Preparation method of high-purity titanium target material

Abstract

The invention belongs to the technical field of target material processing technologies, and provides a preparation method of a high-purity titanium target material, which comprises the following steps: step 1, uniformly mixing titanium powder and stearic acid, putting into a ball mill, continuously ball-milling and uniformly mixing to obtain mixed powder, and carrying out plasma sintering to obtain a titanium raw material; 2, melting and casting a titanium raw material, and cooling to obtain a cast ingot blank; step 3, performing first heat treatment on the cast ingot blank, and performing hot rolling on the cast ingot blank subjected to the first heat treatment to obtain a first titanium blank; 4, the first titanium blank is subjected to second heat treatment, and the first titanium blank subjected to second heat treatment is subjected to hot rolling to obtain a second titanium blank; 5, after the second titanium blank is cooled to the room temperature, the second titanium blank is subjected to cold rolling, and a cold-rolled blank is formed; and 6, annealing heat treatment is conducted on the cold-rolled blank, then machine tool machining is conducted, and the titanium target material is obtained. The provided preparation method can obtain the high-purity titanium target material, the preparation process is simple, and the preparation method can be widely applied to the field of sputtering films of electronic devices and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of target material processing technology, and specifically relates to a method for preparing a high-purity titanium target material. Background Art

[0002] Physical Vapor Deposition (PVD) is widely used in high-end industries such as optics, electronics, and information, such as integrated circuits, liquid crystal displays (LCDs), industrial glass, camera lenses, information storage, ships, and chemicals. The metal target components used in PVD are one of the most important raw materials in the manufacturing process of integrated circuits and liquid crystal displays.

[0003] Titanium (Ti) target is a typical metal target. Titanium target is made of pure titanium or titanium alloy as the main component and is finely manufactured. Its unique advantages include extremely high hardness and density, as well as excellent corrosion resistance, which enables it to maintain stability in various environments. In addition, titanium target also has good thermal conductivity and high purity, which provides excellent performance for sputtering thin film technology, so it is widely used in PVD. Pure titanium sputtering targets are now widely used in decorative coating, tool and mold coating, glass coating, semiconductor device coating, electronic device coating, flat panel display coating and other fields. The production of pure titanium plates for targets mainly controls four aspects: purity, grain size, grain orientation and grain uniformity.

[0004] However, the current technical requirements for manufacturing high-purity titanium targets are high and the production is difficult, especially in the high-end target market such as electronic devices, semiconductors, and flat panel displays. Therefore, how to develop a processing technology for high-purity titanium targets is an urgent problem to be solved. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing a high-purity titanium target material to obtain a high-purity titanium target material to meet production needs.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A method for preparing a high-purity titanium target comprises the following steps:

[0008] Step 1, mixing titanium powder and stearic acid evenly, then putting them into a ball mill to continue ball milling and mixing, obtaining a mixed powder, and performing plasma sintering to obtain a titanium raw material; mixing stearic acid with titanium powder can effectively promote the dispersibility of titanium powder on the one hand, and on the other hand, the hardness of pure titanium will change with its C, H, and O content. After adding stearic acid solid to pure titanium and mixing, the hardness of the titanium raw material can be appropriately increased after sintering;

[0009] Step 2, melting the titanium raw material, casting the molten metal, and cooling after casting to obtain an ingot blank;

[0010] Step 3, subjecting the ingot obtained in step 2 to a first heat treatment, and subjecting the ingot after the first heat treatment to hot rolling to obtain a first titanium billet;

[0011] Step 4, performing a second heat treatment on the first titanium billet obtained in step 3, and hot rolling the first titanium billet after the second heat treatment to obtain a second titanium billet;

[0012] Step 5, after the second titanium billet obtained in step 4 is cooled to room temperature, the second titanium billet is cold rolled to form a cold rolled billet;

[0013] Step 6: subjecting the cold-rolled billet obtained by cold rolling in step 5 to annealing heat treatment, and then subjecting it to machine tool processing to obtain a titanium target material.

[0014] As a further solution of the present invention, the titanium powder in step 1 is prepared by the following steps:

[0015] S1, mixing titanium dioxide and magnesium powder, then pressing and forming, performing a self-propagating reaction, then performing an acid leaching reaction, filtering, and drying to obtain pretreated titanium dioxide;

[0016] S2, mixing the pretreated titanium dioxide and calcium powder, continuing to press and shape, performing deep reduction reaction, obtaining reduced titanium powder, and then performing acid leaching reaction, filtering, and drying to obtain titanium powder. In the above technical solution, magnesium powder and calcium powder are used as reducing agents to reduce titanium dioxide, which can effectively reduce the formation of titanium dioxide, avoid changing the surface properties of the target material, and thus promote the sputtering rate of the target material.

[0017] As a further embodiment of the present invention, the molar ratio of titanium dioxide to magnesium powder in S1 is 1:1.8-2.4.

[0018] As a further solution of the present invention, the dosage ratio of pretreated titanium dioxide and calcium powder in S2 is 1:1.18-1.2.

[0019] As a further solution of the present invention, the amount of stearic acid added in step 1 is 2% to 4.5% by mass of the pure titanium powder.

[0020] As a further solution of the present invention, the melting method in step 2 is atmospheric melting or vacuum melting.

[0021] As a further solution of the present invention, the temperature of the first heat treatment in step 3 is 650-800° C., and the holding time is 1.5-2 hours.

[0022] As a further solution of the present invention, the temperature of the second heat treatment in step 4 is 950-1050° C., and the insulation time is 4.5-6 hours.

[0023] As a further solution of the present invention, the temperature of the annealing heat treatment in step 6 is 650-700° C., and the annealing time is 2.5-4 hours.

[0024] Beneficial effects of the present invention:

[0025] The titanium powder prepared by the present invention can effectively avoid the generation of titanium dioxide, so that the raw titanium powder has high purity, and then a high-purity titanium target material is prepared; at the same time, the high-purity titanium target material prepared by the method provided by the present invention not only has a simple and efficient preparation process, but also has reliable quality and economical cost, and can be widely used in the sputtering film fields such as electronic devices, semiconductors, and flat panel displays.

[0026] The present invention adopts a two-stage heat treatment method, first preheating in the temperature range of 650-800°C, and then heating to 1950-1050°C, so that the elements in the titanium blank produce solid diffusion, thereby reducing the uneven distribution of chemical components, reducing the stratification phenomenon of the target blank, and reducing the grain size. At the same time, it can eliminate residual stress, stabilize the size, reduce brittleness, increase its plasticity, and reduce deformation and crack tendency. DETAILED DESCRIPTION

[0027] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] The titanium powder in the embodiments and comparative examples of the present invention is prepared by the following steps:

[0029] S1. Mix titanium dioxide and magnesium powder (molar ratio of 1:1.8), then press and shape, and conduct self-propagating reaction (place the pressed blank sample in a multifunctional self-propagating reactor and close the reactor cover, open the vacuum pump and vacuum air line in turn, evacuate for 30 minutes, then close the vacuum air line and vacuum pump, introduce argon until the vacuum gauge returns to zero, that is, the reactor is filled with argon, and then repeat the vacuum-ventilation steps twice to ensure the vacuum in the reactor; initiate the self-propagating reaction by local ignition or overall heating, and keep warm. After the insulation is completed, open the cooling pump for cooling, and open the reactor cover to take out the product when the temperature drops below 60°C), then conduct acid leaching reaction, filter, and dry to obtain pretreated titanium dioxide;

[0030] The reaction principle of the above steps is: TiO2+nMg→Ti x O+(2-x)MgO, x<1 (self-propagating reaction)

[0031] S2. Mix the pretreated titanium dioxide and calcium powder (mass ratio is 1:2), continue to press and shape, and perform a deep reduction reaction (place it in a tubular resistance furnace to perform a high-temperature deep reduction process in an inert gas reduction) to obtain reduced titanium powder, followed by an acid leaching reaction, filtering, and drying to obtain titanium powder.

[0032] The reaction principle of the above steps is: Ti x O+Ca→Ti+CaO

[0033] Example 1

[0034] This embodiment provides a method for preparing a high-purity titanium target, comprising the following steps:

[0035] Step 1, titanium powder and stearic acid (the amount of stearic acid added is 2% of the mass of pure titanium powder) are mixed evenly, and then put into a ball mill to continue ball milling and mixing to obtain a mixed powder, and plasma sintering is performed to obtain a titanium raw material;

[0036] Step 2, melting the titanium raw material by vacuum melting, casting the molten metal, and cooling after casting to obtain an ingot blank;

[0037] Step 3, subjecting the ingot obtained in step 2 to a first heat treatment at a temperature of 650° C. for a holding time of 2 h, and subjecting the ingot after the first heat treatment to hot rolling to obtain a first titanium billet;

[0038] Step 4, performing a second heat treatment on the first titanium billet obtained in step 3 at a temperature of 950° C. and a holding time of 6 hours, and hot rolling the first titanium billet after the second heat treatment to obtain a second titanium billet;

[0039] Step 5, after the second titanium billet obtained in step 4 is cooled to room temperature, the second titanium billet is cold rolled to form a cold rolled billet;

[0040] Step 6: subjecting the cold-rolled billet obtained by cold rolling in step 5 to annealing heat treatment at a temperature of 650° C. for 4 hours, and then subjecting the cold-rolled billet to machine tool processing to obtain a titanium target.

[0041] Example 2

[0042] Compared with Example 1, the only difference is:

[0043] Step 1: Mix titanium powder and stearic acid (the amount of stearic acid added is 4% of the mass of pure titanium powder) evenly, then put them into a ball mill for further ball milling and mixing to obtain a mixed powder, and perform plasma sintering to obtain a titanium raw material.

[0044] Example 3

[0045] Compared with Example 1, the only difference is:

[0046] Step 3: subjecting the ingot obtained in step 2 to a first heat treatment at a temperature of 800° C. for a holding time of 1.5 h, and subjecting the ingot after the first heat treatment to hot rolling to obtain a first titanium billet.

[0047] Example 4

[0048] Compared with Example 1, the only difference is:

[0049] Step 4: performing a second heat treatment on the first titanium billet obtained in step 3 at a temperature of 1050° C. for a holding time of 4.5 h, and hot rolling the first titanium billet after the second heat treatment to obtain a second titanium billet.

[0050] Example 5

[0051] Compared with Example 1, the only difference is:

[0052] Step 6: subjecting the cold-rolled billet obtained by cold rolling in step 5 to annealing heat treatment at a temperature of 700° C. for 2.5 h, and then subjecting the cold-rolled billet to machine tool processing to obtain a titanium target.

[0053] Comparative Example 1

[0054] This comparative example provides a method for preparing a high-purity titanium target, comprising the following steps:

[0055] Step 1, melting titanium powder (purchased from Shandong Xiya Chemical Co., Ltd.) by vacuum melting, casting the molten metal, and cooling after casting to obtain an ingot blank;

[0056] Step 2, subjecting the ingot obtained in step 1 to a first heat treatment at a temperature of 650° C. for a holding time of 2 h, and subjecting the ingot after the first heat treatment to hot rolling to obtain a first titanium billet;

[0057] Step 3, performing a second heat treatment on the first titanium billet obtained in step 2 at a temperature of 950° C. and a holding time of 6 hours, and hot rolling the first titanium billet after the second heat treatment to obtain a second titanium billet;

[0058] Step 4, after the second titanium billet obtained in step 3 is cooled to room temperature, the second titanium billet is cold rolled to form a cold rolled billet;

[0059] Step 5: subjecting the cold-rolled billet obtained by cold rolling in step 4 to annealing heat treatment at a temperature of 650° C. for 4 h, and then subjecting the cold-rolled billet to machine tool processing to obtain a titanium target.

[0060] Comparative Example 2

[0061] Compared with Example 1, the only difference is:

[0062] Step 1: Mix titanium powder and stearic acid (the amount of stearic acid added is 1% of the mass of pure titanium powder) evenly, then put them into a ball mill and continue to ball mill and mix them to obtain a mixed powder, and then perform plasma sintering to obtain a titanium raw material.

[0063] Comparative Example 3

[0064] Compared with Example 1, the only difference is:

[0065] Step 3: subjecting the ingot obtained in step 2 to a first heat treatment at a temperature of 600° C. for a holding time of 1.8 h, and subjecting the ingot after the first heat treatment to hot rolling to obtain a first titanium billet.

[0066] Comparative Example 4

[0067] Compared with Example 1, the only difference is:

[0068] The first titanium billet obtained in step 3 is subjected to a second heat treatment at a temperature of 900° C. and a holding time of 6.5 h. The first titanium billet after the second heat treatment is hot rolled to obtain a second titanium billet.

[0069] Comparative Example 5

[0070] Compared with Example 1, the only difference is:

[0071] The cold-rolled billet obtained by cold rolling in step 5 is subjected to annealing heat treatment at a temperature of 550° C. for 4 hours, and then machined to obtain a titanium target.

[0072] Performance tests were performed on Examples 1 to 5 and Comparative Examples 1 to 5 to measure the mass purity and average particle size of the titanium targets obtained in the Examples and Comparative Examples. The test results are shown in Table 1:

[0073] Table 1

[0074] project Mass purity (%) Average grain size (μm) Example 1 99.94 82 Example 2 99.92 85 Example 3 99.89 83 Example 4 99.94 84 Example 5 99.91 86 Comparative Example 1 97.20 118 Comparative Example 2 98.32 95 Comparative Example 3 98.27 98 Comparative Example 4 98.58 102 Comparative Example 5 98.35 99

[0075] It can be seen from Table 1 that the mass purity of the titanium target prepared by the present invention is higher than 99.89%, the average grain size is less than 86 μm, and the average grain size is relatively uniform, which meets the technical requirements for sputtering pure titanium target materials and can be widely used in sputtering film fields such as electronic devices, semiconductors, and flat panel displays.

[0076] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0077] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a high-purity titanium target, characterized in that: The following steps are involved: Step 1, titanium powder and stearic acid are mixed evenly, and then put into a ball mill to continue ball milling and mixing to obtain a mixed powder, and plasma sintering is performed to obtain a titanium raw material; Step 2, melting the titanium raw material, casting the molten metal, and cooling after casting to obtain an ingot blank; Step 3, subjecting the ingot obtained in step 2 to a first heat treatment, and subjecting the ingot after the first heat treatment to hot rolling to obtain a first titanium billet; Step 4, performing a second heat treatment on the first titanium billet obtained in step 3, and hot rolling the first titanium billet after the second heat treatment to obtain a second titanium billet; Step 5, after the second titanium billet obtained in step 4 is cooled to room temperature, the second titanium billet is cold rolled to form a cold rolled billet; Step 6: subjecting the cold-rolled billet obtained by cold rolling in step 5 to annealing heat treatment, and then subjecting it to machine tool processing to obtain a titanium target material.

2. The method for preparing a high-purity titanium target according to claim 1, characterized in that: The titanium powder in step 1 is prepared by the following steps: S1, mixing titanium dioxide and magnesium powder, then pressing and forming, performing a self-propagating reaction, then performing an acid leaching reaction, filtering, and drying to obtain pretreated titanium dioxide; S2, mixing the pretreated titanium dioxide and calcium powder, continuing to press and shape, performing a deep reduction reaction to obtain reduced titanium powder, and then performing an acid leaching reaction, filtering, and drying to obtain titanium powder.

3. The method for preparing a high-purity titanium target according to claim 2, characterized in that: The molar ratio of titanium dioxide to magnesium powder in S1 is 1:1.8-2.

4.

4. The method for preparing a high-purity titanium target according to claim 2, characterized in that: The dosage ratio of pretreated titanium dioxide and calcium powder in S2 is 1:1.18-1.

2.

5. The method for preparing a high purity titanium target according to claim 1, characterized in that: The amount of stearic acid added in step 1 is 2% to 4.5% of the mass of the pure titanium powder.

6. The method for preparing a high purity titanium target according to claim 1, characterized in that: The melting method in step 2 is atmospheric melting or vacuum melting.

7. The method for preparing a high purity titanium target according to claim 1, characterized in that: The temperature of the first heat treatment in step 3 is 650-800° C., and the holding time is 1.5-2 hours.

8. The method for preparing a high purity titanium target according to claim 1, characterized in that: The temperature of the second heat treatment in step 4 is 950-1050° C., and the insulation time is 4.5-6 hours.

9. The method for preparing a high purity titanium target according to claim 1, characterized in that: The temperature of the annealing heat treatment in step 6 is 650-700° C., and the annealing time is 2.5-4 hours.