Manufacturing method of exhaust screen, plasma treatment device and exhaust screen

Abstract

A technology is provided that can achieve a balance between exhaust performance and discharge stability. A method for manufacturing an exhaust mesh is provided, through which gas is passed when it is discharged from the processing container of a plasma processing apparatus, comprising: (a) a step of preparing a plurality of metal plates; (b) a step of forming a plurality of hexagonal through-holes in adjacent honeycomb structures on each of the plurality of metal plates to obtain a plurality of thin-plate honeycomb meshes; and (c) a step of laminating the plurality of thin-plate honeycomb meshes so that the plurality of through-holes in the plurality of thin-plate honeycomb meshes are interconnected, and then joining the plurality of thin-plate honeycomb meshes together to produce a thickened exhaust mesh.

Description

[Technical Field]

[0001] This disclosure relates to a method for manufacturing an exhaust screen, a plasma treatment apparatus, and an exhaust screen. [Previous Technology]

[0002] Patent Document 1 discloses a plasma processing apparatus that introduces gas into a processing container to plasmaize it for etching or other processing of a substrate. The gas generated during this process is vented from the processing container to an venting section (venting mechanism). To prevent plasma from seeping into the venting section, the plasma processing apparatus includes a venting mesh (mesh member) made of metal and connected to a ground potential. The venting mesh has multiple circular through holes extending through its thickness direction.

[0003] Although a larger opening ratio of each through hole in this type of exhaust mesh makes it easier for gas to escape, it can also easily lead to abnormal discharges caused by plasma infiltration. In other words, the exhaust performance of the exhaust mesh and the discharge stability are in a trade-off relationship.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2020-188194 [Summary of the Invention]

[0005] This disclosure provides a technology that can achieve a balance between exhaust performance and discharge stability.

[0006] This disclosure provides a method for manufacturing an exhaust screen that allows gas to pass through when it is discharged from the processing container of a plasma processing device, comprising: (a) a step of preparing a plurality of metal plates; (b) a step of forming a plurality of hexagonal through holes in adjacent honeycomb structures on each of the plurality of metal plates to obtain a plurality of thin-plate honeycomb meshes; and (c) a step of laminating the plurality of thin-plate honeycomb meshes so that the plurality of through holes in the plurality of thin-plate honeycomb meshes are interconnected, and a step of joining the plurality of thin-plate honeycomb meshes together to produce the thickened exhaust screen.

[0007] Based on a single state, it is possible to achieve a balance between exhaust performance and discharge stability.

Implementation Method

[0009] Hereinafter, the form used to implement this disclosure will be described with reference to the drawings. In each drawing, there will be cases where the same symbols are given to the same constituent parts to omit repeated descriptions.

[0010] FIG1 is a cross-sectional schematic diagram showing an example of a plasma treatment apparatus related to an embodiment. As shown in FIG1, an exhaust screen 100 related to an embodiment is used in the plasma treatment apparatus 1. Hereinafter, in order to facilitate understanding of the present invention, the configuration of the plasma treatment apparatus 1 will be described first.

[0011] The plasma processing apparatus 1 is an inductively coupled plasma (ICP) processing apparatus that performs various substrate processing on an FPD substrate (hereinafter referred to as substrate G). Examples of FPDs manufactured from the processed substrate G include liquid crystal displays (LCDs), electroluminescent displays (ELs), and plasma display panels (PDPs). In this case, the substrate G is made of materials such as glass or synthetic resin. The substrate G may include a support substrate with circuit patterns on its surface or without circuits. The planar dimensions of the substrate can be approximately 1800 mm to 3400 mm for the long side and approximately 1500 mm to 3000 mm for the short side. Furthermore, the thickness of the substrate G can be approximately 0.2 mm to 4.0 mm. Examples of substrate processing performed by the plasma processing apparatus 1 include film deposition processing using CVD (Chemical Vapor Deposition) or etching processing. The plasma processing apparatus 1, which performs film formation processing to process a substrate, will be described below.

[0012] The plasma processing apparatus 1 includes a rectangular box-shaped processing container 10. The processing container 10 is formed of a metal such as aluminum or an aluminum alloy. Furthermore, the processing container 10 can be formed into an appropriate shape corresponding to the shape of the substrate G. For example, if the substrate G is a circular plate or an elliptical plate, the processing container 10 is preferably formed into a cylindrical shape or an elliptical cylindrical shape.

[0013] The processing container 10 has a rectangular support frame 11 at a predetermined position in the vertical direction, which protrudes into the inside of the processing container 10, and the dielectric plate 12 is supported in the horizontal direction by the support frame 11. The processing container 10 is divided into an upper chamber 13 and a lower chamber 14 through the dielectric plate 12. The upper chamber 13 has an antenna chamber 13a formed on its inner side. The lower chamber 14 has an internal space 14a formed on its inner side for receiving the substrate G and performing substrate processing.

[0014] The side wall 15 of the lower chamber 14 is provided with a transfer inlet 17 that is opened and closed by a gate valve 16. When the gate valve 16 is open, the plasma processing device 1 transfers the substrate G in and out through the transfer inlet 17 by a transfer device (not shown).

[0015] In addition, the sidewall 15 of the lower chamber 14 is grounded (connected to the ground potential) through the grounding wire 18. The sidewalls 15 on all four sides of the lower chamber 14 have sealing grooves 19 wound into an endless shape at the upper end. By placing sealing members 20 such as O-rings in the sealing grooves 19, the support frame 11 and the lower chamber 14 are airtightly sealed to the internal space 14a.

[0016] The support frame 11 is formed of a metal such as aluminum or aluminum alloy. In addition, the dielectric plate 12 is formed of a ceramic such as aluminum oxide (Al2O3) or quartz.

[0017] A spray head 21 is provided inside the support frame 11. The spray head 21 is connected to the support frame 11, is composed of multiple elongated components, and sprays gas into the internal space 14a, also serving as a support beam for the dielectric plate 12. The dielectric plate 12 is supported on the spray head 21. The spray head 21 is preferably formed of a metal such as aluminum and is surface treated by anodizing. A gas flow channel 21a is formed in the horizontal direction inside the spray head 21. In addition, the spray head 21 has multiple gas ejection holes 21b that connect the gas flow channel 21a to the bottom of the spray head 21 (internal space 14a).

[0018] A gas inlet pipe 22 is connected to the spray head 21 and communicates with the gas flow channel 21a. The gas inlet pipe 22 extends upward in the upper chamber 13 and passes through the upper chamber 13, and is connected to the gas supply section 23 located outside the processing container 10.

[0019] The gas supply unit 23 has a gas supply pipe 24 connected to the gas inlet pipe 22, and a gas supply source 25, a mass flow controller 26, and an on / off valve 27 are sequentially provided from upstream to downstream of the gas supply pipe 24. During the film formation process, gas is supplied from the gas supply source 25, the flow rate is controlled by the mass flow controller 26, and the supply time is controlled by the on / off valve 27. The gas flows from the gas supply pipe 24 through the gas inlet pipe 22 into the gas flow channel 21a, and is ejected into the internal space 14a through each gas ejection hole 21b.

[0020] A high-frequency antenna 28 is installed inside the upper cavity 13 forming the antenna chamber 13a. The high-frequency antenna 28 is formed by arranging antenna wires made of conductive metal such as copper into a loop or a spiral shape. Alternatively, the high-frequency antenna 28 may be a loop antenna configured in multiple layers. The terminals of the high-frequency antenna 28 are connected to a power supply member 29 that extends upward within the upper cavity 13.

[0021] The power supply component 29 has an upper end that protrudes outside the processing container 10, and a power supply line 30 is connected to this upper end. The power supply line 30 is connected to the high-frequency power supply 32 through an impedance matching device 31. The high-frequency power supply 32 applies high-frequency power corresponding to the frequency of the substrate processing (e.g., 13.56MHz) to the high-frequency antenna 28. Thereby, the high-frequency antenna 28 will generate an induced electric field within the lower cavity 14.

[0022] Furthermore, the processing container 10 has a platform 40 (placement stage) in the lower chamber 14 for placing the substrate G after it has been moved in from the transfer inlet 17. The platform 40 has a platform body 41, a platform 42, a plurality of lifting pins 43, and a plurality of lifting pin lifting mechanisms 44. The substrate G, after being moved into the lower chamber 14, is transferred to each lifting pin 43 after it has been raised by each lifting pin lifting mechanism 44, and is placed on the platform body 41 by lowering each lifting pin 43.

[0023] The base body 41 has a mounting surface 411 that is rectangular when viewed from above and has a planar dimension that is approximately the same as that of the substrate G. For example, the planar dimension of the mounting surface 411 may be approximately 1800 mm to 3400 mm for the long side and approximately 1500 mm to 3000 mm for the short side.

[0024] A plasma processing space PCS is formed between the mounting surface 411 of the pedestal body 41 and the spray head 21. In the plasma processing space PCS, plasma is generated by the induced electric field formed by the high-frequency antenna 28, which plasmaifies the gas supplied from the spray head 21 to the internal space 14a. The plasma processing apparatus 1 supplies the film-forming precursor in the plasma generated in the plasma processing space PCS to the substrate G.

[0025] Furthermore, the platform body 41 internally includes a heating wire 45, which is a resistive element formed of aluminum or aluminum alloy. The heating wire 45 is connected to the heater drive unit 46 and is heated based on the power supply from the heater drive unit 46. The heater drive unit 46 is connected to the control unit 60 of the plasma processing apparatus 1 and outputs power according to the temperature command of the control unit 60. Moreover, the platform body 41 may also be equipped with a cooling mechanism for precise temperature control. For example, when performing substrate processing (film formation processing), the plasma processing apparatus 1 heats the mounting surface 411 of the platform 40 to about 200°C and maintains it at that temperature.

[0026] The pedestal 42 is formed of insulating material and is disposed in the base plate 33 of the lower chamber 14 to support the pedestal body 41. The pedestal 42 has an opening at the bottom, which fixes and supports the pedestal body 41 in a state where the pedestal body 41 is separated from the base plate 33.

[0027] The plasma processing apparatus 1 has a control unit 60 that controls the operation of the entire apparatus. The control unit 60 is a computer that includes one or more processors 61, memory 62, input / output interfaces (not shown), and electronic circuits. The memory 62 includes non-volatile memory and volatile memory, forming a memory unit of the control unit 60 that stores programs and process parameter condition data. In addition, a portion of the memory 62 may also be built into the processor 61. The input / output interface is an input / output device (not shown) connected to the plasma processing apparatus 1. Examples of input / output devices include touch panels, monitors, and keyboards. The one or more processors 61 can be a combination of one or more of the following: CPU, ASIC, FPGA, circuits composed of multiple discrete semiconductors, etc. The one or more processors 61 execute the program in the memory 62 and perform plasma processing on the substrate G according to the process parameter condition data.

[0028] Furthermore, the plasma treatment apparatus 1 has an exhaust port 14b on the bottom plate 33 of the treatment container 10 for discharging gas from the internal space 14a, and an exhaust section 70 connected to the treatment container 10 through the exhaust port 14b. Although one exhaust port 14b and one exhaust section 70 are shown in FIG1, the plasma treatment apparatus 1 may also have multiple exhaust ports 14b and exhaust sections 70.

[0029] The exhaust port 14b is formed in a perfect circle and is located between the side wall of the processing container 10 and the base 40. The diameter of the exhaust port 14b depends on the size of the processing container 10, but is preferably set in the range of about 200mm to 400mm. In this embodiment, it is set to 300mm. In addition, the shape of the exhaust port 14b may not be perfect circle, depending on the placement position, and may be a semi-circle or other shape corresponding to the placement position.

[0030] Figure 2 is an enlarged cross-sectional view of the exhaust port 14b (gas exhaust port) that discharges gas from the processing container 10. As shown in Figure 2, the exhaust section 70 includes an exhaust pipe 71 connected to the exhaust port 14b and an exhaust mechanism 72 provided in the exhaust pipe 71 to discharge the gas (e.g., volatile gas) in the processing container 10.

[0031] The exhaust pipe 71 has a circular cross-sectional shape and is a pipe with a channel 71a communicating with the exhaust port 14b on its inner side, and is formed of a suitable metal. The exhaust pipe 71 can extend straight downward as shown in FIG2, or it can be bent or folded at a midway point. In addition, as mentioned above, by grounding the processing container 10, the exhaust pipe 71 connected to the processing container 10 is also grounded. The inner circumferential surface of the exhaust pipe 71 constituting the channel 71a is preferably coated with a coating to inhibit corrosion of the exhaust pipe 71.

[0032] As shown in Figures 1 and 2, the exhaust mechanism 72 is equipped with an APC (Automatic Pressure Control) valve 73, a turbomolecular pump (TMP) 74, and a dry pump 75 sequentially on the downstream side of the exhaust pipe 71 in the gas flow direction. The exhaust mechanism 72 performs a rough evacuation of the processing container 10 using the dry pump 75, and then uses the turbomolecular pump 74 to create a vacuum inside the processing container 10. Furthermore, the exhaust mechanism 72 controls the pressure in the internal space 14a by adjusting the opening degree of the APC valve 73.

[0033] The exhaust screen 100 is disposed in the plasma treatment apparatus 1 between the base 40 (platform) and the inlet side of the APC valve 73 of the exhaust mechanism 72 of the exhaust pipe 71, through the exhaust port 14b, and in contact with the exhaust pipe 71 or the lower chamber 14. The exhaust screen 100 becomes grounded by contacting the exhaust pipe 71 or the lower chamber 14, which is at a grounded potential. In this way, the exhaust screen 100 can shield the plasma and suppress the plasma from seeping into the APC valve 73, turbomolecular pump 74, etc. Preferably, a portion of the exhaust screen 100 is disposed in contact with the lower chamber 14 at a position closer to the exhaust port 14b than the inlet side of the APC valve 73, or at a position near the exhaust port 14b (outlet side, inlet side). By being disposed near the exhaust port 14b, the exhaust screen 100 can prevent discharge caused by plasma seeping into the exhaust pipe 71. In addition, the exhaust screen 100 can prevent parts from falling into the APC valve 73 inside the exhaust pipe 71.

[0034] In this embodiment, the plasma treatment apparatus 1 has an exhaust screen 100 disposed at the connection end of the exhaust port 14b in the exhaust pipe 71, adjacent to the outlet side of the exhaust port 14b. Alternatively, the exhaust screen 100 may be disposed at the inlet side of the exhaust port 14b. Furthermore, the exhaust screen 100 may be configured to contact the lower chamber 14 at the inlet side of the exhaust port 14b, or it may be configured to contact the lower chamber 14 inside the exhaust port 14b (between the outlet side and the inlet side). Alternatively, the exhaust screen 100 may be configured to directly or indirectly contact the lower chamber 14 through electrical conduction in the internal space 14a above the exhaust port 14b. In addition to having an exhaust screen 100 in the exhaust pipe 71 (or exhaust port 14b), the plasma treatment apparatus 1 may also have a baffle (not shown) inside the treatment container 10. Furthermore, if the exhaust screen 100 is not in electrical contact with the lower chamber 14 and is not in contact with the exhaust pipe 71 and thus not at ground potential, the effect of the exhaust screen 100 in shielding plasma will be weakened.

[0035] Figure 3 is a perspective view of the exhaust screen 100. As shown in Figure 3, the exhaust screen 100 is formed into a perfect circle when viewed from above. The diameter of the exhaust screen 100 is preferably set in the range of about 200 mm to 400 mm. In this embodiment, an exhaust screen 100 with a diameter of 300 mm is used to correspond to the size of the exhaust port 14b.

[0036] As shown in Figures 2 and 3, the exhaust mesh 100 has an annular outer frame portion 101 and an inner portion 102 that allows gas to flow inside the outer frame portion 101. Alternatively, the outer frame portion 101 may be omitted, and the exhaust mesh 100 may be constructed solely from the inner portion 102, which has a honeycomb structure 104. Furthermore, the exhaust pipe 71 and the exhaust mesh 100 are detachably fixed to the exhaust pipe 71 by means of a snap-fit ​​mechanism 76.

[0037] For example, the engaging mechanism 76 is provided at the connecting end (upper end) of the exhaust pipe 71 to which the processing container 10 is connected. The inner diameter of the exhaust pipe 71 is set to be approximately the same as the diameter of the inner side portion 102, and the connecting end of the exhaust pipe 71 has a flange portion 77 that extends radially outward corresponding to the outer frame portion 101. With the outer frame portion 101 of the exhaust screen 100 placed on the flange portion 77, the exhaust pipe 71 is fixed to the bottom plate 33 of the processing container 10 by means of fastening or other connection methods. In this way, the plasma processing apparatus 1 can arrange the exhaust screen 100 at a position adjacent to the exhaust port 14b of the processing container 10 along with the connection of the exhaust pipe 71. In addition, the inner side portion 102 is arranged opposite to the channel 71a inside the exhaust pipe 71 when the exhaust pipe 71 is arranged.

[0038] The outer frame 101 and the inner side 102 are interconnected by a metal primarily composed of stainless steel (e.g., SUS304) or aluminum. Furthermore, the exhaust mesh 100 may be coated with a ceramic such as yttrium oxide (Y2O3). This ceramic coating provides the exhaust mesh 100 with plasma resistance. However, the ceramic coating must have a thickness sufficient to allow the exhaust mesh 100 to function as a ground potential in the RF circuit. The exhaust mesh 100, formed of metal and fixed to the exhaust pipe 71, is grounded (connected to a ground potential) through the exhaust pipe 71 and the processing container 10.

[0039] Figure 4 is an explanatory diagram of the honeycomb structure 104 of the exhaust mesh 100. Figure 4(a) is a partial top view of the inner side surface 102 of the exhaust mesh 100, and Figure 4(b) is a partial cross-sectional view along line IV-IV of (a). The inner side surface 102 of the exhaust mesh 100 is formed as a plate, and a honeycomb structure 104 is formed by arranging a plurality of hexagonal (regular hexagonal) through holes 103 that share common edges with each other. That is, as shown in Figure 4(a), the inner side 102 has a plurality of through holes 103 and a plurality of hole edges 105 surrounding each of the plurality of through holes 103. In addition, each through hole 103 may also be a hexagon other than a regular hexagon (e.g., a flat hexagon).

[0040] The through holes 103 of the honeycomb structure 104 are arranged along a direction that makes the hole edges 105 parallel to each other (a direction orthogonal to the long side direction of the hole edge 105) to form the mesh (grid) of the exhaust net 100. Each hole edge 105 is elongated relative to the size of each through hole 103 and extends linearly with a fixed width. Furthermore, each hole edge 105 is formed to the same length corresponding to each hexagonal through hole 103 and is connected to each other at an angle of 120°. By having such a plurality of through holes 103 and a plurality of hole edges 105, the opening ratio of the inner portion 102 (exhaust net 100) is set to 85% or more. That is, by means of the sealing structure 104, the opening ratio of the inner portion 102 of the exhaust net can be greatly improved, allowing gas to flow easily from the exhaust port 14b to the channel 71a.

[0041] Furthermore, as shown in FIG4(b), the exhaust mesh 100 is formed by laminating multiple thin plates (hereinafter referred to as thin plate honeycomb mesh 110) having a honeycomb structure 104 onto each other and joining the multiple thin plate honeycomb meshes 110 together by the manufacturing method described later. Therefore, the exhaust mesh 100 has a configuration in which multiple thin plate honeycomb meshes 110 are joined in the thickness direction (joint portion 106).

[0042] The joint 106 is produced by a suitable joining method in the manufacturing process. For example, the joint 106 is produced by diffusion bonding, in which atoms of the lower thin-plate honeycomb 110 and the upper thin-plate honeycomb 110 diffuse into each other at the interface and simultaneously cross the interface to form new crystal grains. In addition, the joint 106 is not limited to diffusion bonding. As long as the bonding can maintain the electrical conductivity between the lower thin-plate honeycomb 110 and the upper thin-plate honeycomb 110, the lower thin-plate honeycomb 110 and the upper thin-plate honeycomb 110 can also be bonded by bonding methods such as bonding, welding, and pressing.

[0043] The thickness ts (thickness: dimension in the thickness direction) of the thin plate honeycomb mesh 110 is preferably set to correspond to the width We (the interval between two adjacent through holes 103) of the hole edge 105 described later. For example, it can be the same as the width We of the hole edge 105 or slightly shorter than the width We of the hole edge 105. In this embodiment, the thickness ts of the thin plate honeycomb mesh 110 is set to 0.4 mm.

[0044] Furthermore, the width We of the plurality of hole edges 105 is preferably set to a skin depth δ or greater using a high frequency f, relative permeability μr, vacuum permeability μo, and conductivity σ as shown in the following formula (1). This is because it makes it easier for high-frequency electricity to flow along the inner wall surface of the through hole 103 formed by the hole edges 105.

[0045] δ=1 / (π × f × μr × μo × σ)1 / 2…(1)

[0046] As an example, assuming that SUS304 is used as the material of the thin-plate honeycomb mesh 110 and the output frequency is 3.2MHz, the skin depth δ in equation (1) is 0.27mm. Therefore, the width We of the hole edge 105 (the spacing between the through holes 103) is 0.3mm or more. In this way, the high-frequency power can easily flow on the inner wall surface of the through holes 103 of the exhaust mesh 100 formed by joining the thin-plate honeycomb mesh 110, and the high-frequency power can flow to ground through the exhaust mesh 100. As a result, abnormal discharge in the exhaust mesh 100 can be avoided. For example, the width We of the hole edge 105 can also be set to a range of about 0.3mm to 1.0mm. However, if the width We of the hole edge 105 is too wide, the aperture ratio will decrease, the conductivity will decrease, and the gas exhaust efficiency will deteriorate. Therefore, the width We of the hole edge 105 is preferably 0.4mm or less. Based on the above, in order to balance exhaust performance and discharge stability, the spacing between the through holes 103 of the thin plate honeycomb mesh 110 is preferably set to a range of 0.3 mm or more and 0.4 mm or less.

[0047] The width We of the hole edge 105 in this embodiment is 0.4 mm. That is, the hole edge 105 of the thin plate honeycomb mesh 110 presents an approximately square shape with a thickness ts of 0.4 mm and a width We of 0.4 mm on a cross section orthogonal to the extension direction of the hole edge 105.

[0048] Furthermore, the number of laminated sheets of the thin-plate honeycomb mesh 110 constituting the exhaust mesh 100 can be arbitrarily designed, for example, preferably in the range of about 2 to 15 sheets, and in this embodiment, it is 10 sheets. That is, the overall thickness T of the exhaust mesh 100, which has multiple thin-plate honeycomb meshes 110 laminated together, is preferably set in the range of about 0.8 mm to 6.0 mm, and in this embodiment, it is 4.0 mm. By making the thickness T of the exhaust mesh 100 0.8 mm or more, plasma penetration to the APC valve 73 side can be suppressed.

[0049] To suppress plasma infiltration generated by high-frequency electricity in the processing container 10, the size of each through hole in the exhaust mesh 100 is set such that the length E of the line connecting the two opposite vertices of the hexagon of each through hole 103 is shorter than the high-frequency wavelength. Furthermore, to prevent parts used in the processing container 10 (e.g., M4 screws) from falling out, each through hole 103 is preferably set to a size smaller than the parts. As an example, the distance D (width of the through hole 103) between a pair of parallel hole edges 105 sandwiching each through hole 103 can be set to a range of approximately 3.0 mm to 7.0 mm; in this embodiment, it is set to 4.77 mm (=3 / 16 inch).

[0050] Furthermore, when the spacing D between the hole edges 105 is 4.77 mm, and the thickness T of the exhaust mesh 100 is 2.0 mm, the discharge will be unstable; when the thickness T is 4.0 mm, the exhaust characteristics will deteriorate. Therefore, the width of the through hole 103 (the spacing D between a pair of hole edges 105) is preferably in the range of 1.4 to 2.0 times the thickness T of the exhaust mesh 100. When the width of the through hole 103 is less than 1.4 times the thickness T of the exhaust mesh 100, the aperture ratio will decrease, increasing the possibility that gas will have difficulty flowing. On the other hand, when the width of the through hole 103 is greater than 2.0 times the thickness T of the exhaust mesh 100, although the aperture ratio will increase, plasma will easily cause abnormal discharge by passing through the exhaust mesh 100.

[0051] In addition, the ratio of the width We of the hole edge 105 to the width of the through hole 103 (the distance D between a pair of hole edges 105) is preferably in the range of about 1 / 15 to 1 / 8. If the ratio is less than 1 / 15, the discharge stability or mechanical strength of the plasma of the exhaust screen 100 will decrease, and if the ratio is greater than 1 / 8, the opening ratio may decrease.

[0052] Figure 5 is a process diagram illustrating the manufacturing method of the exhaust screen 100. Next, the manufacturing method of the exhaust screen 100 will be described with reference to Figure 5.

[0053] In the manufacture of the exhaust screen 100, the manufacturer will perform the preparation process, the plate processing process, and the joining process in sequence.

[0054] The preparation process involves preparing multiple metal plates 120 as the substrate for the thin-plate honeycomb mesh 110. The manufacturer prepares the multiple metal plates 120 through molding, purchasing, or other means. In this embodiment, the multiple metal plates 120 are stainless steel (SUS) plates with a thickness ts that is the same as the thickness ts of the thin-plate honeycomb mesh 110 to be formed. In the preparation process, plates with a thickness different from the thickness ts of the thin-plate honeycomb mesh 110 may also be appropriately processed (e.g., pressure applied) to obtain the target thickness ts.

[0055] The plate processing step is a process of creating a thin plate honeycomb mesh 110 with a honeycomb structure 104 by forming a plurality of through holes 103 in the metal plate 120. For example, in the plate processing step, each of the plurality of metal plates 120 is etched.

[0056] As an apparatus for etching the metal plate 120, an etching apparatus (not shown) that performs wet etching can be cited as an example. In this case, the manufacturer inputs the processing parameters of the honeycomb structure 104 having multiple through holes 103 into the etching apparatus, and mounts the metal plate 120 in the etching apparatus. A mask for each hole edge 105 of the honeycomb structure 104 is formed on the metal plate 120 in advance, and then the metal plate 120 is immersed in the etching solution of the etching apparatus to form through holes 103 at the parts exposed from the mask. Although burrs may be generated in mechanical processing such as punching, by performing etching in the plate processing process in this way, the generation of processing marks such as burrs on the metal plate 120 can be suppressed. In addition, in the plate processing process, it is not limited to etching; any method that does not generate burrs can be used to form multiple through holes 103 on each metal plate 120. Furthermore, the outer periphery shape of the thin plate honeycomb mesh 110 can be formed simultaneously with the formation of the through hole 103 caused by the above-mentioned wet etching, and the metal plate 120 can also be pre-processed into the outer periphery shape of the thin plate honeycomb mesh 110 before the formation of the through hole 103.

[0057] The joining process is a process in which multiple thin-plate honeycomb meshes 110 formed in the plate processing process are stacked on top of each other and joined together to produce a thickened exhaust mesh 100. At this time, the manufacturer positions the thin-plate honeycomb meshes 110 in such a way that the through holes 103 of the multiple thin-plate honeycomb meshes 110 are interconnected, and at the same time, the thin-plate honeycomb meshes 110 are stacked. For example, the place where the multiple thin-plate honeycomb meshes 110 are stacked (e.g., the worktable for the joining operation) is provided with multiple pins (not shown) that are slightly smaller than the hexagonal through holes 103, and the thin-plate honeycomb meshes 110 can be positioned on top of each other by inserting each of the pins into the through holes 103.

[0058] Alternatively, for example, as a method for joining multiple thin-plate honeycomb meshes 110 to each other, diffusion bonding (including vacuum diffusion bonding or argon diffusion bonding) can be performed. In this case, the manufacturer uses a diffusion bonding device (not shown) to pressurize and heat (hot press) the multiple thin-plate honeycomb meshes 110 after lamination. Thereby, the metal atoms at the interface between the mutually laminated thin-plate honeycomb meshes 110 will mix with each other through diffusion, causing the voids to gradually disappear, and new metal atom grains (bonding portions 106) will be formed across the interface to bond the thin-plate honeycomb meshes 110 to each other.

[0059] The exhaust mesh 100 manufactured by the above manufacturing method will become a thick plate of a perfect honeycomb structure 104 without burrs or steps. That is, after the plate processing and bonding processes, each through hole 103 of the exhaust mesh 100 will be smoothly continuous along the thickness direction of the exhaust mesh 100 (the lamination direction of the multiple thin plate honeycomb meshes 110) to maintain a high opening ratio of the multiple thin plate honeycomb meshes 110. Therefore, the exhaust mesh 100 can stably allow gas to pass through the thickness direction and can suppress abnormal plasma discharge by means of an appropriate thickness T.

[0060] Figure 6 is an explanatory diagram showing the experimental results confirming the exhaust performance of the exhaust network. The graph shown in Figure 6(a) shows the exhaust performance of the exhaust network when the pressure inside the processing container 10 is adjusted to 10 mT (1.33 Pa). The horizontal axis represents the opening degree of the APC valve 73, and the vertical axis represents the oxygen supply flow rate [slm] supplied to the processing container 10 by the mass flow controller 26. That is, when the pressure inside the processing container 10 is adjusted to 10 mT, the change in the gas supply flow rate to the processing container 10 is equivalent to the exhaust volume of gas discharged from the processing container 10 to the exhaust section 70.

[0061] Furthermore, in the graph of Figure 6(a), the flow rate change is shown by solid lines when using the exhaust net 100 with a honeycomb structure 104 (hereinafter referred to as honeycomb exhaust net A) related to this embodiment. In addition, the flow rate change is shown by dashed lines when using the exhaust net with multiple circular holes 130 (hereinafter referred to as circular hole exhaust net B) related to the prior art comparative example. Figure 6(b) is an enlarged top view illustrating the honeycomb exhaust net A used in the experiment. Figure 6(c) is an enlarged top view illustrating the circular hole exhaust net B used in the experiment.

[0062] The size of each through hole 103 in the honeycomb exhaust mesh A (the distance D between a pair of hole edges 105) is 4.77 mm as described above, and the overall opening ratio of the honeycomb exhaust mesh A is 85.1%. In contrast, although the diameter of each round hole 130 in the round hole exhaust mesh B is 5 mm, the overall opening ratio of the round hole exhaust mesh B is 62.9%. The diameter (outer diameter) of both the honeycomb exhaust mesh A and the round hole exhaust mesh B is 350 mm. The thickness of the honeycomb exhaust mesh A is 3 mm, and the thickness of the round hole exhaust mesh B is 2 mm.

[0063] As shown in Figure 6(a), both the honeycomb exhaust mesh A and the perforated exhaust mesh B increase the gas supply flow rate to the processing container 10 as the opening degree of the APC valve 73 increases. That is, since the pressure inside the processing container 10 is constant, an increase in gas supply flow rate means an increase in exhaust volume. Specifically, the larger the opening degree of the APC valve 73, the greater the gas supply flow rate will be for the honeycomb exhaust mesh A compared to the perforated exhaust mesh B. For example, when the opening degree of the APC valve 73 is 400°, the supply flow rate of the honeycomb exhaust mesh A will be 4.8 slm compared to the 4.55 slm of the perforated exhaust mesh B. In other words, the honeycomb exhaust mesh A can discharge more gas from the processing container 10 to the exhaust section 70 than the perforated exhaust mesh B; therefore, the exhaust performance of the honeycomb exhaust mesh A is superior to that of the perforated exhaust mesh B. Furthermore, although there were aspects in the experiment that could not be directly compared due to manufacturing limitations of each exhaust mesh, ultimately, considering the configuration of the hexagonal through holes 103 and the circular holes 130, the following conclusions can be drawn: In the case of the hexagonal through holes 103, if the distance between the through holes 103 is close to 0, the opening ratio will approach 100%. On the other hand, in the case of the circular holes 130, if the distance between the circular holes 130 is close to 0, there will be gaps between the openings of the three circular holes 130, and the limit of the opening ratio will be approximately 93%. Therefore, it can be concluded that the honeycomb exhaust mesh A has a superior opening ratio compared to the circular hole exhaust mesh B.

[0064] Figure 7 is a table showing the discharge stability of pressure changes and plasma output changes within the processing container 10. Additionally, Figure 7(a) shows the case using an exhaust net 100 with a honeycomb structure 104 (honeycomb exhaust net A) related to this embodiment, and Figure 7(b) shows the case using an exhaust net with multiple circular holes 130 (circular hole exhaust net B) related to a comparative example. Discharge stability is determined by visually observing the abnormal discharge generation of the multiple through holes 103 or multiple circular holes 130. Specifically, if no plasma-induced luminescence is generated in each through hole 103 or each circular hole 130, it is determined to have discharge stability and is marked OK. If plasma-induced luminescence is generated in the through holes 103 or circular holes 130, it is determined to have no discharge stability and is marked NG.

[0065] As shown in Figure 7(b), the perforated exhaust screen B exhibits discharge stability when the pressure of the processing container 10 is below 15 mT (2.00 Pa). On the other hand, the perforated exhaust screen B does not exhibit discharge stability when the pressure of the processing container 10 is 20 mT (2.67 Pa) and the plasma output (high-frequency power) is 11.1 kW or more. Furthermore, when the pressure of the processing container 10 is between 25 mT (3.33 Pa) and 35 mT (4.67 Pa), the perforated exhaust screen B will generate abnormal discharge when the plasma output is 5.5 kW or more. Moreover, when the pressure of the processing container 10 is 40 mT (5.33 Pa), the perforated exhaust screen B exhibits no discharge stability regardless of the plasma output.

[0066] In contrast, as shown in Figure 7(a), the honeycomb exhaust mesh A system does not generate abnormal discharge when the pressure of the processing container 10 is below 20 mT (2.67 Pa). Furthermore, the honeycomb exhaust mesh A system lacks discharge stability when the pressure of the processing container 10 is 25 mT (3.33 Pa) and the plasma output (high-frequency power) is 18.0 kW or more. Additionally, the honeycomb exhaust mesh A system lacks discharge stability when the pressure of the processing container 10 is 30 mT (4.00 Pa) and the plasma output is 8.3 kW or more. Moreover, when the pressure of the processing container 10 is between 35 mT (4.67 Pa) and 40 mT (5.33 Pa), the honeycomb exhaust mesh A system lacks discharge stability if the plasma output is 5.5 kW or more. Therefore, the honeycomb exhaust mesh A system achieves discharge stability even at low plasma output when the pressure of the processing container 10 is 40 mT (5.33 Pa).

[0067] As shown in Figures 7(a) and 7(b), the honeycomb exhaust mesh A is more likely to achieve discharge stability than the round hole exhaust mesh B, thus expanding the discharge stability region. In other words, from the perspective of discharge stability, the honeycomb exhaust mesh A is superior to the round hole exhaust mesh B.

[0068] As described above, the manufacturing method of the exhaust mesh 100 disclosed herein can form a honeycomb structure 104 in which multiple hexagonal through holes 103 are arranged with high precision. Furthermore, since the opening ratio of the exhaust mesh 100 is significantly increased by the honeycomb structure 104, the exhaust performance of the exhaust mesh 100 when venting gas is improved. In addition, in the manufacturing method of the exhaust mesh 100, multiple thin-plate honeycomb meshes 110 are joined together to thicken them. This allows the exhaust mesh 100 to reduce abnormal plasma discharge and further improve discharge stability. In other words, the exhaust mesh 100 can improve both exhaust performance and discharge stability.

[0069] In addition, the opening ratio of the honeycomb structure 104 of the exhaust mesh 100 is 85% or more. As a result, the exhaust mesh 100 can further improve the exhaust performance.

[0070] In addition, the spacing between adjacent through holes 103 is in the range of 0.3mm to 0.4mm. As a result, the width We of the hole edge 105 extending between the multiple through holes 103 in the exhaust mesh 100 will be narrowed, making it easier to further increase the opening ratio.

[0071] Furthermore, the spacing D between a pair of hole edges 105 extending parallel to each other with multiple through holes 103 is in the range of 1.4 to 2.0 times the thickness T of the exhaust mesh 100. This allows the exhaust mesh 100 to increase the size of the multiple through holes 103 to improve exhaust performance, while simultaneously obtaining sufficient length of the through holes 103 along the thickness direction to improve discharge stability.

[0072] In addition, in the bonding process, multiple thin-plate honeycomb meshes 110 are bonded together by diffusion bonding. In this way, the method for manufacturing exhaust mesh 100 can stably produce exhaust mesh 100 that can firmly fix multiple thin-plate honeycomb meshes 110 together and suppress burrs or streaks.

[0073] In addition, during the plate processing step, multiple through holes 103 are formed by wet etching of each of the multiple metal plates 120 through multiple honeycomb masks. In this way, the method for manufacturing the exhaust mesh 100 can efficiently and with high precision form the thin plate honeycomb mesh 110.

[0074] Furthermore, the plasma processing apparatus 1 disclosed herein, which performs plasma processing on a substrate G, includes: a processing container 10, which has a stage (base 40) for holding the substrate G; an exhaust pipe 71 connected to an exhaust port 14b provided in the processing container 10; an exhaust mechanism 72 provided in the exhaust pipe 71 for venting gas from the processing container 10; and an exhaust screen 100 provided through the exhaust port 14b between the base 40 and the exhaust mechanism 72 of the exhaust pipe 71; the exhaust screen 100 has a honeycomb structure 104 that causes multiple hexagonal through holes 103 to be adjacent, and is thickened by having a configuration that joins multiple thin-plate honeycomb meshes 110 in the thickness direction. In this way, the plasma processing apparatus 1 can improve venting performance and discharge stability.

[0075] In addition, the exhaust mesh 100 has a configuration in which multiple thin-plate honeycomb meshes 110 are joined together by diffusion bonding. In this way, the exhaust mesh 100 with the joint portion 106 can suppress burrs or steps and simultaneously thicken the plate, so as to further improve exhaust performance and discharge stability.

[0076] Furthermore, the location where the exhaust screen 100 is provided is such that the exhaust port 14b is covered by the exhaust screen 100. By covering the exhaust port 14b with the exhaust screen 100, the plasma treatment device 1 can effectively suppress the infiltration of plasma into the exhaust pipe 71 connected downstream of the exhaust screen 100.

[0077] Furthermore, the exhaust mesh 100 disclosed herein is provided in a plasma processing apparatus 1 that performs plasma processing on a substrate G. It has a honeycomb structure 104 in which multiple hexagonal through holes 103 are adjacent, and is thickened by having a configuration that joins multiple thin-plate honeycomb meshes 110 in the thickness direction. In this way, the exhaust mesh 100 can improve the exhaust performance and discharge stability of the plasma processing apparatus 1.

[0078] In addition, the exhaust mesh 100 has a structure in which multiple thin-plate honeycomb meshes 110 are joined together by diffusion bonding. In this way, the exhaust mesh 100 can suppress burrs or streaks and be thickened at the same time.

[0079] The manufacturing method of the exhaust screen 100, the plasma treatment apparatus 1, and the exhaust screen 100 disclosed herein are exemplary in all respects and not intended to limit the scope of the patent application. The embodiments can be modified and improved in various forms without departing from the scope and spirit of the patent application. The matters described in the aforementioned embodiments can also be configured in other ways without contradiction, and can be combined without contradiction.

[0080] The plasma processing apparatus 1 disclosed herein can also be used with any type of apparatus, including PE-ALD (Plasma Enhanced Atomic Layer Deposition), PE-CVD (Plasma Enhanced Chemical Vapor Deposition), and dry etching. Examples of objects subjected to plasma processing by the plasma processing apparatus 1 include, for example, a 1.5m × 1.85m substrate of G6 and other rectangular substrates of other sizes, but it is not limited to these; various components such as disk-shaped wafers can also be used as objects. [Simplified Explanation of the Diagram]

[0008] Figure 1 is a cross-sectional schematic diagram showing an example of a plasma treatment apparatus related to an embodiment. Figure 2 is an enlarged cross-sectional schematic diagram showing the portion from which gas is discharged from the treatment container of Figure 1. Figure 3 is a perspective view showing an exhaust screen related to an embodiment. Figure 4 is an enlarged explanatory diagram of the honeycomb structure of an exhaust screen related to an embodiment. Figure 5 is a process explanatory diagram showing the manufacturing method of an exhaust screen related to an embodiment. Figure 6 is an explanatory diagram showing the experimental results confirming the exhaust performance of an exhaust screen related to an embodiment. Figure 7 is a table showing the discharge stability of pressure changes and plasma output changes within the treatment container related to an embodiment.

Claims

1. A method for manufacturing an exhaust screen, the exhaust screen being used to pass through gas when it is discharged from a processing container of a plasma processing apparatus; the exhaust screen is made of stainless steel and grounded through at least one of a lower chamber of the processing container having an exhaust port and an exhaust pipe connected to the exhaust port; the method for manufacturing the exhaust screen includes: (a) a step of preparing a plurality of metal plates; (b) a step of forming a honeycomb structure in each of the plurality of metal plates with a plurality of hexagonal through holes adjacent to each other at intervals ranging from 0.3 mm to 0.4 mm to obtain a plurality of thin-plate honeycomb meshes; and (c) a step of laminating the plurality of thin-plate honeycomb meshes so that the plurality of through holes of the plurality of thin-plate honeycomb meshes are interconnected, and a step of joining the plurality of thin-plate honeycomb meshes together to produce the thickened exhaust screen.

2. The method for manufacturing an exhaust mesh as claimed in claim 1, wherein the opening ratio of the honeycomb structure of the exhaust mesh is 85% or more.

3. The method of manufacturing an exhaust mesh as claimed in claim 1 or 2, wherein the interval between a pair of hole edges extending in parallel with the plurality of through holes is in the range of 1.4 to 2.0 times the thickness of the exhaust mesh.

4. The method for manufacturing an exhaust mesh as claimed in claim 1 or 2, wherein in step (c), the plurality of thin-plate honeycomb meshes are joined together by diffusion bonding.

5. The method for manufacturing an exhaust mesh as claimed in claim 1 or 2, wherein in step (b), each of the plurality of metal plates is wet-etched through a plurality of honeycomb-shaped shields to form the plurality of through holes.

6. A plasma processing apparatus for plasma processing a substrate, comprising: a processing container having a stage for holding the substrate; an exhaust pipe connected to an exhaust port provided in the processing container; an exhaust mechanism provided in the exhaust pipe for discharging gas from the processing container; and an exhaust screen provided through the exhaust port at a position between the stage and the exhaust mechanism from the exhaust pipe; the exhaust screen being made of stainless steel and grounded through at least one of a lower chamber of the processing container having an exhaust port and an exhaust pipe connected to the exhaust port; the exhaust screen having a honeycomb structure in which a plurality of hexagonal through holes are adjacent to each other at intervals ranging from 0.3 mm to 0.4 mm, and being thickened by having a configuration that joins a plurality of thin-plate honeycomb meshes in the thickness direction.

7. The plasma processing apparatus of claim 6, wherein the exhaust mesh has a configuration that joins the plurality of thin-plate honeycomb meshes together by diffusion bonding.

8. The plasma processing apparatus of claim 6 or 7, wherein the location of the exhaust screen is such that the exhaust screen covers the location of the exhaust port.

9. An exhaust mesh is provided in a plasma processing apparatus having a processing container for performing plasma processing on a substrate; the exhaust mesh is formed of stainless steel and is grounded through at least one of a lower chamber having an exhaust port in the processing container and an exhaust pipe connected to the exhaust port; the exhaust mesh has a honeycomb structure in which a plurality of hexagonal through holes are adjacent to each other at intervals ranging from 0.3 mm to 0.4 mm, and is thickened by having a configuration that joins a plurality of thin-plate honeycomb meshes in the thickness direction.

10. The exhaust mesh of claim 9, wherein the exhaust mesh has a configuration that allows the plurality of thin-plate honeycomb meshes to be joined together by diffusion bonding.

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