Alumina target as well as preparation method and application thereof

Abstract

The invention discloses an aluminum oxide target material as well as a preparation method and application thereof. The aluminum oxide target material comprises the following raw materials: aluminum oxide and nano aluminum hydroxide, and the mass percent of the nano aluminum hydroxide is 0.5%-20% based on the total mass of the aluminum oxide and the nano aluminum hydroxide. On the premise that impurities are not introduced, the aluminum oxide target material has high density and lower sintering temperature.

Description

Technical Field

[0001] The invention relates to the technical field of sputtering target materials, and in particular to an aluminum oxide target material and a preparation method and application thereof. Background Art

[0002] Alumina films have excellent insulation properties and high light transmittance, and are often used as anti-reflection films, interference films, protective films, and passivation films in optical devices, automobiles, solar cells, and other fields. Magnetron sputtering coating has the advantages of high efficiency and good film uniformity, and is suitable for large-scale coating in industrial production, but it has high requirements for the density of the target material. The melting point of aluminum oxide exceeds 2000°C, and it is difficult to obtain high-purity and high-density aluminum oxide 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 solve at least 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, which can effectively improve the density and reduce the sintering temperature.

[0005] The second aspect of the present invention also provides a method for preparing an aluminum oxide target.

[0006] The third aspect of the present invention also provides an application of an aluminum oxide target.

[0007] According to a first aspect of the present invention, an aluminum oxide target material is provided, comprising the following raw materials: aluminum oxide 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 aluminum oxide and the nano-aluminum hydroxide.

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

[0009] The present invention adds 0.5% to 20% by mass of nano aluminum hydroxide into alumina. On the one hand, the nano aluminum hydroxide can be filled between the alumina particles. On the other hand, the nano aluminum hydroxide decomposes at a relatively low temperature to generate highly active nano aluminum oxide, which promotes the migration of the alumina grain boundaries during the sintering process. Without introducing impurities, the sintering temperature of the alumina target is effectively reduced, while the density is improved.

[0010] Furthermore, when the nano aluminum hydroxide is lower than 0.5%, the effect is not obvious; when the nano aluminum hydroxide is higher than 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%, thereby achieving better density.

[0012] According to some embodiments of the present invention, the mass percentage of the nano aluminum hydroxide is 5% to 15%. Therefore, under the premise of higher density, the sintering temperature is also maintained at a lower level.

[0013] According to some embodiments of the present invention, the D 90 Particle size ≤ 20nm. Therefore, nano aluminum hydroxide has a higher specific surface area, stronger sintering activity, and can be filled between alumina particles to improve density.

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

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

[0016] According to a second aspect of the present invention, an embodiment provides a method for preparing the above-mentioned aluminum oxide target, comprising the following steps:

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

[0018] S2, pressing and cold isostatic pressing the powder to obtain a green blank;

[0019] S3, degreasing and sintering the green blank to obtain an alumina target; the highest sintering temperature in the sintering process is 1350-1550°C.

[0020] The method for preparing an aluminum oxide target according to an embodiment of the present invention has at least the following beneficial effects:

[0021] The preparation method of the present invention achieves high density at a relatively low sintering temperature and without introducing impurities; thus, a high-purity and high-density aluminum oxide target material is prepared.

[0022] Furthermore, the alumina target prepared by the present invention has a larger size and is suitable for industrial large-scale production.

[0023] According to some embodiments of the present invention, the sintering step in step S3 is: first heating to 500°C-700°C, keeping warm for 2-8 hours; then heating to 800°C-950°C, keeping warm for 3-8 hours; then heating to 1350°C-1550°C; keeping warm for 6-17 hours.

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

[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 150 MPa to 220 MPa.

[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 60 MPa to 180 MPa.

[0029] According to some embodiments of the invention, the dispersant comprises polyvinyl pyrrolidone.

[0030] According to some embodiments of the present invention, the adhesive includes at least one of polyvinyl alcohol (PVA), polyvinyl butyral (PVB) or polyvinyl pyrrolidone (PVP), thereby having an excellent bonding effect.

[0031] According to some embodiments of the present invention, the plasticizer includes at least one of polyethylene glycol, gum arabic or 1,3-propylene glycol. Thus, the plasticity is enhanced.

[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 a use of the aluminum oxide target material described in the first aspect of the present invention in magnetron sputtering coating.

[0034] Therefore, the aluminum oxide target material of the present invention can be used for preparing high-quality aluminum oxide films by magnetron sputtering.

[0035] Other features and advantages of the present invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the present invention. DETAILED DESCRIPTION

[0036] The following are specific embodiments of the present invention, and the technical solutions of the present invention are 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 the present invention are conventional reagents, methods and equipment in the art.

[0038] The raw materials in the present invention are as follows:

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

[0040] Alumina: α-alumina powder; D of alumina 90 Particle size is 1.0μm~10.0μm; purity is 4N and above; commercially available.

[0041] Nano-alumina: Nano-alumina has a D90 particle size of ≤20nm; purity of 4N and above; commercially available.

[0042] Example 1

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

[0044] S1. Aluminum hydroxide and α-aluminum oxide were mixed according to the ratio in Table 1, and then deionized water and a dispersant of 0.8 wt% polyvinyl pyrrolidone (PVP) were added, and a qualified slurry was obtained by ball milling with a sand mill. The ball milling time was 13 h, and the median particle size D of the slurry was 90 ≤0.50μm; 0.6wt% binder PVA and 0.3wt% plasticizer PEG were added to the obtained slurry, and then stirred at a low speed for 1-3h, and then spray granulated to obtain spherical powder with good fluidity;

[0045] S2. The granulated powder is injected into a planar target mold of 0.3-1.0m x 0.5-1.6m, with a molding pressure of 150MPa. After demolding, it is packaged and placed in the chamber of a cold isostatic press, maintained at 200MPa for 30min, and demolded after cold isostatic pressing to obtain a planar target blank.

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

[0047] Embodiments 2 to 5

[0048] Examples 2 to 5 provide a series of aluminum oxide targets, the preparation methods of which are the same as those of Example 1, and the amounts of raw materials used are shown in Table 1.

[0049] Table 1 Examples 1 to 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 aluminum oxide target material, and the preparation method is the same as that of Example 3, except that the mold size of the target material is 0.5*1.5.

[0053] Example 7

[0054] This example provides an aluminum oxide target material, and the preparation method is the same as that of 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 aluminum oxide target material, and the preparation method is the same as that of Example 1, except that the content of aluminum oxide is 100 wt.%.

[0057] Comparative Example 2

[0058] Comparative Example 2 provides an aluminum oxide target material, and the preparation method is the same as that of Example 1, except that the content of nano aluminum hydroxide is 0.3 wt.%.

[0059] Comparative Example 3

[0060] Comparative Example 3 provides an aluminum oxide target material, and the preparation method is the same as that of Example 1, except that the content of nano aluminum hydroxide is 22 wt.%.

[0061] Comparative Example 4

[0062] Comparative Example 4 provides an aluminum oxide target material, and the preparation method is the same as that of Example 3, except that nano aluminum oxide is used instead of nano aluminum hydroxide.

[0063] Performance Testing

[0064] The density of the alumina target prepared in the embodiment of the present invention and the comparative example was tested: the density of the target was measured by the Archimedes drainage method; the results are shown in Table 2.

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

[0066]

[0067]

[0068] From the data in Table 2, it can be seen that the high-purity alumina target materials prepared in Examples 1 to 7 of the present invention have a maximum sintering temperature of 1380°C to 1550°C and a density of 96.3% to 99.8%. As the content of nano-aluminum hydroxide increases, the sintering temperature of the target material gradually decreases and the density first increases and then decreases, indicating that the present invention uses nano-aluminum hydroxide as a raw material to obtain a high-density high-purity alumina target material without introducing impurities, and is suitable for alumina flat targets of different sizes, with a maximum size of up to 1.0m*1.6m.

[0069] Comparative Example 1 uses only high-purity alumina as raw material, and the density after sintering at 1550°C is only 93.8%, which is significantly lower than that of Examples 1 to 7. This is because nano-aluminum hydroxide decomposes into nano-amorphous alumina during the sintering process, and it is better distributed between large-particle alumina grains, has higher activity at lower temperatures, promotes the migration of grain boundaries, 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 sintering effect is not as expected, and the decomposition of aluminum hydroxide will produce gaseous water, and the discharge process will have a certain impact on the density. Too high a content will reduce the density of the target material.

[0071] The difference between Comparative Example 4 and Example 3 is that nano-aluminum oxide is used instead of nano-aluminum hydroxide, but its density is significantly lower than that of Comparative Example 3. This is because nano-aluminum hydroxide will first generate amorphous, γ and other crystalline aluminum oxides after being decomposed at elevated temperature, further improving the activity of the powder, and promoting mass transfer and grain boundary migration at a lower temperature, thereby achieving a better sintering effect.

[0072] The above is a detailed description of the embodiments of the present invention, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge scope of ordinary technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. An alumina target, characterized in that: The invention comprises the following raw materials: aluminum oxide 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 aluminum oxide and the nano aluminum hydroxide.

2. The alumina target according to claim 1, characterized in that The mass percentage of the nano aluminum hydroxide is 1% to 15%.

3. The alumina target according to claim 1 or 2, characterized in that: The D of the nano aluminum hydroxide 90 Particle size ≤20nm.

4. The alumina target according to claim 1 or 2, characterized in that: The aluminum oxide is selected from at least one of α-Al2O3, β-Al2O3 or γ-Al2O3.

5. The alumina target according to claim 1 or 2, characterized in that: The D of the aluminum oxide 90 The particle size ranges from 1.0 μm to 10.0 μm.

6. The method for preparing an aluminum oxide target according to any one of claims 1 to 5, characterized in that: The steps include: S1. Alumina, nano aluminum hydroxide and a dispersant are mixed and ball-milled to obtain a slurry; the slurry, a binder and a plasticizer are mixed to obtain a powder; S2, pressing and cold isostatic pressing the powder to obtain a green blank; S3, degreasing and sintering the green blank to obtain an alumina target; The highest sintering temperature in the sintering process is 1350-1550°C.

7. The method for preparing an aluminum oxide target according to claim 6, characterized in that: The sintering steps in step S3 are: first heating to 500°C-700°C, keeping warm for 2-8 hours; then heating to 800°C-950°C, keeping warm for 3-8 hours; then heating to 1350°C-1550°C, keeping warm for 6-17 hours.

8. The method for preparing an aluminum oxide target according to claim 6, characterized in that: In step S2, the pressure of the cold isostatic pressing is 150 MPa to 220 MPa.

9. The method for preparing an aluminum oxide target according to claim 8, characterized in that: During the sintering process in step S3, oxygen is introduced during the last heating; Preferably, the oxygen introduction rate is 20 to 50 L / min.

10. Use of the aluminum oxide target material according to any one of claims 1 to 5 in magnetron sputtering coating.

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