Structural component

Abstract

Provided is a structural member having sufficient durability to plasma. Specifically, a structural member (10) is provided with a base material (100) and a protective film (200) that covers the surface (110) of the base material (100). The protective film (200) contains lanthanum yttrium oxide as a main component.

Description

Technical Field

[0001] This invention relates to a structural component. Background Technology

[0002] Components constituting semiconductor manufacturing apparatuses, such as the inner walls of chambers, require resistance to plasma. Therefore, as such components, for example as described in Patent Document 1 below, structural components with a protective film formed on the surface of a substrate are typically used. As the protective film, oxide ceramics such as yttrium oxide are often used, for example.

[0003] Patent documents Patent Document 1: Japanese Patent Publication No. 2019-507962 Summary of the Invention

[0004] The inventors have conducted research on using new materials as materials for protective films and on further improving the durability of such protective films against plasma.

[0005] The present invention is based on the following problem: the technical problem to be solved is to provide a structural component with sufficient durability against plasma.

[0006] To address the aforementioned issues, the structural component of the present invention comprises a substrate and a protective film covering the surface of the substrate. This protective film contains lanthanum yttrium oxide as its main component.

[0007] The experiments conducted by the inventors have confirmed that when a material containing lanthanum yttrium oxide as the main component is used to form a protective film, the durability of the protective film against plasma can be adequately ensured.

[0008] According to the present invention, a structural component with sufficient durability against plasma can be provided. Attached Figure Description

[0009] Figure 1 It is a diagram that represents the cross-section of a structural component in a stylized way. Figure 2 This is a graph showing the relationship between the hexagonal crystal content of the protective film and the durability of the protective film against plasma. Figure 3 This is a graph showing the relationship between the hexagonal crystal content of the protective film and the durability of the protective film against plasma. Figure 4 This is a diagram used to illustrate the analytical method that uses X-ray diffraction analysis. Figure 5 This is a diagram used to illustrate the analytical method that uses X-ray diffraction analysis. Figure 6 It is a table showing the film-forming conditions, etc., when a protective film is formed. Symbol Explanation 10 - Structural component; 100 - Substrate; 110 - Surface; 200 - Protective film. Detailed Implementation

[0010] The present embodiment will now be described with reference to the accompanying drawings. To facilitate understanding, the same reference numerals are used as much as possible to represent the same constituent elements in the drawings, and repeated descriptions are omitted.

[0011] The structural component 10 involved in this embodiment is configured, for example, as a component for a semiconductor manufacturing apparatus such as a plasma etching apparatus. Specifically, the structural component 10 is used as the inner wall of a processing chamber provided in a semiconductor manufacturing apparatus. Furthermore, the application of such a structural component 10 is merely one example. The structural component 10 may also be, for example, a component such as a focusing ring disposed inside the processing chamber provided in a semiconductor manufacturing apparatus.

[0012] like Figure 1 As shown, structural component 10 includes a substrate 100 and a protective film 200. In plasma etching apparatuses, the surface 210 of the protective film 200 is exposed to the space within the processing chamber. The purpose of providing the protective film 200 is to protect the surface 110 of the substrate 100 from the effects of plasma.

[0013] The substrate 100 is a component that occupies approximately the entirety of the structural component 10. In this embodiment, the substrate 100 is a sintered ceramic body containing high-purity alumina (Al2O3), but it may also be a different type of ceramic, or a component other than ceramic (e.g., a metal component). Furthermore, although the surface 110 of the substrate 100 is flat in this embodiment, it may also be curved or the like. Additionally, a slope may be provided on a portion of the surface 110.

[0014] As previously described, the protective film 200 is formed to protect the substrate 100 from the effects of plasma. The protective film 200 is formed to cover the entire surface 110 of the substrate 100. The protective film 200 is formed from a material containing lanthanum yttrium oxide as a main component. Specifically, the aforementioned lanthanum yttrium oxide refers to LaYO3. The ratio of the number of lanthanum (La) atoms, yttrium (Y) atoms, and oxygen (O) atoms contained in the protective film 200 may also differ from the above. Although the protective film 200 of this embodiment is formed using aerosol deposition, it may also be formed using other film-forming methods.

[0015] In this specification, "principal component" refers to the compound most abundant in the object (here, protective film 200). Specifically, "principal component" refers to the compound that, when quantitative or quasi-quantitatively analyzed for the object using X-ray diffraction (XRD), is found to be present in greater quantities than any other compound contained in the object in volume or mass ratio.

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

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

[0018] The inventors have investigated the use of novel materials as the protective film 200 and further improved the plasma durability of the protective film 200. Various materials were evaluated and studied, and the results confirmed that when a material containing lanthanum yttrium oxide as the main component is used to form the protective film 200, as in this embodiment, the plasma durability of the protective film 200 can be sufficiently ensured.

[0019] Furthermore, it was confirmed that when a material containing lanthanum yttrium oxide as the main component is used to form the protective film 200, the plasma durability of the protective film 200 changes depending on the crystal structure of the protective film 200. Specifically, it was confirmed that the greater the proportion of hexagonal crystal structure in the protective film 200, the higher the plasma durability of the protective film 200.

[0020] The inventors fabricated multiple samples of structural components 10, each with a different crystal structure in the protective film 200, and then evaluated the plasma durability of each protective film 200. Furthermore, in evaluating the plasma durability of the protective films 200, an inductively coupled reactive ion etching (ICP-RIE) apparatus (not shown) was used, and the surface 210 of each protective film 200 was exposed to a plasma atmosphere. The following two conditions were used as conditions for exposing the surface 210 to the plasma atmosphere.

[0021] In the first condition, a 4-inch silicon wafer is held in place by an electrostatic chuck within the chamber of an inductively coupled reactive ion etching apparatus. The sample of the evaluation object, namely structural component 10, is placed on this silicon wafer. Subsequently, the surface 210 of the protective film 200 is exposed to a plasma atmosphere by generating plasma within the chamber. SF6 is used as the process gas and is supplied to the chamber at a flow rate of 100 sccm. The pressure within the chamber is adjusted to 0.5 Pa. The exposure time is 30 minutes. The power output is set to 1500 W for the ICP coil and 750 W for the bias output. Hereinafter, the test in which the surface 210 of the protective film 200 is exposed to a plasma atmosphere under the first condition described above will also be referred to as the "first standard plasma test". In the first standard plasma test, as described above, plasma is introduced toward the protective film 200 by setting the bias output to 750 W and is used for etching the protective film 200.

[0022] Under the second condition, a 4-inch silicon wafer is held in place by an electrostatic chuck within the chamber of an inductively coupled reactive ion etching apparatus. The sample of the evaluation object, namely structural component 10, is placed on this silicon wafer. Subsequently, the surface 210 of the protective film 200 is exposed to a plasma atmosphere by generating plasma within the chamber. SF6 is used as the process gas and supplied to the chamber at a flow rate of 100 sccm. The pressure within the chamber is adjusted to 0.5 Pa. The exposure time is 60 minutes. The power output is set to 1500 W for the ICP coil and OFF (i.e., 0 W) for the bias output. Hereinafter, the test exposing the surface 210 of the protective film 200 to a plasma atmosphere under the second condition described above will also be referred to as the "Second Standard Plasma Test." In the Second Standard Plasma Test, as described above, by setting the bias output to OFF, the plasma is not introduced towards the protective film 200 and is hardly used for etching the protective film 200. The surface 210 of the protective film 200 is only exposed to non-directional plasma.

[0023] exist Figure 2 The results of the first standard plasma test performed on multiple structural components 10 are shown. Figure 2 The horizontal axis of the graph, representing the "hexagonal crystal presence rate," is an indicator of the proportion of hexagonal crystal structures in the protective film 200. When no hexagonal crystal structure exists in the protective film 200, the hexagonal crystal presence rate is 0. When all crystals constituting the protective film 200 are hexagonal, the hexagonal crystal presence rate is 1. The specific definition and calculation method of the hexagonal crystal presence rate will be explained later.

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

[0025] exist Figure 2 In this study, for three samples with different hexagonal crystal presence rates in the protective film 200, the etching rate values ​​and error ranges determined by the first standard plasma test are shown. The etching rate was 3.24 μm / h for the sample with a hexagonal crystal presence rate of 0.03. The etching rate was 1.74 μm / h for the sample with a hexagonal crystal presence rate of 0.46. The etching rate was 2.17 μm / h for the sample with a hexagonal crystal presence rate of 0.47.

[0026] observe Figure 2 It can be seen that the higher the hexagonal crystal content of the protective film 200, the lower the etching rate of the protective film 200. For Figure 2 For the protective film 200, which is located further to the right of the dashed line and has a hexagonal crystal content greater than 0.15, the etching rate is sufficiently reduced, thus confirming sufficient durability against plasma.

[0027] exist Figure 3 The image shows the results of the aforementioned second standard plasma test performed on multiple structural components 10. (Compared to...) Figure 2 The horizontal axis is the same. Figure 3 The horizontal axis of the graph represents the hexagonal crystal content. Furthermore, the samples prepared for the second standard plasma test were prepared using the same method as those prepared for the first standard plasma test. Therefore, Figure 3 The values ​​of hexagonal crystal presence for each sample shown are... Figure 2 The hexagonal crystal content values ​​are the same for all the samples shown.

[0028] Figure 3 The vertical axis of the graph represents the fluorination level of the protective film 200 after the second standard plasma test. "Fluorination level" refers to the degree to which a portion of the plasma, i.e., fluorine atoms, penetrates into the interior of the protective film 200. The specific calculation method for fluorination level is as follows.

[0029] First, while sputtering the surface 210 of the protective film 200, which has undergone the second standard plasma test, with argon, the amount of fluorine atoms present on the surface 210 is continuously measured using X-ray photoelectron spectrometry (XPS). The measurement lasts for 145 seconds. At this point, the proportion (in %) of the measured value of argon at each time point is calculated, and the cumulative value obtained is calculated as the "fluorination amount" of the sample. The higher the plasma durability of the protective film 200, the lower the value of the fluorination amount calculated as described above. Similar to the etching rate mentioned above, the fluorination amount can be used as one of the indicators of the plasma durability of the protective film 200.

[0030] The fluorination amount was 1802 in the sample with a hexagonal crystal presence of 0.03%. The fluorination amount was 869 in the sample with a hexagonal crystal presence of 0.46%. The fluorination amount was 1379 in the sample with a hexagonal crystal presence of 0.47.

[0031] observe Figure 3 It can be seen that the higher the hexagonal crystal content of the protective film 200, the lower the fluorination content of the protective film 200. For Figure 3 As shown in the protective film 200, which is further to the right of the dashed line and has a hexagonal crystal content greater than 0.15, the fluorination content is sufficiently reduced, thus confirming sufficient durability against plasma.

[0032] The method for calculating the hexagonal crystal presence rate is explained. The hexagonal crystal presence rate is calculated based on the results of X-ray diffraction analysis of the crystal structure of the protective film 200.

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

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

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

[0036] Figure 4 The dashed line L0 shown represents the background intensity when no peak is observed. The waveform of the dashed line L0 can be inferred, for example, from the overall waveform of the diffraction pattern.

[0037] Figure 5 The line L11 shown indicates that, relative to Figure 4 The background shown by the single-dotted line L0 is supplemented only with an imaginary diffraction pattern at the maximum peak value at a diffraction angle 2θ of 25.616 degrees. For Figure 5 The lines L12 to L21 shown are the same, representing hypothetical diffraction patterns relative to the background with only the maximum peak value at a specific diffraction angle 2θ added.

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

[0039] Figure 5 The single-dotted line L30 shown is a diffraction pattern obtained by superimposing all the hypothetical diffraction patterns shown by lines L11 to L21. Hereinafter, this diffraction pattern will also be referred to as the "approximate diffraction pattern L30". Furthermore, when superimposing multiple hypothetical diffraction patterns, the background repetition is not included.

[0040] The hypothetical diffraction patterns shown in lines L11 to L21 are individually adjusted so that the waveform of the approximate diffraction pattern L30 obtained by summing them is compared with... Figure 4The measured diffraction pattern L10 shown is roughly consistent. That is, for each line L11, etc., by individually adjusting the value of the diffraction angle 2θ at the point of maximum peak and the height of that peak relative to the background, the waveform of the approximate diffraction pattern L30 is made close to that of the measured diffraction pattern L10. The result of this operation is that, when the waveforms of the two are roughly consistent, the hypothetical diffraction patterns shown for lines L11 to L21 are respectively equivalent to decomposing the measured diffraction pattern L10 into waveforms at each diffraction angle 2θ. This process can be performed manually while observing the waveforms of the approximate diffraction pattern L30, etc., or it can be automated using software.

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

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

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

[0044] Using the maximum strength values ​​of PC, PM, and PH calculated by the above method, the hexagonal crystal presence rate is defined and calculated as follows (1). Hexagonal crystal presence rate = pH / (PC+PM+PH)…(1)

[0045] As previously stated, the maximum intensity PC is the maximum intensity of the peak value belonging to the (222) facet of the cubic crystal. The maximum intensity PM is the maximum intensity of the peak value belonging to the (-402) facet of the monoclinic crystal. The maximum intensity PH is the maximum intensity of the peak value belonging to the (101) facet of the hexagonal crystal. Therefore, the hexagonal crystal presence rate defined by the above equation (1) can be used as an indicator of the proportion of hexagonal crystal structures in the protective film 200. (Refer to...) Figure 2 and Figure 3 As stated above, when the hexagonal crystal presence rate = PH / (PC+PM+PH) > 0.15 is satisfied, sufficient durability against plasma can be ensured on the protective film 200.

[0046] in addition, Figure 4 and Figure 5 The waveforms shown are examples used to illustrate the definition and calculation method of the hexagonal crystal presence rate, and are not examples corresponding to the protective film 200 involved in this embodiment.

[0047] Reference Figure 6 In order to obtain Figure 2 and Figure 3 The manufacturing methods of each sample used for the data will be described. In this figure, samples labeled "No.1" and "No.2" are samples in which a protective film 200 is formed on the surface 110 of the substrate 100 under substantially the same conditions. Sample labeled "No.3" is a sintered body of LaYO3, which was prepared as a comparative example to the above samples.

[0048] The protective films 200 of samples No. 1 and No. 2 were both formed using aerosol deposition. As is well known, in aerosol deposition, the material of the protective film 200, i.e., the microparticles, is dispersed into a gas to form an "aerosol," which is then sprayed from a nozzle toward surface 110 and impacted. On surface 110, due to the deformation and breakage caused by the impact on the microparticles, the microparticles gradually accumulate and combine with each other to form the protective film 200. Figure 6 The diagram shows the type of "gas" used in film formation for each sample and the flow rate of the gas when it is injected from the nozzle. LaYO3 powder was used as the aforementioned "microparticles".

[0049] Figure 6The "hardness" shown is the measured value of the indentation hardness of the protective film 200, expressed in GPa. The indentation hardness of the protective film 200 is determined by performing a very small indentation hardness test (nanoindentation) on the surface 210 of the protective film 200 formed on the substrate 100 (the surface of the sintered body for sample No. 3). A Berkovich indenter is used, with a fixed indentation depth of 200 nm, and the indentation hardness (indentation hardness) is measured at multiple locations on the surface 210. Each measurement location is a portion of the surface 210 without scratches or depressions. If the surface 210 is smoothed by grinding before the indentation hardness measurement, the indentation hardness can be measured with higher accuracy. The number of measurement locations is at least 10, and the average value of the indentation hardness measured at each location is calculated as the indentation hardness of the protective film 200. For other specific test methods, analytical methods, procedures for verifying the performance of test apparatus, and conditions required for standard reference specimens, the methods specified in international standard ISO 14577 were used.

[0050] Samples No. 1, 2, and 3 were each prepared in pairs. A standard plasma test (No. 1) was performed on one of the samples, yielding... Figure 2 The results are shown. A second standard plasma test was performed on the other sample, and the results were... Figure 3 The results are shown. The calculated hexagonal crystal presence rate for the protective film 200 of No. 1 is 0.47, for the protective film 200 of No. 2 it is 0.46, and for the sintered body of No. 3 it is 0.03. As mentioned earlier, the hexagonal crystal presence rate values ​​for samples No. 1 and No. 2 are greater than 0.15, thus confirming high plasma durability.

[0051] Before and after conducting the first standard plasma test, the inventors measured the arithmetic mean height (Sa) of surface 210 of samples No.1 and No.2. Figure 6 In the table, the arithmetic mean height of surface 210, measured before the first standard plasma test, is shown in μm in the "Before Etching" column. The arithmetic mean height of surface 210, measured after the first standard plasma test, is shown in μm in the "After Etching" column. The difference between the two arithmetic mean heights is shown in the "ΔSa" column. That is, the change in the arithmetic mean height of surface 210 caused by the first standard plasma test is shown in μm. Furthermore, the method for measuring the arithmetic mean height uses the method specified in International Standard ISO 25178.

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

[0053] Thus, it can be confirmed that on samples No.1 and 2, where the hexagonal crystal content of the protective film 200 is greater than 0.15, the shape change of the surface 210 associated with etching is small.

[0054] The above description of this embodiment refers to specific examples. However, this disclosure is not limited to these specific examples. As long as the features of this disclosure are present, products with appropriate design modifications to these specific examples by those skilled in the art are also included within the scope of this disclosure. The elements, configurations, conditions, shapes, etc., of the aforementioned specific examples are not limited to the illustrated contents and can be appropriately modified. As long as no technical contradiction arises, the elements of the aforementioned specific examples can be appropriately changed and combined.

Claims

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

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

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

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