Surface-micromachined microoptical elements and systems

Muller, R.S.; Lau, K.Y.

doi:10.1109/5.704276

Cited by 119 publications

(36 citation statements)

References 17 publications

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“…An important application was then found in 3-D microoptoelectromechanical systems (MOEMS), in which rotational assembly is used to create small optical subsystems that process free space beams travelling above the surface of a chip [47]- [49]. 3-D MOEMS components developed to date include refractive [50] and Fresnel lenses [51], corner cube reflectors [52], Fabry-Perot etalons [53], mirror scanners [54], and bar-code readers [55].…”

Section: -D Structuresmentioning

confidence: 99%

Surface tension-powered self-assembly of microstructures - The state-of-the-art

Syms¹,

Yeatman²,

Bright

et al. 2003

J. Microelectromech. Syst.

320

238

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Abstract-Because of the low dimensional power of its force scaling law, surface tension is appropriate for carrying out reshaping and assembly in the microstructure size domain. This paper reviews work on surface tension powered self-assembly of microstructures. The existing theoretical approaches for rotational assembly are unified. The demonstrated fabrication processes are compared. Mechanisms for accurately determining the assembled shape are discussed, and the limits on accuracy and structural distortion are considered. Applications in optics, electronics and mechanics are described. More complex operations (including the combination of self-assembly and self-organization) are also reviewed.[926]Index Terms-Capillary force, microelectromechanical systems (MEMS), microsystems, microoptoelectromechanical systems (MOEMS), self-assembly, surface tension.

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Section: -D Structuresmentioning

confidence: 99%

Surface tension-powered self-assembly of microstructures - The state-of-the-art

Syms¹,

Yeatman²,

Bright

et al. 2003

J. Microelectromech. Syst.

320

238

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“…M ICROOPTOELECTRO-MECHANICAL systems (MOEMS) are movable components constructed on Si substrates by surface micromachining to focus, filter, or deflect optical beams [1]. To process free-space beams, three-dimensional (3-D) structures are formed by out-of-plane rotation of parts hinged to the substrate [2].…”

mentioning

confidence: 99%

Self-assembled 3-D silicon microscanners with self-assembled electrostatic drives

Syms

2000

IEEE Photon. Technol. Lett.

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Abstract-Three-dimensional, electrostatically driven resonant torsion mirror microscanners are constructed by surface tension powered out-of-plane rotation of parts formed in bonded silicon-on-insulator. Simultaneous self-assembly of the fixed electrodes using a below-substrate limiter mechanism allows scanning perpendicular to the assembly axis, and direct drive allows high-Q operation. Similar components have been fabricated by surface tension self-assembly, a method of mass-parallel fabrication of 3-D microstructures [5]. Rotation is powered by melting small pads of material (solder, glass, or photoresist) linking movable parts to the substrate. Recent work has used thick resist, with single crystal parts formed in bonded silicon-on-insulator (BSOI). Assembly has involved 45 rotation, with the final geometry fixed by a limiter [6]. Fig. 1(a) shows the mechanism used, which involves simultaneous rotation of two parts (FRAME-L and FRAME-R) in opposite directions. Catches on the parts prevent further motion when each has rotated through 45 . The assembly accuracy is extremely high, but the mechanism is bulky and, hence, most suitable for major component frames. Index Terms-MEMSThis two-part structure has been used in electrostatically driven torsion mirror scanners [6]. FRAME-R carried a mirror mounted on a torsion bar with its axis parallel to the substrate. The mirror carried one half of a comb electrostatic drive, while the other half was attached to the substrate. After assembly, the mirror could be excited into resonant torsional oscillation by a harmonic electrostatic force between the two halves of the drive. Because of the direct nature of the drive, quality factors as high as 60 were demonstrated.Manuscript received April 25, 2000; revised July 7, 2000. This work was supported by EPSRC.The author is with the Department of Electrical and Electronic Engineering, Imperial College, Exhibition Road, London, SW7 2BT, U.K. (e-mail: r.syms@ic.ac.uk).Publisher Item Identifier S 1041-1135(00)09600-2. The design had several limitations. First, the skewed electrode layout resulted in a high drive voltage, because of the weak electrostatic field. Second, there was a trade off between the voltage and the scan angle, because a reduction in separation between the halves of the comb could only be performed by lengthening the moving electrode fingers, reducing the angle of turn before they struck the substrate. Finally, only mirror axes parallel to the substrate could be used, to avoid the electrodes clashing.In this paper, we show how to overcome these difficulties by further self-assembly operations, and introduce a new mechanism that allows parts as small as the fixed half of the electrode to be reconfigured. Fig. 1(a) and (b) shows the mechanism, which is based on two cranks attached to a third movable part DRIVE near its hinge. Motion is prevented when the cranks reach the substrate. The accuracy of this mechanism is inherently low, as we show below, but it is sufficient for sub-component assembly. Here, we show how...

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“…The mirrors shown in Figure 1 are 100-microns square with 1-micron gaps between mirrors. Earlier mirror work [3,4] demonstrated single micromirrors capable of large rotations. Figure 5 illustrates a micro-flex mirror in the actuated position.…”

Section: Designmentioning

confidence: 99%

<title>Pivoting micromirror designs for large orientation angles</title>

Garcia

2000

SPIE Proceedings

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This paper describes mechanical design concepts for a class of pivoting micromirrors that permit relatively large angles of orientation to be obtained when configured in large arrays. Micromirror arrays can be utilized in a variety of applications ranging from optical switching to beam-front correction in a variety of technologies [1,2]. This particular work is concerned with silicon surface micromachining (SMM). The multi-layer polysilicon surface micromachining process developed at Sandia National Laboratories is used to fabricate micromirror arrays that consist of capacitive electrode pairs which are used to electrostatically actuate mirrors to their desired positions and suitable elastic suspensions which support the 2 pm thick mirror structures. The designs described have been fabricated and successfully operated. Figure 1 illustrates a 100-~m x 100-ym micromirror actuated to 10°.

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Surface-micromachined microoptical elements and systems

Cited by 119 publications

References 17 publications

Surface tension-powered self-assembly of microstructures - The state-of-the-art

Surface tension-powered self-assembly of microstructures - The state-of-the-art

Self-assembled 3-D silicon microscanners with self-assembled electrostatic drives

<title>Pivoting micromirror designs for large orientation angles</title>

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