First adhesion measurements of conductive ultrananocrystalline diamond MEMS sidewalls

Abstract

We present the first measuremenst of adhesion between two micro-electromechanical systems (MEMS) surfaces, fully fabricated with boron doped ultrananocrystalline diamond (B-UNCD). This research allows us to explore the potential of conductive UNCD MEMS for the solution of issues like adhesion and friction in micro-devices and describe with accuracy the effects involved. By means of standard lithographic techniques, we have fabricated a diamond micro thermal actuator (chevron type), which is used as a platform for tribological testing. A peculiar effect has been observed in the adhesion phenomenon of UNCD. It involves with high probability, an interaction between hydrocarbon/amorphous carbon layers (a-C) that cover the two diamond contacting surfaces. The as-etched device shows a 'chewing-gum' effect in the adhesion curve, probably due to the formation of hydrocarbon/a-C chains after the interaction of the surfaces. This effect disappears when the device is treated in oxygen plasma and the hydrocarbon/a-C is removed. The study of this phenomenon will be followed by more accurate analysis and atomistic simulation and the results will be compared with nitrogen-incorporated UNCD (N-UNCD) fabricated devices.

Studies on measuring surface adhesion between sidewalls in boron doped ultrananocrystalline diamond based microelectromechanical devices

“…The presence of a thin layer of superficial amorphous carbon or environmental organic impurities on the sidewalls can be the result of the etching process, releasing and handling in an un-protected environment. This effect was previously observed in [42], where the measured adhesion curves revealed a gradual snap-off. When cleaned, in oxygen plasma, the effect was not visible anymore, leading us to suppose that a superficial amorphous carbon layer was causing this effect.…”

Observation of nanoscale adhesion, friction and wear between ALD Al2O3coated silicon MEMS sidewalls

“…Figure 6 presents a simplified set of sketches that show how the micro devices composing the tribotester were actuated during the tests. The detailed description of the measurement procedure, along with the working principle of these devices, can be found elsewhere [8,[14][15][16].…”