A method for preparing chromium rotating target

Abstract

The present invention relates to the technical field of sputtering target materials, and provides a method for preparing a chromium rotating target material, comprising the following steps: (1) processing spiral lines and sandblasting on the outer diameter surface of a back tube; (2) welding the back tube and the bottom surface of a sleeve to provide a cavity between the back tube and the sleeve, adding chromium powder into the cavity, welding the upper surface of the back tube and the sleeve, and then sequentially degassing, dehydrating and vacuuming; (3) placing in a hot isostatic pressing device for preforming; (4) performing hot isostatic pressing again to improve the densification of the chromium powder; and (5) annealing. The present invention can control the deformation direction of the entire target material, reduce the deformation amount of the target material, and improve the density of the target material by adding a preforming process.

Description

Technical Field

[0001] The invention relates to the technical field of sputtering target materials, in particular to a method for preparing a chromium rotating target material. Background Art

[0002] Target products are mainly divided into planar targets and tube targets. Compared with planar targets, tube targets have the advantages of high utilization rate, good coating continuity, and uniform coating composition. They are ideal sputtering targets with huge market demand. As the coating industry shifts from using planar targets to using rotating tube targets, tube targets are becoming the standard material for magnetron sputtering equipment. Therefore, physical vapor deposition equipment manufacturers and target suppliers have been committed to the development and application of tubular targets with higher target utilization rates.

[0003] In the prior art of tubular target manufacturing, hot isostatic pressing technology is usually required. Hot isostatic pressing (HIP) is a method of applying isostatic pressure in all directions to the powder or sintered blank (or part) to be compacted in a high-temperature and high-pressure sealed container with high-pressure gas as the medium to form a high-density blank (or part). However, when making tubular targets, in the hot isostatic pressing equipment, when high temperature and high pressure are set at the beginning, the tubular targets are prone to uncontrollable deformation, and may even be scrapped.

[0004] CN202110612746.8 discloses a tubular target material and a preparation method thereof, the preparation method comprising the following steps: preparing a stainless steel inner tube and a stainless steel outer tube, threading the outer surface of the stainless steel inner tube, and sandblasting the inner surface of the stainless steel outer tube; coaxially welding the processed stainless steel inner tube and stainless steel outer tube to a first stainless steel cover plate to form an annular cavity; loading the mixed alloy powder into the annular cavity for compaction treatment, and then welding the second stainless steel cover plate to the other end of the stainless steel inner tube and the stainless steel outer tube, and sequentially performing degassing treatment and hot isostatic pressing treatment to obtain a tubular target material; the preparation method adopts a hot isostatic pressing integrated molding method, and by improving the stainless steel inner tube and outer tube, the density and uniformity of the tubular target material are effectively improved, the oxygen content of the tubular target material is reduced, and the yield rate of the tubular target material is improved, and it has good industrial application prospects.

[0005] However, in the above technical solution, under the direct high temperature and high pressure of 120-170 MPa and 1000-1250°C during hot isostatic pressing, the stainless steel inner tube and the stainless steel outer tube are prone to uncontrollable deformation without preforming, and may even be scrapped. Summary of the invention

[0006] The invention provides a method for preparing a chromium rotary target material. The method adopts a low pressure of 20-25 MPa in the whole process of hot isostatic pressing, and sequentially performs preforming at a temperature of 635-650° C. and hot isostatic pressing at a temperature of 1100-1300° C. to improve the densification of chromium powder. In the process of preforming, the deformation direction of the entire target material can be controlled, the deformation amount of the target material can be reduced, and the density of the target material can be improved.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A method for preparing a chromium rotating target comprises the following steps:

[0009] (1) Processing spiral patterns and sandblasting on the outer diameter surface of the back tube;

[0010] (2) welding the bottom surface of the back tube and the sheath to form a cavity between the back tube and the sheath, adding chromium powder into the cavity, welding the upper surface of the back tube and the sheath, and then degassing, dehydrating and vacuuming in sequence;

[0011] (3) Place in hot isostatic pressing equipment, set the air pressure to 20-25 MPa, the temperature to 635-650° C., and process for 6-8 hours for preforming;

[0012] (4) In a hot isostatic pressing device, maintain the gas pressure in step (3), set the temperature to 1100-1300° C., and continue hot isostatic pressing for 6-8 hours;

[0013] (5) Annealing

[0014] In the above-mentioned method for preparing a chromium rotary target, the gas pressure 20-25MPa set in the step (3) includes but is not limited to 20MPa, 21MPa, 22MPa, 23MPa, 24MPa, and 25MPa; the temperature 635-650°C set in the step (3) includes but is not limited to 635°C, 640°C, 645°C, and 650°C; the processing time 6-8h in the step (3) includes but is not limited to 6h, 7h, and 8h.

[0015] In the above-mentioned method for preparing a chromium rotary target, the cross-section of the thread in step (1) is an equilateral triangle of 0.5-0.8 mm, but not limited to 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, and the thread pitch is 3-5 mm, but not limited to 3 mm, 4 mm, 5 mm.

[0016] In the above-mentioned method for preparing a chromium rotary target, the surface roughness of the back tube after sandblasting in step (1) is Ra6-10μm, but not limited to Ra6μm, Ra7μm, Ra8μm, Ra9μm, Ra10μm.

[0017] In the present invention, the chromium powder is a non-spherical powder with a D50 of 200-400 meshes, including but not limited to 200 meshes, 300 meshes, and 400 meshes.

[0018] The present invention further includes a step of machining the chromium target after annealing.

[0019] In the present invention, the cooling rate of annealing in step (5) is 2-3°C / mim, including but not limited to 2°C / mim, 2.5°C / mim, and 3°C / mim.

[0020] In the present invention, the degassing and dehydration temperature in step (3) is 280-310°C, including but not limited to 280°C, 290°C, 300°C, and 310°C, and the time is 6-8h, including but not limited to 6h, 7h, and 8h.

[0021] In step (3) and step (4), the gas introduced during hot isostatic pressing is an inert gas, preferably argon.

[0022] In the present invention, the material of the sheath is 45 carbon steel; the material of the back tube is stainless steel.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The present invention performs hot isostatic pressing in a low-pressure environment, and adds a constant temperature platform with a temperature of 635-650°C during the hot isostatic pressing process to preform the target material, and then performs hot isostatic pressing at a temperature of 1100-1300°C to improve the densification of chromium powder. Through such a design, the deformation direction of the entire target material can be controlled, the deformation amount of the target material can be reduced, and the density of the target material can be improved. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field without creative work based on the embodiments of the present invention are within the scope of protection of the present invention.

[0026] Example 1

[0027] In the examples, the experimental methods used are conventional methods unless otherwise specified, and the materials, reagents, etc. used are all commercially available unless otherwise specified.

[0028] A method for preparing a chromium rotating target comprises the following steps:

[0029] (1) A stainless steel back tube with a length of 1000 mm, an inner diameter of 123 mm, and an outer diameter of 133 mm is used. A spiral pattern and sandblasting treatment are performed on the outer diameter surface of the back tube. The cross section of the spiral pattern is an equilateral triangle of 0.5 mm, and the thread pitch is 4 mm. The surface roughness of the back tube after sandblasting is Ra8 μm.

[0030] (2) A 1.5 mm thick 45 carbon steel sheath is used to weld the back tube to the bottom surface of the sheath, so that a cavity is provided between the back tube and the sheath, and non-spherical chromium powder with a particle size of D50 and 315 mesh is added into the cavity. After welding the upper surface of the back tube and the sheath, degassing, dehydration and vacuuming are performed at 300°C for 6 hours;

[0031] (3) Place in hot isostatic pressing equipment, set the air pressure to 20 MPa, the temperature to 650°C, and process for 6 hours for preforming;

[0032] (4) In a hot isostatic pressing device, the gas pressure in step (3) is maintained, the temperature is set to 1200° C., and the hot isostatic pressing is continued for 6 h;

[0033] (5) Annealing

[0034] In the present invention, in the step (1), the selection of the thread shape depends on the tool. Among the existing tools and thread shapes, the equilateral triangle thread shape is the easiest to process.

[0035] In the present invention, in the step (1), after the back tube is threaded, sandblasting is performed, in order to increase the bonding strength between the chrome powder and the back tube.

[0036] In the present invention, compared with spherical powder, the non-spherical powder is easier to obtain and more economical.

[0037] It should also be noted that in step (2), during the process of adding chromium powder, it is necessary to turn on the external dust collector in order to collect the excess powder floating in the air.

[0038] The present invention further includes a step of machining the chromium target after annealing.

[0039] In the present invention, the temperature of the degassing and dehydration in step (3) can discharge the gas while preventing the oxidation of the material.

[0040] In step (3) and step (4), the gas introduced during hot isostatic pressing is an inert gas, preferably argon.

[0041] Example 2

[0042] The process is basically the same as Example 1, except that in step (3), the gas pressure is set to 20 MPa and the temperature is set to 635°C.

[0043] Example 3

[0044] The process is basically the same as Example 1, except that in step (3), the gas pressure is set to 25 MPa and the temperature is set to 635°C.

[0045] Example 4

[0046] The process is basically the same as Example 1, except that in step (3), the gas pressure is set to 25 MPa and the temperature is set to 650°C.

[0047] Example 5

[0048] The method is basically the same as Example 1, except that the treatment time in step (3) is 8 hours.

[0049] Example 6

[0050] The method is basically the same as Example 1, except that no sandblasting is performed in step (1).

[0051] Example 7

[0052] The method is basically the same as Example 1, except that the chromium powder in step (2) is 200 mesh.

[0053] Example 8

[0054] The method is basically the same as Example 1, except that the chromium powder in step (2) is 400 mesh.

[0055] Comparative Example 1

[0056] Basically the same as Example 1, except that step (3) is not performed and the gas pressure in step (4) is 20 MPa.

[0057] Comparative Example 2

[0058] It is basically the same as Example 1, except that in step (3), the preforming temperature is 600°C.

[0059] Comparative Example 3

[0060] It is basically the same as Example 1, except that in step (3), the preforming temperature is 700°C.

[0061] Comparative Example 4

[0062] The method is basically the same as Example 1, except that in step (3), the preforming is performed at a temperature of 640° C. for 3 hours.

[0063] Comparative Example 5

[0064] Basically the same as Example 1, except that step (3) is not performed and the gas pressure in step (4) is 60 MPa.

[0065] Comparative Example 6

[0066] Basically the same as Example 1, except that step (3) is not performed and the gas pressure in step (4) is 100 MPa.

[0067] The tubular targets prepared by the preparation methods described in Examples 1-8 and Comparative Examples 1-5 were tested for performance, and the results are shown in Table 1.

[0068] Table 1

[0069]

[0070] Result analysis: From the above results, it can be seen that the present invention adds a 635-650℃ constant temperature platform to preform the chromium rotary target, and then performs hot isostatic pressing under low pressure and high temperature environment to prepare the chromium rotary target with high relative density and bonding strength, and small deformation. From the results of Examples 1-4 and Comparative Example 1, it can be seen that under low pressure environment, the preformed chromium rotary target has higher density, smaller deformation and higher bonding strength. From the results of Examples 1-5 and Comparative Examples 2-4, it can be seen that the preforming temperature set by the present invention is 635-650℃, and the processing time is 6-8h, which can further improve the density of the target. If the processing time is too long, the bonding strength will increase, but the deformation of the target will increase; if the processing time is too short, the preforming effect cannot be achieved, so in the subsequent process, the deformation will also be very large. From the results of Examples 1-4 and Examples 6-8, it can be seen that the sandblasting treatment selected by the present invention on the back tube can improve the bonding strength between Cr and the back tube, and the density of the target can be improved by selecting the particle size. From the results of Examples 1-4 and Comparative Examples 5 and 6, it can be seen that when hot isostatic pressing is performed directly without pretreatment, a higher gas pressure can produce a chromium rotating target with a relatively high relative density, but the deformation of the prepared target is larger.

[0071] In summary, the present invention performs hot isostatic pressing in a low-pressure environment, and adds a constant temperature platform with a temperature of 635-650°C during the hot isostatic pressing process to pre-form the target material, and then performs hot isostatic pressing at a temperature of 1100-1300°C to improve the densification of the chromium powder. Through such a design, the deformation direction of the entire target material can be controlled, the deformation amount of the target material can be reduced, and the density of the target material can be improved.

Claims

1. A method for preparing a chromium rotating target, characterized in that: The following steps are involved: (1) Processing spiral patterns and sandblasting on the outer diameter surface of the back tube; (2) welding the bottom surface of the back tube and the sleeve to form a cavity between the back tube and the sleeve, adding chromium powder into the cavity, welding the upper surface of the back tube and the sleeve, and then degassing, dehydrating and vacuuming in sequence; (3) Place in hot isostatic pressing equipment, set the air pressure to 20-25 MPa, the temperature to 635-650°C, and process for 6-8 hours for preforming; (4) In a hot isostatic pressing device, maintain the gas pressure in step (3), set the temperature to 1100-1300°C, and continue hot isostatic pressing for 6-8 hours; (5) Annealing; The chromium powder is a non-spherical powder with a D50 of 200-400 meshes.

2. The method for preparing a chromium rotary target according to claim 1, characterized in that: In the step (1), the cross section of the thread is an equilateral triangle of 0.5 mm to 0.8 mm, and the thread pitch is 3 to 5 mm.

3. The method for preparing a chromium rotary target according to claim 1, characterized in that: The surface roughness of the back tube after sandblasting in the step (1) is Ra6-10 μm.

4. The method for preparing a chromium rotary target according to claim 1, characterized in that: The degassing and dehydration temperature in step (3) is 280-310°C and the time is 6-8h.

5. The method for preparing a chromium rotary target according to claim 1, characterized in that: The method also includes the step of machining the chromium target after annealing.

6. The method for preparing a chromium rotary target according to claim 1, characterized in that: The cooling rate of annealing in step (5) is 2-3°C / min.

7. The method for preparing a chromium rotary target according to claim 1, characterized in that: The material of the sheath is 45 carbon steel; the material of the back tube is stainless steel.

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