A method for preparing an ultra-high nickel-containing target material

Abstract

This invention provides a method for preparing ultra-high nickel content target materials. The method includes the following steps: unidirectional upsetting of a preheated billet to obtain a forged billet; heat treatment of the forged billet to obtain a heated billet; hot rolling of the heated billet, followed by annealing after cooling, to obtain the ultra-high nickel content target material. This invention provides a method for stably and reliably producing high-purity nickel target materials with highly uniform microstructure and precisely controllable grain size, overcoming the defects of existing technologies such as uneven microstructure, poor dimensional controllability, high process risk, or high energy consumption.

Description

Technical Field

[0001] This invention relates to the fields of metal material processing and electronic information material manufacturing technology, and in particular to a method for preparing an ultra-high nickel content target. Background Technology

[0002] High-purity nickel sputtering targets are crucial materials for fabricating metal interconnect layers and electrodes in the semiconductor chip and flat panel display industries. The microstructure of the target, especially the grain size and uniformity, directly determines the quality and performance of the sputtered film. Grain inhomogeneity leads to unstable sputtering rates, uneven film thickness, and is prone to arcing and particulate contamination, severely reducing the yield of the final product.

[0003] CN114000073A discloses a process for improving the internal structure of high-purity nickel sputtering targets, including sequential forging and stretching treatment, a first heat treatment, hot rolling treatment, and a second heat treatment on the billet. The hot rolling temperature is extremely high (890-930℃), while the "second heat treatment" temperature is extremely low (495-505℃), far below the recrystallization temperature of pure nickel (above approximately 600℃). Its function is only to relieve stress through annealing, rather than recrystallization or grain growth annealing. Therefore, the final annealing still results in a fine-grained structure similar to that obtained after hot rolling, and it does not have the ability to obtain large grains of 100µm or more (100-200µm).

[0004] CN117568765A discloses a method for preparing nickel targets for magnetron sputtering. This method uses vacuum induction melting to prepare high-purity nickel ingots, followed by hot and cold deformation processing under suitable conditions. The nickel target billet is then vacuum annealed, and finally machined to obtain a high-performance nickel target with the required microstructure and magnetic properties. This method relies on cold rolling with a large deformation of over 80% to introduce extremely high energy storage, followed by recrystallization annealing at medium to low temperatures (400-800℃). Essentially, this promotes a high nucleation rate to obtain a fine-grained structure (≤50µm). However, if this path is followed to obtain large grains by simply increasing the final annealing temperature, the unavoidable inhomogeneity of deformation will lead to uneven energy distribution, causing abnormal grain growth and failing to achieve the homogenization target.

[0005] Currently, the industry uses a combination of thermomechanical treatment (such as forging and rolling) and annealing to control the grain structure of nickel sputtering targets. Existing technologies can already achieve relatively mature fine-grained structures with grain sizes below 100 μm through a process of large deformation and low-temperature recrystallization. However, with the development of specific high-end applications (such as certain processes requiring low resistivity and high step coverage), there is a clear demand for nickel sputtering targets with grain sizes of 100-200 micrometers (e.g., 100-140 micrometers) and highly uniform microstructure. Obtaining such a large and uniform microstructure faces technical challenges such as a narrow process window and the ease with which uniformity can be lost.

[0006] Therefore, developing a high-purity nickel target preparation technology that can stably obtain large-sized and highly uniform grains has become a key technical challenge that urgently needs to be overcome in this field. Summary of the Invention

[0007] In view of the problems existing in the prior art, the present invention provides a method for preparing ultra-high nickel content targets, which can stably and reliably produce high-purity nickel targets with highly uniform microstructure and precise controllable grain size, so as to overcome the defects of the prior art such as uneven microstructure, poor size controllability, high process risk or high energy consumption.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] This invention provides a method for preparing an ultra-high nickel content target, the method comprising the following steps:

[0010] The preheated billet is then subjected to unidirectional upsetting to obtain a forging billet;

[0011] The forged billet is heat-treated to obtain a heated billet;

[0012] The heated billet is hot-rolled, cooled, and then annealed to obtain the ultra-high nickel content target material.

[0013] This invention uses unidirectional forging to forge the billet, which can eliminate casting defects such as porosity and cracks inside the ingot, and crush the large grains of the original ingot, laying the foundation for uniform grains in subsequent processing.

[0014] As a preferred technical solution of the present invention, the preheating temperature is 800-1000℃, for example, it can be 800℃, 820℃, 840℃, 860℃, 880℃, 900℃, 920℃, 940℃, 960℃, 980℃ or 900℃, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0015] Preferably, the preheating time is 5-30 min, for example, it can be 5 min, 10 min, 15 min, 20 min, 25 min or 30 min, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0016] As a preferred technical solution of the present invention, the number of times the unidirectional pier is pulled is 2-4 times, for example, it can be 2 times, 3 times or 4 times, but it is not limited to the listed values. Other unlisted values ​​within the value range are also applicable.

[0017] Preferably, the deformation amount of each unidirectional pier pull is 40%-60%, for example, it can be 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58% or 60%, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0018] As a preferred technical solution of the present invention, the forging billet is 60%-80% of the original height, for example, it can be 60%, 62%, 64%, 66%, 68%, 70%, 72%, 74%, 76%, 78% or 80%, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0019] As a preferred technical solution of the present invention, the temperature of the heat treatment is 600-800℃, for example, it can be 600℃, 620℃, 640℃, 660℃, 680℃, 700℃, 720℃, 740℃, 760℃, 780℃ or 800℃, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0020] This invention involves hot rolling in a low-temperature range. This low-temperature rolling not only avoids the risk of cracking, but more importantly, it can form a deformed structure with a more uniform energy storage distribution, laying the foundation for obtaining a uniform recrystallized structure in the future. This is in stark contrast to the disadvantage of traditional high-temperature hot rolling, which easily leads to uneven structure.

[0021] As a preferred technical solution of the present invention, the heat treatment time is 30-90 min, for example, it can be 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, 65 min, 70 min, 75 min, 80 min, 85 min or 90 min, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0022] As a preferred technical solution of the present invention, the deformation amount of the hot rolling is 60%-80%, for example, it can be 60%, 62%, 64%, 66%, 68%, 70%, 72%, 74%, 76%, 78% or 80%, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0023] As a preferred technical solution of the present invention, the cooling includes water cooling.

[0024] As a preferred technical solution of the present invention, the annealing temperature is 600-700℃, for example, it can be 600℃, 620℃, 640℃, 660℃, 680℃ or 700℃, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0025] As a preferred technical solution of the present invention, the annealing time is 30-120 min, for example, it can be 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 110 min or 120 min, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0026] By combining a short process of "low-temperature hot rolling" with "specific low-temperature annealing", a high-purity nickel target with uniform grain size of 100-200 μm was successfully prepared.

[0027] Compared with existing technical solutions, the present invention has at least the following beneficial effects:

[0028] This invention employs a process of "low-temperature hot rolling + water cooling + specific low-temperature annealing". Low-temperature hot rolling (600-800℃) lays the foundation for a uniform microstructure. Then, by controlling the path of the final annealing process, it bypasses the traditional complex process and directly and stably prepares high-purity nickel targets with an average grain size of 100-200um and a highly uniform microstructure (density of 99%). Detailed Implementation

[0029] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0030] In one specific embodiment, the present invention provides a method for preparing an ultra-high nickel content target material, the method comprising the following steps:

[0031] The smelted billet is preheated in a heat treatment furnace for 5-30 minutes at a temperature of 800-1000℃.

[0032] The preheated billet is forged to 60%-80% of the original billet height, with 2-4 unidirectional upsetting and drawing processes in between, each with a deformation of 40%-60%, followed by water cooling.

[0033] The hot-forged billet is subjected to heat treatment at a temperature of 600-800℃ for 30-90 minutes.

[0034] After the heat preservation is completed, the billet is directly rolled, with a hot rolling deformation of 60%-80%, and then water-cooled.

[0035] The hot-rolled billet undergoes final heat treatment at a temperature of 600-700℃ for 30-120 minutes.

[0036] It should be clarified that any use of the process provided in the embodiments of the present invention or any substitution or change of conventional data falls within the protection and disclosure scope of the present invention.

[0037] Example 1

[0038] This embodiment provides a method for preparing an ultra-high nickel content target, the method comprising the following steps:

[0039] The smelted billet is preheated in a heat treatment furnace for 20 minutes at a temperature of 900℃.

[0040] The preheated billet is forged to 70% of the original billet height, with three unidirectional upsetting and drawing operations each with a deformation of 50%, followed by water cooling.

[0041] The hot-forged billet is subjected to heat treatment at 700℃ for 60 minutes.

[0042] The billet after the heat preservation is completed is directly rolled, with a hot rolling deformation of 70%, and then water cooled.

[0043] The hot-rolled billet is subjected to final heat treatment at a temperature of 650℃ for 80 minutes.

[0044] Example 2

[0045] This embodiment provides a method for preparing an ultra-high nickel content target, the method comprising the following steps:

[0046] The smelted billet is preheated in a heat treatment furnace for 30 minutes at a temperature of 800℃.

[0047] The preheated billet is forged to 80% of the original billet height, with four unidirectional upsetting and drawing operations each with a deformation of 60%, followed by water cooling.

[0048] The hot-forged billet is subjected to heat treatment at a temperature of 600℃ for 90 minutes.

[0049] The billet after the heat preservation is completed is directly rolled, with a hot rolling deformation of 60%, and then water cooled.

[0050] The hot-rolled billet is subjected to final heat treatment at a temperature of 700℃ for 30 minutes.

[0051] Example 3

[0052] This embodiment provides a method for preparing an ultra-high nickel content target, the method comprising the following steps:

[0053] The smelted billet is preheated in a heat treatment furnace for 5 minutes at a temperature of 1000℃.

[0054] The preheated billet is forged to 60% of the original billet height, with two unidirectional upsetting and drawing operations each with a deformation of 40%, followed by water cooling.

[0055] The hot-forged billet is subjected to heat treatment at 800℃ for 30 minutes.

[0056] After the heat preservation is completed, the billet is directly rolled with a hot rolling deformation of 80% and then water cooled.

[0057] The hot-rolled billet is subjected to final heat treatment at a temperature of 600℃ for 120 minutes.

[0058] Example 4

[0059] This embodiment provides a method for preparing an ultra-high nickel content target. The only difference between this method and Example 1 is that the heat treatment temperature is adjusted to 550°C, while the rest is the same as in Example 1.

[0060] Example 5

[0061] This embodiment provides a method for preparing an ultra-high nickel content target. The only difference between this method and Example 1 is that the heat treatment temperature is adjusted to 850°C, while the rest is the same as in Example 1.

[0062] Example 6

[0063] This embodiment provides a method for preparing an ultra-high nickel content target. The only difference between this method and Example 1 is that the annealing temperature is adjusted to 550°C, while the rest is the same as in Example 1.

[0064] Example 7

[0065] This embodiment provides a method for preparing an ultra-high nickel content target. The only difference between this method and Example 1 is that the annealing temperature is adjusted to 750°C, while the rest is the same as in Example 1.

[0066] Performance testing

[0067] The performance of the ultra-high nickel content targets provided in the examples and comparative examples was tested, and the results are shown in Table 1.

[0068] Table 1

[0069]

[0070] As shown in Table 1, the hot rolling process of this invention, performed at a low temperature, not only avoids the risk of cracking but, more importantly, forms a deformed microstructure with a more uniform energy distribution. This lays an ideal foundation for obtaining a uniform recrystallized microstructure, which contrasts sharply with the disadvantage of traditional high-temperature hot rolling, which easily leads to uneven microstructure. Through this short-process combination of "low-temperature hot rolling" and "specific low-temperature annealing," high-purity nickel targets with uniform grain sizes of 100-200 μm were successfully prepared.

[0071] A comprehensive comparison of Examples 1 and 4-7 shows that if the heat treatment temperature is too low, it is easy to cause difficulties in the processing of the target material, resulting in cracking. If the heat treatment temperature is too high, it is impossible to provide a basis for uniform microstructure, and it is difficult to achieve the purpose of uniform microstructure by annealing alone. If the annealing temperature is higher, the grains will be larger. If the temperature is too low, the grains will be too small, and it is easy to cause uneven distribution of target material microstructure, thereby reducing the quality of the target material.

[0072] The present invention has been illustrated with the above embodiments to illustrate its detailed structural features. However, the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the components used in the present invention, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing an ultra-high nickel content target, characterized in that, The preparation method includes the following steps: The preheated billet is then subjected to unidirectional upsetting to obtain a forging billet. The forged billet is heat-treated to obtain a heated billet; The heated billet is hot-rolled, cooled, and then annealed to obtain the ultra-high nickel content target material.

2. The preparation method according to claim 1, characterized in that, The preheating temperature is 800-1000℃; Preferably, the preheating time is 5-30 minutes.

3. The preparation method according to claim 1 or 2, characterized in that, The number of times the unidirectional pier is pulled is 2-4 times; Preferably, the deformation amount of each unidirectional pier pull is 40%-60%.

4. The preparation method according to any one of claims 1 to 3, characterized in that, The forging billet is 60%-80% of its original height.

5. The preparation method according to any one of claims 1 to 4, characterized in that, The heat treatment temperature is 600-800℃.

6. The preparation method according to any one of claims 1 to 5, characterized in that, The heat treatment time is 30-90 minutes.

7. The preparation method according to any one of claims 1 to 6, characterized in that, The deformation of the hot rolling is 60%-80%.

8. The preparation method according to any one of claims 1 to 7, characterized in that, The cooling includes water cooling.

9. The preparation method according to any one of claims 1 to 8, characterized in that, The annealing temperature is 600-700℃.

10. The preparation method according to any one of claims 1 to 9, characterized in that, The annealing process takes 30-120 minutes.

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