A microfabricated inductively coupled plasma generator

The design, fabrication, and characterization of a surface micromachined plasma generator is described for the first time in this paper. The plasma is sustained without electrodes by inductively coupling a /spl sim/150-MHz current into a region of low-pressure gas, Both argon and air plasmas have been generated over a range of gas pressures from 0.1 to 10 torr (13.3-1333 Pa). Typically, the power used to sustain the plasma is 350 mW, although /spl sim/1.5 W is required to initiate the discharge. Network analysis of the plasma generator circuit shows that over 99% of the applied RF power can be absorbed by the device. Of this, /spl sim/50% is absorbed by the plasma and the remainder of the power is dissipated as ohmic heating. An argon ion current of up to 4.5 mA/cm/sup 2/ has been extracted from the plasma and the electron temperature is 52 000 K at 0.1 torr. This plasma source is intended for electronic excitation of gas samples so that the presence of impurities and toxins may be detected using optical emission spectroscopy.