Film forming material for members for plasma etching apparatus and method for producing the same

Abstract

Provided are a Y2O3-containing film formation material suitable as a member for a plasma etching apparatus and having high plasma resistance, and a method for producing the same. A film formation material characterized by being a film formation material containing a solid solution including Y2O3 and a metal oxide containing only ZrO2, HfO2, or Nb2O5, wherein, in the case where the metal oxide is ZrO2, the content of ZrO2 is 2 to 12 mol%, in the case where the metal oxide is HfO2, the content of HfO2 is 4 to 24 mol%, and in the case where the metal oxide is Nb2O5, the content of Nb2O5 is 1 to 8 mol%, and the crystal structure of the solid solution has a hexagonal crystal structure of Y2O3.

Description

Technical Field

[0001] The present invention relates to film-forming materials for components of plasma etching apparatus suitable for use in semiconductor manufacturing, film-forming methods using film-forming materials, methods for manufacturing plasma etching apparatus, and methods for manufacturing film-forming materials. Background Technology

[0002] Plasma etching is used in semiconductor manufacturing during the process of fabricating circuits on wafers. Before plasma etching begins, the wafer is coated with a photoresist or hard mask (usually oxide or nitride) to expose the circuit pattern in a subsequent photolithography process (patterning process). In plasma etching, the patterned wafer is subjected to plasma etching, thereby selectively removing the material to be etched (etching process).

[0003] This patterning and etching process is repeated multiple times in semiconductor manufacturing. It should be noted that in plasma etching, not only is there a physical sputtering effect, but also plasma using halogen gases such as fluorine and chlorine is used to irradiate the wafer, combining the chemical sputtering effect to remove the material to be etched.

[0004] In plasma etching, to form highly integrated semiconductor circuits, it is necessary to create roughly vertical contours, thus releasing high-energy and high-density ions and free radicals from the plasma. Consequently, not only the wafer being etched, but also the material of the inner surface of the etching cavity is consumed by the plasma irradiation. The resulting particles adhere to the circuitry on the wafer, thus contributing to the reduced yield of semiconductor chip manufacturing.

[0005] The cavities used for plasma etching are typically made of metallic materials such as aluminum alloys, which have low resistance to exposure to halogen-based gas plasmas. Therefore, a plasma-resistant material is used to coat the cavity to suppress the abrasion and particle generation caused by the plasma. Examples of plasma-resistant materials used to coat the cavity include ceramic materials. Metal oxides and other ceramic materials exhibit good durability against plasma exposure due to their complex crystal structures and high chemical stability.

[0006] Among ceramic materials, yttrium oxide (Y2O3) is particularly known for its high resistance to halogen-containing plasmas used in the fabrication of semiconductor devices. For example, Patent Document 1 proposes a plasma processing container internal component with excellent resistance to plasma erosion by covering the surface of a substrate such as a metal, ceramic, or carbon material inside the plasma processing container with a Y2O3 spray coating.

[0007] Furthermore, Patent Document 2 proposes a method for coating a surface of a semiconductor processing device or the like with a precursor oxide that forms a solid solution coating containing Y₂O₃ through a spraying process, by flame spraying, thermal spraying, or plasma spraying, thereby obtaining a coating with plasma resistance and low electrical resistance. It also proposes using a mixed oxide of at least two other oxides selected from the group consisting of ZrO₂, CeO₂, HfO₂, Nb₂O₅, Sc₂O₃, Nd₂O₃, Sm₂O₃, Yb₂O₃, Er₂O₃, and combinations thereof, as the precursor oxide.

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: Japanese Patent Application Publication No. 2001-164354

[0011] Patent Document 2: Japanese Patent Publication No. 2010-535288 Summary of the Invention

[0012] The problem the invention aims to solve

[0013] In recent years, as is well known, semiconductors used in cutting-edge technologies have become increasingly integrated, requiring linewidths of circuits formed on chips to be below 20nm. Therefore, in plasma etching, tiny particles of tens of nanometers in size, which were previously not a problem, have become an issue, making the requirements for plasma resistance more stringent than before.

[0014] However, based on the research conducted by the inventors, the material described in Patent Document 1 cannot be said to fully meet the high requirements for plasma resistance in recent years.

[0015] Furthermore, the improvement of the Y₂O₃-containing solid solution coating formed by the spraying method described in Patent Document 2 is that, as an electrical property of the coating, its low resistivity results in plasma resistance that is the same as that of Y₂O₃, without any particular improvement. This is evident from Patent Document 2. Specifically, Patent Document 2 reports the erosion rates of the Y₂O₃-containing solid solution samples 1-4 in "Table 1," which are shown in Figure 5. The plasma resistance of these samples 1-4 is better than that of conventional materials such as Al₂O₃, AlN, and ZrO₂, but the same as that of pure Y₂O₃.

[0016] The present invention is proposed under such circumstances, and its object is to provide a suitable Y2O3-containing solid solution film-forming material with superior plasma resistance properties, such as a component for a plasma etching apparatus in a semiconductor manufacturing process, a film-forming method using the film-forming material, a method for manufacturing a component for a plasma etching apparatus, and a method for manufacturing the film-forming material.

[0017] Solution for solving the problem

[0018] In order to achieve the above-mentioned objectives, the inventors studied the plasma resistance of film-forming materials containing Y2O3. As a result, they found that when the film-forming material contains a solid solution containing Y2O3 and a specific metal oxide, and the specific metal oxide is ZrO2, HfO2 or Nb2O5, and the content of these metal oxides in the solid solution is within a specific range, and the solid solution has a hexahedral crystal structure of Y2O3, the plasma resistance of the Y2O3-containing material is improved and the erosion (consumption) rate is reduced.

[0019] Based on the above-mentioned new findings, the present invention has the following features.

[0020] (1) A film-forming material, characterized in that it is a film-forming material containing a solid solution, wherein the solid solution comprises Y2O3 and a metal oxide containing only ZrO2, HfO2 or Nb2O5, wherein when the aforementioned metal oxide is ZrO2, the content of ZrO2 is 2 to 12 mol%, when the aforementioned metal oxide is HfO2, the content of HfO2 is 4 to 24 mol%, and when the aforementioned metal oxide is Nb2O5, the content of Nb2O5 is 1 to 8 mol%, and the crystal structure of the solid solution has a regular hexahedral crystal structure of Y2O3.

[0021] (2) According to the film-forming material described in (1) above, wherein, when the aforementioned metal oxide is ZrO2, the content of ZrO2 is 7 to 12 mol%.

[0022] (3) According to the film-forming material described in (1) above, wherein, when the aforementioned metal oxide is HfO2, the content of HfO2 is 8 to 20 mol%.

[0023] (4) The film-forming material according to (1) above, wherein, when the aforementioned metal oxide is Nb2O5, the content of Nb2O5 is 3 to 7 mol%.

[0024] (5) The film-forming material according to any one of (1) to (4) above, wherein the ratio of Zr, Hf or Nb atoms to Y atoms contained in the aforementioned solid solution is as follows: in 5 randomly selected points of the solid solution contained in the film-forming material, the ratio is within ±5% of the absolute value.

[0025] (6) The film-forming material according to any one of (1) to (5) above, wherein the aforementioned solid solution produces only peaks of the hexahedral crystal structure of Y2O3 in X-ray diffraction (XRD).

[0026] (7) A film-forming method, wherein the film-forming material described in any one of (1) to (6) above is used for spraying.

[0027] (8) A film-forming method, wherein the film-forming material described in any one of (1) to (6) above is used for physical vapor deposition.

[0028] (9) A method for manufacturing a component for a plasma etching apparatus, wherein a protective coating is formed on a substrate using the film-forming method described in (7) or (8) above.

[0029] (10) A method for manufacturing a film-forming material, characterized in that it is a method for manufacturing the film-forming material described in any one of (1) to (9) above.

[0030] A solid solution is formed by heat-treating a mixed powder, wherein the mixed powder is a mixture of Y2O3 powder and a metal oxide powder containing only ZrO2, HfO2 or Nb2O5. If the metal oxide is ZrO2, the mixed powder with a ZrO2 content of 2-12 mol% is heat-treated at 1000-1600°C to form a solid solution. If the metal oxide is HfO2, the mixed powder with a HfO2 content of 4-24 mol% is heat-treated at 1200-1600°C to form a solid solution. If the metal oxide is Nb2O5, the mixed powder with a Nb2O5 content of 1-8 mol% is heat-treated at 1200-1600°C to form a solid solution.

[0031] (11) The method for manufacturing film-forming material according to (10) above, wherein after forming the solid solution, the material is granulated into particles with an average particle size of 15 to 40 μm and heat-treated at a temperature of 1200 to 1500 °C.

[0032] (12) A method for manufacturing a film-forming material, characterized in that it is a method for manufacturing the film-forming material described in any one of (1) to (9) above.

[0033] A mixture containing Y2O3 powder and metal oxide sol containing ZrO2, HfO2 or Nb2O5 is spray-dried and granulated. The resulting spherical particles, which are composed of ZrO2, HfO2 or Nb2O5 particles and Y2O3 particles, are then heat-treated in an oxidizing atmosphere at a temperature of 1000-1500°C to form a solid solution.

[0034] The effects of the invention

[0035] According to the present invention, a Y2O3-containing solid solution film-forming material suitable for forming a cavity or similar device for dry etching using a plasma generated from a gas containing halogens such as fluorine, is provided, which protects the inner surface of the device from the influence of plasma, suppresses dust generated during the process, and has high plasma resistance; a film-forming method using the film-forming material is also provided; and a method for manufacturing the film-forming material is also provided.

[0036] Furthermore, a method for manufacturing components for plasma etching apparatuses, such as cavities for dry etching using plasma generated from gases containing halogens such as fluorine, is provided, which have high plasma resistance. Attached Figure Description

[0037] Figure 1 This represents the three-dimensional relationship between Y atoms and oxygen atoms in the crystal lattice structure of Y₂O₃.

[0038] Figure 2 The state diagram is for the binary system of Y2O3 and ZrO2.

[0039] Figure 3 The state diagram is for a binary system of Y2O3 and HfO2.

[0040] Figure 4 The state diagram is for the binary system of Y2O3 and Nb2O5.

[0041] Figure 5a The image shows the XRD pattern of the solid solution in Example 3.

[0042] Figure 5b The XRD pattern of the solid solution of Comparative Example 3 is shown.

[0043] Figure 6a The image shows the XRD pattern of the solid solution from Example 5.

[0044] Figure 6b The XRD pattern of the solid solution of Comparative Example 5 is shown.

[0045] Figure 7a The image shows the XRD pattern of the solid solution from Example 8.

[0046] Figure 7b The XRD pattern of the solid solution of Comparative Example 7 is shown. Detailed Implementation

[0047] The following provides a detailed description of the methods for implementing this invention. It should be noted that in this specification (including the claims), when numerical ranges are described, the units of the upper and lower limits are the same, for example, "2 mol% to 12 mol%" is described as "2 to 12 mol%", and "1000℃ to 1600℃" is described as "1000 to 1600℃". Sometimes the unit of the lower limit is omitted.

[0048] <Film forming materials>

[0049] The coating formed using the Y2O3-containing solid solution film-forming material of the present invention has high plasma resistance, which is achieved through the following reasons.

[0050] Y₂O₃, the main component of the film-forming material of this invention, is widely used in semiconductor manufacturing processes, as described above, and is known as one of the materials with the highest resistance to fluorine-containing plasmas. Here, as... Figure 1 As shown, although the unit cell of Y₂O₃ is a regular hexahedral structure capable of coordinating 8 oxygen atoms, Y₂O₃ actually coordinates 6 oxygen atoms. The inventors believe that this results in a large number of oxygen vacancies in the crystal, and by using certain methods to configure oxygen in these vacancies and reduce defects, the plasma resistance of Y₂O₃ can be further improved.

[0051] Therefore, the inventors attempted to add other metal oxides to Y₂O₃ to configure oxygen in the aforementioned oxygen vacancies and reduce defects. As a result, the inventors found that when the metal oxide added to Y₂O₃ satisfies the following two conditions a and b, the consumption rate of the metal oxide-Y₂O₃ composite solid solution due to plasma exposure is significantly reduced, and the plasma resistance is improved.

[0052] a. The oxygen in the crystal lattice structure of metal oxides has 8 or 10 coordination points.

[0053] b. Even with the addition of more than 1 mol% of metal oxide relative to Y2O3, the hexahedral crystal structure of Y2O3 is maintained.

[0054] In this invention, the metal oxides added to Y2O3, ZrO2 and HfO2 are metal oxides with 8 oxygen atoms coordinated, and Nb2O5 is a metal oxide with 10 oxygen atoms coordinated.

[0055] It should be noted that, Figure 2 State diagram of the binary system of Y2O3 and ZrO2 Figure 3 State diagram of the binary system of Y2O3 and HfO2 Figure 4The diagrams show the binary system states of Y₂O₃ and Nb₂O₅. These binary system state diagrams suggest that even with the addition of small amounts of ZrO₂, HfO₂, or Nb₂O₅ to Y₂O₃, the hexahedral crystal structure of Y₂O₃ is maintained.

[0056] Furthermore, ZrO2 and HfO2 are metal oxides with eight coordinated oxygen atoms, but they tend to release oxygen atoms due to temperature changes, etc. Therefore, by dissolving ZrO2 or HfO2 in Y2O3, the oxygen atoms released from ZrO2 or HfO2 are placed in the oxygen vacancies of Y2O3, which can reduce defects. However, if a large amount of ZrO2 or HfO2 is added, Y2O3 cannot maintain a hexahedral structure, resulting in reduced plasma resistance.

[0057] Furthermore, Nb₂O₅ is a metal oxide with 10 coordinated oxygen atoms, but it tends to release oxygen atoms due to temperature changes, etc. Therefore, by dissolving Nb₂O₅ in Y₂O₃, the oxygen atoms released from Nb₂O₅ are placed in the oxygen vacancies of Y₂O₃, which can reduce defects. However, if a large amount of Nb₂O₅ is added, Y₂O₃ cannot maintain a hexahedral structure, resulting in reduced plasma resistance.

[0058] Thus, if metal oxides with 8 or 10 oxygen atoms are added to Y₂O₃ in a proportion that maintains the hexahedral crystal structure of Y₂O₃, oxygen is introduced into the oxygen vacancies in the crystal, thereby reducing the defect density and improving the stability of the crystal. The result is believed to be an increased resistance to physical and chemical sputtering.

[0059] The film-forming material of this invention is a material formed by dissolving a metal oxide containing only ZrO2, HfO2, or Nb2O5 in Y2O3. In this case, as mentioned above, the amount of Y2O3 dissolved in the solution is related to plasma resistance and is therefore important. The improvement in plasma resistance of the resulting solid solution decreases when the metal oxide content is low or, conversely, when it is high. It should be noted that in this invention, Y2O3 is sometimes referred to as the main oxide, and the added metal oxide containing only ZrO2, HfO2, or Nb2O5 is referred to as the secondary oxide.

[0060] When the metal oxide is ZrO2, the content of ZrO2 in the solid solution is 2-12 mol%, preferably 7-12 mol%, and more preferably 8-11 mol%.

[0061] When the metal oxide is HfO2, the content of HfO2 in the solid solution is 4–24 mol%, preferably 8–20 mol%, and more preferably 10–16 mol%.

[0062] In addition, when the metal oxide is Nb₂O₅, the content of Nb₂O₅ in the solid solution is 1 to 8 mol%, preferably 3 to 7 mol%, and more preferably 4 to 6 mol%.

[0063] The Y₂O₃-containing solid solution film-forming material of the present invention, which exhibits high plasma resistance, possesses a solid solution crystal structure that, even when the solid solution contains only added metal oxides such as ZrO₂, HfO₂, or Nb₂O₅, exhibits the hexahedral crystal structure of the Y₂O₃ used as a raw material. In this invention, the crystal structure is preferably confirmed using X-ray diffraction (XRD). When the solid solution possesses a hexahedral crystal structure of Y₂O₃, X-ray diffraction (XRD) of the solid solution produces only peaks representing the hexahedral crystal structure of Y₂O₃.

[0064] In this specification, the phrase "peaks appearing only in X-ray diffraction of the hexahedral crystal structure of Y₂O₃" refers to peaks that have the same structure as the hexahedral crystal structure of Y₂O₃, but do not contain peaks of metal oxides dissolved in Y₂O₃. In other words, it means that when the X-ray diffraction pattern of the Y₂O₃-containing solid solution of this invention is performed, peaks are found at the same positions (parallel shifts) as the pattern of the hexahedral structure of Y₂O₃; that is, peaks with the same shape as the pattern of the hexahedral structure of Y₂O₃. It should be noted that the peak sizes in the X-ray diffraction patterns of the two structures do not necessarily need to be the same.

[0065] <Methods for manufacturing film-forming materials>

[0066] The following describes a representative example of the method for manufacturing the Y2O3-containing solid solution film-forming material of the present invention.

[0067] First, ZrO2 powder, HfO2 powder, or Nb2O5 powder, and Y2O3 powder are pulverized / mixed using a device such as a rotary ball mill. Then, they are subjected to high-temperature heat treatment in an atmosphere or inactive atmosphere using an electric furnace to integrate them (e.g., sintering). In other words, there is a process that integrates Y2O3 powder and a mixture of ZrO2 powder, HfO2 powder, or Nb2O5 powder by heat treatment.

[0068] In the case of a mixture of Y₂O₃ powder and ZrO₂ powder, the ZrO₂ content is 2–12 mol%, preferably 7–12 mol%. In the case of a mixture of Y₂O₃ powder and HfO₂ powder, the HfO₂ content is 4–24 mol%, preferably 8–20 mol%. In the case of a mixture of Y₂O₃ powder and Nb₂O₅ powder, the Nb₂O₅ content is 1–8 mol%, preferably 3–7 mol%.

[0069] In the Y2O3-containing solid solution film-forming material of the present invention, the added metal oxide is preferably uniformly dissolved in the film-forming material, and a uniform film-forming material can be obtained according to the following manufacturing method.

[0070] The uniform film-forming material obtained in this invention refers to a film-forming material for which, for each point on the solid solution particles, five points are randomly selected, and the metal atom content ratio of the added metal oxide relative to the composition of Y atoms is calculated. The deviation of the metal atom / Y atom ratio at all five points is within ±5% of the absolute value of the film-forming material. It should be noted that the absolute value here refers to the theoretical value of the metal atom / Y atom ratio assuming that the added metal oxide is uniformly dissolved in the film-forming material.

[0071] For example, in the case of a film-forming material formed by dissolving 10 mol% ZrO2 in Y2O3, the absolute value is 0.111. The uniformity of the film-forming material formed by dissolving 10 mol% ZrO2 in Y2O3 means that the Zr atom / Y atom value is in the range of 0.111 ± 0.00555 in all 5 randomly selected points.

[0072] It should be noted that, as a method for determining the content of metal atoms in a solid solution, one example is the use of an inductively coupled plasma atomic emission spectrometer. By uniformly dissolving the material during the film-forming stage, a uniform solid solution state is maintained even after coating, thus suppressing deviations in plasma resistance within the coating.

[0073] The following explanation illustrates the manufacturing method of Y₂O₃-containing solid solution film-forming materials, using ZrO₂ as an example. The manufacturing method can also be used for materials with HfO₂ or Nb₂O₅ as the metal oxide.

[0074] The purity of the powders used when pulverizing / mixing Y2O3 powder and ZrO2 powder is preferably 99.5% by weight or more. In addition, the average particle size (D50) of these powders supplied to the pulverizing / mixing process is preferably 4 μm or less, and the average particle size of the pulverized / mixed powder is preferably 2 μm or less.

[0075] The average particle size of the ZrO2 powder before heat treatment is preferably less than 1 / 3, and more preferably 1 / 5, of the average particle size of the Y2O3 powder. Since the mixing ratio of ZrO2 powder is less than that of Y2O3 powder, the number of contact points between the Y2O3 and ZrO2 powders is correspondingly reduced. Therefore, by ensuring that the average particle sizes of both ZrO2 and Y2O3 powders are within the aforementioned ranges, the contact opportunities between the Y2O3 and ZrO2 powders can be increased. Thus, by performing heat treatment with increased contact opportunities between the Y2O3 and ZrO2 powders, the solid-phase reaction is promoted, enabling the ZrO2 powder to be dissolved in the Y2O3 powder in a short time.

[0076] The heat treatment for sintering a mixture of Y₂O₃ and ZrO₂ powders is preferably performed at 1100°C to 1600°C, more preferably at 1300°C to 1500°C. This sufficiently accelerates the solid-state reaction rate of the Y₂O₃ and ZrO₂ powders and allows for adjustment of the particle size of the sintered body after heat treatment. It should be noted that the heat treatment for sintering a mixture of Y₂O₃ and HfO₂ powders, or a mixture of Y₂O₃ and Nb₂O₅ powders, is preferably performed at 1200°C to 1600°C, more preferably at 1400°C to 1600°C. This sufficiently accelerates the solid-state reaction rate of the Y₂O₃ and HfO₂ powders, or the solid-state reaction rate of the Y₂O₃ and Nb₂O₅ powders, and allows for adjustment of the particle size of the sintered body after heat treatment.

[0077] It should be noted that when heat treatment is performed at temperatures below the aforementioned range, the microstructure cannot be sufficiently homogenized, and the solid-phase reaction rate slows down, resulting in a very long manufacturing time. On the other hand, when treatment is performed at temperatures above the aforementioned range, the sintering of Y2O3 particles becomes more active, and consolidation progresses, making subsequent particle size adjustment difficult. It should be noted that the heat treatment time is preferably 3 to 12 hours, more preferably 5 to 8 hours.

[0078] Next, the synthetic powders, which have been sintered together by heat treatment, are broken up and added to a solvent or the like to form a slurry. This slurry is then granulated using a spray drying method or the like into spherical particles with an average particle size preferably of 15 to 40 μm. These granulated particles are then subjected to an oxidizing atmosphere in which the organic binder is removed using an electric furnace or the like. Furthermore, to improve the breaking strength of the spherical particles, they are heated to a temperature preferably of 1200 to 1500°C, more preferably 1350 to 1500°C, and then supplied as a film-forming material.

[0079] It should be noted that the method for manufacturing the film-forming material of the present invention is not limited to the method described above. Other methods include using a particulate dispersion sol with a metal oxide as the dispersant, or a metal salt. For example, commercially available ZrO2 sol and Y2O3 powder are mixed in a preferred ratio of Y2O3 and ZrO2 as described above, and this mixture is used as a raw material for spray drying and granulation, thereby obtaining spherical particles composed of primary particles of ZrO2 and Y2O3. These spherical particles are preferably heat-treated in an oxidizing atmosphere at a temperature of 1000–1500°C, thereby simultaneously achieving integrated reaction processing and improving the breaking strength of the spherical particles. The heat-treated spherical particles are then supplied as a film-forming material. It should be noted that the ZrO2 sol described above can also be replaced with HfO2 sol or Nb2O5 sol, and can still be supplied as a film-forming material.

[0080] Furthermore, the manufacturing method of the film-forming material of the present invention can also be carried out using electrofusion and pulverization methods. For example, by electrofusion, Y2O3 powder and ZrO2 powder mixed in a specified ratio are melted / cast at a temperature preferably 3000 to 4000°C, thereby obtaining an ingot of a synthetic material in which the hexahedral crystal structure of Y2O3 is maintained through the high-temperature process during melting. If the ingot is pulverized sequentially using a jaw crusher, ball mill, or other equipment and adjusted to a suitable particle size range, it can be supplied as a film-forming material.

[0081] <Film Formation Method>

[0082] Known methods such as spraying and physical vapor deposition are examples of coating methods that utilize the film-forming material of the present invention. Each film-forming method will be described below. Coatings formed using the spraying or physical vapor deposition method with the film-forming material of the present invention exhibit high plasma resistance.

[0083] As suitable sputtering methods for the present invention, examples include atmospheric pressure plasma sputtering and depressurized plasma sputtering. Atmospheric pressure plasma sputtering is preferred. Known methods, including apparatus and conditions, can be used in the atmospheric pressure plasma sputtering method suitable for the present invention; examples are given below.

[0084] Plasma spraying equipment: Plasma spraying gun (manufactured by Sulzer Metco Ltd., 9MB)

[0085] Operating voltage: 65V

[0086] Operating current: 700A

[0087] Primary gas (Ar) flow rate: 60 NL / min

[0088] Secondary gas (H2) flow rate: 5 NL / min

[0089] Spraying distance: 140mm

[0090] Examples of physical vapor deposition methods suitable for the present invention include sputtering, ion plating, arc ion plating, and electron beam physical vapor deposition. Electron beam physical vapor deposition is preferred. Known methods, including apparatus and conditions, can be used in electron beam physical vapor deposition methods suitable for the present invention; examples are given below.

[0091] Apparatus: Von Ardenne, Tuba 150

[0092] Substrate temperature: 450℃

[0093] Chamber pressure: 1.0 Pa

[0094] Operating voltage: 60kW

[0095] <Manufacturing Method of Components for Plasma Etching Apparatus>

[0096] The film-forming material of the present invention is applicable to components used in plasma etching apparatuses in semiconductor manufacturing. Components used in plasma etching apparatuses in the present invention refer to components that can be exposed to plasma in plasma processes, such as components within etching chambers and electrostatic chucks.

[0097] The plasma etching apparatus of this invention includes a cylindrical cavity, a plasma generation section such as electrodes, and an electrostatic chuck for holding the wafer. The wafer, held in the electrostatic chuck within the cavity, is etched using the plasma generated by the plasma generation section. At this time, the generated plasma acts not only on the wafer but also on the cavity components and the electrostatic chuck.

[0098] The components for plasma etching apparatus in this invention refer to the aforementioned cavity components, electrostatic chucks, and other components that can be exposed to plasma. For these plasma etching apparatus components, high plasma resistance is required to suppress the generation of microparticles due to plasma exposure. Therefore, a protective coating using the film-forming material of this invention is formed on the substrate of the plasma etching apparatus component using a spraying method or a physical vapor deposition method, thereby enabling the plasma etching apparatus component to possess high plasma resistance.

[0099] Example

[0100] The present invention will be specifically described below using examples. It should be noted that the present invention is not limited to the following examples. In the present invention, the average particle size, unless otherwise specified, refers to the particle size (D50) at which the cumulative value of the particle size distribution determined by laser diffraction / scattering method reaches 50%.

[0101] (Example 1)

[0102] Y₂O₃ powder with an average particle size of 3.3 μm and ZrO₂ powder with an average particle size of 1.0 μm were prepared. The powders were dry-mixed using a planetary mill (using zirconia balls and a zirconia jar) to achieve a ZrO₂ content of 2 mol% in the resulting mixture of Y₂O₃ and ZrO₂ powders. The resulting mixed powder was heated in an electric furnace at 1500 °C for 10 hours for solid solution synthesis. Subsequently, the synthesized powder was crushed using an alumina mortar and millstone, and the crushed powder was used to prepare a sintered body (solid solution) via a discharge plasma sintering apparatus.

[0103] The surface of the sintered body was then ground to #1200 using wet sandpaper (SiC abrasive), and the crystalline phase was identified using X-ray diffraction (XRD).

[0104] Finally, the sintered body subjected to X-ray diffraction was subjected to a plasma exposure test to determine the consumption rate. Here, the consumption rate is defined as follows, by measuring the difference in the plasma exposure level between the parts of the sintered body that are shielded from plasma and the parts that are exposed to plasma using a laser microscope.

[0105] Consumption rate = Size of the step difference (μm) / Etching time (minutes)

[0106] The plasma exposure test used a dry etching apparatus to statically sinter the substrate on a 4-inch Si wafer and expose it to plasma. The plasma was generated under the following conditions.

[0107] Plasma gas types and flow rates:

[0108] CF4··50sccm, O2…10sccm,

[0109] Ar…50sccm

[0110] RF output power: 800W, bias voltage: 600W

[0111] (Example 2)

[0112] The ZrO2 powder content in the mixture of Y2O3 powder and ZrO2 powder is 5 mol%. Otherwise, the sintered body is prepared, the crystalline phase is identified, plasma exposure test is performed, and the consumption rate is determined using the same method as in Example 1.

[0113] (Example 3)

[0114] The ZrO2 powder content in the mixture of Y2O3 powder and ZrO2 powder is 10 mol%. Otherwise, the sintered body is prepared, the crystalline phase is identified, plasma exposure test is performed, and the consumption rate is determined using the same method as in Example 1.

[0115] In Example 3, five points were randomly selected from the obtained sintered powder particles, and the content ratio of Zr atoms relative to Y atoms was investigated at each point. The results were 0.1123, 0.1088, 0.1075, 0.1115, and 0.1135, respectively. The absolute value relative to the material formed by dissolving 10 mol% ZrO2 in Y2O3 is 0.111, indicating that ZrO2 is uniformly dissolved in the powder material obtained in this example. Here, the XRD pattern used to identify the crystalline phase of the solid solution in Example 3 is shown in Figure 5(a). As can be seen from Figure 5(a), the solid solution in Example 3 only produces peaks of the hexahedral crystal structure of Y2O3.

[0116] (Comparative Example 1)

[0117] The ZrO2 powder content in the mixture of Y2O3 powder and ZrO2 powder is 15 mol%. Otherwise, the sintered body is prepared, the crystalline phase is identified, plasma exposure test is performed, and the consumption rate is determined using the same method as in Example 1.

[0118] (Comparative Example 2)

[0119] The ZrO2 powder content in the mixture of Y2O3 powder and ZrO2 powder is 20 mol%. Otherwise, the sintered body is prepared, the crystalline phase is identified, plasma exposure test is performed, and the consumption rate is determined using the same method as in Example 1.

[0120] (Comparative Example 3)

[0121] The ZrO2 powder content in the mixture of Y2O3 powder and ZrO2 powder was 30 mol%. Otherwise, the sintered body was prepared, the crystalline phase was identified, plasma exposure was tested, and the consumption rate was measured using the same method as in Example 1. Here, the XRD pattern used for identifying the crystalline phase of the solid solution in Comparative Example 3 is shown in Figure 5(b). As can be seen from Figure 5(b), the solid solution of Comparative Example 3 produced not only peaks of the hexahedral crystal structure of Y2O3 but also peaks of ZrO2.

[0122] (Example 4)

[0123] Y₂O₃ powder with an average particle size of 3.3 μm and HfO₂ powder with an average particle size of 0.8 μm were prepared. The powders were dry-mixed using a planetary mill (using zirconia balls and a zirconia jar) to form a 5 mol% HfO₂ content in the resulting mixture of Y₂O₃ and HfO₂ powders. The resulting mixed powder was heated in an electric furnace at 1500°C for 10 hours for solid solution synthesis. The synthesized powder was then crushed using an alumina mortar and millstone, and the crushed powder was used to prepare a sintered body (solid solution) using a discharge plasma sintering apparatus. Identification of the crystalline phase, plasma exposure testing, and determination of the consumption rate were performed using the same methods as in Example 1.

[0124] (Example 5)

[0125] The HfO2 content in the mixture of Y2O3 powder and HfO2 powder was 10 mol%. Otherwise, the sintered body was prepared, the crystalline phase was identified, plasma exposure was tested, and the consumption rate was measured using the same method as in Example 4. Here, the XRD pattern used for identifying the crystalline phase of the solid solution in Example 5 is shown in Figure 6(a). As can be seen from Figure 6(a), the solid solution in Example 5 only produces peaks of the hexahedral crystal structure of Y2O3.

[0126] (Example 6)

[0127] The HfO2 content in the mixture of Y2O3 powder and HfO2 powder is 20 mol%. Otherwise, the sintered body is prepared, the crystalline phase is identified, plasma exposure test is performed, and the consumption rate is determined using the same method as in Example 4.

[0128] (Comparative Example 4)

[0129] The HfO2 content in the mixture of Y2O3 powder and HfO2 powder is 30 mol%. Otherwise, the sintered body is prepared, the crystalline phase is identified, the plasma exposure test is performed, and the consumption rate is determined using the same method as in Example 4.

[0130] (Comparative Example 5)

[0131] The HfO2 content in the mixture of Y2O3 powder and HfO2 powder reached 35 mol%. Otherwise, the sintered body was prepared, the crystalline phase was identified, plasma exposure was tested, and the consumption rate was confirmed using the same method as in Example 4. Here, the XRD pattern used for identifying the crystalline phase of the solid solution in Comparative Example 5 is shown in Figure 6(b). As can be seen from Figure 6(b), the solid solution of Comparative Example 5 not only produced peaks of the hexahedral crystal structure of Y2O3 but also peaks of HfO2.

[0132] (Example 7)

[0133] Y₂O₃ powder with an average particle size of 3.3 μm and Nb₂O₅ powder with an average particle size of 0.66 μm were prepared. The powders were dry-mixed using a planetary mill (using zirconia balls and a zirconia jar) to achieve a Nb₂O₅ content of 2 mol% in the resulting mixture of Y₂O₃ and Nb₂O₅ powders. The resulting mixed powder was heated in an electric furnace at 1500°C for 10 hours for solid solution synthesis. The synthesized powder was then crushed using an alumina mortar and millstone, and the crushed powder was used to prepare a sintered body (solid solution) using a discharge plasma sintering apparatus. Identification of the crystalline phase, plasma exposure testing, and determination of the consumption rate were performed using the same methods as in Example 1.

[0134] (Example 8)

[0135] The Nb2O5 content in the mixture of Y2O3 powder and Nb2O5 powder was 5 mol%. Otherwise, the sintered body was prepared, the crystalline phase was identified, plasma exposure was tested, and the consumption rate was measured using the same method as in Example 7. Here, the XRD pattern used for identifying the crystalline phase of the solid solution in Example 8 is shown in Figure 7(a). As can be seen from Figure 7(a), the solid solution in Example 8 only produces peaks of the hexahedral crystal structure of Y2O3.

[0136] (Comparative Example 6)

[0137] The Nb2O5 content in the mixture of Y2O3 powder and Nb2O5 powder is 10 mol%. Otherwise, the sintered body is prepared, the crystalline phase is identified, plasma exposure test is performed, and the consumption rate is determined using the same method as in Example 7.

[0138] (Comparative Example 7)

[0139] The Nb2O5 content in the mixture of Y2O3 powder and Nb2O5 powder was 15 mol%. Otherwise, the sintered body was prepared, the crystalline phase was identified, plasma exposure was tested, and the consumption rate was measured using the same method as in Example 7. Here, the XRD pattern used for identifying the crystalline phase of the solid solution in Comparative Example 7 is shown in Figure 7(b). As can be seen from Figure 7(b), the solid solution of Comparative Example 7 produced not only peaks of the hexahedral crystal structure of Y2O3 but also peaks of Nb2O5.

[0140] (Comparative Example 8)

[0141] The Nb2O5 content in the mixture of Y2O3 powder and Nb2O5 powder is 20 mol%. Otherwise, the sintered body is prepared, the crystalline phase is identified, plasma exposure test is performed, and the consumption rate is determined using the same method as in Example 7.

[0142] (Comparative Example 9)

[0143] Sintered bodies were prepared using Y₂O₃ powder with an average particle size of 1–2 μm via a discharge plasma sintering apparatus. The identification of the crystalline phase, plasma exposure tests, and the determination of the consumption rate were performed using the same methods as in Example 1.

[0144] The results of X-ray diffraction and plasma exposure tests in the above embodiments and comparative examples are shown in Table 1 below.

[0145] Here, the X-ray diffraction results in Table 1 are the results of identifying the crystalline phase using X-ray diffraction. Additional information includes: 〇 for cases where only the peak of the hexahedral structure of Y2O3 is detected; × for cases where, in addition to the peak of the hexahedral structure of Y2O3, peaks of metal oxides dissolved in Y2O3, composite oxides, etc., are also detected.

[0146] In addition, the consumption rate in Table 1 is a value obtained by comparing the consumption rate of the Si wafer supplied for plasma exposure test with the consumption rate of each embodiment and comparative example supplied for plasma exposure test. The consumption rate of the Si wafer is set to 100, and the consumption rate of each test piece is shown as the consumption rate.

[0147] [Table 1]

[0148]

[0149] As shown in Table 1, the consumption rate of the sintered bodies (solid solutions) of Examples 1-8, in which only the peaks of the hexahedral crystal structure of Y₂O₃ were detected by X-ray diffraction, was lower than that of the sintered bodies of Comparative Examples 1-9, in which peaks of other metal oxides were detected. This demonstrates that by solidifying ZrO₂, HfO₂, or Nb₂O₅ at a ratio relative to Y₂O₃ where the hexahedral crystal structure of Y₂O₃ is maintained, the consumption due to plasma can be significantly reduced.

[0150] Next, an example of a spray-coated film obtained using the film-forming material of the present invention will be described.

[0151] (Example 9)

[0152] A Y2O3-ZrO2 slurry was prepared using ZrO2 aqueous sol (Nissan Chemical Co., Ltd., trade name: NanoUse ZR), Y2O3 powder with an average particle size of 1.5 μm, and deionized water. The slurry contained 10 mol% ZrO2 of the total Y2O3 and ZrO2 content, and 45% by weight of total solids.

[0153] Next, 0.40% by weight of an acrylic binder (Chukyō Oils & Fats Co., Ltd., trade name: Celuna WN-405) was added to the slurry, and the mixture was spray-dried and granulated to obtain spherical particles with an average particle size of 36 μm. The spherical particles were then heated to 1350°C in an atmospheric atmosphere using an electric furnace to perform binder removal and homogenization treatments, thereby preparing a film-forming material containing a solid solution.

[0154] Next, a square aluminum alloy (A5052) substrate with a thickness of 3mm, a length of 20mm, and a width of 20mm was sandblasted and roughened. Then, atmospheric plasma spraying was performed on its surface using an atmospheric plasma spraying device (plasma spraying gun (Sulzer Metco Ltd. 9MB)) with a working voltage of 65V, a working current of 700A, a primary gas (Ar) flow rate of 60NL / min, a secondary gas (H2) flow rate of 5NL / min, and a spraying distance of 140mm to produce a test piece with a sprayed coating thickness of about 0.15mm.

[0155] The coated surface of the above-prepared test piece was polished with #800 wet sandpaper, ultrasonically washed in pure water, and then dried at 85°C in a constant temperature bath before being subjected to plasma exposure tests to determine the consumption rate. Here, the consumption rate is defined by the magnitude of the difference between the areas shielded from plasma and those exposed to plasma, measured using a laser microscope. The test used a dry etching apparatus, where the sintered body was statically placed on the wafer and exposed to plasma. Plasma generation was carried out under the following conditions.

[0156] Plasma gas types and flow rates:

[0157] CF4··50sccm, O2…10sccm,

[0158] Ar…50sccm

[0159] RF output power: 800W, bias voltage: 600W

[0160] (Example 10)

[0161] HfO2 powder with an average particle size of 0.8 μm and Y2O3 powder with an average particle size of 3.3 μm were weighed and mixed to form a 15 mol% HfO2 content in the resulting mixture. The mixed powders were then mixed in ethanol solvent using zirconia balls and a zirconia container. The dried mixed powders were then heat-treated in an electric furnace to 1500 °C in an air stream to form a composite powder with HfO2 dissolved in Y2O3. The composite powder was then crushed, and the resulting crushed material was used to prepare a slurry with a solid content of 40 wt% using deionized water as a solvent.

[0162] An acrylic binder (Chukyō Oils & Fats Co., Ltd., trade name: Celuna WN-405) was added to the slurry obtained above, based on the solid content, and then spray-dried for granulation. As a result, spherical particles with an average particle size of 31 μm were obtained. These spherical particles were then heated to 1450°C in an atmospheric atmosphere using an electric furnace to perform binder removal and homogenization treatments, thus preparing a film-forming material. The method for preparing the test pieces and confirming the consumption rate was carried out using the same method as in Example 9.

[0163] (Comparative Example 10)

[0164] Y₂O₃ powder with an average particle size of 3.3 μm was dispersed in ion-exchanged water at a solid content of 40 wt% to form a slurry. Next, an acrylic binder (Chukyō Oils & Fats Co., Ltd., trade name: Celuna WN-405) was added to the slurry at a solid content of 0.40 wt%, and the mixture was spray-dried to granulate, resulting in granulated spherical powder with an average particle size of 33 μm. Then, the spherical particles were heated to 1450°C in an atmospheric atmosphere using an electric furnace to perform binder removal and homogenization treatments, thus preparing a film-forming material. The method for preparing test pieces and confirming the consumption rate was performed using the same method as in Example 9.

[0165] (Comparative Example 11)

[0166] Y₂O₃ powder with an average particle size of 3.3 μm and ZrO₂ powder with an average particle size of 0.9 μm were uniformly mixed in an air stream to form 18 mol% ZrO₂. The mixture was then heated to 1450 °C in an air stream. The crushed synthetic powder was dispersed in deionized water at a solids content of 40 wt% to form a slurry. Next, an acrylic binder (Chukyō Oils & Fats Co., Ltd., trade name: Celuna WN-405) at a solids content of 0.40 wt% was added to the slurry, followed by spray drying granulation to obtain granulated spherical powder with an average particle size of 33 μm. Furthermore, the spherical particles were heated to 1450 °C in an atmospheric atmosphere using an electric furnace to perform binder removal and homogenization treatments to prepare a film-forming material. The method for preparing test pieces and confirming the consumption rate was carried out using the same method as in Example 9.

[0167] The results of the plasma exposure tests in the above-described embodiments and comparative examples are shown in Table 2 below. Here, the consumption rate in Table 2 refers to the value obtained by comparing the consumption rate of the Y2O3 spray coating of Comparative Example 10 supplied for the plasma exposure test with the consumption rate of each embodiment and comparative example supplied for the plasma exposure test, and the consumption rate of the Y2O3 spray coating is set to 100.

[0168] [Table 2]

[0169]

[0170] As shown in Table 2, the consumption rates of the spray-coated films in Example 9 and Example 10 are lower than the consumption rate of the spray-coated film in Comparative Example 10. On the other hand, it can be seen that the consumption rate of the spray-coated film in Comparative Example 11 is higher than that of Comparative Example 10.

[0171] Industrial availability

[0172] The film-forming material of the present invention is effective in a wide range of fields, including components for plasma etching apparatuses that use halogen gases such as fluorine in semiconductor manufacturing processes.

[0173] It should be noted that the entire contents of the specification, claims, drawings and abstract of Japanese Patent Application No. 2021-200979, filed on December 10, 2021, are incorporated herein by reference as a public disclosure of the specification of this invention.

Claims

1. A film-forming material, characterized in that, It is a film-forming material containing a solid solution, wherein the solid solution contains only Y2O3 and one metal oxide selected from ZrO2, HfO2 and Nb2O5. When the metal oxide is ZrO2, the content of ZrO2 is 2 to 12 mol%. When the metal oxide is HfO2, the content of HfO2 is 4 to 24 mol%. When the metal oxide is Nb2O5, the content of Nb2O5 is 1 to 8 mol%. Furthermore, the crystal structure of the solid solution has the hexahedral crystal structure of Y2O3.

2. The film-forming material according to claim 1, wherein, When the metal oxide is ZrO2, the content of ZrO2 is 7 to 12 mol.

3. The film-forming material according to claim 1, wherein, When the metal oxide is HfO2, the content of HfO2 is 8~20 mol.

4. The film-forming material according to claim 1, wherein, When the metal oxide is Nb2O5, the content of Nb2O5 is 3 to 7 moles.

5. The film-forming material according to any one of claims 1 to 4, wherein, The ratio of Zr, Hf, or Nb atoms to Y atoms in the solid solution is as follows: in 5 randomly selected points of the solid solution contained in the film-forming material, the absolute value is within ±5%.

6. The film-forming material according to any one of claims 1 to 4, wherein, The solid solution produces only peaks of the hexahedral crystal structure of Y2O3 in X-ray diffraction (XRD).

7. A film-forming method, wherein the film-forming material according to any one of claims 1 to 6 is used for spraying.

8. A film-forming method, wherein the film-forming material according to any one of claims 1 to 6 is used for physical vapor deposition.

9. A method for manufacturing a component for a plasma etching apparatus, wherein a protective coating is formed on a substrate using the film-forming method described in claim 7 or 8.

10. A method for manufacturing a film-forming material, characterized in that, It is a method for manufacturing the film-forming material according to any one of claims 1 to 6. A solid solution is formed by heat-treating a mixed powder, wherein the mixed powder is a mixture of Y2O3 powder and a metal oxide powder containing only ZrO2, HfO2, or Nb2O5. If the metal oxide is ZrO2, the mixed powder with a ZrO2 content of 2-12 mol% is heat-treated at 1000-1600°C to form a solid solution. If the metal oxide is HfO2, the mixed powder with a HfO2 content of 4-24 mol% is heat-treated at 1200-1600°C to form a solid solution. If the metal oxide is Nb2O5, the mixed powder with a Nb2O5 content of 1-8 mol% is heat-treated at 1200-1600°C to form a solid solution.

11. The method for manufacturing the film-forming material according to claim 10, wherein, After the solid solution is formed, it is granulated into particles with an average particle size of 15 to 40 μm and heat-treated at a temperature of 1200 to 1500 °C.

12. A method for manufacturing a film-forming material, characterized in that, It is a method for manufacturing the film-forming material according to any one of claims 1 to 6. A mixture containing Y2O3 powder and metal oxide sol containing ZrO2, HfO2 or Nb2O5 is spray-dried and granulated. The resulting spherical particles, which are composed of ZrO2, HfO2 or Nb2O5 particles and Y2O3 particles, are then heat-treated in an oxidizing atmosphere at a temperature of 1000~1500℃ to form a solid solution.

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