JP5162206B2 - Oscillator, oscillator manufacturing method, and oscillator - Google Patents

Description

  The present invention relates to an oscillator having a structure capable of oscillating a plurality of resonance frequencies, a method for manufacturing the oscillator, and an oscillator including the oscillator.

  Conventionally, crystal oscillators using crystal oscillators have been used for clock pulse generation in digital devices and wireless devices. However, silicon oscillators that use silicon, which is more mass-productive and easier to design frequencies, are used. Attempts have been made to manufacture oscillators.

  The silicon oscillator utilizes a resonance mode of a cantilever beam or a doubly supported beam held so as to be swingable. Since the resonance frequency is defined by the cross-sectional size and length of the beam, the design is easy. In addition, since elements can be collectively formed on a large-diameter silicon substrate, mass productivity is high, and it is also possible to manufacture using a conventional CMOS IC manufacturing line.

  As shown in Patent Document 1, a silicon oscillator vibrates a vibrator made of silicon in a predetermined direction by an electrostatic attractive force between a piezoelectric element or a counter electrode and the vibrator, and the vibration with the counter electrode. What is detected by a change in capacitance between the two or a piezoresistor has been proposed.

  However, in this method, the vibrator can be vibrated only in one direction, and only one frequency signal can be output. A device that requires signals of a plurality of frequencies needs to be equipped with an oscillator having a vibrator and a drive circuit corresponding to each frequency, leading to an increase in size and cost.

  In order to solve the above-described drawbacks, as shown in Patent Document 2, there has been proposed an oscillator 30 that modulates a frequency by applying a gas pressure to a diaphragm-like vibrator.

  As shown in FIG. 17, the oscillator 30 includes a diaphragm-shaped vibrator 31. The vibrator 31 is disposed so as to separate the upper airtight chamber 32 and the lower airtight chamber 33. A gas pipe 34 communicating with the outside is connected to the upper hermetic chamber 32, and the pressure in the upper hermetic chamber 32 can be changed via a valve 35. When gas is introduced into the upper hermetic chamber 32, the internal stress of the vibrator 31 changes due to the pressure difference between the upper hermetic chamber 32 and the lower hermetic chamber 33, so that the resonance frequency can be changed.

In general, a method of changing a resonance frequency by applying an external force such as an electrostatic attractive force to a vibrator is also known, not limited to a pressure by gas.
JP2007-175577 JP2007-235754

  However, the oscillator 30 configured as described above has the following drawbacks. That is, in the method of changing the resonance frequency by applying these external forces to the vibrator, it is impossible to simultaneously output a plurality of frequency signals having different frequencies. In addition, a structure for applying an external force to the vibrator is necessary, and the structure becomes complicated. Further, in order to greatly change the resonance frequency, the external force must be increased, and there is a limit to the amount of change in the resonance frequency.

  The present invention has been made in view of the above circumstances, and its purpose is to have different frequencies from one vibrator without applying external force to the vibrator and changing the resonance frequency of the vibrator itself. To provide an oscillator capable of outputting a plurality of frequency signals at the same time and easily designing each resonance frequency, a method of manufacturing the oscillator, and an oscillator including the oscillator.

  In order to solve the above problems, the present invention provides the following means.

  The resonator according to the present invention includes a vibrator having a plurality of side surfaces, an anchor connected to one or both ends of the vibrator to hold the vibrator in a swingable manner, and a predetermined interval between the side surfaces of the vibrator. A plurality of drive electrodes opposed to each other with a gap therebetween, and a plurality of detection electrodes arranged opposite to the drive electrodes across the vibrator with a predetermined interval therebetween. It is characterized by this.

  In the resonator according to the aspect of the invention, when a drive voltage having a predetermined waveform is applied to each of the drive electrodes, the vibrator is attracted to the drive electrode by an electrostatic attractive force and vibrates. If the vibrator is formed so that the resonance frequency in the direction attracted to each drive electrode of the vibrator is different, it is possible to simultaneously output a frequency signal substantially matching the resonance frequency in each direction from each detection electrode.

  The resonator according to the present invention is the resonator according to the present invention described above, wherein a cross section of the vibrator in a short direction is a rectangle, and includes two drive electrodes and two detection electrodes. It is characterized by this.

  In the resonator according to the present invention, since the cross section in the short direction of the vibrator is rectangular, each of the cross sections of the vibrator is parallel to the long side by appropriately setting the length of the long side and the short side. The resonance frequency in a certain direction and the resonance frequency in a direction parallel to the short side can be easily designed to a predetermined frequency.

  The resonator according to the present invention is the resonator according to the present invention described above, wherein the vibrator has a square cross-section in the short direction, and includes two drive electrodes and two detection electrodes. It is characterized by this.

  In the resonator according to the present invention, since the cross section of the vibrator is square, the two frequency signals output from the resonator can be substantially matched. Also, the phase of the frequency signal can be matched or different.

  The resonator according to the present invention is the resonator according to the present invention described above, wherein the vibrator, the anchor, the first drive electrode among the drive electrodes, and the vibrator among the detection electrodes are sandwiched. The first detection electrode disposed on the opposite side of the first drive electrode is composed of an active layer of an SOI (Silicon On Insulator) substrate, and the second drive electrode or the second of the detection electrodes among the drive electrodes. One of the detection electrodes is made of a support layer of an SOI substrate, and the other of the second drive electrode or the second detection electrode is formed on a lid substrate made of an insulator bonded to the active layer. A through-hole made of a conductive thin film, provided with a through-hole communicating with the drive electrode and the detection electrode in the lid substrate, and having at least an inner peripheral surface of the through-hole covered with a conductive material. Special It is a sign.

  In the resonator according to the present invention, the interval between the vibrator, the drive electrode, and the detection electrode can be easily formed with high accuracy, and can be driven efficiently, and an accurate frequency signal can be output. At the same time, the number of man-hours can be reduced to provide a highly reliable oscillator.

  The resonator according to the present invention is the resonator according to the present invention described above, wherein the vibrator, the drive electrode, and the detection electrode are formed of an active layer of an SOI substrate, and the anchor is formed of a support layer of the SOI substrate. The vibrator is arranged so that the longitudinal direction of the vibrator coincides with the thickness direction of the active layer.

  In the resonator according to the present invention, since the resonator can be formed only by the SOI substrate, the resonator can be easily formed with high accuracy. In addition, since a lid substrate is unnecessary, the device can be downsized and the number of steps can be reduced.

  The method for manufacturing an oscillator according to the present invention is the method for manufacturing the oscillator according to the present invention, wherein a predetermined region of the active layer of the SOI substrate is selectively removed so that the resonator, the anchor, and the first drive A vibrator step of forming an electrode and a first detection electrode, selectively removing a predetermined region of the buried oxide film layer of the SOI substrate to make the vibrator swingable, and an insulator A predetermined region of the lid substrate is selectively removed to form a through hole, a gap is formed at a position facing the vibrator on the lid substrate, and a conductive position is formed at a position facing the vibrator on the lid substrate. A lid substrate step for forming either the second drive electrode or the second detection electrode made of a conductive thin film, and the vibrator step and the lid so that the through hole communicates with the drive electrode and the detection electrode The SOI substrate subjected to the substrate process and the Joining de substrate, it is characterized in that and a joining step of forming the through electrode over at least the inner circumferential surface of a conductive material of the through hole.

  In the method for manufacturing an oscillator according to the present invention, since the vibrator is formed using the active layer of the SOI substrate, the vibrator having an accurate resonance frequency can be formed. In addition, since the drive electrode or the detection electrode is formed on the lid substrate and bonded to the SOI substrate on which the vibrator is formed, the drive electrode or the detection electrode can be easily arranged around the vibrator, thereby reducing the number of steps. Can do.

  The oscillator according to the present invention includes the oscillator according to the present invention described above, and the same number of drive circuits as the drive electrodes that apply to the drive electrodes a drive voltage that substantially matches the resonance frequency of the vibrator provided in the oscillator. , Provided.

  In the oscillator according to the present invention, since driving voltages having different frequencies can be applied to the plurality of driving electrodes, a plurality of different frequency signals can be output simultaneously.

  The oscillator according to the present invention is the oscillator according to the present invention, wherein one of the frequency signals output from the oscillator is input, and a frequency correction signal is detected by detecting a deviation of the frequency signal from a predetermined frequency. A frequency shift detection circuit that outputs the other of the frequency signal and the frequency correction signal, a frequency correction circuit that corrects the frequency signal input according to the frequency correction signal to a predetermined frequency and outputs the frequency signal to the outside , Provided.

  In the oscillator according to the present invention, even if the resonance frequency of the vibrator changes due to a change in temperature of the oscillator or application of an external force, the change can be corrected and a frequency signal can be output. Unlike installing a temperature sensor or the like outside the oscillator, it detects and corrects the change in the resonance characteristics of the vibrator itself, making it more accurate and making corrections regardless of the cause of the change in resonance characteristics. Can do.

  An oscillator according to the present invention is the oscillator according to the present invention, wherein the oscillator is the oscillator according to claim 4, and the drive circuit, the frequency shift detection circuit, and the frequency correction circuit are the oscillator. It is formed on the lid substrate.

  In the oscillator of the present invention, since the drive circuit, the frequency shift detection circuit, and the frequency correction circuit are formed on the lid substrate of the oscillator, the oscillator becomes a one-chip oscillator, and the device is downsized. Can do. In addition, since the distance between the oscillator and the drive circuit is short, unnecessary parasitic capacitance and resistance are small, and a signal can be efficiently transmitted from the drive circuit to the oscillator.

  According to the oscillator, the manufacturing method of the oscillator, and the oscillator according to the present invention, a plurality of frequencies having different frequencies from one oscillator without changing the resonance frequency of the oscillator itself by applying an external force to the oscillator. Signals can be output simultaneously, and each resonance frequency can be easily designed. Furthermore, it is possible to detect a change in the resonance frequency of the vibrator due to application of temperature or external force using one of the frequency signals, and output the frequency signal with efficient correction.

(First embodiment)
A first embodiment according to the present invention will be described below with reference to FIGS. 1 and 2. FIG. 1 is a perspective view showing an oscillator 1 according to the first embodiment, and FIG. 2 is a cross-sectional view of FIG. 1 viewed from the z direction.

  The oscillator 1 includes a columnar vibrator 2 having a rectangular cross section, an anchor 3 that is connected to one or both ends of the vibrator 2 and holds the vibrator 2 in a swingable manner, and a predetermined adjacent portion of the vibrator 2. Two drive electrodes 4A and 4B arranged to face each of the two side surfaces 2A and 2B with a predetermined gap, and two adjacent side surfaces 2C and 2D of the vibrator 2 respectively. In contrast, two detection electrodes 5A and 5B that are arranged to face each other with a predetermined interval are provided, and the drive electrode 4A and the detection electrode 5A, and the drive electrode 4B and the detection electrode 5B each include the vibrator 2. It is arranged so as to sandwich. Here, since the cross section of the vibrator 2 is rectangular, the side face 2A facing the drive electrode 4A and the side face 2C facing the detection electrode 5A are located on opposite sides of the center axis of the vibrator 2. The side surface 2B opposite to the drive electrode 4B and the side surface 2D opposite to the detection electrode 5B are positioned substantially opposite to each other with the central axis of the vibrator 2 interposed therebetween. Furthermore, the side surfaces 2A and 2C and the side surfaces 2B and 2D have a positional relationship that is substantially orthogonal to each other.

  In the present embodiment, as shown in FIGS. 1 and 2, the longitudinal direction of the vibrator 2 is the z direction, and the direction substantially orthogonal to the side surfaces 2A and 2C facing the drive electrode 4A and the detection electrode 5A is the x direction. And the direction substantially orthogonal to the side surfaces 2B and 2D facing the drive electrode 4B and the detection electrode 5B is defined as the y direction.

  In the oscillator 1 configured as described above, when a drive voltage having a predetermined waveform is applied to the drive electrode 4A, an electrostatic attractive force acts between the vibrator 2 and the drive electrode 4A, and the vibrator is driven according to the waveform of the drive voltage. 2 is drawn to the drive electrode 4A. When the frequency of the drive voltage substantially matches the resonance frequency in the x direction of the vibrator 2, the vibrator 2 resonates and the amplitude increases.

  The resonance frequency f1 in the x direction of the vibrator 2 is given by Equation 1.

  Here, m is a coefficient determined by the support method of the vibrator 2, etc., E is the Young's modulus of the vibrator 2, ρ is the density of the vibrator 2, L is the length of the vibrator 2, and W1 is the drive electrode 4A. This is the width of the vibrator 2 that forms a right angle.

  When the vibrator 2 vibrates in the x direction, the distance between the vibrator 2 and the detection electrode 5A varies, and the capacitance between the vibrator 2 and the detection electrode 5A changes. This is output to the outside as an electrical signal.

  When a drive voltage having a predetermined waveform is applied to the drive electrode 4B, an electrostatic attractive force acts between the vibrator 2 and the drive electrode 4B, and the vibrator 2 vibrates in the y direction. When the frequency of the drive voltage substantially matches the resonance frequency in the y direction of the vibrator 2, the vibrator 2 resonates and the amplitude increases.

  The resonance frequency f2 in the y direction of the vibrator 2 is given by Equation 2.

  m, E, ρ, and L are common to Equation 1. W2 is the width of the vibrator 2 perpendicular to the drive electrode 4B.

  When the vibrator 2 vibrates in the y direction, the distance between the vibrator 2 and the detection electrode 5B varies, so that the capacitance between the vibrator 2 and the detection electrode 5B changes. This is output to the outside as an electrical signal.

  When drive voltages corresponding to f1 and f2 are input to the drive electrodes 4A and 4B, the vibration of the vibrator 2 has an x-direction component and a y-direction component, and the trajectory draws a Lissajous figure. As an example, FIG. 3 shows the trajectory of the vibrator 2 when f1: f2 = 1: 1.2.

  As can be seen from Equations 1 and 2, by appropriately setting the values of W1 and W2, the resonance frequency in the x direction and the resonance frequency in the y direction of the vibrator 2 can be determined independently. Therefore, two types of different frequency signals can be output simultaneously from one oscillator 1, and the device can be miniaturized.

Further, the cross section of the vibrator 2 may be a square. In this case, since the resonance frequency in the x direction is equal to the resonance frequency in the y direction, it is suitable for a device that requires two frequency signals having the same frequency but different phases.
(Second Embodiment)
Next, a second embodiment according to the present invention will be described with reference to FIGS. FIG. 4 is a perspective view showing the resonator 1 according to the second embodiment, and FIG. 5 is a cross-sectional view of FIG. 4 viewed from the z direction.

  An oscillator 1 according to this embodiment includes a columnar vibrator 2 having a hexagonal cross section, an anchor 3 that is connected to one or both ends of the vibrator 2 and holds the vibrator 2 in a swingable manner, and the vibrator 2. Drive electrodes 4A, 4B, and 4C that are arranged to face each of the predetermined three side surfaces 2A, 2E, and 2C at a predetermined interval, and the predetermined three side surfaces 2D and 2B of the vibrator 2. And detection electrodes 5A, 5B, and 5C that are arranged to face each other at a predetermined interval with respect to each of 2F, and drive electrode 4A and detection electrode 5A, drive electrode 4B and detection electrode 5B, The drive electrode 4C and the detection electrode 5C are arranged so as to sandwich the vibrator 2, respectively. Here, since the vibrator 2 has a hexagonal cross section, the side face 2A facing the drive electrode 4A and the side face 2D facing the detection electrode 5A are located on opposite sides of the center axis of the vibrator 2. The side surface 2E facing the drive electrode 4B and the side surface 2B facing the detection electrode 5B are positioned on opposite sides of the center axis of the vibrator 2 and are substantially parallel to each other, and the drive electrode 4C The side surface 2C opposed to and the side surface 2F opposed to the detection electrode 5C are located on the opposite sides of the center axis of the vibrator 2 and are substantially parallel to each other.

  In the present embodiment, as shown in FIGS. 4 and 5, the longitudinal direction of the vibrator 2 is the z direction, and the direction substantially orthogonal to the side surfaces 2A and 2D where the drive electrode 4A and the detection electrode 5A are opposed is the x1 direction. The direction substantially orthogonal to the side surfaces 2E and 2B facing the drive electrode 4B and the detection electrode 5B is the x2 direction, and the direction substantially orthogonal to the side surfaces 2C and 2F facing the drive electrode 4C and the detection electrode 5C is the x3 direction. .

  In the oscillator 1 configured as described above, when a drive voltage having a predetermined waveform is applied to the drive electrode 4A, an electrostatic attractive force acts between the vibrator 2 and the drive electrode 4A, and the vibrator is driven according to the waveform of the drive voltage. 2 is drawn to the drive electrode 4A. When the frequency of the drive voltage substantially coincides with the resonance frequency f1 of the vibrator 2 in the x1 direction, the vibrator 2 resonates and the amplitude increases.

  Similarly, when a drive voltage having a frequency substantially equal to the resonance frequency f2 of the vibrator 2 in the x2 direction is applied to the drive electrode 4B, the vibrator 2 resonates in the x2 direction. Further, when a drive voltage having a frequency substantially equal to the resonance frequency f3 of the vibrator 2 in the x3 direction is applied to the drive electrode 4C, the vibrator 2 resonates in the x3 direction.

  Since the resonance frequencies f1, f2, and f3 of each direction of the vibrator 2 are complicatedly dependent on the lengths W1, W2, and W3 of the side surfaces of the vibrator, the resonance frequencies in each direction are independently set as in the first embodiment. Although it cannot be determined, f1, f2, and f3 can be determined by appropriately setting the sizes of W1, W2, and W3.

  When the vibrator 2 vibrates, the capacitance between the vibrator 2 and the detection electrodes 5A and 5B and 5C changes, and this is output to the outside as an electric signal.

In the first embodiment and the second embodiment, the resonator including the vibrator having the rectangular and hexagonal cross sections has been described as an example. However, when the present invention is applied to the resonator, An oscillator having a cross section of 2N square (N is an appropriate natural number of 2 or more), N drive electrodes and N detection electrodes provided to face each surface of the vibrator It is also good. In this case, N types of frequency signals can be output, and the device can be downsized.
(Third embodiment)
Next, a third embodiment according to the present invention will be described with reference to FIGS. 6 is a plan view of the oscillator 1 according to the third embodiment, FIG. 7 is a cross-sectional view of the oscillator 1 along the line AA ′ in FIG. 6, and FIG. 8 is a cross-sectional view of the oscillator 1 along the line BB ′ in FIG. . As shown in FIGS. 6 to 8, the x direction, the y direction, and the z direction are determined. In FIG. 6, the lid substrate 14 is omitted for the sake of simplicity.

  An oscillator 1 according to this embodiment includes a columnar vibrator 2 having a rectangular cross section, an anchor 3 that is connected to one or both ends of the vibrator 2 and holds the vibrator 2 in a swingable manner, The drive electrodes 4A and 4B arranged to face the predetermined side surfaces 2A and 2B with a predetermined space therebetween, and the predetermined side surfaces 2C and 2D of the vibrator 2 with a predetermined space therebetween. The detection electrodes 5A and 5B are provided, and the drive electrode 4A and the detection electrode 5A, and the drive electrode 4B and the detection electrode 5B are arranged so as to sandwich the vibrator 2, respectively. The vibrator 2, the anchor 3, the drive electrode 4 </ b> A, and the detection electrode 5 </ b> A are formed from an active layer 11 made of silicon of an SOI (Silicon On Insulator) substrate 10. The drive electrode 4B is composed of a support layer 12 made of silicon of an SOI substrate. The active layer 11 and the support layer 12 are arranged with a buried oxide film layer 13 made of silicon dioxide interposed therebetween. The detection electrode 5B is formed on a lid substrate 14 made of an insulating material, and the lid substrate 14 is connected to the anchor 3. The lid substrate 14 is provided with through-electrodes 6A, 6B, 6C, 6D, and 6E that are in communication with the drive electrode 4A, the detection electrode 5A, the drive electrode 4B, the detection electrode 5B, and the anchor 3, respectively.

  In the oscillator 1 configured as described above, when a drive voltage having a predetermined waveform is applied to the drive electrode 4A via the through electrode 6A, an electrostatic attractive force acts between the vibrator 2 and the drive electrode 4A, causing vibration. The child 2 is attracted to the drive electrode 4A. When the frequency of the drive voltage substantially matches the resonance frequency in the x direction of the vibrator 2, the vibrator 2 resonates and the amplitude increases.

  When a drive voltage having a predetermined waveform is applied to the drive electrode 4B via the through electrode 6C, an electrostatic attractive force acts between the vibrator 2 and the drive electrode 4B, and the vibrator 2 is attracted to the drive electrode 4B. . When the frequency of the drive voltage substantially matches the resonance frequency in the y direction of the vibrator 2, the vibrator 2 resonates and the amplitude increases.

  When the vibrator 2 vibrates, the capacitance between the vibrator 2 and the detection electrodes 5A and 5B changes, and this is output to the outside through the through electrodes 6B and 6D.

  When the cross section of the vibrator 2 is rectangular, the resonance frequency in the x direction and the resonance frequency in the y direction can be determined independently as in the case of the first embodiment.

  Further, the cross section of the vibrator 2 may be a square. In this case, the resonance frequency in the x direction is equal to the resonance frequency in the y direction.

  Further, an insulating film such as silicon oxide is formed on the active surface of the integrated circuit substrate on which a circuit for driving the oscillator 1 and a circuit for modulating a frequency signal output from the oscillator 1 are formed as the lid substrate 14. A film formed may be used. In this case, the oscillator 1 becomes a one-chip oscillator, and the device can be miniaturized. In addition, since the distance between the oscillator and the drive circuit is short, unnecessary parasitic capacitance and resistance are small, and a signal can be efficiently transmitted from the drive circuit to the oscillator.

Next, a method for manufacturing the resonator 1 configured as described above will be described with reference to FIGS. 9 to 11 correspond to cross-sectional views taken along line AA ′ of FIG. In general, a large number of oscillators 1 are arranged side by side and manufactured together. However, in order to simplify the description, it is assumed that one oscillator 1 is manufactured.

  First, a vibrator process is performed.

  As shown in FIG. 9A, an SOI comprising an active layer 11 made of silicon and a support layer 12 and an active layer 11 made of silicon dioxide and a buried oxide film layer 13 disposed so as to be sandwiched between the support layer 12. A substrate 10 is prepared. The material for forming the oscillator 1 is not limited to the SOI substrate, but may be a semiconductor substrate such as a silicon substrate or a metal substrate. However, when an SOI substrate is used, embedded oxide is formed when the vibrator 2 is formed as described later. Since the film layer 13 can be used as an etching stop, the thickness of the vibrator 2 can be easily controlled.

  Next, as shown in FIG. 9B, a predetermined position of the active layer 11 is removed, and the vibrator 2, the anchor 3, the drive electrode 4A, the detection electrode 5A, and the island 7 are formed. Various methods can be selected as a method for selectively removing a predetermined position of the active layer 11. For example, a mask is formed on the surface of the active layer 11 using a lithography technique, and TMAH (Tetramethyl Ammonium Hydroxide) is used. A predetermined region is selectively removed by selecting a method such as wet etching using a strong alkaline etchant such as an aqueous solution or an aqueous potassium hydroxide solution, or dry etching using RIE (Reactive Ion Etching) using SF6 plasma.

  Next, as shown in FIG. 9C, a predetermined position of the buried oxide film layer 13 is removed to make the vibrator 2 swingable. Various methods can be selected as a method for selectively removing a predetermined position of the buried oxide film layer 13. For example, etching can be performed using a hydrogen fluoride aqueous solution or hydrogen fluoride gas. . At this time, if the width of the vibrator 2 is sufficiently smaller than the anchor 3, the drive electrode 4A, the detection electrode 5A, etc., the buried oxide film layer 13 below the anchor 3, the drive electrode 4A, and the detection electrode 5A is completely removed. Since the buried oxide film layer 13 below the vibrator 2 is removed before being performed, only the vibrator 2 can be in a swingable state.

  Next, a lid substrate process is performed.

  In the lid substrate process, first, an insulating lid substrate 14 is prepared as shown in FIG. As the material of the lid substrate 14, for example, an insulating material such as glass or quartz can be used. A silicon substrate having an insulating thin film such as silicon dioxide formed on the surface can also be used.

  Next, as shown in FIG. 10B, a predetermined position on the surface of the lid substrate 14 is selectively removed, and a cavity gap 8 is formed so as to face the vibrator 2 in a bonding process described later. As a method for selectively removing a predetermined position on the surface of the lid substrate 14, a mask is formed using a lithography technique, and wet etching using a hydrogen fluoride aqueous solution or dry etching using RIE using plasma such as CF4 or C2F6. And so on.

  The depth of the cavity gap 8 may be such that the vibrator 2 does not contact and keeps a swingable state, for example, about 0.5 μm. Further, if the cavity gap 8 is too deep, the capacitance between the vibrator 2 and the detection electrode 5B becomes small and the sensitivity is deteriorated. Therefore, the depth of the cavity gap 8 should be about 5 micrometers or less, for example. desirable.

  Next, as shown in FIG. 10C, a conductive thin film is formed on the surface of the cavity gap 8, and a predetermined position is selectively removed so as to face the vibrator 2, thereby forming the detection electrode 5B. To do. As the material of the detection electrode 5B, for example, aluminum, gold, copper, or the like can be selected and can be easily formed.

  Next, as shown in FIG. 10D, a through hole 9 for forming through electrodes 6A, 6B, 6C, 6D, and 6E described later is formed. As a technique for forming the through hole 9, processing by sandblasting or laser irradiation can be selected. In addition, when a silicon substrate is selected as the material of the lid substrate 14, etching can be performed while keeping the angle of the side wall close to vertical with a high aspect ratio by using Deep RIE technology using a Bosch process. 2 can be reduced in size.

  Next, a joining process is performed.

  First, as shown in FIG. 11A, the vibrator 2 and the detection electrode 5B face each other with a predetermined interval between the SOI substrate 10 that has finished the vibrator step and the lid substrate 14 that has finished the lid substrate step. The through holes 9 are joined so as to communicate with the anchor 3, the drive electrode 4A, the detection electrode 5A, and the island 7, respectively. Various methods can be selected as a method for bonding the SOI substrate 10 and the lid substrate 14. For example, a glass containing alkali metal ions such as borosilicate glass is used as the material of the lid substrate 14. At least one of the anodic bonding method in which the SOI substrate 10 and the lid substrate 14 are brought into contact with each other by heating to a temperature of ° C or higher and bonding is performed by applying a voltage using the SOI substrate 10 as an anode. A resin bonding method in which a resin film such as polyimide is applied and bonded to each other, a solder or AuSn alloy film is formed on at least one of the SOI substrate 10 and the lid substrate 14 and heated to a temperature equal to or higher than the eutectic point. A eutectic bonding method to be bonded can be selected. Alternatively, a surface activated bonding method can be selected in which at least one of the SOI substrate 10 and the lid substrate 14 is irradiated with an ion beam or plasma to activate the surface, and bonded at room temperature or by heating.

  Next, as shown in FIG. 11B, a conductive material is deposited on at least the inner peripheral surface of the through hole 9 and electrically connected to the drive electrodes 4A and 4B and the detection electrodes 5A and 5B. Through electrodes 6A, 6B, 6C, 6D, and 6E are formed.

As described above, in the third embodiment according to the present invention, by applying a drive voltage having a waveform close to the resonance frequency in the x direction and y direction of the vibrator 2 to the drive electrodes 4A and 4B, respectively. Frequency signals corresponding to the x direction and y direction of the vibrator 2 can be simultaneously output from the detection electrodes 5A and 5B.
(Fourth embodiment)
Next, a fourth embodiment according to the present invention will be described with reference to FIGS. 12 is a plan view of the oscillator 1 according to the fourth embodiment, and FIG. 13 is a cross-sectional view of the oscillator 1 taken along the line CC ′ of FIG. Further, the x direction and the y direction are determined as shown in FIG.

  The oscillator 1 includes a columnar vibrator 2 having a rectangular cross section, an anchor 3 that is connected to one or both ends of the vibrator 2 and holds the vibrator 2 in a swingable manner, and a predetermined side surface 2A of the vibrator 2. , 2B and the drive electrodes 4A and 4B arranged opposite to each other with a predetermined interval, and the detection that is arranged opposite to the predetermined side surfaces 2C and 2D of the vibrator 2 with a predetermined interval. Electrodes 5A and 5B are provided, and the drive electrode 4A and the detection electrode 5A, and the drive electrode 4B and the detection electrode 5B are arranged so as to sandwich the vibrator 2, respectively.

  The vibrator 2, each drive electrode 4, and each detection electrode 5 are each formed from an active layer 11 of the SOI substrate 10.

  In the oscillator 1 configured as described above, when a drive voltage having a predetermined waveform is applied to the drive electrode 4A, an electrostatic attractive force acts between the vibrator 2 and the drive electrode 4A, and the vibrator is driven according to the waveform of the drive voltage. 2 is drawn to the drive electrode 4A. When the frequency of the drive voltage substantially matches the resonance frequency in the x direction of the vibrator 2, the vibrator 2 resonates and the amplitude increases.

  When the vibrator 2 vibrates in the x direction, the distance between the vibrator 2 and the detection electrode 5A varies, and the capacitance between the vibrator 2 and the detection electrode 5A changes. This is output to the outside as an electrical signal.

  When a drive voltage having a predetermined waveform is applied to the drive electrode 4B, an electrostatic attractive force acts between the vibrator 2 and the drive electrode 4B, and the vibrator 2 vibrates in the y direction. When the frequency of the drive voltage substantially matches the resonance frequency in the y direction of the vibrator 2, the vibrator 2 resonates and the amplitude increases.

  When the vibrator 2 vibrates in the y direction, the distance between the vibrator 2 and the detection electrode 5B varies, so that the capacitance between the vibrator 2 and the detection electrode 5B changes. This is output to the outside as an electrical signal.

  When the cross section of the vibrator 2 is rectangular, the resonance frequency in the x direction and the resonance frequency in the y direction can be determined independently as in the case of the first embodiment.

  Similarly to the case of the second embodiment, a vibrator having a cross section of 2N square (N is an appropriate natural number of 2 or more) and N drive electrodes provided to face each face of the vibrator. In addition, an oscillator having N detection electrodes may be used. In this case, N types of frequency signals can be output. For example, FIG. 14 shows an example of an oscillator 1 having a vibrator 2 having a hexagonal cross section with N = 3, three drive electrodes 4A, 4B, and 4C and three detection electrodes 5A, 5B, and 5C. .

In the third embodiment, two substrates of the SOI substrate 10 and the lid substrate 14 are required. On the other hand, according to the fourth embodiment, the oscillator 1 is composed only of the SOI substrate 10, and thus the thickness is reduced. The device can be miniaturized. Further, since the vibrator 2, the drive electrodes 4, and the detection electrodes 5 can all be formed from the active layer 11 of the SOI substrate 10, the resonator 1 can be simply removed by selectively removing unnecessary portions of the active layer 11. Can be manufactured.
(Fifth embodiment)
Next, a fifth embodiment according to the present invention will be described with reference to FIG.

  FIG. 15 is a block diagram of an oscillator 20 including the resonator 1 according to the present invention.

  The oscillator 20 of this embodiment includes the oscillator 1 shown in the first to fourth embodiments, the same number of drive circuits 21 and detection circuits (not shown) as the types of frequency signals output from the oscillator 1, and It has. In the present embodiment, as an example, the oscillator 1 outputs two types of frequency signals.

  The drive circuit 21 </ b> A applies a drive voltage having a frequency substantially equal to the first resonance frequency f <b> 1 of the oscillator 1 to the drive electrode 4 </ b> A of the oscillator 1. The vibrator 2 resonates at the first resonance frequency f1 due to the drive voltage, and the capacitance between the vibrator 2 and the detection electrode 5A varies due to the displacement. This is output as a frequency signal. As shown in FIG. 15, when a part of the output frequency signal is fed back to the drive circuit 21A and only the drive voltage that matches the phase is amplified and applied to the drive electrode 4A, self-excitation occurs and oscillation occurs. The child 1 can be oscillated stably.

  In addition, the drive circuit 21 </ b> B applies a drive voltage having a frequency substantially equal to the second resonance frequency f <b> 2 of the oscillator 1 to the drive electrode 4 </ b> B of the oscillator 1. The vibrator 2 resonates at the second resonance frequency f2 due to the drive voltage, and the capacitance between the vibrator 2 and the detection electrode 5B varies due to the displacement. This is output as a frequency signal. When a part of the frequency signal is fed back to the drive circuit 21B, the oscillator 1 can be stably oscillated as described above.

In the oscillator 20 configured as described above, two different frequency signals can be output from one oscillator 1 to the outside, so that the device can be reduced in size and power consumption.
(Sixth embodiment)
Next, a sixth embodiment according to the present invention will be described with reference to FIG.

  FIG. 16 is a block diagram of an oscillator 20 including the oscillator 1 according to the present invention.

  The oscillator 20 of the present embodiment includes the oscillator 1 described in the first to fourth embodiments, the same number of drive circuits 21 as the types of frequency signals output from the oscillator 1, a frequency shift detection circuit 22, The frequency correction circuit 23 is provided. In the present embodiment, as an example, the oscillator 1 outputs two types of frequency signals.

  In the present embodiment, as in the case of the fifth embodiment, the first frequency signal having the frequency f1 and the second frequency signal having the frequency f2 are output from the oscillator 1 by the drive circuits 21A and 21B. The second frequency signal is input to the frequency shift detection circuit 22.

  Here, when the temperature of the vibrator 2 changes, physical property values such as Young's modulus change, so the frequency of the frequency signal output from the oscillator 1 changes with temperature. A change in the frequency of the second frequency signal is detected by the frequency shift detection circuit 22, and the correction amount is output to the frequency correction circuit 23. The first frequency signal is input to the frequency correction circuit 23, corrected appropriately, and output from the oscillator 20.

  If the frequency signal changes with temperature, other devices that use the frequency signal may be adversely affected. Therefore, a means for correcting the frequency change is required. Further, the frequency fluctuates when an external force is applied to the vibrator 2. As a means for correcting the temperature characteristics, it is common to arrange a temperature sensor such as a MOS transistor or a thermocouple adjacent to the oscillator 20 and measure the temperature of the oscillator 20 to correct the frequency of the frequency signal. . However, in this method, an error occurs because the temperature of the vibrator 2 cannot be directly measured. In addition, it is impossible to correct frequency fluctuations caused by causes other than temperature, such as external force. However, if the oscillator 20 of the present embodiment is employed, the temperature of the vibrator 2 itself can be measured using the variation in the frequency of the second frequency signal, so that the change in the frequency signal can be accurately corrected. it can. Further, correction can be performed even if the resonance frequency changes due to factors other than temperature, such as external force. Furthermore, there is no need to provide a separate temperature sensor, and the device can be miniaturized.

  The cross section of the vibrator 2 may be a square. In this case, since the resonance frequency in the x direction is equal to the resonance frequency in the y direction, temperature correction can be performed more efficiently.

  The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

1 is a perspective view showing an oscillator 1 according to a first embodiment. It is sectional drawing which looked at FIG. 1 from the z direction. 2 is an example of a trajectory of a vibrator 2 in the resonator 1 according to the first embodiment. It is a perspective view which shows the resonator 1 of 2nd Embodiment. It is sectional drawing which looked at FIG. 4 from the z direction. It is a top view of oscillator 1 of a 3rd embodiment. FIG. 7 is a cross-sectional view of the oscillator 1 taken along the line AA ′ of FIG. 6. FIG. 7 is a cross-sectional view of the oscillator 1 taken along the line BB ′ in FIG. 6. It is sectional drawing which shows a vibrator | oscillator process in the manufacturing method of 3rd Embodiment. It is sectional drawing which shows a lid substrate process in the manufacturing method of 3rd Embodiment. It is sectional drawing which shows a joining process in the manufacturing method of 3rd Embodiment. It is a top view of oscillator 1 of a 4th embodiment. FIG. 13 is a cross-sectional view of the oscillator 1 taken along line CC ′ of FIG. 12. In 4th Embodiment, it is a top view of the oscillator 1 which can output three types of frequency signals. It is a block diagram of oscillator 20 of a 5th embodiment. It is a block diagram of the oscillator 20 of 6th Embodiment. 2 is a cross-sectional view of a conventional oscillator 30. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Oscillator 2 Vibrator 3 Anchor 4A, 4B, 4C Drive electrode 5A, 5B, 5C Detection electrode 6A, 6B, 6C, 6D, 6E Through electrode 7 Island 8 Cavity gap 9 Through hole 10 SOI substrate 11 Active layer 12 Support layer DESCRIPTION OF SYMBOLS 13 Embedded oxide film layer 14 Lid board | substrate 20 Oscillator 21A, 21B Drive circuit 22 Frequency shift detection circuit 23 Frequency correction circuit 30 Conventional oscillator 31 Vibrator 32 Upper airtight chamber 33 Lower airtight chamber 34 Gas pipe 35 Valve

Claims (9)

A vibrator with multiple sides;
An anchor connected to one or both ends of the vibrator and holding the vibrator in a swingable manner;
A plurality of drive electrodes opposed to the side surface of the vibrator with a predetermined interval;
A plurality of detection electrodes arranged opposite to the drive electrode across the vibrator, facing the side surface of the vibrator with a predetermined interval ,
The cross section of the vibrator in the short direction is a 2N square (N is a natural number of 2 or more),
The drive electrode and the detection electrode are provided in N pieces so as to face each surface of the cross section of the vibrator, respectively . The oscillator according to claim 1,
Resonator lateral direction of the cross section of the vibrator which is a rectangle and 2 the N. The oscillator according to claim 1,
Resonator lateral direction of the cross section of the oscillator is characterized in that a square to 2 said N. The oscillator according to claim 2 or 3,
Of the vibrator, the anchor, and the drive electrode, the first drive electrode, and the first detection electrode disposed on the opposite side of the first drive electrode across the vibrator is the SOI. Consisting of the active layer of the substrate,
Either one of the second drive electrode among the drive electrodes or the second detection electrode among the detection electrodes comprises a support layer of an SOI substrate,
The other of the second drive electrode or the second detection electrode is made of a conductive thin film formed on a lid substrate made of an insulator bonded to the active layer,
An oscillator having a through hole provided in the lid substrate and communicating with the drive electrode and the detection electrode, and having at least an inner peripheral surface of the through hole covered with a conductive material. The oscillator according to any one of claims 1 to 3,
The vibrator, the drive electrode, and the detection electrode are made of an active layer of an SOI substrate,
The anchor comprises a support layer of the SOI substrate,
An oscillator, wherein the vibrator is arranged so that a longitudinal direction thereof coincides with a thickness direction of the active layer. A method of manufacturing an oscillator according to claim 4,
A predetermined region of the active layer of the SOI substrate is selectively removed to form a vibrator, an anchor, a first drive electrode, and a first detection electrode, and the predetermined region of the buried oxide film layer of the SOI substrate is formed A vibrator step for selectively removing the vibrator to be in a swingable state;
A predetermined region of the lid substrate made of an insulating material is selectively removed to form a through hole, a gap is formed at a position of the lid substrate facing the vibrator, and the lid substrate faces the vibrator. A lid substrate step of forming either a second drive electrode or a second detection electrode made of a conductive thin film at a position;
The SOI substrate and the lid substrate that have been subjected to the vibrator step and the lid substrate step are joined so that the through hole communicates with the drive electrode and the detection electrode, and at least the inner peripheral surface of the through hole is made conductive. And a bonding step of forming a penetrating electrode by covering with the material described above. The oscillator according to any one of claims 1 to 5,
An oscillator comprising: the same number of drive circuits as the drive electrodes that apply to the drive electrodes a drive voltage that substantially matches a resonance frequency of a vibrator provided in the oscillator. The oscillator according to claim 7, wherein
One of frequency signals output from the oscillator is input, a frequency shift detection circuit that detects a deviation of the frequency signal from a predetermined frequency and outputs a frequency correction signal;
And a frequency correction circuit that receives the other of the frequency signals and the frequency correction signal, corrects the frequency signal input according to the frequency correction signal to a predetermined frequency, and outputs the frequency signal to the outside. Oscillator. The oscillator according to claim 7 or 8, comprising:
The oscillator is the oscillator according to claim 4,
An oscillator, wherein the drive circuit, the frequency shift detection circuit, and the frequency correction circuit are formed on a lid substrate of the oscillator.

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