An indium zinc oxide evaporation target and a preparation method thereof

Abstract

The present invention relates to the technical field of target production, and discloses a preparation method of an indium zinc oxide evaporation target. In this method, a dispersant, a binder, zinc oxide powder, and indium oxide powder are first added to pure water and mixed to obtain a mixed slurry; then the mixed slurry is spray granulated to obtain IZO powder; subsequently, the IZO powder is spread into a graphite boat, sintered for the first time, and sieved to obtain the IZO powder after the first sintering; finally, deionized water is added to the IZO powder after the first sintering for wetting, molded, and sintered for the second time to obtain the indium zinc oxide evaporation target; the indium zinc oxide evaporation target prepared by the above method not only has a high relative density and conductivity, but also can be directly used for evaporation. In addition, the present application also discloses an indium zinc oxide evaporation target.

Description

Technical Field

[0001] The present invention relates to the technical field of target production, and particularly relates to an indium zinc oxide evaporation target and a preparation method thereof. Background Art

[0002] Transparent conductive oxide (TCO for short) is an important optoelectronic functional material. It has a high transmittance to visible light, a high reflectance to infrared light, and excellent electrical conductivity. Therefore, TCO is widely used in fields such as solar cells, flat panels, liquid crystal displays, light-emitting diodes, and thermal radiation mirrors. Indium tin oxide (ITO for short) is the most widely used transparent conductive film at present. Common preparation methods of ITO thin films include vacuum evaporation, chemical vapor deposition, spraying, magnetron sputtering, and sol-gel methods.

[0003] Among them, the vacuum evaporation method uses a large current to generate high heat energy to evaporate or sublimate the evaporation material into gaseous particles with energy, which leave the surface of the evaporation material and deposit on the surface of the material to be coated to form a thin film. It has the advantages of simple film-forming method, high purity and density of the thin film, and unique film structure and performance. As the raw material for vacuum evaporation of IZO thin films, IZO evaporation materials present a huge market.

[0004] Zinc oxide has rich raw material sources, low price, non-toxicity, and good stability in hydrogen plasma; it is a wide-bandgap semiconductor, has a high transmittance to visible light, is easy to achieve n-type doping, and the electrical conductivity of the transparent conductive film after n-type doping is close to that of ITO. Therefore, transparent conductive films doped with zinc oxide as the matrix have become the current research focus and have a development trend of gradually replacing ITO in many fields. Currently, indium zinc oxide (In2O3-ZnO: usually called IZO) evaporation targets are widely used in multiple electronic components such as transparent conductive films for liquid crystal display devices or gas sensors.

[0005] Chinese Patent Application No. 202211616872.1 discloses an indium zinc oxide target and a preparation method thereof. The indium zinc oxide target is composed of indium oxide and zinc oxide, and the atomic ratio of Zn to In in the target is Zn / (Zn + In) = 18% - 50%. The preparation method is as follows: adding a dispersant, zinc oxide powder, indium oxide powder, and a binder into water, stirring and dispersing evenly, then wet grinding to obtain a mixed slurry; spray granulating the obtained mixed slurry to obtain IZO powder, and then sintering after dry pressing and cold isostatic pressing to obtain an indium zinc oxide target;

[0006] The IZO target prepared by the above - mentioned solution has a high proportion of ZnO addition amount, can achieve a high density and conductivity, and can significantly reduce the usage amount of indium metal;

[0007] Meanwhile, the above - mentioned solution further adopts a preparation process of mixing and granulating slurries with large and small particle sizes. After the large and small particle - sized particles are mixed by the slurry and granulated, the contact between particles can be made closer, and the density and conductivity of the target can be improved;

[0008] However, it should be noted that dispersants, binders and other additives are added during the preparation process of the above - mentioned solution. During the preparation process, it is inevitable that the above - mentioned additives will remain and adhere to the powder surface. After high - temperature sintering, part of the dispersants and binders volatilize, which is likely to cause a certain degree of downward trend in the overall density of the target.

[0009] Chinese Patent Application No. 202211616130.9 discloses an indium zinc oxide doped rare earth metal target and its preparation method, including the following steps: Step 1: Mix zinc oxide powder and rare metal oxide powder and grind them wet; Step 2: Add indium oxide powder to the mixture in Step 1, mix and grind them wet, and then add a binder and mix and grind; Step 3: Granulate, shape, cold isostatic press, and sinter the product of Step 2; The weight ratio of the indium oxide powder, zinc oxide powder and rare metal oxide powder is: 77.5 - 93.2: 6.7 - 22.3: 0.1 - 0.2; The average particle size of the indium oxide powder is 0.1 - 3μm, the average particle size of the zinc oxide powder is 0.5 - 4μm, and the average particle size of the rare metal oxide powder is 0.5 - 4μm.

[0010] And by observing the specification of the above - mentioned solution, it can be seen that through multiple grindings, appropriate particle size selection and optimization of the raw material ratio in the above - mentioned solution, the conductivity reaches more than 1100 s / cm and the density reaches 97%; However, at the same time, it should be noted that the above - mentioned solution still does not consider the influence of the dispersant on the relative density of the target too much.

[0011] At the same time, the above two precedents are both cases of improving the relative density of planar targets. In the field of target preparation, there are still certain differences between evaporation targets and planar targets;

[0012] Chinese Patent Application No. 201210228240.8 discloses a preparation method of a high - density ITO evaporation target. Step 1: According to the requirements of the component ratio, prepare indium tin oxide powders with different average particle sizes according to the weight percentage of In2O3: 90% - 98%, SnO2: 2% - 10%. The average particle size D50 of the powder is 30 - 130nm, and the specific surface area is 3 - 20m 2 / g;

[0013] Step 2: Wet-mix the two kinds of powders with different particle size distributions obtained in Step 1 for 12 to 30 hours, then add additives, including binder, lubricant, surfactant, and dispersant, and continue mixing for 4 to 24 hours to uniformly coat the powders with the organic matter;

[0014] Step 3: Dry and granulate the ITO powder with additives treated in Step 2 at 80 to 120 °C;

[0015] Step 4: Put the granulated ITO powder treated in Step 3 into a metal mold for pre-pressing, with a pressure of 60 to 140 MPa;

[0016] Step 5: Cold isostatically press the green compact target treated in Step 4, with a pressure of 200 to 350 MPa;

[0017] Step 6: Put the ITO green compact formed in Step 5 into a debinding furnace, dehydrate and remove binders at 500 to 800 °C, and keep the temperature for 4 to 48 hours;

[0018] Step 7: Put the debound ITO green compact treated in Step 6 into a sintering furnace and sinter it under normal pressure or non-pressure oxygen atmosphere at a temperature of 1400 to 1700 °C for 10 to 72 hours; Through the above steps, a high-density ITO evaporation target is prepared.

[0019] This solution enables the moisture and other additives in the ITO green compact to be discharged as much as possible through the dehydration and debinding step before sintering, thereby improving the relative density of the evaporation target. However, it should be noted that after the dehydration and debinding step is completed, the target is basically formed, that is, the green compact mentioned in the solution. For the basically formed green compact, it is rather difficult to further sinter it to improve its relative density.

[0020] Problems to be solved by this solution: How to further improve the relative density and conductivity of the evaporation target. Summary of the Invention

[0021] The purpose of this application is to provide a method for preparing an indium zinc oxide evaporation target, which further optimizes the preparation process, reduces the influence of additives such as dispersants and binders on the target density, and thus improves the relative density and conductivity of the target.

[0022] Unless otherwise specified in this application: nM represents nanomoles per liter, μM represents micromoles per liter, mM represents millimoles per liter, and M represents moles per liter;

[0023] To achieve the above purpose, this application discloses a method for preparing an indium zinc oxide evaporation target, including the following steps:

[0024] Step 1: Add a dispersant, a binder, zinc oxide powder, and indium oxide powder to pure water and mix to obtain a mixed slurry;

[0025] Step 2: Spray granulate the mixed slurry to obtain IZO powder;

[0026] Step 3: Spread the IZO powder into a graphite boat, sinter it for the first time, and screen it to obtain the IZO powder after the first sintering;

[0027] Step 4: Add deionized water to the IZO powder after the first sintering to wet it, perform molding, and sinter it for the second time to obtain an indium zinc oxide evaporation target.

[0028] Preferably, the mass ratio of the zinc oxide powder to the indium oxide powder is 2 - 3:97 - 98.

[0029] Preferably, Step 1 specifically includes:

[0030] Step A1: Disperse the first dispersant in water, then add the zinc oxide powder to the water containing the first dispersant, disperse it at a rotation speed of 300 rpm for 20 - 40 min, and then grind it to obtain Slurry 1;

[0031] Step A2: Disperse the second dispersant in water, add Slurry 1 to the water containing the second dispersant, disperse it at a rotation speed of 300 rpm for 20 - 40 min, add the indium oxide powder, and then grind it to obtain Slurry 2;

[0032] Step A3: Add a binder to Slurry 2 and grind it at a rotation speed of 1200 - 1400 rpm for 5 hours to obtain a mixed slurry;

[0033] The addition amount of the first dispersant is 5 - 7% of the mass of the zinc oxide powder;

[0034] The addition amount of the second dispersant is 5 - 7% of the total mass of the zinc oxide powder and the indium oxide powder;

[0035] The addition amount of the binder is 15% of the total mass of the zinc oxide powder, the indium oxide powder, the first dispersant, and the second dispersant.

[0036] Preferably, in Step 1, the median particle size of the mixed slurry is 0.17 - 0.25 microns.

[0037] Preferably, the first dispersant is selected from at least one of polyvinylpyrrolidone, sodium dodecylbenzenesulfonate, polycarboxylic acid-based compounds, polyvinyl salts, or sodium hexadecylbenzenesulfonate;

[0038] The second dispersant is selected from at least one of polyvinylpyrrolidone, sodium dodecylbenzenesulfonate, polycarboxylic acid-based compounds, polyvinyl salts, or sodium hexadecylbenzenesulfonate;

[0039] The binder is selected from at least one of a mixture of polyvinyl alcohol and polyethylene glycol added, polyvinyl alcohol, and polyvinyl butyral.

[0040] Preferably, step 2 is specifically as follows: The mixed slurry obtained in step 1 is spray granulated using a spray drying tower to obtain IZO powder; wherein the outlet air temperature during the spray granulation process is 60 - 80°C, and the frequency of the atomizer is 20 - 26 Hz.

[0041] Preferably, step 3 is specifically as follows: The IZO powder obtained in step 2 is spread into a graphite boat, and then heated to 1200 - 1300°C at a heating rate of 2°C / min and held for 7 - 9 hours. After the first sintering is completed, it is sieved to obtain the IZO powder after the first sintering.

[0042] Preferably, step 4 specifically includes:

[0043] Step B1: Add deionized water to the IZO powder after the first sintering to wet it, and then let it stand for 24 hours to obtain an IZO precursor;

[0044] Step B2: Put the IZO precursor into a mold and apply pressure to obtain an IZO green body;

[0045] Step B3: Put the IZO green body into a sintering furnace, heat it to 1450 - 1500°C at a heating rate of 0.5°C / min and hold for 10 hours to obtain an indium zinc oxide evaporation target;

[0046] In step B1, the addition amount of deionized water is 3 - 7% of the mass of the IZO powder;

[0047] In step B2, during the pressure application process, the pressure is 15T and the pressure application time is 100 seconds.

[0048] Preferably, the particle size of the indium oxide powder is 1 - 5 microns; the particle size of the zinc oxide powder is 1 - 5 microns.

[0049] In addition, the present application also discloses an indium zinc oxide evaporation target, which is obtained by the preparation method of the indium zinc oxide evaporation target described above. The relative density of the indium zinc oxide evaporation target is greater than or equal to 98%; the conductivity is 1360 - 1950 s / cm.

[0050] The beneficial effects of the present application are as follows: Through one-time sintering in the present application, the dispersant and binder are decomposed by high temperature. Meanwhile, after one-time sintering, the powder is pressed and then sintered for the second time. The advantage of setting the pressing process after one-time sintering in the present application is that, on the one hand, it can prevent the IZO powder from caking after one-time sintering, resulting in the generation of internal defects. On the other hand, sintering after the decomposition of the dispersant and binder during one-time sintering can further reduce the gaps between the powders, thereby improving its relative density. And through one-time sintering, the present application can further reduce the oxides, lower the content of carbon and other impurities, improve the purity of the powder, and at the same time eliminate the work hardening of the powder and stabilize the crystal structure of the powder. Detailed implementation mode

[0051] In the description of the present invention, it should be noted that for those not specified in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. For the reagents or instruments not specified in the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0052] The following will describe the present invention clearly and completely in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work belong to the scope of protection of the present invention.

[0053] Embodiment 1

[0054] Step A1: Weigh zinc oxide powder and indium oxide powder according to the mass ratio of zinc oxide powder to indium oxide powder of 3:97. Subsequently, disperse the first dispersant in water, then add the zinc oxide powder to the water containing the first dispersant, and disperse it at a rotation speed of 300 rpm for 20 min, and then grind it at a rotation speed of 1300 rpm for 8 hours to obtain slurry one.

[0055] Step A2: Disperse the second dispersant in water, add slurry one to the water containing the second dispersant, disperse it at a rotation speed of 300 rpm for 20 min, add indium oxide powder, and then grind it at a rotation speed of 1300 rpm for 10 hours to obtain slurry two.

[0056] Step A3: Add a binder to slurry two and grind it at a rotation speed of 1200 rpm for 5 hours to obtain a mixed slurry.

[0057] After grinding in step A3, the particle size of the mixed slurry is 0.242 μm.

[0058] The first dispersant is polyvinylpyrrolidone and the addition amount is 5% of the mass of the zinc oxide powder.

[0059] The second dispersant is polyvinylpyrrolidone and the addition amount is 5% of the total mass of zinc oxide powder and indium oxide powder;

[0060] The binder is polyvinyl alcohol and the addition amount is 15% of the total mass of zinc oxide powder, indium oxide powder, the first dispersant and the second dispersant;

[0061] Step 2: Spray granulate the mixed slurry prepared in Step 1 using a spray drying tower to obtain IZO powder; wherein the outlet air temperature during the spray granulation process is 60 °C and the frequency of the atomizer is 20 Hz.

[0062] Step 3: Spread the IZO powder prepared in Step 2 into a graphite boat, then heat it to 1200 °C at a heating rate of 2 °C / min and hold for 7 hours. After the first sintering is completed, sieve it to obtain the IZO powder after the first sintering.

[0063] Step B1: Add deionized water to the IZO powder after the first sintering to wet it, then let it stand for 24 hours to obtain an IZO precursor;

[0064] Step B2: Put the IZO precursor into a mold and apply pressure to obtain an IZO green body;

[0065] Step B3: Put the IZO green body into a sintering furnace, heat it to 1450 °C at a heating rate of 0.5 °C / min and hold for 10 hours to obtain an indium zinc oxide evaporation target;

[0066] In Step B1, the addition amount of deionized water is 3% of the mass of the IZO powder;

[0067] In Step B2, during the pressure application process, the pressure is 15 T and the pressure application time is 100 seconds.

[0068] Example 2

[0069] Step A1: Weigh zinc oxide powder and indium oxide powder according to the mass ratio of zinc oxide powder to indium oxide powder of 2:98. Then, disperse the first dispersant in water, then add the zinc oxide powder to the water containing the first dispersant, and disperse it at a rotation speed of 300 rpm for 40 min, and then grind it at a rotation speed of 1300 rpm for 8 hours to obtain Slurry 1;

[0070] Step A2: Disperse the second dispersant in water, add Slurry 1 to the water containing the second dispersant, disperse it at a rotation speed of 300 rpm for 40 min, add indium oxide powder, and then grind it at a rotation speed of 1300 rpm for 10 hours to obtain Slurry 2;

[0071] Step A3: Add the binder to Slurry 2 and grind it at a rotation speed of 1400 rpm for 5 hours to obtain a mixed slurry;

[0072] After step A3 grinding, the particle size of the mixed slurry is 0.171 μm;

[0073] Wherein the first dispersant is sodium dodecylbenzenesulfonate and the addition amount is 7% of the mass of the zinc oxide powder;

[0074] The second dispersant is sodium hexadecylbenzenesulfonate and the addition amount is 7% of the total mass of the zinc oxide powder and indium oxide powder;

[0075] The binder is polyvinyl butyral and the addition amount is 15% of the total mass of the zinc oxide powder, indium oxide powder, first dispersant and second dispersant;

[0076] Step 2: Spray granulate the mixed slurry prepared in step 1 using a spray drying tower to obtain IZO powder; wherein the outlet air temperature during the spray granulation process is 80 °C and the frequency of the atomizer is 26 Hz.

[0077] Step 3: Spread the IZO powder prepared in step 2 into a graphite boat, then heat it to 1300 °C at a heating rate of 2 °C / min and hold for 9 hours. After the first sintering is completed, sieve to obtain the IZO powder after the first sintering.

[0078] Step B1: Add deionized water to the IZO powder after the first sintering to wet it, then let it stand for 24 hours to obtain an IZO precursor;

[0079] Step B2: Put the IZO precursor into a mold and apply pressure to obtain an IZO green body;

[0080] Step B3: Put the IZO green body into a sintering furnace, heat it to 1500 °C at a heating rate of 0.5 °C / min and hold for 10 hours to obtain an indium zinc oxide evaporation target;

[0081] In step B1, the addition amount of deionized water is 7% of the mass of the IZO powder;

[0082] In step B2, during the pressure application process, the pressure is 15 T and the pressure application time is 100 seconds.

[0083] Example 3

[0084] Step A1: Weigh zinc oxide powder and indium oxide powder according to the mass ratio of zinc oxide powder to indium oxide powder of 2.5:97.5. Then, disperse the first dispersant in water, then add the zinc oxide powder to the water containing the first dispersant, and disperse it at a rotation speed of 300 rpm for 30 min, and then grind it at a rotation speed of 1300 rpm for 8 hours to obtain slurry one;

[0085] Step A2: Disperse the second dispersant into water, add Slurry 1 into the water containing the second dispersant, disperse at a rotation speed of 300 rpm for 30 min, add indium oxide powder, and then grind at a rotation speed of 1300 rpm for 10 hours to obtain Slurry 2;

[0086] Step A3: Add a binder to Slurry 2 and grind at a rotation speed of 1300 rpm for 5 hours to obtain a mixed slurry;

[0087] After grinding in Step A3, the median particle size of the mixed slurry is 0.201 μm;

[0088] Wherein the first dispersant is sodium hexadecyl benzene sulfonate and the addition amount is 5% of the mass of zinc oxide powder;

[0089] The second dispersant is sodium dodecyl benzene sulfonate and the addition amount is 5% of the total mass of zinc oxide powder and indium oxide powder;

[0090] The binder is a mixture of polyvinyl alcohol and polyethylene glycol, and the addition amount is 15% of the total mass of zinc oxide powder, indium oxide powder, the first dispersant and the second dispersant;

[0091] Step 2: Spray granulate the mixed slurry prepared in Step 1 using a spray drying tower to obtain IZO powder; wherein the outlet air temperature during the spray granulation process is 70 °C and the frequency of the atomizer is 24 Hz.

[0092] Step 3: Spread the IZO powder prepared in Step 2 into a graphite boat, then heat it to 1250 °C at a heating rate of 2 °C / min and hold for 8 hours. After the first sintering is completed, sieve to obtain the IZO powder after the first sintering.

[0093] Step B1: Add deionized water to the IZO powder after the first sintering to wet it, and then let it stand for 24 hours to obtain an IZO precursor;

[0094] Step B2: Put the IZO precursor into a mold and apply pressure to obtain an IZO green body;

[0095] Step B3: Put the IZO green body into a sintering furnace, heat it to 1475 °C at a heating rate of 0.5 °C / min and hold for 10 hours to obtain an indium zinc oxide evaporation target;

[0096] In Step B1, the addition amount of deionized water is 5% of the mass of the IZO powder;

[0097] In Step B2, during the pressure application process, the pressure is 15 T and the pressure application time is 100 seconds.

[0098] Example 4

[0099] Basically the same as Example 1, except that the first dispersant is a mixture of polyvinylpyrrolidone and sodium dodecylbenzenesulfonate, and the mass ratio of polyvinylpyrrolidone to sodium dodecylbenzenesulfonate is 1:1.

[0100] Example 5

[0101] Basically the same as Example 1, except that the second dispersant is a mixture of sodium hexadecylbenzenesulfonate and sodium dodecylbenzenesulfonate, and the mass ratio of sodium hexadecylbenzenesulfonate to sodium dodecylbenzenesulfonate is 1:1.

[0102] Example 6

[0103] Basically the same as Example 1, except that the first dispersant is a mixture of polyvinylpyrrolidone and sodium dodecylbenzenesulfonate, and the mass ratio of polyvinylpyrrolidone to sodium dodecylbenzenesulfonate is 1:1;

[0104] The second dispersant is a mixture of sodium hexadecylbenzenesulfonate and sodium dodecylbenzenesulfonate, and the mass ratio of sodium hexadecylbenzenesulfonate to sodium dodecylbenzenesulfonate is 1:1.

[0105] Comparative Example 1

[0106] Basically the same as Example 1, except that the first dispersant, zinc oxide powder, the second dispersant, and indium oxide powder are added together to obtain Slurry 2.

[0107] Comparative Example 2

[0108] Basically the same as Example 1, except that deionized water is not added to the IZO powder in step B1.

[0109] Comparative Example 3

[0110] Basically the same as Example 1, except that the IZO powder prepared in step 2 is loaded into a mold, then placed in a hot press furnace, pre-pressed at 60 MPa. After the pre-pressing is completed, the vacuum degree of the hot press furnace is pumped to below 10 Pa, heated to 1000 °C at a rate of 8 °C / min, and when the holding time reaches 20 minutes, the pressure in the vacuum furnace is increased to 180 MPa and held for 1 hour;

[0111] Subsequently, it is cooled by furnace cooling, and after processing, an IZO evaporation target is obtained.

[0112] Comparative Example 4

[0113] Basically the same as Example 1, except that the primary sintering process in step 3 is not carried out; deionized water is added to the IZO powder prepared in step 2 to wet it, and then it is left standing for 24 hours to obtain an IZO precursor;

[0114] Put the IZO precursor into a mold and apply pressure to obtain a green IZO body;

[0115] Put the green IZO body into a sintering furnace, heat it at a heating rate of 0.5 °C / min to 1450 °C - 1500 °C and hold for 10 hours to obtain an indium zinc oxide evaporation target.

[0116] Comparative Example 5

[0117] It is basically the same as Example 1, except that in step B1, the addition amount of deionized water is 20% of the mass of the IZO powder after the first sintering.

[0118] Performance test:

[0119] Observe the cracking situation of the targets prepared in each example and comparative example, and test the relative density and conductivity of the targets prepared in the examples and comparative examples. The results are shown in Table 1:

[0120] Table 1: Performance test result table

[0121]

[0122] Result analysis:

[0123] 1. It can be seen from Examples 1 - 3 that when variables such as the particle size of the mixed slurry, the mass ratio of zinc oxide to indium oxide, the dispersion time, the dispersion rotation speed, the sintering time, and the sintering temperature change slightly, only minor fluctuations occur in the relative density and conductivity of the evaporation target;

[0124] It can be seen from Example 1 and Examples 4 - 6 that when the first dispersant is a mixture of polyvinylpyrrolidone and sodium dodecylbenzenesulfonate, the relative density and conductivity of the target increase to a certain extent; when the second dispersant is a mixture of sodium hexadecylbenzenesulfonate and sodium dodecylbenzenesulfonate, the relative density and conductivity of the target also increase to a certain extent;

[0125] When both of the above are satisfied, that is, the implementation method shown in Example 6, it can be seen that the relative density and conductivity of the target increase significantly. We speculate that the reason for this phenomenon may be that, on the one hand, after the first dispersant and the second dispersant are compounded, indium oxide and zinc oxide are more evenly distributed, thereby increasing the relative density and conductivity to a certain extent. On the other hand, the compounded dispersant evenly disperses the powder in the liquid, thereby forming a stable slurry, increasing the surface activity of the powder, effectively preventing it from precipitating or aggregating in the liquid, improving the quality and stability of the slurry, and thus indirectly increasing the relative density and conductivity of the target, and further making the relative density and conductivity of the target show a significant increase;

[0126] 2. As can be seen from Example 1 and Comparative Example 1, when the first dispersant, zinc oxide powder, the second dispersant, and indium oxide powder are added together, the relative density and conductivity of the target show an obvious downward trend. We speculate that the reason for this phenomenon is that when the first dispersant, zinc oxide powder, the second dispersant, and indium oxide powder are added together, the zinc oxide powder and indium oxide powder are not sufficiently dispersed. Moreover, during the grinding process, it is inevitable that the powder is not ground sufficiently, resulting in an insufficient particle size of the powder in Slurry 2. At the same time, the components in Slurry 2 are not evenly dispersed, so the relative density and conductivity of the target decrease significantly.

[0127] 3. As can be seen from Example 1 and Comparative Example 2, when deionized water is not added, the relative density and conductivity of the target both decrease significantly. We believe that the reason for this phenomenon is that the moisture contained in the powder for making the target has the effect of a lubricant. Its presence can reduce the friction between particles, facilitate the effective transmission of cold pressing pressure, and also facilitate the smooth sliding and rearrangement of powder particles. However, when the water content is too low or too high, it will affect the quality of the target. The binder and other components in the powder have been completely eliminated during the first calcination, and the powder itself does not have any adhesiveness. After the precursor powder is wetted by moisture, the fragmentation and rearrangement between particles during the forming process are more obvious than when no water is added; and then during the sintering process, the contact surface between particles is larger, the sintering driving force is stronger, so the sintered density is higher. Since the sintered density of the target itself is higher, the internal defects are fewer and the conductivity of the target itself is also higher.

[0128] 4. As can be seen from Example 1 and Comparative Example 3, when vacuum hot pressing is used instead of the method of secondary sintering combined with pressing used in this application, the relative density and conductivity of the target both decrease to varying degrees. We speculate that the reason for this phenomenon may be that compared with the method of secondary sintering combined with pressing in the present invention, vacuum hot pressing is difficult to resist the deformation resistance between powders, and the pressure is difficult to be transmitted to the core of the powder material, resulting in a low density. At the same time, during vacuum hot pressing, the number of pores inside the green body decreases, the scattering probability of free electrons decreases, resulting in a decrease in resistivity. When the hot pressing temperature continues to rise, the grains grow, the grain boundaries decrease, weakening the scattering of free carriers. At the same time, point defects in the crystal are thermally excited, resulting in an increase in the concentration of interstitial atoms or the concentration of O atom vacancies, leading to a decrease in the resistivity of the target.

[0129] 5. As can be seen from Example 1 and Comparative Example 4, when the first sintering is not carried out, the relative density and conductivity of the target both decrease significantly. We believe that the reason for this phenomenon is that since the surface of the target contains a certain amount of additives such as dispersants and binders, directly performing secondary sintering without the first sintering causes the dispersants and binders to decompose, resulting in defects inside the target and making it prone to deformation, thereby affecting the relative density and conductivity of the target.

[0130] As can be seen from Example 1 and Comparative Example 5, when the addition amount of deionized water is excessive, it causes too much moisture in the target in the sintered IZO precursor, and then leaves some pores while the moisture evaporates during the secondary sintering process, thereby reducing the relative density and conductivity of the target.

[0131] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A preparation method of an indium zinc oxide evaporation target, characterized in that, It includes the following steps: Among them, step 1 includes the following sub-steps: Step A1: Disperse the first dispersant into water, then add zinc oxide powder into the water containing the first dispersant, and disperse for 20 - 40 minutes at a rotation speed of 300 rpm, and then grind to obtain slurry one; Step A2: Disperse the second dispersant into water, add slurry one into the water containing the second dispersant, and disperse for 20 - 40 minutes at a rotation speed of 300 rpm, add indium oxide powder, and then grind to obtain slurry two; Step A3: Add a binder to slurry two, and grind for 5 hours at a rotation speed of 1200 - 1400 rpm to obtain a mixed slurry; Step 2: Spray granulate the mixed slurry to obtain IZO powder; Step 3: Spread the IZO powder into a graphite boat, conduct primary sintering, and screen to obtain the IZO powder after primary sintering; Step 4: Add deionized water to wet the IZO powder after primary sintering, conduct molding, and conduct secondary sintering to obtain an indium zinc oxide evaporation target, and the addition amount of deionized water is 3 - 7% of the mass of the IZO powder; The first dispersant is a mixture of polyvinylpyrrolidone and sodium dodecylbenzenesulfonate, and the mass ratio of polyvinylpyrrolidone to sodium dodecylbenzenesulfonate is 1:1; The second dispersant is a mixture of sodium hexadecylbenzenesulfonate and sodium dodecylbenzenesulfonate, and the mass ratio of sodium hexadecylbenzenesulfonate to sodium dodecylbenzenesulfonate is 1:1; The mass ratio of the zinc oxide powder to the indium oxide powder is 2 - 3:97 - 98; Among them, the addition amount of the first dispersant is 5 - 7% of the mass of the zinc oxide powder; The addition amount of the second dispersant is 5 - 7% of the total mass of the zinc oxide powder and the indium oxide powder.

2. The preparation method of the indium zinc oxide evaporation target according to claim 1, characterized in that, The addition amount of the binder is 15% of the total mass of the zinc oxide powder, the indium oxide powder, the first dispersant, and the second dispersant.

3. The preparation method of the indium zinc oxide evaporation target according to claim 1, characterized in that, In step 1, the median particle size of the mixed slurry is 0.17 - 0.25 microns.

4. The preparation method of the indium zinc oxide evaporation target according to claim 1, characterized in that The binder is selected from at least one of a mixture of polyvinyl alcohol and polyethylene glycol, polyvinyl alcohol, and polyvinyl butyral.

5. The preparation method of the indium zinc oxide evaporation target according to claim 1, wherein, The specific content of step 2 is: Use a spray drying tower to spray granulate the mixed slurry prepared in step 1 to obtain IZO powder; among them, the outlet air temperature during the spray granulation process is 60 - 80 °C, and the frequency of the atomizer is 20 - 26 Hz.

6. The preparation method of the indium zinc oxide evaporation target according to claim 1, characterized in that, The specific content of step 3 is: Spread the IZO powder prepared in step 2 into a graphite boat, then heat it to 1200 °C - 1300 °C at a heating rate of 2 °C / min and keep it warm for 7 - 9 hours, and screen after the primary sintering is completed to obtain the IZO powder after primary sintering.

7. The preparation method of the indium zinc oxide evaporation target according to claim 1, characterized in that, The specific content of step 4 includes: Step B1: Add deionized water to wet the IZO powder after primary sintering, and then let it stand for 24 hours to obtain an IZO precursor; Step B2: Put the IZO precursor into a mold and apply pressure to obtain an IZO green body; Step B3: Put the IZO green body into a sintering furnace, heat it to 1450 °C - 1500 °C at a heating rate of 0.5 °C / min and keep it warm for 10 hours to obtain an indium zinc oxide evaporation target; In step B2, during the pressure application process, the pressure is 15 T and the pressure application time is 100 seconds.

8. The preparation method of the indium zinc oxide evaporation target according to claim 1, characterized in that, The particle size of the indium oxide powder is 1 to 5 microns; the particle size of the zinc oxide powder is 1 to 5 microns.

9. An indium zinc oxide evaporation target, which is obtained by the preparation method of the indium zinc oxide evaporation target according to any one of claims 1-8, and is characterized in that, The relative density of the indium zinc oxide evaporation target is greater than or equal to 98%; the conductivity is 1360 to 1950 s / cm.

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