| 摘要 |
PROBLEM TO BE SOLVED: To decrease the component ratio of hydrogen ions contained in an ion beam drawn out of a high frequency ion source by setting the intensity of a cusped magnetic field in a sheath formed between a high frequency electrode and plasma in a specified value. SOLUTION: A sheath 36 in which electrons are rarefied according to the difference between the mobility of electrons and that of ions (the former is substantially higher) within plasma 16 is formed between a high frequency electrode 6 and the plasma 16. Since an electric field caused by sheath voltage and a magnetic field caused by a cusp magnetic field are applied to the sheath 16, electrons conduct drift motion within the sheath 36. In this case, the intensity of the cusped magnetic field within the sheath 36 formed between the high frequency electrode 6 and the plasma 16 is set to 1-3 mT (mili tesla). An ion beam 28 is stably drawn out, and component ratio of hydrogen ions contained in the ion beam 28 can be decreased. As a result, the generation of troubles caused by hydrogen ions contained in the ion beam can be avoided.
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