Patent Number: 
Section: claims

1. An ion implantation apparatus, in which an ion beam formed in a ribbon-shape having a larger dimension in an X direction than a dimension in a Y direction substantially orthogonal to the X direction is irradiated onto a target, the ion implantation apparatus comprising:first and second magnets provided on an upstream side of the target, facing each other in the Y direction across a center of a cross-section of a path for the ribbon-shaped ion beam, and crossing a traveling direction of the ribbon-shaped ion beam,wherein the first magnet has a first magnetic pole having a first polarity on an inlet side of the ion beam and a second magnetic pole having a second polarity opposite to the first polarity on an outlet side of the ion beam, the second magnet has a third magnetic pole having the second polarity on the inlet side of the ion beam and a fourth magnetic pole having the first polarity on the outlet side of the ion beam, andthe first and second magnets generate magnetic fields in a direction so that an inward Lorentz force is applied to the ion beam between both the magnets, and the ion beam is narrowed in the Y direction. 2. The ion implantation apparatus according to claim 1, wherein the ribbon-shaped ion beam is formed by scanning the ion beam in the X direction or by not scanning in the X direction. 3. The ion implantation apparatus according to claim 1, wherein the first and second magnets are arranged substantially plane symmetrically with respect to a symmetric plane passing through a center in the Y direction of the path for the ion beam and substantially orthogonal to the X direction and the Y direction, except that the first magnet and the second magnet are opposite in polarity from each other. 4. The ion implantation apparatus according to claim 1, wherein the first and second magnets are arranged so as to obliquely cross the traveling direction of the ion beam. 5. The ion implantation apparatus according to claim 2, wherein the first and second magnets are provided on a path for the ion beam where the ion beam is scanned in a fan shape in the X direction,the first and second magnets respectively have arc shapes protruding in the traveling direction the ion beam, such that an angle formed between the advancing direction of the ion beam at each scanning position in the X direction and a straight line connecting between the pair of the magnetic poles of each magnet at the shortest distance is invariably substantially constant. 6. The ion implantation apparatus according to claim 1, further comprising:an ion beam deflector configured to deflect the ion beam which is in an energy state so as to be irradiated onto the target by a magnetic field or an electric field, and separate the ion beam and neutral particles,wherein the first and second magnets are disposed in at least a vicinity on a downstream side of the ion beam deflector. 7. The ion implantation apparatus according to claim 1, further comprising:an ion beam deflector configured to deflect the ion beam which is in an energy state so as to be irradiated onto the target by a magnetic field or an electric field, and separate the ion beam and neutral particles,wherein the first and second magnets are disposed in at least a vicinity on an upstream side of the ion beam deflector. 8. The ion implantation apparatus according to claim 1, wherein the first and second magnets are permanent magnets. 9. The ion implantation apparatus according to claim 1, wherein the first and second magnets are electromagnets. 10. The ion implantation apparatus according to claim 1, wherein the first magnet includes a first long side at the inlet side of the ion beam and a second long side at the outlet side of the ion beam, the first long side has the first magnetic pole over an overall length thereof, and the second long side has the second magnetic pole over an overall length thereof, and wherein the second magnet includes a third long side at the inlet side and a fourth long side at the outlet side, the third long side has the second magnetic pole over an overall length thereof, and the fourth long side has the first magnetic pole over an overall length thereof.