A wafer-scale membrane transfer Process for the fabrication of optical quality, large continuous membranes

• Published in: Journal of microelectromechanical systems 2003-12, Vol.12 (6), p.804-815
• Main Authors: Eui-Hyeok Yang, Wiberg, D.V.
• Format: Article
• Language: English
• Subjects: Actuators; Applied sciences; Area measurement; Biomembranes; Construction; Corrugating; Electrodes; Electronics; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Interferometers; Lenses, prisms and mirrors; Lithography, masks and pattern transfer; Mechanical instruments, equipment and techniques; Membranes; Microelectronic fabrication (materials and surfaces technology); Micromechanical devices and systems; Mirrors; Optical device fabrication; Optical elements, devices, and systems; Optical interferometry; Optics; Physics; Polymers; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Silicon; Single crystals; Wafer bonding
• ISSN: 1057-7157; 1941-0158
• DOI: 10.1109/JMEMS.2003.818454

This paper describes a new fabrication technique developed for the construction of large area mirror membranes via the transfer of wafer-scale continuous membranes from one substrate to another. Using this technique, wafer-scale silicon mirror membranes have been successfully transferred without the use of sacrificial layers such as adhesives or polymers. This transfer technique has also been applied to the fabrication and transfer of 1 /spl mu/m thick corrugated membrane actuators. These membrane actuators consist of several concentric-ring-type corrugations constructed within a polysilicon membrane. A typical polysilicon actuator membrane with an electrode gap of 1.5 /spl mu/m, fabricated using the wafer-scale transfer technique, shows a vertical deflection of 0.4 /spl mu/m at 55 V. The mirror membranes are constructed from single-crystal silicon, 10 cm in diameter, and have been successfully transferred in their entirety. Using a white-light interferometer, the measured average peak-to-valley surface figure error for the transferred single-crystal silicon mirror membranes is approximately 9 nm as measured over a 1 mm/sup 2/ membrane area. The wafer-scale membrane transfer technique demonstrated in this paper has the following benefits over previously reported transfer techniques: 1) No postassembly release process to remove sacrificial polymers is required. 2) The bonded interface is completely isolated from any acid, etchant, or solvent during the transfer process, ensuring a clean and uniform membrane surface. 3) Our technique is capable of transferring large, continuous membranes onto substrates.