US20060038103A1 - Deformable mirror method including bimorph flexures - Google Patents
Deformable mirror method including bimorph flexures Download PDFInfo
- Publication number
- US20060038103A1 US20060038103A1 US11/260,999 US26099905A US2006038103A1 US 20060038103 A1 US20060038103 A1 US 20060038103A1 US 26099905 A US26099905 A US 26099905A US 2006038103 A1 US2006038103 A1 US 2006038103A1
- Authority
- US
- United States
- Prior art keywords
- layer
- mirror
- forming
- flexure
- flexures
- 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.)
- Abandoned
Links
Images
Classifications
-
- 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
- G02B26/06—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the phase of light
-
- 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
- G02B26/0825—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 flexible sheet or membrane, e.g. for varying the focus
Abstract
An apparatus comprising a substrate; and a platform elevated above the substrate and supported by curved flexures. The curvature of said flexures results substantially from variations in intrinsic residual stress within said flexures. In one embodiment the apparatus is a deformable mirror exhibiting low temperature-dependence, high stroke, high control resolution, large number of degrees of freedom, reduced pin count and small form-factor. Structures and methods of fabrication are disclosed that allow the elevation of mirror segments to remain substantially constant over a wide operating temperature range. Methods are also disclosed for integrating movable mirror segments with control and sense electronics to a produce small-form-factor deformable mirror.
Description
- This application claims the benefit of U.S. Provisional Patent Application No. 60/425,049 entitled Reduced Rotation MEMS Deformable Mirror Apparatus and Method, and U.S. Provisional Patent Application No. 60/425,051 entitled Deformable Mirror Method and Apparatus Including Bimorph Flexures and Integrated Drive, both filed Nov. 8, 2003.
- 1. Field of the Invention
- This invention relates to a methods and structures for elevating a platform above a substrate and for producing a controlled motion of that platform. It also relates to MEMS deformable mirror (“DM”) arrays, and more particularly to long-stroke MEMS deformable mirror arrays for adaptive optics applications.
- 2. Description of the Related Art
- Adaptive optics (“AO”) refers to optical systems that adapt to compensate for disadvantageous optical effects introduced by a medium between an object and an image formed of that object. Horace W. Babcock proposed the concept of adaptive optics in 1953, in the context of mirrors capable of being selectively deformed to correct an aberrated wavefront. See John W. Hardy, Adaptive optics for astronomical telescopes, Oxford series in optical and imaging sciences 16, Oxford University Press, New York, 1998. Since then, deformable mirrors (DM) have been proposed for a variety of AO applications, although they have yet to be implemented in many such proposed applications.
- The general operation of a DM is shown schematically in
FIG. 1 , in which aDM 100 reflects anaberrated wavefront 105, resulting in a desiredplanar wavefront 110. The DM shape is dynamically adapted to correct the path-length variations of the inbound aberrated wavefront. That is, by selectively deforming the mirror to decrease or increase the path length for specific portions of the aberrated wavefront, the aberrations in the reflected wavefront are corrected. The amount of local displacement needed of the DM surface is generally approximately equal to half the path-length variations in the aberrated wavefront. The exact scale factor depends on the angle at which the aberrated wavefront strikes the deformable mirror. - A prior art AO system is shown schematically in
FIG. 2 . This example is particularly related to an astronomical telescope application, but the general principles of AO shown here are illustrative of other applications. InFIG. 2 , anaberrated wavefront 105 enters theoptical system 205 where it is modified as it reflects off aDM 100. Aberrations in the wavefront reflected from the DM are the error signal for a computer-controlled feedback loop. Thereflected wavefront 110 enters adichroic beam splitter 220; the infrared wavelengths pass to ascience camera 225 and the visible wavelengths reflect toward awavefront sensor 230. The wavefront sensor measures the wavefront slope at discrete points and sends these data to awavefront reconstructor 235. Thewavefront reconstructor 235 determines the remaining wavefront aberrations in the corrected wavefront. Anactuator control block 240 calculates actuator drive signals to correct the remaining wavefront errors, which are sent from theblock 240 to theDM 100, thus dosing the feedback loop. In this way, the DM is continuously driven in such a way as to minimize the aberrations in the reflected wavefront, thereby improving image resolution at the science camera. - AO systems have been proposed and demonstrated for improving resolution in a number of imaging applications. In astronomy, for example, AO has been used to correct aberrations introduced by motion of the atmosphere, allowing ground-based telescopes to exceed the resolution provided by the Hubble Space Telescope under some observing conditions. In the field of vision science, AO has been shown to offer benefits, for example, for in-vivo retinal imaging in humans. Here, AO systems can compensate for the aberrations introduced by the eye, improving lateral image resolution by a factor of three and axial resolution by a factor of ten in confocal imagers. This has allowed individual cells to be resolved in living retinal tissue, a capability that was not present before the advent of AO.
- In addition to improving image resolution, AO systems can be used to improve confinement of a projected optical beam traveling through an aberrating medium. Examples of applications in this category are free-space optical communication, optical data storage and retrieval, scanning retinal display, and laser-based retinal surgery.
- A number of characteristics are commonly used to compare performance of DM designs. Fill-factor is the fraction of the DM aperture that is actively used to correct wavefront aberrations. Mirror stroke is the amount of out-of-plane deformation that can be induced in the DM surface. The number of degrees-of-freedom is a measure of the spatial complexity of the surface shapes the DM is capable of assuming and is related to the number of individual actuators that are used to deform the mirror surface. DM aperture diameter, DM device size, control resolution, operating temperature range, power consumption, frequency response and price are also generally considered when selecting a DM for a given application. For example, astronomical imaging typically requires mirror stroke in the range of a few micrometers, frequency responses in the kilohertz range and aperture sizes on the order of a few centimeters to a few meters. Systems for imaging structures in the human eye, by contrast, generally require mirror stroke on the order of 10 micrometers or greater, frequency responses in the tens to hundreds of Hertz range, and aperture sizes on the order of one centimeter or less.
- Despite the advantages outlined above, AO has not been universally adopted, even in the aforementioned applications. Two important factors that have impeded the widespread adoption of AO are the high cost and limited stroke of available DMs.
- DM designs can be broadly divided into two classes; continuous-face-sheet designs and segmented designs. Continuous-face-sheet DMs have a reflective surface that is continuous over their whole aperture. The surface is deformed using actuators, typically mounted behind it, that push or pull on it to achieve a desired deformation. This type of DM has been implemented, for example, by mounting an array of piezoelectric actuators to the rear surface of a somewhat flexible glass or ceramic mirror. Because the optical surface is continuous and rather inelastic, large actuation forces are required to deform the mirror, and the resulting mirror stroke is small, typically less than 5 micrometers. The continuous surface also means that the deformation produced by each actuator is not tightly confined to the area of the mirror directly connected to it, but instead may extend across the whole mirror aperture, making precise control of the overall mirror deformation problematic. Because of the way they are constructed, such DMs are also comparatively large, having apertures on the order of 50 mm or greater. This large size precludes their deployment in many optical systems that might otherwise benefit from AO. Their fabrication methods also make these DMs expensive to manufacture and do not permit easy integration of control electronics into the DM structure.
- A number of continuous-face-sheet DMs using microfabrication techniques that offer the potential to reduce DM size and cost have been created. Vdovin and Sarro, in “Flexible mirror micromahined in silicon”, Applied Optics, vol. 34, no. 16 (1995), disclose a DM fabricated by assembling a metal-coated silicon nitride membrane above an array of electrodes that are used to deform the membrane by electrostatic attraction.
- Bifano et al. disclose an alternative microfabricated continuous-face-sheet DM in “Microelectromechanical Deformable Mirrors”, IEEE Journal of Selected Topics in Quantum Electronics, vol. 5 no. 1 (1999). Their design relies on the removal of a sacrificial layer to create cavities underneath the mirror surface that define the maximum travel range of each mirror actuator.
- U.S. Pat. No. 6,384,952 to Clark et al. (2002) discloses a continuous-face-sheet DM that employs a mirrored membrane fabricated, for example, from metal-coated silicon nitride and actuated by an array of vertical comb actuators disposed underneath the membrane. Use of vertical comb actuators can provide higher force for a given applied voltage than the parallel plate electrostatic actuators used in other continuous-face-sheet designs.
- In contrast to the continuous-face-sheet designs discussed above, segmented DM designs divide the DM aperture into a number of generally planar mirror segments, the angle and height of each segment being controlled by a number of actuators. Segmented designs are advantageous in that they allow the area of influence of each actuator to be tightly confined, simplifying the problem of driving the mirror to a particular desired deformation. Segmenting the mirror surface also eliminates the need to deform a comparatively inflexible optical reflector to produce a desired DM surface shape. Rather, the individual mirror segments are tilted, raised and lowered to form a piecewise approximation of whatever deformation is required to correct the aberrations of the incoming wavefront. Segmenting the surface can therefore result in a lower force requirement for a given surface deformation, enabling the high-stroke DMs that are needed for many AO applications.
- A number of inventors have disclosed segmented DM designs that may be constructed using microfabrication techniques. U.S. Pat. No. 6,175,443 to Aksyuk et al. (2001) discloses an array of conductive mirror elements, connected together by linking members that act as supports, suspending the mirror array above an actuating electrode. These linking members also serve to keep the mirror array in an approximately planar configuration when no actuating voltage is applied. Energizing the electrode results in an attractive force between it and the mirror segments, deforming the array into a curved configuration.
- U.S. Pat. No. 6,028,689 to Michalicek et al. (2000) discloses an array of mirror segments attached to a substrate by posts, each segment capable of tilting about two axes and also moving vertically, perpendicular to the array, under the influence of applied control voltages.
- U.S. Pat. No. 6,545,385 to Miller et al. (2003) discloses methods for elevating a mirror segment above a substrate by supporting it on flexible members that can bend up out of the substrate plane. This provides a large cavity underneath the mirror segment, not limited by the thickness of the sacrificial materials used in its fabrication, and offering the potential for large mirror stroke.
- Helmbrecht, in “Micrmirror Arrays for Adaptive Optics”, PhD. Thesis, University of California, Berkeley (2002), discloses a segmented DM for use in AO applications, that exhibits high fill-factor, high mirror quality and offers the potential for high mirror stroke.
- It is therefore an object of the present invention to provide improved methods and structures for elevating a platform above a substrate and for precisely controlling the tip, tilt and piston motion of that platform.
- A further object of the invention is to provide a high-degree-of-freedom DM which can be used to compensate for large optical wavefront aberrations, without the need for temperature control or monitoring.
- Another object of the invention is to provide a high-degree-of-freedom, high-stroke DM with integrated control electronics in a small form-factor configuration.
- A further object of the invention is to provide a high-degree-of-freedom, high-stroke DM with integrated sense electronics in a small form-factor configuration.
- Yet another object is to provide a high-degree-of-freedom DM with a greatly reduced control-pin count.
- A further object of the invention is to provide a small-form-factor DM that can be used in clinical ophthalmic instruments to correct wavefront aberrations of the human eye.
- A further object of the invention is to provide a high-degree-of-freedom, high-stroke DM that can be fabricated at low cost.
- A further object of the invention is to provide a temperature-insensitive, high-fill-factor, segmented piston-tip-tilt DM, having segments with improved optical flatness.
- Yet another object of the invention is to provide a highly-reliable DM, capable of operating over many millions of actuation cycles.
- A further object of the invention is to provide a high-degree-of-freedom DM comprising actuators that may be operated largely independently, in order to provide correction for different areas of an optical wavefront.
- A further object of the invention is to provide a DM that can be batch fabricated using IC-compatible fabrication methods and materials.
- A further object of the invention is to provide a high-degree-of-freedom DM with reduced power consumption.
- In accordance with the above objects, the invention, roughly described comprises an apparatus including a substrate and a platform elevated above the substrate and supported by curved flexures, wherein the curvature of said flexures results substantially from variations in intrinsic residual stress within said flexures.
- In another embodiment, the invention comprises a tiled array of mirror segments, each supported by a number of curved flexures attached, at one end, to the underside of the segment and, at the other end, to a substrate. A number of independently addressable actuators are used to apply forces to each mirror segment, causing it to move in a controlled manner. The application points of the actuating forces and the locations of the support flexures are placed so as to allow each segment to be tilted about two distinct axes substantially parallel to the substrate and translated along an axis substantially perpendicular to the substrate. The invention may optionally include electronic circuits embedded in the substrate for the purpose of addressing the individual actuators and/or sensing the state of a given mirror segment. The invention includes methods and structures for improved flexures for supporting and elevating the segments above the substrate. More particularly, the invention provides methods and apparatus for fabricating mirror segments supported by curved flexures, the curvature of which is induced, principally or entirely, by variations in intrinsic residual stress through the thickness of the flexure material or materials. The invention also includes methods for separately fabricating the MEMS portion of the inventive apparatus and the electronics portion, and then integrating the two to form the apparatus.
-
FIG. 1 : Illustration of prior art use of a deformable mirror to correct an aberrated wavefront. -
FIG. 2 : Illustration of prior art adaptive optic (AO) system. -
FIG. 3A : Partial cutaway perspective view of a first embodiment of the invention. -
FIG. 3B : Perspective view of the improved flexure according to a first embodiment of the invention. -
FIG. 4A : Flow diagram of the process steps required to fabricate a first embodiment of the invention. -
FIG. 4B : Schematic cross-sections through structures fabricated at various process steps in a first embodiment of the invention. -
FIG. 5 : Schematic cross-section through the MEMS structures for a single mirror segment in a first embodiment of the invention. -
FIG. 6 : Schematic cross-section through the portion of the CMOS substrate underlying a single mirror segment in a first embodiment of the invention. -
FIG. 7A : Schematic cross-section through a single mirror segment and underlying structures before MEMS release and passivation layer removal in a first embodiment of the invention. -
FIG. 7B : Schematic cross-section through a single mirror segment and underlying structures after MEMS release and passivation layer removal, in a first embodiment of the invention. -
FIG. 8 : Table of coefficients of thermal expansion for several candidate materials for construction of curved flexures. -
FIG. 9 : Partially exploded perspective view of a third embodiment of the invention. - Methods and structures for elevating one or more platforms above a substrate and for controlling the tip, tilt and piston motion of those platforms with high precision are hereinafter described. Several embodiments are described in which a plurality of such platforms are tiled to form a large-stroke segmented piston-tip-tilt deformable mirror
-
FIG. 3A shows a partial cutaway perspective view of a first embodiment of a DM incorporating the improved methods and structures. The DM is formed on asubstrate 300, which may be a silicon wafer or chip containing embedded addressing and sensing circuits (not shown). On top of thesubstrate 300 are formed a number ofcontrol electrodes 370 that are electrically isolated from one another and electrically connected to the embedded addressing and sensing circuits. In the first embodiment, thecontrol electrodes 370 are arranged in groups of three and are rhombic in shape, so that the footprint of each group is essentially hexagonal. Disposed around each group of threecontrol electrodes 370, are threeconductive ground pads 310, fabricated from the same material as thecontrol electrodes 370. Theground pads 310 are electrically isolated from thecontrol electrodes 370 and electrically connected to a ground plane or to circuits embedded in thesubstrate 300. Attached to one end of eachground pad 310 is afirst anchor portion 350 of aflexure 320. The flexure, in the first embodiment comprises two layers, afirst flexure layer 330 formed from conductive polycrystalline silicon and asecond flexure layer 340 formed from silicon nitride (SixNy). Thefirst anchor portion 350 is both mechanically and electrically connected to theground pad 310 so that the conductivefirst flexure layer 330 is held at the same electrical potential as theground pad 310. Thesecond flexure layer 340 is rigidly attached to the underside of thefirst flexure layer 330 and extends over a portion of the length of theflexure 320. The purpose of the second flexure layer is to provide a residual stress difference between the top and bottom portions of theflexure 320, causing theflexure 320 to bend up out of the plane of thesubstrate 300. - The end of the
flexure 320 opposite thefirst anchor portion 350 terminates in asecond anchor portion 360.FIG. 3B is a detail perspective view of oneflexure 320, showing thefirst anchor portion 350, thesecond anchor portion 360, thefirst flexure layer 330, thesecond flexure layer 340, and theground pad 310 underlying the flexure. - Referring again to
FIG. 3A , thesecond anchor portion 360 is mechanically and electrically connected to the underside of amirror segment 380. The mirror segment is any one individual mirror of the DM device. Thus themirror segment 380 is held at some elevation above thesubstrate 300. In the first embodiment, this elevation is on the order of 50 micrometers. The mirror segment is electrically conductive and therefore is held at the same potential as theground pad 310. In the first embodiment, themirror segment 380 is hexagonal in shape and is formed from a 20 micrometer-thick layer of single crystal silicon and is coated on its top surface with an optical coating, which may be a highly reflective metal layer. The mirror segment diameter in the first embodiment is on the order of 500 micrometers. - For the sake of clarity,
FIG. 3A shows only threemirror segments 380. However, an exemplary embodiment of the DM comprises an array of 121 nominally identicalelevated mirror segments 380 disposed over the substrate so as to form a larger, segmented mirror surface, approximately circular in outline and having inter-segment gaps of 5 micrometers. - The following is a general overview of the process of the current invention for fabricating the first embodiment of the DM. The process involves separately fabricating the MEMS structure and the addressing and sensing circuits on two separate wafers, then assembling them together as shown in
FIGS. 4A and 4B .FIG. 4A is a process flow diagram andFIG. 4B illustrates the corresponding structure at each step. As shown atstep 400, eachmirror segment 380 is fabricated by reactive ion etching (RIE) the top single crystal silicon “device” region of a bonded silicon-on-insulator wafer (BSOI). Atstep 405, the wafer is then coated with a sacrificial layer to fill the trenches left by the previous etch, provide a temporary support for various mechanical structures of the DM, and optionally to act as a dopant source for undoped polysilicon regions. This sacrificial layer might typically be phosphorus-doped silicate glass deposited by low pressure chemical vapor deposition (LPCVD). Alternatively, in cases where the sacrificial layer is not required to act as a dopant source, silicon oxide deposited by a tetraethoxysilane (TEOS) process might be used. - As shown at
step 410, the PSG region is next patterned to define the attachment points for thesecond anchor portions 360 of the flexures; in some instances the patterning may include an etching step. Atstep 415, a one micron undoped amorphous polysilicon layer and a PSG layer are deposited by LPCVD and annealed at 950° C. for six hours to dope and tune the residual stress of the polysilicon layer to approximately −40 MPa, where the negative sign denotes compressive stress. The top PSG layer is then removed atstep 420 using a wet hydrofluoric (HF) acid etch and the polysilicon layer is patterned and etched to define thefirst flexure layer 330 atstep 425. Silicon nitride (SixNy) is then deposited by LPCVD atstep 430, and patterned and etched to define thesecond flexure layer 340 atstep 435. Atstep 437, conductive metal pads are deposited, for example by electroplating, on to thefirst anchor portion 350 of the flexures. These metal pads will serve as the electrical and mechanical attachment points between the flexures and thesubstrate 300. -
FIG. 5 schematically illustrates a cross-section through theMEMS structure 500 supporting a single mirror segment, completed up to this point and including themirror segment 380,flexure 320 and thesacrificial layer 515, typically phosphorus-doped silicate glass (PSG). As compared with the structure shown at thelast step 437 ofFIG. 4B-1 , the structure shown inFIG. 5 has been inverted in preparation for bonding to the electronics chip. In the first embodiment, theflexure 320 is a two-layer structure with afirst flexure layer 330 of phosphorus-doped polysilicon, and asecond flexure layer 340 of SixNy. Although not required in all embodiments, the MEMS device in the first embodiment includes a temporary handle wafer (not shown inFIG. 5 ), typically 300 to 500 micrometers thick, used to support the MEMS structure prior to release in a manner known in the art. - Continuing again with reference to process
steps 445 onwards, shown inFIGS. 4A and 4B , drive circuitry in the form of an integrated circuit is now introduced. This integrated circuit is thesubstrate 300 on which the flexures and mirror segments will be mounted. Thesubstrate 300 is typically fabricated through separate processing in a conventional manner, for example using silicon CMOS techniques not shown here, and well known in the art. As shown atstep 445 inFIG. 4 , thesubstrate 300 is typically coated with a passivation layer to protect it from the MEMS release agent, which may for example be hydrofluoric acid. As shown instep 447 ofFIG. 4 , the passivation layer is patterned and etched to expose bond sites on thesubstrate 300 that are electrically connected to a ground plane or to underlying circuits. An electricallyconductive bonding agent 610 is then deposited on these bond sites.FIG. 6 is a schematic cross-section through the substrate at the end ofstep 447, showing the locations of thecontrol electrodes 370, thebonding agent 610 and thewiring layer 625. - Continuing to refer to
FIG. 4 , atstep 450 theMEMS structure 500, constructed as described above, is disposed over thesubstrate 300 and the two are then bonded together. At this point theMEMS structure 500 still includes thesacrificial layer 515. - At
step 455 the handle wafer of the BSOI wafer is etched away from the MEMS mirror segment, after which the sacrificial layer is released from the MEMS structure as shown atstep 460. The IC passivation layer is removed atstep 465, typically using an O2 plasma or appropriate solvent. Finally, an optical coating is deposited on the top surface of the mirror segments, for example using a shadow-masked metal evaporation, instep 470. The resulting device is a completed, integrated DM.FIG. 7A shows a cross-section through a single mirror segment and underlying structures, after removal of the handle wafer atstep 455.FIG. 7B shows a cross section through the same structure at the end of the fabrication process, after the MEMSsacrificial layer 515 and circuitry passivation layer have been removed. The device includes the following elements: IC portion orsubstrate 300 andMEMS structure 500; on the IC portion are shown acontrol electrode 370, thebonding agent 610 and awiring layer 625. On theMEMS portion 500 are shown themirror segment 380 andflexure 320, comprising thefirst flexure layer 330 andsecond flexure layer 340. - One important aspect of the present invention is the above-described passivation layer. In the first embodiment of the invention, an electrically-conductive contact must be established through the passivation layer at the points where the
MEMS structure 500 is bonded to thesubstrate 300. The bonding process can be any suitable process that results in a conductive bond, for example gold to gold bonding. To allow the bond material to be deposited onto theIC substrate 300, the passivation layer is preferably patternable. In an exemplary arrangement, the passivation layer is completely removable after the MEMS structure is released in a manner that will not damage the MEMS structure. This passivation material may be a protective polymer material such as a polyimide or parylene. - Alternatively, the passivation material can be conductive so that upon removal from the exposed surfaces, electrical contact between the ICs and MEMS element is maintained. The passivation material need not be patterned before bonding as it is selectively removed, where not bonded to the MEMS structures, in the passivation layer removal process. A conductive polymer or epoxy can be used, for example, EPO-TEK OH108-1 or other similar conductive epoxy made by Epoxy Technology, Inc., of Billerca, Mass.
- The present invention differs significantly from the prior art in that it relies on the influence of IRS (as opposed to CTE) in the flexures to elevate the mirror segments above the substrate plane, to a much greater degree than has been found in the prior art. The “Coefficient of thermal expansion” (“CTE”) describes the linear change in size of a material as a function of temperature, while “Intrinsic residual stress” (IRS) describes the stress in a material, which is dependent on the grain morphology and crystalline defects of a material. This means that the elevation of the segments above the substrate can be far less sensitive to changes in temperature than for comparable prior art devices. The deflection at the elevated end of each flexure is essentially proportional to the curvature of the flexure, which may be written as the sum of two components; a first component proportional to the intrinsic residual stress in the flexure and a second component proportional to the CTE mismatches in the flexure. In the first embodiment of the invention, the first flexure layer is composed of polysilicon and the second flexure layer is composed of silicon nitride. This provides a flexure for which the IRS component is larger than the CTE component by a factor of approximately one thousand at normal operating temperatures, for example in the range 0-100 degrees Celcius.
- Many alternative embodiments of the flexure are possible in which the second flexure material is one with a CTE similar to that of the first flexure material. If that first material is polysilicon, the second material can be a ceramic, such as SiC, or silicon nitride (SixNy), or even polysilicon itself, deposited under different conditions so as to induce a different grain structure and crystal defect concentration, and thus different IRS.
FIG. 8 is a table that lists the CTE of some example materials. - In contrast to the prior art usage of nickel, SixNy is advantageous because it does not contaminate etchers as Ni does. SixNy is also easier to process because it is a standard IC material deposited by LPCVD. The residual stress of SixNy can be controlled by varying the ratios of the reactant gasses, deposition pressure, and the deposition temperature. For example, a layer deposited with a gas flow ratio of 1:3 dichlorosilane to ammonia at 125 mTorr and 800 will yield a stoichiometric film (Si3N4) with approximately 1 GPa of residual tensile stress, while 4:1 gas ratio at 140 mTorr and 835° C. will yield a film composition near Si3N3 with approximately 280 MPa of residual tensile stress. To achieve the desired radius of curvature of the flexure, different SixNy stoichiometries can be used, the appropriate choice for which may be application-specific.
- The first embodiment of the DM comprises a tiled array of mirror segments, supported on flexures and elevated approximately 50 micrometers above the substrate. As described, the substrate contains electronic circuits used for controlling and sensing the tip, tilt and piston motion of the segments. The circuits are controlled via electrical signals transmitted, for example, through bond pads on the substrate and generated, for example, by a microprocessor in a manner well known in the art. The control signals typically contain information, generated by a wavefront reconstructor, about the combination of tip, tilt and piston motions for each mirror segment needed to compensate for the wavefront aberrations at a given time. “Piston movement” is one of three types of movement used to describe actuation of a mirror segment, and describes translation normal to the plane of the DM aperture. “Tilt”, the second type of movement, is movement about any first axis that is parallel to the plane of the DM aperture. “Tip”, the third type of movement, is movement about any second axis (not parallel to the first axis) that is also parallel to the substrate.
- The circuits embedded in the
substrate 300 decode this information and translate it into a corresponding set of voltages that are applied to the control electrodes disposed under each mirror segment. The electrical potential difference and resulting electrostatic force between each mirror segment and its three control electrodes causes it to move in tip, tilt and piston, and assume a position and orientation determined by the voltages applied to the three electrodes. This ability to independently orient and position each segment allows spatially complex wavefront aberrations to be corrected by the DM. In some implementations of the first embodiment, the substrate also contains sense electronics that detect the tip, tilt and piston of each segment, for example by measuring the capacitance between the segment and its three control electrodes. Incorporation of sense electronics can improve the resolution with which the segments can be controlled. Because the attractive force between a segment and its control electrodes increases rapidly as the gap between them diminishes, the control voltages must be limited to avoid pulling segments into contact with the electrodes. Typically, the maximum operation voltage is chosen to be the voltage that causes a segment to travel 25% of the elevation produced by the flexures. Therefore, the flexure elevation of 50 micrometers described in the first embodiment results in a useable mirror stroke of approximately 12 micrometers. - In a second embodiment of the invention, the structure of the DM is identical to the structure of the first embodiment, except that the ground pads and control electrodes are formed on the MEMS part rather than the CMOS part. The appearance of the completed device is essentially identical to that of the first embodiment, illustrated in
FIG. 3A . - Fabrication of the second embodiment proceeds in a manner identical to that used for the first embodiment up to step 435 of
FIG. 4B . A sacrificial layer is then deposited, patterned and etched to open up anchor points where theground pads 310 will attach to thefirst anchor regions 350 of the flexures. A layer of polysilicon is then deposited, patterned and etched to define theground pads 310 and thecontrol electrodes 370. A layer of metal is then deposited, patterned and etched so that it coats the surfaces of theground pads 310 andcontrol electrodes 370, but does not bridge unconnected structures. - The
CMOS portion 300 of the device is fabricated in the same way as for the first embodiment, but has bond sites in locations that correspond to both theground pads 310 and thecontrol electrodes 370 of the MEMS structure. The ground pad bond sites are electrically connected to a ground plane or to circuits in thesubstrate 300, while the control electrode bond sites are connected to the appropriate control and sense circuits within thesubstrate 300. The MEMS portion and the CMOS portion are bonded together using a film of anisotropic conductive polymer that conducts only in a direction normal to the plane of the film. In this embodiment, the anisotropic conductive polymer acts as both a bonding agent and a CMOS passivation layer. After bonding, the MEMS structures are mechanically released, for example by HF etching, as in the first embodiment. Because of the anisotropic nature of the polymer, it does not need to be removed from the DM and so the passivation layer removal step is omitted for this embodiment. As for the first embodiment, the final step is the deposition of an optical coating on the top surface of the mirror segments. - The method of operation for the second embodiment is identical to that for the first embodiment.
-
FIG. 9 shows the mechanical structure of a DM according to the third embodiment of the invention, in a partially exploded perspective view. For the sake of clarity,FIG. 9 shows only a single piston-tip-tilt mirror segment. However, it will be clear to one skilled in the art that multiple such mirrors may be fabricated side-by-side on a single substrate to form a segmented DM, as was described for the first embodiment. - The third embodiment of the DM comprises a
substrate 900, which may be a silicon wafer. On top of thesubstrate 900 are formed a number ofcontrol electrodes 960 that are electrically isolated from one another and electrically connected to conductive traces (not shown inFIG. 9 ) that may either be embedded in thesubstrate 900 or attached to the surface of thesubstrate 900. These traces electrically connect thecontrol electrodes 960 directly to bond pads (not shown inFIG. 9 ) that may be disposed around the perimeter of the DM chip. Thecontrol electrodes 960 are arranged in groups of three and are rhombic in shape, so that the footprint of each group is essentially hexagonal. - Disposed around each group of three
control electrodes 960, are threeconductive ground pads 910, fabricated from the same material as thecontrol electrodes 960. Theground pads 910 are electrically isolated from thecontrol electrodes 960 and electrically connected to a ground plane embedded in thesubstrate 900. Attached to one end of eachground pad 910 is afirst anchor portion 950 of aflexure 920. The flexure, in the third embodiment comprises two layers, afirst flexure layer 930 formed from conductive polycrystalline silicon and asecond flexure layer 940 formed from silicon nitride. Thefirst anchor portion 950 is both mechanically and electrically connected to theground pad 910 so that the conductivefirst flexure layer 930 is held at the same potential as theground pad 910. Thesecond flexure layer 940 is rigidly attached to the top side of thefirst flexure layer 930 and extends over a portion of the length of theflexure 920. The purpose of the second flexure layer is to provide a residual stress difference between the top and bottom portions of theflexure 920, causing theflexure 920 to bend up out of the plane of thesubstrate 300. - The end of the
flexure 920 opposite thefirst anchor portion 950 is electrically and mechanically connected to ahexagonal platform 980. Aplatform bond site 990, fabricated from a metal, is electrically and mechanically connected to the platform. This platform bond site matches up with a corresponding segment bond site, also fabricated from a metal, on the underside of amirror segment 970. The segment bond site is not visible inFIG. 9 , since it is on the underside of themirror segment 970. In the fully assembled DM, themirror segment 970 is mechanically and electrically connected to theplatform 980 via these bond sites. Thus themirror segment 970 is held at some elevation above thesubstrate 900. In the first embodiment, this elevation is on the order of 50 micrometers. The mirror segment is electrically conductive and therefore is held at the same potential as theground pad 910. In the third embodiment, themirror segment 970 is hexagonal in shape and is formed from a 20 micrometer-thick layer of single crystal silicon and is coated on its top surface with an optical coating, which may be a highly reflective metal layer. The mirror segment diameter in the third embodiment is on the order of 500 micrometers. - In the third embodiment, the DM does not incorporate drive and sense electronics, but does incorporate the improved bimorph flexure. The
actuator substrate 900 is fabricated in a method similar to that used to fabricate the MEMS portion of the first embodiment, but where the starting material is a standard silicon wafer rather than a bonded SOI wafer. Theground pads 910,control electrodes 960, electrical traces and bond pads are defined in a first undoped polysilicon layer, deposited on an insulating silicon nitride layer. Alternatively, the traces could be fabricated in a buried layer beneath the electrodes that is electrically isolated in all regions except areas that contact the electrical traces to electrodes and bond pads. A phosphorous-doped silicate glass (PSG) sacrificial layer is then deposited, patterned and etched to open up regions where thefirst anchor portion 950 of the flexures will connect to theground pads 910. A second undoped amorphous polysilicon layer is then deposited followed by a PSG layer. The wafer is annealed at 950° C. for six hours to dope and tune the residual stress of the second polysilicon layer to approximately −40 MPa. In this step, the sacrificial PSG layer also dopes the first layer of polysilicon. The top PSG layer is then removed using a wet HF acid etch and the second polysilicon layer is patterned and etched to define the first flexure layers 930 andplatforms 980. A layer of silicon nitride is then deposited, patterned and etched to define the second flexure layers 940, after which a low-temperature oxide (LTO) is deposited by LPCVD to protect the structures from a later etch. The LTO layer is etched and a metal layer is selectively deposited, for example by electroplating, to form thebond sites 990 and bond pads disposed around the perimeter of the DM chip. - The
mirror segments 970 are formed on a separate wafer, typically a BSOI wafer with a 20 micrometer thick device layer. The mirror segments are defined using deep reactive ion etching, followed by deposition of a sacrificial layer (typically PSG) that refills the trenches between the segments. The sacrificial layer is then patterned and etched to clear access holes for bond sites that match those deposited on theactuator substrate 900. A metal layer is then selectively deposited, for example by evaporation and lift-off, to form the segment bond sites that will be joined to the correspondingplatform bond sites 990. - The actuators and mirror segments are then assembled and bonded together, for example using gold to gold bonding. The mirror-segment handle wafer is then removed in a manner known to those skilled in the art, and the sacrificial layers are removed, for example by HF etching, to allow the flexures to lift the
mirror segments 970 above thesubstrate 900. Finally, an optical coating is deposited on the top surface of the mirror segments. - The third embodiment is operated in a manner similar to the first embodiment, with the exception that the control voltages used to set the orientation and piston of the mirror segments are generated by driver electronics on a chip or board that is physically separate from the DM chip. The control electrodes for each mirror segment are connected to the outputs of the drive electronics for example via bond wires electrically connected to the bond pads disposed around the edges of the DM chip.
- Accordingly, the invention provides improved methods and structures for elevating a number of platforms above a substrate and for controlling the piston, tip and tilt motions of those platforms. The resulting structures feature low temperature dependence, small size and power consumption and high control precision. The methods and structures may be used to construct an improved deformable mirror (DM) that features low temperature dependence, high fill-factor, high control resolution and large stroke, and which can be fabricated in a small form-factor at low cost. The ability to integrate drive and sense electronics on the same chip as the mirror segments allows DMs with large numbers of actuators to be realized. The structures and methods for producing temperature-insensitive elevated mirror segments and the structures and methods for assembling the mirror segments on to control and sense electronics can be applied separately or in combination.
- Although the description above contains many specificities, these should not be construed as limiting the scope of the invention but as merely providing illustrations of some of the possible embodiments of this invention. For example, the mirror segments can have other shapes, such as square, rectangular, triangular etc.; the mirror segments can be supported by different numbers of flexures; the flexures can be constructed from any number of materials and comprise any number of layers, provided their curvature is predominantly caused by IRS, rather than CTE differences; the tip, tilt and piston of the mirror segments can be controlled by varying the duty cycle of an AC signal applied to the control electrodes rather than the magnitude of an applied DC signal; the thicknesses of the layers that comprise the DM can be varied; the diameters or widths of features such as the mirror segments, flexures and control electrodes can be varied; the number and placement of the control electrodes under each segment can be changed; the elevation of the mirror segments above the substrate can be altered; the actuators need not be electrostatic but could be, for example, piezoelectric or magnetic; the gaps between mirror segments can be changed; different reflective coatings including both metallic and dielectric coatings can be deposited on the top surface of the segments; different materials and methods can be used to bond the MEMS portion to the CMOS portion; different passivation materials can be used to protect the CMOS circuits during MEMS release; the number of mirror segments comprising the DM can be varied, etc.
- While numerous specific details have been set forth in order to provide a thorough understanding of the present invention, numerous aspects of the present invention may be practiced with only some of these details. In addition, certain process operations and related details which are known in the art have not been described in detail in order not to unnecessarily obscure the present invention.
- Thus the scope of the invention should be determined by the appended claims and their legal equivalents, rather than by the examples given.
- The foregoing detailed description of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. The described embodiments were chosen in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto.
Claims (9)
1. (canceled)
2. A method for fabricating a microelectromechanical (MEMS) structure, the method comprising:
forming a platform connected with a set of one or more bimorph flexures; and
for each bimorph flexure in the set of bimorph flexures:
forming a first layer comprised of a first material; and
forming a second layer comprised of a second material, the first and second materials having particular intrinsic residual stress (IRS) characteristics and coefficients of thermal expansion (CTEs), each bimorph flexure having a curvature resulting from a first component proportional to the difference in IRS characteristics of the first and second materials and a second component proportional to the difference in CTEs of the first and second materials, the first component being larger than the second component.
3. The method of claim 2 , wherein the curvature of each formed bimorph flexure results predominantly from the first component.
4. The method of claim 2 , wherein the first material comprises silicon and the second material comprises silicon nitride, or the first material comprises polysilicon and the second material comprises ceramic, SiC, or silicon nitride (SixNy).
5. The method of claim 2 , wherein forming the second layer comprises forming the second layer external to the first layer.
6. The method of claim 2 , wherein forming the second layer comprises forming the second layer to extend over a portion of the first layer that is less than the entire length of the first layer and forming the second layer to be affixed to the first layer along the entire length of the second layer.
7. The method of claim 2 , wherein the first and second layers are formed under conditions that produce substantially different intrinsic residual stress (IRS) characteristics in the first and second materials.
8. The method of claim 7 , wherein:
forming the first layer comprises tuning the residual stress of the first layer; and
forming the second layer comprises forming the second layer under a specific ratio of the reactant gasses, deposition pressure, and deposition temperature to produce a desired residual stress of the second layer.
9. The method of claim 7 , wherein the first and second materials comprise polysilicon.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US11/260,999 US20060038103A1 (en) | 2002-11-08 | 2005-10-28 | Deformable mirror method including bimorph flexures |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US42505102P | 2002-11-08 | 2002-11-08 | |
US42504902P | 2002-11-08 | 2002-11-08 | |
US10/703,391 US7019434B2 (en) | 2002-11-08 | 2003-11-07 | Deformable mirror method and apparatus including bimorph flexures and integrated drive |
US11/260,999 US20060038103A1 (en) | 2002-11-08 | 2005-10-28 | Deformable mirror method including bimorph flexures |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US10/703,391 Division US7019434B2 (en) | 2002-11-08 | 2003-11-07 | Deformable mirror method and apparatus including bimorph flexures and integrated drive |
Publications (1)
Publication Number | Publication Date |
---|---|
US20060038103A1 true US20060038103A1 (en) | 2006-02-23 |
Family
ID=32872718
Family Applications (4)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US10/703,391 Expired - Fee Related US7019434B2 (en) | 2002-11-08 | 2003-11-07 | Deformable mirror method and apparatus including bimorph flexures and integrated drive |
US11/097,777 Expired - Fee Related US7138745B1 (en) | 2002-11-08 | 2005-04-01 | Method and apparatus for an actuator system with integrated control |
US11/096,367 Expired - Fee Related US7294282B1 (en) | 2002-11-08 | 2005-04-01 | Method for fabricating an actuator system |
US11/260,999 Abandoned US20060038103A1 (en) | 2002-11-08 | 2005-10-28 | Deformable mirror method including bimorph flexures |
Family Applications Before (3)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US10/703,391 Expired - Fee Related US7019434B2 (en) | 2002-11-08 | 2003-11-07 | Deformable mirror method and apparatus including bimorph flexures and integrated drive |
US11/097,777 Expired - Fee Related US7138745B1 (en) | 2002-11-08 | 2005-04-01 | Method and apparatus for an actuator system with integrated control |
US11/096,367 Expired - Fee Related US7294282B1 (en) | 2002-11-08 | 2005-04-01 | Method for fabricating an actuator system |
Country Status (1)
Country | Link |
---|---|
US (4) | US7019434B2 (en) |
Cited By (23)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20050100339A1 (en) * | 2003-11-10 | 2005-05-12 | Harris Corporation, Corporation Of The State Of Delaware | System and method of free-space optical satellite communications |
US20070120444A1 (en) * | 2005-11-30 | 2007-05-31 | Hitachi, Ltd. | Actuator and method of manufacturing actuator module |
US20090042372A1 (en) * | 2007-04-05 | 2009-02-12 | Analog Devices, Inc. | Polysilicon Deposition and Anneal Process Enabling Thick Polysilicon Films for MEMS Applications |
US7629725B1 (en) * | 2002-11-08 | 2009-12-08 | Iris Ao, Inc. | Micromechanical actuator with asymmetrically shaped electrodes |
US20100151194A1 (en) * | 2008-12-12 | 2010-06-17 | Soraa, Inc. | Polycrystalline group iii metal nitride with getter and method of making |
US20100192941A1 (en) * | 2009-01-30 | 2010-08-05 | Stoia Michael F | Solar Concentration System With Micro-Mirror Array |
DE102009033191A1 (en) * | 2009-07-07 | 2011-01-13 | Technische Universität Dresden | Reduction of the dynamic deformation of translation mirrors with the aid of inert masses |
US8391700B1 (en) * | 2005-02-28 | 2013-03-05 | DigitalOptics Corporation MEMS | Autofocus camera systems and methods |
US9813022B2 (en) | 2014-02-21 | 2017-11-07 | The Boeing Company | Dynamically setting a threshold output level for a solar array |
US10236822B2 (en) | 2014-02-21 | 2019-03-19 | The Boeing Company | Method and apparatus for calibrating a micro-concentrator solar array |
US10250182B2 (en) | 2014-02-21 | 2019-04-02 | The Boeing Company | Micro-concentrator solar array using micro-electromechanical systems (MEMS) based reflectors |
US10693028B2 (en) | 2014-02-21 | 2020-06-23 | The Boeing Company | Micro-concentrator solar array using micro-electromechanical systems (MEMS) based reflectors |
US11333879B2 (en) * | 2019-09-20 | 2022-05-17 | Raytheon Company | Electronically steered inter-satellite optical communication system with micro-electromechanical (MEM) micromirror array (MMA) |
US11477350B2 (en) | 2021-01-15 | 2022-10-18 | Raytheon Company | Active imaging using a micro-electro-mechanical system (MEMS) micro-mirror array (MMA) |
US11483500B2 (en) | 2021-03-24 | 2022-10-25 | Raytheon Company | Optical non-uniformity compensation (NUC) for passive imaging sensors using micro-electro-mechanical system (MEMS) micro-mirror arrays (MMAS) |
US11522331B2 (en) | 2020-09-23 | 2022-12-06 | Raytheon Company | Coherent optical beam combination using micro-electro-mechanical system (MEMS) micro-mirror arrays (MMAs) that exhibit tip/tilt/piston (TTP) actuation |
US11539131B2 (en) | 2020-08-24 | 2022-12-27 | Raytheon Company | Optical true time delay (TTD) device using microelectrical-mechanical system (MEMS) micromirror arrays (MMAS) that exhibit tip/tilt/piston (TTP) actuation |
US11550146B2 (en) | 2021-01-19 | 2023-01-10 | Raytheon Company | Small angle optical beam steering using micro-electro-mechanical system (MEMS) micro-mirror arrays (MMAS) |
US11644542B2 (en) | 2021-09-20 | 2023-05-09 | Raytheon Company | Optical sensor with MEMS MMA steered transmitter and staring detector |
US11815676B2 (en) | 2020-09-17 | 2023-11-14 | Raytheon Company | Active pushbroom imaging system using a micro-electro-mechanical system (MEMS) micro-mirror array (MMA) |
US11835709B2 (en) | 2021-02-09 | 2023-12-05 | Raytheon Company | Optical sensor with micro-electro-mechanical system (MEMS) micro-mirror array (MMA) steering of the optical transmit beam |
US11837840B2 (en) | 2020-09-01 | 2023-12-05 | Raytheon Company | MEMS micro-mirror array laser beam steerer for simultaneous illumination of multiple tracked targets |
US11921284B2 (en) | 2021-03-19 | 2024-03-05 | Raytheon Company | Optical zoom system using an adjustable reflective fresnel lens implemented with a micro-electro-mechanical system (MEMs) micro-mirror array (MMA) |
Families Citing this family (44)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7019434B2 (en) * | 2002-11-08 | 2006-03-28 | Iris Ao, Inc. | Deformable mirror method and apparatus including bimorph flexures and integrated drive |
JP2004198626A (en) * | 2002-12-17 | 2004-07-15 | Olympus Corp | Deformable mirror system and reflecting surface shape control method |
WO2010014261A2 (en) * | 2008-08-01 | 2010-02-04 | The Penn State Research Foundation | Polycrystalline complex-shaped mesoscale components |
JP2004262777A (en) * | 2003-02-27 | 2004-09-24 | Shiseido Co Ltd | Acetylated hyaluronic acid-containing ocular medicinal preparation |
US7046411B1 (en) | 2005-04-29 | 2006-05-16 | Sandia Corporation | Tensile-stressed microelectromechanical apparatus and micromirrors formed therefrom |
US7159397B1 (en) | 2005-06-07 | 2007-01-09 | Sandia Corporation | Tensile-stressed microelectromechanical apparatus and tiltable micromirrors formed therefrom |
TWI372271B (en) * | 2005-09-13 | 2012-09-11 | Zeiss Carl Smt Gmbh | Optical element unit, optical element holder, method of manufacturing an optical element holder, optical element module, optical exposure apparatus, and method of manufacturing a semiconductor device |
US7498715B2 (en) * | 2005-10-31 | 2009-03-03 | Xiao Yang | Method and structure for an out-of plane compliant micro actuator |
US7576308B1 (en) * | 2006-07-28 | 2009-08-18 | The United States Of America As Represented By The Secretary Of The Air Force | Mosaic imager using wave front control |
US8100543B1 (en) | 2007-06-12 | 2012-01-24 | Nvidia Corporation | Display system and method equipped with at least one steerable deflecting mirror |
US8118440B1 (en) * | 2007-06-12 | 2012-02-21 | Nvidia Corporation | Capture system and method equipped with at least one steerable deflecting mirror |
DE102007038872A1 (en) * | 2007-08-16 | 2009-02-26 | Seereal Technologies S.A. | Imaging device for influencing incident light |
DE102008014615A1 (en) * | 2008-03-17 | 2009-10-01 | Friedrich-Schiller-Universität Jena | Adaptive deformable mirror to compensate for wavefront errors |
FR2933782B1 (en) * | 2008-07-11 | 2010-08-13 | Thales Sa | DEVICE FOR CORRECTING THE OPTICAL DEFECTS OF A TELESCOPE MIRROR |
US8797279B2 (en) | 2010-05-25 | 2014-08-05 | MCube Inc. | Analog touchscreen methods and apparatus |
US8928602B1 (en) | 2009-03-03 | 2015-01-06 | MCube Inc. | Methods and apparatus for object tracking on a hand-held device |
US8234951B1 (en) * | 2009-05-13 | 2012-08-07 | University Of South Florida | Bistable aerial platform |
US8421082B1 (en) | 2010-01-19 | 2013-04-16 | Mcube, Inc. | Integrated CMOS and MEMS with air dielectric method and system |
US8476129B1 (en) | 2010-05-24 | 2013-07-02 | MCube Inc. | Method and structure of sensors and MEMS devices using vertical mounting with interconnections |
US8823007B2 (en) | 2009-10-28 | 2014-09-02 | MCube Inc. | Integrated system on chip using multiple MEMS and CMOS devices |
US8553389B1 (en) | 2010-08-19 | 2013-10-08 | MCube Inc. | Anchor design and method for MEMS transducer apparatuses |
US8710597B1 (en) | 2010-04-21 | 2014-04-29 | MCube Inc. | Method and structure for adding mass with stress isolation to MEMS structures |
US8477473B1 (en) | 2010-08-19 | 2013-07-02 | MCube Inc. | Transducer structure and method for MEMS devices |
US9709509B1 (en) | 2009-11-13 | 2017-07-18 | MCube Inc. | System configured for integrated communication, MEMS, Processor, and applications using a foundry compatible semiconductor process |
EP2333603A1 (en) * | 2009-12-08 | 2011-06-15 | Alcatel Lucent | An optical beam scanner |
US8794065B1 (en) | 2010-02-27 | 2014-08-05 | MCube Inc. | Integrated inertial sensing apparatus using MEMS and quartz configured on crystallographic planes |
US8936959B1 (en) | 2010-02-27 | 2015-01-20 | MCube Inc. | Integrated rf MEMS, control systems and methods |
US8367522B1 (en) | 2010-04-08 | 2013-02-05 | MCube Inc. | Method and structure of integrated micro electro-mechanical systems and electronic devices using edge bond pads |
US8928696B1 (en) | 2010-05-25 | 2015-01-06 | MCube Inc. | Methods and apparatus for operating hysteresis on a hand held device |
US8869616B1 (en) | 2010-06-18 | 2014-10-28 | MCube Inc. | Method and structure of an inertial sensor using tilt conversion |
US8652961B1 (en) | 2010-06-18 | 2014-02-18 | MCube Inc. | Methods and structure for adapting MEMS structures to form electrical interconnections for integrated circuits |
US8709264B2 (en) | 2010-06-25 | 2014-04-29 | International Business Machines Corporation | Planar cavity MEMS and related structures, methods of manufacture and design structures |
US8993362B1 (en) | 2010-07-23 | 2015-03-31 | MCube Inc. | Oxide retainer method for MEMS devices |
DE102010042764A1 (en) * | 2010-10-21 | 2012-04-26 | Siemens Aktiengesellschaft | Brush with brush elements for power transmission to a sliding surface |
US8723986B1 (en) | 2010-11-04 | 2014-05-13 | MCube Inc. | Methods and apparatus for initiating image capture on a hand-held device |
GB2485607B (en) | 2010-11-22 | 2017-12-27 | Daqri Holographics Ltd | Spatial light modulators |
US8969101B1 (en) | 2011-08-17 | 2015-03-03 | MCube Inc. | Three axis magnetic sensor device and method using flex cables |
DE102014211379A1 (en) * | 2014-06-13 | 2015-12-17 | Robert Bosch Gmbh | MIRROR MIRROR AND PROJECTION DEVICE |
LT6250B (en) | 2014-07-10 | 2016-02-25 | Uab "Altechna R&D" | Wavefront preserving laser beam shaper |
CN104370272B (en) * | 2014-10-30 | 2016-07-06 | 无锡微奥科技有限公司 | A kind of MEMS autoregistration height comb and manufacture method thereof |
DE102015206774B4 (en) * | 2015-04-15 | 2018-10-25 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. | Micromechanical device with an actively bendable element |
US11535511B2 (en) | 2017-08-02 | 2022-12-27 | United States Of America As Represented By The Secretary Of The Air Force | Post-processing techniques on mems foundry fabricated devices for large angle beamsteering |
US11279613B2 (en) * | 2017-08-02 | 2022-03-22 | Government Of The United States, As Represented By The Secretary Of The Air Force | MEMS device for large angle beamsteering |
CN110703428A (en) * | 2019-10-28 | 2020-01-17 | 京东方科技集团股份有限公司 | Light modulation mirror, manufacturing method thereof and light modulation device |
Citations (18)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4374402A (en) * | 1980-06-27 | 1983-02-15 | Burroughs Corporation | Piezoelectric transducer mounting structure and associated techniques |
US5096279A (en) * | 1984-08-31 | 1992-03-17 | Texas Instruments Incorporated | Spatial light modulator and method |
US5796152A (en) * | 1997-01-24 | 1998-08-18 | Roxburgh Ltd. | Cantilevered microstructure |
US6091050A (en) * | 1997-11-17 | 2000-07-18 | Roxburgh Limited | Thermal microplatform |
US6283601B1 (en) * | 2000-04-14 | 2001-09-04 | C Speed Corporation | Optical mirror system with multi-axis rotational control |
US6351330B2 (en) * | 1998-04-10 | 2002-02-26 | Samsung Electronics Co., Ltd. | Micromirror device for image display apparatus |
US6366414B1 (en) * | 1999-09-03 | 2002-04-02 | Agere Systems Guardian Corp. | Micro-electro-mechanical optical device |
US6440766B1 (en) * | 2000-02-16 | 2002-08-27 | Analog Devices Imi, Inc. | Microfabrication using germanium-based release masks |
US20020122238A1 (en) * | 2000-12-28 | 2002-09-05 | Knipe Richard L. | Capacitively coupled micromirror |
US6448622B1 (en) * | 1999-01-15 | 2002-09-10 | The Regents Of The University Of California | Polycrystalline silicon-germanium films for micro-electromechanical systems application |
US6454421B2 (en) * | 1999-07-13 | 2002-09-24 | Input/Output, Inc. | Dual axis micro machined mirror device |
US6466356B1 (en) * | 2000-09-28 | 2002-10-15 | Xerox Corporation | Structure for an optical switch on a silicon substrate |
US6545385B2 (en) * | 2000-04-11 | 2003-04-08 | Sandia Corporation | Microelectromechanical apparatus for elevating and tilting a platform |
US6632374B1 (en) * | 2000-09-28 | 2003-10-14 | Xerox Corporation | Method for an optical switch on a silicon on insulator substrate |
US20040160118A1 (en) * | 2002-11-08 | 2004-08-19 | Knollenberg Clifford F. | Actuator apparatus and method for improved deflection characteristics |
US6781208B2 (en) * | 2001-08-17 | 2004-08-24 | Nec Corporation | Functional device, method of manufacturing therefor and driver circuit |
US6795603B2 (en) * | 2001-07-18 | 2004-09-21 | Nec Corporation | Optical switch |
US7138745B1 (en) * | 2002-11-08 | 2006-11-21 | Iris Ao, Inc. | Method and apparatus for an actuator system with integrated control |
Family Cites Families (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6674562B1 (en) * | 1994-05-05 | 2004-01-06 | Iridigm Display Corporation | Interferometric modulation of radiation |
US6128122A (en) * | 1998-09-18 | 2000-10-03 | Seagate Technology, Inc. | Micromachined mirror with stretchable restoring force member |
EP1088250A1 (en) | 1999-03-18 | 2001-04-04 | Trustees Of Boston University | Very large angle integrated optical scanner made with an array of piezoelectric monomorphs |
US6617750B2 (en) * | 1999-09-21 | 2003-09-09 | Rockwell Automation Technologies, Inc. | Microelectricalmechanical system (MEMS) electrical isolator with reduced sensitivity to inertial noise |
JP2001249285A (en) | 2000-03-02 | 2001-09-14 | Seiko Epson Corp | Switching device, optical switching unit and video display device |
US6525864B1 (en) * | 2000-07-20 | 2003-02-25 | Nayna Networks, Inc. | Integrated mirror array and circuit device |
US6662655B2 (en) * | 2000-10-31 | 2003-12-16 | Honeywell International, Inc. | Net zero isolator |
US6543286B2 (en) | 2001-01-26 | 2003-04-08 | Movaz Networks, Inc. | High frequency pulse width modulation driver, particularly useful for electrostatically actuated MEMS array |
US6625004B1 (en) * | 2001-08-31 | 2003-09-23 | Superconductor Technologies, Inc. | Electrostatic actuators with intrinsic stress gradient |
-
2003
- 2003-11-07 US US10/703,391 patent/US7019434B2/en not_active Expired - Fee Related
-
2005
- 2005-04-01 US US11/097,777 patent/US7138745B1/en not_active Expired - Fee Related
- 2005-04-01 US US11/096,367 patent/US7294282B1/en not_active Expired - Fee Related
- 2005-10-28 US US11/260,999 patent/US20060038103A1/en not_active Abandoned
Patent Citations (18)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4374402A (en) * | 1980-06-27 | 1983-02-15 | Burroughs Corporation | Piezoelectric transducer mounting structure and associated techniques |
US5096279A (en) * | 1984-08-31 | 1992-03-17 | Texas Instruments Incorporated | Spatial light modulator and method |
US5796152A (en) * | 1997-01-24 | 1998-08-18 | Roxburgh Ltd. | Cantilevered microstructure |
US6091050A (en) * | 1997-11-17 | 2000-07-18 | Roxburgh Limited | Thermal microplatform |
US6351330B2 (en) * | 1998-04-10 | 2002-02-26 | Samsung Electronics Co., Ltd. | Micromirror device for image display apparatus |
US6448622B1 (en) * | 1999-01-15 | 2002-09-10 | The Regents Of The University Of California | Polycrystalline silicon-germanium films for micro-electromechanical systems application |
US6454421B2 (en) * | 1999-07-13 | 2002-09-24 | Input/Output, Inc. | Dual axis micro machined mirror device |
US6366414B1 (en) * | 1999-09-03 | 2002-04-02 | Agere Systems Guardian Corp. | Micro-electro-mechanical optical device |
US6440766B1 (en) * | 2000-02-16 | 2002-08-27 | Analog Devices Imi, Inc. | Microfabrication using germanium-based release masks |
US6545385B2 (en) * | 2000-04-11 | 2003-04-08 | Sandia Corporation | Microelectromechanical apparatus for elevating and tilting a platform |
US6283601B1 (en) * | 2000-04-14 | 2001-09-04 | C Speed Corporation | Optical mirror system with multi-axis rotational control |
US6466356B1 (en) * | 2000-09-28 | 2002-10-15 | Xerox Corporation | Structure for an optical switch on a silicon substrate |
US6632374B1 (en) * | 2000-09-28 | 2003-10-14 | Xerox Corporation | Method for an optical switch on a silicon on insulator substrate |
US20020122238A1 (en) * | 2000-12-28 | 2002-09-05 | Knipe Richard L. | Capacitively coupled micromirror |
US6795603B2 (en) * | 2001-07-18 | 2004-09-21 | Nec Corporation | Optical switch |
US6781208B2 (en) * | 2001-08-17 | 2004-08-24 | Nec Corporation | Functional device, method of manufacturing therefor and driver circuit |
US20040160118A1 (en) * | 2002-11-08 | 2004-08-19 | Knollenberg Clifford F. | Actuator apparatus and method for improved deflection characteristics |
US7138745B1 (en) * | 2002-11-08 | 2006-11-21 | Iris Ao, Inc. | Method and apparatus for an actuator system with integrated control |
Cited By (33)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7741685B1 (en) | 2002-11-08 | 2010-06-22 | Iris Ao, Inc. | Method and apparatus for an actuator system having buried interconnect lines |
US7699296B1 (en) | 2002-11-08 | 2010-04-20 | Iris Ao, Inc. | Method and apparatus for an actuator having an intermediate frame |
US7629725B1 (en) * | 2002-11-08 | 2009-12-08 | Iris Ao, Inc. | Micromechanical actuator with asymmetrically shaped electrodes |
US7593641B2 (en) * | 2003-11-10 | 2009-09-22 | Harris Corporation | System and method of free-space optical satellite communications |
US20050100339A1 (en) * | 2003-11-10 | 2005-05-12 | Harris Corporation, Corporation Of The State Of Delaware | System and method of free-space optical satellite communications |
US9625673B2 (en) | 2005-02-28 | 2017-04-18 | DigitalOptics Corporation MEMS | Autofocus camera systems and methods |
US8391700B1 (en) * | 2005-02-28 | 2013-03-05 | DigitalOptics Corporation MEMS | Autofocus camera systems and methods |
US7449818B2 (en) * | 2005-11-30 | 2008-11-11 | Hitachi, Ltd. | Actuator and method of manufacturing actuator module |
US7449817B2 (en) * | 2005-11-30 | 2008-11-11 | Hitachi, Ltd. | Actuator and method of manufacturing actuator module |
US20070241641A1 (en) * | 2005-11-30 | 2007-10-18 | Hitachi, Ltd. | Actuator and method of manufacturing actuator module |
US20070120444A1 (en) * | 2005-11-30 | 2007-05-31 | Hitachi, Ltd. | Actuator and method of manufacturing actuator module |
US20090042372A1 (en) * | 2007-04-05 | 2009-02-12 | Analog Devices, Inc. | Polysilicon Deposition and Anneal Process Enabling Thick Polysilicon Films for MEMS Applications |
US7754617B2 (en) * | 2007-04-05 | 2010-07-13 | Analog Devices, Inc. | Polysilicon deposition and anneal process enabling thick polysilicon films for MEMS applications |
US20100151194A1 (en) * | 2008-12-12 | 2010-06-17 | Soraa, Inc. | Polycrystalline group iii metal nitride with getter and method of making |
US20100192941A1 (en) * | 2009-01-30 | 2010-08-05 | Stoia Michael F | Solar Concentration System With Micro-Mirror Array |
DE102009033191A1 (en) * | 2009-07-07 | 2011-01-13 | Technische Universität Dresden | Reduction of the dynamic deformation of translation mirrors with the aid of inert masses |
US8873128B2 (en) | 2009-07-07 | 2014-10-28 | Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung E.V. | Reduction of the dynamic deformation of translational mirrors using inertial masses |
US10236822B2 (en) | 2014-02-21 | 2019-03-19 | The Boeing Company | Method and apparatus for calibrating a micro-concentrator solar array |
US10250182B2 (en) | 2014-02-21 | 2019-04-02 | The Boeing Company | Micro-concentrator solar array using micro-electromechanical systems (MEMS) based reflectors |
US10693028B2 (en) | 2014-02-21 | 2020-06-23 | The Boeing Company | Micro-concentrator solar array using micro-electromechanical systems (MEMS) based reflectors |
US9813022B2 (en) | 2014-02-21 | 2017-11-07 | The Boeing Company | Dynamically setting a threshold output level for a solar array |
US11650412B2 (en) | 2019-09-20 | 2023-05-16 | Raytheon Company | Optical non-uniformity correction (NUC) for active mode imaging sensors using micro-electro-mechanical system (MEMS) micro-mirror arrays (MMAs) |
US11333879B2 (en) * | 2019-09-20 | 2022-05-17 | Raytheon Company | Electronically steered inter-satellite optical communication system with micro-electromechanical (MEM) micromirror array (MMA) |
US11539131B2 (en) | 2020-08-24 | 2022-12-27 | Raytheon Company | Optical true time delay (TTD) device using microelectrical-mechanical system (MEMS) micromirror arrays (MMAS) that exhibit tip/tilt/piston (TTP) actuation |
US11837840B2 (en) | 2020-09-01 | 2023-12-05 | Raytheon Company | MEMS micro-mirror array laser beam steerer for simultaneous illumination of multiple tracked targets |
US11815676B2 (en) | 2020-09-17 | 2023-11-14 | Raytheon Company | Active pushbroom imaging system using a micro-electro-mechanical system (MEMS) micro-mirror array (MMA) |
US11522331B2 (en) | 2020-09-23 | 2022-12-06 | Raytheon Company | Coherent optical beam combination using micro-electro-mechanical system (MEMS) micro-mirror arrays (MMAs) that exhibit tip/tilt/piston (TTP) actuation |
US11477350B2 (en) | 2021-01-15 | 2022-10-18 | Raytheon Company | Active imaging using a micro-electro-mechanical system (MEMS) micro-mirror array (MMA) |
US11550146B2 (en) | 2021-01-19 | 2023-01-10 | Raytheon Company | Small angle optical beam steering using micro-electro-mechanical system (MEMS) micro-mirror arrays (MMAS) |
US11835709B2 (en) | 2021-02-09 | 2023-12-05 | Raytheon Company | Optical sensor with micro-electro-mechanical system (MEMS) micro-mirror array (MMA) steering of the optical transmit beam |
US11921284B2 (en) | 2021-03-19 | 2024-03-05 | Raytheon Company | Optical zoom system using an adjustable reflective fresnel lens implemented with a micro-electro-mechanical system (MEMs) micro-mirror array (MMA) |
US11483500B2 (en) | 2021-03-24 | 2022-10-25 | Raytheon Company | Optical non-uniformity compensation (NUC) for passive imaging sensors using micro-electro-mechanical system (MEMS) micro-mirror arrays (MMAS) |
US11644542B2 (en) | 2021-09-20 | 2023-05-09 | Raytheon Company | Optical sensor with MEMS MMA steered transmitter and staring detector |
Also Published As
Publication number | Publication date |
---|---|
US7294282B1 (en) | 2007-11-13 |
US7019434B2 (en) | 2006-03-28 |
US20040165243A1 (en) | 2004-08-26 |
US7138745B1 (en) | 2006-11-21 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US7019434B2 (en) | Deformable mirror method and apparatus including bimorph flexures and integrated drive | |
US6384952B1 (en) | Vertical comb drive actuated deformable mirror device and method | |
US6940630B2 (en) | Vertical displacement device | |
US6108121A (en) | Micromachined high reflectance deformable mirror | |
US6353492B2 (en) | Method of fabrication of a torsional micro-mechanical mirror system | |
US9329360B2 (en) | Actuator having two piezoelectric elements on a membrane | |
US8724200B1 (en) | MEMS hierarchically-dimensioned optical mirrors and methods for manufacture thereof | |
Jung et al. | High fill-factor two-axis gimbaled tip-tilt-piston micromirror array actuated by self-aligned vertical electrostatic combdrives | |
US7336412B2 (en) | PZT unimorph based, high stroke mems deformable mirror with continuous membrane and method of making the same | |
US8743449B2 (en) | Method and apparatus for providing high-fill-factor micromirror/micromirror arrays with surface mounting capability | |
US7453621B2 (en) | Micro mirrors with piezoelectric release mechanism | |
Lammel et al. | Optical microscanners and microspectrometers using thermal bimorph actuators | |
US11163152B2 (en) | MEMS electrothermal actuator for large angle beamsteering | |
US6822370B2 (en) | Parallel plate electrostatic actuation of MEMS mirrors | |
Helmbrecht et al. | Segmented MEMS deformable-mirror for wavefront correction | |
Cornelissen et al. | Development of a 4096 element MEMS continuous membrane deformable mirror for high contrast astronomical imaging | |
Cornelissen et al. | A 4096 element continuous facesheet MEMS deformable mirror for high-contrast imaging | |
US6954301B2 (en) | Low-voltage electromechanical device including a tiltable microplatform, method of tilting same, array of such devices and method of setting dimple-to-substrate spacing | |
Helmbrecht et al. | Segmented MEMS deformable-mirror technology for space applications | |
US11535511B2 (en) | Post-processing techniques on mems foundry fabricated devices for large angle beamsteering | |
Menn et al. | Advances in MEMS deformable mirror technology for laser beam shaping | |
Kubby | Wavefront correctors | |
Schwartz et al. | A micromachined deformable mirror for adaptive optics | |
Bifano et al. | MEMS deformable mirrors for space and defense applications | |
Li et al. | Real-time phase correction of optical images using adaptive optics system based on MEMS technology |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |