Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H37/00—Thermally-actuated switches
  • H01H37/02—Details
  • H01H37/32—Thermally-sensitive members
  • H01H37/58—Thermally-sensitive members actuated due to thermally controlled change of magnetic permeability
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F7/00—Magnets
  • H01F7/06—Electromagnets; Actuators including electromagnets
  • H01F7/08—Electromagnets; Actuators including electromagnets with armatures
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H50/00—Details of electromagnetic relays
  • H01H50/005—Details of electromagnetic relays using micromechanics
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F7/00—Magnets
  • H01F7/06—Electromagnets; Actuators including electromagnets
  • H01F2007/068—Electromagnets; Actuators including electromagnets using printed circuit coils
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H1/00—Contacts
  • H01H1/0036—Switches making use of microelectromechanical systems [MEMS]
  • H01H2001/0042—Bistable switches, i.e. having two stable positions requiring only actuating energy for switching between them, e.g. with snap membrane or by permanent magnet
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H50/00—Details of electromagnetic relays
  • H01H50/005—Details of electromagnetic relays using micromechanics
  • H01H2050/007—Relays of the polarised type, e.g. the MEMS relay beam having a preferential magnetisation direction
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H51/00—Electromagnetic relays
  • H01H51/22—Polarised relays
  • H01H51/2209—Polarised relays with rectilinearly movable armature
  • H01H2051/2218—Polarised relays with rectilinearly movable armature having at least one movable permanent magnet
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H51/00—Electromagnetic relays
  • H01H51/22—Polarised relays
  • H01H51/2209—Polarised relays with rectilinearly movable armature

Definitions

• the present invention relates to a magnetic actuator with a moving magnet and in particular a microactuator which can be produced by the techniques of microtechnology.
• This actuator when it has several stable positions finds its application in the production of microrelays or electrical microswitches controlling the opening or closing of an electrical contact possibly taken from several, of microrelays or microswitches controlling the passage, the shutter, the switching or switching of a light beam, of microvalves controlling the passage, the shutter or the switching of a fluid, of micropumps controlling the pumping of a fluid.
• This actuator can be controlled so as to be able to take a multitude of successive positions with nanometric precision according to 5 degrees of freedom.
• Known magnetic actuators have a fixed magnetic part, a mobile magnetic part which is mechanically connected to the fixed magnetic part.
• An electric circuit makes it possible to excite the mobile magnetic part to make it take up a working position by making it move relative to the fixed magnetic part. In the absence of excitation, the mobile magnetic part is in a rest position.
• the driving forces of the moving magnetic part are due to the magnetic field created by at least one coil.
• a microbool creates a much weaker force than a coil of the same shape but larger.
• the performance of such microactuators therefore remains poor.
• the mass forces they are capable of providing are small relative to their size.
• actuators must be electrically powered so that they remain in a working position, in the absence of power they return to a rest position.
• the object of the present invention is precisely to propose a magnetic actuator which does not have all of these drawbacks.
• the actuator of the present invention is particularly suitable for an embodiment in microtechnologies. It has a high movement speed, an ability to exert significant mass forces and large displacements relative to its size. In stable position, position which can correspond to a working position, the electric consumption of this actuator is zero.
• the actuator of the invention comprises a fixed magnetic part and a mobile magnetic part formed by a magnet which, when it is not glued to the fixed magnetic part, is levitated without contact. When it moves and is attracted by the fixed magnetic part, it is completely guided magnetically. There is no mechanical guidance.
• the magnetic actuator according to the invention comprises a fixed magnetic part which cooperates magnetically with a mobile magnetic part and means for triggering the displacement of the mobile magnetic part.
• the mobile magnetic part comprises at least one magnet and the fixed magnetic part has at least two areas of attraction on which the mobile magnetic part is likely to come to stick, the mobile magnetic part being in levitation when it is not glued on one of the attraction zones, its movement being done by magnetic guidance.
• the fixed magnetic part can be made of a material chosen from the group of soft magnetic materials, hard magnetic materials, hysteresis materials, superconductive materials, diamagnetic materials, these materials being taken alone or in combination.
• the means for triggering the displacement of the movable magnetic part are means magnetic, they can be means of heating the fixed magnetic part.
• the material of the fixed magnetic part can have a Curie point lower than that of the magnet of the mobile magnetic part, so the heating does not disturb the properties of the magnet. If this is not the case, it is necessary to take into account the thermal coupling, the magnet can be thermally insulated from the mobile magnetic part from the fixed magnetic part.
• the means for triggering the displacement of the mobile magnetic part create a magnetic field in the vicinity of the mobile magnetic part.
• the means for triggering the displacement of the mobile magnetic part can be produced by at least one electrical conductor.
• the actuator may include means for controlling the current to be circulated in the conductor at the position of the movable magnetic part so that it can assume a plurality of stable positions in levitation. It can then operate in positioner.
• the means for triggering the displacement of the mobile magnetic part thus serve to keep the mobile magnetic part stable in levitation.
• the conductor can surround the fixed magnetic part.
• the conductor can take the form of a substantially planar winding.
• the fixed and mobile magnetic parts can also be substantially planar, they can be arranged substantially in the same plane.
• the conductor on the one hand and the fixed and mobile magnetic parts on the other hand can then be. arranged in substantially parallel planes.
• the fixed magnetic part can be a single element which surrounds the mobile magnetic part, the latter then being able to assume several stable positions inside the fixed magnetic part. It can thus have at least four degrees of freedom.
• the fixed magnetic part can be formed of several elements, the mobile magnetic part coming to stick on one of the elements of the fixed magnetic part or on another. If the fixed magnetic part comprises several planar elements oriented in different planes, the mobile magnetic part can then take the orientation of the element on which it is glued.
• the magnetization of the fixed magnetic part and that of the movable magnetic part can be directed in the same direction or on the contrary be directed in opposite directions.
• the means for triggering the movement of the movable magnetic part can trigger a rotation movement.
• the fixed magnetic part can comprise, at at least one attraction zone, a pair of electrical contacts and the mobile magnetic part at least one electrical contact, the mobile magnetic part coming to connect the two contacts of the pair when it comes stick to the area of attraction.
• the mobile magnetic part can comprise a reflecting zone intended to reflect a light ray, the actuator can then be used as an optical relay or switch, as a scanner for example according to the displacement which the mobile magnetic part can make.
• Such an actuator can be produced on a non-magnetic substrate, the means for triggering the movement of the mobile magnetic part being embedded in the substrate.
• An array of actuators can be produced with a plurality of magnetic actuators thus defined, these magnetic actuators being grouped together on the same support.
• the present invention also relates to a device which uses at least one magnetic actuator thus defined. It can be for example a relay, a switch, a pump, a valve, a positioner, an optical scanner.
• the present invention also relates to a method for producing a magnetic actuator. It includes the following steps:
• It also includes a step of magnetization of the magnet of the mobile magnetic part and possibly of the fixed magnetic part before the release of the mobile magnetic part.
• the etching step of the dielectric layer of the first substrate also aims to produce at least one access opening to at least one electrical contact for supplying the conductor.
• a step of producing at least one electrical contact for supplying the conductor can take place on the second substrate, after the conductor has been deposited and before the two substrates are assembled.
• a step of depositing a dielectric material on the surface of the second substrate can intervene before assembling the two substrates to protect the conductor.
• the two substrates can be solid semiconductor substrates or SOI type substrates.
• FIG. 1A to 1D show an example of a switch according to the invention in different positions that its movable magnetic part can take;
• FIGS. 3A to 3C show different configurations of the means for triggering the movement of the movable magnetic part of an actuator according to the invention
• FIG. 4 shows an example of an actuator according to the invention produced on a non-magnetic substrate
• FIG. 5 shows an example of an actuator according to the invention produced on a non-magnetic substrate
• FIG. 6 shows an example of an actuator according to the invention which can be controlled by five degrees of freedom
• FIG. 7 shows an example of an actuator according to the invention, the fixed magnetic part of which is formed by four elements
• FIG. 8 shows an example of an actuator according to the invention, the fixed magnetic part of which comprises a single element which surrounds the mobile magnetic part
• FIGS. 10A to 101 show different stages in the production of the fixed and mobile magnetic parts of an actuator according to the invention, on a solid semiconductor substrate;
• - Figures 11A to 111 show different stages in the production of the fixed and mobile magnetic parts of an actuator according to the invention, on a SOI type semiconductor substrate;
• - Figures 12A to 12G show different stages of production of the means for triggering the displacement of the mobile magnetic part of an actuator according to the invention, on a semiconductor substrate;
• - Figures 13A and 13B show the steps of assembling and finishing the substrates obtained in Figures 101 and 12G;
• Figures 14A and 14B show the steps of assembling and finishing the substrates obtained in Figures 111 and 12G; DETAILED PRESENTATION OF PARTICULAR EMBODIMENTS
• FIGS. 1A to 1D schematically illustrate an actuator according to the invention and different positions that its mobile magnetic part can take.
• the fixed magnetic part 3 may include one or more elements based on permanent magnets 3-1 and / or magnetic material. In FIGS. 1, it is assumed that the fixed magnetic part 3 comprises two elements 3-1 which are permanent magnets.
• the assembly of mobile magnetic part and fixed part is supported by a non-magnetic support (not shown in Figures 1). During the production of such an actuator in microtechnologies, it can be produced on or in a substrate as will be seen later.
• the fixed magnetic part 3 and the mobile magnetic part 1 cooperate magnetically with one another.
• the fixed magnetic part 3 is configured so as to present at least two attraction zones 3-2 which separately and naturally attract the mobile magnetic part 1.
• the movable magnetic part 1 is limited to a single permanent magnet 1-1 in the form of a parallelepiped plate. It is located between the two permanent magnets 3-1 of the fixed magnetic part 3 which also have the shape of a parallelepiped plate.
• the areas of attraction 3-2 are lateral faces of the fixed magnets 3-1.
• the movable magnet 1-1 can be bonded either on one of the faces 3-2 of the fixed magnet on the right or on one of the faces 3-2 of the fixed magnet on the left, these two faces being opposite.
• the three magnets 1-1 and 3-1 are aligned and extend substantially in the x, y plane.
• the mobile magnetic part 1 has no permanent mechanical connection with the fixed part 2.
• the mobile magnetic part 1 is not glued to one of the attraction zones 3-2, it is free, levitating without contact, thanks to the interactions it has with the fixed magnetic part 3.
• it is magnetically guided.
• the means 4 for triggering the displacement of the mobile magnetic part 1 have the function of modifying the forces which interact on the mobile magnetic part 1 and therefore of modifying the balance of the whole mobile magnetic part 1-fixed magnetic part 3. They initiate the displacement of the mobile magnetic part 1 but then the displacement is due to the interactions between the fixed magnetic part 3 and the mobile magnetic part 1.
• the means 4 for triggering the displacement are magnetic means. They can act according to several different physical principles. They can, by a localized increase in temperature, modify the magnetic characteristics of the fixed magnetic part 3 at the level of the attraction zone 3-2 on which the mobile magnetic part 1 is stuck. According to a variant, they can create a magnetic field at the mobile magnetic part, this magnetic field modifies the magnetic characteristics of the assembly and sets in motion the mobile magnetic part.
• each of the magnets 3-1 of the fixed magnetic part 3 is provided with a heating resistor R.
• This resistor R can be deposited on one of the faces of the magnets 3-1 of the fixed magnetic part. It can be made of copper, silver, gold, aluminum for example. Once the movement is initiated, the heating can be stopped and there is no more energy required. When the mobile magnetic part is glued to the fixed magnetic part, the energy consumption is also zero.
• a light beam for example a laser beam which would irradiate the fixed magnetic part at the level of the zone whose magnetic properties we want to modify.
• the fixed magnetic part 3 can then be • made of a material whose Curie point is low, for example less than or equal to 100 ° C. Its magnetic properties are likely to disappear with an increase in temperature.
• the material used is magnetic below 100 ° C and non-magnetic above 100 ° C.
• the temperature reached by the fixed magnetic part during heating must not disturb the behavior of the magnet of the mobile magnetic part which can then have a higher Curie point.
• the Curie point of the magnet of the mobile magnetic part may not be less than that of the fixed magnetic part, but in this case the magnet of the mobile magnetic part will have a weak thermal coupling with the fixed magnetic part so not to heat when the fixed magnetic part heats up.
• the mobile magnet 1-1 is glued to the fixed magnet 3-1 on the left. Once it is in such a stable position, the magnetic forces are so great that even a very violent shock could not take it off.
• mobile and fixed magnets whose dimensions are 50 ⁇ m x 50 ⁇ m x 10 ⁇ m, with a magnetization of 1 Tesla, it would take a shock far greater than 1000G to be able to take it off and move it by 1 .mu.m.
• the fixed magnetic part 3 and the mobile magnetic part 1 can be provided with electrical contacts as illustrated in FIGS. 2A, 2B, 2C, 2D.
• At least one attraction zone 3-2 of the fixed magnetic part 3 is provided with a pair of electrical contacts C1, C2, these contacts extend beyond the attraction zone 3-2 to be accessible.
• the mobile magnetic part 1 is provided with at least one electrical contact C. When the mobile magnetic part 1 is bonded to the attraction area 3-2, its contact C electrically connects the two contacts C1, C2 of the pair. An electrical relay can thus be produced.
• the two fixed magnets 3-1 are provided with contacts C1, C2 and the movable magnet 1-1 has two of its faces 1-2 each provided with a contact C (the contact C on its face 1-2 which comes into contact with the fixed magnet 3-1 on the left is not visible in FIGS. 2A, 2B).
• a device 20, for example of the electrical switch type, has thus been produced, comprising at least one magnetic actuator according to the invention.
• the fixed magnetic part instead of being formed by two elements 3-1 each provided with a pair of electrical contacts is formed by two pairs of elements 3 -la, 3-lb. The elements 3-la, 3-lb of a pair are side by side but disjoint.
• Each of the elements 3-la, 3-lb of the pair is provided with an electrical contact C1, C2 respectively. There is no change for the mobile magnetic part 1.
• the magnetization of the fixed and mobile magnetic parts is directed in the same direction along the x axis.
• FIG. 3A The only difference compared to the previous figures is at the level of the means 4 for triggering the displacement of the mobile magnetic part 1.
• Their principle is now to create a magnetic field in the vicinity of the mobile magnetic part.
• These means 4 can be produced by at least one conductor 4-1 intended to be traversed by an electric current to generate the magnetic field.
• the conductor 4-1 can have a large number of configurations, for example it can take the form of an open loop or of a winding with one or more turns. In the following description, when the term winding has been used, it could just as easily be a conductor taking an appropriate shape to generate the magnetic field without being a winding.
• FIG. 3A there is a single substantially flat coil 4-1 extending in an x, y plane.
• the winding has one or more turns wound around an empty central part, the fixed magnetic part 3 is in the vicinity of the turns and the mobile magnetic part 1, when it is levitated is located near the central part of the coil 4-1.
• a current pulse travels through this coil 4-1, a magnetic field is created which has the effect of modifying the magnetic balance of the fixed magnetic 3 and moving parts 1 and triggering the displacement of the moving magnetic part 1 by one stable position toward another.
• the impulse required for switching from one position to another may be less than 5 ⁇ s for the actuator whose characteristics have been given above.
• the rest of the actuator does not consume energy.
• An actuator which would switch a thousand times per second would consume around 2mW which is very low. With very good quality magnetic materials, this consumption could be reduced.
• the fixed magnetic part 3 can rest on the coil 4-1 while the mobile magnetic part 1 is levitated above. Appropriate isolations are inserted between the fixed magnetic part and the winding.
• the direction of movement is conditioned by the direction of the current flowing in the winding 4-1.
• the mobile magnet 3-1 will be attracted to the fixed magnet 3-1 on the left.
• the means 4 for triggering the displacement of the mobile magnetic part 1 are now produced by two conductors 40 which each surround one of the elements of the fixed magnetic part. They take the form of tubular coils.
• soft magnetic materials For the fixed magnetic part, soft magnetic materials, hard magnetic materials, magnetic materials with hysteresis, diamagnetic materials, superconductive materials may be used, these materials being taken alone or in combination.
• Soft magnetic materials such as iron, nickel, iron-nickel alloys, iron-cobalt, iron-silicon, magnetize according to an inductive field to which they are subjected.
• Hard magnetic materials correspond to magnets such as ferrite magnets, samarium-cobalt magnets, neodymium-iron-boron magnets, platinum-cobalt magnets.
• Hysteresis materials for example of the aluminum-nickel-cobalt (AlNiCo) type, have properties which lie between those of soft magnetic materials and those of hard magnetic materials. They are sensitive to the magnetic field in which they are found.
• diamagnetic materials such as bismuth or pyrolitic graphite
• the superconductive materials could be alloys nobium-titanium (NbTi), yttrium-barium-copper-oxygen (YBaCuO) for example.
• the magnet of the mobile magnetic part can be produced, for example, from ferrite, samarium-cobalt, neodymium-iron-boron, platinum-cobalt.
• the low Curie point magnetic materials which are suitable for producing the fixed magnetic part are for example the manganese-arsenic alloys
• MnAs cobalt-manganese-phosphorus
• CoMnP cobalt-manganese-phosphorus
• ErFeB erbium-fer-boron
• the actuator according to the invention is transformed into a positioner.
• the mobile magnetic part 1 is capable of assuming a plurality of intermediate positions between the two extreme stable positions which correspond to the cases where it is glued to the fixed magnetic part 3.
• the current flowing in the conductor 4-1 can be controlled as a function of the position of the mobile magnetic part 1.
• the means for triggering the displacement of the mobile magnetic part then serve to keep the mobile magnetic part in a position stable while it is levitating.
• a device 5 can be used which detects the position of the mobile magnetic part 1.
• the signal delivered by this device 5 is compared to a setpoint K in a comparator 6 and the result of this comparison is used to control a power source 7 provided to supply the conductor 4- 1.
• the device 5 which detects the position of the mobile magnetic part 1 can comprise, associated with each of the fixed magnetic elements 3-1, a capacitive position sensor 5-1 which measures the capacity existing between the fixed magnetic element 3-1 with which it is associated with and the mobile magnetic part 1.
• a differentiating device 5-2 receives the signals from the two capacitive position sensors 5-1, makes the difference and delivers a signal representative of the position of the mobile magnetic part 1.
• the magnets whether they belong to the fixed magnetic part or to the mobile magnetic part, can ultimately be produced in a simple and in a single operation because they are all magnetized in the same direction.
• FIG. 4 shows a variant of an actuator according to the invention ' produced on a substrate 9, for example a silicon wafer. It can have a thickness of 300 ⁇ m if the mobile and fixed magnetic parts have the dimensions mentioned above
• the fixed magnetic part 3 is attached to the surface of the substrate 9, the mobile magnetic part 1, when it is not glued to the fixed magnetic part 3, floats above the substrate 9, in the magnetic field created by the fixed magnetic part 3, as for the means 4 for triggering the displacement of the mobile magnetic part 1, they are embedded in the substrate 9.
• the mobile 1 and fixed 3 magnetic parts can be produced in a similar manner to those of FIGS. 1 to 3, but other configurations are possible.
• the fixed magnetic part could be massive.
• it could be made from a ferromagnetic material.
• the magnetization of the fixed and mobile magnetic parts now follow the z axis instead of following the x axis.
• This magnetization follows the thickness of the mobile and fixed magnetic parts which have the form of plates. But these magnetizations are of opposite direction.
• the two plates of magnet 3-1 or of ferromagnetic material of the fixed magnetic part 3 have a magnetization in the same direction and the magnetization of the magnet 1-1 of the movable magnetic part 1 is in the opposite direction. If the plates 3-1 of the fixed magnetic part 3 are ferromagnetic, their magnetization depends on that of the magnet 1-1 of the mobile magnetic part 1, it is naturally opposite to that of the mobile magnetic part 1.
• the means 4 for triggering the displacement of the mobile magnetic part 1 are modified in an appropriate manner in order to be able to be effective.
• they are formed from two substantially planar coils 410, 411, placed side by side, in the same plane, along the x axis.
• Each of these windings 410, 411 is comparable to that shown in FIG. 3A. But now the movable magnetic part 1 sits astride the turns of each of the coils 410, 411. '
• the two windings 410, 411 can be supplied in series, in parallel or independently of one another. No power source has been shown so as not to overload the figure.
• the creation of an asymmetry in the currents flowing through the two windings 410, 411 can make it possible to drive the mobile magnetic part 1 in rotation about the y axis when it is levitated.
• a portion 10 of the movable magnetic part 1 reflective and by adjusting the current in the coils 410, 411, it is possible to control the angle of reflection of a light beam F incident on the reflecting face.
• this portion 10 is located on the upper main face of the mobile magnetic part 1. It is possible to thus make an optical scanner.
• the portion 10 is located on an edge of the mobile magnetic part 1 or on its lower main face if the substrate 9 allows it. The latter could be provided with an opening or allow the light beam F to pass if it is made of glass for example.
• the mobile magnetic part 1 has a resonant frequency and by exploiting this frequency, it is possible to produce an optical scanner with very low power consumption. This supply corresponds to that injected into the windings to obtain the rotation of the mobile magnetic part when it is in levitation and therefore the desired scanning of the light beam F. At resonance, it is necessary to supply very little energy to the system for make it oscillate. In theory, one impulse would be enough to make it oscillate indefinitely.
• Figure 5 illustrates a variant of the previous configuration.
• the two elements 3-1 of the fixed magnetic part 3 instead of being in the same plane, have an asymmetry of shape or position with respect to the mobile magnetic part 1. In this example, they are now inclined the one over the other. In Figure 5, they are tilted around the x axis.
• the mobile magnetic part 1 coming to stick on one of the elements 3-1 of the fixed magnetic part takes the same inclination as it. If the movable magnetic part 1 is provided with a reflecting portion 10, a light ray F reflecting on this portion 10 will be deflected with a inclination which depends on that of the fixed magnetic element on which the mobile magnetic part is stuck. An optical switch is then produced.
• FIG. 6 is an actuator according to the invention which is deduced from the configuration of FIG. 4.
• the means 4 for triggering the displacement of the mobile magnetic part 1 comprise four coils 401, 402, 403, 404 planes, located in a same plane x, y and arranged in a matrix.
• the movable magnetic part overlaps a portion of turn of the four coils 401, 402, 403, 404 and each element 3-1 of the fixed magnetic portion 3 overlaps a portion of turn of two of the coils 401, 402, 403, 404.
• the mobile magnetic part 1 is similar to that of FIG. 6, the means 4 for triggering the displacement also with the exception of the fifth winding 405 which has been omitted, for the purpose of simplification but which could be present.
• the fixed magnetic means 3 which now include four fixed magnetic elements 31, 32, 33, 34 forming a cross with the movable magnetic part 1.
• Each of these elements 31, 32, 33, 34 of the part fixed magnetic 3 overlaps a turn portion of two coils respectively (401, 404), (401, 402), (402, 403), (403, 404).
• the mobile magnetic part 1 can then be controlled in the same directions as those of FIG. 6.
• the addition of the fifth winding could be envisaged to obtain a displacement in a direction perpendicular to the plane of the first windings 401, 402, 403, 404.
• the actuator can take four stable positions, the mobile magnetic part 1 can be stuck on each of the four fixed magnetic elements 31, 32, 33, 34.
• the fixed magnetic part 3 is formed of a single element 30 which surrounds the mobile magnetic part 1. The mobile magnetic part 1 can then take an infinity of stable positions when it sticks against the fixed magnetic element 30. It is then possible to obtain a positioner.
• the fixed magnetic part has been shown like a hollowed out square plate.
• Other shapes are of course conceivable, for example in a ring.
• the mobile magnetic part must have a shape compatible with that of the fixed magnetic part.
• a ring shape for the fixed magnetic part would correspond to a disc shape for the mobile magnetic part.
• FIGS. 9A, 9B A device with a plurality of actuators A according to the invention has been shown in FIGS. 9A, 9B.
• the different actuators A are arranged in a matrix M on the same support 9, at the crossroads between n line conductors il to i3 and m column conductors jl to j4 (n and m are integers, n and m may or may not be different).
• signals propagating on a sheet formed by the n line conductors 11 to .i3 can be switched to the m column conductors j1, j2, j3, j4.
• These signals can be electrical or optical signals depending on the nature of the actuators A. Due to the bistability of the actuators A of the matrix M, the latter can be programmed and keep its configuration without the need to power it electrically.
• actuators operate in positioners, such a matrix allows access to several memories mounted in parallel, each position of the positioner corresponding to a memory position of one of the memories.
• the actuators can be grouped into a particular matrix B as in FIG. 9B with a row conductor il and several column conductors jl to j4. By connecting a bus to the line conductor il, the signals it conveys can be directed to the different column conductors jl to j4 depending on the state of the different actuators A.
• microactuators have their mobile and fixed magnetic parts produced by magnets.
• the means for triggering the displacement of the mobile magnetic part. are made by windings.
• the advantage of this process is that it can be made to produce several at the same time on the same substrate.
• FIGS. 14A, 14B the microactuator is completely embedded in the substrate produced in two assembled parts.
• FIGS. 13A, 13B only the triggering means are embedded in the substrate also produced in two assembled parts, the mobile and fixed magnetic parts are placed on the substrate.
• the two parts are solid conventional semiconductor substrates while in FIGS. 14A, 14B, one of them is a solid conventional substrate while the other is an SOI substrate (acronym silicon on insulator, for silicon on insulator).
• SOI substrate acronym silicon on insulator, for silicon on insulator.
• Such a silicon substrate has a layer of insulating material 93-1, of silicon oxide, buried within the silicon. Its advantage is that when an etching operation is carried out, the layer of insulating material can serve as a stop layer.
• the micro magnets On a first substrate, either a conventional solid 91 made of semiconductor material, or of the SOI 93 type, the micro magnets will be produced (FIGS. 10A to 101 and 11A to 111).
• the displacement triggering means taking the form of one or more conductors can be arranged in winding (FIGS. 12A to 12G). In these figures 12A to 12G a solid substrate has been shown.
• FIG. 12B the position of the layer of insulating material of an SOI substrate is shown diagrammatically by dotted lines.
• Etching is carried out in the first substrate 91, 93 of the boxes 51 for the magnets.
• the etching can be a dry etching.
• the etching stops on the oxide layer 93-1. We remove the resin 03/012805
• a conductive bonding sub-layer 52 is deposited on the substrate 91, 93. In fact this variant is only found in FIG. 10B.
• FIG. 11B there are two bonding sub-layers 52-1, 52-2, the second 52-2 being inserted between the first 52-1 and the substrate 93. It allows good adhesion to the substrate 93 of the first underlay 52-1. It also allows protection of the mobile magnet 1-1, produced subsequently, against corrosion.
• the first sublayer may be gold and the second titanium. These two sublayers could be used in the example of FIG. 10B.
• the magnet deposition area is defined by photolithography.
• the resin layer used bears the reference 50-2.
• the magnets 3-1, 1-1 are deposited electrolytically.
• the material used can be cobalt-platinum ( Figures 10C, 11C).
• a conductive layer 53 is then deposited on the surface intended to make the electrical contacts Cl, C2, C on the magnets 3-1, 1-1.
• the geometry of the contacts Cl, C2, C is defined by photolithography.
• the resin has the reference 50-3
• the next step is a step of etching the conductive layer 53 to delimit the contacts C1, C2, C.
• the resin 50-3 is then removed.
• An insulating layer 54 is deposited on the surface, in Si0 for example, then a planarization step is carried out (FIGS. 10F, 11F).
• etching of a box 55 is carried out which must receive the conductor 4-1.
• the etching of the box 55 stops on the insulating layer.
• the depth of the box 55 corresponds to the thickness of the conductor 4-1.
• a conductive bonding sub-layer 56 is deposited on the surface (FIG. 12B). It can be made of copper for example. It is also possible to introduce a second sub-layer as described in FIG. 10B. It can be made of titanium for example.
• the conductor deposition area is defined by photolithography.
• the resin used bears the reference 50-6.
• the conductor 4-1 is deposited electrolytically, its ends referenced 45 are clearly visible (FIGS. 12C).
• the deposit can be copper.
• the resin 50-6 is removed, the conductive deposit is planarized.
• the conductive sub-layer 56 is etched on the surface to remove it (FIG. 12D).
• a conductive layer 57 is then deposited on the surface intended to make the supply contacts 47 of the conductor 4-1, these contacts 47 covering the ends 45 of the conductor 4-1.
• the geometry of the contacts 47 is defined by photolithography, the resin used for this bearing the reference 50-7 (FIG. 12E).
• the conductive layer 57 is then etched so as to remove it wherever it is not protected by resin 50-7.
• an insulating layer 59 is deposited on the surface. It can be made of silicon oxide Si0 2 . It will isolate the conductor 4-1 from the magnets 3-1, 1-1 during the assembly of the first substrate 91, 93 and the second substrate 92 (FIG. 12F).
• the first substrate 91, 93 will be totally or partially eliminated. It may be a mechanical thinning and / or a chemical attack.
• FIG. 13B the substrate 91 has been completely removed while in FIG. 14B, the elimination has stopped on the oxide layer 93-1 and the silicon of the substrate 93 which is below it remains in place.
• the magnets 3-1, 1-1 are then embedded in the substrate formed by the two assembled parts 92 and 93 while in FIG. 13B they are on the surface of the substrate 92.
• the actuator according to the invention if it occupies a volume greater than about 1 cubic centimeter, risk to be sensitive to the external environment such as vibrations and shocks. Its performance may not be optimal in such disturbed environments. By cons, against all expectations, with smaller dimensions its performance is greatly improved whatever the environment.
• the interaction between the fixed and mobile magnetic parts is favorable and does not degrade performance as in the case of a much larger actuator.

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• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Thermal Sciences (AREA)
• Micromachines (AREA)
• Reciprocating, Oscillating Or Vibrating Motors (AREA)
• Vehicle Body Suspensions (AREA)
• Magnetic Bearings And Hydrostatic Bearings (AREA)

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• 2001
  • 2001-07-27 FR FR0110081A patent/FR2828000B1/fr not_active Expired - Fee Related
• 2002
  • 2002-07-25 US US10/485,193 patent/US7106159B2/en not_active Expired - Fee Related
  • 2002-07-25 AT AT02772452T patent/ATE342572T1/de not_active IP Right Cessation
  • 2002-07-25 DE DE60215367T patent/DE60215367T2/de not_active Expired - Lifetime
  • 2002-07-25 EP EP02772452A patent/EP1428232B8/de not_active Expired - Lifetime
  • 2002-07-25 WO PCT/FR2002/002666 patent/WO2003012805A2/fr active IP Right Grant

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