Tungsten Molybdenum Alloy Sputtering Targets

Tungsten molybdenum alloys can be used at higher temperatures than molybdenum or molybdenum alloys. Molybdenum-tungsten alloy has better conductivity, oxidation resistance and lower coating stress than molybdenum, which meets the requirement of sputtering target material for flat display film production line. Especially the Mo-W alloy with tungsten content of 3.5%25% is more suitable for high quality flat panel display.

As far as the existing technology is concerned, the tungsten molybdenum alloy sputtering target suitable for the production of the sputtering film on the flat panel display, especially the molybdenum-tungsten alloy sputtering target with uniform composition, non-segregation, fine grain and other properties, needs very precise technology to fully meet the requirements of the high quality flat panel display. The tungsten-molybdenum alloy sputtering target can fully meet the requirements of the high quality flat panel display. The material can be manufactured with the following technical scheme:

1)Material preparation: The powder used is molybdenum powder and tungsten powder. The physical properties of the powders are as follows: molybdenum powder has Mo content of more than 99.95%, particle size of 5 microns; tungsten powder has W content of more than 99.95%, particle size of 5 microns.

2)Powder mixing: The molybdenum powder and tungsten powder are weighed according to the following mass percentage ratio. The molybdenum powder content is 96.5% and the tungsten powder content is 3.5%. The two powders are mixed evenly.

3)Mechanical alloying: Mechanical alloying is to synthesize nano-sized molybdenum-tungsten alloy powder by grinding, crushing, cold welding and low temperature solid state reaction under mechanical force. The molybdenum powder and tungsten powder were mixed proportionally and milled in a planetary high energy ball mill. The ball-to-powder ratio was 1:1.5 and the milling time was 48 hours.

4)Moulding: Hollow powdered tungsten molybdenum alloy slab was prepared by filling the above-mentioned mixed molybdenum-tungsten alloy powder in the rubber mould sleeve.

5)Cold isostatic pressing: Hollow powder molybdenum-tungsten alloy slab is pressed by cold isostatic press to obtain solid molybdenum-tungsten alloy slab.

6)Sintering: The solid molybdenum-tungsten alloy slab is put into the intermediate frequency sintering furnace, and hydrogen is introduced into the furnace. The sintering process is in the hydrogen environment.

7)The sintered products were heated at 1600 ℃ for 3 hours, and the slabs were rolled in a hot rolling mill. The slabs were rolled at 1600 ℃ for 3 hours. The slabs of molybdenum-tungsten alloy with 25 mm thickness were obtained by four-pass rolling.

8)Vacuum annealing: Rolled molybdenum-tungsten alloy target is put into the vacuum annealing furnace for vacuum annealing, which is used to eliminate internal stress and prepare for future mechanical processing. The specific annealing process is: holding at 1300 ℃ for 2 hours, then slowly cooling to room temperature.

9)Machining: The annealed molybdenum-tungsten tubes are machined, including milling surface, milling side, wire-cut arc and grinding surface. The surface finish can reach Ra < 0.8 micron, then the product is inspected and packed after cleaning.

After multi-fire multi-pass high temperature rolling and vacuum annealing, the internal grain structure of Mo-W alloy is changed, fibrous grains are formed, and secondary crystallization is produced, which refines the grains, makes the final prepared Mo-W alloy planar target possess higher strength and density, and improves the sputtering coating speed. The uniformity and deposition rate of the film can meet the requirement of sputtering target material for the production line of flat panel display.

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