Date of Award
Master of Science in Electrical Engineering - (M.S.)
Electrical and Computer Engineering
William N. Carr
N. M. Ravindra
Michael J. Grieco
Tantalum silicide was studied as an alternative microelectromechanical material by fabricating a rotary micromotor utilizing a proven design. This material was used for the rotor, stators, and bearing over a silicon substrate. It has the attraction of potentially reducing the friction which is a major problem with polysilicon-to-polysilicon bearings.
The necessity of high aspect ratio features required that a plasma or reactive ion etch with a high degree of anisotropy be developed to etch tantalum silicide films in excess of 1.5μm. A sulfur hexafluoride/Freon 115 plasma provided the necessary process control during the etches. The stress present in annealed tantalum silicide films made it necessary to limit the maximum processing temperature to 300°C. These low temperature tantalum silicide films have thus far proved to be inadequate as a microelectromechanical material for the micromotor due to their inability to withstand the hydrofluoric acid release etch.
Berry, Michael Steven, "Tantalum silicide variable capacitance rotary micromotors : design and fabrication" (1993). Theses. 1266.