JP2012175363A - Method of manufacturing piezoelectric vibration piece, device for manufacturing piezoelectric vibration piece, piezoelectric vibration piece, oscillator, electronic apparatus and radio clock - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a piezoelectric vibration piece with which non-uniformity in film thickness can be suppressed when forming a mask member film, a device for manufacturing the piezoelectric vibration piece, the piezoelectric vibration piece, a piezoelectric vibrator with the piezoelectric vibration piece, an oscillator, an electronic apparatus and a radio clock.SOLUTION: The method includes a photo resist film forming step (mask member film forming step) of forming a photo resist member 85 on a first face 65a of a wafer 65 by a spin coat method. The photo resist film forming step is implemented by rotating the wafer 65 in a circumferential direction of the wafer 65. On a lower face 72b of a wafer holding section 72, a spin chuck 70 radially extends along a diameter direction of the spin chuck 70, and includes fins 75 which generate down air currents D downward from the lower face 72b of the wafer holding section 72 when rotating the spin chuck 70.

Description

  The present invention relates to a piezoelectric vibrating piece manufacturing method, a piezoelectric vibrating piece manufacturing apparatus, a piezoelectric vibrating piece, a piezoelectric vibrator, an oscillator, an electronic device, and a radio-controlled timepiece.

  In recent years, a piezoelectric vibrator using a crystal or the like is used as a time source, a timing source of a control signal, a reference signal source, or the like in a mobile phone or a portable information terminal device. Various piezoelectric vibrators of this type are provided, and one of them is a piezoelectric vibrator having a so-called tuning fork type piezoelectric vibrating piece. A tuning-fork type piezoelectric vibrating piece includes a pair of vibrating arm portions arranged side by side in the width direction and a thin plate-like crystal having a base portion that integrally fixes the base end sides in the longitudinal direction of the pair of vibrating arm portions. It is a piece.

A specific method for forming the outer shape of the tuning-fork type piezoelectric vibrating piece is as follows.
First, a metal film to be a metal mask for forming an outer shape is formed on the wafer on which the piezoelectric vibrating piece is formed by sputtering or the like. Next, a photoresist film (corresponding to the “mask material film” in the claims) is formed by applying a photoresist material on the metal film. Subsequently, the photoresist film is patterned by photolithography to form a resist film pattern for etching the metal film. Thereafter, the metal film is etched using the resist film pattern as a resist mask to form a metal film pattern. Finally, the wafer is etched using the metal film pattern as a metal mask. Thereby, the wafer other than the area protected by the metal film pattern is selectively removed, and the outer shape of the piezoelectric vibrating piece is formed.

Incidentally, in the step of forming the outer shape of the piezoelectric vibrating piece described above, it is necessary to apply a photoresist material to the surface of the wafer so as to obtain a uniform film thickness without unevenness. The reason is as follows.
For example, when a negative resist is used as the photoresist material, if there is a portion with a large film thickness due to unevenness of the film thickness of the photoresist film, it cannot be sufficiently cured even when exposed and is dissolved during development. As a result, surface defects are generated in the resist film pattern formed by the photoresist film. When the metal film is etched using the resist film pattern having the surface defect as a resist mask, the metal film corresponding to the surface defect is etched, and the surface defect is transferred to the metal film pattern. Further, when the wafer is etched using the metal film pattern to which the surface defect is transferred as a metal mask, the wafer corresponding to the surface defect is etched, and the surface defect is transferred to the piezoelectric vibrating piece formed on the wafer.
That is, the unevenness of the photoresist film applied on the surface of the wafer becomes a surface defect of the resist mask, which causes a defect when forming the outer shape of the piezoelectric vibrating piece. Therefore, it is necessary to apply a photoresist material to the surface of the wafer so that the film thickness of the photoresist film is uniform and uniform.

Here, as a method of forming a photoresist film on the surface of a wafer, a spin coating method using a spin chuck is known (see, for example, Patent Document 1).
The spin chuck disclosed in Patent Document 1 rotates at a high speed in a state where a wafer placed on an adsorption plate (corresponding to a “wafer holding portion” in the claims of the present application) is adsorbed at a negative pressure. Then, by discharging the photoresist material onto the upper surface of the wafer through the nozzle, the photoresist material spreads in a thin film shape by centrifugal force, and a photoresist film is formed on the upper surface of the wafer.

JP 2007-19317 A

However, generally, when the spin chuck and the wafer rotate at a high speed, airflow turbulence (hereinafter referred to as “turbulent flow”) occurs around the spin chuck and the wafer due to contact between the surface of the spin chuck and the wafer and air.
The mist of the photoresist material and dust in the atmosphere (hereinafter referred to as “floating matter”) generated when the photoresist material is discharged are disturbed around the wafer by the turbulent flow, and the wafer is being deposited. May adhere to the surface. This may cause unevenness in the film thickness of the photoresist film.

  Accordingly, the present invention provides a piezoelectric vibrating piece manufacturing method, a piezoelectric vibrating piece manufacturing apparatus, a piezoelectric vibrating piece, a piezoelectric vibrator including the piezoelectric vibrating piece, which can suppress unevenness in film thickness when forming a mask material film, It is an object to provide an oscillator, an electronic device, and a radio timepiece.

  In order to solve the above problems, a piezoelectric vibrating piece manufacturing apparatus according to the present invention is a method for manufacturing a piezoelectric vibrating piece from a wafer, wherein the piezoelectric vibrating piece is formed on a first surface of the wafer. A mask material film forming step for forming a mask material film as a mask for forming the outer shape by a spin coating method, wherein the mask material film forming step is performed on the upper surface of the wafer holder of the spin chuck on the upper surface of the wafer; The spin chuck is radially extended along the radial direction of the spin chuck on the lower surface of the wafer holding portion by holding the wafer faced down and rotating the wafer in the circumferential direction of the wafer. And a fin for generating a downward air flow from the lower surface of the wafer holding portion when the spin chuck rotates.

  According to the present invention, in the mask material film forming step, the mask material film is formed on the first surface of the wafer disposed above while generating a downward air flow by the fins provided on the lower surface of the wafer holding unit. ing. Therefore, floating substances that exist when the mask material film is formed are transported below the wafer by the downdraft. Thereby, since the attachment of the suspended | floating matter to the 1st surface of the wafer arrange | positioned upward can be suppressed, the nonuniformity of the film thickness at the time of forming a mask material film can be suppressed.

Further, the upper surface of the wafer holding portion covers and holds the entire second surface of the wafer.
According to the present invention, since the wafer holding part covers the entire surface of the second surface of the wafer, it is possible to completely prevent floating substances from adhering to the second surface. In addition, since the entire second surface of the wafer is held by the wafer holding unit, vibration of the outer peripheral portion of the wafer can be suppressed. Thereby, a film having a uniform thickness can be accurately formed on the first surface of the wafer. Therefore, it is possible to further suppress unevenness in film thickness when the mask material film is formed.

The piezoelectric vibrating piece manufacturing apparatus according to the present invention is an apparatus for manufacturing a piezoelectric vibrating piece used when a mask material film for forming the outer shape of the piezoelectric vibrating piece is formed on the first surface of the wafer by spin coating. A spin chuck that holds the second surface of the wafer downward on the upper surface of the wafer holding portion and rotates the wafer in the circumferential direction of the wafer, the spin chuck on the lower surface of the wafer holding portion And a fin that extends radially along the radial direction of the spin chuck and that generates a downward airflow downward from the lower surface of the wafer holding portion when the spin chuck rotates.
According to the present invention, the fins that generate the downward airflow when the spin chuck rotates are provided on the lower surface of the wafer holding unit, so that floating substances that exist when the mask material film is formed can be conveyed below the wafer. Thereby, since the attachment of the suspended | floating matter to the 1st surface of the wafer arrange | positioned upward can be suppressed, the nonuniformity of the film thickness at the time of forming a mask material film can be suppressed.

A piezoelectric vibrating piece according to the present invention is manufactured by the above-described method for manufacturing a piezoelectric vibrating piece.
According to the present invention, it is possible to accurately form the piezoelectric vibrating piece by suppressing the unevenness of the film thickness of the mask material film by the above manufacturing method. Accordingly, since the number of piezoelectric vibrating pieces discarded due to a defective outer shape is reduced, the cost of the piezoelectric vibrating piece can be reduced.

In addition, the piezoelectric vibrator of the present invention is characterized by including the piezoelectric vibrating piece manufactured by the above manufacturing method.
According to the present invention, since the low-cost piezoelectric vibrating piece is provided, a low-cost piezoelectric vibrator can be obtained.

The oscillator according to the present invention is characterized in that the above-described piezoelectric vibrator is electrically connected to an integrated circuit as an oscillator.
In addition, the electronic device of the present invention is characterized in that the above-described piezoelectric vibrator is electrically connected to a time measuring unit.
The radio timepiece of the present invention is characterized in that the above-described piezoelectric vibrator is electrically connected to the filter unit.
According to the oscillator, electronic device, and radio timepiece of the present invention, since the low-cost piezoelectric vibrator is provided, a low-cost oscillator, electronic device, and radio timepiece can be provided.

  According to the present invention, in the mask material film forming step, the mask material film is formed on the first surface of the wafer disposed above while generating a downward air flow by the fins provided on the lower surface of the wafer holding unit. ing. Therefore, floating substances that exist when the mask material film is formed are transported below the wafer by the downdraft. Thereby, since the attachment of the suspended | floating matter to the 1st surface of the wafer arrange | positioned upward can be suppressed, the nonuniformity of the film thickness at the time of forming a mask material film can be suppressed.

It is a top view of a piezoelectric vibrating piece. It is sectional drawing in the AA of FIG. It is a flowchart of the manufacturing process of a piezoelectric vibrating piece. It is side surface sectional drawing containing the centerline of a spin chuck. It is a bottom view of a spin chuck. It is explanatory drawing of a photoresist film formation process. It is explanatory drawing of a resist film pattern formation process. It is explanatory drawing of a metal film pattern formation process. It is explanatory drawing of a wafer etching process. It is explanatory drawing of the wafer after an etching. It is an external perspective view of a piezoelectric vibrator. It is an internal block diagram of a piezoelectric vibrator, and is a plan view in a state where a lid substrate is removed. It is sectional drawing in the BB line of FIG. FIG. 12 is an exploded perspective view of the piezoelectric vibrator shown in FIG. 11. It is a block diagram which shows one Embodiment of an oscillator. It is a lineblock diagram showing one embodiment of electronic equipment. It is a block diagram which shows one Embodiment of a radio timepiece.

(Piezoelectric vibrating piece)
First, a piezoelectric vibrating piece according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a plan view of the piezoelectric vibrating piece 4.
2 is a cross-sectional view taken along line AA in FIG.
As shown in FIG. 1, the piezoelectric vibrating reed 4 of the present embodiment is a tuning fork-type vibrating reed made of crystal and vibrates when a predetermined voltage is applied. The piezoelectric vibrating reed 4 includes a pair of vibrating arm portions 10 and 11 arranged in parallel, a base portion 12 that integrally fixes the base end sides of the pair of vibrating arm portions 10 and 11, and a pair of vibrating arm portions. And a groove portion 18 formed on both main surfaces 10 and 11. The groove portion 18 is formed from the proximal end side of the vibrating arm portions 10 and 11 to the vicinity of the middle along the longitudinal direction of the vibrating arm portions 10 and 11.

  The piezoelectric vibrating reed 4 is formed on the outer surface of the pair of vibrating arm portions 10 and 11, and is an excitation electrode including a first excitation electrode 13 and a second excitation electrode 14 that vibrate the pair of vibrating arm portions 10 and 11. 15, the mount electrodes 16 and 17 formed on the base 12 for mounting the piezoelectric vibrating reed 4 on the package, the first excitation electrode 13 and the second excitation electrode 14, and the mount electrodes 16 and 17 are electrically connected. And lead electrodes 19 and 20 to be connected.

  The excitation electrode 15 and the extraction electrodes 19 and 20 are formed of a single layer film of chromium made of the same material as that of the underlying layer of the mount electrodes 16 and 17 described later. Thereby, the excitation electrode 15 and the extraction electrodes 19 and 20 can be formed simultaneously with the formation of the underlying layers of the mount electrodes 16 and 17. However, the present invention is not limited to this. For example, the excitation electrode 15 and the extraction electrodes 19 and 20 may be formed of nickel, aluminum, titanium, or the like.

  The excitation electrode 15 is an electrode that vibrates the pair of vibrating arm portions 10 and 11 at a predetermined resonance frequency in a direction toward or away from each other. The first excitation electrode 13 and the second excitation electrode 14 constituting the excitation electrode 15 are formed by being patterned on the outer surfaces of the pair of vibrating arm portions 10 and 11 while being electrically separated from each other. (See FIG. 2). The first excitation electrode 13 and the second excitation electrode 14 are electrically connected to mount electrodes 16 and 17 (described later) via lead electrodes 19 and 20 on both main surfaces of the base portion 12, respectively. Yes.

  The mount electrodes 16 and 17 are laminated films of chromium and gold, and are formed by forming a chromium film having good adhesion with crystal as a base layer and then forming a gold thin film as a finishing layer on the surface. The However, the present invention is not limited to this. For example, after forming chromium and nichrome as a base layer, a gold thin film may be further formed as a finishing layer on the surface.

  A weight metal film 21 for adjusting (frequency adjustment) so as to vibrate within a predetermined frequency range is coated on the tip of the pair of vibrating arm portions 10 and 11. The weight metal film 21 is divided into a coarse adjustment film 21a used when the frequency is roughly adjusted and a fine adjustment film 21b used when the frequency is finely adjusted. By adjusting the frequency using the coarse adjustment film 21a and the fine adjustment film 21b, the frequency of the pair of vibrating arm portions 10 and 11 can be kept within the range of the nominal frequency of the device.

(Method for manufacturing piezoelectric vibrating piece)
Next, the manufacturing process of the piezoelectric vibrating reed 4 described above will be described below with reference to a flowchart.
FIG. 3 is a flowchart of the manufacturing process of the piezoelectric vibrating reed 4.
In the manufacturing process of the piezoelectric vibrating reed 4, the outer shape forming step S <b> 110 for forming the outer shape of the piezoelectric vibrating reed 4 on the wafer 65 (see FIG. 4) and the recess that becomes the groove 18 (see FIG. 2) of the piezoelectric vibrating reed 4 are formed. A groove forming step S130, an electrode forming step S140 for forming each electrode, and a fragmenting step S150 for cutting the piezoelectric vibrating reed 4 from the wafer 65 are provided. Details of each step will be described below.

(Outline forming step S110)
In the outer shape forming step S110, a metal film forming step S112 for forming a metal film on the surface of the wafer 65, a wafer setting step S114 for setting the wafer 65 on a spin chuck 70 (see FIG. 4) described later, And a photoresist film forming step S116 for forming a film of a photoresist (corresponding to “mask material film” in the claims). Further, a resist film pattern forming step S120 for forming a resist film pattern from the photoresist film by photolithography technology, a metal film pattern forming step S122 for forming a metal film pattern by etching the metal film using the resist film pattern as a mask, And a wafer etching step S124 for etching the wafer 65 using the film pattern as a mask. In the following description, among the both surfaces of the wafer 65, the surface disposed above in the first wafer setting step S114 will be described as the first surface 65a, and the surface disposed below will be described as the second surface 65b.

(Metal film formation process S112)
First, in the metal film forming step S112, a metal film 84 (see FIG. 7) is formed on the wafer 65 which has been polished and finished to a predetermined thickness with high accuracy. The metal film 84 is, for example, a laminated film of a base film 84a (see FIG. 7) made of chromium and a protective film 84b (see FIG. 7) made of gold, and is formed by a sputtering method, a vapor deposition method, or the like. . The metal film pattern formed in the metal film forming step S112 serves as a metal mask for etching the wafer 65 in the subsequent wafer etching step S124 and groove forming step S130.

(Wafer setting step S114, spin chuck)
Next, a wafer setting step S114 for setting the wafer 65 on the spin chuck 70 is performed.
FIG. 4 is a side cross-sectional view including the central axis K of the spin chuck 70.
FIG. 5 is a bottom view of the spin chuck 70.
In the following, first, the spin chuck 70 will be described with reference to FIGS. 4 and 5, and then the wafer setting step S114 will be described. In FIG. 4, the metal film 84 formed on the surface of the wafer 65 is not shown for easy understanding of the drawing.

  As shown in FIG. 4, the spin chuck 70 includes a wafer holding portion 72 that holds the wafer 65, and a column portion 76 that extends downward from the center of the wafer holding portion 72 and supports the wafer holding portion 72. I have. The wafer holding part 72 and the column part 76 are made of, for example, resin or metal.

The wafer holding part 72 is a plate-like member having a substantially circular shape in plan view. The diameter of the wafer holding portion 72 is formed to be substantially the same as the diameter of the wafer 65 so as to cover the entire second surface 65 b of the wafer 65.
The upper surface 72a of the wafer holding part 72 is formed flat, and the wafer 65 can be placed by contacting the second surface 65b of the wafer 65.
A plurality of suction holes 74 are formed on the entire upper surface 72 a of the wafer holding portion 72. The suction hole 74 is connected to a vacuum pump (not shown) through a suction passage 73 formed in the wafer holding portion 72 and a suction passage 78 formed in a post portion 76 described later. By vacuuming with a vacuum pump, the wafer 65 is attracted to the wafer holding unit 72 by negative pressure and held on the upper surface 72 a of the wafer holding unit 72.

A support column 76 extending downward is provided at the approximate center of the lower surface 72 b of the wafer holding unit 72.
The column portion 76 is a hollow cylindrical member, and is formed integrally with the wafer holding portion 72 so that the central axis substantially coincides with the central axis of the wafer holding portion 72.
A suction passage 78 is formed inside the column 76 and is connected to a vacuum pump (not shown). The suction passage 78 communicates with a suction passage 73 and a suction hole 74 formed in the wafer holding portion 72.
The column portion 76 is connected to a motor (not shown). When the motor is driven to rotate, the spin chuck 70 rotates about the center axis K as the center of rotation.

As shown in FIG. 5, flat fins 75 that extend radially along the radial direction of the spin chuck 70 are formed on the lower surface 72 b of the spin chuck 70. A plurality of fins 75 (four in this embodiment) are formed from the center portion 72c of the spin chuck 70 to the outer peripheral edge portion 72d at intervals of about 90 ° in the circumferential direction of the wafer holding portion 72. The fins 75 are formed in a substantially triangular shape having a vertex at the outer peripheral edge 72d of the wafer holding portion 72 and a bottom side on the outer periphery of the column portion 76 in a side view (see FIG. 4).
Further, the fin 75 has an inclined surface facing the rotation direction W (clockwise direction in FIG. 5) and the downward direction of the spin chuck 70. By forming the fins 75 in this manner, a downward air flow D (see FIG. 6) is generated downward from the lower surface 72b of the wafer holding portion 72 when the spin chuck 70 rotates as will be described later. Note that the shape and number of fins 75, the inclination angle, and the like are set according to the required air volume of the downdraft D or the like.

  The spin chuck 70 is arranged in a coater cup 81 formed so as to surround the side and the lower side of the spin chuck 70. An exhaust port 83 communicating with a suction pump (not shown) is provided below the coater cup 81, and the inside of the coater cup 81 is configured to have a negative pressure by being sucked by the suction pump. . Mist of the photoresist material 85 and floating matter such as dust in the atmosphere generated in a photoresist film forming step S116 described later are transported by the descending airflow D generated when the spin chuck 70 rotates, and are coated from the exhaust port 83 to the coater cup. 81 is discharged to the outside.

(Wafer setting step S114)
A wafer setting step S114 for setting the wafer 65 on which the metal film is formed on the spin chuck 70 configured as described above is performed.
In the wafer setting step S114, the wafer 65 is set on the wafer holder 72 of the spin chuck 70. Specifically, the second surface 65 b disposed below the wafer 65 and the upper surface 72 a of the wafer holding unit 72 are brought into contact with each other, and the wafer 65 is placed on the upper surface 72 a of the wafer holding unit 72. A positioning mechanism (not shown) is provided between the second surface 65 b of the wafer 65 and the upper surface 72 a of the wafer holder 72, and the central axis of the wafer 65 substantially coincides with the central axis K of the spin chuck 70. Is placed as follows.

(Photoresist film forming step S116)
FIG. 6 is an explanatory diagram of the photoresist film forming step S116.
Subsequently, as shown in FIG. 6, a photoresist film 85 (corresponding to a “mask material film” in the claims of the present application) is applied, and a photoresist film forming step S <b> 116 is performed to form a photoresist film on the wafer 65. . Note that the photoresist film forming step S116 is performed in the atmosphere. Further, the photoresist material 85 applied in the present embodiment is a so-called negative resist material in which the exposed portion is cured and remains at the time of development.

In the photoresist film forming step S116, first, vacuuming is performed by a vacuum pump (not shown), and the second surface 65b of the wafer 65 is vacuum-sucked by the wafer holding unit 72, and a motor (not shown) is driven to rotate. The chuck 70 and the wafer 65 are rotated at high speed.
Subsequently, as shown in FIG. 6, a photoresist material 85 is dropped from a nozzle 79 disposed above the wafer 65 along the central axis K toward the first surface 65 a of the wafer 65.
When the dropped photoresist material 85 adheres to the first surface 65a of the wafer 65, it spreads in a thin film shape from the approximate center of the wafer 65 to the outer peripheral side by centrifugal force. As a result, a photoresist film 85 a is formed on the first surface 65 a of the wafer 65.

  Here, on the first surface 65 a side of the wafer 65, a turbulent flow F is generated by the rotation of the wafer 65. Then, when the photoresist material 85 is dropped or when the photoresist material 85 spreads in a thin film shape from the approximate center of the wafer 65 to the outer peripheral side, mist of the photoresist material 85, dust in the atmosphere, etc. The suspended matter is disturbed around the wafer 65 by the turbulent flow F. For this reason, there is a possibility that floating substances may adhere to the surface of the wafer 65 during the formation of the photoresist film 85a, and there is a possibility that unevenness may occur in the film thickness of the photoresist film 85a.

However, the fins 75 are formed on the lower surface 72b of the spin chuck 70 of the present embodiment, and the spin chuck 70 rotates at a high speed in the photoresist film forming step S116, so that the lower surface 72b of the wafer holding unit 72 is downward. A downward airflow D is generated. Due to the descending airflow D, the turbulent flow F generated around the wafer 65 is rectified from the outer peripheral edge of the wafer 65 toward the lower side of the wafer 65. The suspended matter around the wafer 65 is conveyed by the descending airflow D and discharged from the exhaust port 83 provided below the wafer 65. Therefore, adhesion of floating substances to the first surface 65a of the wafer 65 is suppressed. Furthermore, since the entire second surface 65b of the wafer 65 is covered with the wafer holding portion 72, the attachment of floating substances to the second surface 65b of the wafer 65 is completely prevented.
As described above, in the photoresist film forming step S116, the attachment of floating substances to the first surface 65a and the second surface 65b of the wafer 65 is suppressed, so that the film thickness when forming the photoresist film 85a is reduced. Unevenness can be suppressed.

(Application surface confirmation S117 and front / back reversing step S118)
After the photoresist film 85a is formed on the first surface 65a of the wafer 65, when the photoresist film 85a is not formed on the second surface 65b of the wafer 65 disposed below (S117), the wafer 65 The first surface 65a and the second surface 65b are reversed, and the photoresist film forming step S116 is performed again on the second surface 65b of the wafer 65.
At this time, as described above, the floating substance around the wafer 65 is conveyed by the descending airflow D and is discharged from an exhaust port (not shown), so that attachment of the floating substance to the second surface 65b of the wafer 65 is suppressed. . Furthermore, since the entire first surface 65a of the wafer 65 on which the photoresist film 85a has already been formed in the first photoresist film formation step S116 is covered by the wafer holding portion 72, the first surface 65a of the wafer 65 is covered. Adherence of suspended matter is suppressed.
Thus, in the second photoresist film formation step S116, the attachment of floating substances to the second surface 65b of the wafer 65 and the first surface 65a of the wafer 65 on which the photoresist film 85a has already been formed is suppressed. Therefore, unevenness in film thickness when the photoresist film 85a is formed can be suppressed.
Thus, the photoresist film 85a is formed on the first surface 65a and the second surface 65b of the wafer 65.

(Resist film pattern forming step S120)
FIG. 7 is an explanatory diagram of the resist film pattern forming step S120.
Next, as shown in FIG. 7, a resist film pattern forming step S120 is performed in which the photoresist film 85a formed on the metal film 84 is patterned by photolithography.
The photomask 90 is obtained by forming a light-shielding film pattern 95 having a light-shielding property such as chromium on a main surface 91a of a light-transmitting photo substrate 91 such as glass. The light shielding film pattern 95 is for patterning the photoresist film 85 a and is formed on the main surface 91 a of the photo substrate 91 in a region excluding the region corresponding to the outer shape of the piezoelectric vibrating reed 4.
In the resist film pattern forming step S120, photomasks 90 are set on both surfaces of the wafer 65, and exposure is performed by irradiating ultraviolet rays R. As described above, the photoresist material 85 of this embodiment uses a negative resist material that cures the photoresist film 85a in the region exposed to ultraviolet rays. Therefore, when immersed in the developer after exposure, only the photoresist film 85a in the region that is not exposed to ultraviolet rays and not cured is selectively removed.

Here, when the film thickness of the photoresist film 85a is uneven and there is a portion where the film thickness is thick, even if the photoresist film 85a is exposed, it cannot be cured sufficiently and may be dissolved and removed during development. There is. Then, since a surface defect occurs in the resist film pattern of the remaining photoresist film 85a, there is a risk of causing a defect when the outer shape of the piezoelectric vibrating piece 4 is formed.
However, in this embodiment, in the photoresist film forming step S116, floating substances are prevented from adhering to the first surface 65a and the second surface 65b of the wafer 65, and unevenness of the film thickness of the photoresist film 85a is suppressed. However, a photoresist film 85a is formed. Therefore, in the resist film pattern forming step S120, a resist film pattern 85b (see FIG. 8) having no surface defects can be formed.

(Metal film pattern formation process S122)
FIG. 8 is an explanatory diagram of the metal film pattern forming step S122.
Next, using the resist film pattern 85b of the remaining photoresist film 85a as a resist mask, a metal film pattern forming step S122 for patterning the metal film 84 formed in the metal film forming step S112 is performed. In this step, the metal film 84 not masked by the resist film pattern 85b is selectively removed. Thereafter, the resist film pattern 85b is removed. As a result, a metal film pattern 84 c corresponding to the outer shape of the piezoelectric vibrating reed 4 is formed on the first surface 65 a and the second surface 65 b of the wafer 65.

(Wafer Etching Step S124)
FIG. 9 is an explanatory diagram of the wafer etching step S124.
FIG. 10 is an explanatory diagram of the wafer 65 after etching.
Next, as shown in FIG. 9, a wafer etching process S124 is performed in which the wafer 65 is etched from both sides of the wafer 65 using the metal film pattern 84c as a metal mask. Thereby, the region not masked by the metal film pattern 84c can be selectively removed, and the piezoelectric plate 4a (see FIG. 10) having the outer shape of the piezoelectric vibrating piece 4 can be formed. As shown in FIG. 10, each piezoelectric plate 4a is connected to the etched wafer 65 by a connecting portion 4b.
Thus, the outer shape forming step S110 is completed.

(Groove forming step S130)
Next, a groove forming step S130 is performed in which a concave portion that becomes the subsequent groove 18 (see FIG. 1) is formed in each piezoelectric plate 4a. Specifically, a photoresist film (not shown) is formed on the surface of each piezoelectric plate 4a by a spray coating method or the like, and the photoresist film is patterned by a photolithography technique. Subsequently, the metal film 84 is etched using the resist film pattern as a resist mask, and the metal film 84 is patterned in a state where a recess formation region is left open. Then, after etching the wafer 65 using the metal film 84 as a metal mask, the metal film 84 is removed, whereby a recess can be formed on the main surface of each piezoelectric plate 4a. Above, groove part formation process S130 is complete | finished.

(Electrode formation step S140)
Next, an electrode forming step S140 is performed in which an electrode or the like is formed on the outer surface of the piezoelectric plate 4a formed in the outer shape of the piezoelectric vibrating piece 4. In the electrode forming step S140, first, a metal film is formed and patterned to form the excitation electrode 15, the extraction electrodes 19 and 20, the mount electrodes 16 and 17, and the weight metal film 21 (all of which refer to FIG. 1). . Next, the resonance frequency of the piezoelectric plate 4a is coarsely adjusted. The coarse adjustment film 21a of the weight metal film 21 is irradiated with laser light to evaporate a part thereof, and the weight of the vibrating arm portions 10 and 11 is changed. Thus, the electrode formation process S140 is completed.

(Smallization step S150)
Finally, a connecting portion 4b that connects the wafer 65 and each piezoelectric plate 4a is cut, and a fragmentation step S150 is performed to separate the plurality of piezoelectric vibrating reeds 4 from the wafer 65 into pieces. As a result, a plurality of tuning-fork type piezoelectric vibrating reeds 4 can be manufactured from a single wafer 65 at a time. At this time, the manufacturing process of the piezoelectric vibrating reed 4 is completed, and a plurality of piezoelectric vibrating reeds 4 can be obtained.

(effect)
According to the present embodiment, in the photoresist film forming step S116, the first air flow 65a of the wafer 65 disposed above is generated while the downward airflow D is generated by the fins 75 provided on the lower surface 72b of the wafer holder 72. A photoresist film 85a is formed. Accordingly, floating substances that are present when the photoresist film 85 a is formed are conveyed below the wafer 65 by the descending airflow D. Thereby, since the adhesion of floating substances to the first surface 65a of the wafer 65 disposed above can be suppressed, unevenness of the film thickness when the photoresist film 85a is formed can be suppressed.

  Further, according to the present embodiment, since the wafer holding unit 72 covers the entire surface of the second surface 65b of the wafer 65, it is possible to completely prevent floating substances from adhering to the second surface 65b. Further, since the entire surface of the second surface 65b of the wafer 65 is held by the wafer holding unit 72, vibration of the outer peripheral portion of the wafer 65 can be suppressed. Thus, a photoresist film 85a having a uniform thickness can be formed on the first surface 65a of the wafer 65 with high accuracy. Accordingly, it is possible to further suppress unevenness in film thickness when the photoresist film 85a is formed.

  Further, according to the present embodiment, the wafer holding unit 72 covers the entire surface of the second surface 65 b of the wafer 65, so that the large fins 75 can be formed on the lower surface 72 b of the wafer holding unit 72. As a result, a strong descending airflow D can be generated, so that floating substances can be more effectively suppressed from adhering to the first surface 65a of the wafer 65 disposed above.

Here, when forming a semiconductor device, a resist pattern is often formed only on the surface of the semiconductor substrate (corresponding to the “first surface 65a” in the present embodiment), and only the surface of the semiconductor substrate is used. For this reason, the floating substance adhering to the back surface of the semiconductor substrate (corresponding to the “second surface 65b” in the present embodiment) could be removed by polishing.
On the other hand, when forming the external shape of the piezoelectric vibrating reed 4, the first surface 65 a and the second surface 65 b of the wafer 65 are used as described above. For this reason, the floating substances adhering to the second surface 65b before the formation of the photoresist film 85a cannot be removed by polishing, and an additional process for removing the adhering substances attached by rinsing liquid application, N2 blow, or the like is required. I need it. Further, after forming the photoresist film 85a on the second surface 65b in the second photoresist film forming step S116 after the front / back reversing step S118, the photoresist film 85a is floated on the first surface 65a on which the photoresist film 85a has already been formed. When an object is attached, it is very difficult to remove the attached suspended matter.
However, according to the present embodiment, since the wafer holding unit 72 covers the entire surface of the second surface 65b of the wafer 65, it is possible to completely prevent adhesion of floating substances to the second surface 65b. As described above, the present invention that reliably prevents floating substances from adhering to the second surface 65 b of the wafer 65 is particularly effective in forming the outer shape of the piezoelectric vibrating reed 4.

  In addition, according to the present embodiment, the piezoelectric vibrating reed 4 can be formed with high accuracy by suppressing the unevenness of the film thickness of the photoresist film 85a by the above manufacturing method. Accordingly, the number of piezoelectric vibrating reeds 4 discarded due to a defective outer shape is reduced, and the cost of the piezoelectric vibrating reed 4 can be reduced.

(Piezoelectric vibrator)
Next, the piezoelectric vibrator 1 will be described as a package 9 including the piezoelectric vibrating reed 4 manufactured by the manufacturing method described above.
FIG. 11 is an external perspective view of the piezoelectric vibrator 1.
FIG. 12 is an internal configuration diagram of the piezoelectric vibrator 1 and is a plan view in a state where the lid substrate 3 is removed.
13 is a cross-sectional view taken along line BB in FIG.
FIG. 14 is an exploded perspective view of the piezoelectric vibrator 1 shown in FIG.
In FIG. 14, the excitation electrodes 13 and 14, the extraction electrodes 19 and 20, the mount electrodes 16 and 17, and the weight metal film 21, which will be described later, are omitted for easy understanding of the drawing.
As shown in FIG. 11, the piezoelectric vibrator 1 according to the present embodiment includes a package 9 in which a base substrate 2 and a lid substrate 3 are anodically bonded via a bonding film 35, and a piezoelectric vibration housed in a cavity 3 a of the package 9. The surface mount type piezoelectric vibrator 1 is provided with a piece 4.

  As shown in FIG. 13, the base substrate 2 and the lid substrate 3 are anodic bondable substrates made of a glass material, for example, soda lime glass, and are formed in a substantially plate shape. A cavity 3 a for accommodating the piezoelectric vibrating reed 4 is formed on the side of the lid substrate 3 that is bonded to the base substrate 2.

  A bonding film 35 (bonding material) for anodic bonding is formed on the entire bonding surface side of the lid substrate 3 with the base substrate 2. The bonding film 35 is formed in the frame area around the cavity 3a in addition to the entire inner surface of the cavity 3a. Although the bonding film 35 of the present embodiment is formed of aluminum, the bonding film 35 can be formed of chromium, silicon, or the like. The bonding film 35 and the base substrate 2 are anodically bonded, and the cavity 3a is vacuum-sealed.

  The piezoelectric vibrator 1 includes through electrodes 32 and 33 that penetrate the base substrate 2 in the thickness direction and conduct the inside of the cavity 3 a and the outside of the piezoelectric vibrator 1. The through electrodes 32 and 33 are disposed in the through holes 30 and 31 that penetrate the base substrate 2, and the metal pins 7 that electrically connect the piezoelectric vibrating reed 4 and the outside, the through holes 30 and 31, and the metal And a cylindrical body 6 filled between the pins 7. In the following description, the through electrode 32 is described as an example, but the same applies to the through electrode 33. The electrical connection of the through electrode 33, the routing electrode 37 and the external electrode 39 is the same as that of the through electrode 32, the routing electrode 36 and the external electrode 39.

The through hole 30 is formed so that the inner shape gradually increases from the upper surface U side to the lower surface L side of the base substrate 2, and the cross-sectional shape including the central axis O of the through hole 30 is tapered. Has been.
The metal pin 7 is a conductive rod-shaped member formed of a metal material such as silver, nickel alloy, or aluminum, and is molded by forging or pressing. The metal pin 7 is preferably formed of a metal having a linear expansion coefficient close to that of the glass material of the base substrate 2, for example, an alloy (42 alloy) containing 58 weight percent iron and 42 weight percent nickel.
The cylinder 6 is obtained by baking paste-like glass frit. At the center of the cylinder 6, a metal pin 7 is arranged so as to penetrate the cylinder 6, and the cylinder 6 is firmly fixed to the metal pin 7 and the through hole 30.

  As shown in FIG. 14, a pair of routing electrodes 36 and 37 are patterned on the upper surface U side of the base substrate 2. A bump B made of gold or the like is formed on each of the pair of lead-out electrodes 36 and 37, and the pair of mount electrodes of the piezoelectric vibrating reed 4 is mounted using the bump B. As a result, one mount electrode 17 (see FIG. 12) of the piezoelectric vibrating reed 4 is electrically connected to one through electrode 32 via one lead-out electrode 36, and the other mount electrode 16 (see FIG. 12) is connected to the other. The other through electrode 33 is electrically connected to the other through electrode 37.

  A pair of external electrodes 38 and 39 are formed on the lower surface L of the base substrate 2. The pair of external electrodes 38 and 39 are formed at both ends in the longitudinal direction of the base substrate 2, and are electrically connected to the pair of through electrodes 32 and 33, respectively.

  When the piezoelectric vibrator 1 configured in this way is operated, a predetermined drive voltage is applied to the external electrodes 38 and 39 formed on the base substrate 2. As a result, a voltage can be applied to the first excitation electrode 13 and the second excitation electrode 14 of the piezoelectric vibrating reed 4, so that the pair of vibrating arm portions 10 and 11 are vibrated at a predetermined frequency in a direction in which they are approached and separated. Can do. The vibration of the pair of vibrating arm portions 10 and 11 can be used as a time source, a timing source for control signals, a reference signal source, and the like.

(effect)
According to the present invention, since the low-cost piezoelectric vibrating piece 4 is provided, the low-cost piezoelectric vibrator 1 can be obtained.

(Oscillator)
Next, an embodiment of an oscillator according to the present invention will be described with reference to FIG.
As shown in FIG. 15, the oscillator 110 according to the present embodiment is configured such that the piezoelectric vibrator 1 is an oscillator electrically connected to an integrated circuit 111. The oscillator 110 includes a substrate 113 on which an electronic element component 112 such as a capacitor is mounted. An integrated circuit 111 for an oscillator is mounted on the substrate 113, and a piezoelectric vibrating piece of the piezoelectric vibrator 1 is mounted in the vicinity of the integrated circuit 111. The electronic element component 112, the integrated circuit 111, and the piezoelectric vibrator 1 are electrically connected by a wiring pattern (not shown). Each component is molded with a resin (not shown).

In the oscillator 110 configured as described above, when a voltage is applied to the piezoelectric vibrator 1, the piezoelectric vibrating piece in the piezoelectric vibrator 1 vibrates. This vibration is converted into an electric signal by the piezoelectric characteristics of the piezoelectric vibrating piece and input to the integrated circuit 111 as an electric signal. The input electrical signal is subjected to various processes by the integrated circuit 111 and output as a frequency signal. Thereby, the piezoelectric vibrator 1 functions as an oscillator.
In addition, by selectively setting the configuration of the integrated circuit 111, for example, an RTC (real-time clock) module or the like as required, the operation date and time of the device or external device in addition to a single-function oscillator for a clock, etc. Functions such as controlling time and providing time and calendar can be added.

  According to the oscillator 110 of this embodiment, since the low-cost piezoelectric vibrator 1 is provided, the low-cost oscillator 110 can be provided.

(Electronics)
Next, an embodiment of an electronic apparatus according to the present invention will be described with reference to FIG. Note that a portable information device 120 having the above-described piezoelectric vibrator 1 will be described as an example of the electronic device.
First, the portable information device 120 of this embodiment is represented by, for example, a mobile phone, and is a development and improvement of a wrist watch in the prior art. The appearance is similar to that of a wristwatch, and a liquid crystal display is arranged in a portion corresponding to a dial so that the current time and the like can be displayed on this screen. Further, when used as a communication device, it is possible to perform communication similar to that of a conventional mobile phone by using a speaker and a microphone that are removed from the wrist and incorporated in the inner portion of the band. However, it is much smaller and lighter than conventional mobile phones.

  Next, the configuration of the portable information device 120 of this embodiment will be described. As shown in FIG. 16, the portable information device 120 includes the piezoelectric vibrator 1 and a power supply unit 121 for supplying power. The power supply unit 121 is made of, for example, a lithium secondary battery. The power supply unit 121 includes a control unit 122 that performs various controls, a clock unit 123 that counts time, a communication unit 124 that communicates with the outside, a display unit 125 that displays various information, and the like. A voltage detection unit 126 that detects the voltage of the functional unit is connected in parallel. Power is supplied to each functional unit by the power supply unit 121.

  The control unit 122 controls each function unit to control operation of the entire system such as transmission and reception of audio data, measurement and display of the current time, and the like. The control unit 122 includes a ROM in which a program is written in advance, a CPU that reads and executes the program written in the ROM, and a RAM that is used as a work area for the CPU.

  The timer unit 123 includes an integrated circuit including an oscillation circuit, a register circuit, a counter circuit, an interface circuit, and the like, and the piezoelectric vibrator 1. When a voltage is applied to the piezoelectric vibrator 1, the piezoelectric vibrating piece vibrates, and the vibration is converted into an electric signal by the piezoelectric characteristics of the crystal, and is input to the oscillation circuit as an electric signal. The output of the oscillation circuit is binarized and counted by a register circuit and a counter circuit. Then, signals are transmitted to and received from the control unit 122 through the interface circuit, and the current time, current date, calendar information, and the like are displayed on the display unit 125.

The communication unit 124 has functions similar to those of a conventional mobile phone, and includes a radio unit 127, a voice processing unit 128, a switching unit 129, an amplification unit 130, a voice input / output unit 131, a telephone number input unit 132, a ring tone generation unit. 133 and a call control memory unit 134.
The radio unit 127 exchanges various data such as audio data with the base station via the antenna 135. The audio processing unit 128 encodes and decodes the audio signal input from the radio unit 127 or the amplification unit 130. The amplifying unit 130 amplifies the signal input from the audio processing unit 128 or the audio input / output unit 131 to a predetermined level. The voice input / output unit 131 includes a speaker, a microphone, and the like, and amplifies a ringtone and a received voice or collects a voice.

In addition, the ring tone generator 133 generates a ring tone in response to a call from the base station. The switching unit 129 switches the amplifying unit 130 connected to the voice processing unit 128 to the ringing tone generating unit 133 only when an incoming call is received, so that the ringing tone generated by the ringing tone generating unit 133 passes through the amplifying unit 130. To the audio input / output unit 131.
Note that the call control memory unit 134 stores a program related to incoming / outgoing call control of communication. The telephone number input unit 132 includes, for example, number keys from 0 to 9 and other keys. By pressing these number keys and the like, a telephone number of a call destination is input.

  The voltage detection unit 126 detects the voltage drop and notifies the control unit 122 when the voltage applied to each functional unit such as the control unit 122 by the power supply unit 121 falls below a predetermined value. . The predetermined voltage value at this time is a value set in advance as a minimum voltage necessary to stably operate the communication unit 124, and is, for example, about 3V. Upon receiving the voltage drop notification from the voltage detection unit 126, the control unit 122 prohibits the operations of the radio unit 127, the voice processing unit 128, the switching unit 129, and the ring tone generation unit 133. In particular, it is essential to stop the operation of the wireless unit 127 with high power consumption. Further, the display unit 125 displays that the communication unit 124 has become unusable due to insufficient battery power.

That is, the operation of the communication unit 124 can be prohibited by the voltage detection unit 126 and the control unit 122, and that effect can be displayed on the display unit 125. This display may be a text message, but as a more intuitive display, a x (X) mark may be attached to the telephone icon displayed at the top of the display surface of the display unit 125.
In addition, the function of the communication part 124 can be stopped more reliably by providing the power cutoff part 136 that can selectively cut off the power supply of the part related to the function of the communication part 124.

  According to the portable information device 120 of the present embodiment, since the low-cost piezoelectric vibrator 1 is provided, the low-cost portable information device 120 can be provided.

(Radio watch)
Next, an embodiment of a radio timepiece according to the present invention will be described with reference to FIG.
As shown in FIG. 17, the radio-controlled timepiece 140 according to the present embodiment includes the piezoelectric vibrator 1 electrically connected to the filter unit 141, and receives a standard radio wave including timepiece information to accurately It is a clock with a function of automatically correcting and displaying the correct time.
In Japan, there are transmitting stations (transmitting stations) that transmit standard radio waves in Fukushima Prefecture (40 kHz) and Saga Prefecture (60 kHz), each transmitting standard radio waves. Long waves such as 40 kHz or 60 kHz have both the property of propagating the ground surface and the property of propagating while reflecting the ionosphere and the ground surface, so the propagation range is wide, and the above two transmitting stations cover all of Japan. is doing.

Hereinafter, the functional configuration of the radio timepiece 140 will be described in detail.
The antenna 142 receives a long standard wave of 40 kHz or 60 kHz. The long-wave standard radio wave is obtained by subjecting time information called a time code to AM modulation on a 40 kHz or 60 kHz carrier wave. The received long standard wave is amplified by the amplifier 143 and filtered and tuned by the filter unit 141 having the plurality of piezoelectric vibrators 1.
The piezoelectric vibrator 1 according to this embodiment includes crystal vibrator portions 148 and 149 having resonance frequencies of 40 kHz and 60 kHz that are the same as the carrier frequency.

Further, the filtered signal having a predetermined frequency is detected and demodulated by the detection and rectification circuit 144.
Subsequently, the time code is taken out via the waveform shaping circuit 145 and counted by the CPU 146. The CPU 146 reads information such as the current year, accumulated date, day of the week, and time. The read information is reflected in the RTC 148, and accurate time information is displayed.
Since the carrier wave is 40 kHz or 60 kHz, the crystal vibrator portions 148 and 149 are preferably vibrators having the tuning fork type structure described above.

  In addition, although the above-mentioned description was shown in the example in Japan, the frequency of the long standard wave is different overseas. For example, in Germany, a standard radio wave of 77.5 KHz is used. Therefore, when the radio timepiece 140 that can be used overseas is incorporated in a portable device, the piezoelectric vibrator 1 having a frequency different from that in Japan is required.

  According to the radio timepiece 140 of this embodiment, since the low-cost piezoelectric vibrator 1 is provided, the low-cost radio timepiece 140 can be provided.

The present invention is not limited to the embodiment described above.
In the manufacturing method of the piezoelectric vibrating piece 4 of the present embodiment, the tuning fork type piezoelectric vibrating piece 4 is manufactured. However, the piezoelectric vibrating piece 4 manufactured by the manufacturing method of the present invention is not limited to the tuning fork type. A cut-type piezoelectric vibrating piece (thickness sliding vibrating piece) may be used. Moreover, you may manufacture electronic components other than a piezoelectric vibrating piece with the manufacturing method of this invention.

  In the method of manufacturing the piezoelectric vibrating reed 4 of this embodiment, the photoresist material 85 is formed using the spin chuck 70, but the film forming material is not limited to the photoresist material 85. Further, although a negative resist material is used as the photoresist material 85, the photoresist material 85 is not limited to a negative resist material, and for example, a positive resist material may be used.

  The fins 75 of the spin chuck 70 of this embodiment are formed in a flat plate shape. However, the fin 75 is not limited to a flat plate shape, and may be formed on a curved surface, for example. However, this embodiment has an advantage in that molding is easy. Further, the shape and the number of the fins 75 are not limited to this embodiment.

DESCRIPTION OF SYMBOLS 1 ... Piezoelectric vibrator 4 ... Piezoelectric vibrating piece 65 ... Wafer 65a ... 1st surface 65b ... 2nd surface 70 ... Spin chuck 72 ... Wafer holding part 72a ... Upper surface 72b ... Lower surface 75 ... Fin 85 ... Photoresist material (mask material film) 110 ... Oscillator 120 ... Portable information device (electronic device) 123 ... Timekeeping unit 140 ... Radio wave Clock 141... Filter part D .. descending air flow S116... Photoresist film forming step (mask material film forming step)

Claims (8)

A method of manufacturing a piezoelectric vibrating piece for manufacturing a piezoelectric vibrating piece from a wafer,
A mask material film forming step for forming a mask material film on the first surface of the wafer by a spin coating method as a mask for forming an outer shape of the piezoelectric vibrating piece;
The mask material film forming step is performed by holding the wafer on the upper surface of the wafer holding portion of the spin chuck with the second surface of the wafer downward, and rotating the wafer in the circumferential direction of the wafer,
The spin chuck extends radially on the lower surface of the wafer holding portion along the radial direction of the spin chuck, and generates a downward air flow from the lower surface of the wafer holding portion when the spin chuck rotates. A method of manufacturing a piezoelectric vibrating piece comprising a fin. A method of manufacturing a piezoelectric vibrating piece according to claim 1,
The method of manufacturing a piezoelectric vibrating piece, wherein an upper surface of the wafer holding unit covers and holds the entire second surface of the wafer. An apparatus for manufacturing a piezoelectric vibrating piece used when a mask material film for forming an outer shape of a piezoelectric vibrating piece is formed on a first surface of a wafer by a spin coating method,
A spin chuck that holds the second surface of the wafer downward on the upper surface of the wafer holder and rotates the wafer in the circumferential direction of the wafer;
The spin chuck extends radially on the lower surface of the wafer holding portion along the radial direction of the spin chuck, and generates a downward air flow from the lower surface of the wafer holding portion when the spin chuck rotates. An apparatus for manufacturing a piezoelectric vibrating piece comprising a fin.   A piezoelectric vibrating piece manufactured by the manufacturing method according to claim 1.   A piezoelectric vibrator comprising the piezoelectric vibrating piece according to claim 4.   An oscillator, wherein the piezoelectric vibrator according to claim 5 is electrically connected to an integrated circuit as an oscillator.   6. An electronic apparatus, wherein the piezoelectric vibrator according to claim 5 is electrically connected to a timer unit.   6. A radio timepiece wherein the piezoelectric vibrator according to claim 5 is electrically connected to a filter portion.

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