DESIGN AND CHARACTERIZATION OF A PLANAR MAGNETRON RADIOFREQUENCY GLOW-DISCHARGE SOURCE FOR ATOMIC-EMISSION SPECTROMETRY

A planar magnetron radio-frequency-powered glow discharge source has b een constructed and characterized. Electrical behavior, sputtering rat es, and emission properties of the source have been studied with both conducting and insulating samples over a pressure range of 0.05 to 0.6 Torr, and over a forward-power range between 30 and 120 W. The bias v oltage showed little or no dependence on power or on pressure between 0.2 and 0.6 Torr. However, at lower pressures there was a sharp increa se in the voltage as pressure was dropped, signaling a change in the o perational mode of the discharge. The magnetron source proved to have much higher sputtering rates for both conducting and insulating sample s than a similar source without a magnet; the highest sputtering rates were found at 0.05 Torr. The dependence of emission on pressure was s imilar to that of previously described d.c. magnetron sources. Detecti on limits ranged from 1 to 50 ppm for elements in a conducting matrix.