JP2012029052A - Method for adjacent placement of electrode structure element and vibrating structure element and mems device utilizing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for adjacent placement of an electrode structure element (a drive electrode) and a vibrating structure element (such as a vibrating beam) placed to face each other, and to provide a MEMS resonator utilizing the same.SOLUTION: An electrode structure element 12 (connected to a slider 20) and a vibrating structure element 13 are formed in a separated state. After the processing finishes, a slide mechanism equipped with the slider 20 is utilized to place the electrode structure element 12 adjacently to the vibrating structure element 13, allowing an opposed placement with spacing 1 μm or less. As a result, improved characteristics of a MEMS resonator are easily achieved even with conventional technology.

Description

  The present invention relates to a method of arranging an electrode structural element and a vibration structural element close to each other. Moreover, it is related with the MEMS device which has a narrow gap using this method.

  2. Description of the Related Art In recent years, technological advances in semiconductor devices have been great, and they have been used over a wide range such as industrial equipment and consumer equipment. In particular, miniaturization and high integration of semiconductor devices have greatly contributed to downsizing, weight reduction, price reduction, and high functionality of devices and systems equipped with the semiconductor devices. However, while miniaturization and high integration of semiconductor devices are achieved, the manufacturing process is becoming larger and more complicated, and the manufacturing equipment is becoming larger and more expensive. Furthermore, the limits of miniaturization are discussed, and development directions other than miniaturization are being sought. A MEMS (microelectromechanical system) device is one example, and it is characterized in that new functions can be realized by miniaturizing mechanical elements and matching with semiconductor technology. In addition, new technologies and new knowledge obtained through the technological development of MEMS devices are reflected in conventional semiconductor processes and contribute to the advancement of the semiconductor field.

  One such MEMS device is a device called “RF-MEMS”. This is a device that operates in a high frequency (RF) band, and is expected to be applied to the communication field, such as filters and oscillators. In RF-MEMS, a high-frequency electric signal is applied between a fixed electrode arranged close to a minute structure (many of a beam and a disk shape) and the structure to mechanically vibrate the structure. . Such vibration is electrically detected as an amount of change in capacitance or the like. In order to increase the operating frequency (vibration frequency) of RF-MEMS, it is necessary to reduce the size of the vibrating structure and reduce the distance between the fixed electrode and the structure. . Many semiconductor processes can be used for such miniaturization of mechanical dimensions, and can be used for higher frequency RF-MEMS.

  There are generally three approaches to configuring MEMS devices. One is “bulk micromachining” for microfabrication of single crystal silicon, one is “surface micromachining” using sacrificial layer etching, and the other is a stacked structure of single crystal silicon (so-called “ "Bulk surface micromachining" using silicon on insulator wafer, SOI wafer ".

  In bulk micromachining, a single crystal silicon wafer is etched from the back side or the front side to create a three-dimensional structure of single crystal silicon. Applications to diaphragm type pressure sensors and acceleration sensors have been put into practical use. However, it is also known that there is a limit to realizing a more complicated three-dimensional structure.

  In surface micromachining, devices are formed by thin film deposition, patterning, and removal of layers between thin films (sacrificial layer etching). Often, a thin film of a silicon layer is deposited into a vibrating structure. The silicon layer is polycrystalline silicon (polysilicon), and the thickness is usually set to about 0.1 to 3 micrometers so as not to increase the residual stress in the layer. Surface micromachining is easy to divert a general semiconductor manufacturing line, but the mechanical properties of polycrystalline silicon depend on the manufacturing conditions, and polycrystalline silicon has inferior mechanical properties compared to single crystal silicon. Etc. have been pointed out.

  FIG. 28 shows a cross-sectional structure of an RF-MEMS produced by surface micromachining. This figure is described in the following cited non-patent document 1. In FIG. 2A, the beam 1 is made of polycrystalline silicon and can vibrate (thickness is 2 micrometers in the figure), and the single crystal silicon substrate 2 is a base portion. The drive electrode 3 disposed facing the beam 1 is fixed to the single crystal silicon substrate 2. FIG. 6A is a sectional view of the structure immediately after the “sacrificial layer etching” is completed, and the beam 1 is illustrated as if it is floating (in the drawing, it is drawn as 2000 angstroms). ) Is fixed to the single crystal silicon substrate 2 at a location not shown in a direction perpendicular to the drawing. In FIG. 6B, a DC voltage 4 is applied from the outside, and the beam is attracted to the fixed electrode side by an electrostatic force, deformed, and a narrow gap 5 (illustrated as 500 angstroms in the figure) is realized. It has been shown. In this state, the beam 1 vibrates in the vertical direction of the drawing by the high frequency signal applied to the drive electrode 3. Because of the narrow gap 5, the vibration amplitude in the vertical direction of the beam 1 is large, and the electrical characteristics as RF-MEMS are also improved.

A MEMS device utilizing polycrystalline silicon and surface micromachining has an advantage that a conventional semiconductor production line can be used. However, the structure shown in FIG. 28 has the following problems.
(1) It is difficult to increase the mechanical strength by increasing the thickness of the mechanical element.
When forming polycrystalline silicon, the process conditions are controlled to reduce the internal stress of the thin film polycrystalline silicon as much as possible. However, the internal stress is sensitive to the conditions of the forming process, and the residual internal stress tends to increase as the thickness of the thin film increases. For this reason, when a structure in which a part of the mechanical element (for example, a beam portion) is levitated from the substrate so as to vibrate is realized, the remaining internal stress is released and the beam is deformed (usually twisted or bent) To be observed). For this reason, the thickness of polycrystalline silicon is limited to about 3 micrometers at the maximum.
(2) It is difficult to control the formation conditions of polycrystalline silicon.
As described above, if internal stress remains during the formation of polycrystalline silicon, beam deformation or the like occurs after the sacrificial layer etching, and the desired operation becomes difficult. For this reason, it is required that the formation conditions (temperature, gas component ratio, gas component amount, atmosphere, etc.) of polycrystalline silicon be strictly controlled. For this reason, there are many problems in terms of manufacturing technology, such as setting conditions for each semiconductor manufacturing line and ensuring stability of conditions.
(3) The number of photomasks increases due to sacrificial layer etching.
In the conventional example illustrated in FIG. 28, an oxide film (to be a sacrificial layer) sandwiched between the mechanical element and the substrate is removed by etching in order to float the vibrating mechanical element from the substrate. . In addition, when a DC voltage 4 is applied, the mechanical element floats from the substrate through a certain distance (500 angstrom in the figure), and in order to prevent contact with the substrate, a dimple 6 A so-called minute convex structure is formed. That is, the beam 1 as a mechanical element has a uniform thickness, but its front and back surfaces are not flat. A plurality of photomasks are used to create such a structure and pattern. In the case of FIG. 28, five photomasks are required. Further, when integrating a MEMS device and a peripheral circuit such as a driving circuit on the same chip, a processing photomask for the MEMS portion and a photomask for forming the peripheral circuit are required separately. From the viewpoint of manufacturing, it is advantageous to reduce the number of photomasks as much as possible. In this respect, an increase in the number of photomasks for sacrificial layer etching is a major problem from the viewpoint of manufacturing technology.
(4) There is a high risk of destruction in the process after the sacrificial layer etching.
When the sacrificial layer etching is completed, a narrow gap (2000 angstrom in FIG. 28) is formed between the beam 1 and the drive electrode 3 described above. For this reason, in the process after the sacrificial layer etching, there is a risk that the beam 1 is bent toward the driving electrode 3 and is fixed to the driving electrode 3 due to impact or electrostatic charging. When this sticking occurs, it is impossible to lift the beam 1 away from the drive electrode 3 and to float again. For this reason, preventing these destruction has been a problem.
(5) Since the deformation of the beam is large, there is a high possibility that the physical property value will change.
In the conventional example of FIG. 28, the gap of 2000 angstroms is reduced to 500 angstroms (gap 5) by the DC power supply 4. That is, the displacement of the beam 1 (thickness is 2 micrometers) is 1500 angstroms (0.15 micrometers). The ratio of the displacement amount to the thickness reaches about 10%, and the vibration operation is performed in the large deformation region. As a result, mechanical property values such as rigidity change as compared with the case where the displacement amount (ratio) is small. The subject which requires the design of RF-MEMS which considered this physical property value fluctuation | variation generate | occur | produces.

  As described in the previous paragraph, an approach that utilizes polycrystalline silicon and surface micromachining has advantages but many issues that need to be solved.

  In bulk surface micromachining, which is a third approach for constructing MEMS devices, an SOI wafer in which two single crystal silicon layers are bonded via an oxide film is used, and a silicon layer (also called a device layer) on the surface side of the oxide film is used. Machine elements and electronic circuits are formed, and a silicon layer (also called a substrate layer) on the back side of the oxide film is used as a support for the device layer. In bulk surface micromachining, a device layer or a substrate layer is often directly finely processed by etching or the like. Sacrificial layer etching is relatively rarely used for device layer processing. The thickness of the device layer is about 1 to 100 micrometers, and an optimum thickness is selected depending on the device to be created. The device layer in a region where no mechanical element or electronic circuit is formed may be removed by etching. Here, since it is required to deeply etch a narrow region, a unique manufacturing apparatus is used. However, since the device layer forming the mechanical element and the electronic circuit is single crystal silicon, there is an advantage that a design method and a processing method used in a normal silicon semiconductor device can be used as they are.

  FIG. 29 is a scanning electron microscope (SEM) photograph of RF-MEMS produced by bulk surface micromachining. The figure (a) is described in the following cited non-patent document 2, and the figures (b) and (c) are described in the cited non-patent document 3. The MEMS shown in the figure is composed of a beam having fixed ends (a thin rod-like shape at the center is lifted) and a drive electrode disposed facing the center of the beam. These beams are excited by a high-frequency voltage signal applied between the drive electrodes and vibrate in the left-right direction. The device shown in FIG. 5A is composed of a beam having a length of 760 micrometers, a width of 10 micrometers, and a thickness of 20 micrometers, and a drive electrode having a width of 100 micrometers arranged to face the central portion of the beam. Has been. The distance between this beam and the drive electrode is 4 micrometers. The primary resonance frequency is observed in the vicinity of 140 kHz in the device of FIG. On the other hand, FIG. 5B shows a device improved so that the beam is miniaturized and the primary resonance frequency becomes higher. The device shown in FIG. 6B is composed of a beam having a length of 76 micrometers, a width of 10 micrometers, and a thickness of 20 micrometers, and drive electrodes disposed so as to face each other over the entire length of the beam. . In the device of FIG. 5B, a primary resonance frequency is observed in the vicinity of 11 MHz. The distance between this beam and the drive electrode is 1 micrometer. Both devices are fabricated by processing an SOI wafer having a device layer thickness of 20 micrometers.

Compared with the conventional example illustrated in FIG. 28, the MEMS device made by single crystal silicon and bulk surface micromachining has the following advantages.
(1) It is easy to increase the mechanical strength by increasing the thickness of the mechanical element.
Using SOI wafers, the thickness of the machine element can be made equal to the thickness of the device layer. For this reason, by increasing the thickness of the device layer, a mechanical element having high mechanical strength can be easily realized.
(2) Since single crystal silicon is used, there is no influence of residual stress.
Since the SOI wafer uses single crystal silicon for the device layer, it has a feature that the internal residual stress is small regardless of the conditions of the MEMS device formation process. For this reason, even if a machine element is created by micromachining, no deformation occurs.
(3) The number of photomasks is small.
In the example illustrated in FIG. 29, it is possible to create with two photomasks, and the number of masks can be significantly reduced as compared with “5” in the example of FIG.
(4) Since the deformation of the beam is small, the physical property value does not change.
Since the method of forcibly bringing the beam and the drive electrode close is not adopted, the vibration of the beam is in a small amplitude operation range. For this reason, it is possible to avoid a change in the physical property value during the large amplitude operation.

  In the production of the RF-MEMS in FIG. 29, etching using reactive gas (RIE; reactive ion etching) is used. In RIE, hole processing with a diameter of about 2 micrometers and a depth of about 4 micrometers is possible at the mass production level by selecting the gas to be used and setting the atmospheric conditions (gas concentration, reaction temperature, etc.). The “depth of 4 micrometers” exemplified here is sufficient for a general semiconductor device in which electronic circuits are integrated. For example, in a random access memory (DRAM), a “trench” structure is sometimes used to increase the storage capacity. However, with the miniaturization of memory cells, the depth of the trench has become relatively shallow. For this reason, the “depth of 4 micrometers” is a necessary and sufficient processing depth. Of course, in the advanced research field, it has been reported that a deep hole having a diameter of 1.5 micrometers and a depth of 30 micrometers is created by RIE, but this is also a limit value.

  However, as described above, in the device of FIG. 29B, the distance between the beam and the drive electrode is 1 micrometer. This value is a relatively large value when viewed from the processing technology in the current semiconductor process, but is a minute value in the processing technology using RIE described above. Further, when forming a gap between the beam and the drive electrode, processing with a large aspect ratio (ratio of processing depth to processing width) of 1 micrometer in width and 20 micrometers in height is required. This large aspect ratio is difficult to achieve with current semiconductor processes including RIE. On the other hand, in order to realize high-frequency RF-MEMS, it is essential to reduce the length of the beam, and as a result, the electrostatic capacitance between the beam and the drive electrode is also reduced. Since the electrical signal from the RF-MEMS is a fluctuation amount of the capacitance induced by the vibration of the beam, it is inevitable that the electrical signal becomes weak as the frequency increases. As a method for obtaining a large electric signal, (1) the distance between the beam and the drive electrode is reduced (narrow gap), and (2) the area where the beam and the drive electrode are opposed to each other is increased, so that electromechanical coupling One example is to increase the coefficient. That is, in RF-MEMS produced by bulk surface micromachining, (1) how deep and a narrow gap of 1 micrometer or less is formed, or (2) how the beam and drive electrode are opposed to each other It is an important technological development item to make the structure large.

  If a narrow gap can be easily realized, it is possible to increase the frequency of the RF-MEMS. Such a device is advantageous for the advancement of portable devices such as mobile phones. In recent years, although the frequency range that can be used is limited, the amount of traffic by portable devices has increased. How can I find a frequency band that is not used instantaneously and communicate in this band? "Is attracting attention. This technique, also called cognitive communication, requires a large number of filters and oscillators to operate the device in many frequency bands. Quartz resonators and surface acoustic wave (SAW) devices that are widely used at present have an upper limit on the operating frequency because of their structure. Furthermore, the occupied area / volume when multiple devices are used is an issue. It has become. On the other hand, a resonator (including a filter, an oscillator, and the like) configured by RF-MEMS is manufactured by a semiconductor process, and thus has a feature that it can be simultaneously created and integrated with a peripheral circuit. For this reason, there is a great expectation for practical application of RF-MEMS, but overcoming the barriers of “narrowing gap” and “increasing the area of competition” when operating at high frequency is an important issue.

Conference presentation paper Wang et al., “VHF Free-Free Beam High-Q Micromechanical Resonators”, J. Am. Microelectromechanical Systems, Vol. 9, no. 3, September 2000 Conference presentation paper Ishino et al., “Three-dimensional vibration characteristics of single-crystal silicon MEMS resonators”, Proceedings of the 25th Symposium on Sensors, Micromachines and Applied Systems, 551-557, October 2008 Conference presentation paper Hashimoto et al., "Development of 10MHz band MEMS resonator using narrow gap fabrication process", Proceedings of the 26th "Sensor Micromachine and Applied Systems" Symposium, pages 116-119 (C1-4), 2009 October

  When a MEMS device is produced by single crystal silicon and bulk surface micromachining, it is necessary to form a narrow and deep gap. FIG. 29 shows a conventional example of RF-MEMS produced by bulk surface micromachining. As described in the paragraph “Background Art”, in the device shown in FIG. 5B, a gap of 1 μm is formed with a depth of 20 μm. For the formation of the gap, etching using reactive gas (RIE; reactive ion etching) is used. Using semiconductor process technology (RIE) that is currently in practical use, it is possible to form a hole with a diameter of about 2 micrometers and a depth of about 4 micrometers in a silicon substrate. However, in the example of FIG. 29, a finer and deeper hole is formed. In a semiconductor process such as RIE, it is known that if the area to be processed is small or the processing depth is large, processing becomes difficult and processing time (etching speed) is slow. This is because (1) the reaction gas hardly enters the hole, and (2) the reaction product hardly discharges from the hole. FIG. 2C is an enlarged photograph of the gap portion (1 micrometer) of the MEMS resonator. A mask that covers a region not etched by the RIE process is a chrome thin film, and a focused ion beam (FIB) is used for patterning. Using this mask pattern, the silicon substrate is etched with a width of 1 micrometer. However, in order to form a beam with a thickness of 20 micrometers, it takes five times the normal time. Here, “normal” indicates a case where only a silicon substrate (not patterned on the surface) other than the gap region is etched, or a case where the gap is a large value such as 10 micrometers. FIG. 3C shows that the mask pattern is eroded by the reaction gas due to the etching over a long time, and a gap having a uniform width is not formed.

  In order to realize high-frequency RF-MEMS, it is essential to reduce the length of the beam, and as a result, the capacitance between the beam and the drive electrode is also reduced. Since the electrical signal from the RF-MEMS is the amount of change in the capacitance induced by the vibration of the beam, it is inevitable that the electrical signal becomes weak as the frequency increases. One technique for obtaining a large electrical signal is to increase the electromechanical coupling coefficient. The electromechanical coupling coefficient is a conversion coefficient when detecting the vibration amplitude of a mechanically vibrating beam as an electric signal. If this electromechanical coupling coefficient is increased, a large electrical signal can be obtained even with a small amplitude. In order to increase the electromechanical coupling coefficient, there are methods such as (1) reducing the distance between the beam and the drive electrode (narrowing the gap), and (2) increasing the area where the beam and the drive electrode face each other. Therefore, in RF-MEMS created by bulk surface micromachining, (1) how deep and a narrow gap of 1 micrometer or less is formed, or (2) how the facing area is large. It is an important issue to be solved.

  In the method of manufacturing a semiconductor device, (1) an electrode structure element is connected to a slider, (2) a vibration structure element facing the electrode structure element through a first distance is provided, and (3) the slider is slid The sliding mechanism moves the slider in a designated direction until the distance between the electrode structural element and the vibration structural element becomes a designated second distance that is shorter than the first distance.

  In the preceding paragraph, “connected” means that the electrode structural element and the slider are integrated. As a specific example of such integration, the slider and the electrode structural element are made of the same material, and a part of the slider functions as the electrode structural element. Another example is a case where the electrode structural element is mounted on the slider via an insulating layer or the like. That is, there are many forms of “connection”, and the specific form is not limited.

  In the preceding paragraph, “opposing” indicates a state in which the electrode structural element and the vibration structural element are arranged to face each other.

  The constituent materials of the “electrode structural element” and the “vibrating structural element” are not necessarily metals. For example, it may be a semiconductor material such as silicon, or a material that imparts conductivity to the surface of an insulator such as resin. The “first distance” is larger (longer) than the “second distance”. Further, the “slide mechanism” is a mechanism that moves the slider with a force generated by an electrostatic force or an electromagnetic force. In general, the electrode structural element moves linearly to the position of the “second distance” while maintaining the posture in which the electrode structural elements face each other through the “first distance”. However, it is not limited to this. For example, the trajectory of the electrode structural element during movement may be a straight line, a circular arc, a zigzag or the like. The “designated direction” means that the electrode structure element has moved from a state where the electrode structure element is located at a “first distance” to a state where the electrode structure element is located at a “second distance”. It only shows the direction between the final states.

  The “designated second distance” does not include “zero”. “Zero” means that the electrode structural element and the vibration structural element are in “contact” (corresponding to the contact point of an electrical switch being connected). The vibration structural element is characterized by being “in an electrically insulated state”. In addition, in the state where the “designated second distance” is reached, the electrode structural element and the vibration structural element may be “partially and mechanically contacted”. Even in the case, it is required to be in an “electrically insulated state”.

  The “designated second distance” is often designated by a “stopper” incorporated in the slide mechanism, but is not limited thereto. For example, the “second distance” may be designated by electrical or mechanical feedback control by a “slider position detection mechanism” incorporated in the slide mechanism. In addition, after the electrode structural element has moved to the “designated second distance”, the distance between the electrode structural element and the vibration structural element maintains the “designated second distance”. Preferably it is. For example, this is a case where the slider is assumed to move by a minute amount due to external vibration or impact. When the “designated second distance” is determined by the “stopper”, in order to prevent such a small amount of movement, the slider is attached to the vibrating structural element constantly or periodically. The slide mechanism that presses toward the end is preferable. As an example of such a slide mechanism, the slide mechanism is configured such that the electrostatic force or electromagnetic force described in the previous paragraph is continuously or periodically generated, or a spring force is used. Can be mentioned.

  In this paragraph, the formation of the electrode structural element and the vibration structural element will be described. The electrode structural element and the vibration structural element may be formed by the same process, but are not limited thereto, and may be formed by different processes. However, when formed by the same process, the respective base materials are placed at a distance (the “designated first distance”). In the formation process, (1) the presence of the vibration structural element is present. It is necessary that the formation of the electrode structural element is not affected, and (2) the presence of the electrode structural element does not affect the formation of the vibration structural element. A feature of the present invention is that, after the electrode structural element and the vibration structural element are formed, they are arranged close to each other (the “designated second distance”) by the slide mechanism of the slider. is there.

  The slider is made of a material containing silicon.

  The slide mechanism is made of a material containing silicon, and the slider is moved by a driving force including an electrostatic force.

  The material constituting the slider and the slide mechanism of the slider may be metal, resin, semiconductor, or a mixture (hybrid material) thereof. In consideration of the level of microfabrication technology, a silicon semiconductor is preferable, but not limited thereto. The mechanism for generating the driving force may be an electrostatic force, an electromagnetic force, an ultrasonic wave, or a combination of these. In the MEMS device field, electrostatic force is often used, but is not limited thereto.

  In this paragraph, an electrostatic force that is one of the driving forces for moving the slider is described. In the MEMS field, a mechanism using a “comb electrode” as an “actuator” using electrostatic force is well known. In this mechanism, a movable electrode can be moved in the longitudinal direction of the comb teeth by applying a DC voltage to a pair of comb-shaped electrodes (one is fixed and the other is movable). It is a feature that moves. On the other hand, it is also possible to apply a mechanism that applies a DC voltage to two electrodes arranged opposite to each other without using a comb-shaped electrode and uses a suction force generated between these electrodes. In this mechanism, a DC electric field generated between the two electrodes (one is fixed and the other is movable) induces the attraction force, and the movable electrode is fixed to the fixed electrode. Move to the side. The DC voltage required for movement depends on the distance between the two electrodes. If the distance is large, a large DC voltage is required. As described in this paragraph, there are various utilization forms of the electrostatic force used when moving the slider, and any form can be applied to the present invention.

  The designated second distance is determined by a stopper disposed on the electrode structural element, the vibration structural element, or the slider.

  The “designated second distance” may be realized by arranging a mechanical stopper. The positions where such stoppers are arranged are (1) the surface of the electrode structure element, which faces the vibration structure element, and (2) the surface of the vibration structure element, which faces the electrode structure element. (3) a region of the slider, which is a region where the electrode structural elements are not connected. In the arrangement examples (1) and (2), the electrode structural element and the vibration structural element are in contact with each other with the stopper interposed therebetween. Therefore, if it is desired that the electrode structural element and the conductor are electrically insulated, the stopper may be formed of an insulator, or the surface of the electrode structural element or the vibration structural element. It is necessary to coat with an insulator. When the electrode structural element or the vibration structural element is made of a semiconductor such as silicon, the stopper is also made of a semiconductor such as silicon, and the insulator is formed by oxidizing the surface thereof. Is possible.

  The stopper described above is formed over the entire thickness direction such as the surface of the electrode structural element facing the vibrating structural element or the surface of the vibrating structural element facing the electrode structural element. Not necessarily. For example, the electrode structure element surface may be formed only in a specified region in the thickness direction of the electrode structure element surface among surfaces facing the vibration structure element. A specific example of this is a case where the stopper is partially formed in a “shallow” region of the surface of the electrode structural element that faces the vibrating structural element.

  The vibrating structural element is a vibrating body of a MEMS resonator, and the electrode structural element is a driving electrode that vibrates the vibrating body.

  One field of application of the present invention is a MEMS resonator. As an example of such a resonator, an electrostatic force generated by applying a high-frequency signal between the drive electrode and the beam, which is composed of a beam fixed at both ends and a drive electrode disposed opposite to the beam. The beam is vibrated. When the present invention is applied to this structure, the vibrating structural element may be a beam (vibrating body), and the electrode structural element may be a driving electrode. In this configuration, the vibration structural element facing the electrode structural element (drive electrode) has a specified region that vibrates as a beam and a region of the vibration structural element that does not include the specified region. It is necessary to prevent vibration. Further, the number of the electrode structural elements to be drive electrodes is not limited to one, and two or more may be arranged.

  Another example of the MEMS resonator is a disk (flat plate) type. The disk-type resonator includes a disc or polygonal diaphragm having a fixed central region, and drive electrodes arranged along the periphery of the diaphragm. An example in which the present invention is applied to this structure is that the vibration structural element is the diaphragm and the electrode structural element is a drive electrode. Further, the number of the electrode structural elements to be drive electrodes is not limited to one, and two or more may be arranged.

  Another example of the MEMS resonator is a ring type. The ring-type resonator includes a donut-like plate-shaped diaphragm and drive electrodes arranged along the periphery of the diaphragm. In the donut-shaped diaphragm, a designated area on the outer periphery or inner periphery is fixed. As an example in which the present invention is applied to this structure, the vibrating structural element may be the donut-shaped and flat plate-shaped diaphragm, and the electrode structural element may be a drive electrode. Further, the number of the electrode structural elements to be drive electrodes is not limited to one, and two or more may be arranged.

  The slider described above has a “movable part” having an electrostatic force as a driving force. On the other hand, the vibrator (beam or disk) of the MEMS resonator described above is also mechanically movable. For this reason, when the “movable part” of the slider is excited when the MEMS resonator is excited, the vibration of the MEMS resonator may be inhibited. In order to eliminate such inconvenience, the resonance frequency f1 of the “movable part” of the slider may be set low, while the resonance frequency f2 of the vibrating body of the MEMS resonator may be set high. For example, if f1 is set to approximately 100 Hz and f2 is set to a value exceeding 1 MHz, the inconvenience described above can be avoided. There are many design guidelines for setting f1 low, but as an example, the mass of the slider may be increased.

  A MEMS resonator which is a form of a MEMS device includes: (1) a slider; (2) an electrode structure element coupled to the slider; and (3) the electrode structure element facing each other via a first distance. (4) the slider has a slide mechanism for sliding the slider in a specified direction, and (5) the amount of movement of the slider by the slide mechanism is: It is configured to be determined by a designated second distance that is shorter than the first distance.

  The MEMS resonator includes a vibrating structure (corresponding to the “vibrating structural element”) and a drive electrode (corresponding to the “electrode structural element”) disposed in proximity to the structural body through a narrow gap. It is configured. The shape of this structure includes a beam with fixed ends, a disk or ring with fixed center. As the operating frequency increases, the electrical signal obtained from the resonator tends to decrease. For this reason, it is essential to take measures to increase the electric signal. An example of this is to increase the electromechanical coupling coefficient. It is known that the electromechanical coupling coefficient is inversely proportional to the square of the gap size and proportional to the facing area between the structure and the drive electrode. For this reason, a narrow gap greatly contributes to high performance of the MEMS resonator. However, in the prior art, it has been difficult to form a narrow gap with a high aspect ratio. For this reason, the structure and the drive electrode are formed at a “separated distance” (corresponding to the “first distance” in the previous paragraph), and after the respective shape processing is completed, the slide mechanism is used. The present invention has been devised in which both are arranged in “close proximity” (corresponding to the “second distance” in the previous paragraph). Such a close placement technique can easily achieve extremely narrow gaps with high aspect ratios. For example, a MEMS resonator having a gap whose depth does not exceed 1 micrometer (submicron) and a depth of 30 micrometers is realized.

  The “designated second distance” does not include “zero”. “Zero” means that the electrode structural element and the vibration structural element are in “contact” (corresponding to the contact point of an electrical switch being connected). The vibration structural element is characterized by being “in an electrically insulated state”. In addition, in the state where the “designated second distance” is reached, the electrode structural element and the vibration structural element may be “partially and mechanically contacted”. Even in the case, it is required to be in an “electrically insulated state”.

  The slider, the electrode structure element, and the vibration structure element are made of a material containing silicon.

The slide mechanism is made of a material containing silicon, and the slider is moved by a driving force including an electrostatic force.

  If the slider, the electrode structure element, and the vibration structure element are made of a silicon semiconductor, they can be formed at a time by a semiconductor process including RIE, so that the MEMS resonator can be easily formed. Even in such a configuration, the structure body and the drive electrode are formed in a “separated” state, and after the respective shape processing is completed, both are arranged in the “close” state by the slide mechanism described above. The features of the present invention are utilized. The slider is preferably moved by a slide mechanism that can be produced by a semiconductor process, but this is not a limitation. When electrostatic force or electromagnetic force is used for driving, it can be constituted by a semiconductor process. In addition, a configuration in which ultrasonic waves are used for driving, or a combination of electrostatic force, electromagnetic force, and ultrasonic waves is possible. Furthermore, it is also possible to maintain the “close” state by using a method such as feedback control together with the slide mechanism of the slider.

  The designated second distance is determined by a stopper disposed on the electrode structural element, the vibration structural element, or the slider.

  The size required for the second distance is a minute distance not exceeding 5 micrometers (more preferably a distance not exceeding 1 micrometer). The smaller the value, the more difficult it is to stop the slider at the second distance. The stopper is a mechanism for stopping the slider at the second distance, and the presence of the stopper makes it easy to stop the slider with high positional accuracy. Note that the position where the stopper is disposed is one of the electrode structural element, the vibration structural element, and the slider. Further, a plurality of the stoppers may be arranged on the plurality of components.

  In this paragraph, the arrangement of the stopper will be described. For convenience of explanation, the case where the stopper is disposed on the electrode structural element will be described, but the same applies to the case where the stopper is disposed on the vibration structural element or the like. The conductive drive body vibrates with a high-frequency signal supplied from the outside. When this vibration mode is analyzed, it is found that the conductive drive body has “nodes” and “antinodes”. A “node” is a region where the spatial amplitude of the vibration is zero or very small, and an “antinode” is a region where the spatial amplitude of the vibration is large (generally the maximum amplitude). When the stopper is disposed corresponding to the “node” region, the contact of the stopper with the vibration structural element does not affect the vibration, or the influence thereof is small. This situation applies to any of the “beam type”, “disk type”, and “ring type” MEMS resonators. For this reason, the vibration of the vibration structural element is almost the same as the form without the stopper, which is a great advantage in the design of the resonator.

  The vibration structural element is a vibration beam of a beam-type MEMS resonator fixed at both ends, and the electrode structural element is a drive electrode of the beam-type MEMS resonator.

  The vibrating structural element is a vibrating body of a ring type or disk type MEMS resonator, and the electrode structural element is a driving electrode of the ring type or disk type MEMS resonator.

  There are many types of MEMS resonators other than the “beam type”, “disk type”, and “ring type” described in the previous paragraph and the previous paragraph. For example, a configuration in which a plurality of beams are arranged in a two-dimensional space (this is an image of a grilled net), a mechanism for connecting the beams to each other in an area where each beam intersects, and a torsional vibration of the beam is used. is there. In any form, the present invention can be applied when a narrow gap is required and reducing the gap width contributes to improvement in characteristics.

  When the MEMS resonator is formed, an SOI wafer is used, and when bulk surface micromachining is adopted, the device layer of the wafer is used for the vibrating beam or disk or ring and the electrode structural element. can do. Further, the vibration beam or disk or ring and the electrode structure element are composed of (1) the device layer and (2) a specific region of the substrate layer located immediately below the device layer, (3) It is also possible to electrically connect the device layer and the region. By adopting such a configuration, it is possible to increase the area where the vibrating beam or disk or ring and the electrode structure element face each other, and increase the electromechanical coupling coefficient.

  In the configuration of the MEMS resonator described above, the vibration structural element is mechanically vibrated by a signal applied to the electrode structural element in the state of the “designated second distance”. On the other hand, in the state of the “designated first distance”, the vibration structural element does not vibrate even when a signal is applied to the electrode structural element. This is because the above-described electromechanical coupling coefficient is small at the “designated first distance”. For this reason, the operation of the MEMS resonator can be selected ON (vibrating) or OFF (not vibrating) depending on the position of the slider (depending on the driving force of the sliding mechanism). That is, the slider can be moved when it is desired to operate the MEMS resonator, and the slider is not moved when it is not desired to operate.

  A MEMS device includes: (1) a vibration structural element that vibrates mechanically; and (2) a first structure that is disposed opposite to the first side of the vibration structural element via a third distance and coupled to the first slider. (3) a first slide mechanism for moving the first slider in a first direction, and (4) the first side of the vibration structural element is the vibration structural element. A second electrode structural element disposed opposite to the second side sandwiched by a fourth distance and connected to the second slider; and (5) the second slider is a second side And (6) determining the amount of movement of the first slider by the first slide mechanism at a designated fifth distance, and (7) The amount of movement of the second slider by the second slide mechanism is a designated sixth distance. A constant.

  In the configuration described in the previous paragraph, the first electrode structure element and the second electrode structure element are arranged on both sides of a single vibration structure element. In this configuration, the first electrode structural element and the second electrode structural element are disposed at the third distance and the fourth distance (both are “separated”), respectively. Thus, the first electrode structural element and the second electrode structural element are processed. After the processing, the first slide mechanism and the second slide mechanism are moved to the fifth distance and the sixth distance (both are “close”), respectively, so that a narrow gap is formed. Composed. The third distance is greater than the fifth distance, and the fourth distance is greater than the sixth distance.

The “vibrating structural element” described in the previous paragraph is a vibrating beam (beam type resonator), a vibrating ring (ring type resonator), a vibrating disk (disk type resonator), or the like. Moreover, you may be the vibration structural element of MEMS resonators other than these. For example, in a form in which a plurality of beams are arranged in a two-dimensional space (this is an image of a grilled net), a mechanism for connecting the beams to each other in a region where each beam intersects, and torsional vibration of the beam is used. is there.

  The first slider, the first electrode structure element, the vibration structure element, the second slider, and the second electrode structure element are made of a material containing silicon, and electrostatic force is generated. The first slider and the second slider are moved by the included driving force.

  When the first electrode structural element, the second electrode structural element, the first slider, the second slider, and the vibration structural element are composed of a silicon semiconductor, all the structures are formed in a semiconductor process including RIE. Since the elements are collectively formed, the MEMS resonator can be easily manufactured. Even in such a configuration, the vibration structural element, the first electrode structural element, and the second electrode structural element are formed in a “separated” state, and after the respective shape processing is completed, the slide described above is performed. The feature of the present invention in which both are placed in “close proximity” by a mechanism is utilized. Further, the movement of the first slider and the second slider is preferably performed by a slide mechanism that can be created by a semiconductor process, but is not limited thereto. When electrostatic force or electromagnetic force is used for driving, it can be constituted by a semiconductor process. Furthermore, it is possible to use an ultrasonic wave for driving, or a combination of electrostatic force, electromagnetic force, and ultrasonic wave.

  The designated fifth distance is determined by a stopper disposed on the first electrode structural element, or the first slider, or the vibrating structural element, and the designated sixth distance is It is determined by a stopper disposed on the second electrode structural element, the second slider, or the vibration structural element.

  The size required for the designated fifth distance and the designated sixth distance is a minute distance that does not exceed 1 micrometer, and thus the fifth distance and the sixth distance. The smaller the distance, the more difficult it is to stop each slider accurately at the required distance. The stopper is a mechanism for stopping the sliders at the designated fifth distance and the designated sixth distance, and the presence of the stopper causes the first slider and the first slider to be stopped. It is easy to stop the second slider with high positional accuracy. The positions where these stoppers are arranged are any of the first electrode structural element, the second electrode structural element, the vibration structural element, the first slider, or the second slider. It is an area. Further, a plurality of these stoppers may be arranged on the plurality of components described above.

  In this paragraph, an improved configuration of the MEMS resonator described above will be described. More specifically, in a “MEMS resonator” composed of the first electrode structural element, the second electrode structural element, and the vibration structural element, the first electrode structural element is referred to as “driving electrode”. The operation of the configuration in which the second electrode structural element is the “detection electrode” will be described. Electrically, the vibration structural element is at a ground potential, and a high frequency signal (generally, a high frequency signal is superimposed on a DC voltage) is applied to the “driving electrode”. As a result, the vibration structural element vibrates at the frequency of the high-frequency signal (or its harmonic frequency or overtone frequency). Such vibration changes (modulates) the value of the capacitance formed between the vibrating structural element and the second electrode structural element, so that the change is detected as an electrical signal. Such a configuration is characterized in that since the drive side and the detection side are electrically and spatially separated, the circuit configuration on the detection side can be configured independently of the circuit configuration on the drive side.

In this paragraph, another improved configuration of the above-described MEMS resonator will be described. In such an improved configuration, the second electrode structure element connected to the second slider is arranged separately into a 2-1 electrode structure element and a 2-2 electrode structure element. It is a feature. In the “close” state of these electrode structural elements, both are disposed at the designated sixth distance. On the other hand, unlike the second electrode structure element, the first electrode structure element is not separated. In the “close” state of the first electrode structural element, the first electrode structural element is disposed at the designated fifth distance. In this configuration, two electrode structural elements (2-1 and 2-2) are provided on the second side of the vibration structural element, and one electrode is provided on the first side of the vibration structural element. Electrode structural elements are arranged. In this configuration,
(1) The first electrode structure element is moved to the designated fifth distance (“close” state), and the 2-1 electrode structure element and the 2-2 electrode structure element are When placed at the designated fourth distance ("away" state),
(2) The first electrode structure element is set to the specified third distance (in a “separated” state), and the 2-1 electrode structure element and the 2-2 are set to the specified When placed at the sixth distance ("close" state)
(3) The first electrode structural element is moved to the designated fifth distance (in the “close” state), and the 2-1 electrode structural element and the 2-2 electrode structural element are When placed at the designated sixth distance ("close" state)
There are three combinations. In (1) and (2), the vibrating structural element is vibrated at its fundamental frequency (the lowest frequency when the beam resonates), and in (3), it vibrates at the third frequency of the vibrating structural element. Will be. In the above (3), it is directly driven at the harmonic (or overtone) frequency of the vibration structural element. In the above configuration, the resonance frequency can be changed by controlling the first slider and the second slider. In general, when changing the frequency of a resonator, resonators having a plurality of resonance frequencies are arranged in parallel and switched by a switch or the like made of a semiconductor element. However, deterioration of the characteristics of these switches (especially impedance at ON and insulation at OFF) is a problem in the high frequency band. With the above configuration, no switches are required, and the characteristic deterioration of the resonator system caused by these switches can be prevented. Further, in the separation of the second electrode structural element, the number of separations is not limited to two, and two or more electrode structural elements may be separated. The first electrode structural element may be separated into two or more electrode structural elements. In the configuration composed of the first electrode structure element and the second electrode structure element and separated from each other, by selecting a region where each separated electrode structure element is disposed, It is possible to vibrate at the following frequency.

  In the configuration described in the previous paragraph, it is described that there are combinations (1) to (3) depending on the arrangement of the electrode structural elements. In this paragraph, the first electrode structure element is further moved to the designated third distance (a “separated” state), and the 2-1 electrode structure element and the 2-2 electrode A case will be described in which structural elements are arranged at the designated fourth distance (a “separated” state). In such an arrangement, since the vibrating structural element does not vibrate, the MEMS resonator is in an OFF (not operating) state. That is, when the configuration of this paragraph is added, the MEMS resonator can be set to any one of an OFF state and three ON states (corresponding to (1) to (3)).

In this paragraph, another improved configuration of the above-described MEMS resonator will be described. In such an improved configuration, the vibration structural element is not a single element, and two vibration structural elements (here, the first vibration structure) having different mechanical characteristics (for example, the length, width, or thickness of the vibration beam). It is characterized by being separated into an element and a second vibration structural element. The first electrode structure element is disposed opposite to the first vibration structure element, and the second electrode structure element is disposed opposite to the second vibration structure element. In this configuration,
(1) The first electrode structural element is placed at the designated fifth distance (in a “close proximity” state) with respect to the first vibrating structural element, and the second electrode structural element is When disposed at the designated fourth distance (in a “distant” state) relative to the second vibrating structural element;
(2) The first electrode structural element is moved to the designated third distance (in a “separated” state) with respect to the first vibrating structural element, and the second electrode structural element is When disposed at the designated sixth distance (in a “close” state) to the second vibrating structural element;
There are two combinations. In (1), only the first vibrating structural element is vibrated, and in (2), only the second vibrating structural element is vibrated. That is, the resonance frequency can be changed by the first slider and the second control. Such an improved configuration does not require a switch as described in the previous paragraph, and can prevent deterioration of the characteristics of the resonator system due to the switch.

  According to the present invention, a method of arranging an electrode structural element and a vibrating structural element close to each other and a MEMS device using the same are provided. According to the present invention, it is possible to easily form a narrow gap, and the contribution to the advancement of MEMS devices is great.

  In a conventional semiconductor process, it was possible to form a hole having a diameter of 2 micrometers and a depth of 4 micrometers in a silicon substrate. In advanced research, drilling of holes with a diameter of 1.5 micrometers and a depth of 30 micrometers has also been reported. However, for MEMS resonators and the like, finer processing has been required for improving characteristics. For example, an electrode structural element having a thickness of several tens of micrometers and a vibrating structural element are opposed to each other at a distance of 1 micrometer or less. When such a structure is realized by a semiconductor process, a reactive ion etching (RIE) process is suitable, but it has been known that the processing speed (etching speed) decreases as the processing area becomes finer. Therefore, a longer processing time is required, the mask layer for processing is eroded, and the shape of the processed cross section is greatly disturbed. According to the present invention, shape processing is performed in a state in which the electrode structural element and the vibration structural element are separated from each other, and after the processing is finished, the electrode structural element is brought close to the vibration structural element by a slide mechanism, and is disposed in proximity We were able to. As a result, for example, an electrode structure element having a thickness of 20 micrometers and a vibration structure element can be brought close to 1 micrometer or less.

  When creating a MEMS device, a silicon substrate (SOI substrate) called a silicon-on-insulator (SOI) is often used. This is a structure or deposition in which the surface of a silicon single crystal substrate is covered with an oxide film (for example, 1 micrometer in thickness) and a silicon single crystal layer (for example, 20 micrometers in thickness) is pasted thereon. It is the structure made to do. In general, a base substrate is called a “substrate layer”, and a silicon layer on the surface is called a “device layer”. In a MEMS device using an SOI substrate, a micro mechanical element is formed in a device layer. The electrode structural element and the vibration structural element described above are also formed of a part of the device layer. In producing such two structural elements, two structural elements are formed by forming a gap penetrating the device layer. That is, for example, in order to realize a gap of 1 micrometer, the device layer is drilled with a width of 1 micrometer and a depth of 20 micrometers. In the RIE process, it is necessary to remove a reaction product from the processing region at the same time as a reactive gas is fed into the processing region, but these are difficult in processing of 1 micrometer. In the present invention, for example, a hole having a width of about 10 micrometers and a depth of 20 micrometers is formed, and after completion of the processing, the electrode structure element is brought close to the vibration structure element by a slide mechanism, and the distance between the two is 1 It became possible to make it close to become a micrometer. Furthermore, the distance can be set to 1 micrometer or less.

  In this paragraph, an example in which the present invention is applied to a beam-type MEMS resonator will be described. In the beam-type MEMS resonator, the vibration structural element corresponds to a beam, and the electrode structural element corresponds to a drive electrode. In the MEMS resonator, the beam is downsized (for example, the length is shortened and the cross-sectional area is reduced) in order to increase the resonance frequency. However, as a result of the structure miniaturization, the detected electrical signal is also weak. In order to increase the electrical signal, it is important to increase the electromechanical coupling coefficient. It is known that the electromechanical coupling coefficient is inversely proportional to the square of the gap and proportional to the facing area between the beam and the drive electrode. It was effective. Further, the electrode structural element and the vibration structural element are configured by a device layer and a substrate layer in a specific region, thereby increasing the facing area between the electrode structural element and the vibration structural element. . As described above, according to the present invention, it is possible to increase the electromechanical coupling coefficient and increase the electrical signal.

  As described above, the present invention is characterized in that the electrode structure element is brought close to the vibration structure element by a slide mechanism. Such a sliding mechanism could be easily realized by an “electrostatic actuator”. The electrostatic actuator mainly includes an opposed fixed comb-shaped electrode (stator) and a movable electrode (rotor) levitated from the substrate. When a DC voltage is applied between these electrodes, the rotor moves so as to be drawn between the comb electrodes (stator). By using a part of the rotor as the electrode structural element, the electrode structural element can be moved, and can be disposed close to the vibrating structural element.

  The slider described above has a “movable part” whose driving force is an electrostatic force and the vibrator of the MEMS resonator described above is also mechanically movable. In order to prevent the “movable part” of the slider from being excited when the MEMS resonator is excited, the resonance frequency f1 of the “movable part” of the slider is set to, for example, 100 Hz, and the resonance of the vibrating body of the MEMS resonator is performed. The frequency f2 was set to a value exceeding 1 MHz. As a result, excitation of the “movable part” can be prevented and only the vibrating body can be excited.

  By providing a stopper in the slide mechanism, it is possible to control the amount of movement of the electrode structural element. For example, by making the size of the stopper (similar to the height of the protrusion in the planar shape) equal to the “specified distance”, the distance between the electrode structural element and the vibration structural element is accurately set to a predetermined value. It became possible to do.

  With the configuration in which the first electrode structure element and the second electrode structure element are arranged close to each other on both sides of the vibration structure element, it has become possible to provide many functions. For example, by separating the first electrode structure element into two electrode structure elements, the vibration structure element can be directly vibrated at a harmonic or overtone frequency. Such vibration operation can increase the resonance frequency without downsizing the vibration structural element, and can increase the frequency of the MEMS resonator.

  Furthermore, by arranging the two vibrating structural elements in parallel and changing the length of each beam, it is possible to vibrate each of the vibrating structural elements independently. With this configuration, switching between two resonance frequencies can be performed without using a semiconductor switch or the like. As a result, it is possible to avoid deterioration of characteristics due to the impedance at the time of ON and the insulation at the time of OFF due to the semiconductor switch.

  With the configuration in which the first electrode structure element and the second electrode structure element are arranged close to each other on both sides of the vibration structure element, other functions can be provided. For example, the drive system and the detection system can be separated spatially and electrically by setting the first electrode structure element as the drive side and the second electrode structure element as the detection side. .

  In addition to the beam-type MEMS resonator, many advantages as described above can be obtained by applying the present invention to a disk-type or ring-type MEMS resonator.

  The “method for arranging the electrode structure element and the vibration structure element close to each other” according to the present invention is widely applied to the processing field where a narrow gap is required, in addition to the application to the RF-MEMS or the MEMS resonator as described above. Applicable. For example, when applied to a capacitance type MEMS sensor (acceleration sensor, gyro sensor, etc.), a large capacitance change value is output, and high sensitivity of the sensor can also be realized.

It is a figure which shows the method of arrange | positioning an electrode structural element close. <Example 1> It is a figure which shows the structure (-1) of a silicon MEMS device. <Example using electrostatic force> <Example 2> It is a figure explaining operation | movement of the electrostatic actuator shown in Example 2. FIG. It is a figure which shows the structure (-2) of a silicon MEMS device. <Example using electromagnetic force> <Example 3> It is a figure explaining composition (-3) of a silicon MEMS device. <Example Using Ultrasonic Vibration> <Example 4> It is a figure explaining composition (-4) of a silicon MEMS device. <Other examples using electrostatic force> <Example 5> It is a figure explaining the structure (-1) of a MEMS resonator. <Vibrating beam> <Example 6> It is a figure explaining the electromechanical coupling coefficient in a MEMS resonator. It is a figure explaining the electromechanical operation | movement of a MEMS resonator. It is a figure explaining the manufacturing process of a MEMS resonator. <Example 7> It is a figure explaining composition (-1) of a stopper. <Example 8> It is a figure explaining composition (-2) of a stopper. <Example 9> It is a figure explaining the structure (-3) of a stopper, and its manufacturing method. <Example 10> It is a figure explaining composition (-4) of a stopper. <Example 11> It is a figure explaining the structure (-5) of a stopper. <Example 12> It is a figure explaining the structure (-2) of a MEMS resonator. <Vibrating beam> <Example 13> It is a figure explaining the structure (-3) of a MEMS resonator. <Vibrating beam> <Example 14> It is a figure explaining the structure (-4) of a MEMS resonator. <Vibrating beam> <Example 15> It is a figure explaining the MEMS resonator which can enlarge an electromechanical coupling coefficient. <Area where Electrode Structural Element and Vibrating Beam Oppose> <Example 16> It is a figure explaining the structure of FIG. It is a figure explaining the manufacturing process of a MEMS resonator. <Example 17> It is a figure explaining the structure (-2) of a MEMS resonator. <Vibrating beam> <Example 18> It is a figure explaining the structure (-3) of a MEMS resonator. <Vibrating beam> <Example 19> It is a figure explaining the structure (-4) of a MEMS resonator. <Vibrating beam> <Example 20> It is a figure explaining the structure (-5) of a MEMS resonator. <Disk> <Example 21> It is a figure explaining the structure (-6) of a MEMS resonator. <Disk> <Example 22> It is a figure explaining the structure (-7) of a MEMS resonator. <Octagonal Disc> <Example 23> It is a figure which shows the cross section of the device produced by the surface micromachining. <Conventional example 1> It is a photograph of a device created by bulk surface micromachining. <Conventional example 2>

  Hereinafter, a method for arranging an electrode structure element and a vibration structure element close to each other and a MEMS device using the same will be described in detail with reference to the drawings.

<Method of arranging electrode structure elements close to each other>
FIG. 1 is a diagram for explaining a method of disposing the electrode structural element and the vibration structural element close to each other in the first embodiment. FIG. 6A shows the electrode structural element and the vibration structural element in an unprocessed state (not separated into two structural elements, but remains as a single structural element). Shows the state where the processing to the electrode structural element and the vibration structural element is completed and arranged “separated”, and FIG. 8C shows the state where the electrode structural element and the vibration structural element are arranged “close”. Each state is shown. In the figure, the proximity arrangement method of the electrode structural element and the vibration structural element is shown in principle, and it does not always match the actual form. In FIG. 2A, the structural element 10 shows the two structural elements in an unprocessed state. Since the structural element 10 is unprocessed, it is not separated into two. The slider 20 is provided with a slide mechanism (not shown), and can move in the left-right direction in the drawing above the base portion 21. The slider 20 is provided with a protrusion 22. The structural element 10 is connected to the slider 20 via the insulating layer 11 for electrical insulation from the slider. Here, “connected” means integration with the slider 20, and is illustrated as if it is bonded in the figure, but is not limited thereto. The structural elements described above are arranged on the surface of the basic base 26. When the central portion of the structural element 10 and the insulating layer 11 is selectively removed by a technique such as etching in the state of FIG. 11A, the state of FIG. In the figure, the electrode structural element 12 and the vibration structural element 13 are disposed to face each other via a distance d1. Note that the distance d1 is patterned on the mask at the time of etching as the “designated first distance” when the “selective removal” is performed. The electrode structural element 12 is connected to the slider 20 via an insulating layer 14. Moreover, the case where the vibration structural element 13 is connected to the base portion 25 through the insulating layer 15 is shown. FIG. 2C shows a state in which the slider 20 is moved in a specified direction (rightward in the drawing) and the protrusion 22 is in contact with the base portion 25. In such a state, the electrode structural element 12 and the vibration structural element 13 are disposed to face each other via a “designated second distance” (denoted as d2 in the drawing). The “designated second distance” is smaller than the “designated first distance”. The “designated second distance” is a distance not exceeding 5 micrometers. The distance d2 is determined by the length of the projection 22 described above, and if the length is shortened, the gap formed between the electrode structure element 12 and the vibration structure element 13 can be reduced. In other words, the protrusion 22 functions as a “stopper” that stops the movement of the slider 20 at a desired position (position where the gap interval is the distance d2).

  In FIG. 1, the protrusion 22 is used to place the electrode structural element 12 at a “designated second distance”. However, it is also possible to use a technique such as “feedback control” for detecting the position of the slider 20 and controlling the movement of the slider 20 without moving the projection 22.

  The specified second distance (illustrated by d2 in the figure) is a finite value that does not include zero. That is, the electrode structural element 12 and the vibration structural element 13 are not in contact with each other, are electrically insulated from each other, and their mechanical behavior including vibration is not hindered. However, when the projection 22 that functions as a stopper is provided on the electrode structural element 12 or the vibration structural element 13 (not shown), (1) the projection 22 is made of an insulator to make electrical Insulation is ensured, and (2) the mechanical behavior can be prevented from being hindered by reducing the area where the projection 22 contacts the other side. Even in such a configuration, since the protrusion 22 is an “insulator”, the designated second distance d2 indicates the distance between the electrode structural element 12 and the vibration structural element 13. Further, by setting the size of the protrusion, the specified second distance can be set to 5 micrometers or a value not exceeding it, for example, 1 micrometer or less, and a narrow gap interval can be easily realized. become.

  The constituent materials of the electrode structural element 12 and the vibration structural element 13 described above are not limited to metals, but may be a semiconductor such as silicon, or a material that imparts conductivity to the surface of an insulator such as a resin. The slider 20 is moved by a mechanism that slides the slider 20 with a force generated by electrostatic force, electromagnetic force, ultrasonic vibration, or a combination thereof. In general, the movement (slide) is such that the electrode structural element 12 moves linearly to the position of the designated second distance while maintaining the posture facing the vibration structural element 13. Not limited to this. For example, the trajectory of the electrode structural element 12 during movement may be a straight line, a circular arc, a zigzag, or the like. Further, the “designated direction” (right direction in FIG. 1) means that the electrode structure element 12 is located at a “second distance” from a state where the electrode structure element is located at a “first distance”. It only shows the direction between the final state in which the electrode structure element 12 has moved to the state.

  As described above, in this embodiment, the electrode structure element 12 and the vibration structure element 13 are processed in a “separated” state (the designated first distance), and after the processing is completed, the electrode structure It is characterized in that the element 12 is moved and placed in the “close” state (the designated second distance). If the electrode structural element 12 and the vibration structural element 13 are inevitably processed in a “close proximity” state, restrictions on the manufacturing technology increase. For example, if a gap of 1 micrometer or less is directly formed, the processing time becomes longer and the shape maintenance tends to be difficult as compared with the case of forming a wide gap. According to the present embodiment, it is possible to greatly reduce the restrictions on the manufacturing technology.

<Configuration of MEMS device>
FIG. 2 is a diagram for explaining a second embodiment to which the present invention is applied. In the figure, an application example to a MEMS device using silicon is illustrated. FIGS. 4A and 4C show the planar structure of the MEMS device. In addition, in the same figure (a) and (c), the cross-sectional structure diagrams of the portions indicated by the line segments 30 and 31 are shown in the same figure (b) and (d), respectively. FIGS. 9A and 9B show the state in which the electrode structural element 32 and the vibration structural element 33 are “separated” (the “designated first distance” indicated by d1 in the figure). (C) and (d) show a state in which the electrode structural element 32 and the vibration structural element 33 are “close” (the “designated second distance” indicated by d2 in the drawing). Further, the electrode structural element 32 and the vibration structural element 33 are in a state of being “separated” and completed (the details of the processing process using the SOI wafer will be described later).
(1) The electrode structure element 32 is “connected” to the slider 35, but in this embodiment, the electrode structure element 32 is disposed at the end of the slider 35 as the same component as the slider 35. That is, both are composed of the same silicon substrate (device layer in the case of SOI wafer).
(2) The central area of the slider 35 (indicated by “lower right hatching” in the figure) and the electrode structural element 32 float in the air as shown in the cross sections of FIGS. ing. The central region of the slider 35 is supported by “polygonal” beams 36 arranged at four ends thereof, and the four beams are fixed by four base portions 37. That is, the slider 35 is composed of a floating area (indicated by “downwardly hatched”) and a fixed base portion 37 (indicated by “dark gray”).
(3) A part of the slider 35 constitutes a “comb electrode”. This comb-shaped electrode is arranged to face the other comb-shaped electrode 38 (all of which are “fixed”). When a DC voltage is applied between these comb-shaped electrodes, the floating region of the slider 35 moves in the direction indicated by the arrow 39 in FIG. That is, in this embodiment, the slide mechanism of the slider 35 is configured by an electrostatic drive actuator using comb-shaped electrodes. In such a slide mechanism, the amount of movement of the slider 35 is determined by the magnitude of the applied DC voltage. For this reason, the magnitude of the DC voltage is controlled so that the distance between the electrode structural element 32 and the vibration structural element 33 matches the “designated second distance”.
(4) The above-described four beams 36 have a function of floating the slider 35 in the air and maintaining the floating as the slider 35 moves. Although “4” is illustrated in the drawing, the number of beams 36 is not limited to four in order to have the function. In addition, although “six bent corners” are illustrated as “polygonal lines”, the number of corners or the shape of the beam 36 is not limited to the example shown in FIG. The beam shape and the number of corners may be selected so as not to hinder the movement of the slider 36.
(5) In the present embodiment, the vibration structural element 33 is fixed to the base portion 41 via the insulating layer 40.
(6) The base parts 37 and 41 are arranged on a basic base (not shown) such as a package.

  In the second embodiment shown in FIG. 2, it is shown that the electrode structural element 32 and the vibration structural element 33 processed in the “distant” state are arranged “close to each other” by the slide mechanism of the slider 35. It was.

<Operation of electrostatic actuator>
FIG. 3 is a diagram for explaining the operation of the electrostatic actuator described in the second embodiment. In the figure, the same reference numerals as those in FIG. 2 denote the same components. For convenience of explanation, the figure is drawn upside down from FIG. Further, only a part of the slider 35 (one comb-shaped electrode group) and one fixed comb-shaped electrode group 38 are shown. Further, a portion where the beam 36 is fixed to the base portion 37, a part of the comb electrode 38 which is floating, and a part of the comb electrode 38 which is "fixed" are indicated by circles in the figure. It is enlarged and displayed. In the enlarged view, AA ′ and BB ′ are displayed, and their structural sectional views are shown in FIG. In the cross-sectional view taken along the line AA ′ in FIG. 5B, the beam 36 and the base 37 are made of the same silicon material (more specifically, the device layer of the SOI wafer), and BB. In the partial sectional view, 35 is surfaced and it is shown that it can move from the front to the back or from the back to the front. In FIG. 6C, a DC voltage 45 is applied between the above-described “fixed” comb-shaped electrode 38 and the comb-shaped electrode that is a part of the floating slider 35, and It is shown that the slider 35 moves in the direction. The distance of the movement depends on the magnitude of the DC voltage 45, and the amount of movement is determined by the magnitude of the DC voltage 45.

<Configuration of MEMS device-2>
FIG. 4 is a diagram showing a third embodiment in which electromagnetic force (Lorentz force) is used for the slider sliding mechanism described above. In the figure, the same reference numerals as those in FIG. 2 denote the same components. FIGS. 4A and 4C show the planar structure of the MEMS device. In addition, the cross-sectional structural views of the portions indicated by line segments 50 and 56 in FIGS. 10A and 10C are shown in FIGS. FIGS. 9A and 9B show the state in which the electrode structural element 32 and the vibration structural element 33 are “separated” (the “designated first distance” indicated by d1 in the figure). (C) and (d) show a state in which the electrode structural element 32 and the vibration structural element 33 are “close” (the “designated second distance” indicated by d2 in the drawing). In FIG. 5A, a conductive path 51 is disposed on the surface of the slider 35 so that a direct current (I) flows in the direction indicated by the arrow 52. Although two conductive paths are illustrated in FIG. 1A, the number and shape thereof are not limited. The conductive path extends along the beam 36 and has means connected to an external power source (not shown) in the region of the base portion 37. When the DC current is zero, the distance between the electrode structural element 32 and the vibration structural element 33 is the “designated first distance (distance d1)” (state shown in FIG. 5B). Further, the magnetic field 53 is applied from the front surface side (front side in the drawing) to the back side (back side in the drawing) of the slider 35. When such a uniform magnetic field 53 (whose intensity is H) is applied, a force (F) is generated in the slider 35 so as to move in the direction of the arrow 54. According to Fleming's law, it is well known that F = H × I, and the force is proportional to the direct current I and the magnetic field strength H. As a result, as shown in FIG. 5C, the slider 35 moves, and stops in a state where F and the reaction force accompanying the deformation of the beam are balanced. In this state, the distance between the electrode structural element 32 and the vibration structural element 33 is the “designated second distance (distance d2)” (the state shown in FIG. 4D). That is, the strength of the direct current or magnetic field 53 is set so that the distance between the electrode structural element 32 and the vibration structural element 33 is the distance d2.

  In the third embodiment shown in FIG. 4, the electrode structural element 32 and the vibration structural element 33 processed in a “separated” state are placed in “close proximity” with each other by the slide mechanism of the slider 35 using electromagnetic force. Was shown to be.

<Configuration of MEMS device-3>
FIG. 5 is a diagram showing a fourth embodiment in which ultrasonic vibration is used for the slide mechanism of the slider 35 described above. In the figure, the same reference numerals as those in FIG. 2 denote the same components. FIGS. 4A and 4C show the planar structure of the MEMS device. Moreover, in the same figure (a) and (c), the cross-section figure of the part shown with the dashed-dotted line of the line segments 60 and 62 is shown to the figure (b) and (d), respectively. FIGS. 9A and 9B show the state in which the electrode structural element 32 and the vibration structural element 33 are “separated” (the “designated first distance” indicated by d1 in the figure). (C) and (d) show a state in which the electrode structural element 32 and the vibration structural element 33 are “close” (the “designated second distance” indicated by d2 in the drawing). In FIG. 6A, an ultrasonic vibration mechanism 61 is disposed below the slider 35 and vibrates by a driving means (not shown). Such vibration induces the movement of the slider 35 in the direction indicated by the arrow 64 in FIG. As a result, as shown in FIG. 6C, the electrode structural element 32 approaches the vibration structural element 33, and the position of the “designated second distance (distance d2)” (state shown in FIG. ) However, the movement by the ultrasonic vibration is characterized in that the vibration means (for example, the ultrasonic vibration mechanism 61) and the object to be moved (for example, the slider 35) are arranged close to each other but are not in contact with each other. For this reason, if the reaction force generated by the deformation of the beam 36 (which causes a force to return the slider 35 to its original position) is large, the slider is “designated” at the moment when the ultrasonic vibration is stopped. It returns to the position of “first distance (distance d1)” (the state shown in FIG. 5B). In order to prevent this return, it is necessary to continuously apply ultrasonic vibration. Alternatively, it is necessary to provide the slider 35 with a “lock mechanism” (not shown) that prevents the slider 35 from returning.

<Configuration of MEMS device-4>
The fifth embodiment shown in FIG. 6 is another embodiment in which an electrostatic actuator is used for the slide mechanism of the slider 35 described above. In the figure, the same reference numerals as those in FIG. 2 denote the same components. FIGS. 4A and 4C show the planar structure of the MEMS device. In addition, in the same figure (a) and (c), the cross-sectional structure diagrams of the portions indicated by the line segments 30 and 31 are shown in the same figure (b) and (d), respectively. In this embodiment, a pair of left and right comb electrodes 70 and 71 are arranged opposite to the comb electrodes attached to the slider 35. Further, the electrode structural element 32 and the vibration structural element 33 are disposed to face each other, but the facing surfaces are not “parallel” but are disposed via a gap 72 having a distance of approximately a distance d1. Such a non-parallel state occurs in the manufacturing process of the MEMS device, or occurs when the MEMS device is placed in a rotating environment. In particular, in the latter case, even if non-parallelism does not occur in the manufacturing process of the MEMS device, depending on an environment in which the MEMS device is installed (for example, an environment in which the MEMS device is installed in the vicinity of an automobile tire) Rotational force is generated in the slider due to inertial force. In this embodiment, even when such a non-parallel state is obtained, the non-parallel state is corrected by electrostatic actuators (including comb electrodes 70 and 71) that are arranged on the left and right sides and are individually driven. That is, a slight rotation can be imparted to the movement of the slider 35 by individually controlling the DC voltage applied to the pair of left and right electrostatic actuators. As a result, as shown in FIG. 5C, the electrode structural element 32 and the vibration structural element 33 can be arranged “parallel” via the gap 73 having a distance d2. Also in this embodiment, the electrode structural element 32 and the vibration structural element 33 are manufactured in a “separated” state (“designated first distance” denoted by d1 in the figure), and electrostatically By driving the actuator, the electrode structural element 32 and the vibration structural element 33 are set in a “close proximity” state (a “designated second distance” represented by d2 in the drawing).

<Configuration of MEMS resonator-1>
FIG. 7 shows a sixth embodiment applied to the MEMS resonator 80. In this embodiment, the case where the slider 35 is moved by an electrostatic actuator is shown, but it may be moved by various driving means as described above. In the figure, the same reference numerals as those in FIG. 2 denote the same components. FIGS. 4A and 4C show the planar structure of the MEMS resonator 80. FIG. Moreover, the cross-section figure of the part shown with the line segments 84 and 85 of the figure (a) and (c) is shown to the figure (b) and (d), respectively. In FIG. 6A, the MEMS resonator 80 fixes the electrode structural element 32 “connected” to the slider 35, a vibrating body (in this embodiment, “vibrating beam 81”), and both ends of 81. It is comprised by the base parts 82 and 83. FIG. That is, in this embodiment, the vibration structural element includes (1) a vibration beam 81 that is a designated region of the vibration structural element, and (2) a vibration structural element that does not include the region of the vibration beam 81. It is comprised by the base parts 82 and 83 (it does not vibrate) which are area | regions. The electrode structural element 32 acts as a drive electrode for vibrating the vibration beam 81. As shown in FIGS. 9A and 9B, the electrode structural element 32 and the vibration beam 81 are in a “separated” state (“designated first distance” denoted by d1 in the figure). Has been created. In addition, the electrode structural element 32 and the vibration beam 81 are brought into the “close” state (“designation indicated by d2” in the figure) by driving means such as an electrostatic actuator, as shown in FIGS. Second distance ”). FIG. 2C also shows a high-frequency signal 88 in which a DC voltage applied to the electrostatic actuator and a DC bias 87 supplied between the electrode structural element 32 and the vibration beam 81 are superimposed. . The DC bias 87 is set according to the amplitude value of the high-frequency signal 88 so that the instantaneous value of the signal applied to the electrode structural element 32 is always positive. This is because, in the MEMS resonator 80 using electrostatic force, the induced force is the same regardless of whether the voltage of the applied signal is a positive potential or a negative potential. This is to prevent vibrations from occurring at a frequency twice that of 88.

In the vibrating beam type MEMS resonator 80 illustrated in FIG. 7, mechanical vibration is detected as an electric signal (here, a change in capacitance). The mechanical system and the electrical system are associated with each other by “electromechanical coupling coefficient”, which is also “mechanical vibration and electric signal conversion efficiency”. In this paragraph, the “electromechanical coupling coefficient” will be described with reference to FIG. Although the equation related to FIG. 8 is shown, in order to increase the “electromechanical coupling coefficient”, the facing area (S) is increased, the distance (d ₀ ) between the facing surfaces is decreased, and the applied voltage (V ₀ , It is necessary to increase (corresponding to the DC bias 87). In particular, since the “electromechanical coupling coefficient” is inversely proportional to the square of d ₀ , it is effective to reduce the distance between the vibration beam 81 and the drive electrode (electrode structure element 32). It is also effective to increase the area where the vibration beam 81 and the drive electrode face each other. Note that, when the frequency of the MEMS resonator 80 is increased, the vibration beam 81 is inevitably reduced (resonance frequency is increased), and the facing area (S) is also reduced. As a result, the electric signal obtained is also small, so it is an essential task to reduce the distance (d ₀ ) between the opposing surfaces.

  FIG. 9 is a diagram illustrating the electromechanical operation of the MEMS resonator 80 according to the sixth embodiment. In the figure, the same reference numerals as those in FIG. 7 denote the same components. FIG. 7 (a) is the same as FIG. 7 (c), and structural cross-sectional views along the alternate long and short dash line indicated by AA ′ and BB ′ in the drawing are shown in FIGS. It is shown. In FIG. 6A, DC voltages 90 and 91 drive the electrostatic actuator, and an arrow 92 is a direction in which the slider 35 moves by the DC voltages 90 and 91. Due to the DC voltages 90 and 91, the electrode structural element 32 (which is a drive electrode disposed opposite to the vibration beam 81) and the vibration beam 81 are set in a “close proximity” state. As shown in FIG. 5C, the vibration beam 81 is supplied with a high-frequency signal 88 on which a DC bias 87 is superimposed. The high-frequency signal 88 causes the vibration beam 81 to move in the vertical direction in FIG. It is vibrating. The electric equivalent circuit viewed from the high-frequency signal 88 in the direction indicated by the arrow 93 is shown in FIG. The vibration of the vibration beam 81 electrically corresponds to a resonance circuit system including four circuit elements C0, R1, C1, and L1.

  In FIG. 9, two mechanically moving mechanisms are shown. One is the movement of the slider 35, and the other is the vibration of the vibration beam 81. That is, the MEMS resonator 80 includes two different mechanical vibration mechanisms. For this reason, it is important to set the frequency characteristics of the two mechanical mechanisms. For example, when the slider 35 moves in response to the high-frequency signal 88, the energy to be supplied to the original vibration beam 81 is consumed for the movement of the slider 35, and the vibration beam 81 cannot vibrate efficiently. In order to prevent such a problem, it is necessary to make the resonance frequency of the slider 35 sufficiently lower than the frequency at which the vibration beam 81 vibrates. For example, if the resonance frequency of the slider 35 is set to about 100 Hz, the movement of the vibration beam 81 that vibrates at a high frequency is not hindered. Even with such a setting, high-order resonance is observed in the mechanical vibration system, but since the amplitude of the high-order resonance is small, the original movement of the vibration beam is not hindered. In order to lower the resonance frequency of the slider 35, there are means such as increasing the weight of the slider 35 and softening (for example, thinning) the beam 36 that supports the slider. The rigidity of the beam 36 is also related to the efficiency of the electrostatic actuator (the amount of movement of the slider 35 with respect to the DC voltage 90), and is set according to the required specifications (frequency band, etc.) for the MEMS resonator. It is necessary to

<Manufacturing process of MEMS resonator>
FIG. 10 is a diagram for explaining a manufacturing process of the MEMS resonator 80 shown in the sixth embodiment. In the figure, the “base” portion of the beam 36 that supports the slider 35, the comb electrode floating on the electrostatic actuator, and a part of the fixed comb electrode (both shown in circles in the figure). On the other hand, structural sectional views in each manufacturing process are shown. That is, (a-1) to (e-1) correspond to the “base” portion, and (a-2) to (e-2) correspond to the comb electrode portion. In FIGS. 3A-1 and 2A-2, a substrate layer 100, a device layer 101, and an oxide film layer 102 are elements constituting the SIO substrate. Although depending on the diameter of the wafer, as an example of a normal thickness, the substrate layer 100 is 250 micrometers, the device layer 101 is 20 micrometers, and the oxide film layer 102 is 1 micrometer. The first mask layer 103 is patterned on the surface of the device layer 101. The first mask layer 103 is not necessarily a single-layer photoresist made of an organic material applied uniformly. For example, (1) a chrome layer is uniformly formed on the surface of the device layer, (2) a photoresist is applied to the surface of the chrome layer and patterned by a known technique, and (3) the patterned photoresist layer As a mask, the chrome layer may be patterned, and (4) a multi-stage process may be employed in which the photoresist layer is removed and the chrome pattern is exposed. FIGS. 2B-1 and 2B-2 illustrate a structure in which a part of the device layer 101 is removed by etching using the first mask layer 103 as a mask. The region 104 is a region where the device layer 101 is removed by etching and the oxide film layer 102 is exposed. For the etching of the device layer 101, many liquids or gases are used, and a representative example is reactive ion etching (RIE). Next, as shown in FIGS. 2C-1 and 2C-2, a second mask layer 105 is formed on the back surface of the substrate layer 100. FIG. The second mask layer 105 is also formed in the same manner as the first mask layer 103 described above. The region of the substrate layer 100 that is not covered with the second mask layer 105 is etched away by the method described above. FIGS. 4D-1 and 2D-2 illustrate a region 106 where the lower surface of the oxide film layer 102 is exposed by the etching removal. Next, when the exposed oxide film layer 102 is removed by etching, a structure as shown in (e-1) and (e-2) is obtained. Etching of the oxide film layer 102 uses hydrofluoric acid type wet etching or dry etching. In the figure, a region 107 is a beam region that supports the slider, a region 108 is a region of the comb electrode 38 that is fixed, and a region 109 is a region of the comb electrode that is floating.

  Although not explicitly shown in FIG. 10, the vibrating body (vibrating beam 81) and the base portions 82 and 83 that fix both ends of the vibrating beam 81 are produced by a similar manufacturing process. That is, the vibration beam 81 is created in the same manner as the region 109 in FIG. 10 (e-2), and the base parts 82 and 83 are created in the same manner as the region 108 in FIG. 10 (e-2). The MEMS resonator 80 is created by the above process. 10 illustrates the manufacturing process, the manufacturing process of the MEMS resonator 80 is not limited to this. For example, the device layer 101 can be processed first and the substrate layer 100 can be processed later.

  In the process illustrated in FIG. 10, the first mask layer 103 and the second mask layer 105 are formed on the front surface and the back surface of the SOI wafer by separate processes, respectively. The patterning of the second mask layer 105 requires spatial alignment with the pattern of the first mask layer 103, and generally a double-sided exposure machine using infrared rays is used. In the double-side exposure machine, the pattern on the front side (the pattern of the first mask layer 103) can be observed by infrared rays that pass through the silicon layer, and the pattern on the back side (formed on the glass mask) is matched to the pattern. The position of the second mask layer 105 pattern) can be determined. The accuracy of such positioning depends on the performance of the double-sided exposure machine used, but generally an accuracy of about 1 micrometer can be obtained. However, in the process shown in FIG. 10, the shape of each element (the electrode structure element 32, the vibration beam 81, the comb electrode, etc.) constituting the MEMS resonator 80 is determined by the first mask layer 103 described above. It is clear. For this reason, the shape of each element can be created without being limited by the accuracy of the above-described double-side exposure machine.

<Stopper configuration-1>
FIG. 11 shows an eighth embodiment of the present invention applied to a MEMS resonator. The electrode structural element 32 (for example, the drive electrode) and the vibration structural element (for example, the vibration beam 81) created via the “designated first distance” (in the “separated” state) are replaced with an electrostatic actuator or the like One mechanism for moving to a “designated second distance” (in the “close” state) by the mechanism and stopping at the second distance is to use a stopper. In the first embodiment, it is described as the protrusion 22. FIG. 7A shows the main elements of the MEMS resonator 80 shown in FIG. 7, and the same reference numerals as those in FIG. 7 denote the same components. FIGS. 7B and 7C are cross-sectional structural views taken along the line indicated by the line segment 111 in FIG. Also, FIGS. 9A and 9B show a “separated” state, and FIG. 9C shows a “close” state. In FIG. 2A, a protrusion 110 is a protrusion serving as a stopper disposed on the electrode structural element (drive electrode) 32. As shown in FIG. 5B, the size of the protrusion 110 is set equal to the “designated second distance” (distance d2). For this reason, when the electrode structural element 32 is moved in the upward direction (a) by an electrostatic actuator (not shown), the distance between the electrode structural element 32 and the vibration beam 81 is “specified” before the movement. This is the “first distance” (distance d1), and after the movement, becomes the “designated second distance” (distance d2). The protrusion 110 comes into contact with a part of the vibration beam 81, but since the contact is “point contact”, the vibration of the vibration beam is not affected. In addition, although the shape of the protrusion 110 is displayed as a semi-cylindrical shape in which the radius is the distance d2 and the height is the thickness of the electrode structural element 32 (the thickness of the device layer), the shape is not limited thereto. For example, the height of the protrusion 110 may be smaller than the thickness of the electrode structure element 32, and the protrusion 110 may be disposed at a part in the thickness direction of the electrode structure element 32. Further, as shown in the sixth embodiment, since a high frequency signal 88 on which a DC bias 87 is superimposed is applied between the electrode structural element (drive electrode) 32 and the vibration beam 81, FIG. Even in the state shown in FIG. 2, it is necessary that the electrode structural element 32 and the vibration beam 81 are electrically insulated. As a method for ensuring such electrical insulation, the protrusion 110 may be made of an insulating material, or the surface of the protrusion 110 may be covered with an insulating layer. Furthermore, the number of the protrusions 110 is not limited to two, but may be one or more.

  In the configuration illustrated in FIG. 11, the length of the vibration beam 81 may change apparently. For example, when the force pressing the projection 110 against the vibration beam 81 is strong, the length of the vibration beam 81 is shortened and the resonance frequency is increased. In such a case, the entire length of the oscillating beam 81 (supports the oscillating beam) so that the effective length of the oscillating beam 81 (distance between the line segments 111, indicated by L in the figure) becomes a desired length. By setting a large distance between the base portions 82 and 83, it is possible to avoid the influence of the contact of the protrusion 110.

<Stopper configuration-2>
FIG. 12 shows a ninth embodiment applied to the MEMS resonator 80 shown in FIG. 7 and shows the structure of the protrusion 120 as a stopper. In the figure, the same reference numerals as those in FIG. 11 denote the same components. FIGS. 2B and 2C are cross-sectional structural views taken along the line segment 121 in FIG. Also, FIGS. 9A and 9B show a “separated” state, and FIG. 9C shows a “close” state. In FIG. 4A, a protrusion 120 is a protrusion as a stopper disposed on the vibration beam 81 (which is also a vibration structural element). As shown in FIG. 5B, the size of the protrusion 120 is set equal to the “designated second distance” (distance d2). Therefore, when the electrode structural element 32 is moved upward in the drawing by an electrostatic actuator or the like (not shown), the distance between the vibration beam 81 and the electrode structural element 32 is the “designated first distance” before the movement. (Distance d1), and after the movement, the “designated second distance” (distance d2). The protrusion 120 comes into contact with a part of the electrode structural element 32 (which is also a drive electrode), but since the contact is “point contact”, the vibration of the vibration beam 81 is not affected. The shape of the protrusion 120 is displayed as a semi-cylindrical shape in which the radius is the distance d2 and the height is the thickness of the vibration beam 81 (the thickness of the device layer), but is not limited thereto. For example, the height of the protrusion 120 may be smaller than the thickness of the vibration beam 81 and may be disposed at a part in the thickness direction of the vibration beam 81. Further, as shown in the sixth embodiment (FIG. 7), a high frequency signal 88 on which a DC bias 87 is superimposed is applied between the vibration beam 81 and the electrode structure element 32 (drive electrode). Even in the state shown in FIG. 3C, it is necessary that the vibration beam 81 and the electrode structural element 32 are electrically insulated. As a method for ensuring such electrical insulation, the protrusion 120 may be made of an insulating material, or the surface of the protrusion 120 may be covered with an insulating layer.

<Stopper configuration-3>
FIG. 13 shows a tenth embodiment of the present invention applied to a MEMS resonator, and shows a configuration of a protrusion 135 as a stopper and a method for producing the same. In this embodiment, it is described corresponding to the case where the projection 135 is arranged on the slider 35 side (Embodiment 8), but the arrangement position of the projection 135 is not limited to this. In FIG. 2A, a protrusion base 130 is a protrusion base made of silicon or the like and disposed at the end of the electrode structure element 32 connected to the slider 35, and has a sharp tip 131, and is shown as a plan view. ing. The thickness of the projection base 130 is equal to the thickness of the electrode structural element 32, but is not necessarily limited thereto. FIG. 4B is a diagram in which the surface of the structure shown in FIG. By the oxidation process, the upper surface and the side wall surface of the protrusion matrix are changed to a silicon oxide layer 132 having an equal thickness. However, since the tip 131 has a small width, the change to the silicon oxide layer 132 is quick, and as a result, the protrusion matrix remaining without being oxidized becomes round (indicated by the tip 133) in the vicinity of the tip. . FIG. 4C shows the shape of the protrusion matrix after the silicon oxide layer of the structure shown in FIG. In such a shape, a silicon layer (device layer) is exposed on the surface of the protrusion base 130. In the case where electrical insulation is imparted to the surface of the protrusion base 130, the silicon oxide layer 134 can be formed by an oxidation process so that the shape shown in FIG. FIG. 4D shows the created projection 135 whose size is indicated as d2.

  In addition, the size of the protrusion 135 as a stopper includes (1) the size and shape of the protrusion base 130, (2) conditions of the oxidation process (treatment temperature, atmosphere, time), and (3) silicon oxide formed by the oxidation process. By appropriately setting the number of repetitions of etching removal of the layer 132, the size of the protrusion 135 is finally made equal to the “designated second distance” (distance d2). That is, the “distance to silicon oxide” and “etching removal of silicon oxide” shown in FIGS. 2B and 2C may be repeated a plurality of times to obtain a desired distance d2.

<Stopper configuration-4>
14 shows an eleventh embodiment of the present invention applied to the MEMS resonator 80 shown in FIG. 7, and shows another configuration of the protrusion 140 as a stopper. In the figure, the same reference numerals as those in FIG. 12 denote the same components. For convenience of explanation, the electrode structural element 32 and the vibration beam 81 are shown in a “separated” state in FIG. In the figure, a protrusion 140 is a protrusion provided on the electrode structural element (drive electrode) 32. FIG. 6A shows the case where the vibration beam 81 vibrates in the first-order resonance mode, and the protrusion is arranged so as to contact the “node” region of the vibration. On the other hand, FIG. 5B shows a case where the vibration beam 81 vibrates in the third-order resonance mode, and the protrusion is arranged so as to contact the “node” region of the vibration. In any case, the amplitude of vibration is small in the “node” region (theoretically it is zero, and it looks as if the “node” is fixed). It does not affect the operation of the beam. In the MEMS resonator, the order of the resonance mode to be used is set as a system requirement. Therefore, the protrusion can be brought into contact with a region of “node” corresponding to the order. That is, the number of the protrusions 140 is not limited to two.

<Stopper configuration-5>
FIG. 15 is a twelfth embodiment of the present invention applied to the MEMS resonator 80 shown in FIG. 7, and shows another configuration of the protrusion 151 as a stopper. In the figure, the same reference numerals as those in FIG. 7 denote the same components. FIG. 6A corresponds to a state where the electrode structural element 32 and the vibration beam 81 are “separated”. In the figure, a slider 150 is a slider connected to the electrode structural element 32, and a protrusion 151 is provided at an end portion. The stopper receiver 152 contacts the projection 151 to stop the movement of the slider 150 and has the same structure as the base parts 82 and 83. Structural cross-sectional views along the alternate long and short dash line shown by the line segments 153 and 154 in FIG. 10A are shown in FIG. 10B and FIG. 10D, respectively. . FIGS. 4B and 4D show the case where the distance between the electrode structural element 32 and the vibration beam 81 is the “designated first distance”, and FIGS. 3C and 3E show the electrode structural element. This is a case where the distance between the vibration beam 81 and the vibration beam 81 is the “designated second distance”. The slider 150 is moved by a mechanism such as an electrostatic actuator (not shown), but the movement stops when the protrusion 151 comes into contact with the “stopper receiver” 152. Here, by setting the size of the protrusion 151 to the “designated second distance” (distance d2), the distance between the electrode structural element 32 and the vibration beam 81 is the distance d2. Are equal (shown in FIGS. 15B to 15E).

  In the present embodiment, since the projection 151 does not contact the vibration beam 81, there is a feature that there is no possibility of inhibiting the vibration of the vibration beam 81. Strictly speaking, the distance between the electrode structural element 32 and the vibration beam 81 in the “close” state does not coincide with the size d2 of the protrusion 151. The difference between the distance and the distance d2 depends on the pattern accuracy of the semiconductor process used to create the MEMS resonator. However, in recent semiconductor processes, the patterning accuracy is improved, and an accuracy of 0.1 micrometer or less is ensured. Therefore, such inconsistency is not a big problem. If the matching accuracy is further improved, the accuracy can be further improved by pattern design considering the patterning accuracy in the semiconductor process, the manufacturing method of the protrusion 151 (for example, Example 10), or the like.

  Further, the arrangement region of the protrusions 110, 120, 135, 140, 151 is not limited to the region of the constituent elements such as the electrode structural element 32, the vibration beam 81, or the slider 35, and these constituent elements. They may be arranged in a plurality of regions that are combined. Furthermore, the shape of the projections 110, 120, 135, 140, 151 is not necessarily a semi-cylindrical shape.

<Configuration of MEMS resonator-2>
FIG. 16 shows a thirteenth embodiment of the present invention applied to a MEMS resonator. The same reference numerals as those in FIG. 7 denote the same components. FIG. 2A is a plan structural view of a MEMS resonator. FIGS. 7B and 7C are sectional structural views of a portion indicated by a line segment 245, and FIGS. 8D and 9E are sectional structural views of a portion indicated by a line segment 246, respectively. . FIGS. 7B and 7D show the case where the distance between the electrode structural element 32 and the vibration beam 81 is the distance d1, and FIGS. 5C and 5E show the electrode structural element 32 and the vibration beam 81. The case where the distance between the two is the distance d2 is shown. In FIG. 5A, the slider 240 connected to the electrode structural element 32 is connected to the base portion 242 via a beam 241. The slider 240 (including the electrode structure element 32) and the beam 241 are levitated and have a structure that can move in the vertical direction (vertical direction on the paper surface) in FIG. The shape of the beam 241 that supports the slider 240 is exemplified by three lines, but the shape is not limited to this. The electrode 243 is a fixed electrode and is disposed facing the slider 240 at a distance d3. A DC voltage 247 is applied to the electrode 243 and the slider 240. Note that the DC voltage 247 is applied only to the electrode 243 on one side, but it is preferable that the DC voltage 247 is applied to the two electrodes 243 disposed on both sides of the slider 240 at the same time. When the DC voltage 247 is 0 volt, the distance between the slider 240 and the electrode 243 is the distance d3 ((d) in the figure), and the distance between the vibration beam 81 and the electrode structural element 32 is the distance d1. ((B) in the figure). On the other hand, when the DC voltage 247 generates a voltage of several volts or more, the slider 240 is attracted to the electrode 243 side, and the slider 240 and the electrode 243 are “contacted” ((e) in the same figure), and the vibrating beam 81 And the electrode structural element 32 is (distance d1−distance d3). As shown in FIG. 5C, the difference between the distances d1 and d3 is the “designated second distance” (that is, the distance d2). In other words, the size of the distance d3 is designed to be equal to the difference between the “designated first distance” and the “designated second distance”. Note that a boundary region 250 in FIG. 4E indicates a boundary region between the slider 240 and the electrode 243 in the “contact” state. An insulator is present in such a region so that a large current due to contact between the slider 240 and the electrode 243 does not flow to the DC voltage 247. Such a situation is easily realized by covering both the opposing sides of the slider 240 or the electrode 243 with an oxide film or the like. Unlike the embodiment shown in FIG. 7, the embodiment described in this paragraph does not require a comb-shaped electrode (for example, the comb-shaped electrode 38). The DC voltage 247 generates an electrostatic field on the slider 240 and the electrode 243, and the electrostatic field attracts the slider 240 toward the vibration beam 81, thereby realizing the “designated second distance”. Since the attractive force due to the electrostatic field depends on the distance d3, the value of the DC voltage 247 can be reduced by designing the distance d3 as small as possible. Further, in FIG. 6A, a high frequency signal 248 on which a DC bias 249 is superimposed is applied between the vibration beam 81 and the electrode structural element 32. That is, the high frequency signal 248 vibrates the vibration beam 81, and the MEMS resonator is realized.

  In the embodiment of FIG. 16A, the above-described “stopper” function is realized by the “contact”. The construction method of such a “stopper” is similar to the twelfth embodiment shown in FIG. However, the difference is that the electrode 243 for moving the slider 240 also serves as the stopper receiver (stopper receiver 152 in FIG. 15). Further, the slider 240 may be provided with a protrusion (corresponding to the protrusion 151 in FIG. 15) on the side surface facing the electrode 243. Further, the protrusion may be provided on the side surface of the slider 240 facing the electrode 243.

<Configuration of MEMS resonator-3>
FIG. 17 shows a fourteenth embodiment of the present invention applied to a MEMS resonator. The same reference numerals as those in FIG. 16 denote the same components. FIG. 2A is a plan structural view of a MEMS resonator. FIGS. 7B and 7C are sectional structural views of a portion indicated by a line segment 245, and FIGS. 8D and 9E are sectional structural views of a portion indicated by a line segment 246, respectively. . FIGS. 7B and 7D show the case where the distance between the electrode structural element 32 and the vibration beam 81 is the distance d1, and FIGS. 5C and 5E show the electrode structural element 32 and the vibration beam 81. The case where the distance between the two is the distance d2 is shown. This embodiment is characterized in that the DC voltage 256 serves as both the DC voltage 247 and the DC bias 249 shown in FIG. That is, the DC voltage 256 is a DC bias that is superimposed on the high-frequency signal 255 that drives the vibration beam 81 at the same time that an attractive force is induced between the slider 240 and the electrode 243. According to such a configuration, there is an advantage that the driving of the MEMS resonator is simplified.

<Configuration of MEMS resonator-4>
FIG. 18 shows a fifteenth embodiment of the present invention applied to a MEMS resonator, in which the main part of the MEMS resonator is shown. Also, the same numbers as those in FIG. 16 indicate the same components. FIG. 2A is a plan structural view of a MEMS resonator. The slider 260 connected to the electrode structural element 32 is connected to the base portion 242 via the beam 241. The slider 260 (including the electrode structural element 32) and the beam 241 are levitated, and are configured to be movable in the vertical direction (vertical direction on the paper surface) in FIG. The shape of the beam 241 that supports the slider 260 is exemplified by three lines, but the shape is not limited to this. The electrode 243 is a fixed electrode and is disposed to face the slider 260. The figure which expanded this area | region 261 is the same figure (b). The slider 260 included in the region is provided with a concave portion 263, and the opposing electrode 243 is provided with a convex portion 262. The shapes of the concave portion 263 and the convex portion 262 are complementary, and when both come into close contact with each other, they are in “close contact” (as shown in FIG. 5C). Although not explicitly shown in FIG. 6A, the slider 260 moves toward the electrode 243 and the vibration beam 81 by an attractive force induced by a DC voltage supplied from the outside (corresponding to the DC voltage 247 in FIG. 16). To do. The movement continues until the concave portion 263 contacts the convex portion 262, and the movement stops when the contact occurs. In this embodiment, the left and right ends of the slider 260 are provided with recesses, and the projections are disposed on one set of electrodes 243. Therefore, even if the movement is shifted left and right (on the drawing), the final slider 260 The position has the advantage of being geometrically constant. That is, there is an advantage that the mutual positional relationship between the electrode structural element 32 and the vibration beam 81 is uniquely determined.

FIG. 18B shows the positional relationship between the convex portion 263 and the concave portion 262 before the slider 260 moves. FIG. 5C shows the positional relationship between the convex portion 263 and the concave portion 262 after the slider 260 has moved. In FIG. 5B, the angle formed by the concave portion 262 is 2θ, the distance between the concave portion 262 and the convex portion 263 (the length along the moving direction) is the distance d3, and the concave portion 263 and the convex portion 262 are If the distance between (the shortest distance) is the distance d4,
d4 = d3 × sin θ
The relationship is established. That is, since the distance that the slider 260 moves toward the vibration beam 81 is the distance d3, the aforementioned “designated second distance (distance d2)” is
d2 = d1-d4 / sin θ
Determined by That is, the design factor is to set the distance d1, the distance d4, and θ so as to satisfy the above relationship. In the above equation, the distance d4 is adopted as an alternative to the distance d3. In this case, the “gap between patterns” becomes more important when designing an exposure mask for manufacturing and during the manufacturing process. Because it becomes.

<Area where electrode structural element and vibration beam face each other>
FIG. 19 shows a sixteenth embodiment of the present invention applied to the MEMS resonator 160. In order to increase the electromechanical coupling coefficient, the area of the region where the electrode structural element 162 (drive electrode) and the vibration beam 163 face each other is shown. It is characterized by being large. In the figure, the same reference numerals as those in FIG. 7 denote the same components. In this embodiment, the case where the slider 161 is moved by the electrostatic actuator is shown, but it may be moved by various driving means as described above. FIGS. 4A and 4C show a planar structure of the MEMS resonator 160. FIG. Moreover, the cross-section figure of the part shown by the line segments 164 and 165 of the figure (a) and (c) is shown to the figure (b) and (d), respectively. In FIG. 9A, the MEMS resonator 160 includes an electrode structural element 162 (drive electrode) “connected” to the slider 161, a vibrating body (in this embodiment, “vibrating beam 163”), and the vibration. It is comprised by the base parts 82 and 83 which fix the both ends of the beam 163. FIG. As shown in FIGS. 9A and 9B, the electrode structural element 162 and the vibration beam 163 are in a “separated” state (“designated first distance” denoted by d1 in the figure). Has been created. Further, the electrode structural element 162 and the vibration beam 163 are driven by an electrostatic actuator or the like, as shown in (c) and (d) of FIG. 2nd distance ”). FIG. 3C also shows a high-frequency signal in which a DC voltage applied to the electrostatic actuator and a DC bias supplied between the electrode structure element 162 and the vibration beam 163 are superimposed.

  In Example 16, the base region of the MEMS resonator 160 has a thickness t0 as shown in FIGS. 5B and 5D, but the thicknesses of the electrode structural element 162 and the vibration beam 163 are the same. Is t1 which is larger than the thickness of the device layer and smaller than t0. Unlike Example 6 (FIG. 7) described above, a part of the substrate layer of the SOI substrate is left as a specific region in the electrode structural element 162 and the vibration beam 163 (FIG. 7). , Respectively, indicated by substrate layer 166 and substrate layer 167). The remaining substrate layer 166 and the electrode structure element 162 which are the specific regions need to be electrically connected and insulated from the substrate layer 168 of the base portion. Similarly, the substrate layer 167 and the device layer 163 which are the specific regions need to be electrically connected and insulated from the substrate layer 168 of the base portion. Such electrical connections and insulation are described in the next paragraph.

  FIG. 20 is a diagram illustrating the configuration of the vibrating beam 163, the base portion 83, and the electrode structural element 162 (drive electrode) of Example 16 in an enlarged manner. In the figure, the same numbers as those in FIG. 19 indicate the same components. FIG. 2A is a plan view. Structural cross-sectional views of portions indicated by alternate long and short dash lines in line segments 170 and 171 in FIG. 10A are shown in FIGS. As shown in FIG. 4B, the base portion 83 is provided with a groove 172 for separating the substrate layer. By the groove 172, the substrate layer 167 in the region of the vibration beam 163 and the substrate layer 174 in the region of the base portion 83 are electrically insulated. Further, the device layer 175 constituting the vibration beam 163 and the base portion 83 and the substrate layer 167 are electrically connected by a conductive plug 176. The plug 176 has a through hole in the device layer 175 in the region of the base portion 83 (generally wider than a thin vibration beam), and embeds a metal layer or the like inside the through hole. It is formed by. Further, as shown in FIG. 5C, a conductive plug 177 is also provided for the electrode structure element 162, and the substrate layer 166 and the device layer 178 are electrically connected. Although not shown, the electrode structural element 162 is insulated from the substrate layer since the substrate layer in the beam region (for example, the beam 36 in FIG. 19) that supports the electrode structural element 162 is completely removed.

  In Example 16, although the thickness of the base region of the MEMS resonator 160 is t0 as shown in FIGS. 5B and 5C, the region of the electrode structural element 162 and the vibrating body 163 is the same. The thickness of t1 is smaller than t0. Unlike the above-described sixth embodiment (FIG. 7), a part of the substrate layer of the SOI substrate is left in the electrode structural element 162 and the vibration beam 163 as the specific region without being removed. As a result, the area where the electrode structural element 162 (including the substrate layer 166) and the vibration beam 163 (including the substrate layer 167) face each other is increased, and the electromechanical coupling coefficient can be increased.

<Manufacturing Process of Example 16>
FIG. 21 is a diagram for explaining a manufacturing process of the MEMS resonator 160 shown in the sixteenth embodiment, which is the seventeenth embodiment of the present invention. In the figure, the same reference numerals as those in FIG. 10 denote the same components. In the figure, the “base” portion of the beam 36 that supports the slider 161, the comb electrode floating on the electrostatic actuator, and a part of the fixed comb electrode 38 (both shown in circles in the figure). On the other hand, structural sectional views in each manufacturing process are shown. That is, (a-1) to (f-1) in the figure correspond to the "base" part, and (a-2) to (f-2) in the figure correspond to the part of the comb electrode. In the figure, a substrate layer 100, a device layer 101, and an oxide film layer 102 are elements constituting an SIO substrate. Although depending on the diameter of the wafer, as an example of a normal thickness, the substrate layer 100 is 250 micrometers, the device layer 101 is 20 micrometers, and the oxide film layer 102 is 1 micrometer. In the drawing, the initial thickness of the SOI substrate is indicated by t0. In FIG. 1A, after the first mask layer 181 is formed on the back surface (substrate layer 100 side) of the substrate, the substrate layer 100 in a region not covered with the first mask layer 181 is formed. All are removed ((b-1) in the figure). Next, after the second mask layer 182 is formed on the back surface (substrate layer 100 side) of the substrate, a portion of the substrate layer 100 in a region not covered with the second mask layer 182 is removed, It is processed so that the thickness of the specified region is formed. As a result, the back side of the SOI substrate has an uneven shape ((d-2) in the figure).

  In FIGS. 2B-1 and 2C-1, the mask layers 181 and 182 are illustrated as if they are different elements, but this is not restrictive. For example, (1) the first mask layer 181 is formed with a silicon oxide thin film (the substrate layer 100 side is entirely covered with the silicon oxide thin film), and (2) the silicon oxide created in FIG. The substrate layer 100 is removed by etching using the thin film pattern as the first mask layer 181 ((b-1) in the figure), and (3) a second newly created pattern is formed on the remaining silicon oxide thin film. As the mask layer 182, partial etching of the substrate layer 100 is performed ((d-2) in the figure). That is, this is a method of patterning the silicon oxide thin film in two steps.

  Subsequently, as shown in FIGS. 21E-1 and 21E-2, a third mask layer 183 is formed on the surface side of the SOI substrate (the surface of the device layer 101). The third mask layer 183 is patterned in accordance with the concavo-convex shape formed on the back surface of the SOI substrate. Using this third mask layer 183 as a mask, from the surface side of the SOI substrate, the silicon of the device layer 101, the oxide film layer 102 immediately below the device layer 101, and the silicon of the substrate layer 100 immediately below the oxide film layer 102 are RIE or the like. Etching is removed by a known method to obtain the shapes shown in FIGS. In the figure, a region 186 is a beam region that supports the slider 161, a region 187 is a region of the comb electrode 38 that is fixed (the thickness is initially t0), and a region 188 is a floating comb electrode. (The thickness is indicated by t1).

  Although not explicitly shown in FIG. 21, the vibrating body (vibrating beam 163) and the base portions 82 and 83 for fixing both ends of the vibrating beam 163 are also produced by a similar manufacturing process. That is, the vibration beam 163 is formed in the same manner as the region 188 in FIG. 8F, and the base portions 82 and 83 are formed in the same manner as the region 187 in FIG. Thereafter, as described in FIG. 20, plugs 176 and 177 for electrical connection between the device layer 101 and the substrate layer 100 are provided.

  In the MEMS resonator 160 (FIG. 19) created by such a manufacturing process, the thickness of the region of the electrode structural element 162 (drive electrode) and the region of the vibration beam 163 is larger than t1 (generally, the thickness of the device layer 101). Big). That is, the opposing area of the electrode structural element 162 (drive electrode) and the vibration beam 163 is increased, and the above-described electromechanical coupling coefficient can be increased. The thickness (t1) is determined by a process in which the substrate layer 100 is partially removed by etching using the second mask layer 182 as a mask (FIG. 21D-2). From the viewpoint of increasing the electromechanical coupling coefficient, it is desirable that t1 is as close to t0 (original SOI substrate thickness) as possible. However, the mechanical movement of the vibrating beam 163 and the floating comb-shaped electrode moves not only in the SOI substrate plane but also in the thickness direction of the SOI substrate, and the basic base (on which the base unit 37 is mounted ( (Not shown). For this reason, for example, it is desirable to set it approximately 10 micrometers smaller than t0.

  21 illustrates a manufacturing process, the manufacturing process of the MEMS resonator 160 is not limited to this. For example, the processing of the substrate layer 100 may be performed simultaneously with partial etching (FIG. (D-2)), and the remaining substrate layer 100 may be completely removed by etching. There are many other modifications, but as an example, a process considering the ease of alignment at the time of forming the mask layer and the mask resistance at the time of etching, or particularly the first mask layer 181 and the first mask. For example, the mask resistance is improved by making the two mask layers 182 into a two-layer structure.

<Configuration of MEMS resonator-2>
FIG. 22 is an eighteenth embodiment of the present invention and shows another structure of the MEMS resonator. In the figure, the same reference numerals as those in FIG. 7 denote the same components. FIG. 6A shows a state where the vibrating beam 192, the first electrode structural element 199, and the second electrode structural element 196 are “separated”, and FIG. 5B shows a state “close”. In the MEMS resonator according to the present embodiment, a drive system 190 and a detection system 191 are separately disposed, and a common vibration beam 192 is disposed therebetween. Both ends of the vibration beam 192 are fixed by base parts 193 and 194. The detection system 191 has a configuration similar to that of the drive system 190. In FIG. 9A, a first electrode structural element 199 (drive electrode) is disposed at the end of the first slider 198, and the vibration beam 192 is at a designated third distance (in the drawing). (Denoted by d3) in FIG. A second electrode structure element 196 (drive electrode) is disposed at the end of the second slider 195, and is separated from the vibration beam 192 by a designated fourth distance (denoted by d4 in the figure). Has been created. The first slider 198 is moved upward (in the first direction) in the drawing by a fixed comb-shaped electrode 38 (constituting a first slide mechanism). As a result, the distance between the first electrode structural element 199 (connected to the first slider 198) and the vibration beam 192 is the “designated third distance” indicated by d3 in FIG. Thus, the “designated fifth distance” indicated by d5 in FIG. The second slider 195 is moved downward (in the second direction) in the drawing by a fixed comb-shaped electrode 197 (constituting a second slide mechanism). As a result, the distance between the second electrode structural element 196 (connected to the second slider 195) and the vibration beam 192 is the “designated fourth distance” indicated by d4 in FIG. Thus, the “designated sixth distance” indicated by d6 in FIG. In the figure, an example in which the first slide mechanism and the second slide mechanism are both configured by electrostatic actuators is shown, but actuators based on other driving principles may be used. Absent. As described above, the first slider 198 and the second slider 195 are driven so as to be close to the vibration beam by a set of the electrostatic actuators. As shown in FIG. State.

  The “designated third distance (distance d3)” and “designated fourth distance (distance d4)” illustrated in FIG. 22 are the same as the “designated first distance” described in FIG. 2 (Example 2). Distance (distance d1) ", and the setting method (including the creation method as an element) and the size of the distance are the same. Further, the “designated fifth distance (distance d5)” and “designated sixth distance (distance d6)” illustrated in FIG. 2 are the same as the “designated fifth distance (distance d6)” described in FIG. Corresponds to the “second distance (distance d2)”, and the setting method (including the creation method as an element) and the size of the distance are the same.

  The sixth embodiment illustrated in FIG. 7 is a MEMS resonator 80 including a single vibration beam 81 and a single electrode structure element 32 (drive electrode), and the vibration beam is generated by a high-frequency signal 88 connected from the outside. While 81 vibrates, the high frequency current value which flows into the vibration beam 81 from the high frequency signal 88 was detected. That is, the drive system and the detection system are configured in common. On the other hand, in the present embodiment illustrated in FIG. 22, the drive system 190 and the detection system 191 are separated. The detection system 191 in the figure detects an amount of change in electrostatic capacitance formed between the electrode structure element 196 and the vibration beam 192 as an electrical signal. Such “amount of change in capacitance” can be detected by using an operational amplifier amplifier circuit, a switched capacitor circuit, or the like. Thus, since the drive system 190 and the detection system 191 are separated in this embodiment, the drive condition of the drive system 190 (for example, the superimposed DC bias value) and the detection condition of the detection system 191 (for example, There is an advantage that the detection principle and the circuit configuration) can be optimized separately.

<Configuration of MEMS resonator-3>
FIG. 23 is a nineteenth embodiment of the present invention and shows another structure of the MEMS resonator. In the figure, the same numbers as those in FIG. 22 indicate the same components. In FIG. 5A, two electrode structural elements 200 and 201 are connected to the second slider 195 to form a second drive system 205. In other words, the number of electrode structure elements connected to the second slider 195 is not “one”, but the electrode structure elements 200 are separated into the 2-1 electrode structure element 200 and the 2-2 electrode structure element 201. It is a feature. On the other hand, the first slider 198 is connected to a first electrode structural element 199 (not separated but “one”) to form a first drive system 204. These drive systems 204 and 205 are arranged so as to face each other with a common vibration beam 192 interposed therebetween, and are movable by a slide mechanism such as an electrostatic actuator arranged individually. FIG. 5A shows a state where the first drive system 204 and the second drive system 205 are “separated”. FIG. 4B shows the case where only the first drive system 204 moves in the direction indicated by the arrow in the drawing to “close”, and FIG. 5C shows only the second drive system 205. Is moved in the direction indicated by the arrow in the figure to become “close”, the same figure (d) shows that both the first drive system 204 and the second drive system 205 are indicated by the arrows in the figure. Each of the cases where the robot moves in the indicated direction to become “close” is shown. Further, a high-frequency signal on which a DC bias is superimposed is applied between the vibrating beam 192 and the first electrode structural element 199 and between the vibrating beam 192 and the electrode structural elements 200 and 201 as described above. ing. However, when the oscillating beam 192 and the electrode structural elements 199, 200, 201 are in a “separated” state, the oscillating beam 192 does not vibrate with the high frequency signal. This is because, in this state, the distance between the vibrating beam 192 and the electrode structural elements 199, 200, and 201 is large, so the electric field strength is small and vibration cannot be excited (the electromechanical coupling coefficient is small). It is a state). On the other hand, when the vibrating beam 192 and the electrode structural elements 199, 200, and 201 are in the “close proximity” state, the vibrating beam vibrates with the high-frequency signal. That is, the vibration beam 192 vibrates only when the first drive system 204 and the second drive system 205 are in the “close” state.

  In FIG. 23B, since only the first drive system 204 is in the “close proximity” state, the vibration beam 192 is vibrated by the first electrode structural element 199 (drive electrode). The mode in which the amplitude of the vibration is maximum is the primary resonance mode of the vibration beam 192. In FIG. 5C, only the second drive system 205 is in the “close proximity” state, and therefore the vibration beam 192 is connected to the 2-1 electrode structure element 200 (drive electrode) and the 2-2 electrode. It vibrates with the electrode structure element 201 (drive electrode). The mode in which the amplitude of the vibration is maximum is the secondary resonance mode of the vibration beam 192. Further, in FIG. 4D, since the first drive system 204 and the second drive system 205 are both in the “close proximity” state, the vibration beam 192 is the first electrode structural element 199 (drive). Electrode), the 2-1 electrode structure element 200 (drive electrode), and the 2-2 electrode structure element 201 (drive electrode). The mode in which the amplitude of the vibration is maximum is a third-order resonance mode of the vibration beam. That is, in the configuration of FIG. 23, the frequency at which the amplitude is maximum can be electrically changed depending on the positions of the drive systems 204 and 205.

Note that FIG. 23 only shows an example of positions where the electrode structural elements 199, 200, 201 (drive electrodes) are arranged, and the arrangement positions are not limited to these. This paragraph describes a modified example of the arrangement position.
(1) For example, the first electrode structure element 199 is disposed at a position 1/3 from the left end of the vibration beam 192, and the 2-1 electrode structure element 200 is disposed at a position 1/3 from the right end of the vibration beam ( In such a configuration, the electrode structural element 201 is not disposed), whereby the mode in which the vibration amplitude of the vibration beam 192 is maximized can be changed to the secondary resonance mode.
(2) For example, the first electrode structural element 199 is separated into two electrodes (for convenience, the “1-1 electrode” and the “1-2 electrode”), and the 2-1 The arrangement relationship between the electrode structural element 200 (driving electrode) and the 2-2 electrode structural element 201 (driving electrode) is sequentially arranged from the left side on both sides along the vibration beam 192.
"1-1st electrode, 2-1 electrode, 1-2 electrode, 2-2 electrode"
To be. In such a configuration, the mode in which the vibration amplitude of the vibration beam 192 is maximum can be set to the fourth-order resonance mode. As in the example described above, the frequency change range can be greatly increased by setting the number of separated electrode structural elements and the relative arrangement position with respect to the vibration beam. FIG. 23 shows that the vibrating beam 192 is vibrated in different resonance modes by the set of three electrode structural elements 199, 200, and 201 shown in the figure, but this embodiment is limited to the configuration shown in FIG. It is also applicable to many configurations.

  The vibration beam 192 has a higher-order resonance mode in addition to the first-order resonance mode, and the magnitude of the higher-order resonance mode varies depending on the arrangement of the electrode structural elements described above. For example, in FIGS. 23B and 23C, the ratio of the amplitude in the higher-order (for example, second-order) mode to the amplitude in the first-order mode is different. In general, the amplitude in the higher-order mode is small, but when the amplitude in the higher-order mode is relatively large, the mode can be used.

  In the nineteenth embodiment, a set of drive systems (a first drive system 204 and a second drive system 205) (including drive electrodes) are arranged for a single vibration beam 192, and their movements are controlled. It was shown that the resonant frequency can be changed by doing so.

<Configuration of MEMS resonator-4>
FIG. 24 is a twentieth embodiment of the present invention and shows another structure of the MEMS resonator. In the present embodiment, the vibration structural element is not a single element but two vibration structural elements having different lengths (herein referred to as “first vibration structural element” and “second vibration structural element”). It is characterized by being separated. That is, the vibration structural elements are two vibration beams having different lengths (first vibration structural element (first vibration beam 212) and second vibration structural element (second vibration beam 213). ) And each vibrates individually. The two vibration beams 212 and 213 are fixed on a common base, but this is not restrictive. In the figure, a first drive system 210 has a slide mechanism including a first electrode structural element 215 (drive electrode) connected to a slider and an electrostatic actuator. The second drive system 211 has a slide mechanism including a second electrode structural element 216 (drive electrode) connected to the slider and an electrostatic actuator. These slide mechanisms are individually controlled. FIG. 6A shows a state in which the drive systems 210 and 211 are “separated”, and FIG. 6B shows a state in which only the first drive system 210 is “close”. Only the second drive system 211 is shown in FIG. The “close” state is shown in FIG. Further, a high frequency signal on which a DC bias is superimposed is omitted. In FIG. 6A, since the first drive system 210 and the second drive system 211 are both “separated”, the two vibration beams do not vibrate. In FIG. 5B, the first electrode structural element 215 connected to the “adjacent” first drive system 210 vibrates the first vibration beam 212 which is the “first vibration structural element”. . In FIG. 5C, the second electrode structural element 216 connected to the “adjacent” second drive system 211 vibrates the second vibration beam 213 which is the “second vibration structural element”. . If the vibration beams 212 and 213 are set to have different vibration characteristics, different frequency characteristics can be obtained in FIGS. In order to realize “different vibration characteristics”, the configuration of “vibration beams having different lengths” is adopted in the figure, but this is not restrictive. For example, the thickness and width of the beam may be changed with the same length.

  24D, 24E, and 24F are electrical equivalent circuits of the MEMS resonator shown in FIG. (D) corresponds to (a), (e) corresponds to (b), and (f) corresponds to (c). It has been shown that two different electrical resonant circuits can be switched. In FIG. 4D, the MEMS resonator is not operating and the resonance circuit system is disconnected. In the conventional frequency switching circuit, a resonant circuit system having two different frequency characteristics is switched by a circuit element such as a semiconductor switch. However, in such a configuration, it is known that characteristics when the semiconductor switch is ON (for example, ON resistance) and characteristics when the semiconductor switch is OFF (for example, insulation impedance) deteriorate the characteristics of the switching circuit. Particularly, in the case of a high frequency circuit, the characteristics of the semiconductor switch are also deteriorated, so that the characteristics of the resonance circuit system are also deteriorated. However, in the configuration shown in the figure, the vibration system having two different frequency characteristics is switched between the “separated” state and the “close” state of the electrode structural elements 215 and 216, which is caused by the semiconductor switch. Characteristic deterioration can be prevented.

  In FIG. 24, by individually controlling the movement of the drive systems 210 and 211, either one of the two vibration beams 212 and 213 is vibrated to obtain different frequency characteristics, and the resonator system is separated. It is a feature that can be done.

<Configuration of MEMS resonator-5>
FIG. 25 is a twenty-first embodiment of the present invention and shows another configuration of the MEMS resonator, that is, a disk-type (disk-shaped) resonator. In the figure, the same reference numerals as those in FIG. 7 denote the same components. In the figure, the slider 220 is connected to an electrode structure element 221 (drive electrode). The slider 220 can be moved in the vertical direction of the drawing by an electrostatic actuator or the like. Further, the disk 222 can vibrate, its shape is circular, and its central part is fixed by a base part 223. The disk 222 is floating except for the area of the base part 223. Such a structure can be created by a process similar to the manufacturing process described above. FIG. 5A shows a state where the electrode structural element 221 and the disk 222 are “separated”, and is a state immediately after the MEMS resonator is formed. The slider 220 is moved in a designated direction (indicated by an upward arrow in the figure) by the fixed comb-shaped electrode 38 or the like, and a state of being “close” is shown in FIG. In such a state, the disk 222 is vibrated by the high frequency signal applied to the electrode structure element 221. The surface of the electrode structure element 221 facing the disk 222 is a curved surface, and preferably has a curvature such that the distance to the disk is equal in the state shown in FIG. This is not the case.

  In FIG. 25, a disk-shaped “disk” type resonator is described. The shape of the disk 222 is not limited to a disk shape, and may be a polygonal flat plate shape. Further, the present invention may be applied to a “ring type” resonator similar to a disk type resonator. The “ring type” includes (1) a concentric ring (a shape similar to a donut), (2) at least two support beams arranged in the diameter direction of the ring, and (3) a ring center. A base portion that is disposed in the region and fixes a region where the support beams intersect, and (4) an electrode structure element as a drive electrode that vibrates the beam. In such a configuration, the ring becomes a region where the vibration structural element vibrates.

  As illustrated in FIG. 25, according to the present invention, the electrode structure element 221 and the disc 222 that can vibrate are created in a “separated” state and brought into an “close” state by external control means, and the electrode structure The disk 222 can be vibrated by a high-frequency signal to the element 221.

<Configuration of MEMS resonator-6>
FIG. 26 is a twenty-second embodiment of the present invention and shows another structure of the MEMS resonator, that is, a disk-type (disk-shaped) resonator. In the figure, the same reference numerals as those in FIG. 25 denote the same components. In the present embodiment, the first drive system 230 and the second drive system 231 are arranged facing the periphery of the disk 222. The first drive system 230 includes a first slider 232, a first electrode structural element 233 connected to the first slider 232, an electrostatic actuator having a fixed comb electrode, and the like. The second drive system 231 includes a second slider 234, a second electrode structural element 235 connected to the second slider 234, an electrostatic actuator having a fixed comb electrode, and the like. FIG. 6A shows a state in which the first electrode structure element 233 and the second electrode structure element 235 are “separated” from the disk 222, and is a state immediately after the MEMS resonator is formed. The first slider 232 is moved in the designated first direction (in the direction indicated by the upward arrow in the figure) by the fixed comb-shaped electrode or the like, and the second slider 234 is designated. The state of moving in the second direction (the direction indicated by the downward arrow in the figure) and “close to each other” is shown in FIG. In such a state, the disk vibrates by a high frequency signal applied to the first electrode structure element 233 and the second electrode structure element 235. The surfaces of the first electrode structural element 233 and the second electrode structural element 235 facing the disk are both curved surfaces, and the distance between the disk and the disk is equal in the state shown in FIG. However, this is not a limitation.

  The configuration in FIG. 26 has vibration characteristics different from the configuration illustrated in FIG. It is well known that there are various vibration modes of a disk-type MEMS resonator. For example, (1) a mode in which the entire disk 222 expands and contracts in the radial direction of the disk 222, (2) a mode in which the disk 222 extends in a first direction of the diameter of the disk 222 and contracts in a second direction orthogonal to the first direction, (3) A mode in which the disk 222 is distorted and becomes elliptical. FIG. 26 exemplifies a case where the first electrode structural element 233 and the second electrode structural element 235 face each other across the disk 222. In such a configuration, the above (2) and ( 3) is the main vibration mode. In addition, the second electrode structure element 235 is arranged at a position not facing the first electrode structure element 233 (for example, the first electrode structure element 233 is placed at the 6 o'clock direction of the watch, By disposing the element 235 in the 3 o'clock direction of the timepiece, the vibration mode of the disk 222 can be selected. As a result, the electrical frequency characteristic can be made variable. Furthermore, it is possible to select many vibration modes by arranging two or more electrode structural elements and setting the positions where they are arranged. As an example, four electrode structure elements are provided in the periphery of the disk, and each electrode structure element is arranged at a position at 12 o'clock, 3 o'clock, 6 o'clock, or 9 o'clock in the timepiece. .

  As an alternative to the disk 222 of FIG. 26, it is also possible to use a ring of the aforementioned “ring-type” resonator.

<Configuration of MEMS resonator-7>
FIG. 27 is a twenty-third embodiment of the present invention and shows another configuration of the MEMS resonator, that is, an octagonal disk-type resonator. In the figure, a disk 270 is an octagonal disk, and its four corners are connected to a base portion 272 via beams 271. Further, the disk 270 and the beam 271 are levitated and are arranged so that the disk 270 can vibrate. An electrode structural element 274 connected to a slider 273 is disposed opposite to the end of the disk 270. In the figure, an example is shown in which the electrode structure elements 274 are arranged at two positions above and below (on the drawing), but the present invention is not limited to this. That is, there is a structure in which a single electrode structure element 274 is arranged, and a structure in which electrode structure elements 274 are arranged in four places. Both ends of the slider 273 are supported by the beam 275 and connected to the base portion 276. The electrode 277 is a set of electrodes arranged to face the slider. By applying a DC voltage (not shown) between the electrode 277 and the slider 273, the slider 273 moves toward the disk 270, and when the electrode 277 contacts the electrode 277, the movement stops. That is, the slider 273 is arranged close to the disk 270 up to the “designated second distance”.

  In this specification, beam type, disk type (disc shape and octagonal), and ring type MEMS resonators are given as examples, but there are many other forms of the MEMS resonator. There is. For example, there are “fish-bone type” and “a coupled resonator in which vibration regions of a plurality of adjacent MEMS resonators are mechanically coupled”. The present invention can be implemented for many of these forms.

  According to the present invention, two electrode structural elements can be easily arranged close to each other, and the effect when applied to a MEMS device is great. In particular, when applied to a MEMS resonator, high frequency can be easily achieved and a frequency variable mechanism can be provided. Furthermore, since the MEMS resonator is manufactured using silicon semiconductor technology, it can be integrated with a driving circuit and a signal processing circuit in one chip, and is effective for upgrading a semiconductor integrated circuit. Such a function can contribute to the enhancement of functions of portable devices, particularly portable communication devices. In addition, multi-frequency communication represented by cognitive communication promotes downsizing and low power consumption of devices, and can be used to construct a ubiquitous environment.

1, 36, 241, 271, 275 Beam 2 Single crystal silicon substrate 3 Drive electrodes 4, 45, 90, 91, 247, 256 DC voltage 5, 72, 73 Gap 6 Dimple 10 Structural elements 11, 14, 15, 40 Insulation Layer 12, 32, 162, 196, 199, 200, 201, 215, 216, 221, 233, 235, 274 Electrode structural element 13, 33 Vibrating structural element 20, 35, 150, 161, 195, 198, 220, 232 234, 240, 260, 273 Slider 21, 25, 37, 41, 82, 83, 193, 194, 223, 242, 272, 276 Base part 22, 110, 120, 135, 140, 151 Protrusion 26 Base mother Base 30, 31, 50, 56, 60, 62, 84, 85, 111, 121, 153, 154, 164, 16 , 170, 171, 245, 246 Line segments 38, 70, 71, 197 Comb electrodes 39, 46, 52, 54, 64, 92, 93 Arrow 51 Conductive path 53 Magnetic field 61 Ultrasonic vibration mechanism 80, 160 MEMS resonator 81, 163, 192, 212, 213 Vibration beam 87, 249 DC bias 88, 248, 255 High-frequency signal 100, 166, 167, 168, 174 Substrate layer 101, 175, 178 Device layer 102 Oxide layer 103, 105, 181 , 182, 183 Mask layer 104, 106, 107, 108, 109, 186, 187, 188, 261 Region 130 Projection base 131, 133 Tip 132, 134 Silicon oxide layer 152 Stopper receiver 172 Groove 176, 177 Plug 190, 204 , 205, 210, 211, 230, 231 drive 191 detection system 222,270 disks 243,277 electrode 262 protrusion 263 recess

Claims (14)

In a method for manufacturing a semiconductor device,
Connect the electrode structure element to the slider,
Providing a vibrating structural element facing the electrode structural element via a first distance;
The slide mechanism for sliding the slider causes the slider to move in a designated direction until the distance between the electrode structural element and the vibrating structural element is a designated second distance that is shorter than the first distance. A method of manufacturing a semiconductor device, characterized by comprising: The method of manufacturing a semiconductor device according to claim 1, wherein the slider is made of a material containing silicon. The sliding mechanism is made of a material containing silicon,
The method of manufacturing a semiconductor device according to claim 1, wherein the slider is moved by a driving force including an electrostatic force. The specified second distance is determined by a length of the electrode structural element, the vibration structural element, or a stopper disposed on the slider. The manufacturing method of the semiconductor described. The vibrating structural element is a vibrating body of a MEMS resonator;
The method of manufacturing a semiconductor device according to claim 1, wherein the electrode structural element is a drive electrode that vibrates the vibrating body. A MEMS resonator which is a form of a MEMS device,
A slider,
An electrode structure element coupled to the slider;
The electrode structural element is arranged to be opposed to each other through a first distance, and is composed of a vibration structural element that mechanically vibrates,
The slider has a slide mechanism that slides the slider in a specified direction;
The amount of movement of the slider by the slide mechanism is determined by a specified second distance that is shorter than the first distance. The MEMS resonator according to claim 6, wherein the slider, the electrode structural element, and the vibration structural element are made of a material containing silicon. The sliding mechanism is made of a material containing silicon,
The MEMS resonator according to claim 6 or 7, wherein the slider is moved by a driving force including an electrostatic force. The specified second distance is determined by the length of the electrode structural element, the vibration structural element, or a stopper disposed on the slider. The MEMS resonator as described. The vibrating structural element is a vibrating beam of a beam-type MEMS resonator fixed at both ends,
The MEMS resonator according to claim 6, wherein the electrode structural element is a drive electrode of the beam-type MEMS resonator. The vibration structural element is a ring-type or disk-type MEMS resonator vibration body,
The MEMS resonator according to any one of claims 6 to 9, wherein the electrode structural element is a drive electrode of the ring type or disk type MEMS resonator. A MEMS resonator which is a form of a MEMS device,
Vibration structural elements that vibrate mechanically;
A first electrode structural element disposed opposite the first side of the vibrating structural element via a third distance and coupled to a first slider;
A first slide mechanism for moving the first slider in a first direction;
The vibration structural element is disposed on the second side opposite to the first side with respect to the first vibration structural element and is opposed to the second slider via a fourth distance, and is connected to the second slider. A second electrode structural element;
A second slide mechanism for moving the second slider in a second direction;
The amount of movement of the first slider by the first slide mechanism is determined by a designated fifth distance;
The MEMS resonator, wherein a movement amount of the second slider by the second slide mechanism is determined by a designated sixth distance. The first slider, the first electrode structural element, the vibration structural element, the second slider, and the second electrode structural element are made of a material containing silicon,
The MEMS resonator according to claim 12, wherein the first slider and the second slider move by a driving force including an electrostatic force. The designated fifth distance is determined by a length of a stopper disposed on the first electrode structural element, or the first slider, or the vibration structural element,
The specified sixth distance is determined by a length of a stopper disposed on the second electrode structural element, the second slider, or the vibrating structural element. Alternatively, the MEMS resonator according to 13.

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