Microstripline Circuits for Microwave Plasma Discharges
Widely used in a variety of products and processes, plasmas are generated by applying a voltage between electrodes to facilitate gas ionization. The voltage may be static (DC) or varying at a fixed rate that can be in the RF range (<100 KHz) or as high as tens of MHz in frequency. Typical plasmas have a characteristic physical dimension on the order of 40 to 80 cm. Smaller plasmas can be generated via waveguide or cavity structures and exciting frequencies in the microwave regime (>1 GHz). However, the necessary electrode structures become increasingly small and more difficult to fabricate as the target size of the discharge is reduced.
Description of Technology
MSU’s invention is a method for using stripline microwave applicators for the creation of plasma discharges with a characteristic physical dimension between a millimeter and tens of microns. The microstripline conductors that couple the microwave energy (at 300 MHz to 30 GHz) are transverse to the microwave discharge.
- Small size: The plasma can be as small as 10 to 20 microns.
- Volume expansion: A surface wave created in the plasma can extend the plasma far outside the excitation region in one dimension.
- Low power: RF power as low as 1 to 2 watts is sufficient to excite the plasma.
- Ease of manufacturing: Well known, mature, and easily fabricated microstripline technology is used for the actuator structure. These structures can be easily integrated with MEMS technology to create system-on-a-chip (SOC) structures.
- High density: The high density plasmas
Miniature plasmas can be used in a wide variety of applications:
- Chemical/biological lab-on-a-chip devices
- Small spectrometers, lights, ion pumps, and gas flow controllers
- Localized semiconductor processing
- Cleaning, sterilization, or coating of MEMS structures
- Manufacturing of highly uniform nanoparticles from gas precursors
- Functionalized polymers, tunable plasma antennas, and paint removal
Timothy Grotjohn, Jes Asmussen, Andy Mijaya
For Information, Contact:
Michigan State University