Magnetically Enhanced Dual Frequency Capacitively Coupled Plasma Source for Large-area Wafer Processing

概要

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A magnetron-type plasma source of parallel plate configuration has been developed for large-area wafer processing in the semiconductor industry. In this plasma source there are 80 equally separated magnets arranged with alternative polarities on a 40-cm-diameter top rf electrode. These magnets generate magnetic field cusps below the top rf electrode. Since electrons that lie in the magnetic field cusps are confined, a lower self-bias voltage of the top rf electrode results. With this magnet arrangement, the E × B drifts of charged particles are limited to smaller localized areas and canceled out in macro-scale. Therefore, the radial uniformity of the plasma does not differ much from that of a nonmagnetic parallel plate capacitively coupled plasma source. The plasma density of this magnetron-type plasma source monitored at 1.3 Pa is above 10^<11> cm^<-3> for rf powers over 1000 W. The plasma nonuniformity over φ300 mm area is <±5% at the pressures below 4 Pa. Further, this magnet arrangement yields a magnetic-field-free environment for wafer processing in the close vicinity of the top rf electrode-a feature that cannot be seen in most of the magnetron-type plasma sources.
社団法人応用物理学会の論文
1998-11-15