Electrode plate for plasma processing equipment

Abstract

To provide an electrode plate for a plasma processing device that has gas holes with small roundness.SOLUTION: In an electrode plate for a plasma processing device 11, a plurality of gas holes 21 are provided through an electrode plate main body 12 in parallel to each other in the thickness direction, the gas hole 21 has a straight portion 22 with a length of at least more than 12 mm, and the straight portion 22 is open to the plasma side surface, and the diameter of the plasma side opening is 0.5 mm or more and 1.0 mm or less, and the circularity of the plasma side opening is 0.01 mm or less.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an electrode plate for a plasma processing apparatus. [Background technology]

[0002] In a plasma processing apparatus such as a plasma etching apparatus or a plasma CVD apparatus used in a semiconductor device manufacturing process, an upper electrode and a lower electrode connected to a high-frequency power source are arranged, for example, vertically facing each other in a chamber. The lower electrode has a substrate to be processed placed on it, and the upper electrode has an air hole through which an etching gas is passed toward the substrate to be processed while a high-frequency voltage is applied. In this way, the plasma processing apparatus generates plasma and performs processing such as etching on the substrate to be processed.

[0003] Patent Document 1 discloses an electrode plate for plasma etching that suppresses particle generation. This electrode plate for plasma etching has through holes (gas holes) that are parallel to the thickness direction of an electrode plate made of single crystal silicon. The through holes are composed of large-diameter straight hole portions and small-diameter straight hole portions. With this electrode plate, large particles are not generated, the number of cleaning operations can be reduced, and silicon wafers can be plasma etched more efficiently than before.

[0004] By the way, the thicker the electrode plate, the longer its lifespan. Recently, it has become necessary to etch deeply into the multi-layered complex three-dimensional structure of the substrate to be processed (e.g., 3D-NAND). To achieve this, the etching gas pressure must be increased. This causes the gas holes to wear out quickly, and the lifespan of electrode plates of conventional thicknesses is shortened. For this reason, thicker electrode plates are required to extend the lifespan. On the other hand, there are various methods for machining gas holes in electrode plates, including drilling, lasers, water jets, and electrical discharge machining, but laser machining can only drill holes to a depth of a few millimeters (approximately 5 mm). When machining holes using water jets, it is not possible to machine the opening of the gas hole into a good shape. Electrical discharge machining can only be used with materials that conduct electricity. In contrast, drilling is superior in terms of workability, versatility, and quality. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2001-102357 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, even with this drilling, if the depth is large, for example with a diameter of 0.5 mm to 1.0 mm, the drill may vibrate due to the processing load, causing the roundness of the gas hole to increase (deteriorate), which may degrade the quality of the plasma processing.

[0007] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an electrode plate for a plasma processing apparatus that is provided with gas holes having a small degree of roundness. [Means for solving the problem]

[0008] The method for manufacturing an electrode plate for a plasma processing apparatus of the present invention forms gas holes having straight portions each having a length of at least 12 mm in the thickness direction of the electrode plate body in a mutually parallel penetrating state, the method comprising the steps of: forming a pilot hole forming step of forming a pilot hole having a diameter of 50% to 80% of the diameter of the straight portion from one side of the electrode plate body with a first drill; and a straight portion forming step of forming the straight portion by overlapping the pilot hole with a second drill.

[0009] According to this method for manufacturing an electrode plate for a plasma processing apparatus, a pilot hole having a diameter of 50% to 80% of the diameter of the straight portion is formed by the first drill, and then the straight portion is formed by the second drill, so that the second drill performs hole processing with a small processing load, which is the original cutting area of ​​the entire straight portion minus the pilot hole cutting area. Since the processing load on the second drill is reduced, the processing accuracy of the second drill is improved and a straight portion with low roundness can be formed. In this case, if the diameter of the pilot hole is less than 50% of the diameter of the straight portion, the effect of reducing the processing load on the second drill is small, but if it exceeds 80%, the processing load on the first drill, which has a smaller diameter, becomes large, and there is a risk of the first drill breaking or being damaged.

[0010] However, as the drilling depth increases (the electrode plate becomes thicker), the drill becomes more susceptible to buckling because of the increased drilling load. For this reason, single crystal diamond drills, polycrystalline diamond drills, sintered drills, drills with oil inlets, and other drills that are strong against buckling and resistant to drilling loads are sometimes used, but the risk of drill breakage due to drilling loads can be avoided by using the following manufacturing method.

[0011] That is, in the manufacturing method of the present invention, the pilot hole forming step may preferably include forming a pilot hole to a partway through the thickness of the electrode plate body with the first drill. In this case, the pilot hole may preferably have a machining depth exceeding 5 mm.

[0012] According to this method for manufacturing an electrode plate for a plasma processing apparatus, before the gas holes are formed in the electrode plate body, pilot holes with an inner diameter of 50% to 80% of the inner diameter of the linear portion of the gas holes are drilled partway through the thickness direction. Since the pilot holes only need to be formed partway through the thickness direction of the electrode plate body, the first drill can be shorter than the thickness of the electrode plate body. In other words, even if the first drill for pilot holes has a small diameter, it is short and less likely to break. In this case, for a straight portion having a length exceeding 12 mm, the pilot hole should be formed to a length exceeding 5 mm, since a length of 5 mm or less would reduce the effect of reducing the machining load by the second drill.

[0013] On the other hand, the second drill has a larger diameter than the first drill, and drills a pilot hole made by the first drill, for example, coaxially from the same direction as the pilot hole. Here, the second drill drills a pilot hole coaxially with the pilot hole, thereby reducing the processing load corresponding to the pilot hole cutting area that has already been removed. Therefore, the second drill can drill a hole with a small processing load that is the original cutting area of ​​the entire straight section minus the pilot hole cutting area. Therefore, the second drill is less likely to buckle due to a cumulative increase in processing load. As a result, even if the second drill is longer than the first drill, the risk of breakage is reduced by the reduced processing load. It is preferable that the second drill be drilled coaxially with the pilot hole formed by the first drill, but a slight deviation within the difference in diameter between the two drills is permitted.

[0014] In the manufacturing method of the present invention, the second drill may drill holes from the one surface of the electrode plate body, or may drill holes from the other surface of the electrode plate body.

[0015] In this method for manufacturing an electrode plate for a plasma processing apparatus, when the second drill drills a hole from the other surface of the electrode plate body, the hole is drilled in the opposite direction to when the first drill formed the pilot hole. Even in this case, the second drill drills a hole approximately coaxially with the pilot hole, so that the processing load after reaching the pilot hole cutting area that has already been removed from one surface is reduced by an amount corresponding to the pilot hole cutting area, and the overall processing load is also reduced compared to drilling the entire original gas hole. Then, when the second drill reaches a predetermined depth from the other surface, it connects to the pilot hole formed from one surface. After this, the processing load of the second drill is reduced by an amount corresponding to the pilot hole cutting area.

[0016] Therefore, the second drill can perform hole drilling with a small processing load, which is the cutting area for the entire straight section minus the pilot hole cutting area, from the middle of the thickness direction (after reaching the pilot hole cutting area). Therefore, the processing load of the second drill is reduced from the middle of the thickness direction, making it less likely to buckle due to a cumulative increase in processing load. In other words, even if the second drill is longer than the first drill, the risk of breakage is reduced by the reduced processing load.

[0017] As a method for aligning the machining with the first drill and the machining with the second drill coaxially, a hole that is not a gas hole is used as a reference hole, its position information is set in the machining center (machine), and the machining positions of the first drill and the second drill are set to the same coordinates, which allows for coaxial machining. The same applies when the second drill drills a hole from the other side of the electrode plate body. Also, the first drill is generally replaced by the second drill automatically and coaxially using the auto-change function of the drill changer (drill and tool storage) of the machining center.

[0018] In the manufacturing method of the present invention, when drilling a hole from the other surface of the electrode plate body, the second drill may reach the pilot hole and form the straight portion halfway through the thickness of the electrode plate body.

[0019] The gas hole formed by this manufacturing method has a stepped hole shape with a small diameter hole that was a pilot hole on one side of the electrode plate body and a large diameter hole that becomes a straight part on the other side. In this case, too, the processing load of each drill can be reduced, and it can be applied to thick electrode plates.

[0020] The electrode plate for a plasma processing apparatus of the present invention is an electrode plate for a plasma processing apparatus having a plurality of gas holes formed parallel to each other in the thickness direction of the electrode plate body, the gas holes having at least a straight portion having a length of more than 12 mm, and the straight portion having a diameter of 0.5 mm or more and 1.0 mm or less and a circularity of 0.01 mm or less.

[0021] According to this electrode plate for plasma processing equipment, since the length of at least the straight portion exceeds 12 mm, the electrode plate body is formed with a thickness exceeding 12 mm, and the life can be extended. In addition, since the roundness of the straight portion is 0.01 mm or less, the gas flow is further prevented from becoming uneven.

[0022] In this electrode plate for a plasma processing apparatus, the gas hole has a small diameter portion opening on one side of the electrode plate body and a large diameter portion opening on the other side, which are connected midway through the thickness direction, and the large diameter portion can be considered to be the straight portion. Effect of the Invention

[0023] According to the manufacturing method of the electrode plate for plasma processing equipment of the present invention, even when gas holes are drilled in an electrode plate for plasma processing equipment having a thickness of more than 12 mm, the risk of drill breakage is reduced and high-precision gas holes can be formed. In addition, the electrode plate for plasma processing equipment can have a long life due to its thick electrode plate. Moreover, since the roundness of the straight portion is 0.01 mm or less, unevenness in the gas flow is further prevented. [Brief description of the drawings]

[0024] [Figure 1] 1 is a plan view of an electrode plate for a plasma processing apparatus according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a vertical cross-sectional view of the main part of FIG. [Diagram 3] FIG. 4 is a cross-sectional view showing a state in which pilot holes are formed in a pilot hole forming step in the manufacturing method according to the embodiment. [Figure 4] 10 is a cross-sectional view showing a state in which a straight portion is formed in the same direction as the pilot hole in a straight portion forming step after the pilot hole forming step. FIG. [Diagram 5] 11 is a cross-sectional view showing a state in which a straight portion is formed from the opposite direction to the pilot hole in a straight portion forming step after the pilot hole forming step. FIG. [Figure 6] FIG. 11 is a cross-sectional view showing an example in which a gas hole has a stepped shape formed by a pilot hole and a straight portion. [Figure 7]13 is a cross-sectional view showing a state in which a second drill is positioned to form a straight portion partway through the thickness direction of the electrode plate body after the pilot hole forming step. FIG. [Figure 8] 10 is a cross-sectional view showing a state in which a hole having a smaller diameter than the straight portion is formed by a third drill in a straight portion formed partway through the thickness direction of the electrode plate body. FIG. [Figure 9] 9 is a cross-sectional view showing a stepped gas hole formed by the method shown in FIG. 8. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a plan view of an electrode plate for a plasma processing apparatus according to an embodiment of the present invention. The electrode plate for plasma processing apparatus (hereinafter, also simply referred to as "electrode plate") 11 is formed of single crystal silicon, columnar crystal silicon, or polycrystalline silicon in a circular plate having a thickness t of more than 12 mm and not more than 30 mm, and a diameter of 200 mm to 550 mm, and has a plurality of gas holes 21 (in this case, several hundred to 1000, at least 100 or at least 500, etc.) formed at a pitch of several mm to 10 mm so as to penetrate the electrode plate body 12 in parallel in the thickness direction while being aligned, for example, vertically and horizontally. The gas holes 21 have a straight portion 22 having a length of at least more than 12 mm in the thickness direction of the electrode plate body 12. In the example shown in FIG. 2, the gas holes 21 are formed in a straight shape throughout the entire thickness of the electrode plate body 12. Therefore, the straight portion 22 in this embodiment constitutes the entire gas hole 21, and its length exceeds 12 mm. The straight portion 22 has a diameter d of 0.5 mm to 1.0 mm and a circularity of 0.01 mm or less.

[0026] This plasma processing apparatus electrode plate 11 is manufactured by forming gas holes in a disk-shaped electrode plate body 12 obtained by slicing a silicon ingot such as single crystal silicon, and then carrying out etching, polishing and other processes. In addition, the formation of the gas hole includes a pilot hole formation process in which a pilot hole 23 having a diameter of 50% to 80% of the diameter of the hole forming the straight portion 22 is formed from one side of the electrode plate body 12 using a first drill 31, and is formed halfway through the thickness of the electrode plate body 12, and a straight portion formation process in which the gas hole 21 is formed by forming the straight portion 22 overlapping the pilot hole 23 using a second drill 32.

[0027] These drills 31 and 32 can be sintered tungsten (W) drills, diamond particle electrodeposited drills, polycrystalline diamond drills, single crystal diamond drills, etc. As a result of selecting these drills, it was found that single crystal drills in particular were the most suitable because they caused the fewest breakages.

[0028] The gas hole forming process will be described in more detail. First, in the pilot hole forming process, pilot holes 23 having an inner diameter of 50% to 80% of the inner diameter of the straight portion 22 of the gas hole 21 are machined to the middle of the thickness of the electrode plate body 12. When the diameter of the straight portion 22 is 0.5 mm to 1.0 mm, the pilot holes 23 have a diameter of, for example, 0.3 mm to 0.8 mm. The pilot holes 23 are machined to the middle of the thickness of the electrode plate body 12 with the first drill 31, for example, to a depth L1 of about 8 mm. Therefore, the diameter d1 of the first drill 31 is smaller than the diameter of the straight portion 22. FIG. 3 shows a state in which the pilot holes 23 are machined with the first drill 31. When the pilot holes 23 are machined to a depth L1 of about 8 mm, the first drill 31 is removed from the pilot holes 23.

[0029] Next, in the straight portion forming process, straight portions 22 having a diameter of 0.5 mm to 1.0 mm larger than pilot holes 23 are machined with second drill 32 to penetrate electrode plate body 12. For example, straight portions 22 are formed to have a diameter approximately 0.2 mm (0.1 mm on each side) larger than pilot holes 23. Therefore, diameter d2 of second drill 32 is larger than diameter d1 of first drill 31. 3 and 4, the pilot hole cutting area 41 formed in the pilot hole forming step is shown by a solid line, and the straight portion cutting area 42 to be formed in the straight portion forming step is shown by a dashed line. In the example shown in these Figs. 3 and 4, the second drill 32 drills a hole coaxially with the pilot hole 23 from the same direction as the first drill 31 did when drilling the pilot hole 23. In this straight portion forming step, the second drill 32 drills a hole until it penetrates the electrode plate body 12. Therefore, the straight portion 22 is formed over the entire thickness of the electrode plate body 12.

[0030] In the above manufacturing method, before the gas holes 21 are formed in the electrode plate body 12, pilot holes 23 having an inner diameter of 50% to 80% of the inner diameter of the straight portions 22 of the gas holes 21 are formed partway through the thickness direction. Since it is sufficient that the pilot holes 23 are formed partway through the thickness direction of the electrode plate body 12, the first drill 31 may be shorter than the thickness of the electrode plate body 12. In other words, the first drill 31 for pilot holes has a small diameter but is short and therefore unlikely to break.

[0031] On the other hand, the second drill 32 is larger in diameter and longer than the first drill 31, and has a linear length exceeding at least 12 mm. The second drill 32 may be drilled from above the pilot hole 23 opened by the first drill 31 until it penetrates the electrode plate body 12 coaxially with the pilot hole 23. In other words, by drilling the hole coaxially with the pilot hole 23, the processing load corresponding to the pilot hole cutting area 41 that has already been removed is reduced. Therefore, the second drill 32 can drill the hole with a small processing load obtained by subtracting the pilot hole cutting area 41 from the cutting area of ​​the entire gas hole 21 (straight portion 22). Therefore, the second drill 32 is less likely to buckle due to a cumulative increase in the processing load. As a result, even if the second drill 32 is longer than the first drill 31, the risk of breakage is reduced by the amount of the reduced processing load. In this way, the first drill 31 and the second drill 32 have different drill diameters. Therefore, the gas hole 21 of the electrode plate body 12 is a hole formed by at least two drills (for example, the first drill 31 and the second drill 32) having different drill diameters. It is preferable that the second drill 32 is drilled coaxially with the pilot hole 23 formed by the first drill 31, but a slight deviation within the difference in diameter between the two drills 31, 32 is permitted.

[0032] In addition, the drilling depth of the pilot hole 23 by the first drill 31 is preferably more than 5 mm and less than 15 mm, while the length of the straight portion 22 is more than 12 mm and not more than 30 mm. If the drilling depth of the pilot hole 23 is shallow (5 mm or less), the processing load on the second drill 32 cannot be reduced, which may lead to breakage of the second drill 32 or a decrease in roundness. If the drilling depth of the pilot hole 23 is deep, the processing load on the first drill 31 increases, which may lead to breakage of the first drill 31. More preferably, the drilling depth is 7 mm or more and 13 mm or less. Therefore, if the thickness of the electrode plate body 12 is less than 15 mm, preferably 13 mm or less, the pilot hole 23 by the first drill 31 may be formed to penetrate the electrode plate body 12.

[0033] In the electrode plate 11 obtained by this manufacturing method, the gas hole 21 has a straight portion 22 whose length is at least more than 12 mm. In the example shown in Fig. 2, the entire gas hole 21 is a straight portion 22. The straight portion 22 has a diameter of 0.5 mm or more and 1.0 mm or less, and a circularity of 0.01 mm or less.

[0034] According to this electrode plate 11, since at least the length of the straight portion 22 exceeds 12 mm, the electrode plate body 12 is formed with a thickness exceeding 12 mm, and the life of the electrode plate 11 can be extended. In addition, since the roundness of the straight portion 22 is 0.01 mm or less, the gas flow is further prevented from becoming uneven.

[0035] By the way, when drilling holes using two drills, the following method can be considered. (1) The outer diameter of two drills is set to the same diameter that can form the final gas hole, and the first drill is used to drill a hole halfway through the thickness of the electrode plate body, and then the second drill is used from above the hole to drill a second hole through the electrode plate body. (2) The outer diameter of two drills is set to the same diameter that can form the final gas hole, and the first drill is used to drill a hole partway through the thickness of the electrode plate body, and the tip of the second drill is inserted into the hole and a second drill is used to drill a hole through the electrode plate body. However, in the methods (1) and (2), a short drill can be used for the first hole drilling, so the risk of the drill breaking is small, but the position of the hole drilled in the first hole drilling and the hole drilled in the second hole drilling may be misaligned, causing distortion at the opening edge of the hole and reducing the roundness of the hole. In addition, the drill may vibrate during the second hole drilling, which may cause the drill to break.

[0036] In the present invention, the second drill 32 may be used to drill holes from the same direction as the first drill 31 that formed the pilot hole 23, as described above, or may be used to drill holes from the opposite side of the electrode plate body 12 from the first drill 31. FIG. 5 shows an example in which the second drill 32 for processing the straight portion 22 is formed from the opposite direction to the formation direction of the pilot hole 23. The first drill 31, as in FIG. 3, drills a hole from one surface of the electrode plate body 12 to the middle of the thickness direction to form the pilot hole 23. In contrast, the second drill 32 drills a hole from the other surface of the electrode plate body 12 (the surface opposite to the one surface, or the surface facing the one surface) until it penetrates the electrode plate body 12 coaxially with the pilot hole 23. As a result, the straight portion 22 penetrating the electrode plate body 12 is formed over the entire thickness of the electrode plate body 12. Therefore, the shape of the formed gas hole 21 is the same as that in the processing shown in FIG. 3 and FIG. 4, and is straight as shown in FIG. 2.

[0037] In the present invention, the straight portion 22 does not necessarily have to be formed to a length that penetrates the electrode plate body 12 . In Figure 6, as in Figure 5, a straight section 22 is formed on the opposite side of the electrode plate body 12 from the pilot hole 23, but this straight section 22 also extends to the middle of the thickness of the electrode plate body 12 at a depth L2 that reaches the tip of the pilot hole 23, thereby forming a stepped gas hole 211 that connects the pilot hole 23 and the straight section 22. In this case, the pilot hole 23 becomes a small diameter portion 24 formed from one surface side of the electrode plate body 12 to the middle in the thickness direction. The straight portion 22 becomes a large diameter portion 25 formed from the other surface side of the electrode plate body 12 to the middle in the thickness direction of the electrode plate body 12, coaxial with the small diameter portion 24, and communicating with the small diameter portion 24. As a result, a stepped gas hole 211 is formed in the electrode plate body 12, connecting the small diameter portion 24 and the large diameter portion 25.

[0038] The gas holes 21, 211 formed by the methods shown in Figures 3 to 6 above have straight portion 22 with a length of at least 12 mm, and the diameter of this straight portion 22 is 0.5 mm or more and 1.0 mm or less, and the circularity is 0.01 mm or less.

[0039] Furthermore, when forming a stepped gas hole, it may be formed by the method shown in FIGS. In the method of this example, first, a pilot hole cutting region 41 is formed from one side of the electrode plate body 12 to the middle in the thickness direction with a first drill 31 (not shown in Figs. 7 to 8, see Fig. 3), and a straight portion 22 is formed coaxially with the second drill 32 from the same direction as shown in Fig. 7 to the middle of the thickness of the electrode plate body 12 within a range of length L2 (see Fig. 8). Then, a hole is drilled coaxially with a third drill 33 from the other side of the electrode plate body 12 to a depth that reaches the straight portion cutting region 42, resulting in the state shown in Fig. 9. In the example shown in Figs. 7 to 9, since the diameter of the third drill 33 is smaller than the diameter of the second drill 32, the straight portion 22 is the large diameter portion 25, and the hole formed by the third drill 33 is the small diameter portion 24, and these become a stepped gas hole 212 that communicates with each other at a position in the thickness of the electrode plate body 12. In this case, the straight portion 22 is also formed to a length L2 exceeding 12 mm. Although not shown in the figure, the third drill 33 has a smaller diameter than the second drill 32. However, it is also possible to use a third drill having a larger diameter than the second drill 32 to machine a hole communicating with the straight portion 22, making the straight portion 22 a small diameter portion and the hole formed by the third drill 33 a large diameter portion. EXAMPLES

[0040] Samples were prepared using the following multiple types of hole drilling methods, and after drilling, a Mitutoyo Corporation three-dimensional image measuring device (Mitutoyo Corporation Quick Vision QVX606-PRO) was used to measure the hole diameter and roundness of the opening on the second drill inlet side by image processing, and the presence or absence of breakage of the drill during processing was also confirmed. Five tests were performed (five holes were drilled), and the average values ​​for hole diameter and roundness were calculated, and it was investigated how many drills broke during the five tests. If any drills were broken, they were excluded from the measurement samples.

[0041] [Example 1] A straight hole with a diameter of 0.8 mm is drilled through the 20 mm thick electrode plate body. (1) Conventional processing method A The holes were drilled at once from one side of the electrode plate body using a drill with a diameter of 0.8 mm and a cutting length of 20 mm. (2) Comparative example processing method A A drill with a diameter of 0.8 mm and a cutting length of 10 mm (first drill: in the comparative examples, the first drill is referred to as the first drill and the second drill is referred to as the second drill; similarly below) was used to drill a pilot hole 10 mm deep from one side of the electrode plate body, and then a drill with a diameter of 0.8 mm and a cutting length of 20 mm (second drill) was used to drill a hole 20 mm deep from one side of the electrode plate body to include the pilot hole, penetrating the electrode plate body. (3) Comparative example processing method B A pilot hole 10 mm deep was drilled from one side of the electrode body using a drill (first drill) with a diameter of 0.8 mm and a cutting length of 10 mm, and then the tip of a drill (second drill) with a diameter of 0.8 mm and a cutting length of 20 mm was inserted into the pilot hole and a hole 10 mm deep was drilled from the 10 mm deep position to penetrate the electrode plate body. (4) Example Processing Method A A pilot hole 10 mm deep was drilled from one side of the electrode plate body using a first drill with a diameter of 0.6 mm and a cutting length of 10 mm, and then a hole 20 mm deep was drilled from one side of the electrode plate body to include the pilot hole using a second drill with a diameter of 0.8 mm and a cutting length of 20 mm, penetrating the electrode plate body. These results are shown in Table 1. The evaluation of the drill breakage in the conventional example is shown in the column for the first drill (the same applies to Tables 2 and 3).

[0042] [Table 1]

[0043] In the case of conventional example A, the drill broke in all five tests, so the hole diameter and roundness were not measured. In both Comparative Examples A and B, the drill (second drill) broke in three out of five tests, the hole diameter had a large error from the target hole diameter, and the roundness was also poor. In contrast, in the case of the machining method of Example A, no breakage was observed in any of the drills, the error in the diameter of the drilled holes was small, and holes with small circularity could be drilled.

[0044] [Example 2] A straight hole with a diameter of 0.8 mm is drilled through the 30 mm thick electrode plate body. (1) Conventional processing method B The holes were drilled at once from one side of the electrode plate body using a drill with a diameter of 0.8 mm and a cutting length of 30 mm. (2) Comparative example processing method C A pilot hole 10 mm deep was drilled from one side of the electrode plate body using a drill (first drill) with a diameter of 0.8 mm and a cutting length of 10 mm, and then a hole 30 mm deep was drilled from one side of the electrode plate body using a drill (second drill) with a diameter of 0.8 mm and a cutting length of 30 mm to include the pilot hole and penetrate the electrode plate body. (3) Comparative example processing method D A pilot hole 10 mm deep was drilled from one side of the electrode body using a drill (first drill) with a diameter of 0.8 mm and a cutting length of 10 mm, and then the tip of a drill (second drill) with a diameter of 0.8 mm and a cutting length of 30 mm was inserted into the pilot hole and a hole 20 mm deep was drilled from the 10 mm deep position to penetrate the electrode plate body. (4) Example Processing Method B A pilot hole 10 mm deep was drilled from one side of the electrode plate body using a first drill with a diameter of 0.6 mm and a cutting length of 10 mm, and then a hole 30 mm deep was drilled from one side of the electrode plate body to include the pilot hole using a second drill with a diameter of 0.8 mm and a cutting length of 30 mm, penetrating the electrode plate body. The results are shown in Table 2.

[0045] [Table 2]

[0046] In the conventional example B, the drill broke in all five tests, and in the comparative examples C and D, the second drill broke in all five tests, so that the hole diameter and roundness were not measured. In the processing method of Example B, no breakage was observed in any of the drills, the error in the diameter of the holes was small, and holes with small circularity could be processed. Thus, the method of the present invention is also effective in processing a gas hole with a straight portion of 30 mm in length.

[0047] [Example 3] A straight hole with a diameter of 0.8 mm is drilled through the 13 mm thick electrode plate body. (1) Conventional processing method C The holes were drilled at once from one side of the electrode plate body using a drill with a diameter of 0.8 mm and a cutting length of 13 mm. (2) Comparative example processing method E A pilot hole 10 mm deep was drilled from one side of the electrode plate body using a drill (first drill) with a diameter of 0.8 mm and a cutting length of 10 mm, and then a hole 13 mm deep was drilled from one side of the electrode plate body using a drill (second drill) with a diameter of 0.8 mm and a cutting length of 13 mm to include the pilot hole and penetrate the electrode plate body. (3) Comparative example processing method F A pilot hole 10 mm deep was drilled from one side of the electrode body using a drill (first drill) with a diameter of 0.8 mm and a cutting length of 10 mm, and then the tip of a drill (second drill) with a diameter of 0.8 mm and a cutting length of 13 mm was inserted into the pilot hole and a hole 3 mm deep was drilled from the 10 mm deep position to penetrate the electrode plate body. (4) Example Processing Method C A pilot hole 10 mm deep was drilled from one side of the electrode plate body using a first drill with a diameter of 0.6 mm and a cutting length of 10 mm, and then a hole 13 mm deep was drilled from one side of the electrode plate body to include the pilot hole using a second drill with a diameter of 0.8 mm and a cutting length of 13 mm, penetrating the electrode plate body. (5) Example Processing Method D A pilot hole (through hole) 13 mm deep was drilled from one side of the electrode plate body using a first drill with a diameter of 0.6 mm and a cutting length of 13 mm, and then a hole 13 mm deep was drilled from one side of the electrode plate body to include the pilot hole using a second drill with a diameter of 0.8 mm and a cutting length of 13 mm, to prepare the electrode plate body. The results are shown in Table 3.

[0048] [Table 3]

[0049] In the conventional example, the drill broke in three out of five tests, and in comparative examples E and F, the second drill broke in one out of five tests, but because the hole drilling depth was smaller than in examples 1 and 2, there was little drill breakage and some holes were drilled, but the holes formed had a large error in hole diameter and were not of satisfactory roundness. In addition, the hole drilling with the second drill in comparative example F was thought to be a small load at a depth of 3 mm, but it was prone to vibration in the hole made in the first pass, so it broke in one out of five tests. In Example C, none of the drills were broken, the hole diameter error was small, and the roundness was also small. In Example D, breakage of the first drill was observed in two of the five tests, but the error in the hole diameter was small and the roundness was also small.

[0050] As is clear from the above examples, according to the manufacturing method of the present invention, even if the electrode plate body is thick, it is possible to form a straight hole with a length of more than 12 mm with high precision (small circularity). [Explanation of symbols]

[0051] 11 Electrode plate (electrode plate for plasma processing device) 12 Electrode plate body 21,211,212 Gas hole 22 Straight section 23 Pilot hole 24 Small diameter section 25 Large diameter section 31 First Drill 32 2nd Drill 41 Pilot hole drilling area 42 Straight line cutting area

Claims

1. An electrode plate for a plasma processing apparatus, comprising an electrode plate body made of single crystal silicon, columnar crystal silicon, or polycrystalline silicon, and a plurality of gas holes extending parallel to each other in the thickness direction of the electrode plate body, The gas hole is a straight portion formed in a straight shape across the entire thickness of the electrode plate body, the straight portion having a length of at least 12 mm, the diameter of the opening on the plasma side being 0.5 mm or more and 1.0 mm or less, and the circularity of the opening on the plasma side being 0.01 mm or less.

2. An electrode plate for a plasma processing apparatus, comprising an electrode plate body made of single crystal silicon, columnar crystal silicon, or polycrystalline silicon, and a plurality of gas holes extending parallel to each other in the thickness direction of the electrode plate body, the gas hole has a small diameter portion opening on one side of the electrode plate body and a large diameter portion opening on the other plasma side surface, the small diameter portion being connected midway through the thickness direction, the large diameter portion being a straight portion having a length of at least 12 mm, the straight portion opening on the plasma side surface, the diameter of the plasma side opening being 0.5 mm or more and 1.0 mm or less, and the circularity of the plasma side opening being 0.01 mm or less.

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