Fabrication of Optical Microelectromechanical-System Switches Having Multilevel Mirror-Drive Electrodes

Abstract

This work describes a practical and high-yield method of fabricating optical microelectromechanical-system (MEMS) switches. The method features the use of thick-plated gold multilevel interconnections for the mirror-drive electrodes and polyimide coating to protect the fragile and easily-movable micromachined mirror. The multilevel electrode developed was over 80-µm high providing enough space for the tilting mirror placed above it. Open-short circuit yield was 100% on 6-inch wafers. All the processes for fabricating the electrodes were carried out at under 310°C, meaning the electrodes could be successively formed after mirror-control large-scale integrated circuits (LSIs) were fabricated on a wafer. The fragile mirrors are sealed in polyimide during the fabrication processes. As this method protects the mirrors against the shock and damage caused by factors such as the dicing process, it enables 3-dimensional MEMS structures that have moving portions to be handled through conventional fabrication processes without the need for any special care. The static and dynamic characteristics of the optical MEMS switches fabricated are shown.

Deformation and Restoration of Shape in Microelectromechanical System Membrane

“…11,12 However, the process often causes the z E-mail: sakata.tomomi@lab.ntt.co.jp oxidization of the Si membrane surface, which results in unexpected movement of the membrane due to the charge accumulated in the oxidized surface. Therefore, the oxidized surface has to be removed to prevent such charge drift.…”

Scaling Limits of MEMS Beam-Steering Switches for Data Center Networks

“…3). Gap closing actuators are typically fabricated with parallel (flat) plate electrodes [12], but we also considered a ramped electrode design, which has been shown to have improved voltage response [13]. In addition to in-plane gimbaled two-axis tilt mirrors, we considered variations with the support structures hidden under the mirror [14], [15].…”

Monolithic integrated MEMS mirror array module towards low electrical interference

“…The mirror, torsion spring, and cantilever patterns are formed on the BOX by photolithography and a Bosch process with inductively coupled plasma-reactive ion etching (ICP-RIE) of the pattern. Then, an organic film is spin-coated on top to protect the mirrors from damage during the remaining steps, such as dicing [3]. Here, the resist mask for comb-shaped walls and mirror release is simultaneously formed on the bulk Si on the reverse side and then the Bosch process with ICP-RIE is carried out.…”