An ion implanter and an ion implant method are disclosed. Essentially, the wafer is moved along one direction and an aperture mechanism having an aperture is moved along another direction, so that the projected area of an ion beam filtered by the aperture is two-dimensionally scanned over the wafer. Thus, the required hardware and/or operation to move the wafer may be simplified. Further, when a ribbon ion beam is provided, the shape/size of the aperture may be similar to the size/shape of a traditional spot beam, so that a traditional two-dimensional scan may be achieved. Optionally, the ion beam path may be fixed without scanning the ion beam when the ion beam is to be implanted into the wafer, also the area of the aperture may be adjustable during a period of moving the aperture across the ion beam.