Patent Number: 
Section: claims

1. A method of reducing doping process impurities in an ion implantation apparatus having a chamber through which an ion beam path extends, the method comprising:providing a removable shielding assembly for the chamber comprising at least first and second removable shielding members, the at least first and second removable shielding members being made of graphite or impregnated graphite;installing the shielding assembly in the chamber such that the first shielding member covers a first magnetic area inside the chamber and the second shielding member covers a second magnetic area inside the chamber;using the ion implantation apparatus for implanting ions into semiconductor wafers;removing the shielding assembly from the chamber after the ion implantation apparatus has been used for implanting ions into semiconductor wafers for a period of time;cleaning the shielding assembly while the shielding assembly is removed from the chamber; andre-installing the shielding assembly in the chamber for further use of the ion implantation apparatus. 2. The method of claim 1, wherein the shielding assembly includes a third shielding member adapted to cover a side surface inside the chamber extending between the first and second magnetic areas. 3. The method of claim 1, wherein the shielding assembly includes a third shielding member adapted to extend from a side edge of the second shielding member in a side-by-side relationship so as to cover a portion of a top surface inside the chamber adjacent the second magnetic area. 4. The method of claim 3, wherein the act of installing the shielding assembly comprises mounting a support mechanism in the chamber for supporting the third shielding member in a position juxtaposed to the top surface, and installing the third shielding member in the chamber, with a side edge of the third shielding member overlapping and supported on an adjacent edge of the second shielding member and a bottom surface of the third shielding member resting on the support mechanism. 5. The method of claim 4, wherein the act of installing the third shielding member further includes adjusting an adjustment mechanism of the support mechanism so that the third shielding member is supported substantially parallel to the top surface. 6. The method of claim 1, wherein the act of cleaning the shielding assembly further includes treating the shielding assembly such that the shielding assembly is substantially free of a cleaning agent used to clean the shielding assembly. 7. The method of claim 1, wherein the act of treating the shielding assembly comprises heating the shielding assembly to remove the cleaning agent. 8. A method of maintaining an ion implantation apparatus having a chamber through which an ion beam path extends, the method comprising:providing a removable shielding assembly for the chamber comprising a first shielding member for covering a first magnetic area in the chamber, a second shielding member for covering a second magnetic area in the chamber, a third shielding member for covering a side surface area in the chamber extending between top and bottom surfaces of the chamber, and a fourth shielding member for covering a top surface area in a side-by-side relationship with the second shielding member, wherein the first, second, third, and fourth shielding members are made of graphite or impregnated graphite; andinstalling the shielding assembly in the chamber such that the first shielding member covers the first magnetic area, the second shielding member covers the second magnetic area, the third shielding member covers the side surface area, and the fourth shielding member covers the top surface area. 9. The method of claim 8, further comprising:using the ion implantation apparatus for implanting ions into semiconductor wafers;removing the shielding assembly from the chamber after the ion implantation apparatus has been used for a period of time;cleaning the shielding assembly while the shielding assembly is removed from the chamber; andre-installing the shielding assembly in the chamber for further use of the ion implantation apparatus. 10. The method of claim 8, wherein the first, second, third, and fourth shielding members are made entirely of graphite or impregnated graphite. 11. The method of claim 8, further comprising installing an adjustable support mechanism in the chamber, the support mechanism being configured to support the fourth shielding member and vary the tilt of the fourth shielding member relative to the top surface area. 12. The method of claim 11, further comprising adjusting the support mechanism so that the fourth shielding member is supported substantially parallel to the top surface area. 13. An ion implanting apparatus comprising:a chamber through which an ion beam path extends, the chamber having a bottom surface and a top surface, the bottom surface having a bottom magnetic area and a top surface having a top magnetic area;a first shielding member comprising a unitary body having a raised central portion for completely covering the bottom magnetic area and an outer portion substantially surrounding the central portion; anda second shielding member comprising a unitary body having a raised central portion for completely covering the top magnetic area and an outer portion substantially surrounding the central portion;wherein the first and second shielding members are configured to be easily removable from the chamber to facilitate cleaning of the shielding members, the first and second shielding members being made entirely of graphite or impregnated graphite. 14. The apparatus of claim 13, wherein the first and second shielding members are substantially identical in size and shape. 15. The apparatus of claim 13, further comprising a third shielding member configured to cover a side surface inside the chamber extending between the top and bottom surfaces, the third shielding member being configured to be removable from the chamber and being made entirely of graphite or impregnated graphite. 16. The apparatus of claim 13, further comprising a third shielding member configured to cover a portion of the top surface in a side-by-side relationship with the second shielding member, the third shielding member being configured to be removable from the chamber and being made only of graphite or impregnated graphite. 17. The apparatus of claim 16, further comprising a support mechanism adapted for mounting in the chamber in a position such that the support mechanism supports the third shielding member in opposing relationship to the top surface of the chamber. 18. The apparatus of claim 17, wherein the support mechanism is configured to vary the tilt of the third shielding member relative to the top surface. 19. The apparatus of claim 18, wherein the support mechanism comprises a body and at least one adjusting bolt threadably received in the body, the bolt having an upper end positioned to support the third shielding member, the bolt being adjustable to vary the tilt of the third shielding member relative to the top surface. 20. The apparatus of claim 13, further comprising an arcuate-shaped shielding member configured to cover a top portion of a barrier extending upwardly from the bottom surface of the chamber. 21. An ion implanting apparatus comprising:a chamber through which an ion beam path extends having a bottom surface and a top surface;a bottom magnet disposed on the bottom surface, the bottom magnet having a magnet core;a top magnet disposed on the top surface, the top magnet having a magnet core;a first shielding member comprising a unitary body having a raised central portion for covering the magnet core of the bottom magnet and an outer portion substantially surrounding the central portion for covering a surface of the bottom magnet surrounding its respective magnet core; anda second shielding member comprising a unitary body having a raised central portion for covering the magnet core of the top magnet and an outer portion substantially surrounding the central portion for covering a surface portion of the top magnet surrounding its respective magnet core;a third shielding member configured to cover a side surface area inside the chamber extending between the top and bottom surfaces;a fourth shielding member configured to cover a portion of the top surface in a side-by-side relationship with the second shielding member;a support mechanism adapted to be mounted in the chamber for supporting the fourth shielding member in the chamber such that the fourth shielding member is juxtaposed the top surface of the chamber, the support mechanism being configured to vary the tilt of the fourth shielding member relative to the top surface;an arcuate-shaped, upright barrier coupled to the bottom surface of the chamber; anda fifth shielding member configured to cover a top portion of the barrier;wherein the first, second, third, fourth and fifth shielding members are configured to be removable from the chamber for cleaning the shielding members outside of the chamber, the first, second, third, fourth and fifth shielding members being made of isotropic graphite. 22. The apparatus of claim 15, wherein the third shielding member comprises first and second edges, the first edge of the third shielding member contacting an adjacent edge of the first shielding member and the second edge of the third shielding member contacting an adjacent edge of the second shielding member. 23. The apparatus of claim 16, wherein the third shielding member has a lip portion that engages an adjacent lip portion of the second shielding member such that the third shielding member is at least partially supported by the second shielding member. 24. The apparatus of claim 23, wherein the lip portions of the second shielding member and the third shielding member define areas of reduced thickness of the second and third shielding members, the areas of reduced thickness being dimensioned such that the third shielding member is co-planar with the second shielding member when the shielding members are installed in the chamber. 25. The apparatus of claim 19, wherein the body of the support mechanism is formed with a slot that is dimensioned to fit over a top edge of an existing plate in the chamber so as to support the support mechanism. 26. The apparatus of claim 15 wherein the third shielding member is formed with an aperture that is sized and positioned to correspond with an ion-beam outlet in the side surface of the chamber. 27. The method of claim 1, wherein the shielding members are made of isotropic graphite. 28. The method of claim 8, wherein the shielding members are made of isotropic graphite. 29. The apparatus of claim 13, wherein the shielding members are made of isotropic graphite.