Invited Paper PS-ThA1
Damage Control: Electron Beam Generated Plasmas for Low T_e Processing

Thursday, October 31, 2013, 2:00 pm, Room 104 C

The advantages of plasma-based materials processing techniques are numerous. The capability to modify large (> 10³ cm²) areas with precision down to the nanoscale is one reason plasmas are widely used in the materials and surface engineering communities. However, with the rapidly evolving demand for new materials in applications ranging from organic and nanoelectronics to biosensors, some of the limitations of conventional plasma sources are becoming apparent. The lack of process control and excessive ion energies in the processing of soft or very thin materials 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 (~ 2 keV) electron beam. This approach provides a solution to many of the problems associated with conventional plasma processing systems, making it potentially useful in the development of a wide variety of novel materials. 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, ions leaving the plasma impact surfaces with energies in the range of 1 to 5 eV. This provides the ability to slowly etch and/or controllably engineer both the surface morphology and chemistry, critically important features for applications requiring atomically thin or smooth materials.

An overview of NRL’s research efforts in developing this technology with a focus on source development, plasma characterizations, and materials processing will be presented. Particular attention will be given to current efforts in the processing of polymers and 2-d materials such as graphene, where we take advantage of the unique attributes of electron beam generated plasmas to engineer the surface properties of these materials for electronic and sensing applications. This work is supported by the Naval Research Laboratory base program.