Single-Crystal Silicon Micro-Opto-Electro-Mechanical Devices
We present in this paper, micro-opto-electro-mechanical devices made of singlecrystalline
silicon (S.C.S.) along with the corresponding micro-fabrication technological
processes. These micro-components are micro-lenses, vertical mirrors for optical
crossconnects, and magnetically-driven optical scanners. First, micro-lenses are presented.
The so-called MEMSNAS micro-fabrication process was used. It allows the realization of
three-dimensional (3D) micro-objects of nearly all shapes, which was successfully applied
for manufacturing silicon lens. This is a one-mask process that uses equipment, widespread
in microelectronics. Then, we present self-aligned vertical mirrors and V-grooves for optical
switching applications. For this purpose, we used a micro-fabrication process based on
anisotropic wet etching by potassium hydroxide (KOH), optionally in combination with Deep
Reactive Ion Etching (DRIE). This process lead to thin (down to 3 microns) and tall (up to
500 microns) S.C.S. vertical mirrors and V-grooves, which are naturally aligned at 45
degrees one to the other, thanks to the (100) and (110) crystalline directions in SCS. Finally,
we present optical scanners with integrated piezoresistive strain gages, which provide autooscillation
capabilities to these devices when combined with the integrated magnetic
excitation, either magnetostrictive or galvanic using Laplace force. Furthermore, the
integrated strain gages are able to selectively detect different vibration modes such as
bending and torsion. This feature provided a way to implement 2D scanning functionality.
tarik BOUROUINA, Philippe HÉLIN, Olivier FRANÇAIS
Lens, Mirror, Switch, Scanner, MOEMS, 3D Micro-Machining, DRIE, KOH.