Structural members

Abstract

To provide a structural component with a highly durable protective film against plasma. [Solution] The structural member 10 comprises a base material 100 and a protective film 200 that covers the surface 110 of the base material 100 and mainly contains yttria. When the diffraction pattern obtained by analyzing the surface 210 of the protective film 200 using X-ray diffraction is defined as follows: P1 is the maximum intensity of the peak attributed to the (622) plane of the cubic crystal, P2 is the maximum intensity of the peak attributed to the (211) plane of the cubic crystal, P3 is the maximum intensity of the peak attributed to the (222) plane of the cubic crystal, P4 is the maximum intensity of the peak attributed to the (400) plane of the cubic crystal, P5 is the maximum intensity of the peak attributed to the (440) plane of the cubic crystal, and P6 is the maximum intensity of the peak attributed to the (541) plane of the cubic crystal, then for the structural member 10, P1 / (P1+P2+P3+P4+P5+P6)>0.015 holds.

Description

[Technical Field]

[0001] This invention relates to a structural member. [Background technology]

[0002] Components of semiconductor manufacturing equipment, such as the inner walls of chambers, require durability against plasma. Therefore, it is common practice to use structural components with a protective film formed on the surface of a substrate, as described in Patent Document 1 below. For the protective film, materials such as yttria are often used. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2007-321183 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] In semiconductor manufacturing equipment, repeated processing of substrates gradually degrades the protective film over time. To reduce the frequency of maintenance on semiconductor manufacturing equipment, it is desirable to have the highest possible durability of the protective film against plasma.

[0005] This invention has been made in view of these problems, and its objective is to provide a structural member with a protective film that has high durability against plasma. [Means for solving the problem]

[0006] To solve the above problems, the structural member according to the present invention comprises a base material and a protective film covering the surface of the base material, the protective film mainly composed of yttria. When the surface of the protective film is analyzed using X-ray diffraction and the diffraction pattern obtained is defined as follows, with P1 being the maximum intensity of the peak attributed to the (622) plane of the cubic crystal, P2 being the maximum intensity of the peak attributed to the (211) plane of the cubic crystal, P3 being the maximum intensity of the peak attributed to the (222) plane of the cubic crystal, P4 being the maximum intensity of the peak attributed to the (400) plane of the cubic crystal, P5 being the maximum intensity of the peak attributed to the (440) plane of the cubic crystal, and P6 being the maximum intensity of the peak attributed to the (541) plane of the cubic crystal, then in this structural member, P1 / (P1+P2+P3+P4+P5+P6)>0.015 holds.

[0007] Experiments conducted by the present inventors confirmed that when a protective film is formed using a material mainly composed of yttria, the greater the proportion of cubic (622) planes on the surface of the protective film, the higher the durability of the protective film against plasma. Specifically, it was confirmed that the durability of the protective film against plasma can be sufficiently increased if the above proportion is increased to such an extent that P1 / (P1+P2+P3+P4+P5+P6)>0.015 holds true. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a structural member with a protective film that has high 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 crystal plane ratio of the protective film and the durability of the protective film against plasma. [Figure 3] This is a diagram illustrating an analytical method using X-ray diffraction. [Figure 4] This is a diagram illustrating an analytical method using X-ray diffraction. [Figure 5]This is a diagram for explaining an analysis method using X-ray diffraction. [Figure 6] This is a table showing a list of film formation conditions and the like when forming a protective film.

Embodiments for Carrying Out the Invention

[0010] Hereinafter, this embodiment will be described with reference to the accompanying drawings. For ease of understanding of the description, the same reference numerals are given to the same components in each drawing as much as possible, and duplicate descriptions are omitted.

[0011] The structural member 10 according to this embodiment is configured as a member for a semiconductor manufacturing apparatus such as a plasma etching apparatus. Specifically, the structural member 10 is a member used as the inner wall of a processing chamber provided in a semiconductor manufacturing apparatus. Note that the use of such a structural member 10 is merely an example. The structural member 10 may be a member disposed inside a processing chamber provided in a semiconductor manufacturing apparatus, such as a focus ring.

[0012] As shown in FIG. 1, the structural member 10 includes a base material 100 and a protective film 200. In a plasma etching apparatus or the like, the surface 210 of the protective film 200 is exposed toward 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 member that generally occupies the entire structural member 10. In this embodiment, the base material 100 is a ceramic sintered body mainly containing high-purity alumina (Al2O3), but it may be a different type of ceramics, or a member other than ceramics (for example, a metal member). Also, the surface 110 of the base material 100 is a flat surface in this embodiment, but it may be a curved surface or the like. Also, 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 yttria (Y2O3). The ratio of the number of 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 physical vapor deposition (PVD), but it may also be a film formed using other film formation methods.

[0015] In this specification, "major component" refers to the compound that is present in the greatest quantity in the object (in this case, the protective film 200). Specifically, "major component" refers to a compound that, when quantitative or semi-quantitative analysis is performed on the object using X-ray diffraction (XRD), is found to be present in a relatively greater quantity by volume or mass ratio than any other compound in the object.

[0016] In the protective film 200 of this embodiment, the proportion of the main component (yttria) is greater than 50% by volume or mass. This proportion may be greater than 70%, greater than 90%, or even 100%.

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

[0018] The present inventors have decided to use yttria as the material for the protective film 200, as in this embodiment, and have been investigating ways to further improve the plasma resistance of the material. As a result, it has been confirmed that when the protective film 200 is formed using a material mainly composed of yttria, the plasma resistance of the protective film 200 changes depending on the crystal structure of the protective film 200. Specifically, it has been confirmed that the greater the proportion of cubic (622) planes on the surface 210 of the protective film 200, the higher the plasma resistance of the protective film 200.

[0019] The inventors prepared multiple samples of structural members 10 with different crystal structures in the protective film 200, and then evaluated the durability of each protective film 200 against plasma. To evaluate 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). Exposure of the surface 210 to the plasma atmosphere was performed using the following method.

[0020] First, a 4-inch silicon wafer was held in the chamber of an inductively coupled reactive ion etching apparatus using an electrostatic chuck. 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). Under these conditions, the test in which the surface 210 of the protective film 200 is exposed to a plasma atmosphere will be referred to as the "standard plasma test" below. In the 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.

[0021] Figure 2 shows the results of the standard plasma test performed on each of the multiple structural members 10. The horizontal axis of the graph in Figure 2, "crystal plane ratio," is an index that indicates the proportion of the surface 210 of the protective film 200 occupied by the (622) plane of the cubic crystal. The larger the proportion of the surface 210 of the protective film 200 occupied by the (622) plane of the cubic crystal, the larger the crystal plane ratio value. The specific definition and calculation method of the crystal plane ratio will be explained later.

[0022] The vertical axis of the graph in Figure 2 represents the fluorination amount of protective film 200 after the 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.

[0023] First, the surface 210 of the protective film 200, which had undergone a 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 can be used as an indicator of the durability of the protective film 200 against plasma.

[0024] As is clear from Figure 2, the larger the crystal plane ratio of the protective film 200, the smaller the amount of fluoride in the protective film 200 generally becomes. For protective films 200 with a crystal plane ratio greater than 0.015, the amount of fluoride was reduced to about 2500, confirming that they have sufficient durability against plasma.

[0025] The method for calculating the crystal plane ratio is explained below. The crystal plane ratio is calculated based on the results of analyzing the crystal structure of protective film 200 using X-ray diffraction.

[0026] The crystal plane ratio of the protective film 200 was measured using the following method. First, grazing-incidence X-ray diffraction (GIXRD) was performed on the protective film 200 formed on the substrate 100 using an out-of-plane measurement method.

[0027] X-ray diffraction is performed using an X-ray diffractometer (XRD) as shown in Figure 3, for example. In the XRD, X-rays of a specific wavelength generated by an X-ray generator (XR) are incident on the surface 210 of the protective film 200, which is the object of measurement. The scattered light generated on the surface 210 is detected by a detector (DT) to obtain an intensity distribution, i.e., a scattering angle θ. B The intensity distribution (diffraction pattern) of the scattered light for each X-ray corresponds to the crystal structure of the protective film 200. At this time, the incident angle θ of the X-rays on the surface 210 is AThe larger the angle of incidence θ, the more the resulting diffraction pattern corresponds to the crystal structure at a depth from the surface 210. A By performing X-ray diffraction while varying the parameters, the crystal structure of the protective film 200 at any desired depth can be investigated.

[0028] In this embodiment, a Rigaku Smart Lab X-ray diffractometer (XRD) was used. The tube voltage was set to 45kV, the tube current to 200mA, the scan range to 18-80°, the step to 0.05°, the scan speed to 0.5° / min, and the incident angle of the X-rays θ A The angle was set to 0.3°. The sample size was approximately 20mm x 20mm.

[0029] Line L10 in Figure 4 is an example of a diffraction pattern obtained by analyzing the protective film 200 using the X-ray diffraction method described above. 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 and crystal structure of the protective film 200. For example, the diffraction angle θ corresponding to the maximum value of each peak B This value corresponds to the crystal structure of protective film 200. Furthermore, the height of each peak corresponds to the diffraction angle θ. B The height corresponds to the proportion of the surface 210 of the protective film 200 occupied by the corresponding crystal structure.

[0030] 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 the crystal plane ratio of the protective film 200 with higher accuracy, in this embodiment, the maximum intensity value of each peak is obtained using the following method.

[0031] 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.

[0032] The line L11 shown in FIG. 5 represents a provisional diffraction pattern when only the peaks that reach the maximum at a diffraction angle θ of 20.72 degrees with respect to the background shown by the dashed line L0 in FIG. 4 are added. The same applies to the lines L12 to L22 shown in FIG. 5, and each represents a provisional diffraction pattern when only the peaks that reach the maximum at a specific diffraction angle θ with respect to the background are added. B The diffraction angle θ corresponding to the peak of line L12 B is 29.23 degrees, the diffraction angle θ corresponding to the peak of line L13

[0033] is 33.89 degrees, the diffraction angle θ corresponding to the peak of line L14 B is 41.70 degrees, the diffraction angle θ corresponding to the peak of line L15 B is 43.50 degrees, the diffraction angle θ corresponding to the peak of line L16 B is 48.41 degrees, the diffraction angle θ corresponding to the peak of line L17 B is 56.10 degrees, the diffraction angle θ corresponding to the peak of line L18 B is 56.70 degrees, the diffraction angle θ corresponding to the peak of line L19 B is 57.54 degrees, the diffraction angle θ corresponding to the peak of line L20 B is 58.83 degrees, the diffraction angle θ corresponding to the peak of line L21 B is 76.04 degrees, the diffraction angle θ corresponding to the peak of line L22 B is 77.11 degrees. B B

[0034] The dashed line L30 shown in FIG. 5 is a diffraction pattern obtained by superimposing all of the provisional diffraction patterns shown by the lines L11 to L22. This diffraction pattern is also referred to as the "approximate diffraction pattern L30" below. When superimposing multiple provisional diffraction patterns, the overlapping portion of the background is not added.

[0035] ​​Each of the provisional diffraction patterns shown by lines L11 to L22 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 diffraction angle θ at which the peak is maximized is adjusted. B By individually adjusting values ​​such as the height of the peak relative to the background, the waveform of the approximate diffraction pattern L30 is brought closer to the measured diffraction pattern L10. When the waveforms of both patterns roughly match as a result of this process, each of the provisional diffraction patterns shown by lines L11 to L22 will have a diffraction angle θ of the measured diffraction pattern L10. B This corresponds to waveforms decomposed into individual waveforms. This process can be performed manually while observing waveforms such as the approximate diffraction pattern L30, but it can also be performed automatically using software functions.

[0036] If the material of the protective film 200 is yttria, the diffraction angle θ of the peak attributed to the (622) plane of the cubic crystal is B It is known that this is approximately 57.62 degrees. Therefore, in the example shown in Figure 5, the peak attributed to the (622) plane of the cubic crystal can be inferred to be the peak of line L19. 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 P1" below.

[0037] If the material of the protective film 200 is yttria, the diffraction angle θ of the peak attributed to the (211) plane of the cubic crystal is B It is known that this is approximately 20.49 degrees. Therefore, in the example shown in Figure 5, the peak attributed to the (211) plane of the cubic crystal can be inferred to be the peak of line L11. 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 P2" below.

[0038] If the material of the protective film 200 is yttria, the diffraction angle θ of the peak attributed to the (222) plane of the cubic crystal is BIt is known that this is approximately 29.15 degrees. Therefore, in the example shown in Figure 5, the peak attributed to the (222) plane of the cubic crystal can be inferred to be the peak of line L12. 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 P3" below.

[0039] If the material of the protective film 200 is yttria, the diffraction angle θ of the peak attributed to the (400) plane of the cubic crystal is B It is known that this is approximately 33.78 degrees. Therefore, in the example shown in Figure 5, the peak attributed to the (400) plane of the cubic crystal can be inferred to be the peak of line L13. 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 P4" below.

[0040] If the material of the protective film 200 is yttria, the diffraction angle θ of the peak attributed to the (440) plane of the cubic crystal is B It is known that this is approximately 48.54 degrees. Therefore, in the example shown in Figure 5, the peak attributed to the (440) plane of the cubic crystal can be inferred to be 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 P5" below.

[0041] If the material of the protective film 200 is yttria, the diffraction angle θ of the peak attributed to the (541) plane of the cubic crystal is B It is known that this is approximately 56.17 degrees. Therefore, in the example shown in Figure 5, the peak attributed to the (541) plane of the cubic crystal can be inferred to be 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 P6" below.

[0042] In Figure 5, only the maximum intensities P1 and P6 are shown, while the maximum intensities P2 to P5 are omitted from the illustration.

[0043] Using the maximum intensity values ​​P1 to P6 calculated by the method described above, the crystal plane ratio is defined and calculated as shown in equation (1) below. Crystal plane ratio = P1 / (P1+P2+P3+P4+P5+P6)···(1)

[0044] As mentioned earlier, the maximum intensity P1 is the maximum intensity of the peak attributed to the (622) plane of the cubic crystal. Therefore, the crystal plane ratio defined by equation (1) above can be used as an indicator of the proportion of the (622) plane of the cubic crystal on the surface 210 of the protective film 200. As described with reference to Figure 2, if the crystal plane ratio = P1 / (P1+P2+P3+P4+P5+P6)>0.015 holds true on the surface 210 of the protective film 200, then sufficient durability against plasma is ensured for the protective film 200.

[0045] Note that the waveform examples shown in Figures 4 and 5 are examples used to explain the definition and calculation method of crystal plane ratio, and do not correspond to the protective film 200 according to this embodiment.

[0046] The manufacturing methods for each sample used to obtain the data in Figure 2 will be explained with reference to Figure 6. In the same figure, the sample shown as "No. 1" is a sample prepared under conditions such that the crystal plane ratio on the surface 210 of the protective film 200 is 0.014. "No. 2" is a sample prepared under conditions such that the crystal plane ratio on the surface 210 of the protective film 200 is 0.019, "No. 3" is a sample prepared under conditions such that the crystal plane ratio on the surface 210 of the protective film 200 is 0.156, and "No. 4" is a sample prepared under conditions such that the crystal plane ratio on the surface 210 of the protective film 200 is 0.206.

[0047] "No. 5" is a sample prepared under conditions where the crystal plane ratio on the surface 210 of the protective film 200 is 0.278, "No. 6" is a sample prepared under conditions where the crystal plane ratio on the surface 210 of the protective film 200 is 0.608, "No. 7" is a sample prepared under conditions where the crystal plane ratio on the surface 210 of the protective film 200 is 0.676, and "No. 8" is a sample prepared under conditions where the crystal plane ratio on the surface 210 of the protective film 200 is 0.878.

[0048] In the table in Figure 6, the "Substrate" column shows the composition of the surface 110 of the substrate 100, which is alumina. In sample No. 1, the surface 110 of the substrate 100 is amorphous. In samples No. 2, 5-7, the surface 110 of the substrate 100 is polycrystalline. In samples No. 3, 4, and 8, the surface 110 of the substrate 100 is monocrystalline.

[0049] The protective films 200 for samples No. 1 to 8 were all formed using physical vapor deposition (PVD). In the table in Figure 6, the "Pressure" column shows the pressure inside the deposition chamber during the formation of the protective film 200, specifically the argon pressure, expressed in units of "Pa".

[0050] In the table in Figure 6, the "Sa" column shows the arithmetic mean height (Sa) of the surface 110 immediately before the protective film 200 is formed, expressed in units of "μm".

[0051] In the table in Figure 6, the "Hardness" column shows the indentation hardness of the protective film 200 immediately after deposition (i.e., before the standard plasma test) 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. 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 value 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.

[0052] As shown in Figure 6, each of the samples from No. 1 to 8 differs from the others in the composition of the surface 110 of the substrate 100, the arithmetic mean height, and the deposition conditions of the protective film 200 (specifically, the pressure in the deposition chamber). As a result, the crystal plane ratio of the protective film 200 also differs from the others.

[0053] After calculating the crystal plane ratio for each of the samples No. 1 to 8, a standard plasma test was performed, and the results shown in Figure 2 were obtained. In the table in Figure 6, the "Crystal Plane Ratio" column shows the calculated crystal plane ratio values ​​for each sample. As described with reference to Figure 2, it was confirmed that the greater the crystal plane ratio value of the protective film 200, the better the durability of the protective film 200 against plasma.

[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 210: Surface

Claims

1. Substrate and A protective film comprising a film covering the surface of the substrate, the protective film mainly containing yttria, In the diffraction pattern obtained by analyzing the surface of the protective film using X-ray diffraction, Let P1 be the maximum intensity of the peak attributed to the (622) plane of the cubic crystal. Let P2 be the maximum intensity of the peak attributed to the (211) plane of the cubic crystal. Let P3 be the maximum intensity of the peak attributed to the (222) plane of the cubic crystal. Let P4 be the maximum intensity of the peak attributed to the (400) plane of the cubic crystal. Let P5 be the maximum intensity of the peak attributed to the (440) plane of the cubic crystal. When the maximum intensity of the peak attributed to the (541) plane of the cubic crystal is defined as P6, A structural member characterized by the fact that P1 / (P1+P2+P3+P4+P5+P6) > 0.

015.

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

3. The structural member according to claim 1, characterized in that the base material contains alumina as the main component.

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