Patent Number: 
Section: claims

1. An ion beam generator comprising:a discharge tank for generating plasma that includes ions;a lead-out electrode, having an annular grid portion provided with openings for leading out the ions generated in the discharge tank, while accelerating the generated ions as an annular ion beam, which is led out of the lead-out electrode; anda deflecting electrode for deflecting the annular ion beam, led out of the lead-out electrode, in an annular center direction, the deflecting electrode comprising a first electrode tube and a second electrode tube, the first electrode tube and the second electrode tube being in a circular truncated cone shape having respective openings in an upper surface portion and a bottom surface portion thereof, a diameter of an opening of the second electrode tube being smaller than a diameter of an opening of the first electrode tube,wherein the ion beam led out from the lead-out electrode enters the deflecting electrode between the first electrode tube and the second electrode tube, and is deflected. 2. The ion beam generator according to claim 1, wherein the annular grid portion of the lead-out electrode is a grid portion having one of a substantially circular ring shape and a substantially regular polygonal shape. 3. The ion beam generator according to claim 1, further comprising a drive mechanism for moving the deflecting electrode in a direction to face the lead-out electrode. 4. The ion beam generator according to claim 3, wherein the drive mechanism moves the deflecting electrode reciprocally. 5. The ion beam generator according to claim 1, wherein the openings of the annular grid portion are linear holes. 6. An ion beam etching apparatus comprising:a neutralizer for irradiating electrons;a substrate holder for holding a substrate; andan ion beam generator disposed to face the substrate held by the substrate holder,wherein the ion beam generator is one according to any one of claims 1 to 5. 7. The ion beam etching apparatus according to claim 6, wherein, in the ion beam generator, the grid is arranged parallel to the substrate held by the substrate holder, and the deflecting electrode deflects the ion beam led out by the grid portion, so that the ion beam is caused to enter the substrate held by the substrate holder at an angle that is inclined relative to the substrate.