Microforming of three-dimensional microstructures from thin-film metallic glass

Thin-film metallic glasses (TFMGs) are characterized by an absence of size effect, high strength and high elastic limit due to their amorphous nature. As such, these materials are considered to be ideal candidates for microelectromechanical systems (MEMS). Furthermore, the TFMGs soften and show viscous flow within a certain temperature range called the supercooled liquid region (SCLR), which allows the TFMGs to be easily formed into three-dimensional (3-D) microstructures. The viscous flow in the SCLR is also useful for annealing and relaxing inner residual stresses of TFMGs. In the present paper, TFMG microcantilevers are fabricated by surface micromachining techniques. In order to heat and form the cantilevers, a local laser heating and microforming system is introduced, and the conditions of laser power and heating time that can not only form the cantilevers but also can maintain the amorphous nature of the TFMG are examined. Finally, based on the results of these investigations, microcantilevers having a 90/spl deg/ bend and a 90/spl deg/ twist, respectively, are successfully fabricated.

[1]  A. Shimokohbe,et al.  A micro lens actuator for optical flying head , 2002, Technical Digest. MEMS 2002 IEEE International Conference. Fifteenth IEEE International Conference on Micro Electro Mechanical Systems (Cat. No.02CH37266).

[2]  Akira Shimokohbe,et al.  Thermal, Mechanical and Electrical Properties of Pd-Based Thin-Film Metallic Glass , 2001 .

[3]  Akira Shimokohbe,et al.  Fabrication of thin film metallic glass and its application to microactuators , 1999, Smart Materials, Nano-, and Micro- Smart Systems.

[4]  Martina Rothe,et al.  Application of ultraviolet depth lithography for surface micromachining , 1995 .

[5]  A. Yavari,et al.  High packing density of Zr- and Pd-based bulk amorphous alloys , 1998 .

[6]  A. Shimokohbe,et al.  Thin film metallic glasses: fabrication and property test , 2001, Technical Digest. MEMS 2001. 14th IEEE International Conference on Micro Electro Mechanical Systems (Cat. No.01CH37090).

[7]  Hee-Won Jeong,et al.  Micro-forming of thin film metallic glass by local laser heating , 2002, Technical Digest. MEMS 2002 IEEE International Conference. Fifteenth IEEE International Conference on Micro Electro Mechanical Systems (Cat. No.02CH37266).

[8]  Wenmin Qu.  3D UV-microforming: principles and applications , 1999 .

[9]  T. Kawai,et al.  Ultra-precision micro structuring by means of mechanical machining , 2001, Technical Digest. MEMS 2001. 14th IEEE International Conference on Micro Electro Mechanical Systems (Cat. No.01CH37090).

[10]  Y. Saotome,et al.  Superplastic micro-forming of microstructures , 1994, Proceedings IEEE Micro Electro Mechanical Systems An Investigation of Micro Structures, Sensors, Actuators, Machines and Robotic Systems.

[11]  K. Samwer,et al.  Thermal expansion of amorphous Zr Al Cu Ni in the vicinity of the glass transition , 2000 .

[12]  P. McNally,et al.  A comparative study of Pd/Sn/Au, Au/Ge/Au/Ni/Au, Au-Ge/Ni and Ni/Au-Ge/Ni ohmic contacts to n-GaAs , 1998 .

[13]  D. Turnbull,et al.  Evidence of a Glass-Liquid Transition in a Gold-Germanium-Silicon Alloy , 1968 .

[14]  W. Johnson,et al.  Viscosity, Relaxation and Crystallization Kinetics In Zr-Ti-Cu-Ni-Be Strong Bulk Metallic Glass Forming Liquids , 1998 .