Sputtering apparatus and process for high rate coatings

• US 6,488,824 B1
• Filed: 07/14/2000
• Issued: 12/03/2002
• Est. Priority Date: 11/06/1998
• Status: Expired due to Fees

• Current Assignee: Winsky Technology Limited
• Original Assignee: Raycom Technologies, Inc. (Wei Jun Li)
• Inventors: Petersen, Carl T., Rosenblum, Martin P., Hollars, Dennis R.
• Primary Examiner(s): VerSteeg, Steven H.
• Application Number:
  US09/616,489
• Time in Patent Office: 872 Days
• Field of Search: 204/192.12, 204/192.22, 204/298.07, 204/298.11, 204/298.12, 204/298.2, 204/298.22, 204/298.26, 204/298.28
• US Class Current: 204/192.22
• CPC Class Codes: C23C 14/35 by application of a magnetic field, e.g. magnetron sputtering C23C14/3457 takes precedence
• CPC Class Codes: C23C 14/352 using more than one target C23C14/56 takes precedence
• CPC Class Codes: C23C 14/568 Transferring the substrates through a series of coating stations C23C14/562 takes precedence
• CPC Class Codes: H01J 37/3405 Magnetron sputtering

Abstract

A sputtering apparatus and method for high rate deposition of electrically insulating and semiconducting coatings with substantially uniform stoichiometry. At least one set of vertically mounted, dual and triple rotatable cylindrical (or planar) magnetrons with associated vacuum pumps, form semi-isolated sputtering modules. The sputtering modules can be independently controlled for the sequential deposition of layers of similar or different materials. Constant voltage operation of AC power with an optional reactive gas flow feedback loop maintains constant coating stoichiometry during small changes in pumping speed caused by substrate motion. The coating method is extremely stable over long periods (days) of operation, with the film stoichiometry being selectable by the voltage control point. The apparatus may take the form of a circular arrangement of modules for batch coating of wafer-like substrates, or the modules may be arranged linearly for the coating of large planar substrates

Claims

1. A method for high rate deposition of thin films, comprising:

presenting a substrate to a deposition apparatus;

fitting dual cylindrical magnetrons in a vacuum chamber of the deposition apparatus, each of the dual cylindrical magnetrons including

a target made out of a target material and having a cylindrical shape, the target being rotable,

a magnet assembly supporting a sputtering plasma in a sputtering region that causes particles of the target material to be deposited on the substrate;

fitting a shield around the target within each of the dual cylindrical magnetrons so that a narrow gap is formed between the shield and the target, the shield having a cutout facing the substrate;

introducing a sputtering gas into the vacuum chamber and allowing the sputtering gas to flow into the narrow gap, the sputtering gas flowing in the narrow gap around the target in each of the cylindrical magnetrons at higher pressure than in the vacuum chamber and entering the sputtering region at the edges of the shield cutout, wherein a sputtering gas curtain exists in the narrow gap around regions of the target which are not being sputtering during rotation of the target; and

introducing a reactive gas into the vacuum chamber, wherein a sweeping action of the sputtering gas flow in the narrow gap together with the higher pressure of the sputtering gas in the narrow gap maintains the target within each of the cylindrical magnetrons in a state substantially free of the reactive gas during sputtering operations.

2. The method of claim 1 wherein the shield is constructed from a conductive material so that it can serve as an anode.

3. The method of claim 1 wherein the deposition apparatus performs high rate reactive deposition of dielectric thin films.

4. The method of claim 1 wherein the target material is either conductive or insulating material.

5. The method of claim 1 wherein the sputtering gas is argon and the reactive gas is oxygen.

6. The method of claim 1 wherein sputtered material from the target is deposited on the substrate at a particular substrate position, the method further comprising fitting the deposition apparatus with a deposition shield that prevents high angle, low energy sputtered material from reaching the particular substrate position.

7. The method of claim 1 wherein the pressure of the sputtering gas in the vacuum chamber is one millitorr or less and the pressure in the narrow gap is more than one millitorr.

8. The method of claim 1 wherein, for added control sensitivity, the deposition apparatus is fitted with a fast acting valve having a switching time of a few milliseconds or less for the introduction of the sputtering gas.

9. The method of claim 8 wherein the fast acting valve is a Piezoelectric valve with a fast response time.

10. The method of claim 1 wherein the sputtering gas is introduced into the vacuum chamber at a side of the vacuum chamber in order to allow mounting of a turbomolecular pump on the back of the chamber.

11. The method of claim 1 further comprising

fitting the deposition apparatus with a local pump and one or more pumps located in the vacuum chamber; and

allowing the sputtering gas to flow into the local pump rather than through the one or more pumps in the vacuum chamber so that it is possible to increase the flow of sputtering gas and at the same time maintain a low total pressure of the sputtering gas and a fast response time, wherein deposition process control is improved.

12. An apparatus for high rate deposition of thin films, comprising:

at least one set of dual cylindrical magnetrons in a vacuum chamber of the deposition apparatus, each of the cylindrical magnetrons including

a target made of a target material and having a cylindrical shape, the target being rotatable,

a magnet assembly for supporting a sputtering plasma in a sputtering region that causes particles of the target material to be deposited on a substrate, and

a shield partially encapsulating the target so that a narrow gap is formed between the shield and the target, the shield having a cutout bordering the sputtering region;

means for introducing a sputtering gas into the vacuum chamber at a first pressure via the narrow gap in each of the cylindrical magnetrons, the sputtering gas flowing in the narrow gap around the target in each of the cylindrical magnetrons being at higher pressure than in the vacuum chamber and entering the sputtering region at the edges of the shield cutout, thereby forming a sputtering gas curtain around regions of the target which are not being sputtered during rotation of the target; and

means for introducing a reactive gas into the vacuum chamber at a second pressure lower than said first pressure such that the sputtering gas flow in the narrow gap within each of the dual magnetrons, together with the higher pressure of the sputtering gas in the narrow gap causes a sweeping action that maintains the target within the regions of the gap in a state substantially free of the reactive gas during sputtering operations.

13. The apparatus of claim 12 wherein the shield is constructed from a conductive material so that it can serve as an anode.

14. The apparatus of claim 12 configured to perform high rate reactive deposition of dielectric thin films.

15. The apparatus of claim 12 wherein the target material is either conductive or insulating material.

16. The apparatus of claim 12 wherein the sputtering gas is argon and the reactive gas is oxygen.

17. The apparatus of claim 12 further comprising a deposition shield positioned to prevent high angle, low energy sputtered material from reaching the substrate, particularly, at a location where sputtered material from the target is being deposited, wherein the apparatus produces a restricted band of sputtered target material and, at the same time, achieves improved target material collection efficiency.

18. The apparatus of claim 12 wherein the pressure of the sputtering gas in the vacuum chamber is one millitorr or less and the pressure in the narrow gap is more than one millitorr.

19. The apparatus of claim 12 wherein, for added control sensitivity, the sputtering gas introduction means includes a fast acting valve having a switching time of a few milliseconds or less.

20. The apparatus of claim 19 wherein the fast acting valve is a Piezoelectric valve with a fast response time.

21. The apparatus of claim 12 wherein the sputtering gas introduction means is mounted on a side of the vacuum in order to allow mounting of a turbomolecular pump on the back of the chamber.

22. The apparatus of claim 12 further comprising a local pump and one or more pumps mounted in the vacuum chamber in a configuration that allows the sputtering gas to flow into the local pump rather than through the one or more pumps so that it is possible to increase the flow of sputtering gas and at the same time maintain a low total pressure of the sputtering gas and a fast response time, wherein deposition process control is improved.

23. The apparatus of claim 12 in which the shield in one of the dual cylindrical magnetrons is electrically isolated from the shield in another of the dual cylindrical magnetron, and wherein the shield in either or both of the dual cylindrical magnetrons may be driven in phase with an AC power source.

24. An apparatus for high rate deposition of thin films, comprising:

at least one set of three magnetrons arranged to form a triple magnetron configuration in which two of three magnetrons are mounted symmetrically opposite each other and equidistant from a substrate position while a third of the three magnetrons is mounted further away from the substrate position and equidistant from the two magnetrons, the two, symmetrically opposed magnetrons being mounted facing each other to form a hall of mirrors for sputtering and resputtering target material, the third magnetron being configured to capture and resputter the target material so that a substantial part of the sputtered target material reaches the substrate position, each of the three magnetrons including a target constructed of the target material, a magnet assembly coupled to the target and supporting a sputtering plasma in a sputtering region in front of the magnet assembly, the magnet assembly being capable of orientation at various angles, wherein the deposition apparatus provides a superior net collection efficiency.

25. The apparatus of claim 24 wherein the target in each of the three magnetrons is rotatable, and wherein each the three magnetrons further includes a structure partially encapsulating the target so as to allow introduction of a sputtering gas in close proximity to the plasma region and formation of a protective zone around those regions of the target that are not being sputtered during rotation of the target.

26. The apparatus of claim 25 wherein each of the three magnetrons further includes water cooling means coupled to the target encapsulating structure.

27. The apparatus of claim 24 being configured for deposition of metallic and/or dielectric thin films formed in the presence of a reactive gas.

28. The apparatus of claim 24 in which the magnet assembly in the three magnetrons is structurally substantially similar.

29. The apparatus of claim 24 in which the triple magnetron configuration can assume a geometry such that substantially most of the sputtered material eventually reaches the substrate position.

30. The apparatus of claim 24 wherein the magnetrons are either cylindrical or planar so that the target is either cylindrical or planar, respectively.

31. The apparatus of claim 24 in which the magnet assemblies of the two, symmetrically opposed magnetrons are mounted directly opposing each other and together with the magnet assembly of the third magnetron forming six magnetic field patterns.

32. The apparatus of claim 24 in which the magnet assemblies of the two, symmetrically opposed magnetrons are mounted directly opposing each other and forming magnetic fields in two directions, one of the magnetic fields being central and oriented in one direction and others of the magnetic fields, one on each side of the central field, being oriented in the opposite direction.

33. The apparatus of claim 24 in which the magnet assemblies of the two, symmetrically opposed magnetrons are magnetic plates mounted directly opposing each other and forming a uni-directional magnetic field.

34. The apparatus of claim 24 in which the target material of the target in the third magnetron is different from the target material of the targets in the two, symmetrically opposed magnetrons.

35. The apparatus of claim 24 in which a sputtering rate of the third magnetron can be controlled independently from the sputtering rate of the two, symmetrically opposed magnetrons.

36. The apparatus of claim 24 in which the three magnetrons can be separately or jointly powered by each or a combination of DC, AC or RF power sources.

37. The apparatus of claim 24 in which the at least one set includes more than three magnetrons.

38. The magnetron of claim 24 in which not all the magnetrons have identical dimensions.