RF transmission member

Abstract

Provided is an RF transmission member that makes it possible to prevent breakage or the like of a protective film caused by residual stress. The RF transmission member 10 comprises a cylindrical body 100, and a protective film 200 that covers an inner surface 130 of the cylindrical body 100. A first opening 111 is formed at one end of the cylindrical body 100, and a second opening 121 that has a larger inner diameter than that of the first opening 111 is formed at the other end of the cylindrical body 100. In a cross section when cut along a plane that includes a central axis AX of the cylindrical body 100, the inner surface 130 of the cylindrical body 100 includes a first region D1 that protrudes inward in an arc shape and a second region D2 that is a portion closer to the second opening 121 than the first region D1 and protrudes outward in an arc shape. In the cross section, the curvature of the first region D1 is larger than the curvature of the second region D2, and the protective film 200 that covers the first region D1 is thinner than the protective film 200 that covers the second region D2.

Description

RF transmission member

[0001] The present invention relates to an RF transmission member.

[0002] For example, in a semiconductor manufacturing apparatus such as an etching apparatus, an RF transmission member is provided. The RF transmission member is a member that transmits high-frequency radio waves (RF) generated by an outer coil into an inner space to generate plasma in the space. As described in Patent Document 1 below, in recent years, an RF transmission member having a cylindrical shape has also been proposed and has already been put into practical use.

[0003] In such an RF transmission member, an opening formed at one end of the cylindrical body is used as a gas inlet, and an opening formed at the other end is used as a plasma outlet. The inner surface of the cylindrical body is covered with a protective film for protecting the cylindrical body from plasma. As the material of the cylindrical body, for example, alumina or the like is used. As the material of the protective film, for example, yttria or the like is used.

[0004] Japanese Patent Application Laid-Open No. 2023-2673

[0005] In the protective film, stress generated during film formation or the like often remains as residual stress. As the curvature of the inner surface of the cylindrical body increases, the residual stress of the protective film covering that portion tends to increase. Also, as the protective film becomes thicker, the residual stress of the protective film tends to increase. Therefore, depending on the shape of the inner surface of the cylindrical body and the thickness of the protective film, etc., the residual stress may become too large, and there is a possibility that the protective film may be damaged or peeled off.

[0006] The present invention has been made in view of such problems, and an object thereof is to provide an RF transmission member capable of preventing damage to the protective film caused by residual stress.

[0007] To solve the above problems, the RF-transmitting member according to the present invention comprises a cylindrical body and a protective film covering the inner surface of the cylindrical body. A first opening is formed at one end of the cylindrical body, and a second opening with a larger inner diameter than the first opening is formed at the other end of the cylindrical body. In a cross-section when the cylindrical body is cut by a plane including the central axis, the inner surface of the cylindrical body includes a first region that protrudes inward in an arc shape, and a second region that is on the second opening side of the first region and protrudes outward in an arc shape. In the above cross-section, the curvature of the first region is greater than the curvature of the second region, and the protective film covering the first region is thinner than the protective film covering the second region.

[0008] The first region of the inner surface of the cylindrical body has a large curvature in its cross-section, making it a region where large residual stresses tend to remain in the protective film. Therefore, by making the thickness of the protective film covering this first region thin, the residual stress in the protective film can be suppressed. As a result, damage to the protective film caused by residual stress can be prevented.

[0009] According to the present invention, it is possible to provide an RF-transmitting member that can prevent damage to the protective film caused by residual stress.

[0010] This is a schematic diagram showing the configuration of a semiconductor manufacturing apparatus. This is a diagram showing a cross-section of the RF-transmitting member according to this embodiment.

[0011] 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.

[0012] The RF-transmitting member 10 according to this embodiment is used in semiconductor manufacturing equipment such as a plasma etching apparatus. Before describing the RF-transmitting member 10, the configuration of the semiconductor manufacturing equipment will be described first.

[0013] 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 an RF-transmitting member 10.

[0014] 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. Among the components that make up the chamber CM, the upper component (top plate) in Figure 1 has an opening OP formed therein, and the shower plate SH and RF-transmitting member 10, which will be described later, are provided to cover the opening OP from above.

[0015] Pump PM is a device for reducing the pressure inside the chamber CM. By using Pump PM to expel the gas from inside the chamber CM, the pressure inside the chamber CM is reduced to a pressure suitable for plasma generation and etching.

[0016] The chuck unit EC is a device that supports the substrate W from below. For example, an electrostatic chuck that uses electrostatic force to attract and fix the substrate W is used as the chuck unit EC. The chuck unit EC is installed on a support base SB located inside the chamber CM.

[0017] The gas supply unit GS is a device that supplies the gas necessary for plasma generation. The gas from the gas supply unit GS is supplied into the RF permeable member 10, which will be described below, and becomes plasma which is then supplied into the chamber CM.

[0018] The RF permeable member 10 is a cylindrical member that connects the gas supply unit GS and the chamber CM. As shown in Figure 2, the RF permeable member 10 comprises a cylindrical body 100 and a protective film 200.

[0019] The cylindrical body 100 is a component that makes up the majority of the RF-transmitting member 10. The cylindrical body 100 is made of a material that can transmit high-frequency radio waves (RF) generated by the coil CL described later, such as a ceramic material such as alumina. The cross-section of the cylindrical body 100 shown in Figure 2 is the cross-section obtained when the cylindrical body 100 is cut by a plane containing its central axis AX. The shape of the cylindrical body 100 is obtained by rotating the cross-section shown in Figure 2 360 degrees around the central axis AX. Therefore, the cross-sectional shape when the cylindrical body 100 is cut perpendicular to the central axis AX is circular regardless of the height position of the cut surface.

[0020] A circular first opening 111 is formed at one end 110 of the cylindrical body 100, along the central axis AX (the upper side in Figure 2). A circular second opening 121 is formed at the other end 120 of the cylindrical body 100, along the central axis AX (the lower side in Figure 2). The inner diameter of the second opening 121 is larger than the inner diameter of the first opening 111.

[0021] As shown in Figure 1, end 110 is connected to the end of the supply piping extending from the gas supply unit GS. End 120 is connected to the chamber CM via a shower plate SH. The shower plate SH is a plate-shaped member made of metal, provided to cover the entire opening OP. The shower plate SH covers the entire second opening 121 from below and the entire opening OP from above. Multiple through holes HL are formed in the shower plate SH. The internal space of the cylindrical body 100 and the internal space of the chamber CM are in communication with each other via the through holes HL.

[0022] A coil CL is positioned on the outside of the cylindrical body 100. The coil CL is for generating high-frequency radio waves necessary for plasma generation. When an AC voltage is applied between the coil CL and the support base SB, the generated high-frequency radio waves pass through the cylindrical body 100 and enter its internal space. The gas supplied to the inside of the cylindrical body 100 from the gas supply unit GS is ionized by the high-frequency radio waves and becomes a plasma containing numerous particles such as radicals. The plasma enters the chamber CM through the through-hole HL of the shower plate SH and is used for processes such as etching on the substrate W. Some of the supplied gas may also become plasma after entering the chamber CM through the through-hole HL.

[0023] As shown in Figure 2, the cylindrical body 100 is a dome-shaped member such that its entire inner surface 130 is generally a concave curved surface. In the cross-section of Figure 2, the portion of the curve representing the shape of the inner surface 130 that is labeled "D1" and the surrounding area are regions that protrude inward in an arc shape. The region of the inner surface 130 that has the shape described above in the cross-section of Figure 2 will also be referred to as the "first region D1" below. In the above, "toward" means "towards the central axis AX".

[0024] In the cross-section of Figure 2, the portion of the curve representing the shape of the inner surface 130 labeled "D2" and the surrounding area are located below the first region D1 (i.e., towards the second opening 121) and are regions that protrude outward in an arc shape. The region of the inner surface 130 that has the shape described above in the cross-section of Figure 2 will also be referred to as the "second region D2" below. In the above, "outward" means "away from the central axis AX".

[0025] In the cross-section shown in Figure 2, the curvature of the curve representing the shape of the first region D1 is greater than the curvature of the curve representing the shape of the second region D2. In other words, the radius of curvature of the curve representing the shape of the first region D1 is smaller than the radius of curvature of the curve representing the shape of the second region D2.

[0026] The protective film 200 is a film formed to cover the entire inner surface 130 of the cylindrical body 100. The protective film 200 is provided as a film to protect the inner surface 130 of the cylindrical body 100 from plasma. The protective film 200 is formed of a material that has resistance to plasma, for example, a material mainly composed of yttria. The thickness of the protective film 200 is appropriately set according to the length of time for which resistance to plasma is required. In this embodiment, the thickness of the protective film 200 is approximately 10 μm. The protective film 200 can be formed, for example, using the aerosol deposition method. The protective film 200 may also be formed using physical vapor deposition (PVD) or chemical vapor deposition (CVD).

[0027] Incidentally, the protective film 200 often retains residual stress from the stress generated during its formation. In the cross-section shown in Figure 2, the greater the curvature of the inner surface 130, the greater the residual stress in the protective film 200 covering that portion tends to be. Also, the thicker the protective film 200, the greater the residual stress in the protective film 200 tends to be. Therefore, depending on the shape of the inner surface 130 and the thickness of the protective film 200, the residual stress may become too large, potentially causing damage or peeling of the protective film 200.

[0028] Therefore, in the RF-transmitting member 10 of this embodiment, damage to the protective film 200 caused by residual stress is prevented by devising the thickness distribution of the protective film 200 that covers each part of the inner surface 130.

[0029] As shown in the enlarged view labeled "B" in Figure 2, the thickness of the protective film 200 covering the second region D2 is T2. Also, as shown in the enlarged view labeled "A" in Figure 2, the thickness of the protective film 200 covering the first region D1 is T1, which is smaller than T2. ​​In other words, in this embodiment, the thickness distribution of the protective film 200 covering each part of the inner surface 130 is adjusted so that the protective film 200 covering the first region D1 is thinner than the protective film 200 covering the second region D2. The thickness adjustment can be done, for example, by varying the amount of polishing when polishing the surface after the formation of the protective film 200 is complete.

[0030] The first region D1 of the inner surface 130 is a part with a large curvature in the cross-section shown in Figure 2, and therefore is a part where large residual stresses tend to remain in the protective film 200. By making the thickness of the protective film 200 covering this first region D1 thin, the residual stress in the protective film 200 can be suppressed. As a result, damage to the protective film 200 caused by residual stress can be prevented.

[0031] It is preferable that the thickness (T1) of the protective film 200 covering the first region D1 be 20 μm or less. Experiments conducted by the inventors have confirmed that setting T1 in Figure 2 to such a thickness sufficiently reduces the residual stress of the protective film 200 in the first region D1.

[0032] When AC power is supplied to the coil CL, a phenomenon called sputtering is likely to occur in the portion of the protective film 200 near the coil CL, where a part of the protective film 200 is scraped off due to radical collisions. Therefore, if the protective film 200 is made too thin, there is a possibility that the protective film 200 will deteriorate in a relatively short period of time.

[0033] Therefore, it is preferable that the thickness (T2) of the portion of the protective film 200 that covers the second region D2 be 5 μm or more. Experiments conducted by the inventors have confirmed that if T2 in Figure 2 is set to such a thickness under the condition T1 < T2, the durability of the protective film 200 in the second region D2 can be sufficiently increased.

[0034] The thickness of the portion of the protective film 200 covering the first region D1 and the thickness of the portion covering the second region D2 may change discontinuously between them, or they may change smoothly.

[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.

[0036] 10: RF transmitting member 100: Cylindrical body 111: First opening 121: Second opening 130: Inner surface 200: Protective film D1: First region D2: Second region AX: Central axis

Claims

1. An RF-transmitting member comprising a cylindrical body and a protective film covering the inner surface of the cylindrical body, wherein a first opening is formed at one end of the cylindrical body, and a second opening having a larger inner diameter than the first opening is formed at the other end of the cylindrical body, and in a cross-section when the cylindrical body is cut by a plane including the central axis, the inner surface of the cylindrical body includes a first region projecting inward in an arc shape, and a second region that is on the second opening side of the first region and projecting outward in an arc shape, wherein the curvature of the first region is greater than the curvature of the second region, and the protective film covering the first region is thinner than the protective film covering the second region.

2. The RF-transmitting member according to claim 1, characterized in that the thickness of the protective film covering the first region is 20 μm or less.

3. The RF-transmitting member according to claim 1, characterized in that the thickness of the protective film covering the second region is 5 μm or more.

Images