum deposition or sputtering. Next, a gold film is formed on the surface of the chromium film by a vapor deposition method such as vacuum deposition or sputtering. Next, the laminate of the chromium film and the gold film is patterned using photolithography and etching to form the excitation electrode 31, the extraction electrode 41, the excitation electrode 32, and the extraction electrode 42. Note that the excitation electrode 31, the extraction electrode 41, the excitation electrode 32, and the extraction electrode 42 may also be formed by mask deposition or lift-off.

[0044] 1.5.2.Protective film formation process 4 and 9, in the protective film forming step S23, a protective film 51 having through holes 51h is formed on the extraction electrode 41, and a protective film 52 having through holes 52h is formed on the surface 42s of the extraction electrode 42. In this step, first, a protective film is formed on the extraction electrode 41 and the extraction electrode 42. Next, the protective film is patterned to form the protective film 51 and the protective film 52.

[0045] 1.5.3. Frequency Adjustment Process In the frequency adjusting step S24, the mass of the vibration element 3 is reduced using a frequency adjusting device 8 shown in FIG. 10, thereby adjusting the resonance frequency of the vibration element 3 to a desired value. 10, frequency adjustment device 8 includes an adjustment chamber 81, a power supply 82, a frequency measurement device 83, switches 84a and 84b, lead wires 85a and 85b, a gas inlet valve 86a, and a gas outlet valve 86b. The positive terminals of adjustment chamber 81 and power supply 82 are connected to earth.

[0046] As shown in FIG. 7, the frequency adjusting step S24 includes a frequency measuring step S241, a determining step S242, and an etching step S243.

[0047] In the frequency measurement step S241, the resonance frequency of the vibration element 3 is measured. In this process, first, the vibration element 3 is placed in the adjustment chamber 81, and the lead wires 85a and 85b are connected to the extraction electrodes 41 and 42, respectively. The switches 84a and 84b are each connected to the frequency measuring device 83. Next, the adjustment chamber 81 is evacuated, and the resonant frequency of the vibration element 3 is measured by the frequency measuring device 83.

[0048] In the determination step S242, it is determined whether or not frequency adjustment of the vibration element 3 is necessary based on the frequency measured by the frequency measurement device 83. If the measured frequency is not the desired frequency, the process proceeds to the etching step S243, and if the measured frequency is the desired frequency, the process exits the frequency adjustment step S24.

[0049] 1.5.4.Etching process In the etching step S243, the surface 32s of the excitation electrode 32 is etched away to adjust the resonance frequency of the vibration element 3. In other words, in this step, at least a part of the surface 32s of the excitation electrode 32 is removed by etching, thereby reducing the mass of the vibration element 3.

[0050] In this embodiment, the frequency is adjusted by one of the excitation electrodes 32. Therefore, the surface 31s of the excitation electrode 31 is treated so as not to be etched. Note that the frequency adjustment in the etching step S243 may be performed by using both the excitation electrode 31 and the excitation electrode 32, or by using one of the excitation electrodes 31. The configuration for adjusting the frequency by one of the excitation electrodes 31 will be described in the next section.

[0051] In the etching step S243, an inert discharge gas is introduced into the adjustment chamber 81 through the gas introduction valve 86a. In this embodiment, argon gas is introduced into the adjustment chamber 81 as the discharge gas. The switches 84a and 84b are each connected to the power source 82. Note that the switch 84a electrically connected to the excitation electrode 31 may be connected to an open terminal, but since it is preferable that the excitation electrodes 31 and 32 be at the same potential during the etching step S243, in this embodiment the switches 84a and 84b are each connected to the power source 82.

[0052] A negative DC voltage is applied from the power supply 82 to the excitation electrodes 31 and 32 via the lead wires 85a and 85b and the extraction electrodes 41 and 42, respectively. When a negative DC voltage is applied to the excitation electrode 32, the argon gas around the excitation electrode 32 becomes a plasma state. Argon cations 88 in the plasma are accelerated by the negative potential of the excitation electrode 32 and collide with the surface 32s of the excitation electrode 32, etching the excitation electrode 32. The method of generating plasma is not limited to application of a DC voltage; high-frequency discharge plasma may also be generated by applying an AC voltage to the argon gas. In the case of high-frequency discharge plasma, by applying a negative DC voltage to the excitation electrode 32, the argon cations 88 in the plasma can be accelerated by the negative potential of the excitation electrode 32 and collide with the surface 32s of the excitation electrode 32, etching the excitation electrode 32.

[0053] When the excitation electrode 32 is hit by the argon cations 88, metal particles 89 fly out from the metal film on the surface side, which is a frequency adjustment film, and the surface 32s of the excitation electrode 32 is gradually eroded. In this embodiment, the metal film on the surface side is a gold film. Therefore, the metal particles 89 are gold particles.

[0054] 11A, recesses 32a and protrusions 32b are formed by etching on a surface 32s of the excitation electrode 32. The recesses 32a are thinner portions of the surface 32s than the protrusions 32b due to more advanced etching.

[0055] The protrusions 32b are formed in an island shape on the surface 32s of the excitation electrode 32. The recesses 32a are formed in a groove shape on the surface 32s of the excitation electrode 32. In other words, the recesses 32a and the protrusions 32b form an uneven pattern on the surface 32s of the excitation electrode 32. The pattern formed by the recesses 32a and the protrusions 32b may be a polka dot pattern, a striped pattern, or the like, depending on the etching conditions, etc. When the entire surface 32s of the excitation electrode 32 is uniformly removed by etching, the entire surface 32s of the excitation electrode 32 becomes the recesses 32a. In this embodiment, the recesses 32a are an example of a thin film portion.

[0056] In this embodiment, the excitation electrode 32 has a two-layer structure consisting of a gold film on the surface side and a chromium film on the lower side. Because the ion etching rate of the lower chromium film is smaller than that of the gold film on the surface side, even if the lower chromium film is exposed in the recess 32a, etching of the lower chromium film is suppressed. Therefore, damage such as holes in the excitation electrode 32 is suppressed.

[0057] After the etching step S243 is completed, the process returns to the frequency measurement step S241 to measure the resonance frequency of the vibration element 3. Then, steps S241, S242, and S243 are repeated until the resonance frequency of the vibration element 3 reaches the desired frequency.

[0058] 1.5.5. Another Aspect of the Etching Process 11B is a cross-sectional view showing another example of the etching step S243, in which the cross section is taken at a position including the extraction electrode 41. 11B, the surface 31s of the excitation electrode 31 is removed by etching to adjust the resonance frequency of the vibration element 3. Therefore, the excitation electrode 32 is prevented from being etched.

[0059] 11B, recesses 31a and protrusions 31b are formed by etching on the surface 31s of the excitation electrode 31. The recesses 31a are thinner as a result of more etching than the protrusions 31b. The protrusions 31b are formed in island shapes on the surface 31s of the excitation electrode 31, and the recesses 31a are formed between the multiple protrusions 31b.

[0060] As described above, the vibrator 1 of this embodiment comprises a vibrating element 3 having a vibrating bar 30 as a piezoelectric substrate, an excitation electrode 31 as a first electrode provided on the surface 30a as a first surface of the vibrating bar 30, an excitation electrode 32 as a second electrode provided on the surface 30b as a second surface opposite the surface 30a of the vibrating bar 30 and having at least a recess 32a as a thin film portion, an extraction electrode 41 as a first extraction electrode electrically connected to the excitation electrode 31, an extraction electrode 42 as a second extraction electrode electrically connected to the excitation electrode 32, and a protective film 52 as a first protective film provided on the surface 42s of the extraction electrode 42.

[0061] As described above, in this embodiment, the protective film 52 is provided on the surface 42s of the extraction electrode 42. Therefore, even if the excitation electrode 32 has a configuration in which the recess 32a is provided, the extraction electrode 42 is protected by the protective film 52, and the formation of a recess similar to the recess 32a is suppressed. Therefore, the occurrence of defects such as high resistance and disconnection of the extraction electrode 42 due to the formation of the recess 32a is avoided, and a vibrator 1 with excellent quality can be realized.

[0062] In the vibrator 1 of this embodiment, the protective film 52 serving as the first protective film is made of a material having a lower sputtering rate than the excitation electrode 32 serving as the second electrode. In this way, the protective film 52 is made of a material with a lower sputtering rate than the excitation electrode 32. Since the extraction electrode 42 is covered with such a protective film 52, it is possible to suppress damage in the etching step S243, and to avoid the occurrence of defects such as high resistance and disconnection due to a thin film thickness. Moreover, since the protective film 52 is specifically formed of a metal material such as chromium or nickel, it functions as a part of the extraction electrode 42 and contributes to reducing the resistance of the extraction electrode 42 .

[0063] In the vibrator 1 of this embodiment, the protective film 52 serving as the first protective film is made of an insulating material. In this way, the protective film 52 is made of an insulating material such as silicon oxide (SiO2). The protective film 52 formed from an insulating material has a lower ion etching rate in the etching step S243 than the protective film 52 formed from a metal material, so the protective film 52 can be made thinner, and the vibration element 3 can be made smaller and lighter. Furthermore, since the protective film 52 formed from an insulating material has a lower ion etching rate in the etching step S243 than the protective film 52 formed from a metal material, the adjustment range of the frequency of the vibration element 3 can be increased and the adjustment time can be lengthened.

[0064] In the vibrator 1 of this embodiment, the extraction electrode 42 as the second extraction electrode includes a terminal portion 42a and a connection portion 42b between the terminal portion 42a and the excitation electrode 32 as the second electrode, and the protective film 52 as the first protective film is provided on at least the surface 42bs of the connection portion 42b.

[0065] The connection portion 42b is narrower and has a smaller area than the terminal portion 42a. Therefore, by configuring the connection portion 42b to be protected by the protective film 52, it is possible to prevent problems such as high resistance and disconnection caused by a thinning of the extraction electrode 42.

[0066] The manufacturing method of the vibrator 1 of this embodiment is a manufacturing method of the vibrator 1 including a vibrating element 3 having a vibrating bar 30 as a piezoelectric substrate, an excitation electrode 31 as a first electrode provided on a surface 30a as a first surface of the vibrating bar 30, an excitation electrode 32 as a second electrode provided on a surface 30b as a second surface opposite the surface 30a of the vibrating bar 30 and having at least a recess 32a as a thin film portion, an extraction electrode 41 as a first extraction electrode electrically connected to the excitation electrode 31, an extraction electrode 42 as a second extraction electrode electrically connected to the excitation electrode 32, and a protective film 52 provided on a surface 42s of the extraction electrode 42, and includes a protective film forming process S23 as a process of forming the protective film 52 on the surface 42s of the extraction electrode 42, and a frequency adjustment process S24 as a process of adjusting the frequency of the vibrating element 3 by applying a predetermined voltage to the excitation electrode 32 and scraping the surface 32s of the excitation electrode 32 with ions.

[0067] As described above, this embodiment includes a protective film forming step S23 in which the protective film 52 is formed on the surface 42s of the extraction electrode 42. Therefore, even if the surface 32s of the excitation electrode 32 is scraped in the frequency adjusting step S24, scraping of the extraction electrode 42 is suppressed. This prevents defects such as high resistance and disconnection of the extraction electrode 42, and realizes a vibrator 1 with excellent quality.

[0068] 2. Embodiment 2 Fig. 12 is a perspective view of the vibration element 3a according to embodiment 2. Fig. 13 is a perspective view of the vibration element 3a of Fig. 12 as seen from the back side. In the second embodiment, another form of the vibration element 3 used in the vibrator 1 of the first embodiment is shown. The vibration element 3a of the second embodiment differs from the vibration element 3 shown in the first embodiment in that the vibration element 3a has protective films 53a, 53b, 53c, and 53d at the four corners of the excitation electrode 31, respectively, and has protective films 54a, 54b, 54c, and 54d at the four corners of the excitation electrode 32, respectively. In the following description, the same reference numerals are used for the same components as in the first embodiment, and redundant description will be omitted. In this embodiment, the protective films 54a, 54b, 54c, and 54d are each an example of a second protective film.

[0069] 2.1.Protective film 53a, 53b, 53c, 53d 12, in the second embodiment, protective films 53a, 53b, 53c, and 53d are provided at the four corners of the excitation electrode 31. The reason for this is as follows.

[0070] Through experiments conducted by the inventors and others, it has been discovered that when the resonant frequency of the vibration element 3 is adjusted by scraping the surface 31s of the excitation electrode 31 in the frequency adjustment process S24, etching of the four corners of the excitation electrode 31 proceeds more rapidly than etching of the central portion of the excitation electrode 31.

[0071] Based on this finding, in the second embodiment, protective films 53a, 53b, 53c, and 53d are provided at the four corners of the surface 31s of the excitation electrode 31, respectively, to protect the four corners of the excitation electrode 31. Therefore, the configuration of the second embodiment prevents defects such as high resistance or chipping at the four corners of the excitation electrode 31. Furthermore, the adjustment range of the frequency of the vibration element 3 can be increased, and the adjustment time can be lengthened.

[0072] In the second embodiment, the protective film 51 and the protective films 53a, 53b, 53c, and 53d do not cover the side surfaces of the extraction electrode 41 and the excitation electrode 31, respectively. In other words, the side surfaces of the extraction electrode 41 and the side surfaces of the four corners of the excitation electrode 31 are exposed. However, since the area of ​​the side surfaces is smaller than the area of ​​the upper surfaces of the extraction electrode 41 and the excitation electrode 31, such a configuration is also possible. Note that, as in the first embodiment, the protective film 51 may be formed to cover the side surfaces of the extraction electrode 41. Furthermore, the protective films 53a, 53b, 53c, and 53d may be formed to cover the side surfaces of the four corners of the excitation electrode 31.

[0073] 2.2.Protective film 54a, 54b, 54c, 54d 13, in the second embodiment, protective films 54a, 54b, 54c, and 54d are provided at the four corners of the excitation electrode 32. The reason for this is as follows.

[0074] Through experiments conducted by the inventors and others, it has been discovered that when the resonant frequency of the vibration element 3 is adjusted by scraping the surface 32s of the excitation electrode 32 in the frequency adjustment process S24, etching of the four corners of the excitation electrode 32 progresses more than etching of the central part of the excitation electrode 32.

[0075] Based on this finding, in the second embodiment, protective films 54a, 54b, 54c, and 54d are provided at the four corners of the surface 32s of the excitation electrode 32, respectively, to protect the four corners of the excitation electrode 32. Therefore, the configuration of the second embodiment prevents defects such as high resistance or chipping at the four corners of the excitation electrode 32. Furthermore, the frequency adjustment range of the vibration element 3 can be increased, and the adjustment time can be lengthened.

[0076] In the second embodiment, the protective film 52 and the protective films 54a, 54b, 54c, and 54d do not cover the side surfaces of the extraction electrode 42 and the excitation electrode 32, respectively. In other words, the side surfaces of the extraction electrode 42 and the side surfaces of the four corners of the excitation electrode 32 are exposed. However, since the area of ​​the side surfaces is smaller than the area of ​​the upper surfaces of the extraction electrode 42 and the excitation electrode 32, such a configuration is also possible. Note that, as in the first embodiment, the protective film 52 may be formed to cover the side surfaces of the extraction electrode 42. Furthermore, the protective films 54a, 54b, 54c, and 54d may be formed to cover the side surfaces of the excitation electrode 32.

[0077] In the second embodiment, when the resonance frequency of the vibration element 3 is adjusted by scraping the surface 31s of the excitation electrode 31, the protective films 54a, 54b, 54c, and 54d may be omitted. On the other hand, when the resonance frequency of the vibration element 3 is adjusted by scraping the surface 32s of the excitation electrode 32, the protective films 53a, 53b, 53c, and 53d may be omitted.

[0078] As described above, in the vibrator 1 of the second embodiment, the vibrating element 3a has the protective films 54a, 54b, 54c, and 54d as second protective films provided at the four corners of the surface 32s of the excitation electrode 32 as the second electrode.

[0079] As described above, according to the second embodiment, it is possible to prevent defects such as high resistance or loss at the four corners of the excitation electrode 32. Furthermore, it is possible to increase the adjustment range of the frequency of the vibration element 3 and lengthen the adjustment time.

[0080] Although the preferred embodiment has been described above, the present invention is not limited to the above embodiment. The configuration of each part of the present invention can be replaced with any configuration that exhibits the same function as the above embodiment. [Explanation of symbols]

[0081] 1... vibrator, 3, 3a... vibrating element, 7... oscillation circuit, 8... frequency adjustment device, 10... base, 11... substrate, 12, 13, 15... insulating layer, 14... wiring layer, 16... passivation layer, 17... terminal layer, 18... external terminal, 18v... through electrode, 20... lid, 20r... recess, 30... vibrating element, 30a, 30b... surface, 30c... side, 31... excitation electrode, 31a... recess, 31b... convex portion, 31s... surface, 32... excitation electrode, 32a... recess, 32b... convex portion, 32s... surface, 41... extraction electrode, 41a... terminal portion, 41b... connection portion, 41s, 41bs... surface surface, 42...extraction electrode, 42a...terminal portion, 42b...connection portion, 42s, 42bs...surface, 51...protective film, 51h...through hole, 52...protective film, 52...through hole, 53a, 53b, 53c, 53d...protective film, 54a, 54b, 54c, 54d...protective film, 60...junction, 81...adjustment chamber, 82...power supply, 83...frequency measuring device, 84a, 84b...switch, 85a, 85b...lead wire, 86a...gas inlet valve, 86b...gas outlet valve, 88...argon cation, 89...metal particles, 100...circuit board, 700...element, S...accommodation space, B...joint member.

Claims

1. a piezoelectric substrate; a first electrode provided on a first surface of the piezoelectric substrate; a second electrode provided on a second surface of the piezoelectric substrate opposite to the first surface, the second electrode having at least a thin film portion; a first extraction electrode electrically connected to the first electrode; a second extraction electrode electrically connected to the second electrode; a first protective film provided on a surface of the second extraction electrode, Vibrator.

2. the first protective film is made of a material having a lower sputtering rate than the second electrode; The vibrator according to claim 1 .

3. the first protective film is made of an insulating material; The vibrator according to claim 1 .

4. the second extraction electrode includes a terminal portion and a connection portion between the terminal portion and the second electrode, the first protective film is provided at least on a surface of the connection portion; The vibrator according to claim 1 .

5. the vibration element has a second protective film provided on each of four corners of a surface of the second electrode; The vibrator according to claim 1 .

6. A method for manufacturing a vibrator including a vibrating element having a piezoelectric substrate, a first electrode provided on a first surface of the piezoelectric substrate, a second electrode provided on a second surface opposite to the first surface of the piezoelectric substrate and having at least a thin film portion, a first extraction electrode electrically connected to the first electrode, a second extraction electrode electrically connected to the second electrode, and a protective film provided on a surface of the second extraction electrode, forming the protective film on a surface of the second extraction electrode; applying a predetermined voltage to the second electrode to shave the surface of the second electrode with ions, thereby adjusting the frequency of the vibration element. A method for manufacturing a vibrator.

Images