Fastening structure, plasma processing apparatus and fastening method

Abstract

To prevent fastening a screw from being loosened in a fastening structure in which members constituting a substrate processing device are mutually fastened via the fastening screw.SOLUTION: In a fastening structure for fastening a first member and a second member constituting a substrate processing device. The first member includes a female screw portion. The second member includes: a through hole corresponding to the female screw portion; a counterbore portion that is continuous with the through hole and has a diameter larger than that of the through hole; a fastening screw having a male screw portion inserted into the through hole and screwed into the female screw portion, and a screw head continuous with the end portion of the male screw portion; and a flat washer that is fitted to the counterbore portion and into which the male screw portion is inserted. At least one or both of a first surface of the screw head portion facing the flat washer and a second surface of the flat washer facing the screw head portion are covered with a lubricating material.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to a fastening structure, a plasma processing apparatus, and a fastening method. [Background technology]

[0002] Patent Document 1 discloses a plasma processing apparatus that performs plasma processing on a glass substrate in a processing space evacuated by using a processing gas that has been converted into plasma. The plasma processing apparatus includes a mounting table on which a glass substrate is mounted, an electrically grounded metal processing vessel that has an opening on the upper surface facing the mounting table, a metal window that is made of a plurality of conductive partial windows arranged to close the opening of the processing vessel and form a processing space, and a plasma antenna that is provided above the metal window and faces the metal window, for converting the processing gas into plasma by inductive coupling. In the plasma processing apparatus of Patent Document 1, each partial window of the metal window also serves as a shower head for supplying the processing gas. Each partial window is configured by stacking, from the bottom, a shower plate having a number of processing gas discharge holes formed therein for supplying the processing gas to the processing space, and a metal window body for forming a processing gas diffusion chamber for diffusing the processing gas between the shower plate. Furthermore, in the plasma processing apparatus of Patent Document 1, the shower plate is fastened to the metal window body by a screw, and a temperature control flow path for passing a temperature control fluid for temperature control is formed in the metal window body. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-27775 A Summary of the Invention [Problem to be solved by the invention]

[0004] The technology according to the present disclosure prevents loosening of fastening screws in a fastening structure in which components constituting a substrate processing apparatus are fastened together by fastening screws. [Means for solving the problem]

[0005] One aspect of the present disclosure is a fastening structure for fastening a first member and a second member constituting a substrate processing apparatus, the first member having a female threaded portion, the second member having a through hole corresponding to the female threaded portion and a countersunk portion continuous with the through hole and having a diameter larger than that of the through hole, a fastening screw having a male threaded portion inserted into the through hole and screwed into the female threaded portion, and a screw head continuous with an end of the male threaded portion, and a flat washer fitted into the countersunk portion and through which the male threaded portion is inserted, at least one or both of a first surface of the screw head facing the flat washer and a second surface of the flat washer facing the screw head are coated with a lubricating material. The relative positions of the female screw portion, the through hole, and the countersunk portion are different when the substrate is processed by the substrate processing apparatus and when the substrate is not processed. . Effect of the Invention

[0006] According to the present disclosure, in a fastening structure in which components constituting a substrate processing apparatus are fastened together with fastening screws, it is possible to prevent the fastening screws from becoming loose. [Brief description of the drawings]

[0007] [Figure 1] 1 is a vertical cross-sectional view showing an outline of a configuration of a plasma processing apparatus according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a bottom view of a metal window described below. [Diagram 3] FIG. 2 is a partially enlarged view of FIG. [Figure 4] 2 is a vertical cross-sectional view showing an outline of the configuration of a fastening structure provided in the plasma processing apparatus of FIG. 1, and corresponds to a partially enlarged view of FIG. 3 inverted form. [Diagram 5] FIG. 11 is a vertical cross-sectional view showing another example of the fastening structure. [Figure 6] FIG. 11 is a vertical cross-sectional view showing another example of the fastening structure. [Figure 7]FIG. 11 is a vertical cross-sectional view showing another example of the fastening structure. [Figure 8] FIG. 13 is a diagram showing the results of a confirmation test. [Figure 9] FIG. 13 is a diagram showing the results of a confirmation test. [Figure 10] FIG. 13 is a diagram showing the results of a confirmation test. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] In the manufacturing process of flat panel displays (FPDs) such as liquid crystal displays (LCDs), substrate processing such as etching and film formation is performed on substrates such as glass substrates. For these substrate processing operations, a substrate processing apparatus having a processing vessel in which the substrate to be processed is accommodated is used. Further, as the substrate processing apparatus, there is a plasma processing apparatus which performs substrate processing using plasma of a processing gas, and as the plasma processing apparatus, there is one which uses inductively coupled plasma (see Patent Document 1).

[0009] The plasma processing apparatus using inductively coupled plasma of Patent Document 1 includes, as described above, a mounting table on which a glass substrate is mounted, and a metallic processing vessel that is open on the upper surface facing the mounting table and is electrically grounded. The plasma processing apparatus of Patent Document 1 also includes a metal window made of a plurality of conductive partial windows arranged to close the opening of the processing vessel to form a processing space, and a plasma antenna that is provided above the metal window to face the metal window and converts a processing gas into plasma by inductive coupling. In the plasma processing apparatus of Patent Document 1, each partial window of the metal window also serves as a shower head for supplying a processing gas. Each partial window is configured by stacking, from the bottom, a shower plate having a number of processing gas discharge holes formed therein for supplying a processing gas to the processing space, and a metal window body for forming a processing gas diffusion chamber for diffusing the processing gas between the shower plate. Furthermore, in the plasma processing apparatus of Patent Document 1, the shower plate is fastened to the metal window body by a screw, and a temperature control flow path for passing a temperature control fluid for temperature control is formed in the metal window body.

[0010] Incidentally, in a plasma processing apparatus, when screws are used to fasten the shower plate and the metal window body as in Patent Document 1, the screws may become loose due to substrate processing or repeated substrate processing. The reason for the loosening of the screws is thought to be the difference in thermal expansion between the shower plate and the metal window body. Specifically, the shower plate receives heat from the plasma of the processing gas, and although the temperature is regulated, the temperature regulation is via the metal window body, so it becomes hot and expands, whereas the temperature of the metal window body remains almost unchanged and does not expand, since the temperature is regulated directly by the temperature control flow path. Therefore, the shower plate slides along the metal window body, and at that time, a force acts on the screws, which is thought to result in the screws loosening.

[0011] If the screws fastening the shower plate and metal window body become loose, problems may occur, such as corrosion caused by processing gas reaching unnecessary parts, generation of particles due to corrosion, and poor electrical conductivity and heat transfer between the shower plate and metal window body.

[0012] In substrate processing apparatuses other than plasma processing apparatuses, if screws fastening components constituting the substrate processing apparatus together become loose, this can adversely affect substrate processing and the like.

[0013] In view of this, the technology disclosed herein prevents the occurrence of loosening of fastening screws in a fastening structure in which components constituting a substrate processing apparatus are fastened together by fastening screws.

[0014] Hereinafter, a fastening structure, a plasma processing apparatus, and a fastening method according to the present embodiment will be described with reference to the drawings. In this specification and the drawings, elements having substantially the same functional configurations are denoted by the same reference numerals, and duplicated descriptions will be omitted.

[0015] <Plasma processing device 1> Fig. 1 is a vertical cross-sectional view showing an outline of the configuration of a plasma processing apparatus according to this embodiment, Fig. 2 is a bottom view of a metal window described later, and Fig. 3 is a partially enlarged view of Fig. 1. 1 performs substrate processing, i.e., plasma processing, using plasma of a processing gas on a rectangular glass substrate G (hereinafter referred to as "substrate G") as a substrate. The plasma processing performed by the plasma processing apparatus 1 includes, for example, film formation processing for FPDs, etching processing, ashing processing, etc. Through these processing, electronic devices such as light-emitting elements and driving circuits for the light-emitting elements are formed on the substrate G.

[0016] The plasma processing apparatus 1 includes a rectangular cylindrical container body 10. The container body 10 is made of a conductive material, for example, aluminum, and is electrically grounded. Since a corrosive gas is often used in the plasma processing, the inner wall surface of the container body 10 is subjected to a corrosion-resistant coating treatment such as anodizing treatment in order to improve corrosion resistance. An opening is formed on the upper surface of the container body 10. This opening is airtightly closed by a rectangular metal window 20 provided insulated from the container body 10, specifically, airtightly closed by the metal window 20 and a metal frame 14 described later. The space surrounded by the container body 10 and the metal window 20 becomes a processing space S1 in which a substrate G to be processed in the plasma processing is located during plasma processing, and the space above the metal window 20 becomes an antenna chamber S2 in which a high-frequency antenna (plasma antenna) 80 described later is disposed. A loading / unloading port 11 for loading / unloading the substrate G into / from the processing space S1 and a gate valve 12 for opening / closing the loading / unloading port 11 are provided on the side wall of the container body 10.

[0017] A substrate support 30 for supporting a substrate G is provided at the lower side of the processing space S1 so as to face the metal window 20. The substrate support 30 has a main body 31 on which the substrate G is placed, and the main body 31 is installed on the bottom surface of the container body 10 via legs 32.

[0018] The main body 31 is made of a conductive material, such as aluminum. The surface of the main body 31 is subjected to a coating process, such as anodizing or ceramic spraying, in order to improve insulation and corrosion resistance. The main body 31 is also provided with an electrostatic chuck (not shown) that attracts and holds the substrate G.

[0019] Furthermore, a high frequency power supply 41 is connected to the main body 31 via a matching box 40. The high frequency power supply 41 supplies high frequency power for bias, for example, high frequency power having a frequency of 3.2 MHz, to the main body 31. This allows ions in the plasma generated in the processing space S1 to be attracted to the substrate G.

[0020] In addition, a cooling mechanism having a refrigerant flow path (not shown) through which a cooling refrigerant for cooling the substrate G flows is provided in the main body 31 as a temperature adjustment mechanism for adjusting the temperature of the substrate G. As the temperature adjustment mechanism, a heating mechanism (e.g., a resistance heater) for heating may be provided instead of the cooling mechanism, or both the cooling mechanism and the heating mechanism may be provided. In addition, a temperature sensor (not shown) and a gas flow path (not shown) for supplying a heat transfer gas such as He gas to the back surface of the substrate G are provided in the main body 31.

[0021] An exhaust port 13 is formed on the bottom surface of the container body 10, and an exhaust unit 50 having a vacuum pump or the like is connected to this exhaust port 13. The processing space S1 is depressurized by this exhaust unit 50. The exhaust unit 50 may be provided for each of the multiple exhaust ports 13, or may be provided commonly to the multiple exhaust ports 13.

[0022] A metal frame 14, which is a rectangular frame made of a metal material such as aluminum, is provided on the upper surface side of the side wall of the container body 10. A seal member 15 for keeping the processing space S1 airtight is provided between the container body 10 and the metal frame 14. The container body 10, the metal frame 14, and the metal window 20 together form a processing container for accommodating a substrate G to be processed.

[0023] As shown in FIGS. 1 and 2, the metal window 20 is divided into a plurality of partial windows 21, which are arranged inside the metal frame 14 to form the metal window 20 having a rectangular shape as a whole.

[0024] Each of the partial windows 21 functions as a shower head for supplying a processing gas to the processing space S1. For example, as shown in Fig. 3, each partial window 21 is configured by stacking a metal window body (base member) 23 as a first member and a shower plate 22 as a second member in this order from below. The shower plate 22 is formed with a large number of gas discharge holes 22a for supplying a processing gas to the processing space S1. The metal window body 23 forms a diffusion chamber 23a between itself and the shower plate 22 for diffusing the processing gas.

[0025] The shower plate 22 is fastened to the metal window body 23 by fastening screws 24. In other words, the plasma processing apparatus 1 includes a fastening structure that fastens the shower plate 22 and the metal window body 23 by the fastening screws 24. The fastening structure will be described in detail later. Specifically, the shower plate 22 is fastened to the underside of the metal window body 23 in an area outside the recess that constitutes the diffusion chamber 23a by fastening screws 24. More specifically, the shower plate 22 is fastened to the underside of the metal window body 23 in an area between an O-ring 25 and a spiral ring 26, which will be described later, by fastening screws 24.

[0026] In addition, an O-ring 25 for sealing the diffusion chamber 23a is provided between the peripheral portion of the shower plate 22 and the peripheral portion of the metal window body 23, and a spiral ring 26 for electrically connecting the shower plate 22 and the metal window body 23 is provided on the outside of the O-ring 25.

[0027] The partial window 21 having these configurations is held on the ceiling surface side of the processing space S1 via a holding portion (not shown).

[0028] 1, the diffusion chamber 23a of each partial window 21 is connected to a process gas supply unit 61 via a gas supply pipe 60. The process gas supply unit 61 includes a flow rate control valve (not shown) and an on-off valve (not shown), and supplies process gases required for film formation, etching, ashing, and other processes to the diffusion chamber 23a. For convenience of illustration, FIG. 1 shows a state in which the process gas supply unit 61 is connected to one partial window 21, but in reality, the process gas supply unit 61 is connected to the diffusion chamber 23a of each partial window 21.

[0029] 1 and 3, a temperature control flow path 23b for passing a temperature control fluid for temperature control is formed in the metal window body 23 of each partial window 21. The temperature control flow path 23b is connected to a temperature control fluid supply unit (not shown). The temperature control fluid supply unit includes an opening / closing valve, a pump, and the like, and supplies the temperature control fluid to the temperature control flow path 23b. The temperature control fluid controls the temperature of the shower plate 22 through the metal window body 23. Specifically, the temperature control fluid is supplied from the temperature control fluid supply unit based on the temperature detection result of a temperature sensor (not shown) provided in the metal window body 23, so that the shower plate 22 has a preset temperature. It is also possible to change the set temperature of the temperature control fluid supply unit according to the processing result of the substrate G without using a temperature sensor.

[0030] Each shower plate 22 and each metal window body 23 are made of a non-magnetic conductive material, for example, aluminum. In addition, the lower surface of the shower plate 22, which is the surface on the processing space S1 side, the surfaces of the shower plate 22 and the metal window body 23 forming the diffusion chamber 23a, and the inner peripheral surface of the gas discharge hole 22a of the shower plate 22 are subjected to a corrosion-resistant coating such as anodizing treatment in order to improve corrosion resistance when a corrosive gas is used as the processing gas. Furthermore, the lower surface of the shower plate 22 is subjected to a plasma-resistant coating such as a treatment of coating with ceramic such as yttrium oxide in order to improve plasma resistance. Note that the area outside the O-ring 25 on the upper surface of the peripheral part of the shower plate 22 and the lower surface of the peripheral part of the metal window body 23 is not subjected to a corrosion-resistant coating. This is to electrically connect the shower plate 22 and the metal window body 23 and to adjust the temperature of the shower plate 22 via the metal window body 23.

[0031] Furthermore, the partial window 21 is electrically insulated from the metal frame 14 by an insulating member 27 , and adjacent partial windows 21 are also electrically insulated from each other by the insulating member 27 . The insulating member 27 is provided with an insulating member cover 28 that covers the surface of the insulating member 27 facing the processing space S1 in order to protect the insulating member 27. As shown in FIG. 2, the insulating member cover 28 is divided into, for example, a plurality of partial covers 28a.

[0032] 3, the insulating member cover 28 covers the processing space S1 side of the fastening screw 24 to prevent the fastening screw 24 from being exposed to the processing space S1. Specifically, the insulating member cover 28 closes the countersunk portion into which the screw head of the fastening screw 24 fits.

[0033] 1, a top plate portion 70 is disposed above the metal window 20. The top plate portion 70 is supported by a side wall portion 71 provided on the metal frame 14.

[0034] The space surrounded by the metal window 20, the side wall portion 71 and the top plate portion 70 constitutes an antenna chamber S2, and a high-frequency antenna 80 is disposed inside the antenna chamber S2 so as to face the partial window 21.

[0035] The high-frequency antenna 80 is disposed at a distance from the partial window 21 via a spacer (not shown) made of, for example, an insulating material. The high-frequency antenna 80 is formed concentrically, for example in a spiral shape, along the surface corresponding to each partial window 21 so as to go around the circumferential direction of the rectangular metal window 20, constituting a polycyclic antenna.

[0036] A high frequency power supply 43 is connected to each high frequency antenna 80 via a matching box 42. High frequency power of, for example, 13.56 MHz is supplied to each high frequency antenna 80 from the high frequency power supply 43 via the matching box 42. As a result, during plasma processing, eddy currents are induced on the surface of each partial window 21, and an induced electric field is formed inside the processing space S1 by the eddy currents. The processing gas discharged from the gas discharge holes 22a is turned into plasma inside the processing space S1 by the induced electric field.

[0037] 1, the plasma processing apparatus 1 is further provided with a control unit U. The control unit U is, for example, a computer equipped with a CPU, a memory, etc., and has a program storage unit (not shown). The program storage unit stores a program for controlling the processing of the substrate G in the plasma processing apparatus 1. The above-mentioned program may be recorded in a computer-readable storage medium and installed from the storage medium into the control unit U. A part or all of the program may be realized by dedicated hardware (circuit board).

[0038] <Fastening structure K> As described above, in conventional plasma processing apparatuses, when the shower plate and the metal window body are fastened with fastening screws, the fastening screws may become loose due to repeated substrate processing (specifically, plasma processing), etc. Therefore, the plasma processing apparatus 1 according to the present embodiment is provided with the following fastening structure K to prevent the fastening screws 24 from becoming loose.

[0039] FIG. 4 is a vertical cross-sectional view showing an outline of the configuration of a fastening structure K included in the plasma processing apparatus 1, and corresponds to FIG. 3 turned upside down and partially enlarged.

[0040] The fastening structure K in FIG. 4 includes a female thread portion 100 provided in the metal window main body 23, a through hole 110 and a countersunk portion 111 provided in the shower plate 22, a fastening screw 24, and a flat washer 120.

[0041] The female thread portion 100 is configured, for example, by an insert 101 having a female thread that is embedded in the metal window main body 23. The insert 101 is, for example, a coil-shaped member formed by winding a wire having a rhombic cross section. The female screw portion 100 is formed, for example, as follows: That is, a pilot hole formed on the shower plate 22 side of the metal window body 23 is tapped, and the insert 101, which is the coil-shaped member, is screwed in, thereby forming the female screw portion 100. The material used for the insert 101 is a material having higher rigidity than the material used for the metal window body 23. When aluminum is used as the material for the metal window body 23, the material used for the insert 101 is, for example, stainless steel.

[0042] The through hole 110 is formed in the shower plate 22 on the metal window body 23 side at a position corresponding to the female thread portion 100 .

[0043] The countersunk portion 111 is formed in the shower plate 22 so as to be continuous with the through hole 110. Specifically, the countersunk portion 111 is recessed in the penetration direction of the through hole 110 from the surface of the shower plate 22 opposite the metal window body 23, and is formed so as to be continuous with the side of the through hole 110 opposite the metal window body 23.

[0044] The fastening screw 24 has a male threaded portion 24a that is inserted through the through hole 110 and screws into the female threaded portion 100, and a screw head 24b that is continuous with the base end of the male threaded portion 24a. The diameter of the through hole 110 is set so that only the male threaded portion 24a of the fastening screw 24 can be inserted into the through hole 110, and the screw head 24b cannot be inserted. The diameter of the countersunk portion 111 is set so that not only the male threaded portion 24a of the fastening screw 24 but also the screw head 24b can be inserted. The diameter of the male threaded portion 24a is, for example, 3 to 7 mm, and the diameter of the screw head 24b is, for example, 6 to 15 mm.

[0045] The flat washer 120 is fitted into the countersunk portion 111 of the shower plate 22, and the male threaded portion 24a of the fastening screw 24 is inserted into the flat washer 120. Specifically, the flat washer 120 has a hole in the center through which only the male threaded portion 24a of the fastening screw 24 can be inserted, and has an outer diameter that allows the flat washer 120 to fit into the countersunk portion 111.

[0046] As described above, the flat washer 120 is fitted into the countersunk portion 111 of the shower plate 22. Therefore, when the through hole 110 and the countersunk portion 111 of the shower plate 22 move relative to the female screw portion 100 of the metal window main body 23, the flat washer 120 moves relative to the female screw portion 100 together with the countersunk portion 111 and the like. At this time, if the frictional force between the screw head 24b and the flat washer 120 is large, the frictional force may become a torque and apply a force in the rotational direction to the screw head 24b, which may loosen the fastening screw 24. Note that the diameter of the hole in the center of the flat washer 120 through which the male screw portion 24a can be inserted is set so that the flat washer 120 and the male screw portion 24a of the fastening screw 24 do not collide with each other during the relative movement of the flat washer 120.

[0047] In the fastening structure K, either or both of the first surface 24c of the screw head 24b facing the plain washer 120 and the second surface 120a of the plain washer 120 facing the screw head 24b are coated with a lubricating material. In other words, either or both of the first surface 24c and the second surface 120a are coated with a lubricating material. This makes it possible to reduce the frictional force acting between the plain washer 120 and the fastening screw 24.

[0048] The coating with a lubricating material is, for example, a coating with polytetrafluoroethylene (PTFE)-containing electroless nickel plating.

[0049] In addition, in the fastening structure K, the male threaded portion 24a of the fastening screw 24 is screwed into the female threaded portion 100 via the flat washer 120 and the through hole 110, and the fastening screw 24 is tightened, whereby the shower plate 22 can be fastened to the metal window body 23 by the fastening screw 24.

[0050] <Function of fastening structure K> Next, the operation of the fastening structure K in the plasma processing apparatus 1 will be described. In the plasma processing apparatus 1, the shower plate 22 receives heat from the plasma of the processing gas and is temperature-regulated, but the temperature regulation is via the metal window body 23, so the shower plate 22 becomes hot and expands during plasma processing. On the other hand, the metal window body 23 receives no direct heat from the plasma of the processing gas and is directly temperature-regulated by the temperature regulation flow path 23b, so the temperature of the metal window body 23 hardly changes and does not expand during plasma processing. Therefore, the relative positions of the female thread portion 100 of the metal window body 23 and the through hole 110 and the countersunk portion 111 of the shower plate 22 are different during plasma processing and during times other than plasma processing. In other words, during plasma processing, the through hole 110 and the countersunk portion 111 move relative to the female thread portion 100 and also move relative to the fastening screw 24 attached to the female thread portion 100.

[0051] Unlike the fastening structure K, in the case of a flat washer having an outer diameter smaller than that fitted into the countersunk portion 111, that is, in the case of a flat washer that is movable inside the countersunk portion 111, when the through hole 110 and the countersunk portion 111 move relative to the fastening screw 24, the flat washer does not move sufficiently relative to the fastening screw 24. For this reason, the flat washer moves relative to both the fastening screw 24 and the countersunk portion 111, and there is a possibility that the way in which the fastening force is applied between the fastening screw 24, the metal window main body 23, and the flat washer changes more significantly, and the fastening screw 24 may become loose due to the change in fastening force accompanying the movement of the flat washer.

[0052] In contrast, in the fastening structure K, as described above, the plain washer 120 is fitted into the countersunk portion 111, so when the through hole 110 and the countersunk portion 111 move relative to the fastening screw 24, the plain washer 120 moves together with the countersunk portion 111 relative to the fastening screw 24. Therefore, the plain washer 120 is fixed within the countersunk portion 111 and the way in which the force is applied therebetween does not change, and the screw head 24b of the fastening screw 24 moves on the stable surface of the plain washer 120, so there is little change in the way in which the force is applied therebetween. Therefore, there is a low possibility that the fastening screw 24 will loosen due to a change in the fastening force accompanying the movement of the plain washer 120.

[0053] Furthermore, in the fastening structure K, either or both of the first surface 24c of the fastening screw 24 and the second surface 120a of the plain washer 120 are coated with a lubricating material. Therefore, when the plain washer 120 moves relative to the fastening screw 24, that is, when the plain washer 120 slides on the first surface 24c of the screw head 24b, the frictional force acting between the plain washer 120 and the screw head 24b of the fastening screw 24 is small. Therefore, the fastening screw 24 does not loosen due to this frictional force.

[0054] Therefore, according to the fastening structure K, it is possible to prevent the fastening screw 24 from becoming loose.

[0055] <Substrate processing> Next, the substrate processing in the plasma processing apparatus 1 will be described. First, the gate valve 12 is opened, and the substrate G is loaded into the processing space S1 through the load / unload port 11 and placed on the substrate support portion 30. Thereafter, the gate valve 12 is closed.

[0056] Then, a processing gas is supplied from the processing gas supply unit 61 into the processing space S1 through the diffusion chamber 23a of each partial window 21. In addition, the processing space S1 is evacuated by the exhaust unit 50, and the inside of the processing space S1 is adjusted to a desired pressure.

[0057] Next, high frequency power is supplied from the high frequency power source 43 to the high frequency antenna 80, which generates an induced electric field in the processing space S1 through the metal window 20. As a result, the processing gas in the processing space S1 is converted into plasma by the induced electric field, generating high-density inductively coupled plasma. Then, ions in the plasma are attracted to the substrate G by the bias high frequency power supplied from the high frequency power source 41 to the main body 31 of the substrate support 30, and plasma processing is performed on the substrate G.

[0058] After the plasma processing is completed, the power supply from the high frequency power sources 41 and 43 and the supply of the processing gas from the processing gas supply unit 61 are stopped, and the substrate G is unloaded in the reverse order to that of the loading. This completes the series of substrate processing steps.

[0059] During the above-mentioned series of substrate processing, including during plasma processing, the shower plate 22 of each partial window 21 is adjusted in temperature by a temperature control fluid supplied to the temperature control flow path 23b. However, during plasma processing, the shower plate 22 becomes hot and expands due to heat input from the plasma. Therefore, the through hole 110 and the countersunk portion 111 of the shower plate 22 move relative to the fastening screw 24. However, in the plasma processing apparatus 1, the flat washer 120 is fitted into the countersunk portion 111, and either or both of the first surface 24c of the fastening screw 24 and the second surface 120a of the flat washer 120 are coated with a lubricating material. Therefore, the above-mentioned relative movement does not apply a large frictional force between the flat washer 120 and the screw head 24b of the fastening screw 24, so that the fastening screw 24 does not loosen.

[0060] As described above, according to the present embodiment, in the fastening structure in which the shower plate 22 and the metal window body 23 constituting the plasma processing apparatus 1 are fastened by the fastening screws 24, it is possible to prevent the fastening screws 24 from becoming loose.

[0061] If the fastening screw 24 loosens, the sealing of the diffusion chamber 23a by the O-ring 25, for example, may decrease, and the processing gas may reach between the periphery of the shower plate 22 and the periphery of the metal window body 23. In this case, since there are areas on the periphery of the shower plate 22 and the periphery of the metal window body 23 that are not coated with a corrosion-resistant coating as described above, if a corrosive gas is used as the processing gas or cleaning gas, the areas will corrode. As a result, particles that cause defects in the electronic device formed on the substrate G may be generated, or the electrical conduction between the shower plate 22 and the metal window body 23 and the heat transfer between the two members may be impaired. If the heat transfer between the shower plate 22 and the metal window body 23 is impaired, only the multiple partial windows 21 that constitute the metal window 20 will become high in temperature, and a temperature bias will occur within the surface of the metal window 20. As a result, the plasma of the processing gas may also be biased, and the desired plasma processing may not be performed. Furthermore, if the airtightness of the diffusion chamber 23a is reduced, the spiral ring 26 corrodes, resulting in the generation of particles and the like.

[0062] According to this embodiment, the fastening screws 24 do not loosen, and therefore the airtightness of the diffusion chamber 23a does not decrease, so that the generation of particles as described above can be prevented, and also, the electrical conductivity between the shower plate 22 and the metal window body 23 and the heat transfer between the two components can be prevented from being impaired.

[0063] <Modification> In the above examples, either or both of the first surface 24c of the fastening screw 24 and the second surface 120a of the plain washer 120 are coated with a lubricating material. The portion coated with the lubricating material is not limited to this, and may be, for example, either or both of the entire fastening screw 24 and the entire plain washer 120. In other words, in the fastening structure K, it is sufficient that at least either or both of the first surface 24c of the fastening screw 24 and the second surface 120a of the plain washer 120 are coated with a lubricating material.

[0064] Furthermore, by coating the male thread portion 24a of the fastening screw 24 with a lubricating material in addition to either or both of the first surface 24c of the fastening screw 24 and the second surface 120a of the plain washer 120, the following effect is obtained. That is, since the frictional force between the male thread portion 24a and the female thread portion 100 is reduced, the force that counteracts the frictional force in the fastening torque is small, and even if the fastening screw 24 is fastened with the same fastening torque, the shower plate 22 and the metal window main body 23 can be more reliably fastened together. As a result, it is possible to prevent the fastening screw 24 from loosening due to insufficient fastening force of the fastening screw 24 against the metal window main body 23.

[0065] 5 to 7 are vertical cross-sectional views showing other examples of the fastening structure. In the fastening structure K1 in Fig. 5, the female screw portion 100 is formed by an insert 200 having a locking function (i.e., a function to prevent loosening). The insert 200 is, for example, a coil-shaped member made by winding a wire having a diamond-shaped cross section, with the central portion wound into a polygonal shape. The wire bent into a polygonal shape expands as the male screw portion 24a of the fastening screw 24 is screwed in, and the repulsive force of this expansion tightens the male screw portion 24a, thereby preventing the fastening screw 24 from loosening. Furthermore, when the insert 200 is used, it is advisable to coat the male thread portion 24a of the fastening screw 24 with a lubricating material as well. This makes it possible to prevent the male thread portion 24a from seizing when the male thread portion 24a is screwed in.

[0066] In the fastening structure K2 of Fig. 6, the fastening screw 210 is a flange bolt, and its screw head 211 has a flange 212 at the end on the male threaded portion 24a side. Therefore, in the fastening structure K2, the contact area between the first surface 211a of the fastening screw 210 and the second surface 120a of the plain washer 120 is large, so that the pressure applied to the first surface 211a and the second surface 120a can be dispersed, that is, the pressure per unit area applied to the first surface 211a and the second surface 120a can be reduced. As a result, it is possible to suppress damage or deformation of the fastening screw 24 and the plain washer 120 due to extreme stress caused by localized high pressure, and to prevent the screw from becoming unable to rotate due to deformation when attaching or detaching the screw.

[0067] The fastening structure K3 in FIG. 7 is similar to the fastening structure K2 in FIG. 6 except that a bolt cover 130 consisting of a flat washer portion 131 and a side wall portion (side wall member) 132 is used, and a flange bolt is used for the fastening screw 210.

[0068] The side wall portion 132 is cylindrical and is joined to an upper portion of the peripheral end of the plain washer portion 131, i.e., to the side where the fastening screw 210 is inserted. The inner diameter of the side wall portion 132 is larger than the outer diameter of the flange 212 of the fastening screw 210, and the outer diameter of the side wall portion 132 is smaller than the inner diameter of the countersunk portion 111. The flat washer portion 131 is the same as the flat washer 120 of the fastening structure K2 in Fig. 6 except that a side wall portion 132 is joined to the peripheral edge of the flat washer portion 131. In other words, the flat washer 120 of the fastening structure K2 in Fig. 6 constitutes the bolt cover 130 together with the side wall portion 132 joined to the peripheral edge of the flat washer 120 as the flat washer portion 131.

[0069] In the bolt cover 130, a recess 140 recessed in the thickness direction of the plain washer portion 131 is formed by the side wall portion 132 and the plain washer portion 131. When the bolt cover 130 is attached to the fastening screw 210 and the male thread portion 24a is inserted into the plain washer portion 131, the screw head 211 of the fastening screw 210 fits in the recess 140.

[0070] A fall-prevention ring (fall-prevention member) 133 is disposed on the inside of the side wall portion 132, i.e., on the inside of the recess 140. The fall-prevention ring 133 is caught (i.e., engaged) on the flange 212 of the fastening screw 210, thereby preventing the bolt cover 130 attached to the fastening screw 210 from falling off from the fastening screw 210. This makes it possible to improve the efficiency of the fastening work using the fastening screw 210.

[0071] The fall-off prevention ring 133 is disposed in the recess 140 in a contracted state, and is fixed to the side wall portion 132 in the recess 140 by the elastic force generated by the contraction. The fall-off prevention ring 133 is, for example, an elastic member whose inner diameter is larger than the outer diameter of the screw head 211 and smaller than the outer diameter of the flange 212, and may be, for example, a C-ring or the like that is made of a metal material and has a C-shape in plan view.

[0072] The side wall portion 132 has a joint end portion that is joined to the flat washer portion 131, and an open end portion that is open on the opposite side to the joint end portion. A step is provided on the inner wall of the side wall portion 132 between the joint end portion and the open end portion, where the drop prevention ring 133 is disposed. The inner diameter of the side wall portion 132 is smaller on the open end side than on the joint end side from the step, preventing the drop prevention ring 133 from slipping out from the open end portion. The drop prevention ring 133 is fitted from the upper portion of the bolt cover 130, i.e., the open end portion of the side wall portion 132, after the fastening screw 210 is inserted into the bolt cover 130. Note that the step is not the only option, and other structures may be used as long as they can prevent the drop prevention ring 133 from slipping out.

[0073] The above has been explained using an example of a process in which a difference in the degree of expansion occurs between the fastened components, but the technology disclosed herein can prevent the fastening screws from loosening even in a process in which a difference in the degree of contraction occurs between the fastened components (specifically, for example, the process in which the shower plate 22 returns to the temperature before the plasma processing after the plasma processing).

[0074] In the above examples, the substrate to be processed in the plasma processing is a glass substrate, but it may be another substrate such as a semiconductor wafer.

[0075] In the above example, the technology according to the present disclosure is used for the fastening structure between the shower plate 22 and the metal window body 23 constituting the plasma processing apparatus 1, but the technology according to the present disclosure can also be applied to other fastening structures using fastening screws in the plasma processing apparatus 1. In addition, the technology according to the present disclosure can be applied to structures using fastening screws in substrate processing apparatuses other than plasma processing apparatuses.

[0076] <Confirmation test> The present inventors conducted a test to confirm the effect of the fastening structure according to the present disclosure in suppressing loosening of the fastening screw. In this confirmation test, a plate material (hereinafter, metal window body simulant) that is rectangular in plan view and has a recess on its underside similar to the recess that forms the diffusion chamber 23a of the metal window body 23 was fixed, and a plate-like member (hereinafter, shower plate simulant) whose dimensions in plan view are equivalent to those of the metal window body simulant was fastened to the underside of the metal window body simulant with fastening screws. Then, multiple air cylinders were provided along each of the long sides of the shower plate simulant, and the shower plate simulant was vibrated horizontally 100 times in the short side direction of the shower plate simulant with these air cylinders, after which the loosening angle of the fastening screws was measured. The dimensions of the metal window body simulant and shower plate simulant in plan view were approximately 150 mm x 400 mm, and the amplitude of the shower plate simulant caused by the air cylinder was approximately 0.5 mm. Aluminum was used as the material for the metal window body simulant and shower plate simulant, and fastening screws were used in a total of six locations, at the four corners and the center of each long side of the shower plate simulant. The diameter of the male thread of the fastening screw was 5 mm, and the diameter of the screw head was 8 mm (the diameter of the flange part in the case of a flange was 10 mm).

[0077] In the test example, a fastening structure similar to the fastening structure K2 in Fig. 6 was adopted. That is, a flange bolt was used as the fastening screw, and an insert with a locking function (i.e., a function to prevent loosening) was used. In addition, the fastening screw and flat washer were made of stainless steel, and the whole was treated with electroless nickel plating containing PTFE.

[0078] The fastening structure of Comparative Example 1 was similar to the fastening structure K in Fig. 4. However, in the fastening structure of Comparative Example 1, neither the fastening screw nor the flat washer was coated with a lubricating material, and the flat washer was smaller than that of the test example and was not fitted into the counterbore. In other words, the fastening structure of Comparative Example 1 was a conventional fastening structure.

[0079] The fastening structure of Comparative Example 2 was similar to the fastening structure K in Fig. 5. However, in the fastening structure of Comparative Example 2, neither the fastening screw nor the flat washer was coated with a lubricating material, and the flat washer was smaller than that of the test example and was not fitted into the counterbore. In other words, the fastening structure of Comparative Example 2 is a structure in which the insert of the fastening structure of Comparative Example 1, which is a conventional fastening structure, is replaced with an insert having a locking function.

[0080] 8 to 10 are diagrams showing the loosening angles of the fastening screws at six locations in Comparative Example 1, Comparative Example 2, and Test Example, respectively.

[0081] In Comparative Example 1 using a conventional fastening structure, five of the six fastening screws were loosened by 90° or more, and the remaining one was loosened by 45°, as shown in Fig. 8. In other words, the conventional fastening structure causes a large degree of loosening of the fastening screws.

[0082] In addition, in Comparative Example 2, the degree of loosening of the fastening screws was reduced compared to Comparative Example 1, but five of the six fastening screws were loosened by 30° or more, as shown in Fig. 9. In other words, simply replacing the insert in the conventional fastening structure with an insert having a locking function cannot sufficiently suppress the loosening of the fastening screws.

[0083] In contrast, in the test example, five out of six fastening screws were not loosened at all, and the remaining one also had a small loosening angle of 15°, as shown in Figure 10. In this way, the fastening structure according to the present disclosure can suppress loosening of the fastening screws.

[0084] The embodiments disclosed herein should be considered as illustrative and not restrictive in all respects. The above-described embodiments may be omitted, substituted, or modified in various forms without departing from the scope and spirit of the appended claims. [Explanation of symbols]

[0085] 1. Plasma processing equipment 22 Shower Plate 23 Metal window body 24, 210 Fastening screw 24a Male thread 24b, 211 screw head 24c, 211a 1st page 100 Female thread 110 Through hole 111 Counterbore 120 Flat washer 120a Second Face G Glass substrate K, K1, K2, K3 fastening structure

Claims

1. A fastening structure for fastening a first member and a second member constituting a substrate processing apparatus, comprising: The first member has a female thread portion, the second member has a through hole corresponding to the female screw portion, and a countersunk portion continuous with the through hole and having a diameter larger than that of the through hole, A fastening screw having a male screw portion that is inserted into the through hole and screwed into the female screw portion, and a screw head portion that is continuous with an end of the male screw portion; a flat washer that is fitted into the countersunk portion and through which the male screw portion is inserted, At least one or both of a first surface of the screw head facing the flat washer and a second surface of the flat washer facing the screw head are coated with a lubricating material; A fastening structure, wherein the relative positions of the female screw portion, the through hole, and the countersunk portion are different when the substrate is being processed by the substrate processing apparatus and when the substrate is not being processed.

2. The fastening structure according to claim 1 , wherein the fastening screw has a head portion having a flange at an end of the male thread portion.

3. A fastening structure for fastening a first member and a second member constituting a substrate processing apparatus, comprising: The first member has a female thread portion, the second member has a through hole corresponding to the female screw portion, and a countersunk portion continuous with the through hole and having a diameter larger than that of the through hole, A fastening screw having a male screw portion that is inserted into the through hole and screwed into the female screw portion, and a screw head portion that is continuous with an end of the male screw portion; a flat washer that is fitted into the countersunk portion and through which the male screw portion is inserted, At least one or both of a first surface of the screw head facing the flat washer and a second surface of the flat washer facing the screw head are coated with a lubricating material; The fastening screw has a screw head having a flange at an end on the male thread portion side, The flat washer constitutes a bolt cover together with a cylindrical side wall member joined to the peripheral portion of the flat washer as a flat washer portion, and a fall prevention member is arranged on the inner wall portion of the side wall member, and the fall prevention member engages with the flange to prevent the bolt cover from falling off the fastening screw.

4. The fastening structure according to any one of claims 1 to 3, wherein the coating with the lubricating material is electroless nickel plating containing polytetrafluoroethylene.

5. A plasma processing apparatus for performing plasma processing on a substrate, The plasma processing apparatus includes a first member and a second member which are components of the plasma processing apparatus and are fastened to each other; The first member has a female thread portion, the second member has a through hole corresponding to the female screw portion, and a countersunk portion continuous with the through hole and having a diameter larger than that of the through hole, A fastening screw having a male screw portion that is inserted into the through hole and screwed into the female screw portion, and a screw head portion that is continuous with an end of the male screw portion; a flat washer fitted to the countersunk portion and through which the male screw portion is inserted, At least one or both of a first surface of the screw head facing the flat washer and a second surface of the flat washer facing the screw head are coated with a lubricating material; The fastening screw has a screw head having a flange on the first surface side, A plasma processing apparatus in which the flat washer constitutes a bolt cover together with a cylindrical side wall member joined to the peripheral portion of the flat washer as a flat washer portion, and a fall-off prevention member is arranged on an inner wall portion of the side wall member, and the fall-off prevention member engages with the flange to prevent the bolt cover from falling off the fastening screw.

6. a shower head for supplying a processing gas to a processing space in which a substrate to be processed by plasma processing is located; 6. The plasma processing apparatus according to claim 5, wherein the showerhead is composed of a base member and a shower plate, the first member being the base member and the second member being the shower plate.

7. 7. The plasma processing apparatus according to claim 5, wherein the coating of the lubricating material is electroless nickel plating containing polytetrafluoroethylene.

Images