Method for manufacturing equiaxed crystal target
By using radial forging, rolling, equal channel corner extrusion, and annealing recrystallization heat treatment, the problems of complexity and high cost of existing target preparation methods have been solved, and equiaxed crystal targets suitable for semiconductor sputtering have been manufactured, achieving grain refinement to below 20 μm and improving film quality.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- METAL INDS RES & DEV CENT
- Filing Date
- 2024-12-05
- Publication Date
- 2026-06-05
AI Technical Summary
Existing target preparation methods suffer from complex processes, high production costs, and the inability to achieve grain refinement below 100 μm, especially for pure aluminum materials.
The process involves radial forging, rolling, equal channel corner extrusion, and annealing recrystallization heat treatment. The radial forging process initially refines the grains, the rolling process controls the grain orientation, the equal channel corner extrusion process severely breaks down the subgrains, and the annealing recrystallization heat treatment process refines the grains to below 20 μm.
It enables the fabrication of equiaxed crystal targets with a grain size of no more than 20 μm, which is suitable for semiconductor sputtering processes and improves the electrical properties and thickness uniformity of thin films.
Smart Images
Figure CN122147256A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for manufacturing a target material, and more particularly to a method for manufacturing an equiaxed crystal target material. Background Technology
[0002] As the demand for portable electronic products increases, semiconductor devices are also moving towards miniaturization, which in turn requires improvements in the quality of thin films in semiconductor devices.
[0003] Sputtering is a process in which plasma bombards a target, causing the atoms released by the impact energy to deposit onto a substrate to form a thin film. Sputtered films exhibit high adhesion and uniformity, and are therefore widely used in semiconductor manufacturing. In addition to the power and speed parameters used in the sputtering process, the quality of the target material is also a crucial factor in determining the quality of the sputtered film. Generally, the purity of sputtering targets used in semiconductor manufacturing is required to be above 4N (99.99%), and the target grain size must be less than 30 nm to form a thin film on the substrate that meets the requirements for electrical properties and film thickness uniformity.
[0004] Existing target preparation methods employ multi-directional free forging to plastically deform aluminum ingots, followed by cold rolling at 0 to 5°C to refine grain size. However, these methods suffer from complex processes, high production costs, and the inability to achieve uniform grain size distribution below 100 μm.
[0005] Patent document (CN 109518140 A) discloses a method for preparing ultra-high purity, equiaxed fine-grained aluminum target material, characterized by the following steps: (1) remelting: placing high-purity aluminum ingots in a vacuum furnace for remelting, and obtaining high-purity aluminum liquid after complete melting; (2) recasting: pouring the high-purity aluminum liquid into an ingot mold for recasting, and electromagnetically stirring the high-purity aluminum liquid during the cooling process, and obtaining a newly cast high-purity aluminum ingot after recasting; (3) annealing: holding the newly cast high-purity aluminum ingot at 200-400℃ and then cooling it at room temperature; (4) forging: forging the annealed newly cast high-purity aluminum ingot; (5) rolling: rolling the forged newly cast high-purity aluminum ingot; (6) holding and cooling the rolled newly cast high-purity aluminum ingot to obtain equiaxed ultra-high purity aluminum with a grain size of less than 100μm. However, the equiaxed crystal targets in the patent documents are for pure aluminum materials, and their manufacturing process is relatively complex.
[0006] In view of this, it is necessary to provide a method for manufacturing equiaxed crystal targets to solve the above problems. Summary of the Invention
[0007] The purpose of this invention is to provide a method for manufacturing equiaxed crystal sputtering targets, which can produce equiaxed crystal sputtering targets with a grain size of no more than 20 μm and which are then processed into semiconductor sputtering targets.
[0008] To achieve the above objectives, the present invention provides a method for manufacturing an equiaxed crystal target, comprising the following steps: forming a forged substrate from a metal rod through a radial forging process; forming a first plate from the forged substrate through a rolling process and a forging process, wherein the rolling process is performed along the axial direction of the forged substrate; performing an equal channel corner extrusion process on the first plate repeatedly with an equal channel corner extrusion die to obtain a second plate, wherein the cumulative average equivalent strain of the second plate is greater than 10, wherein the feeding direction of the first plate into each of the channel corner extrusion dies is the same as the rolling direction of the forged substrate; and performing an annealing and recrystallization heat treatment process on the second plate to obtain an equiaxed crystal target.
[0009] In some embodiments, the second plate is subjected to the annealing and recrystallization heat treatment process using an induction heat treatment device to obtain each of the axial crystal targets, wherein the grain size of each of the axial crystal targets is not greater than 20 μm.
[0010] In some embodiments, the heat treatment temperature of the annealing-recrystallization heat treatment process is below the recrystallization temperature of the metal rod material.
[0011] In some embodiments, when the material of the metal rod is pure copper, the heat treatment temperature of the annealing and recrystallization heat treatment process is between 300 and 400 °C, and the heat treatment time is between 30 and 60 minutes.
[0012] In some embodiments, the grain size difference between the grains of each of the axial crystal targets is no greater than one grain size number.
[0013] In some embodiments, the number of extrusions in each of the channel corner extrusion processes is not less than 4, and the grain size of each of the axial crystal targets is not greater than 5 μm.
[0014] In some embodiments, during the extrusion process of each of the channel corners, the first sheet material and each of the channel corner extrusion dies are simultaneously lubricated.
[0015] In some embodiments, after the radial forging process, the cumulative central equivalent strain of the core of the forged substrate is greater than 2, and after the rolling process and the forging process, the cumulative central equivalent strain of the core of the first plate is greater than 5.
[0016] In some embodiments, the metal rod is made of pure copper or copper-manganese.
[0017] In some embodiments, after the annealing and recrystallization heat treatment process, each of the axial crystal targets is subjected to a machining process.
[0018] The manufacturing method of the equiaxed crystal target of the present invention has the following characteristics: the above steps can be used to obtain an equiaxed crystal target with a grain size of no more than 20 μm for use in the semiconductor industry. Attached Figure Description
[0019] Figure 1 This is a flowchart illustrating the steps of the manufacturing method of the equiaxed crystal target of the present invention.
[0020] Figure 2 This is a schematic diagram of the radial forging process in the manufacturing method of the equiaxed crystal target of the present invention.
[0021] Figure 3 This is a schematic diagram of the equal-channel corner extrusion process in the manufacturing method of the equiaxed crystal target of the present invention.
[0022] In the picture: 1: Metal rods; 2: First board material; 3: Equal channel corner extrusion die; S110, S130, S150, S170: Steps. Detailed Implementation
[0023] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention. The drawings are mainly simplified schematic diagrams, which are only used to illustrate the basic structure of the present invention. Therefore, only the elements related to the present invention are marked in the drawings, and the elements shown are not drawn according to the number, shape, size ratio, etc. of the implementation. The actual specifications and dimensions of the implementation are a selective design, and the layout of the elements may be more complex.
[0024] The following descriptions of the embodiments are made with reference to the accompanying drawings, illustrating specific embodiments in which the invention may be practiced. Directional terms used in this invention, such as "up," "down," "front," and "back," are merely directional references to the accompanying drawings. Therefore, the directional terms used are for illustration and understanding of this application and not for limiting it. Furthermore, in this specification, unless explicitly stated otherwise, the word "comprising" will be understood to mean including the stated elements, but does not exclude any other elements.
[0025] Please refer to Figure 1 The flowchart of the manufacturing method of the equiaxed crystal target of the present invention includes the following steps: A metal rod 1 is formed into a forged substrate through a radial forging process (step S110). In one embodiment, after the radial forging process, the cumulative central equivalent strain of the core of the forged substrate is greater than 2, thereby initially refining the grains of the metal rod 1 and reducing the size difference of grains in the same orientation. Preferably, the radial forging process can be performed at low temperature or room temperature, resulting in a higher degree of grain fragmentation of the metal rod 1, and thus a smaller grain size. Please refer to... Figure 2 The equipment used in this radial forging process can be cogging, which shapes the metal bar 1 into the forging substrate in four directions. The forging substrate of the target size can be made by adjusting the radial forging amount.
[0026] In one embodiment, the material of the metal rod 1 can be pure copper or copper-manganese, wherein the purity of the pure copper can be 6N (99.9999%) or higher.
[0027] The forged substrate is formed into a first sheet through a rolling process and a forging process. The rolling process is performed along the axial direction of the forged substrate (step S130). In one embodiment, after the rolling process and the forging process, the cumulative central equivalent strain of the core of the first sheet is greater than 5. This not only controls the grain orientation but also allows the core of the first sheet to obtain a larger strain, thereby reducing the strain difference between the outer edge and the core of the first sheet. Preferably, the forging process can be performed at a low temperature (e.g., not greater than 200°C) or at room temperature to prevent the grains of the first sheet from growing larger at high temperatures, thus maintaining fine grains. Preferably, after the rolling process, the forged substrate is rolled into a thick sheet with a width-to-thickness ratio of 4 to 8, and then the forging process is performed to forge a thin sheet (i.e., the first sheet).
[0028] Please refer to Figure 3 The first sheet 2 is subjected to an equal channel angular extrusion (ECAE) process by reciprocating through an equal channel angular extrusion die 3. This process applies a large-angle shear strain to the entire first sheet 2, causing severe grain breakage and forming fine subgrains, thereby obtaining a second sheet. The cumulative average equivalent strain of the second sheet is greater than 10 (step S150). The feeding direction of the first sheet 2 into each of the channel angular extrusion dies 3 is the same as the rolling direction of the forging substrate.
[0029] In one embodiment, during the extrusion process of each of the channel corners, the first sheet 2 and each of the channel corner extrusion dies 3 can be lubricated simultaneously (e.g., material coating and lubricant).
[0030] The second sheet material is subjected to an annealing-recrystallization heat treatment process to obtain an equiaxed crystal target (step S170). After the annealing-recrystallization heat treatment process, each of the equiaxed crystal targets can be subjected to a machining process. In one embodiment, the annealing-recrystallization heat treatment process can be performed on the second sheet material using an induction heat treatment device, so that the grain size of each of the obtained equiaxed crystal targets is no greater than 20 μm when the number of extrusions in each of the channel corner extrusion processes is 1, and the grain size difference between the grains of each of the equiaxed crystal targets is no greater than 1 grain size number, wherein the grain size number can be measured by standards such as ASTM E112, E1382, and IS 4748.
[0031] It is worth mentioning that by using this induction heat treatment equipment to perform the annealing and recrystallization heat treatment process on the second plate, the entire second plate can be heated to the required temperature within a few seconds and then rapidly annealed, so as to achieve the effect of rapid heating and rapid cooling, thereby obtaining the effect of relatively fine grain size of each of the axial crystal targets.
[0032] In one embodiment, the heat treatment temperature of the annealing and recrystallization heat treatment process is below the recrystallization temperature of the material of the metal rod 1, and when the material of the metal rod 1 is pure copper, the heat treatment temperature of the annealing and recrystallization heat treatment process can be between 300 and 400 °C, and the heat treatment time can be between 30 and 60 minutes.
[0033] In another embodiment, when the extrusion number of each of the channel corner extrusion processes is not less than 4 times, the grain size of each of the equiaxed crystal targets obtained can be no greater than 5 μm. The extrusion angle of each of the channel corner extrusion dies 3 can be between 30 and 90 degrees. It is understood that, prior to the aforementioned annealing-recrystallization heat treatment process, the manufacturing method of the equiaxed crystal target in this invention does not involve an additional heat treatment process; therefore, the equivalent strain within the material can accumulate, which helps to form equiaxed fine grains after the annealing-recrystallization heat treatment process.
[0034] As described above, the manufacturing method of the equiaxed crystal target of the present invention can obtain an equiaxed crystal target with a grain size of no more than 20 μm through the above steps, for use in the semiconductor industry.
[0035] The embodiments described above are merely preferred embodiments for fully illustrating the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention.
Claims
1. A method for manufacturing an equiaxed crystal target, characterized in that, Includes the following steps: A metal bar is formed into a forged substrate through a radial forging process; The forged substrate is formed into a first plate through a rolling process and a forging process, wherein the rolling process is performed along the axial direction of the forged substrate. A first sheet is subjected to a reciprocating first-channel corner extrusion process using a first-channel corner extrusion die to obtain a second sheet. The cumulative average equivalent strain of the second sheet is greater than 10. The feeding direction of the first sheet into each of the corner extrusion dies is the same as the rolling direction of the forged substrate. The second plate is subjected to an annealing and recrystallization heat treatment process to obtain an equiaxed crystal target.
2. The method for manufacturing the equiaxed crystal target as described in claim 1, characterized in that, The second plate is subjected to the annealing and recrystallization heat treatment process using an induction heat treatment device to obtain each of the axial crystal targets, wherein the grain size of each of the axial crystal targets is not greater than 20 μm.
3. The method for manufacturing the equiaxed crystal target as described in claim 2, characterized in that, The heat treatment temperature of the annealing and recrystallization heat treatment process is below the recrystallization temperature of the metal rod material.
4. The method for manufacturing the equiaxed crystal target as described in claim 3, characterized in that, When the material of the metal rod is pure copper, the heat treatment temperature of the annealing and recrystallization heat treatment process is between 300 and 400 °C, and the heat treatment time is between 30 and 60 minutes.
5. The method for manufacturing the equiaxed crystal target as described in claim 2, characterized in that, The grain size difference between the grains of each of the aforementioned axial crystal targets is no greater than one grain size number.
6. The method for manufacturing the equiaxed crystal target as described in claim 1, characterized in that, The number of extrusion cycles in each of the channel corner extrusion processes is not less than 4, and the grain size of each of the axial crystal targets is not greater than 5 μm.
7. The method for manufacturing the equiaxed crystal target as described in claim 1, characterized in that, During the extrusion process of each of the aforementioned channel corners, the first sheet material and each of the aforementioned channel corner extrusion dies are simultaneously lubricated.
8. The method for manufacturing the equiaxed crystal target as described in claim 1, characterized in that, After the radial forging process, the cumulative central equivalent strain of the core of the forged substrate is greater than 2, and after the rolling process and the forging process, the cumulative central equivalent strain of the core of the first plate is greater than 5.
9. The method for manufacturing the equiaxed crystal target as described in claim 1, characterized in that, The metal rod is made of pure copper or copper-manganese.
10. The method for manufacturing the equiaxed crystal target as described in claim 1, characterized in that, After the annealing and recrystallization heat treatment process, each of the axial crystal targets is subjected to a machining process.