Effects of electron beam induced carbon deposition on the mechanical properties of a micromechanical oscillator

Electron beam induced deposition of amorphous carbon finds several uses in microlithography, surface micromachining, and the manufacturing of micro- and nanomechanical devices. This process also occurs unintentionally in vacuum chambers of electron microscopes and interferes with normal image acquisition by reducing resolution and causing charging effects. In this work, we show that the resonance frequency of a micromechanical oscillator can be significantly affected by exposing it to a focused electron beam, which induces local carbonization on the surface of the oscillator, resulting in increase in the effective stress along the beam. This in-situ carbonization can be utilized for analyzing the amount of residual organic contamination in vacuum chambers. In addition, the method described here allows post-fabrication fine tuning of mechanical resonance frequencies of individual oscillating elements.