| 摘要 |
An ion implantation apparatus includes an ion source for extracting ions therefrom at an extraction voltage, an acceleration pipe for accelerating the ions thus extracted at an acceleration voltage of VA and a momentum segregation magnet for selecting the ions having a specific momentum from the ions extracted from the acceleration pipe so that the desired ions are caused to be incident on a target. In the event that MI denotes the mass number of the desired ions, ZI denotes the valence thereof, MC denotes the mass number of noted impurity ions of the impurity ions generated an upstream side of the acceleration pipe, and ZC denotes the valence thereof, if the relationship that the value of MI.(VE+VA)/ZI and that of MC.VA/ZC are equal or approximately equal to each other is satisfied, one of the extraction voltage VE and the acceleration voltage VA is increased and the other thereof is decreased while the value of (VE+VA) is maintained substantially constant.
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