Structural members

Abstract

To provide a structural member that has sufficient durability against plasma. [Solution] The structural member 10 comprises a base material 100 and a protective film 200 covering the surface 110 of the base material 100. The protective film 200 mainly contains lanthanum yttrium oxide. By forming the protective film using a material mainly containing lanthanum yttrium oxide, sufficient durability of the protective film against plasma is ensured.

Description

Technical Field

[0001] The present invention relates to a structural member.

Background Art

[0002] Members constituting a semiconductor manufacturing apparatus, such as a member of the inner wall of a chamber, etc., are required to have durability against plasma. For this reason, as such a member, it has generally become common to use a structural member in which a protective film is formed on the surface of a base material, as described in Patent Document 1 below, for example. As the protective film, oxide ceramics such as yttria are often used.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The inventors of the present invention have been studying using a new material as the material of the protective film and further enhancing the durability of the protective film against plasma.

[0005] The present invention has been made in view of such problems, and an object thereof is to provide a structural member having sufficient durability against plasma.

Means for Solving the Problems

[0006] In order to solve the above problems, the structural member according to the present invention includes a base material and a protective film that covers the surface of the base material. The protective film contains lanthanum yttrium oxide as a main component.

[0007] Experiments conducted by the present inventors confirmed that forming a protective film using a material mainly composed of lanthanum yttrium oxide ensures sufficient durability of the protective film against plasma. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a structural member that has sufficient durability against plasma. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram showing a cross-section of a structural member. [Figure 2] This figure shows the relationship between the hexagonal crystal abundance of the protective film and the durability of the protective film against plasma. [Figure 3] This figure shows the relationship between the hexagonal crystal abundance of the protective film and the durability of the protective film against plasma. [Figure 4] This is a diagram illustrating an analytical method using X-ray diffraction. [Figure 5] This is a diagram illustrating an analytical method using X-ray diffraction. [Figure 6] This table shows a list of film formation conditions and other factors used when forming a protective film. [Modes for carrying out the invention]

[0010] This embodiment will now be described with reference to the attached drawings. To facilitate understanding of the explanation, the same reference numerals are used for identical components in each drawing whenever possible, and redundant explanations are omitted.

[0011] The structural member 10 according to this embodiment is configured as a component for semiconductor manufacturing equipment, such as a plasma etching apparatus. Specifically, the structural member 10 is a component used as the inner wall of a processing chamber in semiconductor manufacturing equipment. However, this application of the structural member 10 is merely an example. The structural member 10 may also be a component placed inside the processing chamber of semiconductor manufacturing equipment, such as a focus ring.

[0012] As shown in Figure 1, the structural member 10 comprises a base material 100 and a protective film 200. In a plasma etching apparatus, the surface 210 of the protective film 200 is exposed to the space inside the processing chamber. The protective film 200 is provided for the purpose of protecting the surface 110 of the base material 100 from plasma.

[0013] The base material 100 is a component that occupies approximately the entirety of the structural member 10. In this embodiment, the base material 100 is a ceramic sintered body containing high-purity aluminum oxide (Al2O3), but it may be a different type of ceramic, or a component other than ceramic (for example, a metal component). Also, in this embodiment, the surface 110 of the base material 100 is a flat surface, but it may be a curved surface or the like. Furthermore, a slope may be provided on a part of the surface 110.

[0014] As mentioned above, the protective film 200 is a film formed to protect the substrate 100 from plasma. The protective film 200 is formed to cover the entire surface 110 of the substrate 100. The protective film 200 is made of a material mainly composed of lanthanum yttrium oxide. Specifically, the lanthanum yttrium oxide is LaYO3. The ratio of the number of lanthanum (La) atoms, yttrium (Y) atoms, and oxygen (O) atoms in the protective film 200 may differ from that described above. In this embodiment, the protective film 200 is a film formed using the aerosol deposition method, but it may also be a film formed using other film formation methods.

[0015] In this specification, the "main component" refers to the compound that is most abundantly contained in the object (here, the protective film 200). Specifically, the "main component" refers to a compound that, when quantitative analysis or semi-quantitative analysis using X-ray Diffraction (XRD) is performed on the object, is confirmed to be relatively more contained in terms of volume ratio or mass ratio than any other compound contained in the object.

[0016] In the protective film 200 of this embodiment, the proportion occupied by the main component (lanthanum yttrium oxide) is greater than 50% in terms of volume ratio or mass ratio. This proportion may be greater than 70%, may be greater than 90%, or may be 100%.

[0017] The thickness of the protective film 200 is appropriately set according to the length of the period for which durability is required, etc. In this embodiment, the thickness of the protective film 200 is 15 μm or less.

[0018] [[ID=??]]The inventors of the present invention have been proceeding with studies on using a new material as the material of the protective film 200 and further enhancing the durability of the protective film 200 against plasma. As a result of evaluating and studying various materials, it was confirmed that when the protective film 200 is formed using a material containing lanthanum yttrium oxide as the main component as in this embodiment, sufficient durability of the protective film 200 against plasma can be ensured.

[0019] Further, it was also confirmed that when the protective film 200 is formed using a material containing lanthanum yttrium oxide as the main component, the durability of the protective film 200 against plasma changes according to the crystal structure of the protective film 200. Specifically, it was confirmed that the greater the proportion of the hexagonal crystal structure in the protective film 200, the higher the durability of the protective film 200 against plasma.

[0020] It should be noted that there seems to be a typo in line 12 where "??" is used instead of "12". This has been left as is in the translation for the purpose of maintaining consistency with the original text.The inventors prepared a plurality of samples of the structural member 10 having different structures in the crystal structure of the protective film 200, and for each protective film 200, evaluated the durability against plasma and the like. Incidentally, in evaluating the durability of the protective film 200 against plasma, the surface 210 of each protective film 200 was exposed to a plasma atmosphere using an inductively coupled reactive ion etching (ICP-RIE) apparatus (not shown). As conditions for exposing the surface 210 to the plasma atmosphere, the following two conditions were used.

[0021] In the first condition, a 4-inch silicon wafer was adsorbed and held by an electrostatic chuck in the chamber of the inductively coupled reactive ion etching apparatus. A sample of the structural member 10 to be evaluated was placed on the silicon wafer. Then, by generating plasma in the chamber, the surface 210 of the protective film 200 was exposed to the plasma atmosphere. SF6 was used as the process gas, and the gas was supplied into the chamber at a flow rate of 100 sccm. The pressure in the chamber was adjusted to 0.5 Pa. The exposure time was 30 minutes. The magnitude of the power output was such that the coil output for ICP was 1500 W and the bias output was 750 W. The test of exposing the surface 210 of the protective film 200 to the plasma atmosphere under the first condition as described above is hereinafter also referred to as the "first standard plasma test". In the first standard plasma test, since the bias output was set to 750 W as described above, the plasma was drawn toward the protective film 200 and used for etching the protective film 200.

[0022] Under the second condition, a 4-inch silicon wafer was held by electrostatic chuck within the chamber of an inductively coupled reactive ion etching apparatus. A sample of the structural component 10 to be evaluated was placed on the silicon wafer. Subsequently, plasma was generated in the chamber to expose the surface 210 of the protective film 200 to a plasma atmosphere. SF6 was used as the process gas and supplied to the chamber at a flow rate of 100 sccm. The pressure inside the chamber was adjusted to 0.5 Pa. The exposure time was 60 minutes. The power output was set to 1500W for the ICP coil output and the bias output was turned OFF (i.e., 0W). The test in which the surface 210 of the protective film 200 is exposed to a plasma atmosphere under the second condition described above will also be referred to as the "second standard plasma test" below. In the second standard plasma test, as described above, the bias output was turned OFF, so the plasma was not drawn towards the protective film 200 and was hardly used for etching the protective film 200. The surface 210 of the protective film 200 is simply exposed to a non-directional plasma.

[0023] Figure 2 shows the results of the first standard plasma test performed on each of the multiple structural members 10. The horizontal axis of the graph in Figure 2, "Hexagonal Abundance," is an index that indicates the proportion of the protective film 200 that is composed of hexagonal crystal structures. If no hexagonal crystal structures are present in the protective film 200, the value of the hexagonal abundance is 0. If all the crystals constituting the protective film 200 are hexagonal, the value of the hexagonal abundance is 1. The specific definition and calculation method of the hexagonal abundance will be explained later.

[0024] The vertical axis of the graph in Figure 2 represents the etching rate in the first standard plasma test, i.e., the depth to which the protective film 200 is etched per unit time, expressed in units of "μm / h". The higher the durability of the protective film 200 against the plasma, the lower its etching rate. The etching rate can be used as one indicator of the durability of the protective film 200 against the plasma.

[0025] Figure 2 shows the etching rates, measured after the first standard plasma test, for three samples of protective film 200 with different hexagonal abundances, along with their error ranges. For the sample with a hexagonal abundance of 0.03, the etching rate was 3.24 μm / h. For the sample with a hexagonal abundance of 0.46, the etching rate was 1.74 μm / h. For the sample with a hexagonal abundance of 0.47, the etching rate was 2.17 μm / h.

[0026] As is clear from Figure 2, the larger the hexagonal crystal abundance of the protective film 200, the smaller the etching rate of the protective film 200. For protective films 200 to the right of the dotted line shown in Figure 2, i.e., where the hexagonal crystal abundance is greater than 0.15, the etching rate is sufficiently small, confirming that they have sufficient durability against plasma.

[0027] Figure 3 shows the results of the second standard plasma test performed on each of the multiple structural members 10. The horizontal axis of the graph in Figure 3 is the same as the horizontal axis in Figure 2, representing the hexagonal abundance. Each sample prepared for the second standard plasma test was prepared using the same method as each sample prepared for the first standard plasma test. Therefore, the hexagonal abundance values ​​for each sample shown in Figure 3 are the same as the hexagonal abundance values ​​for each sample shown in Figure 2.

[0028] The vertical axis of the graph in Figure 3 represents the fluorination amount of protective film 200 after the second standard plasma test. "Fluorination amount" is an indicator of how much fluorine atoms, which are part of the plasma, have penetrated into the protective film 200. The specific method for calculating the fluorination amount is as follows.

[0029] First, the surface 210 of the protective film 200, which had undergone the second standard plasma test, was sputtered with argon, and the amount of fluorine atoms present on the surface 210 was continuously measured using X-ray photoelectron spectroscopy (XPS). The measurement was performed over 145 seconds. At each time point, the percentage (in units: %) of the argon measurement was calculated, and the cumulative value of the obtained values ​​was calculated as the "fluorination amount" of the sample. The higher the durability of the protective film 200 against plasma, the smaller the fluorination amount calculated as described above. The fluorination amount, like the etching rate mentioned earlier, can be used as one of the indicators of the durability of the protective film 200 against plasma.

[0030] In the sample with a hexagonal abundance of 0.03, the fluoride content was 1802. In the sample with a hexagonal abundance of 0.46, the fluoride content was 869. In the sample with a hexagonal abundance of 0.47, the fluoride content was 1379.

[0031] As is clear from Figure 3, the higher the hexagonal crystal abundance of the protective film 200, the lower the amount of fluoride in the protective film 200. For protective films 200 to the right of the dotted line shown in Figure 3, i.e., where the hexagonal crystal abundance is greater than 0.15, the amount of fluoride is sufficiently low, and it was confirmed that they have sufficient durability against plasma.

[0032] The method for calculating the hexagonal crystal abundance is explained below. The hexagonal crystal abundance is calculated based on the results of analyzing the crystal structure of protective film 200 using X-ray diffraction.

[0033] The lattice constant of the protective film 200 was measured using the following method. First, X-ray diffraction (XRD) was performed on the protective film 200 formed on the substrate 100 using an out-of-plane θ-2θ scan.

[0034] Line L10 in Figure 4 is an example of a diffraction pattern obtained by analyzing the protective film 200 using X-ray diffraction. This diffraction pattern will also be referred to as the "measured diffraction pattern L10" below. Multiple peaks appear in the measured diffraction pattern L10, and each peak is unique to the material of the protective film 200 and its crystal structure. For example, the diffraction angle 2θ corresponding to the maximum value of each peak corresponds to the crystal structure of the protective film 200. Furthermore, the height of each peak corresponds to the proportion of the crystal structure corresponding to the diffraction angle 2θ that occupies in the protective film 200.

[0035] The maximum intensity value for each peak can be directly used as the maximum intensity value represented on the vertical axis in Figure 4. However, in order to determine with higher accuracy the proportion of the hexagonal crystal structure in the protective film 200, in this embodiment, the maximum intensity value of each peak is obtained using the following method.

[0036] The dashed-dotted line L0 shown in Figure 4 represents the background intensity when no peaks appear. The waveform of the dashed-dotted line L0 can be estimated and obtained, for example, from the overall waveform of the diffraction pattern.

[0037] Line L11 in Figure 5 represents a hypothetical diffraction pattern obtained by adding only the peaks that are maximum at a diffraction angle of 2θ of 25.616 degrees to the background shown by the dashed line L0 in Figure 4. The same applies to lines L12 to L21 in Figure 5, each representing a hypothetical diffraction pattern obtained by adding only the peaks that are maximum at a specific diffraction angle of 2θ to the background.

[0038] The diffraction angle 2θ corresponding to the peak of line L12 is 26.730 degrees, the diffraction angle 2θ corresponding to the peak of line L13 is 27.460 degrees, the diffraction angle 2θ corresponding to the peak of line L14 is 27.911 degrees, the diffraction angle 2θ corresponding to the peak of line L15 is 28.356 degrees, the diffraction angle 2θ corresponding to the peak of line L16 is 29.070 degrees, the diffraction angle 2θ corresponding to the peak of line L17 is 30.231 degrees, the diffraction angle 2θ corresponding to the peak of line L18 is 30.632 degrees, the diffraction angle 2θ corresponding to the peak of line L19 is 31.328 degrees, the diffraction angle 2θ corresponding to the peak of line L20 is 32.380 degrees, and the diffraction angle 2θ corresponding to the peak of line L21 is 32.973 degrees.

[0039] The dashed line L30 shown in Figure 5 is the diffraction pattern obtained by superimposing all the provisional diffraction patterns shown by lines L11 to L21. This diffraction pattern will also be referred to as the "approximate diffraction pattern L30" below. When superimposing multiple provisional diffraction patterns, the overlapping background is not added.

[0040] Each of the provisional diffraction patterns shown by lines L11 to L21 is individually adjusted so that the waveform of the approximate diffraction pattern L30 obtained by summing them up roughly matches the measured diffraction pattern L10 shown in Figure 4. In other words, for each of lines L11, etc., the value of the diffraction angle 2θ at which the peak is maximized, the height of the peak relative to the background, etc. are individually adjusted to bring the waveform of the approximate diffraction pattern L30 closer to the measured diffraction pattern L10. When the waveforms of the two roughly match as a result of this work, each of the provisional diffraction patterns shown by lines L11 to L21 corresponds to the waveform obtained by decomposing the measured diffraction pattern L10 into waveforms for each diffraction angle of 2θ. This processing may be performed manually while observing the waveform of the approximate diffraction pattern L30, etc., but it may also be performed automatically using the functions of software.

[0041] When the material of the protective film 200 is lanthanum yttrium oxide, it is known that the diffraction angle 2θ of the peak attributed to the (222) plane of the cubic crystal is approximately 28.3 degrees. Therefore, in the example shown in Figure 5, it can be inferred that the peak attributed to the (222) plane of the cubic crystal is the peak of line L15. The maximum intensity of this peak, specifically the maximum intensity of this peak relative to the background, will also be referred to as "maximum intensity PC" below.

[0042] It is known that when the material of the protective film 200 is lanthanum yttrium oxide, the diffraction angle 2θ of the peak attributed to the (-402) plane of the monoclinic crystal is approximately 29.3 degrees. Therefore, in the example shown in Figure 5, it can be inferred that the peak attributed to the (-402) plane of the monoclinic crystal is the peak of line L16. The maximum intensity of this peak, specifically the maximum intensity of this peak relative to the background, will also be referred to as "maximum intensity PM" below.

[0043] When the material of the protective film 200 is lanthanum yttrium oxide, it is known that the diffraction angle 2θ of the peak attributed to the (101) plane of the hexagonal crystal is approximately 29.8 degrees. Therefore, in the example shown in Figure 5, it can be inferred that the peak attributed to the (101) plane of the hexagonal crystal is the peak of line L17. The maximum intensity of this peak, specifically the maximum intensity of this peak relative to the background, will also be referred to as "maximum intensity PH" below.

[0044] Using the maximum intensity PC, PM, and PH values ​​calculated by the method described above, the hexagonal crystal abundance is defined and calculated as shown in equation (1) below. Hexagonal crystal abundance rate=PH / (PC+PM+PH)...(1)

[0045] As mentioned earlier, the maximum intensity PC is the maximum intensity of the peak attributed to the (222) plane of the cubic crystal. The maximum intensity PM is the maximum intensity of the peak attributed to the (-402) plane of the monoclinic crystal. The maximum intensity PH is the maximum intensity of the peak attributed to the (101) plane of the hexagonal crystal. Therefore, the hexagonal crystal abundance defined in equation (1) above can be used as an indicator of the proportion of the protective film 200 occupied by the hexagonal crystal structure. As described with reference to Figures 2 and 3, if the hexagonal crystal abundance = PH / (PC+PM+PH) > 0.15 holds true for the protective film 200, then sufficient durability against plasma is ensured in the protective film 200.

[0046] Note that the waveform examples shown in Figures 4 and 5 are examples used to explain the definition and calculation method of hexagonal crystal abundance, and do not correspond to the protective film 200 according to this embodiment.

[0047] The manufacturing methods of each sample used to obtain the data in Figures 2 and 3 will be explained with reference to Figure 6. The samples shown as "No. 1" and "No. 2" in the same figure are samples in which a protective film 200 was formed on the surface 110 of the substrate 100 under generally the same conditions. The sample shown as "No. 3" is a sintered body of LaYO3, and was prepared as a comparative example to the above samples.

[0048] The protective films 200 for samples No. 1 and 2 were both deposited using the aerosol deposition method. As is well known, in the aerosol deposition method, fine particles, which are the material for the protective film 200, are dispersed in a gas to form an "aerosol," which is then sprayed from a nozzle onto the surface 110 and collided with it. On the surface 110, the impact of the collision causes deformation and fragmentation of the fine particles, and as the fine particles bond together, they gradually accumulate to form the protective film 200. Figure 6 shows the type of "gas" used during the deposition of each sample and the flow rate when the gas was sprayed from the nozzle. LaYO3 powder was used as the "fine particles" mentioned above.

[0049] The "hardness" shown in Figure 6 represents the measured indentation hardness of the protective film 200, expressed in units of "GPa". The indentation hardness of the protective film 200 was measured by performing a nanoindentation test on the surface 210 of the protective film 200 formed on the substrate 100 (for sample No. 3, the surface of the sintered body). A Berkovich indenter was used, and the indentation depth was fixed at 200 nm. The indentation hardness (indentation hardness) was measured at multiple locations on the surface 210. Each measurement location was a part of the surface 210 that was free of scratches and dents. If the surface 210 is polished and smoothed prior to the measurement of indentation hardness, a more accurate measurement of indentation hardness can be obtained. The number of measurement locations was set to at least 10, and the average value of the indentation hardness measured at each location was calculated as the indentation hardness of the protective film 200. For other specific test methods, analytical methods, procedures for verifying the performance of test equipment, and requirements for standard reference samples, we followed the methods specified in ISO 14577.

[0050] Samples No. 1, 2, and 3 were each prepared in pairs. One sample underwent the first standard plasma test, yielding the results shown in Figure 2. The other sample underwent the second standard plasma test, yielding the results shown in Figure 3. The hexagonal crystal abundance value calculated for protective film 200 of sample No. 1 was 0.47, the hexagonal crystal abundance value calculated for protective film 200 of sample No. 2 was 0.46, and the hexagonal crystal abundance value calculated for sintered body No. 3 was 0.03. As mentioned earlier, the hexagonal crystal abundance values ​​for samples No. 1 and No. 2 were greater than 0.15, confirming their high resistance to plasma.

[0051] The inventors measured the arithmetic mean height (Sa) of surface 210 for each sample, No. 1 and No. 2, before and after performing the first standard plasma test. In the table in Figure 6, the "Before Etching" column shows the arithmetic mean height of surface 210 measured before the first standard plasma test, in units of μm. The "After Etching" column shows the arithmetic mean height of surface 210 measured after the first standard plasma test, in units of μm. The "ΔSa" column shows the difference between the two arithmetic mean heights. That is, it shows the change in the arithmetic mean height of surface 210 due to the first standard plasma test, in units of μm. The method for measuring the arithmetic mean height was the method specified in ISO 25178.

[0052] In sample No. 3, i.e., the sample in which the hexagonal crystal abundance on the sintered body surface is less than 0.15, the change in the arithmetic mean height of surface 210 (ΔSa) due to the first standard plasma test is significantly greater than 0.05 μm. On the other hand, in samples No. 1 and 2, i.e., the samples in which the hexagonal crystal abundance of the protective film 200 is greater than 0.15, the change in the arithmetic mean height of surface 210 (ΔSa) due to the first standard plasma test is less than 0.05 μm in both cases.

[0053] Thus, in samples No. 1 and 2, where the hexagonal crystal abundance of the protective film 200 was greater than 0.15, it was confirmed that the shape change of the surface 210 due to etching was small.

[0054] The embodiments have been described above with reference to specific examples. However, this disclosure is not limited to these specific examples. Modifications made to these specific examples by those skilled in the art are also included within the scope of this disclosure, as long as they retain the features of this disclosure. The elements, their arrangement, conditions, shapes, etc., of each of the aforementioned specific examples are not limited to those illustrated and can be modified as appropriate. The elements of each of the aforementioned specific examples can be combined in different ways as appropriate, as long as no technical inconsistencies arise. [Explanation of Symbols]

[0055] 10: Structural members 100: Base material 110: Surface 200: Protective film

Claims

1. Substrate and The substrate comprises a protective film covering the surface of the substrate, A structural member characterized in that the protective film contains lanthanum yttrium oxide as its main component.

2. In the diffraction pattern obtained by analyzing the protective film using X-ray diffraction, Let the maximum intensity of the peak attributed to the (222) plane of the cubic crystal be denoted as PC. Let PM be the maximum intensity of the peak attributed to the (-402) plane of the monoclinic crystal. When the maximum intensity of the peak attributed to the (101) plane of the hexagonal crystal is denoted as PH, The structural member according to claim 1, characterized in that PH / (PC+PM+PH) > 0.15 holds true.

3. The structural member according to claim 1, characterized in that the protective film is a film formed using the aerosol deposition method.

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