Structural members

Abstract

The present invention provides a structural member that can shorten the time required for the formation of the pre-coat layer while improving the adhesion between the pre-coat layer and the protective film. [Solution] The structural member 10 comprises a base material 100 and a protective film 200 covering the surface 101 of the base material 100. The protective film 200 mainly contains yttria in which the amount of oxygen atoms is less than the amount in the stoichiometric ratio, and the arithmetic mean roughness of the surface of the protective film 200 is 0.65 μm or less.

Description

Technical Field

[0001] The present invention relates to a structural member.

Background Art

[0002] A structural member having a protective film on the surface of a base material is used in various fields such as semiconductor manufacturing apparatuses. For example, as described in Patent Document 1 below, in a semiconductor manufacturing apparatus, a protective film for protecting the base material from plasma is formed on the surface of the base material constituting the inner wall of a chamber. As such a protective film, for example, oxide ceramics such as yttria are used.

[0003] When processes such as etching are repeated in a semiconductor manufacturing apparatus, foreign matter generated by the reaction of plasma accumulates on the surface of the protective film covering the inner wall of the chamber. Such foreign matter needs to be removed periodically from the surface of the protective film. In order to facilitate the removal of the foreign matter, in a semiconductor manufacturing apparatus, a precoat process is often performed prior to a process such as etching. The precoat process is a process of previously forming a precoat layer containing Si on the surface of the protective film.

[0004] The foreign matter generated in a process such as etching accumulates on the surface of the precoat layer. After the process is completed, the precoat layer is removed by an ashing process. At this time, the foreign matter deposited on the surface of the precoat layer is also removed together. Since the foreign matter can be removed without substantially damaging the surface of the protective film, the function of the protective film can be maintained for a long period of time.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] To improve adhesion between the pre-coat layer and the protective film, it is preferable to roughen the surface of the protective film beforehand. However, in order to completely cover the rough surface of the protective film with the pre-coat layer, the pre-coat layer needs to be formed thickly. As a result, the time required to form the pre-coat layer becomes longer.

[0007] This invention has been made in view of these problems, and its objective is to provide a structural member that can improve the adhesion between the pre-coat layer and the protective film while shortening the time required to form the pre-coat layer. [Means for solving the problem]

[0008] 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 contains yttria in which the amount of oxygen atoms is less than the amount in the stoichiometric ratio, and its surface has an arithmetic mean roughness of 0.65 μm or less.

[0009] By making the surface of the protective film relatively smooth, with an arithmetic mean roughness of 0.65 μm or less, it becomes unnecessary to form a thick pre-coat layer. This reduces the time required to form the pre-coat layer.

[0010] Furthermore, since the yttria constituting the protective film has a lower amount of oxygen atoms compared to the stoichiometric ratio, its reactivity on the surface of the protective film is increased. Therefore, the surface of the protective film can be made smooth as described above, and while shortening the time required for the formation of the pre-coat layer, sufficient adhesion between the pre-coat layer and the protective film can be ensured. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a structural member that can improve the adhesion between the pre-coat layer and the protective film while shortening the time required to form the pre-coat layer. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic diagram showing the configuration of semiconductor manufacturing equipment. [Figure 2] This figure schematically shows a cross-section of the structural member according to this embodiment. [Figure 3] This is a diagram illustrating the pre-coat layer. [Figure 4] This diagram schematically shows a cross-section of a structural member relating to a comparative example. [Modes for carrying out the invention]

[0013] This embodiment will now be described with reference to the attached drawings. To facilitate understanding of the explanation, the same reference numerals are used for identical components in each drawing whenever possible, and redundant explanations are omitted.

[0014] The structural member 10 according to this embodiment is used as a component of a semiconductor manufacturing apparatus, such as a plasma etching apparatus. Before describing the structural member 10, the configuration of the semiconductor manufacturing apparatus will be described first.

[0015] Figure 1 schematically shows the configuration of an etching apparatus EQ, which is an example of semiconductor manufacturing equipment. The etching apparatus EQ is a device for selectively removing a portion of a film that has been pre-formed on the surface of a substrate W to be processed, using plasma. The etching apparatus EQ comprises a chamber CM, a pump PM, a chuck section EC, a gas supply section GS, and a coil CL.

[0016] The chamber CM is a container that houses the chuck portion EC and the like inside. The etching process on the substrate W is performed inside the chamber CM. The structural member 10 according to this embodiment is used, for example, as a member that constitutes the inner wall of the chamber CM.

[0017] The pump PM is a device for reducing the pressure inside the chamber CM. By discharging the gas inside the chamber CM with the pump PM, the pressure inside the chamber CM is reduced to a pressure suitable for plasma generation and etching processes.

[0018] The chuck unit EC is a device for supporting the substrate W from below. As the chuck unit EC, for example, an electrostatic chuck that adsorbs and fixes the substrate W by electrostatic force is used. The chuck unit EC is provided on the support base SB inside the chamber CM.

[0019] The gas supply unit GS is a device for supplying the gas necessary for plasma generation into the chamber CM. The gas from the gas supply unit GS is supplied into the chamber CM through the top plate WD located at the uppermost side of the chamber CM.

[0020] The coil CL is for generating high-frequency radio waves (RF) between it and the support base SB, and is arranged above the top plate WD (that is, outside the chamber CM). The high-frequency radio waves generated by the coil CL penetrate the top plate WD and enter the chamber CM. The gas supplied from the gas supply unit GS is ionized by the high-frequency radio waves to become plasma, which is used for the etching process on the surface of the substrate W.

[0021] The structural member 10 according to this embodiment will be described. As described above, the structural member 10 is used as a member constituting the inner wall of the chamber CM or the like. The structural member 10 includes a base material 100 and a protective film 200. In the etching apparatus EQ, the surface 201 of the protective film 200 is exposed toward the space inside the chamber CM. The protective film 200 is provided for the purpose of protecting the surface 101 of the base material 100 from plasma.

[0022] 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. Also, the surface 101 of the base material 100 is a flat surface in this embodiment, but the surface 101 may have irregularities, inclinations, etc.

[0023] As described above, the protective film 200 is a film formed to protect the surface 101 of the base material 100 from plasma. The protective film 200 is formed so as to cover the entire surface 101 of the base material 100. The thickness of the protective film 200 is appropriately set according to the length of the period for which durability is required, etc. In this embodiment, the thickness of the protective film 200 is 10 μm.

[0024] The protective film 200 mainly contains polycrystalline yttria (yttrium oxide). However, in this yttria, the amount of oxygen atoms is less than the amount in the stoichiometric ratio. That is, when the chemical composition of yttria is expressed as "Y2O n ", the protective film 200 mainly contains yttria such that the value of n is less than 3.

[0025] Such a protective film 200 can be obtained, for example, by first forming a stoichiometric yttria (Y2O3) film and then heating and reducing the film in a reduced-pressure environment. The stoichiometric yttria film can be formed using, for example, physical vapor deposition (PVD), chemical vapor deposition (CVD), aerosol deposition method, etc.

[0026] In an etching apparatus EQ, when etching and other processes are repeated, foreign matter generated by the plasma reaction accumulates on the surface 201 of the protective film 200 that covers the inner wall of the chamber CM (i.e., the substrate 100). Such foreign matter needs to be periodically removed from the surface 201 of the protective film 200. To facilitate the removal of foreign matter, semiconductor manufacturing equipment such as etching apparatus EQ often performs a pre-coating process prior to etching and other processes. "Pre-coating process" is a process in which a pre-coating layer 300 containing Si is formed in advance on the surface 201 of the protective film 200.

[0027] Figure 3(A) shows the structural member 10 after pre-coating. The entire surface 201 of the protective film 200 is covered with the pre-coat layer 300. The pre-coat layer 300 can be formed, for example, by generating plasma while supplying a gas containing Si into the chamber CM, without placing the substrate W inside the chamber CM.

[0028] Subsequently, while the surface 201 of the protective film 200 is covered with the pre-coat layer 300, etching and other processes are performed on the substrate W. As shown in Figure 3(B), foreign matter DP generated during the process accumulates on the surface of the pre-coat layer 300.

[0029] After the processing is complete, the pre-coat layer 300 is removed, for example, by ashing using fluorine plasma. At this time, the foreign matter DP that had accumulated on the surface of the pre-coat layer 300 is also removed, resulting in the state shown in Figure 3(C). Since the foreign matter DP can be removed with almost no physical damage to the surface 201 of the protective film 200, the function of the protective film 200 can be maintained for a long period of time.

[0030] Incidentally, in order to improve the adhesion between the pre-coat layer 300 and the protective film 200, it is preferable to roughen the surface 201 of the protective film 200 beforehand prior to the pre-coat treatment. However, as shown in the comparative example in Figure 4, in order to cover the entire surface 201 of the protective film 200 with the pre-coat layer 300 so that the surface 201 is not exposed, it is necessary to form a thick pre-coat layer 300. As a result, the problem arises that the time required to form the pre-coat layer 300 becomes longer.

[0031] Therefore, in this embodiment, the surface 201 of the protective film 200 is made relatively smooth, with an arithmetic mean roughness (Ra) of 0.65 μm or less. Such surface roughness can be achieved, for example, by performing a grinding or other treatment on the surface 201 after the formation of the protective film 200 is complete. By making the surface 201 a smooth surface as described above, it becomes unnecessary to form a thick pre-coat layer 300. This makes it possible to shorten the time required to form the pre-coat layer 300.

[0032] Furthermore, as mentioned earlier, the yttria constituting the protective film 200 in this embodiment has a smaller amount of oxygen atoms compared to the stoichiometric ratio. As a result, the reactivity on the surface 201 of the protective film 200 is increased, and the adhesion strength between it and the pre-coat layer 300 is enhanced. Consequently, in this embodiment, the surface 201 of the protective film 200 is made smooth as described above, and while shortening the time required to form the pre-coat layer 300, it is possible to ensure sufficient adhesion between the pre-coat layer 300 and the protective film 200.

[0033] In conventional configurations, in order to ensure adhesion between the pre-coat layer 300 and the protective film 200, it was necessary to make the surface 201 rough, which required the pre-coat layer 300 to be 10 μm or thicker. In contrast, by adopting the configuration of this embodiment, the thickness of the pre-coat layer 300 can be reduced to less than 3 μm.

[0034] As described above, the arithmetic mean roughness of the surface 201 of the protective film 200 is preferably 0.65 μm or less, but by setting it to 0.4 μm or less, the time required to form the pre-coat layer 300 can be further shortened. However, in order to ensure minimum adhesion between the pre-coat layer 300 and the protective film 200, it is preferable to set the arithmetic mean roughness of the surface 201 to 0.01 μm or more.

[0035] 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]

[0036] 10: Structural members 100: Base material 101: Surface 200: Protective film 201: Surface

Claims

1. Substrate and The substrate comprises a protective film covering the surface of the substrate, The protective film contains yttria as its main component, in which the amount of oxygen atoms is less than the amount in the stoichiometric ratio. A structural member characterized in that the arithmetic mean roughness of the surface of the protective film is 0.65 μm or less.

2. The structural member according to claim 1, characterized in that the arithmetic mean roughness of the surface of the protective film is 0.01 μm or more.

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