Thesis Title

Fabrication Of Mems Bridges Using Electron=Beam Evaporated Sio2

Date of Graduation

Summer 2006


Master of Science in Materials Science


Physics, Astronomy and Materials Science

Committee Chair

Ryan Giedd


MEMS bridges, biosensor, e-beam evaporation, silicon dioxide, SiO2

Subject Categories

Materials Science and Engineering


To meet the demands for more precise bio-detection methods, a biosensor device based on a micro electro-mechanical system (MEMS) bridge platform was suggested by Giedd et al.1 Therefore, in order to build MEMS bridges, we have used e-beam evaporated silicon dioxide (SiO2) as a sacrificial layer. Feasibility of this fabrication process has been proved in this work. A detailed recipe for building MEMS bridges is provided. Bridges which were built consist of gold (Au) pillars and photoresist (PR) coated aluminum (Al) bridge surfaces. Dimensions of the Au pillars are 125æm x 125æm x 2.5æm. Remaining on the pillars, 2.5æm above the substrate surface, are 25æm wide and 50æm long, PR coated Al bridge surfaces. Besides the e-beam evaporation which was described in detail, other techniques used in the process were also introduced. Properties of the e-beam evaporated SiO2 thin film, obtained concurrently, were: the etch rate, dielectric constant, film uniformity, and film pinholing. Etch rate of 83Å/sec, when using etchant solution with a 2-4% content of hydrofluoric acid (HF), was found. Dielectric constant values which varied from 5.38 to 8.32 have been measured. Values of the obtained properties have led us to conclude that the e-beam evaporated SiO2 thin films have relatively high content of silicon (Si-rich). Better understanding of the e-beam evaporated SiO2 thin films helped us acquire the results sought for in the development of MEMS bridges.


© Aleksandar Jankovic