Submicron grain GTO sputtering target material and preparation method thereof
The submicron grain GTO sputtering targets are prepared by multi-stage ball milling and four-stage temperature-controlled sintering. The problems of uneven grains and unstable performance of targets in the prior art are solved, and the target preparation of high density and fine grains is achieved, and the performance and stability of TCO films are improved.
Patent Information
- Application Number
- CN202510447459.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-10
- Publication Date
- 2025-06-27
AI Technical Summary
During the preparation process of existing TCO films, the grain structure of the target material is uneven, resulting in impure film composition and unstable performance, and the sputtering power of high-density target materials is small, and porous target materials are prone to abnormal electric fields to increase the risk of poisoning.
The submicron grain GTO sputtering target was prepared by multi-stage ball milling and four-stage temperature controlled sintering. By optimizing the ball milling strength and sintering temperature, the grain size was controlled between 0.44 and 0.71 μm, and the relative density was 99.59 and 99.8%.
The density of the target material and fine grains are achieved, the risk of abnormal discharge is reduced, the composition purity and performance stability of the film are improved, the preparation process is simplified and energy consumption is reduced.
Smart Images
Figure CN120208660A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of sputtering targets, and particularly relates to a sub-micron grain GTO sputtering target and a preparation method thereof. Background Art
[0002] Transparent conductive oxide (TCO) is a new type of functional material with both conductive and light-transmitting properties. Due to its excellent properties such as narrow band gap, low resistivity, high visible light transmittance, and high reflectivity in the near-infrared spectral region, it shows great application potential in optoelectronic devices.
[0003] There are many methods for preparing TCO thin films. Among them, the magnetron sputtering method is widely used because of its low cost, easy large-scale manufacturing, and high deposition speed. The target is the core material for manufacturing TCO thin films by the magnetron sputtering method. Only a dense and fine-grained target can obtain a thin film with excellent optoelectronic properties. A highly dense target has a small sputtering power, a high film formation speed, and the resulting thin film is not easily cracked. A target with a porous structure is prone to abnormal electric fields during sputtering, which increases the risk of target poisoning; a target with a uniform and fine grain structure can ensure a higher composition purity of the prepared thin film. Therefore, the properties of the target have a decisive influence on the formation and performance of the thin film. Optimizing the preparation process and properties of the target is the key link to improving the performance of the thin film.
[0004] As a wide-bandgap semiconductor oxide, SnO2 presents a unique rutile structure, exhibits high transmittance and excellent conductivity in the visible spectral range, as well as good chemical, physical properties and thermal stability. It is considered a potential TCO candidate material. At the same time, this material is non-toxic, pollution-free, rich in resources and low in price, suitable for large-scale commercial production, so it shows important value in the fields of energy, environment, electronics, etc. Summary of the Invention
[0005] In view of this, on the one hand, some embodiments disclose a preparation method of a sub-micron grain GTO sputtering target, including the steps of:
[0006] S1. Tin oxide as the main oxide, gallium oxide as the doping oxide, a dispersant and water are ball-milled and mixed in a set ratio to obtain a mixed raw material;
[0007] S2. A binder is added to the mixed raw material and further ball-milled and mixed to obtain a raw material slurry;
[0008] S3. The raw material slurry is granulated and formed into a mixed raw material powder;
[0009] S4. The mixed raw material powder is pressed into a shape under a first pressure to obtain a primary GTO target green body;
[0010] S5. The primary GTO target green body is pressed into shape under a second pressure to obtain a shaped GTO target green body; wherein, the second pressure is greater than the first pressure.
[0011] S6. The shaped GTO target green body is subjected to multi-step sintering in a pressureless oxygen atmosphere to obtain a sub-micron grain GTO sputtering target; wherein, the multi-step sintering includes:
[0012] Heating to a first sintering temperature for the first step of sintering, the first sintering temperature is 700 - 800 °C, the heating rate is 1 - 2 °C / min, and the holding time is 4 - 7 h;
[0013] Heating from the first sintering temperature to a second sintering temperature for the second step of sintering, the second sintering temperature is 1200 - 1400 °C, the heating rate is 2 - 5 °C / min, and the holding time is 10 - 40 min;
[0014] Cooling from the second sintering temperature to a third sintering temperature for the third step of sintering, the third sintering temperature is 1100 - 1300 °C, the cooling rate is 10 - 15 °C / min, and the holding time is set to 10 - 25 h;
[0015] Cooling from the third sintering temperature to a fourth sintering temperature for the fourth step of sintering, the fourth sintering temperature is 400 - 500 °C, the cooling rate is 2 - 5 °C / min, and keep warm for 1 - 3 h;
[0016] After the sintering process is completed, it is naturally cooled to room temperature.
[0017] Furthermore, in the preparation method of the sub-micron grain GTO sputtering target disclosed in some embodiments, in step S1, the mass ratio of the main oxide to the doped oxide is 90 - 99:10 - 1. In the mixed raw materials, the mass content of the dispersant is 0.5 - 1.5%, and the mass content of water is 60 - 70%.
[0018] In the preparation method of the sub-micron grain GTO sputtering target disclosed in some embodiments, the ball milling and mixing process in step S1 is controlled in stages, the ball-to-material ratio is 3:1, and the total ball milling time is 25 - 50 h; specifically including:
[0019] The first stage: the rotation speed of the ball mill is 150 - 230 r / min, and the ball milling time is 8 - 15 h;
[0020] The second stage: the rotation speed of the ball mill is 250 - 350 r / min, and the ball milling time is 12 - 25 h;
[0021] The third stage: the rotation speed of the ball mill is 180 - 250 r / min, and the ball milling time is 5 - 10 h.
[0022] The preparation method of the submicron-grained GTO sputtering target disclosed in some embodiments, in step S2, the addition amount of the binder is 0.5-1.5% of the mass of the mixed raw materials, the ball milling and mixing process is controlled in stages, and the ball-to-material ratio is 3:1; including:
[0023] The first stage: the rotational speed of the ball mill is 160-220 r / min, and the ball milling time is 0.5-3 h;
[0024] The second stage: the rotational speed of the ball mill is 250-350 r / min, and the ball milling time is 0.5-2 h.
[0025] The preparation method of the submicron-grained GTO sputtering target disclosed in some embodiments, in step S3, the raw material slurry is spray granulated in a spray granulator, the granulation temperature is 190-220 °C, the feeding rate is 5-15 ml / min, and the centrifuge frequency is 30-50 Hz.
[0026] The preparation method of the submicron-grained GTO sputtering target disclosed in some embodiments, in step S4, the first pressure is 30-50 Mpa, and the pressure holding time is 2-5 min.
[0027] The preparation method of the submicron-grained GTO sputtering target disclosed in some embodiments, in step S5, the second pressure is 100-250 MPa, and the pressure holding time is 5-30 min.
[0028] On the other hand, some embodiments disclose a submicron-grained GTO sputtering target obtained by the preparation method of the submicron-grained GTO sputtering target disclosed in the embodiments of the present invention. The grain size of the submicron-grained GTO sputtering target is 0.44-0.71 μm, and the relative density is 99.59-99.8%.
[0029] The preparation method of the submicron-grained GTO sputtering target disclosed in the embodiments of the present invention obtains a submicron-grained GTO sputtering target with a grain size of 0.44-0.71 μm and a relative density of 99.59-99.8%, which can be used to prepare a TCO film with excellent performance. BRIEF DESCRIPTION OF THE DRAWINGS
[0030] Figure 1 is the XRD pattern of the GTO target in Example 1;
[0031] Figure 2 is the SEM image of the GTO target in Example 1;
[0032] Figure 3 is the SEM image of the GTO target in Comparative Example 1;
[0033] Figure 4 is the expansion curve of different materials in Example 1. DETAILED DESCRIPTION OF THE INVENTION
[0034] As used herein, the term "embodiment" in the context of "exemplary", any embodiment described as such need not be construed as superior or better than other embodiments. For performance index testing in the embodiments of the present invention, unless otherwise specified, conventional test methods in the art are adopted. It should be understood that the terms described in the embodiments of the present invention are merely for describing particular embodiments and are not intended to limit the content disclosed in the embodiments of the present invention.
[0035] Unless otherwise stated, the technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the embodiments of the present invention pertain; other test methods and technical means not specifically noted in the embodiments of the present invention refer to the experimental methods and technical means commonly adopted by those of ordinary skill in the art.
[0036] The terms "substantially" and "about" as used herein are used to describe minor fluctuations. For example, they can refer to less than or equal to ±5%, such as less than or equal to ±2%, such as less than or equal to ±1%, such as less than or equal to ±0.5%, such as less than or equal to ±0.2%, such as less than or equal to ±0.1%, such as less than or equal to ±0.05%. Numerical data presented or expressed in a range format herein is used only for convenience and brevity and should therefore be interpreted flexibly to include not only the values explicitly recited as the bounds of the range but also all individual values or sub-ranges subsumed within that range. For example, a numerical range of "1 to 5%" should be interpreted to include not only the explicitly recited values of 1% to 5% but also individual values and sub-ranges within the indicated range. Thus, within this numerical range, individual values such as 2%, 3.5%, and 4% are included, and sub-ranges such as 1% to 3%, 2% to 4%, and 3% to 5% etc. This principle also applies to ranges that list only one value. Additionally, such an interpretation applies regardless of the width of the range or the characteristics described.
[0037] In this document, including in the claims, conjunctions such as "comprising", "including", "carrying", "having", "containing", "involving", "accommodating", etc. are understood to be open-ended, that is, meaning "including but not limited to". Only the conjunctions "consisting of" and "composed of" are closed conjunctions.
[0038] To better illustrate the content of the present invention, numerous specific details are given in the following specific embodiments. Those skilled in the art should understand that the present invention can be implemented without some of these specific details. In the embodiments, some methods, means, instruments, equipment, etc. well-known to those skilled in the art are not described in detail so as to highlight the gist of the present invention.
[0039] On the premise of no conflict, the technical features disclosed in the embodiments of the present invention can be arbitrarily combined, and the obtained technical solutions belong to the content disclosed in the embodiments of the present invention.
[0040] In some embodiments, the method for preparing a sub-micron grain GTO sputtering target includes the steps of:
[0041] S1. Tin oxide as the main oxide, gallium oxide as the doping oxide, a dispersant and water are ball-milled and mixed in a set ratio to obtain a mixed raw material; generally, multi-stage ball milling can be performed during the powder processing, and the particle size distribution of the powder is controlled by optimizing the ball milling intensity at different stages, so as to obtain uniformly mixed and finely dispersed gallium oxide-doped tin oxide GTO powder;
[0042] S2. A binder is added to the mixed raw material and further ball-milled and mixed to obtain a raw material slurry;
[0043] S3. The raw material slurry is granulated and formed into a mixed raw material powder;
[0044] S4. The mixed raw material powder is pressed into a primary GTO target green body under a first pressure;
[0045] S5. The primary GTO target green body is pressed into a formed GTO target green body under a second pressure; wherein, the second pressure is greater than the first pressure;
[0046] S6. The formed GTO target green body is sintered in a pressureless oxygen atmosphere in multiple steps to obtain a sub-micron grain GTO sputtering target; generally, high-temperature short-time sintering is first performed during the multi-step sintering process to promote the densification of the target, and then low-temperature long-time sintering and heat preservation can inhibit grain growth, inhibit grain boundary migration and promote grain boundary diffusion at the same time, control the grain size within the sub-micron level while ensuring the densification of the target, and further reducing the temperature for sintering and heat preservation can further stabilize the structure and reduce defects; the target with a smaller grain size has a relatively uniform and dense etching morphology during magnetron sputtering, and atoms are more easily bombarded out of the target, obtaining a TCO film with excellent performance;
[0047] In some embodiments, the multi-step sintering includes:
[0048] Heating to a first sintering temperature for the first-step sintering, the first sintering temperature is 700 - 800 °C, the heating rate is 1 - 2 °C / min, and the heat preservation time is 4 - 7 h;
[0049] Heating from the first sintering temperature to a second sintering temperature for the second-step sintering, the second sintering temperature is 1200 - 1400 °C, the heating rate is 2 - 5 °C / min, and the heat preservation time is 10 - 40 min;
[0050] Cool down from the second sintering temperature to the third sintering temperature for the third-step sintering. The third sintering temperature is 1100 - 1300 °C, the cooling rate is 10 - 15 °C / min, and the holding time is set to 10 - 25 h;
[0051] Cool down from the third sintering temperature to the fourth sintering temperature for the fourth-step sintering. The fourth sintering temperature is 400 - 500 °C, the cooling rate is 2 - 5 °C / min, and hold for 1 - 3 h;
[0052] The sintering process ends, and it is naturally cooled to room temperature.
[0053] Furthermore, in the preparation method of the submicron-grained GTO sputtering target disclosed in some embodiments, in step S1, the mass ratio of the main oxide to the doping oxide is 90 - 99:10 - 1. In the mixed raw materials, the mass content of the dispersant is 0.5 - 1.5%, and the mass content of water is 60 - 70%.
[0054] In the preparation method of the submicron-grained GTO sputtering target disclosed in some embodiments, the ball milling and mixing process in step S1 is controlled in stages. The ball-to-material ratio is 3:1, and the total ball milling time is 25 - 50 h. In some embodiments, the ball milling process is divided into three stages. Among them, the rotational speed of the ball mill in the second stage is greater than that in the first stage, and the rotational speed of the ball mill in the third stage is less than that in the second stage.
[0055] In some embodiments, the three-stage ball milling process specifically includes: the first stage: the rotational speed of the ball mill is 150 - 230 r / min, and the ball milling time is 8 - 15 h; the second stage: the rotational speed of the ball mill is 250 - 350 r / min, and the ball milling time is 12 - 25 h; the third stage: the rotational speed of the ball mill is 180 - 250 r / min, and the ball milling time is 5 - 10 h.
[0056] In the preparation method of the submicron-grained GTO sputtering target disclosed in some embodiments, in step S2, the addition amount of the binder is 0.5 - 1.5% of the mass of the mixed raw materials, and the ball milling and mixing process is controlled in stages. The ball-to-material ratio is 3:1. In some embodiments, the ball milling process in step S2 is divided into two stages. Among them, the rotational speed of the ball mill in the second stage is greater than that in the first stage. In some embodiments, the two-stage ball milling in step S2 specifically includes: the first stage: the rotational speed of the ball mill is 160 - 220 r / min, and the ball milling time is 0.5 - 3 h; the second stage: the rotational speed of the ball mill is 250 - 350 r / min, and the ball milling time is 0.5 - 2 h.
[0057] In the preparation method of the submicron-grained GTO sputtering target disclosed in some embodiments, in step S3, the raw material slurry is spray granulated in a spray granulator. The granulation temperature is 190 - 220 °C, the feeding rate is 5 - 15 ml / min, and the centrifuge frequency is 30 - 50 Hz.
[0058] In the preparation method of the submicron-grained GTO sputtering target disclosed in some embodiments, in step S4, the first pressure is 30 to 50 Mpa, and the pressure holding time is 2 to 5 min.
[0059] In the preparation method of the submicron-grained GTO sputtering target disclosed in some embodiments, in step S5, the second pressure is 100 to 250 MPa, and the pressure holding time is 5 to 30 min.
[0060] On the other hand, some embodiments disclose a submicron-grained GTO sputtering target obtained by the preparation method of the submicron-grained GTO sputtering target disclosed in the embodiments of the present invention. The grain size of the submicron-grained GTO sputtering target is 0.44 to 0.71 μm, and the relative density is 99.59 to 99.8%.
[0061] The preparation method of the submicron-grained GTO sputtering target disclosed in the embodiments of the present invention uses three-stage ball milling for raw material mixing and ball milling, combines different combinations of rotation speed and time, and can significantly refine the grains. In the sintering stage, four-stage temperature-controlled sintering is carried out, which effectively inhibits grain growth. Among them, degreasing is carried out at a low temperature of 700 to 800 °C, then short-time densification is carried out at a high temperature of 1340 to 1400 °C for 10 to 40 min, and then quickly cooled to the third temperature of 1100 to 1300 °C for long-time heat preservation for 10 to 25 h, which is beneficial to stabilizing the grain boundaries; finally, low-temperature annealing is carried out at the fourth temperature of 400 to 500 °C to reduce defects. In the obtained GTO sputtering target, the grain size can reach the submicron level, between 0.44 and 0.71 μm, and the relative density is 99.59 to 99.8%. The submicron grains make the etching morphology more uniform during target sputtering and reduce the risk of abnormal discharge. The four-stage temperature-controlled sintering effectively inhibits grain growth, and the rapid high-temperature sintering and low-temperature long-time heat preservation processes cooperate with each other to effectively shorten the preparation cycle and reduce energy consumption.
[0062] The following further exemplarily illustrates the technical details in conjunction with the embodiments.
[0063] Example 1
[0064] In Example 1, the preparation method of the submicron-grained GTO sputtering target includes:
[0065] The main oxide SnO2, the doped oxide Ga2O3, the dispersant, and deionized water are mixed in a certain proportion and ball-milled to make the mixed powder evenly mixed to obtain the mixed raw material; among them, the mass ratio of SnO2 to Ga2O3 is 95:5; the mass of deionized water is 65% of the total mass of the mixed raw material, and the mass of the dispersant ammonium polyacrylate is 1% of the total mass of the mixed raw material; the ball-milling process is carried out in three stages with a ball-to-material ratio of 3:1 and a total time of 25 hours; among them, in the first stage, the ball mill rotates at a speed of 150 r / min and the ball-milling time is 8 h; in the second stage, the ball mill rotates at a speed of 250 r / min and the ball-milling time is 12 h; in the third stage, the ball mill rotates at a speed of 180 r / min and the ball-milling time is 5 h;
[0066] Polyvinyl alcohol is used as the binder, and 1% of the polyvinyl alcohol by mass of the mixed raw material is added to the mixed raw material and ball-milled for 1 h to obtain the mixed raw material slurry. The ball-milling includes: ball-milling at a speed of 160 r / min for 0.5 h, and then ball-milling at a speed of 250 r / min for 0.5 h, with a ball-to-material ratio of 3:1;
[0067] The obtained mixed raw material slurry is spray granulated by a spray granulator to obtain dry, spherical granulated powder of the mixed raw material with good fluidity; among them, the granulation temperature is 220 °C, the feeding rate is 12 ml / min, and the centrifuge frequency is 45 Hz;
[0068] The obtained spherical granulated powder of the mixed raw material is filled into an alloy steel mold and pressed into shape in a hydraulic press at a forming pressure of 45 MPa for a holding time of 3 min to obtain a primary GTO target green body;
[0069] The primary GTO target green body is completely coated with aluminum-silicon foil and vacuum-packaged by a vacuum packaging machine, and then further pressed in an isostatic press at a pressure of 220 MPa for 10 min to obtain a formed GTO target green body;
[0070] The obtained formed GTO target green body is placed in a sintering furnace for pressureless multi-step sintering in an oxygen atmosphere, including: heating to the first sintering temperature for the first step of sintering, the first sintering temperature is 700 °C, the heating rate is 2 °C / min, and the holding time is 5 h; heating from the first sintering temperature to the second sintering temperature for the second step of sintering, the second sintering temperature is 1340 °C, the heating rate is 3 °C / min, and the holding time is 10 min; cooling from the second sintering temperature to the third sintering temperature for the third step of sintering, the third sintering temperature is 1260 °C, the cooling rate is 15 °C / min, and the holding time is set to 15 h; cooling from the third sintering temperature to the fourth sintering temperature for the fourth step of sintering, the fourth sintering temperature is 400 °C, the cooling rate is 2 °C / min, and the holding time is 1 h; the sintering program ends and it is naturally cooled to room temperature.
[0071] The density of the GTO target obtained in Example 1 is 6.9101 g / cm 3 , the relative density is 99.59%, and the average grain size is 0.44 μm; Figure 1 This is the XRD pattern of the GTO target, showing a single tetragonal rutile structure SnO2 (PDF#41-1445). At the same time, the diffraction peaks of GaSnO3 are detected, indicating that the sample has formed a secondary phase compound of Sn and Ga; Figure 2 This is the SEM pattern of the GTO target obtained in Example 1. From Figure 2 it can be seen that the microstructure of the target is very dense, and the grain size is small, and the two phases are evenly distributed inside the target.
[0072] Figure 4 These are the thermal expansion curves of different materials; Figure 4 The thermal expansion curves of tin oxide and the GTO target at different heating rate temperatures are listed. The results show that the GTO sputtering target begins to have shrinkage above 1000 °C, has relatively good shrinkage above 1200 °C, and has good shrinkage after 1300 °C. Based on this, it can be determined that the second sintering temperature of Example 1 is above 1300 °C, which is 1340 °C.
[0073] Example 2
[0074] In Example 2, the preparation method of the sub-micron grain GTO sputtering target includes:
[0075] The main oxide SnO2, the doping oxide Ga2O3, the dispersant and deionized water are mixed in a certain proportion and ball-milled to make the mixed powder evenly mixed to obtain the mixed raw material; among them, the mass ratio of SnO2 to Ga2O3 is 96:4; the mass of deionized water is 68% of the total mass of the mixed raw material, and the mass of the dispersant ammonium polyacrylate is 1.3% of the total mass of the mixed raw material; the ball-milling process is carried out in three stages, the ball-to-material ratio is 3:1, and the total time is 38 hours; among them, in the first stage, the ball mill rotates at 200 r / min and the ball-milling time is 10 h; in the second stage, the ball mill rotates at 280 r / min and the ball-milling time is 20 h; in the third stage, the ball mill rotates at 220 r / min and the ball-milling time is 8 h;
[0076] Using polyvinyl alcohol as the binder, 1.1% of the mass of polyvinyl alcohol in the mixed raw material is added to the mixed raw material and ball-milled for another 2 h to obtain the mixed raw material slurry. The ball-milling includes: ball-milling at 200 r / min for 1 h, and then ball-milling at 280 r / min for 1 h, and the ball-to-material ratio is 3:1;
[0077] The obtained mixed raw material slurry is spray granulated by a spray granulator to obtain dry spherical granulated powder of the mixed raw materials with good fluidity; wherein, the granulation temperature is 200 °C, the feeding rate is 10 ml / min, and the centrifuge frequency is 40 Hz;
[0078] The obtained spherical granulated powder of the mixed raw materials is filled into an alloy steel mold and is pressed into shape in a hydraulic press at a forming pressure of 40 MPa for a holding time of 4 min to obtain a primary GTO target green body;
[0079] The primary GTO target green body is completely coated with aluminum-silicon foil and is subjected to vacuum packaging treatment using a vacuum packaging machine, and then is further pressed in an isostatic press at a pressure of 230 MPa for a holding time of 15 min to obtain a formed GTO target green body;
[0080] The obtained formed GTO target green body is placed in a sintering furnace for pressureless multi-step sintering in an oxygen atmosphere, including: heating to a first sintering temperature for the first step of sintering, the first sintering temperature is 750 °C, the heating rate is 2.5 °C / min, and the holding time is 6 h; heating from the first sintering temperature to a second sintering temperature for the second step of sintering, the second sintering temperature is 1390 °C, the heating rate is 3.5 °C / min, and the holding time is 10 min; cooling from the second sintering temperature to a third sintering temperature for the third step of sintering, the third sintering temperature is 1260 °C, the cooling rate is 12 °C / min, and the holding time is set to 15 h; cooling from the third sintering temperature to a fourth sintering temperature for the fourth step of sintering, the fourth sintering temperature is 450 °C, the cooling rate is 3 °C / min, and the holding time is 2 h; the sintering program ends and it is naturally cooled to room temperature.
[0081] The density of the GTO target obtained in this Example 2 is 6.9246 g / cm 3 and the relative density is 99.80%, and the average grain size is 0.57 μm.
[0082] Example 3
[0083] In Example 3, the preparation method of the submicron-grained GTO sputtering target includes:
[0084] The main oxide SnO2, the doped oxide Ga2O3, the dispersant and deionized water are mixed in a certain proportion and ball-milled to make the mixed powder uniformly mixed to obtain the mixed raw material; among them, the mass ratio of SnO2 to Ga2O3 is 97:3; the mass of deionized water is 70% of the total mass of the mixed raw material, and the mass of the dispersant ammonium polyacrylate is 1.5% of the total mass of the mixed raw material; the ball-milling process is carried out in three stages, the ball-to-material ratio is 3:1, and the total time is 50 hours; among them, in the first stage, the ball mill rotates at a speed of 230 r / min and the ball-milling time is 15 h; in the second stage, the ball mill rotates at a speed of 350 r / min and the ball-milling time is 10 h; in the third stage, the ball mill rotates at a speed of 250 r / min and the ball-milling time is 10 h;
[0085] Polyvinyl alcohol is used as the binder, and polyvinyl alcohol with a mass of 1.5% of the mixed raw material is added to the mixed raw material and ball-milled for another 3 h to obtain the mixed raw material slurry. The ball-milling includes: ball-milling at a speed of 220 r / min for 1.5 h, and then ball-milling at a speed of 350 r / min for 1.5 h, and the ball-to-material ratio is 3:1;
[0086] The obtained mixed raw material slurry is spray granulated by a spray granulator to obtain dry, spherical granulated powder of the mixed raw material with good fluidity; among them, the granulation temperature is 190 °C, the feeding rate is 11 ml / min, and the centrifuge frequency is 50 Hz;
[0087] The obtained spherical granulated powder of the mixed raw material is filled into an alloy steel mold and pressed into shape in a hydraulic press at a forming pressure of 42 MPa for a holding time of 5 min to obtain a primary GTO target green body;
[0088] The primary GTO target green body is completely coated with aluminum-silicon foil, and vacuum packaging treatment is carried out using a vacuum packaging machine, and then further pressed in an isostatic press, the pressure is 250 MPa, and the holding time is 20 min to obtain a formed GTO target green body;
[0089] The obtained formed GTO target green body is placed in a sintering furnace for pressureless multi-step sintering in an oxygen atmosphere, including: heating to the first sintering temperature for the first step of sintering, the first sintering temperature is 725 °C, the heating rate is 3 °C / min, and the holding time is 7 h; heating from the first sintering temperature to the second sintering temperature for the second step of sintering, the second sintering temperature is 1340 °C, the heating rate is 4 °C / min, and the holding time is 10 min; cooling from the second sintering temperature to the third sintering temperature for the third step of sintering, the third sintering temperature is 1280 °C, the cooling rate is 10 °C / min, and the holding time is set to 15 h; cooling from the third sintering temperature to the fourth sintering temperature for the fourth step of sintering, the fourth sintering temperature is 500 °C, the cooling rate is 4 °C / min, and the holding time is 3 h; the sintering program ends and it is naturally cooled to room temperature.
[0090] The density of the GTO target obtained in this Example 3 is 6.9191 g / cm 3 , the relative density is 99.72%, and the average grain size is 0.71 μm.
[0091] Comparative Example 1
[0092] In Comparative Example 1, the preparation method of the sub-micron grain GTO sputtering target includes:
[0093] The main oxide SnO2, the doping oxide Ga2O3, the dispersant and deionized water are mixed in a certain proportion and ball-milled to obtain a uniformly mixed mixed raw material; among them, the mass ratio of SnO2 to Ga2O3 is 95:5; the mass of deionized water is 65% of the total mass of the mixed raw material, and the mass of the dispersant ammonium polyacrylate is 1% of the total mass of the mixed raw material; during the ball-milling process, the ball-to-material ratio is 3:1, the rotation speed of the ball mill is 330 r / min, and the time is 48 hours;
[0094] Using polyvinyl alcohol as a binder, 1% of the mass of polyvinyl alcohol in the mixed raw material is added to the mixed raw material and ball-milled for another 1.5 h to obtain a mixed raw material slurry, the rotation speed of the ball mill is 330 r / min, and the ball-to-material ratio is 3:1;
[0095] The obtained mixed raw material slurry is spray granulated by a spray granulator to obtain dry, spherical granulated powder of the mixed raw material with good fluidity; before granulation, the defoaming agent n-octanol is added to the mixed raw material slurry to eliminate the bubbles therein; among them, the granulation temperature is 220 °C, the feeding rate is 12 ml / min, and the centrifuge frequency is 45 Hz;
[0096] The obtained spherical granulated powder of the mixed raw material is filled into an alloy steel mold and pressed into shape in a hydraulic press at a forming pressure of 45 MPa for a holding time of 3 min to obtain a primary GTO target green body;
[0097] The primary GTO target green body is completely coated with aluminum-silicon foil and vacuum packaged by a vacuum packaging machine, and then further pressed in an isostatic press, the pressure is 220 MPa, and the holding time is 10 min to obtain a formed GTO target green body;
[0098] The obtained formed GTO target green body is placed in a sintering furnace for pressureless multi-step sintering in an oxygen atmosphere, including: heating to a sintering temperature of 1600 °C for one-step sintering, the heating rate is 3 °C / min, and the holding time is 8 h; after the sintering program ends, it is naturally cooled to room temperature.
[0099] The density of the GTO target obtained in this Comparative Example 1 is 6.8032 g / cm 3 , the relative density is 98.05%, and the average grain size is 10.63 μm; Figure 3SEM image of the GTO target of Comparative Example 1, Figure 3 showing that the grain size inside the GTP target is large.
[0100] The preparation method of the sub-micron grain GTO sputtering target disclosed in the embodiments of the present invention results in a sub-micron grain GTO sputtering target with a grain size of 0.44 - 0.71 μm and a relative density of 99.59 - 99.8%, which can be used to prepare TCO films with excellent performance.
[0101] The technical solutions and technical details disclosed in the embodiments of the present invention are only exemplary illustrations of the inventive concept of the present invention, and do not constitute limitations on the technical solutions of the embodiments of the present invention. Any conventional changes, substitutions, or combinations made to the technical details disclosed in the embodiments of the present invention have the same inventive concept as the present invention and are within the protection scope of the claims of the present invention.
Claims
1. A method for preparing a submicron-grained GTO sputtering target, characterized in that: Includes steps: S1, the main oxide tin oxide, the doped oxide gallium oxide, the dispersant and water are ball-milled and mixed according to a set ratio to obtain a mixed raw material; S2, adding a binder to the mixed raw materials, further ball milling and mixing, to obtain a mixed raw material slurry; S3, granulating the mixed raw material slurry into mixed raw material powder; S4, pressing the mixed raw material powder under a first pressure to obtain a primary GTO target blank; S5, the primary GTO target material blank is pressed and formed under a second pressure to obtain a formed GTO target material blank; wherein the second pressure is greater than the first pressure; S6. The formed GTO target blank is subjected to multi-step sintering in a non-pressurized oxygen atmosphere to obtain a submicron-grained GTO sputtering target; wherein the multi-step sintering includes: The first sintering step is carried out by heating to a first sintering temperature, wherein the first sintering temperature is 700-800°C, the heating rate is 1-2°C / min, and the holding time is 4-7h; The second sintering step is performed by heating from the first sintering temperature to the second sintering temperature, wherein the second sintering temperature is 1200-1400° C., the heating rate is 2-5° C. / min, and the holding time is 10-40 min; The third sintering step is performed by cooling from the second sintering temperature to the third sintering temperature, wherein the third sintering temperature is 1100-1300°C, the cooling rate is 10-15°C / min, and the holding time is set to 10-25h; The fourth sintering step is performed by cooling from the third sintering temperature to the fourth sintering temperature, wherein the fourth sintering temperature is 400-500° C., the cooling rate is 2-5° C. / min, and the temperature is kept for 1-3 hours; After the sintering process is completed, the mixture is cooled naturally to room temperature.
2. The method for preparing a submicron-grained GTO sputtering target according to claim 1, characterized in that: In step S1, the mass ratio of the main oxide to the doped oxide is 90-99:10-1, and in the mixed raw materials, the mass content of the dispersant is 0.5-1.5%, and the mass content of water is 60-70%.
3. The method for preparing a submicron-grained GTO sputtering target according to claim 1, characterized in that: In step S1, the ball milling mixing process is controlled in stages, the ball-to-material ratio is 3:1, and the total ball milling time is 25 to 50 hours; comprising: The first stage: ball mill speed 150-230r / min, ball milling time 8-15h; The second stage: ball mill speed 250-350r / min, ball milling time 12-25h; The third stage: ball mill speed 180 ~ 250r / min, ball milling time 5 ~ 10h.
4. The method for preparing a submicron-grained GTO sputtering target according to claim 1, characterized in that: In step S2, the amount of binder added is 0.5-1.5% of the mass of the mixed raw materials, the ball milling mixing process is controlled in stages, and the ball-to-material ratio is 3:1; comprising: The first stage: ball mill speed 160 ~ 220r / min, ball milling time 0.5 ~ 3h; The second stage: ball mill speed 250~350r / min, ball milling time 0.5~2h.
5. The method for preparing a submicron-grained GTO sputtering target according to claim 1, characterized in that: In step S3, the raw material slurry is spray granulated in a spray granulator, the granulation temperature is 190-220° C., the feed rate is 5-15 ml / min, and the centrifuge frequency is 30-50 Hz.
6. The method for preparing a submicron-grained GTO sputtering target according to claim 1, characterized in that: In step S4, the first pressure is 30-50 MPa, and the pressure holding time is 2-5 min.
7. The method for preparing a submicron-grained GTO sputtering target according to claim 1, characterized in that: In step S5, the second pressure is 100-250 MPa, and the pressure holding time is 5-30 min.
8. Submicron-grained GTO sputtering target, characterized in that: The submicron-grain GTO sputtering target material obtained by the preparation method according to any one of claims 1 to 7 has a grain size of 0.44 to 0.71 μm and a relative density of 99.59 to 99.8%.