Precious metal vapor deposition material

Abstract

The present disclosure addresses the problem of providing a noble metal vapor deposition material which is used in a vacuum vapor deposition method and which is capable of suppressing the occurrence of a sudden boiling phenomenon during vacuum vapor deposition. A vapor deposition material comprising a noble metal, in which Fe is less than 10% by weight when a 50 [mu] m * 50 [mu] m area of the surface of the vapor deposition material is analyzed using energy dispersive X-ray spectroscopy, and Fe is 10 ppm by weight or less when analyzed using ICP emission spectroscopy.

Description

Technical Field

[0001] The present disclosure relates to a noble metal evaporation material used in a vacuum evaporation method. Background Art

[0002] Vacuum deposition is a film-forming technique that involves heating a deposition material in a vacuum, converting it into gaseous molecules and adhering to a substrate to form a thin film. Vacuum deposition is widely used in the formation of components such as electronic components, semiconductor devices, optical thin films, magnetic devices, LEDs, organic ELs, and LCDs.

[0003] When a deposition material is filled into a crucible and melted using an electron beam or other method, sudden boiling occurs, causing molten droplets to adhere to the film. Regarding this issue, Reference 1 discloses a technique for preventing sudden boiling by reducing impurities in the deposition material. Furthermore, Patent Document 2 describes a technique for preventing the adhesion of molten droplets by washing the deposition material surface with aqua regia.

[0004] The applicant has previously disclosed a gold deposition material for use in vacuum deposition, which is a technology capable of suppressing sudden boiling during vacuum deposition. For example, Patent Document 3 discloses a deposition material with a surface roughness Ra of 10 μm or less and a reduced number of microcracks with an area-equivalent circle diameter of 0.1 mm or greater. Furthermore, Patent Document 4 discloses a deposition material with an average crystal grain size of 0.1 mm or greater, an oxygen content of 10 wtppm or less, and a hydrogen content of 5 wtppm or less.

[0005] [Prior art literature]

[0006] [Patent Document]

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 1-180961

[0008] Patent Document 2: Japanese Patent Application Laid-Open No. 2018-123389

[0009] Patent Document 3: International Publication No. 2022 / 070432

[0010] Patent Document 4: International Publication No. 2022 / 070433 Summary of the Invention

[0011] [Problems to be Solved by the Invention]

[0012] An object of the present disclosure is to provide a noble metal deposition material used in a vacuum deposition method, which can suppress the occurrence of a sudden boiling phenomenon during vacuum deposition.

[0013] [Means for solving the problem]

[0014] The gist of the present disclosure is as follows. [1]

[0016] A vapor deposition material composed of precious metals.

[0017] When analyzing a 50 μm×50 μm area of ​​the surface of the vapor deposition material using energy dispersive X-ray spectroscopy, Fe is less than 10% by weight.

[0018] When analyzed by ICP emission spectrometry, the Fe content was 10 wtppm or less. [2]

[0020] A vapor deposition material composed of precious metals.

[0021] When analyzing the surface of the vapor deposition material in an area of ​​50 μm × 50 μm using energy dispersive X-ray spectroscopy, the Si content was less than 10% by weight.

[0022] When analyzed by ICP emission spectrometry, the Si content was 10 wtppm or less. [3]

[0024] A vapor deposition material composed of precious metals.

[0025] When a surface analysis of a 50 μm×50 μm area of ​​the vapor deposition material is performed using energy dispersive X-ray spectroscopy, C is 10 wt % or less.

[0026] When analyzed by non-dispersive infrared absorption method, the C content was 10 ppm by weight or less.

[0027] [Effects of the Invention]

[0028] According to the present disclosure, the sudden boiling phenomenon can be effectively suppressed when the precious metal vapor deposition material melts. As a result, it is expected that particles adhering to the substrate will be reduced, thus contributing to improved product yield. DETAILED DESCRIPTION

[0029] The precious metal evaporation material used in the vacuum evaporation method usually uses a precious metal raw material with a purity of 99.9% by weight or more as a raw material, and the precious metal raw material is melted in a ceramic crucible such as alumina or a carbon crucible in the atmosphere. After melting, the molten precious metal is flowed into a mold to make an ingot. The obtained ingot is drawn (wire drawing) using lubricating oil and then cut into a predetermined length to make particles (rods). Afterwards, the surface of the particles is cleaned with acid or an organic solvent to remove impurities attached to the surface. By going through the above process, a granular precious metal evaporation material with relatively few impurities can be produced.

[0030] However, even when using such precious metal evaporation materials, which are relatively low in impurities, sudden boiling can occur during the initial deposition phase. This can increase the pre-deposition time before actual deposition, necessitating changes to the deposition equipment settings, and thus reducing production efficiency. Precious metals are particularly expensive, so increasing the pre-deposition time increases costs. Furthermore, sudden boiling can contaminate the equipment and crucible, increasing the frequency of equipment cleaning.

[0031] The present inventors analyzed the surface and interior of the deposition material and discovered that large amounts of iron-based components (iron or its compounds), silicon-based components (silicon or its compounds), and carbon-based components (carbon or its compounds) are present on and within the material. The presence of large amounts of these components (hereinafter sometimes referred to as impurities) increases the risk of bumping, starting from these components. Furthermore, the inventors discovered that reducing these impurities can suppress bumping during vacuum deposition.

[0032] In this disclosure, the amount of impurities present on the surface of the vapor-deposited material is represented by the results of surface analysis using energy-dispersive X-ray spectroscopy, while the amount of impurities present within the vapor-deposited material is represented by the results of analysis using ICP emission spectroscopy or non-dispersive infrared absorption spectroscopy. Furthermore, because surface analysis using energy-dispersive X-ray spectroscopy in this disclosure results in significant variation between samples, ten samples were randomly selected, and the center of each sample was measured. The average of these ten results was used as the amount of impurities present on the surface of the vapor-deposited material.

[0033] One embodiment of the present disclosure is a deposition material composed of a precious metal, wherein Fe is 10% by weight or less when analyzing a 50 μm x 50 μm area of ​​the deposition material surface using energy dispersive X-ray spectroscopy, and 10 ppm by weight or less when analyzing using inductively coupled plasma emission spectrometry. Iron-based components, such as compounds and iron oxides primarily composed of iron (Fe), are believed to be present in the raw materials used and to be contaminated from components of the equipment used during wire drawing.

[0034] By reducing the Fe content to less than 10 wt% on the surface of the precious metal vapor-deposited material and to less than 10 wtppm within the material, bumping during vapor deposition can be effectively suppressed. The Fe content on the surface of the precious metal vapor-deposited material is preferably less than 5 wt% and more preferably less than 1 wt%. Furthermore, the Fe content within the precious metal vapor-deposited material is preferably less than 5 wtppm and more preferably less than 1 wtppm.

[0035] One embodiment of the present disclosure is a deposition material composed of a precious metal, wherein Si content is less than 10% by weight when analyzing a 50 μm x 50 μm area of ​​the deposition material surface using energy dispersive X-ray spectroscopy, and is 10 wtppm or less when analyzing using an ICP emission spectrometer. Silicon-based components are compounds primarily composed of silicon (Si) or silicon oxides, and are believed to be naturally present in the raw materials used and to be mixed in from the ambient atmosphere (air) or the crucible used during melting.

[0036] By reducing the Si content to less than 10 wt % on the surface of the precious metal vapor-deposited material and to less than 10 wt ppm within the material, bumping during vapor deposition can be effectively suppressed. On the surface of the precious metal vapor-deposited material, the Si content is preferably less than 5 wt % and more preferably less than 1 wt %. Furthermore, within the precious metal vapor-deposited material, the Si content is preferably less than 5 wt ppm and more preferably less than 1 wt ppm.

[0037] One embodiment of the present disclosure is a deposition material composed of a precious metal, wherein a carbon content of 10% by weight or less is determined by surface analysis of a 50 μm x 50 μm area of ​​the deposition material using energy dispersive X-ray spectroscopy, and a carbon content of 10 ppm by weight or less is determined by non-dispersive infrared absorption analysis. Carbon-based components are compounds primarily composed of carbon (C), and are believed to be incorporated into carbon crucibles and molds, or into lubricating oil used during wire drawing.

[0038] By reducing the carbon content to 10% by weight or less on the surface of the precious metal vapor-deposited material and 10 ppm by weight or less in the interior, bumping during vapor deposition can be effectively suppressed. On the surface of the precious metal vapor-deposited material, the carbon content is preferably 5% by weight or less, and more preferably 1% by weight or less.

[0039] The vapor deposition material according to the embodiments of the present disclosure only needs to have at least one of Fe, Si, and C within the above range, more preferably any two of Fe, Si, and C within the above range, and even more preferably all of Fe, Si, and C within the above range. When these impurities are present in large quantities on the surface of the vapor deposition material, they can cause bumping, so the source of the impurities is not particularly limited.

[0040] In the present disclosure, the evaporation material is composed of any one of the precious metals gold (Au), platinum (Pt), palladium (Pd), and silver (Ag). High-purity products with a purity of 99.9% or more by weight or 99.99% or more by weight can generally be used. Impurities are a cause of sudden boiling, so using high-purity products can suppress sudden boiling to a certain extent. However, high-purity products are expensive, so they can be appropriately changed according to the application and purpose.

[0041] The following describes in detail the method for manufacturing the vapor deposition material of this embodiment. It should be noted that the manufacturing conditions, etc., are illustrative and are not intended to be limiting. Furthermore, to avoid unnecessary ambiguity in the disclosed manufacturing method, descriptions of known manufacturing processes and processing actions are omitted.

[0042] (Casting process)

[0043] The precious metal raw material with a purity of 99.9% by weight or more is subjected to EB (electron beam) melting or shell melting. In general precious metal casting, ceramic crucibles and carbon crucibles are used, but when these crucibles are used, impurities are mixed in. Therefore, it is preferred to use EB melting using a copper crucible with less pollution, or shell melting with less pollution from the crucible. The melting temperature is preferably set to be above 50°C and below 200°C from the melting point of the target precious metal. After the precious metal raw material is melted in a vacuum or in an atmosphere containing an inert gas (vacuum degree: 1000~0.001Pa), the molten metal is flowed into a water-cooled copper mold and then cooled at room temperature to produce an ingot (casting) of the precious metal. It should be noted that in the method of this process, contamination from the crucible and the mold can be prevented, but impurities from the raw material remain.

[0044] (Forging process, rolling process)

[0045] In order to achieve a predetermined shape that can be processed in the wire drawing process of the next step, forging and rolling are performed. In this process, impurity components may be mixed in from device components, etc., but by heating at a temperature range of 300°C or more and 100°C lower than the melting point of the target precious metal while performing forging and rolling, impurity components mixed in from the raw material or from device components, etc. can be concentrated on the surface. The heating temperature is preferably 300°C or more. On the other hand, when heating at a temperature exceeding the melting point of the target precious metal, part of the precious metal will melt, so it is preferably set to a temperature of 100°C or more lower than the melting point of the target precious metal. During forging and rolling, impurity components sometimes adhere to the surface from device components and the surroundings, but by heating at a predetermined temperature during these processes, they can be concentrated on the surface of the precious metal.

[0046] (Wire drawing process, cutting)

[0047] The resulting precious metal (forged or rolled product) is then drawn (wire-processed) into a wire shape. Heat treatment is performed before or after this drawing process, or during the drawing process, to concentrate impurities from the interior toward the surface. The optimal heat treatment temperature range varies depending on the type of deposition material, and it is preferably adjusted as follows.

[0048] Gold (Au) heat treatment temperature: 300°C or higher and 900°C or lower

[0049] Heat treatment temperature of platinum (Pt): 500°C or higher and 1500°C or lower

[0050] Palladium (Pd) heat treatment temperature: 300°C or higher and 1000°C or lower

[0051] Silver (Ag) heat treatment temperature: 300°C or higher and 800°C or lower

[0052] During the wire drawing process, impurities from the equipment and the ambient atmosphere sometimes adhere to the surface, but they are almost non-existent inside. Therefore, these components can be removed by pickling, which will be described later. It should be noted that lubricating oil is usually used during wire drawing, but it can cause contamination from carbon-based components, so its use is preferably avoided. After drawing, the wire is cut into a predetermined length. The cutting length varies depending on the equipment, etc., and is not particularly limited. For example, it can be set to 10 mm or more, 20 mm or more, or 30 mm or more.

[0053] (Pickling and cleaning process)

[0054] After cutting, the precious metal (evaporation material) is acid-washed and cleaned to remove impurities concentrated on its surface. Examples of acid solutions include aqua regia and hydrochloric acid. Subsequently, the precious metal is cleaned with acetone and pure water. This process allows the desired precious metal vapor-deposited material (rod shape) to be produced.

[0055] Example

[0056] Next, examples and comparative examples of the present invention will be described. It should be noted that the following examples are representative examples, and the present invention is not necessarily limited to these examples, but should be interpreted within the scope of the technical concept described in the specification.

[0057] The present examples and comparative examples were analyzed using the following apparatuses and the like.

[0058] (Surface analysis using energy dispersive X-ray spectroscopy)

[0059] Analyzer: Aztec Advanced Ultim Max40

[0060] Oxford Company System

[0061] Accelerating voltage: 10kV or 15kV

[0062] Magnification: 200 to 20,000 times

[0063] Irradiation current: 7-10μA

[0064] Objective lens aperture: 3

[0065] Analysis area: 100 μm × 100 μm

[0066] Working distance (WD): 10mm

[0067] Detector: Secondary electrons

[0068] Resolution: 127eV

[0069] Measurement method: Prepare a sample with a diameter of 2 mm and a length of 20 mm. Because surface analysis can vary greatly between samples, 10 samples are randomly selected and the center of each sample is measured. The average of the 10 measured values ​​is then calculated.

[0070] (Analysis using ICP emission spectroscopy)

[0071] Analytical equipment: AMETEK ICP-OES, SPECTROGREEN FMD46

[0072] Sample: Take about 2 g from the evaporation material, dissolve it in aqua regia, filter it, and then adjust the volume.

[0073] (Analysis using non-dispersive infrared absorption method)

[0074] Analyzer: EMIA-920V, a carbon and sulfur analyzer manufactured by Horiba, Ltd.

[0075] Combustion-supporting materials: W 1.5g, Sn 3.5g

[0076] (Evaluation of sudden boiling phenomenon)

[0077] When sudden boiling occurs during electron beam melting of the evaporation material, the evaporation material adheres to the inside of the evaporation device and the weight of the evaporation material decreases. Therefore, the sudden boiling phenomenon can be evaluated by measuring the weight loss of the evaporation material after melting. About 40g of the evaporation material is placed in a copper crucible and the vacuum degree is 1×10 -1 Electron beam melting was performed under the conditions of 0.01 wt % (0.01 wt %), electron beam irradiation power: 6 kW, and electron beam irradiation time: 2 minutes, and the weight loss after melting was measured. It should be noted that under these melting conditions, almost no loss due to evaporation was caused. In addition, a weight loss rate of less than 0.01 wt % was judged as ◎ (very good), a weight loss rate of 0.01 wt % or more and less than 0.1 wt % was judged as ○ (good), a weight loss rate of 0.1 wt % or more and less than 1 wt % was judged as △ (poor), and a weight loss rate of 1 wt % or more was judged as × (very poor).

[0078] (Example 1: Au evaporation material)

[0079] Au raw material with a purity of 99.99% or more by weight is electron beam melted in a water-cooled copper crucible at a vacuum of 10 Pa to produce an ingot. The resulting ingot is forged and rolled at 300°C to a 50mm square. It is then heat-treated at 500°C and drawn simultaneously. No lubricant is used during the drawing process, and the filaments are refined to a diameter of approximately 2mm. After drawing, the wires are cut into 20mm lengths, the surface is pickled with aqua regia, rinsed with acetone, and dried.

[0080] The surface of the sample after drawing was observed with SEM (JSM-7000E, manufactured by JEOL Ltd.: 100x magnification). Energy dispersive X-ray spectroscopy was used for surface analysis, and the results showed that Fe, Si, and C were all less than 10 wt %. In addition, ICP emission spectroscopy was used for analysis, and the results showed that Fe and Si were less than 1 wt ppm. Non-dispersive infrared absorption was used for analysis, and the results showed that C was less than 10 wt ppm. The obtained sample was evaluated for the sudden boiling phenomenon, and the weight loss rate was less than 0.01%, which was very good.

[0081] (Comparative Example 1: Au Vapor Deposition Material)

[0082] Au raw material with a purity of 99.99% or more by weight is atmospherically melted in a carbon crucible to produce an ingot. The resulting ingot is forged and rolled into a 50 mm square. It is then drawn without heat treatment. During the drawing process, the filaments are thinned without the use of lubricating oil. After drawing, the wires are cut into 20 mm lengths, then the surface is pickled with aqua regia, rinsed with acetone, and dried.

[0083] Surface analysis of the drawn sample using energy-dispersive X-ray spectroscopy, as in Example 1, revealed that Fe, Si, and C were all above 10% by weight. Analysis using ICP emission spectroscopy revealed that Fe and Si were 18 wtppm and 12 wtppm, respectively. Analysis using a non-dispersive infrared absorption spectrometer revealed that C was 30 wtppm. The resulting sample was evaluated for sudden boiling, and the weight loss was 0.2% by weight, a poor result.

[0084] (Example 2: Pt evaporation material)

[0085] Platinum raw material with a purity of 99.95% or more by weight is melted in a water-cooled copper crucible at a vacuum of 0.1 Pa to produce an ingot. The resulting ingot is forged and rolled at 900°C to a 50mm square. It is then heat-treated at 800°C and drawn. No lubricant is used during the drawing process, and the filaments are refined to a diameter of approximately 2mm. After drawing, the wires are cut into 20mm lengths, the surface is pickled with aqua regia, rinsed with acetone, and dried.

[0086] The surface of the drawn sample was analyzed using energy-dispersive X-ray spectroscopy as in Example 1. The results showed that Fe, Si, and C were all below 10% by weight. Furthermore, analysis using ICP emission spectroscopy revealed that Fe and Si were 3 wtppm and 2 wtppm, respectively. Analysis using non-dispersive infrared absorption spectroscopy revealed that C was less than 10 wtppm. The resulting sample was evaluated for sudden boiling, and the weight loss rate was 0.02%, which was satisfactory.

[0087] (Comparative Example 2: Pt Vapor Deposition Material)

[0088] A Pt raw material with a purity of 99.95% by weight was atmospherically melted in a ceramic crucible to produce an ingot. The resulting ingot was forged and rolled into a 50 mm square. It was then drawn without heat treatment. During the drawing process, the filaments were thinned without the use of lubricating oil. After drawing, the wires were cut into 20 mm lengths, then the surface was pickled with aqua regia, then rinsed with acetone, and dried.

[0089] Surface analysis of the drawn sample using energy-dispersive X-ray spectroscopy, as in Example 1, revealed that Fe, Si, and C were all above 10% by weight. Analysis using ICP emission spectroscopy revealed that Fe and Si were 15 wtppm and 20 wtppm, respectively. Analysis using non-dispersive infrared absorption spectroscopy revealed that C was 20 wtppm. The resulting sample was evaluated for sudden boiling, and the weight loss was 1.5% by weight, a very poor result.

[0090] (Example 3: Pd evaporation material)

[0091] A Pd raw material with a purity of 99.9% by weight or more is melted in a water-cooled copper crucible at a vacuum of 500 Pa with argon gas introduced to produce an ingot. The resulting ingot is forged and rolled at 1000°C to a 50mm square. It is then heat-treated at 600°C and drawn. No lubricating oil is used during the drawing process, and the filaments are thinned to a diameter of about 2mm. After drawing, the wires are cut into 20mm lengths, the surface is pickled with aqua regia, then rinsed with acetone and dried.

[0092] The surface of the drawn sample was analyzed using energy dispersive X-ray spectroscopy in the same manner as in Example 1. The results showed that both Fe and Si were less than 10% by weight, and C was 10% by weight. Furthermore, analysis using ICP emission spectroscopy revealed that Fe and Si were 5 wtppm and 8 wtppm, respectively. Analysis using non-dispersive infrared absorption spectroscopy revealed that C was 10 wtppm. The resulting sample was evaluated for sudden boiling, and the weight loss rate was 0.09%, which was satisfactory.

[0093] (Comparative Example 3: Pd Vapor Deposition Material)

[0094] A Pd raw material with a purity of 99.9% or more by weight was atmospherically melted in a ceramic crucible to produce an ingot. The resulting ingot was forged and rolled into a 50 mm square. It was then drawn without heat treatment. During the drawing process, the filaments were thinned without the use of lubricating oil. After drawing, the wires were cut into 20 mm lengths, then the surface was pickled with aqua regia, then rinsed with acetone, and dried.

[0095] Surface analysis of the drawn sample using energy-dispersive X-ray spectroscopy, as in Example 1, revealed that Fe, Si, and C were all above 10% by weight. Analysis using ICP emission spectroscopy revealed that Fe and Si were 30 wtppm and 45 wtppm, respectively. Analysis using non-dispersive infrared absorption spectroscopy revealed that C was 20 wtppm. The resulting sample was evaluated for sudden boiling, and the weight loss was 2.7% by weight, a very poor result.

[0096] (Example 4: Ag evaporation material)

[0097] Ag raw material with a purity of 99.99% or more by weight is electron beam melted in a water-cooled copper crucible at a vacuum of 10 Pa to produce an ingot. The resulting ingot is forged and rolled at 500°C to a 50mm square. It is then heat-treated at 300°C and drawn. No lubricant is used during the drawing process, and the wires are thinned to a diameter of approximately 2mm. After drawing, the wires are cut into 20mm lengths, the surface is pickled with aqua regia, rinsed with acetone, and dried.

[0098] Surface analysis of the drawn sample using energy-dispersive X-ray spectroscopy, as in Example 1, revealed that Fe, Si, and C were all less than 10% by weight. Furthermore, analysis using ICP emission spectroscopy revealed that Fe and Si were both less than 1 ppm by weight. Analysis using non-dispersive infrared absorption spectroscopy revealed that C was less than 10 ppm by weight. The resulting sample was evaluated for sudden boiling, and the weight loss was less than 0.01%, a very good result.

[0099] (Comparative Example 4)

[0100] Ag raw material with a purity of 99.99% by weight or greater is atmospherically melted in a carbon crucible to produce an ingot. The resulting ingot is forged and rolled into a 50 mm square. It is then drawn without heat treatment. During the drawing process, the wire is thinned without the use of lubricating oil. After drawing, the wire is cut into 20 mm lengths, then the surface is pickled with aqua regia, rinsed with acetone, and dried.

[0101] Surface analysis of the drawn sample using energy-dispersive X-ray spectroscopy, as in Example 1, revealed that Fe, Si, and C were all at least 10% by weight. Analysis using ICP emission spectroscopy revealed Fe and Si to be 12 wtppm and 15 wtppm, respectively. Analysis using non-dispersive infrared absorption spectroscopy revealed C to be 50 wtppm. The resulting sample was evaluated for sudden boiling, and the weight loss was 0.5 wt%, a poor result.

[0102] [Table 1]

[0103]

[0104] Industrial applicability

[0105] According to the present disclosure, the sudden boiling phenomenon can be effectively suppressed when the precious metal vapor deposition material is melted. This can be expected to reduce particles adhering to the substrate. Therefore, it can help improve the yield rate of the product. The precious metal vapor deposition material of the present disclosure is useful for forming components in electronic components, semiconductor devices, optical films, magnetic devices, LEDs, organic ELs, LCDs, etc.

Claims

1. A vapor deposition material composed of precious metals, When analyzing a 50 μm×50 μm area of ​​the surface of the vapor deposition material using energy dispersive X-ray spectroscopy, Fe is less than 10% by weight. When analyzed by ICP emission spectrometry, the Fe content was 10 wtppm or less.

2. A vapor deposition material composed of a precious metal, When analyzing the surface of the vapor deposition material in an area of ​​50 μm × 50 μm using energy dispersive X-ray spectroscopy, the Si content was less than 10% by weight. When analyzed by ICP emission spectrometry, the Si content was 10 wtppm or less.

3. A vapor deposition material composed of a precious metal, When a surface analysis of a 50 μm×50 μm area of ​​the vapor deposition material is performed using energy dispersive X-ray spectroscopy, C is 10 wt % or less. When analyzed by non-dispersive infrared absorption method, the C content was 10 ppm by weight or less.

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