Molybdenum oxide-based sintered body, sputtering target comprising same, and oxide thin film

Abstract

Provided are an oxide sintered body mainly containing a molybdenum oxide, a sputtering target containing the sintered body, and an oxide thin film formed by the sintered body. In the present invention, by adding a specific (pseudo) metal oxide in a prescribed range to a molybdenum oxide and a niobium oxide which are difficult to sinter, the sinterability can be improved and high-density characteristics can be ensured even if pressureless sintering is performed.

Description

Technical Field

[0001] The present invention relates to an oxide sintered body with molybdenum oxide as the main component, a sputtering target comprising the above-mentioned sintered body, and an oxide thin film formed therefrom. More specifically, it relates to a molybdenum oxide-based sintered body, a sputtering target, and an oxide thin film formed therefrom, which, when used to prepare a sputtering target for TFT structures for LCDs and OLEDs, simultaneously improves sinterability and density characteristics by adding a specified range of specific (quasi)metal oxides. Background Technology

[0002] Typically, conductive thin films with low reflectivity are used in flat panel displays (FPDs), touch screen panels, solar cells, and organic light emitting diodes (OLEDs).

[0003] The representative material is indium tin oxide (In2O3-SnO2) (“ITO”), and ITO compositions are used to form conductive thin films with high visible light transmittance and conductivity. This ITO composition exhibits excellent low reflectivity, but due to its poor economic efficiency, materials to replace all or part of indium oxide are under continuous research.

[0004] However, this research focuses on the low reflectivity of the thin film formed by the target material, and needs to consider the chemical resistance and heat resistance properties, which can improve the reliability of the film during long-term use.

[0005] On the other hand, molybdenum oxide is a difficult-to-sinter material. As such, when using molybdenum oxide-based ceramic materials that are difficult to sinter and have low density, it is not only difficult to form high-density (e.g., relative density of over 90%) targets, but also, when sputtering with the prepared targets, foreign matter is generated due to back depo. and nodule, which inevitably leads to a decrease in the physical properties of the film.

[0006] Existing technical documents

[0007] Patent Document 1: Korean Patent Publication No. 10-2020-0069314 Summary of the Invention

[0008] Technical issues

[0009] The present invention was proposed to solve the above-mentioned problems. The technical problem of the present invention is to provide a novel molybdenum oxide-based sintered body, which improves sinterability and ensures high density even when sintering under pressureless conditions by adding a specified range of specific (quasi) metal oxides to a difficult-to-sinter molybdenum oxide as the main raw material, a sputtering target containing the above-mentioned sintered body, and an oxide film formed therefrom.

[0010] Other objects and advantages of the present invention may be more clearly explained by the following detailed description of the invention and the scope of the claims.

[0011] Technical solution

[0012] To solve the above-mentioned technical problems, the present invention provides an oxide sintered body comprising: molybdenum oxide (M1) containing at least one of MoO2 and MoO3; niobium oxide (M2); and metal oxide (M3) containing at least one alkaline earth metal, wherein the content of molybdenum oxide (M1) is 70% or more by weight relative to the total weight of the sintered body.

[0013] In one embodiment of the present invention, the metal oxide (M3) may include a first metal oxide (M3-1) containing at least one of Ca and Mg.

[0014] In one embodiment of the present invention, the first metal oxide (M3-1) may comprise one or more selected from the group consisting of CaCO3 and MgO.

[0015] In one embodiment of the present invention, the metal oxide (M3) may include a first metal oxide (M3-1) and a second metal oxide (M3-2) containing one or more metals selected from the group consisting of Co, Si, Y and Ga.

[0016] In one embodiment of the present invention, the second metal oxide (M3-2) may comprise one or more selected from the group consisting of Co3O4, SiO2, Y2O3 and Ga2O3.

[0017] In one embodiment of the present invention, based on 100% by weight of the sintered body, the content of the metal oxide (M3) may be greater than 0% by weight and less than 10.0% by weight.

[0018] In one embodiment of the present invention, based on 100% by weight of the above-mentioned oxide sintered body, the content of the above-mentioned molybdenum oxide (M1) and the above-mentioned niobium oxide (M2) can be 90.0% by weight or more and less than 100% by weight, and the content ratio of the above-mentioned molybdenum oxide (M1) to the above-mentioned niobium oxide (M2) can be 50:50 by weight to 90:10 by weight.

[0019] In one embodiment of the present invention, the above-mentioned oxide sintered body can be formed by mixing molybdenum oxide (M1), niobium oxide (M2) and metal oxide (M3) and then sintering them without pressure.

[0020] In one embodiment of the present invention, the resistivity of the oxide sintered body can be 1×10⁻⁶. -2 For samples with a density below Ωcm, the relative density can be above 80%.

[0021] Furthermore, the present invention provides a sputtering target comprising the above-mentioned pressureless sintered body.

[0022] In addition, the present invention provides an oxide thin film formed from the above-mentioned sputtering target.

[0023] The effects of the invention

[0024] According to one embodiment of the present invention, by adding a specified range of (quasi)metal oxides containing specific elements to a difficult-to-sinter molybdenum oxide, the sinterability of the molybdenum oxide sintered body can be improved and high density can be ensured even under pressureless conditions.

[0025] Therefore, the molybdenum oxide-based sintered body and sputtering target of the present invention can be usefully applied to forming electrodes or lines for TFT structures of LCDs and OLEDs.

[0026] The effects of the present invention are not limited to the examples above, and this specification also includes many other effects. Attached Figure Description

[0027] Figure 1 The image shows the microstructure of the sintered body of the molded body of Example 9 using added metal oxide (M3) as a function of heat treatment temperature.

[0028] Figure 2 This image shows the change in microstructure of the sintered body of the molded body of Comparative Example 1 without added metal oxide (M3) according to the heat treatment temperature.

[0029] Figure 3 SEM images of the fracture surfaces of the powder microstructure of the mixed raw materials, the microstructure of the pressureless sintered body prepared in Example 9, and the microstructure of the pressure sintered body prepared in Comparative Example 5 are shown respectively.

[0030] Figure 4 SEM images of the polished surfaces of the microstructure of the pressureless sintered body prepared in Example 9 and the microstructure of the pressure-sintered body prepared in Comparative Example 5 are shown respectively.

[0031] Figure 5 To show the relative density curves of the pressureless sintered bodies prepared in Examples 1 to 6 as a function of sintering temperature.

[0032] Figure 6 To illustrate the relative density curves of the pressureless sintered bodies prepared in Examples 7 to 12 with sintering temperature.

[0033] Figure 7 To illustrate the relative density curves of the pressureless sintered bodies prepared in Examples 13 to 17 with sintering temperature.

[0034] Figure 8 To show the relative density curves of the sintered bodies prepared in Comparative Examples 1 to 4 with sintering temperature.

[0035] Figure 9 To illustrate the shrinkage rate of the pressureless sintered bodies prepared in Examples 1 to 6 as a function of sintering temperature.

[0036] Figure 10 To illustrate the curves showing the shrinkage rate of the pressureless sintered bodies prepared in Examples 7 to 12 as a function of sintering temperature.

[0037] Figure 11 To illustrate the shrinkage rate of the pressureless sintered bodies prepared in Examples 13 to 18 as a function of sintering temperature.

[0038] Figure 12 To show the shrinkage rate of the oxide sintered bodies prepared in Comparative Examples 1 to 4 as a function of sintering temperature.

[0039] Figure 13 XRD patterns are shown for the crystal structures of the pressureless sintered body prepared in Example 9 and the pressure sintered bodies prepared in Comparative Examples 1 and 5.

[0040] Figure 14 The graph shows the thin-film resistance characteristics of the unit films prepared from the components of Example 1, Example 9 and Comparative Example 1.

[0041] Figure 15 The graph shows the average reflectance of the double films prepared from the components of Example 1, Example 9 and Comparative Example 1 in the visible light range (380-740 nm wavelength).

[0042] Figure 16 Images showing the etching evaluation results of the double films prepared from the components of Example 9 and Comparative Example 1. Detailed Implementation

[0043] The present invention will now be described in detail.

[0044] All terms used in this specification (including technical and scientific terms) may be used in the sense that would be commonly understood by one of ordinary skill in the art to which this invention pertains. Furthermore, unless otherwise specifically defined, terms as defined in common dictionaries should not be idealized or over-interpreted.

[0045] Furthermore, throughout the specification, when a part "includes" a structural element, unless otherwise specifically stated to the contrary, it means that other structural elements may also be included, rather than excluding them. Also, throughout the specification, "above" or "above" refers not only to the case where it is located above or below the object part, but also to the case where there are other parts in between, and does not necessarily mean that it must be located above based on the direction of gravity. Moreover, in the specification of this invention, terms such as "first" and "second" are used to distinguish structural elements from each other rather than to indicate any order or importance.

[0046] MoO2-Nb2O5 materials used as existing n-type semiconductor thin films are typically prepared via pressure sintering. However, pressure sintering is unsuitable for mass production due to the increased cost of the equipment. Furthermore, the high pressure applied in the process limits the ability to increase the size of the sintered product.

[0047] To address the aforementioned issues, pressureless sintering of MoO2-Nb2O5 materials is difficult to apply due to the limited increase in sintering density. Furthermore, increasing the sintering temperature leads to a decrease in density due to increased melting and volatilization. In other words, sintering requires heat as a driving force, and generally, higher temperatures are more beneficial in ensuring sinterability (densification). Conversely, for some raw materials, volatilization and other problems can lead to a decrease in density.

[0048] Therefore, the present invention can provide a molybdenum oxide-based sintered body and a sputtering target thereof, which can achieve high density while improving sinterability by using a small amount of a specific dopant (M3) that helps sinterability in a difficult-to-sinter material with molybdenum oxide and niobium oxide as basic components.

[0049] Specifically, the alkaline earth metal-based oxide dopant (M3) used in this invention helps ensure the sintering driving force of MoO2 / MoO3-Nb2O5, a difficult-to-sinter material, thereby increasing the sintering density due to the temperature drop effect even when pressureless sintering is performed. For example, compared to sintered bodies that do not contain the specific metal oxide (M3), the molybdenum oxide sintered body of this invention can have excellent density and resistivity characteristics. In particular, even when a pressureless sintered body is formed solely through heat treatment without pressurization, density and resistivity characteristics at or above the level of conventionally pressurized oxide sintered bodies (e.g., HP, HIP, etc.) can be ensured. Moreover, compared to pressurized oxide sintered bodies, it is superior in terms of sintering size and mass production, and also has the advantage of low equipment cost.

[0050] Furthermore, since the grain size of the oxide sintered body constituting the present invention is larger than that of the molybdenum oxide sintered body subjected to pressure sintering by simultaneously applying a specified pressure and heat treatment, it is more advantageous in terms of reaction. For example, as follows: Figures 3-4 As shown, the pressurized sintered body is a form in which the initial raw materials are forcibly aggregated together by high pressure, so the particle size hardly increases. In contrast, it can be seen that the particle size of the sintered body of the present invention increases through reaction. In particular, it can be seen that the particles are in a composite and merged state in the mutual reaction between dissimilar elements, which is advantageous in terms of reaction.

[0051] Furthermore, without added elements, molybdenum oxide targets have very low density and high resistivity. This high resistivity leads to a problem of plasma not forming during DC sputtering. In contrast, the molybdenum oxide target of this invention ensures sinterability by adding a dopant, thus providing a high-density target at a sputtering-ready level even through pressureless sintering.

[0052] <Oxide Sintered Bodies and Sputtering Targets>

[0053] One example of the present invention is a metal oxide sintered body used to prepare a sputtering target material with molybdenum oxide as the main component. This sintered body differs from existing sintered bodies in that it contains a metal oxide (M3) containing at least one alkaline earth metal as an essential component.

[0054] In one specific example, the oxide sintered body comprises: molybdenum oxide (M1) containing at least one of MoO2 and MoO3; niobium oxide (M2); and metal oxide (M3) containing at least one alkaline earth metal, wherein the content of molybdenum oxide (M1) is 70% by weight or more relative to the total weight of the sintered body.

[0055] When a sintered metal oxide body composed of the above components is used as a target to form a thin film, the resulting film exhibits low reflectivity. Furthermore, by optimizing the proportion and composition of the molybdenum oxide, heat resistance and chemical resistance are improved. Moreover, by adding a small amount of a specific dopant (M3) to increase density, Mo-Nb-O based sputtering targets, which are difficult-to-sinter materials, can be prepared without the need for pressure sintering.

[0056] The following is a detailed description of each ingredient.

[0057] The molybdenum oxide contained in the oxide sintered body of the present invention is the main component constituting the sintered body.

[0058] Molybdenum oxide (M1) is a component such as MoO2, MoO3, or MoO4, which has molybdenum combined with oxygen. In this invention, MoO2, MoO3, or a mixture of MoO2 and MoO3 can be used as molybdenum oxide (M1). In this case, when a mixture of MoO2 and MoO3 is used as molybdenum oxide, there are no particular limitations on the mixing ratio between them, and it can be appropriately adjusted within the conventional content range known in the art. On the other hand, since the melting point of MoO3 is about 800°C, it will volatilize at high temperatures above 1000°C. Therefore, in this invention, MoO2 is preferably used as molybdenum oxide.

[0059] One of the additives included in the oxide sintered body of the present invention is niobium oxide (M2).

[0060] This niobium oxide (M2) is an oxide dopant that improves the chemical and heat resistance properties of molybdenum oxide. The aforementioned metal oxide can enhance the chemical and heat resistance properties of molybdenum oxide. There are no particular limitations on the niobium oxide used, as long as it has a niobium-oxygen bond, for example, Nb2O5. In the following description, the niobium oxide composition will be indicated by M2.

[0061] Another additive component included in the oxide sintered body of the present invention is a metal oxide (M3) containing at least one alkaline earth metal.

[0062] For example, the metal oxide (M3) mentioned above may contain at least one of Ba, Ca, Mg and Sr, and specifically, may contain a first metal oxide (M3-1) containing at least one of Ca and Mg.

[0063] The first metal oxide (M3-1) acts as a dopant, exhibiting a density increase effect by improving the sinterability of difficult-to-sinter molybdenum oxides. The chemical resistance and heat resistance properties of molybdenum oxides can be improved by adding this first metal oxide. There are no particular limitations on the first metal oxide (M3-1), as long as it is a composition in which at least one element (A) selected from Ca and Mg is combined with oxygen; for example, it may contain one or more elements selected from the group consisting of CaCO3 and MgO.

[0064] For example, the aforementioned metal oxide (M3) may include a first metal oxide (M3-1) and a second metal oxide (M3-2) containing one or more metals selected from the group consisting of Co, Si, Y and Ga.

[0065] The second metal oxide (M3-2) can improve the sinterability of the molybdenum oxide by assisting the first metal oxide. There are no particular limitations on this second metal oxide (M3-2), as long as it is a composition in which at least one element selected from Co, Si, Y, and Ga is combined with oxygen. For example, it can contain one or more elements selected from the group consisting of Co3O4, SiO2, Y2O3, and Ga2O3. In this case, when the first metal oxide (M3-1) and the second metal oxide (M3-2) are used together as the metal oxide (M3), there are no particular limitations on their mixing ratio, for example, a weight ratio of 1:0.3 to 2.5, more specifically, a weight ratio of 1:0.5 to 2.0.

[0066] In a metal oxide sintered body comprising the aforementioned molybdenum oxide (M1), niobium oxide (M2), and (quasi-)metal oxide (M3), based on 100% by weight of the sintered body, the content of molybdenum oxide (M1) and niobium oxide (M2) may be 90% by weight or more and less than 100% by weight, and the content of (quasi-)metal oxide (M3) may be greater than 0% by weight and less than 10% by weight. More specifically, it may have a composition consisting of 95.0% to 99.5% by weight of molybdenum oxide (M1) and niobium oxide (M2), and 0.5% to 5.0% by weight of (quasi-)metal oxide (M3). The content ratio of molybdenum oxide (M1) to niobium oxide (M2) is a weight ratio of 50:50 to 90:10, specifically a weight ratio of 70:30 to 90:10, and more specifically, a weight ratio of 75:25 to 90:10. In this invention, when the proportion of molybdenum oxide accounts for more than 70% by weight of the total metal oxide sintered body, it can have low reflectivity when deposited as a thin film.

[0067] The oxide sintered body of the invention, as described above, exhibits a relative density of 80% or more, specifically 90% or more, even after pressureless sintering. In this case, there is no particular upper limit. Furthermore, the resistivity of the oxide sintered body is 1 × 10⁻⁶. -2 Below Ωcm, there are no special restrictions on its lower limit value.

[0068] Furthermore, the grain size (D) contained in the oxide sintered body 50 There are no particular limitations; for example, the grain size can be from 1 μm to 30 μm. Specifically, the grain size of the sintered body prepared under pressure conditions can be from 1 μm to 3 μm, and the grain size of the sintered body prepared under pressureless conditions can be from 3 μm to 30 μm. In particular, the particle size of the oxide sintered body constituting the present invention is larger than that of the molybdenum oxide sintered body formed by artificially pressing powder and then pressure sintering using methods such as HP or HIP. Therefore, it has a more advantageous effect in terms of reaction.

[0069] In one specific example, the average particle size (D) constituting the pressureless sintered body of the present invention is... 50 It can satisfy the conditions of Equation 1 below.

[0070] Formula 1:

[0071] G N / G P ≥3.0

[0072] In the above formula,

[0073] G N The average particle size (D) of the oxide sintered body subjected to pressureless heat treatment at 1400±200℃ for 2 hours is given. 50 ), G P The average particle size (D) of the oxide sintered body subjected to pressure heat treatment at 30 MPa and 830 °C for 2 hours is given. 50 ).

[0074] Specifically, the average particle size (D) of the pressureless sintered body constituting Formula 1 above... 50 The average particle size (D) of the oxide sintered body undergoing pressureless heat treatment is 5.0 or higher, and more specifically, it can be 10.0 or higher. For example, the average particle size (D) of the oxide sintered body undergoing pressureless heat treatment... 50 The average particle size (D) of the oxide sintered body subjected to pressure heat treatment can range from 3 μm to 30 μm. 50 The diameter can range from 1μm to 3μm.

[0075] Furthermore, according to another embodiment of the present invention, the sputtering target includes: an oxide sintered body, with the aforementioned molybdenum oxide as the main component; and a backing plate, which is bonded to one surface of the sintered body to support the sintered body.

[0076] The backplate is a substrate that supports the sintered body used for sputtering the target, and conventional backplates known in the art can be used without restriction. In this case, there are no particular limitations on the material constituting the backplate or its shape.

[0077] <Preparation Methods of Oxide Sintered Bodies and Sputtering Targets>

[0078] The following will describe a method for preparing an oxide sintered body and a sputtering target according to an embodiment of the present invention. However, the method is not limited to the following preparation method, and the steps of each process may be changed or selectively combined as needed.

[0079] As an embodiment of the above preparation method, it can be configured to include: step (i), preparing a raw material powder containing molybdenum oxide (M1), niobium oxide (M2), and a metal oxide (M3) containing at least one alkaline earth metal (A); step (ii), preparing a molded body using the above raw material powder ("step S20"); and step (iii), preparing a sintered body by pressurelessly sintering the above molded body at a temperature of 1200°C to 1600°C for 1 hour to 20 hours ("step S30").

[0080] The preparation method described above will be explained in the following steps.

[0081] (i) Prepare raw material powder (“Step S10”)

[0082] In step S10 above, a raw material powder comprising molybdenum oxide (M1), niobium oxide (M2), and a (quasi)metal oxide (M3) containing at least one alkaline earth metal (A) is prepared. Specifically, molybdenum oxide (M1), niobium oxide (M2), one or more first metal oxide powders (M3-1) selected from the group consisting of CaCO3 and MgO, and a second metal oxide powder (M3-2) as required are weighed to meet the target composition. Then, each powder is placed in a mixer for pulverization and mixing to prepare a mixture.

[0083] When mixing the above-mentioned raw material powders, conventional additives known in the art may be further included as needed, such as binders, dispersants, defoamers, etc. In this case, the amount of additives used can be appropriately adjusted within the conventional range known in the art; for example, it may be used from 0.01% to 10% by weight relative to the total weight of the powder in the slurry (e.g., 100% by weight).

[0084] There are no particular limitations on the mixing and pulverization of the raw material powders, and conventional ball mills, grinding mills, bead mills, etc., known in the art can be used. For example, the mixed raw material powders can be dry-milled using zirconia balls. The weight of the zirconia balls can be 1 to 3 times the amount of powder, and the milling can be carried out at a speed of 100 to 300 rpm for 10 to 36 hours.

[0085] As a specific example of step S10 above, in order to mix and pulverize the raw material powder by a wet ball mill, a pre-weighed elemental powder is added to a prepared PE container, along with zirconium oxide balls at a weight equivalent to approximately 2 to 4 times, preferably 3 times, the weight of the raw material. Then, distilled water or pure water at approximately 1.5 times the level of the raw material is added for ball milling.

[0086] The wet-milled mixture is then dried in a drying oven and ball-milled again to obtain a dry raw material powder. In this case, there are no particular restrictions on the drying conditions; for example, it can be dried in a drying oven at a temperature of about 90°C to 110°C for about 10 to 15 hours.

[0087] Next, the dried mixture is ball-milled again to obtain a dried raw material powder. Depending on the requirements, it is filtered through a sieve of approximately 90 to 110 mesh, specifically 100 mesh, to separate the zirconia balls from the powder.

[0088] (ii) Preparation of the molded body (“Step S20”)

[0089] In step S20 above, a molded body is prepared using the prepared raw material powder. Specifically, the raw material powder is placed in a molding machine and a molded body of a specified specification is prepared through a molding process.

[0090] To increase the density of the molded part, the molding process can be performed in two stages. For example, the first molding process can be performed using a uniaxial molding machine, and the second molding process can be performed using an isostatic pressing machine.

[0091] There are no particular limitations on the conditions during the first and second molding processes described above, and they can be appropriately adjusted under conventional conditions known in the art. For example, there are no particular limitations on the pressure during the first molding after the raw material powder is placed in a uniaxial molding machine; specifically, it can be 10 MPa or more per unit area. Furthermore, there are no particular limitations on the pressure during the second molding process after the first molding is placed in an isostatic pressing machine; for example, it can be 200 MPa or more per unit area, preferably in the range of 200 MPa to 300 MPa.

[0092] As a specific example of step S20 above, a first molded body is prepared using an STS material mold with a specification of 20Φ according to the predetermined powder weight. In this case, it can be carried out under the minimum pressure conditions that allow shape formation, for example, it can be carried out under a pressure of about 10 MPa for 1 minute. Then, a second molding is performed by hydrostatic pressing (CIP) at 200 MPa for several hours. In this case, since the second hydrostatic pressing is carried out with an organic solvent including water, it can be carried out while placed in an acrylic sealing material (e.g., a bag).

[0093] (iii) Preparation of sintered body (“Step S30”)

[0094] In step S30 above, a sintered body is prepared by sintering the prepared molded body under specified conditions.

[0095] In this case, there are no particular restrictions on the sintering conditions, and they can be appropriately adjusted under conventional conditions known in the art. For example, pressureless sintering can be performed at a temperature of 1200°C to 1600°C for 1 to 20 hours, specifically, for 1 to 4 hours. The above sintering can be carried out in an oxygen atmosphere or under inert conditions.

[0096] As a specific example of step S30 above, the prepared molded body is placed in an alumina crucible of specified dimensions for sintering. In this experiment, to confirm the differences in properties between the molded body before heat treatment and the pressureless sintered body after heat treatment, the weight, diameter, and height of the corresponding molded and sintered bodies were measured to compare each physical property (see Table 2 below). Figures 9 to 12 ).

[0097] The relative density of the pressureless sintered body prepared by this process can be above 80%, specifically above 90%. In this case, there is no particular upper limit.

[0098] (iv) Preparation of sputtering targets

[0099] Next, the sintered body is removed and processed. For example, after removing the sintered body, in order to grind the surface of the target material, the upper and lower parts of the target material can be processed to more than 1 mm respectively.

[0100] Then, commercial sputtering targets are prepared using diffusion bonding and final processing methods known in the art.

[0101] Specifically, the sintered body obtained in step S30 above is bonded to the backing plate. In this case, indium can be used as the adhesive, preferably with an adhesion rate of 95% or higher. Next, it is processed to the final target thickness using processing equipment, and the final sputtering target is obtained by spraying and / or arc spraying the surface of the backing plate.

[0102] Metal oxide targets can be prepared through the above process. The prepared target has a target density of 90% or higher, specifically, preferably 95% or higher.

[0103] <Oxide Thin Films>

[0104] Another example of the present invention is a metal oxide thin film deposited using the above-described molybdenum oxide-based target. This metal oxide thin film can be formed by sputtering the above-described sintered body as a target.

[0105] The aforementioned oxide thin films may exhibit slight variations in composition depending on the evaporation atmosphere, but since they are prepared by sputtering the aforementioned oxide target, their composition is essentially the same as that of the target. Therefore, a relative density characteristic of over 90% and a density of 1×10⁻⁶ can be formed. -2 An oxide thin film exhibiting excellent resistivity below Ωcm. Furthermore, by adding specific metal oxides and metals within a defined range to molybdenum oxide, which is the main raw material, the chemical resistance and heat resistance properties can be improved by optimizing the proportion and composition of the molybdenum oxide.

[0106] The metal oxide thin film of the present invention can be formed (evaporated) using conventional sputtering methods known in the art. As an embodiment of the above preparation method, it includes a step of mounting the above-described molybdenum oxide pressureless sintered body sputtering target and then performing room-temperature evaporation in an oxygen and / or argon atmosphere within a vacuum chamber. In this case, a DC sputtering machine can be used for sputtering.

[0107] The substrate and sputtering apparatus used can be any conventional substrate and sputtering apparatus known in the art without limitation. Specifically, it is formed by supplying oxygen or a mixture of oxygen and high-purity argon at a rate of 80–110 sccm (standard cubic centimeters per minute) in a vacuum chamber, specifically at a rate of 95–105 sccm, and the deposition can be performed at room temperature (RT) without heating the substrate on which the film is formed. Furthermore, the power density of the DC sputtering machine can be 1.0–2.0 W / cm². 2 The thickness of the metal oxide film can be 300 to 500, but is not particularly limited to this.

[0108] The oxide thin film obtained as described above can be used in various ways during the fabrication of semiconductor devices, for example, to form circuits or electrodes. In particular, the aforementioned metal oxide thin film can be used as at least one of the gate layer, source layer, and drain layer of a thin-film transistor (TFT). Thus, when the thin film of the present invention is used as a barrier layer for the source and drain included in a thin-film transistor, contact resistance can be reduced, and it exhibits excellent transparency and a low refractive index, thereby improving the physical properties of the thin-film transistor.

[0109] Because the molybdenum oxide-based sputtering target and the resulting oxide film of the present invention possess high density and excellent resistivity characteristics even under no pressure, the contact resistance with the electron injection layer of LCD and OLED TFT structures or organic light-emitting devices can be suppressed to a low level. Therefore, the aforementioned oxide film can also be applied without limitation to various display devices such as liquid crystal displays or organic light-emitting displays; information transmission devices such as LCD, PDP, OLED, and LED flat panel displays; touch screens for surface light source illumination devices such as OLED and LED; and information transmission devices utilizing mobile phones, tablet computers, and / or devices using them.

[0110] The present invention will now be described in detail through the following embodiments. However, the following embodiments are merely examples of the present invention, and the present invention is not limited to the following embodiments.

[0111] Examples 1-17: Preparation of MoO2-Nb2O5-α sintered bodies

[0112] The molded body was prepared by mixing molybdenum oxide (M1), niobium oxide (M2) and (quasi)metal oxide (M3) according to the composition ratio shown in Table 1 below.

[0113] When preparing the molded bodies, most samples were prepared as 20Φ discs, but some components were also prepared as 50Φ discs. Then, the oxide sintered bodies of Examples 1 to 17 were prepared by pressureless heat treatment at a temperature of about 1200 to 1600°C for 2 hours using a heat treatment apparatus.

[0114] Table 1

[0115]

[0116] Comparative Examples 1-4: Preparation of sintered bodies with added MoO2-Nb2O5 and α

[0117] Except for changing the composition of the added oxides as shown in Table 1 above, the molded articles were prepared by the same method as in the above examples. Then, the sintered articles of Comparative Examples 1 to 4 were prepared by heat treatment at a temperature of about 1200 to 1600°C for 2 hours using a heat treatment apparatus.

[0118] Comparative Example 5: Preparation of Sintered Body

[0119] Molybdenum oxide (M1) and niobium oxide (M2) were weighed according to the composition ratio shown in Table 1 above. The weighed powder was placed in a 1L plastic container, and three times the amount of alumina balls were added. The alumina balls used were 3-10 mm in size. After adding the weighed powder and balls, the mixture was dry-mixed in a ball mill at a speed of 170-230 rpm for 8 hours. The resulting dry powder was then pressure-sintered using a hot press. Under these conditions, the internal vacuum condition of the hot press was 30 MPa, the heating rate was 3-7°C, the maximum temperature was 830°C, and the temperature was maintained for approximately 2 hours before furnace cooling. The sintered body of Comparative Example 5 was prepared by the process described above.

[0120] Experimental Example 1: Evaluating the microstructure changes of molded bodies after heat treatment

[0121] The microstructure changes of sintered bodies under heat treatment were evaluated using molded bodies with and without added metal oxides.

[0122] Figure 1 To illustrate the change in microstructure of the sintered body of the molded body using the addition of metal oxide (M3) in Example 9 according to the heat treatment temperature, Figure 2 This image shows the change in microstructure of the sintered body of the molded body of Comparative Example 1 without added metal oxide (M3) according to the heat treatment temperature.

[0123] Experimental results confirm that, compared to molded bodies without added metal oxides, molded bodies with added metal oxides exhibit relatively larger microstructural changes with heat treatment temperature. For example, they suppress pores in the sintered body (see below). Figures 1-2 ).

[0124] Experimental Example 2: Evaluation of the evaluation particle size of sintered bodies

[0125] The microstructure changes and average grain size of sintered bodies subjected to heat treatment under pressure and pressureless conditions were evaluated respectively.

[0126] Specifically, the sintered body of Example 9, prepared under pressureless conditions, and Comparative Example 5, prepared under pressure, were used as samples. Both samples were cut into 10×10×10 mm pieces using a metal blade, then polished for several minutes using SiC sandpaper (#100 to #2000) before being prepared using a 1 μm paste and ultrafine fiber cloth. The samples were then immersed in hydrogen peroxide at approximately 200°C for 1 minute and heat-treated to expose the surface of the tissue.

[0127] Furthermore, for the determination of the average particle size of the sintered body, each sample was observed at the same magnification of 1000 using an FE-SEM (Hitachi, S-4800). Five lines were randomly plotted on the measured image, and calculations were performed on approximately 100 particles using the linear intercept method according to the following mathematical formula 2.

[0128] Mathematical formula 2

[0129] D = 1.56 × C / MN

[0130] In the above formula, D = average particle size, C = total length of the line, M = magnification, and N = number of particles on the line.

[0131] Figure 3 as well as Figure 4 SEM images of the fracture surfaces and polished surfaces of the powder microstructure of the mixed raw materials, the microstructure of the pressureless sintered body prepared in Example 9, and the microstructure of the pressure sintered body prepared in Comparative Example 5 are shown respectively.

[0132] As follows Figures 3-4 As shown, the pressure-sintered body of Comparative Example 5 is formed by forcibly agglomerating the initial raw materials together under high pressure, resulting in almost no increase in particle size. In contrast, it can be seen that the particle size of the sintered body of Example 9 increases through reaction, and in particular, it is known that the reaction is advantageous because the particles coalesce in the interaction between dissimilar elements.

[0133] Experiment Example 3: Evaluating the physical properties of molded bodies

[0134] The physical properties of the molded articles prepared in Examples 1 to 17 and Comparative Examples 1 to 4 are evaluated as follows.

[0135] Specifically, the diameter (D) and height (T) of each molded body were measured using vernier calipers, and the weight (Mass) was measured using a scale. The relative density was calculated by converting the amount of each added weight to a volume percentage and the level compared to the theoretical density to a percentage, and the results are shown in Table 2. The density of the measured samples was calculated as weight / volume, and when multiple identical samples were prepared, it is expressed as an average value.

[0136] For reference, the samples in Table 2 below have low relative densities because they were not sintered, and the relative densities of the sintered bodies after sintering (heat treatment) are 96%.

[0137] Table 2

[0138]

[0139] Experiment Example 4: Evaluation of the density and shrinkage rate of sintered bodies

[0140] After heat treatment of the samples prepared in Examples 1 to 17 and Comparative Examples 1 to 4, the changes in the physical properties of each sintered body were measured.

[0141] (1) Evaluate the density after heat treatment

[0142] The density of the heat-treated sintered body was evaluated using the same methods as in Experiment 3 above. For example, the results of the relative density calculated by measuring the diameter, height, and weight of the heat-treated sintered body are shown below. Figures 5 to 8 middle.

[0143] The experimental results show that in Examples 1 to 17, as the sintering temperature was increased from 1200℃ to 1600℃, the relative density also increased significantly (see Example 1). Figures 5 to 7 In contrast, in Comparative Examples 1 to 4, it was found that the relative density of the molded body was lower or similar to that of the sintering temperature. Furthermore, it was found that the slope of temperature increase was low, and in Comparative Example 1, even with further temperature increases, the relative density did not increase further (see...). Figure 8 Furthermore, the sintering density of Comparative Example 5 was only 95-97%.

[0144] (2) Evaluate the shrinkage rate before and after heat treatment.

[0145] The shrinkage rate was calculated by measuring the diameter and height of the molded body before heat treatment and the sintered body after heat treatment, respectively. The calculated shrinkage rate results are shown below. Figures 9 to 12 middle.

[0146] The experimental results showed that, in Comparative Examples 1 to 4, the rate of change in shrinkage due to heat treatment was not significant (see [reference]). Figure 12 In contrast, it can be seen that in the cases of Examples 1 to 17, the rate of change in the shrinkage rate of the sintered body caused by heat treatment is relatively high (see Example 1). Figures 9 to 11 ).

[0147] Experiment Example 5: Evaluating the resistivity of sintered bodies

[0148] The resistivity characteristics of each sintered body sample prepared in Examples 1 to 17 and Comparative Examples 1 to 5 were evaluated.

[0149] Specifically, samples within the intermediate temperature range of 1500°C were used as sintered body samples. The resistivity of the samples was measured using a Loresta-GX MCP-T700 product (Mitsubishi Chemical Co., Ltd.), and the results are shown in Table 3 below.

[0150] Table 3

[0151]

[0152] As shown in Table 3 above, it can be confirmed that the sintered bodies of Examples 1 to 17, which contain the specified metal oxide as an additive, have excellent resistivity characteristics compared with the sintered bodies of Comparative Examples 1 to 5, which do not contain the above-mentioned additives.

[0153] Experiment Example 6: Analysis and Evaluation of the Crystal Structure of Sintered Bodies

[0154] The crystal structure characteristics of each sintered body sample prepared in Example 9, Comparative Example 1 and Comparative Example 5 were evaluated.

[0155] Specifically, in Example 9 and Comparative Example 1, samples sintered at an intermediate temperature range of 1500°C were cut into 10×10×3 mm (T) pieces for measurement. Furthermore, in Comparative Example 5, samples sintered at 830°C were cut into the same size pieces for measurement. The X-ray diffraction equipment used for the measurements was a Pro MRD product (Malvern Panalytical), with a 2-theta range of 20–60 degrees.

[0156] As follows Figure 13 As shown, unlike the sintered bodies of Comparative Example 1 and Example 9, the sintered body of Comparative Example 5, prepared by pressure sintering, has a crystal structure that is more similar to the original mixed powder.

[0157] Experiment Example 7: Evaluating the thin-film resistivity and reflectivity characteristics of thin films

[0158] The properties of the films prepared from the sintered bodies of Examples 1, 9 and Comparative Example 1 are evaluated below.

[0159] Specifically, 4-inch targets prepared with the compositions of the examples and comparative examples were vapor-deposited using a DC sputtering machine. To form a unit film. Furthermore, a 4-inch Cu target is sputtered using a DC sputtering machine. A double film was prepared by sputtering onto the aforementioned unit film. The results of the thin-film resistivity and reflectivity characteristics of the prepared films are shown below. Figure 14 as well as Figure 15 middle.

[0160] Figure 14 The graph shows the thin-film resistivity characteristics of the unit films prepared from the components of Example 1, Example 9, and Comparative Example 1. It can be seen that the films of Example 1 and Example 9 have significantly lower thin-film resistivity characteristics than those of Comparative Example 1.

[0161] and, Figure 15 The graph shows the results of measuring the average reflectance of the double films prepared using the components of Example 1, Example 9, and Comparative Example 1 in the visible light range (380–740 nm wavelength). The double film of Comparative Example 1 has an average reflectance of more than about 10%, while the double films of Example 1 and Example 9 have an average reflectance of less than 9%, indicating that they have superior reflectance characteristics.

[0162] Experiment Example 8: Evaluating the Chemical Stability of Thin Films

[0163] The double films prepared from the components of Example 9 and Comparative Example 1 were subjected to a photoresist (PR) process. During the PR process, samples for etching evaluation were prepared by exposure to form linewidths of 50 nm to 100 nm. The results are shown in Table 4 below. Figure 16 middle.

[0164] Table 4

[0165] Damage level (nm) of molybdenum oxide thin film Angle after etching (°) Comparative Example 1 1.75 51.5 Example 9 0 48.6

[0166] Figure 16 The etching evaluation results are for the dual-mode fabricated using the components of Example 9 and Comparative Example 1. Figure 16 Part (a) is an image of Example 9. Figure 16 Part (b) is the image of Comparative Example 1.

[0167] As shown in Table 4 above and Figure 16As shown in section (a), compared to Comparative Example 1, the film of Example 9 exhibits significantly lower film damage and a lower angle after the etching process. Therefore, it can be confirmed that the oxide sintered body of the present invention has excellent chemical stability.

Claims

1. An oxide sintered body, characterized in that, Include: Molybdenum oxide M1 contains at least one of MoO2 and MoO3; Niobium oxide M2; as well as The first oxide M3-1 or CaCO3 is used as the dopant M3, wherein the first oxide M3-1 contains at least one alkaline earth metal selected from Ca and Mg. The content of molybdenum oxide M1 is 70% or more by weight relative to the total weight of the sintered body. The aforementioned oxide sintered body is formed by pressureless sintering of a mixture of molybdenum oxide M1, niobium oxide M2, and the dopant M3. The relative density is above 80%, and the resistivity is 1×10⁻⁶. -2 Below Ω·cm.

2. The oxide sintered body according to claim 1, characterized in that, The aforementioned dopant M3 contains CaCO3 and MgO.

3. The oxide sintered body according to claim 1, characterized in that, The aforementioned dopant M3 further comprises: The second oxide M3-2 contains one or more elements selected from the group consisting of Co, Si, Y and Ga.

4. The oxide sintered body according to claim 3, characterized in that, The aforementioned second oxide M3-2 comprises one or more selected from the group consisting of Co3O4, SiO2, Y2O3 and Ga2O3.

5. The oxide sintered body according to claim 1, characterized in that, Based on the above sintered body of 100% by weight, the content of the dopant M3 is greater than 0% by weight and less than 10.0% by weight.

6. The oxide sintered body according to claim 1, characterized in that, Based on 100% by weight of the above-mentioned oxide sintered body, the contents of the above-mentioned molybdenum oxide M1 and the above-mentioned niobium oxide M2 ​​are 90.0% by weight or more and less than 100% by weight, and the content ratio of the above-mentioned molybdenum oxide M1 to the above-mentioned niobium oxide M2 ​​is 50:50 to 90:10 by weight.

7. The oxide sintered body according to claim 1, characterized in that, The average particle size D of the oxide sintered body formed by pressureless sintering is 50 The following conditions of Equation 1 must be met: Formula 1: G N / G P ≥3.0 In the above formula, G N The average particle size D of the oxide sintered body subjected to pressureless heat treatment at 1400±200℃ for 2 hours is given. 50 , G P The average particle size D of the oxide sintered body subjected to pressure heat treatment at 30 MPa and 830 °C for 2 hours is given. 50 .

8. A sputtering target, characterized in that, It comprises the oxide sintered body according to any one of claims 1 to 7.

9. An oxide thin film, characterized in that, Formed from the sputtering target as described in claim 8.

10. A thin-film transistor, characterized in that, The oxide thin film of claim 9 may be used as any one of the gate layer, source layer and drain layer.

11. A display device, characterized in that, It includes the oxide thin film according to claim 9.

12. A method for preparing the oxide sintered body according to claim 1, characterized in that, include: Step (i) prepare a raw material powder containing molybdenum oxide M1, niobium oxide M2 ​​and a first oxide M3-1 or CaCO3 as a dopant M3, wherein the first oxide M3-1 contains at least one alkaline earth metal selected from Ca and Mg. Step (ii): Prepare a molded body using the above-mentioned raw material powder; as well as Step (iii) involves preparing a sintered body by subjecting the above-mentioned molded body to pressureless heat treatment at a temperature of 1200–1600°C for 1–20 hours.

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