Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
  • G01C19/00—Gyroscopes; Turn-sensitive devices using vibrating masses; Turn-sensitive devices without moving masses; Measuring angular rate using gyroscopic effects
  • G01C19/02—Rotary gyroscopes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B81—MICROSTRUCTURAL TECHNOLOGY
  • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
  • B81B3/00—Devices comprising flexible or deformable elements, e.g. comprising elastic tongues or membranes
  • B81B3/0064—Constitution or structural means for improving or controlling the physical properties of a device
  • B81B3/0067—Mechanical properties
  • B81B3/0078—Constitution or structural means for improving mechanical properties not provided for in B81B3/007 - B81B3/0075
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B81—MICROSTRUCTURAL TECHNOLOGY
  • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
  • B81B3/00—Devices comprising flexible or deformable elements, e.g. comprising elastic tongues or membranes
  • B81B3/0062—Devices moving in two or more dimensions, i.e. having special features which allow movement in more than one dimension
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
  • G01C19/00—Gyroscopes; Turn-sensitive devices using vibrating masses; Turn-sensitive devices without moving masses; Measuring angular rate using gyroscopic effects
  • G01C19/56—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
  • G01C19/5719—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using planar vibrating masses driven in a translation vibration along an axis
  • G01C19/5733—Structural details or topology
  • G01C19/5755—Structural details or topology the devices having a single sensing mass
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B81—MICROSTRUCTURAL TECHNOLOGY
  • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
  • B81B2201/00—Specific applications of microelectromechanical systems
  • B81B2201/02—Sensors
  • B81B2201/0228—Inertial sensors
  • B81B2201/0242—Gyroscopes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B81—MICROSTRUCTURAL TECHNOLOGY
  • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
  • B81B2203/00—Basic microelectromechanical structures
  • B81B2203/01—Suspended structures, i.e. structures allowing a movement
  • B81B2203/0136—Comb structures
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B81—MICROSTRUCTURAL TECHNOLOGY
  • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
  • B81B2203/00—Basic microelectromechanical structures
  • B81B2203/04—Electrodes

Definitions

• the present invention relates to a micromachined gyroscope and a
• Micro inertial sensors are one application among various aspects
• inertial sensors made of silicon are inexpensive, mass-producible, and can
• micromachined gyroscopes have not been commercialized yet. For their
• the element can operate at a low Q value, and thereby two
• a gyroscope comprises: a
• driving fixed electrode being fixed; a driving displacement electrode being fixed
• sensing displacement electrode being connected to the inertial mass
• the driving displacement electrode is supported by a folded spring
• the driving displacement electrode and the inertial mass can be any driving displacement electrode and the inertial mass.
• inertial mass can be movable in the first direction and are connected by a folded spring having no fixture shaft.
• Two sensing displacement electrodes are provided on two sides of
• the gyroscope further comprises an edge gimbal for connecting the two sensing displacement electrodes.
• a cavity is provided in the center of the inertial mass, and the gyroscope further comprises a displacement limit shaft provided to the
• the gyroscope further comprises tuning electrodes, each
• a gyroscope comprises: (a) performing anodic bonding on a silicon
• gyroscope structure to connect it to an external circuit.
• the method further comprises dicing the silicon substrate and the
• the metallic layer formed in (c) is a double layer of Cr and Au, and
• the glass substrate is etched using an HF solution in (e).
• the depth for etching the glass substrate using the HF solution is
• the silicon substrate is etched using a KOH aqueous solution of
• FIG. 1 shows a perspective view of a gyroscope according to a
• FIG. 2 shows a floor plan of a gyroscope according to a preferred
• FIG. 3 shows a magnified portion of FIG. 1 ;
• FIG. 4 shows a partial SEM (scanning Electron Microscope)
• FIG. 5 shows a magnified view of a driving or sensing spring of a
• FIG. 6 shows an SEM photograph of a driving or sensing spring of
• FIG. 7 shows a concept view of a driving or sensing connection
• FIG. 8 shows a graph of resonance driving and sensing
• FIGs. 9(a) to 9(h) show a process for fabricating a gyroscope
• the invention is capable of modification in
• FIG. 1 shows a perspective view of a gyroscope according to a
• FIG. 2 shows a floor plan of
• FIG. 3 shows a magnified portion of FIG. 1
• FIG. 4 shows a partial
• present invention comprises a glass substrate 10 and a silicon structure
• the silicon structure comprises a driver, sensor, a plurality of
• the sensor comprises a sensing fixing electrode 25, a sensing displacement electrode 22, and an edge gimbal 21.
• springs comprise driving springs 28 and 29 for supporting and allowing
• sensing connection spring 32 for connecting the sensing
• the driving fixing electrode 26 of the driver is fixed by the
• the driving displacement electrode 24 is supported by the external
• inertial mass 23 is vibrated together with the driving displacement electrode
• the sensing displacement electrode 22 is supported by the
• the sensing displacement electrode 22 is connected to the
• sensing connection spring 32 delivers the south to north directional
• the edge gimbal 21 totally surrounds the driver and the sensor
• Each tuning electrode 34 of a total of four, is formed on the east
• spaced toothed portion is formed on the tuning electrode's surface facing
• displacement electrodes 22 face those of the tuning electrode 34.
• the displacement limit shaft 33 formed in the center of a cavity
• driving displacement electrode 24 is electrostatically driven according to the
• the inertial mass 23 is also vibrated
• the tuning electrode 34 functions as an electric spring, and it varies the resonance frequency of the sensing
• shaft 33 limits driving displacement of the inertial mass 23 within a uniform
• FIG. 5 shows a magnified view of a driving or sensing spring of a
• FIG. 6 shows an SEM photograph of a driving or sensing spring of a
• the driving or sensing spring comprises a fixture shaft 1 , a
• connector 2 connects the internal plate 3 with the external plate 4.
• sensing displacement electrode which is determined according to a
• the spring of this structure is referred to
• the thin layer provided on the silicon structure As a folded spring. Referring to FIG. 5, the thin layer provided on the silicon structure
• This metallic layer is a metallic layer. This metallic layer is formed to perform flip chip bonding
• FIGs. 1 to 4 omit this illustration.
• the structure are used for injecting etchant when etching the glass
• the cavities are formed on all portions of the structure except for
• connection spring 31 or 32 applied to the preferred embodiment of the
• FIG. 7 shows a concept view of a driving or sensing connection
• connection spring comprises a connector 2, an internal plate 3,
• the connector 2 connects
• connection spring or a sensing connection spring
• FIG. 8 shows a graph of resonance driving and sensing
• the present gyroscope provides a problem in that the output performance is very sensitive to external noise (the degrees of vacuum or variations of frequency). To overcome this problem, the present gyroscope provides a
• the driving displacement is uniformly maintained in the
• the gyroscope can be operated in the sensing resonance frequency
• FIGs. 9(a) to 9(h) show a process for fabricating a gyroscope
• resistive silicon wafer 20 and a glass substrate 10 such as Pyrex #7740 for
• the silicon wafer 20 is etched using a KOH
• the thickness of the silicon wafer 20 After the etching, the thickness of the silicon wafer 20
• CMP chemical mechanical polishing
• the etchant is a 36wt.% KOH aqueous solution, used at
• KOH etching, hillocks and pit holes are formed on the silicon surface.
• the surface of the silicon wafer 20 is
• an oxidized layer (not illustrated) is deposited on the
• the photoresist pattern includes a pattern for
• the oxidized layer is etched using the
• photoresist pattern 50 as an etching mask, and reactive ion etching (RIE) is
• the glass substrate 10 is etched in a 49% HF
• the silicon structure 20 can float
• layer 40 is flip-chip-bonded on an electrode structure for wiring on a printed
• PCB circuit board
• the photoresist and the oxidized layer are used as
• the gyroscope is fabricated based on very simple processes, and
• the fabricated gyroscope has only one
• gyroscope is connected to a circuit.
• the driver and the sensor of the gyroscope structure adopt a
• the Q value of the structure may be predicted based on the
• the structure are designed to be greater than 5kHz in order to remove
• the driving and sensing frequencies are predicted
• a displacement limiter that artificially limits the displacement
• the gyroscope structure has a form basically identical with a two-
• the number of combed electrode structures in the structure is maximized in order to maximize the driving and sensing sensitivities
• edge gimbals are adopted in order to minimize mechanical interference.
• the size of the gyroscope structure is 8 x 8 mm 2 , and the whole size,
• the thickness of the structure is designed to be 50 ⁇ m. Also, the thickness of the structure is designed to be 50 ⁇ m.
• gyroscope structure is floated above the glass substrate by 50 ⁇ m so as to
• a damping value is to be calculated in order to
• the driver has 426 combed electrode structures and 6 folded
• the spring coefficient is calculated to be 2,684 and the driving
• the driving voltage is set to be
• the detector has 692 combed electrode structures and 6 folded
• the Q factor of the detector is calculated to
• the oxidized layer used as a deep RIE etching mask undergoes an
• deep RIE is fabricated to be narrower than the conventional one by about
• the thickness of the fabricated structure is 44 ⁇ m, and the deep RIE is
• the gap between the substrate and the structure is measured to be 37 ⁇ m.
• the gyroscope according to the present invention has 426 driving
• the gyroscope has a displacement limiter provided in the
• * represents a calculated displacement with applied voltage
• V(t) 15 + 3cos ⁇ dn [V] (bi-directional), and ** shows a measured
• the driver the operation of the sensor, or the operation of the driver and the
• the resonance frequencies range between 5,500 and 6,500Hz
• the driving voltage is artificially increased to check the
• the present invention provides an electrostatically driven and
• a gyroscope operable in atmospheric pressure is provided;
• etching cavities on its front side is provided through a single
• the fabricated gyroscope structure can be directly integrated into
• the present gyroscope can solve
• the structure is designed so that it may have as many driving and
• sensing electrodes as possible and as large an inertial mass as possible so
• the gyroscope structure has the
• limiting driving displacement is mechanically added so as to provide a
• the fabricated gyroscope is operable in atmospheric pressure

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• Engineering & Computer Science (AREA)
• Computer Hardware Design (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Mechanical Engineering (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Radar, Positioning & Navigation (AREA)
• Remote Sensing (AREA)
• Gyroscopes (AREA)

Priority Applications (4)

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Publications (1)

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Citations (2)

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• 2001
  • 2001-02-12 KR KR10-2001-0006695A patent/KR100418624B1/ko not_active Expired - Lifetime
• 2002
  • 2002-01-30 JP JP2002564435A patent/JP3713019B2/ja not_active Expired - Fee Related
  • 2002-01-30 EP EP02711501A patent/EP1360144B1/en not_active Expired - Lifetime
  • 2002-01-30 DE DE60229919T patent/DE60229919D1/de not_active Expired - Fee Related
  • 2002-01-30 CN CNB028002954A patent/CN1242913C/zh not_active Expired - Fee Related
  • 2002-01-30 US US10/257,532 patent/US6845668B2/en not_active Expired - Fee Related
  • 2002-01-30 AT AT02711501T patent/ATE414674T1/de not_active IP Right Cessation
  • 2002-01-30 WO PCT/KR2002/000135 patent/WO2002064497A1/en not_active Ceased

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