Tubular target having a protective device

Abstract

A tubular target for cathode atomization does not have a backing tube and it is made of molybdenum or a molybdenum alloy. The target has an inner surface which is in contact at least in certain regions with a cooling medium, wherein at least one region of the inner surface is separated from the cooling medium by at least one protective device. By way of example, the protective device may be in the form of a polymer layer. The tubular target exhibits outstanding long-term stability.

Claims

1. A tubular target for cathode atomization, comprising: a tubular target formed without a backing tube and made of molybdenum or a molybdenum alloy having a molybdenum content of at least 50 at. %; said tubular target having a sputtering surface and an inner surface to be cooled, at least in certain regions thereof, with a cooling medium; and at least one protective device being a coating layer applied on the inner surface by a coating process, said coating layer being disposed to separate at least one region of the inner surface from the cooling medium and to prevent contact of the cooling medium with the at least one region of the inner surface, and wherein the coating layer comprises at least one polymer, said polymer is provided with a filler and said filler comprises ceramic.

2. The tubular target according to claim 1, wherein said protective device has a surface adjoining and adhering to said inner surface in areal contact with said inner surface.

3. The tubular target according to claim 2, wherein said protective device has a thickness of 0.0005 mm to 1 mm.

4. The tubular target according to claim 3, wherein said protective device has a thickness of 0.0005 mm to 0.1 mm.

5. The tubular target according to claim 1, wherein said protective device is a single-ply or multi-ply layer.

6. The tubular target according to claim 1, wherein an entirety of said inner surface is separated from the cooling medium by at least one protective device.

7. The tubular target according to claim 1, wherein said polymer is a thermally and/or electrically conductive polymer.

8. The tubular target according to claim 1, wherein said polymer is a polymer selected from the group consisting of epoxy resin, polyethylene, polypropylene, polyurethane, polyvinyl chloride, polyester, vinyl ester, and fluoroelastomer.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) The FIGURE shows an oblique view of the tubular target -1- according to the invention having a sputtering surface -2-, and inner surface -3- and a protective device -4-.

DESCRIPTION OF THE INVENTION

Example 1

(2) A molybdenum tube -1- having an internal diameter of 125 mm, an external diameter of 165 mm and a sputtering surface -2- was produced in accordance with the process described in EP 1 937 866 (A). The inner surface -3- of the molybdenum tube which was to be coated had a length of 1500 mm. The turned inner surface was firstly roughened by sand blasting. The subsequent coating was effected by brushing on an epoxy resin filled with 70% by volume Al having a particle size of 50 μm. The layer thickness of the protective device -4- was approximately 300 μm.

Example 2

(3) Cylindrical molybdenum samples having a diameter of 10 mm and a length of 50 mm were tested for corrosion resistance in the uncoated and coated (Examples 2a to 2g) state in exposure tests. In this case, the samples were stored in various cooling media over a period of time of 160 hours, and the loss in mass of the samples was measured. The coolant bath was agitated by means of a magnetic stirrer during the test period. The results of the measurements are shown in Table 2. The samples designated with R (reference samples) correspond to the prior art (uncoated). Examples 2a to 2g are examples according to the invention.

Example 2a

(4) The turned surface was roughened by sand blasting. The subsequent coating was effected by brushing on an epoxy resin comprising 70% by volume Al having a particle size of 50 μm. The layer thickness was approximately 300 μm.

Example 2b

(5) The turned surface was roughened by sand blasting. The subsequent coating was effected by wet coating with an alkyd resin paint (a polyester), which was dried out in air. The layer thickness was approximately 100 μm.

Example 2c

(6) The turned surface was roughened by sand blasting. The subsequent coating was effected by brushing on an epoxy resin filled with 70% by volume Al.sub.2O.sub.3. The layer thickness was approximately 300 μm.

Example 2d

(7) The turned surface was cleaned and degreased by pickling. The subsequent coating was effected by means of the powder spraying of a polyurethane compound. The layer thickness was approximately 500 μm.

Example 2e

(8) The turned surface was cleaned and degreased by pickling. A layer of copper having a thickness of 15 μm was deposited by a conventional electrochemical process (copper sulphate basis).

Example 2f

(9) The turned surface was roughened by sand blasting. An SiO.sub.2-based slurry was then applied and heat-treated at 200° C./60 min.

Example 2g

(10) The turned surface was roughened by sand blasting. A TiN layer having a thickness of 2 μm was then applied by means of CVD.

(11) TABLE-US-00002 TABLE 2 Corrosion Change Mo content rate in pH in the water Sample Cooling water Inhibitor [mm/a] value [mg] R Mains water No 0.9 4 2300 R Osmosis water No 0.7 2 1500 R Mains water Yes 0.01 0-1 20 R Osmosis water Yes 0.2 3-4 400 Ex. 2a Mains water No <0.0001 <0.1 <1 Ex. 2a Osmosis water No <0.0001 <0.1 <1 Ex. 2a Mains water Yes <0.0001 <0.1 <1 Ex. 2a Osmosis water Yes <0.0001 <0.1 <1 Ex. 2b Mains water No <0.0001 <0.1 <1 Ex. 2c Mains water No <0.0001 <0.1 <1 Ex. 2d Mains water No <0.0001 <0.1 <1 Ex. 2e Mains water No <0.0001 <0.1 <1 Ex. 2f Mains water No <0.0001 <0.1 <1 Ex. 2g Mains water No <0.0001 <0.1 <1