WO2002065186A2 - Micro-miroir optique a pivot, matrice de tels micro-miroirs et procede de realisation dudit micro-miroir. - Google Patents
Micro-miroir optique a pivot, matrice de tels micro-miroirs et procede de realisation dudit micro-miroir. Download PDFInfo
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- WO2002065186A2 WO2002065186A2 PCT/FR2002/000545 FR0200545W WO02065186A2 WO 2002065186 A2 WO2002065186 A2 WO 2002065186A2 FR 0200545 W FR0200545 W FR 0200545W WO 02065186 A2 WO02065186 A2 WO 02065186A2
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Classifications
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- 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
- B81B3/0062—Devices moving in two or more dimensions, i.e. having special features which allow movement in more than one dimension
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
- G02B26/08—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light
- G02B26/0816—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more reflecting elements
- G02B26/0833—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more reflecting elements the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD
- G02B26/0841—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more reflecting elements the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD the reflecting element being moved or deformed by electrostatic means
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
- B81B2201/00—Specific applications of microelectromechanical systems
- B81B2201/04—Optical MEMS
- B81B2201/045—Optical switches
-
- 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
- B81B2203/0181—See-saws
-
- 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
- the invention relates to an optical pivot micro-mirror as well as a matrix of such micro-mirrors and its production method.
- This micro-mirror is suitable for being electrically controlled.
- Micro-mirrors are generally used in systems involving deflections of light beams and in particular in optical routing systems or in image projection systems.
- micro-mirrors most often using electrostatic, electro-magnetic, piezoelectric or thermoelastic forces
- They generally use hinge configurations allowing, depending on the complexity of the technological steps involved, to oscillate around an axis (single hinge) or two axes of rotation (double hinge) most often oriented orthogonally.
- FIG. 1a shows a view of such a micromirror with electrostatic controls allowing rotation along 2 perpendicular axes, used in optical routing systems.
- the fixed frame 2 of the micro-mirror and the moving parts 3 and 4 articulated respectively around the hinges 5 and 6 which allow the desired rotations around the 2 orthogonal axes.
- Each axis of rotation passes through a separate hinge.
- the movable part 4 is covered with a layer of material of high reflectivity.
- Figure 1b gives a very schematic sectional view of the various elements forming this type of micro-mirror (section along the axis of the hinge 5). This figure also shows the different control electrodes 7, 8, 9 and 10 of the micro-mirror.
- the opposite electrodes 7 and 8 make it possible to rotate the mobile part 3 around the hinge 5, while the opposite electrodes 9 and 10 make it possible to rotate the mobile part around the hinge 6.
- the movable part of the hinged micro-mirrors has limited degrees of freedom. Indeed, each hinge can only offer one axis of rotation to the movable part, this axis being in the plane of the movable part u and passing through the hinge. Also, to increase the degrees of freedom of the mobile part, it is necessary to divide the mobile part into independent patterns, located in the same plane and respectively articulated by a hinge, which complicates the structure without allowing it a large number of degrees of freedom. Currently, only micro-mirrors with double hinges have been produced. The references cited at the end of the description give examples of hinged micro-mirrors. Statement of the invention and brief description of the figures
- the present invention relates to an optical micromirror overcoming the drawbacks of the prior art and having a movable part having a large number of axes of rotation while proposing a method of manufacturing such a micro-mirror easy to implement .
- the micro-mirror of the invention comprises a fixed part, a mobile part comprising reflection means, the micro-mirror further comprising articulation means connecting the mobile part to the fixed part;
- this micro-mirror is characterized in that the articulation means are formed by a pivot located under the movable part between the latter and the fixed part and capable of allowing movement of the mobile part along axes of rotation contained in the part movable and passing through the axis of the pivot.
- a very large number of axes of rotation for the movable part is possible, since the latter can pivot around the pivot and describe in the case of a circular movable part, a cylinder.
- the axes of rotation of the movable part correspond to all the radii describing a center semicircle, the pivot.
- the pivot is centered under the movable part, but one can completely envisage in particular applications, an off-center pivot under the movable part and ⁇ or even a movable part of thickness. not homogeneous allowing to favor certain axes of rotations and ⁇ or certain directions of rotations.
- the micro-mirror of the invention also advantageously comprises means for electrically controlling the movement of the movable part along all or part of said axes of rotation.
- the electrical control means comprise a set of so-called lower electrodes arranged on the fixed part opposite the movable part and a set of so-called upper electrodes arranged on the movable part opposite the lower electrodes.
- the set of lower electrodes comprises at least 2.n electrodes arranged in sectors around the axis of the pivot, n being the number of axes of rotation which one chooses to have the movable part take and the set of upper electrodes comprises a single electrode arranged opposite at least in part of each of the 2.n lower electrodes.
- the set of upper electrodes comprises at least 2.n electrodes arranged in sectors around the axis of the pivot, n being the number of axes of rotation which one chooses to have the movable part take and the set of lower electrodes comprises a single electrode arranged opposite at least in part of each of the 2.n upper electrodes.
- the electrical control means also comprises connection lines and contact sockets at the ends of the lines to connect the lower and upper electrodes to control electronics.
- the connection lines and the contact points are advantageously made on the fixed part opposite the mobile part, the set of upper electrodes being connected to one or more of these lines via the pivot and one or more electrodes placed under the pivot, on the fixed part.
- the connection lines are produced by metallized holes through the fixed part, the set of upper electrodes being connected to one or more of these metallized holes by means of the pivot and one or more electrodes arranged under the pivot, on the fixed part; the contact points being located at the ends of these holes on the face of the fixed part, opposite to that carrying the lower electrodes.
- the invention can also use electrical control means using other forces than electrostatic forces and for example electromagnetic, or piezoelectric or thermoelastic forces.
- forces for example, the control of the mobile parts by magnetic forces (Laplace forces) then requires coils and magnets adapted to generate the necessary magnetic fields.
- the fixed part comprises at least one cavity facing at least one zone of one of the ends of the movable part, of geometric shape and dimensions such that they make it possible to separate the parameters of dimensions of the movable part and the total angular excursion ⁇ according to the different axis or axes of rotation.
- this cavity is peripheral and is opposite a peripheral zone of the end of the movable part.
- the reflective means comprise a layer of reflective material disposed on the side of the movable part opposite to that facing the fixed part.
- the fixed part is made of silicon
- the first layer is a thermal silicon oxide
- the second layer is of monocrystalline silicon
- the pivot is of monocrystalline silicon
- the micro-mirror of the invention makes it possible in particular to increase the number of degrees of freedom, it comprises on the fixed part at least two superposed mobile parts: the first mobile part is connected to the fixed part by a first pivot comprising a first axis and the second movable part comprising reflecting means is connected to the first movable part by a second pivot comprising a second axis; this micro-mirror also comprises control means able to move the first movable part around n x axes of rotation contained in this first part and passing through the first axis and moving the second movable part, around n 2 axes of rotation contained in this second part and passing through the second axis.
- the first axis and the second axis are generally parallel. They can be the same or different.
- the control means are of the same type as those used for a single movable part but doubled.
- the first mobile part you need on the one hand at least 2.
- n! electrodes and on the other hand at least one electrode disposed respectively on the opposite faces of the fixed part and of the mobile part (or the reverse); and to control the second movable part, it therefore requires on the one hand at least 2.
- n 2 electrodes and on the other hand at least one electrode disposed respectively on the facing faces of the first movable part and of the second movable part ( or the opposite) .
- This principle can of course be generalized to a number of moving parts greater than 2, at least the last moving part comprising reflecting means.
- the pivot can be produced as well by a homogeneous pattern, as a multi-element pattern.
- a multi-element pattern can correspond to a superposition of materials both parallel to the axis of the pivot and perpendicular to this axis and making it possible to use different materials capable of imparting, by their combination, mechanical properties (mechanical strength / elasticity .%) and / or properties electrical (conduction / insulation) impossible to obtain with a single material.
- a pivot can be made with parallel conductive elements separated by insulation; these elements make it possible to independently connect several electrodes of the mobile part to independent connection lines generally via also independent electrodes placed on the fixed part, under these conductive elements.
- the invention also relates to a matrix of micro-mirrors with pivots which can be controlled independently of one another as well as to a method of manufacturing such a micro-mirror. This process allows in particular the collective realization of tnicro-
- the term matrix includes the bar which is a special case of a matrix whose elements are arranged along a single axis.
- the method of manufacturing the micro-mirror of the invention comprises the following steps: a) making a stack formed of a mechanical support intended to form the fixed part, of a layer of sacrificial material called the first layer and of an assembly intended to form the mobile part and comprising at least one layer of material, called the second layer b) making the pivot, c) making the movable part by etching at least the second layer of material, so as to obtain at least one pattern, d) eliminating the sacrificial layer so as to release said movable part which is then connected to the rest of the structure corresponding to the fixed part, by the pivot.
- the steps of the method of the invention can be carried out in the previous order or in a different order, moreover in certain embodiments some of the steps can be inserted in other steps.
- the support or the layers are not necessarily formed of a single material, thus, the support can comprise several layers and the layers can comprise several sublayers.
- the reflecting means are produced on the second layer by mono or multilayer deposition of reflecting materials such as metals for example gold, silver, aluminum or dielectrics for example Si0 2 ⁇ Ti0 2 or from
- Si0 2 ⁇ HFO 2 these materials are deposited for example by sputtering or evaporation under vacuum on the second layer generally after step b).
- the reflecting means are then produced by the second layer itself.
- the first layer is a layer of thermal oxidation material, which makes it possible to have a layer of extremely well controlled thickness which acts as a sacrificial layer.
- the value of the angular excursion of the movable part is therefore very precise and reproducible.
- the thermal oxidation layer can be partially removed; it must be engraved at least to allow the release of the movable part.
- the method further comprises a step of epitaxy of the second layer, the reflecting means then being produced on the second layer after epitaxy.
- the epitaxy of the second layer allows an increase in the thickness of this layer with the best possible mechanical continuity and the obtaining of a slightly deformable layer of high mechanical quality.
- the second layer is a layer of monocrystalline material.
- the use for the mobile part of monocrystalline materials makes it possible to obtain a great flatness of the surface on which the layer of reflectivity is arranged.
- the stacking of step a) can be obtained by producing the sacrificial layer on the support, then depositing the second layer.
- step a it is therefore possible either to carry out the stacking, or to directly take a semiconductor wafer on insulator such as SOI called "Silicon On Insolator" in English terminology, commercially available. In the latter case, at 6518
- step a) consists on the mechanical support, to transfer the second layer, the support and ⁇ or the second layer comprising on their faces to transfer a sacrificial layer which will form after transfer the first layer.
- the sealing of the transferred elements is carried out by the molecular adhesion technique.
- the second layer can be associated with an intermediate support by a connecting zone capable of allowing the withdrawal of the intermediate support after postponement or in certain specific cases before postponement.
- this bonding zone is a weakening zone obtained by ion implantation (see in particular the patents US-5,374,564 and US-6,020,252) and ⁇ or by creation of porosity in the second layer, the removal of the intermediate support is carried out according to this embrittlement zone by an appropriate treatment such as the application of mechanical forces, and ⁇ or the use of a heat treatment.
- this connection zone is a sacrificial layer which is attacked " chemically to allow removal of the intermediate support.
- the transfer technique used in this second mode allows the implementation of several plates and thus allows greater freedom for the realization of structures, which may have several mobile parts superposed.
- a localized etching of the layer or layers arranged above the support is carried out before step d), so as to form a via and an epitaxy is carried out through the via, the epitaxy material in the via forming all or part of the pivot of the articulation means.
- the pivot can be produced in several parts, in particular in the case of the second embodiment using the transfer of the second layer.
- a deposit such as an epitaxy
- a via comprising insulating meshes (each mesh corresponding to an opening bordered with insulator) so that these elements are isolated after production.
- the method of the invention involves a thinning of the second layer to reduce the inertia of the mobile part and allow the operation of the micro-mirror at high frequencies.
- This thinning of the second layer can be achieved either by the creation of a weakening zone at a depth in the second layer such that the remaining thickness, after removal of the surplus (which may be that of an intermediate support), corresponds to the desired thickness of the second layer, either by a step of reactive chemical or ionic etching or mechanical-chemical polishing up to the desired thickness or by a combination of all these techniques. If the thinning step leads to too small thicknesses of the second layer, this thickness can be re-increased during an epitaxy step.
- one or more cavities are produced in the fixed part opposite the mobile part, advantageously by etching.
- a peripheral cavity is etched, facing a peripheral zone of the end of the movable part.
- the cavity or cavities make it possible to considerably increase the possibilities of movement of the mobile part.
- any intermediate spacer layer can be avoided, the intermediate layer being able to offer only a limited clearance given its limited thickness.
- the cavities can preferably be produced during step a) of the method indicated above.
- the cavities are produced after step a) of the method, it may be advantageous to etch them from a rear part of the fixed part, that is to say from a part which does not carry the movable part.
- the method of the invention comprises a step of making the set of lower electrodes and set of upper electrodes by an ion implantation of dopants followed or not by an appropriate thermal diffusion of the implanted dopants.
- connection lines of the electrodes to a control electronics can be produced in different ways and in particular by an ion implantation of dopants followed or not by an appropriate thermal diffusion of the dopants. These lines are advantageously made on the face of the fixed part opposite the mobile part, the set of upper electrodes being connected to one or more lines by means of the pivot and of one or more electrodes placed under the pivot. on the fixed part. Contacts can also be provided at the ends of these lines for connection to the control electronics.
- connection lines of the different electrodes are produced by metallized holes through the fixed part, the set of electrodes of the mobile part being connected to one or more of these metallized holes by means of the pivot. and one or more electrodes placed under the pivot, on the fixed part; contact sockets can also be provided at the ends of these lines for connection to the control electronics.
- the method of the invention applies particularly well to a collective production of micro-mirrors.
- FIGS. 2a to 2c schematically represent, in section, different positions of a movable part connected to the fixed part by a pivot according to the principle of the micro-mirror of the invention
- FIG. 3a to 3i show schematically, in section, the different steps of a first method of manufacturing a pivot micro-mirror of the invention
- FIG. 4a to 4g show schematically, in section, the different steps a second method of manufacturing the fixed part of a micro-mirror of the invention
- FIGS. 5a to 5g schematically represent, in section, the different stages of a second method of manufacturing the movable part of a micro-mirror of the invention
- FIGS. 6a to 6e schematically represent, in section, the different stages allowing after transfer of the structures obtained in FIGS. 4g and 5g to produce a micro-mirror according to this second mode
- FIGS. 7a to 7g schematically represent, in section, the different stages of a third method of manufacturing the fixed part of a micro-mirror of the invention
- - Figures 8a to 8c show top views of different micro-mirrors of the invention showing in particular different geometries of electrodes allowing rotations around one (fig.8a), two (fig.8b) or four axes of rotation (fig. 8c), and
- FIG. 9 shows schematically, in section, a micro-mirror comprising two superposed moving parts.
- FIGS. 2a, 2b and 2c an example of a pivoting micro-mirror according to the invention is shown in three different positions.
- This micro-mirror comprises a fixed part 31 and a mobile part 41 disposed above the fixed part and connected to the latter by a pivot 47.
- the pivot is centered under the mobile part but according to the applications of the micro-mirror the pivot may not be centered.
- Lower electrodes 33 are arranged on the face of the fixed part opposite the movable part and an upper electrode 43 is arranged on the face of the movable part opposite the fixed part so that at least a part of the upper electrode is opposite at least a part of each of the lower electrodes.
- FIGS. 2 which are sections along a plane perpendicular to the plane of the layers and passing through the pivot, only two lower electrodes are represented on either side of the pivot. These electrodes are connected to connection lines 62 arranged on the same face.
- An additional electrode 33 'disposed under the pivot, on the fixed part makes it possible to connect the upper electrode via the pivot to a connection line (not present in the plane of FIGS. 2).
- the fixed part also comprises cavities 36 opposite the ends of the mobile part. These cavities are preferably peripheral and therefore only form a single cavity.
- FIG. 2a shows the mobile part arranged in a plane parallel to the plane of the support
- FIG. 2b illustrates the mobile part which has pivoted along an axis of rotation perpendicular to that of the pivot and perpendicular to the plane of the figure, one of the ends of the mobile part is located in the cavity 36
- FIG. 2c illustrates the mobile part which has pivoted around the same axis of rotation but at 180 °, the opposite end of the mobile part is in turn in the cavity 36.
- the following description sets out two methods for manufacturing a micro-mirror of the invention, knowing on the one hand that these methods allow collective production of micro-mirrors and on the other hand that numerous variants of these methods can be used without departing from the scope of the invention.
- the first process is carried out on a wafer while that the second process is carried out on two separate plates A and B then transferred.
- the description has been chosen by way of example for producing the micro-mirror, silicon for the support, the second layer and the pivot and a thermal silicon oxide for the first layer.
- the first embodiment of the micro-mirror of the invention which is implemented on a wafer is illustrated in the different figures 3.
- the thermal oxide layer is preferably produced by high temperature oxidation under a dry atmosphere (between 800 ° C and 1100 ° C under oxygen) or under a humid atmosphere (between 800 ° C and 1100 ° C under water vapor) and at atmospheric or high pressure.
- a monocrystalline silicon layer of surface 20 is then deposited by all the known deposition techniques and in particular those of the thin layer transfer.
- FIG. 3b shows the production of the electrodes of the electrical control means by the formation of different doped zones. 24, 24 'and 23 in the upper part of the undoped silicon support 21 and in the monocrystalline silicon layer of surface 20.
- zones are obtained by ion implantation of doping atoms (generally boron or phosphorus) at different energies according to the desired localization depth, followed or not by thermal annealing.
- the implantation energies will typically be between 20 and 300 keV and the doses implanted between 10 14 and 10 16 cm "2-
- the implantation energies for forming the zones 23 will be low (15 to 100 keV) whereas in the support 21, the implanted ions having to pass through the layer of silica 22 of thickness W and in part the layer of silicon 21, the implantation energies for forming the zones 24 and 24 ′ will be higher (generally greater than 100 keV).
- FIG. 3c shows the formation of the location 25 of the future pivot by local etching of the layers 20 and 22 to form a via above the implanted area 24 '.
- Figure 3d illustrates an epitaxy step. This step makes it possible both to produce the pivot in doped monocrystalline silicon and to increase the thickness of the surface silicon 20 in order to increase the mechanical rigidity of what will form the mobile part of the micro-mirror.
- the doping of the epitaxy material can be modified and for example chosen higher at the start of the process (corresponding to the formation of the pivot 27 which must be electrically 65186
- the depression 28 which may appear in this epitaxial layer results from the presence of local etching 25.
- FIG. 3e shows a section of the device after the epitaxy and thinning step, for example by mechanical-chemical polishing necessary to erase the depression 28 and obtain a layer of monocrystalline silicon 26 of perfect flatness.
- Other thinning techniques can of course be used and in particular that described in US Pat. No. 5,374,564 or in US Pat. No. 6,020,252.
- FIG. 3f shows the production of the reflection means by the formation on the layer 26 of a mirror layer of high reflectivity 29 at the wavelengths of use of the micro-mirror, for example by a metallic deposit or dielectric multilayers.
- Figure 3g illustrates the etching step of the future mobile part of the micro-mirror.
- This etching involves layers 29 and 26 and possibly the thermal silica layer 22.
- This etching is carried out for example by all types of etching adapted to the materials involved (ionic etching, reactive ionic etching and ⁇ or chemical etching).
- this etching is carried out through a mask (not shown) by a first reactive ion attack, for example with chlorinated gases to attack the aluminum, then by a second reactive ion attack using for example an SF 6 gas to attack the silicon.
- a first reactive ion attack for example with chlorinated gases to attack the aluminum
- a second reactive ion attack using for example an SF 6 gas to attack the silicon.
- FIG. 3h shows a section of the component after removal of the sacrificial layer of silica 22 at least under the mobile part of the micro-mirror and therefore the release of this mobile part.
- the removal of the layer 22 ' is carried out for example for a silicon oxide layer by a chemical attack based on hydrofluoric acid or by a reactive ionic attack based on fluorinated gases.
- FIG. 3i gives a means of circumventing this drawback by producing in the support 21 cavities 19 passing through or not, the inner edges of which are located at a distance L 'from the axis of the pivot smaller than L / 2 and the outer edges at a distance L "greater than L / 2.
- the angular excursion ⁇ defined by the tangent relation ⁇ H / L 'does not then depend on L'and no longer on L.
- This cavity can be easily produced by the rear face of the wafer, for example by preferential chemical etching as illustrated in FIG. 3i, and therefore it must pass through the thickness of the silicon support.
- FIGS. 4, 5 and 6 The second embodiment of the invention which carries out the steps of the method on two plates A and B then which transfers these plates is shown in FIGS. 4, 5 and 6.
- FIG. 4c illustrates a step of thermal oxidation of the support, intended to form a layer of thermal oxide 32 of perfectly controlled thickness and in general between 1 and 3 microns; during this step, generally carried out at high temperature, there is diffusion of dopants from the implanted zones and increase in the volume occupied by these zones.
- the steps shown in fig.4b 'and fig.4c can be reversed at the cost of increasing the implantation energies for producing the doped zones 33, 33 ′ (the implanted ions then having to pass through the layer of thermal silica).
- FIG. 4d shows the next step corresponding to the formation of the localized etching 34 of the thermal silica layer 32 above the doped zone 33 'to form a via.
- FIG. 4e illustrates an epitaxy step which makes it possible to grow monocrystalline silicon doped in via 34.
- the part of the articulation element 35 thus formed is of thickness generally very slightly greater than the thickness of the silica layer 32; this part of the element will constitute a part of the future pivot.
- FIG. 4f illustrates a mechanical-chemical polishing step intended to planarize the surface of the wafer A and "erase" the possible excess thickness of the articulation element 35.
- FIG. 4g represents a step of etching cavities 36 which make it possible to separate the dimensions of the mobile part and the maximum angular excursion ⁇ of said part.
- the dimensions (position relative to the axis of the future pivot, width and depth) of the openings 36 are determined from the dimensions of the mobile part and of the desired angular excursion ⁇ along the different axes of rotation.
- the cavities 36 can have a thickness much less than the thickness of the support 31.
- These cavities can be of any shape and in particular surround the pivot.
- FIGS. 5 show the different stages of manufacturing the wafer B.
- a substrate 41 for example made of monocrystalline silicon, in which an electrode 43 is formed, for example by ion implantation (fig. 5b) whether or not followed by thermal annealing.
- a thermal oxide layer 42 (fig.5c) is formed in the same way as for layer 32.
- This layer 42 is then etched to form a via 44 (fig.5d) which extends to l 'electrode 43; this opening has dimensions very close to those of the opening 34 (fig.4d); an epitaxy step (fig.5e) from monocrystalline silicon then makes it possible to form in the opening 44 another part of the pivot which is made of doped monocrystalline silicon 45.
- a chemical mechanical polishing step (fig.5f) allows if necessary to obtain a perfect planarization of the surface of the wafer B.
- the step illustrated in FIG. 5g consists in creating a connection zone 46 in the wafer 41 such as a weakening zone created for example by implantation of ions.
- This zone delimits in the wafer a layer (previously called second layer) of thickness typically between 0.1 and 2 microns between the silica layer 42, and the rest of the wafer (which may be an intermediate support).
- This weakening zone makes it possible to separate the second layer, from the rest of the wafer, either before transfer but more generally after transfer (see in particular US Patents 5,374,564 and US 6,020,252).
- Assembly of plates A and B The first step illustrated in Figure 6a consists in assembling the two plates A and B with the oxidized side against the oxidized side. During this assembly, the positioning of the two plates is carried out so as to align the two parts of the pivot 35 and 45 and form the pivot 47.
- the sealing can favorably be carried out by known techniques of molecular adhesion.
- the upper part of the layer 41 of the wafer B is separated from the assembly A and B at the level of the weakened zone 46.
- This separation can favorably be made from a heat treatment. and ⁇ or mechanical. After this separation, there remains, see FIG. 6b, only a thin layer of monocrystalline silicon 41 ′ possibly comprising zones of different dopings.
- the method can also comprise (see FIG. 6 c) an epitaxy step intended to increase the thickness of the monocrystalline film 41 ′ in order to increase the mechanical rigidity of what will form the movable part of the mirrors, this step can be followed by a chemical mechanical polishing step to planarize the surface.
- the final thickness of this layer 41 ′ is for example from 5 to 60 ⁇ m.
- a layer 48 of high reflectivity at the optical working wavelengths, either metallic or multi-dielectric, is then deposited on the layer 41 '.
- FIG. 6d shows the next step of etching the layers 41 ′ and 48 according to the desired pattern for the mobile part of the future micro-mirror. This engraving is carried out through a mask not shown.
- FIG. 6e illustrates the step of releasing the movable part around the pivot 47 by removing the sacrificial layers of thermal silica by chemical attack, for example using an attack bath using hydrofluoric acid or a reactive ion attack based on fluorinated gases.
- the different manufacturing steps presented in the various Figures 3 to 6 can include many variants. In particular, the order of the different steps can in certain cases be reversed and some of the steps can be modified.
- connection lines and the contact points to control electronics can be produced in different ways and in particular by ion implantation followed or not by an appropriate thermal diffusion of the dopants. These lines are advantageously made on the front face of the support opposite the mobile part, the electrode of the mobile part being connected to some of these lines by means of the pivot when the latter is conductive and of the electrode 33 . These connection lines can also be produced by metallized holes through the support, the electrode of the movable part being connected to some of these metallized holes by means of the pivot when the latter is conductive and of the electrode 33 .
- FIG. 4g shows in dotted lines the embodiment through the support of metallized holes 70 connecting the electrodes 33 and 33 ′ to contact sockets 71.
- the micro-mirror When the micro-mirror must rotate around at least two perpendicular axes of rotation while retaining the advantage of separating the value of the angular excursion ⁇ , from the dimension L of the movable part, it is advantageously carried out in the support, cavities completely surrounding the pivot 47.
- the connection lines are made on the front face of the support, so as not to cut through the cavities, the electrical connection lines (shown by way of example in the figures 9 and designated by 62) supplying the various electrodes, the support is etched to forming a peripheral cavity before forming the doped zones 33 33 '.
- Figures 7 illustrate this variant of the process.
- a cavity 36 is formed by etching carried out by different methods such as reactive ion etching (corresponding to the shape of the cavity in FIG. 3g) where the preferred chemical etching (corresponding to the shape of the cavity in Figure 7b).
- the geometry (shapes and dimensions) of the cavity 36 is determined from the shape (which can be circular, square, rectangular, octagonal ...) and the dimensions of the mobile part of the micro-mirror and the value of the total angular excursion ⁇ desired along the different axes of rotation; the value of the total angular excursion ⁇ can also take different values ⁇ i, ⁇ 2 ...
- FIG. 7c embdiments of the doped zones
- FIG. 7d production of the thermal oxide
- FIG. 7e production of a via 34 in the oxide layer
- FIG. 7f epitaxy to produce a part of the pivot
- Figure 7g planarization of the structure
- the following is then transferred to the wafer obtained in FIG. 7g, for example the wafer obtained in FIG. 5g and the rest of the steps of the process are carried out as described with reference to FIGS.
- the micro-mirror obtained is for example that shown in FIGS. 2.
- FIG. 8a shows a top view of a geometry of lower electrodes 33 in the fixed part.
- the electrodes allowing the mobile part to oscillate in 2 positions around a single axis of rotation RI are 2 in number and are arranged symmetrically with respect to the axis of rotation RI which passes through the pivot 47, the electrode 33 'central only allows the electrical connection of the mobile part.
- FIG. 8b shows a geometry of lower electrodes 33 making it possible to obtain 4 positions around 2 perpendicular axes of rotation RI and R2 passing through the pivot; these electrodes 33 are 4 in number and are matched 2 to 2, each pair of electrodes being arranged symmetrically with respect to one of the axes; similarly, the central electrode 33 ′ only allows the electrical connection of the mobile part.
- FIG. 8c gives an example with 4 axes of rotation (RI, R2, R3, R4) at 45 ° from each other and 4 pairs of lower electrodes 33 arranged in sectors around the axis of the pivot.
- FIGS. 8a, 8b and 8c the various key elements of the micro-mirrors are shown in transparency. There is shown the sets of lower electrodes 33 (electrodes of the fixed part), and the upper electrode 43 (electrode of the mobile part); the lower electrode 33 'which is electrically connected to the upper electrode by the pivot 47 is drawn in dark gray while in FIG.
- the two sets of electrodes allowing the rotation control of the micro-mirror along each of the perpendicular axes of rotation are drawn with two shades of gray which are lighter but different.
- the reflecting surface 48 of the movable part and the traces 50 and 51 of the etched areas 36 allowing the separation of the dimensions variables of the micro-mirror and total angular excursion ⁇ are also shown.
- connection lines 62 from the electrodes to the contact sockets 60 are also shown very schematically, these contact sockets being able to be connected to a control electronics (not shown).
- FIG. 9 represents a schematic section of an example of micro-mirror with 2 moving parts on a fixed part 31.
- the first movable part comprises a second layer 41; it is connected to the fixed part by a pivot 47.
- the second movable part comprises a second layer 71 and a reflective layer 78; it is connected to the first mobile part by a pivot 77.
- the movable part 71 comprises an electrode 73 and the movable part 41 comprises electrodes 53 arranged in sector around the pivot 77, the electrodes 73 and 53 being arranged opposite; in addition, the movable part 41 includes electrodes 43 arranged in sector around the pivot 47, these electrodes being arranged opposite the electrodes 33 of the fixed part.
- the axes of the pivots 47 and 77 are combined; these pivots are multi-element and allow the electrodes 73, 53 and 43 of the mobile parts 41 and 71 to be connected to control electronics, via connection lines 62 arranged on the fixed part.
- This principle can of course be generalized to a number of moving parts greater than 2.
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Mechanical Light Control Or Optical Switches (AREA)
- Micromachines (AREA)
Abstract
Description
Claims
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2002564645A JP2004522996A (ja) | 2001-02-15 | 2002-02-13 | 旋回する光マイクロミラー、マイクロミラーのマトリックス、およびマイクロミラーの製造方法 |
EP02704815A EP1390793A2 (fr) | 2001-02-15 | 2002-02-13 | Micro-miroir optique a pivot, matrice de tels micro-miroirs et procede de realisation dudit micro-miroir. |
CA002437816A CA2437816A1 (fr) | 2001-02-15 | 2002-02-13 | Micro-miroir optique a pivot, matrice de tels micro-miroirs et procede de realisation dudit micro-miroir. |
US10/468,060 US20040061961A1 (en) | 2001-02-15 | 2002-02-13 | Pivoting optical micromirror, array for such micromirrors and method for making same |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR01/02065 | 2001-02-15 | ||
FR0102065A FR2820833B1 (fr) | 2001-02-15 | 2001-02-15 | Micro-miroir optique a pivot, matrice de tels micro-miroirs et procede de realisation dudit micro-miroir |
Publications (2)
Publication Number | Publication Date |
---|---|
WO2002065186A2 true WO2002065186A2 (fr) | 2002-08-22 |
WO2002065186A3 WO2002065186A3 (fr) | 2003-11-27 |
Family
ID=8860053
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/FR2002/000545 WO2002065186A2 (fr) | 2001-02-15 | 2002-02-13 | Micro-miroir optique a pivot, matrice de tels micro-miroirs et procede de realisation dudit micro-miroir. |
Country Status (6)
Country | Link |
---|---|
US (1) | US20040061961A1 (fr) |
EP (1) | EP1390793A2 (fr) |
JP (1) | JP2004522996A (fr) |
CA (1) | CA2437816A1 (fr) |
FR (1) | FR2820833B1 (fr) |
WO (1) | WO2002065186A2 (fr) |
Families Citing this family (13)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2002258174A (ja) * | 2001-03-02 | 2002-09-11 | Seiko Epson Corp | 光変調装置及びそれを有する電子機器 |
US6912336B2 (en) * | 2002-03-15 | 2005-06-28 | Nippon Telegraph And Telephone Corporation | Optical switch device |
US6800212B2 (en) * | 2002-05-15 | 2004-10-05 | The Regents Of The University Of California | Fabrication of optical components using Si, SiGe, SiGeC, and chemical endpoint detection |
US20050094241A1 (en) * | 2003-11-01 | 2005-05-05 | Fusao Ishii | Electromechanical micromirror devices and methods of manufacturing the same |
US7183618B2 (en) * | 2004-08-14 | 2007-02-27 | Fusao Ishii | Hinge for micro-mirror devices |
US7209290B2 (en) * | 2004-05-25 | 2007-04-24 | Samsung Electro-Mechanics Co., Ltd. | Diffractive thin-film piezoelectric micromirror and method of producing the same |
US7372617B2 (en) * | 2005-07-06 | 2008-05-13 | Peter Enoksson | Hidden hinge MEMS device |
KR100709325B1 (ko) | 2005-11-16 | 2007-04-20 | 삼성전자주식회사 | 마이크로 미러 액튜에이터 |
US7598688B2 (en) * | 2006-06-22 | 2009-10-06 | Orbotech Ltd | Tilting device |
JP2009233836A (ja) * | 2008-03-28 | 2009-10-15 | Yamaha Corp | Memsおよびmems製造方法 |
JP6106970B2 (ja) * | 2012-07-02 | 2017-04-05 | 株式会社ニコン | 空間光変調器および露光装置 |
JP2014203844A (ja) * | 2013-04-01 | 2014-10-27 | 株式会社東芝 | Mems装置及びその製造方法 |
CN109991730B (zh) * | 2019-03-12 | 2021-06-15 | 上海集成电路研发中心有限公司 | 一种微镜结构 |
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US3886310A (en) * | 1973-08-22 | 1975-05-27 | Westinghouse Electric Corp | Electrostatically deflectable light valve with improved diffraction properties |
US5096279A (en) * | 1984-08-31 | 1992-03-17 | Texas Instruments Incorporated | Spatial light modulator and method |
Family Cites Families (12)
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US5620931A (en) * | 1990-08-17 | 1997-04-15 | Analog Devices, Inc. | Methods for fabricating monolithic device containing circuitry and suspended microstructure |
DE4229507C2 (de) * | 1991-10-30 | 2002-03-07 | Cms Mikrosysteme Gmbh | Mikromechanischer 3-D-Aktor |
EP0539889A3 (en) * | 1991-10-30 | 1993-07-28 | Steinbichler, Hans, Dr. | Micromechanical actuator |
US5212582A (en) * | 1992-03-04 | 1993-05-18 | Texas Instruments Incorporated | Electrostatically controlled beam steering device and method |
US5708521A (en) * | 1993-05-04 | 1998-01-13 | Daewoo Electronics Co., Ltd. | Actuated mirror array for use in optical projection system |
US5629790A (en) * | 1993-10-18 | 1997-05-13 | Neukermans; Armand P. | Micromachined torsional scanner |
US5485304A (en) * | 1994-07-29 | 1996-01-16 | Texas Instruments, Inc. | Support posts for micro-mechanical devices |
KR100243190B1 (ko) * | 1996-06-10 | 2000-02-01 | 윤종용 | 가동미러장치 및 그 제조방법 |
US6061323A (en) * | 1996-07-30 | 2000-05-09 | Seagate Technology, Inc. | Data storage system having an improved surface micro-machined mirror |
DE19712201A1 (de) * | 1997-03-24 | 1998-10-01 | Bodenseewerk Geraetetech | Mikromechanische Spiegel-Anordnung |
DE19800745A1 (de) * | 1998-01-12 | 1999-07-15 | Bosch Gmbh Robert | Design- und Herstellungsverfahren für eine mikromechanische Vorrichtung |
US6020272A (en) * | 1998-10-08 | 2000-02-01 | Sandia Corporation | Method for forming suspended micromechanical structures |
-
2001
- 2001-02-15 FR FR0102065A patent/FR2820833B1/fr not_active Expired - Fee Related
-
2002
- 2002-02-13 CA CA002437816A patent/CA2437816A1/fr not_active Abandoned
- 2002-02-13 US US10/468,060 patent/US20040061961A1/en not_active Abandoned
- 2002-02-13 EP EP02704815A patent/EP1390793A2/fr not_active Withdrawn
- 2002-02-13 WO PCT/FR2002/000545 patent/WO2002065186A2/fr not_active Application Discontinuation
- 2002-02-13 JP JP2002564645A patent/JP2004522996A/ja not_active Withdrawn
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US3886310A (en) * | 1973-08-22 | 1975-05-27 | Westinghouse Electric Corp | Electrostatically deflectable light valve with improved diffraction properties |
US5096279A (en) * | 1984-08-31 | 1992-03-17 | Texas Instruments Incorporated | Spatial light modulator and method |
Non-Patent Citations (1)
Title |
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See also references of EP1390793A2 * |
Also Published As
Publication number | Publication date |
---|---|
FR2820833A1 (fr) | 2002-08-16 |
US20040061961A1 (en) | 2004-04-01 |
JP2004522996A (ja) | 2004-07-29 |
FR2820833B1 (fr) | 2004-05-28 |
WO2002065186A3 (fr) | 2003-11-27 |
EP1390793A2 (fr) | 2004-02-25 |
CA2437816A1 (fr) | 2002-08-22 |
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