Manufacture of Micromirror Arrays Using a CMOS-MEMS Technique

Abstract

In this study we used the commercial 0.35 μm CMOS (complementary metal oxide semiconductor) process and simple maskless post-processing to fabricate an array of micromirrors exhibiting high natural frequency. The micromirrors were manufactured from aluminum; the sacrificial layer was silicon dioxide. Because we fabricated the micromirror arrays using the standard CMOS process, they have the potential to be integrated with circuitry on a chip. For post-processing we used an etchant to remove the sacrificial layer and thereby suspend the micromirrors. The micromirror array contained a circular membrane and four fixed beams set symmetrically around and below the circular mirror; these four fan-shaped electrodes controlled the tilting of the micromirror. A MEMS (microelectromechanical system) motion analysis system and a confocal 3D-surface topography were used to characterize the properties and configuration of the micromirror array. Each micromirror could be rotated in four independent directions. Experimentally, we found that the micromirror had a tilting angle of about 2.55° when applying a driving voltage of 40 V. The natural frequency of the micromirrors was 59.1 kHz.

Scanning Micromirror Platform Based on MEMS Technology for Medical Application

“…With a platform’s dimension of 1.4 mm × 1.7 mm, the performances of the device are at 0.3° on two axes at 55 V with a resonant frequency of 181 Hz and 45 Hz for outer frame and mirror respectively. Moreover, surface electrostatic actuators can perform up to three DOFs by using a CMOS technique [ 54 ]. For a tip-tilt-piston stage, Kao et al reported an electrostatic phenomenon of parallel plates.…”

Multipurpose Drivers for MEMS Devices Based on a Single ASIC Implemented in a Low‐Cost HV CMOS Process without a Triple Well

“…Besides DC biasing, MEMS sensors often require accurate control voltages, as well. A DC voltage programmable between 5 V and 45 V was used in [10] to control the tilting angle of micromirrors between 0.24°and 2.55°; in [11], DC voltages up to 30 V were applied to the top or middle membranes of capacitive mass-based MEMS sensors, to enhance their operational properties, particularly their sensitivity. MEMS varicaps have similar requirements: the voltage levels used in [12] varied from 10 V to 22 V, while in [13], the range was from 0 to 20 V.…”

“…However, the continuous quest for size and cost reduction demands MEMS devices to work in conjunction with integrated circuits manufactured in low-cost CMOS processes and even to be realized on the same CMOS substrate-the CMOS MEMS monolithic integration [18]. Complex MEMS devices can be integrated alongside electronic circuitry in a standard CMOS process, with only mask-less post-CMOS processing [10].…”

“…These limitations require that new topologies and circuit solutions are developed for MEMS drivers that can be implemented in such low-cost HV CMOS technologies. Additional design challenges are brought in by the applications envisaged here: low-cost single-ASIC drivers for MEMS mirrors used in endoscopic optical coherence tomography (OCT) [23] and similar precision applications [10]. An extended review of such devices was presented in [23]: it showed that large voltage levels (16 V to 300 V) are required to obtain large tilting/scan angles (±2°to ±20°) and also that voltage levels need to be precisely controlled and programmable in fine steps and should exhibit a very low-voltage ripple.…”

Cobalt Oxide Nanosheet and CNT Micro Carbon Monoxide Sensor Integrated with Readout Circuit on Chip

“…The manufacturing technique which uses the commercial CMOS process to fabricate MEMS devices is called CMOS-MEMS [ 14 – 16 ]. Micro devices made by the CMOS-MEMS technique usually need a post-process to coat the functional films [ 17 ] or to release the suspended structures [ 18 ]. For example, Liu et al [ 17 ] coated a sensitive film of polyaniline nanofiber on a micro ammonia sensor using a post-process.…”