Programmed fine ion implantation beam system

Claim 1

An ion beam device for producing an ion beam suitable for ion implantation of a target, said ion beam device comprising: means for producing an ion beam, said means for producing an ion beam comprising an ion source, an extraction electrode for extracting ions from said ion source, and a focusing electrode for focusing the extracted ions into a beam; mass separation means positioned along the ion beam for separating out of the ion beam ions of other than the selected species by deflecting the unselected species away from the beam path; an aperture plate and decelerating field reference electrode means positioned downstream along the beam path from said mass separation means for decelerating the ion beam to reduce the energy of the beam to minimize sputtering from beam impingement on said aperture plate, said decelerating field reference electrode being positioned between said aperture plate and said mass separation means and being at a potential substantially less positive than the potential of said ion source, said aperture plate being substantially at the potential of said ion source, said aperture plate having a limiting aperture therein positioned along the path of the beam, said limiting aperture being of smaller size than the beam so that only a portion of the beam is able to pass therethrough and the balance of the beam impinging the aperture plate is of sufficiently low energy that it reduces sputtering of the aperture plate; and focusing lens electrode positioned downstream of said limiting aperture so that the ions passing through said limiting aperture are focused for a minimum spot size on the target and are accelerated towards the target; deflecting electrodes positioned adjacent the ion beam downstream of said accelerating and focusing lens electrode to deflect the ion beam onto a target.