ETCHING MATERIALS WITH AN ATMOSPHERIC-PRESSURE PLASMA-JET

A plasma jet has been developed for etching materials at atmospheric p ressure and between 100 and 275 degrees C. Gas mixtures containing hel ium, oxygen and carbon tetrafluoride were passed between an outer, gro unded electrode and a centre electrode, which was driven by 13.56 MHz radio frequency power at 50 to 500 W. At a flow rate of 51 l min(-1), a stable, are-free discharge was produced. This discharge extended out through a nozzle at the end of the electrodes, forming a plasma jet. Materials placed 0.5 cm downstream from the nozzle were etched at the following maximum rates: 8.0 mu m min(-1) for Kapton (O-2 and He only) , 1.5 mu m min(-1) for silicon dioxide, 2.0 mu m min(-1) for tantalum and 1.0 mu m min(-1) for tungsten. Optical emission spectroscopy was u sed to identify the electronically excited species inside the plasma a nd outside in the jet effluent.