Classifications

• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11C—STATIC STORES
  • G11C23/00—Digital stores characterised by movement of mechanical parts to effect storage, e.g. using balls; Storage elements therefor
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B81—MICROSTRUCTURAL TECHNOLOGY
  • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
  • B81B3/00—Devices comprising flexible or deformable elements, e.g. comprising elastic tongues or membranes
  • B81B3/0064—Constitution or structural means for improving or controlling the physical properties of a device
  • B81B3/0067—Mechanical properties
  • B81B3/007—For controlling stiffness, e.g. ribs
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B81—MICROSTRUCTURAL TECHNOLOGY
  • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
  • B81B2203/00—Basic microelectromechanical structures
  • B81B2203/01—Suspended structures, i.e. structures allowing a movement
  • B81B2203/0127—Diaphragms, i.e. structures separating two media that can control the passage from one medium to another; Membranes, i.e. diaphragms with filtering function
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B81—MICROSTRUCTURAL TECHNOLOGY
  • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
  • B81B2203/00—Basic microelectromechanical structures
  • B81B2203/03—Static structures
  • B81B2203/0323—Grooves
  • B81B2203/0346—Grooves not provided for in B81B2203/033 - B81B2203/0338
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B81—MICROSTRUCTURAL TECHNOLOGY
  • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
  • B81B2203/00—Basic microelectromechanical structures
  • B81B2203/03—Static structures
  • B81B2203/0361—Tips, pillars
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B81—MICROSTRUCTURAL TECHNOLOGY
  • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
  • B81B2203/00—Basic microelectromechanical structures
  • B81B2203/05—Type of movement
  • B81B2203/051—Translation according to an axis parallel to the substrate
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B81—MICROSTRUCTURAL TECHNOLOGY
  • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
  • B81B2203/00—Basic microelectromechanical structures
  • B81B2203/05—Type of movement
  • B81B2203/058—Rotation out of a plane parallel to the substrate

Definitions

• micro-tips deforms locally under the action of local forces applied perpendicularly to its surface by micro-tips, under the control of electronic addressing and micro-tip control means, to allow recording of data on the support of memory. It is thus possible to achieve very high memory densities. However, it may be important, in particular for questions of tribology, to reduce as much as possible the stiffness of the memory medium under the microdots, without however limiting the dimensional stability of the memory medium in its plane.
• the invention aims to remedy the above drawbacks.
• a flexible membrane according to the appended claims and, more particularly by a flexible membrane comprising at least one thin layer in which are formed a plurality of notches, between which are located support points. for mechanical actuating elements intended to locally deform the membrane with which they come into contact at the support points.
• the notches are arranged periodically in the plane of the membrane.
• the notches may be linear, T-shaped, H-shaped or notched and have enlarged ends, of substantially circular section.
• the membrane constitutes a data recording medium intended to cooperate with a two-dimensional network of micro-tips coming into contact with the membrane at said support points.
• Figures 2 to 5 show a pattern of a flexible membrane according to the invention with different embodiments of the notches.
• the rows and columns are not necessarily horizontal and vertical respectively.
• the rows and the columns then each alternately comprise first notches (2a) arranged in a first direction and second notches (2b) arranged in a second direction.
• the step (p3) separating two first adjacent notches (2a) of the same line is preferably substantially equal to twice the step (p1) separating, in the second direction, two support points (3) adjacent, the pitch (p4) separating two adjacent second notches (2b) of the same column being substantially equal to twice the pitch (p2) separating, in the first direction, two adjacent support points 3.
• the different steps mentioned above can be of the order of 100 ⁇ m for p1 and p2 and of the order of 200 ⁇ m for p3 and p4, the length of the notches being of the order of 120 ⁇ m to 150 ⁇ m.
• the membrane 1 thus perforated has increased flexibility in the transverse direction, without reducing the precision and the geometric quality of the membrane in its plane.
• the membrane Under the action of an actuating element exerting a force on a fulcrum 3, the membrane deforms transversely to its plane and has tears at the location of the notches 2 adjacent to said fulcrum.
• This increase in flexibility is all the more important as the notches 2 are long and leave little material constituting the membrane between them.
• a limit to the transverse flexibility of the membrane is however constituted by the loss of geometric rigidity of the membrane in its plane.
• the staggered structure described above provides good support of the ends of the elementary patterns, avoiding surface raising effects during the stages of production of the membrane consisting in releasing the surfaces.
• the arrangement of the notches can be arbitrary. It is in particular possible to use structures in the form of square, rectangular meshes (for example illustrated in FIGS. 1 and 2), in rhombus, etc.
• the shape of the notches can also be arbitrary.
• the notches can be linear, as shown in FIG. 1, possibly with enlarged ends, for example of substantially circular section, as shown in FIG. 2.
• Other geometric shapes are possible, in particular notches T-shaped, H-shaped, notched, as shown in Figures 3 to 5 respectively, or by a combination of these shapes on the same membrane.
• the widening of the ends of the notches, illustrated in FIG. 2 can be used whatever the shape of the notch (linear, T, H, square, etc.).
• a vertical notch 2a connected to a horizontal notch 2b adjacent to the same line constitute a single complex notch, in the form of a lying T.
• two horizontal notches 2b connected by a vertical notch 2a of the same column form a single complex notch, in the shape of a coated H.
• the number and / or dimensions of the notches are adapted to the minimum rigidity necessary for the membrane to play the role assigned to it.
• FIGS. 6 to 8 A particular method of manufacturing an openwork membrane is illustrated in FIGS. 6 to 8.
• a sacrificial layer 4, for example made of silica, is formed on a substrate 5.
• a layer 6, for example made of silicon nitride intended to constitute the membrane 1, is then deposited on the sacrificial layer 4.
• a mask 7, corresponding to the desired pattern for the notches, is formed, for example by photo- lithography in a resin layer, deposited on layer 6 ( Figure 6).
• the stack of layers 4 to 6 can also consist of silicon on insulator (SOI), which incorporates a layer of silica constituting an insulator and which can serve as a sacrificial layer 4.
• SOI silicon on insulator
• the silica layer can optionally, in known manner, also ensuring a separation layer function for a possible transfer of the membrane for assembly in accordance with Smartcut TM technology.
• the notches 2 are then formed in the layer 6, by anisotropic etching, preferably up to the level of the sacrificial layer 4 in silica (FIG. 7).
• This anisotropic etching can be carried out, in a known manner, by ion bombardment or by selective chemical attack, for example by potassium hydroxide (KOH) if the layer constituting the membrane is made of silicon.
• KOH potassium hydroxide
• the sacrificial layer 4 is then attacked, for example by selective isotropic etching in the aqueous phase, with hydrofluoric acid, by means of the notches 2 (FIG. 8).
• the membrane structure is thus released, by isotropic chemical attack stopped after a predetermined time, long enough to release the membrane.
• the latter remains fixed to the substrate 5 by the remaining part of the sacrificial layer 4, constituting a support frame for the membrane.
• the resin mask can then be removed, in a known manner, and possible additional layers of the membrane can then be deposited on the etched and released membrane.
• the openwork flexible membrane 1 according to the invention can be used in all structures with flexible membranes requiring great flexibility transverse and, more particularly in all structures in which a flexible membrane is intended to cooperate with a mechanical actuating structure bearing on the membrane at a number of support points 3, which can be movable in the plane of the membrane.
• An openwork membrane 1 can in particular be used as a memory medium in the field of data processing or in the field of multimedia.
• the membrane then serves as a data recording medium cooperating with a two-dimensional network of microtips.
• the flexible membrane 1 can be carried by a frame 8 forming a plurality of adjacent cells. Each cell then cooperates with at least one microtip 9.
• the two-dimensional network of microtips is, for example, formed on a base 10 disposed opposite the membrane 1, parallel to the latter.
• a relative movement of the micro-tips 9 and of the membrane 1 constituting the memory medium can be printed on the membrane and / or on the micro-tips by actuators (not shown), themselves controlled by microcomputer.
• the control and addressing or multiplexing of the micro-tips 9 in the reading or writing position is carried out by any appropriate means, preferably by an electronic circuit produced in technology integrated in the base 10.
• the use of the perforated membrane according to the invention not only makes it possible to compensate for possible differences in height of the micro-tips and possible deformations of the base supporting the micro-tips, but also to reduce the bearing force of the micro-tips on the membrane 1 .
• the flexible perforated membrane 1 described above can also be used to form elementary membranes 1 a and 1 b, in a data recording device of the type described in the patent application.
• the particular embodiment shown in Figure 10 allows to limit the side effects related to the use of a frame.
• the flexible membrane comprises a first elementary membrane 1a, associated with the frame 8 as in FIG. 9, and a second elementary membrane 1b, intended to come into contact with the network of microtips 9.
• the two elementary membranes 1a and 1b are separated by a network of spacers 11, which is offset laterally with respect to the frame 8.
• the spacers 11 have a thickness sufficient to avoid contact between the two elementary membranes during their deformation.
• the perforated membrane according to the invention can also be used, supported on studs, in the field of adaptive optics or to produce space modulators with deformable mirror.
• the flexibility introduced by the notches 2 is used to facilitate the tilting by a network of actuators of the elements of a mirror constituted by the membrane, which then comprises a reflective layer.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Computer Hardware Design (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Micromachines (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=34944625

Family Applications (1)

Country Status (5)

Citations (1)

Family Cites Families (8)

• 2004
  • 2004-04-01 FR FR0403432A patent/FR2868411B1/fr not_active Expired - Fee Related
• 2005
  • 2005-03-25 JP JP2007505577A patent/JP4762974B2/ja not_active Expired - Fee Related
  • 2005-03-25 EP EP05744606A patent/EP1730738A1/de not_active Withdrawn
  • 2005-03-25 US US10/593,976 patent/US7505394B2/en not_active Expired - Fee Related
  • 2005-03-25 WO PCT/FR2005/000716 patent/WO2005098845A1/fr not_active Ceased

Patent Citations (1)

Non-Patent Citations (1)

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