Cooled sputtering target for ion source
An ion source with a target holder for holding a solid dopant material is disclosed. The target holder is mounted to a shaft, which may be in communication with an actuator, which allows the solid dopant material to be inserted and retracted from the arc chamber. The shaft and/or the target holder is actively cooled such that the solid dopant material remains below its melting point. In this way, the solid dopant material may be inserted into the arc chamber without any melting. The cooling mechanisms used may include gas cooling, liquid cooling, thermoelectric cooling or other cooling techniques.
1 . An ion source for generating an ion beam, comprising:
an arc chamber, comprising a plurality of walls connecting a first end and a second end;
a target holder to hold a solid dopant material;
a shaft connected to the target holder, to extend the target holder into the arc chamber, such that, when extended, the solid dopant material is exposed to a plasma in the arc chamber;
a vacuum seal to divide the shaft into two portions, such that the target holder and a first portion of the shaft are in communication with the arc chamber and a second portion is disposed in an atmospheric environment; and
a cooling system to actively cool the solid dopant material.
2 . The ion source of claim 1 , wherein the cooling system actively cools the shaft.
3 . The ion source of claim 2 , wherein the shaft is made from copper and at least a portion of the shaft is covered by a sheath, made of a non-copper material.
4 . The ion source of claim 2 , wherein the shaft is cooled using a cooling fluid.
5 . The ion source of claim 4 , wherein the shaft includes a hollow cavity comprising an inlet channel and an outlet channel, such that the cooling fluid flows through an interior of the shaft.
6 . The ion source of claim 5 , wherein a partition is located within the hollow cavity and separates the inlet channel from the outlet channel.
7 . The ion source of claim 5 , wherein the shaft includes two tubes, wherein the hollow cavity defines an outer tube, and an inner tube is disposed within the outer tube and does not extend to a distal end of the shaft, wherein the two tubes form the inlet channel and the outlet channel.
8 . The ion source of claim 2 , wherein the shaft is cooled by flowing a cooling gas toward an exterior of the shaft.
9 . The ion source of claim 2 , further comprising a cooling tube, in fluid communication with a fluid chiller, wherein the cooling tube is wrapped around a portion of the shaft.
10 . The ion source of claim 2 , further comprising a cooling plate affixed to a proximal end of the shaft, wherein the cooling plate serves as a heat sink.
11 . The ion source of claim 10 , wherein channels are disposed in the cooling plate and cooling fluid flows through the cooling plate to maintain the cooling plate within a predetermined temperature range.
12 . The ion source of claim 1 , wherein the shaft and/or the target holder is actively cooled using heat pumps affixed thereto.
13 . The ion source of claim 1 , wherein the target holder is actively cooled using a cooling fluid that passes through the target holder.
14 . An ion implanter, comprising:
an ion source to generate an ion beam; and
one or more beamline components to direct the ion beam toward a workpiece,
wherein the ion source comprises:
an arc chamber, comprising a plurality of walls connecting a first end and a second end;
a target holder to hold a solid dopant material;
a shaft connected to the target holder, to extend the target holder into the arc chamber, such that, when extended, the solid dopant material is exposed to a plasma in the arc chamber;
a vacuum seal to divide the shaft into two portions, such that the target holder and a first portion of the shaft are in communication with the arc chamber and a second portion is disposed in an atmospheric environment; and
a cooling system to actively cool the solid dopant material.
15 . The ion implanter of claim 14 , further comprising:
a thermocouple to measure a temperature of the solid dopant material; and
a controller, wherein the controller uses information from the thermocouple to maintain the solid dopant material within a desired temperature range.
16 . The ion implanter of claim 15 , wherein the controller actively cools the shaft to maintain the solid dopant material within the desired temperature range.
17 . The ion implanter of claim 15 , wherein the shaft is cooled by a fluid passing through an interior of the shaft or a fluid passing over an exterior of the shaft, wherein the controller controls a temperature of the solid dopant material by controlling a rate of flow of the fluid.
18 . The ion implanter of claim 15 , wherein the shaft is cooled by attachment of a cooling plate to a proximal end of the shaft, wherein the controller controls a temperature of the solid dopant material by controlling a temperature of the cooling plate.
19 . The ion implanter of claim 15 , wherein the shaft and/or target holder is cooled by attachment of one or more heat pumps, wherein the controller controls a temperature of the solid dopant material by controlling power supplied to the one or more heat pumps.
20 . The ion implanter of claim 15 , wherein the target holder is cooled by a fluid passing through an interior of the target holder, wherein the controller controls a temperature of the solid dopant material by controlling a rate of flow of the fluid.