Rotatable sputtering magnetron with high stiffness
A sputtering magnetron ( 300 ) insertable in a rotatable target is described. The magnetron is designed around a single piece, multiwalled tube ( 102, 202 ) with compartments ( 316, 316′, 318, 318 ′) extending over the length of the tube. The multiwalled tube gives a much stiffer magnetron carrier structure compared to prior art magnetrons. As a result, the magnetic field generator can be mounted inside a compartment and the distance between magnets and target surface is easily adjustable as the tube is much stiffer than the generator. Additionally, the coolant channels can be incorporated inside the tube and close to the outer wall of the tube so that coolant can be supplied in the vicinity of the magnetic field generator. The increased stiffness of the magnetron allows the target tube to be carried by the magnetron—not the other way around—at least during part of the useful life of the target. As a result thin target carrier tubes can be used as they don't have to carry the magnetron anymore resulting in a longer use of the target.
1. A sputtering magnetron insertable in a rotatable target comprising:
a tube; and
an elongated magnetic field generator,
wherein said tube is a single piece, internally multiwalled tube,
wherein said tube has at least first and second compartments, extending over substantially a whole length of said tube for increasing bending stiffness of said tube,
wherein said magnetic field generator is integrated inside the tube in the first compartment, and
wherein the second compartment forms a coolant channel incorporated inside the tube.
2. The sputtering magnetron according to claim 1 wherein said tube is one piece formed by extrusion or casting or milling or welding.
3. The sputtering magnetron according to claim 2 wherein said tube is formed by extrusion of an aluminium alloy.
4. The sputtering magnetron according to claim 1 wherein said magnetic field generator has a lower bending stiffness than the bending stiffness of said tube, and wherein said magnetic field generator is adjustably mounted inside the first compartment for adjusting a distance between said magnetic field generator and an outer wall of said tube.
5. The sputtering magnetron according to claim 1 further comprising discrete supports distributed over the length of said tube for adjusting distances between said magnetic field generator and an outer wall of said tube.
6. The sputtering magnetron according to claim 5 wherein said supports are configured to allow longitudinal movement of said magnetic field generator relative to said supports for ease of adjustment of said magnetic field generator.
7. The sputtering magnetron according to claim 5 wherein said supports are adjustable by mechanical, electrical, hydraulic or pneumatic means.
8. The sputtering magnetron according to claim 5 wherein said supports are mechanically adjustable by adjustable screw, by an adjustable sliding means, by shims, or by washers.
9. The sputtering magnetron according to claim 5 wherein said supports are adjustable from outside said magnetron responsive to a process status indicator.
10. The sputtering magnetron according to claim 1 wherein the second compartment is adjacent to an outer tube wall.
11. The sputtering magnetron according to claim 10 wherein said coolant channel has exit holes arranged lengthwise so as to permit a coolant flow between said tube and said target at least in front of said magnetic field generator so as to reduce friction between said target and said magnetron.
12. The sputtering magnetron according to claim 10 wherein a returning channel for collection and drain of the coolant is formed by a third compartment in said tube or by a longitudinal indentation in an outer wall of the magnetron extending over a length of said magnetron.