Patent Number: 
Section: abstract

A wafer having a plurality of elements closely arranged thereon is irradiated with an ion beam while being conveyed in one direction by a conveying unit. Each of shutters adjusts an irradiation time during which a target area of the wafer is irradiated with the ion beam. Thus, a frequency in the target area is adjusted. Each of a plurality of mask holes in a pattern mask disposed between the wafer and the shutters corresponds to one area of the wafer. The mask holes are alternately displaced in a wafer conveying direction in which the wafer is conveyed, and are arranged in a plurality of columns perpendicular to the wafer conveying direction. To individually open and close the mask holes, the shutters are arranged to correspond to the respective mask holes. Thus, frequency adjustment, for areas in one column perpendicular to the wafer conveying direction, is performed in multiple steps.