A high-purity high-entropy aluminum alloy sputtering coating material

Abstract

The present invention discloses a high-purity high-entropy aluminum alloy sputtering coating material. The present invention improves the reflectivity of the alloy film layer by adding a specific amount of silicon and copper to pure aluminum. At the same time, by reasonably adding two or more elements among nickel, lanthanum, chromium and manganese to form an alloy phase, the present invention has the characteristics of improving its thermal stability, high adhesion and low resistance. The crystal structure of the high-entropy aluminum alloy sputtering coating material is a mixture of at least five-element, four-element, and three-element alloys with AlSiCu as the matrix. It is an aluminum alloy film layer material that has low contact resistance, strong oxidation resistance, high reflectivity and high adhesion.

Description

Technical Field

[0001] The present invention relates to the technical field of sputtering target materials, and in particular to a high-purity high-entropy aluminum alloy sputtering coating material. Background Art

[0002] In the display field, pure Al or Al alloy films are usually used as electrode materials. However, when such films are used in direct contact with pixel electrodes, insulating aluminum oxide will form on the interface, thereby increasing the contact resistance.

[0003] There is also a technology that uses Al-Ni alloy film as a wiring material. The reflectivity of the Al-Ni alloy film is reduced, and there are also problems such as poor adhesion between the film layer and the base material and poor thermal stability. As a result, the photoelectric performance of the display device deteriorates after etching and high temperature conditions in the subsequent display process.

[0004] Therefore, it is very necessary to develop an aluminum alloy film material with low contact resistance, strong oxidation resistance, high reflectivity and high adhesion. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a high-purity high-entropy aluminum alloy sputtering coating material, which has low contact resistance, strong oxidation resistance, high reflectivity and high adhesion.

[0006] In order to achieve the above-mentioned object, the technical solution adopted by the present invention is: a high-purity high-entropy aluminum alloy sputtering coating material, which is an AlSiCuX alloy, which is composed of Al, Si, Cu, and X elements, wherein the X elements are any two elements among Ni, La, Cr and Mn, and in terms of atomic percentage of the elements, 2<Cu<5at%, 1<Si<3at%, 2<X<10at%, and the remainder is Al and inevitable trace impurity elements, and its crystal structure is a mixture of at least a quinary alloy, a quaternary alloy and a ternary multi-element alloy with AlSiCu as the matrix.

[0007] The total contents of C and N in the alloy material are both less than 50 ppm, the oxygen content is less than 500 ppm, the average grain size is ≤50 μm, and the purity is greater than 99.99%.

[0008] The Cu forms a limited solid solution in the crystal, and Cu atoms squeeze into the Al to cause lattice distortion.

[0009] The Ni forms conductive nickel precipitates at the crystal interface.

[0010] The La is present in the form of Al 11 La3 precipitation phase exists.

[0011] The La forms a strong bond with the adjacent ITO layer due to its high bonding energy with oxygen.

[0012] The Cr forms an intermetallic compound in Al.

[0013] The Mn dissolves in Al and forms a dispersed intermetallic compound MnAl6.

[0014] The X element is composed of Ni and La, and the alloy material is Al in atomic percentage. 86 Cu4Si2Ni6La2at%.

[0015] The alloy material is A1 in terms of atomic percentage of elements 85 Cu4Si2Ni6Cr3at%,A1 87 Cu4Si2Mn5La2 at%, A1 89 Cu3si2Cr4La2 at% or A1 88 Cu3si2Cr5Mn2 at%.

[0016] The advantages of the present invention over the prior art are: the present invention improves the reflectivity of the alloy film layer by adding a specific amount of silicon and copper to pure aluminum, and at the same time forms an alloy phase by reasonably adding two or more elements among nickel, lanthanum, chromium and manganese. The process of the present invention is simple, the production cost is low, and the process is easy to implement and control, with high stability and high yield; the high-purity high-entropy aluminum alloy sputtering coating material prepared by the present invention has the characteristics of improving its thermal stability and high adhesion and low resistance. The crystal structure of the high-entropy aluminum alloy sputtering coating material is a mixture of at least five-element, four-element, three-element and other multi-element alloys with AlSiCu as the matrix. It is an aluminum alloy film layer material that has low contact resistance, strong oxidation resistance, high reflectivity and high adhesion. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the alloy metallographic diagram of the high-purity high-entropy aluminum alloy sputtering coating material of the present invention.

[0018] Figure 2 and 3 Detection of oxygen content in high-purity high-entropy aluminum alloy sputtering coating materials.

[0019] Figure 4 This is a flaw detection diagram of the large-size, high-purity, high-entropy aluminum alloy target material of the present invention.

[0020] Figure 5 This is the AFM roughness detection image of the aluminum alloy coating layer of sample A3#, with an AFM roughness of 1.25 nm.

[0021] Figure 6This is the AFM roughness detection image of the aluminum alloy coating layer of sample A4#, with AFM roughness = 0.84nm.

[0022] Figure 7 This is a test chart of the adhesion of a grid knife to aluminum alloy coatings with different formulations.

[0023] Figure 8 This is the reflectivity spectrum of the film layer of the present invention.

[0024] Figure 9 is the average sheet resistance of the film layer of the present invention.

[0025] Figure 10 This is a comparison chart of experimental data for samples A1#~A8#.

[0026] Figure 11 This is a SEM comparison of the thermal stability of the film layer of different formula materials. DETAILED DESCRIPTION

[0027] A high-purity, high-entropy aluminum alloy sputtering coating material, the alloy material is an AlSiCuX alloy, composed of aluminum (Al), silicon (Si), copper (Cu), and X elements, wherein the X elements are any two elements selected from nickel (Ni), lanthanum (La), chromium (Cr), and manganese (Mn), and in terms of atomic percentage, 2 < Cu < 5at%, 1 < Si < 3at%, 2 < X < 10at%, with the remainder being Al and inevitable trace impurity elements. The crystal structure is a mixture of at least a quinary alloy, a quaternary alloy, and a ternary multi-element alloy with AlSiCu as the matrix. Figures 1 to 11 shown.

[0028] This invention enhances the reflectivity of the alloy film by adding specific amounts of silicon (Si) and copper (Cu) to pure aluminum. Furthermore, by rationally adding at least two of the elements nickel (Ni), lanthanum (La), chromium (Cr), and manganese (Mn) to form an alloy phase, it improves thermal stability, enhances adhesion, and achieves low electrical resistance. The alloy material has a total carbon and nitrogen content of less than 50 ppm, an oxygen content of less than 500 ppm, an average grain size of ≤50 μm, a purity greater than 99.99%, and a reflectivity of ≥90% for a specific wavelength range, meeting the current requirements of the emerging display industry for high-purity sputtering materials.

[0029] The principle of the present invention is to add silicon and copper elements to pure aluminum to maintain a high reflectivity of the high-purity aluminum matrix itself, so that the reflectivity of the alloy gold material to wavelengths within a specific range is ≥90%.

[0030] When copper (Cu) is added, it forms a limited solid solution in aluminum. Cu atoms squeeze into Al to produce lattice distortion. According to the atomic percentage of the element, 2<Cu<5at%, which hinders the movement of dislocations, plays a role in solid solution strengthening, and improves the conductivity of the film. However, the addition amount must also be controlled within a certain range. Too high a copper content will lead to poor oxidation resistance. The optimal copper atomic percentage is 3<Cu<4at%.

[0031] Adding silicon can inhibit the growth of aluminum grains and phase transformation, stabilize the structure and properties of aluminum alloys, reduce the resistivity between film layers, and improve the thermal stability and alloy strength of the alloy material. At the same time, it can improve the adhesion between the alloy material and the substrate silicon wafer. However, excessive silicon content will lead to increased brittleness of the material during processing and low yield rate. The preferred atomic percentage of silicon is 1<si<2at%.

[0032] Since the solid solubility of Ni in Al is extremely small and basically negligible, Ni can form conductive nickel precipitates at the interface, inhibiting the formation of aluminum oxide and reducing the resistivity of the alloy gold material.

[0033] Add lanthanum (La), because the solid solubility of La in Al is very low, La in the crystal is in the form of Al 11 The presence of La3 precipitated phase improves the stability and strength of the alloy while ensuring high conductivity of the aluminum alloy. Rare earth La forms a strong bond with the adjacent ITO layer due to its high bond energy with oxygen, blocking the diffusion of loose oxygen atoms in ITO and improving the thermal stability of the alloy gold material.

[0034] Adding chromium (Cr) forms intermetallic compounds in Al, which hinders the nucleation and growth process of recrystallization, strengthens the alloy material, and is beneficial to improving high temperature resistance and oxidation resistance.

[0035] By adding manganese (Mn), Mn dissolves in Al and forms a dispersed intermetallic compound MnAl6, which can hinder grain growth and refine the grains. At the same time, the electrode potential of MnAl6 is similar to that of the matrix, which makes the alloy material have excellent corrosion resistance and processing plasticity.

[0036] The high-purity high-entropy aluminum alloy sputtering coating material of the present invention, as a newly developed multi-principal alloy, surpasses the design limitations of traditional alloy materials based on a single majority main element, and has an alloy system with many excellent special properties. The final overall performance effect of the high-entropy aluminum alloy sputtering coating material is greater than the sum of its parts. The present invention obtains good oxidation resistance and thermal stability by reasonably matching the above-mentioned relevant element ratios, while having a high-entropy aluminum alloy film material with high reflectivity. In addition to the preferred addition of elemental components, the present invention also selects target material indicators that can obtain a smooth and dense film deposition effect. Preferably, the C and N content is controlled to be less than 40ppm, the oxygen content is less than 400ppm, the average grain size is ≤40um, the purity is ≥99.999% (not less than 5N purity), the material composition is uniform, there is no segregation, the average roughness of the alloy film is <0.85nm, and the film reflectivity is ≥95%, thereby obtaining an aluminum alloy film material with high reflectivity, high oxidation resistance and low resistance.

[0037] A method for producing a high-purity high-entropy aluminum alloy sputtering coating material comprises the following steps:

[0038] Atomization granulation step, according to Al 90 The atomic percentage of Cu6Si4at% is shown in the following example: pure aluminum powder, pure copper powder and pure silicon powder with low oxygen content in corresponding weight proportions are added to the atomizing granulator, and the atomizing granulation method is used to prepare the aluminum powder with the atomic percentage of Cu6Si4at%. 90 Cu6Si4at% alloyed powder with a particle size of 8 to 30 μm and an oxygen content of ≤1000 ppm; Al-Cu-Si pre-alloyed powder; 86 The atomic percentage of Cu4Si2Ni6La2at% is as follows: high-purity nickel powder and lanthanum powder are continuously added to the atomizing granulator in the atomizing granulation step to prepare an alloyed mixed powder. The powder particle size of the mixed powder is 8 to 30 μm and the oxygen content is less than 1000 ppm;

[0039] The ball milling step comprises the following steps: placing the mixed powder into a mechanical ball milling device, adding liquid nitrogen to the mechanical ball milling device, and then performing mechanical ball milling and mixing treatment. During the mechanical ball milling process, the temperature of the ball mill and the mixed powder is always maintained below 50° C.; during the ball milling process, argon gas is filled in, the ball milling speed of the mechanical ball milling device is controlled at 200 revolutions per minute, the ball-to-material ratio is 4:1, and the ball milling process and argon-protected ball milling are performed for 5 to 8 hours to partially alloy or surface-alloy the powder to obtain a mixed ball milled powder.

[0040] In the densification pretreatment step, the mixed ball-milled powder can is placed in the cavity of a hot press mold, the cavity is heated and pressurized, and the mixed ball-milled powder is first subjected to a constant temperature and pressure treatment at a temperature of 150 to 250° C. for 1 to 3 hours;

[0041] In the sintering step, after the cavity is emptied, the cavity is heated and pressurized, the mixed ball-milled powder is subjected to a constant temperature and pressure treatment at a temperature of 420-480° C. for 3-5 hours, and hot-pressed sintering is performed to prepare an aluminum alloy ingot;

[0042] The aluminum alloy ingot is subjected to vacuum annealing treatment and then sliced ​​to obtain an alloy plate. Specifically, the aluminum alloy ingot is subjected to vacuum annealing treatment at a temperature of 380°C for 2 hours, and then sliced ​​by machining after vacuum annealing to obtain an alloy plate of 100mm*100mm*6mm.

[0043] In the binding step, the alloy plate and the copper back plate are welded and bound to prepare a high-purity high-entropy aluminum alloy sputtering coating material. After passing the C~SCAN inspection, a high-purity high-entropy aluminum alloy sputtering coating material is obtained.

[0044] The present invention prepared comparative example samples by the above process: A1# sample Al 94 Ni6at% target, A2# sample Al 92 Ni6La2at% target and A3#A1 88 Ni6Cu4La2at% target; The present invention prepared the example sample by the above process: A4# sample Al 86 Cu4Si2Ni6La2at%, A5# sample A1 85 Cu4Si2Ni6Cr3 at%, A6# sample A1 87 Cu4Si2Mn5La2, A7# sample A1 89 Cu3si2Cr4La2 at% and A8# sample A1 88 Cu3si2Cr5Mn2 at%, and then the eight alloy targets were magnetron sputtered on several 100*100mm silicon substrates, with an aluminum alloy film thickness of 50±5nm. Finally, the reflectivity, resistivity, high temperature stability and adhesion of the coated samples were tested and compared. The comparative experimental data are shown in the figure. Figure 10 shown.

[0045] Among them, the average grain size of the material metallographic detection of samples A4~A8# is less than 50um, the density is good, the internal structure is evenly distributed without segregation, the gas impurity content C is less than 50ppm, N is less than 50ppm, and the oxygen content is less than 500ppm, as shown in Figures 1 and 2.

[0046] 1. Film reflectivity test comparison:

[0047] The reflectivity of the film in different bands was tested using a UV-visible spectrophotometer. Figure 8As shown, the average reflectivity of samples A1# and A2# is lower than 88%, because they contain nickel and do not contain copper and silicon. Their reflectivity is significantly lower than that of other materials. 88 Although copper is added to Ni6Cu4La2at%, the reflectivity is increased to 92.6%, but it is lower than the reflectivity of A4~A8# samples. The reflectivity of A4~A8# samples is greater than 95%. It can be seen that adding copper and silicon can effectively increase its reflectivity to ≥95%, which better meets the 90% requirement for new display.

[0048] 2. Sheet resistance test comparison:

[0049] The sheet resistance of four different areas of each film was tested using a thin film resistor meter, and the average value was calculated. It was found that the sheet resistance of samples A1 to A3# was relatively large, exceeding the industry requirement, which requires a sheet resistance of less than 2000mΩ / Sq. 92 Due to the addition of La, part of the nickel and lanthanum form a nickel-lanthanum alloy phase in Ni6La2at%, which reduces the precipitation of conductive nickel at the interface. As a result, the resistance increases to 3122mΩ / Sq compared with the A1# sample. After adding a certain amount of copper to the A2# sample, the A3# sample improves the overall conductivity of the material, but still does not meet the industry requirements.

[0050] The average sheet resistivity of samples A4 to A8# of the present invention is less than 1500 mΩ / Sq. Figure 9 As shown, the resistivity value is significantly lower than the industry requirement of 2000 mΩ / Sq, and the resistivity values ​​at each point in the region fluctuate slightly, demonstrating excellent stability. This is due to the fact that the varying atomic sizes in the high-entropy phase cause displacements at each lattice position. These distortions are much more severe than those in conventional alloys, resulting in a higher enthalpy. The high-entropy aluminum alloy of the present invention transcends the limitations of conventional alloy design and belongs to an alloy system with numerous exceptional properties. The overall performance of the aluminum alloy material is greater than the sum of its parts, ultimately exhibiting excellent electrical properties.

[0051] 3. Comparison of high temperature thermal stability:

[0052] The eight films of samples A1 to A8# were annealed at 350°C for 1 hour in an atmospheric environment, and the surface of the films was visually inspected for discoloration. 86 Cu4Si2Ni6La2at%, A5# sample A1 85 Cu4Si2Ni6Cr3 at%, A6# sample A1 87 Cu4Si2Mn5La2, A7# sample A1 89Cu3si2Cr4La2at% and A8# sample A1 88 The membranes of the five samples with Cu3si2Cr5Mn2 at% did not change color and had good high-temperature oxidation resistance.

[0053] Figure 5 and 6 The figure shows a comparison of the AFM roughness measurements of samples A3# and A4# at room temperature. The average roughness of the alloy coating layer of sample A3# is 1.25nm, and its surface smoothness and density are inferior to those of the film layer of sample A4# of the present invention, which has an average roughness of 0.84nm. This shows that the material formula and corresponding indicators of the present invention, such as C and N content less than 50ppm, oxygen content less than 500ppm, and average grain size ≤50μm, achieve smooth and dense film deposition.

[0054] Samples A2#, A3# and A4# were taken separately. 86 SEM comparison of Cu4Si2Ni6La2at% membrane before and after annealing, Figure 11 As shown in the figure, after annealing at 350℃, clusters of protrusions ranging from 50 to 500nm were generated on the film surface of samples A2# and A3#, and their surfaces were oxidized to varying degrees, which showed that the film became darker in the macroscopic sense. However, the Al 86 After annealing, the Cu4Si2Ni6La2at% film had no foreign matter on its surface, and the film layer remained dense and uniform. Macroscopically, the film layer did not change color. The alloy film layer of the present invention exhibited excellent high-temperature oxidation resistance.

[0055] 4. Adhesion test comparison:

[0056] Adhesion was tested using the grid knife tape method. Film bonding strength tests were performed on eight types of membranes at room temperature and after annealing at 350°C for 1 hour according to ASTM D3359-97. Figure 7 Shown are actual photos of the A1, A2, A4, and A5 coating samples being tested with the grid knife tape method at room temperature. The A1 and A2 films shed severely, while the A4 and A5 films did not shed at all. Actual photos of the coating samples being tested with the grid knife tape method at room temperature. The A1# and A2# films shed severely, while the A4# and A5# films did not shed at all. The test shows that the adhesion of the A1# and A2# samples is not ideal, and partial shedding occurs before and after high temperature. The adhesion of the A3# sample also decreases after high-temperature annealing, and shedding occurs. The film layers of the A4# to A8# samples of the present invention did not shed before and after high temperature, showing 5A-level adhesion, which is a better effect.

[0057] The above contents are only preferred embodiments of the present invention. For ordinary technicians in this field, according to the concept of the present invention, there may be changes in the specific implementation methods and application scopes. The contents of this specification should not be understood as limiting the present invention.

Claims

1. A high-purity high-entropy aluminum alloy sputtering coating material, characterized by: The alloy material is an AlSiCuX alloy, which is composed of Al, Si, Cu, and X elements, wherein the X elements are any two elements among Ni, La, Cr, and Mn, and in terms of atomic percentage, 2<Cu<5at%, 1<Si<3at%, 2<X<10at%, and the remainder is Al and inevitable trace impurity elements. The crystal structure is a mixture of at least a quinary alloy, a quaternary alloy, and a ternary multi-element alloy with AlSiCu as the matrix.

2. The high-purity high-entropy aluminum alloy sputtering coating material according to claim 1, characterized in that: The total contents of C and N in the alloy material are both less than 50 ppm, the oxygen content is less than 500 ppm, the average grain size is ≤50 μm, and the purity is greater than 99.99%.

3. A high-purity high-entropy aluminum alloy sputtering coating material according to claim 1 or 2, characterized in that: The Cu forms a limited solid solution in the crystal, and Cu atoms squeeze into the Al to cause lattice distortion.

4. The high-purity high-entropy aluminum alloy sputtering coating material according to claim 3, characterized in that: The Ni forms conductive nickel precipitates at the crystal interface.

5. The high-purity high-entropy aluminum alloy sputtering coating material according to claim 3, characterized in that: The La is present in the crystal as Al 11 La3 precipitation phase exists.

6. The high-purity high-entropy aluminum alloy sputtering coating material according to claim 3, characterized in that: The Cr forms an intermetallic compound in Al.

7. The high-purity high-entropy aluminum alloy sputtering coating material according to claim 3, characterized in that: The Mn dissolves in Al and forms a dispersed intermetallic compound MnAl6.

8. The high-purity high-entropy aluminum alloy sputtering coating material according to claim 3, characterized in that: The X element is composed of Ni and La, and the alloy material is Al in atomic percentage. 86 Cu4Si2Ni6La2at%.

9. The high-purity high-entropy aluminum alloy sputtering coating material according to claim 3, characterized in that: The alloy material is A1 in atomic percentage of elements 85 Cu4Si2Ni6Cr3 at%, A1 87 Cu4Si2Mn5La2at%,A1 89 Cu3si2Cr4La2at% or A1 88 Cu3si2Cr5Mn2 at%.

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