Patent ID: 8017922

Claim:
An ion implantation method comprising; performing an implantation process of implanting ions over an entire substrate, by scanning reciprocatingly an ion beam in an X direction by an electric field or magnetic field and mechanically driving reciprocatingly the substrate in a Y direction substantially orthogonal to the X direction; forming a dose distribution that is non-uniform between a center region of the substrate and a peripheral region of the substrate and substantially symmetrical with respect to the center of the substrate within the plane of the substrate to correct a characteristic variation of a semiconductor device caused by at least one process prior to performing the ion implantation process by changing either a scanning speed of the ion beam along the X direction or a driving speed of the substrate along the Y direction while the ion beam is irradiated onto the substrate so that the speed change becomes substantially symmetrical with respect to center of the substrate; rotating the substrate around a central part thereof; and performing the implantation process at least four times, the substrate being rotated by a predetermined rotation angle around the central part thereof in an interval between each implantation process; wherein the resultant substrate has a non-uniform does distribution of a desired pattern within the plane of the substrate.