eBid

Electron beam induced deposition (EBID) is a direct-write nanofabrication technique that uses a focused electron beam in a scanning or transmission electron microscope to decompose adsorbed precursor gas molecules and leave non-volatile fragments on a substrate, forming solid deposits with nanoscale precision. EBID enables maskless patterning and repair of nanoscale structures, without the need for lithographic masks.

Process: A gas injection system introduces organometallic or inorganic precursor gases to the substrate under high vacuum. The focused electron beam locally irradiates the adsorbed molecules; this causes their fragmentation and deposition of metal- or other-containing material, while volatile byproducts are pumped away.

Materials and control: The composition of the deposits depends on the precursor and processing conditions. Commonly used precursors include MeCpPtMe3 for platinum, W(CO)6 for tungsten, and other metal-containing sources; hydrocarbon precursors yield carbon-rich deposits. Deposition rate and purity are influenced by beam energy, current, dwell time, spot size, gas flux, and substrate temperature. The technique can produce features from tens of nanometers to the sub-10-nanometer scale; three-dimensional deposition is achieved by voxel-by-voxel writing strategies.

Applications and limitations: EBID is widely used for circuit editing and nanoscale prototyping, micro- and nanoelectromechanical systems repair, TEM sample preparation, and the creation of electrodes and contacts in nanoscale devices. Limitations include carbon and impurity content in deposits, relatively slow growth rates, dependence on precursor purity, and the need for high vacuum. Post-deposition treatments, such as annealing or plasma cleaning, are sometimes employed to improve conductivity or remove contaminants.