MSE Seminar Series: Scott Walton
Friday, September 11, 2015
1:00 p.m.-2:00 p.m.
Room 2108, Chemical and Nuclear Engineering Building
Electron Beam Generated Plasmas: Ultra low Te Sources for Atomic Layer Processing
Naval Research Laboratory
The advantages of plasma-based materials processing techniques are numerous. The capability to rapidly modify large (> 103 cm2) areas with precision down to a fraction of a micron is one reason plasmas are widely used in the materials and surface engineering communities. However, with the rapidly evolving demand for new materials and single nanometer-scale precision across a variety of applications, some of the limitations of conventional plasma sources are becoming apparent. The lack of process control and excessive ion energies in the development of atomic layer processing strategies are examples.
The Naval Research Laboratory (NRL) has developed a processing system based on an electron beam-generated plasma. Unlike conventional discharges produced by electric fields (DC, RF, microwave, etc.), ionization is driven by a high-energy (~ keV) electron beam, an approach that can overcome many of the problems associated with conventional plasma processing systems. Importantly, high plasma densities (1010- 1011 cm-3) can be produced in electron beam generated plasmas, while the electron temperature remains between 0.3 and 1.0 eV. Accordingly, a large flux ions can be delivered to substrate surfaces with kinetic energies in the range of 1 to 5 eV, a value comparable to the bond strength in most materials. This provides the potential for controllably etching and/or engineering both the surface morphology and chemistry with monolayer precision.
An overview of NRL’s research efforts in developing this technology will be presented, with a focus on source development, plasma characterizations, and materials processing. Particular attention will be given to the processing of polymers, graphene, and select semiconductor materials, where we take advantage of the unique attributes of electron beam generated plasmas to engineer the surface properties of these materials for specific applications. This work is supported by the Naval Research Laboratory base program.