A STUDY ON PROCESS LIMITATIONS AND SCOPES OF MICRO-MANUFACTURING TECHNIQUES FOR THE FABRICATION OF MEMS TORSIONAL ACTUATORS
Keywords:
Microfabrication, Surface Micromachining, PolyMUMPS, SOI, Process-induced residual stress, Thin plate electrodes , Film ThicknessAbstract
A theoretical study on the various micro fabrication techniques such as surface micromaching, Silicon-On-Insulator (SOI), polyMUMPS, and identifying the process limitations and suggesting new scopes in the microfabrication process sequence for the development of MEMS devices with better performance. A multi-layer, multi-step lithography process is used in fabrication of micro actuators in silicon as base materials and oxide layers and metal layers combination. Selective deposition of metal on microstructures using poly silicon multi user MEMS process (polyMUMPS). The deposited metal layer thickness invariably induces tensile or compressive residual stress which will affect the operating characteristics the device. The fabrication sequences such as deposition, etching, annealing at different temperature level significantly affect the mechanical properties of the torsional type switching device. The deposited metal increases the stiffness and the effective mass of the laminated structure. The residual stress increases or decreases the net stiffness if it is a tensile or compressive type respectively. The process-induced residual stresses present in the planer structures of the micro-switch should be reduced for its effective and improved performance
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