A method for preparing a tantalum target blank with high uniformity of tissue texture

Abstract

This invention discloses a method for preparing a tantalum target blank with highly uniform microstructure. The method includes: sequentially forging high-purity tantalum melted by electron beam through a first forging, a second forging, and a third forging; then performing a first cross-rolling on the high-purity tantalum after the third forging to obtain an intermediate target blank; finally, averaging the intermediate target blank along its thickness direction and performing a second cross-rolling to obtain the tantalum target blank. The tantalum target blank prepared by the above method has a fine microstructure and uniform orientation distribution. Along the thickness direction of the tantalum target blank, the average grain size is ≤60μm, the {100} texture accounts for ≥35%, and the {111} texture accounts for ≤30%. Furthermore, the prepared tantalum target blank has a diameter ≥500mm and a thickness ≥10mm, which can meet the sputtering coating requirements of 12-inch wafers.

Description

Technical Field

[0001] This invention belongs to the field of sputtering target preparation technology, specifically relating to a method for preparing a tantalum target blank with highly uniform microstructure and texture. Background Technology

[0002] The semiconductor industry is a strategic, fundamental, and pioneering industry for national economic and social development. In recent years, driven by the market, supported by policies, and under external pressure, my country's semiconductor industry has developed rapidly and its overall strength has significantly improved. Tantalum targets are widely used in large-scale semiconductor industries as sputtering thin film materials for diffusion barrier layers in silicon chip and copper interconnect processes. The technology of tantalum targets for semiconductors has high requirements and is difficult to prepare. Three key technologies need to be overcome in the preparation process: (1) purity ≥ 99.995% (4N5); (2) average grain size ≤ 80μm; (3) uniform distribution of the three textures {100}, {111}, and {110} without obvious texture bands. However, during the rolling process, tantalum targets are prone to forming a texture gradient in the thickness direction, with the surface layer dominated by {100} texture and the core dominated by {111} texture. Among them, the sputtering rate of {111} texture is the slowest, which affects the production efficiency and the uniformity of film thickness, and thus affects the performance of semiconductor devices.

[0003] CN117144308A discloses a method for preparing tantalum target blanks using DS continuous rolling. This method simplifies the process by continuously rolling the tantalum target blank with multiple work rolls of different diameters, reducing the proportion of {111} texture and achieving a uniform distribution of {100} and {111} textures. However, this method places excessive demands on equipment, requiring multiple high-precision rolling mills to operate simultaneously. Furthermore, the tantalum target blanks prepared by this method have relatively small thicknesses, making it difficult to meet the industrial production requirements of tantalum target blanks. CN115029668B discloses a method for preparing high-performance tantalum sputtering targets using stack rolling. This method uses electron beam welding to fix two intermediate tantalum target blanks and performs cumulative cross-stack rolling. Although it obtains tantalum targets with uniform texture distribution, it requires high flatness of the intermediate tantalum target blanks, and the weld joints are prone to cracking during rolling, adversely affecting the stability of industrial production. There is an urgent need to propose a method for preparing tantalum target blanks with highly uniform texture to meet industrial production requirements. Summary of the Invention

[0004] The technical problem to be solved by this invention is to address the shortcomings of the prior art by providing a method for preparing a tantalum target blank with high uniformity of microstructure and texture. This method, through controlling the deformation during forging and rolling processes and employing stepped annealing, results in a tantalum target blank with a fine average grain size, uniform texture distribution, high {100} texture ratio, and low {111} texture ratio, meeting the process requirements for 12-inch wafer sputtering deposition.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for preparing a tantalum target blank with highly uniform microstructure, characterized by comprising the following steps:

[0006] Step 1, First Forging: The high-purity tantalum after electron beam melting is forged once on a hydraulic press, and then subjected to high-temperature annealing.

[0007] Step 2, Secondary Forging: The high-purity tantalum after high-temperature annealing in Step 1 is forged a second time, and then subjected to medium-temperature annealing.

[0008] Step 3, Three-time forging: The high-purity tantalum after the medium-temperature annealing treatment in Step 2 is forged three times, and then subjected to low-temperature annealing treatment;

[0009] Step 4, One-time cross rolling: The high-purity tantalum after low-temperature annealing in Step 3 is cross-rolled once on a rolling mill, and then subjected to medium-temperature short-time annealing to obtain an intermediate target billet;

[0010] Step 5, intermediate target blank cutting: The intermediate target blank described in Step 4 is wire-cut along 1 / 2 of its thickness, and the intermediate target blank is cut into two groups on average.

[0011] Step 6, Secondary Cross Rolling: The intermediate target billet cut in Step 5 is subjected to secondary cross rolling, and then subjected to low-temperature long-time annealing to obtain tantalum target billet.

[0012] The above-mentioned method for preparing a highly uniform tantalum target blank is characterized in that the purity of the high-purity tantalum in step one is 5N, and the tonnage of the hydraulic press is 2000T.

[0013] The above-mentioned method for preparing a tantalum target blank with highly uniform microstructure is characterized in that the specific process of the forging in step one includes: upsetting the high-purity tantalum along the axial direction to 1 / 2 of its original height in multiple passes, followed by drawing it to its original height in multiple passes. Each pass of upsetting and drawing involves large deformation, with each pass having a deformation amount of 18% to 20%. The high-temperature annealing treatment in step one is performed at a temperature of 1220℃ to 1280℃ and a holding time of 1 hour.

[0014] The above-mentioned method for preparing a tantalum target blank with high uniformity of microstructure is characterized in that the specific process of secondary forging in step two includes: upsetting high-purity tantalum in multiple passes along the axial direction to 1 / 2 of the original height, followed by multiple draw-out passes to the original height, wherein each pass of upsetting and draw-out is a medium deformation, and the deformation amount per pass is 12% to 13%; the temperature of the medium-temperature annealing treatment in step two is 1120℃ to 1180℃, and the holding time is 1h.

[0015] The above-mentioned method for preparing a tantalum target blank with high uniformity of microstructure is characterized in that the specific process of the three forgings in step three includes: upsetting the high-purity tantalum along the axial direction to 1 / 2 of its original height in multiple passes, and then drawing it to its original height in multiple passes. Each pass of upsetting and drawing has a small deformation, and the deformation amount of each pass is 8% to 10%. The temperature of the low-temperature annealing treatment in step three is 1020℃ to 1080℃, and the holding time is 1h.

[0016] The method for preparing a highly uniform tantalum target billet with the above-mentioned structure is characterized in that the roll diameter of the rolling mill in step four is 400mm to 600mm.

[0017] The above-mentioned method for preparing a highly uniform tantalum target billet is characterized in that the specific process of the single cross rolling in step four includes: after each rolling pass, the high-purity tantalum is rotated 90° clockwise along the normal direction for the next rolling pass, each pass has a large deformation, the deformation amount is 14% to 16%, and the total deformation amount of the single cross rolling is 45% to 50%; the temperature of the medium-temperature short-time annealing treatment in step four is 1120℃ to 1180℃, and the holding time is 20min to 40min.

[0018] The above-mentioned method for preparing a tantalum target blank with highly uniform microstructure is characterized in that the wire cutting process in step five should ensure that the cutting surface is smooth and burr-free.

[0019] The above-mentioned method for preparing a tantalum target blank with highly uniform texture is characterized in that the specific process of the secondary cross rolling in step six includes: after each rolling pass, the intermediate target blank is rotated 90° clockwise along the normal direction for the next rolling pass, each pass is a small deformation, the deformation amount is 8% to 10%, and the total deformation amount of the secondary cross rolling is 50% to 60%; the temperature of the low-temperature long-time annealing treatment in step six is ​​1020℃ to 1080℃, and the holding time is 1.5h to 2.5h.

[0020] The above-mentioned method for preparing a tantalum target blank with high uniformity of microstructure and texture is characterized in that, in step six, the microstructure and texture of the tantalum target blank are uniformly distributed, with an average grain size ≤60μm, a {100} texture ratio ≥35%, and a {111} texture ratio ≤30%; the diameter of the tantalum target blank is ≥500mm and the thickness is ≥10mm.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] 1. High-purity tantalum cores after electron beam melting have coarse microstructures, requiring multiple forging processes to break down the core grains. During the drawing process of high-purity tantalum, the edges experience large deformation and good fluidity, while the core experiences small deformation and poor fluidity, making it prone to "core shrinkage" defects during forging. This invention employs a staged forging and annealing process. Large deformation amounts in each pass of the first forging stage are beneficial for core stress, transferring deformation to the core and causing large core grains to break down, thereby reducing macroscopic defects such as "core shrinkage." High-temperature annealing after the first forging stage completely eliminates deformed grains, allowing them to fully recrystallize. Small to medium deformation amounts in each pass of the second and third forging stages reduce macroscopic crack defects caused by stress concentration during forging. Medium-to-low temperature annealing after the second and third forging stages helps slow down excessive grain growth and refine grain size.

[0023] 2. Conventional rolling methods easily induce severe {111} texture in the core of high-purity tantalum. This invention employs cross-rolling, which can weaken the {111} texture in the core to a certain extent. The larger deformation per pass in each cross-rolling pass facilitates deeper penetration of the rolling force into the core, and subsequent medium-temperature short-time annealing prevents grain growth. An intermediate target billet is diced at half its thickness, transforming the core position into an edge position after dicing. This ensures consistent uniformity between the edge and core microstructures after the second cross-rolling. Low-temperature long-time annealing after the second cross-rolling allows the rolled grains to recrystallize via subcrystalline nucleation, thereby suppressing the formation of {111} recrystallization texture and retaining more {100} recrystallization texture.

[0024] 3. By controlling key parameters such as deformation and annealing temperature during the processing and employing an intermediate target blank slicing method, the present invention produces a tantalum target blank with fine microstructure and uniform texture distribution. The {100} texture accounts for ≥35% and the {111} texture accounts for ≤30%. The average grain size along the thickness direction of the tantalum target blank is ≤60μm. Furthermore, the prepared tantalum target blank has a diameter ≥500mm and a thickness ≥10mm, which can meet the sputtering coating requirements of 12-inch wafers.

[0025] 4. The method of the present invention is not limited by equipment, has high production efficiency, can be used for mass production of tantalum target blanks, and produces tantalum target blanks with few macroscopic defects and processing waste, with defects and waste accounting for less than 5%, resulting in a high yield and significantly reducing production costs.

[0026] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the preparation process of the tantalum target blank of the present invention.

[0028] Figure 2 This is a statistical chart of the average grain size of the tantalum target blanks prepared in Examples 1 to 6 of the present invention.

[0029] Figure 3 This is an orientation distribution diagram of the edge of the tantalum target blank prepared in Example 1 of the present invention along the thickness direction.

[0030] Figure 4 This is an orientation distribution diagram of the center of the tantalum target blank prepared in Example 1 of the present invention along the thickness direction.

[0031] Figure 5 This is an orientation distribution diagram of the edge of the tantalum target blank prepared in Example 2 of the present invention along the thickness direction.

[0032] Figure 6 This is an orientation distribution diagram of the center of the tantalum target blank prepared in Example 2 of the present invention along the thickness direction. Detailed Implementation

[0033] A schematic flowchart of the method for preparing the highly uniform tantalum target preform of the present invention is shown below. Figure 1 As shown, the process includes: forging high-purity tantalum melted by electron beam in sequence through a first forging, a second forging, and a third forging; then, performing a cross-rolling on the high-purity tantalum after the third forging to obtain an intermediate target billet; finally, slicing the intermediate target billet evenly along the thickness direction and performing a second cross-rolling to obtain a tantalum target billet.

[0034] Example 1

[0035] This embodiment provides a method for preparing a tantalum target preform with highly uniform microstructure, comprising the following steps:

[0036] Step 1, Primary Forging: The high-purity tantalum, after electron beam melting, is forged on a hydraulic press. After primary forging, the high-purity tantalum undergoes high-temperature annealing. The purity of the high-purity tantalum is 5N. The tonnage of the hydraulic press is 2000T. The specific process of primary forging is as follows: the high-purity tantalum is upset along the axial direction in multiple passes to half its original height, followed by multiple draw-out passes to its original height. Each pass of upsetting and drawing involves large deformation, with a deformation amount of 18% per pass. The high-temperature annealing temperature is 1220℃, and the holding time is 1 hour.

[0037] Step 2, Secondary Forging: The high-purity tantalum after high-temperature annealing in Step 1 is subjected to secondary forging. After secondary forging, the high-purity tantalum is subjected to medium-temperature annealing. The specific process of secondary forging is as follows: the high-purity tantalum is upsetting along the axial direction to 1 / 2 of its original height in multiple passes, and then drawn back to its original height in multiple passes. Each pass of upsetting and drawing is a medium deformation, and the deformation amount per pass is 12%. The temperature of the medium-temperature annealing treatment is 1120℃, and the holding time is 1 hour.

[0038] Step 3, Three-stage forging: The high-purity tantalum after the medium-temperature annealing in Step 2 is forged three times. After the three forgings are completed, the high-purity tantalum is subjected to low-temperature annealing. The specific process of the three-stage forging is as follows: the high-purity tantalum is upsetting along the axial direction to 1 / 2 of its original height in multiple passes, and then drawing back to its original height in multiple passes. Each pass of upsetting and drawing has a small deformation, and the deformation amount per pass is 8%. The temperature of the low-temperature annealing is 1020℃, and the holding time is 1 hour.

[0039] Step 4, One-time cross rolling: The high-purity tantalum after low-temperature annealing in Step 3 is subjected to one-time cross rolling on a rolling mill. After the one-time cross rolling, the high-purity tantalum is subjected to medium-temperature short-time annealing to obtain an intermediate target billet. The roll diameter of the rolling mill is 400mm. The specific process of the one-time cross rolling is as follows: after each rolling pass, the high-purity tantalum is rotated 90° clockwise along the normal direction for the next rolling pass. Each pass has a large deformation, with a pass deformation of 14%, and the total deformation of the one-time cross rolling is 45%. The temperature of the medium-temperature short-time annealing is 1120℃, and the holding time is 20min.

[0040] Step 5, intermediate target blank cutting: The intermediate target blank described in Step 4 is wire-cut along 1 / 2 of its thickness, dividing the intermediate target blank into two groups on average; the wire-cutting process should ensure that the cut surface is smooth and burr-free;

[0041] Step Six: Secondary Cross Rolling: The intermediate target billet cut in Step Five is subjected to secondary cross rolling. After secondary cross rolling, the intermediate target billet undergoes low-temperature long-time annealing to obtain a tantalum target billet. The specific process of secondary cross rolling is as follows: after each rolling pass, the intermediate target billet is rotated 90° clockwise along the normal direction for the next rolling pass. Each pass has a small deformation, with a deformation amount of 8% per pass, and the total deformation amount of the secondary cross rolling is 50%. The temperature of the low-temperature long-time annealing is 1020℃, and the holding time is 1.5h. The diameter of the tantalum target billet is ≥500mm, the thickness is ≥10mm, and the proportion of defects and scrap is <5%.

[0042] The proportions of {100} and {111} textures in the tantalum target blanks prepared in Example 1 are shown in Table 1. It can be seen that the {100} texture accounts for 40%, and the {111} texture accounts for 21%. The average grain size statistics of the tantalum target blanks are shown in [Table 1]. Figure 2 It can be seen that the average grain size is 55.2 μm. Figure 3 and Figure 4 The images show the orientation distribution of the tantalum target blank along the thickness direction at its edge and center in Example 1. It can be seen that the {100} and {111} orientations are uniformly distributed along the thickness direction at both the edge and center, with no textured bands formed. The prepared tantalum target blank can meet the sputtering coating requirements of a 12-inch wafer.

[0043] Example 2

[0044] This embodiment provides a method for preparing a tantalum target preform with highly uniform microstructure, comprising the following steps:

[0045] Step 1, Primary Forging: The high-purity tantalum, after electron beam melting, is forged on a hydraulic press. After the primary forging, the high-purity tantalum undergoes high-temperature annealing. The purity of the high-purity tantalum is 5N. The tonnage of the hydraulic press is 2000T. The specific process of the primary forging is as follows: the high-purity tantalum is upset along the axial direction in multiple passes to half of its original height, followed by multiple draw-out passes to the original height. Each pass of upsetting and drawing involves large deformation, with a deformation amount of 18% per pass. The high-temperature annealing temperature is 1250℃, and the holding time is 1 hour.

[0046] Step 2, Secondary Forging: The high-purity tantalum after high-temperature annealing in Step 1 is subjected to secondary forging. After secondary forging, the high-purity tantalum is subjected to medium-temperature annealing. The specific process of secondary forging is as follows: the high-purity tantalum is upsetting along the axial direction to 1 / 2 of its original height in multiple passes, and then drawn back to its original height in multiple passes. Each pass of upsetting and drawing is a medium deformation, and the deformation amount per pass is 12%. The temperature of the medium-temperature annealing treatment is 1140℃, and the holding time is 1 hour.

[0047] Step 3, Three-stage forging: The high-purity tantalum after the medium-temperature annealing in Step 2 is forged three times. After the three forgings are completed, the high-purity tantalum is subjected to low-temperature annealing. The specific process of the three-stage forging is as follows: the high-purity tantalum is upsetting along the axial direction to 1 / 2 of its original height in multiple passes, and then drawn back to its original height in multiple passes. Each pass of upsetting and drawing has a small deformation, and the deformation amount per pass is 8%. The temperature of the low-temperature annealing is 1060℃, and the holding time is 1 hour.

[0048] Step 4, One-time cross rolling: The high-purity tantalum after low-temperature annealing in Step 3 is subjected to one-time cross rolling on a rolling mill. After the one-time cross rolling, the high-purity tantalum is subjected to medium-temperature short-time annealing to obtain an intermediate target billet. The roll diameter of the rolling mill is 400mm. The specific process of the one-time cross rolling is as follows: after each rolling pass, the high-purity tantalum is rotated 90° clockwise along the normal direction for the next rolling pass. Each pass has a large deformation, with a pass deformation of 14%, and the total deformation of the one-time cross rolling is 48%. The temperature of the medium-temperature short-time annealing is 1140℃, and the holding time is 30min.

[0049] Step 5, intermediate target blank cutting: The intermediate target blank described in Step 4 is wire-cut along 1 / 2 of its thickness, and the intermediate target blank is cut into two groups on average; the cutting surface should be smooth and burr-free during the wire cutting process.

[0050] Step Six: Secondary Cross Rolling: The intermediate target billet cut in Step Five is subjected to secondary cross rolling. After secondary cross rolling, the intermediate target billet undergoes low-temperature long-time annealing to obtain a tantalum target billet. The specific process of secondary cross rolling is as follows: after each rolling pass, the intermediate target billet is rotated 90° clockwise along the normal direction for the next rolling pass. Each pass has a small deformation, with a pass deformation of 9%, and the total deformation of the secondary cross rolling is 53%. The temperature of the low-temperature long-time annealing is 1060℃, and the holding time is 1.5h. The diameter of the tantalum target billet is ≥500mm, the thickness is ≥10mm, and the proportion of defects and scrap is <5%.

[0051] The proportions of {100} and {111} textures in the tantalum target blanks prepared in Example 2 are shown in Table 1. It can be seen that the {100} texture accounts for 44%, and the {111} texture accounts for 26%. The average grain size statistics of the tantalum target blanks are shown in [Table 1]. Figure 2 The average grain size is 41.3 μm. Figure 5 and Figure 6 The images show the orientation distribution of the tantalum target blank along the thickness direction at its edge and center in Example 2. It can be seen that the {100} and {111} orientations are uniformly distributed along the thickness direction at both the edge and center, with no textured bands formed. The prepared tantalum target blank can meet the sputtering coating requirements of a 12-inch wafer.

[0052] Example 3

[0053] This embodiment provides a method for preparing a tantalum target preform with highly uniform microstructure, comprising the following steps:

[0054] Step 1, Primary Forging: The high-purity tantalum, after electron beam melting, is forged on a hydraulic press. After primary forging, the high-purity tantalum undergoes high-temperature annealing. The purity of the high-purity tantalum is 5N. The tonnage of the hydraulic press is 2000T. The specific process of primary forging is as follows: the high-purity tantalum is upset along the axial direction in multiple passes to half its original height, followed by multiple draw-out passes to its original height. Each pass of upsetting and drawing involves large deformation, with a deformation amount of 18% per pass. The high-temperature annealing temperature is 1230℃, and the holding time is 1 hour.

[0055] Step 2, Secondary Forging: The high-purity tantalum after high-temperature annealing in Step 1 is subjected to secondary forging. After secondary forging, the high-purity tantalum is subjected to medium-temperature annealing. The specific process of secondary forging is as follows: the high-purity tantalum is upsetting along the axial direction to 1 / 2 of its original height in multiple passes, and then drawn back to its original height in multiple passes. Each pass of upsetting and drawing is a medium deformation, and the deformation amount per pass is 13%. The temperature of the medium-temperature annealing treatment is 1160℃, and the holding time is 1 hour.

[0056] Step 3, Three-stage forging: The high-purity tantalum after the medium-temperature annealing in Step 2 is forged three times. After the three forgings are completed, the high-purity tantalum is subjected to low-temperature annealing. The specific process of the three-stage forging is as follows: the high-purity tantalum is upsetting along the axial direction to 1 / 2 of its original height in multiple passes, and then drawn back to its original height in multiple passes. Each pass of upsetting and drawing has a small deformation, and the deformation amount per pass is 9%. The temperature of the low-temperature annealing is 1030℃, and the holding time is 1 hour.

[0057] Step 4, One-time cross rolling: The high-purity tantalum after low-temperature annealing in Step 3 is subjected to one-time cross rolling on a rolling mill. After the one-time cross rolling, the high-purity tantalum is subjected to medium-temperature short-time annealing to obtain an intermediate target billet. The roll diameter of the rolling mill is 500mm. The specific process of the one-time cross rolling is as follows: after each rolling pass, the high-purity tantalum is rotated 90° clockwise along the normal direction for the next rolling pass. Each pass has a large deformation, with a deformation amount of 15% per pass, and the total deformation amount of the one-time cross rolling is 45%. The temperature of the medium-temperature short-time annealing is 1150℃, and the holding time is 20min.

[0058] Step 5, intermediate target blank cutting: The intermediate target blank described in Step 4 is wire-cut along 1 / 2 of its thickness, dividing the intermediate target blank into two groups on average; the wire-cutting process should ensure that the cut surface is smooth and burr-free;

[0059] Step Six: Secondary Cross Rolling: The intermediate target billet cut in Step Five is subjected to secondary cross rolling. After secondary cross rolling, the intermediate target billet undergoes low-temperature long-time annealing to obtain a tantalum target billet. The specific process of secondary cross rolling is as follows: after each rolling pass, the intermediate target billet is rotated 90° clockwise along the normal direction for the next rolling pass. Each pass has a small deformation, with a pass deformation of 9%, and the total deformation of the secondary cross rolling is 53%. The temperature of the low-temperature long-time annealing is 1060℃, and the holding time is 2 hours. The diameter of the tantalum target billet is ≥500mm, the thickness is ≥10mm, and the proportion of defects and scrap is <5%.

[0060] The proportions of {100} and {111} textures in the tantalum target blanks prepared in Example 3 are shown in Table 1. It can be seen that the {100} texture accounts for 42% and the {111} texture accounts for 18%. The average grain size statistics of the tantalum target blanks are shown in [Table 1]. Figure 2 The average grain size is 47.6 μm. The {100} and {111} orientations are uniformly distributed along the thickness direction at both the edge and center of the tantalum target blank, with no texture bands formed. The prepared tantalum target blank meets the sputtering coating requirements for 12-inch wafers.

[0061] Example 4

[0062] This embodiment provides a method for preparing a tantalum target preform with highly uniform microstructure, comprising the following steps:

[0063] Step 1, Primary Forging: The high-purity tantalum, after electron beam melting, is forged on a hydraulic press. After the primary forging, the high-purity tantalum undergoes high-temperature annealing. The purity of the high-purity tantalum is 5N. The tonnage of the hydraulic press is 2000T. The specific process of the primary forging is as follows: the high-purity tantalum is upset along the axial direction in multiple passes to half its original height, followed by multiple draw-out passes to the original height. Each pass of upsetting and drawing involves large deformation, with a deformation amount of 20% per pass. The high-temperature annealing temperature is 1250℃, and the holding time is 1 hour.

[0064] Step 2, Secondary Forging: The high-purity tantalum after high-temperature annealing in Step 1 is subjected to secondary forging. After secondary forging, the high-purity tantalum is subjected to medium-temperature annealing. The specific process of secondary forging is as follows: the high-purity tantalum is upsetting along the axial direction to 1 / 2 of its original height in multiple passes, and then drawn back to its original height in multiple passes. Each pass of upsetting and drawing is a medium deformation, and the deformation amount per pass is 13%. The temperature of the medium-temperature annealing is 1150℃, and the holding time is 1 hour.

[0065] Step 3, Three-stage forging: The high-purity tantalum after the medium-temperature annealing in Step 2 is forged three times. After the three forgings are completed, the high-purity tantalum is subjected to low-temperature annealing. The specific process of the three-stage forging is as follows: the high-purity tantalum is upsetting along the axial direction to 1 / 2 of its original height in multiple passes, and then drawn back to its original height in multiple passes. Each pass of upsetting and drawing has a small deformation, and the deformation amount per pass is 8%. The temperature of the low-temperature annealing is 1080℃, and the holding time is 1 hour.

[0066] Step 4, One-time cross rolling: The high-purity tantalum after low-temperature annealing in Step 3 is subjected to one-time cross rolling on a rolling mill. After the one-time cross rolling, the high-purity tantalum is subjected to medium-temperature short-time annealing to obtain an intermediate target billet. The roll diameter of the rolling mill is 500mm. The specific process of the one-time cross rolling is as follows: after each rolling pass, the high-purity tantalum is rotated 90° clockwise along the normal direction for the next rolling pass. Each pass has a large deformation, with a deformation amount of 15% per pass, and the total deformation amount of the one-time cross rolling is 48%. The temperature of the medium-temperature short-time annealing is 1160℃, and the holding time is 40min.

[0067] Step 5, intermediate target blank cutting: The intermediate target blank described in Step 4 is wire-cut along 1 / 2 of its thickness, dividing the intermediate target blank into two groups on average; the wire-cutting process should ensure that the cut surface is smooth and burr-free;

[0068] Step Six: Secondary Cross Rolling: The intermediate target billet cut in Step Five is subjected to secondary cross rolling. After secondary cross rolling, the intermediate target billet undergoes low-temperature long-time annealing to obtain a tantalum target billet. The specific process of secondary cross rolling is as follows: after each rolling pass, the intermediate target billet is rotated 90° clockwise along the normal direction for the next rolling pass. Each pass has a small deformation, with a deformation amount of 10% per pass, and the total deformation amount of the secondary cross rolling is 60%. The temperature of the low-temperature long-time annealing is 1080℃, and the holding time is 2 hours. The diameter of the tantalum target billet is ≥500mm, the thickness is ≥10mm, and the proportion of defects and scrap is <5%.

[0069] The proportions of {100} and {111} textures in the tantalum target blanks prepared in Example 4 are shown in Table 1. It can be seen that the {100} texture accounts for 37%, and the {111} texture accounts for 23%. The average grain size statistics of the tantalum target blanks are shown in... Figure 2 The average grain size is 52.1 μm. The {100} and {111} orientations are uniformly distributed along the thickness direction at both the edge and center of the tantalum target blank, with no texture bands formed. The prepared tantalum target blank meets the sputtering coating requirements for 12-inch wafers.

[0070] Example 5

[0071] This embodiment provides a method for preparing a tantalum target preform with highly uniform microstructure, comprising the following steps:

[0072] Step 1, Primary Forging: The high-purity tantalum, after electron beam melting, is forged on a hydraulic press. After primary forging, the high-purity tantalum undergoes high-temperature annealing. The purity of the high-purity tantalum is 5N. The tonnage of the hydraulic press is 2000T. The specific process of primary forging is as follows: the high-purity tantalum is upset along the axial direction in multiple passes to half its original height, followed by multiple draw-out passes to its original height. Each pass of upsetting and drawing involves large deformation, with a deformation amount of 19% per pass. The high-temperature annealing temperature is 1280℃, and the holding time is 1 hour.

[0073] Step 2, Secondary Forging: The high-purity tantalum after high-temperature annealing in Step 1 is subjected to secondary forging. After secondary forging, the high-purity tantalum is subjected to medium-temperature annealing. The specific process of secondary forging is as follows: the high-purity tantalum is upsetting along the axial direction to 1 / 2 of its original height in multiple passes, and then drawn back to its original height in multiple passes. Each pass of upsetting and drawing is a medium deformation, and the deformation amount per pass is 12%. The temperature of the medium-temperature annealing treatment is 1160℃, and the holding time is 1 hour.

[0074] Step 3, Three-stage forging: The high-purity tantalum after the medium-temperature annealing in Step 2 is forged three times. After the three forgings are completed, the high-purity tantalum is annealed at low temperature. The specific process of the three-stage forging is as follows: the high-purity tantalum is upsetting along the axial direction to 1 / 2 of its original height in multiple passes, and then drawn back to its original height in multiple passes. Each pass of upsetting and drawing has a small deformation, and the deformation amount per pass is 10%. The temperature of the low-temperature annealing is 1080℃, and the holding time is 1 hour.

[0075] Step 4, One-time cross rolling: The high-purity tantalum after low-temperature annealing in Step 3 is subjected to one-time cross rolling on a rolling mill. After the one-time cross rolling, the high-purity tantalum is subjected to medium-temperature short-time annealing to obtain an intermediate target billet. The roll diameter of the rolling mill is 600mm. The specific process of the one-time cross rolling is as follows: after each rolling pass, the high-purity tantalum is rotated 90° clockwise along the normal direction for the next rolling pass. Each pass has a large deformation, with a pass deformation of 16%, and the total deformation of the one-time cross rolling is 50%. The temperature of the medium-temperature short-time annealing is 1160℃, and the holding time is 40min.

[0076] Step 5, intermediate target blank cutting: The intermediate target blank described in Step 4 is wire-cut along 1 / 2 of its thickness, dividing the intermediate target blank into two groups on average; the wire-cutting process should ensure that the cut surface is smooth and burr-free;

[0077] Step Six: Secondary Cross Rolling: The intermediate target billet cut in Step Five is subjected to secondary cross rolling. After secondary cross rolling, the intermediate target billet undergoes low-temperature long-time annealing to obtain a tantalum target billet. The specific process of secondary cross rolling is as follows: after each rolling pass, the intermediate target billet is rotated 90° clockwise along the normal direction for the next rolling pass. Each pass has a small deformation, with a deformation amount of 10% per pass, and the total deformation amount of the secondary cross rolling is 60%. The temperature of the low-temperature long-time annealing is 1060℃, and the holding time is 2.5h. The diameter of the tantalum target billet is ≥500mm, the thickness is ≥10mm, and the proportion of defects and scrap is <5%.

[0078] The proportions of {100} and {111} textures in the tantalum target blanks prepared in Example 5 are shown in Table 1. It can be seen that the {100} texture accounts for 36%, and the {111} texture accounts for 20%. The average grain size statistics of the tantalum target blanks are shown in [Table 1]. Figure 2 The average grain size is 45.8 μm. The {100} and {111} orientations are uniformly distributed along the thickness direction at both the edge and center of the tantalum target blank, with no texture bands formed. The prepared tantalum target blank meets the sputtering coating requirements for 12-inch wafers.

[0079] Example 6

[0080] This embodiment provides a method for preparing a tantalum target preform with highly uniform microstructure, comprising the following steps:

[0081] Step 1, Primary Forging: The high-purity tantalum, after electron beam melting, is forged on a hydraulic press. After primary forging, the high-purity tantalum undergoes high-temperature annealing. The purity of the high-purity tantalum is 5N. The tonnage of the hydraulic press is 2000T. The specific process of primary forging is as follows: the high-purity tantalum is upset along the axial direction in multiple passes to half its original height, followed by multiple draw-out passes to its original height. Each pass of upsetting and drawing involves large deformation, with a deformation amount of 20% per pass. The high-temperature annealing temperature is 1280℃, and the holding time is 1 hour.

[0082] Step 2, Secondary Forging: The high-purity tantalum after high-temperature annealing in Step 1 is subjected to secondary forging. After secondary forging, the high-purity tantalum is subjected to medium-temperature annealing. The specific process of secondary forging is as follows: the high-purity tantalum is upsetting along the axial direction to 1 / 2 of its original height in multiple passes, and then drawn back to its original height in multiple passes. Each pass of upsetting and drawing is a medium deformation, and the deformation amount per pass is 13%. The temperature of the medium-temperature annealing treatment is 1180℃, and the holding time is 1 hour.

[0083] Step 3, Three-stage forging: The high-purity tantalum after the medium-temperature annealing in Step 2 is forged three times. After the three forgings are completed, the high-purity tantalum is subjected to low-temperature annealing. The specific process of the three-stage forging is as follows: the high-purity tantalum is upsetting along the axial direction to 1 / 2 of its original height in multiple passes, and then drawing back to its original height in multiple passes. Each pass of upsetting and drawing has a small deformation, and the deformation amount per pass is 10%. The temperature of the low-temperature annealing is 1060℃, and the holding time is 1 hour.

[0084] Step 4, One-time cross rolling: The high-purity tantalum after low-temperature annealing in Step 3 is subjected to one-time cross rolling on a rolling mill. After the one-time cross rolling, the high-purity tantalum is subjected to medium-temperature short-time annealing to obtain an intermediate target billet. The roll diameter of the rolling mill is 600mm. The specific process of the one-time cross rolling is as follows: after each rolling pass, the high-purity tantalum is rotated 90° clockwise along the normal direction for the next rolling pass. Each pass has a large deformation, with a pass deformation of 16%, and the total deformation of the one-time cross rolling is 50%. The temperature of the medium-temperature short-time annealing is 1180℃, and the holding time is 30min.

[0085] Step 5, intermediate target blank cutting: The intermediate target blank described in Step 4 is wire-cut along 1 / 2 of its thickness, dividing the intermediate target blank into two groups on average; the wire-cutting process should ensure that the cut surface is smooth and burr-free;

[0086] Step Six: Secondary Cross Rolling: The intermediate target billet cut in Step Five is subjected to secondary cross rolling. After secondary cross rolling, the intermediate target billet undergoes low-temperature long-time annealing to obtain a tantalum target billet. The specific process of secondary cross rolling is as follows: after each rolling pass, the intermediate target billet is rotated 90° clockwise along the normal direction for the next rolling pass. Each pass has a small deformation, with a deformation amount of 10% per pass, and the total deformation amount of the secondary cross rolling is 60%. The temperature of the low-temperature long-time annealing is 1080℃, and the holding time is 2.5h. The diameter of the tantalum target billet is ≥500mm, the thickness is ≥10mm, and the proportion of defects and scrap is <5%.

[0087] The proportions of {100} and {111} textures in the tantalum target blanks prepared in Example 6 are shown in Table 1. It can be seen that the {100} texture accounts for 39%, and the {111} texture accounts for 24%. The average grain size statistics of the tantalum target blanks are shown in [Table 1]. Figure 2 The average grain size is 47.2 μm. The {100} and {111} orientations are uniformly distributed along the thickness direction at both the edge and center of the tantalum target blank, with no texture bands formed. The prepared tantalum target blank meets the sputtering coating requirements for 12-inch wafers.

[0088] Table 1. Proportions of {100} and {111} textures in tantalum target blanks prepared in Examples 1 to 6

[0089] {100}Texture percentage {111} Textile proportion Example 1 40％ 21％ Example 2 44％ 26％ Example 3 42％ 18％ Example 4 37％ 23％ Example 5 36％ 20％ Example 6 39％ 24％

[0090] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any simple modifications, alterations, or equivalent structural changes made to the above embodiments based on the technical essence of the invention shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing a tantalum target blank with highly uniform microstructure, characterized in that, Includes the following steps: Step 1, Primary Forging: The high-purity tantalum, after electron beam melting, is forged on a hydraulic press and then subjected to high-temperature annealing. The specific process of primary forging includes: upsetting the high-purity tantalum along the axial direction to half its original height in multiple passes, followed by drawing it to its original height in multiple passes. Each pass of upsetting and drawing involves large deformation, with a deformation amount of 18% to 20% per pass. The high-temperature annealing process is carried out at a temperature of 1220℃ to 1280℃ and a holding time of 1 hour. Step 2, Secondary Forging: The high-purity tantalum after high-temperature annealing in Step 1 is subjected to secondary forging, followed by medium-temperature annealing. The specific process of secondary forging includes: upsetting the high-purity tantalum along the axial direction to half of its original height in multiple passes, followed by drawing it to its original height in multiple passes. Each pass of upsetting and drawing involves medium deformation, with a deformation amount of 12% to 13% per pass. The temperature of the medium-temperature annealing is 1120℃ to 1180℃, and the holding time is 1 hour. Step 3, Three-stage forging: The high-purity tantalum after the medium-temperature annealing in Step 2 is forged three times, followed by low-temperature annealing. The specific process of the three-stage forging includes: upsetting the high-purity tantalum along the axial direction to half of its original height in multiple passes, followed by drawing it to its original height in multiple passes. Each pass of upsetting and drawing involves small deformation, with a deformation amount of 8% to 10% per pass. The temperature of the low-temperature annealing is 1020℃ to 1080℃, and the holding time is 1 hour. Step 4, One-time cross rolling: The high-purity tantalum after low-temperature annealing in Step 3 is subjected to one-time cross rolling on a rolling mill, followed by medium-temperature short-time annealing to obtain an intermediate target billet; the specific process of the one-time cross rolling includes: after each rolling pass, the high-purity tantalum is rotated 90˚ clockwise along the normal direction for the next rolling pass, each pass has a large deformation, the deformation amount is 14%~16%, and the total deformation amount of one-time cross rolling is 45%~50%; the temperature of the medium-temperature short-time annealing is 1120℃~1180℃, and the holding time is 20min~40min; Step 5, intermediate target blank cutting: The intermediate target blank described in Step 4 is wire-cut along 1 / 2 of its thickness, and the intermediate target blank is cut into two groups on average. Step Six, Secondary Cross Rolling: The intermediate target billet cut in Step Five is subjected to secondary cross rolling, and then subjected to low-temperature long-time annealing to obtain a tantalum target billet. The specific process of the secondary cross rolling includes: after each rolling pass, the intermediate target billet is rotated 90˚ clockwise along the normal direction for the next rolling pass. Each pass has a small deformation, with a deformation amount of 8%~10%, and the total deformation amount of the secondary cross rolling is 50%~60%. The temperature of the low-temperature long-time annealing is 1020℃~1080℃, and the holding time is 1.5h~2.5h.

2. The method for preparing a tantalum target blank with highly uniform microstructure according to claim 1, characterized in that, The purity of the high-purity tantalum mentioned in step one is 5N, and the tonnage of the hydraulic press is 2000T.

3. The method for preparing a tantalum target blank with highly uniform microstructure according to claim 1, characterized in that, The roll diameter of the rolling mill mentioned in step four is 400mm~600mm.

4. The method for preparing a tantalum target blank with highly uniform microstructure according to claim 1, characterized in that, In step five, the wire cutting process should ensure that the cut surface is smooth and burr-free.

5. The method for preparing a tantalum target blank with highly uniform microstructure according to claim 1, characterized in that, The tantalum target blank in step six has a uniform microstructure distribution, with an average grain size ≤60μm, a {100} texture ratio ≥35%, and a {111} texture ratio ≤30%; the diameter of the tantalum target blank is ≥500mm and the thickness is ≥10mm.

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