Tin dioxide target material, preparation method and application thereof

Abstract

The present invention provides a tin dioxide target material and its preparation method and application, which relates to the field of semiconductors. The preparation method of the tin dioxide target material comprises the following steps: firstly pressurizing the mixed powder under the pressure of 50-1500 MPa for 5-30 minutes until the mixed powder is pressed into shape; the mixed powder comprises SnO2 powder and M x O y The powder comprises an element M selected from the group consisting of Ta, Sb, Nb, W, Mo, and V, and x and y are integers ranging from 1 to 5. The SnO2 powder accounts for 80% to 99.9% of the mass of the mixed powder. The method can press the mixed powder into a dense tin dioxide target without adding a binder, thereby improving the purity of the target and thereby enhancing the electrical and optical properties of the conductive film.

Description

Technical Field

[0001] The present application relates to the field of semiconductors, and in particular to a tin dioxide target material and a preparation method and application thereof. Background Art

[0002] Compared to the transparent conductive material indium oxide, metallic tin is cheap and readily available, and tin oxide is relatively stable in reducing atmospheres and high-humidity air environments, making it more suitable for the preparation of transparent conductive films. Transparent conductive oxide films based on tin oxide can be used in technical fields such as solar cells, touch screen liquid crystal displays, thin film transistors, organic and inorganic semiconductor lasers, and thermal insulation and energy-saving glass. In industry, physical vapor deposition (PVD) methods such as magnetron sputtering (MS), reactive plasma deposition (RPD), and ion beam sputtering (IS) are generally used to prepare tin oxide transparent conductive oxide films.

[0003] Currently, when PVD is used to produce tin oxide-based transparent conductive oxide films, a target is typically used to promote the formation of the transparent conductive oxide film. This target is generally composed of tin dioxide powder mixed with an organic binder and a dopant (such as a doped metal oxide). While the use of an organic binder can improve the density of the target, it also reduces its purity, resulting in a high level of impurities in the resulting tin dioxide conductive film. Summary of the Invention

[0004] The embodiment of the present application provides a tin dioxide target material and a preparation method thereof. The tin dioxide target material prepared by the preparation method has high purity. When the tin dioxide target material is used to prepare a conductive film, the impurity content in the conductive film can be reduced.

[0005] In the first aspect, the embodiment of the present application provides a method for preparing a tin dioxide target, which comprises the following steps: firstly pressurizing the mixed powder under a pressure of 50 to 1500 MPa for 5 to 30 minutes until the mixed powder is pressed into a shape; the mixed powder comprises SnO2 powder and M x O y The powder comprises the element M being at least one of Ta, Sb, Nb, W, Mo and V, and x and y being any integer between 1 and 5; the mass of the SnO2 powder accounts for 80% to 99.9% of the mass of the mixed powder.

[0006] Currently, during press molding, in order to ensure the density of the target material, it is usually necessary to add a binder and press under relatively low pressure conditions (usually less than 50MPa). In the above technical solution, the inventors found that by adjusting the pressure to 50-1500Mpa and the pressing time to 5-30 minutes during press molding, the mixed powder can be pressed into a tin dioxide target material without adding a binder, and the density of the formed tin dioxide target material will not be reduced. In addition, since no binder is added, no additional impurities are introduced into the mixed powder, which can help improve the purity of the target material, thereby improving the electrical and optical properties of the conductive film.

[0007] In a possible implementation, in the pressing step, the pressure is 500 to 1500 MPa, and the pressing time is 15 to 30 minutes.

[0008] In a possible implementation, the mixed powder is prepared by the following steps: grinding and / or pre-sintering SnO2 powder in an oxidant, and then mixing with M x O y Powder mixing; optionally, the oxidant includes at least one of H2O2, O2, O3.

[0009] The inventors also discovered that SnO phases are prevalent in existing SnO2 powders. Using untreated SnO2 powder to prepare targets negatively impacts the optical transmittance and conductivity of metal-doped tin oxide transparent conductive films. Even when SnO2 thin films are deposited in an O2 atmosphere via PVD, the characteristics of PVD still result in a significant amount of SnO phase when deposited on the surface of targets made from untreated SnO2 powder.

[0010] In the above technical solution, grinding and / or pre-calcining the SnO2 powder in an oxidant before forming the mixed powder effectively eliminates the SnO phase in the SnO2, thereby preventing the negative impact of the subsequent tin dioxide target material made from the mixed powder on the metal-doped tin oxide transparent conductive film, significantly improving the film's photoelectric performance and stability. Oxidants such as H2O2, O2, and O3 are easily removed and are unlikely to remain in the SnO2 powder, which helps to improve the purity of the tin dioxide target material.

[0011] In a possible implementation, before the step of pressing the mixed powder into a shape, the step of ball milling the mixed powder is further included. The rotation speed during ball milling is 100 to 800 rpm, and the ball milling time is 3 to 20 min.

[0012] In the above technical solution, the ball milling step can make the tin dioxide powder and M x O y The powder undergoes sufficient solid phase reaction to make Mx O y The M element in the powder can enter the tin dioxide lattice as much as possible to replace Sn, thereby making the prepared target material more uniform and dense.

[0013] In one possible implementation, after the step of ball milling the mixed powder using a ball mill, the step of preheating the mixed powder is also included, with the preheating time being 1000 to 3000 minutes, the preheating temperature being 700 to 1400°C, and the heating rate during preheating being 1 to 10°C / min.

[0014] In the above technical solution, the preheating step can make the tin dioxide powder and M x O y The powder undergoes sufficient solid phase reaction to make M x O y The M element in the powder can enter the tin dioxide lattice as much as possible to replace Sn, thereby making the prepared target material more uniform and dense.

[0015] In a possible implementation, after the step of preheating the mixed powder, the method further includes a step of drying the mixed powder, with the drying temperature being 70 to 120° C. and the drying time being 50 to 100 minutes.

[0016] In a possible implementation, the particle size of the SnO2 powder is 20 to 500 nm; and / or, M x O y The particle size of the powder is 20 to 500 nm.

[0017] In one possible implementation, after the step of pressing the mixed powder into shape, a sintering step is also included; optionally, in the sintering step, the temperature is first raised to 1000-1600°C and kept warm for 1000-3000 minutes, with a heating rate of 1-10°C / min during sintering; then the temperature is lowered to 10-30°C, with a cooling rate of 1-5°C / min during sintering.

[0018] In the above technical solution, the sintering step can ensure that M x O y The elements in the powder can enter the tin dioxide lattice as much as possible to replace Sn, thereby enhancing the density of the tin dioxide target.

[0019] In a second aspect, an embodiment of the present application provides a tin dioxide target material, which is prepared by the above-mentioned method for preparing the tin dioxide target material.

[0020] In the above technical solution, the tin dioxide target material prepared using the above preparation method has good density, high purity, and few lattice defects. Using the tin dioxide target material of the present application to prepare a transparent conductive film can enhance the purity of the film, reduce the resistivity of the film, and improve the carrier concentration and carrier mobility of the film.

[0021] In a third aspect, an embodiment of the present application provides an application of the tin dioxide target material of the second aspect in depositing a conductive oxide film in a solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 This is a process flow chart for preparing a tin dioxide target material according to an embodiment of the present application;

[0024] Figure 2 : is the transmittance spectrum of the TCO film obtained using the tin dioxide target material of Example 1 of the present application;

[0025] Figure 3 : is the light transmittance spectrum of the TCO film obtained using the tin dioxide target material of Example 2 of the present application;

[0026] Figure 4 : is the transmittance spectrum of the TCO film obtained using the tin dioxide target material of Example 3 of the present application;

[0027] Figure 5 : is the light transmittance spectrum of the TCO film obtained using the tin dioxide target material of Example 4 of the present application;

[0028] Figure 6 The light transmittance spectrum of the TCO film obtained using the tin dioxide target material of Comparative Example 1 of the present application;

[0029] Figure 7 The light transmittance spectrum of the TCO film obtained using the tin dioxide target material of Comparative Example 2 of the present application;

[0030] Figure 8 The light transmittance spectrum of the TCO film obtained using the tin dioxide target material of Comparative Example 3 of the present application;

[0031] Figure 9 : This is the light transmittance spectrum of the TCO film obtained using the tin dioxide target material of Comparative Example 4 of the present application. DETAILED DESCRIPTION

[0032] To make the purpose, technical solutions and advantages of the examples of the present application clearer, the technical solutions in the examples of the present application will be described clearly and completely below. Where specific conditions are not specified in the examples, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially.

[0033] The tin dioxide target material and its preparation method according to the embodiment of the present application are described in detail below.

[0034] The embodiment of the present application provides a tin dioxide target material, Figure 1 The process flow chart for preparing tin dioxide target is as follows:

[0035] S100, forming a mixed powder.

[0036] Specifically, this step is generally to grind and / or pre-sinter the SnO2 powder in an oxidant, and then x O y The powder is mixed so that M x O y The M element in the powder can enter the SnO2 lattice to replace Sn, and with the subsequent steps, the prepared target material can be more uniform and dense. The oxidant can be at least one of H2O2, O2, and O3 to facilitate subsequent removal; the element M is at least one of Ta, Sb, Nb, W, Mo, and V. The particle size of SnO2 powder is generally 20 to 500 nm, specifically, it can be 100 to 400 nm, more specifically, it can be 200 to 300 nm, for example, the particle size of SnO2 powder is 50 nm, 150 nm, 250 nm, 350 nm or 450 nm; M x O y The particle size of the powder is 20 to 500 nm, specifically, 100 to 400 nm, more specifically, 200 to 300 nm. For example, M x O y The particle size of the powder is 50 nm, 150 nm, 250 nm, 350 nm or 450 nm.

[0037] The inventors have discovered that SnO2 powder currently available on the market generally has lattice defects such as oxygen vacancies (i.e., the presence of SnO phases). Oxygen vacancies refer to vacancies formed by the detachment of oxygen atoms (or ions) in the lattice of metal oxides or other oxygen-containing compounds, resulting in oxygen deficiency. Simply put, it refers to the defects left behind by the escape of oxygen ions from its lattice. The target material prepared using this SnO2 powder will also have oxygen vacancies on its surface, which is not conducive to the preparation of TCO (Transparent Conductive Oxide) films with high conductivity and high transmittance.

[0038] In this step, SnO2 powder is ground and / or pre-sintered in an oxidant to oxidize SnO2, which can eliminate the SnO phase in SnO2 to the greatest extent and reduce the oxygen vacancy defects in SnO2. The target material prepared subsequently can improve the stability of the TCO film and reduce the sensitivity of the TCO film.

[0039] For example, in this step, H2O2 and SnO2 can be mixed and ground, in which case the molar ratio of H2O2 to SnO2 can be 0.1 to 1:1, or SnO2 can be ground in an O2 atmosphere, or in an O3 atmosphere. The above grinding process can be carried out in a ball mill, the grinding time is generally 3 to 20 minutes, and the speed of the ball mill during grinding is generally 100 to 800 rpm. Of course, the above oxidation step can also be repeated, the number of repetitions is generally 5 to 30, and the time interval between each repetition is generally 5 to 20 minutes.

[0040] In addition, this step can also be to place SnO2 in an O2 atmosphere or an O3 atmosphere for heating. The heating is generally carried out in a tubular furnace. The pressure in the furnace during heating is generally 0.1 to 1 atmospheres, and the heating time is generally 10 to 100 minutes. When heating in an O2 atmosphere, the heating temperature is generally 50 to 1400°C. When heating in an O3 atmosphere, the heating temperature is generally 50 to 400°C.

[0041] S200, ball milling is performed using a ball mill.

[0042] In this step, the ball milling speed is 100 to 800 rpm, for example, 200 rpm, 350 rpm, 450 rpm, 550 rpm, or 700 rpm. The ball milling time is 3 to 20 minutes, for example, 5 minutes, 12 minutes, 16 minutes, or 18 minutes. Of course, this step can also be repeated for 5 to 30 minutes, with each repetition time typically being 5 to 20 minutes.

[0043] S300: preheating the mixed powder.

[0044] This step is generally carried out in a tube furnace or a box furnace. The preheating time is generally 1000 to 3000 min, for example, 2000 min or 2500 min; the preheating temperature is 700 to 1400°C, for example, 800°C, 1000°C, 1200°C or 1300°C; the heating rate during preheating is 1 to 10°C / min, for example, 3°C / min, 5°C / min, 7°C / min or 9°C / min.

[0045] Through S200 ball milling and S300 preheating, M x O y The powder undergoes a sufficient solid-phase reaction with the SnO2 powder, allowing the M element to enter the SnO2 lattice as much as possible to replace Sn, thereby making the prepared target material more uniform and dense. To ensure that the M element enters the SnO2 lattice as much as possible, steps S200 and S300 can be repeated multiple times.

[0046] S400, drying the mixed powder at a drying temperature of 70 to 120° C. for 50 to 100 minutes.

[0047] S500, pressing the mixed powder into a mold at a pressure of 50 to 1500 MPa for 5 to 30 minutes.

[0048] By controlling the pressure at 50-1500 MPa and the pressing time at 5-30 min, it is possible to ensure that the SnO2 powder and Mn are bonded together without adding a binder. x O y The powders are tightly combined and pressed into shape without affecting the compactness of the subsequent target material during molding. Moreover, without adding a binder, the purity of the target material can be better improved, thereby improving the electrical and optical properties of the conductive film. Specifically, in this step, the pressure is 50 to 1500 MPa, such as 80 MPa, 100 MPa, 200 MPa, 400 MPa, 600 MPa, 900 MPa, 1200 MPa or 1400 MPa; the pressurization time is 15 to 30 minutes, such as 18 minutes, 20 minutes, 22 minutes, 24 minutes, 26 minutes or 28 minutes. In addition, this step is generally pressed in a mold to facilitate the mixing of powders into a specific shape.

[0049] S600: Sintering to obtain a tin dioxide target.

[0050] The sintering step can also make M x O y The powder and SnO2 powder undergo sufficient solid phase reaction to make M x O yThe M element in the powder enters the SnO2 lattice as much as possible to replace Sn, thereby making the prepared target material more uniform and dense.

[0051] Specifically, during sintering in this step, the temperature is first raised to 1000-1600° C. and kept for 1000-3000 min at a heating rate of 1-10° C. / min; then lowered to 10-30° C. at a cooling rate of 1-5° C. / min.

[0052] The features and performance of the present application are further described in detail below with reference to the embodiments.

[0053] Example 1

[0054] This embodiment provides a tin dioxide target material, and the preparation method thereof is as follows:

[0055] 40 g of SnO2 powder with a particle size of 100 to 200 nm was mixed with 12 ml of a 30 wt.% H2O2 solution and placed in a ball mill for grinding to perform oxidation treatment. The grinding speed was 100 rpm and the grinding time was 20 min.

[0056] The oxidized SnO2 powder is mixed with 2g of Ta2O5 powder with a particle size of 100-200nm, and ball milled at a rotation speed of 100 rpm and a ball milling time of 20min. The ball milled powder is then placed in a box furnace for preheating at a preheating temperature of 1400°C, a preheating time of 1000min, and a heating rate of 10°C / min. The preheated mixed powder is then cooled and ball milled again, preheated again after ball milling, cooled after preheating again, and then ball milled for a third time.

[0057] The mixed powder from the third ball milling process was placed in a drying oven and dried at 100°C for 1 hour. The dried mixed powder was then pressed into shape in a mold at a pressure of 800 MPa for 30 minutes. After compaction, the mixed powder was placed in a box furnace for sintering. The temperature was first increased to 1000°C at a rate of 10°C / min, then held at that temperature for 3000 minutes, and then cooled to 30°C at a rate of 5°C / min.

[0058] The target material blank is placed in a box furnace for sintering; (10) a radio frequency magnetron sputtering device is used to coat the sintered target material under the coating conditions of 30W, 0.4Pa, 27min, and 200°C.

[0059] Example 2

[0060] This embodiment provides a tin dioxide target material, and the preparation method thereof is as follows:

[0061] 40 g of SnO2 powder with a particle size of 100 to 200 nm was measured and ground in an O3 atmosphere for oxidation treatment at a grinding speed of 800 rpm for 3 min.

[0062] The oxidized SnO2 powder is mixed with 1.8 g of Sb2O5 powder with a particle size of 100 to 300 nm, and ball milled at a rotation speed of 800 rpm and a ball milling time of 3 min. The ball milled powder is then placed in a box furnace for preheating at a preheating temperature of 700°C, a preheating time of 3000 min, and a heating rate of 10°C / min. The preheated mixed powder is then cooled and ball milled again, preheated again after ball milling, cooled after preheating again, and then ball milled for a third time.

[0063] The mixed powder after the third ball milling was placed in a drying oven and dried at 100°C for 1 hour. The dried mixed powder was then pressed into shape in a mold at a pressure of 800 MPa for 15 minutes. After compaction, the mixed powder was placed in a box furnace for sintering. The temperature was first increased to 1600°C at a rate of 10°C / min, then held at that temperature for 3000 minutes, and then cooled to 15°C at a rate of 5°C / min.

[0064] Example 3

[0065] This embodiment provides a tin dioxide target material, and the preparation method thereof is as follows:

[0066] 40 g of SnO2 powder with a particle size of 100 to 200 nm was measured and ground in an O3 atmosphere for oxidation treatment at a grinding speed of 400 rpm for 15 min.

[0067] The oxidized SnO2 powder is mixed with 1.9 g of Nb2O5 powder with a particle size of 50 to 200 nm, and ball milled at a rotation speed of 400 rpm for 15 min. The milled powder is then placed in a box furnace for preheating at a temperature of 1200°C for 2000 min and a heating rate of 10°C / min. The preheated mixed powder is then cooled and ball milled again, preheated again after ball milling, cooled after preheating again, and ball milled for a third time.

[0068] The mixed powder after the third ball milling was placed in a drying oven and dried at 100°C for 1 hour. The dried mixed powder was then pressed into shape in a mold at a pressure of 700 MPa for 20 minutes. After compaction, the mixed powder was placed in a box furnace for sintering. The temperature was first increased to 1300°C at a rate of 10°C / min, then held at that temperature for 2000 minutes, and then cooled to 20°C at a rate of 5°C / min.

[0069] Example 4

[0070] This embodiment provides a tin dioxide target material, and the preparation method thereof is as follows:

[0071] 40 g of SnO2 powder with a particle size of 100 to 200 nm was measured and ground in an O2 atmosphere for oxidation treatment at a grinding speed of 400 rpm for 15 min.

[0072] The oxidized SnO2 powder is mixed with 1.2 g of WO3 powder with a particle size of 200-300 nm, and ball milled at a rotation speed of 400 rpm for 15 min. The ball milled powder is then placed in a box furnace for preheating at a preheating temperature of 1000°C, a preheating time of 2000 min, and a heating rate of 10°C / min. The preheated mixed powder is then cooled and ball milled again, preheated again after ball milling, cooled after preheating again, and then ball milled for a third time.

[0073] The mixed powder after the third ball milling was placed in a drying oven and dried at 100°C for 1 hour. The dried mixed powder was then pressed into shape in a mold at a pressure of 600 MPa for 25 minutes. After compaction, the mixed powder was placed in a box furnace for sintering. The temperature was first increased to 1300°C at a rate of 10°C / min, then held at that temperature for 2000 minutes, and then cooled to 20°C at a rate of 5°C / min.

[0074] Comparative Example 1

[0075] This comparative example provides a tin dioxide target material, and its preparation method has the following main differences compared with Example 1:

[0076] SnO2 was not oxidized, and the mass of Ta2O5 powder in the mixed powder was 1.2 g.

[0077] Comparative Example 2

[0078] This comparative example provides a tin dioxide target material, and its preparation method has the following main differences compared with Example 1:

[0079] The pressure during pressing is 40 MPa and the pressing time is 30 min.

[0080] Comparative Example 3

[0081] This comparative example provides a tin dioxide target material, and its preparation method has the following main differences compared with Example 1:

[0082] The pressure during pressing is 1600 MPa and the pressing time is 3 minutes.

[0083] Comparative Example 4

[0084] This comparative example provides a tin dioxide target material, and its preparation method has the following main differences compared with Example 1:

[0085] Polyvinyl alcohol was added to the mixed powder as a binder.

[0086] Application Examples

[0087] Using radio frequency magnetron sputtering equipment, coating was performed using the tin dioxide targets in Examples 1 to 4 and Comparative Examples 1 to 4, respectively. The coating conditions were 30 W, 0.4 Pa, 27 min, and 200° C.

[0088] The transmittance of TCO films made with different tin dioxide targets was tested using a UV-spectrophotometer. The spectra are shown in Figure 2. Figures 2 to 9 shown.

[0089] Depend on Figures 2 to 9 It can be seen that the light transmittance of the TCO film produced by using the tin dioxide target material of the embodiment is better than that of the TCO film produced by using the tin dioxide target material of the comparative example.

[0090] The TCO films made with different tin dioxide targets were electrically tested using a Hall effect tester. The test results are shown in Table 1:

[0091] Table 1 Carrier concentration, carrier mobility, resistivity and film thickness of TCO films

[0092]

[0093] It can be seen from the table that the electrical properties of the TCO film produced using the tin dioxide target material of the embodiment are better than those of the TCO film produced using the tin dioxide target material of the comparative example.

[0094] The above description is merely an embodiment of the present application and is not intended to limit the scope of protection of the present application. For those skilled in the art, various modifications and variations of the present application are possible. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A method for preparing a tin dioxide target, characterized in that: It includes the following steps: SnO2 powder and M x O y The powders are mixed and ball milled using a ball mill. The mixed powder obtained after ball milling is preheated, with a preheating time of 1000-3000 minutes, a preheating temperature of 700-1400° C., and a heating rate of 1-10° C. / min during preheating. The preheated mixed powder is cooled and pressurized under a pressure of 50-1500 MPa for 5-30 minutes until the mixed powder is pressed into a shape, and then sintered. The sintering includes raising the temperature to 1000-1600° C. and holding it for 1000-3000 minutes at a heating rate of 1-10° C. / min during sintering; then lowering the temperature to 10-30° C. at a cooling rate of 1-5° C. / min during sintering; The M x O y The element M in the powder is at least one of Ta, Sb, Nb, W, Mo, and V, and x and y are any integers between 1 and 5. The mass of the SnO2 powder accounts for 80% to 99.9% of the mass of the mixed powder.

2. The method for preparing a tin dioxide target according to claim 1, wherein: In the step of pressing, the pressure is 500-1500 MPa, and the pressing time is 15-30 min.

3. The method for preparing a tin dioxide target according to claim 1, wherein: The mixed powder is mainly prepared by the following steps: grinding and / or pre-sintering the SnO2 powder in an oxidant, and then mixing with the M x O y Powder mixing.

4. The method for preparing a tin dioxide target according to claim 3, wherein: The oxidant includes at least one of H2O2, O2, and O3.

5. The method for preparing a tin dioxide target according to claim 1, wherein: Before the step of pressing the mixed powder into a shape, the method further comprises the step of ball milling the mixed powder using a ball mill, wherein the rotation speed during ball milling is 100 to 800 revolutions per minute and the ball milling time is 3 to 20 minutes.

6. The method for preparing a tin dioxide target according to claim 1, wherein: After the step of preheating the mixed powder, the method further comprises the step of drying the mixed powder, wherein the drying temperature is 70-120° C. and the drying time is 50-100 minutes.

7. The method for preparing a tin dioxide target according to claim 1, wherein: The particle size of the SnO2 powder is 20-500 nm; and / or, the M x O y The particle size of the powder is 20~500nm.

8. A tin dioxide target, characterized in that: The tin dioxide target is prepared by the preparation method of any one of claims 1 to 7.

9. Use of the tin dioxide target material according to claim 8 in preparing a conductive oxide film in a solar cell.

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