HIGH-DENSITY FLAT PLASMA PRODUCTION BASED ON SURFACE-WAVES

Recent development of large-diameter (>30 cm) high-density (>10(11) cm (-3)) microwave plasma production at low pressures (<20 mTorr) without an external DC magnetic field is reviewed in view of application to t he next generation ULSI devices and flat panel displays. Understanding the discharge physics-excitation, propagation and absorption of the s urface wave in a flat plasma geometry under overdense conditions (omeg a(p) much greater than omega)-is indispensable for controlling the pla sma. Experimental evidence of discrete surface-wave modes is clearly f ound in optical emission and microwave field measurements. The analysi s of the full-wave electromagnetic dispersion successfully identified the observed eigenmodes. Stability analysis of the wave-plasma interac tion resulted in a stability criterion predicting hysteresis loops in the power-density dependence, which were found in the experiment. A po ssibility of collisionless absorption of surface waves, i.e. mode conv ersion to electron plasma waves at the resonant layer, is discussed wi th the recent experimental results taken into account. From the plasma technology point of view, examples of surface-wave plasma tools (some of them commercially available) are introduced and the significance o f the antenna structure is emphasized. Finally, the advantages of the surface-wave plasma source in comparison with other high-density sourc es are summarized.