CN115894010A - Tubular indium gallium zinc (In) oxide 2 Ga 2 ZnO 7 ) Preparation method of fine-grain high-density crack-free target material - Google Patents

Abstract

The invention belongs to the technical field of metal oxide target preparation, and in particular relates to a method for preparing a tubular indium gallium zinc oxide (In ₂ Ga ₂ ZnO ₇ ) fine-grained, high-density, crack-free target. The method comprises material ball milling, granulation, cold isostatic pressing to prepare a tubular target blank, and three-stage sintering. The present invention uses a three-stage sintering process, and prepares a high-density, fine-grained, and crack-free InGaZn tubular target material through the regulation of target material powder treatment, green body molding and sintering process. When the tubular target is sputtered in the rotating cathode, the target utilization rate is increased from 30 to 40% to more than 70% compared with the planar target, which greatly improves the sputtering efficiency and target utilization rate, and has high industrial utilization value.

Description

A preparation method of tubular indium gallium zinc oxide (In2Ga2ZnO7) fine-grained high-density crack-free target

technical field

The invention belongs to the technical field of metal oxide target preparation, and in particular relates to a method for preparing a tubular indium gallium zinc oxide (In ₂ Ga ₂ ZnO ₇ ) fine-grained, high-density, crack-free target.

Background technique

Indium gallium zinc oxide (IGZO) is a kind of transparent conductive oxide (Transparent conductive oxide, TCO) and is a new type of semiconductor material. IGZO is an n-type semiconductor material with a band gap of about 3.5eV. Because of its important role in the electronics industry and other fields, it has become a strong candidate material for driving components such as next-generation display technologies LCD, AMOLED, flexible display, and electronic paper. Compared with other metal oxide semiconductor materials such as indium tin oxide (ITO), tin antimony oxide (ATO), and aluminum zinc oxide (AZO), amorphous IGZO thin films are widely used in flat panel display devices due to their special photoelectric properties. The field of thin film transistors (TFTs) has received extensive attention. Compared with amorphous silicon (α-Si) and low-temperature polysilicon (LTPS) TFTs, IGZO thin film transistors, with their two obvious advantages of the lowest leakage current and the carrier mobility with the largest on-off ratio, can ensure mobile display devices When the pixels are not working, the screen energy consumption is greatly saved. Therefore, high-purity oxides represented by IGZO targets have become the key basic materials for improving the performance of flat-panel displays, and are widely used in the channel layer of thin-film transistors in flat-panel display devices.

InGaZnO thin films are mainly prepared by magnetron sputtering. Compared with other thin film deposition techniques, the magnetron sputtering method has the advantages of low deposition temperature, high deposition efficiency, good film uniformity in the thickness direction, and large-area deposition. The magnetron sputtering method is to make charged ions bombard the target under the action of a magnetic field through high-voltage discharge, so that the particles bombarded on the surface of the target are deposited on the surface of the substrate, thereby preparing a sputtered film. Improving the utilization rate of the target has always been a major problem that needs to be solved urgently in the magnetron sputtering technology.

The current research on improving target utilization mainly focuses on improving the magnetic field structure in the sputtering process and improving the performance of the target. For most magnetron coating equipment, especially the planar magnetron sputtering target, due to the effect of the orthogonal electromagnetic field on the charged ions, the sputtering target will produce uneven erosion during the sputtering process, resulting in the thickness of the sputtered film Inhomogeneity, and due to the uneven etching of the target, the utilization rate of the target is low, which will have an adverse effect on controlling the production cost and production cycle of the film. Therefore, it is necessary to improve the original magnetic field structure, from the original static target surface magnetic field distribution to the dynamically changing target surface magnetic field distribution, and then change the etching area of the charged ions on the target surface, so that the target surface can be etched uniformly, and the target surface can be improved. The utilization rate and the uniformity of the coating. Studies have shown that the design of the moving magnetic field (rotating cathode) and the use of tubular targets can effectively increase the utilization rate of the target, increasing the utilization rate from 30 to 40% to more than 70%. In addition, the IGZO target is used as the raw material for the preparation of the IGZO transparent conductive film. Its properties such as density and grain size will not only affect the film sputtering process, but also have an important impact on the properties of the prepared film. However, due to its special hollow circular tubular structure, the tube target poses a great challenge to the forming and sintering process of the target material, which can easily lead to poor microstructure uniformity of the target blank. After sintering, defects such as cracking and deformation of the tube target and low density will occur, thereby further affecting the performance of the sintered tube target. Therefore, it is possible to control the structure and properties of IGZO tubular targets while preparing them, so as to realize the preparation of fine-grained, high-density, and crack-free indium gallium zinc oxide tubular targets, which will improve target utilization, deposition efficiency and film performance. key.

The invention patent application with the application publication number CN108706965A discloses a short-process preparation method of indium gallium zinc oxide tubular target material, including indium oxide powder, gallium oxide powder and zinc oxide powder ball milling and mixing to obtain a mixed powder; the mixed powder The powder is mixed with the slurry liquid to obtain a slurry, and the mass content of the mixed powder in the slurry is set between 30% and 50%; the slurry is poured into a tubular target mold, molded and demolded, and dried to obtain a tubular target material Blank; Indium Gallium Zinc Oxide tubular target is obtained by integrated degreasing and sintering tubular target blank.

Contents of the invention

In order to solve the problems of low utilization rate of planar targets and poor performance of sputtering films, the present invention provides a method for preparing tubular indium gallium zinc oxide (In ₂ Ga ₂ ZnO ₇ ) targets with high density and fine grains , in order to obtain an indium gallium zinc oxide tubular target with a density of more than 99% and an average particle size of less than 10 μm.

In order to achieve the above object, the present invention is achieved through the following technical solutions:

A method for preparing a tubular indium gallium zinc oxide (In ₂ Ga ₂ ZnO ₇ ) fine-grained, high-density, crack-free target, comprising the following steps:

Step 1: Material ball milling:

Mix the raw materials indium oxide powder, gallium oxide powder, zinc oxide powder, and dispersant ammonium polyacrylate to obtain a mixed powder, add water to the mixed powder, and ball mill to obtain a slurry; then add the binder polyvinyl alcohol, continue Ball milling and mixing to obtain a mixed slurry.

The invention selects high-purity indium oxide powder, gallium oxide powder, and zinc oxide powder as raw materials, uses ammonium polyacrylate as a dispersant, and polyvinyl alcohol as a binder. In terms of mole percentage, the raw materials indium oxide powder, gallium oxide powder, and zinc oxide powder are proportioned in equal molar percentages; ammonium polyacrylate accounts for 0.5-2% of the total amount of raw materials; polyvinyl alcohol accounts for 0.5-2% of the total amount of raw materials .

Wherein, the particle sizes of the raw materials are: indium oxide 70-200 nm, purity 4N; gallium oxide 2-5 μm, purity 4N; zinc oxide 100-600 nm, purity 4N.

When the raw materials indium oxide powder, gallium oxide powder, zinc oxide powder, and dispersant ammonium polyacrylate are ball milled, they are put into a 2L zirconia ball mill jar, and three kinds of zirconia balls of different specifications are placed in the ball mill jar in advance, and Add pure water into the ball mill tank, the amount of pure water added is 60% of the total mass of raw material indium oxide powder, gallium oxide powder, zinc oxide powder, and dispersant ammonium polyacrylate. The specifications of the grinding balls are φ5mm, φ3mm and φ1mm respectively. The quality of the grinding balls of the three specifications remains the same; the ball-to-material ratio is kept at 3:1, and the maximum charging volume does not exceed 1.5L.

Specifically, a high-energy planetary ball mill can be used to fully mix and ball-mill the mixture (indium oxide powder, gallium oxide powder, zinc oxide powder, ammonium polyacrylate and water). The ball mill speed is 150-250r/min, and the ball milling time needs to be more than 24 hours. Then, after adding polyvinyl alcohol into the slurry, ball milling is continued for 1 hour, so that the binder is evenly mixed into the slurry.

Step 2: Granulation:

The ball-milled mixed slurry is taken out from the ball mill tank, and processed by a spray granulation method to obtain a spherical mixed powder. The drying temperature in the spray granulation process needs to be controlled at 180-220°C;

Step 3: Preparation of tubular target blank by cold isostatic pressing method:

Take the mixed powder and fill it in the flexible mold. During the filling process, the mixed powder is vibrated to make the powder evenly fill the mold. The tap density of the powder is 1.6-1.9g/cm ³ ; after the filling is completed, the flexible mold is completely wrapped. After the coating is completed, the powder is pressed and formed by cold isostatic pressing, and the pressure is maintained to obtain a tubular target blank. Among them, the pressure of cold isostatic pressing is 220-280 MPa, and the holding time is 5-15 minutes.

The above-mentioned flexible mold includes a metal core, and an outer sheath is arranged outside the metal core, a powder cavity is formed between the metal core and the outer sheath, upper and lower cover plates are arranged on the top and bottom of the outer sheath, and the upper and lower cover plates are connected with the outer sheath. compatible with the inner diameter. Assemble the metal core, outer casing and lower cover before filling. Assemble the top cover after filling is complete and fully wrap the mold with a film release material.

Step 4: Sintering:

The tubular target blank is taken out from the flexible mold, and the tubular target blank is sintered using a three-stage sintering process to obtain a fine-grained, high-density InGaZnO crack-free tubular target.

The first stage: at room temperature, the temperature is raised to 600°C to degrease the tubular target blank. In order to completely degrease the bisque, it is necessary to slowly raise the temperature in the range from room temperature to 600°C and control the heating rate at 0.5-1°C/min; in the first stage, air is introduced at the beginning of the temperature rise, and the air flow rate is 15L/min;

The second stage: raise the temperature from 600°C to 1450-1550°C, and keep at this temperature for 10 minutes. In order to quickly achieve sintering and densification of the target, increase the heating rate when the temperature rises to 600°C, and control the heating rate at 2-5°C/min until the temperature rises to 1450-1550°C; Switch to oxygen and reduce gas flow to 12L/min;

The third stage: In order to prevent the grains of the target material from being coarse, the temperature is rapidly lowered to 1250-1350°C after a short-term heat preservation at the highest temperature point, and the cooling rate is 5-10°C/min. After 12-18 hours of heat preservation, stop heating and drop to room temperature with a cooling rate of 1-3°C/min. In the third stage, when the temperature drops below 900°C, the oxygen is turned off.

When taking out the tubular target material blank from the flexible mold, the specific operation is: remove the isolation film outside the flexible mold to prevent the liquid pressure medium in the isostatic press from penetrating into the mold; and remove the upper cover plate and outer cover of the flexible mold in sequence .

The beneficial effects of the present invention are:

In order to improve the utilization rate and performance of the indium gallium zinc oxide target, the present invention specially uses a three-stage sintering process, through the control of the target powder treatment, green body forming and sintering process, to prepare high-density, fine-grained, Crack-free InGaZn Tubular Targets. When the tubular target is sputtered in the rotating cathode, the target utilization rate is increased from the original 30-40% to more than 70% compared with the planar target, which greatly improves the sputtering efficiency and target utilization rate, and has high industrial utilization value.

(1) The molding method of the present invention uses a flexible mold combined with a cold isostatic pressing molding process to prepare the InGaZn tubular target blank, which shortens the production cycle and greatly reduces the production cost compared with the grouting molding method, and is suitable for streamlining mass production;

(2) The sintering method of the green body of the present invention adopts a three-stage sintering process. In the first stage, the degreasing process of the bisque was completed, and the initial sintering of the powder was carried out, which prepared for the sintering of the later sample to achieve high density; in the second stage, the sample was raised from low temperature in a short period of time. To a sintering temperature higher than the conventional sintering temperature, the sample powder obtains a higher sintering driving force at this sintering temperature, which provides energy for sintering densification; in the third stage, the sample cools down in a very short time , Rapid cooling from a temperature point higher than conventional sintering to a temperature point lower than conventional sintering, and a long-term heat preservation, so that the sample is densified by high driving force at a low temperature point. The growth of crystal grains is inhibited, and the occurrence of densification is promoted, thereby realizing the preparation of high-density, fine-grained targets. In addition, low temperature sintering and long holding time make the sample shrink slowly, reducing target cracking. By using the sintering method of the invention, a tubular target material of indium gallium zinc oxide with fine grain, high density and no crack is obtained.

(3) The target material prepared by the method of the present invention makes the target material obtain a high utilization rate (from 30 to 40% to more than 70%). At the same time, due to the control of the target material forming and sintering process, the prepared indium oxide Gallium zinc target has the characteristics of high density, fine grain, and no cracking.

Description of drawings

FIG. 1 is a macroscopic photo of an indium gallium zinc oxide target in Example 1.

FIG. 2 is the XRD spectrum of the indium gallium zinc oxide target in Example 1. FIG.

FIG. 3 is a scanning electron microscope image of the polished surface of the indium gallium zinc oxide target in Example 1. FIG.

Figure 4 is a structural diagram of the mold.

Detailed ways

In the following, the present invention will be described in more detail through specific embodiments, so as to facilitate the understanding of the technical solution of the present invention, but it is not used to limit the protection scope of the present invention.

The indium oxide used in the examples is 70-200 nm, with a purity of 4N; the gallium oxide is 2-5 μm, with a purity of 4N; and the zinc oxide is 100-600 nm, with a purity of 4N.

Embodiment one

A method for preparing a tubular indium gallium zinc oxide (In ₂ Ga ₂ ZnO ₇ ) fine-grained, high-density, crack-free target, comprising the following steps:

Step 1: Select high-purity indium oxide, gallium oxide, and zinc oxide powders as raw materials, use ammonium polyacrylate as a dispersant, and polyvinyl alcohol as a binder. Proportion by mole percentage: 33.3% of high-purity indium oxide powder; 33.3% of high-purity gallium oxide powder; 33.3% of high-purity zinc oxide powder; The weighed amount of the polyvinyl alcohol of binder is 0.8%.

Step 2: Mix the weighed indium oxide, gallium oxide, zinc oxide powder and ammonium polyacrylate, and then put it into a 2L zirconia ball mill jar, and place three different specifications of zirconia balls in the ball mill jar in advance; Then weigh pure water according to 60% of the total mass of indium oxide, gallium oxide, zinc oxide powder and ammonium polyacrylate, and add it into the zirconia ball mill jar. The specifications of the grinding balls are φ5mm, φ3mm and φ1mm respectively. The quality of the grinding balls of the three specifications remains the same; the ball-to-material ratio is kept at 3:1, and the maximum charging volume does not exceed 1.5L.

Step 3: Use a high-energy planetary ball mill to fully mix and ball mill the mixture. The speed of the ball mill is 250r/min, and the ball milling time needs to reach 48 hours. After the ball milling is completed, add polyvinyl alcohol into the ball mill jar, and continue ball milling for 1 hour, so that the binder is evenly mixed into the slurry.

Step 4: The mixed slurry after ball milling is taken out from the ball mill tank, and processed by spray granulation method to obtain spherical mixed powder. The drying temperature in the spray granulation process is controlled at 210°C.

Step 5: Take the mixed powder and fill it in a flexible mold. As shown in Figure 4, the flexible mold comprises a cylindrical metal core, a circular tubular outer sheath is arranged outside the metal mold core, a powder cavity is formed between the metal mold core and the outer sheath, and the top and bottom of the outer sheath are provided with The upper and lower cover plates match the inner diameter of the outer sheath. Assemble the metal core, outer casing and upper and lower cover plates before filling. The mixed powder needs to be vibrated during the filling process, so that the powder can be evenly filled into the mold, and the tap density of the powder is 1.79g/cm ³ . Assemble the top cover after the filling is complete and fully wrap the mold with a film release material. After the coating is completed, the powder is pressed into shape by cold isostatic pressing, and the pressure is kept. The pressure of cold isostatic pressing is 250 MPa, and the holding time is 10 minutes.

Step 6: Carefully remove the isolation film outside the mold to prevent the liquid pressure medium in the isostatic press from seeping into the mold. And successively remove the upper cover plate and the outer cover of the mold, and take out the tubular target blank from the flexible mold.

Step 7: Sinter the InGaZn tubular target green body using a three-stage sintering process.

The first stage: In order to completely degrease the green body, the temperature needs to be raised slowly within the range from room temperature to 600°C, and the heating rate is controlled at 1°C/min, and air is introduced at the beginning of the temperature rise, and the air flow rate is 15L/min.

The second stage: In order to quickly achieve sintering and densification of the target, increase the heating rate when the temperature rises to 600°C, and control the heating rate at 5°C/min until the temperature rises to 1500°C, and keep it at this temperature for 10 minutes. Switch the air to oxygen at the beginning of the phase and reduce the gas flow to 12 L/min.

The third stage: In order to prevent the grain size of the target material from being coarse, the temperature is rapidly lowered to 1350°C after a short time at the highest temperature point, and the cooling rate is 10°C/min. After 15 hours of heat preservation, stop heating and lower the temperature at a rate of 1°C/min. When the temperature drops below 900°C, turn off the oxygen and cool to room temperature with the furnace. The fine-grained and highly dense InGaZnO crack-free tubular target can be obtained.

The relative density of the indium gallium zinc oxide tubular target prepared in this example is 99.71%, which has a relatively high relative density, and its macroscopic photo is shown in Figure 1.

XRD phase analysis was performed on the IGZO target prepared in this example, as shown in FIG. 2 , the XRD result analysis showed that only a single In ₂ Ga ₂ ZnO ₇ phase existed, and no impurity phase existed.

Fig. 3 is a microstructure diagram of the indium gallium zinc oxide tubular target prepared in this embodiment. The grains are regular polygons, the inter-grains are densely bonded, no obvious pores exist, and the grains are fine and uniform, with an average grain size of about 8.0 μm. It can be seen that a fine-grained, highly dense, and crack-free indium gallium zinc oxide tubular target was obtained.

Embodiment two

A method for preparing a tubular indium gallium zinc oxide (In ₂ Ga ₂ ZnO ₇ ) fine-grained, high-density, crack-free target, comprising the following steps:

Step 1: Select high-purity indium oxide, gallium oxide, and zinc oxide powder as raw materials, use ammonium polyacrylate as dispersant, and polyvinyl alcohol as binder. Proportion by mole percentage: 33.3% of high-purity indium oxide powder; 33.3% of high-purity gallium oxide powder; 33.3% of high-purity zinc oxide powder; The weighed amount of the polyvinyl alcohol of binder is 0.8%.

Step 2: Mix the weighed indium oxide, gallium oxide, zinc oxide powder and ammonium polyacrylate, and then put it into a 2L zirconia ball mill jar, and place three different specifications of zirconia balls in the ball mill jar in advance; Then weigh pure water according to 60% of the total mass of indium oxide, gallium oxide, zinc oxide powder and ammonium polyacrylate, and add it into the zirconia ball mill jar. The specifications of the grinding balls are φ5mm, φ3mm and φ1mm respectively. The quality of the grinding balls of the three specifications remains the same; the ball-to-material ratio is kept at 3:1, and the maximum charging volume does not exceed 1.5L.

Step 3: Use a high-energy planetary ball mill to fully mix and ball mill the mixture. The speed of the ball mill is 250r/min, and the ball milling time needs to reach 48 hours. After the ball milling is completed, add polyvinyl alcohol into the ball mill jar, and continue ball milling for 1 hour, so that the binder is evenly mixed into the slurry.

Step 4: The mixed slurry after ball milling is taken out from the ball mill tank, and processed by spray granulation method to obtain spherical mixed powder. The drying temperature in the spray granulation process is controlled at 210°C.

Step 5: Take the mixed powder and fill it in a flexible mold. The mixed powder needs to be vibrated during the filling process, so that the powder can be evenly filled into the mold, and the tap density of the powder is 1.81g/cm ³ . Assemble the top cover after filling is complete and fully wrap the mold with a film release material. After the coating is completed, the powder is pressed into shape by cold isostatic pressing, and the pressure is kept. The pressure of cold isostatic pressing is 250 MPa, and the holding time is 10 minutes.

Step 6: Carefully remove the isolation film outside the mold to prevent the liquid pressure medium in the isostatic press from seeping into the mold. And successively remove the upper cover plate and the outer cover of the mold, and take out the tubular target blank from the flexible mold.

Step 7: Sinter the InGaZn tubular target green body using a three-stage sintering process.

The first stage: In order to completely degrease the green body, the temperature needs to be raised slowly within the range from room temperature to 600°C, and the heating rate is controlled at 1°C/min, and air is introduced at the beginning of the temperature rise, and the air flow rate is 15L/min.

The second stage: In order to quickly achieve sintering and densification of the target, increase the heating rate when the temperature rises to 600°C, and control the heating rate at 5°C/min until the temperature rises to 1500°C, and keep it at this temperature for 10 minutes. Switch the air to oxygen at the beginning of the phase and reduce the gas flow to 12 L/min.

The third stage: In order to prevent the coarse grains of the target material, the temperature is rapidly lowered to 1300°C after a short time at the highest temperature point, and the cooling rate is 10°C/min. After 15 hours of heat preservation, stop heating and lower the temperature at a rate of 1°C/min. When the temperature drops below 900°C, turn off the oxygen and cool to room temperature with the furnace. The fine-grained and highly dense InGaZnO crack-free tubular target can be obtained.

The relative density of the indium gallium zinc oxide tubular target prepared in this example is 99.32%. XRD phase analysis was performed on the IGZO target prepared in this example, and the XRD result analysis showed that only a single In ₂ Ga ₂ ZnO ₇ phase existed, and no impurity phase existed. Moreover, the crystal grains of the IGZO target material in this embodiment are regular polygons, and the bonding between the grains is dense, and there are a small number of pores in the grain gaps, and the grains are fine and uniform, with an average grain size of about 7.6 μm. In general, this embodiment obtains a fine-grained, highly dense, and crack-free InGaZn tubular target.

Embodiment three

A method for preparing a tubular indium gallium zinc oxide (In ₂ Ga ₂ ZnO ₇ ) fine-grained, high-density, crack-free target, comprising the following steps:

Step 1: Select high-purity indium oxide, gallium oxide, and zinc oxide powder as raw materials, use ammonium polyacrylate as dispersant, and polyvinyl alcohol as binder. Proportion by mole percentage: 33.3% of high-purity indium oxide powder; 33.3% of high-purity gallium oxide powder; 33.3% of high-purity zinc oxide powder; The weighed amount of the polyvinyl alcohol of binder is 0.8%.

Step 2: Mix the weighed indium oxide, gallium oxide, zinc oxide powder and ammonium polyacrylate, and then put it into a 2L zirconia ball mill jar, and place three different specifications of zirconia balls in the ball mill jar in advance; Then weigh pure water according to 60% of the total mass of indium oxide, gallium oxide, zinc oxide powder and ammonium polyacrylate, and add it into the zirconia ball mill jar. The specifications of the grinding balls are φ5mm, φ3mm and φ1mm respectively. The quality of the grinding balls of the three specifications remains the same; the ball-to-material ratio is kept at 3:1, and the maximum charging volume does not exceed 1.5L.

Step 3: Use a high-energy planetary ball mill to fully mix and ball-mill the mixture (indium oxide, gallium oxide, zinc oxide powder, ammonium polyacrylate and water). The ball mill speed is 250r/min, and the ball milling time needs to reach 48 hours. After the ball milling is completed, add polyvinyl alcohol into the ball mill jar, and continue ball milling for 1 hour, so that the binder is evenly mixed into the slurry.

Step 4: The mixed slurry after ball milling is taken out from the ball mill tank, and processed by spray granulation method to obtain spherical mixed powder. The drying temperature in the spray granulation process needs to be controlled at 210°C.

Step 5: Take the mixed powder and fill it in a special flexible mold. During the filling process, vibration treatment is required to make the powder evenly fill the mold, and the tap density of the powder is 1.78g/cm ³ . Assemble the top cover after filling is complete and fully wrap the mold with a film release material. After the coating is completed, the powder is pressed into shape by cold isostatic pressing, and the pressure is kept. The pressure of cold isostatic pressing is 250 MPa, and the holding time is 10 minutes.

Step 6: Carefully remove the aluminum-silicon foil wrapping container and isolation film outside the mold to prevent the liquid pressure medium in the isostatic press from penetrating into the mold. And successively remove the upper cover plate and the outer cover of the mold, and take out the tubular target blank from the flexible mold.

Step 7: Sinter the InGaZn tubular target green body using a three-stage sintering process.

The first stage: In order to completely degrease the green body, the temperature needs to be raised slowly within the range from room temperature to 600°C, and the heating rate is controlled at 1°C/min, and air is introduced at the beginning of the temperature rise, and the air flow rate is 15L/min.

The second stage: In order to quickly achieve sintering and densification of the target, increase the heating rate when the temperature rises to 600°C, and control the heating rate at 5°C/min until the temperature rises to 1450°C, and keep at this temperature for 10 minutes. Switch the air to oxygen at the beginning of the phase and reduce the gas flow to 12 L/min.

The third stage: In order to prevent the coarse grains of the target material, the temperature is rapidly lowered to 1300°C after a short time at the highest temperature point, and the cooling rate is 10°C/min. After 15 hours of heat preservation, stop heating and lower the temperature at a rate of 1°C/min. When the temperature drops below 900°C, turn off the oxygen and cool to room temperature with the furnace. The fine-grained and highly dense InGaZnO crack-free tubular target can be obtained.

The relative density of the indium gallium zinc oxide tubular target prepared in this example is 99.16%. XRD phase analysis was performed on the IGZO target prepared in this example, and the XRD result analysis showed that only a single In ₂ Ga ₂ ZnO ₇ phase existed, and no impurity phase existed. Moreover, the crystal grains of the IGZO target material in this embodiment are regular polygons, and the bonding between each crystal grain is relatively dense, and there are a small number of pores in the gap between the grains, and the grains are fine and uniform, with an average grain size of about 6.3 μm. In general, this embodiment obtains a fine-grained, highly dense, and crack-free InGaZn tubular target.

comparative example

In this embodiment, the mixed powder and slurry are processed according to the method of Embodiment 1, that is, steps 1 to 4 of this embodiment are the same as in Embodiment 1.

Step 5: Use a flexible mold to shape the granulated powder.

After the mixed powder is evenly filled in the flexible mold, it is subjected to vibration treatment, and the tap density of the powder is 1.79g/cm ³ . Cold isostatic pressing is used to press and form the powder, and the pressure is kept. The cold isostatic pressing pressure is 250 MPa, and the holding time is 10 minutes.

Step 6: Place the indium gallium zinc oxide tubular target blank in a degreasing furnace for degreasing treatment, the degreasing temperature is 600°C, the degreasing time is 10 hours, and an air atmosphere with a gas flow rate of 15L/min is introduced. After the degreasing is completed, the furnace is cooled to room temperature, and then it is moved into a muffle furnace for sintering. The heating rate is 5°C/min, the sintering temperature is 1500°C, the temperature is kept at this temperature for 6 hours, and an oxygen atmosphere with a gas flow rate of 12L/min is introduced. After the heat preservation is completed, stop heating and lower the temperature at a rate of 1°C/min. When the temperature drops below 900°C, turn off the oxygen and cool down to room temperature with the furnace.

The relative density of the indium gallium zinc oxide tubular target prepared in this example is 98.06%, which is relatively low. XRD phase analysis was performed on the IGZO target prepared in this example, and the XRD result analysis showed that it was an In ₂ Ga ₂ ZnO ₇ phase. The grain size of the IGZO target in this example is relatively coarse, with an average grain size of about 14.7 μm, and IGZO tubular targets with high density (>99%) and fine grains (<10 μm) were not obtained at the same time. The tubular target prepared in this embodiment will have certain influence on the sputtering process and the performance of the film.

The above-described embodiments are only preferred embodiments of the present invention, and do not limit the scope of the present invention. Therefore, all equivalent changes or modifications made according to the structure, features and principles described in the patent scope of the present invention are valid. Should be included in the patent scope of the present invention.

Claims (10)

1. A method for preparing a tubular indium gallium zinc oxide (In ₂ Ga ₂ ZnO ₇ ) fine-grained, high-density, crack-free target, characterized by comprising the following steps: Step 1: Add water to the raw materials indium oxide powder, gallium oxide powder, zinc oxide powder, dispersant ammonium polyacrylate, and binder polyvinyl alcohol for ball milling to obtain a mixed slurry; Powder and zinc oxide powder are proportioned according to equal molar percentage; ammonium polyacrylate accounts for 0.5-2% of the total amount of raw materials; polyvinyl alcohol accounts for 0.5-2% of the total amount of raw materials; Step 2: Take out the mixed slurry after ball milling, and dry to obtain mixed powder; Step 3: Prepare the tubular target blank by cold isostatic pressing on the mixed powder; Step 4: Use a three-stage sintering process to sinter the tubular target blank, The first stage: Degrease the tubular target blank by raising the temperature to 600°C at room temperature, and control the heating rate at 0.5-1°C/min; The second stage: raise the temperature from 600°C to 1450-1550°C, control the heating rate at 2-5°C/min, and keep at this temperature for 10 minutes; The third stage: cool down to 1250-1350°C, the cooling rate is 5-10°C/min, stop heating after 12-18 hours of heat preservation and drop to room temperature, the cooling rate is 1-3°C/min. 2. The preparation method according to claim 1, characterized in that, in step 1, the raw material indium oxide powder, gallium oxide powder, zinc oxide powder, dispersant ammonium polyacrylate and water are ball milled to obtain a slurry; then add The binder polyvinyl alcohol is ball-milled and mixed to obtain a mixed slurry. 3. The preparation method according to claim 1, wherein in step 1, the particle sizes of the raw materials are: indium oxide 70-200 nm, purity 4N; gallium oxide 2-5 μm, purity 4N; zinc oxide 100-200 nm. 600nm, purity 4N. 4. The preparation method according to claim 2, characterized in that, the specific operation of ball milling to obtain the slurry is as follows: loading raw material indium oxide powder, gallium oxide powder, zinc oxide powder, and dispersant ammonium polyacrylate into a zirconia ball mill tank , and add pure water into the ball mill tank, the amount of pure water added is 60% of the total mass of the raw material indium oxide powder, gallium oxide powder, zinc oxide powder, and dispersant ammonium polyacrylate, and the specifications of the balls in the ball mill tank are φ5mm, φ3mm and φ1mm, the quality of the three specifications of grinding balls remains the same; keep the ball-to-material ratio at 3:1, and the maximum charging amount does not exceed 75% of the volume of the ball milling tank. 5. The preparation method according to claim 4, characterized in that, using a high-energy planetary ball mill to fully mix and ball-mill indium oxide powder, gallium oxide powder, zinc oxide powder, ammonium polyacrylate and water, the ball mill rotating speed is 150～250r /min, the ball milling time reaches more than 24 hours; then add polyvinyl alcohol to the slurry, and continue ball milling for 1 hour. 6 . The preparation method according to claim 1 , wherein in step 2, the mixed slurry is processed by spray granulation to obtain spherical mixed powder, and the drying temperature in the spray granulation process is controlled at 180-220° C. 7. The preparation method of a fine-grained high-density indium gallium zinc oxide non-cracking tubular target according to claim 1, characterized in that, in step 3, before cold isostatic pressing of the mixed powder, the powder is filled Put in the mold and vibrate, the tap density is 1.6-1.9g/cm ³ . 8. The preparation method according to claim 1, characterized in that, in step 3, the cold isostatic pressing pressure is 220-280 MPa, and the holding time is 5-15 minutes. 9. The preparation method according to claim 7, characterized in that, before the cold isostatic pressing, the mold is completely coated with a film isolation. 10. The preparation method according to claim 1, characterized in that, in step 4, air is fed into the first stage when the temperature rise begins, and the air flow rate is 15L/min; the second stage converts air into oxygen when the temperature rise begins , and reduce the gas flow to 12L/min; the third stage turns off the oxygen when the temperature drops below 900°C.

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