Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B81—MICROSTRUCTURAL TECHNOLOGY
  • B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
  • B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
  • B81C1/00642—Manufacture or treatment of devices or systems in or on a substrate for improving the physical properties of a device
  • B81C1/0065—Mechanical properties
  • B81C1/00666—Treatments for controlling internal stress or strain in MEMS structures
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
  • G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
  • G01P15/02—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
  • G01P15/08—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B81—MICROSTRUCTURAL TECHNOLOGY
  • B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
  • B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
  • B81C1/00349—Creating layers of material on a substrate
  • B81C1/00357—Creating layers of material on a substrate involving bonding one or several substrates on a non-temporary support, e.g. another substrate
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B81—MICROSTRUCTURAL TECHNOLOGY
  • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
  • B81B7/00—Microstructural systems; Auxiliary parts of microstructural devices or systems
  • B81B7/02—Microstructural systems; Auxiliary parts of microstructural devices or systems containing distinct electrical or optical devices of particular relevance for their function, e.g. microelectro-mechanical systems [MEMS]
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B81—MICROSTRUCTURAL TECHNOLOGY
  • B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
  • B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
  • G01P1/00—Details of instruments
  • G01P1/02—Housings
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
  • G01P1/00—Details of instruments
  • G01P1/02—Housings
  • G01P1/023—Housings for acceleration measuring devices
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
  • G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
  • G01P15/02—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
  • G01P15/08—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values
  • G01P15/0802—Details
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
  • G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
  • G01P15/02—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
  • G01P15/08—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values
  • G01P15/097—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values by vibratory elements
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
  • G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
  • G01P15/02—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
  • G01P15/08—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values
  • G01P15/12—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values by alteration of electrical resistance
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
  • G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
  • G01P15/02—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
  • G01P15/08—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values
  • G01P15/12—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values by alteration of electrical resistance
  • G01P15/123—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values by alteration of electrical resistance by piezo-resistive elements, e.g. semiconductor strain gauges
• • 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
  • B81B2201/0235—Accelerometers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B81—MICROSTRUCTURAL TECHNOLOGY
  • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
  • B81B2207/00—Microstructural systems or auxiliary parts thereof
  • B81B2207/09—Packages
  • B81B2207/091—Arrangements for connecting external electrical signals to mechanical structures inside the package
  • B81B2207/094—Feed-through, via
  • B81B2207/096—Feed-through, via through the substrate
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
  • G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
  • G01P15/02—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
  • G01P15/08—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values
  • G01P2015/0805—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values being provided with a particular type of spring-mass-system for defining the displacement of a seismic mass due to an external acceleration
  • G01P2015/0822—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values being provided with a particular type of spring-mass-system for defining the displacement of a seismic mass due to an external acceleration for defining out-of-plane movement of the mass
  • G01P2015/084—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values being provided with a particular type of spring-mass-system for defining the displacement of a seismic mass due to an external acceleration for defining out-of-plane movement of the mass the mass being suspended at more than one of its sides, e.g. membrane-type suspension, so as to permit multi-axis movement of the mass
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
  • G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
  • G01P15/02—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
  • G01P15/08—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values
  • G01P2015/0862—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values being provided with particular means being integrated into a MEMS accelerometer structure for providing particular additional functionalities to those of a spring mass system
  • G01P2015/088—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values being provided with particular means being integrated into a MEMS accelerometer structure for providing particular additional functionalities to those of a spring mass system for providing wafer-level encapsulation

Definitions

• the invention relates to the field of inertial sensors, such as accelerated meters or gyrometers, made in MEMS technology (English acronym for "microelectromechanical System” in English or “electromechanical microsystem” in French) or NEMS (acronym for English). Saxon for "nanoelectromechanical System” in English or “electromechanical nanosystem” in French).
• the invention relates to a method for manufacturing an inertial sensor with resonant-type measuring beam or variable resistance type, for example piezoresistive.
• resonant-type measuring beam or variable resistance type for example piezoresistive.
• An inertial sensor such as an accelerometer, in particular to measure the acceleration experienced by an object to which it is reported.
• a sensor comprises in particular a test body (also called test mass) coupled to one or more measuring beams.
• test body also called test mass
• an inertial force is applied to the test body, and induces a stress on the beam.
• the stress applied by the mass of the test body induces a variation of the frequency of the resonator.
• the stress applied by the mass of the test body induces a variation of the electrical resistance. This is what allows to calculate the acceleration.
• EP 2 211 185 discloses a sensor in which the test body has a thickness greater than that of the beam, and furthermore proposes two methods of manufacturing such a sensor based on SOI technology ("Silicon On Insulator"). in English or “Silicon on Insulator” in French).
• the strain gauge is first etched in a surface layer of an SOI substrate, then covered with a protection. Silicon epitaxy is then performed on this surface layer so as to obtain a layer of thickness desired for producing the test body.
• the epitaxial growth technique is cumbersome and expensive to implement, and does not make it possible to obtain very large thicknesses of silicon layer. Because of this limitation, it is difficult to obtain an optimal dimensioning of the test body, and therefore of its mass, to maximize the stress applied to the gauge.
• the test body is first etched in an SOI substrate.
• a polycrystalline silicon layer of nanometric thickness is then deposited for the formation of the strain gauge.
• the small thickness of the polycrystalline silicon layers is still difficult to control, and its mechanical and electrical properties are lower than those of a monocrystalline silicon layer.
• the deposition of such a thin layer may be subject to constraints, such as deformations, which may affect the performance of the gauge. It is therefore difficult, by this method, to obtain a gauge having mechanical and electrical characteristics that optimize the sensitivity of the sensor.
• the present invention is intended to provide a novel method of manufacturing an inertial sensor free from the limitations mentioned above.
• the object of the invention is notably to propose a manufacturing method making it possible to optimize the dimensions of the test body and of the strain gauge so as to improve the performance of the sensor.
• the object of the invention is in particular to propose a more efficient inertial sensor, comprising a lower thickness strain gauge, in mono-crystalline silicon, and a larger mass proof body.
• the subject of the invention is thus a method for manufacturing an inertial sensor comprising at least:
• This method offers a better control of the dimensions of the beams and the active body, and thus optimizes both the thickness of the active body and the thickness of the beam.
• This method makes it possible in particular to obtain measuring beams of very small thickness and an active body of larger mass.
• the constraints likely to deteriorate the performance of the measuring beams are limited throughout the process Manufacturing.
• the sensitivity of the measuring beam is improved without limiting the mass of the test body.
• the combination of a test body having a high mass and a measuring beam of small thickness provides a better sensitivity in the detection of the inertial measurement.
• the method further comprises making an electrical contact between the active body and the measuring beam.
• this electrical contact can be made during the sealing of the first active layer with the second active layer, this seal making it possible to make a mechanical contact and an electrical contact between the beam and the active body.
• the measurement beam is made of piezoresistive strain gauge material, the electrical resistance of the material varying with the stress applied to the mass.
• the measuring beam is a mechanical resonator, the frequency of the resonator varying with the stress applied to the mass.
• the resonator comprises a vibrating blade, an excitation means and a means for detecting the vibration.
• the ratio of the first thickness to the second thickness is greater than or equal to 5.
• the manufacturing process may further include:
• the medium in which the measuring beam and the active body are enclosed contains a vacuum, so as to limit any degradation of the resolution of the sensor.
• all the seals of the manufacturing process are carried out under vacuum or in a controlled atmosphere.
• a vacuum seal is preferred for the production of an inertial sensor provided with a resonator, and a seal under an atmosphere Controlled is preferred for the realization of an inertial sensor provided with piezoresistive strain gage.
• the measuring beam is made of monocrystalline silicon, advantageously doped to improve the sensitivity of the piezoresistive beam.
• the test mass may also be monocrystalline silicon.
• the first and second substrates are of the SOI type.
• the invention also relates to an inertial sensor comprising at least one measuring beam and an active body formed of a test body and deformable blades, said active body being kept in suspension inside a hermetic enclosure via its blades, and the measuring beam connecting a portion of the test body to an inner wall 15 of said enclosure, said measuring beam having a thickness less than that of the test body.
• FIGS. 1 to 15 are diagrammatic views illustrating the steps of the method of manufacturing an inertial sensor according to an embodiment of the invention.
• an inertial sensor of the piezoresistive or resonant type comprises, in particular, measuring beams 23 of the piezoresistive or resonator type and an active body formed of a test body.
• Mobile and deformable blades 14 The test body 13 is held in suspension inside a chamber 30, 40 hermetic, measuring beams 23 connecting the deformable blades to the inner wall of the enclosure. These measuring beams 23 have in particular a thickness less than that of the test body 13.
• the deflection of the test body 13 causes a variation of the frequency of the resonator, and in the case of a measurement beam 23 of the piezoresistive strain gauge type, the deflection of the body test 13 induces the variation of the electrical resistance of the gauge, this variation can be recovered via electrical pad disposed inside recesses.
• first substrate 1 which may be a slice of SOI type material (English acronym for "Silicon On Insulator") comprising a first active layer 10 of a first thickness e ls for example of the order of ⁇ to ⁇ , and a non-active layer consisting of an insulating layer 11 (for example a layer of oxide) and a support layer 12 (or bulk), etching is performed in this first active layer 10.
• This etching (FIG. 1)
• the first active layer comprises the test body 13, the blades deformable 14 and a frame 15.
• a second substrate 2 which may also be a slice of SOI type material comprising a second active layer 20 of a second thickness e 2 , for example of the order of 100 nm to ⁇ ⁇ , and a non-active layer consisting of an insulating layer 21 and a support layer 22, an etching is carried out in this first active layer 20.
• This etching (FIG. 4), for example a photolithography, consists in forming the measuring beams 23 in this second active layer 20.
• the first and second active layers 10, 20 are then sealed between so as to achieve a mechanical seal and an electrical contact between the deformable blades and the measurement beams ( Figures 5 and 6).
• the measurement beams can be positioned between the test body 13 and the frame 15. And, of course, it is possible to make this electrical contact independently of the mechanical seal between the two active layers 10, 20.
• the non-active layer, namely the insulating layer 11 and the support layer 12, of the first substrate is eliminated (FIG. 7). In other words, the test body 13 is in suspension and is held at the second substrate 2 by means of the measuring beams 23.
• a first cavity 30 is made to contain the body. active, for example by DRIE type engraving.
• this first cavity 30 is made in the insulating layer and a portion of the support layer, as illustrated in FIG. 8.
• This third substrate 3 is then sealed (FIGS. 9 and 10) to the active layer of the first substrate 1 so that the active body is found inside this first cavity 30.
• the free surface of the insulating layer 31 of the third substrate 3 is sealed to the free surface of the frame 15 of the first active layer.
• a second cavity 40 is also produced, for example by DRIE type engraving.
• this second cavity 30 is made in the insulating layer and a portion of the support layer, as illustrated in FIG.
• This fourth substrate 4 is then sealed (FIGS. 12 and 13) to the active layer of the second substrate 2 so that the active body and the measuring beams are encapsulated inside the hermetic enclosure formed by the first and second cavities 30, 40.
• Recesses passing through the thickness of the third substrate 3 and opening at the frame 15 of the first substrate 1 can also be made (FIG. 14).
• the deposition of an electrical contact point 6 in these recesses makes it possible to recover the electrical signal generated during the deflection of the test body 13.
• the manufacturing method of the invention makes it possible, in particular, to produce inertial sensors provided in particular with a larger mass proof body combined with measurement gages of the strain gauge type or resonators of very low thickness, without any alteration of the the sensitivity of the whole.
• the solution of the invention makes it possible to optimize the dimensions of the test body and measurement beams so as to improve the performance of the sensor. It is therefore possible to obtain both a high mass test body to induce high stress on the measurement beams, and measurement beams of very small thickness for better detection sensitivity.

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• Engineering & Computer Science (AREA)
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• General Physics & Mathematics (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Manufacturing & Machinery (AREA)
• Mechanical Engineering (AREA)
• Computer Hardware Design (AREA)
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• Gyroscopes (AREA)

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• 2011
  • 2011-03-03 FR FR1151746A patent/FR2972263B1/fr not_active Expired - Fee Related
• 2012
  • 2012-02-02 WO PCT/FR2012/050236 patent/WO2012117177A1/fr active Application Filing
  • 2012-02-02 CN CN201280010090.1A patent/CN103518138A/zh active Pending
  • 2012-02-02 JP JP2013555919A patent/JP2014512518A/ja active Pending
  • 2012-02-02 US US14/001,799 patent/US20140024161A1/en not_active Abandoned
  • 2012-02-02 KR KR1020137022957A patent/KR20140074865A/ko not_active Application Discontinuation
  • 2012-02-02 EP EP12707855.8A patent/EP2681568A1/de not_active Withdrawn

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