Patent ID: 7371991

Claim:
An ion beam irradiation device comprising a plasma generation chamber which generates a plasma inside, and a processing chamber connected to the plasma generation chamber, with a plurality of grids with a large number of small holes being arranged between the plasma generation chamber and the processing chamber in order to draw out ions in the plasma, the ion beam irradiation device further comprising an insulating spacer fixed to each of the plurality of grids to determine a positional relationship of the grids and to prevent the grids from electrically coming into contact with each other, wherein the insulating spacer has a grid support portion supporting one of the grids, and an annular groove in an insulating portion consisting of a grid fixing portion with an annular, substantially plane portion opposed to another of the grids with a predetermined space therebetween and formed in a region different from the grid support portion and a small diameter portion which is a cylindrical portion being raised from a central portion of the annular, substantially plane portion and having an end surface abutting another of the grids, with the annular groove being perpendicular to the plane and separating a peripheral portion of the annular portion and the cylindrical portion from each other.