Method for preparing CoFeB target material by adopting hot isostatic pressing

Abstract

The invention provides a method for preparing a CoFeB target material by adopting hot isostatic pressing, which comprises the following steps of: (1) ball-milling and mixing FeB powder, Co powder and Fe powder according to the formula ratio to obtain mixed powder; and (2) carrying out hot isostatic pressing sintering on the mixed powder obtained in the step (1) to obtain the CoFeB target material. The compact and high-purity CoFeB target material with relatively high magnetic permeability is prepared by adopting a method of carrying out hot isostatic pressing sintering after powder mixing, so that the technological processes of smelting and gas atomization powder preparation are omitted, and the cost is greatly reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of sputtering target materials and relates to a method for preparing a target material, in particular to a method for preparing a CoFeB target material by adopting hot isostatic pressing. Background Art

[0002] CoFeB is a very important alloy material in spin electronics. It is widely used in magnetic tunnel junctions and magnetic random access memories. It contains two of the three ferromagnetic metals at room temperature. The crystal structure of the pure metal mixture is destroyed by B doping, and the long-range order is removed to form an amorphous structure. There is no need to consider the lattice mismatch problem when combining it with semiconductor materials. Moreover, since its growth depends on magnetically controlled epitaxy, it gets rid of the limitations of growth methods such as molecular beam epitaxy, making large-scale industrial production possible.

[0003] However, at present, CoFeB alloy is mainly focused on film forming, and there are few studies on the preparation of CoFeB target materials. CN115747730A discloses a CoFeB alloy target material and a preparation method thereof. When preparing the CoFeB alloy target material, the method uses a boron nitride coating and molybdenum paper as a spacer layer, which can effectively reduce the C content in the CoFeB alloy target material, and adjust the grain size, density and magnetic permeability inside the target material by adjusting the conditions of pressure sintering, so that the final obtained CoFeB alloy target material has a uniform internal grain size, a high magnetic permeability, low C and O content, and accurate and uniform composition. However, the preparation method provided by it is complicated and costly, so this patent adopts a method of mixing powder and hot pressing sintering to prepare the CoFeB target material.

[0004] At present, the ratio of CoFeB alloy target is relatively simple, and the preparation method mainly comprises first preparing alloy powder by smelting and gas atomization powder making, and then hot pressing or hot isostatic pressing sintering after cold pressing. The process route is complicated, the loss in the intermediate process is large, and the cost is high. Therefore, it is necessary to provide a method for preparing CoFeB target by hot isostatic pressing with low cost and simple process. Summary of the invention

[0005] In view of the shortcomings of the prior art, the object of the present invention is to provide a method for preparing a CoFeB target material by hot isostatic pressing, which can prepare a dense, high-purity CoFeB target material with high magnetic permeability, omitting the smelting and gas atomization powder making process, and greatly reducing the cost.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] The present invention provides a method for preparing a CoFeB target material by hot isostatic pressing, the method comprising the following steps:

[0008] (1) mixing FeB powder, Co powder and Fe powder by ball milling according to the formula to obtain a mixed powder;

[0009] (2) The mixed powder obtained in step (1) is subjected to hot isostatic pressing to obtain a CoFeB target.

[0010] The present invention adopts a method of hot isostatic pressing and sintering after powder mixing to prepare a dense, high-purity CoFeB target material with relatively high magnetic permeability, omitting the smelting and gas atomization powder making process, and greatly reducing the cost.

[0011] Preferably, the ball milling mixing in step (1) is carried out in a protective atmosphere.

[0012] Preferably, the rotation speed of the ball milling mixing in step (1) is 50-200 r / min.

[0013] Preferably, the ball milling mixing time in step (1) is 10-48 hours.

[0014] Preferably, the ball-to-material ratio of the ball milling mixing in step (1) is 2:(3-10).

[0015] Preferably, the hot isostatic pressing sintering in step (2) is carried out in a stainless steel jacket.

[0016] Preferably, the mixed powder and the stainless steel sheath are isolated by high temperature cotton and graphite paper.

[0017] Preferably, the temperature of the hot isostatic pressing in step (2) is 750-950°C.

[0018] Preferably, the pressure of the hot isostatic pressing in step (2) is 100-130 MPa.

[0019] Preferably, the heat preservation and pressure holding time of the hot isostatic pressing in step (2) is 3-5 hours.

[0020] Preferably, the molar ratio of Co, Fe and B in the mixed powder of step (1) is (20-60):(20-50):(5-30).

[0021] Preferably, the particle size D50 of the FeB powder in step (1) is 3-24 μm, preferably 5-20 μm.

[0022] Preferably, the particle size D50 of the Co powder in step (1) is 3-10 μm.

[0023] Preferably, the particle size D50 of the Fe powder in step (1) is 3-10 μm.

[0024] Preferably, the purity of the FeB powder in step (1) is above 3N.

[0025] Preferably, the purity of the Co powder in step (1) is above 4N.

[0026] Preferably, the purity of the Fe powder in step (1) is above 4N.

[0027] As a preferred technical solution of the present invention, the method comprises the following steps:

[0028] (1) In a protective atmosphere, FeB powder, Co powder and Fe powder are mixed by ball milling according to the formula to obtain a mixed powder;

[0029] The speed of the ball milling is 50-200 r / min, the time is 10-48 h, and the ball-to-material ratio is 2:(3-10);

[0030] The mass ratio of Co, Fe and B in the mixed powder is (20-60):(20-50):(5-30);

[0031] The FeB powder has a particle size D50 of 5-20 μm and a purity of 3N or more;

[0032] The particle size D50 of the Co powder is 3-10 μm, and the purity is above 4N;

[0033] The particle size D50 of the Fe powder is 3-10 μm, and the purity is above 4N;

[0034] (2) hot isostatic pressing and sintering the mixed powder obtained in step (1) to obtain a CoFeB target;

[0035] The hot isostatic pressing sintering is carried out in a stainless steel jacket;

[0036] The mixed powder and the stainless steel sheath are isolated by high temperature cotton and graphite paper;

[0037] The temperature of the hot isostatic pressing is 750-950° C., the pressure is 100-130 MPa, and the heat preservation and pressure holding time is 3-5 hours.

[0038] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] The present invention adopts a method of hot isostatic pressing and sintering after powder mixing to prepare a dense, high-purity CoFeB target material with high magnetic permeability, eliminating the smelting and gas atomization powder making process, greatly reducing the cost; and can prepare a CoFeB target material with a density of 99.5%, uniform phase structure and a magnetic permeability of 35%. DETAILED DESCRIPTION

[0041] The technical solution of the present invention is further illustrated below through specific implementation methods.

[0042] A certain embodiment of the present invention provides a method for preparing a CoFeB target material by hot isostatic pressing, the method comprising the following steps:

[0043] (1) mixing FeB powder, Co powder and Fe powder by ball milling according to the formula to obtain a mixed powder;

[0044] (2) The mixed powder obtained in step (1) is subjected to hot isostatic pressing to obtain a CoFeB target.

[0045] The present invention adopts a method of hot isostatic pressing and sintering after powder mixing to prepare a dense, high-purity CoFeB target material with relatively high magnetic permeability, omitting the smelting and gas atomization powder making process, and greatly reducing the cost.

[0046] In certain embodiments, the ball milling mixing in step (1) is performed in a protective atmosphere.

[0047] The protective atmosphere of the present invention comprises nitrogen and / or inert gas.

[0048] The inert gas includes any one of helium, neon or argon or a combination of at least two of them. Typical but non-limiting combinations include a combination of helium and neon, a combination of neon and argon, a combination of helium and argon, or a combination of helium, neon and argon.

[0049] In some embodiments, the rotation speed of the ball milling mixing in step (1) is 50-200 r / min, for example, it can be 50 r / min, 100 r / min, 150 r / min or 200 r / min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0050] Exemplarily, the ball milling mixing method in step (1) of the present invention includes but is not limited to planetary ball milling, and the rotation speed is the orbital speed of the planetary ball mill.

[0051] In certain embodiments, the ball milling mixing time in step (1) is 10-48 hours, for example, 10 hours, 15 hours, 20 hours, 30 hours, 40 hours or 48 hours, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0052] In certain embodiments, the ball-to-material ratio of the ball-milling mixing in step (1) is 2:(3-10), for example, it can be 2:3, 2:4, 2:5, 2:6, 2:8 or 2:10, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0053] In certain embodiments, the hot isostatic pressing sintering in step (2) is performed in a stainless steel jacket.

[0054] In some embodiments, the mixed powder is isolated from the stainless steel sheath by high temperature wool and graphite paper.

[0055] In some embodiments, the temperature of the hot isostatic pressing in step (2) is 750-950°C, for example, 750°C, 800°C, 850°C, 900°C or 950°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0056] In some embodiments, the pressure of the hot isostatic pressing in step (2) is 100-130 MPa, for example, 100 MPa, 105 MPa, 110 MPa, 120 MPa or 130 MPa, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0057] In some embodiments, the holding time of the hot isostatic pressing in step (2) is 3-5 hours, for example, 3 hours, 4 hours or 5 hours, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0058] In certain embodiments, the molar ratio of Co, Fe, and B in the mixed powder of step (1) is (20-60):(20-50):(5-30), for example, it can be 20:50:30, 40:30:20, or 60:20:5, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0059] In some embodiments, the particle size D50 of the FeB powder in step (1) is 3-24 μm, preferably 5-20 μm, for example, 3 μm, 5 μm, 10 μm, 15 μm, 20 μm or 24 μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0060] In some embodiments, the particle size D50 of the Co powder in step (1) is 3-10 μm, for example, 3 μm, 5 μm, 6 μm, 8 μm or 10 μm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0061] In some embodiments, the particle size D50 of the Fe powder in step (1) is 3-10 μm, for example, 3 μm, 5 μm, 6 μm, 8 μm or 10 μm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0062] In some embodiments, the purity of the FeB powder in step (1) is above 3N, for example, it can be 99.9wt%, 99.93wt%, 99.95wt%, 99.98wt% or 99.99wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0063] In some embodiments, the purity of the Co powder in step (1) is above 4N, for example, it can be 99.99wt%, 99.993wt%, 99.995wt%, 99.998wt% or 99.999wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0064] In some embodiments, the purity of the Fe powder in step (1) is above 4N, for example, it can be 99.99wt%, 99.993wt%, 99.995wt%, 99.998wt% or 99.999wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0065] As a preferred technical solution of the present invention, the method comprises the following steps:

[0066] (1) In a protective atmosphere, FeB powder, Co powder and Fe powder are mixed by ball milling according to the formula to obtain a mixed powder;

[0067] The speed of the ball milling is 50-200 r / min, the time is 10-48 h, and the ball-to-material ratio is 2:(3-10);

[0068] The molar ratio of Co, Fe and B in the mixed powder is (20-60):(20-50):(5-30);

[0069] The FeB powder has a particle size D50 of 5-20 μm and a purity of 3N or more;

[0070] The particle size D50 of the Co powder is 3-10 μm, and the purity is above 4N;

[0071] The particle size D50 of the Fe powder is 3-10 μm, and the purity is above 4N;

[0072] (2) hot isostatic pressing and sintering the mixed powder obtained in step (1) to obtain a CoFeB target;

[0073] The hot isostatic pressing sintering is carried out in a stainless steel jacket;

[0074] The mixed powder and the stainless steel sheath are isolated by high temperature cotton and graphite paper;

[0075] The temperature of the hot isostatic pressing is 750-950° C., the pressure is 100-130 MPa, and the heat preservation and pressure holding time is 3-5 hours.

[0076] Example 1

[0077] This embodiment provides a method for preparing a CoFeB target material by hot isostatic pressing, the method comprising the following steps:

[0078] (1) In a nitrogen atmosphere, FeB powder, Co powder and Fe powder are mixed by ball milling according to the formula to obtain a mixed powder;

[0079] The ball milling mixing was performed at a speed of 100 r / min, a time of 30 h, and a ball-to-material ratio of 2:6;

[0080] The molar ratio of Co, Fe and B in the mixed powder is 30:50:20;

[0081] The particle size D50 of the FeB powder is 10 μm, and the purity is 3N; the particle size D50 of the Co powder is 6 μm, and the purity is 4N; the particle size D50 of the Fe powder is 6 μm, and the purity is 4N;

[0082] (2) hot isostatic pressing and sintering the mixed powder obtained in step (1), and machining to obtain a CoFeB target;

[0083] The hot isostatic pressing sintering is carried out in a stainless steel jacket;

[0084] The mixed powder and the stainless steel sheath are isolated by high temperature cotton and graphite paper;

[0085] The hot isostatic pressing temperature is 850° C., the pressure is 115 MPa, and the heat preservation and pressure holding time is 4 hours.

[0086] Example 2

[0087] This embodiment provides a method for preparing a CoFeB target material by hot isostatic pressing, the method comprising the following steps:

[0088] (1) In a nitrogen atmosphere, FeB powder, Co powder and Fe powder are mixed by ball milling according to the formula to obtain a mixed powder;

[0089] The ball milling mixing was performed at a speed of 50 r / min, a time of 48 h, and a ball-to-material ratio of 2:3;

[0090] The molar ratio of Co, Fe and B in the mixed powder is 30:50:20;

[0091] The particle size D50 of the FeB powder is 5 μm, and the purity is 3N; the particle size D50 of the Co powder is 3 μm, and the purity is 4N; the particle size D50 of the Fe powder is 3 μm, and the purity is 4N;

[0092] (2) hot isostatic pressing and sintering the mixed powder obtained in step (1), and machining to obtain a CoFeB target;

[0093] The hot isostatic pressing sintering is carried out in a stainless steel jacket;

[0094] The mixed powder and the stainless steel sheath are isolated by high temperature cotton and graphite paper;

[0095] The hot isostatic pressing temperature is 750° C., the pressure is 100 MPa, and the heat preservation and pressure holding time is 5 hours.

[0096] Example 3

[0097] This embodiment provides a method for preparing a CoFeB target material by hot isostatic pressing, the method comprising the following steps:

[0098] (1) In a nitrogen atmosphere, FeB powder, Co powder and Fe powder are mixed by ball milling according to the formula to obtain a mixed powder;

[0099] The ball milling mixing was performed at a speed of 200 r / min, a time of 10 h, and a ball-to-material ratio of 2:10;

[0100] The molar ratio of Co, Fe and B in the mixed powder is 30:50:20;

[0101] The particle size D50 of the FeB powder is 20 μm, and the purity is 3N; the particle size D50 of the Co powder is 10 μm, and the purity is 4N; the particle size D50 of the Fe powder is 10 μm, and the purity is 4N;

[0102] (2) hot isostatic pressing and sintering the mixed powder obtained in step (1), and machining to obtain a CoFeB target;

[0103] The hot isostatic pressing sintering is carried out in a stainless steel jacket;

[0104] The mixed powder and the stainless steel sheath are isolated by high temperature cotton and graphite paper;

[0105] The hot isostatic pressing temperature is 950° C., the pressure is 130 MPa, and the heat preservation and pressure holding time is 3 hours.

[0106] Example 4

[0107] This embodiment provides a method for preparing a CoFeB target by hot isostatic pressing, which is the same as that of Embodiment 1 except that the molar ratio of Co, Fe, and B in the mixed powder is 60:20:20.

[0108] Example 5

[0109] This embodiment provides a method for preparing a CoFeB target material by hot isostatic pressing. Except that the particle size D50 of the FeB powder is 3 μm, the rest is the same as that of Embodiment 1.

[0110] Example 6

[0111] This embodiment provides a method for preparing a CoFeB target material by hot isostatic pressing. Except that the particle size D50 of the FeB powder is 24 μm, the rest is the same as that of Embodiment 1.

[0112] Example 7

[0113] This embodiment provides a method for preparing a CoFeB target material by hot isostatic pressing. Except that the temperature of the hot isostatic pressing is 700° C., the rest is the same as that of Embodiment 1.

[0114] Performance Characterization

[0115] The density and magnetic permeability of the CoFeB target materials obtained in Examples 1-13 were measured. The density was measured by the Archimedes drainage method. The magnetic permeability was measured using a dedicated magnetic permeability detection device. The results are shown in Table 1.

[0116] Table 1

[0117]

[0118]

[0119] In summary, the present invention adopts the method of hot isostatic pressing and sintering after powder mixing to prepare a dense, high-purity CoFeB target with high magnetic permeability, which eliminates the smelting and gas atomization powder making process and greatly reduces the cost; and can prepare a CoFeB target with a density of 99.5%, uniform phase structure and a magnetic permeability of 35%.

[0120] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a CoFeB target by hot isostatic pressing, characterized in that: The method comprises the following steps: (1) mixing FeB powder, Co powder and Fe powder by ball milling according to the formula to obtain a mixed powder; (2) The mixed powder obtained in step (1) is subjected to hot isostatic pressing to obtain a CoFeB target.

2. The method according to claim 1, characterized in that The ball milling mixing in step (1) is carried out in a protective atmosphere.

3. The method according to claim 1 or 2, characterized in that: The rotation speed of the ball milling mixing in step (1) is 50-200 r / min; Preferably, the ball milling mixing time in step (1) is 10-48 hours; Preferably, the ball-to-material ratio of the ball milling mixing in step (1) is 2:(3-10).

4. The method according to any one of claims 1 to 3, characterized in that: The hot isostatic pressing sintering in step (2) is carried out in a stainless steel jacket; Preferably, the mixed powder and the stainless steel sheath are isolated by high temperature cotton and graphite paper.

5. The method according to any one of claims 1 to 4, characterized in that: The temperature of the hot isostatic pressing in step (2) is 750-950° C. Preferably, the pressure of the hot isostatic pressing in step (2) is 100-130 MPa.

6. The method according to claim 5, characterized in that The heat preservation and pressure holding time of the hot isostatic pressing in step (2) is 3-5h.

7. The method according to any one of claims 1 to 6, characterized in that: The molar ratio of Co, Fe and B in the mixed powder of step (1) is (20-60):(20-50):(5-30).

8. The method according to claim 7, characterized in that The particle size D50 of the FeB powder in step (1) is 3-24 μm, preferably 5-20 μm; Preferably, the particle size D50 of the Co powder in step (1) is 3-10 μm; Preferably, the particle size D50 of the Fe powder in step (1) is 3-10 μm.

9. The method according to claim 7 or 8, characterized in that: The purity of the FeB powder in step (1) is above 3N; Preferably, the purity of the Co powder in step (1) is above 4N; Preferably, the purity of the Fe powder in step (1) is above 4N.

10. The method according to claim 1, characterized in that The method comprises the following steps: (1) In a protective atmosphere, FeB powder, Co powder and Fe powder are mixed by ball milling according to the formula to obtain a mixed powder; The speed of the ball milling is 50-200 r / min, the time is 10-48 h, and the ball-to-material ratio is 2:(3-10); The molar ratio of Co, Fe and B in the mixed powder is (20-60):(20-50):(5-30); The FeB powder has a particle size D50 of 5-20 μm and a purity of 3N or more; The particle size D50 of the Co powder is 3-10 μm, and the purity is above 4N; The particle size D50 of the Fe powder is 3-10 μm, and the purity is above 4N; (2) hot isostatic pressing and sintering the mixed powder obtained in step (1) to obtain a CoFeB target; The hot isostatic pressing sintering is carried out in a stainless steel jacket; The mixed powder and the stainless steel sheath are isolated by high temperature cotton and graphite paper; The temperature of the hot isostatic pressing is 750-950° C., the pressure is 100-130 MPa, and the heat preservation and pressure holding time is 3-5 hours.

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