GAS RING FOR A PVD SOURCE

Abstract

A gas ring for a PVD-source with a cathode having a target for material deposition. The gas ring includes an inner rim and an outer rim and at least one flange between the inner and the outer rim. The gas ring further includes: —a gas inlet; —gas openings arranged circumferentially in or near the inner rim; —at least one circumferential gas channel connected to the gas inlet and/or the gas openings; —a cooling duct.

Claims

1-18. (canceled)

19. A PVD-source (1) with a cathode (24) having a target (6) for material deposition, and a gas ring, wherein said gas ring (2) comprises an inner rim (3) and an outer rim (4) and at least one flange (5, 5′) between the inner and the outer rim, said gas ring (2) further comprising: a gas inlet (6); gas openings (7) arranged circumferentially in or near the inner rim (3); at least one circumferential gas channel (8, 9) connected to the gas inlet and/or the gas openings; a cooling duct (11); and a circumferential anode facing the circumference of the target and being releasably mounted on or near the inner rim; wherein the material of the gas ring, of optional subrings, or of an optional first and second ring is of a first material having a first coefficient of thermal expansion (CTE) and the anode is made of a second material having a higher coefficient of thermal expansion than the first material.

20. The PVD-source according to claim 19, wherein the cooling duct is a water duct (10).

21. The PVD-source according to claim 19, comprising a first circumferential gas channel (8) and a second circumferential gas channel (9), the first gas channel (8) being connected to the gas inlet (6), the second gas channel (9) being connected to the gas openings, both gas channels (8,9) being separated by a circumferential flow modifier (10).

22. The PVD-source according to claim 21, wherein the flow modifier is a partition wall having small holes evenly arranged on the circumference of the partition wall.

23. The PVD-source according to claim 21, wherein the flow modifier is a grid or a frit.

24. The PVD-source according to claim 19, said gas ring being made of at least one solid ring or of at least two or more subrings which are joined together.

25. The PVD-source according to claim 23, wherein the subrings comprise a first ring comprising a gas inlet, e.g. a gas connector, at least a first part of a gas inlet channel, fluid ports, and at least a first part of the fluid inlet and outlet ducts, and a second ring comprising the circumferential gas channel(s) and at least a part of the circumferential cooling duct.

26. The PVD-source according to claim 19, wherein the second material is one of aluminum or copper.

27. The PVD-source according to claim 19, wherein the first material is stainless steel and the second material is aluminum.

28. The PVD-source according to claim 19, wherein the anode is mounted on a first flange, said first flange being offset outwardly from the inner rim.

29. The PVD-source according to claim 19, further comprising a second flange on a step in the inner wall of the ring.

30. The PVD-source according to claim 19, further comprising a third flange on a step in the outer wall of the ring.

31. The PVD-source according to claim 19, wherein said PVD-source is a sputter-source.

32. Vacuum chamber comprising a PVD-source with a gas ring according to claim 19.

Description

FIGURES

[0024] The invention shall now be further exemplified with the help of figures. The figures show:

[0025] FIG. 1: A schematic drawing of state-of-the-art gas rings;

[0026] FIG. 2: A schematic drawing of an inventive gas ring.

[0027] On the left side of FIG. 1, that is left from axis Z, a gas ring 2′ according to the state-of-the-art is shown, mounted in a vacuum chamber 40′ and surrounding an anode 34 of a circular PVD-source 1′, the latter further comprising a cathode 24 having a cathode base 25 with a power connection 28 and a target 26 to be sputtered or evaporated. In the lower left side of FIG. 1 a quadrant of the front face of the PVD-source 1′ is shown, that is towards the surface 26 of the target 26 and the inner surface 35 of the anode which is inclined or concave towards the target surface 26. Openings 7′ in the front side of the gas ring 2′ are directed axially. Cross section A-A is shown in the upper left half of FIG. 1. Gas is fed to gas inlet 6′, distributed within the gas ring 2′ and expelled into the process atmosphere as symbolized by arrows. In the process atmosphere molecules of the process gas can be positively ionized, e.g. Ar to Art, and in the following be attracted towards the target surface 26 for sputtering and/or surface alloying in case of reactive processes where mixtures of inert sputter-gas(s) and reactive gas(s) are used. Gas ring 2″ can be plugged to the vacuum chamber 40′ by a cylindrical gas inlet 6′ comprising two O-rings for press-fitting and sealing. Additional screw or clamp fixings (not shown) will be applied as usually with state-of-the-art gas rings. The anode thereby is mounted directly to a wall of the vacuum chamber 40′ round an aperture for the sputter-source 1′.

[0028] On the right side of FIG. 1 another state-of-the-art gas ring 2″ is shown, encompassing the target and situated behind the anode 34 when looking towards the face or front side of the PVD-source 1. Having a cylindrical gas inlet 6″ and gas openings 7″, the ring 2″ is similar in construction to the ring 2′ as shown on the left side. An isolating ring 31 is mounted between the target 26′ and the gas ring 2″ to avoid the generation of parasitic plasmas between the target and the gas ring. In this situation the anode 34′ is mounted within the aperture of the vacuum chamber 40″ which is foreseen for the sputter source 1′. Despite of the widespread use of state-of-the-art gas rings 2′, 2″ as shown with vacuum equipment and PVD-sources 1′ in a wide spread field of surface engineering applications, such gas rings, especially when applied with RF-sputtering still tend to make problems with reference to process stability and uniformity of gas distribution as mentioned in the section technical background.

[0029] An inventive gas ring 2 as mounted to a PVD-source 1 in a vacuum chamber 40, symbolized by parts of its vacuum enclosure, is shown in FIG. 2. As with FIG. 1 in the lower left part a quadrant of the front face of the respective PVD-source is shown. In this case with two cross sections as displayed schematically on the left and right upper part of the drawing: At the left side cross section B-B intersecting the gas ring 2 in the area of the cooling fluid inlet duct 19c, and at the right side cross section C-C intersecting at the gas inlet 6. Gas inlet 6 may have a connector 41 as shown with the quadrant scheme below. Fittings 41 and 42 for gas respectively fluid connection can be industrial standard fittings like Swagelok-fittings or the like.

[0030] With reference to FIG. 2 a gas ring 2 is shown in a set up comprising an outer subring 12 and inner subring 13 (see cross section C-C) which are welded together, e.g. by a WIG-welding process. An alternative dividing line 15 of the two subrings is shown in dashed lines with cross section B-B. Such alternative subrings can be used to produce a gas ring of the same dimensions and properties. Same reference numbers with FIG. 1 refer to same parts in FIG. 2, also if respective parts of same number may vary in certain aspects of geometry and design. The area comprising the gas inlet 6 or the gas inlet and the fluid inlet 19 may be manufactured as ring inserts and be inserted as e.g. one prefabricated part of the gas ring to ease manufacturing of respective gas inlet channels 6c or fluid inlet ducts 19c, see dashed lines in the lower left quadrant.

[0031] The stainless gas ring 2 is delimited in a sidewise direction by an outer rim 4 and by an inner rim 3 towards the anode 34 made of aluminum, or copper in an alternative embodiment. For optimum contact and process-stability the anode is fixed (e.g. with screws 29 or clamps) to the gas ring. Radially elongated slots may be used in the anode 34 to allow respective movement of the aluminum anode towards the cylindrical seat of the stainless gas ring due to the different CTE of the materials. Due to this construction the gas ring 2 and the anode 34 can be pre-assembled and easily mounted together to the PVD-source or the vacuum chamber.

[0032] In cross-section B-B details of the cooling fluid supply, which usually will be used with tempered water, can be seen. The fluid system comprising a cooling fluid inlet port 19, a cooling fluid inlet duct 19c, a circumferential cooling duct 21 running from the inlet duct 19c round the gas ring 2 to the outlet duct and thereby to the cooling fluid outlet port 20, which can have the same design feature as the fluid inlet part, both being provided with an outer closing 22 and respective fluid fittings 42. The inner closing ring 23 covers the duct 21, both the outer closing 22 and the inner closing ring 23 can be made from laser welded stainless steel sheets of 0.5 to 2.5 mm thickness to withstand the fluid pressure in the duct, e.g. water at 0.1 to 10 bar. Below the circumferential fluid duct 21, the circumferential gas channels 8 and 9 separated by a flow modifier 10 can be seen. The flow modifier 10 and an inner closure ring 17 which separates the second channel 9 against the vacuum chamber can be again made of laser welded stainless sheets of the same dimensions as mentioned above. For fluid communication between the first 8 and second gas channel 9 holes 11 of 0.5 mm diameter are arranged regularly along the circumference of the flow modifier 10. For fluid communication between the second gas channel 9 and the vacuum chamber 40 (see also respective arrow) gas openings 7 are provided within the inner rim 3. The opening 7 extend to the lower side of the gas ring 2, which refers to the face side of the PVD-source, see also cross section C-C quadrant of source face. By the two channel construction and respective design of the rectangular openings 7 arranged tangential to the inner rim 3 and anode 34, an optimal even distribution of any gas or gas mixture can be provided to the target surface and/or a substrate in front of and centered to the target.

[0033] With reference to cross section C-C further details of the gas system are shown with gas flow symbolized by arrows: gas inlet 6, and gas inlet channel 6c, as well as gas channels 8, 9, flow modifier 10, and gas opening 7. On a first flange 5 a centering pin 18 to ease the mounting of the anode 34 can be seen. On a second flange 5′ a gasket 37 and a copper ring 38 are provided as vacuum sealing, e.g. to a cover lid of the vacuum chamber 40, respectively as RF-protection. The ring may further sit with a third flange including an outer closure 16 of the gas inlet channel 6c on a flange of the vacuum chamber 40 (dashed lines) which may comprise a further gasket 37. The anode 35 again can have an inner surface 35 which is inclined (solid) or concave (dashed) towards the target surface 26.

[0034] In cross-section B-B the cathode 24 set-up can be the same as with the state-of-the-art set-up in FIG. 1 and may refer to a target 26 which is bonded to the cathode base 25 forming an outer cathode margin 27. Here to an isolating cylinder 30 may surround the cathodically biased parts 25 and 26 in a dark room distance. However, the cathode set-up 24 in cross-section C-C shows a target 26 which is mechanically clamped to the cathode base 25 by clamp ring 32 and distance ring 33 which are screwed to the cathode base 25. Such cathode set-ups can be used with target materials of high mechanical strength and provides a better stability for high power sputtering.

[0035] Finally, it should be mentioned that all features as shown or discussed in connection with only one of the embodiments or examples of the present invention and not further discussed with other embodiments can be seen to be features well adapted to improve the performance of other embodiments of the present invention too, as long such a combination cannot be immediately recognized as being prima facie inexpedient for the man of art. Therefore, with the exception as mentioned all combinations of features of certain embodiments can be combined with other embodiments where such features are not mentioned explicitly.

REFERENCE NUMBERS

[0036] 1 PVD-source [0037] 2,2′,2″ gas ring [0038] 3 inner rim [0039] 4 outer rim [0040] 5,5′ flange [0041] 6,6′,6″ gas inlet [0042] 6c gas inlet channel [0043] 7,7′ gas openings [0044] 8 first circumferential gas channel [0045] 9 second circumferential gas channel [0046] 10 flow modifier [0047] 11 holes [0048] 12 outer subring [0049] 13 inner subring [0050] 14 dividing line [0051] 15 alternative dividing line [0052] 16 outer closure [0053] 17 inner closure ring [0054] 18 centering pin [0055] 19 cooling fluid inlet port [0056] 19c cooling fluid inlet/outlet duct [0057] 20 cooling fluid outlet port [0058] 21 circumferential cooling duct [0059] 22 outer closing [0060] 23 inner closing ring [0061] 24 cathode [0062] 25 cathode base [0063] 26/26′ target/target surface [0064] 27 outer margin [0065] 28 power connection [0066] 29 pressing means (e.g. screw) [0067] 30 isolator [0068] 31 isolator [0069] 32 clamp ring [0070] 33 distance ring [0071] 34 anode [0072] 35 inner anode surface [0073] 37 gasket [0074] 38 RF-protection [0075] 39 seal (O-ring) [0076] 40,40′,40″ vacuum chamber [0077] 41 gas connector [0078] 42 water fitting