CN101319303A - Method for manufacturing sputtering target material containing noble metal - Google Patents

Abstract

A method for manufacturing a sputtering target containing precious metals comprises the steps of preparation, surface treatment, fusion casting, hot working and annealing. Preparing each metal ingot in the preparation step, performing the surface treatment step to remove surface oxides and oil stains, then performing vacuum melting on each metal ingot according to a specific weight composition ratio in the melting and casting step to obtain an alloy melt, solidifying and forming the alloy melt into a casting blank in a metal casting mold, simultaneously utilizing electric arc heating to maintain the surface of the alloy melt in a high-temperature molten state, and finally simultaneously cooling the whole surface of the alloy melt without gradually cooling from the outer edge to the center, so that the defect of shrinkage cavity due to bubbling can be effectively eliminated, and the hot working and annealing steps are matched to manufacture the sputtering target material with the material yield of more than 90% and the fine and uniform structure components.

Description

Preparation method of noble metal-containing sputtering target

technical field

The invention relates to a method for manufacturing an alloy sputtering target material, in particular to a method for manufacturing a noble metal-containing sputtering target material used in a thin film sputtering process.

Background technique

The hard disk is the main component used to store a large amount of data in modern times, and the data is mainly stored in the magnetic thin film recording layer on the hard disk, and the main component is a cobalt (Co)-based alloy material containing platinum (Pt) noble metal. The magnetic thin film recording layer is coated on the hard disk by a sputtering process, so an alloy target for sputtering is required.

The sputtering process refers to the use of plasma to ion-bomb the alloy target for sputtering, and use the momentum transfer of the ion bombardment to knock out the atoms on the surface of the alloy target in the form of gas molecules. , nucleation and other processes, grow on the hard disk to form a magnetic thin film recording layer.

Since the field of hard disk technology covers cutting-edge technologies such as electronics, semiconductors, laser optics, precision machinery, and advanced physical chemistry, the requirements for alloy targets for sputtering are relatively high, and the traditional atmospheric melting and casting process cannot be used to cast targets. . In addition, since the content of platinum (Pt) noble metal contained in the target material for the recording layer of the hard disk is often as high as 30wt%, how to choose an appropriate process to increase the yield of the target blank and avoid the waste of platinum (Pt) noble metal becomes a problem. It is a matter of considerable concern to manufacturers of target materials containing precious metals, and it is also where the industry's competitiveness lies.

The technical means disclosed in the U.S. Patent No. 6,797,137 is to first produce a cheaper cobalt chromium boron (CoCrB) master alloy with vacuum melting and powder spraying equipment, and then use ball milling to mix the powder of the master alloy with platinum. (Pt) noble metal powders are fully mixed, and finally subjected to hot isostatic pressure (Hot Isostatic Pressure, HIP) process to produce high-purity cobalt-chromium-platinum-boron (CoCrPtB) targets, which can be used in hard disks The thin-film sputtering process of the magnetic recording layer, however, adopts a ball milling method, which is prone to uneven powder mixing and uneven target material composition, thereby reducing the quality of subsequent sputtering.

Another existing sputtering target manufacturing method is to use vacuum induction melting (Vacuum Induction Melting, VIM) process and vacuum arc refining (Vacuum Arc Remelting, VAR) process to prepare high-purity cobalt-containing chromium (CoCr) alloy target. Its characteristic is to use the ingot of vacuum induction melting (VIM) as the negative electrode, and the copper crucible with the positive electrode to carry out vacuum arc refining (VAR) to obtain high-quality casting embryos. However, more than 40% of riser shrinkage defects in VIM ingots must be removed before they can be used as VAR electrodes, so the overall yield must be lower than 60%. In addition, the equipment and manufacturing costs of the vacuum powder spraying equipment, hot isostatic pressing equipment, vacuum induction melting equipment, and vacuum arc refining equipment used in the above two existing target manufacturing methods are quite expensive and invisible. It also increases the production cost of the target.

Therefore, how to improve the uniformity and fineness of the composition of the alloy target and the material yield, so as to effectively reduce the production cost and improve the market competitiveness, has become an urgent research direction for sputtering alloy target manufacturers.

Contents of the invention

The object of the present invention is to provide a method for producing a noble metal-containing sputtering target, which has the advantage of high yield, and the produced sputtering target not only has high purity, but also has a fine structure and uniform composition.

In order to achieve the above object, the manufacturing method of the noble metal-containing sputtering target of the present invention includes a preparation step, a surface treatment step, a casting step, a thermal processing step and an annealing step.

The preparation step is to prepare a high-purity substrate made of magnetic metal elements and a high-purity precious metal ingot, and the surface treatment step is to remove surface oxides and oil stains from the substrate and the precious metal ingot, The melting and casting step is to take a precious metal ingot with a weight percentage of less than 50%, cooperate with a balanced amount of base material, carry out vacuum melting, then pour the alloy melt obtained by vacuum melting into a metal casting mold, and cool the metal casting mold to make the alloy The melt is solidified and formed into a billet. When the alloy melt is poured into the metal mold, the surface of the alloy melt in the metal mold is kept in a high-temperature molten state by means of electric arc heating until the pouring process is completed, and then the The thermal processing step is to perform plastic deformation on the cast billet, and then perform the annealing step to perform annealing on the cast billet to obtain a sputtering target material containing precious metals for use in the sputtering process.

In the manufacturing method of the noble metal-containing sputtering target according to the present invention, the substrate prepared in the preparation step is selected from the group consisting of iron, cobalt, nickel and a combination thereof.

The preparation method of the noble metal-containing sputtering target according to the present invention, the noble metal ingot prepared in the preparation step is selected from the group consisting of platinum, palladium, gold, silver, rhodium, iridium, ruthenium, osmium and these a combination.

According to the manufacturing method of the noble metal-containing sputtering target in the present invention, the purity of the base material and the noble metal ingot prepared in the preparation step is above 99.95% by weight.

The manufacturing method of the noble metal-containing sputtering target according to the present invention, the preparation step also prepares a chromium metal ingot with a purity of more than 99.95% by weight, the base material is a cobalt metal ingot, and the melting and casting step is to prepare the cobalt metal Ingots, chromium metal ingots and precious metal ingots are vacuum smelted with 45% to 60% by weight of cobalt, 5% to 27% by weight of chromium, and 25% to 45% by weight of precious metals to obtain alloy melts .

The preparation method of the noble metal-containing sputtering target according to the present invention, the surface treatment step is to place the base material, the chromium metal ingot, and the noble metal ingot in an acidic solution, and remove surface oxides and oil stains by means of ultrasonic vibration, Then it is placed in deionized water, and the acidic solution remaining on the surface is also removed by ultrasonic vibration, and then dried.

In the manufacturing method of the noble metal-containing sputtering target according to the present invention, the acid solution used in the surface treatment step is selected from the group consisting of nitric acid, phosphoric acid, hydrochloric acid, hydrofluoric acid and aqua regia.

The manufacturing method of the noble metal-containing sputtering target according to the present invention, the manufacturing method also includes a turning step, the sputtering target obtained after the annealing step is finished, after slicing and turning the surface oxide layer, it is used for sputtering Plating process use.

The manufacturing method of the noble metal-containing sputtering target according to the present invention, the working temperature of the thermal processing step is between 0.75 and 0.85 times the melting point temperature of the casting billet, and the annealing temperature of the annealing step is lower than the working temperature of the thermal processing step Between 100°C and 300°C, the annealing time is between 1 and 2 hours.

In the manufacturing method of the noble metal-containing sputtering target according to the present invention, in the melting and casting step, during vacuum smelting, less than 5% by weight of boron is added.

In the manufacturing method of the noble metal-containing sputtering target according to the present invention, the vacuum melting method in the melting and casting step is vacuum induction melting.

In the manufacturing method of the noble metal-containing sputtering target according to the present invention, the vacuum melting method in the melting and casting step is vacuum arc melting.

In the manufacturing method of the noble metal-containing sputtering target according to the present invention, the thermal processing step adopts hot forging.

In the manufacturing method of the noble metal-containing sputtering target according to the present invention, the thermal processing step adopts hot rolling.

In the manufacturing method of the noble metal-containing sputtering target according to the present invention, the annealing step is carried out under the atmosphere.

In the manufacturing method of the noble metal-containing sputtering target of the present invention, the annealing step is carried out under a protective atmosphere.

In the manufacturing method of the noble metal-containing sputtering target according to the present invention, the protective atmosphere used in the annealing step is argon.

The efficacy of the present invention lies in that while the alloy melt is solidified and formed into a casting blank in a metal casting mold, the surface of the alloy melt is kept in a high-temperature molten state by means of arc heating simultaneously, and finally the entire surface of the alloy melt is cooled at the same time without It will gradually cool from the outer edge to the center, so it can effectively eliminate the pitting and shrinkage defects, and cooperate with the thermal processing and annealing steps to obtain a sputtering target with fine structure and uniform composition.

Description of drawings

FIG. 1 is a flow chart illustrating a preferred embodiment of the method for manufacturing a noble metal-containing sputtering target according to the present invention.

FIG. 2 is a microstructure diagram illustrating the sputtering target made by the embodiment method 1 using the weight composition ratio of 50wt% cobalt, 8wt% chromium and 42wt% platinum, and its grain size is less than 150 μm.

Fig. 3 is a microstructure diagram illustrating the sputtering target made of 54wt% cobalt, 14wt% chromium, 31wt% platinum and 1wt% boron in embodiment 2, and its grain size is about 80 μm.

Detailed ways

The manufacturing method of the noble metal-containing sputtering target of the present invention will be described in detail below through preferred embodiments and accompanying drawings.

Referring to Fig. 1, the preferred embodiment of the manufacturing method 1 of noble metal-containing sputtering target of the present invention comprises a preparation step 11, a surface treatment step 12, a casting step 13, a thermal processing step 14, an annealing step 15 and Step 16 for one vehicle.

The preparation step 11 is to prepare a high-purity base material made of magnetic metal elements, a high-purity chromium metal ingot and a high-purity precious metal ingot, and the purity of the base material, chromium metal ingot, and precious metal ingot is All as high as 99.95wt% or more.

In this embodiment, the base material prepared in the preparation step 11 is a cobalt (Co) metal ingot, of course it can also be an iron (Fe) metal ingot, or a nickel (Ni) metal ingot, or iron, cobalt, nickel An alloy ingot in which at least two of the three metal elements are mixed. As for the composition of the precious metal ingot is platinum (Pt) metal element, of course, it can also be palladium (Pd), gold (Au), silver (Ag), rhodium (Rh), iridium (Ir), ruthenium (Ru), osmium (Os) and other types of noble metal elements, or an alloy of at least two metal elements mixed therein, the above metal elements are all easily imagined and replaced by those of ordinary skill in the art, so it should not be limited to the description of this embodiment.

The surface treatment step 12 is to place the cobalt metal ingot, chromium metal ingot, and precious metal ingot in an acidic solution, remove surface oxides and oil stains by ultrasonic vibration, and then place them in deionized water, and also use ultrasonic vibration Remove the acidic solution remaining on the surface by means of a method, and then dry it.

In this embodiment, the acidic solution is a nitric acid solution with a volume concentration of more than 95%. Of course, phosphoric acid, hydrochloric acid, hydrofluoric acid, or other types of acidic solutions such as aqua regia can be used to remove surface oxides and oil stains. Therefore, it should not be limited by the description of this embodiment.

In the melting and casting step 13, the cobalt metal ingot, chromium metal ingot and precious metal ingot are mixed with 45wt%-60wt% cobalt, 5wt%-27wt% chromium, 25wt%-45wt% precious metal, and adding 0-5wt% Boron element is vacuum smelted to obtain alloy melt, and then the alloy melt is poured into a metal mold (generally a pure copper mold with high thermal conductivity) with a cooling circulation waterway, and cooled by cooling water The circulating waterway flows continuously to cool the metal mold so that the alloy melt is solidified and formed into a billet. When the alloy melt is poured into the metal mold, the alloy melt located in the metal mold is simultaneously heated by an arc. The surface remains hot and molten until the end of the pouring process.

Then carry out the hot working step 14 to carry out plastic deformation operation (generally hot forging or hot rolling) to form the predetermined shape, and then carry out the annealing step 15 to carry out annealing operation to the cast billet to obtain The sputtering target material containing noble metal, wherein, the working temperature of the thermal processing step 14 is between 0.75 to 0.85 times the melting point temperature of the cast billet, and the annealing temperature of the annealing step 15 is lower than the working temperature of the thermal processing step 14 by 100°C ℃～300℃, the annealing time is between 1～2 hours.

Finally, the machining step 16 is performed, and the sputtering target obtained after the annealing step 15 is sliced and the surface oxide layer is removed by machining, and then used in the sputtering process.

The following are the two implementation methods obtained by adopting the steps described in this embodiment, according to different alloy compositions, and the different working conditions of the thermal processing step 14 and the annealing step 15, to clearly illustrate the present invention The production method 1 of the noble metal-containing sputtering target, and the effects that can be achieved by the production method 1.

Implementation method 1

In this implementation method, the production of a cobalt-chromium-platinum (CoCrPt) alloy sputtering target is taken as an example. First, in the preparation step 11, cobalt metal ingots, chromium metal ingots, and platinum metal ingots with a purity of more than 99.95 wt% are prepared, and then Perform the surface treatment step 12, place the above three types of metal ingots in a nitric acid solution with a volume concentration of 95% or more, remove surface oxides and oil stains by ultrasonic vibration, and then place them in deionized water, and also use ultrasonic vibration Remove the nitric acid solution remaining on the surface by means of a method, and then dry it.

Then carry out the melting and casting step 13. The cobalt metal ingot, chromium metal ingot and platinum metal ingot are weighed according to the weight ratio of 50wt% cobalt, 8wt% chromium and 42wt% platinum, and weighed The metal raw material is placed in a vacuum melting furnace, and the alloy melt is obtained by vacuum induction melting (Vacuum Induction Melting, VIM), and then the alloy melt is poured into a pure copper mold with a circulating water channel and high thermal conductivity for cooling. It is formed into a billet by rapid solidification. When the alloy melt is poured into the mold, the surface of the alloy melt in the mold is kept in a high-temperature molten state by means of arc heating simultaneously until the pouring process is completed.

Then carry out the thermal processing step 14, carry out hot forging at 0.85 times the melting point temperature of the billet (i.e. 1200° C.), to carry out plastic deformation operation to form the billet into a predetermined shape, and then perform the annealing step 15, The billet is annealed at an annealing temperature lower than the hot forging temperature of 300° C. (that is, 900° C.) for 2 hours in the atmosphere to obtain a sputtering target with fine grains and uniform structure components.

Finally, the machining step 16 is performed, and the sputtering target material obtained after the annealing step 15 is sliced and the slight oxide layer on the surface is removed by machining, and then it can be used in the sputtering process.

The yield of the sputtering target produced by the above process is about 94%, and its microstructure is shown in Figure 2. It can be seen from the figure that the structure of the sputtering target is quite fine and uniform, and is equiaxed. Crystal form, the grain size is less than 150μm.

Implementation Method 2

In this implementation method, the production of a cobalt-chromium-platinum-boron (CoCrPtB) alloy sputtering target is taken as an example. First, in the preparation step 11, cobalt metal ingots, chromium metal ingots, and platinum metal ingots with a purity of more than 99.95wt% are prepared. Then carry out the surface treatment step 12, place the above three types of metal ingots in a hydrochloric acid solution with a volume concentration of 95% or more, remove surface oxides and oil stains by means of ultrasonic vibration, and then place them in deionized water. The hydrochloric acid solution remaining on the surface is removed by vibration, and then dried.

Then carry out the melting and casting step 13, the cobalt metal ingot, chromium metal ingot and platinum metal ingot, carry out raw material weighing with the weight composition ratio of 54wt% cobalt, 14wt% chromium and 31wt% platinum, and add 1wt% Boron, placed in a vacuum melting furnace, is subjected to vacuum arc melting (Vacuum Arc Melting, VAM) to obtain an alloy melt, and then the alloy melt is poured into a pure copper mold with a circulating water circuit and high thermal conductivity for cooling , so that the alloy melt is rapidly solidified and formed into a casting billet. When the alloy melt is poured into the mold, the surface of the alloy melt in the mold is kept in a high-temperature molten state by means of arc heating simultaneously until the pouring process is completed.

Then carry out the thermal processing step 14, carry out hot rolling at 0.75 times the melting point temperature of the billet (that is, 1100° C.), so as to perform plastic deformation on the billet to form a predetermined shape, and then perform the annealing step 15 , the billet is annealed at an annealing temperature 100°C lower than the hot rolling temperature (that is, 1000°C) in an argon atmosphere for 1 hour to obtain a sputtering target with fine grains and uniform structure components .

Finally, the machining step 16 is performed, and the sputtering target material obtained after the annealing step 15 is sliced and the slight oxide layer on the surface is removed by machining, and then it can be used in the sputtering process.

The yield of the sputtering target produced by the above process is about 92%, and its microstructure is shown in Figure 3. It can be seen from the figure that the structure of the sputtering target is quite fine and uniform, and the grain size is about is 80 μm.

It can be seen from the above two implementation methods that the manufacturing method 1 of the noble metal-containing sputtering target of the present invention has the following advantages:

(1) The material yield is high, which reduces the production cost of sputtering targets:

In the melting and casting step 13, when the alloy melt is cooled and solidified in the metal casting mold, arc heating is simultaneously used to keep the surface of the alloy melt in a high-temperature molten state without solidification at the same time, until the alloy melt is poured into the process The arc heating will be ended, so that the overall surface of the alloy melt can be cooled at the same time without gradually cooling from the outer edge to the center, effectively eliminating the cavity and shrinkage defects of the billet; in contrast to the existing target material production method, its The alloy ingot made also needs to go through a process of removing holes and shrinkage defects, so the yield of the target product is relatively low. The material yield is as high as over 90%, which can effectively reduce the production cost of the sputtering target material, and through the rapid solidification of the billet, the precipitation of a large number of low-melting crystals can be avoided, thereby improving the hot ductility of the billet.

(2) High purity, fine tissue and uniform composition:

The production method 1 of the present invention uses high-purity metal ingots for smelting in a vacuum environment, so it can avoid the intrusion of impurities and maintain high purity, and then through the melting and casting step 13, thermal processing step 14 and annealing step 15, you can obtain The sputtering target with fine grain and uniform structure will not produce the problem of uneven target composition caused by uneven powder mixing like the general target production method using ball milling mixing process; therefore, the use of the production method of the present invention 1 The sputtering target made has the advantages of high purity, fine structure and uniform composition. For the subsequent sputtering process, it can maintain a very good sputtering quality and is suitable for high-tech industries.

To sum up the above, the manufacturing method 1 of the noble metal-containing sputtering target of the present invention, through the overall surface of the alloy melt is in a state of simultaneous cooling, and will not gradually cool from the outer edge to the center, so the risk of the casting blank can be effectively eliminated. Pore shrinkage defects can improve the yield of sputtering target products and reduce the production cost of sputtering targets; as for the casting billet formed by rapid condensation, it can also avoid a large amount of crystallization with low melting point, thereby improving the casting billet In addition, using high-purity metal ingots to carry out the sputtering target made by the casting step 13, thermal processing step 14, and annealing step 15 also has the advantages of high purity, fine and uniform structure composition, etc., which is conducive to improving The quality of the subsequent sputtering process, so the purpose of the present invention can indeed be achieved.

Claims (17)

1. A method for making a sputtering target containing noble metal, characterized in that, The production method includes: A preparatory step, preparing a high-purity substrate made of magnetic metal elements and a high-purity precious metal ingot; A surface treatment step, the base material and the precious metal ingot are subjected to the operation of removing surface oxides and oil stains; In the first melting and casting step, the base material and the precious metal ingot are vacuum smelted, and the alloy melt obtained by vacuum smelting is poured into a metal mold, and the metal mold is cooled so that the alloy melt is solidified and formed into a billet. While the alloy melt is being poured into the metal casting mold, the surface of the alloy melt in the metal casting mold is kept in a high-temperature molten state by arc heating simultaneously until the pouring process is completed; A thermal processing step, subjecting the casting blank that has completed the melting and casting step to plastic deformation; and An annealing step, annealing the billets after the thermal processing step to obtain a sputtering target material containing precious metals for use in the sputtering process. 2. the preparation method containing noble metal sputtering target material according to claim 1, is characterized in that, The substrate prepared by this preparation step is selected from the group consisting of iron, cobalt, nickel and a combination of these. 3. the preparation method containing precious metal sputtering target material according to claim 2, is characterized in that, The precious metal ingot prepared by this preparation step is selected from the group consisting of platinum, palladium, gold, silver, rhodium, iridium, ruthenium, osmium, and a combination of these. 4. the preparation method containing noble metal sputtering target material according to claim 3, is characterized in that, The purity of the base material and the precious metal ingot prepared in the preparation step is above 99.95% by weight. 5. the preparation method containing noble metal sputtering target material according to claim 4, is characterized in that, The preparation step also prepares a chromium metal ingot with a purity of more than 99.95% by weight, and the base material is a cobalt metal ingot. -60% cobalt, 5%-27% chromium by weight, and 25%-45% precious metal by weight are subjected to vacuum melting to obtain an alloy melt. 6. the preparation method containing precious metal sputtering target material according to claim 5, is characterized in that, The surface treatment step is to place the base material, chromium metal ingot, and precious metal ingot in an acidic solution, remove surface oxides and oil stains by ultrasonic vibration, and then place them in deionized water, and remove them by ultrasonic vibration. The acidic solution remaining on the surface is then dried. 7. the preparation method containing noble metal sputtering target material according to claim 6, is characterized in that, The acidic solution used in the surface treatment step is selected from the group consisting of nitric acid, phosphoric acid, hydrochloric acid, hydrofluoric acid and aqua regia. 8. the preparation method containing noble metal sputtering target material according to claim 7, is characterized in that, The manufacturing method also includes a turning step, the sputtering target obtained after the annealing step is sliced and turned to remove the surface oxide layer, and then used in the sputtering process. 9. the preparation method containing noble metal sputtering target material according to claim 8, is characterized in that, The working temperature of the thermal processing step is between 0.75 and 0.85 times the melting point temperature of the casting billet, the annealing temperature of the annealing step is lower than the working temperature of the thermal processing step between 100°C and 300°C, and the annealing time is between 1 and 300°C. between 2 hours. 10. the preparation method of noble metal-containing sputtering target material according to claim 9, is characterized in that, During the melting and casting step, less than 5% by weight of boron is added during vacuum melting. 11. the preparation method of noble metal-containing sputtering target material according to claim 9, is characterized in that, The vacuum smelting method carried out in the melting and casting step is vacuum induction smelting. 12. the preparation method of noble metal-containing sputtering target material according to claim 9, is characterized in that, The vacuum smelting method carried out in the melting and casting step is vacuum arc smelting. 13. the preparation method of noble metal-containing sputtering target material according to claim 9, is characterized in that, The hot working step is to use hot forging. 14. the preparation method of noble metal-containing sputtering target material according to claim 9, is characterized in that, The hot working step is by hot rolling. 15. the preparation method of noble metal-containing sputtering target material according to claim 9, is characterized in that, The annealing step is performed under atmospheric atmosphere. 16. the preparation method of noble metal-containing sputtering target material according to claim 9, is characterized in that, The annealing step is performed under a protective atmosphere. 17. The method for preparing a noble metal-containing sputtering target according to claim 16, characterized in that, The protective atmosphere used in the annealing step is argon.

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