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EP2681568A1 - Method of fabricating an inertial sensor - Google Patents

Method of fabricating an inertial sensor

Info

Publication number
EP2681568A1
EP2681568A1 EP12707855.8A EP12707855A EP2681568A1 EP 2681568 A1 EP2681568 A1 EP 2681568A1 EP 12707855 A EP12707855 A EP 12707855A EP 2681568 A1 EP2681568 A1 EP 2681568A1
Authority
EP
European Patent Office
Prior art keywords
substrate
active
active layer
thickness
measuring beam
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP12707855.8A
Other languages
German (de)
French (fr)
Inventor
Stéphane Renard
Antoine FILIPE
Joël COLLET
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Tronics Microsystems SA
Original Assignee
Tronics Microsystems SA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Tronics Microsystems SA filed Critical Tronics Microsystems SA
Publication of EP2681568A1 publication Critical patent/EP2681568A1/en
Withdrawn legal-status Critical Current

Links

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

Abstract

Fabrication of an inertial sensor comprising at least one measurement beam (23) and an active body formed of a proof body (13) and of deformable blades (14), said active body being maintained in suspension inside a hermetic enclosure via its blades (14), the measurement beam (23) linking a part of the proof body (13) to an internal wall of said enclosure, said measurement beam (23) exhibiting a thickness less than that of the proof body (13).

Description

PROCEDE DE FABRICATION D'UN CAPTEUR INERTIEL  METHOD FOR MANUFACTURING AN INERTIAL SENSOR
Domaine technique L'invention se rapporte au domaine des capteurs inertiels, tels que accéléra mètres ou gyromètres, réalisés en technologie MEMS (acronyme anglo-saxon pour « microelectromechanical System » en anglais ou « microsystème électromécanique » en français) ou NEMS (acronyme anglo-saxon pour « nanoelectromechanical System » en anglais ou « nanosystème électromécanique » en français). TECHNICAL FIELD 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).
Plus précisément, l'invention se rapporte à un procédé de fabrication d'un capteur inertiel à poutre de mesure de type résonant ou de type à résistance variable, par exemple piézorésistive. Etat de la technique antérieure More specifically, the invention relates to a method for manufacturing an inertial sensor with resonant-type measuring beam or variable resistance type, for example piezoresistive. State of the art
Un capteur inertiel, tel qu'un accéléromètre, permet notamment de mesurer l'accélération subie par un objet auquel il est rapporté. Un tel capteur comprend notamment un corps d'épreuve (également appelé masse d'épreuve) couplé à une ou plusieurs poutres de mesure. Lors d'un déplacement du capteur, une force inertielle s'applique au corps d'épreuve, et induit une contrainte sur la poutre. An inertial sensor, such as an accelerometer, in particular to measure the acceleration experienced by an object to which it is reported. Such a sensor comprises in particular a test body (also called test mass) coupled to one or more measuring beams. During a displacement of the sensor, an inertial force is applied to the test body, and induces a stress on the beam.
Dans le cas d'une poutre de mesure de type résonateur, la contrainte appliquée par la masse du corps d'épreuve induit une variation de la fréquence du résonateur. Dans le cas d'une poutre de mesure de type à résistance variable, par exemple piézorésistif, la contrainte appliquée par la masse du corps d'épreuve induit une variation de la résistance électrique. C'est ce qui permet de calculer l'accélération. In the case of a resonator type measuring beam, the stress applied by the mass of the test body induces a variation of the frequency of the resonator. In the case of a measuring beam of variable resistance type, for example piezoresistive, 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.
De manière générale, il est avantageux d'employer un corps d'épreuve de masse élevée de manière à maximiser la force inertielle lors d'un déplacement, et donc d'induire une contrainte suffisante à la poutre de mesure. En outre, il est également avantageux que la poutre de mesure présente une épaisseur la plus faible possible de manière à maximiser la contrainte appliquée par le corps d'épreuve sur cette poutre. Le document EP 2 211 185 présente un capteur dans lequel le corps d'épreuve présente une épaisseur supérieure à celle de la poutre, et propose en outre deux procédés de fabrication d'un tel capteur basés sur une technologie SOI (« Silicon On Insulator » en anglais ou « Silicium sur Isolant » en français). In general, it is advantageous to use a high mass test body so as to maximize the inertial force during a displacement, and thus to induce sufficient stress to the measuring beam. In addition, it is also advantageous that the measuring beam has a thickness as small as possible so as to maximize the stress applied by the test body on this beam. 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).
Selon le premier procédé de fabrication décrit dans ce document, la jauge de contrainte est tout d'abord gravée dans une couche superficielle d'un substrat SOI, puis recouverte d'une protection. Une épitaxie de silicium est ensuite réalisée sur cette couche superficielle de manière à obtenir une couche d'épaisseur désirée pour la réalisation du corps d'épreuve. Cependant, la technique de croissance par épitaxie est lourde et coûteuse à mettre en œuvre, et ne permet pas d'obtenir des épaisseurs très importantes de couche de silicium. Du fait de cette limite, il est difficile d'obtenir un dimensionnement optimal du corps d'épreuve, et donc de sa masse, pour maximiser la contrainte appliquée à la jauge. According to the first manufacturing method described in this document, 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. However, 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.
Selon le deuxième procédé de fabrication décrit dans ce document, le corps d'épreuve est tout d'abord gravé dans un substrat SOI. Une couche de silicium polycristallin d'épaisseur nanométrique est ensuite déposée en vue de la formation de la jauge de contrainte. Cependant, la faible épaisseur des couches en silicium polycristallin est encore difficile à contrôler, et ses propriétés mécaniques et électriques sont inférieures à celles d'une couche en silicium monocristallin. En outre, le dépôt d'une telle couche mince peut être soumis à des contraintes, telles que des déformations, pouvant affecter les performances de la jauge. Il est donc difficile, par ce procédé, d'obtenir une jauge présentant des caractéristiques mécaniques et électriques qui optimisent la sensibilité du capteur. According to the second manufacturing method described in this document, 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. However, 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. In addition, 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.
Ces solutions ne sont donc pas satisfaisantes, dans la mesure où il faut choisir entre une solution permettant d'obtenir une jauge de contrainte d'épaisseur faible au détriment de la masse du corps d'épreuve, et une solution permettant d'obtenir un corps d'épreuve de masse importante au détriment de la sensibilité de la jauge. Exposé de l'invention These solutions are therefore not satisfactory, insofar as it is necessary to choose between a solution making it possible to obtain a strain gauge of small thickness at the expense of the mass of the test body, and a solution making it possible to obtain a body mass test to the detriment of the sensitivity of the tonnage. Presentation of the invention
Dans ce contexte, la présente invention a notamment pour but de proposer un nouveau procédé de fabrication d'un capteur inertiel exempte des limitations précédemment évoquées. L'invention a notamment pour but de proposer un procédé de fabrication permettant d'optimiser les dimensions du corps d'épreuve et de la jauge de contrainte de manière à améliorer les performances du capteur. L'invention a notamment pour but de proposer un capteur inertiel plus performant, comprenant une jauge de contrainte de plus faible épaisseur, en silicium mono cristallin, et un corps d'épreuve de masse plus importante. In this context, 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.
L'invention a ainsi pour objet un procédé de fabrication d'un capteur inertiel comprenant au moins : The subject of the invention is thus a method for manufacturing an inertial sensor comprising at least:
- la réalisation d'au moins un corps actif formé d'un corps d'épreuve et de lames déformables (constituant, par exemple, des ressorts linéaires ou des axes de torsions), par gravure d'une première couche active d'un premier substrat, ladite première couche active présentant une première épaisseur ;  - The production of at least one active body formed of a test body and deformable blades (constituting, for example, linear springs or torsion axes), by etching a first active layer of a first substrate, said first active layer having a first thickness;
- la réalisation d'au moins une poutre de mesure par gravure d'une deuxième couche active d'un deuxième substrat, ladite deuxième couche active présentant une deuxième épaisseur inférieure à la première épaisseur ;  - Producing at least one measurement beam by etching a second active layer of a second substrate, said second active layer having a second thickness less than the first thickness;
- le scellement de la première couche active avec la deuxième couche active ; sealing the first active layer with the second active layer;
- l'élimination des couches non actives du premier substrat ;- la réalisation d'une première cavité par gravure d'un troisième substrat ; eliminating the non-active layers of the first substrate; producing a first cavity by etching a third substrate;
- le scellement du troisième substrat avec la couche active du premier substrat, le corps actif étant disposé à l'intérieur de la première cavité ;  - Sealing the third substrate with the active layer of the first substrate, the active body being disposed within the first cavity;
- l'élimination des couches non actives du deuxième substrat ;  the elimination of the non-active layers of the second substrate;
- la réalisation d'une deuxième cavité par gravure d'un quatrième substrat ; et the production of a second cavity by etching a fourth substrate; and
- le scellement du quatrième substrat avec la couche active du deuxième substrat. Ce procédé offre notamment un meilleur contrôle des dimensions des poutres et du corps actif, et permet donc d'optimiser à la fois l'épaisseur du corps actif et l'épaisseur de la poutre. Ce procédé permet notamment d'obtenir des poutres de mesure de très faible épaisseur et un corps actif de masse plus importante. En outre, les contraintes susceptibles de détériorer les performances des poutres de mesure sont limitées tout le long du procédé de fabrication. De ce fait, la sensibilité de la poutre de mesure est améliorée sans limitation de la masse du corps d'épreuve. En d'autres termes, la combinaison d'un corps d'épreuve présentant une masse élevée et d'une poutre de mesure de faible épaisseur assure une meilleure sensibilité quant à la détection de la mesure inertielle. - Sealing the fourth substrate with the active layer of the second substrate. 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. In addition, the constraints likely to deteriorate the performance of the measuring beams are limited throughout the process Manufacturing. As a result, the sensitivity of the measuring beam is improved without limiting the mass of the test body. In other words, 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.
Avantageusement, le procédé comprend en outre la réalisation d'un contact électrique entre le corps actif et la poutre de mesure. Par exemple, ce contact électrique peut être réalisé lors du scellement de la première couche active avec la deuxième couche active, ce scellement permettant de réaliser un contact mécanique et un contact électrique entre la poutre et le corps actif. Advantageously, the method further comprises making an electrical contact between the active body and the measuring beam. For example, 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.
Selon un mode de réalisation, la poutre de mesure est en matériau piézorésistif formant jauge de contrainte, la résistance électrique du matériau variant avec la contrainte appliquée à la masse. According to one embodiment, the measurement beam is made of piezoresistive strain gauge material, the electrical resistance of the material varying with the stress applied to the mass.
Selon un autre mode de réalisation, la poutre de mesure est un résonateur mécanique, la fréquence du résonateur variant avec la contrainte appliquée à la masse. Par exemple, le résonateur comprend une lame vibrante, un moyen d'excitation et un moyen de détection de la vibration. According to another embodiment, the measuring beam is a mechanical resonator, the frequency of the resonator varying with the stress applied to the mass. For example, the resonator comprises a vibrating blade, an excitation means and a means for detecting the vibration.
Par exemple, le ratio de la première épaisseur sur la deuxième épaisseur est supérieur ou égale à 5. For example, the ratio of the first thickness to the second thickness is greater than or equal to 5.
Le procédé de fabrication peut en outre comprendre : The manufacturing process may further include:
- la réalisation d'au moins un évidement traversant l'épaisseur du troisième substrat et débouchant sur le premier substrat ; et  - Making at least one recess passing through the thickness of the third substrate and opening on the first substrate; and
- le dépôt d'un point de contact électrique dans ledit évidement.  depositing an electrical contact point in said recess.
De préférence, le milieu dans lequel sont enfermés la poutre de mesure et le corps actif contient du vide, de manière à limiter toute dégradation de la résolution du capteur. Preferably, 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.
De préférence, l'ensemble des scellements du procédé de fabrication sont réalisés sous vide ou sous atmosphère contrôlée. Un scellement sous vide est préféré pour la réalisation d'un capteur inertiel muni de résonateur, et un scellement sous atmosphère contrôlée est préféré pour la réalisation d'un capteur inertiel muni de jauge de contrainte piézorésistive. Preferably, 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.
Par exemple, la poutre de mesure est en silicium monocristallin, avantageusement 5 dopés pour améliorer la sensibilité de la poutre piézorésistive. For example, the measuring beam is made of monocrystalline silicon, advantageously doped to improve the sensitivity of the piezoresistive beam.
La masse d'épreuve peut également être en silicium monocristallin. The test mass may also be monocrystalline silicon.
Avantageusement, les premier et deuxième substrats sont de type SOI. Advantageously, the first and second substrates are of the SOI type.
10  10
L'invention a également pour objet un capteur inertiel comprenant au moins une poutre de mesure et un corps actif formé d'un corps d'épreuve et de lames déformables, ledit corps actif étant maintenu en suspension à l'intérieur d'une enceinte hermétique via ses lames, et la poutre de mesure reliant une partie du corps d'épreuve à une paroi interne 15 de ladite enceinte, ladite poutre de mesure présentant une épaisseur inférieure à celle du corps d'épreuve.  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.
Brève description des dessins Brief description of the drawings
20 D'autres caractéristiques et avantages de l'invention ressortiront clairement de la description qui en est faite ci-après, à titre indicatif et nullement limitatif, en référence aux figures annexées, dans lesquelles les figures 1 à 15 sont des vues schématiques illustrant les étapes du procédé de fabrication d'un capteur inertiel selon un mode de réalisation de l'invention. Other characteristics and advantages of the invention will emerge clearly from the description which is given below, by way of indication and in no way limiting, with reference to the appended figures, in which 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.
25  25
Exposé détaillé d'un mode de réalisation particulier  Detailed presentation of a particular embodiment
En référence à la figure 15, un capteur inertiel de type piézorésistif ou résonant selon un mode de réalisation de l'invention comprend notamment des poutres de mesure 30 23 de type piézorésistif ou résonateur et un corps actif formé d'un corps d'épreuve 13 mobile et de lames déformables 14. Le corps d'épreuve 13 est maintenue en suspension à l'intérieur d'une enceinte 30, 40 hermétique, les poutres de mesure 23 reliant les lames déformables à la paroi interne de l'enceinte. Ces poutres de mesure 23 présentent notamment une épaisseur inférieure à celle du corps d'épreuve 13. Ainsi, dans le cas d'une poutre de mesure 23 de type résonateur, la déflection du corps d'épreuve 13 engendre une variation de la fréquence du résonateur, et dans le cas d'une poutre de mesure 23 de type jauge de contrainte piézorésistive, la déflection du corps d'épreuve 13 induit la variation de la résistance électrique de la jauge, cette variation pouvant être récupérée par l'intermédiaire de plot électrique disposé à l'intérieur d'évidements. With reference to FIG. 15, an inertial sensor of the piezoresistive or resonant type according to one embodiment of the invention 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. Thus, in the case of a measuring beam 23 of the resonator type, 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.
Le procédé de fabrication d'un tel capteur est décrit ci-après en référence aux figures 1 à 15. A partir d'un premier substrat 1 (figure 1) qui peut être une tranche de matériau de type SOI (acronyme anglo-saxon pour « silicium On Insulator ») comprenant une première couche active 10 d'une première épaisseur el s par exemple de l'ordre de ΙΟμιη à ΙΟΟμιη, et une couche non active constituée d'une couche d'isolant 11 (par exemple une couche d'oxyde) et une couche support 12 (ou bulk), on réalise une gravure dans cette première couche active 10. Cette gravure (figure 2), par exemple de type DRIE (pour « deep reactive ion etching » en anglais ou « gravure profonde par ions réactifs » en français), consiste à former le corps d'épreuve 13 et les lames déformables 14 dans cette première couche active 10. En d'autres termes, la première couche active comprend la le corps d'épreuve 13, les lames déformables 14 et un cadre 15. The method of manufacturing such a sensor is described below with reference to FIGS. 1 to 15. From a first substrate 1 (FIG. 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 ΙΟμιη to ΙΟΟμιη, 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. 2), for example of the DRIE type (for "deep reactive ion etching" in English or "deep etching" by reactive ions "in French), consists in forming the test body 13 and the deformable blades 14 in this first active layer 10. In other words, the first active layer comprises the test body 13, the blades deformable 14 and a frame 15.
A partir d'un deuxième substrat 2 (figure 3) qui peut également être une tranche de matériau de type SOI comprenant une deuxième couche active 20 d'une deuxième épaisseur e2, par exemple de l'ordre de lOOnm à Ι μιη, et une couche non active constituée d'une couche d'isolant 21 et une couche support 22, on réalise une gravure dans cette première couche active 20. Cette gravure (figure 4), par exemple une photolithographie, consiste à former les poutres de mesure 23 dans cette deuxième couche active 20. From a second substrate 2 (FIG. 3) 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 Ι μιη, 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.
Les premier et deuxième couches actives 10, 20 sont ensuite scellées entre de manière à réaliser un scellement mécanique ainsi qu'un contact électrique entre les lames déformables et les poutres de mesure (figures 5 et 6). Dans une autre configuration (non représentée sur les figures), les poutres de mesure pourront être positionnées entre le corps d'épreuve 13 et le cadre 15. Et, bien entendu, il est possible de réaliser ce contact électrique indépendamment du scellement mécanique entre les deux couches actives 10, 20. Afin de libérer le corps actif et de réaliser son encapsulation, la couche non active, à savoir la couche isolante 11 et la couche support 12, du premier substrat est éliminée (figure 7). En d'autres termes, le corps d'épreuve 13 se retrouve en suspension et est maintenu au deuxième substrat 2 par l'intermédiaire des poutres de mesure 23. 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). In another configuration (not shown in the figures), 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. In order to release the active body and to realize its encapsulation, 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 partir d'un troisième substrat 3 (figure 8) comprenant notamment une couche d'isolant 31 (par exemple une couche d'oxyde) et une couche support 32 (ou bulk), on réalise une première cavité 30 permettant de contenir le corps actif, par exemple par gravure de type DRIE. Par exemple, cette première cavité 30 est réalisée dans la couche d'isolant et une portion de la couche support, comme illustré sur la figure 8. From a third substrate 3 (FIG. 8) comprising in particular an insulating layer 31 (for example an oxide layer) and a support layer 32 (or bulk), a first cavity 30 is made to contain the body. active, for example by DRIE type engraving. For example, this first cavity 30 is made in the insulating layer and a portion of the support layer, as illustrated in FIG. 8.
Ce troisième substrat 3 est ensuite scellé (figures 9 et 10) à la couche active du premier substrat 1 de sorte que le corps actif se retrouve à l'intérieur de cette première cavité 30. En d'autres termes, la surface libre de la couche isolante 31 du troisième substrat 3 est scellée à la surface libre du cadre 15 de la première couche active. 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. In other words, 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.
De même, les couches non actives, à savoir la couche isolante 21 et la couche support 22, du deuxième substrat 2 sont éliminées (figure 11). A partir d'un quatrième substrat 4 (figure 12) comprenant notamment une couche d'isolant 41 (par exemple une couche d'oxyde) et une couche support 42 (ou bulk), on réalise également une deuxième cavité 40, par exemple par gravure de type DRIE. Par exemple, cette deuxième cavité 30 est réalisée dans la couche d'isolant et une portion de la couche support, comme illustré sur la figure 12. Likewise, the non-active layers, namely the insulating layer 21 and the support layer 22, of the second substrate 2 are eliminated (FIG. 11). From a fourth substrate 4 (FIG. 12) comprising in particular an insulator layer 41 (for example an oxide layer) and a support layer 42 (or bulk), a second cavity 40 is also produced, for example by DRIE type engraving. For example, this second cavity 30 is made in the insulating layer and a portion of the support layer, as illustrated in FIG.
Ce quatrième substrat 4 est ensuite scellé (figures 12 et 13) à la couche active du deuxième substrat 2 de sorte que le corps actif et les poutres de mesure se retrouvent encapsulés à l'intérieur de l'enceinte hermétique formé par les première et deuxième cavités 30, 40. 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.
Des évidements traversant l'épaisseur du troisième substrat 3 et débouchant au niveau du cadre 15 du premier substrat 1 peuvent également être réalisés (figure 14). Le dépôt d'un point de contact électrique 6 dans ces évidements permet de récupérer le signal électrique généré lors de la déflection du corps d'épreuve 13. Ainsi, le procédé de fabrication de l'invention permet notamment de réaliser des capteurs inertiels munis notamment de corps d'épreuve de masse plus importante combiné à des poutres de mesure de type jauges de contrainte ou résonateurs d'épaisseur très faible, sans altération de la sensibilité de l'ensemble. En d'autres termes, la solution de l'invention permet d'optimiser les dimensions du corps d'épreuve et des poutres de mesure de manière à améliorer les performances du capteur. Il est donc possible d'obtenir à la fois un corps d'épreuve de masse élevée pour induire une contrainte élevée sur les poutres de mesure, et des poutres de mesure de très faible épaisseur pour une meilleure sensibilité de détection. 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. Thus, 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. In other words, 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.

Claims

REVENDICATIONS
1. Procédé de fabrication d'un capteur inertiel caractérisé en ce qu'il comprend au moins : 1. A method of manufacturing an inertial sensor characterized in that it comprises at least:
- la réalisation d'au moins un corps actif formé d'un corps d'épreuve (13) et de lames déformables (14), par gravure d'une première couche active (10) d'un premier substrat (1), ladite première couche active (10) présentant une première épaisseur (ei) ;  - The production of at least one active body formed of a test body (13) and deformable blades (14), by etching a first active layer (10) of a first substrate (1), said first active layer (10) having a first thickness (ei);
- la réalisation d'au moins une poutre de mesure (23) par gravure d'une deuxième couche active (20) d'un deuxième substrat (2), ladite deuxième couche active the embodiment of at least one measuring beam (23) by etching a second active layer (20) of a second substrate (2), said second active layer
(20) présentant une deuxième épaisseur (e2) inférieure à ladite première épaisseur (ei) ; (20) having a second thickness (e 2 ) smaller than said first thickness (ei);
- le scellement de la première couche active (10) avec la deuxième couche active (20) ;  - sealing the first active layer (10) with the second active layer (20);
- l'élimination des couches non actives (11, 12) du premier substrat (1) ;  the elimination of the non-active layers (11, 12) of the first substrate (1);
- la réalisation d'une première cavité (30) par gravure d'un troisième substrat (30) ;  - producing a first cavity (30) by etching a third substrate (30);
- le scellement du troisième substrat (3) avec la couche active du premier substrat (1), le corps actif étant disposé à l'intérieur de la première cavité (30) ; - l'élimination des couches non actives (21, 22) du deuxième substrat (2) ;  - Sealing the third substrate (3) with the active layer of the first substrate (1), the active body being disposed within the first cavity (30); eliminating the non-active layers (21, 22) of the second substrate (2);
- la réalisation d'une deuxième cavité (40) par gravure d'un quatrième substrat (4) ; et  - Making a second cavity (40) by etching a fourth substrate (4); and
- le scellement du quatrième substrat (4) avec la couche active du deuxième substrat (2).  - Sealing the fourth substrate (4) with the active layer of the second substrate (2).
2. Procédé selon la revendication 1, caractérisé en ce qu'il comprend en outre la réalisation d'un contact électrique entre le corps actif et la poutre de mesure (23). 2. Method according to claim 1, characterized in that it further comprises the realization of an electrical contact between the active body and the measuring beam (23).
3. Procédé selon la revendication 2, caractérisé en ce que ledit contact électrique est réalisé lors du scellement de la première couche active avec la deuxième couche active, ce scellement induisant à la fois un contact mécanique et un contact électrique entre la poutre et le corps actif. 3. Method according to claim 2, characterized in that said electrical contact is made during the sealing of the first active layer with the second active layer, this seal inducing both a mechanical contact and an electrical contact between the beam and the body. active.
4. Procédé selon l'une des revendications 1 à 3, caractérisé en ce que la poutre de mesure (23) est en matériau piézorésistif formant jauge de contrainte. 4. Method according to one of claims 1 to 3, characterized in that the measuring beam (23) is a piezoresistive strain gauge material.
5. Procédé selon l'une des revendications 1 à 3, caractérisé en ce que la poutre de mesure (23) est un résonateur mécanique. 5. Method according to one of claims 1 to 3, characterized in that the measuring beam (23) is a mechanical resonator.
6. Procédé selon l'une quelconque des revendications 1 à 5, caractérisé en ce que le ratio de la première épaisseur (ei) sur la deuxième épaisseur (e2) est supérieur ou égal à 5. 6. Method according to any one of claims 1 to 5, characterized in that the ratio of the first thickness (ei) on the second thickness (e 2 ) is greater than or equal to 5.
7. Procédé selon l'une quelconque des revendications 1 à 6, caractérisé en ce qu'il comprend en outre : 7. Method according to any one of claims 1 to 6, characterized in that it further comprises:
- la réalisation d'au moins un évidement (5) traversant l'épaisseur du troisième substrat (3) et débouchant sur le premier substrat (1) ; et  - Making at least one recess (5) passing through the thickness of the third substrate (3) and opening on the first substrate (1); and
- le dépôt d'un point de contact électrique (6) dans ledit évidement (5).  depositing an electric contact point (6) in said recess (5).
8. Procédé selon l'une quelconque des revendications 1 à 7, caractérisé en ce que le milieu dans lequel sont enfermés la poutre de mesure et le corps actif contient du vide. 8. Method according to any one of claims 1 to 7, characterized in that the medium in which are enclosed the measuring beam and the active body contains vacuum.
9. Procédé selon l'une quelconque des revendications 1 à 8, caractérisé en ce que l'ensemble des scellements du procédé de fabrication sont réalisés sous vide ou sous atmosphère contrôlée. 9. Process according to any one of claims 1 to 8, characterized in that all the seals of the manufacturing process are carried out under vacuum or in a controlled atmosphere.
10. Procédé selon l'une quelconque des revendications 1 à 9, caractérisé en ce que la poutre de mesure et la masse d'épreuve sont en silicium monocristallin. 10. Method according to any one of claims 1 to 9, characterized in that the measuring beam and the test mass are monocrystalline silicon.
11. Procédé selon la revendication 10, caractérisé en ce que la poutre de mesure est en silicium monocristallin dopés. 11. The method of claim 10, characterized in that the measuring beam is doped monocrystalline silicon.
12. Procédé selon l'une quelconque des revendications 1 à 11, caractérisé en ce que les premier et deuxième substrats (1, 2) sont de type SOI. 12. Method according to any one of claims 1 to 11, characterized in that the first and second substrates (1, 2) are SOI type.
EP12707855.8A 2011-03-03 2012-02-02 Method of fabricating an inertial sensor Withdrawn EP2681568A1 (en)

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FR1151746A FR2972263B1 (en) 2011-03-03 2011-03-03 INERTIAL SENSOR AND METHOD FOR MANUFACTURING THE SAME
PCT/FR2012/050236 WO2012117177A1 (en) 2011-03-03 2012-02-02 Method of fabricating an inertial sensor

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CN103518138A (en) 2014-01-15
FR2972263A1 (en) 2012-09-07

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