EP1357571A1 - Système microélectromécanique et son procédé de fabrication - Google Patents

Système microélectromécanique et son procédé de fabrication Download PDF

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Publication number
EP1357571A1
EP1357571A1 EP02405334A EP02405334A EP1357571A1 EP 1357571 A1 EP1357571 A1 EP 1357571A1 EP 02405334 A EP02405334 A EP 02405334A EP 02405334 A EP02405334 A EP 02405334A EP 1357571 A1 EP1357571 A1 EP 1357571A1
Authority
EP
European Patent Office
Prior art keywords
micro
substrate
electromechanical system
switch
working position
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Withdrawn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
EP02405334A
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German (de)
English (en)
Inventor
Ralf Strümpler
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.)
ABB Research Ltd Switzerland
ABB Research Ltd Sweden
Original Assignee
ABB Research Ltd Switzerland
ABB Research Ltd Sweden
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 ABB Research Ltd Switzerland, ABB Research Ltd Sweden filed Critical ABB Research Ltd Switzerland
Priority to EP02405334A priority Critical patent/EP1357571A1/fr
Priority to EP02796487A priority patent/EP1468436B1/fr
Priority to US10/501,979 priority patent/US7109560B2/en
Priority to AU2002361920A priority patent/AU2002361920A1/en
Priority to PCT/CH2002/000722 priority patent/WO2003060940A1/fr
Priority to DE50204300T priority patent/DE50204300D1/de
Priority to AT02796487T priority patent/ATE304736T1/de
Publication of EP1357571A1 publication Critical patent/EP1357571A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H59/00—Electrostatic relays; Electro-adhesion relays
    • H01H59/0009—Electrostatic relays; Electro-adhesion relays making use of micromechanics
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H1/00—Contacts
    • H01H1/12—Contacts characterised by the manner in which co-operating contacts engage
    • H01H1/14—Contacts characterised by the manner in which co-operating contacts engage by abutting
    • H01H1/20—Bridging contacts
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H1/00—Contacts
    • H01H1/50—Means for increasing contact pressure, preventing vibration of contacts, holding contacts together after engagement, or biasing contacts to the open position
    • 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
    • H01H1/00—Contacts
    • H01H1/0036—Switches making use of microelectromechanical systems [MEMS]
    • H01H2001/0078—Switches making use of microelectromechanical systems [MEMS] with parallel movement of the movable contact relative to the substrate

Definitions

  • micro-electro-mechanical system micro electro-mechanical system, MEMS
  • a corresponding method are, for example, out DE 198 00 189 A1 known.
  • a micromechanical switch is described there, which is a flat carrier substrate, one on the carrier substrate fixed contact piece, a movable electrode and a fixed to the Carrier substrate connected includes the counter electrode.
  • the movable electrode has a free end and a fixed one connected to the carrier substrate The End.
  • the movable electrode and the counter electrode face each other Surfaces on.
  • the electrostatic forces of attraction between the facing one another Surfaces of the movable electrode and the counter electrode is through applying a voltage between the movable electrode and the Counter electrode generated.
  • a short circuit that is an electrical one Contact between the movable electrode and the counter electrode
  • stoppers are inserted in the counter electrode, which over the protrude the surface of the counter electrode facing the movable electrode and are not at the same potential as the counter electrode.
  • Springs can also be provided for the same purpose, on which the Counter electrode facing away from the movable electrode attached and the movement of the movable electrode in the direction of the counter electrode limit.
  • the surface of the movable electrode facing the counter electrode be provided with an electrically insulating layer.
  • the force therefore increases linearly with the surface, quadratically with the tension and inversely proportional to the square of the distance.
  • the microsystem disclosed in the aforementioned DE 198 00 189 A1 has been published under Use of a silicon deep etching process generated from the carrier substrate. After applying a mask to the carrier substrate at the points where the mask is open, material is etched out of the carrier substrate. The resulting trenches or etching channels, at least have a minimum width characteristic of the etching process.
  • a sacrificial layer process is used, the free end of the movable Separates the electrode from the carrier substrate.
  • the carrier substrate below the moving parts of the micromechanical switch arranged sacrificial layer selectively removed by an etching process, wherein the sacrificial layer at locations where a connection to the substrate is desired is, as on the counter electrode, the fixed contact piece and the fixed end of the movable electrode.
  • DE 42 05 029 C1 shows an electrostatically operated micro-electromechanical Relay that works horizontally. That means the switching movement this relay runs essentially perpendicular to a carrier substrate.
  • a tongue-shaped electrode with a contact piece is made from a silicon substrate etched. The substrate is then placed on a counter substrate a counter electrode and a counter contact applied that the electrode includes a wedge-shaped gap with the counter electrode.
  • By Applying a switching voltage between the electrode and the counter electrode these can be moved towards each other, creating an electrically conductive Connection between contact and counter contact can be achieved. Size Contact forces can be achieved through relatively wide electrodes.
  • MEMS micro-electro-mechanical system To create
  • Improved switchability can mean, for example, that a switching operation can already be triggered at lower switching voltages.
  • New functionalities can, for example, the realization of de-energized closed Connections or of micro-relays with both de-energized open as well as voltage-free closed connections.
  • micro-actuators can be new or be realized more simply or in an improved form.
  • the second micro-element is a first solid which is firmly connected to the substrate End as well as a moving part, being in the working position of the first micro-element the movable part of the second micro-element by electrostatic forces between the first micro-element and the second micro-element from an off position to an on position is movable, and wherein the two micro-elements in the area of the the said smaller distance between the two micro-elements is present, have contact points and is electrically non-conductive are.
  • the fact that there are points of contact means that the lower one mentioned Distance is zero.
  • Electrostatically operating actuators whose electrostatically switchable electrodes (electrode and counter electrode) touch each other.
  • the consequence of electrode gaps is improved switchability. Switching the actuator with very low switching voltages is possible.
  • the first micro-element is additionally designed such that it is a includes adapted counter electrode, the shape of the second micro-element is adapted: the adapted counter electrode is shaped in such a way that the adjusted in the switch-on position of the second micro-element Counter electrode and the second micro-element in the area mentioned Overlap areas of contact over a large area.
  • the on position The matched counter electrode of the second micro-element nestle and the second micro-element to each other. This will make one Maximized the areas between which the electrostatic Attractions act, which is greater electrostatic attractions and thus results in improved switchability. Switching the actuator with very low switching voltages.
  • the said adapted Counter electrode additionally a second section, the opposite the section of the counterelectrode that clings to the second micro-element is stepped back.
  • this second section of the adapted Counter electrode and the second micro-element close this second section of the adapted Counter electrode and the second micro-element a gap.
  • the force that can be selected in this way can be, for example a contact force of the second micro-element on one or two electrical Contacts that are the second micro-element in its on position contacted, whereby a safe electrical contact can be made.
  • a changeover switch relay realized.
  • the movable part of the second micro-element by switching the first micro-element elastically deformable from the initial position to the working position. Thereby it is possible to implement closed connections without voltage.
  • the method according to the invention includes two Micro elements with facing surfaces switching the bistable switchable micro-element. This can create new or improved ones MEMS such as those mentioned above are manufactured.
  • Fig. 1 shows a schematic plan view of a first according to the invention micro-electromechanical system (MEMS). It comprises a first micro element 1 and a second micro element 2, both rigid with one Substrate S are connected.
  • MEMS micro-electromechanical system
  • the substrate S is a wafer made of single-crystal silicon, in which one of the two largest surfaces forms a main surface of the substrate. In Fig. 1, this main surface lies in the paper plane.
  • DRIE dry reactive ion etching
  • sacrificial layer technology the first micro-element 1 and the second micro-element 2 from the S shaped substrate.
  • the structuring process DRIE has the property of removing material Procedure to be; it is an etching process. It also has the property good for creating narrow yet deep channels, columns or Trenches to be suitable, giving the DRIE a preferred direction which can be the direction of the preferred material removal indicates and is therefore perpendicular to the main surface of the substrate. Perpendicular again to this preferred direction is the width of one using DRIE generated trench downwards, i.e. narrow trenches.
  • micro elements 1, 2 are formed from the substrate can, is known to the person skilled in the art and can also, for example, of those mentioned Laid-open application DE 198 00 189 A1 can be found in the hereby included in the description with its entire disclosure content becomes.
  • Micro-elements created with DRIE typically have side faces, which are aligned almost perpendicular to the main surface of the substrate S, or in other words: (local) surface normal vectors of the side surfaces run practically parallel to the main surface of the substrate S.
  • Such Micro elements are therefore essentially in the form of a straight line (right angled) prism, the base of which is parallel to the main surface of the Substrate S is aligned.
  • the level is typically such Micro element (perpendicular to the main surface) very large compared to the (Narrowest) width of such a micro element.
  • the first micro element and the second micro element are of this type.
  • the first micro-element 1 is a bistable elastic MEMS mechanism trained as described in the publication J. Qiu et al., "A Centrally-Clamped Parallel-Beam Bistable MEMS Mechanism ", Proc. Of MEMS 2001, Interlaken, Switzerland, Jan. 20-22, 2001. Details about Embodiments, properties and for the production of such Micro-elements can be found in this publication, which hereby included in the description with its entire disclosure content becomes.
  • the first micro element 1 is at a first end 6 and a second end 7 fixed on the substrate S. In between that points first micro-element 1 two parallel, cosine curved Spring tongues on the middle 8 between the two ends 6.7 with each other are connected. Considering their small width and their large These spring tongues can be adjusted in height (perpendicular to the main substrate surface) also understand as a parallel membrane.
  • the first micro-element 1 is bistable between an initial position A and a working position B switchable (the latter shown in dashed lines in Fig. 1). This means that the micro-element 1 has two mechanically stable states or positions A and B, between which there is a lateral, force parallel to the substrate can be moved back and forth; the movement takes place essentially laterally. Any intermediate positions are not stable, but independently lead to a rapid transition into one of the two stable states A or B. The transition takes place by preferably elastic deformation of the first micro element 1.
  • the first micro-element 1 consists here only of a switching part 5, through which it is bistable switchable.
  • the first micro-element 1 faces the second micro-element 2 Page a side formed by DRIE, the first Area 3a is called.
  • This first surface 3a has a first coating 3b, which is electrically insulating and its outer, that is, from the Surface 3a facing away from the first surface 3 of the first Micro-element 1 forms.
  • the first coating 3b is typically generated by oxidation of the silicon.
  • the second micro-element 2 has a first fixed end 10 on which it is fixed on the substrate S, and a movable part 11; it is arranged next to the first micro-element 1.
  • the second micro-element 2 On that side of the second micro-element facing the first micro-element 1 the second micro-element 2 has a side surface shaped by DRIE on, which is referred to as the second surface 4a.
  • This second surface 4a has a second coating 4b, which is electrically insulating and whose outer surface, ie the surface facing away from the second surface 4a forms second surface 4 of the second micro-element 2.
  • the first surface 3 and the second surface 4 are surfaces facing one another, as well as the first surface 3a and the second surface 4a facing each other are.
  • the second coating 4b is also typically made by oxidation of silicon.
  • the first micro-element 1 in the initial position A and that second micro-element 2 in an off position A ' is the first micro-element 1 in the initial position A and that second micro-element 2 in an off position A '. Since the surfaces 3a and 4a are formed in the middle DRIE, they have a distance from each other that is at least is as large as a minimum distance given by DRIE. With the The distance between the surfaces means the distance between the two Have points that are closest to each other, one Point on the first surface 3a and the other point on the second surface 4a lies. So the distance is the width of the trench between the first Surface 3a and the second surface 4a at its narrowest point. 1 is this point at a corner of the first fixed end 10 of the second micro-element 2 and near the first end 6 of the first micro-element 1 the membrane of the first micro-element 1, which has the first surface 3a.
  • the initial position A of the first micro-element 1 is a production-related one Initial position.
  • the arrangement of the first micro element 1 and of the second micro-element 2 is selected such that after a switchover of the first micro-element 1 from the initial position A to the working position B the distance of the first surface 3a from the second surface 4a is smaller than that mentioned by the manufacturing process (e.g. DRIE) given minimum distance.
  • the distance is even zero, that is, in working position A, the first micro-element touch 1 and the second micro-element 2.
  • the working position A can intended interaction of the first micro-element 1 with the second micro-element 2 take place within the MEMS.
  • the MEMS in Fig. 1 represents a micro-actuator that of the first micro-element 1 and the second micro-element 2, together with the substrate S. is formed.
  • the second micro-element 2 acts as a movable, electrostatically switchable electrode and the bistable switchable first micro-element 1 as an associated electrostatic counter electrode.
  • the first Micro-element 1 is in working position A.
  • the functioning of the micro-actuator when it is in working position B is essentially known from the prior art: On the first fixed End 6 of the first micro element 1 is a contacting electrode C, and at the first fixed end 10 of the second micro-element 2 a contacting electrode C 'is provided. These contact electrodes C, C 'are used to apply switching voltages to the micro-elements 1,2, through which the micro-elements are charged electrostatically, so that electrostatic forces between micro-elements 1 and 2 Act.
  • the material from which the micro-elements are made be sufficiently conductive, for example by appropriate doping of silicon is reached.
  • the electrostatic force increases inversely proportional to the distance.
  • the MEMS according to the invention Fig. 1 has the great advantage, even with smaller switching voltages to be switchable than they would be required for a MEMS, its distance between electrode and counterelectrode greater than or equal to that due to Structuring method given the minimum distance.
  • the micro actuator in FIG. 1 can be used, for example, as an optical micro switch can be used by passing a light beam to be switched or interrupted by the movable part 11 of the second micro-element 2 will, depending on whether the second micro-element 2 is in the off position A 'or in the switch-on position B'. Redirecting is just as good a light beam with the micro-actuator in Fig. 1 possible, for example when in the movable part 11 of the second micro-element 2 reflective area is arranged (not shown).
  • the switch-on position B ' is by definition present when there are suitable switching voltages; otherwise the switch-off position A 'is present.
  • the bistable switchable first micro-element 1 is called an electrostatic Electrode or counter electrode used.
  • FIG. 2 shows a MEMS which largely corresponds to the MEMS from FIG. 1; Indeed the first micro element 1 is constructed differently.
  • the first micro element 1 is here lateral as another, bistable and preferably elastic switchable mechanism.
  • the first micro element 1 is also here at a first end 6 and a second end 7 on the substrate S. set.
  • the first micro-element 1 has a curved one Spring tongue, which has the shape of an antinode. In view of its small width and great height (perpendicular to the Substrate main surface) this spring tongue can also be used as a membrane describe.
  • the first micro-element 1 In the initial position A, that is, in the state in which the first micro-element 1 is structured, the first micro-element 1 describes one symmetrical antinode, in working position B an asymmetrical one Vibration belly (the latter drawn in dashed lines in Fig. 2).
  • the asymmetrical antinode represents the second stable position of the first Micro-element 1 represents and comes about by the fact that one with the Substrate S firmly attached stop the first micro-element 1 in the working position B touches and the corresponding deformation of the first Micro-element 1 leads. This stop is here by a corresponding formed and arranged first fixed end 10 of the second micro-element 2 formed.
  • the corresponding point of contact is expedient right of a link that runs from the second end 7 extends to the first end 6 of the first micro-element 1 when the symmetrical antinode in the initial position A to the left of this Connection route is arranged.
  • the value of a parallel to this link position coordinate of the point of contact not 0.5 (no asymmetrical antinode) and lies preferably between 0.52 and 0.92 the length of the link; it is here about 0.84.
  • the stop can also by a correspondingly shaped first End 6 or second end 7 of the first micro-element 1 are formed or as a separately fixed stop on the substrate S (which is then to be regarded as belonging to the first micro-element 1).
  • the MEMS becomes the first after the application of coatings 3b, 4b Micro-element 1 switched from initial position A to working position B, where in working position B the distance between the two Micro elements 1.2 is smaller than the minimum distance mentioned.
  • MEMS thus become two micro-elements with one through the structuring process not produced a small distance apart (by taking advantage of the bistable switchability of one of the micro elements).
  • FIG. 3 shows a MEMS according to the invention, which largely corresponds to that in FIG. 1 shown embodiment corresponds; however, the first is here Micro-element 1 not only from a switching part 5, but also includes another electrode 9.
  • the electrode 9 has an elongated part, the first surface 3a, the first coating 3b and the first surface 3 of the first micro-element 1 includes. This part is by means of another elongated part, which is aligned approximately perpendicular to the above is, with the switching part 5 in the middle 8 between the ends 6,7 of the first Micro-element 1 connected.
  • the electrode 9 Since the electrode 9 is attached to the switching part 5, it moves with the Switching part 5 with when from the initial position A to the working position B (and back again if necessary). Become more suitable by creating Switching voltages electrostatic attraction between the first Micro element 1 (naturally in working position A) and the second micro element 2 generated, so the movable part 11 of the second micro-element 2 elastically deformed and approaches the electrode 9: It is from the switch-off position A 'switched to the switch-on position B'.
  • the shape of the Electrode 9, and in particular the shape of first surface 3, is preferred shaped such that the first surface 3 and the second Touch surface 4 fully in the switch-on position. It means that there is a flat contact between the two surfaces 3, 4, which does not mean that the two surfaces 3, 4 completely touch have to.
  • the first surface 3 is thus in the shape of the second surface 4 adjusted in the switch-on position.
  • the two surfaces 3, 4 are nestled against each other in the switch-on position B '.
  • By the adapted Electrode 9 becomes the effective area for the electrostatic forces maximized and the effective distances minimized. Consequently, at low switching voltages can be switched.
  • FIG. 3 For more details on the Embodiment of FIG. 3 is written to that written in connection with FIG. 1 directed.
  • the second micro-element 2 has or more precisely: the movable part 11 of the second micro-element 2, one Contact area 16, which is electrically conductive.
  • the Contact area 16 in the area of that end of the movable part 11 of the second micro-element 2, which is not at the first fixed end 10 of the second micro-element 2 borders.
  • the contact area 16 forms part of a side surface of the second micro-element 2 and is preferred formed as a coating that by means of vapor deposition or Sputtering techniques is applied to the second micro-element 2.
  • the MEMS further comprises two electrically fixed on the substrate S. conductive fixed contacts 17, 18.
  • the arrangement of the fixed contacts 17, 18 and the contact area 16 is selected in such a way that more suitable in the event of concerns Switching voltages on the first micro-element 1 and the second micro-element 2 (i.e. in the switch-on position B 'of the second micro-element 2) the contact area 16 an electrically conductive connection between the Fixed contact 17 and the fixed contact 18 generated.
  • a ' is in the off state this is not the case. So there is an electrostatic micro-relay through which is formed by the fixed contacts 17, 18 by means of the switching voltages Connection can be switched.
  • the open distance between the Contact area 16 of the second micro-element 2 and the fixed contacts 17.18 can be selected and can be reproduced very well in terms of production technology.
  • the contact area 16 is in FIG. 4 on that side of the second micro-element 2 arranged, which faces the first micro-element 1, on the side that also contains the surface 4.
  • the fixed contacts 17, 18 are in such a way that that they are in that area of the substrate S which is on the side of the second micro-element facing away from the first micro-element 1 2 lies.
  • the contact area 16 is then corresponding to that Side of the movable part 11 of the second micro-element 2, which faces away from the first micro-element 1.
  • the relay can be switched by repulsive electrostatic forces.
  • this micro relay or that Fig. 4 shown to build micro-relays without (adapted) electrode 9 (analogous to the structure in Fig. 1).
  • the MEMS also includes one third micro-element 1 'and two further fixed contacts 17', 18 '; and the second micro-element 2 has a further electrically conductive contact area 16 'on which on one side of the movable part 11 of the second Micro-element 2 is arranged, which is the side facing the Has contact area 16.
  • the third micro-element 1 'and the others Fixed contacts 17 ', 18' are movable with respect to the elongated Part 11 of the second micro-element 2 arranged in mirror image to the first micro element 1 and the fixed contacts 17, 18.
  • the arrangement must not be exactly mirror images; it is sufficient if the third micro-element 1 'connected to the substrate in a region of the substrate S. is that on the side facing away from the first micro-element 1 of the second Micro-element (2) and the other fixed contacts 17 ', 18' in one area of the substrate S are connected to the substrate on which the Fixed contacts 17, 18 facing away from the second micro-element 2.
  • the structure of the third micro-element 1 ' corresponds to the structure of the first Micro-element 1.
  • the other fixed contacts 17 ', 18' are of the same type designed like the fixed contacts 17, 18.
  • the interaction between the third micro-element 1 'and the corresponds to the second micro-element (2) and the further fixed contacts (17 ', 18') the interaction between the first micro-element described above 1 and the second micro-element 2 and the fixed contacts 17, 18.
  • suitable switching voltages are applied to the third micro-element 1 ' and the second micro-element 2 can be an electrically conductive connection between the further fixed contacts 17 ', 18' through the further contact area 16 'can be created.
  • Three-position switch or a changeover relay that defined three States have: (1.) contacts between the two fixed contact pairs 17, 18; 17 ', 18' open, (2.) contacts between the further fixed contacts 17 ', 18' open and Contacts between the fixed contacts 17, 18 closed and (3.) contacts between the fixed contacts 17, 18 open and contacts between the others Fixed contacts 17 ', 18' closed.
  • FIG. 6 shows a further MEMS according to the invention, which largely corresponds to the MEMS from FIG. 4. It contains the characteristics of the MEMS Fig. 4, for which reference is made to the corresponding part of the description.
  • the electrode 9 of the first micro-element 1 is special here educated.
  • the electrode 9 has an (optionally step-shaped) recess on.
  • the electrode 9 comprises a gap-forming surface 12 which stepped in relation to the first surface 3 of the first micro-element 1 is set back. You can see this electrode 9 as a stepped Designate electrode 9.
  • attractive electrostatic Forces to switch from switch-off position A 'to switch-on position B' used.
  • the first micro-element 1 is in the working position B.
  • the second micro-element 2 and the second micro-element 2 in the switch-on position B ' they close gap-forming surface 12 and the second micro-element 2, or more precisely: the movable part 11 of the second micro-element 2, a gap 13.
  • the choice of the geometry of the gap allows one targeted predetermination and choice of contact force. In particular, can for this purpose the length of the gap and the width of the gap (i.e.
  • the Distance between movable part 11 of the second micro-element 2 and the gap-forming surface 12) and optionally the course of the Width of the gap can be selected.
  • the length of the gap by approximately one order of magnitude, preferably by approximately two orders of magnitude larger than the width of the gap.
  • An (approximately) evenly is advantageous wide gap selected, and the first surface 3 touches the second Full surface 4. The relative arrangement of the micro elements 1, 2 and the fixed contacts 17, 18 on the substrate must be carried out carefully.
  • Such a MEMS has the advantage that problems that may arise when switching from switch-on position B 'to switch-off position A', caused by slow or poor detachment of the movable part 11 of the second micro-element 2 from the electrode 9 (more precisely: from the first surface 3) for example due to surface effects can occur, can be reduced.
  • the (air) gap 13 allows one rapid detachment of the movable part 11 of the second micro-element 2 from the electrode 9 when switching from the switch-on position B 'to the switch-off position A ', while still in the switch-on position B' large electrostatic Attractive forces between the first micro-element 1 and the second micro-element 2 act if the gap width is appropriate was chosen low.
  • the movable part 11 of the second Micro-element 2 is specially designed here. It has a first area 14 and a second area 15, the first area 14 being less is stiff, that is to say more easily deformable, than the second region 15. And the first area is between the fixed first end 10 of the second Micro-element 2 and the second region 15 are arranged.
  • the contact area 16 is advantageously arranged in the second area 15, in particular in the Region of the end of the second opposite the first region 15 Area 16.
  • the second area 15 comprises at least that Area of the movable part 11 in which the movable part 11 and the second micro-element 2 do not face each other.
  • the second region 15 advantageously at least that area of the movable Part 11, in which the movable part 11 and the gap-forming surface 12 face each other.
  • the second area 15 also has a (slight) overlap with the first Surface 3 has.
  • the greater stiffness of the second area 15 compared to the first area 14 is achieved in the exemplary embodiment from FIG. 7 in that the second region 15 is thicker or wider than the first region 14. It is also possible to make the second region 15 more difficult to bend make, for example, by applying a coating there; to the Example on a base of the straight prismatic body that the forms second region 15, or on at least one of the side surfaces. through a correspondingly (large, long) trained contact area, the is designed as a coating, this could be achieved.
  • NO connection means that connection is open when a suitable switching voltage is not present (open when de-energized), as in the exemplary embodiments listed above (Fig. 4 to Fig. 7) is the case.
  • NC connections which are not used a suitable switching voltage are closed (de-energized closed), on the other hand, are difficult to implement, but are in this Embodiment realized.
  • an NC connection is in here a MEMS structured using DRIE.
  • the MEMS in FIG. 8 is constructed in mirror image and comprises a first micro element 1, a third micro-element 1 ', a fourth micro-element 19 and a fifth micro-element 20, which are all bistable and one stable initial position A (drawn solid) and a stable working position B (shown in dashed lines). They are here as such bistable micro-elements are formed, as they are in connection with FIG. 1 are described in more detail (two parallel, cosine-shaped, connected in the middle Spring tongues). The position in which these micro elements are used The first position is A.
  • the first micro element 1 and the third micro-element 1 ' largely correspond to each other in their Function. They consist of only one switching part 5.
  • the fourth micro element 19 and the fifth micro-element 20 also correspond to one another largely in their function. They each have a contacting electrode D, D '(for applying a signal to be switched, for example one electrical current) and an electrically conductive contact electrode 21, 22 on.
  • the conductivity of the contact electrodes 21, 22 is preferably determined by creates a metallic coating.
  • the contact electrodes 21, 22 are elongated, finger-shaped and approximately in the middle 8 between the two Ends of the respective micro element 19, 20 on the respective micro element 19.20 attached.
  • the MEMS has two more with the Fixed electrodes 17, 18 connected to substrate S (for the application of another electrical current to be switched).
  • the MEMS in FIG. 8 further comprises a second micro-element 2.
  • the second micro element 2 is a monostable switchable micro element; it therefore only has a stable position. It includes a first fixed end 10 and a second fixed end 10 ', which ends 10,10' on the substrate S are fixed, and a between these two fixed ends 10,10 ' arranged movable part 11.
  • the movable part 11 is as one, preferably Vibration-bellied, curved structure designed to the the two fixed ends 10, 10 'of the second micro-element 2 is attached and has an electrically conductive contact region 16.
  • the mobile Part 11 also has a second surface 4, which is of an optional second coating 4b is formed, and what second surface 4 facing a first surface 3 of the first micro-element 1 is. The situation is analogous with a fourth surface 4 'of the second micro-element 2 and a third surface 3 'of the third micro-element 1'.
  • the second surface 4 is between the first fixed end 10 and the Contact area 16 arranged.
  • the fourth surface 4 ' is between the second fixed end 10 'and the contact area 16.
  • To the structuring of the second micro-element 2 is the movable one Part 11 in the off position A ', the stable position of the second Micro element 2.
  • the bistable micro-elements 1, 1 ', 19, 20 Due to the existence of the minimum distance between are two micro elements or surfaces created by DRIE the bistable micro-elements 1, 1 ', 19, 20 from the second micro-element 2 spaced with at least one such minimum distance.
  • the optional non-conductive coatings 3b, 3b 'of the first and third micro-element 1,1 'and the optional electrically conductive Coatings of the contact electrodes 21,22 are in the context of Manufacturing method of the MEMS according to the invention the bistable micro-elements 1,1 ', 19,20 switched from the initial position A to the working position B. This will set the distance between the micro elements or Surfaces less than the specified minimum distance; touch in Fig. 8 even the micro elements. In particular, both contact electrodes touch 21, 22 the contact area 16.
  • Fig. 9 shows a two-way switching relay, which apart from a normally open connection (NO connection) also a normally closed connection (NC connection) includes.
  • the MEMS is structured very similar to that described in Figure 8; for corresponding features, refer to the above Text referenced.
  • the second micro-element 2 is not monostable here, but designed to be bistable. In particular, it has a structure with two parallel, cosine-shaped spring tongues connected in the middle, as described in detail in connection with FIG. 1.
  • the two stable positions of the second micro-element 2 are the switch-off position A 'and the switch-on position B'.
  • a big advantage of the bistability of the second micro element 2 is that there is no applied switching voltage required to the second micro-element 2 in the switch-off position A 'or Hold switch position B '. After applying a suitable switching voltage and the switching process caused thereby into the other state A ', B', the second micro-element 2 automatically remains in this state FROM'. This allows each of the two pairs of contacts to which one is closed switching signal is present (fixed electrodes 17, 18 or micro-elements 19, 20) can be an NO connection or an NC connection.
  • the MEMS in FIG. 9 has two further bistable switchable micro-elements on: the sixth micro element 23 and the seventh micro element 24. These are also here with two parallel, cosine-shaped, in the middle connected spring tongues and each have one (adapted) electrode 9. They are arranged in the region of the substrate S, which is on the side of the second micro-element 2 that the Micro-elements 1.1 'is facing away.
  • the micro elements 23, 24 act in analogously with the second micro-element 2 together as the micro-elements 1.1 '.
  • the second micro-element 2 has one sixth surface 26a and an eighth surface 26a 'with a fifth Surface 25a (of the sixth micro element 23) or a seventh Surface 25a '(the seventh micro-element 24) interact.
  • electrostatic attraction forces between the second micro-element 2 and the sixth micro-element 23 (more precisely: between the corresponding Surfaces or surfaces) or the seventh micro-element 24 (more precisely: between the corresponding surfaces or surfaces) can the second micro-element 2 from the on state B 'in the Switch-off state A 'can be switched.
  • 10a to 10c show a further advantageous embodiment of the Invention in different positions.
  • This MEMS is a micro relay with an NC connection, which is generally only is difficult to implement.
  • the MEMS is based on that shown in FIG. 4 Embodiment described, since it has the same components having.
  • 10a shows the MEMS, in the state it is after the structuring by means of DRIE: The first micro element 1 is in the initial position A.
  • Fig. 10b shows the MEMS in a state in which the first micro-element 1 is in the working position B, and that second micro-element 2 is in the off state A '.
  • 10c shows the MEMS in a state in which the first micro-element 1 is in the working position B, and the second micro-element 2 in the Switched on state B '.
  • the first micro-element 1 after switching from the initial position A in the working position B comes closer than the minimum distance given by DRIE and only touches the second micro element 2 (lightly).
  • the arrangement of the micro elements 1, 2 on the substrate S and the configuration of the Micro elements 1, 2 selected such that the first micro element 1 in the Working position B a force on the movable part 11 of the second micro-element 2 exercises, which leads to a (clear) elastic deformation of the Movable part 11 of the second micro-element 2 leads (see Fig. 10b).
  • the movable part 11 of the second micro-element 2 is deformed in such a way that the electrically conductive contact area 16 of the second micro-element 2 Conductively connects the fixed contacts 17, 18:
  • the NC connection is closed. It becomes a tension-free closed but detachable contact realized; in a MEMS structured using DRIE.
  • By switching the first micro-element 1 from the initial position A in the working position B is a switching operation of the second micro-element 2 evoked. Since there is no switching voltage required, is the second micro-element 2 after this switching process in the Switch-off position A '.
  • a suitable switching voltage between the first micro-element 1 and the second micro-element 2 can be created.
  • the NC connection is opened and the second micro element 2 goes into the on state B '(see Fig. 10c).
  • the electrode 9 can be omitted. Or the electrode 9 can be designed differently.
  • the electrode 9 and the micro-elements can advantageously be designed in this way 1.2 to each other so that the points of contact between the two micro-elements 1, 2 (if the first micro-element 1 in is the working position A and the second micro-element 2 in the switch-off position A 'is) lying essentially on a straight line with the center 8 in the initial position A and the middle 8 in the working position. This can cause a low mechanical stress on the first micro-element 1 reached be, with large contact forces on the fixed contacts 17,18 can be exercised (safe contacts).
  • a second pair of fixed contacts 17 ', 18' (not shown in Fig. 10) to be provided, these fixed contacts 17 ', 18' being arranged such that the contact area 16 of the second micro-element 2 these fixed contacts 17 ', 18' electrically conductively connects to one another when the second micro-element 2 is in the switch-on position B '.
  • the movable part 11 of the second micro-element 2 are formed in two parts (analogous to that Embodiment of Fig. 7).
  • FIG. 11a and 11b show a possible embodiment in which the moving parts of the MEMS are essentially horizontally movable.
  • Figure 11a is a cross-sectional side view of the one shown in plan in Figure 11b MEMS.
  • Fig. 11b with XIa-XIa is the line of the section of the 11a.
  • the MEMS is a micro relay with an NC connection.
  • the first micro-element 1 is here a bistable in the form of an antinode elastically switchable micro-element, analogous to that in FIG. 2 shown first micro-element 1.
  • A In the initial position A is the symmetrical Vibration belly arched away from the substrate S.
  • the second end 7 of the first micro-element 1 is designed here as a bridge. Thereby can the second micro-element arranged below the antinode 2 to outside the area between the first end 6 and second end 7 of the first micro-element 1 extend.
  • the first firm End 10 of the second micro-element 2 serves as a stop for the Formation of the asymmetrical antinode of the first micro-element 1 in working position B.
  • the movable part 11 of the second micro-element 2 initially runs (after structuring) substantially parallel to the main surface of the Substrates S. After switching the first micro-element 1 from the initial position A in working position B the first micro-element 1 exercises Compressive force on the movable part 11 of the second micro-element 2.
  • the second micro element 2 is elastically deformed. It gets into his Switch-off position A ', in which a fixedly attached to the movable part 11 movable contact electrode E a fixed electrode fixed on the Sustrat S. 17 touches. This creates an NC connection between the movable Contact electrode E and the fixed electrode 17. This generation of a NC connection is quite analogous to that in connection with the 10a to 10c described method.
  • the second micro-element 2 goes into the on state B 'above, in which the movable part 11 of the second micro-element 2 is bent away from the substrate and the NC connection is opened is.
  • the contacting electrodes C, C ' serve to apply Switching voltages. Contacting electrodes are used to apply a signal to be switched D, D '
  • the contacting electrode D which is electrical connected to the movable contact electrode E is here on the first fixed end 10 of the second micro-element 2 arranged. With the fixed contact 17 electrically connected contacting electrode D 'is on arranged the substrate S.
  • MEMS such as those described above MEMS can also be implemented as horizontally operating MEMS.
  • An arrangement with a fixed electrode 17 and a movable contact electrode E, as in Fig. 11a and 11b, is also advantageous in the above described MEMS, which with a contact area 16 and two fixed electrodes 17, 18 are described, realizable.
  • a MEMS according to the invention is not only, as in the examples above, as Switch or relay executable.
  • Various micro-actuators can be implemented.
  • the substrate S used to produce a MEMS according to the invention is preferably flat. Typically it has one Main area that is structured to produce the MEMS, the Movement of the moving parts of the MEMS essentially parallel or are movable perpendicular to this main surface.
  • Substrate S made of a semiconductor material, in particular silicon, which is advantageous monocrystalline and particularly advantageous (for sufficient electrical Conductivity) is also endowed. With single-crystalline silicon is under Mechanical stress-resistant bistable switchable micro elements 1,1 ', 2,19,20,23,24 advantageously no or only very slow Relaxation to be expected.
  • an SOI wafer silicon-on-insulator
  • silicon oxide-silicon there the silicon oxide layer serves as a sacrificial layer.
  • the structuring process mentioned is typically a material-removing process Process, preferably an etching process.
  • the LIGA technology or in particular the reactive ion etching and particularly advantageously the ion etching (DRIE) come into question here.
  • the DRIE process has the advantage to be very well suited for the creation of surfaces which (relative to their subtrate perpendicular height) are closely spaced and practically perpendicular to the main surface of the substrate S.
  • the laterally working MEMS is well suited DRIE.
  • the material Applying are conceivable, for example when facing each other Depending on the process, surfaces must have a minimum distance. For example Rapid prototyping processes using photopolymerization.
  • actuators that can be actuated electromagnetically or piezoelectrically will be realized.
  • the actuating forces can be repulsive or attractive his.
  • a bistable switchable micro-element according to the invention can also be tristable or otherwise switchable multistable. It is for some applications furthermore, it is not necessary for the micro-elements 1, 1 ', 19, 20, 23, 24 after the first switch from the initial position A to the working position B can also be switched back to the initial position A.
  • the micro elements 1, 1 ', 19, 20, 23, 24 are preferably bistably elastic switchable and switchable back to initial position A. Especially It is advantageous to use the bistable micro-elements 1,1 ', 2,19,20,23,24 the described cosine or as the described antinode Form micro-elements, these also in modified form Form and combined within a MEMS can be realized.
  • the micro elements can optionally be electrically conductive or be coated electrically non-conductive.
  • a non-conductive coating preferably serves to prevent discharges between one another touching electrostatic electrodes.
  • the contacting electrodes C, C ', D, D' can be produced in a known manner (for example by sputtering) and for example contactable by bonding.
  • the first switching of the first micro-element 1 and also the other bistable switchable micro-elements 1 ', 19, 20, 23, 24 of the initial position A in the working position B as yet to the manufacturing process of the MEMS is to be considered properly.
  • This initial switching process can be done mechanically. However, this switching operation is preferably carried out in Carried out as part of a quality or functional test (burn-in) of the MEMS, other units connected to the substrate also being tested or can be initialized.
  • the initial switching process can then preferably by creating an attractive force between the bistable Micro-element 1,1 ', 19,20,23,24 and the second micro-element 2 take place, this force advantageously by applying a switching voltage he follows.
  • a switching voltage is typically higher than one Switching voltage used to switch the second micro-element 2 between Switch-off position A 'and switch-on position B' is used.
  • the linear expansion of the MEMS described is typically between 0.2 mm and 5 mm, preferably 0.8 mm to 2 mm.
  • DRIE as a structuring process is the minimum distance mentioned (minimum trench width) about 5 ⁇ m to 15 ⁇ m; it shows little dependence on the Depth of the structured trench.
  • Layer thicknesses of the electrically non-conductive coatings 3b, 3b ', 4b, 4b' are typically 50 nm to 500 nm
  • the switching voltages for the MEMS described are typically 10 V to 80 V, preferably 25 V to 50 V.
  • electrostatic attractive forces are typically used for this Switching voltages between 70 V and 300 V, preferably between 100 V and 200 V.

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EP02405334A 2002-01-18 2002-04-24 Système microélectromécanique et son procédé de fabrication Withdrawn EP1357571A1 (fr)

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Application Number Priority Date Filing Date Title
EP02405334A EP1357571A1 (fr) 2002-04-24 2002-04-24 Système microélectromécanique et son procédé de fabrication
EP02796487A EP1468436B1 (fr) 2002-01-18 2002-12-23 Systeme micro-electromecanique et procede de fabrication
US10/501,979 US7109560B2 (en) 2002-01-18 2002-12-23 Micro-electromechanical system and method for production thereof
AU2002361920A AU2002361920A1 (en) 2002-01-18 2002-12-23 Micro-electromechanical system and method for production thereof
PCT/CH2002/000722 WO2003060940A1 (fr) 2002-01-18 2002-12-23 Systeme micro-electromecanique et procede de fabrication
DE50204300T DE50204300D1 (de) 2002-01-18 2002-12-23 Mikro-elektromechanisches system und verfahren zu dessen herstellung
AT02796487T ATE304736T1 (de) 2002-01-18 2002-12-23 Mikro-elektromechanisches system und verfahren zu dessen herstellung

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KR100703140B1 (ko) 1998-04-08 2007-04-05 이리다임 디스플레이 코포레이션 간섭 변조기 및 그 제조 방법
US8928967B2 (en) 1998-04-08 2015-01-06 Qualcomm Mems Technologies, Inc. Method and device for modulating light
JP2008515150A (ja) * 2004-09-27 2008-05-08 アイディーシー、エルエルシー 変形する薄膜を備えたｍｅｍｓスイッチ
US7446927B2 (en) 2004-09-27 2008-11-04 Idc, Llc MEMS switch with set and latch electrodes
US7532195B2 (en) 2004-09-27 2009-05-12 Idc, Llc Method and system for reducing power consumption in a display
US7916980B2 (en) 2006-01-13 2011-03-29 Qualcomm Mems Technologies, Inc. Interconnect structure for MEMS device
EP1850360A1 (fr) 2006-04-26 2007-10-31 Seiko Epson Corporation Microrupteur avec une première pièce commandable et une seconde pièce de contact
US7724417B2 (en) 2006-12-19 2010-05-25 Qualcomm Mems Technologies, Inc. MEMS switches with deforming membranes
US8022896B2 (en) 2007-08-08 2011-09-20 Qualcomm Mems Technologies, Inc. ESD protection for MEMS display panels

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US5677823A (en) * 1993-05-06 1997-10-14 Cavendish Kinetics Ltd. Bi-stable memory element
US6168395B1 (en) * 1996-02-10 2001-01-02 Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung E.V. Bistable microactuator with coupled membranes

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US5677823A (en) * 1993-05-06 1997-10-14 Cavendish Kinetics Ltd. Bi-stable memory element
US6168395B1 (en) * 1996-02-10 2001-01-02 Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung E.V. Bistable microactuator with coupled membranes

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AU2002361920A1 (en) 2003-07-30
ATE304736T1 (de) 2005-09-15
EP1468436A1 (fr) 2004-10-20
WO2003060940A1 (fr) 2003-07-24

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