Structural member and manufacturing method for the same

Abstract

To provide a structural member that can ensure sufficient durability against plasma and a manufacturing method for the same.SOLUTION: A structural member 10 includes a base material 100 and a protective film 200 that covers a surface 101 of a base material 100. The protective film 200 is subjected to a reduction treatment that reduces the in-plane variation of residual stress on a surface 201.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a structural member and a method for manufacturing the same. [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 a semiconductor manufacturing equipment, a protective film is formed on the surface of a substrate constituting an inner wall of a chamber to protect the substrate from plasma. For example, oxide ceramics such as yttria are used as such a protective film. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-321183 A Summary of the Invention [Problem to be solved by the invention]

[0004] Since the protective film is a film for protecting the substrate from plasma as described above, it must have sufficient durability against plasma. However, the durability of a part of the protective film may be locally decreased, and the deteriorated protective film may become a source of particle generation. The present inventors have conducted extensive research into the cause. As a result, a new finding has been obtained that when the residual stress caused by polishing during manufacturing is locally increased on the surface of the protective film, the durability of the part (specifically, the halogen resistance against fluorine, chlorine, etc.) is decreased.

[0005] The present invention has been made in view of the above problems, and an object of the present invention is to provide a structural member capable of ensuring sufficient durability against plasma, and a manufacturing method thereof. [Means for solving the problem]

[0006] In order to achieve the above object, a structural member according to the present invention includes a base material and a protective film covering a surface of the base material. The protective film is subjected to a reduction treatment for reducing in-plane variations in residual stress on the surface of the protective film.

[0007] In such structural members, a reduction treatment is applied to the surface of the protective film. The "reduction treatment" refers to a reduction that reduces the in-plane variation of the residual stress on the surface. Such a reduction treatment may include, for example, a process of releasing and smoothing the localized residual stress by heating, or a process of removing part of the protective film by etching or the like. By applying the reduction treatment, the distribution of the residual stress on the surface of the protective film becomes roughly uniform. As a result, sufficient durability against plasma can be ensured throughout the entire protective film.

[0008] The manufacturing method of the structural member as described above includes the steps of preparing a substrate, forming a protective film on the surface of the substrate, and performing a reduction treatment, which is a treatment for reducing the in-plane variation of residual stress on the surface of the protective film. Effect of the Invention

[0009] According to the present invention, it is possible to provide a structural member capable of ensuring sufficient durability against plasma, and a method for manufacturing the same. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a schematic cross-sectional view of a structural member according to the present embodiment. [Diagram 2] 1 is an image obtained by observing the surface of a structural member according to this embodiment with an electron microscope. [Diagram 3] 1A and 1B are diagrams for explaining the distribution of residual stress on the surface of a protective film. [Figure 4] 4A to 4C are diagrams for explaining a method for manufacturing a structural member according to the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, the present embodiment will be described with reference to the accompanying drawings. In order to facilitate understanding of the description, the same components in each drawing are denoted by the same reference numerals as much as possible, and duplicated description will be omitted.

[0012] 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 use in semiconductor manufacturing apparatus.

[0013] 1, the structural member 10 includes a substrate 100 and a protective film 200. In a plasma etching device or the like, a surface 201 of the protective film 200 is exposed to the space inside a chamber. The protective film 200 is provided for the purpose of protecting the surface 101 of the substrate 100 from plasma.

[0014] The substrate 100 is a member that occupies almost the entirety of the structural member 10. In this embodiment, the substrate 100 is a ceramic sintered body containing high-purity aluminum oxide (Al2O3), but may be a different type of ceramic. In this embodiment, the surface 101 of the substrate 100 is a flat surface, but the surface 101 may have irregularities, inclinations, or the like.

[0015] As described above, the protective film 200 is a film formed to protect the substrate 100 from plasma. The protective film 200 is formed so as to cover the entire surface 101 of the substrate 100. The protective film 200 is a film containing polycrystalline yttria (Y2O3), and is formed by using an aerosol deposition method in this embodiment. The thickness of the protective film 200 is appropriately set according to the length of time for which durability is required to be maintained, etc. In this embodiment, the thickness of the protective film 200 is 10 μm. The material and formation method of the protective film 200 may be different from those described above.

[0016] As will be described later, after the protective film 200 is formed on the substrate 100, the surface 201 is mechanically polished for the purpose of adjusting the surface roughness of the surface 201, etc. FIG. 2 shows an image of the surface 201 immediately after polishing, observed with an electron microscope. As shown in the figure, many scratches SC are formed on the surface 201 after polishing. Each scratch SC is a mark left by the surface 201 of the protective film 200 being scraped by a minute diamond abrasive grain.

[0017] However, in conventional structural members, when exposed to plasma in a processing chamber, a portion of the protective film deteriorates more than the surrounding area, and the deteriorated portion may become a source of particle generation. The present inventors have conducted extensive research into the cause of this local decrease in durability in a portion of the protective film. As a result, it was found that the durability against plasma is significantly decreased in the portion of the surface of the protective film that has scratches SC as shown in Figure 2. Further research revealed that the cause of the local decrease in the durability of the protective film against plasma is a local increase in residual stress in the protective film.

[0018] The above-mentioned "residual stress" is generated, for example, when the surface 201 is polished, and remains in the protective film 200 along each scratch SC as shown in FIG. 2. The present inventors have confirmed that if the polished surface 201 is exposed to fluorine-based plasma without carrying out the reduction treatment described below, the scratch SC portion (i.e., the portion with large residual stress) is fluorinated more deeply than the surrounding area. The present inventors have also confirmed, using a technique such as Raman scattering spectroscopy, that the residual stress in the scratch SC portion is larger than the surrounding area immediately after polishing. From the above, it is considered that the localized residual stress reduces the chemical resistance of the protective film 200 in that portion.

[0019] 3 is a schematic diagram of a cross section of the protective film 200 immediately after polishing. In the cross section, the part with different hatching and reference numeral 211 indicates a part where stress generated during polishing remains. The residual stress in the scratch SC is larger and remains deeper than the residual stress in the surrounding area. Therefore, the inner surface of the scratch SC has lower plasma resistance than the surrounding area.

[0020] If the surface 201 of the protective film 200 is exposed to plasma in this state, the inner surface of the scratch SC will be deteriorated by the plasma, and the deteriorated protective film 200 may become a source of particle generation. It is believed that the deteriorated portion becomes a source of particle generation because the protective film 200 expands in volume due to fluorination, etc., causing a large number of microcracks to occur on the surface 201.

[0021] Therefore, in the structural member 10 according to this embodiment, a reduction treatment is applied to the polished surface 201. The "reduction treatment" refers to a treatment for reducing the in-plane variation of the residual stress in the surface 201. Various treatments can be adopted as the reduction treatment, but in this embodiment, a treatment for heating the entire structural member 10 including the protective film 200 to a predetermined temperature or higher is performed as the reduction treatment.

[0022] In the case where the protective film 200 is a film containing yttria (Y2O3) as in this embodiment, it is preferable to heat the protective film 200 to a temperature of 800° C. or higher. By carrying out such a treatment, localized residual stresses, particularly at the scratches SC, are released, and the in-plane variation of the residual stresses in the protective film 200 is reduced. As a result of the distribution of the residual stresses in the surface 201 of the protective film 200 becoming roughly uniform, sufficient durability against plasma can be ensured throughout the entire protective film 200.

[0023] The reduction process may be a process of releasing and smoothing the local residual stress by heating or the like as described above, or may be a process of removing a portion of the protective film 200 having a large residual stress (specifically, a surface layer portion). In this case, it is preferable to adopt a process of chemically etching the surface 201 of the protective film 200 so that new residual stress is not generated by the removal. When the protective film 200 is a film containing yttria (Y2O3) as in this embodiment, the surface layer portion of the protective film 200 can be removed using, for example, hydrochloric acid. Instead of chemical etching, the surface layer portion of the protective film 200 may be physically removed by a method such as shot peening.

[0024] Incidentally, the in-plane variation of the residual stress in the protective film 200 may occur due to a cause other than the polishing of the surface 201 as described above. Even in such a case, it is preferable to reduce the in-plane variation of the residual stress by performing a reduction process on the surface 201. In other words, the target of the reduction process may be the surface 201 that has not been polished.

[0025] A method for manufacturing the structural member 10 will be described with reference to Fig. 4. First, a substrate 100 is prepared as shown in Fig. 4(A). It is preferable that the surface roughness, etc. of a surface 101 of the substrate 100 is adjusted in advance so that a protective film 200 can be formed thereon stably later.

[0026] 4(B), a protective film 200 is formed to cover the surface 101 of the substrate 100. As described above, in this embodiment, the protective film 200 is formed by using the aerosol deposition method, but the protective film 200 may be formed by other methods. For example, the protective film 200 may be formed by PVD or CVD.

[0027] Next, the surface 201 of the protective film 200 is mechanically polished. This adjusts the surface roughness, etc., of the surface 201. FIG. 4C shows a schematic diagram of the state of the surface 201 after polishing. A large number of scratches SC (not shown in FIG. 4C) as shown in FIG. 2 are formed on the surface 201. Furthermore, residual stress occurs in the surface 201 as a result of polishing. In FIG. 4C, like FIG. 3, the portion where the stress remains is marked with the reference symbol "211". As explained above, the residual stress in the scratch SC portion is larger and remains deeper than the residual stress in the surrounding area.

[0028] After polishing is completed, a stress reduction process is performed on surface 201. This releases the residual stress in surface 201. When the stress reduction process is performed, as shown in FIG. 4(D), the portion (portion 211) where the residual stress is locally high in surface 201 generally disappears. In other words, the in-plane variation in the residual stress is reduced. This ensures sufficient durability of the protective film against plasma.

[0029] The present embodiment has been described above with reference to specific examples. However, the present disclosure is not limited to these specific examples. Any design modifications made by a person skilled in the art to these specific examples are also included within the scope of the present disclosure as long as they have the features of the present disclosure. The elements of each of the above-mentioned specific examples and their arrangements, conditions, shapes, etc. are not limited to those exemplified and can be changed as appropriate. The combination of each of the elements of each of the above-mentioned specific examples can be changed as appropriate as long as no technical contradiction occurs. [Explanation of symbols]

[0030] 10: Structural members 100: Base material 101: Surface 200: Protective film 201: Surface

Claims

1. A substrate; A protective film covering the surface of the base material; The protective film includes: A structural member, characterized in that a reduction treatment is applied to reduce in-plane variations in residual stress on the surface of the structural member.

2. 2. The structural member according to claim 1, wherein the surface of said protective film is polished prior to said reduction treatment.

3. 2. The structural member according to claim 1, wherein the protective film is a film formed by an aerosol deposition method.

4. Providing a substrate; forming a protective film on a surface of the substrate; and performing a reduction treatment to reduce in-plane variations in residual stress on the surface of the protective film.

5. 5. The method for manufacturing a structural member according to claim 4, wherein the reduction treatment is a treatment for heating the protective film to a predetermined temperature or higher.

6. 5. The method for manufacturing a structural member according to claim 4, wherein the reduction treatment is a treatment for chemically etching the surface of the protective film.

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