Zinc aluminum oxide target having high oxygen vacancy concentration and method of making the same

Abstract

The application belongs to the technical field of semiconductors, and discloses a preparation method of a zinc aluminum oxide target material with high oxygen vacancy concentration. In a vacuum environment, zinc aluminum oxide precursors and titanium powder are placed in the same environment and do not contact each other, and are sintered according to a gradient heating method to obtain a zinc aluminum oxide target material. The gradient heating method is as follows: heating at a speed of 0.5-1.5 DEG C / min, and holding for 0.5-1.5 h at 1000 DEG C±20 DEG C, 1100 DEG C±20 DEG C and 1200 DEG C±20 DEG C respectively; when the temperature is raised to 1200-1350 DEG C, holding for 10-12 h; and then reducing the temperature at a speed of 0.1-0.5 DEG C / min. The method uses titanium to absorb oxygen, and realizes the increase of oxygen vacancies of the zinc aluminum oxide target material under vacuum conditions. While titanium is used, the oxygen vacancies can be optimized by controlling the stepwise heating amplitude. Meanwhile, the application also provides the zinc aluminum oxide target material.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, specifically to a zinc oxide aluminum target with high oxygen vacancy concentration and its preparation method. Background Technology

[0002] The target material is a basic consumable in the magnetron sputtering process. Not only is it used in large quantities, but the quality of the target material plays a crucial role in determining the performance of the thin film.

[0003] For zinc oxide aluminum sputtering targets, controlling the oxygen vacancy concentration is an important indicator of quality control.

[0004] Existing technology 1: Wan Dongyun et al. published a method for preparing pure ZnO targets with oxygen vacancies in *Chinese Optical Letters* (Vol. 9, No. 10, 2011, pp. 103-102). In this method, a dry-pressed ZnO preform is sintered at 1350℃ for 4 hours and then placed in a small crucible inside an inverted large crucible. Carbon powder is placed between the two crucibles. During the heating process, the carbon powder reacts with residual oxygen to form reducing CO gas. This gas then reduces ZnO, causing oxygen to be lost from the inverted ZnO lattice, thus forming a zinc oxide target with oxygen vacancies.

[0005] Prior art 2: CN108546109A discloses a method for preparing large-size AZO magnetron sputtering targets with controllable oxygen vacancies. The method involves placing a ceramic preform into a conventional lifting-type box-type electric resistance furnace with 4-10 air inlets in the furnace chamber wall. The furnace is heated from room temperature to a first-step set temperature of 1050-1250℃ at a rate of 0.5-10℃ / min, held for 30-90 min, and then heated to a second-step set temperature of 1300-1450℃ at a rate of 10-100℃ / min, held for 120-480 min. n, and finally cooled to room temperature at a rate of 0.5-10℃ / min to form a semi-finished product; wherein, after cooling to the set temperature of the first step, the crucible sealed with high-purity carbon-based solid material is placed at each air inlet of the furnace chamber of the aforementioned ordinary lifting box-type resistance furnace, and compressed air is introduced from the air inlet at a flow rate of 5-50 sccm, and this operation is continued until the temperature drops to 1000℃; after the temperature drops to 1000℃, the compressed air introduced from the air inlet is converted into nitrogen at a flow rate of 5-50 sccm, and this operation is continued until the temperature drops to 300℃.

[0006] It is evident that both existing technologies 1 and 2 utilize carbon, a typical reducing material; the former uses it throughout the heating process, while the latter uses it during the cooling process.

[0007] Using carbon has the following problems:

[0008] 1. To ensure a sufficient presence of reducing gases, oxygen or air must be added;

[0009] 2. Existing technology 1 uses carbon powder, which is prone to dust generation, damaging the purity of the target material. At the same time, carbon powder easily adheres to the heating tube, shortening the equipment's lifespan.

[0010] 3. Existing technology 2 obviously takes into account the problem of toner. It uses a cured carbon-based material, but it requires air assistance to ensure that the carbon-based material can generate carbon monoxide and achieve the effect of increasing oxygen vacancies.

[0011] For those skilled in the art, it is common practice to improve zinc oxide aluminum targets based on the absorption of oxygen by carbon and the reduction effect of carbon monoxide (Prior Art 1) or the reduction effect of carbon monoxide (Prior Art 2).

[0012] However, due to the above problems, the preparation process of zinc oxide aluminum target material is relatively complicated.

[0013] Therefore, the technical problem to be solved in this case is: how to increase the oxygen vacancies in the zinc oxide aluminum target while simplifying the process. Summary of the Invention

[0014] One of the objectives of this invention is to provide a method for preparing a zinc oxide aluminum target with a high oxygen vacancy concentration. This method uses titanium to absorb oxygen, thereby increasing the oxygen vacancy in the zinc oxide aluminum target under vacuum conditions. In addition to using titanium, the oxygen vacancy can be optimized by controlling the step temperature rise.

[0015] Meanwhile, the present invention also provides the zinc oxide aluminum target material.

[0016] Unless otherwise specified in this invention, M stands for mol / L and % stands for mass percentage.

[0017] To achieve the above objectives, the present invention provides a method for preparing a zinc-aluminum oxide target with high oxygen vacancy concentration. In a vacuum environment, a zinc-aluminum oxide precursor and titanium powder are placed in the same environment without contacting each other, and sintered by a gradient heating method to obtain a zinc-aluminum oxide target.

[0018] The gradient heating method is as follows:

[0019] The temperature is increased at a rate of 0.5℃ to 1.5℃ / min, and held at three stages: 1000℃±20℃, 1100℃±20℃, and 1200℃±20℃ for 0.5 to 1.5 hours each. When the temperature reaches 1200 to 1350℃, it is held for 10 to 12 hours. Then the temperature is decreased at a rate of 0.1℃ to 0.5℃ / min.

[0020] The purpose of using gradient heating in this invention is to ensure that the target material is fully degassed during sintering by holding it at different temperatures, thus making the target material density uniform. Also, since oxygen removal is more difficult for zinc oxide targets compared to other targets, it is necessary to increase the holding time at each temperature to facilitate oxygen removal.

[0021] In other words, the temperature gradient can be set to be denser, but it cannot be reduced. Different temperature gradients are used to allow gas to escape from different depths of the material, from shallow to deep. Only when the shallow channels are clear can the deep gas be allowed to escape more smoothly. Therefore, theoretically speaking, it is feasible to appropriately extend the low-temperature isothermal time, but the low-temperature isothermal time cannot be shortened.

[0022] Therefore, reasonable variations in the temperature gradient of this invention should be included within the scope of protection of this invention. This invention only verifies the most basic experimental parameters, and it is not excluded that equivalent substitutions and optimizations based on the basic conditions of this invention can still yield the results of this invention.

[0023] In some embodiments of the present invention, the heating rate is 0.5℃ / min, 0.7℃ / min, 0.9℃ / min, 1.0℃ / min, or 1.5℃ / min;

[0024] The maximum temperature can be: 1200℃, 1210℃, 1220℃, 1230℃, 1240℃, 1250℃, 1260℃, 1270℃, 1280℃, 1290℃, 1300℃, 1310℃, 1320℃, 1330℃, 1340℃ or 1350℃;

[0025] In some embodiments of the present invention, the cooling rate is 0.1℃ / min, 0.2℃ / min, 0.3℃ / min, 0.4℃ / min, or 0.5℃ / min;

[0026] In the above-mentioned method for preparing zinc oxide aluminum target material with high oxygen vacancy concentration, the gradient heating method is as follows:

[0027] The temperature is increased at a rate of 0.7℃~1.2℃ / min, and held at three stages: 1000℃±10℃, 1100℃±10℃, and 1200℃±10℃ for 50~70min each; when the temperature reaches 1200~1350℃, it is held for 10~12h; then the temperature is decreased at a rate of 0.2℃~0.4℃ / min to 500℃ or below.

[0028] Preferably, the zinc oxide aluminum precursor is composed of zinc oxide and aluminum oxide, and the mass ratio of zinc oxide to aluminum oxide is 97-98:2-3.

[0029] In some embodiments of the present invention, the mass ratio of zinc oxide to aluminum oxide is 97:3, 98:2, or 99:1;

[0030] In the above-mentioned method for preparing zinc oxide aluminum target material with high oxygen vacancy concentration, the method for preparing the zinc oxide aluminum precursor is as follows:

[0031] Zinc oxide aluminum mixed powder is obtained by dispersing, grinding, and granulating zinc oxide, aluminum oxide, dispersant and binder. Then, zinc oxide aluminum mixed powder is molded and cold isostatically pressed to obtain zinc oxide aluminum target preform. Zinc oxide aluminum target preform is heated and degreased to obtain zinc oxide aluminum precursor.

[0032] More optimally, the preparation method of the zinc-aluminum oxide precursor is as follows:

[0033] Step 1: Pour the alumina powder and the first dispersant into a slurry tank containing pure water, disperse them evenly, and then wet grind them to obtain slurry one.

[0034] Step 2: Add zinc oxide powder, pure water and a second dispersant to slurry one, disperse evenly, and then wet grind to obtain slurry two;

[0035] Step 3: Add binder to the obtained slurry two, disperse evenly, and then wet grind to obtain slurry three;

[0036] Step 4: The slurry is spray-granulated, then mixed and sieved to obtain zinc oxide aluminum mixed powder;

[0037] Step 5: The zinc oxide aluminum powder mixture is molded and then cold isostatically pressed to obtain the zinc oxide aluminum target blank;

[0038] Step 6: Heat-treat the zinc oxide aluminum target blank at a temperature controlled between 400℃ and 600℃ for degreasing.

[0039] In the above-mentioned method for preparing zinc oxide aluminum target material with high oxygen vacancy concentration, the first dispersant and the second dispersant are each independently one or more combinations of polyvinylpyrrolidone, sodium dodecylbenzenesulfonate, and sodium hexadecylbenzenesulfonate.

[0040] In the above-mentioned method for preparing zinc oxide aluminum target material with high oxygen vacancy concentration, the weight of the first dispersant is equivalent to 1-5% of the total weight of the slurry.

[0041] The weight of the second dispersant is equivalent to 1-5% of the total weight of the zinc oxide powder and the second dispersant.

[0042] In the above method for preparing zinc oxide aluminum target material with high oxygen vacancy concentration, the molding process parameters in step 5 are as follows:

[0043] The molding process is as follows: After filling the mold with mixed powder into a 50-300mm mold, it is placed in a hydraulic press and hydraulically pressed at a pressure of 15-80Mpa. After demolding, zinc oxide aluminum target blanks are obtained.

[0044] The process parameters for cold isostatic pressing are as follows: the obtained zinc oxide aluminum target blank is placed in a soft packaging film, which is generally made of PE plastic bag. The sealed bag is placed in a cold isostatic press and immersed in a liquid pressure medium. The blank is then pressed by high-pressure liquid injected by a high-pressure pump at a pressure of 360MPa-400MPa to obtain the zinc oxide aluminum target blank.

[0045] In the above-mentioned method for preparing zinc oxide aluminum target material with high oxygen vacancy concentration, a gradient heating operation is carried out in a sintering furnace.

[0046] A layer of alumina fine sand with a thickness of 1.5-2.5mm is pre-laid in the sintering furnace, then a layer of sintering plate is placed on top, and a quartz boat containing titanium powder with a purity of 99.99% is placed on the sintering plate.

[0047] The weight of the titanium powder is 0.1% to 100% of the weight of the zinc oxide aluminum precursor; preferably, the weight of the titanium powder is 1% to 20% of the weight of the zinc oxide aluminum precursor.

[0048] Finally, the present invention also discloses a zinc oxide aluminum target material, which is prepared by any of the methods described above.

[0049] Beneficial effects

[0050] Compared with the prior art, the present invention has the following advantages:

[0051] (1) In this invention, elemental titanium was selected as a material for adsorbing oxygen. It has the advantages of being difficult to vaporize, having a high melting point, and being able to rapidly combine with oxygen at the sintering temperature. These are characteristics that many other elemental metals do not have.

[0052] (2) The present invention optimizes oxygen vacancy while sintering, which can not only increase the oxygen vacancy on the surface, but also increase the oxygen vacancy in the inner layer. By controlling the heating gradient during the heating process, the exhaust channels of the surface and inner layers are smooth, which is conducive to further increasing the oxygen vacancy at high temperature and constant temperature.

[0053] (3) The titanium powder of the present invention has a high density, and the dust is not easy to fly under vacuum conditions. Compared with carbon powder, it can ensure the purity of the product. At the same time, the titanium powder has a large specific surface area and can quickly adsorb oxygen. Compared with carbon-based solid materials, its adsorption speed has obvious advantages. It can achieve the purpose of generating high oxygen vacancies without generating reducing gas. Detailed Implementation

[0054] The present invention will be further described below with reference to embodiments, but this does not constitute any limitation on the present invention. Any limited modifications made within the scope of the claims of the present invention are still within the scope of the claims of the present invention.

[0055] To illustrate the technical content of the present invention in detail, the following description is provided in conjunction with the embodiments.

[0056] Example 1

[0057] (1) Weigh out zinc oxide (Malvin D90 is 1.61 microns) and alumina powder (Malvin D90 is 1.28 microns) in a mass ratio of 97.5:2.5 and set aside.

[0058] (2) Add a certain amount of pure water to the slurry tank, and add the alumina powder and PVP weighed in step (1) to the slurry tank for pre-dispersion. The dispersion time is 30 min and the dispersion speed is 100 rpm. PVP accounts for 4% of the total mass of the added alumina powder, pure water and PVP.

[0059] (3) The slurry obtained in step 2 is fed into a sand mill for grinding using a pneumatic diaphragm pump. The grinding time is 12 hours and the grinding speed is 1500 r / min to obtain slurry one.

[0060] (4) Add zinc oxide powder and PVP to the slurry obtained in step 3 and disperse for 30 minutes at a speed of 100 rpm. Then, use a pneumatic diaphragm pump to feed the slurry into a sand mill for grinding for 8 hours at a speed of 1500 rpm to obtain slurry two. PVP accounts for 4% of the total mass of the added zinc oxide powder and PVP.

[0061] (5) PVA was added to slurry two obtained in step 4 and pre-dispersed for 30 minutes at a dispersion speed of 100 rpm. Then, the slurry was pumped into a sand mill for grinding for 2 hours at a grinding speed of 1500 rpm to obtain slurry three. The binder accounted for 10% of the total mass of the added zinc oxide powder, alumina, and binder.

[0062] (6) The slurry obtained in step 5 is fed into a spray drying tower for spray granulation, followed by mixing and sieving to obtain zinc oxide aluminum mixed powder. The outlet air temperature is 75℃ and the atomizer frequency is 120Hz.

[0063] (7) The mixed powder obtained in step 6 is molded by molding and cold isostatic pressing to obtain zinc oxide aluminum target blank;

[0064] The molding process is as follows: After filling the mold with mixed powder into a 50-300mm mold, it is placed in a hydraulic press and hydraulically pressed at a pressure of 15-80Mpa. After demolding, zinc oxide aluminum target blanks are obtained.

[0065] The process parameters for cold isostatic pressing are as follows: the obtained zinc oxide aluminum target blank is placed in a soft packaging film, which is generally made of PE plastic bag. The sealed bag is placed in a cold isostatic press and immersed in a liquid pressure medium. The blank is then pressed by high-pressure liquid injected by a high-pressure pump at a pressure of 360MPa-400MPa to obtain the zinc oxide aluminum target blank.

[0066] (8) The target blank obtained in step 7 is placed in a sintering furnace for degreasing heat treatment. Under air atmosphere, the temperature is controlled at 500°C with a heating rate of 0.5 / min and a holding time of 8h. After cooling to room temperature, the additives and other organic matter in the target blank are removed.

[0067] (9) Spread a layer of fine alumina sand with a thickness of about 1.5-2.5 mm evenly on the sintering plate of the sintering furnace. The purity of the fine alumina sand is not less than 98%, and the particle size is between 0.15-0.25 mm.

[0068] (10) Place the heat-treated target blank from step 8 on the laid alumina fine sand, cover it with a firing plate, and place a quartz boat filled with titanium powder on the firing plate. The titanium powder has a purity of 99.99% and a weight of 80% of the target blank.

[0069] (11) Close the furnace door and perform vacuum sintering at a heating rate of 1℃ / min. Heat to 1000℃, 1100℃, and 1200℃ and hold for 1 hour each. Hold at 1300℃ for 12 hours, then slowly cool down at 0.1℃ / min. After cooling to 400℃, allow to cool naturally. Do not open the furnace door before the temperature drops to 200℃. Obtain the target material.

[0070] (12) The relative density of the target material obtained in step 11 was 99.67%, and the oxygen vacancy concentration was 6.32E+18cm. -3 .

[0071] (13) The obtained target material was sputtered using a sputtering coating machine with Ar / O2 / H2 as the working gas. The sputtering power was 100W, the pressure was 0.4Pa, the substrate temperature was 200℃, the gas flow rate was 1%O2 / 1.8%H2, the pre-sputtering time was 300s, and the sputtering time was 380s. The measured glass slide mobility was 19.29cm. 2 / (V·S).

[0072] Example 2

[0073] It is largely the same as Example 1, except that the weight ratio of zinc oxide and aluminum oxide powder is 97:3.

[0074] The target material has a relative density of 99.63% and an oxygen vacancy concentration of 6.28E+18cm. -3 .

[0075] The obtained target material was sputtered using a sputtering coating machine with Ar / O2 / H2 as the working gas. The sputtering power was 100 W, the pressure was 0.4 Pa, the substrate temperature was 200 °C, the gas flow rate was 1% O2 / 1.8% H2, the pre-sputtering time was 300 s, and the sputtering time was 380 s. The measured glass slide mobility was 19.13 cm⁻¹. 2 / (V·S).

[0076] Example 3

[0077] It is largely the same as Example 1, except that the weight ratio of zinc oxide and aluminum oxide powder is 98:2.

[0078] The target material has a relative density of 99.57% and an oxygen vacancy concentration of 6.14E+18cm. -3 .

[0079] The obtained target material was sputtered using a sputtering coating machine with Ar / O2 / H2 as the working gas. The sputtering power was 100 W, the pressure was 0.4 Pa, the substrate temperature was 200 °C, the gas flow rate was 1% O2 / 1.8% H2, the pre-sputtering time was 300 s, and the sputtering time was 380 s. The measured glass slide mobility was 19.02 cm⁻¹. 2 / (V·S).

[0080] Example 4

[0081] The general process is the same as in Example 1, except for step 11:

[0082] Vacuum sintering was performed with the furnace door closed. The heating rate was 0.5℃ / min. The temperature was raised to 1000℃, 1100℃, and 1200℃, and held for 0.9 hours each. The temperature was then held at 1300℃ for 12 hours. After that, the temperature was slowly lowered at 0.5℃ / min until it reached 400℃. Then, the temperature was allowed to drop naturally. The furnace door should not be opened until the temperature dropped to 200℃. The target material was obtained.

[0083] The target material has a relative density of 99.52% and an oxygen vacancy concentration of 6.18E+18cm. -3 .

[0084] The obtained target material was sputtered using a sputtering coating machine with Ar / O2 / H2 as the working gas. The sputtering power was 100 W, the pressure was 0.4 Pa, the substrate temperature was 200 °C, the gas flow rate was 1% O2 / 1.8% H2, the pre-sputtering time was 300 s, and the sputtering time was 380 s. The measured glass slide mobility was 19.16 cm⁻¹. 2 / (V·S).

[0085] Example 5

[0086] The general process is the same as in Example 1, except for step 11:

[0087] Vacuum sintering was performed with the furnace door closed. The heating rate was 1.5℃ / min. The temperature was raised to 1000℃, 1100℃, and 1200℃, and held for 1.1 hours each. The temperature was then held at 1300℃ for 12 hours. After that, the temperature was slowly lowered at 0.3℃ / min until it reached 400℃. Then, the temperature was allowed to drop naturally. The furnace door should not be opened until the temperature dropped to 200℃. The target material was obtained.

[0088] The target material has a relative density of 99.53% and an oxygen vacancy concentration of 6.14E+18cm. -3 .

[0089] The obtained target material was sputtered using a sputtering coating machine with Ar / O2 / H2 as the working gas. The sputtering power was 100 W, the pressure was 0.4 Pa, the substrate temperature was 200 °C, the gas flow rate was 1% O2 / 1.8% H2, the pre-sputtering time was 300 s, and the sputtering time was 380 s. The measured glass slide mobility was 19.16 cm⁻¹. 2 / (V·S).

[0090] Example 6

[0091] The general process is the same as in Example 1, except for step 11:

[0092] Vacuum sintering was performed with the furnace door closed. The heating rate was 1℃ / min. The temperature was raised to 980℃, 1120℃, and 1180℃, and held for 1 hour each. The temperature was then held at 1300℃ for 12 hours. After that, the temperature was slowly lowered at 0.1℃ / min until it reached 400℃. Then, the temperature was allowed to drop naturally. The furnace door should not be opened until the temperature dropped to 200℃. The target material was obtained.

[0093] The target material has a relative density of 98.47% and an oxygen vacancy concentration of 3.75E+17cm. -3 .

[0094] The obtained target material was sputtered using a sputtering coating machine with Ar / O2 / H2 as the working gas. The sputtering power was 100 W, the pressure was 0.4 Pa, the substrate temperature was 200 °C, the gas flow rate was 1% O2 / 1.8% H2, the pre-sputtering time was 300 s, and the sputtering time was 380 s. The measured glass slide mobility was 15.27 cm⁻¹. 2 / (V·S).

[0095] Example 7

[0096] The general process is the same as in Example 1, except for step 11:

[0097] Vacuum sintering was performed with the furnace door closed. The heating rate was 1℃ / min, and the temperature was raised to 1020℃, 1080℃, and 1220℃, and held for 1 hour each. The temperature was then held at 1300℃ for 12 hours. After that, the temperature was slowly lowered at 0.1℃ / min until it reached 400℃, after which it was allowed to cool naturally. The furnace door should not be opened until the temperature dropped to 200℃. The target material was then obtained.

[0098] The target material has a relative density of 98.59% and an oxygen vacancy concentration of 4.29E+17cm. -3 .

[0099] The obtained target material was sputtered using a sputtering coating machine with Ar / O2 / H2 as the working gas. The sputtering power was 100 W, the pressure was 0.4 Pa, the substrate temperature was 200 °C, the gas flow rate was 1% O2 / 1.8% H2, the pre-sputtering time was 300 s, and the sputtering time was 380 s. The measured glass slide mobility was 15.64 cm⁻¹. 2 / (V·S).

[0100] Comparative Example 1

[0101] (1) Weigh out zinc oxide and aluminum oxide powders according to the mass ratio of 97.5:2.5 and set aside.

[0102] (2) Add a certain amount of pure water to the slurry tank, and add the alumina powder and PVP weighed in step (1) to the slurry tank for pre-dispersion. The dispersion time is 30 min and the dispersion speed is 100 rpm. PVP accounts for 4% of the total mass of the added alumina powder, pure water and PVP.

[0103] (3) The slurry obtained in step 2 is fed into a sand mill for grinding using a pneumatic diaphragm pump. The grinding time is 12 hours and the grinding speed is 1500 r / min to obtain slurry one.

[0104] (4) Add zinc oxide powder and PVP to the slurry obtained in step 3 and disperse for 30 minutes at a speed of 100 rpm. Then, use a pneumatic diaphragm pump to feed the slurry into a sand mill for grinding for 8 hours at a speed of 1500 rpm to obtain slurry two. PVP accounts for 4% of the total mass of the added zinc oxide powder and PVP.

[0105] (5) PVA was added to slurry two obtained in step 4 and pre-dispersed for 30 minutes at a dispersion speed of 100 rpm. Then, the slurry was pumped into a sand mill for grinding for 2 hours at a grinding speed of 1500 rpm to obtain slurry three. The binder accounted for 10% of the total mass of the added zinc oxide powder, alumina, and binder.

[0106] (6) The slurry obtained in step 5 is fed into a spray drying tower for spray granulation, followed by mixing and sieving to obtain zinc oxide aluminum mixed powder. The outlet air temperature is 75℃ and the atomizer frequency is 120Hz.

[0107] (7) The mixed powder obtained in step 6 is molded and cold isostatically pressed to obtain zinc oxide aluminum target blanks.

[0108] (8) The target blank obtained in step 7 is placed in a sintering furnace for degreasing heat treatment. Under air atmosphere, the temperature is controlled at 500°C with a heating rate of 0.5 / min and a holding time of 8h. After cooling to room temperature, the additives and other organic matter in the target blank are removed.

[0109] (9) Spread a layer of fine alumina sand with a thickness of about 1.5-2.5 mm evenly on the sintering plate of the sintering furnace. The purity of the fine alumina sand is not less than 98%, and the particle size is between 0.15-0.25 mm.

[0110] (10) Place the heat-treated target blank from step 8 on the laid alumina fine sand, cover it with a firing plate, and place a quartz boat filled with titanium powder on the firing plate. The titanium powder has a purity of 99.99% and a weight of 80% of the target blank.

[0111] (11) Close the furnace door and perform vacuum sintering at a heating rate of 1℃ / min. After heating to 1300℃, hold for 12 hours to obtain the target material.

[0112] (12) The density of the target material obtained in step 9 was tested, and the relative density was found to be 97.32%, with an oxygen vacancy concentration of 9.79E+14cm. -3 .

[0113] (13) The obtained target material was sputtered using a sputtering coating machine with Ar / O2 / H2 as the working gas. The sputtering power was 100W, the pressure was 0.4Pa, the substrate temperature was 200℃, the gas flow rate was 1%O2 / 1.8%H2, the pre-sputtering time was 300s, the sputtering time was 380s, and the glass slide mobility was measured to be 13.25cm2 / (V·S).

[0114] Comparative Example 2

[0115] (1) Weigh out zinc oxide and aluminum oxide powders according to a molar ratio of 97:3 for later use.

[0116] (2) Add a certain amount of pure water to the slurry tank, and add the alumina powder and PVP weighed in step (1) to the slurry tank for pre-dispersion. The dispersion time is 30 min and the dispersion speed is 100 rpm. PVP accounts for 4% of the total mass of the added alumina powder, pure water and PVP.

[0117] (3) The slurry obtained in step 2 is fed into a sand mill for grinding using a pneumatic diaphragm pump. The grinding time is 12 hours and the grinding speed is 1500 r / min to obtain slurry one.

[0118] (4) Add zinc oxide powder and PVP to the slurry obtained in step 3 and disperse for 30 minutes at a speed of 100 rpm. Then, use a pneumatic diaphragm pump to feed the slurry into a sand mill for grinding for 8 hours at a speed of 1500 rpm to obtain slurry two. PVP accounts for 4% of the total mass of the added zinc oxide powder and PVP.

[0119] (5) PVA was added to slurry two obtained in step 4 and pre-dispersed for 30 minutes at a dispersion speed of 100 rpm. Then, the slurry was pumped into a sand mill for grinding for 2 hours at a grinding speed of 1500 rpm to obtain slurry three. The binder accounted for 10% of the total mass of the added zinc oxide powder, alumina, and binder.

[0120] (6) The slurry obtained in step 5 is fed into a spray drying tower for spray granulation, followed by mixing and sieving to obtain zinc oxide aluminum mixed powder. The outlet air temperature is 75℃ and the atomizer frequency is 120Hz.

[0121] (7) The mixed powder obtained in step 6 is molded and cold isostatically pressed to obtain zinc oxide aluminum target blanks.

[0122] (8) The target blank obtained in step 7 is placed in a sintering furnace for degreasing heat treatment. Under air atmosphere, the temperature is controlled at 500°C with a heating rate of 0.5 / min and a holding time of 8h. After cooling to room temperature, the additives and other organic matter in the target blank are removed.

[0123] (9) The target blank obtained in step 8 is placed in a sintering furnace for sintering at a heating rate of 1℃ / min. After heating to 1300℃, it is held for 12h. The target material is obtained.

[0124] (10) The density of the target material obtained in step 9 was tested, and the relative density was found to be 94.97%, with an oxygen vacancy concentration of 6.75E+9cm. -3 .

[0125] (11) The obtained target material was sputtered using a sputtering coating machine with Ar / O2 / H2 as the working gas. The sputtering power was 100W, the pressure was 0.4Pa, the substrate temperature was 200℃, the gas flow rate was 1%O2 / 1.8%H2, the pre-sputtering time was 300s, and the sputtering time was 380s. The measured glass slide mobility was 9.83cm. 2 / (V·S).

[0126] Comparative Example 3

[0127] (1) Weigh out zinc oxide and aluminum oxide powders according to the mass ratio of 97.5:2.5 and set aside.

[0128] (2) Add a certain amount of pure water to the slurry tank, and add the alumina powder and PVP weighed in step (1) to the slurry tank for pre-dispersion. The dispersion time is 30 min and the dispersion speed is 100 rpm. PVP accounts for 4% of the total mass of the added alumina powder, pure water and PVP.

[0129] (3) The slurry obtained in step 2 is fed into a sand mill for grinding using a pneumatic diaphragm pump. The grinding time is 12 hours and the grinding speed is 1500 r / min to obtain slurry one.

[0130] (4) Add zinc oxide powder and PVP to the slurry obtained in step 3 and disperse for 30 minutes at a speed of 100 rpm. Then, use a pneumatic diaphragm pump to feed the slurry into a sand mill for grinding for 8 hours at a speed of 1500 rpm to obtain slurry two. PVP accounts for 4% of the total mass of the added zinc oxide powder and PVP.

[0131] (5) PVA was added to slurry two obtained in step 4 and pre-dispersed for 30 minutes at a dispersion speed of 100 rpm. Then, the slurry was pumped into a sand mill for grinding for 2 hours at a grinding speed of 1500 rpm to obtain slurry three. The binder accounted for 10% of the total mass of the added zinc oxide powder, alumina, and binder.

[0132] (6) The slurry obtained in step 5 is fed into a spray drying tower for spray granulation, followed by mixing and sieving to obtain zinc oxide aluminum mixed powder. The outlet air temperature is 75℃ and the atomizer frequency is 120Hz.

[0133] (7) The mixed powder obtained in step 6 is molded and cold isostatically pressed to obtain zinc oxide aluminum target blanks.

[0134] (8) The target blank obtained in step 7 is placed in a sintering furnace for degreasing heat treatment. Under air atmosphere, the temperature is controlled at 500°C with a heating rate of 0.5 / min and a holding time of 8h. After cooling to room temperature, the additives and other organic matter in the target blank are removed.

[0135] (9) Spread a layer of fine alumina sand with a thickness of about 1.5-2.5 mm evenly on the sintering plate of the sintering furnace. The purity of the fine alumina sand is not less than 98%, and the particle size is between 0.15-0.25 mm.

[0136] (10) Close the furnace door and perform vacuum sintering. The heating rate is 1℃ / min. Heat to 1000℃, 1100℃ and 1200℃ and hold for 1 hour each. Hold at 1300℃ for 12 hours. Then slowly cool down at 0.1℃ / min. After cooling down to 400℃, allow it to cool naturally. Do not open the furnace door before the temperature drops to 200℃ to obtain the target material.

[0137] (11) The relative density of the target material obtained in step 11 was 96.13%, and the oxygen vacancy concentration was 6.32E+13cm. -3 .

[0138] (12) The obtained target material was sputtered using a sputtering coating machine with Ar / O2 / H2 as the working gas. The sputtering power was 100W, the pressure was 0.4Pa, the substrate temperature was 200℃, the gas flow rate was 1%O2 / 1.8%H2, the pre-sputtering time was 300s, and the sputtering time was 380s. The measured glass slide mobility was 10.28cm. 2 / (V·S).

[0139] Comparative Example 4

[0140] The general process is the same as in Example 1, except for step 11:

[0141] Vacuum sintering was performed with the furnace door closed. The heating rate was 1℃ / min. The temperature was raised to 1100℃ and then 1200℃, and held for 1.5 hours each. The temperature was then held at 1300℃ for 12 hours. After that, the temperature was slowly lowered at 0.1℃ / min until it reached 400℃. Then, the temperature was allowed to drop naturally. The furnace door should not be opened until the temperature dropped to 200℃. The target material was obtained.

[0142] (12) The relative density of the target material obtained in step 11 was 97.82%, and the oxygen vacancy concentration was 9.92E+14cm. -3 .

[0143] (13) The obtained target material was sputtered using a sputtering coating machine with Ar / O2 / H2 as the working gas. The sputtering power was 100W, the pressure was 0.4Pa, the substrate temperature was 200℃, the gas flow rate was 1%O2 / 1.8%H2, the pre-sputtering time was 300s, and the sputtering time was 380s. The measured glass slide mobility was 13.56cm. 2 / (V·S).

[0144] Comparative Example 5

[0145] The general process is the same as in Example 1, except for step 11:

[0146] Vacuum sintering was performed with the furnace door closed. The heating rate was 2℃ / min. The temperature was raised to 1000℃, 1100℃, and 1200℃, and held for 1 hour each. The temperature was then held at 1300℃ for 12 hours. After that, the temperature was slowly lowered at 0.1℃ / min until it reached 400℃. Then, the temperature was allowed to drop naturally. The furnace door should not be opened until the temperature dropped to 200℃. The target material was obtained.

[0147] The experiment was terminated because the target material cracked due to excessive heating rate.

[0148] Comparative Example 6

[0149] The general process is the same as in Example 1, except for step 11:

[0150] Place the heat-treated target blank from step 8 on the spread alumina fine sand, cover it with a firing plate, and place a quartz boat containing carbon particles (1mm particle size) on the firing plate, with a weight of 50% of the target blank's weight.

[0151] After using it, we found that vacuum sintering could not be used for subsequent experiments, so we switched to oxygen sintering; the density and oxygen vacancy concentration of the target material obtained by oxygen sintering were not significantly inferior to those in Example 1.

[0152] After repeatability testing, we found the following problems:

[0153] 1. Using carbon sintering will damage the sintering furnace, resulting in the performance of the target material deteriorating from one sintering batch to the next. This is because it will cause significant damage to the heating wire. Unless the heating wire is replaced frequently, this will lead to increased costs.

[0154] 2. The purity of the target material in Comparative Example 9 is significantly lower than that in Example 1.

[0155] In summary, the characteristics of this case are as follows:

[0156] 1. As can be seen from Examples 1-7, by gradient heating and slow cooling, combined with non-contact oxygen adsorption and reduction, a product with a high oxygen vacancy concentration can be obtained.

[0157] Among these factors, the maintenance of the stepped temperature during heating is the most important factor affecting the oxygen vacancy concentration. This invention optimizes oxygen vacancy during sintering, which can not only increase the oxygen vacancy on the surface but also in the inner layer. By controlling the temperature gradient during the heating process, the exhaust channels of the surface and inner layers are kept smooth, which facilitates further improvement of oxygen vacancy at high temperature and constant temperature.

[0158] 2. As can be seen from Example 1 and Comparative Example 1, for zinc oxide aluminum targets, the increase in oxygen vacancy concentration is limited without a step-by-step heating process; however, compared to the scheme in Comparative Example 2 that did not use reducing powder, it can achieve an increase of several orders of magnitude, indicating that the use of titanium powder is essential. As can be seen from Comparative Example 3, step-by-step heating helps to increase oxygen vacancy concentration, indicating that a vacuum environment is conducive to oxygen removal during the heating operation, but its importance is not as great as that of titanium powder.

[0159] 3. As can be seen from Comparative Example 4 and Example 1, the 1000°C heat preservation operation is very necessary. The possible reason is that at 1000°C, the inner and outer crystals undergo preliminary rearrangement and their gas channels are constructed. Appropriately extending the heat preservation at this stage is beneficial to the smoothness of the subsequent channels.

[0160] The comparison between Comparative Example 1 and Comparative Example 4 shows that without the 1000℃ holding period, the oxygen vacancy concentration did not increase by the expected order of magnitude. Therefore, maintaining the low temperature constant temperature period for a certain period of time is necessary.

[0161] In further verification of the present invention, by canceling the heat preservation stages of 1100°C and 1200°C respectively, we found that although the heat preservation stages of 1100°C and 1200°C are important, they have increased by orders of magnitude compared with Comparative Example 1. Although they are still 2-3 orders of magnitude different from Example 1, the increase in oxygen vacancies and the low temperature isothermal stage are more closely related.

[0162] 4. As can be seen from Comparative Examples 5 and 6, neither excessively rapid heating nor the use of toner can produce products that meet the basic standards.

[0163] In this invention, titanium is selected as an elemental form obtained through repeated optimization in this project. Titanium oxide has the following characteristics: high temperature stability and resistance to vaporization and sublimation; elemental titanium has the following characteristics: resistance to softening at sintering temperature, good activity at sintering temperature, and resistance to vaporization and sublimation; the former ensures that it does not contaminate the target material, and the latter ensures that it can effectively absorb oxygen.

[0164] For example, iron decomposes at temperatures above 1200℃; aluminum has an oxide film on its surface, making it difficult to react; alkali metals are too reactive and easily volatilize; elemental zinc sublimates at around 1000℃; and carbon powder is extremely easy to fly around and contaminate the target material.

[0165] The embodiments presented herein are merely selected implementations based on combinations of all possible embodiments. The appended claims should not be limited to the embodiments described herein. Some numerical ranges used in the claims include sub-ranges within them, and variations within these ranges should also be covered by the appended claims.

Claims

1. A method for preparing a zinc oxide aluminum target with high oxygen vacancy concentration, characterized in that, In a vacuum environment, zinc oxide aluminum precursor and titanium powder are placed in the same environment without contacting each other, and sintered by gradient heating to obtain zinc oxide aluminum target material. The gradient heating method is as follows: The temperature is increased at a rate of 0.5℃~1.5℃ / min, and held at three stages: 1000℃±20℃, 1100℃±20℃, and 1200℃±20℃ for 0.5~1.5h each. When the temperature reaches 1200~1350℃, it is held for 10~12h. Then the temperature is decreased at a rate of 0.1℃~0.5℃ / min. After the temperature drops to 400℃, it is allowed to cool naturally. The furnace door should not be opened before the temperature drops to 200℃ to obtain the target material. The zinc oxide aluminum precursor is composed of zinc oxide and aluminum oxide, and the mass ratio of zinc oxide to aluminum oxide is 97-98:2-3.

2. The method for preparing zinc oxide aluminum target material with high oxygen vacancy concentration according to claim 1, characterized in that, The gradient heating method is as follows: The temperature is increased at a rate of 0.7℃~1.2℃ / min, and held at three stages: 1000℃±10℃, 1100℃±10℃, and 1200℃±10℃ for 50~70min each. When the temperature reaches 1200~1350℃, it is held for 10~12h. Then the temperature is decreased at a rate of 0.2℃~0.4℃ / min. After the temperature drops to 400℃, it is allowed to cool naturally. The furnace door should not be opened before the temperature drops to 200℃ to obtain the target material.

3. The method for preparing zinc oxide aluminum target material with high oxygen vacancy concentration according to claim 1, characterized in that, The method for preparing the zinc oxide aluminum precursor is as follows: A slurry containing zinc oxide, aluminum oxide, dispersant, and binder is dispersed, ground, and granulated to obtain a zinc oxide aluminum mixed powder. The zinc oxide aluminum mixed powder is then molded and cold isostatically pressed to obtain a zinc oxide aluminum target preform. The zinc oxide aluminum target preform is then heated and degreased to obtain a zinc oxide aluminum precursor.

4. The method for preparing zinc oxide aluminum target material with high oxygen vacancy concentration according to claim 3, characterized in that, The method for preparing the zinc oxide aluminum precursor is as follows: Step 1: Pour the alumina powder and the first dispersant into a slurry tank containing pure water, disperse them evenly, and then wet grind them to obtain slurry one. Step 2: Add zinc oxide powder, pure water and a second dispersant to slurry one, disperse evenly, and then wet grind to obtain slurry two; Step 3: Add binder to the obtained slurry two, disperse evenly, and then wet grind to obtain slurry three; Step 4: The slurry is spray-granulated, then mixed and sieved to obtain zinc oxide aluminum mixed powder; Step 5: The zinc oxide aluminum powder mixture is molded and then cold isostatically pressed to obtain the zinc oxide aluminum target blank; Step 6: Heat-treat the zinc oxide aluminum target blank at a temperature controlled between 400℃ and 600℃ for degreasing.

5. The method for preparing zinc oxide aluminum target material with high oxygen vacancy concentration according to claim 4, characterized in that, The first dispersant and the second dispersant are each independently one or more combinations of polyvinylpyrrolidone, sodium dodecylbenzenesulfonate, and sodium hexadecylbenzenesulfonate.

6. The method for preparing zinc oxide aluminum target material with high oxygen vacancy concentration according to claim 5, characterized in that, The weight of the first dispersant is equivalent to 1-5% of the total weight of the slurry; The weight of the second dispersant is equivalent to 1-5% of the total weight of the zinc oxide powder and the second dispersant.

7. The method for preparing zinc oxide aluminum target material with high oxygen vacancy concentration according to claim 4, characterized in that, In step 5, the molding process parameters are as follows: The molding process is as follows: After filling the mold with mixed powder into a 50-300mm mold, it is placed in a hydraulic press and hydraulically pressed at a pressure of 15-80MPa. After demolding, zinc oxide aluminum target blank is obtained. The process parameters for cold isostatic pressing are as follows: the obtained zinc oxide aluminum target blank is placed in a soft packaging film, which is made of PE plastic bag. The sealed bag is placed in a cold isostatic press and immersed in a liquid pressure medium. The blank is then pressed by high-pressure liquid injected by a high-pressure pump at a pressure of 360MPa-400MPa to obtain the zinc oxide aluminum target blank.

8. The method for preparing zinc oxide aluminum target material with high oxygen vacancy concentration according to claim 1, characterized in that, Gradient heating operation is carried out in the sintering furnace; A layer of fine alumina sand with a thickness of 1.5-2.5 mm is pre-laid in the sintering furnace, then a layer of firing plate is placed on top, and a quartz boat containing titanium powder with a purity of 99.99% is placed on the firing plate. The weight of the titanium powder is 0.1% to 100% of the weight of the zinc oxide aluminum precursor.

9. The method for preparing zinc oxide aluminum target material with high oxygen vacancy concentration according to claim 8, characterized in that, The weight of the titanium powder is 1 to 20% of the weight of the zinc oxide aluminum precursor.

10. A zinc oxide aluminum target material, characterized in that, It is prepared by the method described in any one of claims 1 to 9.