Two-Axis Single-Crystal Silicon Micromirror Arrays

Abstract

This paper presents the design, fabrication, and testing of a two-axis 320 pixel micromirror array. The mirror platform is constructed entirely of single-crystal silicon (SCS) minimizing residual and thermal stresses. The 14-m-thick rectangular (750 800 m 2 ) silicon platform is coated with a 0.1-m-thick metallic (Au) reflector. The mirrors are actuated electrostatically with shaped parallel plate electrodes with 86 m gaps. Large area 320-mirror arrays with fabrication yields of 90% per array have been fabricated using a combination of bulk micromachining of SOI wafers, anodic bonding, deep reactive ion etching, and surface micromachining. Several type of micromirror devices have been fabricated with rectangular and triangular electrodes. Triangular electrode devices displayed stable operation within a ( 5 , 5 ) (mechanical) angular range with voltage drives as low as 60 V.[1124]Index Terms-Al etching, deep-reactive ion etching (DRIE), micromirrors, optical switching, silicon on insulator (SOI) wafers.

Fully programmable micro diffraction grating for VIS and near-IR spectroscopic applications

“…The thermally grown oxide does act as an etch stop for the Si handle removal in KOH; however, small pinholes in the thin oxide layer can allow small amounts of KOH to breach this masking layer causing damage to the silicon device layer. Dokmeki et al have shown that the device yield can be improved by removing the wafer stack from the KOH bath before reaching the oxide and removing the remaining handle layer using RIE [10]. The oxide layer is also removed by RIE before performing the final photolithography step to pattern the micromirrors and flexures into the SCS device layer (Fig.…”

MEMS optical switch: Switching time reduction

“…Similarly, the well known micromirror designed by Bell Labs [21,38] (Lucent Technologies, currently Alcatel-Lucent) and used in WaveStar Lambda Router has the same drawback. Another micromirror presented in [39] has natural frequencies in rotation about the x and y axis equal to 175 Hz and 394 Hz, respectively. The single-crystal silicon micromirror developed by Intellisense uses a heavy gimbal structure as well.…”

MEMS-based endoscopic optical coherence tomography

“…• have been achieved with lower driving voltages in the range of 40 V to 200 V, but the reported mirror aperture diameters are normally smaller than 500 µm [27][28][29][30][31][32][33][34]. What limits this structure from realizing larger scan angle is the pull-in effect.…”