Aluminum oxide target, method for producing the same, and use thereof

Abstract

The application discloses an aluminum oxide target material and a preparation method and application thereof. The aluminum oxide target material comprises the following raw materials: aluminum oxide and nano aluminum hydroxide. The mass percentage of the nano aluminum hydroxide is 0.5-20% in the total mass of the aluminum oxide and the nano aluminum hydroxide. The aluminum oxide target material has high compactness and lower sintering temperature without introducing impurities.

Description

Technical Field

[0001] This invention relates to the field of sputtering target technology, and in particular to an alumina target, its preparation method, and its application. Background Technology

[0002] Alumina thin films possess excellent insulation properties and high light transmittance, and are commonly used as antireflective coatings, interference films, protective films, and passivation films in optical devices, automobiles, solar cells, and other fields. Magnetron sputtering coating offers advantages such as high efficiency and good film uniformity, making it suitable for large-scale coating in industrial production; however, it requires high density of the target material. Alumina has a melting point exceeding 2000℃, making it difficult to obtain high-purity and highly dense alumina targets using conventional preparation processes.

[0003] Therefore, it is necessary to develop a new type of alumina target. Summary of the Invention

[0004] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, the first aspect of the present invention provides an alumina target material that can effectively improve density and reduce sintering temperature.

[0005] A second aspect of the present invention also provides a method for preparing an alumina target.

[0006] A third aspect of the present invention also provides an application of an alumina target.

[0007] An alumina target material provided according to a first aspect of the present invention comprises the following raw materials: alumina and nano-aluminum hydroxide, wherein the mass percentage of the nano-aluminum hydroxide is 0.5% to 20% based on the total mass of the alumina and nano-aluminum hydroxide.

[0008] The alumina target material according to embodiments of the present invention has at least the following beneficial effects:

[0009] This invention incorporates 0.5% to 20% by mass of nano-aluminum hydroxide into alumina. On the one hand, nano-aluminum hydroxide can fill the spaces between alumina particles. On the other hand, nano-aluminum hydroxide decomposes at a lower temperature to generate highly active nano-alumina, which promotes the migration of alumina grain boundaries during sintering. Without introducing impurities, this effectively reduces the sintering temperature of the alumina target material and increases its density.

[0010] Furthermore, when the content of nano-aluminum hydroxide is below 0.5%, the effect is not obvious; when the content of nano-aluminum hydroxide is above 20%, the density of the target material will decrease.

[0011] According to some embodiments of the present invention, the mass percentage of the nano-aluminum hydroxide is 1% to 15%. This allows for better density.

[0012] According to some embodiments of the present invention, the mass percentage of the nano-aluminum hydroxide is 5% to 15%. Thus, while achieving higher density, the sintering temperature is also kept at a lower level.

[0013] According to some embodiments of the present invention, the D of the nano-aluminum hydroxide 90 Particle size ≤20nm. As a result, nano-aluminum hydroxide has a higher specific surface area, stronger sintering activity, and can fill the spaces between alumina particles, thus improving density.

[0014] According to some embodiments of the present invention, the alumina is selected from at least one of α-Al₂O₃, β-Al₂O₃, or γ-Al₂O₃. Furthermore, when the alumina is selected from α-Al₂O₃, it exhibits good grain stability.

[0015] According to some embodiments of the present invention, the D of the alumina 90 The particle size ranges from 1.0 μm to 10.0 μm. As a result, the prepared alumina target material has a uniform size distribution.

[0016] According to a second aspect of the present invention, a method for preparing the alumina target material described above is provided, comprising the following steps:

[0017] S1. Alumina, nano-aluminum hydroxide, and dispersant are mixed and ball-milled to obtain a slurry; the slurry, binder, and plasticizer are mixed to obtain a powder.

[0018] S2. The powder is pressed and cold isostatically pressed to obtain a green body.

[0019] S3. The green blank is degreased and sintered to obtain the alumina target material; the sintering temperature during the sintering process is up to 1350-1550℃.

[0020] The method for preparing alumina targets according to embodiments of the present invention has at least the following beneficial effects:

[0021] The preparation method of the present invention achieves high density at a low sintering temperature without introducing impurities, and a high-purity and high-density alumina target material is obtained.

[0022] Furthermore, the alumina target material prepared by this invention has a larger size, making it suitable for large-scale industrial production.

[0023] According to some embodiments of the present invention, the sintering step in step S3 is as follows: first, the temperature is raised to 500℃~700℃ and held for 2~8h; then the temperature is raised to 800℃~950℃ and held for 3~8h; then the temperature is raised to 1350℃~1550℃ and held for 6~17h.

[0024] According to some embodiments of the present invention, oxygen is introduced during the final heating process in step S3 of the sintering process.

[0025] According to some embodiments of the present invention, the oxygen introduction rate is 20 to 50 L / min.

[0026] According to some embodiments of the present invention, in step S2, the pressure of the cold isostatic pressing is 150MPa to 220MPa.

[0027] According to some embodiments of the present invention, in step S2, the cold isostatic pressing time is 10 min to 50 min.

[0028] According to some embodiments of the present invention, in step S2, the pressing pressure is 60MPa to 180MPa.

[0029] According to some embodiments of the present invention, the dispersant comprises polyvinylpyrrolidone.

[0030] According to some embodiments of the present invention, the adhesive comprises at least one of polyvinyl alcohol (PVA), polyvinyl butyral (PVB), or polyvinylpyrrolidone (PVP). This results in excellent bonding performance.

[0031] According to some embodiments of the present invention, the plasticizer comprises at least one selected from polyethylene glycol, gum arabic, or 1,3-propanediol. This enhances plasticity.

[0032] According to some embodiments of the present invention, in step S1, the ball milling time is 8 to 16 hours.

[0033] The third aspect of the present invention provides an application of the alumina target material described in the first aspect of the present invention in magnetron sputtering coating.

[0034] Therefore, the alumina target of the present invention can be used to prepare high-quality alumina films by magnetron sputtering.

[0035] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Detailed Implementation

[0036] The following are specific embodiments of the present invention, and the technical solutions of the present invention will be further described in conjunction with the embodiments, but the present invention is not limited to these embodiments.

[0037] Unless otherwise specified, the reagents, methods and equipment used in this invention are all conventional reagents, methods and equipment in this technical field.

[0038] The raw materials used in this invention are as follows:

[0039] Nano aluminum hydroxide: D of nano aluminum hydroxide 90 Particle size ≤20nm; purity 4N and above; commercially available.

[0040] Alumina: α-alumina powder; D of alumina 90 Particle size ranges from 1.0 μm to 10.0 μm; purity is 4N or higher; commercially available.

[0041] Nano alumina: The D90 particle size of nano alumina is ≤20nm; the purity is 4N and above; commercially available.

[0042] Example 1

[0043] This example provides an alumina target material, the raw material dosage of which is shown in Table 1, and its preparation method is as follows:

[0044] S1. Mix aluminum hydroxide and α-alumina according to the proportions in Table 1, then add deionized water and 0.8 wt% polyvinylpyrrolidone (PVP) dispersant. Ball mill the mixture using a sand mill to obtain a qualified slurry. The ball milling time is 13 hours, and the median particle size D of the slurry is... 90 ≤0.50μm; 0.6wt% binder PVA and 0.3wt% plasticizer PEG were added to the obtained slurry, and then stirred at low speed for 1-3h. Subsequently, spray granulation was carried out to obtain spherical powder with good flowability.

[0045] S2. Inject the granulated powder into a flat target mold of 0.3-1.0m x 0.5-1.6m, with a molding pressure of 150MPa. After demolding, seal and place in the chamber of a cold isostatic press, maintain at 200MPa for 30min, and demold after cold isostatic pressing to obtain the flat target blank.

[0046] S3. After degreasing the target blank obtained in step S2, it is sintered at high temperature in an oxygen atmosphere, with a maximum sintering temperature of 1380℃-1550℃. The first stage sintering temperature is 600℃, the heating rate is 0.3℃ / min, and the holding time is 5h; the second stage sintering temperature is 900℃, the heating rate is 1℃ / min, and the holding time is 3h; the third stage sintering temperature is 1550℃, the heating rate is 1℃ / min, oxygen is introduced, the holding time is 12h, and the oxygen introduction rate is 35L / min.

[0047] Examples 2-5

[0048] Examples 2-5 provide a series of alumina targets, which are prepared in the same way as in Example 1, and the amount of raw materials used is shown in Table 1.

[0049] Table 1 Examples 1-5 (wt.%)

[0050] Example 1 Example 2 Example 3 Example 4 Example 5 Alumina 99 95 90 85 80 Nano aluminum hydroxide 1 5 10 15 20

[0051] Example 6

[0052] This example provides an alumina target material, which is prepared in the same way as in Example 3, except that the mold size of the target material is 0.5*1.5.

[0053] Example 7

[0054] This example provides an alumina target material, which is prepared in the same way as in Example 3, except that the mold size of the target material is 1.0*1.6.

[0055] Comparative Example 1

[0056] Comparative Example 1 provides an alumina target material prepared in the same way as in Example 1, except that the alumina content is 100 wt.%.

[0057] Comparative Example 2

[0058] Comparative Example 2 provides an alumina target material prepared in the same way as in Example 1, except that the content of nano-aluminum hydroxide is 0.3 wt.%.

[0059] Comparative Example 3

[0060] Comparative Example 3 provides an alumina target material prepared in the same way as in Example 1, except that the content of nano-aluminum hydroxide is 22 wt.%.

[0061] Comparative Example 4

[0062] Comparative Example 4 provides an alumina target material, which is prepared in the same way as in Example 3, except that nano-alumina is used instead of nano-alumina hydroxide.

[0063] Performance testing

[0064] The alumina targets prepared in the embodiments and comparative examples of the present invention were subjected to density tests: the density of the targets was measured by Archimedes' displacement method; the results are shown in Table 2.

[0065] Table 2 Examples 1-7 and Comparative Examples 1-4

[0066]

[0067]

[0068] As shown in Table 2, the high-purity alumina targets prepared in Examples 1-7 of this invention have a maximum sintering temperature of 1380℃ to 1550℃ and a density of 96.3% to 99.8%. With the increase of nano-aluminum hydroxide content, the sintering temperature of the target gradually decreases and the density first increases and then decreases. This indicates that this invention uses nano-aluminum hydroxide as raw material to obtain high-density high-purity alumina targets without introducing impurities, and is suitable for alumina planar targets of different sizes, with the maximum size reaching 1.0m*1.6m.

[0069] Comparative Example 1 uses only high-purity alumina as raw material. After firing at 1550℃, the density is only 93.8%, which is significantly lower than that of Examples 1 to 7. This is because nano-alumina hydroxide decomposes into nano-amorphous alumina during the sintering process, and it is well distributed between large alumina grains. It has high activity at a lower temperature, promotes grain boundary migration, and thus achieves a better sintering aid effect.

[0070] The raw materials of Comparative Examples 2 and 3 are the same as those of Examples 1-7, but their density is lower than that of Examples 1-7. This is because the aluminum hydroxide content is too low, the calcination effect is not as expected, and the decomposition of aluminum hydroxide will produce gaseous water, which will have a certain impact on the density during the discharge process. If the content is too high, the density of the target material will decrease.

[0071] The difference between Comparative Example 4 and Example 3 is that nano-alumina is used instead of nano-alumina hydroxide, but its density is significantly lower than that of Comparative Example 3. This is because after nano-alumina hydroxide decomposes at elevated temperature, it will first generate amorphous, γ-crystalline alumina, which further improves the activity of the powder. It can promote mass transfer and grain boundary migration at lower temperatures, thus achieving a better sintering effect.

[0072] The present invention has been described in detail above with reference to the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for preparing an alumina target, characterized in that, Includes the following steps: S1. Alumina, nano-aluminum hydroxide, and dispersant are mixed and ball-milled to obtain a slurry; the slurry, binder, and plasticizer are mixed to obtain a powder. S2. The powder is pressed and cold isostatically pressed to obtain a green body. S3. Degreasing and sintering the green blank yields the alumina target material. The maximum sintering temperature during the sintering process is 1350~1550℃; The sintering step in step S3 is as follows: first, heat to 500 ℃~700 ℃ and hold for 2~8 hours; then heat to 800 ℃~950 ℃ and hold for 3~8 hours; then heat to 1350 ℃~1550 ℃ and hold for 6~17 hours. The total mass percentage of the nano-aluminum hydroxide is 5% to 15% based on the total mass of alumina and nano-aluminum hydroxide; the D90 particle size of the nano-aluminum hydroxide is ≤20nm.

2. The method for preparing the alumina target material according to claim 1, characterized in that, The alumina is selected from at least one of α-Al2O3, β-Al2O3, or γ-Al2O3.

3. The method for preparing the alumina target material according to claim 1, characterized in that, The D90 particle size of the alumina ranges from 1.0 μm to 10.0 μm.

4. The method for preparing the alumina target material according to claim 1, characterized in that, In step S2, the pressure of the cold isostatic pressing is 150MPa~220MPa.

5. The method for preparing the alumina target material according to claim 1, characterized in that, During the sintering process in step S3, oxygen is introduced during the final heating.

6. The method for preparing the alumina target material according to claim 5, characterized in that, The oxygen flow rate is 20-50 L / min.

7. The application of the alumina target prepared by the preparation method according to any one of claims 1 to 6 in magnetron sputtering coating.

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