CoFeB target material and preparation method thereof

Abstract

The invention provides a CoFeB target material and a preparation method thereof, and the preparation method comprises the following steps: mixing CoB powder, Co powder and Fe powder to obtain mixed powder; carrying out ball milling on the obtained mixed powder to obtain a sintering raw material; and carrying out hot pressed sintering on the obtained sintering raw material to obtain the CoFeB target material. According to the preparation method provided by the invention, a powder mixing and hot pressed sintering combined process is adopted, the high-quality CoFeB target material with high purity, high density and high magnetic permeability is prepared, the whole preparation process of the CoFeB target material is simplified, and the production cost is remarkably reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of target material preparation, and in particular relates to a CoFeB target material and a preparation method thereof. Background Art

[0002] CoFeB alloy is an important ferromagnetic alloy material, which is widely used in the field of spin electronics, especially in devices such as magnetic tunnel junction (MTJ) and magnetic random access memory (MRAM). CoFeB alloy is usually composed of three elements: cobalt (Co), iron (Fe) and boron (B). Through the doping of B element, the crystal structure of the alloy will change, destroying the crystal structure of the pure metal mixture of Co and Fe to form an amorphous structure, which not only removes the long-range order, but also effectively avoids the lattice mismatch problem caused by traditional metal alloys when combined with semiconductor materials.

[0003] In the preparation process of CoFeB alloy, the research and application of thin film preparation technology has made significant progress, especially magnetron sputtering and other technologies provide a good platform for high-quality growth of thin films. However, the research and preparation methods of CoFeB alloy targets are still relatively limited.

[0004] The prior art discloses some research on the preparation technology of CoFeB target materials. For example, CN115747730A discloses a CoFeB alloy target material and a preparation method thereof, wherein the preparation method comprises weighing cobalt, iron and boron raw materials for batching, smelting in an inert atmosphere, atomizing and powdering the melt, and then using a boron nitride coating and molybdenum paper as a spacer layer, pre-pressing and hot pressing sintering to obtain a CoFeB alloy target material with a low carbon content; CN116288196A discloses a CoFeB target material and a preparation method thereof, specifically, after smelting the cobalt, iron and boron raw materials, performing secondary feeding and stirring, and then melt casting to obtain a CoFeB target material; CN116815136A discloses a CoFeB alloy target material and a preparation method thereof, wherein boron particles, cobalt sheets and iron sheets are smelted, atomized and powdered to obtain alloy raw materials, and then hot isostatic pressing and sintering are performed to obtain a CoFeB alloy target material. However, at present, the preparation methods of CoFeB targets mostly rely on processes such as smelting, gas atomization powder making and hot isostatic pressing. These processes are often complicated, difficult to operate and costly, resulting in an increase in the cost of preparing high-performance CoFeB alloy targets, limiting their application in large-scale industrial production.

[0005] In order to solve the problems of the prior art, the present invention provides a process for preparing a CoFeB target material. Summary of the invention

[0006] In view of the shortcomings of the prior art, the object of the present invention is to provide a CoFeB target material and a preparation method thereof, simplify the preparation process, prepare high-quality CoFeB target material, and facilitate large-scale industrial production.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a method for preparing a CoFeB target, the preparation method comprising the following steps:

[0009] (1) Mixing CoB powder, Co powder and Fe powder to obtain a mixed powder;

[0010] (2) ball milling the mixed powder obtained in step (1) to obtain a sintering raw material;

[0011] (3) hot pressing and sintering the sintered raw material obtained in step (2) to obtain a CoFeB target.

[0012] The preparation method provided by the present invention adopts a combination process of powder mixing and hot pressing sintering, which simplifies the entire preparation process of the CoFeB target material, reduces the loss in the intermediate links, and significantly reduces the production cost. It can not only ensure the high density and uniformity of the CoFeB target material, but also effectively control the purity and magnetic properties of the target material, and is suitable for large-scale industrial production.

[0013] Preferably, in the mixed powder of step (1), the content of Fe element is 5-30wt%, for example, it can be 5wt%, 10wt%, 15wt%, 20wt%, 25wt% or 30wt%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0014] Preferably, in the mixed powder of step (1), the content of Co element is 40-70wt%, for example, it can be 40wt%, 45wt%, 50wt%, 55wt%, 60wt%, 65wt% or 70wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0015] Preferably, in the mixed powder of step (1), the content of element B is 5-30wt%, for example, it can be 5wt%, 10wt%, 15wt%, 20wt%, 25wt% or 30wt%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0016] Preferably, the particle size of the CoB powder in step (1) is in the range of 5-20 μm, for example, 5 μm, 10 μm, 15 μm or 20 μm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0017] Preferably, the purity of the CoB powder in step (1) is ≥3N, for example, 3N, 3.5N, 4N, 4.5N, 5N or 6N, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0018] Preferably, the particle size of the Co powder in step (1) is in the range of 3-10 μm, for example, 3 μm, 4 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.

[0019] Preferably, the purity of the Co powder in step (1) is ≥4N, for example, it can be 4N, 4.5N, 5N, 5.5N or 6N, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0020] Preferably, the particle size range of the Fe powder in step (1) is 3-10 μm, for example, 3 μm, 4 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.

[0021] Preferably, the purity of the Fe powder in step (1) is ≥4N, for example, it can be 4N, 4.5N, 5N, 5.5N or 6N, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0022] Preferably, the ball milling in step (2) is carried out under an inert gas atmosphere.

[0023] Preferably, the ball-to-material ratio of the ball milling in step (2) is 2:(3-10), for example, it can be 2:3, 2:4, 2:5, 2:6, 2:7, 2:8, 2:9 or 2:10, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0024] Preferably, the rotation speed of the ball mill in step (2) is 50-200 r / min, for example, it can be 50 r / min, 75 r / min, 100 r / min, 125 r / min, 150 r / min, 175 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.

[0025] Preferably, the ball milling time in step (2) is 10-48 h, for example, 10 h, 15 h, 20 h, 25 h, 30 h, 35 h, 40 h, 45 h or 48 h, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0026] Preferably, the temperature of the hot pressing sintering in step (3) is 950-1100°C, for example, it can be 950°C, 975°C, 1000°C, 1025°C, 1050°C, 1075°C or 1100°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0027] Preferably, the pressure of the hot pressing sintering in step (3) is 30-50 MPa, for example, 30 MPa, 35 MPa, 40 MPa, 45 MPa or 50 MPa, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0028] Preferably, the hot pressing sintering time in step (3) is 1-3 hours, for example, 1 hour, 1.5 hours, 2 hours, 2.5 hours or 3 hours, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0029] As a preferred technical solution of the preparation method provided by the present invention, the preparation method comprises the following steps:

[0030] (1) CoB powder with a purity of 3N or more and a particle size of 5-20 μm, Co powder with a purity of 4N or more and a particle size of 3-10 μm, and Fe powder with a purity of 4N or more and a particle size of 3-10 μm are selected and mixed to obtain a mixed powder, wherein the content of Fe element is 5-30wt%, the content of Co element is 40-70wt%, and the content of B element is 5-30wt%;

[0031] (2) ball milling the mixed powder obtained in step (1) under an argon atmosphere at a rotation speed of 50-200 r / min, a ball-to-material ratio of 2:(3-10), and a ball milling time of 10-48 h to obtain a sintering raw material;

[0032] (3) The sintering raw material obtained in step (2) is loaded into a graphite mold for hot pressing and sintering. The hot pressing and sintering temperature is 950-1100° C., the hot pressing and sintering pressure is 30-50 MPa, and the hot pressing and sintering time is 1-3 h to obtain a CoFeB target.

[0033] In a second aspect, the present invention provides a CoFeB target material, wherein the CoFeB target material is prepared by the preparation method described in the first aspect.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The preparation method provided by the present invention adopts a combination process of powder mixing and hot pressing sintering to prepare high-quality CoFeB target materials with high purity, high density and high magnetic permeability, simplifies the entire preparation process of the CoFeB target materials, and significantly reduces production costs. DETAILED DESCRIPTION

[0036] The technical solution of the present invention is further illustrated below through specific implementation methods.

[0037] Example 1

[0038] This embodiment provides a method for preparing a CoFeB target material, the preparation method comprising the following steps:

[0039] (1) CoB powder with a purity of 3N (particle size range of 5-20 μm), Co powder with a purity of 4N (particle size range of 3-10 μm) and Fe powder with a purity of 4N (particle size range of 3-10 μm) were mixed to obtain a mixed powder with a content of Fe element of 15 wt%, a content of Co element of 65 wt% and a content of B element of 20 wt%;

[0040] (2) placing the mixed powder obtained in step (1) into a ball mill, mixing the powder using a planetary ball mill, with a ball mill speed of 100 r / min, a ball-to-material ratio of 2:6, and a time of 30 h, and mixing the powder in an argon protective atmosphere to obtain a sintering raw material;

[0041] (3) The sintering raw material obtained in step (2) is loaded into a graphite mold for hot pressing and sintering. The hot pressing and sintering temperature is 1000° C., the pressure is 40 MPa, and the heat and pressure holding time is 2 h to obtain a CoFeB target.

[0042] Example 2

[0043] This embodiment provides a method for preparing a CoFeB target material, the preparation method comprising the following steps:

[0044] (1) CoB powder with a purity of 3N (particle size range of 5-20 μm), Co powder with a purity of 4N (particle size range of 3-10 μm) and Fe powder with a purity of 4N (particle size range of 3-10 μm) were mixed to obtain a mixed powder with a content of Fe element of 30 wt%, a content of Co element of 40 wt% and a content of B element of 30 wt%;

[0045] (2) placing the mixed powder obtained in step (1) into a ball mill, mixing the powder using a planetary ball mill, with a ball mill speed of 50 r / min, a ball-to-material ratio of 2:3, and a time of 48 h, and mixing the powder in an argon protective atmosphere to obtain a sintering raw material;

[0046] (3) The sintering raw material obtained in step (2) is loaded into a graphite mold for hot pressing and sintering. The hot pressing and sintering temperature is 950° C., the pressure is 50 MPa, and the heat and pressure holding time is 1 h to obtain a CoFeB target.

[0047] Example 3

[0048] This embodiment provides a method for preparing a CoFeB target material, the preparation method comprising the following steps:

[0049] (1) CoB powder with a purity of 3N (particle size range of 5-20 μm), Co powder with a purity of 4N (particle size range of 3-10 μm) and Fe powder with a purity of 4N (particle size range of 3-10 μm) were mixed to obtain a mixed powder with a content of Fe element of 5 wt%, a content of Co element of 70 wt% and a content of B element of 25 wt%;

[0050] (2) placing the mixed powder obtained in step (1) into a ball mill, mixing the powder using a planetary ball mill, with a ball mill speed of 200 r / min, a ball-to-material ratio of 2:10, and a mixing time of 10 h, the powder mixing is carried out in an argon protective atmosphere to obtain a sintering raw material;

[0051] (3) The sintering raw material obtained in step (2) is loaded into a graphite mold for hot pressing and sintering. The hot pressing and sintering temperature is 1100° C., the pressure is 30 MPa, and the heat and pressure holding time is 3 h to obtain a CoFeB target.

[0052] Example 4

[0053] This embodiment provides a method for preparing a CoFeB target material, the preparation method comprising the following steps:

[0054] (1) CoB powder with a purity of 3N (particle size range of 5-20 μm), Co powder with a purity of 4N (particle size range of 3-10 μm) and Fe powder with a purity of 4N (particle size range of 3-10 μm) were mixed to obtain a mixed powder with a content of Fe element of 15 wt%, a content of Co element of 65 wt% and a content of B element of 20 wt%;

[0055] (2) placing the mixed powder obtained in step (1) into a ball mill, mixing the powder using a planetary ball mill, with a ball mill speed of 100 r / min, a ball-to-material ratio of 2:6, and a time of 30 h, and mixing the powder in an argon protective atmosphere to obtain a sintering raw material;

[0056] (3) The sintering raw material obtained in step (2) is loaded into a graphite mold for hot pressing and sintering. The hot pressing and sintering temperature is 900° C., the pressure is 40 MPa, and the heat and pressure holding time is 2 h to obtain a CoFeB target.

[0057] That is, compared with Example 1, the temperature of hot pressing sintering is controlled to 900° C., and the rest are the same as Example 1.

[0058] Example 5

[0059] This embodiment provides a method for preparing a CoFeB target material, the preparation method comprising the following steps:

[0060] (1) CoB powder with a purity of 3N (particle size range of 5-20 μm), Co powder with a purity of 4N (particle size range of 3-10 μm) and Fe powder with a purity of 4N (particle size range of 3-10 μm) were mixed to obtain a mixed powder with a content of Fe element of 15 wt%, a content of Co element of 65 wt% and a content of B element of 20 wt%;

[0061] (2) placing the mixed powder obtained in step (1) into a ball mill, mixing the powder using a planetary ball mill, with a ball mill speed of 100 r / min, a ball-to-material ratio of 2:6, and a time of 30 h, and mixing the powder in an argon protective atmosphere to obtain a sintering raw material;

[0062] (3) The sintering raw material obtained in step (2) is loaded into a graphite mold for hot pressing and sintering. The hot pressing and sintering temperature is 1200° C., the pressure is 40 MPa, and the heat and pressure holding time is 2 h to obtain a CoFeB target.

[0063] That is, compared with Example 1, the temperature of hot pressing sintering is controlled to 1200° C., and the rest are the same as Example 1.

[0064] The purity, density and magnetic permeability of the CoFeB target prepared in Example 1 were tested, and the results are listed in Table 1.

[0065] Table 1

[0066] purity(%) Density(%) Magnetic permeability (%) Example 1 3N5 ＞98.5 15 Example 2 3N 98 20 Example 3 3N2 ＞98.5 10 Example 4 3N5 97 10 Example 5 3N5 ＞98.5 12

[0067] As can be seen from Table 1, the preparation method provided by the present invention adopts a specific raw material composition, and a two-step process of powder mixing and hot pressing sintering can be used to realize the preparation of CoFeB target material. The obtained target material has high purity, good density, high magnetic permeability, and good target performance. Compared with Example 1, in Example 4, the temperature of hot pressing sintering is too low, the densification degree of the target material is insufficient, the density is reduced, and the magnetic permeability is reduced. In Example 5, the temperature of hot pressing sintering is too high, the density of the target material is difficult to further improve, and the magnetic permeability is reduced. It can be seen that the preparation method of the present invention adopts specific raw materials and processes to cooperate with each other, which is crucial to the performance of the target material.

[0068] In summary, the preparation method provided by the present invention adopts a combination of powder mixing and hot pressing and sintering, uses specific raw materials and ratios, and can prepare high-quality CoFeB targets with high purity, high density and high magnetic permeability only by hot pressing and sintering after ball milling, which simplifies the entire preparation process of the CoFeB target and significantly reduces the production cost. The process flow is simple, the loss is low, and the cost is low.

[0069] 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, characterized in that: The preparation method comprises the following steps: (1) mixing CoB powder, Co powder and Fe powder to obtain a mixed powder; (2) ball milling the mixed powder obtained in step (1) to obtain a sintering raw material; (3) hot pressing and sintering the sintered raw material obtained in step (2) to obtain a CoFeB target.

2. The preparation method according to claim 1, characterized in that: In the mixed powder of step (1), the content of Fe element is 5-30wt%, the content of Co element is 40-70wt%, and the content of B element is 5-30wt%.

3. The preparation method according to claim 1 or 2, characterized in that: The particle size of the CoB powder in step (1) is in the range of 5-20 μm; Preferably, the purity of the CoB powder in step (1) is ≥3N; Preferably, the particle size of the Co powder in step (1) is in the range of 3-10 μm; Preferably, the purity of the Co powder in step (1) is ≥4N; Preferably, the particle size of the Fe powder in step (1) is in the range of 3-10 μm; Preferably, the purity of the Fe powder in step (1) is ≥4N.

4. The preparation method according to any one of claims 1 to 3, characterized in that The ball milling in step (2) is carried out under an inert gas atmosphere; Preferably, the ball-to-material ratio of the ball milling in step (2) is 2:(3-10).

5. The preparation method according to any one of claims 1 to 4, characterized in that: The rotation speed of the ball mill in step (2) is 50-200 r / min; Preferably, the ball milling time in step (2) is 10-48 hours.

6. The preparation method according to any one of claims 1 to 5, characterized in that: The temperature of the hot pressing sintering in step (3) is 950-1100°C.

7. The preparation method according to any one of claims 1 to 6, characterized in that: The pressure of the hot pressing sintering in step (3) is 30-50MPa.

8. The preparation method according to any one of claims 1 to 7, characterized in that: The hot pressing sintering time in step (3) is 1-3 hours.

9. The preparation method according to any one of claims 1 to 8, characterized in that: The preparation method comprises the following steps: (1) CoB powder with a purity of 3N or more and a particle size of 5-20 μm, Co powder with a purity of 4N or more and a particle size of 3-10 μm, and Fe powder with a purity of 4N or more and a particle size of 3-10 μm are selected and mixed to obtain a mixed powder, wherein the content of Fe element is 5-30wt%, the content of Co element is 40-70wt%, and the content of B element is 5-30wt%; (2) ball milling the mixed powder obtained in step (1) under an argon atmosphere at a rotation speed of 50-200 r / min, a ball-to-material ratio of 2:(3-10), and a ball milling time of 10-48 h to obtain a sintering raw material; (3) The sintering raw material obtained in step (2) is loaded into a graphite mold for hot pressing and sintering. The hot pressing and sintering temperature is 950-1100° C., the hot pressing and sintering pressure is 30-50 MPa, and the hot pressing and sintering time is 1-3 h to obtain a CoFeB target.

10. A CoFeB target material, characterized in that: The CoFeB target is prepared by the preparation method according to any one of claims 1-9.