Characteristics of high power ion beam produced in plasma focus and its application to semiconductor processing

To apply an intense pulsed ion beams produced in plasma focus (PF) to material processing, characteristics of the beam was evaluated. In the experiment a Mather type PF was used which was pre-filled with N2 (5.5 Pa) to produce nitrogen ions. To clarify the mechanism of the production of impurity ions, two types of anode (type A; rod type and has an anode tip on the top, type B; hollow shape top) were used. In both type peak discharge currents of 550 kA were obtained at 1.5 µs after the rise of the current. From the measurement by Thomson parabola spectrometer large quantity of copper ions were observed when type A is used and the purity for type A and type B were evaluated to be 26 % and 90 %, respectively. To enhance the energy and the charge state of the nitrogen ions the PF with type B anode was pre-filled with mixture of nitrogen and hydrogen (N2 20, H2 180 Pa). From the TPS measurement, multiply ionized nitrogen ions (N¹⁻⁵⁺) of energy more than several MeV were observed with protons of maximum energy 1 MeV. Thin layer of amorphous silicon was irradiated by the ion beams produced in PF and we found that the layer was crystallized.