Patent ID: 9601314
Date: 2017-03-21
CPC Classifications: C23C,H01J,H01L

Claim:
1. An ion implantation method in which an ion beam is scanned in a beam scanning direction and a wafer is mechanically scanned in a direction perpendicular to the beam scanning direction so as to implant ions into the wafer, the method comprising: setting a wafer rotation angle with respect to the ion beam in a stepwise manner to implant ions into the wafer at each of a set wafer rotation angles; and implanting the ions into the wafer forming a central region in the wafer overlapping a portion of a range where the wafer is mechanically scanned to obtain a two-dimensional ion implantation amount in-surface distribution pattern where a ratio of a maximum to a minimum ion implantation amount is five times or more, the central region representing the maximum or the minimum ion implantation amount corresponding to a defined relationship among a diameter of the wafer, a wafer scanning region length, and a radius of the wafer, wherein, when the central region represents the minimum ion implantation amount and a plurality of ion implantation regions that overlap as the wafer is rotated, the implanting comprises: wherein, when the central region represents the maximum ion implantation amount and a plurality of ion implantation regions that overlap as the wafer is rotated, the implanting comprises: during a first step of the implanting, setting the wafer scanning region length to be longer than the radius of the wafer, during a second step of the implanting, simultaneously varying the wafer scanning region length for regulating the range where the wafer is mechanically scanned, and changing a beam scanning speed of the ion beam to be lower in the central region than other positions of the wafer at each of the set of wafer rotation angles, and during a third step of the implanting, continuously repeating the second step for a full rotation of the wafer.