Magnetron sputtering device
View Patent ↗The present invention relates to a magnetron sputtering device and technique for depositing materials onto a substrate at a high production rate in which the deposited films have predictive thickness distribution and in which the apparatus can operate continuously and repeatedly for very long periods. The present invention has realized increased production by reducing cycle time. Increased coating rates are achieved by coupling a planetary drive system with a large cathode. The cathode diameter is greater than the diameter of a planet and less than twice the diameter of the planet. Lower defect rates are obtained through the lower power density at the cathode which suppresses arcing, while runoff is minimized by the cathode to planet geometry without the use of a mask.
1. A magnetron sputtering device for applying a coating to an object comprising:
a planetary drive system including a central rotational axis and a plurality of planets disposed substantially equidistant from the central rotational axis, each planet having a secondary axis adapted for independent rotation and a diameter defining a coating area, each planet adapted to support one or more objects in an object plane, wherein a distance from the central rotational axis to the secondary axes comprises a rotation radius of the planetary drive system;
a circular cathode including a target comprising material for forming the coating having a surface plane disposed a throw distance from the object plane, the cathode having a center point, and having a cathode diameter greater than the planet diameter and up to twice the planet diameter;
anode means for providing a voltage difference to the cathode, such that electrons are returned to the anode means;
a chamber having walls for housing the cathode and the planetary drive system adapted to be evacuated in operation; and
a gas delivery system for providing a flow of sputter gas into the chamber,
wherein the rotation radius of the planetary drive system and the throw distance are between half and twice the size of the planet diameter thereby providing minimized radial runoff of the coating quality without the use of a mask,
and wherein the anode means comprises a conductive interior surface of a vessel electrically connected to a positive potential of a power supply having a single opening in communication with a chamber interior, and the conductive interior surface is surrounded by an electrically insulated outer body and electrically isolated from the walls of the chamber,
and wherein the gas delivery system providing the flow of sputter gas is disposed within the vessel, the opening and the flow of gas being operative to pressurize the anode vessel before passing through the opening into the chamber.
2. A magnetron sputtering device as defined in claim 1 , wherein the center point of the cathode is substantially aligned with the central rotational axis thereby defining a central axis of the device.
3. A magnetron sputtering device as defined in claim 1 , wherein the center point of the cathode is translated from alignment with the central rotational axis up to a third of the cathode diameter.
4. A magnetron sputtering device as defined in claim 1 further including means for adjusting the throw distance between the surface plane of the target and the object plane.
5. A magnetron sputtering device as defined in claim 1 , wherein the cathode is supported on a cathode exchange mechanism for changing the target in the chamber under vacuum.
6. A magnetron sputtering device as defined in claim 5 , wherein the cathode exchange mechanism can support a plurality of target materials for applying a plurality of different material layers to the objects during a single run.
7. A magnetron sputtering device for applying a coating to an object comprising:
an electrically charged cathode including a target comprising material for forming the coating, the cathode having a center point;
a planetary drive system disposed a throw distance from the source including a central rotational axis and a plurality of planets each supported on a secondary axis adapted for independent rotation and disposed equidistant from the central rotational axis, each planet adapted to support an object through two degrees of rotational movement;
a chamber having walls for housing the cathode and the planetary drive system adapted to be evacuated to reduced pressure in operation;
electrically charged anode means for providing a voltage difference to the cathode comprising a conductive interior surface of a vessel electrically connected to a positive potential of a power supply having a single opening in communication with a chamber interior, and the conductive interior surface is surrounded by an electrically insulated outer body and electrically isolated from the walls of the chamber;
a gas delivery system for supplying a sputter gas to the chamber for forming a plasma, wherein each of the plurality of planets has a diameter d, each secondary axis is disposed at a rotation radius r such that 0.85*d<r<1.3*d, the throw distance t between the cathode and the planetary drive system is 0.7*d<t<1.3*d, and the cathode circumscribes material having a cathode diameter CD about its center point such that d<CD<2*d.
8. A magnetron sputtering device as defined in claim 7 , wherein the central rotational axis is substantially aligned with the center point of the cathode defining a central axis of the device.
9. A magnetron sputtering device as defined in claim 7 , wherein the center point of the cathode is translated from alignment with the central rotational axis up to a quarter of the diameter of the cathode.
10. A magnetron sputtering device as defined in claim 7 , wherein the rotation radius r equal to the distance from the central rotary axis to the secondary axes is defined as r=(d+s)/2 sin(α) where α=360°/2n, d=planet diameter, s=planet separation and n=number of planets.
11. A magnetron sputtering device as defined in claim 10 , wherein the planets each have a diameter d with a separation s as small as practical between them, are defined by 0.85*d<r<1.3*d in relation to the rotation radius r.
12. The magnetron sputtering device of claim 7 further including means for adjusting the throw distance t between the planetary drive system and the cathode while the chamber is under vacuum.
13. The magnetron sputtering device of claim 7 wherein the number of planets is between 5 and 8.
14. The magnetron sputtering device of claim 7 , wherein the planet diameter is 8 inches or less.
15. The magnetron sputtering device of claim 1 , comprising one of a DC and a pulsed DC magnetron device.
16. The magnetron sputtering device of claim 1 , wherein the cathode is electrically insulated on all non-impinged surfaces.
17. The magnetron sputtering device of claim 1 , wherein the cathode is annular.
18. The magnetron sputtering device of claim 1 , wherein the vessel containing the anode is disposed outside the chamber and includes a single opening in communication with the chamber interior.
19. The magnetron sputtering device of claim 1 , wherein the secondary axes are substantially parallel to the central rotational axis.
20. The magnetron sputtering device of claim 7 , wherein the source of sputter gas is disposed within the vessel.
21. The magnetron sputtering device of claim 1 , wherein an activated reactive gas is directed toward the objects from a reactive source disposed such that the surface plane of the target is between the reactive source and the object plane.
22. The magnetron sputtering device of claim 7 , wherein the cathode diameter is at least 10 inches.