Patent Number: 
Section: claims

1. An ion implantation apparatus including a beam line of implanting an ion to a wafer by irradiating an ion beam extracted from an ion source and passed through a mass analysis magnet apparatus and a mass analysis slit to the wafer by being reciprocally scanned by a beam scanner;wherein the ion implantation apparatus is constituted such that the ion beam is converged and shaped by providing a first quadrupole focusing electromagnet at a section of the beam line from an outlet of the mass analysis magnet apparatus before incidence of the mass analysis slit, and by providing a second quadrupole focusing electromagnet having an effective magnetic field effect which is larger than an effective magnetic field effect of the first quadrupole focusing electromagnet at a section of the beam line from an outlet of the mass analysis slit before incidence of the beam scanner. 2. The ion implantation apparatus according to claim 1, wherein an effective magnetic field section in the beam line of the second quadrupole focusing electromagnet is longer than an effective magnetic field section of the first quadrupole focusing electromagnet. 3. The ion implantation apparatus according to claim 1, wherein the effective magnetic field effect is defined by a magnetic flux density. 4. The ion implantation apparatus according to claim 1, wherein the effective magnetic field effect is defined by a length of an effective magnetic field section having a uniform magnetic field. 5. The ion implantation apparatus according to claim 1, wherein the effective magnetic field effect is increased by making a diameter of a magnetic core of the second quadrupole focusing electromagnet larger than a diameter of a magnetic core of the first quadrupole focusing electromagnet. 6. The ion implantation apparatus according to claim 2, wherein the effective magnetic field effect is increased by making a magnetic core of the second quadrupole focusing electromagnet longer than a magnetic core of the first quadrupole focusing electromagnet in a direction of the beam line. 7. The ion implantation apparatus according to claim 3, wherein the effective magnetic field effect is increased by making a turn number of a winding of the second quadrupole focusing electromagnet larger than a turn number of a winding of the first quadrupole focusing electromagnet. 8. The ion implantation apparatus according to claim 3, wherein the effective magnetic field effect is increased by making an exciting voltage or current of the second quadrupole focusing electromagnet larger than an exciting voltage or current of the first quadrupole focusing electromagnet. 9. The ion implantation apparatus according to claim 1, wherein a magnitude of the effective magnetic field effect of the second quadrupole focusing electromagnet is made to be twice as much or more of a magnitude of the effective magnetic field effect of the first quadrupole focusing electromagnet. 10. The ion implantation apparatus according to claim 9, wherein the second quadrupole focusing electromagnet is constituted by aligning to arrange two of constitutions the same as the first quadrupole focusing electromagnet in the direction of the beam line. 11. The ion implantation apparatus according to claim 1, wherein the second quadrupole focusing electromagnet is constituted by an electromagnet for converging in a longitudinal direction and a range of converging the ion beam in the longitudinal direction is widened. 12. The ion implantation apparatus according to claim 1, wherein the first quadrupole focusing electromagnet and the second quadrupole focusing electromagnet are respectively electromagnets for converging in a longitudinal direction. 13. The ion implantation apparatus according to claim 1, wherein the first quadrupole focusing electromagnet and the second quadrupole focusing electromagnet are respectively an electromagnet for converging in a longitudinal direction and an electromagnet for converging in a lateral direction. 14. The ion implantation apparatus according to claim 1, wherein the first quadrupole focusing electromagnet and the second quadrupole focusing electromagnet are respectively an electromagnet for converging in a lateral direction and an electromagnet for converging in a longitudinal direction. 15. The ion implantation apparatus according to claim 1, wherein the first quadrupole focusing electromagnet and the second quadrupole focusing electromagnet are respectively electromagnets for converging in a lateral direction. 16. The ion implantation apparatus according to claim 1, wherein the second quadrupole focusing electromagnet is arranged at a position of a middle state of converging and diverging the ion beam, on the section of the beam line from the outlet of the mass analysis slit to the inlet of the beam scanner. 17. The ion implantation apparatus according to claim 1, wherein the second quadrupole focusing electromagnet is an electromagnet for converging in a longitudinal direction;wherein the beam scanner includes a pair of scanning electrodes arranged by interposing the ion beam, scanner suppression electrodes respectively provided at a vicinity on an upstream side and at a vicinity on a downstream side of the pair of scanning electrodes, and a pair of electric field correcting electrodes connected to the scanner suppression electrodes and provided at a space interposed by electrode faces of the pair of scanning electrodes opposed to each other; andwherein the beam scanner is made to be operated as a lateral direction converging means for alleviating conversion in a longitudinal direction of the second quadrupole focusing electromagnet by a zero electric field effect when a beam scanning angle by the pair of scanning electrodes is zero. 18. The ion implantation apparatus according to claim 1, wherein a steering coil for adjusting a beam position of the ion beam in the lateral direction is arranged at a position on an upstream side adjacent to an inlet of the second quadrupole focusing electromagnet. 19. A method of converging and shaping an ion beam in an ion implantation apparatus, the method being applied to an ion implantation apparatus for implanting an ion to a wafer by irradiating an ion beam extracted from an ion source and passed through a mass analysis magnet apparatus and a mass analysis slit to the wafer by reciprocally scanning the ion beam with a beam scanner;wherein the ion beam is converged in a longitudinal direction by a first quadrupole focusing electromagnet arranged at a section of a beam line from an outlet of the mass analysis magnet apparatus before incidence of the mass analysis slit; andwherein the ion beam is made to be able to be shaped to a sectional shape suitable for the beam scanner by further converging the ion beam in a longitudinal direction by a second quadrupole focusing electromagnet arranged at a section of the beam line from an outlet of the mass analysis slit before incidence of the beam scanner and having an effective magnetic field effect larger than an effective magnetic field effect of the first quadrupole focusing electromagnet.