Ion sources for ion implantation apparatus
First Claim
1. An ion source comprising an ionisation chamber within which a plasma can be generated, the chamber having an outlet through which ions can exit from the ionisation chamber, electrodes in the ionisation chamber for establishing and maintaining a plasma within the chamber when a power supply is provided thereto, and a heat shield enclosing at least a part of the ionization chamber to retain heat within the chamber when the ion source is functioning, wherein the heat shield comprises a plurality of heat shield members which extend around the ionization chamber in spaced relationship thereto and a plurality of coupling members for connecting the heat shield members to form the heat shield around the ionization chamber, and wherein the ionization chamber is of cuboid shape and has side and end walls and the heat shield members are arranged in spaced relationship to said side and end walls, andwherein the coupling members are mounted adjacent intersections of side and end walls of the ionization chamber and each coupling member comprises a pillar portion extending parallel to and spaced from its adjacent intersection and wing portions extending in the general direction of the adjacent wall, the wing portions providing said slots to accommodate therebetween the spaced parallel plates of the associated heat shield member.
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Accused Products
Abstract
The invention relates to improving the efficiency of ion flow from an ion source, by reducing heat loss from the source both in the ion chamber of the ion source and its constituent parts (e.g. the electron source). This is achieved by lining the interior of the ion chamber and/or the exterior with heat reflective and/or heat insulating material and by formation of an indirectly heated cathode tube such that heat transfer along the tube and away from the ion chamber is restricted by the formation of slits in the tube. Efficiency of the ion source is further enhanced by impregnating and/or coating the front plate of the ion chamber with a material which comprises an element or compound thereof, the ions of which element are the same specie as those to be implanted into the substrate from the source thereof.
33 Citations
43 Claims
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1. An ion source comprising an ionisation chamber within which a plasma can be generated, the chamber having an outlet through which ions can exit from the ionisation chamber, electrodes in the ionisation chamber for establishing and maintaining a plasma within the chamber when a power supply is provided thereto, and a heat shield enclosing at least a part of the ionization chamber to retain heat within the chamber when the ion source is functioning, wherein the heat shield comprises a plurality of heat shield members which extend around the ionization chamber in spaced relationship thereto and a plurality of coupling members for connecting the heat shield members to form the heat shield around the ionization chamber, and wherein the ionization chamber is of cuboid shape and has side and end walls and the heat shield members are arranged in spaced relationship to said side and end walls, and
wherein the coupling members are mounted adjacent intersections of side and end walls of the ionization chamber and each coupling member comprises a pillar portion extending parallel to and spaced from its adjacent intersection and wing portions extending in the general direction of the adjacent wall, the wing portions providing said slots to accommodate therebetween the spaced parallel plates of the associated heat shield member.
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14. An ion source comprising an ionization chamber within which a plasma can be generated, the chamber having an outlet through which ions can exit from the ionization chamber, electrodes in the ionization chamber for establishing and maintaining a plasma within the chamber when a power supply is provided thereto, and a heat shield enclosing at least a part of the ionization chamber to retain heat within the chamber when the ion source is functioning wherein the heat shield comprises a plurality of heat shield members which extend around the ionization chamber in spaced relationship thereto and a plurality of coupling members for connecting the heat shield members to form the heat shield around the ionization chamber, and
wherein the ionization chamber is of cuboid shape and has side and end walls and the heat shield members are arranged in spaced relation ship to said side and end walls, wherein two electrodes are provided in the ionisation chamber, a first electrode extending through one end wall of the ionisation chamber and the second electrode extending through the other end wall thereof, and each heat shield member provided adjacent an end wall being formed in at least two parts so as to extend from its coupling member adjacent the intersection of that end wall with its associated side wall to a location adjacent but spaced from the adjacent electrode.
- 15. An ion source comprising an ionisation chamber within which a plasma can be generated, an outlet through which ions can exit the chamber, electrodes in the ionisation chamber for establishing and maintaining a plasma within the chamber when a power supply is provided to the electrodes, a screen provided at an interior wall of the ionisation chamber, electrically insulated therefrom, the screen being heated during operation of the ion source to assist at least one of ejection of ions therefrom through said outlet and the break down of molecular species within the arc chamber, and a power supply connected to bias the screen positively relative to the chamber.
- 29. An ion source for an ion implanter, comprising an ionisation chamber having opposed wall portions, an outlet through which ions can exit from the chamber, and an indirectly heated cathode, said indirectly heated cathode comprising a cathode tube extending through one of said opposed wail portions, a cathode button mounted at an end of the cathode tube within the ionization chamber, and a heater element positioned in spatial relation in the cathode tube for connection with a power supply negatively biasing the element relative to the cathode button so that in use electrons emitted by the heated element are accelerated to the button to heat the cathode button by electron impact, thereby to cause the cathode button in use to emit electrons into the ionisation chamber, wherein said cathode tube is cylindrical having an axis and a uniform external diameter of between 10 and 20 mm, and has at least one slit with a component transverse to the axis such as to restrict heat conduction along the cathode tube.
Specification