Structural member

Abstract

To provide a structural member that can be used for a long period of time.SOLUTION: A structural member 10 includes a base material 100 and a protective film 200 that covers a surface 101 of the base material 100. At least a part near a surface 201 of the protective film 200 has a first layer 210 and a second layer 220, which includes all of the elements contained in the first layer 210 and differs from the first layer 210 in terms of the composition ratio of each element. These are arranged alternately along a depth direction perpendicular to the surface 201.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present 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 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.

[0003] When the protective film is exposed to plasma, the surface of the protective film is eroded by the plasma and gradually deteriorates. After a certain period of time has passed, the deteriorated part on the surface of the protective film can be removed by polishing or other methods to expose a new, undeteriorated surface, making it possible to continue using the structural component. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2007-321183 A Summary of the Invention [Problem to be solved by the invention]

[0005] The depth of the deteriorated portion of the protective film is not uniform across the surface, but varies from place to place. For this reason, when removing the surface layer of the protective film by polishing or the like, it is necessary to set the amount of removal according to the deepest deteriorated portion. In other areas, undeteriorated portions of the protective film will also be removed. In addition, because the protective film is removed to a deep position each time, it becomes thin in a relatively short period of time, making it necessary to replace the structural member with a new one.

[0006] 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 that can be used for a long period of time. [Means for solving the problem]

[0007] In order to solve the above problems, a structural member according to the present invention includes a substrate and a protective film covering a surface of the substrate. At least a portion of the protective film near the surface has a first layer and a second layer that contains all of the elements contained in the first layer and differs from the first layer in the composition ratio of the elements, and these are alternately arranged in a depth direction perpendicular to the surface of the protective film.

[0008] In such a structural member, at least the portion of the protective film near the surface has a multi-layer structure, with first and second layers arranged alternately. In such a configuration, deterioration of the protective film is more likely to progress in a direction parallel to the interface between the layers than in the depth direction. Since the progression of deterioration in the depth direction is slow, the frequency of removing the surface layer of the protective film can be reduced, and the structural member can be used for a long period of time.

[0009] Furthermore, as the rate of deterioration in the depth direction slows, the in-plane variation in the depth of the deteriorated portion decreases. Since it is no longer necessary to remove the protective film to a deep position each time, it becomes possible to use the structural member for a longer period of time. Effect of the Invention

[0010] According to the present invention, it is possible to provide a structural member that can be used for a long period of time. [Brief description of the drawings]

[0011] [Figure 1] FIG. 2 is a schematic cross-sectional view of a structural member according to the present embodiment. [Diagram 2] 2 is an enlarged view showing the configuration of part A in FIG. 1. [Diagram 3] 10A and 10B are diagrams for explaining deterioration 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

[0012] 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.

[0013] 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.

[0014] 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.

[0015] 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 it may be a different type of ceramic, or may be a member other than ceramic (for example, a metal member). 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.

[0016] 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 yttrium oxide. The protective film 200 is formed using a physical vapor deposition method (PVD). A specific formation method will be described later. The thickness of the protective film 200 is appropriately set depending on 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.

[0017] 2 is an enlarged cross-sectional view showing the configuration of part A in FIG. 1, that is, a portion of the protective film 200 near the surface 201. As shown in FIG. 2, the protective film 200 has a plurality of first layers 210 and second layers 220, which are arranged alternately along a direction perpendicular to the surface 201. The direction perpendicular to the surface 201 is also referred to as the "depth direction" below. Both the first layer 210 and the second layer 220 are layers containing yttrium oxide.

[0018] The first layer 210 is a layer containing Y2O3 as a main component. The first layer 210 may contain only Y2O3, but may also contain a component other than Y2O3 as an additive.

[0019] The second layer 220 is a layer containing YO as a main component. The second layer 220 may contain only YO, or may contain components other than YO as additives. Such a second layer 220 can be said to be a layer that contains all of the elements contained in the first layer 210 and differs from the first layer in the composition ratio of each element. In this embodiment, "the elements contained in the first layer 210" refers to "Y", "O", and, if an additive is present, its constituent elements.

[0020] The first layer 210 containing Y2O3 as a main component has a stoichiometric ratio of Y and O, making it a relatively stable layer, and therefore has low reactivity to plasma. In other words, it has high durability against plasma. On the other hand, the second layer 220 containing YO as a main component has a non-stoichiometric ratio of Y and O, making it a relatively unstable layer, and therefore has high reactivity to plasma compared to the first layer 210. In other words, it has low durability against plasma.

[0021] The boundary between the first layer 210 and the second layer 220 does not have to be clear as in Fig. 2. That is, the composition ratio of Y and O may change discontinuously (i.e., stepwise) according to the change in position in the depth direction, or may change continuously (i.e., smoothly). The first layer 210 and the second layer 220 may be alternately arranged throughout the entire protective film 200 along the depth direction, or may be alternately arranged only in the portion of the protective film 200 near the surface 201.

[0022] The effect of forming the protective film 200 into the multi-layer structure as described above will be described. Fig. 3(A) shows a cross section of the protective film 200 according to a comparative example. In this comparative example, the protective film 200 does not have a multi-layer structure as in the present embodiment, but is entirely composed of a single layer containing Y2O3 as a main component. In the figure, the region hatched differently and marked with the symbol "250" indicates a region that has been exposed to plasma and deteriorated. This region will be referred to below as the "deteriorated region 250".

[0023] In the comparative example, in the structural member having the conventional configuration, the depth of the deteriorated portion of the protective film 200 was not uniform within the surface. That is, the depth of the deteriorated region 250 greatly differed depending on the location in each part of the surface 201.

[0024] The deteriorated protective film 200 becomes a source of particle generation. Therefore, after deterioration of the protective film 200 has progressed to a certain extent, if the deteriorated region 250 on the surface layer of the protective film 200 is removed by polishing or the like to expose a new, undeteriorated surface, it becomes possible to continue using the structural member 10.

[0025] At this time, in order to leave no deteriorated region 250, it is necessary to polish down to the deepest position of the deteriorated region 250. For example, in the example of Fig. 3(A), it is necessary to remove the entire range indicated by "RM1" by polishing. Since the protective film 200 is removed to a deep position each time, the protective film 200 becomes thin in a relatively short period of time, and it becomes necessary to replace the structural member 10 with a new one.

[0026] RM1 also includes undegraded portions of the protective film 200. In other words, as a result of setting the removal amount according to the most deeply deteriorated portion, undegraded portions of the protective film 200 are also removed from other portions.

[0027] Therefore, in this embodiment, as described above, the protective film 200 has a multi-layer structure in which the first layer 210 and the second layer 220 are alternately stacked. In such a configuration, the deterioration of the protective film 200 is more likely to progress in a direction parallel to the interface between the layers than in the depth direction. In addition, as the deterioration progresses more slowly in the depth direction, the in-plane variation in the depth of the deteriorated portion becomes smaller.

[0028] Fig. 3(B) shows a cross section of the protective film 200 according to this embodiment in the same manner as Fig. 3(A). Note that in Fig. 3(B), the division into the first layer 210 and the second layer 220 is omitted. Fig. 3(B) also shows a deteriorated region 250 after exposure to plasma, as in Fig. 3(A).

[0029] In the protective film 200 according to this embodiment, degradation is likely to progress in a direction parallel to the surface 201. For this reason, as shown in FIG. 3B, the depth of the degradation region 250 caused by exposure to plasma is generally uniform at each portion along the surface 201. Furthermore, by suppressing the progression of degradation in the depth direction, the depth of the deepest portion of the degradation region 250 is shallower than that of the comparative example in FIG. 3A. In many cases, the lower end of the degradation region 250 is equal to the position of any one of the second layers 220.

[0030] In the example of Fig. 3(B), in order to continue using the structural member 10, it is necessary to remove the entire area indicated by "RM2" by polishing. Unlike the comparative example of Fig. 3(A), the removed RM2 contains almost no undegraded portion of the protective film 200.

[0031] In the protective film 200 of this embodiment, the progression of deterioration in the depth direction is slowed down as described above, so that the frequency of removing the surface layer of the protective film 200 can be reduced, enabling the structural member 10 to be used for a long period of time. In addition, since it is no longer necessary to remove the protective film 200 to a deep position every time, the structural member 10 can be used for an even longer period of time.

[0032] A method for manufacturing the structural member 10 will be described with reference to Fig. 4. First, a substrate 100 is prepared. It is preferable that the surface roughness and the like of a surface 101 of the substrate 100 is adjusted in advance to an extent that the protective film 200 can be stably formed.

[0033] 4(A), a metal layer 221 is formed so as to cover the surface 101 of the base material 100. The metal layer 221 is a layer containing yttrium (Y) as a main component. Such a metal layer 221 can be formed by, for example, a physical vapor deposition method using yttrium as a metal target, but may also be formed by other film formation methods.

[0034] Thereafter, oxygen plasma is generated near the metal layer 221, and the plasma is reacted with the metal layer 221. As a result, the surface side portion (the side opposite to the substrate 100) of the metal layer 221 is oxidized, and most of it becomes Y2O3. That is, the surface side portion of the metal layer 221 becomes the first layer 210 as shown in FIG. 4(B).

[0035] If the exposure to oxygen plasma is performed for a sufficient time, the entire metal layer 221 will become the first layer 210 (Y2O3). However, in this embodiment, the supply of oxygen is stopped or reduced before the entire metal layer 221 becomes the first layer 210 (Y2O3). Therefore, the portion of the metal layer 221 on the substrate 100 side is not sufficiently oxidized, and most of it becomes YO. In other words, the portion of the metal layer 221 on the substrate 100 side becomes the second layer 220 as shown in FIG. 4(B).

[0036] As described above, the portion that was the metal layer 221 in Fig. 4(A) becomes the first layer 210 and the second layer 220 through the oxidation step in Fig. 4(B). How the composition ratio of Y and O changes at the boundary between the two can be adjusted according to the amount of oxygen supplied, the plasma output, etc.

[0037] Subsequently, as shown in Fig. 4(C), a metal layer 221 is formed again so as to cover the surface of the first layer 210 that was the outermost layer. The method for forming this metal layer 221 is the same as the method for forming the metal layer 221 shown in Fig. 4(A). The supply of yttrium from the metal target to the base material 100 may be interrupted during the oxidation step shown in Fig. 4(B), but may also be continued.

[0038] Next, an oxidation step similar to that shown in Fig. 4(B) is performed again. The portion of the metal layer 221 on the front side (the side opposite to the substrate 100) shown in Fig. 4(C) is oxidized to become the first layer 210 as shown in Fig. 4(D). The portion of the metal layer 221 on the substrate 100 side is not sufficiently oxidized to become the second layer 220 as shown in Fig. 4(D).

[0039] Thereafter, similarly, a step of forming a metal layer 221 on the surface and a step of oxidizing the metal layer 221 to form the first layer 210 and the second layer 220 are repeatedly performed. As a result, a plurality of first layers 210 and second layers 220 are laminated, and the protective film 200 shown in FIG. 2 is formed.

[0040] The first layer 210 and the second layer 220 both contain yttrium oxide, but differ from each other in the composition ratio of yttrium to oxygen. Therefore, when forming the first layer 210 and the second layer 220 alternately, it is not necessary to switch targets or gas types midway, and it is sufficient to simply change the film formation conditions such as the supply amounts.

[0041] In this embodiment, the first layer 210 is exposed on the surface 201 of the protective film 200. By making the highly durable first layer 210 the surface of the protective film 200, the performance of the protective film 200 can be improved.

[0042] After the outermost first layer 210 deteriorates, the second layer 220 behind it deteriorates. Since the second layer 220 is a layer that deteriorates easily, the deterioration does not progress further into the depth until the entire second layer 220 deteriorates. As a result, localized deep deterioration is unlikely to occur.

[0043] Alternatively, the second layer 220 may be exposed on the surface 201 of the protective film 200 .

[0044] By intentionally leaving the less durable second layer 220 exposed to the surface, light elements such as Na and Ca attached to the surface 201 of the protective film 200 can be separated and removed together with the outermost second layer 220 during seasoning before the start of processing in the semiconductor manufacturing equipment. This makes it possible to start processing such as etching with the (new) surface of the protective film 200 in a clean state.

[0045] In order to expose the second layer 220 on the surface 201 of the protective film 200, the protective film 200 is formed by the method shown in FIG. 4, and then the first layer 210 at the outermost surface may be removed by polishing or the like.

[0046] 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]

[0047] 10: Structural members 100: Base material 101: Surface 200: Protective film 201: Surface 210: 1st layer 220: 2nd layer

Claims

1. A substrate; A protective film covering the surface of the base material; At least a portion of the protective film near the surface thereof is A first layer; a second layer that contains all of the elements contained in the first layer and differs from the first layer in the composition ratio of each element; and these are arranged alternately along a depth direction perpendicular to a surface of the protective film.

2. the first layer has higher plasma resistance than the second layer, 2. The structural member according to claim 1, wherein the first layer is exposed at a surface of the protective film.

3. the first layer has higher plasma resistance than the second layer, 2. The structural member according to claim 1, wherein the second layer is exposed at a surface of the protective film.

4. 4. The structural member according to claim 2, wherein the first layer and the second layer both contain yttrium oxide and are different from each other in the composition ratio of yttrium to oxygen.

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