Insertable target holder for solid dopant materials
An ion source with an insertable target holder for holding a solid dopant material is disclosed. The insertable target holder includes a pocket or cavity into which the solid dopant material is disposed. When the solid dopant material melts, it remains contained within the pocket, thus not damaging or degrading the arc chamber. Additionally, the target holder can be moved from one or more positions where the pocket is at least partially in the arc chamber to one or more positions where the pocket is entirely outside the arc chamber. In certain embodiments, a sleeve may be used to cover at least a portion of the open top of the pocket.
1. An indirectly heated cathode ion source, comprising:
an arc chamber, comprising a plurality of walls connecting a first end and a second end;
an indirectly heated cathode disposed on the first end of the arc chamber; and
a target holder, having an enclosed pocket to hold a dopant material such that the dopant material is not exposed to a plasma generated in the arc chamber, wherein the target holder is oriented in the arc chamber so that gravity retains the dopant material in the target holder, the target holder entering the arc chamber through one of the plurality of walls, having a first position where the enclosed pocket is outside the arc chamber and a second position where at least a portion of the enclosed pocket is disposed in the arc chamber such that the plasma heats the dopant material in the enclosed pocket.
2. The indirectly heated cathode ion source of claim 1 , further comprising an actuator in communication with the target holder to move the target holder from the first position to the second position.
3. The indirectly heated cathode ion source of claim 1 , where the target holder further comprises a conduit from the enclosed pocket to an exterior of the target holder, such that in the second position, the conduit leads from the enclosed pocket to an interior of the arc chamber.
4. The indirectly heated cathode ion source of claim 1 , where the target holder is made of a porous material, such that vaporized or sublimated dopant material passes through the porous material and into the arc chamber.
5. The indirectly heated cathode ion source of claim 1 , wherein the target holder comprises a removable seal to allow access to the enclosed pocket.
6. The indirectly heated cathode ion source of claim 1 , wherein the target holder comprises a heating element.
7. The indirectly heated cathode ion source of claim 1 , wherein the target holder is electrically biased with respect to the arc chamber.
8. An indirectly heated cathode ion source, comprising:
an arc chamber, comprising a plurality of walls connecting a first end and a second end;
an indirectly heated cathode disposed on the first end of the arc chamber; and
a target holder, having a top surface and a pocket to hold a dopant material, the target holder disposed at the second end, having a first position where at least a portion of the pocket is disposed in the arc chamber and a second position where the pocket is disposed outside the arc chamber, and wherein in the second position, the top surface of the target holder serves as the second end of the arc chamber.
9. The indirectly heated cathode ion source of claim 8 , further comprising an actuator in communication with the target holder to move the target holder from the first position to the second position.
10. The indirectly heated cathode ion source of claim 8 , wherein the pocket comprises a bottom surface, a plurality of sidewalls and an open top.
11. The indirectly heated cathode ion source of claim 1 , further comprising a third position, where the enclosed pocket is disposed outside the arc chamber and the target holder is in thermal communication with the arc chamber such that the dopant material vaporizes while the target holder is in the third position.
12. A method of ionizing different dopants, using the indirectly heated cathode ion source of claim 2 , comprising:
disposing a dopant in solid form into the enclosed pocket of the target holder;
introducing and ionizing a gas to create a plasma;
actuating the actuator so that the enclosed pocket is disposed in the arc chamber;
extracting ions containing the dopant from the indirectly heated cathode ion source;
retracting the actuator so that the enclosed pocket is disposed outside the arc chamber;
introducing and ionizing a second gas containing a second dopant in the arc chamber; and
extracting ions containing the second dopant from the indirectly heated cathode ion source.