Conductive contamination resistant insulator
View Patent ↗An apparatus that forms a source bushing, while comprehending the possible formation of electrically conductive films thereon, is disclosed. Such an apparatus may advantageously be used to isolate an ion source from other components within the ion implanter, as these components may be at different electrical potentials. In one embodiment, the source bushing is constructed from a material having a lower electrical resistance than is currently used. By constructing the bushing in this manner, the effects of the applied lower resistance films is reduced, as the change in effective resistance is reduced. In other embodiments, the source bushing is purposely lined with an electrically semiconducting material, so that the effects of the later applied lining are minimized. In either case, the electrical potential between the two devices that are being isolated by the bushing is more evenly applied across the bushing.
1. An ion implanting apparatus, comprising:
an ion source, operating at a first electrical potential;
a second component, operating at a second electrical potential; and
an insulator, coupling said ion source and said second component, having a bulk resistance of less than 4 GΩ.
2. The ion implanting apparatus of claim 1 , wherein said resistance value is modified by applying additives to said bulk material.
3. The ion implanting apparatus of claim 1 , wherein said additive is selected from the group consisting of silver, graphite powder, doped alumina, semiconductor materials, semi-insulator materials and organo-metallic material.
4. The ion implanting apparatus of claim 1 , wherein said resistance value is modified by applying a conductive layer to said insulator.
5. The ion implanting apparatus of claim 4 , wherein said conductive layer is applied using CVD.
6. The ion implanting apparatus of claim 1 , wherein said conductive layer is molded onto said bulk material.
7. The ion implanting apparatus of claim 1 , wherein said second component is a mounting flange or vacuum chamber, operating at ground potential.
8. A method of eliminating arcing within an ion implanting apparatus, said apparatus having an ion source, operating at a first electrical potential, a second component, operating at a second electrical potential, and an insulator, comprising a bulk material, having a vacuum side and an atmospheric side, said insulator coupling said ion source and said second component, wherein a portion of said vacuum side of said insulator becomes coated by a film, and a second portion of said vacuum side is uncoated, said method comprising:
determining a location on said bushing where arcing occurs;
determining a resistance of said film from said ion source to said arcing location;
determining a maximum voltage at which arcing does not occur; and
calculating a maximum resistance of said insulator, based on said determined values; and
modifying said bulk material of said insulator so as to achieve a resistance less than said maximum calculated resistance.
9. The method of claim 8 , further comprising adding an additive to said bulk material.
10. The method of claim 9 , wherein said additive is selected from the group consisting of silver, graphite powder, doped alumina, semiconductor materials, semi-insulator materials and organo-metallic material.
11. The method of claim 8 , further comprising applying a conductive layer to said insulator.
12. The method of claim 11 , wherein said conductive layer is applied using CVD.
13. The method of claim 8 , wherein said conductive layer is molded onto said bulk material.