Structure member

Abstract

To provide a structure member capable of easily removing light elements from a surface.SOLUTION: A structure member 10 comprises a base material 100, and a protective film 200 covering a surface 110 of the base material 100. The protective film 200 has a surface layer part 201 which is a portion including a surface 210 opposite to the base material 100, and a deep layer part 202 which is a portion nearer the base material 100 than the surface layer part 201. The surface layer part 201 has lower durability to plasma than the deep layer part 202.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 the following Patent Document 1, 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, fluoride ceramics such as yttrium fluoride, etc. 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] When a structural member is exposed to plasma for the first time after being attached to a semiconductor manufacturing device, etc., light elements such as sodium and calcium are often already attached to the surface of the protective film. Since light elements can be a source of contamination for silicon wafers, etc., it is preferable to remove them as much as possible before the structural member is attached to the semiconductor manufacturing device. However, it is difficult to completely remove the light elements by cleaning, etc., and the light elements may reattach to the protective film after cleaning.

[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 from whose surface light elements can be easily removed. [Means for solving the problem]

[0006] 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. The protective film has a surface layer portion that is a portion including a surface on the opposite side to the substrate, and a deep layer portion that is a portion closer to the substrate than the surface layer portion. The surface layer portion has lower durability against plasma than the deep layer portion.

[0007] In semiconductor manufacturing equipment, it is common to perform a preparatory operation called "seasoning" before processing semiconductor wafers, etc. During seasoning, the semiconductor manufacturing equipment is operated under conditions roughly similar to those during processing, so the surface of the protective film is exposed to plasma.

[0008] In the structural member having the above-mentioned configuration, the durability of the surface layer of the protective film is lower than that of the deeper layer, which is the innermost part of the surface layer. Therefore, during the above-mentioned seasoning, at least the surface portion of the surface layer is eroded by the plasma over almost the entire surface, and is separated from the protective film together with the light elements that were attached thereto.

[0009] In other words, light elements can be easily removed from the entire surface of the protective film simply by performing seasoning. The surface of the protective film becomes a clean, new surface, and silicon wafer processing begins in this state, preventing the light elements from the protective film from contaminating the silicon wafer. Effect of the Invention

[0010] According to the present invention, it is possible to provide a structural member from whose surface light elements can be easily removed. [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] FIG. 13 is a diagram showing the relationship between each position in the depth direction of a protective film and durability against plasma. [Diagram 3]FIG. 13 is a diagram showing the relationship between each position in the depth direction of a protective film and durability against plasma. [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 210 of the protective film 200 is exposed to the space inside a chamber. The protective film 200 is provided for the purpose of protecting a surface 110 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 110 of the substrate 100 is a flat surface, but the surface 110 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 110 of the substrate 100. In this embodiment, the protective film 200 is configured as a film containing polycrystalline yttria (Y2O3), but may be a ceramic film made of a different material. 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.

[0017] The protective film 200 of this embodiment is formed by using an aerosol deposition method on the surface 110 of the base material 100 after baking. As is well known, in the aerosol deposition method, microparticles, which are the material of the protective film 200, are dispersed in a gas to form an "aerosol," which is then sprayed from a nozzle toward the surface 110 and collided with it. On the surface 110, the microparticles are deformed and crushed by the impact of the collision, so that the microparticles bond to each other and gradually accumulate as the protective film 200.

[0018] 1, the portion surrounded by dotted line DL1 is a portion of protective film 200 that includes surface 210 on the outer side (i.e., the side opposite to substrate 100). This portion is also referred to below as "surface layer portion 201." In the same figure, the portion surrounded by dotted line DL2 is a portion of protective film 200 that is closer to substrate 100 than surface layer portion 201. This portion is also referred to below as "deep layer portion 202."

[0019] 1 shows only a part of the surface layer 201, not the whole. The surface layer 201 refers to the whole of the portion of the protective film 200 that is at the same height as the dotted line DL1 in FIG. 1. Similarly, the dotted line DL2 in FIG. 2 shows only a part of the deep layer 202, not the whole. The deep layer 202 refers to the whole of the portion of the protective film 200 that is at the same height as the dotted line DL2 in FIG. 1. The deep layer 202 may be any portion of the protective film 200 that is closer to the substrate 100 than the surface layer 201, and may be a portion at a different height from the dotted line DL2 in FIG. 1.

[0020] The protective film 200 of this embodiment is formed entirely of the same material, including the surface layer portion 201 and the deep layer portion 202. However, the durability against plasma is not uniform throughout, but is different between the surface layer portion 201 and the deep layer portion 202. Specifically, the durability of the surface layer portion 201 against plasma is lower than the durability of the deep layer portion 202 against plasma.

[0021] 2 shows an example of the relationship between the depth position (horizontal axis) of the protective film 200 and the durability of the protective film 200 against plasma (vertical axis). The "depth position" refers to a position (coordinate) along a direction perpendicular to the surface 210. The depth position on the surface 210 is set to "0", and the depth position of the protective film 200 at the boundary with the substrate 100 is set to "d2". "d1" in FIG. 2 is the depth position of the end of the surface layer 201 on the substrate 100 side.

[0022] 2 is an index that quantitatively indicates the resistance to erosion of the protective film 200 when exposed to plasma. The more easily the protective film 200 is eroded by plasma, the lower the "durability" of that portion. As such an index, for example, the reciprocal of the density of fluorine atoms detected from a specific portion of the protective film 200 after exposing that portion to fluorine-based plasma can be used.

[0023] 2, the durability of the protective film 200 against plasma is sufficiently large in the portion on the substrate 100 side (the right side in FIG. 2) and is a constant value that hardly changes with depth. On the other hand, in the surface layer portion 201 of the protective film 200, the durability gradually decreases toward the surface 210 side (the left side in FIG. 2), and is the lowest at the surface 210.

[0024] The above-described distribution of durability in the protective film 200 is merely an example. The relationship between the depth position of the protective film 200 and the durability against plasma may be as shown in the example of FIG. 3. In the example of FIG. 3, the durability of the protective film 200 changes stepwise depending on the depth position. In this example as well, the durability of the protective film 200 is lowest at the surface 210.

[0025] As described above, the surface layer portion 201 has lower durability against plasma than the deep layer portion 202. When comparing the plasma durability between the surface layer portion 201 and the deep layer portion 202, for example, the average value of the durability in each portion of the surface layer portion 201 and the average value of the durability in each portion of the deep layer portion 202 may be calculated, and the two values ​​may be compared.

[0026] The advantages of the above-mentioned configuration will be described. When the structural member 10 is exposed to plasma for the first time after being attached to a semiconductor manufacturing device (not shown), light elements such as sodium and calcium are often already attached to the surface 210 of the protective film 200. Since light elements can be a source of contamination for silicon wafers and the like, it is preferable to remove them as much as possible before the structural member 10 is attached to the semiconductor manufacturing device. However, it is difficult to completely remove the light elements by cleaning or the like, and the light elements may reattach to the protective film 200 after cleaning.

[0027] Incidentally, in semiconductor manufacturing equipment, it is common to perform a pre-operation called "seasoning" prior to processing semiconductor wafers, etc. During seasoning, the semiconductor manufacturing equipment is operated under substantially the same conditions as those during processing, so that the surface 210 of the protective film 200 is exposed to plasma.

[0028] Therefore, in this embodiment, as described above, the durability of the surface layer 201 of the protective film 200 is made lower than the durability of the deeper layer 202, which is the innermost part thereof. In such a configuration, during the above-mentioned seasoning, at least the surface 210 of the surface layer 201 is eroded by plasma over almost the entire surface, and is separated from the protective film 200 together with the attached light elements.

[0029] In other words, by simply performing seasoning, light elements can be easily removed from the entire surface of protective film 200. Surface 210 of protective film 200 becomes a clean new surface, and silicon wafer processing is started in this state, so that it is possible to prevent the light elements from protective film 200 from contaminating the silicon wafer.

[0030] In order to reduce the durability of the surface layer portion 201, in this embodiment, the protective film 200 is formed so that the porosity of the surface layer portion 201 is greater than the porosity of the deep layer portion 202. The durability decreases when the porosity of the surface layer portion 201 is increased because the surface layer portion 201 is exposed to more plasma as the effective surface area increases. Note that the "porosity" here refers to the ratio of the area of ​​voids to the unit area in a cross section of the protective film 200 perpendicular to the surface 210.

[0031] The durability of the surface layer portion 201 against plasma may be adjusted by a parameter other than the porosity. For example, the protective film 200 may be formed so that the indentation hardness of the surface layer portion 201 is lower than the indentation hardness of the deep layer portion 202.

[0032] In addition, the protective film 200 may be formed so that the average crystallite size in the surface layer portion 201 is larger than the average crystallite size in the deep layer portion 202. The "average crystallite size" refers to the average value of the diameters of a plurality of crystallites that appear in a cross section when the protective film 200 is cut.

[0033] The average crystallite size is, for example, a value calculated by taking a transmission electron microscope (TEM) image at a magnification of 400,000 times or more and averaging the diameters of 15 crystallites in this image by circular approximation. At this time, by making the sample thickness during focused ion beam (FIB) processing sufficiently thin to about 30 nm, the crystallites can be more clearly identified. The magnification of the image is preferably selected appropriately within the range of 400,000 times or more.

[0034] The arithmetic surface roughness of the surface layer portion 201 (i.e., Ra of the surface 210) is preferably set to 0.05 μm or more. By roughening the surface layer portion 201 to this extent, light elements are more likely to be released from the protective film 200 together with the surface layer portion 201 during seasoning.

[0035] A method for manufacturing the structural member 10 will be described with reference to Fig. 4. As shown in Fig. 4(A), first, a substrate 100 is prepared. It is preferable that the surface roughness, etc. of a surface 110 of the substrate 100 is adjusted in advance to such an extent that a protective film 200 can be stably formed.

[0036] 4(B), a protective film 200 is formed so as to cover the surface 110 of the substrate 100. The protective film 200 of this embodiment is formed by using the aerosol deposition method as described above.

[0037] In order to make the porosity of the protective film 200 different depending on the depth position, the film formation conditions are not always the same during the formation of the protective film 200, but are changed during the film formation. For example, the injection concentration of the microparticles, which are the material of the protective film 200, may be increased after the timing when the formation of the deep layer portion 202 is completed and the formation of the surface layer portion 201 begins. In addition, after the above timing, the pressure around the injection nozzle (pressure in the film formation chamber) may be increased, or the incidence angle of the microparticles with respect to the film formation surface may be increased. In addition, the type of microparticles may be changed after the above timing. For example, after the microparticles obtained from granulated powder with low moisture content are injected in the first half, the microparticles obtained from granulated powder with high moisture content may be injected in the second half.

[0038] Even when the protective film 200 is formed by a method other than the aerosol deposition method, the porosity can be adjusted according to the depth position by changing the film formation conditions in the middle in the same manner as described above. The same applies when adjusting the average crystallite size, etc. instead of the porosity.

[0039] 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]

[0040] 10: Structural members 100: Base material 110: Surface 200: Protective film 201: Surface layer 202:Deep 210: Surface

Claims

1. A substrate; A protective film covering the surface of the base material; The protective film is A surface layer portion including a surface opposite to the substrate; A deep layer portion which is a portion closer to the substrate than the surface layer portion, A structural member, characterized in that the surface layer has lower durability against plasma than the deep layer.

2. 2. The structural member according to claim 1, wherein the porosity of the surface layer is greater than the porosity of the deep layer.

3. 2. The structural member according to claim 1, wherein the indentation hardness of the surface layer is lower than the indentation hardness of the deep layer.

4. 2. The structural member according to claim 1, wherein the average crystallite size in the surface layer is larger than the average crystallite size in the deep layer.

5. 2. The structural member according to claim 1, wherein the surface portion has an arithmetic surface roughness of 0.05 [mu]m or more.

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

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