Abstract by Ryan Vanfleet
Physics and Astronomy
Robert Davis, Richard Vanfleet, David Allred
Controlling Reactant Exposure in Tungsten Atomic Layer Deposition
A homebuilt Atomic Layer Deposition (ALD) system for the deposition of tungsten (W) on Carbon Nanotubes (CNTs) has been recently rebuilt. The initial configuration of the ALD system led to waste of the reactants, Silane (SiH4) and tungsten hexafluoride (WF6). The completed reconfiguration did not produce the expected attenuation of reactant pressures in the deposition chamber. A study of process valve speeds revealed sub-optimal programming and slowly-closing valves that explain the lack of pressure attenuation. CNT forests show non-uniform deposition in the form of abrupt steps (spaced 10-100 um apart) of decreasing W thickness and small, localized areas of increased deposition (about 1 um in diameter). The non-uniform depositions seem to be a function of exposure (pressure*time) to the ALD reactants.