Mechanism of nanostructure movement under an electron beam and its application in patterning

In electron microscopy, the motion of the sample features due to the interaction with the electron beam has been traditionally regarded as a detrimental effect. Uncontrolled feature displacement produces artifacts both in imaging and patterning, limiting the resolution and distorting precise nanoscale patterns. The mechanism of such motion remains largely unclear. We present an experimental study of e-beam-induced nanopost movement and offer a mechanistic theoretical model that quantitatively explains the physical phenomenon. We propose that e-beam bombardment produces an uneven distribution of electrons in the sample, and the resulting electrostatic interactions provide forces and torques sufficient to bend the nanoposts. We compare the theoretical predictions with a series of controlled experiments that support our model. We take advantage of this theoretical understanding to demonstrate how this generally undesirable effect can be turned into an unconventional e-beam writing technique to generate pseudo-three-dimensional structures. © 2011 American Physical Society.