CHARACTERISTICS OF AN 8-CM-DIAM ELECTRON-CYCLOTRON RESONANCE SOURCE FOR PLASMA PROCESSING

Performance and characteristics of a microwave source designed for the generation of overdense (N(e) > N(cr) = 7.4 X 10(10) cm-3) uniform plasmas are presented. Microwave power (f = 2.45 GHZ, P = 20-1000 W) was introduced into the cylindrical nonresonant (for any TE and TM microwave modes) cavity (D = 8.25 cm, L = 22 cm) via a matched dielectric window. Two magnetic coils produced the axial static magnetic field of B > B(ce) = 875 G. Two plasma stream modes were observed: (i) narrow mode with a maximum plasma density on the axis, and with the magnetic field near the introduction window of B < 960 G; and (ii) wide mode with lower but uniform plasma density across the stream, and with magnetic fields near the window of 1000-1200 G. Ion current density of 7-8 mA/cm2 was typical for the narrow mode, and 4-5 mA/cm2 for the uniform mode. Ion current density relationship with gas pressure and microwave power is discussed.