Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
  • C23C14/34—Sputtering
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
  • C23C14/34—Sputtering
  • C23C14/3407—Cathode assembly for sputtering apparatus, e.g. Target
  • C23C14/3414—Metallurgical or chemical aspects of target preparation, e.g. casting, powder metallurgy
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
  • B22F3/20—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces by extruding
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F5/00—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
  • B22F5/10—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product of articles with cavities or holes, not otherwise provided for in the preceding subgroups
  • B22F5/106—Tube or ring forms
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F7/00—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression
  • B22F7/06—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite workpieces or articles from parts, e.g. to form tipped tools
  • B22F7/08—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite workpieces or articles from parts, e.g. to form tipped tools with one or more parts not made from powder
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
  • B22F2998/10—Processes characterised by the sequence of their steps
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C1/00—Making non-ferrous alloys
  • C22C1/04—Making non-ferrous alloys by powder metallurgy
  • C22C1/045—Alloys based on refractory metals

Definitions

• the invention relates to a method for producing a tubular target, which comprises a tube of molybdenum or a molybdenum alloy with an oxygen content of less than 50 ⁇ g/g, a density of greater than 99% of the theoretical density, and an average grain size transversely to the axial direction of less than 100 ⁇ m as well as a supporting tube of a non-magnetic material.
• a target is understood as meaning the material to be sputtered of a cathode atomization system.
• Rotating tubular targets are known and described for example in U.S. Pat. Nos. 4,422,916 and 4,356,073.
• the tubular target rotates about a magnetron located in the tube.
• Tubular targets are predominantly used for producing coatings over a large area.
• the rotation of the tubular target achieves the effect of uniform erosion of the sputtering material.
• Tubular targets therefore have a high utilization rate of the target material and a long target lifetime, which is of significance in particular in the case of expensive coating materials, as is the case with molybdenum.
• the utilization rate for planar targets is around 15 to 40% and for tubular targets around 75 to 90%.
• the target cooling performed in the space inside the tubular target is much more effective than in the case of planar targets as a result of the more favourable heat transfer in the tube, which makes a higher coating rate possible.
• the tubular target is usually connected to a supporting tube.
• the supporting tube must in this case be of a non-magnetic material, in order not to interact with the magnetic field which determines the erosion region.
• tubular targets are advantageous whenever substrates of a large area are to be coated.
• molybdenum as the target material, this is the case for example in LCD-TFT production and glass coating.
• Tubular targets may also be produced by winding a thick strip around a core and welding the contact regions.
• the weld seam has a much more coarse microstructure and pores, which leads to non-uniform erosion and, as a consequence, different layer thicknesses.
• the welded region is extremely brittle and consequently at risk of cracking.
• a further tubular target is known from U.S. Pat. No. 4,356,073. Production takes place in this case by the sputtering material being deposited on a backing tube by plasma spraying. Even using the vacuum plasma spraying technique, however, completely dense tubular targets cannot be produced with an adequately low gas content. Electrochemical deposition, as is used for Cr and Sn, is also not suitable for molybdenum and its alloys.
• U.S. Pat. No. 5,435,965 and European patent publication EP 0 500 031 A1 describe the production of a tubular target by hot-isostatic pressing. There, a backing tube is positioned in a can, so as to produce between the backing tube and the mold an intermediate space into which powder of the target material is filled. After closing the can, it is subjected to a hot-isostatic densification operation. The amount of powder used in relation to the weight of the finished tubular target is in this case unfavourably high.
• a method of producing a tubular target which comprises the following method steps:
• a metal powder with a particle size according to Fisher of 0.5 to 10 ⁇ m is used.
• Mo powder with a metal purity of greater than 99.9% by weight is advantageously used.
• the particle size however likewise lying in the range from 0.5 to 10 ⁇ m.
• the powder is filled into a flexible mold, in which the core is already positioned. The core determines the inner diameter of the tube blank, with allowance for the compaction during the pressing operation and the sintering shrinkage.
• Customary tool steels are suitable as the material for the core.
• the flexible mold After filling the flexible mold with the metal powder and liquid-tight closing of the flexible mold, it is positioned in a pressure vessel of a cold-isostatic press. The compaction takes place at pressures between 100 and 500 MPa. After that, the green compact is taken out of the flexible mold and the core is removed. Following that, the green compact is sintered at a temperature in the range from 1600° C. to 2500° C. in a reducing atmosphere or a vacuum. Below 1600° C., adequate densification is not achieved. Above 2500° C., undesired grain coarsening begins. The sintering temperature to be chosen depends on the particle size of the powder.
• Green compacts produced from a powder with a particle size of 0.5 ⁇ m according to Fisher can be sintered at a sintering temperature of as low as 1600° C. to a density of greater than 95% of the theoretical density, whereas for green compacts which are produced from a powder with a particle size of 10 ⁇ m according to Fisher a sintering temperature of approximately 2500° C. is required. If the dimensional accuracy of the pressing process is not adequate, which is usually the case, the sintered blank is machined. The outer diameter of the sintered blank is in this case determined by the inner diameter of the container of the extrusion press.
• the outer diameter of the sintered blank is somewhat smaller than the inner diameter of the container.
• the inner diameter is in turn determined by the diameter of the mandrel.
• the tube blank is heated to a temperature T, where DBTT ⁇ T ⁇ (T S ⁇ 800° C.).
• DBTT is to be understood here as meaning the ductile brittle transition temperature.
• the upper temperature element is given by the melting temperature (T S ) of the molybdenum alloy less 800° C. This ensures that no undesired grain coarsening takes place during the extruding operation.
• the initial heating may in this case be performed in a conventional gas or electrically heated furnace (for example a rotary hearth kiln), allowance having to be made that the gas flow control is chosen such that the lambda value is neutral or negative.
• inductive reheating may be performed. After the initial heating operation, the tube blank is rolled in a glass powder mixture. After that, the tube blank is positioned in the container of the extrusion press and pressed over a mandrel through a die to the respective outer or inner diameter.
• the extruded tube is subjected to a recovering or recrystallizing annealing process in a reducing atmosphere or a vacuum at a temperature T of 700° C. ⁇ T ⁇ 1600° C. If the temperature goes below the lower limit, the stress reduction is too little. At a temperature greater than 1600° C., grain coarsening occurs.
• the extruded tube is machined on the outer side of the tube, the end faces and advantageously the inner side of the tube.
• the molybdenum tube produced in this way is connected to a supporting tube of a non-magnetic material.
• the outer diameter of the supporting tube corresponds approximately to the inner diameter of the molybdenum tube. Furthermore, the supporting tube reaches beyond the respective ends of the molybdenum tube. Copper alloys, austenitic steels, titanium or titanium alloys are to be mentioned as particularly suitable materials for the supporting tube.
• Suitable as connecting methods are both those methods which lead to a material bond and those which lead to a form-fitting connection.
• the molybdenum tube blank is co-extruded with a blank of the supporting tube.
• the production of the molybdenum tube is in this case again based on a metal powder with an average particle size according to Fisher of 0.5-10 ⁇ m.
• the tube blank is once again produced by cold-isostatic pressing of the metal powder in a flexible mold using a core and sintering in the range from 1600° C. to 2500° C.
• the tube blank is machined. Inside the tube blank, a supporting tube blank of an austenitic steel is positioned. At one or both end pieces of the tube blank, a steel tube end piece is joined on by a mechanical connection (for example a screwed or bolted connection).
• the tube end piece has in this case approximately the inner diameter and outer diameter of the tube blank.
• the thickness of the tube end piece preferably lies in the range from 10 to 100 mm.
• Fastened in turn to the tube end piece is the supporting tube blank. This fastening preferably takes place by a welded connection.
• the outer diameter of the supporting tube blank may correspond approximately to the inner diameter of the molybdenum tube blank or else be chosen such that a defined gap is produced between the molybdenum tube blank and the supporting tube blank.
• a steel powder preferably of austenitic steel, is filled into this defined gap.
• the composite tube body produced in this way is heated to a forming temperature of from 900° C. to 1350° C. Only tubular targets of molybdenum alloys which can be appropriately deformed at this temperature can be produced in this way. A higher extrusion temperature cannot be chosen on account of the steel.
• the composite tube blank produced in this way is extruded over a mandrel (co-extrusion), whereby a composite tube is produced.
• this may be followed by carrying out an annealing process, the annealing temperature preferably lying around 800° C. to 1300° C.
• a gap width of from 3 mm to 20 mm proves to be advantageous.
• glass powder as a lubricant achieves the effect of an outstanding surface of the tubular target in the case of both extrusion and co-extrusion, whereby the machining can be reduced to a minimum. Furthermore, this ensures that the tubular target is free from pores and also free from grain boundary cracks.
• the range from 40 to 80% has been found to be an advantageous degree of forming during the extrusion process. The degree of forming is in this case determined as follows: ((initial cross section before extrusion less cross section after extrusion)/initial cross section) ⁇ 100.
• the extruded tube may be straightened. This can be performed by a forging process over a mandrel.
• the wall thickness over the length of the molybdenum tube or composite tube can also be varied by a subsequent forging process.
• the wall thickness can in this case be advantageously made thicker in the region of the tube ends.
• the region of the tube ends is also the region of greatest erosion during use.
• the surface quality and the dimensional tolerances are set by appropriate machining.
• the oxygen content in the molybdenum alloy is ⁇ 50 ⁇ g/g, preferably less than 20 ⁇ g/g
• the density is greater than 99% of the theoretical density, preferably greater than 99.8% of the theoretical density
• the average grain size transversely to the axial direction is less than 100 ⁇ m, preferably less than 50 ⁇ m.
• the average grain size is determined transversely to the axial direction because in the case of an deformed, non-recrystallized microstructure, the grains are stretched in the axial direction and consequently an exact determination of the grain size in the axial direction is made more difficult.
• molybdenum alloys which contain 0.5 to 30% by weight of V, Nb, Ta, Cr and/or W are also particularly suitable.
• MoO 3 powder was reduced in a two-stage reduction process at 600 and 1000° C. to give Mo metal powder with a grain size of 3.9 ⁇ m.
• a steel mandrel with a diameter of 141 mm was positioned in the centre. The molybdenum metal powder was filled into the intermediate space between the steel core and the rubber wall.
• the green compact had a density of 64% of the theoretical density.
• the outer diameter was approximately 300 mm.
• the green compact produced in this way was sintered in an indirect sintering furnace at a temperature of 1900° C.
• the sintered density was 94.9% of the theoretical density.
• the tube blank was machined on all sides, the outer diameter being 243 mm, the inner diameter 123 mm and the length 1060 mm.
• the extrusion took place on a 2500 t indirect extrusion press.
• the tube blank was heated to a temperature of 1100° C. in a gas-heated rotary hearth kiln.
• the lambda value was in this case set such that the atmosphere was slightly reducing, whereby oxidation of the molybdenum was prevented.
• the extruded blank was inductively heated to a temperature of 1250° C. and rolled in a loose fill of glass powder, so that glass powder adhered to the outside on all sides.
• a supporting tube of an austenitic steel with a wall thickness of 6 mm was positioned in the extruded tube. This assembly was straightened over a mandrel on a three-jaw forging machine at a temperature of 500° C. and slightly deformed, whereby a bond between the molybdenum tube and the supporting tube was produced.

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• Chemical & Material Sciences (AREA)
• Mechanical Engineering (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Materials Engineering (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Composite Materials (AREA)
• Powder Metallurgy (AREA)
• Physical Vapour Deposition (AREA)
• Extrusion Of Metal (AREA)
• Electrodes Of Semiconductors (AREA)

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• 2005
  • 2005-10-14 AT AT0069905U patent/AT8697U1/de not_active IP Right Cessation
• 2006
  • 2006-09-19 TW TW102109242A patent/TWI498439B/zh active
  • 2006-09-19 TW TW095134557A patent/TWI403599B/zh active
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  • 2006-10-05 JP JP2007539418A patent/JP4896032B2/ja active Active
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  • 2006-10-05 WO PCT/AT2006/000406 patent/WO2007041730A1/de active Application Filing
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  • 2006-10-05 CN CN2006800002725A patent/CN101052740B/zh active Active
  • 2006-10-05 EP EP06790256A patent/EP1937866B1/de active Active
  • 2006-10-05 ES ES06790256T patent/ES2356773T3/es active Active
  • 2006-10-05 RU RU2006141645/02A patent/RU2353473C2/ru not_active IP Right Cessation
  • 2006-10-16 US US11/581,698 patent/US20070086909A1/en not_active Abandoned
• 2008
  • 2008-03-10 ZA ZA200802221A patent/ZA200802221B/xx unknown
• 2011
  • 2011-12-02 US US13/310,147 patent/US8900340B2/en active Active
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