A copper target material shape transformation heat treatment process suitable for continuous production

Abstract

The application relates to a copper target material deformation heat treatment process suitable for continuous production, characterized in that copper plates are continuously put into a -50 DEG C low-temperature holding box in sequence, the copper plates are quickly sent into a rolling mill for deep low-temperature rolling after the temperature of the copper plates is reduced to -50 DEG C, the above-mentioned temperature reduction and rolling multi-pass processes are repeated, and the total deformation of the copper plates reaches 80%; the application is suitable for industrialized continuous and rapid production, high production efficiency is obtained, the obtained target material has good uniformity and good fine-grain effect; through composite deformation, grains are broken, and then a targeted annealing process is formulated to make high-purity copper recrystallize, eliminate shear bands and coarse grains in a single deformation such as rolling, the process cost is moderate, a complex mold is not needed, and the process is a good high-purity copper target material fine-grain and structure optimization process scheme.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of material science, and particularly relates to a copper target material deformation heat treatment process suitable for continuous production. BACKGROUND

[0002] With the rapid development of the electronic information industry, the requirements of the society on materials are getting higher and higher. Copper has more excellent heat conduction and electrical conductivity than aluminum, and its anti-electromigration ability is much higher than that of aluminum. Therefore, high-purity copper and high-purity copper alloy are gradually widely used in the preparation and production of electronic devices and interconnection lines in the semiconductor industry. The preparation of copper target material is a link with higher technical requirements in the entire industrial chain. The quality of the sputtering target has an important influence on the quality of downstream products. High-purity copper ingots smelted by various methods such as powder metallurgy and smelting always have problems such as coarse grains and uneven structure, and deformation heat treatment needs to be applied to the material to obtain target material with fine grains, uniform structure and beneficial orientation for sputtering.

[0003] After searching and summarizing the papers or patents published at home and abroad, it is found that the fine-grain process for preparing high-purity copper target material includes forging, equal-channel angular extrusion, rolling and the like. Yao Lijun et al. (see patent CN 112921287A) sequentially perform hot forging treatment, primary heat treatment, cold forging treatment, secondary heat treatment, static pressure treatment and rolling on ultra-high-purity copper castings to obtain high-purity copper target material. The copper plate obtained by this method has limited grain size refinement effect, and the average grain size can only reach about 100 μm. In addition, there is a serious problem of uneven structure between the surface and the core, and there is a gradient distribution of grain size and texture.

[0004] Many technicians (patent CN 112453088A and document Nano-grain evolution in austenitic stainless steel during multi-directional forging [J]. Materials Science & Engineering A, etc.) obtain fine-grain effect and good structure uniformity by multi-pass equal-channel angular extrusion plastic deformation, but it is only suitable for the production of cylindrical rods, and the production speed is slow, and the continuity is poor. After each extrusion is completed, the rod needs to be machined.

[0005] Liu Shifeng et al. (see the literature Study on microstructure and texture of ultra-high purity copper and copper-aluminum alloy for sputtering target) adopt the multi-pass asynchronous rolling method at room temperature to obtain fine-grained targets of high-purity copper and high-purity tantalum. This ordinary room temperature rolling method is suitable for continuous production and has high production efficiency, but the grain crushing effect of room temperature rolling on large-size copper plates is not good enough, and the deformation storage energy is insufficient, the grain size and uniformity obtained by the grain are limited, and the problem of uneven surface and core organization cannot be well solved, and there is still a gradient distribution of grain size and texture in the thickness direction.

[0006] Zhang Wu et al. (see patent CN 111299969 A) optimize the microstructure of high-purity copper target material by multi-pass hot rolling and water cooling treatment, but there are problems such as abnormal grain growth after annealing caused by rolling shear band preferential recrystallization during hot working and the inability to better optimize the grain size uniformity.

[0007] There are many methods for preparing ultra-fine-grained copper through large deformation hot working. These processes have large deformation and long process time, which are suitable for the preparation of ultra-fine-grained (grain size of several microns or nanometers) copper materials, but such processes are not suitable for the manufacture of copper plates with grain size of tens of microns due to high precision control and high cost.

[0008] For copper, a metal with medium and low stacking fault energy, recovery, recrystallization, and even abnormal grain growth may occur during heat treatment, and high-purity copper has the characteristics of high purity, so annealing has a great influence on the microstructure and properties of high-purity copper target material. SUMMARY

[0009] In order to overcome the above-mentioned defects of the prior art, the purpose of the present application is to provide a copper target material deformation heat treatment process suitable for continuous production, which is reasonable in design, can improve the internal microstructure of high-purity copper target material, and can solve the problem of uneven organization caused by abnormal grain growth of high-purity copper during heat treatment.

[0010] To achieve this purpose, the technical scheme adopted by the present application is as follows:

[0011] The copper target material deformation heat treatment process suitable for continuous production of the present application is characterized by:

[0012] The copper plate is continuously placed in a -50℃ low-temperature incubator, and after the temperature of the copper plate is reduced to -50℃, the copper plate is quickly sent to the rolling mill for deep low-temperature rolling, and the above-mentioned cooling and rolling multi-pass process is repeated, so that the total deformation of the copper plate reaches 80%.

[0013] Preferably, the copper plate with a total deformation of 80% is sent to a continuous shearing mill for one-pass continuous shearing plastic deformation to further break the grains.

[0014] Preferably, the above sending the copper plate to the mill for deep cryogenic rolling and sending the copper plate to the shearing mill for continuous shearing are both through mechanical hand feeding.

[0015] Preferably, before the copper plate is placed in the-50 DEG C cryogenic incubator, the copper plate is first placed in an annealing furnace for homogenization annealing treatment at 500 DEG C for 1h.

[0016] Preferably, the above sending the copper plate to the mill for multi-pass rolling, after each rolling, the copper plate is placed in a-50 DEG C cryogenic incubator, and after the temperature of the copper plate is reduced to-50 DEG C, the next pass of rolling is performed, and the parameters of each pass of rolling are as follows:

[0017] Preferably, after the total deformation of the copper plate reaches 80%, or after the copper plate is subjected to the continuous shearing process, an annealing process is performed.

[0018] Preferably, the annealing process is as follows: the predetermined target temperature of the copper plate for annealing is 180 DEG C, the temperature of the annealing furnace is first set to 180 DEG C at a heating rate of 10 DEG C / min, the copper plate is placed in the annealing furnace after the set temperature is reached, the temperature during the incubation stage is 180 DEG C, and the incubation time is 2h; after the incubation is completed, the copper plate is taken out and air-cooled to room temperature; the grain size of the high-purity copper plate after annealing is measured, and the average grain size is 10.9 mu m with a deviation of plus or minus 5.2 mu m.

[0019] Preferably, the annealing process is as follows: the predetermined target temperature of the copper plate for annealing is 350 DEG C, the temperature of the annealing furnace is first set to 350 DEG C at a heating rate of 10 DEG C / min, the copper plate is placed in the annealing furnace after the set temperature is reached, the temperature during the incubation stage is 350 DEG C, and the incubation time is 5min; after the incubation is completed, the copper plate is taken out quickly and air-cooled to room temperature; the grain size of the high-purity copper plate after annealing is measured, and the average grain size is 7.6 mu m with a deviation of plus or minus 4.3 mu m.

[0020] The application has the advantages that: the application is suitable for industrialized continuous and rapid production, and has high production efficiency; the target material obtained has good uniformity and good fine-grain effect; the grains are broken through composite deformation, and then a targeted annealing process is formulated to make the high-purity copper recrystallize, eliminate shear bands and coarse grains in the process of single deformation such as rolling, and inhibit abnormal growth of recrystallized grains; deep cryogenic rolling with liquid nitrogen is high in cost and not suitable for actual production, and the production cost of the application is lower than that of deep cryogenic rolling with liquid nitrogen; the cost of the application is moderate, and no complex mold is needed. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is the initial microstructure of high-purity copper target material;

[0022] Figure 2 is the microstructure of copper target material after the processing technology of the application;

[0023] Figure 3 is a schematic diagram of the rolling deformation process;

[0024] Figure 4 is a schematic diagram of the continuous shearing process. DETAILED DESCRIPTION

[0025] In the following examples, the size of the high-purity copper plate taken is 160 mm x 100 mm x 20 mm.

[0026] Example 1

[0027] The high-purity copper plate in the initial state and after homogenization annealing was subjected to microhardness testing and grain size calculation, and the Vickers microhardness of the two was 54 HV and 52 HV, respectively, and the average grain size of the two was 660 μm and 790 μm, respectively, and the particle size deviation was large.

[0028] Example 2

[0029] After homogenization annealing, the residual stress of the material can be significantly reduced, which is beneficial to subsequent plastic deformation, so the high-purity copper after 500℃-1h homogenization annealing is selected as the initial material before deformation, and then the copper plate is continuously placed in a-50℃ low-temperature incubator, and after the temperature of the copper plate is reduced to-50℃, the copper plate is quickly fed into the rolling mill by a mechanical hand for deep low-temperature rolling, and the repeated cooling and rolling process is repeated for multiple passes, so that the total deformation of the target material reaches 80%, and the specific rolling process is shown in Table 1; then the copper plate is deburred and sent to a continuous shearing rolling mill for one-pass continuous shearing plastic deformation, the feeding speed is 300 mm / s, and the process is lubricated with MOS2 lubricant to further break the grains.

[0030] Table 1 Low-temperature rolling process flow

[0031] The annealing process is set as follows: the annealing pre-set target temperature of the high-purity copper plate is 180℃, first set the temperature of the annealing furnace to 180℃, and the heating rate is 10℃ / min; after reaching the set temperature, put in the copper plate, and in the heat preservation stage, the heat preservation temperature is 180℃, and the heat preservation time is 2h. After heat preservation, take out and air cool to room temperature.

[0032] The grain size of the annealed high-purity copper plate was calculated, and the average grain size was 10.9 μm, and the deviation was plus or minus 5.2 μm.

[0033] Example 3

[0034] The residual stress of the material can be significantly reduced after homogenization annealing, which is beneficial for subsequent plastic deformation, so the high-purity copper after 500 DEG C-1h homogenization annealing is selected as the initial material before deformation, then the copper plate is sequentially placed into a-50 DEG C low temperature incubator, after the temperature of the copper plate is reduced to-50 DEG C, the copper plate is quickly sent into the rolling mill by a mechanical hand feeding, and the deep low-temperature rolling is carried out, the temperature is repeatedly reduced and rolled for multiple passes, so that the total deformation of the target material reaches 80%, and the specific rolling process is shown in table 2; then the copper plate is cleaned and sent into a continuous shearing mill for one-pass continuous shearing plastic deformation, the feeding speed is 300mm / s, and the process is lubricated by using MOS2 lubricant, and the crystal grains are further broken.

[0035] Table 2 Low-temperature rolling process flow

[0036]

[0037] The annealing process is set as follows: the annealing pre-set target temperature of the high-purity copper plate is 350 DEG C, first, the temperature of the annealing furnace is set to 350 DEG C, the heating rate is 10 DEG C / min, the copper plate is placed after reaching the set temperature, in the heat preservation stage, the heat preservation temperature is 350 DEG C, the heat preservation time is 5min, and after the heat preservation is completed, it is quickly taken out and air-cooled to room temperature.

[0038] The grain size of the high-purity copper plate after annealing is measured and calculated, and the average grain size is 7.6um, and the deviation is plus or minus 4.3um.

[0039] The application is suitable for industrialized continuous and rapid production, the production efficiency is high, the obtained target material has good uniformity and good fine grain effect; the grains are broken through composite deformation, and then the annealing process is formulated to make the high-purity copper recrystallize, so that the shear band and coarse grains in the rolling process are eliminated, the process cost is moderate, and a complex mold is not needed, so that it is a good fine grain and organization optimization process scheme for high-purity copper target material.

[0040] The application is described through preferred embodiments, and those skilled in the art should understand that various changes or equivalent replacements can be made to these features and embodiments without departing from the spirit and scope of the application. The application is not limited to the specific embodiments disclosed herein, and other embodiments falling within the scope of the claims of the application are within the scope of protection of the application.

Claims

1. A copper target material shape transformation heat treatment process suitable for continuous production, characterized in that: copper plates are sequentially placed into a -50℃ low-temperature incubator, and after the temperature of the copper plates is reduced to -50℃, the copper plates are quickly sent into a rolling mill for deep low-temperature rolling, and the above-mentioned temperature reduction and rolling processes are repeated for multiple passes, so that the total deformation of the copper plates reaches 80%; the copper plates with a total deformation of 80% are deburred and then sent into a continuous shearing mill for one-pass continuous shearing plastic deformation to further break up the grains; the copper plates are sent into the rolling mill for deep low-temperature rolling, and the copper plates are sent into the shearing mill for continuous shearing through a mechanical hand feeding; before the copper plates are placed into the -50℃ low-temperature incubator, the copper plates are first placed into an annealing furnace for homogenization annealing treatment at 500℃ for 1h; the copper plates are sent into the rolling mill for multiple-pass rolling, and after each rolling pass, the copper plates are placed into the -50℃ low-temperature incubator, and after the temperature of the copper plates is reduced to -50℃, the next rolling pass is performed, and the rolling parameters of each pass are as follows: after the total deformation of the copper plates reaches 80% or after the copper plates are subjected to the continuous shearing process, an annealing process is performed; the predetermined target temperature of the copper plates for the annealing process is 180℃, the temperature of the annealing furnace is first set to 180℃ at a heating rate of 10℃ / min, the copper plates are placed into the annealing furnace after the set temperature is reached, the temperature during the holding stage is 180℃, and the holding time is 2h; ； after the holding is completed, the copper plates are taken out and air-cooled to room temperature; the grain size of the high-purity copper plates after annealing is measured, and the average grain size is 10.9μm with a deviation of plus or minus 5.2μm; or, the predetermined target temperature of the copper plates for the annealing process is 350℃, the temperature of the annealing furnace is first set to 350℃ at a heating rate of 10℃ / min, the copper plates are placed into the annealing furnace after the set temperature is reached, the temperature during the holding stage is 350℃, and the holding time is 5min; after the holding is completed, the copper plates are quickly taken out and air-cooled to room temperature; the grain size of the high-purity copper plates after annealing is measured, and the average grain size is 7.6μm with a deviation of plus or minus 4.3μm. ​

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