Oxide target and method of making the same

Abstract

This invention belongs to the field of target material technology and discloses an oxide target material, wherein the content of zinc oxide is 25-30 wt%, the content of titanium oxide is 25-30 wt%, the content of aluminum oxide is 5-12.5 wt%, and the balance is indium tin oxide. Zinc oxide, titanium oxide, and aluminum oxide powders are added to pure water and dispersed to obtain slurry I; slurry I is emulsified and then ball-milled to obtain slurry II; indium tin oxide powder is added to water and dispersed to obtain slurry III; slurry III is emulsified, then mixed with slurry II and a binder, and ball-milled to obtain ball-milled material; the ball-milled material is spray-dried and then granulated to obtain pellets; the pellets are shaped and sintered to obtain the oxide target material. The ITO target material provided by this invention has low resistivity, and the preparation method is simple and low-cost.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of target materials, and particularly relates to an oxide target material and a preparation method thereof. BACKGROUND

[0002] The ITO target material, namely, an indium tin oxide target material, is a black-gray ceramic semiconductor material formed by mixing indium oxide and tin oxide powder in a certain proportion, processing and molding through a series of production processes, and high-temperature sintering. As an n-type semiconductor material, the indium tin oxide has high conductivity, excellent visible light transmittance, strong mechanical hardness, and good chemical stability, and is mainly used for manufacturing liquid crystal displays, flat panel displays, plasma displays, touch screens, electronic paper, organic light-emitting diodes, solar cells, anti-static plating films, transparent conductive plating for EMI shielding, and various optical plating films. In order to further improve the conductivity of the ITO target material, ion-doped ITO target materials are a common method. Selecting appropriate ions for doping can effectively reduce the resistivity. For example, the patent document with the publication number CN103345977A discloses a preparation method of silver-doped ITO thin films; the patent document with the publication number CN114032517A discloses a preparation method of rare earth ion-doped ITO target materials; the patent document with the publication number CN115353369A discloses a microwave method for preparing nickel-aluminum-doped ITO target materials; and the patent document with the publication number CN114591070A discloses a preparation method of high-purity Mo-doped ITO target materials.

[0003] The oxide target material is also a research hotspot. The density, grain size, composition, and uniformity of the oxide target material affect various electrical and optical properties of the sputtered film, which has attracted great attention from a large number of researchers and industry professionals. Reducing the resistivity of the oxide target material is one of the current research focuses. The patent document with the publication number CN115974530A discloses a low-resistivity high-mobility oxide target material composed of praseodymium oxide, indium oxide, gallium oxide, and zinc oxide. Due to the use of more rare and precious metal oxides, the cost is relatively high. SUMMARY

[0004] The purpose of the present application is to provide an oxide target material and a preparation method thereof, achieving low resistivity and low cost of the oxide target material.

[0005] To achieve the above purpose, the present application provides the following specific technical solutions.

[0006] Firstly, the present application provides an oxide target material, wherein the content of zinc oxide is 25-30wt%, the content of titanium oxide is 25-30wt%, the content of aluminum oxide is 5-12.5wt%, and the balance is indium tin oxide.

[0007] In a further preferred embodiment, the outer diameter of the oxide target is 180-210 mm.

[0008] In a further preferred embodiment, the resistivity of the oxide target is 2.7×10 -5 ~3.2×10 -5 Ω·m.

[0009] Secondly, the present application provides a preparation method of the oxide target, comprising the following steps:

[0010] adding zinc oxide, titanium oxide and aluminum oxide powders into pure water, dispersing to obtain slurry I;

[0011] emulsifying the slurry I, and then ball milling to obtain slurry II;

[0012] adding indium tin oxide powder into water, dispersing to obtain slurry III;

[0013] emulsifying the slurry III, and then mixing with the slurry II and a binder, and ball milling to obtain a ball milling material;

[0014] spray drying the ball milling material, and then granulating to obtain a ball;

[0015] sintering the ball after shaping.

[0016] In a further preferred embodiment, the solid content of the slurry I is 25-50 wt%.

[0017] In a further preferred embodiment, the particle size D50 of the slurry II is 0.3-1 μm.

[0018] In a further preferred embodiment, the solid content of the slurry III is 25-50 wt%.

[0019] In a further preferred embodiment, the particle size D50 of the ball milling material is 0.3-1 μm.

[0020] In a further preferred embodiment, the solid content of the ball milling material is 35-75 wt%.

[0021] In a further preferred embodiment, the binder is PVB (polyvinyl pyrrolidone) and / or PVA (polyethylene glycol).

[0022] Further, the amount of the binder added is 1.5-5% of the total mass of the slurry II and the slurry III.

[0023] In a further preferred embodiment, the spray drying method is centrifugal spray drying, the rotation speed of the spray head is 7000-15000 rpm, the inlet air temperature is 150-250℃, and the outlet air temperature is 50-100℃.

[0024] In a further preferred embodiment, the molding method is cold isostatic pressing.

[0025] In a further preferred embodiment, the sintering is atmospheric pressure sintering, and the sintering temperature is 1200~1450℃.

[0026] Furthermore, the sintering time is 7~20h.

[0027] The advantages of the present invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned from specific embodiments thereof. Attached Figure Description

[0028] Figure 1 The image shows the SEM image of the pellets obtained in Example 1.

[0029] Figure 2 This is a photograph of the cylindrical target material obtained in Example 1. Detailed Implementation

[0030] The present invention first provides an oxide target material, wherein the content of zinc oxide is 25~30wt%, the content of titanium oxide is 25~30wt%, the content of aluminum oxide is 5~12.5wt%, and the balance is indium tin oxide.

[0031] Oxides of zinc, titanium, and aluminum are all excellent n-type doped semiconductor materials. ZnO has outstanding advantages such as low price, non-toxicity, and ease of preparation, so ZnO doped systems are considered the best alternative to ITO thin films. Ti 4+ The radius (0.064nm), A1 3+ The radius (0.054 nm) is smaller than In 3+ The radius (0.08nm) easily occupies In 3+ It can become a substitutional ion at its position, or it can easily exist as an interstitial ion, and its ionic valence is greater than that of In. 3+ When Ti 4+ A1 3+ Replace In in the crystal lattice 3+ At this time, more free electrons can be supplied, increasing the carrier concentration of the thin film, effectively reducing resistivity, and thus improving the conductivity of the thin film.

[0032] The inventors discovered that only by simultaneously adding titanium oxide, zinc oxide, and aluminum oxide to the ITO target can the resistivity of the target be effectively reduced. Furthermore, the addition of oxides of Zn, Ti, and Al can reduce the amount of indium used in the target, saving production costs.

[0033] In some preferred embodiments of the present invention, the outer diameter of the oxide target is 180-210 mm. Traditional ITO targets typically have an outer diameter of 150-160 mm, which is relatively small, resulting in a target utilization rate of only about 60-75%. The present invention provides a large-sized target, achieving a utilization rate of over 85%.

[0034] In some preferred embodiments of the present invention, the resistivity of the oxide target is 2.7 × 10⁻⁶. -5 ~3.2×10 5 Ω·m.

[0035] Secondly, the present invention provides a method for preparing the above-mentioned oxide target material, comprising the following steps:

[0036] Zinc oxide, titanium oxide, and aluminum oxide powders were added to pure water and dispersed to obtain slurry I;

[0037] Slurry I was emulsified and then ball-milled to obtain slurry II;

[0038] Indium tin oxide powder was added to water and dispersed to obtain slurry III;

[0039] Emulsified slurry III is then mixed with slurry II and binder, and ball-milled to obtain ball-milled material;

[0040] Spray-dry the ball milling material, then granulate it to obtain pellets;

[0041] After being shaped, the pellets are sintered.

[0042] The dispersion described in the above preparation method can be achieved by using a dispersant, by stirring, or by a combination of both.

[0043] In some preferred embodiments of the present invention, the solid content of slurry I is 25~50wt%.

[0044] In some preferred embodiments of the present invention, the particle size D50 of the slurry II is 0.3~1μm.

[0045] In some preferred embodiments of the present invention, the solid content of the slurry III is 25-50 wt%.

[0046] In some preferred embodiments of the present invention, the particle size D50 of the ball milling material is 0.3~1μm. Within this particle size range, the raw materials are mixed very uniformly; simultaneously, during sintering, the small particle size allows the sintering reaction to be completed more quickly.

[0047] In some preferred embodiments of the present invention, the solid content of the ball milling material is 35~75wt%.

[0048] The binder can be any commonly used binder in the art. In some preferred embodiments of the present invention, the binder is PVB (polyvinylpyrrolidone) and / or PVA (polyethylene glycol). Further, the amount of binder added is 1.5-5% of the total mass of slurry II and slurry III. Adding a larger amount of binder during ball milling is beneficial for preparing large-sized targets and enhances the strength of the targets, making them less prone to cracking.

[0049] In some preferred embodiments of the present invention, the spray drying method is centrifugal spray drying. Spray drying is instantaneous drying, and further employing centrifugal spray drying results in more rounded granules, fewer broken particles, and more uniform filler during molding. Through further optimization, the nozzle rotation speed is controlled at 7000~15000 rpm, the inlet air temperature at 150~250℃, and the outlet air temperature at 50~100℃.

[0050] In some preferred embodiments of the present invention, the molding method is cold isostatic pressing.

[0051] In some preferred embodiments of the present invention, the sintering is atmospheric pressure sintering, and the sintering temperature is 1200~1450℃. Zinc oxide and titanium oxide are more likely to become liquid phases at high temperatures, which lowers the sintering temperature of ITO. Furthermore, if the sintering temperature is too low, there will be many gaps between the particles during sintering, which will affect the density; if the temperature is too high, the grain size will easily grow, making the target more prone to cracking. The sintering time can be adjusted adaptively; in a specific embodiment of the present invention, the sintering time is 7~20 hours.

[0052] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0053] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0054] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0055] Example 1

[0056] 25 parts by weight of zinc oxide, 30 parts by weight of titanium oxide and 5 parts by weight of aluminum oxide were added to 150 parts by weight of water and dispersed at 500 rpm for 0.5 h to obtain slurry I.

[0057] The well-dispersed slurry I was stirred and emulsified at a stirring speed of 500 rpm, and then added to a ball mill and ball-milled for 0.5 h to obtain slurry II with a particle size D50 of 0.5 μm.

[0058] 40 parts by mass of indium tin oxide were added to 100 parts by mass of pure water and dispersed at 700 rpm for 1 hour to obtain slurry III.

[0059] Slurry III was stirred and emulsified at a stirring speed of 500 rpm, and then put into a ball mill together with slurry II for ball milling. During the ball milling process, 7 parts by weight of PVA and 3 parts by weight of PVB were added. The ball milling speed was 700 rpm and the ball milling time was 3 hours to obtain ball milling material with a particle size of 0.3 μm.

[0060] The ball-milled slurry was spray-granulated at an inlet air temperature of 150℃, an outlet air temperature of 50℃, and a spray speed of 7000 rpm. The material was then mixed for 10 minutes at 5 rpm / min using a mixer.

[0061] Using a rigid mold, the powder is pressed into a cylindrical target blank with a size of 180 mm at 200 MPa.

[0062] The pressed target blank was sintered at a temperature of 1200℃ for 20 hours. After sintering, the doped ITO target material was obtained.

[0063] Figure 1 The image shows a SEM image of the powder after spray granulation. As can be seen from the image, spherical particles with a hollow structure are obtained after spray granulation.

[0064] Figure 2 The cylindrical target material obtained by sintering shows that the target material has a high density.

[0065] Comparative Example 1

[0066] The only difference between Comparative Example 1 and Example 1 is that slurry I does not contain titanium oxide and aluminum oxide.

[0067] Comparative Example 2

[0068] The only difference between Comparative Example 2 and Example 1 is that slurry I does not contain zinc oxide.

[0069] Comparative Example 3

[0070] The only difference between Comparative Example 3 and Example 1 is that slurry I does not contain titanium oxide.

[0071] Comparative Example 4

[0072] The only difference between Comparative Example 4 and Example 1 is that slurry I does not contain alumina.

[0073] Comparative Example 5

[0074] The only difference between Comparative Example 5 and Example 1 is that the amounts of zinc oxide, titanium oxide, and aluminum oxide added are different, at 35 parts by weight, 35 parts by weight, and 15 parts by weight, respectively.

[0075] Comparative Example 6

[0076] The only difference between Comparative Example 6 and Example 1 is that the amounts of zinc oxide, titanium oxide, and aluminum oxide added are different, at 20 parts by mass, 20 parts by mass, and 4 parts by mass, respectively.

[0077] Example 2

[0078] 30 parts by weight of zinc oxide, 25 parts by weight of titanium oxide and 12.5 parts by weight of aluminum oxide were added to 67.5 parts by weight of water and dispersed at 500 rpm for 0.5 h to obtain slurry I.

[0079] The dispersed slurry I was stirred and emulsified at a stirring speed of 1000 rpm, and then added to a ball mill and ball-milled for 2.5 h to obtain slurry II with a particle size of 0.3 μm.

[0080] 32.5 parts by weight of indium tin oxide were added to 32.5 parts by weight of pure water and dispersed at 1200 rpm for 1 hour to obtain slurry III.

[0081] Slurry III was stirred and emulsified at a stirring speed of 1000 rpm, and then put into a ball mill together with slurry II for ball milling. During the ball milling process, 3 parts by weight of PVA were added, the solid content of the slurry was controlled at 50 wt%, the ball milling speed was 700 rpm, and the ball milling time was 3 h, to obtain ball milling material with a particle size D50 of 0.5 μm.

[0082] The ball-milled slurry was spray-granulated at an inlet air temperature of 200℃, an outlet air temperature of 70℃, and a spray speed of 10000rpm. The powder was then mixed with a mixer at 13rpm / min for 50min.

[0083] Using a rigid mold, the powder is pressed into a cylindrical target blank with a size of 195 mm at 300 MPa.

[0084] The pressed target blank was sintered at a temperature of 1350℃ for 12 hours. After sintering, the doped ITO target material was obtained.

[0085] Example 3

[0086] 28 parts by mass of zinc oxide, 28 parts by mass of titanium oxide and 10 parts by mass of aluminum oxide were added to 100 parts by mass of water and dispersed at 500 rpm for 0.5 h to obtain slurry I.

[0087] The dispersed slurry I was stirred and emulsified at a stirring speed of 1500 rpm, and then added to a ball mill and ball-milled for 1 hour to obtain slurry II with a particle size of 1 μm.

[0088] 34 parts by mass of indium tin oxide were added to 50 parts by mass of pure water and dispersed at 1500 rpm for 1 hour to obtain slurry III.

[0089] Slurry III was stirred and emulsified at a stirring speed of 1500 rpm, and then put into a ball mill together with slurry II. During the ball milling process, 12.5 parts by weight of PVB were added. The ball milling speed was 700 rpm and the ball milling time was 2 hours to obtain ball milled material with a particle size of 1 μm.

[0090] The ball-milled slurry was spray-granulated at an inlet air temperature of 250℃, an outlet air temperature of 100℃, and a spray speed of 15000rpm. The powder was then mixed with a mixer at 30rpm / min for 100min.

[0091] Using a rigid mold, the powder was pressed into a cylindrical target blank with a size of 210 mm at 400 MPa.

[0092] The pressed target blank was sintered at a temperature of 1450℃ for 7 hours. After sintering, the doped ITO target material was obtained.

[0093] The resistivity of the ITO targets obtained in Examples 1-3 and Comparative Examples 1-6 were tested according to the national standard GB / T-351-2019.

[0094] The results are shown in Table 1.

[0095] Table 1

[0096]

[0097] As can be seen from Table 1, the resistivity of ITO targets containing zinc oxide, titanium oxide, or aluminum oxide is lower than that containing only zinc oxide, titanium oxide, or aluminum oxide, or compared to both containing zinc oxide, titanium oxide, and aluminum oxide. Furthermore, the resistivity of the target increases when the content of zinc oxide, titanium oxide, and aluminum oxide is outside the range defined in this invention.

[0098] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An oxide target material, characterized in that, The target material contains 25-30 wt% zinc oxide, 25-30 wt% titanium oxide, and 5-12.5 wt% aluminum oxide, with the balance being indium tin oxide; the resistivity of the target material is 2.7 × 10⁻⁶. -5 ~3.2×10 -5 Ω·m.

2. The oxide target material as described in claim 1, characterized in that, The outer diameter of the target material is 180~210mm.

3. The method for preparing the oxide target material according to any one of claims 1-2, characterized in that, Includes the following steps: Zinc oxide, titanium oxide, and aluminum oxide powders were added to pure water and dispersed to obtain slurry I; Slurry I was emulsified and then ball-milled to obtain slurry II; Indium tin oxide powder was added to water and dispersed to obtain slurry III; Emulsified slurry III is then mixed with slurry II and binder, and ball-milled to obtain ball-milled material; Spray-dry the ball milling material, then granulate it to obtain pellets; After being shaped, the pellets are sintered.

4. The preparation method according to claim 3, characterized in that, The solid content of slurry I is 25-50 wt%; the solid content of slurry III is 25-50 wt%.

5. The preparation method according to claim 3, characterized in that, The particle size D50 of the slurry II is 0.3~1μm; the particle size D50 of the ball milling material is 0.3~1μm.

6. The preparation method according to any one of claims 3-5, characterized in that, The binder is PVB and / or PVA; the amount of binder added is 1.5 to 5% of the total mass of slurry II and slurry III.

7. The preparation method according to any one of claims 3-5, characterized in that, The spray drying method is centrifugal spray drying, with a nozzle rotation speed of 7000~15000 rpm, an inlet air temperature of 150~250℃, and an outlet air temperature of 50~100℃.

8. The preparation method according to any one of claims 3-5, characterized in that, The forming method is cold isostatic pressing.

9. The preparation method according to any one of claims 3-5, characterized in that, The sintering is atmospheric pressure sintering, and the sintering temperature is 1200~1450℃.

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