Development of Low-Energy Particle-Beam Sources for Super-fine Plasma Processing

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In order to realize super-fine plasma processings, several requirements should be satisfied : Ions incident on a substrate should have a monochromatic parallel velocity and a low energy not to give rise to damage, and also a high-flux, uniform, and large beam is necessary. These requirements will be met by developing a low-pressure, large-area, high-density plasma with the low plasma potential. To do this, we have developed a novel plasma production by an inductively coupled rf discharge under a surface magnetic field.Multi-dipole surface magnetic fields produce following effects ; good confinement of high energy electrons, enhancement of plasma production, reduction of bulk-electron diffusion loss, and the resultant increase in plasma density as well as the uniformity. The decrease in the plasma potential is also expected.Promising results were obtained in our prototype device with surface magnetic confinement as follows :1. The discharge plasma was sustained at low pressures such as Torr.2. A uniform, large-diameter (-40cm), high-density plasma with low plasma potential (-20 V) was obtained.3. The plasma potential was controllable with an externally biased small electrode.On the other hand, we have studied ion-induced radical production on surfaces ; fragmentation of high-energy poly-atomic ions at their impact on surfaces. This type of plasma-surface interactions is of interest since it can be applied to a new source of radical beams.