WO2009157246A1 - Vibrating gyroscope using piezoelectric film and method for manufacturing the same - Google Patents

Vibrating gyroscope using piezoelectric film and method for manufacturing the same Download PDF

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Publication number
WO2009157246A1
WO2009157246A1 PCT/JP2009/057342 JP2009057342W WO2009157246A1 WO 2009157246 A1 WO2009157246 A1 WO 2009157246A1 JP 2009057342 W JP2009057342 W JP 2009057342W WO 2009157246 A1 WO2009157246 A1 WO 2009157246A1
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film
formed
metal film
electrodes
piezoelectric
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PCT/JP2009/057342
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French (fr)
Japanese (ja)
Inventor
池田 隆志
荒木 隆太
伸貴 手嶋
泰之 平田
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住友精密工業株式会社
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Priority to JP2008-163550 priority
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Publication of WO2009157246A1 publication Critical patent/WO2009157246A1/en

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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01CMEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C19/00Gyroscopes; Turn-sensitive devices using vibrating masses; Turn-sensitive devices without moving masses; Measuring angular rate using gyroscopic effects
    • G01C19/56Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
    • G01C19/567Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode
    • G01C19/5677Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators
    • G01C19/5684Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators the devices involving a micromechanical structure

Abstract

Disclosed is a vibrating gyroscope (100) comprising a piezoelectric film (40). The vibrating gyroscope (100) comprises a circular or polygonal vibrating body (11), a leg part (15) flexibly supporting the vibrating body (11) and having a fixed end, a plurality of electrodes (13b) so formed on the vibrating body (11) as to sandwich the piezoelectric film (40) in the thickness direction with an upper metal film (60) and a lower metal film (30), and a lead electrode (14) so formed on the leg part (15) as to sandwich the piezoelectric film (40) and an insulating film (50) of low dielectric constant in the thickness direction with the upper metalfilm (60) and the lower metal film (30).

Description

[Correction based on Rule 91 07.05.2009] Vibrating gyroscope using piezoelectric film and manufacturing method thereof

The present invention relates to a vibration gyro using a piezoelectric film and a method for manufacturing the same.

In recent years, vibratory gyros using piezoelectric materials have been actively developed. Conventionally, a gyro, in which the vibrator itself is made of a piezoelectric material as described in Patent Document 1, has been developed, and there is also a gyro that uses a piezoelectric film formed on the vibrator. For example, in Patent Document 2, a PZT film, which is a piezoelectric material, is used to excite the primary vibration of a vibrating body, and a part of the gyro distortion caused by Coriolis force generated when an angular velocity is applied to the vibrating body. A technique for detecting the above is disclosed.

On the other hand, as the size of various devices on which the gyro is mounted is becoming smaller and smaller, the miniaturization of the gyro itself is also an important issue. In order to achieve downsizing of the gyro, it is necessary to remarkably increase the processing accuracy of each member constituting the gyro. Moreover, it can be said that it is a strong demand of the industry to provide a gyro with further improved angular velocity detection accuracy and a gyro that is resistant to unexpected vibration (disturbance). However, the gyro structure shown in the following patent document does not satisfy the demand for miniaturization and high performance over the past several years.

JP-A-8-271258 JP 2000-9473 A

As described above, it is very difficult to simultaneously satisfy the demand for high performance as a gyro while achieving downsizing and high processing accuracy of a vibration gyro using a piezoelectric film. In general, when the gyro is reduced in size, there is a problem that the signal detected by the detection electrode of the gyro becomes weak when an angular velocity is given to the vibrating body. Therefore, since the size of the vibration gyro reduced in size is small in the difference between the signal that should be detected and the signal that is generated due to an unexpected impact (disturbance) from the outside, it is difficult to improve the detection accuracy of the gyro.

By the way, there are various types of shocks in the external shock. For example, in the ring-shaped vibrating body described in Patent Document 2 described above, there is an impact that causes a seesaw-like movement in the vertical direction of the surface on which the ring exists with the fixed post at the center of the ring as an axis. By this impact, vibration called a rocking mode is excited. On the other hand, there is an impact in which the entire circumference of the ring-shaped member of the vibrating body supported by the fixed post is bent simultaneously above or below the surface where the ring exists. Due to this impact, vibration called a bounce mode is excited. Even if such an impact occurs in the vibrating gyroscope, it is extremely difficult to establish a technique for detecting an accurate angular velocity.

In addition, the drive electrode that excites the primary vibration for the vibration gyro and the extraction electrode that is formed to capture the signal of the detection electrode that detects the secondary vibration caused by the angular velocity constitutes a piezoelectric element due to the manufacturing process. In some cases. In such a case, reducing the piezoelectric effect generated by the extraction electrode itself as much as possible is extremely useful for improving the detection accuracy as a vibration gyroscope.

The present invention greatly contributes to downsizing and high performance of a vibrating gyroscope using a piezoelectric film by solving the above technical problems. The inventors have adopted an annular or polygonal vibration gyro as a basic structure, which is considered to have a relatively small influence on the disturbance. However, in the process of reducing the size of the gyro and simplifying the manufacturing process, the noise output generated by the formation of the extraction electrode described above is a relatively small output, but it is harmful to further improve the detection accuracy. I found out. Thus, it has been found that by forming a predetermined insulating film only at a predetermined position, it is possible to significantly reduce the noise output from the extraction electrode while applying a dry process technique with high processing accuracy. The present invention was created from such a viewpoint. In the present application, the “annular or polygonal vibration gyro” is simply referred to as “ring-shaped vibration gyro”.

One vibrating gyroscope of the present invention includes an annular or polygonal vibrating body, a leg portion that flexibly supports the vibrating body and has a fixed end, an upper metal film and a lower layer formed on the vibrating body. A plurality of electrodes sandwiching the piezoelectric film in the thickness direction by the metal film and the leg portions, and the piezoelectric film and the low dielectric constant insulating film are formed by the upper metal film and the lower metal film. And a lead electrode sandwiched in the direction. In the present application, “flexible” means “to the extent that the vibrating body can vibrate”.

In this vibration gyro, the lead electrode is formed on the leg portion, and the piezoelectric film and the low dielectric constant insulating film are sandwiched between the upper metal film and the lower metal film in the thickness direction. The piezoelectric effect, reverse piezoelectric effect, and capacitance on the leg portion can be greatly reduced. That is, since the piezoelectric film and the insulating film that also function as a capacitor are connected in series, for example, when a voltage is applied to the region, it is caused by a so-called reverse piezoelectric effect as compared with the case without the above-described insulator. Since the distortion of the piezoelectric body is greatly reduced, adverse effects on the primary vibration of the vibrating body can be reduced. In addition, the capacitance obtained by synthesizing the piezoelectric film as the capacitor on the leg portion and the insulating film is significantly reduced as compared with the case where there is no insulator. As a result, even if the above disturbance occurs, only weak polarization (surface charge) is generated in the piezoelectric film on the leg portion, and the piezoelectric effect is reduced. Is suppressed. Further, as described above, when the combined capacitance of the region is significantly reduced, the intensity of the noise signal not caused by the disturbance is significantly reduced, so that the measurement accuracy of the angular velocity is improved.

One method of manufacturing a vibrating gyroscope according to the present invention is a method of manufacturing a vibrating gyroscope including a vibrating body and a leg portion that flexibly supports the vibrating body and has a fixed end. Specifically, a step of forming, by dry etching, a plurality of electrodes in which a piezoelectric film is sandwiched in the thickness direction between an upper metal film and a lower metal film above the above-described vibrating body having an annular shape or a polygonal shape. And dry etching the lead-out electrodes of the above-mentioned plurality of electrodes with the piezoelectric film and the low dielectric constant insulating film sandwiched between the upper metal film and the lower metal film in the thickness direction above the leg portion. And a process of forming by.

According to the above-described vibrating gyro manufacturing method, processing by a dry process technique is possible. Therefore, a piezoelectric element that performs driving and detection is formed on the above-described vibrating body, and a reverse piezoelectric element is formed on the leg portion. It is possible to accurately form a piezoelectric element in which the effect and the piezoelectric effect are suppressed. That is, by forming the insulating film having a low dielectric constant accurately only at a predetermined position on the leg portion by the above-described manufacturing method, the piezoelectric effect, reverse piezoelectric effect, and capacitance on the leg portion are greatly reduced. be able to. As a result, it is possible to manufacture a vibrating gyroscope that does not cause unnecessary excitation of a vibrating body, is resistant to disturbances, and further significantly reduces the intensity of noise signals that do not depend on disturbances.

According to one vibration gyro of the present invention, the reliability of the excited state of the primary vibration can be improved, and the angular velocity can be detected with high accuracy when the angular velocity occurs. Further, according to one method of manufacturing a vibrating gyroscope of the present invention, a piezoelectric element that performs driving and detection is formed on the above-described vibrating body by processing using a dry process technique, and a reverse is provided on the leg portion. It becomes possible to accurately form a piezoelectric element in which the piezoelectric effect and the piezoelectric effect are suppressed. As a result, it is possible to manufacture a vibrating gyroscope that does not cause unnecessary excitation of a vibrating body, is resistant to disturbance, and has a significantly reduced noise signal intensity that does not depend on the disturbance.

It is a front view of the structure which plays the central role of the ring-shaped vibrating gyroscope in one embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the line AA in FIG. It is sectional drawing which shows the process of the one part manufacturing process of the ring-shaped vibrating gyroscope in one embodiment of this invention. It is sectional drawing which shows the process of the one part manufacturing process of the ring-shaped vibrating gyroscope in one embodiment of this invention. It is sectional drawing which shows the process of the one part manufacturing process of the ring-shaped vibrating gyroscope in one embodiment of this invention. It is sectional drawing which shows the process of the one part manufacturing process of the ring-shaped vibrating gyroscope in one embodiment of this invention. It is sectional drawing which shows the process of the one part manufacturing process of the ring-shaped vibrating gyroscope in one embodiment of this invention. It is sectional drawing which shows the process of the one part manufacturing process of the ring-shaped vibrating gyroscope in one embodiment of this invention. It is sectional drawing which shows the process of the one part manufacturing process of the ring-shaped vibrating gyroscope in one embodiment of this invention. It is sectional drawing which shows the process of the one part manufacturing process of the ring-shaped vibrating gyroscope in one embodiment of this invention. It is sectional drawing which shows the structure of the manufacturing apparatus of the ring-shaped vibration gyroscope in one embodiment of this invention. It is sectional drawing equivalent to FIG. 2 in other embodiment of this invention. It is sectional drawing equivalent to FIG. 2 in other embodiment of this invention. It is a figure which illustrates notionally positive / negative of the electrical signal of a 1st detection electrode and a 2nd detection electrode. It is a figure explaining the vibrating body shape in other embodiment of this invention.

Embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this description, common parts are denoted by common reference symbols throughout the drawings unless otherwise specified. In the drawings, the elements of the present embodiment are not necessarily shown to scale. Moreover, in order to make each drawing easy to see, some reference numerals may be omitted.

<First Embodiment>
FIG. 1 is a front view of a structure that plays a central role in a ring-shaped vibrating gyroscope 100 according to this embodiment. FIG. 2 is a cross-sectional view taken along the line AA in FIG.

As shown in FIGS. 1 and 2, the ring-shaped vibrating gyroscope 100 of this embodiment is roughly classified into three regions. The first region is a region in which a plurality of films are stacked on an upper plane (hereinafter referred to as an upper surface) of the ring-shaped vibrating body 11 formed from the silicon substrate 10.

The plurality of electrodes 13a to 13d shown in FIG. 1 includes a first silicon oxide film 20 on an upper surface thereof, and a PZT film that is a piezoelectric film 40 is formed on platinum (Pt) that is a lower metal film 30. And a plurality of electrodes 13a to 13d formed by being sandwiched between platinum (Pt) as the upper metal film 60. In the present embodiment, the upper metal film 60 constituting the plurality of electrodes 13a to 13d is formed about 1 μm inside from the outer peripheral edge of the ring-shaped vibrating body 11 having an upper surface with a width of about 46 μm, and the width is about 21 μm. . The upper metal film 60 of the ring-shaped vibrating body 11 is formed outside a line connecting the centers between both ends of the width of the upper surface of the ring-shaped vibrating body 11 (hereinafter simply referred to as a center line).

On the other hand, extraction electrodes 14,..., 14 are formed on the upper surface of the ring-shaped vibrating body 11 in order to apply a voltage to the plurality of electrodes 13 a to 13 d or acquire an electric signal. Specifically, the first silicon oxide film 20 is provided on the upper surface of the ring-shaped vibrating body 11, and the second silicon oxide film 50 and the piezoelectric film 40 as an insulating film having a low dielectric constant are formed on the lower metal. It is formed by being sandwiched between platinum which is the film 30 and platinum which is the upper metal film 60. In the present application, the “lead electrode” means that the upper metal film 60 and the lower metal film 30 make the piezoelectric film 40 and the low dielectric constant insulating film (the second silicon oxide film 50 in this embodiment) thick. It refers to a place or region sandwiched between directions.

By the way, in this embodiment, the primary vibration of the ring-shaped vibration gyroscope 100 is excited in the in-plane cos 2θ vibration mode. Therefore, the breakdown of the plurality of electrodes 13a to 13d is the two drive electrodes 13a and 13a arranged at an angle of 180 ° from each other in the circumferential direction and the circumferential direction from the drive electrodes 13a and 13a to 90 °. Two monitor electrodes 13c, 13c arranged at an angle apart from each other, and first detection electrodes 13b, 13b and a second detection for detecting a secondary vibration generated when an angular velocity is applied to the ring-shaped vibration gyroscope 100. Electrodes 13d and 13d. In the present embodiment, the first detection electrodes 13b and 13b are arranged at an angle of 45 ° in the circumferential direction and clockwise from the drive electrodes 13a and 13a. Further, the second detection electrodes 13d and 13d are circumferentially spaced from the first detection electrodes 13b and 13b by 90 °, in other words, from the drive electrodes 13a and 13a in the circumferential direction and counterclockwise. At an angle of 45 °.

In the present embodiment, the lower metal film 30 and the upper metal film 60 have a thickness of 100 nm, and the piezoelectric film 40 has a thickness of 3 μm. The thickness of the silicon substrate 10 is 100 μm, and the thickness of the second silicon oxide film 50 is 120 nm. A hatched area indicated by V in FIG. 1 is a space or a gap where there is no structure constituting the ring-shaped vibrating gyroscope 100, and is an area provided for convenience to make the drawing easier to understand.

The second region is the leg portions 15,..., 15 connected to a part of the ring-shaped vibrating body 11. The leg portions 15,..., 15 are also formed from the silicon substrate 10. Further, on the leg portions 15,..., 15, the above-described first silicon oxide film 20, lower metal film 30, piezoelectric film 40, and second silicon oxide continuous with those on the ring-shaped vibrating body 11 are provided. A film 50 is formed on the entire upper surface of the leg portions 15. Further, an upper metal film 60 having a width of about 8 μm is formed on the center line of the upper surface of a part of the piezoelectric film 40 and the second silicon oxide film 50, thereby forming the extraction electrodes 14,. Has been.

The third region is a fixed end portion for an electrode pad provided with a support column 19 and electrode pads 18,..., 18 formed from the silicon substrate 10 connected to the leg portions 15,. 17,... In the present embodiment, the support column 19 is connected to a package portion of the ring-shaped vibrating gyroscope 100 (not shown) and serves as a fixed end. Further, the ring-shaped vibrating gyroscope 100 of the present embodiment includes electrode pad fixed ends 17,..., 17 as fixed ends other than the support column 19. The electrode pad fixed end portions 17,..., 17 are connected only to the support column 19 and the above-described package portion, and therefore do not substantially hinder the movement of the ring-shaped vibrating body 11. Further, as shown in FIG. 2, the leg portions 15,..., 15 are formed on the upper surfaces of the support columns 19 and the electrode pad fixed ends 17,. The first silicon oxide film 20, the lower metal film 30, the piezoelectric film 40, and the second silicon oxide film 50 that are continuous with those above are formed. Here, the lower metal film 30 formed on the first silicon oxide film 20 serves as the fixed potential electrode 16. Further, the upper surface of the second silicon oxide film 50 formed above the support column 19 and the electrode pad fixed ends 17,..., 17 is continuous with that above the leg portions 15,. The lead electrodes 14,..., 14 and the electrode pads 18,..., 18 formed by the upper metal film 60 are formed.

By adopting the above-described structure, the lead electrodes 14,..., 14 on the leg portions 15,... 15 are interposed between the upper metal film 60 and the lower metal film 30 and the piezoelectric film 40. The second silicon oxide film 50, which is a low dielectric constant insulating film, is sandwiched in the thickness direction. Here, the piezoelectric film 40 and the second silicon oxide film 50 also function as a capacitor. In the present embodiment, the relative dielectric constant of the piezoelectric film 40 is about 1000, whereas the relative dielectric constant of the second silicon oxide film 50 is about 4. Then, since the piezoelectric film 40 and the second silicon oxide film 50 are connected in series, the synthesized capacitance in the present embodiment is the capacitance when the second silicon oxide film 50 is not formed. To about 9%.

As a result, for example, even if the ring-shaped vibrating gyroscope 100 receives an unexpected impact (disturbance) from the outside, only weak polarization (surface charge) is present in the piezoelectric film 40 on the leg portions 15,. It does not occur and the piezoelectric effect is reduced. Therefore, the generation of noise due to such disturbance due to the extraction electrodes 14,. In other words, the ring-shaped vibrating gyroscope 100 of the present embodiment has improved impact resistance against external impacts that excite so-called bounce mode and rocking mode vibrations. Further, as described above, when the combined capacitance in the region of the extraction electrodes 14,..., 14 is significantly reduced, the intensity of the noise signal not caused by the disturbance is significantly reduced, so that the accuracy of measuring the angular velocity is improved. To do.

Furthermore, for example, even when a voltage applied to the drive electrodes 13a and 13a is applied to the region, the second silicon oxide film 50 having a small capacitance is formed, so that the extraction electrodes 14. The voltage is hardly applied to the 14 piezoelectric films 40. That is, as compared with the case where the second silicon oxide film 50 is not provided, the distortion of the piezoelectric film 40 caused by the so-called reverse piezoelectric effect is greatly reduced. As a result, adverse effects on the primary vibration of the ring-shaped vibration gyro 100 can be reduced.

In particular, in the present embodiment, the drive electrode 13a and the extraction electrodes 14,..., 14 of the detection electrodes 13b, 13d are only in the approximate center between the outer edge and the inner edge of the upper surface of the leg portions 15,. In other words, it is formed only in the vicinity of the center line). Therefore, as compared with the case where the extraction electrodes 14,..., 14 are formed on substantially the entire surface of the leg portions 15,. The excitation of vibration can be further suppressed.

By the way, in the present embodiment, the lead electrodes 14,..., 14 of both the drive electrode 13a and the detection electrodes 13b, 13d are formed only near the center line of the leg portions 15,. However, the present invention is not limited to this. For example, when the lead electrodes 14 and 14 having only the drive electrode 13 a are formed only near the center line of the leg portions 15 and 15, the lead electrodes 14 and 14 are formed on substantially the entire surface of the leg portions 15 and 15. Unnecessary excitation of primary vibration is suppressed compared to time. On the other hand, when the extraction electrodes 14,..., 14 of only the detection electrodes 13b, 13d are formed only near the center line of the leg portions 15,. The generation of unnecessary noise can be suppressed as compared with the case where the extraction electrodes 14,..., 14 are formed on substantially the entire upper surface.

On the other hand, in the drive electrode 13a and each of the detection electrodes 13b and 13d, the above-described second silicon oxide film 50 is not sandwiched between the upper metal film 60 and the lower metal film 30. Therefore, the performance of the piezoelectric film 40 is exhibited as it is.

Therefore, by using the ring-shaped vibrating gyroscope 100 of the present embodiment, it is possible to significantly suppress the generation of unnecessary noise and unnecessary excitation of primary vibration while maintaining the performance of driving the vibrating body and detecting the angular velocity. . The monitor electrodes 13c and 13c of the present embodiment sandwich the piezoelectric film 40 between the upper metal film 60 and the lower metal film 30 in the thickness direction, like the other electrodes 13a, 13b, and 13d.

Next, a method for manufacturing the ring-shaped vibrating gyroscope 100 according to this embodiment will be described with reference to FIGS. 3A to 3H. 3A to 3H are cross-sectional views corresponding to a part of the range in FIG.

First, the configuration of the etching apparatus 500 for the silicon substrate 10 shown in FIG. 4 will be described. The silicon substrate 10 to be etched is placed on a stage 521 provided on the lower side of the chamber 520. At least one gas selected from an etching gas and an organic deposit forming gas (hereinafter also referred to as a protective film forming gas) is supplied to the chamber 520 from the cylinders 522a and 522b through gas flow rate adjusters 523a and 523b, respectively. The These gases are turned into plasma by a coil 524 to which high frequency power is applied by a first high frequency power source 525. Thereafter, high-frequency power is applied to the stage 521 using the second high-frequency power source 526, so that the generated plasma is drawn into the silicon substrate 10. A vacuum pump 527 is connected to the chamber 520 via an exhaust flow rate regulator 528 to depressurize the chamber 520 and exhaust gas generated after the process. The exhaust flow rate from the chamber 520 is changed by an exhaust flow rate adjuster 528. The gas flow rate adjusters 523a and 523b, the first high frequency power supply 525, the second high frequency power supply 526, and the exhaust flow rate adjuster 528 are controlled by the control unit 529. Although FIG. 4 has been described as an apparatus configuration for etching the silicon substrate 10, it can also be used as an etching apparatus for the piezoelectric film 40 and the metal film described above. For example, if the etching apparatus 500 is used, an object other than silicon, which will be described later, can be etched by appropriately selecting the type of gas introduced into the chamber 520.

In the manufacturing method of the ring-shaped vibrating gyroscope 100 of the present embodiment, first, as shown in FIG. 3A, on the silicon substrate 10, the first silicon oxide film 20, the lower metal film 30, the piezoelectric film 40, and the second silicon An oxide film 50 is stacked. Each of the aforementioned films is formed by a known film forming means. In the present embodiment, the first silicon oxide film 20 is a thermal oxide film by a known means. The lower metal film 30 and the piezoelectric film 40 are both formed by a known sputtering method. The second silicon oxide film 50 is formed by a known sputtering method. In addition, formation of these films | membranes is not limited to the above-mentioned example, It can form also by another well-known means.

Next, a part of the second silicon oxide film 50 is etched. In the present embodiment, after a known resist film is formed on the second silicon oxide film 50, dry etching is performed based on a pattern formed by a photolithography technique, whereby the second silicon oxide film shown in FIG. 3B is obtained. 50 is formed. Here, the dry etching of the second silicon oxide film 50 is performed by using the above-described etching apparatus 500 and known etching using argon (Ar) or a mixed gas of argon (Ar) and oxygen (O 2 ). Made by condition. A known shadow mask or a lift-off method can be applied to other methods for manufacturing the second silicon oxide film 50.

Thereafter, as shown in FIG. 3C, the upper metal film 60 is uniformly laminated on the second silicon oxide film 50 and the piezoelectric film 40. Note that the upper metal film 60 of this embodiment is formed by a known sputtering method.

Next, a part of the upper metal film 60 is etched. In the present embodiment, after forming a known resist film on the upper metal film 60, the upper metal film 60 shown in FIG. 3D is formed by performing dry etching based on the pattern formed by the photolithography technique. The Here, dry etching of the upper metal film 60 was performed using the above-described etching apparatus 500 under known etching conditions using argon (Ar) or a mixed gas of argon (Ar) and oxygen (O 2 ). .

Thereafter, as shown in FIG. 3E, a part of the second silicon oxide film 50 is etched. First, as described above, the second silicon oxide film 50 is dry-etched based on a new resist film patterned by the photolithography technique. In addition, the dry etching of the second silicon oxide film 50 of the present embodiment is performed by using the above-described etching apparatus 500 and known etching using argon (Ar) or a mixed gas of argon (Ar) and oxygen (O 2 ). Made by condition. In the present embodiment, a new resist film is formed for the second silicon oxide film 50, but the residual resist film for the upper metal film 60 is used to etch the second silicon oxide film 50. It may be used as an etching mask for. In that case, a cross-sectional structure shown in FIG. 6 described later is formed. That is, if the resist film residue for the upper metal film 60 is used, the process for forming the patterned resist film can be reduced once. In the present embodiment, the second silicon oxide film 50 is formed on the piezoelectric film 40. In this case, the surface of the lower metal film 30 is not damaged by the patterning of the second silicon oxide film 50 as compared with the case where the second silicon oxide film 50 is formed by patterning on the lower metal film 30. Therefore, there is no influence on the piezoelectric film 40 that is the upper layer. As a result, it is considered that the reliability of the performance of the drive electrode 13a not forming the second silicon oxide film 50 and the detection electrodes 13b and 13d is further increased.

Thereafter, as shown in FIG. 3F, a part of the piezoelectric film 40 is etched. First, as described above, the piezoelectric film 40 is dry-etched based on a new resist film patterned by the photolithography technique. Incidentally, the dry etching of the piezoelectric film 40 of the present embodiment, by using the etching apparatus 500 described above, and argon (Ar) and C 2 F 6 gas mixed gas, or argon (Ar) and C 2 F 6 gas The etching was performed under known etching conditions using a mixed gas of CHF 3 gas. In the present embodiment, a new resist film is formed for the piezoelectric film 40, but the residual resist film for the second silicon oxide film 50 is used for etching the piezoelectric film 40. It may be used as an etching mask. This case is also a preferred embodiment because the second silicon oxide film 50 and the piezoelectric film 40 are etched only by forming a new resist film for the second silicon oxide film 50 once.

Subsequently, as shown in FIG. 3G, a part of the lower metal film 30 is etched. In the present embodiment, a part of the lower metal film 30 is formed using the remaining resist film, upper metal film 60, or second silicon oxide film 50 so that the fixed potential electrode 16 using the lower metal film 30 is formed. Is dry etched. In the present embodiment, the fixed potential electrode 16 is used as a ground electrode. The dry etching of the lower layer metal film 30 according to the present embodiment is performed under the known etching conditions using argon (Ar) or a mixed gas of argon (Ar) and oxygen (O 2 ) using the etching apparatus 500 described above. It was conducted.

By the way, in the present embodiment, the resist film, the upper metal film 60, the second silicon oxide film 50, or the piezoelectric film 40 formed for etching the piezoelectric film 40 is used as an etching mask, and then the first silicon oxide is formed. The film 20 and the silicon substrate 10 are continuously etched. Therefore, the thickness of this resist film is formed to be about 6 μm. However, even if this resist film disappears during the etching of the silicon substrate 10, the etching rate selectivity with respect to the etchant used for the silicon substrate 10 works favorably. The performance of the film 60, the second silicon oxide film 50 immediately below the upper metal film 60, the piezoelectric film 40, and the lower metal film 30 is not substantially affected.

Next, as shown in FIG. 3H, the first silicon oxide film 20 and the silicon substrate 10 are used by using the above-described etching apparatus 500 using the resist film formed for etching the piezoelectric film 40 as described above. Dry etching is performed. Dry etching of the first silicon oxide film 20 of the present embodiment was performed under known etching conditions using argon (Ar) or a mixed gas of argon (Ar) and oxygen (O 2 ).

Thereafter, through-etching is performed by a dry process of the silicon substrate 10 of the present embodiment. In the present embodiment, a method of sequentially repeating a protective film forming process in which a protective film forming gas is introduced and an etching process in which an etching gas is introduced is employed. In this embodiment, the protective film forming gas is C 4 F 8 and the etching gas is SF 6 .

In the dry etching described above, a protective substrate for preventing the stage on which the silicon substrate 10 is placed from being exposed to plasma during penetration is attached to the lower layer of the silicon substrate 10 with grease having excellent heat conductivity. Done. Therefore, for example, in order to prevent the surface in the direction perpendicular to the thickness direction of the silicon substrate 10 after penetration, in other words, the etching side surface from being eroded, the dry etching technique described in JP-A-2002-158214 is employed. This is a preferred embodiment.

As described above, after the central structure of the ring-shaped vibrating gyroscope 100 is formed by etching the silicon substrate 10 and each film laminated on the silicon substrate 10, the process of accommodating the package in a known means, and The ring-shaped vibrating gyroscope 100 is formed through the wiring process. In this embodiment, since dry etching is employed for all, a vibration gyro with high processing accuracy can be manufactured.

Next, the operation of each electrode provided in the ring-shaped vibrating gyroscope 100 will be described. As described above, in the present embodiment, the primary vibration of the in-plane cos 2θ vibration mode is excited. Since the fixed potential electrode 16 is grounded, the lower electrode film 30 formed continuously with the fixed potential electrode 16 is uniformly at 0V.

First, as shown in FIG. 1, an AC voltage of 1V P-0 is applied to the two drive electrodes 13a and 13a. As a result, the piezoelectric film 40 expands and contracts to excite primary vibration. Here, in this embodiment, since the upper metal film 60 is formed outside the center line on the upper surface of the ring-shaped vibrating body 11, the piezoelectric film 40 is not formed on the side surface of the ring-shaped vibrating body 11. The expansion and contraction motion can be converted into the primary vibration of the ring-shaped vibrating body 11.

Next, the monitor electrodes 13c and 13c shown in FIG. 1 detect the amplitude and resonance frequency of the primary vibration described above, and transmit a signal to a known feedback control circuit (not shown). The feedback control circuit of the present embodiment controls the frequency of the alternating voltage applied to the drive electrodes 13a and 13a and the natural frequency of the ring-shaped vibrating body 11 to coincide with each other, and the ring-shaped vibrating body 11 has an amplitude. Control is performed using the signals of the monitor electrodes 13c and 13c so as to obtain a constant value. As a result, the ring-shaped vibrating body 11 maintains constant vibration.

After the above-described primary vibration is excited, the angular velocity around an axis perpendicular to the plane on which the ring-shaped vibrating gyroscope 100 shown in FIG. 1 is arranged (an axis perpendicular to the paper surface, hereinafter simply referred to as “vertical axis”). In this embodiment, which is a cos 2θ vibration mode, a secondary vibration having a new vibration axis inclined at 45 ° on both sides with respect to the vibration axis of the primary vibration is generated by the Coriolis force.

This secondary vibration is detected by the two first detection electrodes 13b and 13b and the two second detection electrodes 13d and 13d. In the present embodiment, as shown in FIG. 1, the first detection electrodes 13b and 13b and the second detection electrodes 13d and 13d are arranged corresponding to the vibration axis of the secondary vibration, respectively. All the first detection electrodes 13 b and 13 b and the second detection electrodes 13 d and 13 d are formed outside the center line on the upper surface of the ring-shaped vibrating body 11. Therefore, the sign of the electrical signals of the first detection electrodes 13b and 13b and the second detection electrodes 13d and 13d generated by the secondary vibration excited by the angular velocity is reversed. As shown in FIG. 7, for example, when the ring-shaped vibrating body 11 changes to a vibrating state of the vibrating body 11 a that is vertically elliptical, the position of the first detection electrode 13 b that is disposed outside the center line. the piezoelectric film 40, while extending in the direction of the arrow shown in a 1, the piezoelectric film 40 of the position of the second detection electrode 13d disposed outside the center line is contracted in directions indicated by arrows a 2 Therefore, their electrical signals are reversed. Similarly, if you change the vibration state of the vibrating body 11b of the ring-shaped vibrating body 11 has an elliptical next, the piezoelectric film 40 of the position of the first detection electrodes 13b, while contracts in the direction of the arrow shown in B 1, the piezoelectric film 40 of the position of the second detection electrodes 13d, since extending in the direction of the arrow shown in B 2, also in this case, their electrical signal is reversed.

Here, in the arithmetic circuit 70 which is a known difference circuit, the difference between the electrical signals of the first detection electrodes 13b and 13b and the second detection electrodes 13d and 13d is calculated. As a result, the detection signal has a detection capability that is approximately twice that of either the first detection signal or the second detection signal.

<Modification Example (1) of First Embodiment>
FIG. 5 is a cross-sectional view corresponding to FIG. 2 of another ring-shaped vibrating gyroscope 200 in the present embodiment. The ring-shaped vibrating gyroscope 200 of the present embodiment has the same configuration as the ring-shaped vibrating gyroscope 100 of the first embodiment except for the position of the second silicon oxide film 50 in the first embodiment. The manufacturing method is the same as that of the first embodiment except for a part. Furthermore, the vibration mode of the present embodiment is an in-plane cos 2θ vibration mode in the same manner as in the first embodiment regarding driving and detection. Therefore, the description which overlaps with 1st Embodiment is abbreviate | omitted.

As shown in FIG. 5, the second silicon oxide film 50 of the present embodiment is formed between the piezoelectric film 40 and the lower metal film 30. One difference from the manufacturing process of the first embodiment is that before the piezoelectric film 40 is formed on the lower metal film 30, the second silicon oxide film 50 is patterned by a photolithography technique. It is a point. In this embodiment, after the step of patterning a resist film on the upper metal film 60 and the piezoelectric film 40, the second silicon oxide film 50, the lower metal film 30, and the first silicon are formed using the resist film as an etching mask. The oxide film 20 and the silicon substrate 10 are dry etched. As a result, the etching mask for the piezoelectric film 40 determines the shape of all the underlying films or substrates, so that the manufacturing process is greatly simplified. However, even if the resist film described above disappears during the etching of the silicon substrate 10, the selectivity of the etching rate with respect to the etchant used for the silicon substrate 10 is advantageous, so that the upper metal film 60 or The piezoelectric film 40 can function as an etching mask for the lower layer.

Also in this embodiment, the second silicon oxide film 50 is not formed in the region where the electrodes such as the drive electrodes 13a and 13a and the first detection electrodes 13b and 13b are formed. On the other hand, in the region of the extraction electrode 14, the second silicon oxide film 50 and the piezoelectric film 40 are sandwiched between the upper metal film 60 and the lower metal film 30 in the thickness direction. Therefore, the ring-shaped vibrating gyroscope 200 of the present embodiment also has the same effect as that of the first embodiment.

<Modification (1) of the first embodiment>
FIG. 6 is a cross-sectional view corresponding to FIG. 2 of another ring-shaped vibrating gyroscope 300 according to this embodiment. The ring-shaped vibrating gyroscope 300 of the present embodiment has the same configuration as the ring-shaped vibrating gyroscope 100 of the first embodiment, except for the patterning of the second silicon oxide film 50 in the first embodiment. The manufacturing method is the same as that of the first embodiment except for a part. Furthermore, the vibration mode of the present embodiment is an in-plane cos 2θ vibration mode in the same manner as in the first embodiment regarding driving and detection. Therefore, the description which overlaps with 1st Embodiment is abbreviate | omitted.

As shown in FIG. 6, the second silicon oxide film 50 of the present embodiment has substantially the same shape as the upper metal film 60 in plan view. The difference from the manufacturing process of the first embodiment is that the residual portion of the resist film used in etching the upper metal film 60 is used when the second silicon oxide film 50 is etched.

Also in this embodiment, the second silicon oxide film 50 is not formed in the region where the electrodes such as the drive electrodes 13a and 13a and the first detection electrodes 13b and 13b are formed. On the other hand, in the region of the extraction electrode 14, the second silicon oxide film 50 and the piezoelectric film 40 are sandwiched between the upper metal film 60 and the lower metal film 30 in the thickness direction. Therefore, the ring-shaped vibrating gyroscope 300 of this embodiment also has the same effect as that of the first embodiment.

By the way, in each above-mentioned embodiment, although the drive electrode and the detection electrode were formed outside the center line, it is not limited to this. Even when the drive electrode and the detection electrode are arranged on the inner side of the center line, the same effect as the effect of the present invention can be obtained.

In addition, although each of the above-described embodiments has been described with a vibrating gyroscope using an annular vibrating body, a polygonal vibrating body may be used instead of the annular ring. For example, even with a regular polygonal vibrator such as a regular hexagon, a regular octagon, a regular dodecagon, and a regular icosahedron, substantially the same effect as the effect of the present invention is exhibited. Moreover, a vibrating body such as the octagonal vibrating body 111 of the ring-shaped vibrating gyroscope 400 shown in FIG. 8 may be used. If a polygonal vibrating body that is a point target shape in a front view of the vibrating body is employed, it is preferable from the viewpoint of stability during vibration of the vibrating body. Further, the “annular shape” includes an elliptical shape.

In each of the above-described embodiments, the lead electrode 14 employs a configuration in which the piezoelectric film 40 and the second silicon oxide film 50 are sandwiched between the upper metal film 60 and the lower metal film 30. It is not limited. Other low dielectric constant insulating films, such as silicon oxynitride film, silicon nitride film, fluorocarbon film, or polyimide film, can be applied as an alternative to the silicon oxide film. Further, even when a plurality of types of insulating films are applied among the above-described insulating films having a low dielectric constant, the same effects as the effects of the present invention can be obtained.

On the other hand, for example, even if a silicon nitride film or a silicon oxynitride film is formed instead of the first silicon oxide film of each of the above-described embodiments, an effect substantially similar to the effect of the present invention is exhibited. .

Furthermore, in each of the embodiments described above, a ring-shaped vibrating gyroscope using silicon as a base material is employed, but the present invention is not limited to this. For example, the base material of the vibration gyro may be silicon germanium. As described above, modifications that exist within the scope of the present invention including other combinations of the embodiments are also included in the scope of the claims.

The present invention can be widely applied as a part of various devices as a vibrating gyroscope.

Claims (7)

  1. An annular or polygonal vibrator,
    A leg portion that flexibly supports the vibrator and has a fixed end;
    A plurality of electrodes formed on the vibrating body and sandwiching the piezoelectric film between the upper metal film and the lower metal film in the thickness direction;
    A vibration gyro comprising: an extraction electrode formed on the leg portion and sandwiching a piezoelectric film and a low dielectric constant insulating film in the thickness direction by the upper metal film and the lower metal film.
  2. The plurality of electrodes include a detection electrode for detecting vibration in a plane parallel to a plane on which the vibrating body is disposed;
    The vibrating gyroscope according to claim 1, wherein the extraction electrode of the detection electrode is formed only at a substantially center between an outer edge and an inner edge of the upper surface of the leg portion.
  3. The plurality of electrodes include drive electrodes for exciting vibrations in a plane parallel to a plane on which the vibrating body is disposed,
    The vibrating gyroscope according to claim 1, wherein the extraction electrode of the drive electrode is formed only at a substantially center between an outer edge and an inner edge of the upper surface of the leg portion.
  4. The vibrating gyroscope according to claim 1, wherein the insulating film is at least one insulating film selected from the group consisting of a silicon oxide film, a silicon oxynitride film, a silicon nitride film, a fluorocarbon film, and a polyimide film.
  5. A vibration gyro manufacturing method comprising a vibrating body and a leg portion that flexibly supports the vibrating body and has a fixed end,
    Forming a plurality of electrodes sandwiching a piezoelectric film in the thickness direction between an upper metal film and a lower metal film by dry etching above the annular or polygonal vibrator,
    The lead-out electrodes of the plurality of electrodes, in which the piezoelectric film and the low dielectric constant insulating film are sandwiched in the thickness direction between the upper metal film and the lower metal film, are formed by dry etching above the leg portion. A method for manufacturing a vibrating gyroscope.
  6. The method for manufacturing a vibrating gyroscope according to claim 5, wherein the insulating film is formed on the piezoelectric film formed above the leg portion.
  7. The method for manufacturing a vibrating gyroscope according to claim 5, wherein the extraction electrode is formed by dry etching only a part of the upper metal film or a part of the insulating film in addition thereto.
PCT/JP2009/057342 2008-06-23 2009-04-10 Vibrating gyroscope using piezoelectric film and method for manufacturing the same WO2009157246A1 (en)

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JP2010210605A (en) * 2009-02-11 2010-09-24 Sumitomo Precision Prod Co Ltd Vibratory gyro using piezoelectric film and method for manufacturing the same
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