JP4441729B2 - Electronics - Google Patents

Description

  The present invention relates to, for example, an angular velocity sensor used for camera shake detection of a video camera, motion detection in a virtual reality device, direction detection in a car navigation system, and the like, and more specifically, a small vibration type having a cantilever vibrator. The present invention relates to an electronic device including a gyro sensor element.

  Conventionally, as a commercial angular velocity sensor, a cantilever vibrator is vibrated at a predetermined resonance frequency, and the angular velocity is detected by detecting a Coriolis force generated by the influence of the angular velocity with a piezoelectric element or the like. A vibration type gyro sensor (hereinafter referred to as a vibration type gyro sensor) is widely used.

  The vibration-type gyro sensor has advantages such as a simple mechanism, a short start-up time, and low-cost manufacturing. For example, it is mounted on electronic devices such as a video camera, a virtual reality device, and a car navigation system. It is used as a sensor for motion detection and direction detection.

  The vibration type gyro sensor is required to be downsized and improved in accordance with downsizing and high performance of electronic devices to be mounted. For example, in order to increase the functionality of electronic devices, there is a demand to reduce the size by mounting a vibration gyro sensor on one substrate in combination with various sensors used for other purposes.

  However, the vibration type gyro sensor has produced a vibrator by cutting and shaping a piezoelectric material by machining, so that there is a limit to the processing accuracy for downsizing as described above, and the desired performance is achieved. There was a problem that I could not get.

  In view of this, a piezoelectric vibration angular velocity meter, that is, a vibration type gyro sensor, in which a vibrator is manufactured by forming a thin film of a piezoelectric material on a single crystal silicon substrate and miniaturized has been devised (for example, Patent Document 1, Patent). Reference 2). In addition, a cantilever vibrator formed by a silicon processing process has a drive electrode in the longitudinal direction of the vibrator, and a pair of detection electrodes in parallel without contacting the drive electrode so as to sandwich the drive electrode. A formed vibration type gyro sensor has been devised. (For example, refer to Patent Document 3).

  Such a vibration type gyro sensor is required to detect an angular velocity with higher sensitivity and stable resonance characteristics.

Japanese Patent Application Laid-Open No. 8-261762 JP-A-8-327364 Japanese Patent Laid-Open No. 7-113643

  By the way, in order to make the vibration type gyro sensor have high sensitivity and stable resonance characteristics, it is necessary to increase a so-called Q value, which is a mechanical quality factor that defines the resonance state of the vibrator.

  The Q value is a constant that represents the degree of sharpness of the resonance characteristics when the vibrator of the vibration type gyro sensor causes natural vibration. The Q value is used as a constant representing the quality of the resonance system in resonance phenomena in the electric and electronic fields and mechanical vibrations such as vibrations of vibrators. The Q value in the vibration type gyro sensor is determined by the material forming the vibrator, the fixing method of the vibrator, and the like.

  For example, when the Q value is large, the amplitude grows only when vibration matching the resonance frequency is received from the outside, and it takes time to grow and attenuate the vibration. In other words, it can be said that it is in a state in which it is hardly affected by the outside world.

  On the other hand, when the Q value is small, it reacts to vibrations having a frequency slightly different from the resonance frequency, and the vibrations grow and decelerate quickly. In other words, it can be said that it is easily affected by the outside world.

  Therefore, by increasing the Q value as described above, the resonance characteristics of the vibration type gyro sensor can be stabilized and a highly sensitive sensor element can be obtained.

  Usually, the vibration type gyro sensor is packaged in a desired package for the purpose of protecting the vibrator and facilitating handling when incorporated in an external device. At this time, there is a problem that air damping becomes strong and the characteristics deteriorate due to the space formation state around the vibrator after packaging and the influence of the package.

  As a method for preventing such air damping, there is a method of vacuum-packaging a vibration type gyro sensor in a package, but there is a problem that it is very time-consuming and requires a lot of cost.

  Accordingly, the present invention has been devised to solve the above-described problems, and by stably defining the space around the vibrator of the packaged vibration type gyro sensor element, stable resonance characteristics can be obtained. An object of the present invention is to provide a small electronic device including a vibration gyro sensor element with high sensitivity at low cost.

In order to achieve the above-described object, an electronic apparatus according to the present invention includes a quadrangular columnar cantilever vibrator formed of single crystal silicon having a lower electrode, a piezoelectric thin film, and an upper electrode, and the piezoelectric thin film piezoelectric An electronic device in which a vibration-type gyro sensor element that detects an angular velocity using an effect is packaged in the air using a cover material and an IC substrate, and the upper electrode applies a voltage that vibrates the vibrator A first detection electrode and a second detection electrode formed in the longitudinal direction of the vibrator in parallel with each other, in contact with the drive electrode, with the drive electrode sandwiched between the drive electrode formed in the longitudinal direction of the vibrator. detection electrodes and being formed from a, distance of a state that is not vibration of the vibrator, from the lower surface of the distance and the transducer from the top surface of the transducer to the cover member to the IC substrate When the vibrator is self-excited and vibrated in the thickness direction by applying a voltage between the lower electrode and the upper electrode, the maximum displacement amount of 2. is the displacement amount when the vibrator is most vibrated. A space of 5 times or more is provided, and the distance from the side wall surface of the vibrator to the wall surface formed to face the side wall surface over the entire side wall surface is twice or more the width of the vibrator. A space is provided .

The present invention is a vibrating gyroscope including a quadrangular columnar cantilever vibrator formed of single crystal silicon having a lower electrode, a piezoelectric thin film, and an upper electrode, and detecting angular velocity using the piezoelectric effect of the piezoelectric thin film. An electronic device in which a sensor element is packaged in the air using a cover material and an IC substrate , wherein the upper electrode is a drive electrode formed in a longitudinal direction of the vibrator for applying a voltage for vibrating the vibrator And a first detection electrode and a second detection electrode formed in parallel with each other in the longitudinal direction of the vibrator without being in contact with the drive electrode. , in a state where no vibration of the vibrator, the distance from the lower surface of the distance and the transducer from the top surface of the transducer to the cover member to the IC substrate, the lower electrode, the voltage between the upper electrode Applied to the time obtained by self-excited vibration in the thickness direction of the above oscillator, the maximum displacement amount of 2.5 times or more and the space is provided which is a displacement amount when the above-described oscillator is the most vibrating, the By providing a space where the distance from the side wall surface of the vibrator to the wall surface formed so as to face the side wall surface over the entire side wall surface is at least twice the width of the vibrator, vacuum grinding is provided. The mechanical quality factor of the packaged vibration type gyro sensor element, the so-called Q value, is affected by the shape of the space around the vibrator, without requiring a lot of labor and cost. Can be as high as possible. Therefore, it is possible to provide a small electronic device that exhibits stable resonance characteristics and includes a highly sensitive vibration type gyro sensor element at low cost.

  The best mode for carrying out an electronic apparatus according to the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is an external perspective view of a vibration type gyro sensor element 10 included in an angular velocity sensor 50 to which the present invention is applied, and FIG. 2 is a diagram illustrating an example of a circuit configuration of the angular velocity sensor 50. For the sake of explanation, a part of the vibration type gyro sensor element 10 shown in FIG.

  As shown in FIG. 1, the vibration gyro sensor element 10 includes a so-called cantilever vibrator 11. The vibrator 11 is formed as a beam having the other end fixed by providing a peripheral space 12 around the vibrator 11 from an element having a thickness t1, a length t2, and a width t3 cut out from the silicon single crystal substrate. The vibrator 11 has a space width of t7b and t7c in a direction perpendicular to the longitudinal direction and a space width of t7a in the longitudinal direction. Note that t7b and t7c have the same length.

  Such a vibrator 11 is formed in a quadrangular prism shape in which a cross-sectional shape when cut along a plane perpendicular to the longitudinal direction is a right-angled quadrilateral.

  The size of the vibration-type gyro sensor element 10 is, for example, as described above, where the element thickness is t1, the element length is t2, and the element width is t3, t1 = 300 μm, t2 = 3 mm, t3 = 1 mm. can do. Further, as shown in FIG. 3, the size of the vibrator 11 at this time is, for example, t4 = 100 μm, t5 when the thickness of the vibrator is t4, the length of the vibrator is t5, and the width of the vibrator is t6. = 2.5 mm and t6 = 100 μm.

  FIG. 4 is a plan view of the vibration type gyro sensor element 10. As shown in FIG. 4, a reference electrode 4a and a piezoelectric body 5a are sequentially stacked on the vibrator 11, and a driving electrode 6a and a pair of detection electrodes 6b are sandwiched between the driving electrode 6a and the piezoelectric body 5a. , 6c are formed in parallel with each other along the longitudinal direction of the vibrator 11 so as not to contact each other. The drive electrode 6a, the detection electrodes 6b and 6c, and the reference electrode 4a are provided with wiring connection terminals A, B, C, and D, respectively.

The piezoelectric body 5a is a thin film made of, for example, piezoelectric ceramics such as lead zirconate titanate (PZT), crystal, piezoelectric single crystal such as LaTaO _3, and the like.

  Such a vibration type gyro sensor element 10 operates by being connected to the IC circuit 40 shown in FIG. 2, and functions as an angular velocity sensor 50 that detects Coriolis force generated according to the angular velocity.

  The IC circuit 40 includes an adder circuit 41, an amplifier circuit 42, a phase shift circuit 43, an AGC (Automatic Gain Control) 44, a differential amplifier circuit 45, a synchronous detection circuit 46, and a smoothing circuit 47. Yes.

  The pair of detection electrodes 6b and 6c of the vibration type gyro sensor element 10 are connected to the adder circuit 41 and the differential amplifier circuit 45 via the wiring connection terminals B and C, respectively. Further, the drive electrode 6 a of the vibration type gyro sensor element 10 is connected to the output end of the AGC 44 via the wiring connection terminal A.

  In the angular velocity sensor 50, a so-called phase shift oscillation circuit is configured by the adder circuit 41, the amplifier circuit 42, the phase shift circuit 43, the AGC 44, and the vibration type gyro sensor element 10, and the vibration type gyro sensor element 10 is configured by this phase shift oscillation circuit. A voltage is applied between the reference electrode 4a and the drive electrode 6a to cause the vibrator 11 to self-oscillate. The vibration direction of the vibrator 11 is the thickness direction of the vibrator 11.

  Further, in the angular velocity sensor 50, the output terminal of the adder circuit 41 and the differential amplifier circuit 45 in which the pair of detection electrodes 6b and 6c are connected via the wiring connection terminals B and C are connected to the synchronous detection circuit 46, The synchronous detection circuit 46 is connected to the smoothing circuit 47, and these and the piezoelectric body 5a function as a detection unit that detects the angular velocity of the vibrator 11.

  That is, in the angular velocity sensor 50 shown in FIG. 2, the angular velocity is applied in the longitudinal direction of the vibrator 11 when the vibrator 11 of the vibration type gyro sensor element 10 is self-excited by the phase-shift oscillation circuit described above. Then, the Coriolis force generated in the direction perpendicular to the vibration direction is detected by the piezoelectric body 5 a, output as signals having opposite polarities from the detection electrodes 6 b and 6 c, and input to the differential amplifier circuit 45. The output amplified by the differential amplifier circuit 45 is input to the synchronous detection circuit 46, where synchronous detection is performed. At this time, the output from the adder 41 is supplied to the synchronous detection circuit 46 as a synchronous signal in order to perform synchronous detection. The output from the synchronous detection circuit 46 is output as an angular velocity signal that is a DC signal obtained by detecting the Coriolis force generated in the vibrator 11 via the smoothing circuit 47.

  As described above, in the angular velocity sensor 50, the vibrator 11 is vibrated using the piezoelectric body 5a, the Coriolis force generated in the vibrator 11 is detected by the piezoelectric body 5a, and the Coriolis force detected by the piezoelectric body 5a is detected. Based on this, the angular velocity can be detected.

<Example>
Subsequently, as an example, the vibration gyro sensor element 10 described above is actually manufactured, and a manufacturing method thereof will be described.

  As described above, the vibration type gyro sensor element 10 shown in FIG. 1 is formed by processing a single crystal silicon substrate.

FIG. 5 is a plan view of the single crystal silicon substrate 1 used when forming the vibration-type gyro sensor element 10, and FIG. 6 is a cross-sectional view of the single crystal silicon substrate 1 shown in FIG. . One main surface 1B and the other main surface 1A of the single crystal silicon substrate 1 are thermally oxidized to form a SiO ₂ film as a protective film during crystal anisotropic etching described later.

  As shown in FIG. 5, the single crystal silicon substrate 1 used in the vibration type gyro sensor element 10 has a {100} plane orientation of one main surface 1B of the single crystal silicon substrate 1, and a side surface 1C as shown in FIG. Is cut out so that the plane orientation of {110} is. Since the other main surface 1A is parallel to the one main surface 1B, the surface orientation of the other main surface 1A is also {100}.

  However, “{}” is a symbol for collectively representing equivalent plane orientations having different directions. For example, {100} is a generic name for (100), (010), (001), and the like. Shall.

  Thus, the size of the single crystal silicon substrate 1 cut out by defining the crystal plane orientation is arbitrarily set according to the apparatus provided in the processing process line. For example, in the present embodiment, a single crystal silicon substrate 1 having a length × width of 3 cm × 3 cm square is used.

  Further, the thickness of the single crystal silicon substrate 1 is determined by workability and the price of the substrate, but may be at least equal to or greater than the thickness of the vibrator 11 formed in the vibration type gyro sensor element 10. For example, in this embodiment, as shown in FIG. 3, the thickness t4 of the vibrator 11 is set to 100 μm, so the thickness of the single crystal silicon substrate 1 is set to 300 μm, which is three times.

As shown in FIG. 6, thermal oxide films 2A and 2B, which are SiO ₂ films, are formed on the other main surface 1A and one main surface 1B of the single crystal silicon substrate 1 by thermal oxidation. The thermal oxide films 2A and 2B function as protective films when performing crystal anisotropic etching described later. The thickness of the thermal oxide films 2A and 2B is arbitrary, but is 0.1 μm in this embodiment. In addition, the single crystal silicon substrate 1 used in this embodiment adopts an N type as a conduction type, but can be arbitrarily determined.

  In the following description, in the single crystal silicon substrate 1, the other main surface 1A side on which the thermal oxide film 2A is formed is the front surface, and the one main surface 1B side on which the thermal oxide film 2B is formed is the back surface.

  Using such a single crystal silicon substrate 1, first, the thermal oxide film 2 </ b> B formed on the back surface of the single crystal silicon substrate 1 where crystal anisotropic etching is performed is removed by photoetching.

  Photoetching is largely divided into a process (photolithography) for forming a resist film pattern with openings to be removed on the thermal oxide film 2B and a process (etching) for removing the thermal oxide film 2B using the pattern. Separated.

  FIG. 7 is a plan view showing a state in which the resist film pattern 3 is formed on the thermal oxide film 2B of the single crystal silicon substrate 1, and FIG. 8 shows the single crystal silicon substrate 1 shown in FIG. It is sectional drawing at the time of cut | disconnecting.

  As shown in FIG. 7, in the resist film pattern 3 formed on the thermal oxide film 2B, the length in the direction perpendicular to the {110} plane is t8, and the length in the direction parallel to the {110} plane is t9. The openings 3a having a rectangular shape of t8 × t9 are regularly arranged with a predetermined interval. In the present embodiment, a pattern in which 3 × 5 openings 3a are formed. Each of the openings 3 a becomes one vibration type gyro sensor element 10.

  This resist film pattern 3 is made of a photosensitive resin after pre-baking to remove moisture by heating the thermal oxide film 2B with microwaves in exactly the same manner as photolithography used in the semiconductor processing process. It is formed by applying a photoresist film, exposing the photoresist film to a mask on which the pattern for forming the opening 3a is formed, and developing the mask.

  T8 and t9 which determine the size of the opening 3a are the shape of the vibrator 11 of the vibration type gyro sensor element 10, the thickness t1 of the single crystal silicon substrate 10, and the spatial widths t7a, t7b of the vibrator shown in FIG. determined by t7c. Specific values of t8 and t9 will be described later in detail.

  In this manner, as shown in FIG. 8, a resist film pattern 3 is formed on the thermal oxide film 2B of the single crystal silicon substrate 1.

  Subsequently, the thermal oxide film 2B in the opening 3a formed by the resist film pattern 3 is removed by etching. FIG. 9 is a plan view showing a state of the single crystal silicon substrate 1 from which only the thermal oxide film 2B at the opening 3a formed by the resist film pattern 3 has been removed, and FIG. 10 is shown in FIG. It is sectional drawing at the time of cut | disconnecting the single crystal silicon substrate 1 by XX line.

  Etching for removing the thermal oxide film 2B may be physical etching such as ion etching or wet etching, but considering the smoothness of the interface of the single crystal silicon substrate 1, only the thermal oxide film 2B is removed. Wet etching is preferred.

  In this example, ammonium fluoride was used as a chemical solution for wet etching. However, in the case of wet etching, when etching is performed for a long time, etching proceeds from the side surface of the opening portion, so-called side etching becomes large. Therefore, the etching is finished so that only the opening portion 3a of the thermal oxide film 2B is removed. Control time accurately.

  In this way, the thermal oxide film 2B located in the opening 3a of the resist film pattern 3 is removed as shown in FIG.

  Subsequently, by removing the thermal oxide film 2B by the above-described etching, single crystal silicon in which the {100} plane is exposed at the opening 2Ba of t8 × t9 having the same size as the opening 3a of the resist film pattern 3 The substrate 1 is subjected to wet etching, and the thickness of the single crystal silicon substrate 1 is cut down to t4 which is the thickness of the vibrator 11.

  FIG. 11 is a plan view showing a state in which the thermal oxide film 2B is removed from the single crystal silicon substrate 1 and only the opening 2Ba having a size of t8 × t9 where the {100} plane is exposed is etched. 12 is a cross-sectional view of the single crystal silicon substrate 1 shown in FIG. 11 taken along the line XX. FIG. 13 is an enlarged view of the area A shown in FIG.

  Here, the wet etching performed on the single crystal silicon substrate 1 is crystal anisotropic etching utilizing the property that the etching rate depends on the crystal direction. When the anisotropic oxide etching is performed on the opening 2Ba where the thermal oxide film 2B is removed and the {100} plane is exposed, an angle of about 55 degrees with respect to the {100} plane is obtained as shown in FIG. The {111} plane that becomes the plane orientation appears, and the etching is finished so as to ensure t4 which is the thickness of the vibrator 11, so that a so-called diaphragm shape is obtained.

  In general, single crystal silicon has an etching rate dependency with respect to a crystal direction that a {111} plane is very difficult to be etched compared to a {100} plane because of its crystal structure. Specifically, the etching rate of {100} plane of single crystal silicon is about 200 times the etching rate of {111} plane.

  Etching solutions that can be used when crystal anisotropic etching is performed on single crystal silicon include TMAH (tetramethylammonium hydroxide), KOH (potassium hydroxide), EDP (ethylenediamine-pyrocatechol-water), humanradine, etc. It is.

  In this example, a TMAH (tetramethylammonium hydroxide) 20% solution in which the selectivity of the etching rate between the thermal oxide film 2A and the thermal oxide film 2B is larger is used as the etchant. During etching, the temperature is maintained at 80 ° C. while stirring the etching solution, and the diaphragm depth t10 is 200 μm over 6 hours, that is, the thickness t11 of the single crystal silicon substrate 1 remaining after etching is the thickness t4 of the vibrator 11. Etching was performed until the thickness became 100 μm.

  Here, in order to perform crystal anisotropic etching, numerical values of t8 and t9 that define the size of the opening 3a formed by the resist film pattern 3 described with reference to FIG. 7 will be specifically described.

  The width t9 of the opening 3a, that is, the width of the diaphragm after etching is t9 = t9a + t9b + t9c as shown in FIG.

  t9c can be expressed as t9c = t6 + t7b + t7c using the width t6 of the vibrator 11 shown in FIG. 3 and the space widths t7b and t7c of the surrounding space 12 formed around the vibrator 11 shown in FIG. .

  Further, t9a and t9b have the same length, and as shown in FIG. 13, the {111} plane that appears when the crystal anisotropic etching is performed and the back surface of the single crystal silicon substrate 1 {100} Since the surface forms an angle of 55 degrees, it can be expressed as t9a = t9b = t10 × 1 / tan55 ° using the depth t10 of the diaphragm.

  Accordingly, the width t9 of the opening 3a is t9 = {t10 × 1 / tan55 °} × 2 + (t6 + t7b + t7c). Here, when t6 = 100 μm, t7b = t7c = 200 μm, and t10 = 200 μm, t9 = 780 μm.

  When the crystalline anisotropic etching as described above is performed, a {111} plane that forms an angle of 55 degrees with the {100} plane appears in the t8 direction in the opening 3a of the resist film pattern 3 as in the t9 direction. Therefore, the length t8 of the opening, that is, the length of the diaphragm after etching is the length t5 of the vibrator 11 shown in FIG. 3, and the space of the surrounding space 12 formed around the vibrator 11 shown in FIG. Using the width t7a, t8 = {t10 × 1 / tan55 °} × 2 + (t5 + t7a). Here, when t5 = 2.5 mm, t7a = 200 μm, and t10 = 200 μm, t8 = 2980 μm.

  In the above description, the entire single crystal silicon substrate 1 has been described with reference to the drawings. However, for convenience of description, in the following description, only the single crystal silicon substrate 1 on which the diaphragm shown as the region W in FIG. This will be explained using. Further, in the following description, since it is a processing process for the thermal oxide film 2A side, a plan view with the thermal oxide film 2A side as a top surface and a cross-sectional view of this plan view cut at a predetermined position is used. Explain.

  Specifically, when the single crystal silicon substrate 1 on which the diaphragm in the region W shown in FIG. 11 is formed has the thermal oxide film 2A as an upper surface, a plan view as shown in FIG. Is as shown in FIG.

  Subsequently, a lower electrode film, a piezoelectric film, and an upper electrode film are formed on the thermal oxide film 2A to form the reference electrode 4a, the piezoelectric body 5a, the drive electrode 6a, and the detection electrodes 6b and 6c shown in FIG. To do. When the lower electrode film 4, the piezoelectric film 5, and the upper electrode film 6 are sequentially formed on the thermal oxide film 2A of the single crystal silicon substrate 1, the plan view is as shown in FIG. The cut sectional view is as shown in FIG.

  In this example, the lower electrode film 4, the piezoelectric film 5, and the upper electrode film 6 were all formed using a magnetron sputtering apparatus.

  First, the lower electrode film 4 is formed on the thermal oxide film 2A. In this example, first, the conditions of the magnetron sputtering apparatus were set to gas pressure: 0.5 Pa, RF power: 1 kW, and titanium (Ti) was formed on the thermal oxide film 2A so as to have a film thickness of 50 nm. Subsequently, platinum (Pt) was formed on the formed titanium (Ti) so that the film thickness was 200 nm under the apparatus conditions of gas pressure: 0.5 Pa and RF power: 0.5 kW. That is, the lower electrode film 4 is formed by depositing titanium and platinum to the above thickness.

Next, a piezoelectric film 5 is formed on the lower electrode film 4. In this example, first, Pb _{(1 + x)} (Zr _0.53 Ti _0.47 ) O _3-y oxide was used as a target, and the conditions of the magnetron sputtering apparatus were normal temperature, gas pressure: 0.7 Pa, RF power. : A piezoelectric thin film of lead zirconate titanate (PZT) was formed on platinum (Pt) formed as the lower layer electrode 4 so as to have a thickness of 1 μm at 0.5 kW. Subsequently, the single crystal silicon substrate 1 on which lead zirconate titanate (PZT) is formed is placed in an electric furnace, and a crystallization heat treatment is performed in an oxygen atmosphere at 700 ° C. for 10 minutes to form the piezoelectric film 5. did.

  Finally, the upper electrode film 6 is formed on the piezoelectric film 5. In this example, the conditions of the magnetron sputtering apparatus were such that the gas pressure was 0.5 Pa and the RF power was 0.5 kW, and platinum (Pt) was formed on the piezoelectric film 5 so that the film pressure was 200 nm.

  Next, the upper electrode film 6 is processed to form drive electrodes 6a and detection electrodes 6b and 6c. 18 is a plan view showing a state of the single crystal silicon substrate 1 on which the drive electrodes 6a and the detection electrodes 6b and 6c are formed. FIG. 19 is a cross-sectional view of the single crystal silicon substrate 1 shown in FIG. It is sectional drawing at the time of doing.

  The drive electrode 6 a is an electrode for applying a voltage for driving the vibrator 11 as described above, and is formed to be the center of the vibrator 11. Further, the detection electrodes 6b and 6c are electrodes for detecting the Coriolis force generated in the vibrator 11 as described above, and in parallel with the drive electrode 6a so as to sandwich the drive electrode 6a, and so as not to contact with each other. Formed on the vibrator 11.

As shown in FIG. 18, the drive electrode 6a and the detection electrodes 6b, 6c are formed so that one end thereof coincides with the root line R that is the root of the vibrator 11, and the one end of each electrode is formed. Terminal junctions 6a ₁ , 6b ₁ , 6c ₁ are formed in the parts, respectively.

In the present embodiment, the width t13 of the drive electrode 6a is 50 μm, the width t14 of the detection electrodes 6b and 6c is 10 μm, the length t12 of the drive electrode 6a and the detection electrodes 6b and 6c is 2 mm, and the drive electrode 6a of the detection electrodes 6b and 6c. The distance t15 between each of the two was 5 μm. The drive electrode 6a and the detection electrodes 6b and 6c can be designed to have any size as long as they are formed on the vibrator 11. In this embodiment, the length t16 of each of the terminal joint portions 6a ₁ , 6b ₁ , 6c ₁ is 50 μm, and the width t17 is 50 μm.

In this embodiment, the drive electrode 6a, the detection electrodes 6b and 6c, and the terminal junctions 6a ₁ , 6b ₁ and 6c ₁ are formed on the upper electrode film 6 by using a photolithography technique, and then ion ions are formed. An unnecessary portion of the electrode film 6 was removed by etching.

The present invention is not limited to the method for forming the drive electrode 6a, the detection electrodes 6b and 6c, and the terminal joints 6a ₁ , 6b ₁ and 6c _1, and various methods other than the above-described methods can be used. Can be applied.

  Next, the piezoelectric film 5 is processed to form a piezoelectric body 5 a on the vibrator 11. 20 is a plan view showing a state of the single crystal silicon substrate 1 on which the piezoelectric body 5a is formed by processing the piezoelectric film 5, and FIG. 21 shows the single crystal silicon substrate 1 shown in FIG. It is sectional drawing at the time of cut | disconnecting.

  The piezoelectric body 5a may have any shape as long as it completely covers the drive electrode 6a and the detection electrodes 6b and 6c formed by processing the upper electrode film 6.

  In this embodiment, the length t18 of the piezoelectric body 5a is 2.2 mm, and the width t19 is 90 μm. The piezoelectric body 5 a having such a size is arranged such that its center coincides with the center of the vibrator 11 and one end thereof coincides with the root line R that is the root of the vibrator 11.

The width t18 of the piezoelectric body 5a needs to be equal to or smaller than the width t4 of the vibrator 11. Further, in this embodiment, the piezoelectric film 5 is provided under the terminal joint portions 6a ₁ , 6b ₁ , 6c ₁ described above, and a width of 5 μm is provided from each outer periphery of the terminal joint portions 6a ₁ , 6b ₁ , 6c _1. It is left. The piezoelectric film 5 remaining under the terminal joints 6a ₁ , 6b ₁ , 6c ₁ is arbitrarily set depending on the overall shape size of the vibration type gyro sensor element 10.

In this embodiment, a photolithography technique is used to form a resist film pattern in the shape of the piezoelectric film 5 to be left under the piezoelectric body 5a and the terminal joints 6a ₁ , 6b ₁ , 6c ₁ , and then wet using a hydrofluoric acid solution. The piezoelectric body 5a was formed by removing the unnecessary portion of the piezoelectric film 5 by etching.

  As described above, in this embodiment, the technique for removing unnecessary portions of the piezoelectric film 5 in order to form the piezoelectric body 5a is wet etching. However, the present invention is not limited to this, and is physically limited. A removal method using ion etching, which is an effective etching, or a removal method using reactive ion etching (RIE) that performs etching by chemical action and physical action can be applied.

  Next, the lower electrode film 4 is processed to form the reference electrode 4 a on the vibrator 11. FIG. 22 is a plan view showing a state of the single crystal silicon substrate 1 on which the reference electrode 4a is formed by processing the lower electrode film 4, and FIG. 23 shows the single crystal silicon substrate 1 shown in FIG. It is sectional drawing at the time of cut | disconnecting by.

  The reference electrode 4a may have any shape as long as it completely covers the piezoelectric body 5a formed by processing the piezoelectric film 5.

  In this example, the length t20 of the reference electrode 4a was 2.3 mm, and the width t21 was 94 μm. Such a reference electrode 4 a has its center coincident with the center of the vibrator 11 and one end thereof coincides with the root line R that is the root of the vibrator 11.

  The width t20 of the reference electrode 4a needs to be equal to or smaller than the width t4 of the vibrator 11. In this embodiment, the lower electrode film 4 under the piezoelectric film 5 that has not been removed as described above is left with a width of 5 μm from the outer periphery of the piezoelectric film 5. This width is arbitrarily set depending on the overall shape size of the vibration type gyro sensor element 10.

  Further, in order to electrically connect the reference electrode 4a and the outside, a wiring connection terminal D is formed by the lower electrode film 4 as shown in FIG. As described above, the reference electrode 4 a and the wiring connection terminal D are electrically connected via the lower electrode film 4 left under the piezoelectric film 5.

  In this embodiment, since it is assumed that the electrical connection between the vibration type gyro sensor element 10 and the outside is performed by wire bonding, a terminal portion to be actually wired of the wiring connection terminal D is necessary at the time of wire bonding. Secure only the required area.

  In this embodiment, the length t22 of the terminal portion of the wiring connection terminal D is 200 μm, and the width t23 is 100 μm. The bonding of the vibration type gyro sensor element 10 to the outside is arbitrary including the bonding method, and the shape of the wiring connection terminal D is set to be optimum according to the bonding method employed.

  In this embodiment, a resist film pattern having a shape as shown in FIG. 22 is formed by using a photolithography technique, and then unnecessary portions of the lower electrode film 4 are removed by ion etching, whereby the reference electrode 4a and the wiring are formed. The lower electrode film 4 for electrically connecting the connection terminal D, the reference electrode 4a and the wiring connection terminal D was formed.

  As described above, in this embodiment, the technique for removing unnecessary portions of the lower electrode film 4 to form the reference electrode 4a is ion etching, which is physical etching. However, the present invention is not limited to this. Instead, it is possible to apply a removal method by wet etching, which is chemical etching, or reactive ion etching (RIE), in which etching is performed by chemical action and physical action.

Next, electrical connection between the terminal connection portions 6a ₁ , 6b ₁ , 6c ₁ formed on one end side of each of the drive electrode 6a and the detection electrodes 6b, 6c and the wiring connection terminals A, B, C is performed. A planarizing resist film 7 is formed for smoothness.

  24 is a plan view showing a state of the single crystal silicon substrate 1 on which the planarizing resist film 7 is formed, and FIG. 25 is a cross-sectional view when the single crystal silicon substrate 1 shown in FIG. 24 is cut along a YY line. FIG.

As shown in FIG. 22 described above, when the wiring connection terminals A, B, and C and the terminal joint portions 6a ₁ , 6b ₁ , and 6c ₁ are physically joined, the piezoelectric body 5a is formed. It must pass through the remaining end of the piezoelectric film 5 and the end of the lower electrode film 4 left when the reference electrode 4a is formed.

In this embodiment, the piezoelectric body 5a is formed by etching the piezoelectric film 5 by wet etching, and the etched end portion has a reverse taper shape or a vertical shape in the direction of the single crystal silicon substrate 1. It has become. Therefore, if the wiring film is formed so as to electrically connect the terminal junctions 6a ₁ , 6b ₁ , 6c ₁ and the wiring connection terminals A, B, C without forming the planarizing resist film 7, There is a possibility that the electrical connection is broken by the step of the end portion.

  Further, since the end portion of the lower electrode film 4 electrically connected to the reference electrode 4a is exposed, the drive electrode 6a, the detection electrodes 6b and 6c, and the reference electrode are formed unless the planarizing resist film 7 is formed. 4a will be short-circuited.

For the reasons described above, as shown in FIG. 24, a planarizing resist film 7 is formed on the terminal junctions 6a ₁ , 6b ₁ , 6c ₁ to eliminate the step at the end of the piezoelectric film 5, and the lower electrode The end of the film 4 is not exposed.

  The shape of the flattening resist film 7 can be arbitrarily set as long as it eliminates the step at the end of the piezoelectric film 5 and does not expose the end of the lower electrode film 4 as described above. In this embodiment, the planarizing resist film 7 has a width t24 of 200 μm and a length t25 of 50 μm.

  The planarization resist film 7 is hardened by applying a heat treatment of about 280 to 300 ° C. to a resist film patterned in a desired shape at a position shown in FIG. 24 by a photolithography technique. In this embodiment, the thickness of the resist film is about 2 μm, but this thickness is preferably changed according to the thicknesses of the piezoelectric film 5 and the lower electrode film 4 to be equal to or greater than the total thickness of both. In this embodiment, the planarization resist film 7 is formed using a resist film. However, any non-conductive material that can avoid the above-described reason is arbitrary including its formation method. .

  Next, wiring connection terminals A, B, and C used when wiring processing for connecting the drive electrode 6a and the detection electrodes 6b and 6c to the outside are performed. 26 is a plan view showing a state of the single crystal silicon substrate 1 on which the wiring connection terminals A, B, and C are formed, and FIG. 27 is a view when the single crystal silicon substrate 1 shown in FIG. 26 is cut along the YY line. FIG.

The wiring connection terminals A, B, and C shown in FIG. 26 are connected to the terminal junctions 6a ₁ , 6b ₁ , and 6c ₁ of the drive electrode 6a and the detection electrodes 6b and 6c, respectively. In this embodiment, since the electrical connection between the vibration type gyro sensor element 10 and the outside is assumed to be performed by wire bonding, the terminal portions of the wiring connection terminals A, B, and C that are actually wired are used. As in the case of the wiring connection terminal D described above, an area required for wire bonding is secured.

Each wiring connection terminal A, B, C is formed on the thermal oxide film 2A so as to pass through the upper surface of the planarization resist film 7 and to be in contact with the terminal junctions 6a ₁ , 6b ₁ , 6c ₁ , respectively. The shape of each electrode joint, which is a joint between the wiring connection terminals A, B, and C, and the terminal connections 6a ₁ , 6b ₁ , and 6c ₁ is arbitrary, but is 5 μm in order to reduce electrical contact resistance. A size of 4 or more is desirable.

  In the wiring connection terminals A, B, and C, the terminal portion to which the wiring is actually connected has a shape that can secure an area necessary for wire bonding bonding as described above.

  In the present embodiment, the length t26 of each of the wiring connection terminals A, B, and C is 200 μm, and the width t27 is 100 μm. The bonding of the vibration type gyro sensor element 10 to the outside is arbitrary including the bonding method, and the shape of the wiring connection terminals A, B, and C is set to be optimal according to the bonding method to be employed.

  In this example, a resist film pattern having a shape as shown in FIG. 26 was formed by using a photolithography technique, and then wiring connection terminals A, B, and C were formed by sputtering. When sputtering, the film adhering to unnecessary portions was removed by a so-called lift-off technique, which is simultaneously removed when removing the resist film pattern.

  Specifically, for the wiring connection terminals A, B, and C, titanium (Ti) for improving adhesion is deposited by 20 nm, copper (Cu) having low electrical resistance and low cost is deposited by 300 nm, Further, in order to facilitate bonding with wire bonding, gold (Au) was formed by depositing 300 nm. Note that the material used when forming the wiring connection terminals A, B, and C and the formation method of the wiring connection terminals A, B, and C are arbitrary, and the present invention is not limited to the materials and the formation method. Absent.

  The subsequent process is a process of manufacturing the cantilever vibrator 11 by forming the surrounding space 12 with respect to the vibration type gyro sensor 10 as shown in FIG. FIG. 28 is a plan view showing a state where the cantilever vibrator 11 is formed by forming the surrounding space 12 in the single crystal silicon substrate 1, and FIG. 29 is a single crystal silicon substrate shown in FIG. 1 is a cross-sectional view showing a state where 1 is cut along a YY line, and FIG. 30 is a cross-sectional view showing a state where the single crystal silicon substrate 1 shown in FIG. 28 is cut along an XX line.

  As shown in FIG. 28, the surrounding space 12 includes a space having a width of t7b and t7c in the left and right directions from the side surface of the vibrator 11 on the side where the detection electrodes 6b and 6c are formed, and a longitudinal direction of the vibrator 11. Thus, a space having a so-called “U” shape is formed by a space having a width of t7a on the end side opposite to the root line R of the vibrator 11.

  In this embodiment, t7b and t7c are each 200 μm. These t7b and t7c are determined by the state of the gas in the surrounding space 12, the Q value indicating the required quality of vibration of the vibrator 11, and the like.

  In this embodiment, first, using a photolithography technique, a “U” -shaped resist film pattern as shown in FIG. 28 is formed on the thermal oxide film 2A, and then the thermal oxide film 2A is ion-etched. Remove with. In order to remove the thermal oxide film 2A, wet etching can be performed, but ion etching is preferable in consideration of a dimensional error caused by side etching.

  Then, the surrounding space 12 is formed by etching and penetrating the "U" -shaped single crystal silicon substrate 1 from which the thermal oxide film 2A has been removed by reactive ion etching (RIE). To do.

  In this embodiment, using an etching apparatus equipped with inductively coupled plasma (ICP), an etching process and a process of forming a sidewall protective film for protecting the sidewall at the etched portion are repeated. A vibrator 11 having a vertical side wall surface was formed by a process (Bosch).

By using this Bosch process, a high-density plasma is generated by ICP, and SF ₆ for etching and C ₄ F ₈ gas for side wall protection are alternately introduced, and about 10 μm per minute. The vibrator 11 having a vertical side wall surface can be formed while etching at a speed.

  With the above process, the main steps of piezoelectric element formation, shape formation, and wiring formation relating to the formation of the vibration type gyro sensor element 10 are completed. For example, as shown in FIG. A plurality of gyro sensor elements 10, here 5 × 3, are formed.

  The number of vibration-type gyro sensor elements 10 formed in one single crystal silicon substrate 1 is not limited to 5 × 3 as shown in FIG. 31, and the size of the vibration-type gyro sensor element 10 to be designed, It is determined by each pitch when forming.

  In the next step, the plurality of vibration gyro sensor elements 10 thus formed on the single crystal silicon substrate 1 are cut into a single element. The method and dimensions for dividing the vibration type gyro sensor element 10 from the single crystal silicon substrate 1 are not particularly determined, and the shape after the division is also arbitrary.

  In the present embodiment, the single crystal silicon substrate 1 was directly folded by hand and the vibration gyro sensor element 10 was taken out after being cut with a diamond cutter so as to trace the element cutting line 20 shown in FIG. . An arbitrary method can be applied to the method of dividing the single crystal silicon substrate 1. For example, a method of grinding with a grindstone or cutting using the plane orientation of the single crystal silicon substrate 1 may be used.

  Subsequently, as shown in FIG. 33, the vibration-type gyro sensor element 10 divided individually is attached to the IC substrate 21. The vibration gyro sensor element 10 and the IC substrate 21 can be attached by any method, but in this embodiment, the vibration gyro sensor element 10 is attached using an anaerobic adhesive.

  After the vibration type gyro sensor element 10 is attached to the IC substrate 21, electrical connection is performed. On the IC substrate 21, the IC circuit 40 described with reference to FIG. 2 at the beginning is mounted. Further, the IC substrate 21 includes a substrate terminal 22a connected to the end of the AGC 44 shown in FIG. 2, substrate terminals 22b and 22c connected to the synchronous detection circuit 45, and a substrate terminal 22d connected to a reference electrode (not shown). Is formed.

  In the present embodiment, the wiring connection terminals A, B, C, and D of the vibration type gyro sensor element 10 and the substrate terminals 22a, 22b, 22c, and 22d in the IC substrate 21 are electrically connected using a wire bonding method. Connection was made. This connection method is also arbitrary, and a method of forming conductive bumps used in semiconductors can also be used.

  Next, as shown in FIG. 34, a cover member 30 is attached to protect the vibration type gyro sensor element 10 and the circuit on the IC substrate 21 from contact with the outside to protect them. The material of the cover member 30 is arbitrary, but it is desirable to have a shielding effect such as SUS in consideration of the influence of external noise. The cover material 30 needs to have a shape that does not hinder the vibration of the vibrator 11. In this way, the angular velocity sensor 50 is formed.

  In this way, when a voltage is applied to the drive electrode 6a of the vibrator 11 included in the vibration type gyro sensor element 10 constituting the angular velocity sensor 50 to vibrate at a predetermined resonance frequency, the vibrator 11 It resonates at the longitudinal resonance frequency in the thickness direction, and at the transverse resonance frequency in the transverse direction, which is the width direction of the vibrator 11.

  As described above, the vibration-type gyro sensor element 10 is attached to the IC substrate 21 as shown in FIG. 34 in order to protect the vibrator 11 and facilitate handling when incorporated in an external device. Covered with material 30 and packaged. At this time, it is assumed that the cover member 30 has a shape that does not hinder the vibration of the vibrator 11.

  Specifically, an appropriate space around the vibrator 11 so that a desired Q value can be obtained when the Q value when the vibrator 11 is self-excited at a longitudinal resonance frequency is measured. It is necessary to secure an area. As described above, if an appropriate space area is secured in the space around the vibrator 11, the vibration of the vibrator 11 is not hindered and a stable vibration state is obtained. High sensitivity can be maintained even if angling is applied.

  Subsequently, the space around the vibrator 11 will be described with reference to FIGS. 35 is a cross-sectional view showing only the vibrator 11 when the vibration type gyro sensor element 10 shown in FIG. 28 is cut by XX line. FIG. 36 is a cross-sectional view of the vibration type gyro sensor element 10 shown in FIG. 3 is a plan view showing only a vibrator 11. FIG.

  In the case of a cantilever-shaped vibrator such as the vibrator 11 provided in the vibration type gyro sensor element 10, the surrounding space has a vibrator in which a drive electrode 6a and detection electrodes 6b and 6c as shown in FIG. 35 are formed. FIG. 36 shows a first space S1 which is a space extending on a plane including the upper surface 11a of the eleventh, a second space S2 which is a space extending on a plane including the lower surface 11b which is the surface facing the upper surface 11a, and As described above, the third space S3 is formed by reactive ion etching (RIE) and includes spaces extending on the respective planes including the side wall surfaces 11c, 11d, and 11e that are the side wall surfaces of the vibrator 11. It is roughly divided into

  As described above, in the first space S1, the second space S2, and the third space S3 that are the surrounding spaces of the vibrator 11, the vibratory gyro sensor 10 including the vibrator 11 is, for example, an IC substrate 21. Since it is affixed on top and covered with the cover material 30 and packaged, the space size is limited.

  37 and 38 are cross-sectional views of the vibration type gyro sensor element 10 shown in FIG. 34 taken along line XX. In FIG. 37, when a voltage is applied between the reference electrode 4a and the drive electrode 6a of the vibrator 11 to cause the vibrator 11 to oscillate by itself, the vibrator 11 swings by the maximum displacement dmax in the direction of the upper surface 11a. FIG. 38 is a cross-sectional view showing a state in which the vibrator 11 is swung by the maximum displacement amount dmax in the direction of the lower surface 11b when the vibrator 11 is also subjected to self-excited vibration. . 37 and 38, the portion indicated by the alternate long and short dash line indicates a state where the vibrator 11 is not vibrating or a state where the displacement amount of the vibrating vibrator 11 is zero.

  In the vibration type gyro sensor element 10 shown in FIG. 37, the first space S1 is an upper space width t7d that is an interval between the inner wall surface 30a of the cover member 30 and the upper surface 11a when the vibrator 11 is not vibrating. Defines the space size. As shown in FIG. 38, the second space S2 is a distance between the substrate surface 21a of the IC substrate 21 to which the vibration type gyro sensor element 10 is attached and the lower surface 11b when the vibrator 11 is not vibrating. The space size is defined by the lower space width t7e. Further, as shown in FIG. 39, the third space S3 has a space size defined by the surrounding space 12 formed by the above-described reactive etching, specifically, the space widths t7a, t7b, and t7c. Become.

  Subsequently, as shown in FIG. 34, the first space S1, the second space S2, and the third space of the vibration-type gyro sensor element 10 that is packaged by being attached onto the IC substrate 21 and covered with the cover material 30. Each of S3 is changed, and a Q value which is a mechanical quality factor is measured, and an optimum space size is defined from the measurement result.

  First, FIG. 40 shows a Q value of the vibration type gyro sensor element 10 when the first space S1 is changed. As described above, the first space S1 is defined by the upper space width t7d shown in FIG.

  The measurement result shown in FIG. 40 shows the Q value at that time by changing the first space S1 by increasing the upper space width t7d from 0 at an appropriate interval.

  In the horizontal axis of FIG. 40, the upper space width t7d is shown as a relative value when the maximum displacement dmax when the vibrator 11 is caused to self-excited is 1. In the vertical axis of FIG. 40, the Q value of the vibration type gyro sensor element 10 that has been packaged as described above and has changed the first space S1 is not packaged. The relative value when the Q value of the vibration-type gyro sensor element 10 in the state where the surrounding space is open is 1 is shown.

  As shown in FIG. 40, when the relative value shown on the horizontal axis is about 2, that is, the upper space width t7d is about twice the maximum displacement dmax of the vibrator 11, the Q value is around 1. I'm taking it. When the relative value of the horizontal axis is about 2.5, that is, when the upper space width t7d is 2.5 times or more of the maximum displacement dmax of the vibrator 11, the Q value is saturated to 1. Yes.

  The measurement results shown in FIG. 40 show that the cover material 30 is adjusted such that the upper space width t7d that defines the first space S1 is twice or more the maximum displacement dmax when the vibrator 11 is self-excited. It shows that when attached, the deterioration of the resonance characteristics of the vibrator 11 can be greatly suppressed. Furthermore, the measurement result shown in FIG. 40 shows that the resonance characteristics of the vibrator 11 are optimized when the cover material 30 is attached so that the upper space width t7d is 2.5 times or more of the maximum displacement dmax. It shows that you can.

  Although the measurement result is not shown for the second space S2, the measurement result of the Q value is almost the same as the measurement result shown in FIG. Therefore, similarly to the first space S1 described above, the lower space width t7e shown in FIG. 38 that defines the second space S2 is twice the maximum displacement dmax when the vibrator 11 is self-excited. When pasted on the IC substrate 21 as described above, the deterioration of the resonance characteristics of the vibrator 11 can be significantly suppressed. Further, the resonance characteristics of the vibrator 11 can be optimized when the lower space width t7e is affixed to the IC substrate 21 so that the maximum displacement dmax is 2.5 times or more.

  Subsequently, FIG. 41 shows the Q value of the vibration type gyro sensor element 10 when the third space S3 is changed. As described above, the third space S3 is defined by the space widths t7a, t7b, and t7c shown in FIG.

  The measurement result shown in FIG. 41 shows the Q value at that time by changing the third space S3 by increasing the space widths t7a, t7b, and t7c from 0 at appropriate intervals. Here, the space widths t7a, t7b, and t7c are all set to the same value.

  In the horizontal axis of FIG. 41, the space widths t7a, t7b, and t7c are shown as relative values when the width t6 of the vibrator 11 is 1. In the vertical axis of FIG. 41, the Q value of the vibration type gyro sensor element 10 packaged as described above and changed in the third space S3 is not packaged, and the vibrator 11 The relative value when the Q value of the vibration-type gyro sensor element 10 in the state where the surrounding space is open is 1 is shown.

  As shown in FIG. 41, when the relative value shown on the horizontal axis is about 0.5, that is, when the space widths t7a, t7b, and t7c are about ½ times the width t6 of the vibrator 11, Q The value is in the vicinity of 1. Further, when the relative value on the horizontal axis is about 2, that is, when the space widths t7a, t7b, and t7c are more than twice the width t6 of the vibrator 11, the Q value is saturated to 1.

  The measurement results shown in FIG. 41 show that reactive ion etching is performed on the surrounding space 12 in which the space widths t7a, t7b, and t7c defining the third space S3 are ½ times or more the width t6 of the vibrator 11. This indicates that the deterioration of the resonance characteristics of the vibrator 11 can be significantly suppressed. Furthermore, the measurement results shown in FIG. 41 show that the resonator 11 is formed by reactive ion etching in which the surrounding space 12 has a space width t7a, t7b, t7c that is twice or more the width t6 of the resonator 11. It is shown that the resonance characteristics of can be optimized.

  The measurement results of the Q value shown in FIGS. 40 and 41 described above are results when the vibration type gyro sensor 10 is packaged at room temperature, but the present invention is not limited to this. For example, even when the vibration type gyro sensor element 10 is packaged in the atmosphere at 80 ° C. and returned to room temperature, the result is the same as the Q value measurement result shown in FIGS. Therefore, when there is a change in atmospheric pressure in the space around the vibrator 11, for example, the space around the vibrator 11 of the vibration type gyro sensor element 10 packaged in the atmosphere is changed to the atmospheric pressure after packaging. It is effective even if it is not.

  In the embodiment, the vibration type gyro sensor element 10 formed by the above-described method is shown as an example, the first space S1 is the upper space width t7d, the second space S2 is the lower space width t7e, and the third space. Although S3 is defined by the space widths t7a, t7b, and t7c, the present invention is not limited to this, and a lower electrode, a piezoelectric thin film, and an upper electrode formed on a single crystal silicon substrate by a thin film forming process. The present invention can be widely applied to a vibration type gyro sensor element that includes a cantilever-shaped vibrator having the above and detects an angular velocity using the piezoelectric effect of a piezoelectric thin film.

  For example, in the present embodiment, as shown in FIG. 39, the vibrator 11 is formed by performing crystal anisotropic etching and reactive ion etching on the single crystal silicon substrate 1, so that The outer frame of the single crystal silicon substrate 1 remains in the vicinity of the side wall surfaces 11c, 11d, and 11e of the vibrator 11.

  However, according to the present invention, the side wall surface 11c of the vibrator 11 is also applied to vibration gyro sensor elements other than the vibration gyro sensor element 10 on which the outer frame is formed by the single crystal silicon substrate 1 as in this embodiment. 11d, 11e, the first space S1, the second space S2, and the second space S2, which improve the resonance characteristics of the vibrator 11 by securing the respective distances from the top face 11a and the bottom face 11b of the vibrator 11 as described above. A third space S3 can be defined.

It is a perspective view for demonstrating the vibration type gyro sensor element shown as the best form for implementing this invention. It is a figure for demonstrating the structure of the angular velocity sensor provided with the vibration gyro sensor element. It is a perspective view for demonstrating the vibrator | oscillator with which the same vibration type gyro sensor element is provided. It is a top view for demonstrating the vibration type gyro sensor element. It is a top view for demonstrating the single crystal silicon substrate used when manufacturing the vibration type gyro sensor element. It is sectional drawing at the time of cut | disconnecting the single crystal silicon substrate shown in FIG. 5 by XX line. It is a top view which shows a mode that the resist film pattern was formed in the single crystal silicon substrate. It is sectional drawing at the time of cut | disconnecting the single crystal silicon substrate shown in FIG. 7 by XX line. It is a top view which shows a mode at the time of removing the thermal oxide film of a single crystal silicon substrate. FIG. 10 is a cross-sectional view of the single crystal silicon substrate shown in FIG. 9 taken along the line XX. It is a top view which shows a mode that the crystal anisotropic etching was performed to the single crystal silicon substrate. It is sectional drawing at the time of cut | disconnecting by the single crystal silicon substrate XX line shown in FIG. It is sectional drawing which expanded and showed the area | region A shown in FIG. It is the top view which showed the mode of the surface side of a single crystal silicon substrate. It is sectional drawing at the time of cut | disconnecting the single crystal silicon substrate shown in FIG. 14 with XX line. It is a top view which shows the mode of the single crystal silicon substrate in which the lower electrode film, the piezoelectric film, and the upper electrode film were formed. FIG. 17 is a cross-sectional view when the single crystal silicon substrate shown in FIG. 16 is cut along XX line. It is a top view which shows the mode of the single crystal silicon substrate in which the drive electrode and the detection electrode were formed. It is sectional drawing when the single crystal silicon substrate shown in FIG. 18 is cut | disconnected by XX line. It is a top view which shows the mode of the single crystal silicon substrate in which the piezoelectric material was formed. It is sectional drawing at the time of cut | disconnecting the single crystal silicon substrate shown in FIG. 20 by XX line. It is a top view which shows the mode of the single crystal silicon substrate in which the reference electrode was formed. It is sectional drawing at the time of cut | disconnecting the single crystal silicon substrate shown in FIG. 22 by XX line. It is a top view which shows the mode of the single crystal silicon substrate in which the planarization resist film was formed. FIG. 25 is a cross-sectional view of the single crystal silicon substrate shown in FIG. 24 taken along line YY. It is a top view which shows the mode of the single crystal silicon substrate in which the wiring connection terminal was formed. FIG. 27 is a cross-sectional view of the single crystal silicon substrate shown in FIG. 26 taken along line YY. It is a top view which shows the mode of the single crystal silicon substrate in which surrounding space was formed in the circumference | surroundings of a vibrator | oscillator by reactive ion etching. FIG. 29 is a cross-sectional view of the single crystal silicon substrate shown in FIG. 28 taken along line YY. FIG. 29 is a cross-sectional view of the single crystal silicon substrate shown in FIG. 28 taken along line XX. It is a top view which shows the single crystal silicon substrate in which the some vibration type gyro sensor element was formed. It is a top view which shows the mode of the single crystal silicon substrate which showed the cutting line at the time of cut | disconnecting the several vibration type gyro sensor element formed in the single crystal silicon substrate. It is a top view which shows a mode when a vibration type gyro sensor element is affixed on an IC substrate. It is a top view which shows a mode when a cover material is attached to the angular velocity sensor provided with a vibration type gyro sensor element. It is a figure for demonstrating the 1st space and 2nd space which are the surrounding space of a vibrator | oscillator. It is a figure for demonstrating the 3rd space which is the surrounding space of a vibrator | oscillator. It is a figure for demonstrating the 1st space of a vibration type gyro sensor element. It is a figure for demonstrating the 2nd space of a vibration type gyro sensor element. It is a figure for demonstrating the 3rd space of a vibration type gyro sensor element. It is the figure which showed Q value of the vibration type gyro sensor element at the time of changing 1st space. It is the figure which showed Q value of the vibration type gyro sensor element at the time of changing 3rd space.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Single crystal silicon substrate, 4a Reference electrode, 5a Piezoelectric body, 6a Drive electrode, 6b, 6c Detection electrode, 10 Vibrating gyro sensor element, 11 Vibrator, 11a, 11b, 11c Side wall surface, 11d Upper surface, 11e Lower surface, 12 , Surrounding space, 21 IC substrate, 30 cover material, R root line, S1 first space, S2 second space, S3 third space

Claims (1)

Covers a vibratory gyro sensor element that has a quadrangular columnar cantilever vibrator made of single crystal silicon with a lower electrode, a piezoelectric thin film, and an upper electrode, and detects angular velocity using the piezoelectric effect of the piezoelectric thin film. Electronic equipment packaged in the atmosphere using a material and an IC substrate ,
The upper electrode has a driving electrode formed in a longitudinal direction of the vibrator for applying a voltage for vibrating the vibrator, and the driving electrode is sandwiched between the upper electrode and the vibrator without being in contact with the driving electrode. Formed of a first detection electrode and a second detection electrode formed in the longitudinal direction of
The distance from the top surface of the vibrator to the cover material and the distance from the bottom surface of the vibrator to the IC substrate when the vibrator is not oscillating, and a voltage between the lower electrode and the upper electrode. When the vibrator is self-excited to vibrate in the thickness direction when applied, a space is provided that is at least 2.5 times the maximum displacement, which is the displacement when the vibrator vibrates most,
An electronic device provided with a space in which the distance from the side wall surface of the vibrator to the wall surface formed so as to face the side wall surface over the entire side wall surface is twice or more the width of the vibrator.

Images