Removal of Multi-Walled Carbon Nanotubes From Contaminated Surfaces With Microscale Topological Features

Experiments were performed to examine the ability of surfactants to remove multi-walled carbon nanotubes (MWCNTs) from silicon wafers with nano and micro scaled features. Well-defined microscale topological features on silicon wafers were induced using photo lithography and plasma etching. The etching time was varied to create variation in topological features with the size and height of ∼ 8±1 μm, and ∼2±1 μm, respectively. MWCNTs in the form of pristine liquid solution were deposited on the surface of silicon wafers using the spin coating process. During cleaning, the contaminated surfaces were first sprayed with one of the two surfactants, sodium dodecyl sulfate (SDS) and sodium dodecyl benzene sulfonate (SDBS), or water. MWCNTs were wiped off using a wiping mechanism. The area density of the MWCNTs was quantified prior to and after their removal using scanning electron microscopy (SEM) and post-image processing. The results show decreasing removal efficiency for all the surfactants as the topological features on the wafers deepen through increasing the etching time. Surfactants show better decontamination efficiency compared with water.