JP2004120351A - Manufacturing method of piezoelectric vibration piece - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a piezoelectric vibration piece capable of easily film-forming a desired electrode at a low cost by utilizing a conventional process. <P>SOLUTION: Corrosion resistant films 11 are formed on both main faces of a crystal wafer 10 for which an etching rate in a thickness direction is high and patterned into a preliminary shape including the outer shape of a tuning fork type crystal vibration piece 1 and a margin part enlarged on the outer side of a detection vibration arm 4 and a wafer surface is exposed. Also, a photoresist layer 13 formed on the corrosion resistant film is patterned into a vibration piece outer shape and the part of the corrosion resistant film corresponding to the margin part is exposed. After forming the preliminary shape by through-etching a wafer exposed surface, the wafer surface is exposed by removing the exposed part of the corrosion resistant film, it is etched and the vibration piece outer shape is formed so as to leave a projected line 14 at the center of the thickness direction on a vibration piece side face. After removing the remaining photoresist layer and corrosion resistant film, an electrode film 16 formed on the vibration piece side face is patterned, the surface of a piezoelectric material is exposed to a projected line tip and electrodes 5a and 5b for detection separated in the thickness direction are formed. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a piezoelectric vibrating reed by photoetching a wafer made of a piezoelectric material such as a root quartz having etching anisotropy and patterning an electrode film on the surface thereof. The present invention relates to a method of forming electrodes separated in the thickness direction on the side surface of a vibrating arm of such a tuning-fork type piezoelectric vibrating reed.
[0002]
[Prior art]
2. Description of the Related Art Piezoelectric vibrating gyroscopes have been widely used as rotational angular velocity sensors for attitude control and navigation control of ships, aircraft, automobiles, etc., and for camera shake prevention / detection of video cameras and the like. Has also been applied. FIG. 5 shows an example of a tuning-fork type crystal vibrating piece for use in such a piezoelectric vibrating gyroscope. As shown in FIG. 5A, the tuning-fork type quartz vibrating piece 1 has a pair of driving vibrating arms 3 extending from the central base 2 to one side and a pair of driving vibrating arms 3 extending to the opposite side. And a vibration arm 4 for detection. The tuning-fork type quartz vibrating reed 1 is mounted in a predetermined package by bonding and fixing the supporting portions 2a and 2b protruding from the base 2, thereby forming a piezoelectric vibrating gyroscope. (For example, see Patent Document 1 below.)
[0003]
As shown in FIG. 5 (B), the detection vibrating arm 4 is provided with two pairs of detection electrodes 5a and 5b separated on the side surfaces thereof in the thickness direction. As shown in FIG. 5C, the driving vibrating arm 3 is provided with first driving electrodes 7a and 7b on the inner surface of a longitudinal groove 6 formed on the upper and lower main surfaces thereof, and has side surfaces thereof. Are provided with second driving electrodes 8a and 8b, and are electrically connected to each other to form a driving electrode for vibrating the tuning-fork type quartz vibrating piece 1. When a predetermined AC voltage is applied to the drive electrodes, electric fields are alternately generated between the adjacent first and second drive electrodes 7a, 8a and 7b, 8b, and the drive vibrating arm 3 is driven at the resonance frequency. It bends and vibrates. In the configuration in which the first driving electrodes 7a and 7b are provided on the inner surface of the groove 6, the electric field is generated in parallel with each of the main surfaces, so that the electric field efficiency is greatly improved and the CI value is reduced. Can be suppressed.
[0004]
In this state, when the tuning-fork type quartz vibrating reed 1 rotates about the Y axis 9 in FIG. 5A, the Coriolis force acting in a direction orthogonal to the direction of the vibration with respect to the rotational angular velocity causes the driving vibrating arm 3 to rotate. Is vertically stressed and vibrates vertically. This vibration is transmitted via the base 2 and causes the detection vibrating arm 4 to vibrate at its resonance frequency. By detecting this as an electric signal from the detection electrodes 5a and 5b, the rotation angular velocity and the rotation direction of the tuning fork type quartz vibrating piece 1 are obtained.
[0005]
Conventionally, a tuning-fork type quartz vibrating piece 1 has an electrode formed by subjecting a quartz wafer to a desired outer shape and a groove of each vibrating arm by wet-etching a quartz wafer using a photolithography technique, and applying a groove to the surface thereof by sputtering or the like. The film is patterned to form desired electrodes and electrode pads and a wiring pattern connecting them. When the quartz crystal wafer has a certain thickness, the detection electrodes 5a and 5b are formed by forming an electrode film on the entire side surface of the detection vibrating arm 4 and then mechanically or mechanically removing an unnecessary portion at the center in the thickness direction. It can be formed by chemical stripping. However, recently, the size and thickness of the piezoelectric device have been reduced with the downsizing of the electronic equipment, and the wafer has become extremely thin. Therefore, it is difficult to separate the electrode films by such a method.
[0006]
In order to cope with the miniaturization and thinning of the piezoelectric device, Japanese Patent Application Laid-Open No. H11-163,199 discloses that a groove is formed by etching the outer shape of a vibrator on both sides of a quartz plate so as to partially leave its thickness. After the electrode film is formed, the remaining portion of the groove is mechanically bent to separate the individual vibrators, and at the same time, an electrode separated in the thickness direction by the protrusion remaining in the groove is formed. A method is described. Further, Patent Literature 2 below discloses a method of similarly dividing an electrode in a thickness direction by removing an etching remaining portion of the groove by etching.
[0007]
[Patent Document 1] JP-A-8-18371 [Patent Document 2] JP-A-8-162874 [0008]
[Problems to be solved by the invention]
However, according to the method described in Patent Document 1, when the remaining portion of the groove is broken, a piece of quartz is generated and adheres to the quartz oscillator, thereby changing its oscillation characteristics or changing an adjacent quartz oscillator. There is a possibility that the electrode film may be damaged by contact with a jig or a jig, thereby causing defective products and a reduction in yield. Furthermore, since the folding position cannot be accurately controlled, the size of the protrusions remaining on the side surfaces of the crystal unit is not uniform, which causes a loss of balance of the vibrating arm, causing unnecessary vibration and deteriorating vibration characteristics. Occurs.
In addition, a special jig is required to fold the crystal unit at the remaining portion of the etching, which complicates the operation and increases the manufacturing cost.
[0009]
Further, in the method disclosed in Patent Document 2, when the remaining portion is completely removed by etching, there is a possibility that the side surface of the crystal unit is over-etched due to the crystal anisotropy of the crystal and a dent is formed. There is. Further, by removing the resist film formed on the remaining portion of the etching, the electrode film formed later thereon is lifted off. However, there is a possibility that the removed electrode material may adhere to the electrode again. .
[0010]
Therefore, the present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to use a conventional processing process utilizing photolithography technology to add a complicated process or to use special tools or equipment. A method for manufacturing a piezoelectric vibrating reed having electrodes separated in the thickness direction on the side surface of the piezoelectric vibrating reed simply and at low cost without using an electrode and without damaging the electrode or affecting the vibration characteristics. Is to do.
[0011]
[Means for Solving the Problems]
According to the present invention, in order to achieve the above object, a step of forming a corrosion resistant film on both main surfaces of a wafer made of a piezoelectric material having a higher etching rate in the thickness direction, and expanding the outer shape of the resonator element and the outside thereof. Patterning a preliminary shape including a blank portion on the corrosion-resistant film, exposing the surface of the wafer, forming a photoresist layer on the corrosion-resistant film and patterning the outer shape of the resonator element, Exposing the corresponding portion of the corrosion-resistant film, through-etching the exposed surface of the wafer to form the preliminary shape, and removing the exposed portion of the corrosion-resistant film corresponding to the blank portion, Exposing the surface of the wafer, and etching the exposed surface of the wafer so as to leave a ridge at the center in the thickness direction on the side surface of the preliminary shape to form the outer shape of the resonator element. And removing the remaining photoresist layer and the corrosion-resistant film, and then forming and patterning an electrode film on the side surface of the vibrating piece including the ridge, and forming a surface of the piezoelectric material on the tip of the ridge. And a step of removing the remaining photoresist layer.
[0012]
Since the wafer has a higher etching rate in the thickness direction, when the exposed surface of the wafer is etched to form the outer shape of the resonator element, the wafer is etched faster in the thickness direction than in the width direction. By adjusting the processing time and other conditions while limiting the processing range by patterning, it is easy to form a ridge at the center in the thickness direction of the side surface of the resonator element even if the resonator element itself is downsized. By controlling the etching rate in the thickness and width directions of the wafer by utilizing the etching anisotropy of the piezoelectric material, the ridge having a height that does not affect the characteristics of the resonator element can be formed on the side. And the electrodes formed on the side surfaces can be separated in the thickness direction by an etching process using a conventional photolithography technique. Therefore, there is no need to add complicated processes or use special tools and equipment, and the cost is low, and the desired piezoelectric vibrating reed can be formed without damaging the electrodes during processing and without affecting the vibration characteristics due to the attachment of foreign matter. It can be manufactured with good yield.
[0013]
As the piezoelectric material, quartz which has been conventionally generally used is preferable, and from the crystal anisotropy, it is preferable that the thickness direction of the wafer is oriented corresponding to the Z-axis direction of the quartz.
[0014]
In one embodiment, the patterning of the electrode film formed on the side surface of the wafer is performed by forming and patterning a photoresist layer on the electrode film by using a photolithography technique to form an electrode film on the tip of the ridge. By exposing, removing the exposed portion of the electrode film and exposing the surface of the piezoelectric material to the tip of the ridge, processing can be easily performed.
[0015]
According to another aspect of the present invention, a step of forming a corrosion-resistant film on both principal surfaces of a wafer made of a piezoelectric material having a higher etching rate in the thickness direction, the outer shape of a tuning fork vibrating piece having a pair of vibrating arms, and Patterning a preliminary shape including a blank portion enlarged outside the vibrating arm on the corrosion-resistant film to expose a surface of the wafer; and forming a photoresist layer on the corrosion-resistant film to form the vibrating piece. Patterning and exposing a portion of the corrosion resistant film corresponding to the blank portion; a process of forming the preliminary shape by penetrating an exposed surface of the wafer; and forming the corrosion resistant film corresponding to the blank portion. Exposing the exposed portion of the wafer to expose the surface of the preliminary shape, and etching the exposed surface of the wafer so as to leave a ridge at the center in the thickness direction on the side surface of the wafer. After forming the resonator element outer shape and removing the remaining photoresist layer and the corrosion-resistant film, an electrode film is formed on the side of the resonator element including the ridge and patterned to form a tip on the ridge. A method for manufacturing a piezoelectric vibrating reed is provided, comprising a step of exposing a surface of the piezoelectric material and a step of removing the remaining photoresist layer.
[0016]
Similarly, as the piezoelectric material, a quartz crystal which has been conventionally generally used is preferable. Due to its crystal anisotropy, the longitudinal direction, the width direction and the thickness direction of the vibrating arm are respectively defined in the Y-axis direction, the X-axis direction and the Z-axis direction of the crystal. It is preferable to orient in accordance with the direction.
[0017]
The patterning of the electrode film formed on the side surface of the wafer is performed by similarly forming a photoresist layer on the electrode film and patterning the photoresist film to expose the electrode film at the tip of the ridge. By exposing the surface of the piezoelectric material at the tip of the ridge, the processing can be easily performed.
[0018]
In one embodiment, the tuning-fork type vibrating reed has another pair of vibrating arms extending in a direction opposite to the pair of vibrating arms, and the preliminary shape is the same as that of the another pair of vibrating arms. In the step of forming an electrode film on the side surface of the vibrating piece and patterning the same, the electrode film is formed on the entire surface of the another pair of vibrating arms at the same time. And patterning. Thereby, two pairs of vibrating arms of a tuning fork type piezoelectric vibrating piece such as the piezoelectric gyro sensor described above with reference to FIG. 5 can be simultaneously processed without increasing the number of steps.
[0019]
In another embodiment, the tuning-fork type vibrating reed further has a longitudinal groove in which a driving electrode is formed on an inner surface of a main surface of the another pair of vibrating arms, and a photoresist layer is formed on the corrosion-resistant film. In the step of patterning the outer shape of the resonator element by forming the above, simultaneously with exposing the portion of the corrosion-resistant film corresponding to the blank portion, exposing the portion of the corrosion-resistant film corresponding to the groove, the corrosion-resistant film corresponding to the blank portion In the step of removing the exposed portion, at the same time, in the step of removing the exposed portion of the corrosion-resistant film corresponding to the groove to expose the surface of the wafer and etching the wafer exposed surface, And the grooves are formed in the main surfaces of the another pair of vibrating arms. As a result, a piezoelectric vibrating reed having a configuration in which an electrode is provided on the inner surface of the groove of the vibrating arm to greatly improve the electric field efficiency and suppress the CI value to a low level can be manufactured without increasing the number of steps by using the manufacturing process as it is. can do.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
FIGS. 1 to 4 show a process of manufacturing the tuning-fork type quartz vibrating piece 1 for a piezoelectric vibrating gyroscope shown in FIG. 5 by applying the method of the present invention. In particular, FIGS. 4 and FIG. 3 and FIG. 4 show cross sections of the driving vibrating arm 3, respectively. First, as shown in FIGS. 1A and 3A, a corrosion-resistant film 11 is formed on both surfaces of a piezoelectric material wafer 10 which is quartz in this embodiment, and a photoresist layer 12 is formed thereon. Is formed on the entire surface of the wafer by spin coating. The corrosion-resistant film 11 is generally formed of a metal material having sufficient corrosion resistance to an etching solution of a wafer. In this embodiment, a Cr / Au film laminated on the wafer surface by sputtering or vapor deposition is used.
[0021]
Next, the photoresist layer 12 is patterned using the first photomask, and the exposed corrosion-resistant film 11 is removed by etching as shown in FIGS. 1B and 3B, and the surface of the wafer 10 is removed. Expose. The first photomask has a mask pattern of a preliminary shape including an outer shape of the vibrating reed 1 and a blank portion enlarged outside the detecting vibrating arm 4. However, in this preliminary shape, no margin is provided outside the driving vibration arm 3. At this time, in consideration of crystal anisotropy of the crystal, the first photomask sets the longitudinal direction, the width direction, and the thickness direction of each vibrating arm with respect to the wafer 10 in the Y-axis direction and the X-axis direction, respectively. And a direction corresponding to the Z-axis direction.
[0022]
As shown in FIGS. 1 (C) and 1 (D), and FIGS. 3 (C) and 3 (D), after completely removing the remaining photoresist layer 12, a new photoresist layer 13 is formed on the entire surface of the wafer by spin coating. Form. The photoresist layer 13 is patterned using a second photomask having a mask pattern corresponding to the outer shape of the resonator element 1 and the groove 6 of the driving vibrating arm 3. Thereby, as for the detection vibrating arm, as shown in FIG. 1E, the portion of the corrosion-resistant film 11 corresponding to the blank portion and the surface of the wafer 10 are exposed. As for the driving vibrating arm, as shown in FIG. 3E, the portion of the corrosion-resistant film 11 corresponding to the groove and the surface of the wafer 10 are exposed.
[0023]
Next, the exposed surface of the wafer 10 is through-etched with an appropriate etchant such as hydrofluoric acid (HF). As a result, the outer shape of the preliminary shape including the blank portion as shown in FIG. 1 (F) is obtained for the detection vibrating arm, and the desired outer shape is obtained as shown in FIG. 3 (F) for the drive vibrating arm. To form Each exposed portion of the corrosion-resistant film 11 in FIGS. 1F and 3F is removed by etching. As a result, the surface of the wafer 10 corresponding to the blank portion is exposed as shown in FIG. 2G for the detection vibrating arm, and the groove is formed as shown in FIG. The surface of the wafer 10 corresponding to 6 is exposed.
[0024]
Next, the exposed surface of the wafer 10 is etched with an appropriate etchant. As shown in FIG. 2H, the detection vibrating arm is processed so that the blank portion is removed and the ridge 14 remains at the center of the side surface in the thickness direction. At the same time, grooves 6 are formed on the upper and lower main surfaces of the driving vibrating arm as shown in FIG. As described above, the longitudinal direction, the width direction, and the thickness direction of each of the vibrating arms are oriented so as to correspond to the Y-axis direction, the X-axis direction, and the Z-axis direction of the crystal, respectively, and the etching rate in the thickness direction is higher than the width direction. Therefore, by appropriately controlling the processing conditions such as the etching time, it is possible to easily form the protrusions 14 that do not substantially affect the vibration characteristics of the crystal resonator element 1.
[0025]
When the remaining photoresist layer 13 and corrosion resistant film 11 are completely removed, a crystal element piece 15 having a desired outer shape and surface shape is completed as shown in FIGS. 2 (I) and 4 (I). Next, as shown in FIG. 2 (J) and FIG. 4 (J), an electrode film 16 made of a Cr / Au film is formed on the entire surface of the crystal element piece 15 including the inner surface of the groove 6 and formed thereon. A photoresist layer 17 is formed.
[0026]
The photoresist layer 17 is patterned using a third photomask 18 in order to form the electrode film 16 into a desired electrode pattern. As for the detection vibrating arm, as shown in FIG. 2 (K), the portion formed at the tip of the ridge 14 of the photoresist layer 17 and the central portion of the upper and lower main surfaces are exposed and developed, and as shown in FIG. The electrode film 16 is exposed in these portions as shown in FIG. At the same time, for the driving vibrating arm, as shown in FIG. 4L, both sides of the groove 6 on the upper and lower main surfaces are patterned to expose the electrode film 16.
[0027]
Next, the exposed portion of the electrode film 16 is removed with an appropriate etchant to expose the wafer surface. As a result, as shown in FIG. 2 (M), desired detection electrodes 5a and 5b are formed on the side surfaces of the vibrating arm for detection separated at the center in the thickness direction by the ridges 14. At the same time, for the driving vibrating arm, the driving electrodes 7a and 7b separated on the inner surface and the side surface of the groove 6 are obtained as shown in FIG. Finally, by removing the remaining photoresist layer 17, the tuning-fork type quartz vibrating reed 1 of FIG. 5 is completed.
[0028]
As described above, the preferred embodiments of the present invention have been described in detail. However, the present invention can be implemented by adding various modifications and changes to the above embodiments within the technical scope thereof. For example, in the above embodiment, the surface of the wafer is processed by wet etching, but dry etching can also be used. Further, in the above-described embodiment, the process of forming the detection electrode for the piezoelectric vibrator for the piezoelectric vibrating gyroscope was described. However, the present invention provides various piezoelectric vibrating reeds having electrodes separated on the side in the thickness direction. It can be applied to the manufacture of
[Brief description of the drawings]
1A to 1F are cross-sectional views showing a process of manufacturing a tuning-fork type quartz vibrating piece for a piezoelectric vibrating gyroscope by applying the method of the present invention in the order of steps along the line BB in FIG. .
FIG. 2 is a similar cross-sectional view including (G) to (N) showing steps subsequent to FIG. 1 in the order of steps.
3A to 3F are cross-sectional views showing a process corresponding to FIG. 1 in the order of steps along the line CC in FIG. 5;
FIG. 4 is a similar cross-sectional view including (G) to (N) showing steps subsequent to FIG. 3 in the order of steps.
FIG. 5A is a plan view of a tuning-fork type quartz vibrating piece for a piezoelectric vibrating gyroscope, FIG. 5B is a cross-sectional view of a detecting vibrating arm taken along line BB, and FIG. It is sectional drawing of the drive vibration arm in a line.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 tuning-fork type crystal vibrating piece, 2 base, 2 a, 2 b support, 3 driving vibrating arm, 4 detecting vibrating arm, 5 a, 5 b detecting electrode, 6 groove, 7 a, 7 b first driving electrode, 8 a 8b 2nd drive electrode, 9 Y-axis, 10 wafer, 11 anticorrosion film, 12/13 photoresist layer, 14 ridge, 15 crystal element piece, 16 electrode film, 17 photoresist layer, 18 third photomask

Claims (8)

Forming a corrosion-resistant film on both main surfaces of a wafer made of a piezoelectric material having a higher etching rate in the thickness direction;
Patterning the outer shape of the vibrating reed and a preliminary shape including a margin portion enlarged outside thereof on the corrosion-resistant film, and exposing the surface of the wafer;
Forming a photoresist layer on the corrosion-resistant film, patterning the outer shape of the resonator element, and exposing a portion of the corrosion-resistant film corresponding to the blank portion;
Forming the preliminary shape by penetrating the exposed surface of the wafer, removing the exposed portion of the corrosion-resistant film corresponding to the blank portion, exposing the surface of the wafer,
Etching the exposed surface of the wafer so as to leave a ridge at the center in the thickness direction on the side surface of the preliminary shape, and forming the resonator element outer shape;
After removing the remaining photoresist layer and the corrosion-resistant film, forming and patterning an electrode film on the side surface of the vibrating piece including the ridge, and exposing the surface of the piezoelectric material to the tip of the ridge. When,
Removing the remaining photoresist layer. 2. The method according to claim 1, wherein the piezoelectric material is quartz, and the thickness direction of the wafer is oriented so as to correspond to a Z-axis direction of the quartz. 3. In the step of patterning the electrode film formed on the side surface of the resonator element including the ridge, forming a photoresist layer on the electrode film and patterning to expose the electrode film at the tip of the ridge, The method according to claim 1, wherein an exposed portion of the electrode film is removed to expose a surface of the piezoelectric material at a tip of the protrusion. Forming a corrosion-resistant film on both main surfaces of a wafer made of a piezoelectric material having a higher etching rate in the thickness direction;
Patterning the outer shape of the tuning-fork type vibrating reed having a pair of vibrating arms and a preliminary shape including a blank portion enlarged outside the vibrating arms on the corrosion-resistant film, thereby exposing the surface of the wafer;
Forming a photoresist layer on the corrosion-resistant film, patterning the outer shape of the resonator element, and exposing a portion of the corrosion-resistant film corresponding to the blank portion;
Forming the preliminary shape by penetrating the exposed surface of the wafer, removing the exposed portion of the corrosion-resistant film corresponding to the blank portion, exposing the surface of the wafer,
Etching the exposed surface of the wafer so as to leave a ridge at the center in the thickness direction on the side surface of the preliminary shape, and forming the resonator element outer shape;
After removing the remaining photoresist layer and the corrosion-resistant film, forming and patterning an electrode film on the side surface of the vibrating piece including the ridge, and exposing the surface of the piezoelectric material to the tip of the ridge. When,
Removing the remaining photoresist layer. The piezoelectric material is quartz, and the vibrating arm is oriented in a longitudinal direction, a width direction, and a thickness direction corresponding to the Y-axis direction, the X-axis direction, and the Z-axis direction of the quartz crystal, respectively. 3. The method for manufacturing a piezoelectric vibrating reed according to item 1. In the step of patterning the electrode film formed on the side surface of the resonator element including the ridge, forming a photoresist layer on the electrode film and patterning to expose the electrode film at the tip of the ridge, The method according to claim 4, wherein an exposed portion of the electrode film is removed to expose a surface of the piezoelectric material at a tip of the protrusion. The tuning fork-type vibrating reed has another pair of vibrating arms extending in a direction opposite to the pair of vibrating arms,
The preliminary shape is formed so as not to include an enlarged blank portion outside the another pair of vibrating arms,
7. The method according to claim 4, wherein the step of forming and patterning the electrode film on the side surface of the wafer includes simultaneously forming and patterning the electrode film on the entire surfaces of the another pair of vibrating arms. A method for manufacturing a piezoelectric vibrating reed according to any of the above items. The tuning fork-type vibrating reed has a longitudinal groove in which a drive electrode is formed on an inner surface of a main surface of the another pair of vibrating arms,
In the step of forming a photoresist layer on the corrosion-resistant film and patterning the outer shape of the resonator element, exposing a portion of the corrosion-resistant film corresponding to the blank portion and simultaneously removing a portion of the corrosion-resistant film corresponding to the groove. Exposed,
In the step of removing the exposed portion of the corrosion resistant film corresponding to the blank portion, at the same time, removing the exposed portion of the corrosion resistant film corresponding to the groove to expose the surface of the wafer,
In the step of etching the exposed surface of the wafer, a ridge is left in the center of the side surface of the vibrating piece in the thickness direction, and the groove is formed in the main surface of the another pair of vibrating arms. Item 8. The method for manufacturing a piezoelectric vibrating reed according to Item 7.

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