TW201350598A - Method of manufacturing iron-cobalt alloy target - Google Patents

Abstract

This invention relates to a method of manufacturing an iron-cobalt alloy target, the manufacturing method comprising the following steps: (a) providing an iron metal and at least one alloy element; (b) performing a vacuum smelting step to smelt the iron metal and the at least one alloy element into an iron alloy solution; (c) atomizing the iron alloy solution to form a plurality of iron alloy micro-droplets; (d) cooling the iron alloy micro-droplets to form an iron alloy powder; (e) performing a dry powder-mixing step to fully mix the iron alloy powder with a cobalt metal powder, so as to form an iron alloy-cobalt alloy composite powder; and (f) shaping and densifying the iron alloy-cobalt alloy composite powder to form the iron-cobalt alloy target. This invention can make an iron-cobalt alloy target without composition segregation and with high texture uniformity, increase target yield rate and reduce target manufacturing costs.

Description

Method for manufacturing iron-cobalt alloy target

The present invention relates to a method for producing a target, and more particularly to a method for producing an iron-cobalt alloy target.

In order to improve the magnetic flux penetration (Pass Through Flux, PTF) of a ferromagnetic metal alloy target such as a cobalt (Co) group, an iron (Fe) group, and a nickel (Ni) group, the target manufacturing method mainly includes the following "Magnetic pulse-assisted casting of metal alloys & metal alloys produced" as disclosed in U.S. Patent Application Publication No. US-A-2008/0145692, the disclosure of which is incorporated herein by reference. ), which is wound around a casting mold (Magnetic Core Assembly), and a DC or alternating current is passed into the core assembly during the solidification of the molten ferromagnetic metal alloy into the mold to allow the mold to be placed inside the mold. A pulse or oscillating magnetic field is generated until the ferromagnetic metal alloy is completely solidified. The above method can improve the shape of the cast structure and increase the magnetic flux of the ferromagnetic metal alloy target. However, this method must install a magnetic core assembly (electromagnetic coil) in the vacuum casting cavity, which will make the manufacturing equipment cost. Significantly improved, and the resulting alloy target still exhibits a dendritic crystalline conventional cast structure, which is not conducive to the uniformity of the sputtering process.

The second manufacturing method is "Magnetic sputter targets manufactured using directional solidification" disclosed in US Patent Publication No. US2007/0169853, which utilizes Directional Solidification. To improve the uniformity of the cast structure and increase the PTF value of the target. However, the so-called directional solidification technique is a casting technique in which the molten alloy is guided to solidify in the opposite direction to the heat flow and in accordance with the planned crystal orientation by controlling the direction of the heat flow. The target is still a traditional foundry structure and is still not conducive to the uniformity of the sputtering process.

In view of this, it is necessary to provide an innovative and progressive method of manufacturing an iron-cobalt alloy target to solve the above problems.

The invention provides a method for manufacturing an iron-cobalt alloy target, comprising the steps of: (a) providing an iron metal and at least one alloying element; (b) performing a vacuum melting step to the iron metal and the at least one alloying element Melting into a ferroalloy solution; (c) atomizing the ferroalloy solution to form a plurality of ferroalloy microdroplets; (d) cooling the ferroalloy microdroplets to form an iron alloy powder; (e) performing a dry mixing step And the iron alloy powder is sufficiently mixed with a cobalt metal powder to form an iron alloy-cobalt metal composite powder; and (f) forming and densifying the iron alloy-cobalt metal composite powder to form the iron cobalt alloy Target.

The method for producing the iron-cobalt alloy target of the present invention can produce an iron-cobalt alloy target without component segregation and fine uniformity of the structure without using complicated and expensive process equipment. Compared with the traditional powder metallurgy process and casting process, the magnetic permeability flux (PTF) of the iron-cobalt alloy target prepared by the invention can be increased by 40% to 90%. In addition, the present invention utilizes a mold of a specific shape to form a target of a specific shape, so that the target does not need to remove the head, tailings and trim. Compared with the traditional casting process, the invention can greatly improve the target yield (up to 95%) Upper) and lower target manufacturing costs, therefore, it is very suitable for the production of high-grade circular sputtering targets used in thin film sputtering processes.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a flow chart showing the manufacturing method of the iron-cobalt alloy target of the present invention. Referring to step S11 of FIG. 1, an iron metal and at least one alloying element are provided. In this embodiment, the iron metal and the at least one alloying element may be in the form of a block or a strip, and the purity of the iron metal and the at least one alloying element is greater than 99.5%. In addition, the weight percentage of the iron metal is greater than 15%, and the at least one alloying element includes at least one of the following: tantalum (Ta), vanadium (V), niobium (Nb), chromium (Cr), molybdenum (Mo), Aluminum (Al), boron (B), copper (Cu), zinc (Zn), zirconium (Zr) and nickel (Ni), preferably, the sum of the weight percentages of the at least one alloying element is not more than 35%.

Further, before step S11, the following steps may be first performed: first, removing the oxide of the iron metal and the surface of the at least one alloy element and the contaminant by using a hydrochloric acid solution, in the embodiment, the hydrochloric acid solution The volume concentration is 95% or more; after that, the iron metal and the hydrochloric acid solution on the surface of the at least one alloying element are removed by deionized water; finally, the iron metal and the at least one alloying element are dried.

Referring to step S12, a vacuum melting step is performed to melt the iron metal and the at least one alloying element into a ferroalloy solution. In this embodiment, the iron metal and the at least one alloying element are smelted in a high temperature vacuum environment, and the high temperature vacuum environment is selected from the group consisting of a vacuum induction melting furnace and a vacuum arc melting furnace. Preferably, the vacuum melting temperature is from 1650 ° C to 1750 ° C, and the vacuum melting vacuum is 10 ^-3 torr (torr) or less.

Referring to step S13, the iron alloy solution is atomized to form a plurality of iron alloy microdroplets. In the present embodiment, the iron alloy solution is atomized by a high pressure inert gas spray method. Preferably, the inert gas system is argon (Ar) and the inert gas has a spray pressure of 20 to 30 atmospheres (atm).

Referring to step S14, the ferroalloy microdroplets are cooled to form an iron alloy powder. In this embodiment, the ferroalloy microdroplets are cooled by a nitrogen sparging method. Alternatively, in another embodiment, the ferroalloy microdroplets can be cooled in a natural cooling manner.

Referring to step S15, a dry mixing step is performed in which the iron alloy powder is thoroughly mixed with a cobalt metal powder to form an iron alloy-cobalt metal composite powder. In the present embodiment, the cobalt metal powder has a purity of more than 99.9% and a weight percentage of more than 20%, and preferably, the dry mixing powder has a mixing time of 4 to 8 hours.

Referring to step S16, the ferroalloy-cobalt metal composite powder is formed and densified to form the iron-cobalt alloy target. In this embodiment, the forming and densification process is selected from the group consisting of a hot press process and a hot press process. Preferably, the molding and densification process temperature is from 750 ° C to 1100 ° C, and the molding and densification process time is from 1 to 4 hours.

The invention is illustrated by the following examples, which are not intended to be limited to the scope of the invention.

Invention Example 1:

Inventive Example 1 is exemplified by making an alloy target of 50% iron-26% cobalt-21% chromium-3% boron (% by weight, wt%). First in the raw material preparation step, follow For example, 50% iron-21% chromium-3% boron weight percentage, iron pieces, chromium blocks and boron particles with a purity of 99.5% or more are prepared, and the iron and chromium blocks are placed at a volume concentration of 95% or more. In the hydrochloric acid solution, the oxide and oil on the surface of the iron block and the chromium block are removed by ultrasonic vibration, and then placed in deionized water to remove the hydrochloric acid solution remaining on the surface of the iron block and the chromium block by ultrasonic vibration. , dry iron and chrome.

In the vacuum melting step, the acid-washed iron, chromium and boron particles are placed in a crucible of a vacuum induction melting furnace and vacuumed, and the vacuum induction melting is performed after the vacuum reaches 10 ^-3 torr or less. The furnace starts to heat up to 1750 ° C, so that the iron, chromium and boron particles in the crucible are melted and held for 10 minutes to ensure that all elements can be completely melted, thereby forming an iron-chromium-boron alloy soup. And the molten iron-chromium-boron alloy solution component is more uniformly mixed under the stirring of the magnetic field provided by the induction coil.

In the atomization step, the molten iron-chromium-boron alloy soup having a uniform composition is poured out from the crucible of the vacuum induction melting furnace, and the iron is sprayed with 28 atmospheres (atm) of high pressure argon gas. The chromium-boron alloy soup is atomized into a plurality of iron-chromium-boron alloy microdroplets.

In the cooling step, the iron-chromium-boron alloy microdroplets are sprayed with nitrogen gas in the cavity of the vacuum induction melting furnace to accelerate the cooling of the iron-chromium-boron alloy microdroplets. An iron-chromium-boron alloy powder having a uniform composition can be obtained.

In the dry mixing, forming and densification steps, 74% of the iron-chromium-boron alloy powder is taken as a percentage by weight, and the 26% cobalt metal powder is dry-mixed without solvent. Mix well for 4 hours. Next, will The mixed composite powder is placed in a graphite mold, and the composite powder is formed and densified by hot pressing, and after being held at 1000 ° C for 2 hours, the composite powder can be pressed to a relative density of more than 99%. And iron-cobalt-chromium-boron alloy target without component segregation.

Figure 2 shows a photomicrograph of the iron-cobalt-chromium-boron alloy target produced by a conventional casting process. Fig. 3 is a photograph showing the microstructure of an iron-cobalt-chromium-boron alloy target obtained in Inventive Example 1. Compared with the microstructure of the target produced by the conventional casting process (Fig. 2), it is apparent that the microstructure of the iron-cobalt-chromium-boron alloy target of the inventive example 1 (Fig. 3) is quite detailed. And even. The iron-cobalt-chromium-boron alloy target of Inventive Example 1 was subjected to a Magnetic Through Flux (PTF) measurement according to the ASTM F1761-00 specification, and the measurement results showed that the PTF value of the inventive example 1 was more than that of the casting. The process has increased by 50%.

Invention Example 2:

Inventive Example 2 was exemplified by a 60% cobalt-23% iron-9% bismuth-7% zirconium-1% chromium (% by weight) alloy target. First, in the raw material preparation step, according to the weight percentage of 23% iron-9% 钽-7% zirconium-1% chromium, iron pieces, bismuth pieces, zirconium grains and chromium blocks having a purity of 99.9% or more are prepared, and the iron pieces are prepared. The crucible, zirconium and chromium blocks are placed in a hydrochloric acid solution with a volume concentration of more than 95%, and the oxides and oils on the surface of the iron, chopped, zirconium and chromium blocks are removed by ultrasonic vibration, and then placed. In the ionized water, the hydrochloric acid solution remaining on the surface of the iron block, the bracts, the zirconium grains and the chromium block is removed by ultrasonic vibration, and then the iron block, the bracts, the zirconium grains and the chromium block are dried.

In the vacuum melting step, the acid-washed iron, bismuth, zirconium and chromium blocks are placed in a crucible of a vacuum induction melting furnace and vacuumed until the vacuum reaches 10 ^-3 torr or less. The vacuum induction melting furnace starts to heat up to 1650 ° C, so that the iron, bismuth, zirconium and chromium blocks in the crucible are melted and held for 10 minutes to ensure that all elements can be completely melted, thereby forming an iron-bismuth. - Zirconium-chromium alloy soup solution, and the molten iron-钽-zirconium-chromium alloy soup liquid component is more uniformly mixed under the stirring of the magnetic field provided by the induction coil.

In the atomization step, the molten iron-cerium-zirconium-chromium alloy soup having a uniform composition is poured out from the crucible of the vacuum induction melting furnace, and is sprayed with high pressure argon gas at 20 atmospheres (atm). The iron-bismuth-zirconium-chromium alloy soup solution is atomized into a plurality of iron-niobium-zirconium-chromium alloy microdroplets.

In the cooling step, in the cavity of the vacuum induction melting furnace, waiting for the iron-钽-zirconium-chromium alloy micro-droplets to be naturally cooled, thereby obtaining a uniform composition of iron-钽-zirconium-chromium alloy powder. .

In the dry mixing, forming and densification steps, 40% of the iron-cerium-zirconium-chromium alloy powder is taken as a percentage by weight, and is dry mixed with 60% of the cobalt metal powder without solvent. The powder is thoroughly mixed for 6 hours. Then, the mixed composite powder is sealed with stainless steel (Canning), and the composite powder is formed and densified by heat equalization, and after holding at 760 ° C for 3 hours, the composite powder can be pressed. A cobalt-iron-rhodium-zirconium-chromium alloy target having a relative density greater than 99% and no component segregation.

Figure 4 shows a photomicrograph of a cobalt-iron-niobium-zirconium-chromium alloy target prepared by a conventional casting process. Fig. 5 is a photograph showing the microstructure of a cobalt-iron-yttrium-zirconium-chromium alloy target obtained in Inventive Example 2. Compared with the microstructure of the target produced by the conventional casting process (Fig. 4), it is apparent that the microstructure of the cobalt-iron-rhodium-zirconium-chromium alloy target of the inventive example 2 (Fig. 5) Quite detailed and even. according to The ASTM F1761-00 specification conducts a magnetic flux-through-flux (PTF) measurement of the cobalt-iron-niobium-zirconium-chromium alloy target of Inventive Example 2, and the measurement results show that the PTF value of the inventive example 2 is higher than that of the casting process. 90%.

In addition, the present invention utilizes a mold of a specific shape to form a target of a specific shape, so that the target does not need to remove the head, tailings and trim. Compared with the traditional casting process, the invention can greatly improve the target yield (up to 95%) and reduce the manufacturing cost of the target. Therefore, it is very suitable for use in the film sputtering process of the magnetic recording industry, the optoelectronic industry or the semiconductor industry. The production of high-grade circular sputter targets.

The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the scope of the present invention. The scope of the invention should be as set forth in the appended claims.

1 is a flow chart showing a method for producing an iron-cobalt alloy target of the present invention; FIG. 2 is a photomicrograph showing a microstructure of an iron-cobalt-chromium-boron alloy target obtained by a conventional casting process; and FIG. 3 is a view showing the first embodiment of the invention. Photomicrograph of the prepared iron-cobalt-chromium-boron alloy target; Figure 4 shows the photomicrograph of the cobalt-iron-cerium-zirconium-chromium alloy target prepared by the conventional casting process; 5 shows a photomicrograph of a cobalt-iron-yttrium-zirconium-chromium alloy target obtained in Inventive Example 2.

Claims (18)

A method for manufacturing an iron-cobalt alloy target, comprising the steps of: (a) providing an iron metal and at least one alloying element; and (b) performing a vacuum melting step of melting the iron metal and the at least one alloying element into a ferroalloy a solution; (c) atomizing the ferroalloy solution to form a plurality of ferroalloy microdroplets; (d) cooling the ferroalloy microdroplets to form an iron alloy powder; (e) performing a dry mixing step, The iron alloy powder is sufficiently mixed with a cobalt metal powder to form an iron alloy-cobalt metal composite powder; and (f) the iron alloy-cobalt metal composite powder is formed and densified to form the iron cobalt alloy target. The method of claim 1, wherein the step (a) further comprises the steps of: (a1) removing the iron metal and the oxides and contaminants on the surface of the at least one alloying element by using a hydrochloric acid solution; (a2) removing The iron metal and the hydrochloric acid solution on the surface of the at least one alloying element; and (a3) drying the iron metal and the at least one alloying element. The method of claim 2, wherein the hydrochloric acid solution of the step (a1) has a volume concentration of 95% or more. The method of claim 2, wherein the step (a2) removes the iron metal and the hydrochloric acid solution on the surface of the at least one alloy element with deionized water. The method of claim 1, wherein the iron metal of the step (a) and the at least one alloying element have a purity greater than 99.5%. The method of claim 1, wherein the at least one alloying element of the step (a) comprises at least one of the following: tantalum (Ta), vanadium (V), niobium (Nb), chromium (Cr), molybdenum (Mo), aluminum. (Al), boron (B), copper (Cu), zinc (Zn), zirconium (Zr), and nickel (Ni). The method of claim 1, wherein the weight percentage of the iron metal in the step (a) is greater than 15%, and the sum of the weight percentages of the at least one alloying element is not more than 35%. The method of claim 1, wherein the step (b) is to smelt the iron metal and the at least one alloying element in a high temperature vacuum environment selected from the group consisting of a vacuum induction melting furnace and a vacuum arc melting. furnace. The method of claim 1, wherein the vacuum melting temperature of step (b) is from 1650 ° C to 1750 ° C. The method of claim 1, wherein the vacuum melting degree of the step (b) is 10 ^-3 torr or less. The method of claim 1, wherein the step (c) atomizes the ferroalloy solution by a high pressure inert gas spray. The method of claim 11, wherein the inert gas system is argon (Ar). The method of claim 11, wherein the inert gas has a spray pressure of 20 to 30 atmospheres (atm). The method of claim 1, wherein the step (d) cools the ferroalloy microdroplets by nitrogen sparging. The method of claim 1, wherein the step (d) cools the ferroalloy microdroplets in a natural cooling manner. The method of claim 1, wherein the forming and densifying process of the step (f) is selected from the group consisting of a hot pressing process and a hot pressing process. The method of claim 1, wherein the molding and densification process temperature of the step (f) is 750 ° C to 1100 ° C. The method of claim 1, wherein the molding and densification process time of the step (f) is 1 to 4 hours.