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 covering the surface 110 of the base material 100. The protective film 200 includes a first portion 201 which is the part exposed on the surface 210 side and a second portion 202 which is the part located further back than the first portion 201. The proportion of monoclinic crystal structure in the first portion 201 is greater than the proportion of monoclinic crystal structure in the second portion 202.

Description

[Technical Field]

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

[0002] Structural members having a protective film on the surface of a substrate are used in various fields such as semiconductor manufacturing equipment. For example, as described in Patent Document 1 below, in semiconductor manufacturing equipment, a protective film is formed on the surface of the substrate constituting the inner wall of the chamber to protect the substrate from plasma. Such protective films can be made of oxide ceramics such as yttria. [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 includes a first portion which is the most exposed part on the surface side and a second portion which is the part deeper than the first portion. In this structural member, the proportion of monoclinic crystal structure in the first portion is greater than the proportion of monoclinic crystal structure in the second portion.

[0007] Experiments conducted by the inventors confirmed that when the surface of a protective film contains a monoclinic crystal structure, its resistance to plasma is higher compared to when it does not. Because the chemical properties of a monoclinic crystal structure are relatively unstable, it is easily affected and its properties change when exposed to plasma. Therefore, it is thought that by placing a monoclinic crystal structure on the surface of the protective film (i.e., the first part), the effects of the plasma are less likely to reach the deeper second part. As a result, the overall resistance of the protective film to plasma is improved.

[0008] The monoclinic crystal structure may be present only in the first part, or in both the first and second parts. In either case, by making the proportion of the monoclinic crystal structure in the first part relatively higher than the proportion in the second part, the durability of the protective film against plasma can be increased. [Effects of the Invention]

[0009] 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]

[0010] [Figure 1] This figure schematically shows a cross-section of a structural member according to the first embodiment. [Figure 2] This is a diagram illustrating a method for manufacturing a structural member according to the first embodiment. [Figure 3]This is a diagram for explaining an analysis method using X-ray diffraction. [Figure 4] This is a diagram for explaining an analysis 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 diagram for explaining a manufacturing method of a structural member according to the second embodiment.

Mode for Carrying Out the Invention

[0011] Hereinafter, this embodiment will be described with reference to the accompanying drawings. For ease of understanding the description, the same reference numerals are attached to the same components in each drawing as much as possible, and redundant descriptions are omitted.

[0012] The first embodiment will be described. The structural member 10 according to this embodiment is used as a member constituting the inner wall of a processing chamber in a semiconductor manufacturing apparatus (not shown) such as a plasma etching apparatus. Note that the use of such a structural member 10 is merely an example and is not limited to semiconductor manufacturing apparatuses.

[0013] 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 chamber. The protective film 200 is provided for the purpose of protecting the surface 110 of the base material 100 from plasma.

[0014] 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 containing high-purity aluminum oxide (Al2O3), but it may be a different type of ceramics or a member other than ceramics (for example, a metal member). Further, the surface 110 of the base material 100 is a flat surface in this embodiment, but the surface 110 may have irregularities, inclinations, or the like.

[0015] As mentioned earlier, 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. In this embodiment, the protective film 200 is composed mainly of polycrystalline yttrium oxide (Y2O3), but it may be a ceramic film made of a different material. The thickness of the protective film 200 is set appropriately according to the length of time for which durability needs to be maintained. In this embodiment, the thickness of the protective film 200 is 10 μm.

[0016] The protective film 200 in this embodiment is formed on the surface 110 of the substrate 100 after firing by physical vapor deposition (PVD). The method for forming the protective film 200 is not limited to physical vapor deposition; other methods may be used. For example, the protective film 200 may be formed using chemical vapor deposition (CVD).

[0017] In Figure 1, the area enclosed by the dashed line DL1 is the outer surface 210 of the protective film 200 (i.e., the side opposite to the substrate 100). This area will also be referred to as "Part 1 201" below. The area enclosed by the dashed line DL2 in the same figure is the area of ​​the protective film 200 that is further inside than Part 1 201 (i.e., on the substrate 100 side). This area will also be referred to as "Part 2 202" below.

[0018] Note that the dashed line DL1 in Figure 1 shows only a portion of the first part 201, not the entirety. The first part 201 is the entire portion of the protective film 200 that is at the same height as the dashed line DL1 in Figure 1. Similarly, the dashed line DL2 in Figure 2 shows only a portion of the second part 202, not the entirety. The second part 202 is the entire portion of the protective film 200 that is at the same height as the dashed line DL2 in Figure 1. Note that the second part 202 may be any portion of the protective film 200 that is closer to the substrate 100 than the first part 201, and may be at a different height than the dashed line DL2 in Figure 1.

[0019] The protective film 200 of this embodiment is formed entirely of the same material, including the first portion 201 and the second portion 202, that is, a material mainly composed of polycrystalline yttrium oxide. However, the first portion 201 and the second portion 202 differ from each other in their crystal structure. Specifically, the proportion of monoclinic crystal structure in the first portion 201 is greater than the proportion of monoclinic crystal structure in the second portion 202.

[0020] Furthermore, monoclinic and cubic crystal structures coexist in various parts of the protective film 200. When observing a specific region of the protective film 200 (for example, a region of unit volume), if NM is the total number of crystals in that region that have a monoclinic crystal structure, and NC is the total number of crystals in that region that have a cubic crystal structure, then the "proportion occupied by monoclinic crystal structure" can be defined as a value calculated using, for example, the formula NM / NC. However, in determining such a relative proportion, it is not necessary to individually and quantitatively calculate the "proportion occupied by monoclinic crystal structure" for each region. A specific method for determining the relative proportions without individually calculating values ​​such as NM and NC will be explained later.

[0021] A method for manufacturing the structural member 10 will be described with reference to Figure 2. As shown in Figure 2(A), first a base material 100 is prepared. It is preferable to pre-polish the surface 110 of the base material 100 so that the surface 110 becomes a smooth surface suitable for forming the protective film 200.

[0022] Next, as shown in Figure 2(B), a protective film 200 is formed to cover the entire surface 110. As mentioned earlier, in this embodiment, the protective film 200 is formed using physical vapor deposition (PVD), but the protective film 200 may be formed using other methods.

[0023] In the state shown in Figure 2(B), where the formation of the protective film 200 is complete, almost the entirety of the yttrium oxide crystals constituting the protective film 200 has a cubic crystal structure. In other words, the yttrium oxide crystals constituting the protective film 200 contain almost no crystals with a monoclinic crystal structure.

[0024] Next, the surface 210 of the protective film 200 is subjected to an impact. For example, as shown in Figure 2(C), the entire surface 210 can be impacted by moving the nozzle NZ of the sandblasting apparatus along arrow AR while spraying abrasive material from the nozzle NZ toward the surface 210. When impact is applied to the surface 210, a phase transition occurs in the surface 210 and its vicinity of the protective film 200, and the crystal structure of some parts changes from cubic to monoclinic. The strength of the impact applied to the surface 210, for example, the spraying speed when spraying the abrasive material from the nozzle NZ, can be appropriately adjusted according to the material and thickness of the protective film 200. The spraying speed of the abrasive material required to cause a phase transition of the crystal structure of the vicinity of the surface 210 from cubic to monoclinic is often smaller than the spraying speed of the abrasive material required to create irregularities on the surface 210 by sandblasting. A method other than the above may be used to cause a phase transition in part of the surface 210 by applying impact.

[0025] In the protective film 200, the above-mentioned phase transition occurs when an impact is applied, and the monoclinic crystal structure increases on the surface 210 and its vicinity. As a result, as mentioned earlier, the proportion of the monoclinic crystal structure in the first part 201 becomes larger than the proportion of the monoclinic crystal structure in the second part 202.

[0026] Experiments conducted by the present inventors have confirmed that when the surface 210 of the protective film 200 contains a monoclinic crystal structure, its resistance to plasma is higher compared to when it does not. Because the chemical properties of a monoclinic crystal structure are relatively unstable, it is easily affected and its properties change when exposed to plasma. Therefore, it is thought that by placing a monoclinic crystal structure on the surface 210 of the protective film 200 (i.e., the first part 201), the effects of the plasma are less likely to reach the deeper second part 202. As a result, it is thought that the overall resistance of the protective film 200 to plasma is improved.

[0027] This section describes an example of a specific method for evaluating the relative proportions of the "monoclinic crystal structure" in each part of the protective film 200. As is well known, the crystal structure of the protective film 200 can be analyzed, for example, by using X-ray diffraction.

[0028] 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 of scattered light (scattering spectrum) 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 determined. A The larger the angle of incidence θ, the more the resulting scattering spectrum 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.

[0029] 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 AIt was set to 0.3°. The sample size was set to approximately 20 mm × 20 mm. In addition, when the intensity of the X-ray diffraction pattern obtained by analyzing the protective film 200 using X-ray diffraction becomes low, it becomes impossible to distinguish between the monoclinic crystal structure and the cubic crystal structure. Therefore, preferably, the peak intensity is 100 cps or more at the dotted line DL12 (scattering angle θ of 29.15 degrees B ) after subtracting the background.

[0030] The line L10 in FIG. 4 is an example of a diffraction pattern, that is, a scattering spectrum, obtained by analyzing the protective film 200 using X-ray diffraction. This scattering spectrum is hereinafter also referred to as the "measured spectrum L10". A plurality of peaks appear in the measured spectrum L10, and each peak is specific to the material of the protective film 2 and its crystal structure. For example, the scattering angle θ B corresponding to the maximum value of each peak is a value corresponding to the crystal structure of the protective film 200. Also, the height of each peak is the height corresponding to the ratio of the crystal structure corresponding to the scattering angle θ B occupied in the protective film 200.

[0031] The dotted line DL12 shown in FIG. 4 represents a scattering angle θ of 29.15 degrees B . For example, as described in PDF card number: 00-041-1105, when the material of the protective film 200 is yttrium oxide as in this embodiment, and the measured portion of the protective film 200 contains a cubic crystal structure and the 222 plane appears at that portion, a peak with the maximum intensity appears at the scattering angle θ of 29.15 degrees B . In other words, when the measured portion of the protective film 200 does not contain a cubic crystal structure, the peak corresponding to the scattering angle θ of 29.15 degrees B does not appear.

[0032] Also, the dotted line DL13 shown in the figure represents a scattering angle θ of 30.3 degrees BThis represents the following. For example, as described in PDF card number 00-044-0399, in this embodiment, when the material of the protective film 200 is yttrium oxide, and the measurement site of the protective film 200 contains a monoclinic crystal structure and a 40-2 plane is present at that site, the scattering angle θ is 30.3 degrees. B The peak with maximum intensity appears at this point. In other words, if the measured area of ​​the protective film 200 does not contain a monoclinic crystal structure, the scattering angle θ is 30.3 degrees. B No corresponding peak appears.

[0033] 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 composition ratio of monoclinic and cubic crystals in the protective film 200 with higher accuracy, in this embodiment, the maximum intensity value of each peak is obtained using the following method.

[0034] The dashed line L0 shown in Figure 4 represents the background scattering intensity when no peaks appear. Scattering angle θ B The smaller L0 becomes, the greater the background scattering intensity tends to be. The waveform of the dashed line L0 can be inferred and obtained, for example, from the overall waveform of the scattering spectrum.

[0035] The line L11 shown in Figure 5 represents the scattering angle θ of DL11 (28.6 degrees) relative to the background shown by the dashed line L0 in Figure 4. B This represents a hypothetical scattering spectrum obtained by summing only the peaks that are largest in that region. The same applies to lines L12 to L16 shown in Figure 5, each with a specific scattering angle θ relative to the background. B This represents a hypothetical scattering spectrum obtained by summing only the peaks with the maximum values ​​at DL12. B This is 29.15 degrees, and the scattering angle θ corresponds to DL13. B This is 30.3 degrees, and the scattering angle θ corresponds to DL14. B This is 31.5 degrees, and the scattering angle θ corresponds to DL15. BThis is 32.5 degrees, and the scattering angle θ corresponds to DL16. B The temperature is 33.7 degrees.

[0036] The dashed line L20 shown in Figure 5 is the scattering spectrum obtained by superimposing all the provisional scattering spectra shown by lines L11 to L16. This scattering spectrum will also be referred to as the "approximate spectrum L20" below. When superimposing the multiple provisional scattering spectra, the overlapping background is not added.

[0037] Each of the provisional scattering spectra shown by lines L11 to L16 is individually adjusted so that the waveform of the approximate spectrum L20 obtained by summing them up roughly matches the measured spectrum L10 shown in Figure 4. In other words, for each of the lines L11, etc., the scattering 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 spectrum L20 is brought closer to the measured spectrum L10. When the waveforms of the two roughly match as a result of this process, each of the provisional scattering spectra shown by lines L11 to L16 will have a scattering angle θ of the measured spectrum L10. B This corresponds to waveforms decomposed into individual waveforms. This process can be performed manually while observing waveforms such as the approximate spectrum L20, but it can also be performed automatically using software functions.

[0038] Of the "provisional scattering spectra" obtained as described above, the maximum intensity of the peak corresponding to the 222-plane and having a cubic crystal structure, specifically the maximum intensity of the peak relative to the background, will hereafter be referred to as the "maximum intensity IC." In the case where the material of the protective film 200 is yttrium oxide, as in this embodiment, the maximum intensity IC can be said to be "the maximum intensity of the peak corresponding to the 222-plane of cubic yttrium oxide."

[0039] As mentioned earlier, if the material of the protective film 200 is yttrium oxide, it has a cubic crystal structure and the scattering angle θ of the peak corresponding to the 222 plane. B This corresponds to 29.15 degrees. Therefore, in the example in Figure 5, the peak height indicated by line L12 is obtained as the maximum intensity IC.

[0040] In the "provisional scattering spectrum," the height of the peak corresponding to the 40-2 plane, which is a monoclinic crystal structure, specifically the height of the peak relative to the background, will hereafter be referred to as "maximum intensity IM." In this embodiment, when the material of the protective film 200 is yttrium oxide, the maximum intensity IM can be said to be "the maximum intensity of the peak corresponding to the 40-2 plane of monoclinic yttrium oxide."

[0041] As mentioned earlier, if the material of the protective film 200 is yttrium oxide, it has a monoclinic crystal structure and the scattering angle θ of the peak corresponding to the 40-2 plane. B This becomes 30.3 degrees. Therefore, in the example in Figure 5, the peak height indicated by line L13 is obtained as the maximum intensity IM.

[0042] The ratio of the maximum intensity of the peak corresponding to the 40-2 plane of monoclinic yttrium oxide (i.e., maximum intensity IM) to the maximum intensity of the peak corresponding to the 222 plane of cubic yttrium oxide (i.e., maximum intensity IC), i.e., the value of IM / IC, can be used as an indicator of the proportion of monoclinic crystal structure occupied at the measurement site of the protective film 200. When the structural member 10 is manufactured using the method described with reference to Figure 2, the IM / IC value measured at the depth position of the first part 201 is greater than the IM / IC value measured at the depth position of the second part 202. In other words, the proportion of monoclinic crystal structure occupied in the first part 201 is greater than the proportion of monoclinic crystal structure occupied in the second part 202.

[0043] According to experiments conducted by the present inventors, it has been confirmed that if the IM / IC value measured on the surface 210 of the protective film 200 or its vicinity (i.e., the first portion 201) is 0.2 or higher, the protective film 200 has sufficient durability against plasma.

[0044] To further enhance the durability of the protective film 200 against plasma, it is preferable to make the surface 210 as smooth as possible. Specifically, it is preferable to polish the surface 210 so that its arithmetic mean height (Sa) is 0.01 μm or less. A laser microscope, "OLS4000 / Olympus," was used to examine the condition of the surface 210. The objective lens magnification was 100x.

[0045] The second embodiment will now be described. The following will primarily focus on the differences from the first embodiment, while common points will be omitted as appropriate.

[0046] In this embodiment, the method for forming the protective film 200 differs from that of the first embodiment. The method for manufacturing the structural member 10 of this embodiment will be described with reference to Figure 6. As shown in Figure 6(A), first a base material 100 is prepared. It is preferable to pre-polish the surface 110 of the base material 100 so that the surface 110 becomes a smooth surface suitable for forming the protective film 200.

[0047] Next, as shown in Figure 6(B), a protective film 200A is formed to cover the entire surface 110. The protective film 200A is made of the same material as the protective film 200 in the first embodiment, but its thickness is thinner than that of the protective film 200 in the first embodiment. Physical vapor deposition (PVD) is used as the method for forming the protective film 200A.

[0048] In the state shown in Figure 6(B), where the formation of protective film 200A is complete, almost the entirety of the yttrium oxide crystals constituting protective film 200A has a cubic crystal structure. In other words, the yttrium oxide crystals constituting protective film 200A contain almost no crystals with a monoclinic crystal structure.

[0049] Next, as shown in Figure 6(C), a protective film 200B is formed so as to cover the entire surface 211 of the protective film 200A. The protective film 200B is also made of the same material as the protective film 200 in the first embodiment. The aerosol deposition method is used to form the protective film 200B. Through this process, the protective film 200 of this embodiment becomes a two-layer film consisting of a protective film 200A on the substrate 100 side and a protective film 200B on the surface 210 side. Its overall thickness is the same as the thickness of the protective film 200 in the first embodiment.

[0050] As is well known, in the aerosol deposition method, fine particles, which are the material for the protective film 200B, are dispersed in a gas to form an "aerosol," which is then sprayed from a nozzle onto the surface 211 and collided with it. On the surface 211, the impact of the collision causes deformation and fragmentation of the fine particles, and as the fine particles combine with each other, they gradually accumulate to form the protective film 200B.

[0051] The protective film 200B grows while being subjected to impacts from particle collisions on its surface. As a result, the protective film 200B grows while changing its crystal structure from the initial cubic crystal to a monoclinic crystal. At this time, a similar change may occur in the protective film 200A, but the proportion of monoclinic crystal structure in protective film 200A is smaller than the proportion of monoclinic crystal structure in protective film 200B.

[0052] In this embodiment, if a portion of the protective film 200B, including the surface 210, is designated as the first portion 201 and a portion of the protective film 200A as the second portion 202, then, as in the first embodiment, the proportion of monoclinic crystal structure in the first portion 201 will be greater than the proportion of monoclinic crystal structure in the second portion 202. In this embodiment, even if the first portion 201 is formed using the position method with aerosols and the second portion 202 is formed using the physical vapor deposition method, the same effects as those described in the first embodiment can be achieved.

[0053] 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]

[0054] 10: Structural members 100: Base material 110: Surface 200: Protective film 201: Part 1 202:Second part 210: Surface

Claims

1. Substrate and The substrate comprises a protective film covering the surface of the substrate, The protective film is The first part is the part that is exposed on the outermost surface, Including a second part which is the part located further back than the first part, In the first part, the proportion occupied by the monoclinic crystal structure is, A structural member characterized in that the proportion of the second portion is greater than the proportion occupied by the monoclinic crystal structure.

2. The structural member according to claim 1, characterized in that the protective film contains yttrium oxide as a main component.

3. In the diffraction pattern obtained by analyzing the surface of the protective film using X-ray diffraction, The structural member according to claim 2, characterized in that the ratio of the maximum intensity of the peak corresponding to the 40-2 plane of monoclinic yttrium oxide to the maximum intensity of the peak corresponding to the 222 plane of cubic yttrium oxide is 0.2 or more.

4. The first portion is formed using the aerosol deposition method, The structural member according to claim 1, characterized in that the second portion is formed using a physical vapor deposition method.

5. The structural member according to claim 1, characterized in that the arithmetic mean height of the surface of the protective film is 0.01 μm or less.

Images