JP2010065252A - Method for producing fine crystal grain copper material, the fine crystal grain copper material, and sputtering target - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a fine crystal grain copper material which can produce a fine crystal grain copper material made of high purity copper or a low concentration copper alloy at low cost, in which crystal grains are refined, and which is thermally stable, to provide a fine crystal grain copper material produced by the production method, and to provide a sputtering target composed of the fine crystal grain copper material. <P>SOLUTION: In the method for producing the fine crystal grain copper material where a copper stock 1 made of high purity copper or a low concentration copper alloy is subjected to multi-axes forging treatment of performing compression working from different directions, respectively, and a copper material in which crystal grains are refined is produced, the initial working temperature T1 at which the first compression working in the multi-axes forging is performed is a temperature in which dynamic recrystallization is at least partially generated in the copper stock 1. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing a fine-grained copper material which is made of high-purity copper or a low-concentration copper alloy and whose crystal grains are refined, and a fine-grained copper material produced by this production method In addition, the present invention relates to a sputtering target made of this fine crystal grain copper material.

2. Description of the Related Art Conventionally, a method using a sputtering method has been proposed as a method for forming a wiring on a circuit board constituting an integrated circuit such as an IC or LSI. Here, in the sputtering method, the crystal grain size of the sputtering target used becomes a problem. That is, if the crystal grains of the sputtering target are coarse, the surface unevenness increases, shadowing occurs during sputtering, and a uniform thin film cannot be formed.
In recent years, higher integration of integrated circuits has been promoted, and accordingly, wiring on a circuit board is also required to be ultrafine on the order of submicrons. In order to cope with such ultrathinning, it is necessary to make the crystal grain of the sputtering target finer than before to suppress the occurrence of shadowing.

Moreover, as a material constituting the wiring, in order to keep the electric resistance value low, high-purity copper having a purity of 99.99% or more and a low-concentration copper alloy containing 0.1% by mass or less of an additive element are used. Is suitable. However, the above-described high-purity copper and low-concentration copper alloy tend to be coarse in crystal grains, and it has been difficult to construct a sputtering target corresponding to sub-micron-order ultra-thinning.
Accordingly, various means have been proposed as means for refining crystal grains of high-purity copper or low-concentration copper alloys. For example, Non-Patent Document 1 discloses a method using uniaxial high-temperature forging, and Non-Patent Document 2-4 discloses a method using a super-strong processing method. Patent Document 1 discloses a method in which super-strong processing and heat treatment are combined.
W. Gao, A. Belyakov, H. Miura and T. Sakai, Materials Science and Engineering A, 265, 233-239 (1999) Nobuyasu Tsuji: Iron and Steel, 88 (2002), 359-369 A. Belyakov, K. Tsuzaki, H. Miura, T. Sakai: Acta Mater., Vol. 51 (2003), 847-861 Hiromi Miura, Taku Sakai: Copper and copper alloys, Vol.43 (2004), 56-60 JP 2007-327118 A

By the way, in the method described in Non-Patent Document 1, even if the deformation resistance during forging is set high, the average crystal grain size is about 80 to 100 μm, and it is difficult to refine crystal grains beyond this. there were.
In addition, in the method described in Non-Patent Document 2-4, although the average crystal grain size can be reduced to about 0.2 μm, it has a high strain energy inside, so that it is thermally stable. It lacks the properties and easily recrystallizes and the crystal grains become coarse. For this reason, it could not be used as a sputtering target.
Furthermore, in the method described in Patent Document 1, the average crystal grain size is refined to about several μm, but it is necessary to perform the processing step and the heat treatment step a plurality of times, and super-strong processing is performed. For this reason, a large forging machine is required, and there is a problem that the versatility is lacking and the manufacturing cost is significantly increased.

  The present invention has been made in view of the circumstances described above, and is made of high-purity copper or a low-concentration copper alloy. A crystal grain is refined and a thermally stable fine-grain copper material is produced at low cost. It is an object of the present invention to provide a method for producing a fine-grained copper material that can be produced, a fine-grained copper material produced by this production method, and a sputtering target comprising the fine-grained copper material.

  In order to solve the above-mentioned problems, a method for producing a fine-grained copper material according to the present invention is a multi-axis forging in which compression processing is performed from different directions on a copper material made of high-purity copper or a low-concentration copper alloy. A method for producing a fine-grained copper material that produces a copper material with crystal grains refined, wherein the initial processing temperature T1 for performing the first pass compression process in the multi-axis forging process is The copper material has a temperature at which dynamic recrystallization occurs at least partially.

  In the method for producing a fine-grained copper material according to the present invention, the initial processing temperature T1 for performing the first pass compression processing is a temperature at which dynamic recrystallization occurs at least partially in the copper material, Due to the dynamic recrystallization that occurs in the compression process of the first pass and the initial crystal grain division by this dynamic recrystallization, the crystal grains in the portion where the dynamic recrystallization has occurred are refined. By performing such compression processing from different directions, it becomes possible to expand the refinement by dynamic recrystallization to the entire copper material. For example, a fine crystal grain copper material having an average crystal grain size of 20 μm or less can be obtained. Can be produced.

The temperature at which dynamic recrystallization occurs generally varies with the purity and the amount of processing strain, but is about 0.3 × Tm to 0.6 × Tm (so-called intermediate temperature range) with respect to the melting point Tm of the metal. Therefore, the initial processing temperature T1 becomes relatively high, the load required for the first pass compression processing can be kept small, and the compression processing can be performed with a relatively small forging machine.
Furthermore, since dynamic recrystallization is generated by compression processing at a relatively high temperature, high strain energy is not accumulated inside the crystal, and a thermally stable fine-grained copper material is produced. be able to.

Here, the initial processing temperature T1 is Ts−50 ° C. ≦ T1 ≦ Ts + 50 with respect to the processing softening temperature Ts at which processing softening occurs when the copper material is uniaxially compressed at the same compression rate as the compression processing. It is preferable that it is set within the range of ° C.
Work softening is a phenomenon that occurs when dynamic recrystallization occurs on a large scale. That is, the dynamic recrystallization surely occurs at the processing softening temperature. Here, by setting the initial processing temperature T1 to T1 ≧ Ts−50 ° C., dynamic recrystallization can be reliably generated in the first pass compression processing. In addition, dynamic recrystallization can be generated in a relatively wide range, and the crystal grain size can be made uniform. Further, by setting the initial processing temperature T1 to T1 ≦ Ts + 50 ° C., the grain size of the crystal grains generated by dynamic recrystallization can be kept small, and the crystal grains can be efficiently refined.

Further, after the second pass in the multi-axis forging process, a configuration may be adopted in which the processing temperature Tn for performing the compression processing has a path that is the same as the processing temperature Tn-1 in the immediately preceding pass.
Further, in the second and subsequent passes in the multi-axis forging processing, a configuration may be adopted in which the processing temperature Tn for performing the compression processing has a pass set lower than the processing temperature Tn-1 in the immediately preceding pass.

The range of dynamic recrystallization generated by compression processing increases as the processing temperature Tn increases, but the grain size of the generated crystal grains decreases as the processing temperature Tn decreases. That is, a higher processing temperature Tn is preferable for making the crystal grain size uniform, and a lower processing temperature Tn is preferable for reducing the crystal grain size.
Therefore, in order to make the crystal grain size uniform, the compression processing is performed at a relatively high temperature by setting the processing temperature Tn for performing the compression processing to be the same as the processing temperature Tn-1 in the immediately preceding pass. On the other hand, when the crystal grain size is reduced, the compression processing is performed at a relatively low temperature by making the processing temperature Tn for performing the compression processing lower than the processing temperature Tn-1 in the immediately preceding pass. When the processing temperature Tn for performing the compression processing is higher than the processing temperature Tn-1 in the immediately preceding pass, the grain size of the crystal grains generated by the dynamic recrystallization becomes larger than that in the immediately preceding pass. This is not preferable because it cannot be efficiently miniaturized.

The high-purity copper may have a copper purity of 99.99% by mass or more.
Such high-purity copper is difficult to be refined by conventional methods, but it is possible to refine crystal grains by the method for producing a fine-grain copper material of the present invention. High-purity copper has a low electrical resistance and is suitable as a material constituting the wiring on the substrate.

Further, the low-concentration copper alloy may have an additive element concentration of 0.1% by mass or less. The additive element is preferably one or more elements selected from Ag, Ca, Co, Zr, and Au.
Such a low-concentration copper alloy is obtained by adding 0.1% by mass or less of an additive element to the above-described high-purity copper, and therefore has a low electric resistance and is suitable as a material constituting the wiring on the substrate.
Furthermore, by employing one or more elements selected from Ag, Ca, Co, Zr, and Au as additive elements, the thermal stability can be greatly improved. Further, the crystal grains can be further refined.

The fine crystal grain copper material according to the present invention is manufactured by the above-described method for manufacturing a fine crystal grain copper material, and has an average crystal grain size of 20 μm or less.
This fine-grained copper material is suitable as a material for a sputtering target because it has a smaller average crystal grain size than the conventional one and is excellent in thermal stability. The average crystal grain size is more preferably 10 μm or less. Further, since the fine crystal grain copper material according to the present invention has crystal grains refined by dynamic recrystallization, a dislocation substructure remains in the crystal. Even if the dislocation substructure is subjected to the heat treatment or the like after the multi-axis forging process, it is considered that the dislocation substructure does not completely disappear and a part of the dislocation substructure remains.

Moreover, the sputtering target according to the present invention is characterized by being made of the above-mentioned fine crystal grain copper material.
According to this sputtering target, since the average crystal grain size is as small as 20 μm or less, there are few surface irregularities, the occurrence of shadowing can be suppressed, and a uniform thin film can be formed by sputtering. Thereby, it can be applied to the formation of sub-micron order wiring.

  According to the present invention, a fine-grained copper material that is made of high-purity copper or a low-concentration copper alloy, and that can produce a thermally-stable fine-grained copper material at a low cost while the crystal grains are refined. , A fine crystal grain copper material produced by this production method, and a sputtering target comprising this fine crystal grain copper material can be provided.

Below, the manufacturing method of the fine crystal grain copper material and fine crystal grain copper material which concern on embodiment of this invention are demonstrated.
In the method for producing a fine-grained copper material according to an embodiment of the present invention, high purity copper having a purity of 99.99% or more, or Ag, Ca, Co, Zr, or Au is added to the high purity copper. A fine-grained copper material made of a low-concentration copper alloy to which one or more elements selected from the above are added in an amount of 0.1% by mass or less is manufactured.

  First, an ingot of the above-described high-purity copper or low-concentration copper alloy is produced, and this ingot is subjected to hot forging and heat treatment to produce a uniform bulk material. By cutting and polishing this bulk material, the copper material 1 provided for the multi-axis forging process described later is obtained. Here, in the present embodiment, the copper material 1 has a prismatic shape as shown in FIG. 1 in order to suitably perform multi-axis forging processing that performs compression processing from different directions.

  A multi-axis forging process is performed on such a prismatic copper material 1. In the multi-axis forging process, the copper material 1 is compressed from different directions, and in this embodiment, as shown in FIG. 2, the X-axis, Y-axis, Compression processing is sequentially performed in the three directions of the Z axis.

  Here, the dimensional ratio of the copper material 1 in the X-axis, Y-axis, and Z-axis directions is determined by the compression rate (strain amount) of the compression process. In this embodiment, the amount of true strain in compression processing is 0.6, and the dimensional ratio of the copper material 1 is set to X: Y: Z = 13.01: 9.65: 7.15. When the copper material 1 having this dimensional ratio is subjected to compression processing so that the major axis direction (X-axis direction) is the compression direction, the dimensional ratio of the copper material 1 after the compression processing is X: Y: Z = 7.15. : 13.01: 9.65, and by making the major axis direction (Y-axis direction) the compression direction in the next compression process, the dimensional ratio of the copper material 1 after the compression process is X: Y: Z = 9.65: 7.15: 13.01. Thus, by repeating the compression process in the X-axis, Y-axis and Z-axis directions, the dimensional ratio of the copper material 1 is kept constant, so by sequentially changing the compression direction of the copper material 1, The same amount of strain can be repeatedly applied to the copper material 1.

  And the initial processing temperature T1 which performs the compression process of the 1st pass in this multi-axis forge processing is made into the temperature at which dynamic recrystallization generate | occur | produces in the copper raw material 1 at least partially. Here, when determining the initial processing temperature T1, the temperature at which work softening occurs by a uniaxial compression test having the same compression rate (strain amount) as the compression rate (strain amount) of compression processing in the multi-axis forging process. (Processing softening temperature Ts) is selected. Work softening is a phenomenon that occurs as a result of dynamic recrystallization occurring on a large scale in uniaxial compression at a predetermined compression rate. Therefore, the initial working temperature T1 is determined based on the work softening temperature Ts. Specifically, the initial processing temperature T1 is preferably set within a range of Ts−50 ° C. ≦ T1 ≦ Ts + 50 ° C. with respect to the processing softening temperature Ts.

  The processing temperature Tn for performing the compression processing after the second pass in the multi-axis forging processing may be the same as the processing temperature Tn-1 in the immediately preceding pass, as shown in FIG. Alternatively, as shown in FIG. 4, the temperature may be lowered stepwise by setting it lower than the processing temperature Tn-1 in the immediately preceding pass. Alternatively, these processes may be combined.

Next, a change in crystal structure when such a multi-axis forging process is performed will be described with reference to FIG.
First, in the state before performing the multi-axis forging process, coarse initial crystal grains 10 exist as a whole as shown in FIG. Here, when the first pass compression process is performed with the X-axis direction being the compression direction at the initial process temperature T1, new crystal grains 11 are partially generated by dynamic recrystallization as shown in FIG. 5B. . New crystal grains 11 by dynamic recrystallization are generated mainly at the grain boundaries of the initial crystal grains 10 to divide the initial crystal grains 10. Thus, since dynamic recrystallization partially occurs, many initial crystal grains 10 remain, and the size of the crystal grains becomes extremely non-uniform after one pass.

  Next, compression processing for the second pass is performed at the processing temperature T2 with the Y-axis direction as the compression direction. At this time, the processing temperature T2 is set to be lower than the initial processing temperature T1. Then, as shown in FIG. 5C, new crystal grains 12 are generated by dynamic recrystallization. At this time, the grain size of the newly generated crystal grain 12 is smaller than that of the crystal grain 11 generated in the first pass. Further, the dynamic recrystallization of the second pass is mainly generated at the grain boundaries of the crystal grains, and the initial crystal grains 10 themselves are also divided. Further, the crystal grains 11 generated in the first pass are slightly coarsened.

Next, the third compression process is performed at the processing temperature T3 with the Z-axis direction as the compression direction. At this time, the processing temperature T3 is lower than the processing temperature T2 of the immediately preceding pass. Then, as shown in FIG. 5D, new crystal grains 13 are generated by dynamic recrystallization. At this time, the newly generated crystal grain 13 has a smaller particle size than the crystal grain 12 generated in the second pass. In addition, the initial crystal grains 10 themselves are divided, and the crystal grain diameter is gradually uniformized.
Thus, by performing compression processing in order from the X-axis direction, the Y-axis direction, and the Z-axis direction, the crystal grains of the copper material 1 are refined. The average crystal grain size of the fine crystal grain copper material according to the present embodiment thus obtained is set to 20 μm or less, more preferably 10 μm or less.

  According to the method for manufacturing a fine crystal grain copper material and the fine crystal grain copper material according to the present embodiment configured as described above, the initial processing temperature T1 for compressing the first pass is reduced by dynamic recrystallization. Since the temperature is set at least partially, the initial processing temperature T1 becomes relatively high, and the load required for the compression process in the first pass can be kept small. Processing can be performed.

  In this way, dynamic recrystallization occurs by compression processing and the original crystal grains are divided, so that the crystal grains can be made finer and uniform by repeating this compression processing. Furthermore, since dynamic recrystallization is performed by compression processing at a relatively high temperature, high strain energy is not accumulated inside, and a thermally stable fine-grained copper material can be produced.

  The initial processing temperature T1 is Ts−50 ° C. ≦ T1 ≦ with respect to the processing softening temperature Ts at which processing softening occurs when the copper material 1 is uniaxially compressed at the same compression rate (strain amount) as the compression processing. Since it is set within the range of Ts + 50 ° C., the dynamic recrystallization can be surely generated in the compression process of the first pass, and the grain size of the crystal grains generated by the dynamic recrystallization can be suppressed to be small. Grain refinement can be performed efficiently.

  Further, the processing temperature of the second pass is set lower than the initial processing temperature T1 of the first pass that is the immediately preceding pass, and the processing temperature of the third pass is set lower than the processing temperature T2 of the second pass that is the immediately preceding pass, In particular, since the processing temperature is lowered, the grain size of the crystal grains newly generated by the dynamic recrystallization decreases for each pass, and the crystal grains can be refined efficiently.

  In addition, the fine crystal grain copper material according to the present embodiment has an average crystal grain size of 20 μm or less, more preferably 10 μm or less, so that there are few surface irregularities and thermal stability. Are better. Therefore, by forming a sputtering target with this fine crystal grain copper material, generation of shadowing can be suppressed and a uniform thin film can be formed.

As mentioned above, although embodiment of this invention was described, this invention is not limited to this, It can change suitably in the range which does not deviate from the technical idea of the invention.
For example, although it has been described as a configuration in which compression processing is performed in order in the X-axis, Y-axis, and Z-axis directions, the present invention is not limited to this, and any configuration may be used as long as compression processing is performed from different directions.

  Furthermore, although the distortion amount at the time of compression processing was demonstrated as 0.6, it is not limited to this, A distortion amount can be set suitably. As described above, when the compression processing is sequentially performed in the X-axis, Y-axis, and Z-axis directions, by setting the dimensional ratio of the X-axis, Y-axis, and Z-axis of the copper material, The crystal grain size can be reduced without changing the outer shape. For example, when the amount of strain in one pass is 0.8, the dimensional ratio of the X-axis, Y-axis, and Z-axis of the copper material is X-axis: Y-axis: Z-axis = 2.22: 1.49: It will be set to 1.0.

  Hereinafter, a specific example is given and the manufacturing method of the fine crystal grain copper material and fine crystal grain copper material which concern on this invention are demonstrated.

(Test pieces)
An ingot of high-purity copper or low-concentration copper alloy having a predetermined composition described later was produced, the ingot was heated to 760 ° C., hot forged, and rapidly cooled in water to obtain a bulk material. The bulk material was cut and faced to prepare prismatic test pieces shown in FIG.

(Compression test)
The compression process of each pass of the multi-axis forging process was performed using a Tensilon high-temperature compression tester manufactured by A & D Corporation. Here, the strain rate when compressing each pass was controlled to 3.0 × 10 ⁻³ s ⁻¹ . A graphite lubricant was used as the lubricant.

(Tissue observation)
A sample for observing the structure was cut out from a test piece with a cross section parallel to the final compression direction, and was subjected to mechanical polishing (emery paper / buff) and electrolytic polishing. The electrolytic polishing was carried out using an electrolytic polishing solution of 50 volume% phosphoric acid and 50 volume% distilled water at room temperature (25 ° C.) at a voltage of 1.8 V for about 40 seconds.
The sample after this electropolishing was analyzed by Orient Imaging Microscope (OIM) manufactured by TSL, and the average crystal grain size was calculated.
Further, after electrolytic polishing, electrolytic corrosion was performed using an electrolytic polishing liquid at room temperature (25 ° C.) at a voltage of 0.5 V for about 10 seconds, and observed with an optical microscope.

Example 1
As Example 1, a fine crystal copper material made of high purity copper (so-called 6N copper) having a purity of 99.9999% or more was produced.
FIG. 6 shows an initial OIM map (before the multi-axis forging process). The crystal grain size D _{0 at the} initial stage (before the multi-axis forging process) was D ₀ = 100 μm.

Next, a uniaxial compression test was performed on a copper material made of high-purity copper at various temperatures (503K, 533K, 563K, and 593K) with a strain amount of 0.6 and a strain rate of 3.0 × 10 ⁻³ s ^−1. It went on condition of. A stress-strain curve is shown in FIG. Work softening was observed at 593 K (320 ° C.), and it is considered that large-scale dynamic recrystallization occurred at this temperature.
FIG. 8 shows an OIM map and an image quality map of a test piece subjected to a uniaxial compression test at various temperatures (503K, 563K, and 593K). It is confirmed that slight dynamic recrystallization occurs even at 503 K (230 ° C.). It can be seen that the region where dynamic recrystallization occurs increases as the compression test temperature increases.
Here, FIG. 9 shows the relationship between the grain size of new crystal grains generated by dynamic recrystallization by the uniaxial compression test and the compression test temperature. It is confirmed that the lower the compression test temperature, the smaller the grain size of new crystal grains.

From the results of this uniaxial compression test, the initial processing temperature T1 for performing the first pass compression processing of the multi-axis forging processing was set to 593K (320 ° C.).
As the multi-axis forging process, the amount of strain per pass was set to 0.6 and the amount of accumulated strain was 3.0, that is, compression processing was performed for 5 passes.
In the isothermal process, the processing temperatures from the first pass to the fifth pass were all set to 593K (320 ° C.). In the temperature lowering step, the processing temperature was decreased by 30 ° C. for each pass, and the fifth processing temperature was set to the same processing temperature (503 K) as the fourth processing.

  FIG. 10 shows an OIM map of the copper material 1 after the first pass compression processing. The OIM maps from 2 passes to 5 passes after the isothermal process are shown in FIGS. In addition, FIGS. 15 to 18 show OIM maps from the second pass to the fifth pass in the temperature lowering process. Furthermore, the change of the average crystal grain size for each pass is shown in FIG.

In the isothermal process, the average crystal grain size D ₅ after 5 passes is 24.4 μm, which is smaller than the initial average crystal grain size D ₀ = 100 μm. The average crystal grain size D ₁ of the following one pass is 29.3Myuemu, 1 pass onward, no significant miniaturization is realized. This is because the compression process is performed at the same temperature from the first pass to the fifth pass, and therefore the grain size of the new crystal by dynamic recrystallization is the same from the first pass to the fifth pass. The

On the other hand, in the temperature lowering step, the average crystal grain size D ₅ after 5 passes is 10.8 μm, which is much finer than the initial average crystal grain size D ₀ = 100 μm. 1 average crystal grain size D ₁ of the post-path is 29.3Myuemu, that crystals 1 pass onward are miniaturized is confirmed. This is judged to be because the grain size of new crystal grains by dynamic recrystallization is reduced stepwise because the compression process is performed by lowering the processing temperature from the first pass to the fourth pass.

(Example 2)
As Example 2, a fine-grained copper material made of a low concentration copper alloy (hereinafter referred to as Cu-Ag alloy) in which 0.035% by mass of Ag was added to high purity copper having a purity of 99.9999% or more was produced.
FIG. 20 shows an initial OIM map (before the multi-axis forging process). The crystal grain size D ₀ at the initial stage (before the multi-axis forging process) was D ₀ = 72 μm. This Cu—Ag alloy was annealed at 550 ° C. × 2 h after the hot forging described above to achieve uniformity.

Next, a uniaxial compression test was performed on a copper material made of a Cu-Ag alloy at various temperatures (563K, 593K, 623K, 643K, 663K, 683K, 703K), a strain amount of 0.6, and a strain rate of 3.0. It carried out on the conditions of * 10 <^-3> s < ^{-1 >} . A stress-strain curve is shown in FIG. Even at 703 K (430 ° C.), no work softening is observed, and it is confirmed that the heat is very stable.
FIG. 22 shows an OIM map and an image quality map of a test piece subjected to a uniaxial compression test at various temperatures (563 K, 643 K, and 703 K). It is confirmed that dynamic recrystallization has partially occurred at 703K.
Further, FIG. 23 shows the relationship between the grain size of new crystal grains generated by dynamic recrystallization by the uniaxial compression test and the compression test temperature. The lower the compression test temperature, the smaller the grain size of the new crystal grains, but the temperature dependence is small compared to high-purity copper (6N copper).

From the results of this uniaxial compression test, the dynamic recrystallization region is still very limited, but the initial processing temperature T1 for performing the compression processing in the first pass of the multiaxial forging processing was set to 703 K (430 ° C.). In order to generate larger crystal grains more uniformly, it is preferable to set T1 to a temperature higher than 703K. In this case, work softening appears in the stress-strain curve.
As the multi-axis forging process, the amount of strain per pass was set to 0.6 and the amount of accumulated strain was 3.0, that is, compression processing was performed for 5 passes.
In the isothermal process, the processing temperatures from the first pass to the fifth pass were all set to 703 K (430 ° C.). In the temperature lowering process, the processing temperature was decreased by 30 ° C. for each pass, and the fifth processing temperature was set to the same processing temperature (613 K) as the fourth processing.

  FIG. 24 shows an OIM map of the copper material after the first pass compression processing. The OIM maps from 2 passes to 5 passes after the isothermal process are shown in FIGS. In addition, FIGS. 29 to 32 show OIM maps from the second pass to the fifth pass in the temperature lowering process. Furthermore, the change of the average crystal grain size for each pass is shown in FIG.

In the isothermal process, the average crystal grain size D ₅ after 5 passes was 9.4 μm, which was smaller than the initial average crystal grain size D ₀ = 74 μm. In addition, it was confirmed that the crystal grains can be greatly refined compared to high-purity copper (6N copper).
On the other hand, in the temperature lowering process, the average crystal grain size D ₅ after 5 passes is 4.3 μm, which is smaller than the initial average crystal grain size D ₀ = 74 μm.

(Example 3)
As Example 3, a fine grain copper material made of a low-concentration copper alloy (hereinafter referred to as Cu—Ca alloy) in which 0.011% by mass of Ca was added to high-purity copper having a purity of 99.9999% or more was produced.
FIG. 34 shows an initial OIM map (before the multi-axis forging process). The crystal grain size D _{0 at the} initial stage (before the multi-axis forging process) was D ₀ = 58 μm. The Cu—Ca alloy was homogenized by annealing at 630 ° C. × 2 h after the aforementioned hot forging.

Next, the uniaxial compression tests on copper material consisting of Cu-Ca alloy, various temperatures (563K, 593K, 643K), the strain amount 0.6, strain rate 3.0 × ¹⁰ -3 ^{s -1} Performed under conditions. The resulting stress-strain curve is shown in FIG. Work softening was observed at 643 K (370 ° C.).
FIG. 36 shows an OIM map and an image quality map of a test piece subjected to a uniaxial compression test at various temperatures (563K, 593K, 643K). It is confirmed that dynamic recrystallization occurs throughout. FIG. 37 shows the relationship between the grain size of new crystal grains generated by dynamic recrystallization by the uniaxial compression test and the compression test temperature. It is confirmed that the lower the compression test temperature, the smaller the grain size of new crystal grains.

From the results of this uniaxial compression test, the initial processing temperature T1 for performing the compression processing in the first pass of the multi-axis forging processing was set to 643K (370 ° C.).
As the multi-axis forging process, the amount of strain per pass was set to 0.6 and the accumulated strain amount was set to 1.8, that is, compression processing was performed for 3 passes.
The processing temperature T2 for the second pass was 623K (350 ° C.), and the processing temperature T3 for the third pass was 593K (320 ° C.).

FIG. 38 shows an OIM map of the copper material after the first pass compression processing. 39 and 40 show OIM maps from the second pass through the third step after the temperature lowering process. Furthermore, the change of the average crystal grain size for each pass is shown in FIG.
3 mean crystal grain size _{D 5} after the path is miniaturized compared to 11.2μm and early average crystal grain size _D 0 = 58 .mu.m. In addition, it was confirmed that the crystal grains can be greatly refined compared to high-purity copper (6N copper).

It is the schematic of the copper raw material used for the manufacturing method of the fine crystal grain copper material which is this embodiment. It is a conceptual diagram of the multi-axis forging process used for the manufacturing method of the fine crystal grain copper material which is this embodiment. It is a pattern figure (isothermal process) of the processing temperature of a multi-axis forging process. It is a pattern figure (temperature-falling process) of the process temperature of a multi-axis forge process. It is explanatory drawing explaining the process of refinement | miniaturization of a crystal | crystallization. It is an OIM map before multi-axis forging processing of high purity copper (6N copper). It is a stress-strain curve figure which shows the result of the uniaxial compression test of high purity copper (6N copper). It is an OIM map after the uniaxial compression test of high purity copper (6N copper). It is a relationship figure of the temperature in the uniaxial compression test of high purity copper (6N copper), and the grain size of the newly generated crystal. It is an OIM map after performing the 1st pass compression processing at 593K in the test piece of high purity copper (6N copper). It is an OIM map after compressing the second pass at 593K. It is an OIM map after compressing the third pass at 593K. It is an OIM map after performing the compression process of the 4th pass at 593K. It is an OIM map after compressing the 5th pass at 593K. It is an OIM map after performing the second pass compression processing at 563K. It is an OIM map after performing the compression process of the 3rd pass at 533K. It is an OIM map after performing the compression process of the 4th pass at 503K. It is an OIM map after performing the compression process of the 5th pass at 503K. It is a graph which shows the average crystal grain diameter for every pass. It is an OIM map before the multi-axis forging process of a low concentration alloy (Cu-Ag alloy). It is a stress-strain curve figure which shows the result of the uniaxial compression test of a low concentration alloy (Cu-Ag alloy). It is an OIM map after the uniaxial compression test of a low concentration alloy (Cu-Ag alloy). It is a relationship diagram of the temperature in the uniaxial compression test of a low concentration alloy (Cu-Ag alloy) and the grain size of the newly generated crystal. It is an OIM map after performing the 1st pass compression processing at 703K in the test piece of a low concentration alloy (Cu-Ag alloy). It is an OIM map after compressing the second pass at 703K. It is an OIM map after performing the compression process of the 3rd pass at 703K. It is an OIM map after performing the compression process of the 4th pass at 703K. It is an OIM map after performing the compression process of the 5th pass at 703K. It is an OIM map after compressing the 2nd pass at 673K. It is an OIM map after compressing the third pass at 643K. It is an OIM map after performing the compression process of the 4th pass at 613K. It is an OIM map after performing the compression process of the 5th pass at 613K. It is a graph which shows the average crystal grain diameter for every pass. It is an OIM map before the multi-axis forging process of a low concentration alloy (Cu-Ca alloy). It is a stress-strain curve figure which shows the result of the uniaxial compression test of a low concentration alloy (Cu-Ca alloy). It is an OIM map after the uniaxial compression test of a low concentration alloy (Cu-Ca alloy). It is a relationship figure of the temperature in the uniaxial compression test of a low concentration alloy (Cu-Ca alloy), and the grain size of the newly generated crystal. It is an OIM map after compressing the 1st pass at 643K in the test piece of a low concentration alloy (Cu-Ca alloy). It is an OIM map after performing the compression process of the 2nd pass at 623K. It is an OIM map after compressing the third pass at 593K. It is a graph which shows the average crystal grain diameter for every pass.

Explanation of symbols

1 Copper material

Claims (9)

A fine grained copper material that produces a copper material with crystal grains refined by performing multi-axis forging processing that compresses the copper material made of high-purity copper or low-concentration copper alloy from different directions. A manufacturing method of
An initial processing temperature T1 for performing compression processing in the first pass in the multi-axis forging processing is a temperature at which dynamic recrystallization occurs at least partially in the copper material. Production method.   The initial processing temperature T1 is in a range of Ts−50 ° C. ≦ T1 ≦ Ts + 50 ° C. with respect to a processing softening temperature Ts at which processing softening occurs when the copper material is uniaxially compressed at the same compression rate as the compression processing. The method for producing a fine-grained copper material according to claim 1, wherein   The second or subsequent pass in the multi-axis forging process has a pass in which the processing temperature Tn for performing the compression processing is the same as the processing temperature Tn-1 in the immediately preceding pass. The manufacturing method of the fine-grain-grain copper material of description.   The second and subsequent passes in the multi-axis forging processing include a pass in which the processing temperature Tn for performing the compression processing is set lower than the processing temperature Tn-1 in the immediately preceding pass. 4. The method for producing a fine grain copper material according to any one of 3 above.   The method for producing a fine-grained copper material according to any one of claims 1 to 4, wherein the high-purity copper has a copper purity of 99.99% by mass or more.   The method for producing a fine-grained copper material according to any one of claims 1 to 4, wherein the low-concentration copper alloy has an additive element concentration of 0.1% by mass or less. .   The method for producing a fine-grained copper material according to claim 6, wherein the additive element is one or more elements selected from Ag, Ca, Co, Zr, and Au.   A fine-grained copper material produced by the method for producing a fine-grained copper material according to any one of claims 1 to 7, wherein an average crystal grain size is 20 µm or less.   A sputtering target comprising the fine-grained copper material according to claim 8.

Images