Patent ID: 7462847
Filing Date: 2008-12-09
Classification: H01J

Abstract:
1. An ion implanter comprising: an ion source; an extraction accelerating section for extracting an ion beam from the ion source; a mass analyzing section for acquiring desired ions from the ion beam extracted by the extraction accelerating section; a wafer holding section for holding a wafer in which ions are implanted; an aperture for removing redundant ions and particles from an ion beam outputted from the mass analyzing section so that such ions and particles do not reach the wafer held by the wafer holding section; a dose controller for measuring an ion beam current during the implantation of ions in the wafer and controlling an amount of ions to be implanted in the wafer; a mechanical scan mechanism for allowing the wafer holding section to reciprocate; a mechanical scan mechanism controller for measuring a mechanical scan position of the wafer holding section reciprocated by the mechanical scan mechanism and a mechanical scan speed of the mechanical scan mechanism, and controlling the mechanical scan mechanism; an accumulated dose distribution computing section for obtaining a dose distribution in a mechanical scan direction of the wafer held by the wafer holding section from the ion beam current measured by the dose controller and the mechanical scan speed and the mechanical scan position each measured by the mechanical scan mechanism controller, and accumulating the dose distribution thus obtained to obtain an accumulated dose distribution of the wafer in the mechanical scan direction, for each mechanical scan of the wafer holding section by the mechanical scan mechanism; an accumulated dose distribution uniformity computing section for computing accumulated dose distribution uniformity from the accumulated dose distribution obtained by the accumulated dose distribution computing section, for each mechanical scan; and a mechanical scan speed computing and correcting section for calculating a mean value of the accumulated dose distribution obtained by the accumulated dose distribution computing section, for obtaining a distribution correction amount of an accumulated dose obtained by deducting the accumulated dose distribution from the mean value, for obtaining a correction value for correcting the mechanical scan speed so as to render an accumulated dose invariant, the accumulated dose having the accumulated dose distribution correction amount taken into consideration in a subseciuent mechanical scan, and for outputting the correction value to the mechanical scan mechanism controller, for each mechanical scan, wherein the mechanical scan mechanism controller corrects the mechanical scan speed in accordance with the mechanical scan speed correction value.