Development of Process Techniques for Bistable Microbeam Fabrication

• Main Author: Francis, Varsha
• Other Authors: Martin Feldman
• Format: Others
• Language: en
• Published: LSU 2005
• Subjects: Electrical & Computer Engineering
• Online Access: http://etd.lsu.edu/docs/available/etd-08252005-130402/

A design which uses bistable beams to modulate light is suggested in this thesis and appropriate processing techniques are presented. A beam when placed under compression above the Euler limit has two stable states. The compression in an electroplated beam can be controlled by the plating current density of nickel during electrodeposition. This beam is attached to an electromechanical comb. Voltages applied to the combs cause the beam to snap from one stable state to another. Structures were designed with dimensions that gave feasible voltages, snap distances, compressions required to snap. A two mask process was used for the fabrication of the device. The first mask delineates the sacrificial layer (AZ P4620) and the second mask delineates the electroplating mould (SU8-50). Developing techniques such as mechanical stirring at room temperature obtained bistable beam lengths of up to 1mm having an aspect ratio of 4. For higher aspect ratios such as 10 the amount of developed beam length was 200um. The dimensions that could be obtained were not adequate for practical applications. Use of better equipment such as a mega sonic bath is suggested to improve the development in the bistable beam length. Reducing the bistable beam lengths is also suggested as an option.