| AVS 64th International Symposium & Exhibition | |
| MEMS and NEMS Group | Tuesday Sessions |
| Session MN+BI+EM+SS+TR-TuM |
| Session: | Microelectromechanics: Relays to RF/Surfaces in Micro- and Nano- Systems |
| Presenter: | MaiPhuong Nguyen, WPI-Advanced Institute for Materials Research (WPI-AIMR)/ Micro System Integration Center (µSIC), Tohoku University, Japan |
| Authors: | M.P. Nguyen, WPI-Advanced Institute for Materials Research (WPI-AIMR)/ Micro System Integration Center (µSIC), Tohoku University, Japan J. Froemel, WPI-Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, Japan S. Tanaka, Graduate School of Engineering/ Micro System Integration Center (µSIC), Tohoku University, Japan |
| Correspondent: | Click to Email |
Micro Electro-Mechanical Systems (MEMS) microphones have been extensively developed and introduce into mobile phones market with high performance such as high signal to noise ratio, good sensitivity, and power consumption and good reliability in term of packages. Up to now, most studies have been focused on the improvement of sensitivity of microphone which is proportional to the compliance of the membrane. However, no significant progress has been achieved due to the limitation of material itself. Generally, single crystal and polycrystalline silicon based devices are brittle and fracture causing the interior defects during the fabrication processes. Therefore, the research of new materials to substitute polycrystalline silicon is necessary. Amorphous metals exhibit no grain boundaries, crystal defects and excellent mechanical properties such as fatigue free, large elastic limit, high strength, corrosion resistance which has been promising materials for MEMS devices such as micro-scanner, RF MEMS varactor, capacitive switch ... Metallic glasses are a kind of amorphous alloy exhibiting viscous flow at a certain temperature range so-called “supercooled liquid region”. In the supercooled liquid region, metallic glasses can be easily produced through a variety of fast-cooling methods and have excellent mechanical formability. In addition, metallic glass thin films are easily prepared on Si or SiO2 substrates by sputtering technique which is compatible with MEMS processes such as photolithography, dry or wet etching and lift off processing. Therefore, characterization and fabrication of metallic glasses films deposited by sputtering for MEMS microphone will be studied.
The CoTaB films with thicknesses in the range of 100 nm to several micrometers have been successful deposited on thermal SiO2 substrates by rf-sputter technique. The amorphous structure with smooth surface and negligible magnetic property was confirmed by TEM, AFM, XRD and SQUIDS measurement, respectively. The metallic glass behavior was investigated by DSC analysis which shows the glass transition and crystalline temperature of 700 and 720.9 C, respectively. In addition, the mechanical properties such as stress, stress gradient and Young modulus have been studied by using pointer and cantilever structure. Co-based metallic glass exhibited tensile and compressive stress depending on sputter conditions, thicknesses as well as further treatment process. Additional results will be presented in detail at the conference with an emphasis on the dependence of the process conditions.