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 ionisation chamber to retain heat within the chamber when the ion source is functioning.
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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.
101 Citations
58 Claims
- 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 ionisation chamber to retain heat within the chamber when the ion source is functioning.
- 19. 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, and 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.
- 33. A cathode unit providing a cathode for use in an ion source of an ion implanter, wherein the ion source comprises an ionisation chamber incorporating said cathode unit and an outlet through which ions can exit from the chamber, the cathode unit comprising a cathode tube arranged to extend through one of said opposed wall portions, a cathode button mounted at the end of the cathode tube within the chamber and a heater element positioned in the cathode tube for connection with a power supply negatively biasing the element relative to the cathode button to emit electrons thereby to heat the cathode button to cause the cathode button to emit electrons into the ionisation chamber, the tube having a length and having at least one slit with a component transverse to the length such as to restrict heat conduction along the cathode tube.
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49. A front plate for an ionisation chamber for use in supply of ions to an ion implantation apparatus for implantation into a substrate the electrode having an outlet so that ions from the chamber may pass therethrough, and being impregnated with a material which is selected from an element, and a compound thereof, the ions of which element are the same specie as those to be implanted into the substrate from the source thereof.
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50. A front plate for an ion source arc chamber, the front plate having an aperture through which ions can be extracted from the ion chamber containing atoms of a predetermined species, and the plate having an exposed surface containing other atoms of said predetermined species.
- 51. A front plate for an ionisation chamber for use in extracting boron ions from a boron ion source within the ionisation chamber for supply to an ion implantation apparatus, the front plate having an outlet and being formed of a material comprising graphite impregnated with a material selected from the group consisting of boron and boron nitride.
- 54. A front plate for an ionisation chamber for supply of boron ions from a boron ion source in the ionisation chamber to an ion implantation apparatus, the plate having an outlet so that ions from the chamber may pass therethrough, and being formed of a material comprising graphite coated with a material selected from the group consisting of boron and boron nitride.
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58. An extraction electrode for use in extracting ions of a selected specie from a source thereof in an ionisation chamber for supply to a substrate placed in an ion implantation apparatus, the extraction electrode being mountable in front of an outlet of the ionisation chamber through which said ions are directed from the ionisation chamber, the electrode having an aperture for alignment with said outlet and being formed of a material bearing itself bearing a material selected from an element, and a compound thereof, the ions of which element are the same specie as those to be implanted into the substrate from the source thereof.
Specification