Yttrium ingot and sputtering target using the same

Abstract

Provided are a yttrium sputtering target material with low particle generation and a yttrium ingot from which the yttrium sputtering target material can be obtained; the yttrium sputtering target material has high plasma resistance and can obtain a low resistance capable of achieving a high film forming rate. A yttrium ingot characterized in that the content of fluorine atoms is 10 wt% or less, the surface roughness of the sputtering surface when the target material is made is 10 nm or more and 2 μm or less, and the number of pores with a diameter of 100 μm or more in the yttrium ingot is 0.1 / cm 2 Below, the relative density is 96% or more.

Description

Technical Field

[0001] The present invention relates to an yttrium ingot for film formation and a sputtering target using the same. Background Art

[0002] In the manufacture of semiconductor equipment, micro-machining using dry etching with highly corrosive halogen gases such as fluorine and chlorine or their plasma is one of the important processes. It is known that these corrosive gases or plasmas will corrode and damage the components of semiconductor manufacturing equipment, and the resulting particles will cause the quality of the equipment to deteriorate. Most of the components of semiconductor manufacturing equipment are consumables, and in order to prevent the reduction in yield and quality caused by the above-mentioned damage, they are replaced regularly. Due to the downtime associated with component replacement and device maintenance, the device operating rate will decrease, and the deterioration of productivity has also become a problem. In the semiconductor manufacturing process, it is required to develop a component with excellent plasma resistance and gas corrosion resistance.

[0003] With the miniaturization of semiconductor elements, the plasma used in the dry etching process is densified. As a material that can withstand this high-density plasma, yttrium oxide has attracted much attention. As a manufacturing method for parts comprising yttrium oxide, from the viewpoint of manufacturing cost and large-scale, the method of forming yttrium oxide film on a substrate by a spraying method as described in patent document 1 has become mainstream as an industrial process. However, since the ceramic powder is melted and rapidly solidified in the spraying method to form a film, surface defects and pores can exist on the film surface. When there is such a defect, in addition to the deterioration of plasma resistance, it can also cause the generation of particles, so a method for forming a dense yttrium oxide film with high efficiency is sought.

[0004] Among them, as one of the film forming methods other than the spraying method, sputtering can be cited. Sputtering is a method of depositing a film on a substrate arranged at an opposite position by causing positive ions such as Ar ions to physically collide with a target material arranged at a cathode, releasing the material constituting the target material through the collision energy, and depositing a film on a substrate arranged at an opposite position, such as direct current sputtering (DC sputtering), high frequency sputtering (RF sputtering), and alternating current sputtering (AC sputtering). It is generally believed that compared with film formation using the spraying method, film formation using the sputtering method can be performed under a low temperature process, can suppress the generation of defects such as pores, and form a denser film. In addition, in film formation using the sputtering method, it is also possible to form an oxide or nitride film by using reactive sputtering that introduces gases such as oxygen and nitrogen into the sputtering chamber. For example, a film of yttrium oxide can be formed on a substrate by DC discharging a yttrium target and introducing reactive DC sputtering of oxygen during sputtering as in Non-Patent Document 1, but the quality of the film formed varies greatly depending on the sputtering conditions. However, although a yttrium target with a purity of 99.5% is used for film formation in Non-Patent Document 1, the correlation between the physical properties of the sputtering target such as density and purity and the sputtering characteristics, and the relationship with the quality of the film formed by sputtering are not fully studied. Therefore, further research is needed on the physical properties of the yttrium target, the sputtering characteristics, and the characteristics of the formed film.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2006-307311

[0008] Non-patent literature

[0009] Non-patent document 1: P. Lei et al. Surface & Coatings Technology 276 (2015) 39-46 Summary of the invention

[0010] Problem that the invention aims to solve

[0011] An object of the present invention is to provide a yttrium ingot used for a yttrium sputtering target having few particles, high plasma resistance and low resistance capable of achieving a high film formation rate, and a sputtering target using the yttrium ingot.

[0012] Solutions for solving problems

[0013] The present inventors conducted intensive research on the desired yttrium ingot for the yttrium sputtering target, and as a result, discovered a yttrium ingot that can obtain a yttrium sputtering target with less particle generation, high plasma resistance and low resistance that can achieve a high film formation rate, thereby completing the present invention.

[0014] That is, the aspects of the present invention are as follows.

[0015] (1) An yttrium ingot characterized in that the content of fluorine atoms is 10% by weight or less, the surface roughness of the sputtering surface when used as a target material is 10 nm or more and 2 μm or less, and the number of pores with a diameter of 100 μm or more in the yttrium ingot is 0.1 pores / cm 2 Below, the relative density is 96% or more.

[0016] (2) The yttrium ingot according to (1), characterized in that the average grain size (D50) is 3000 μm or less.

[0017] (3) The yttrium ingot according to (1) or (2), characterized in that when the content of rare earth elements is set to REwt% and the content of metal elements other than rare earth elements is set to Mwt%, 98≤100-RE-M<99.999.

[0018] (4) The yttrium ingot according to (1), wherein the content of fluorine atoms is 0.05 wt% or more and 10 wt% or less.

[0019] (5) The yttrium ingot according to (4), which contains yttrium oxyfluoride.

[0020] (6) The yttrium ingot according to (4) or (5), wherein when the content of the rare earth element is REwt%, 98≤100-RE<99.999.

[0021] (7) The yttrium ingot according to any one of (4) to (6), wherein the average grain size (D50-2) is 100 μm or less.

[0022] (8) The yttrium ingot according to any one of (4) to (7), wherein the volume resistivity is 1 Ω·cm or less.

[0023] (9) A yttrium sputtering target, comprising the yttrium ingot according to any one of (1) to (8).

[0024] (10) The sputtering target according to (9), comprising a backing plate and a yttrium ingot.

[0025] (11) The yttrium sputtering target according to (9) or (10), wherein the bonding rate between the backing plate and the yttrium ingot is 90% or more.

[0026] (12) A method for producing an yttrium oxide film, characterized by performing sputtering using the yttrium sputtering target described in any one of (9) to (11).

[0027] Effects of the Invention

[0028] The yttrium ingot of the present invention has a smooth surface and a small surface oxide layer, and therefore, when used as a sputtering target, stable discharge characteristics can be obtained without being affected by oxidized high-resistance portions, and high productivity can be obtained. DETAILED DESCRIPTION

[0029] Hereinafter, the present invention will be described in detail.

[0030] The present invention provides an yttrium ingot for an yttrium sputtering target material with less particle generation, characterized in that the content of fluorine atoms is 10wt% or less, the surface roughness of the sputtering surface when the target material is made is 10nm or more and 2μm or less, and the number of pores with a diameter of 100μm or more in the yttrium ingot is 0.1 / cm 2 Below, the relative density is 96% or more.

[0031] The content of fluorine atoms is 10 wt% or less. If it exceeds 10 wt%, the resistivity of the ingot increases, and high-productivity DC discharge cannot be performed.

[0032] The surface roughness of the sputtering surface when the target is made is 10 nm or more and 2 μm or less, preferably 10 nm or more and 1 μm or less, and more preferably 10 nm or more and 0.3 μm or less. By setting it to 2 μm or less, the specific surface area of ​​the surface layer can be reduced, and the surface oxygen of yttrium that is easily oxidized can be reduced, thereby preventing the occurrence of arc discharge during film formation and abnormal discharge caused by increased resistivity. By setting it to 10 nm or more, the microparticles generated in trace amounts during sputtering can be attached to the target surface again, and the microparticles can be inhibited from attaching to the film.

[0033] The number of pores with a diameter of 100 μm or more is 0.1 / cm 2 Below, preferably 0.01 pieces / cm 2 Below, more preferably 0.005 pieces / cm 2 If there are many pores with a diameter of 100 μm or more, this may cause abnormal discharge or particles during sputtering.

[0034] The relative density is 96% or more, preferably 98% or more, more preferably 99% or more, and further preferably 99.8% or more. When it is less than 96%, it is easy to break, especially in large ingots, and it is impossible to produce ingots with good yield. In addition, when such ingots are used and high power is applied during sputtering, it is easy to break during discharge, which becomes a cause of reducing the productivity of the film forming process, so it is not preferred.

[0035] The average grain size (D50) of the yttrium ingot is preferably 3000 μm or less, preferably 1 μm or more and 2000 μm or less, more preferably 1 μm or more and 1500 μm or less, and particularly preferably 1 μm or more and 1000 μm or less.

[0036] For the impurity content of the yttrium ingot, when the content of rare earth elements is set to REwt% and the content of metal elements other than rare earth elements is set to Mwt%, it is preferably 98≤100-RE-M<99.999, more preferably 99≤100-RE-M<99.999, and further preferably 99.9≤100-RE-M<99.999. By reducing the amount of impurities, the purity of the yttrium sputtering target is further improved, thereby suppressing abnormal discharge and particle generation. When a higher purity is made, the purification process becomes complicated and the production cost becomes high, which is not preferred. The inventors of the present invention have studied the correlation between the amount of impurities and the discharge characteristics within the above range, and determined the purity that can be appropriately used in sputtering film forming.

[0037] The volume resistivity of the yttrium ingot is preferably 0.00001 Ω·cm or more and 1 Ω·cm or less, and more preferably 0.00001 Ω·cm or more and 0.001 Ω·cm or less. Yttrium is very easy to oxidize and oxidizes naturally in the atmosphere. Yttrium oxide formed by oxidation is an insulator, so it may cause abnormal discharge during sputtering discharge, especially in the case of film formation by DC discharge. By setting the volume resistivity within the above range, stable discharge characteristics can be obtained in any of DC sputtering, RF sputtering, and AC sputtering.

[0038] The yttrium ingot can be ground into a plate-like shape using a machining machine such as a surface grinder, a cylindrical grinder, a lathe, a cutter, or a machining center.

[0039] The manufacturing method of the yttrium ingot of the present invention is not particularly limited. In the high-purification melt solidification used for vacuum melting and EB (electron beam) melting, pores with a diameter of more than 100 μm are easily generated due to gasification during melting, so it is difficult to directly obtain an ingot with few pores. Therefore, it is preferred to compress the ingot made by the melting method by hot isostatic pressing (HIP method) to crush the pores. However, since yttrium is a material that is easily oxidized, it is preferred to seal the periphery with metal. The HIP temperature is preferably below 1000°C. In addition, yttrium is relatively brittle, so the pressure is preferably below 100 MPa. Thus, a yttrium ingot with a diameter of more than 100 μm and few pores can be obtained.

[0040] In order to form an ingot for yttrium sputtering target material with high plasma resistance and low resistance capable of achieving high film formation rate, the yttrium ingot of the present invention is preferably an yttrium ingot having a fluorine atom content of 0.05wt% to 10wt% (hereinafter also referred to as "fluorine-containing yttrium ingot"), more preferably 0.05wt% to 8wt%, 0.05wt% to 5wt%, 0.1wt% to 4wt%, and more preferably 0.2wt% to 3wt%. When the content is less than 0.05wt%, the plasma resistance brought about by the addition effect of fluorine will not be improved.

[0041] The content expressed in fluorine atoms refers to the weight ratio of fluorine atoms in the entire yttrium ingot, which can be measured using glow discharge mass spectrometry (GDMS) or inductively coupled plasma (ICP).

[0042] The fluorine-containing yttrium ingot preferably contains yttrium oxyfluoride. By containing yttrium oxyfluoride, the situation where yttrium oxyfluoride cannot be generated due to composition deviation during sputtering can be suppressed. There are many compounds as yttrium oxyfluoride (YOF), but it is preferably present mainly in the form of trigonal YOF. Trigonal YOF has high stability, so the final mechanical properties are high. In addition, its existence ratio is preferably 0.1% to 35% in terms of area ratio, more preferably 0.1% to 20% and further preferably 0.1% to 10%. By setting it to this range, stable discharge can be achieved, and a film containing yttrium fluoride can be produced.

[0043] The fluorine-containing yttrium ingot contains a specific amount of fluorine. For the impurity content other than fluorine, when the content of rare earth elements is set to REwt%, it is preferably 98≤100-RE<99.999, more preferably 99≤100-RE<99.999, and further preferably 99.9≤100-RE<99.999. By reducing the amount of rare earth impurities, the purity of the yttrium target is further improved, thereby suppressing abnormal discharge and particle generation. When a higher purity is made, the purification process becomes complicated and the production cost becomes high, which is not preferred. The inventors of the present invention have studied the correlation between the amount of impurities and the discharge characteristics within the above range, and determined the purity that can be appropriately used in sputtering film forming. The rare earths refer to Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, and Er.

[0044] The average particle size (D50-2) of the fluorine-containing yttrium ingot is preferably less than 100 μm, preferably more than 0.1 μm and less than 100 μm, preferably more than 0.1 μm and less than 75 μm, and particularly preferably more than 0.1 μm and less than 20 μm. By uniformly dispersing the fluorine compound of yttrium in the yttrium ingot, the average particle size is refined, and an yttrium ingot that maintains high strength even if it contains yttrium oxyfluoride is formed. The sputtering target using such an ingot can form a film at high speed with high power. In addition, since the fluorine is evenly dispersed, the composition unevenness in the film can also be reduced.

[0045] The volume resistivity of the fluorine-containing yttrium ingot is preferably less than 1Ω·cm, more preferably more than 0.00001Ω·cm and less than 1Ω·cm, and more preferably more than 0.00001Ω·cm and less than 0.001Ω·cm. Yttrium is very easy to oxidize and oxidizes naturally in the atmosphere. The yttrium oxide formed by oxidation is an insulator, so it will cause abnormal discharge during sputtering discharge, especially when film formation is performed by DC discharge. By setting the volume resistivity within the above range, stable discharge characteristics can be obtained in any of DC sputtering, RF sputtering, and AC sputtering.

[0046] The fluorine-containing yttrium ingot can be ground into a plate-like shape using a machining machine such as a surface grinder, a cylindrical grinder, a lathe, a cutter, or a machining center.

[0047] The method for producing the fluorine-containing yttrium ingot is not particularly limited, but in order to mix a certain amount of fluorine, it is preferably produced by a method of performing a reduction treatment with yttrium fluoride followed by melt solidification such as vacuum melting or EB melting.

[0048] Yttrium fluoride is a relatively stable substance, and can be further reduced to generate yttrium oxyfluoride. By controlling the reduction state at this time to retain the required amount of fluorine, it is possible to synthesize an yttrium ingot in which fluorine is uniformly dispersed and contains a specific amount of fluorine. When chloride is used as the starting material, fluorine cannot be uniformly contained, so it is not preferred.

[0049] In melt solidification such as vacuum melting and EB melting, due to gasification during melting, coarse pores of more than 100 μm are easily generated, so it is difficult to directly obtain an ingot with few pores. Therefore, it is preferred to compress the ingot made by the melting method by hot isostatic pressing (HIP method) to crush the pores. However, since yttrium is a material that is easily oxidized, it is preferred to seal the periphery with metal. The HIP temperature is preferably below 1000°C. In addition, yttrium is brittle, so the pressure is preferably below 100 MPa. Thus, an yttrium ingot with few pores of more than 100 μm can be obtained.

[0050] The yttrium ingot of the present invention can be made into a sputtering target comprising the yttrium ingot. As a method for manufacturing a sputtering target, the sputtering target can be obtained by bonding to a backing plate or a backing tube comprising oxygen-free copper, titanium, etc. using indium solder or the like as needed, wherein a sputtering target comprising a backing plate and the yttrium ingot is preferably made.

[0051] The surface roughness of the yttrium ingot side of the bonding surface between the yttrium ingot and the back plate (surface roughness of the bonding portion) is preferably 10 nm or more and 2 μm or less, more preferably 10 nm or more and 1 μm or less, and more preferably 10 nm or more and 0.3 μm or less. By setting it to less than 2 μm, the specific surface area of ​​the surface layer can be reduced, and the surface oxygen of the yttrium that is easily oxidized can be reduced, thereby preventing the peeling of the oxidized part during bonding. In addition, in the treatment of the bonding surface in an oxidized state, the treatment cannot be performed due to the peeling of the oxide layer, and the final bonding rate will be reduced. By setting it to more than 10 nm, the surface and the substrate treatment surface are well engaged, and the bonding force is further improved, so that high-power discharge can be performed. However, due to the aggravation of surface oxidation, it is preferred to grind the surface after target materialization.

[0052] The processing method for adjusting the surface roughness of the sputtering surface is not particularly limited, and a milling machine, numerical control machine (numerical control, NC), surface grinder, grinder, etc. can be used. The surface layer of yttrium is easily oxidized, so it is preferably processed after the target material is made, for example, after the back plate is bonded to the yttrium ingot. Thus, surface oxidation during the bonding process can be suppressed, and impurities in the surface layer can be removed by processing again. Preferably, vacuum packaging is quickly performed after the processing of the sputtering surface of the sputtering target is implemented. Thus, oxidation of the surface layer can be suppressed.

[0053] The back plate is used to efficiently mount the ingot of the film material part of the sputtering target on the sputtering device. In addition, in order to prevent the ingot part from overheating during sputtering, the back plate part is cooled by water cooling, etc. The bonding material uses indium and indium alloys that have high thermal conductivity and are easy to use as solder.

[0054] In addition, the material of the back plate is not particularly limited, and copper, stainless steel, titanium, etc. can be used.

[0055] In a sputtering target comprising a back plate and a yttrium ingot, the bonding rate between the yttrium ingot and the back plate is preferably 90% or more. More preferably, it is 95% or more, and further preferably 98% or more. By setting the bonding rate to the above, the heat of the target generated during sputtering can be rapidly diffused to prevent the sputtering target from being overheated and causing the solder to dissolve. The surface of the yttrium ingot oxidizes over time, so it is difficult to bond with the solder due to the oxide film. Therefore, the oxide layer on the yttrium surface should be removed before joining, and the surface treatment should be performed quickly. The treatment method is not particularly limited, and it is preferred to perform evaporation, plating, ultrasonic welding, etc. on a metal that fits well with the solder. Thus, the solder and the yttrium ingot can be bonded without peeling off. It is preferably within 3 hours from oxide treatment to surface treatment.

[0056] The bonding rate between the yttrium ingot and the back plate can be determined, for example, by ultrasonic flaw detection. When the bonding rate is determined by ultrasonic flaw detection, it is preferred to use a simulated defect sample having a simulated void hole in the center of a plate of a specified size, and adjust the measurement conditions. The measurement sensitivity is adjusted so that the area of ​​the detected defect is consistent with the area of ​​the specified void hole. The raw material of the simulated defect sample is preferably the same as the raw material of the sputtering target. The distance between the ultrasonic incident surface of the simulated defect sample and the bottom surface of the void hole is preferably the same as the distance between the ultrasonic incident surface of the sputtering target and the bonding layer.

[0057] Alternatively, a film may be produced by sputtering using the obtained yttrium sputtering target.

[0058] Example

[0059] The present invention will be described in more detail below by way of examples, but the present invention is not limited thereto. In addition, each measurement in the present example was performed as follows.

[0060] (1) Relative density

[0061] The relative density was determined by the bulk density measured by the Archimedean method according to JIS R 1634 and divided by the actual density of metal yttrium (4.47 g / cm 3 ), and thus the relative density is calculated.

[0062] (2) Porosity measurement

[0063] The whole image is measured using X-ray transmission images, and the positions of pores larger than 100 μm are extracted and their number and size are measured. The number and size are converted to pores / cm based on the measured area. 2 .

[0064] (3) Volume resistivity

[0065] The results were obtained by measuring three or more locations using a four-probe method and averaging the results.

[0066] (4) Average particle size (D50) / (D50-2)

[0067] After mirror polishing and electrolytic etching, the particles were observed under an optical microscope, and the average particle size (D50) was measured by the diameter method based on the obtained structure image. The particles were observed at at least 3 points and measured for 300 or more particles. The average value here refers to the 50% particle size.

[0068] The mirror surface was polished and observed using a scanning electron microscope-electron beam backscatter diffraction (SEM-EBSD) (SEM: manufactured by JEOL, EBSD: manufactured by Oxford), and the arithmetic mean particle size (D50-2) was determined based on the obtained image. At least three points were observed. For the particles, particles with a crystal orientation tilt of more than 5° were counted as one particle, and the diameter was calculated after approximating a sphere. The average value here refers to the 50% particle size.

[0069] (5) Method for measuring adhesion rate

[0070] The adhesion ratio was calculated by measuring using an ultrasonic flaw detector.

[0071] (6) Determination of surface roughness (Ra)

[0072] The surface roughness Ra was measured using a surface roughness measuring device manufactured by Mitsutoyo.

[0073] (7) Analysis of fluorine content and metal impurities

[0074] The analysis values ​​of samples cut out from an arbitrary portion after grinding 1 mm or more from the surface of the sintered yttrium ingot were used as measurement data.

[0075] Determination method: Glow discharge mass spectrometry (GDMS)

[0076] (Example 1)

[0077] A predetermined yttrium ingot subjected to a porosity treatment was prepared and measured, and good results were obtained. The properties of the yttrium ingot are shown in Table 1. In addition, the results of the measurement of impurities contained are shown in Table 2.

[0078] Relative density: 100.3%

[0079] Porosity: 0.004 / cm 2

[0080] Surface roughness: 430nm (grinded with a #400 file)

[0081] Before joining, the joint surface was polished with a #400 file to form a specified roughness, and then indium solder was quickly applied (within 1 hour) with an ultrasonic soldering iron to perform surface treatment, and then bonded to the backing plate with indium solder. The properties of the yttrium target are shown in Table 1.

[0082] (Examples 2-3)

[0083] A yttrium ingot and a yttrium target were produced in the same manner as in Example 1 except that the surface treatment method was changed. Table 1 shows the properties of the yttrium ingot.

[0084] In Example 2, a #1000 file was used, and in Example 3, a #3000 file was used, and the surfaces were ground to have the surface roughness shown in Table 1.

[0085] (Comparative Example 1)

[0086] In Comparative Example 1, the portion to be sputtered was ground with a #80 file at the ingot stage, and the bonding surface was ground with a #400 file before bonding to form a predetermined roughness, and then indium solder was quickly applied with an ultrasonic soldering iron (within 1 hour) to perform surface treatment. Then, yttrium ingots and yttrium sputtering targets were produced without vacuum packaging.

[0087] The adhesion ratio of the sputtering targets of Examples 1 to 3 and Comparative Example 1 was measured. The adhesion ratio was measured using an ultrasonic imaging inspection device (model: AT LINE, manufactured by Hitachi Construction Machinery Precision Technology Co., Ltd.) and an ultrasonic flaw detector (model: 13-0508-T). Prior to the measurement, a simulated sample of the same material as the sputtering target was used, and the sensitivity was adjusted so that the area of ​​the detected defect was consistent with the area of ​​the simulated hole of the simulated sample. The measurement conditions are as follows.

[0088] Gain (intensity of sound waves): 15dB

[0089] Measuring distance: 0.61mm

[0090] Echo level: ≥3.1V

[0091] Ultrasonic radiation: target side

[0092] The adhesion rate of the sputtering target was measured using an analysis program attached to the device. The measurement results are shown in Table 1.

[0093] The sputtering targets of Examples 1 to 3 were mounted on a DC sputtering device and formed into films on a quartz substrate. Thereafter, annealing treatment was performed in an oxygen atmosphere to obtain yttrium oxide films. The sputtering conditions were as follows.

[0094] Target size: Φ101.6×6mmt

[0095] Power: 200W

[0096] Sputtering gas: Ar

[0097] Air pressure: 0.5Pa

[0098] Film thickness: 5μm

[0099] When the sputtering target of Comparative Example 1 was sputtered, the surface roughness of the sputtering surface of the yttrium target was large, which led to the accelerated oxidation and the high surface resistance, making it impossible to perform DC discharge.

[0100] The number of arc discharges during film formation is shown in Table 3. Arc discharges are counted by counting the number of times a voltage drop of 20 V or more occurs from the film formation voltage. In Examples 1 to 3, the number of arc discharges is as low as <1 time / hour. Since the number of arc discharges is small, the generation of particles can be reduced.

[0101] [Table 1]

[0102]

[0103] [Table 2]

[0104]

[0105] [Table 3]

[0106]

[0107] (Comparative Example 2)

[0108] The same treatment as in Example 1 was performed except that a predetermined yttrium ingot was prepared and the porosity reduction treatment was not performed. Table 4 shows the properties of the obtained ingot.

[0109] (Comparative Example 3)

[0110] The properties of the obtained yttrium ingot are shown in Table 4.

[0111] [Table 4]

[0112]

[0113] (Example 4)

[0114] Yttrium fluoride was reduced by Li-Mg to obtain an yttrium ingot containing fluorine-containing yttrium oxide. A yttrium ingot that was further subjected to a porosity reduction treatment was prepared and measured, and good results were obtained. The properties of the yttrium ingot are shown in Table 5. In addition, the results of the metal impurities contained are shown in Table 6.

[0115] Relative density: 100.3%

[0116] Content in terms of fluorine atoms: 0.6wt%

[0117] Before joining, the joint surface was polished to a predetermined roughness, and then indium solder was quickly applied using an ultrasonic soldering iron to perform surface treatment, and then bonded to the backing plate using indium solder. Table 5 shows the properties of the yttrium target.

[0118] (Examples 5-6)

[0119] Yttrium ingots and sputtering targets of Examples 5 and 6 containing yttrium oxyfluoride were prepared in the same manner as in Example 4, except that the amount of yttrium fluoride added was changed. Table 5 shows the properties of the yttrium ingot and the target.

[0120] (Example 7)

[0121] Yttrium powder (3N block product manufactured by Japan Yttrium Corporation) and yttrium oxyfluoride powder (grade: 5LW230 manufactured by Japan Yttrium Corporation) were put into a Cu crucible at a weight ratio of 90:10. After heating and melting in an arc melting furnace, the mixture was cooled to obtain an yttrium ingot containing yttrium oxyfluoride. The obtained yttrium ingot was processed into a specified shape and then mounted on a backing plate in the same manner as in Example 4 to prepare a sputtering target. The properties of the yttrium ingot and the target are shown in Table 5.

[0122] (Example 8)

[0123] Yttrium oxyfluoride was added to the yttrium ingot containing yttrium oxyfluoride prepared in Example 7 so that the final yttrium:yttrium oxyfluoride ratio reached 50:50, and the mixture was put into a Cu crucible. After heating and melting in an arc melting furnace, the mixture was cooled to obtain an yttrium ingot containing yttrium oxyfluoride. The mixture was mounted on a backing plate in the same manner as in Example 4 to prepare a sputtering target. The properties of the yttrium ingot and the target are shown in Table 5.

[0124] (Example 9)

[0125] Yttrium oxyfluoride was added to the yttrium ingot containing yttrium oxyfluoride prepared in Example 7 so that the final yttrium:yttrium oxyfluoride ratio reached 40:60, and the ingot was put into a Cu crucible. After heating and melting in an arc melting furnace, the ingot was cooled to obtain an yttrium ingot containing yttrium oxyfluoride. The ingot was mounted on a backing plate in the same manner as in Example 4 to prepare a sputtering target. The properties of the yttrium ingot and the target are shown in Table 5.

[0126] (Comparative Example 4)

[0127] A fluorine-free yttrium ingot synthesized by molten salt electrolysis using chloride was prepared and mounted on a backing plate in the same manner as in Example 4 to produce a sputtering target. Table 5 shows the properties of the yttrium ingot and the target.

[0128] (Comparative Example 5)

[0129] A yttrium ingot and a sputtering target of Comparative Example 5 containing yttrium oxyfluoride were obtained in the same manner as in Example 4, except that the mixing ratio of the yttrium powder to the yttrium oxyfluoride powder was 30:70 in Example 7. Table 5 shows the properties of the yttrium ingot and the target.

[0130] The adhesion rates of the sputtering targets of Examples 4 to 9 and Comparative Examples 4 and 5 were measured. The adhesion rate was measured using an ultrasonic imaging inspection device (model: AT LINE, manufactured by Hitachi Construction Machinery Precision Technology Co., Ltd.) and an ultrasonic flaw detector (model: 13-0508-T). Prior to the measurement, a simulated sample of the same material as the sputtering target was used, and the sensitivity was adjusted so that the area of ​​the detected defect was consistent with the area of ​​the simulated hole of the simulated sample. The measurement conditions are as follows.

[0131] Gain (intensity of sound waves): 15dB

[0132] Measuring distance: 0.61mm

[0133] Echo level: ≥3.1V

[0134] Ultrasonic radiation: target side

[0135] The adhesion rate of the sputtering target was measured using the analysis program attached to the device. The measurement results are shown in Table 5.

[0136] The sputtering targets of Examples 4 to 7 were mounted on a DC sputtering device and formed into films on a quartz substrate. Thereafter, annealing treatment was performed in an oxygen atmosphere to obtain yttrium oxide films. The sputtering conditions were as follows.

[0137] Target size: Φ101.6×6mmt

[0138] Power: 200W

[0139] Sputtering gas: Ar

[0140] Air pressure: 0.5Pa

[0141] Film thickness: 5μm

[0142] When the sputtering target of Comparative Example 4 was sputtered, oxidation of the sputtering surface of the yttrium target was advanced and the bonding rate was low, so DC discharge could not be performed.

[0143] When the sputtering target of Comparative Example 5 was sputtered, the volume resistivity of the target was high, so DC discharge could not be performed.

[0144] The samples obtained in Examples 4 to 7 were placed in an etching chamber capable of plasma resistance evaluation, and the etching rate was calculated based on the film thickness change before and after plasma irradiation. The plasma resistance evaluation conditions were as follows.

[0145] Sample size: 20mm×20mm

[0146] Power: 300W

[0147] Etching gas: Ar+CF4+O2

[0148] Processing time: 4 hours

[0149] Table 7 shows the results of the plasma resistance evaluation.

[0150] The etching rates of the yttrium films of Examples 4 to 7 were extremely low with respect to the quartz substrate, and good plasma resistance characteristics were obtained.

[0151] [Table 5]

[0152]

[0153] [Table 6]

[0154]

[0155] [Table 7]

[0156]

[0157] (Reference Example 1)

[0158] A yttrium sputtering target was prepared in the same manner as in Example 1, except that the bonding surface was polished using a #80 file in Reference Example 1.

[0159] (Comparative Example 6)

[0160] After the bonding surface of the yttrium ingot was polished for 72 hours, the same treatment as in Example 1 was performed.

[0161] The adhesion ratio of the sputtering target materials of Reference Example 1 and Comparative Example 6 was measured. The adhesion ratio was measured using an ultrasonic imaging inspection device (model: AT LINE, manufactured by Hitachi Construction Machinery Precision Technology Co., Ltd.) and an ultrasonic flaw detector (model: 13-0508-T). Before the measurement, a simulated sample of the same material as the sputtering target was used, and the sensitivity was adjusted so that the area of ​​the detected defect was consistent with the area of ​​the simulated hole of the simulated sample. The measurement conditions are as follows.

[0162] Gain (intensity of sound waves): 15dB

[0163] Measuring distance: 0.61mm

[0164] Echo level: ≥3.1V

[0165] Ultrasonic radiation: target side

[0166] The adhesion rate of the sputtering target was measured using the analysis program attached to the device. The measurement results are shown in Table 8.

[0167] When the sputtering target of Reference Example 1 was sputtered, the surface roughness of the bonding surface was large, peeling occurred during the bonding process, and the bonding area was small, so the heat conduction was poor and DC discharge could not be performed.

[0168] When the sputtering target of Comparative Example 6 was sputtered, it was assumed that the oxide layer peeled off, the adhesion ratio was low, and DC discharge could not be performed.

[0169] [Table 8]

[0170]

[0171] While the invention has been described in detail and with reference to specific embodiments, it will be apparent to one skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.

[0172] It should be noted that this application is based on Japanese patent applications filed on April 23, 2020 (Japanese Patent Application No. 2020-076659), Japanese patent applications filed on April 23, 2020 (Japanese Patent Application No. 2020-076665), Japanese patent applications filed on May 14, 2020 (Japanese Patent Application No. 2020-085139), and Japanese patent applications filed on May 14, 2020 (Japanese Patent Application No. 2020-085189), and the entirety thereof is incorporated herein by reference. In addition, all references cited herein are incorporated in their entirety.

Claims

1. A yttrium ingot, characterized in that: The content of fluorine atoms is 0.05wt% or more and 10wt% or less, the surface roughness of the sputtering surface when the target is made is 10nm or more and 2μm or less, and the number of pores with a diameter of 100μm or more in the yttrium ingot is 0.1 / cm 2 Below, the relative density is above 96%.

2. The yttrium ingot according to claim 1, characterized in that The average particle size D50 measured by a diameter method based on the obtained structure image observed with an optical microscope was 3000 μm or less.

3. The yttrium ingot according to claim 1 or 2, characterized in that: When the content of rare earth elements is defined as REwt% and the content of metal elements other than rare earth elements is defined as Mwt%, 98≤100-RE-M<99.

999.

4. The yttrium ingot according to claim 1 or 2, characterized in that: The content in terms of fluorine atoms is 0.05 wt % or more and 8 wt % or less. The yttrium ingot according to claim 1 or 2, comprising yttrium oxyfluoride.

6. The yttrium ingot according to claim 1 or 2, wherein: When the content of the rare earth element is set to REwt%, 98≤100-RE<99.

999. 7 . The yttrium ingot according to claim 1 , wherein the average grain size D50-2 measured based on an image obtained by observation using a scanning electron microscope-electron beam backscatter diffraction is 100 μm or less.

8. The yttrium ingot according to claim 1 or 2, which has a volume resistivity of 1 Ω·cm or less.

9. A yttrium sputtering target, characterized in that: It comprises the yttrium ingot according to any one of claims 1 to 8. 10 . The yttrium sputtering target according to claim 9 , comprising a backing plate and a yttrium ingot.

11. The yttrium sputtering target according to claim 10, characterized in that The bonding rate between the back plate and the yttrium ingot is over 90%.

12. A method for manufacturing an yttrium oxide film, characterized in that: Sputtering is performed using the yttrium sputtering target according to any one of claims 9 to 11.

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