Outer ring set and plasma processing apparatus

Abstract

To suppress wear on the outer ring and ensure stable plasma containment over a long period. [Solution] The outer ring set of the embodiment is an outer ring set used in a plasma processing apparatus for processing a substrate, and comprises a first outer ring having a first annular portion having a plurality of first slits, a second annular portion facing the first annular portion at a predetermined distance apart, and a wall portion connecting the outer edge of the first annular portion and the outer edge of the second annular portion, and a second outer ring arranged on the surface of the first annular portion facing the second annular portion and having a plurality of second slits at a position that overlaps the plurality of first slits in the vertical direction.

Description

Technical Field

[0001] Embodiments of the present invention relate to an outer peripheral ring set and a plasma processing apparatus.

Background Art

[0002] In a plasma processing apparatus for processing a substrate, a mechanism for confining plasma may be used in the vicinity of the substrate. The plasma confinement mechanism is configured to include, for example, an outer peripheral ring having a plurality of slits and surrounding the outer periphery of the substrate, and an adjustment plate facing the outer peripheral ring and having an adjustable separation distance from the outer peripheral ring.

[0003] However, as the plasma processing time elapses, the outer peripheral ring may be consumed, the opening areas of the plurality of slits may expand, and it may become difficult to confine the plasma.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0005] One embodiment aims to provide an outer peripheral ring set and a plasma processing apparatus that can suppress the consumption of the outer peripheral ring and stably confine plasma over a long period.

Means for Solving the Problems

[0006] The outer ring set of the embodiment is an outer ring set used in a plasma processing apparatus for processing a substrate, and comprises a first outer ring having a first annular portion having a plurality of first slits, a second annular portion facing the first annular portion at a predetermined distance apart, and a wall portion connecting the outer edge of the first annular portion and the outer edge of the second annular portion, and a second outer ring arranged on the surface of the first annular portion facing the second annular portion and having a plurality of second slits at a position that overlaps the plurality of first slits in the vertical direction. [Brief explanation of the drawing]

[0007] [Figure 1] A schematic cross-sectional view showing an example of the configuration of a plasma processing apparatus according to Embodiment 1. [Figure 2] A schematic diagram showing an example of the configuration of the outer ring according to Embodiment 1. [Figure 3] A perspective cross-sectional view showing the outer rings of Embodiment 1 stacked on top of each other. [Figure 4] A schematic cross-sectional view of one side of the outer ring according to Embodiment 1. [Figure 5] A schematic diagram showing an example of the configuration of the outer ring according to a modified example of Embodiment 1. [Figure 6] A schematic diagram showing another example of the configuration of the outer ring according to a modification of Embodiment 1. [Figure 7] A schematic diagram showing yet another example of the configuration of the outer ring according to a modification of Embodiment 1. [Figure 8] A schematic cross-sectional view showing an example of the configuration of a plasma processing apparatus according to Embodiment 2. [Figure 9] A schematic diagram showing an example of the configuration of the outer ring according to Embodiment 2. [Figure 10] A schematic diagram showing an example of the configuration of the outer ring according to Embodiment 2. [Figure 11] A top view showing the overall configuration of the outer ring according to Embodiment 2 after a predetermined usage time has elapsed. [Figure 12] A cross-sectional view of one side of the outer ring according to Embodiment 2 after a predetermined usage time has elapsed. [Figure 13] Top view showing the overall configuration of the outer peripheral ring according to Embodiment 2 after a predetermined usage time has elapsed. [Figure 14] Top view showing how the outer peripheral ring according to Embodiment 2 is overlapped after changing the angle after a predetermined usage time has elapsed. [Figure 15] Cross-sectional view of one side surface after reattachment of the outer peripheral ring according to Embodiment 2. [Figure 16] Flow chart showing an example of the plasma processing procedure in the plasma processing apparatus according to Embodiment 2.

Mode for Carrying Out the Invention

[0008] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited by the following embodiments. Also, the components in the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same.

[0009] [Embodiment 1] Hereinafter, Embodiment 1 will be described in detail with reference to the drawings.

[0010] (Configuration Example of Plasma Processing Apparatus) FIG. 1 is a cross-sectional view schematically showing an example of the configuration of a plasma processing apparatus 1 according to Embodiment 1. The plasma processing apparatus 1 is configured as, for example, a RIE (Reactive Ion Etching) apparatus that performs plasma etching on a wafer 10 as a substrate.

[0011] As shown in FIG. 1, the plasma processing apparatus 1 includes a processing container 11 in which the wafer 10 is processed. The processing container 11 is made of, for example, aluminum and can be hermetically sealed.

[0012] Near the upper part of the processing container 11, a gas supply port 13 is provided. A gas supply device (not shown) is connected to the gas supply port 13 through a pipe, and a processing gas used during plasma processing is supplied.

[0013] A showerhead 30, which functions as an upper electrode, is provided near the top of the processing container 11 and below the gas supply port 13. The showerhead 30 is provided with multiple gas flow channels 32 that penetrate in the thickness direction of the plate. The processing gas supplied from the gas supply port 13 is introduced into the processing container 11 via the gas flow channels 32.

[0014] Below the shower head 30, a wafer stage 20 is positioned opposite the shower head 30. The wafer stage 20 horizontally supports the wafer 10 to be processed and also functions as a lower electrode.

[0015] The wafer stage 20 is supported on a support portion 12 that protrudes vertically upward in a cylindrical shape from the bottom wall near the center of the processing container 11. The support portion 12 supports the wafer stage 20 so as to be parallel to and opposite the shower head 30. Furthermore, the support portion 12 supports the wafer stage 20 so as to be located near the center of the processing container 11, at a predetermined distance from the shower head 30. With this structure, the shower head 30 and the wafer stage 20 constitute a pair of parallel plate electrodes.

[0016] A power supply line 41 that supplies high-frequency power is connected to the wafer stage 20. A blocking capacitor 42, a matching circuit 43, and a high-frequency power supply 44 are connected to the power supply line 41. During plasma processing, high-frequency power of a predetermined frequency is supplied from the high-frequency power supply 44 to the wafer stage 20. With this configuration, the plasma processing apparatus 1 is configured, for example, as a bottom-applied plasma processing apparatus.

[0017] However, the plasma processing apparatus 1 may be configured as an upper-applied plasma processing apparatus by connecting a power supply line 41 having a blocking capacitor 42, a matching circuit 43, and a high-frequency power supply 44, etc., to a shower head 30 that functions as an upper electrode.

[0018] Alternatively, the plasma processing apparatus 1 may be configured as an upper and lower plasma processing apparatus by connecting a power supply line 41 having a blocking capacitor 42, a matching circuit 43, and a high-frequency power supply 44, etc., to both the wafer stage 20 and the shower head 30.

[0019] Furthermore, the wafer stage 20 is equipped with a chuck mechanism for electrostatically adsorbing the wafer 10, and also functions as an electrostatic chuck for electrostatically adsorbing the wafer 10.

[0020] The chuck mechanism comprises a chuck electrode 23, a power supply line 45, and a power supply 46. The chuck electrode 23 is built into the wafer stage 20, and the power supply 46 is connected to the chuck electrode 23 via the power supply line 45. With this mechanism, DC power is supplied from the power supply 46 to the chuck electrode 23, the upper surface of the wafer stage 20 is electrostatically charged, and the wafer 10 is attracted to it.

[0021] A focus ring 21 is positioned at the periphery of the wafer stage 20, covering the sides and periphery of the wafer stage 20. The focus ring 21 adjusts the electric field during etching of the wafer 10 so that the electric field at the periphery of the wafer 10 is not deflected in the vertical direction perpendicular to the wafer surface.

[0022] Outer rings 51 and 52 are provided between the focus ring 21 and the side wall of the processing container 11. Outer ring 51 has a C-shaped cross-section on one side when viewed from the side, bulging from the outer edge of the shower head 30 toward the side wall of the processing container 11. Multiple slits are provided in the C-shaped bottom portion of outer ring 51. Outer ring 52 is an annular flat plate with multiple slits and is placed on the C-shaped bottom portion of outer ring 51.

[0023] As a result, the outer ring 52 functions as a protective member that protects the slit portion of the outer ring 51. The detailed configuration of the outer rings 51 and 52 will be described later.

[0024] A pressure gauge 71 capable of measuring the pressure in a C-shaped space surrounded by an outer ring 52 is provided near the top of the processing container 11.

[0025] Below the outer rings 51 and 52, an adjustment plate 53 is provided so as to face the C-shaped bottom portion of the outer ring 51. The adjustment plate 53 is configured to move up and down by a motor (not shown) or the like in response to the pressure in the C-shaped space of the outer ring 52, as measured by the pressure gauge 71.

[0026] The plasma containment mechanism 50 is composed of outer rings 51 and 52, an adjustment plate 53, and a motor (not shown) for moving the adjustment plate 53 up and down. The configuration including the outer rings 51 and 52 is sometimes called the outer ring set. These outer rings 51 and 52 and the adjustment plate 53 included in the plasma containment mechanism 50 are made of, for example, silicon.

[0027] However, the outer rings 51, 52 and the adjustment plate 53 may be made of silicon carbide, glassy carbon, tungsten, aluminum, etc., and if they are made of metal such as tungsten or aluminum, they may have a coating of these metal oxides, or they may be ceramics of these metals.

[0028] A gas exhaust port 14 is provided in the processing container 11 located further below the adjustment plate 53. A vacuum pump 72 is connected to the gas exhaust port 14. The configuration including the gas exhaust port 14 and the vacuum pump 72 is sometimes referred to as the exhaust section that exhausts the atmosphere inside the processing container 11.

[0029] During plasma processing of the wafer 10, the wafer 10 to be processed is placed on the wafer stage 20. A vacuum pump 72 connected to the gas exhaust port 14 evacuates the inside of the processing container 11 via outer rings 51 and 52, each having multiple slits. When the inside of the processing container 11 reaches a predetermined pressure, processing gas is supplied from a gas supply device (not shown) to the wafer 10 on the wafer stage 20 via the gas flow path 32 of the showerhead 30.

[0030] In the bottom-applied type apparatus, with the upper electrode, the showerhead 30, grounded, a high-frequency voltage is applied to the lower electrode, the wafer stage 20, to generate plasma in the space between the showerhead 30 and the wafer stage 20. Due to the self-bias caused by the high-frequency voltage on the lower electrode side, a potential gradient is created between the plasma and the wafer 10, and ions in the plasma are accelerated toward the wafer stage 20, resulting in anisotropic etching.

[0031] During plasma processing, it is preferable that the plasma is generated between the showerhead 30 and the wafer stage 20, directly above the wafer 10. However, the plasma generated between the showerhead 30 and the wafer stage 20 tends to spread from the outer periphery of the wafer 10 into the C-shaped space of the outer ring 51.

[0032] The adjustment plate 53 is moved up and down based on the measurement results of the pressure gauge 71, adjusting the pressure in this C-shaped space to be constant. This suppresses the spread of plasma to the outer periphery of the wafer 10, and allows the plasma to be contained exclusively within the space between the shower head 30 and the wafer stage 20.

[0033] Furthermore, the smaller the distance between the adjustment plate 53 and the outer ring 52, the greater the plasma containment effect and the higher the plasma density. On the other hand, the larger the distance between the adjustment plate 53 and the outer ring 52, the weaker the plasma containment effect and the lower the plasma density tends to be.

[0034] The control unit 100 is configured as a computer equipped with a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), etc. (not shown).

[0035] However, the control unit 100 may be configured as an ASIC (Application Specific Integrated Circuit) or the like that has functions for use in the plasma processing apparatus 1.

[0036] The control unit 100 controls each part of the plasma processing apparatus 1. Specifically, the control unit 100 controls each part of the plasma processing apparatus 1, such as the wafer stage 20, high-frequency power supply 44, adjustment plate 53, gas supply device, and vacuum pump 72, to enable the plasma processing described above.

[0037] (Example of outer ring configuration) Next, using Figures 2 and 3, we will describe a detailed example of the configuration of the outer rings 51 and 52 included in the plasma containment mechanism 50.

[0038] Figure 2 is a schematic diagram showing an example of the configuration of the outer rings 51 and 52 according to Embodiment 1. More specifically, Figure 2(a) is a perspective cross-sectional view showing a part of the outer ring 51, and Figure 2(b) is a top view showing the overall configuration of the outer ring 52.

[0039] As shown in Figure 2(a), the outer ring 51 comprises annular portions 511 and 512, a wall portion 513, and a plurality of slits 514. Both annular portions 511 and 512 are circular and flat in shape, and are arranged to face each other at a predetermined distance apart. The wall portion 513 is arranged perpendicular to the annular portions 511 and 512, and connects the outer edges of these annular portions 511 and 512. As a result, the outer ring 51 as a whole is configured such that the cross-sectional shape of one side is C-shaped.

[0040] The annular portion 512 is installed in the processing container 11 of the plasma processing apparatus 1 so as to be located below the annular portion 511. The annular portion 512 also has a plurality of slits 514. The plurality of slits 514 penetrate the annular portion 512 in the thickness direction and are arranged radially toward the outer edge of the annular portion 512.

[0041] As shown in Figure 2(b), the outer ring 52 has a plurality of dividing members 522. These dividing members 522 may all have the same configuration, and each is configured to be both arc-shaped and flat. In addition, each dividing member 522 has a plurality of slits 524 that penetrate through the dividing member 522 in the thickness direction. When these dividing members 522 are combined with each other, they form an annular outer ring 52. When the dividing members 522 are combined in an annular shape, the plurality of slits 524 are arranged to extend radially toward the outer edge of the outer ring 52.

[0042] In the example shown in Figure 2(b), the outer ring 52 has four dividing members 522. However, the outer ring 52 is not limited to having four dividing members 522; it may have two, three, or five or more dividing members 522.

[0043] In this way, because the outer ring 52 is divided into multiple segmented members 522, each segmented member 522 can be inserted into the C-shaped space between the annular portions 511 and 512 of the outer ring 51 and positioned on the upper surface of the annular portion 511 of the outer ring 51.

[0044] Figure 3 is a perspective cross-sectional view showing the outer rings 51 and 52 according to Embodiment 1 superimposed on each other. Figure 3 shows a portion of the annular portion 512 of the outer ring 51 and a portion of the corresponding divided member 522 of the outer ring 52.

[0045] As shown in Figure 3, the multiple slits 514 in the annular portion 512 of the outer ring 51 and the multiple slits 524 in the dividing member 522 of the outer ring 52 correspond to each other one-to-one, and when the outer ring 52 is placed on the outer ring 51, they are arranged to overlap each other in the vertical direction. That is, the number of slits 514 in the outer ring 51 is equal to the total number of slits 524 in the outer ring 52.

[0046] In the plasma processing apparatus 1, the atmosphere inside the processing container 11 is exhausted through the overlapping slits 514 and 524 of the outer rings 51 and 52.

[0047] Figure 4 is a schematic cross-sectional view of one side of the outer rings 51 and 52 according to Embodiment 1. More specifically, Figures 4(a) and 4(b) show a cross-section of one side of the new outer rings 51 and 52 immediately after installation in the plasma processing apparatus 1, and a view of these outer rings 51 and 52 from below, respectively. Figures 4(c) and 4(d) show a cross-section of one side of the outer rings 51 and 52 after a predetermined usage time has elapsed, and a view of these outer rings 51 and 52 from below, respectively.

[0048] As shown in Figure 4(a), it is preferable that initially the slit 524 of the outer ring 52 has a smaller opening area than, for example, the slit 514 of the outer ring 51. In this case, as shown in Figure 4(b), when these outer rings 51 and 52 are viewed from below, the inner edge of the slit 524 of the outer ring 52 should appear to protrude from the opening of the slit 514 of the outer ring 51.

[0049] As shown in Figure 4(c), after a predetermined usage time, the outer ring 52 is worn down by the plasma, and the opening area of ​​the slit 524 becomes larger than it was initially. Therefore, as shown in Figure 4(d), when these outer rings 51 and 52 are viewed from below, the portion of the inner edge of the slit 524 of the outer ring 52 that protrudes from the opening of the slit 514 of the outer ring 51 becomes smaller.

[0050] However, at the timings shown in Figures 4(c) and 4(d), the outer ring 51 is protected by the outer ring 52 and does not experience plasma-induced wear. Thus, by positioning the outer ring 52, wear on the outer ring 51 can be suppressed.

[0051] Furthermore, if the outer ring 52 is replaced with a new one at the timing shown in Figure 4(c) and (d), before the opening area of ​​the slit 524 of the outer ring 52 exceeds the opening area of ​​the slit 514 of the outer ring 51, wear of the outer ring 51 due to plasma can be further suppressed.

[0052] (Overview) In plasma processing equipment, a C-shaped outer ring with a slit on its bottom surface and an adjustment plate that can adjust the distance from this outer ring are sometimes used to contain the spread of plasma around the outer edge of the wafer. However, when the outer ring is worn down by the plasma, the opening area of ​​the slit increases, reducing the plasma containment effect. This can cause fluctuations in the plasma processing characteristics of the wafer, leading to a decrease in the yield of semiconductor devices. Furthermore, in order to maintain the plasma containment effect, the outer ring must be replaced after a predetermined period of use, increasing the manufacturing cost of semiconductor devices.

[0053] According to the plasma processing apparatus 1 of Embodiment 1, the apparatus comprises an outer ring 51 having an annular portion 512 having a plurality of slits 514, an annular portion 511 facing the annular portion 512 at a predetermined distance, and a wall portion 513 connecting the outer edge of the annular portion 512 and the outer edge of the annular portion 511, and an outer ring 52 arranged on the surface of the annular portion 512 facing the annular portion 511, and having a plurality of slits 524 at positions that overlap the plurality of slits 514 in the vertical direction. This suppresses wear of the outer ring 51 and enables stable plasma containment over a long period of time.

[0054] According to the plasma processing apparatus 1 of Embodiment 1, the number of slits 524 in the outer ring 52 is equal to the number of slits 514 in the outer ring 51. By creating a one-to-one correspondence between the slits 514 and 524 of these outer rings 51 and 52, the expansion of the slits 514 due to wear of the outer ring 51 can be suppressed more reliably.

[0055] According to the plasma processing apparatus 1 of Embodiment 1, the opening area of ​​each of the multiple slits 524 in the outer ring 52 is smaller than the opening area of ​​each of the multiple slits 514 in the outer ring 51. As a result, even if the slits 524 of the outer ring 52 enlarge after a predetermined period of use, the enlargement of the slits 514 due to wear of the outer ring 51 can be suppressed more reliably.

[0056] According to the plasma processing apparatus 1 of Embodiment 1, the outer ring 52 is composed of a plurality of divided members 522 that combine with each other to form an annular shape. This allows the outer ring 52 to be easily positioned within the C-shaped space of the outer ring 51.

[0057] (modified version) Next, a modified plasma processing apparatus of Embodiment 1 will be described with reference to Figures 5 to 7. The modified plasma processing apparatus differs from Embodiment 1 in that the outer rings 51a to 51c and 52a are configured to be fixable to each other.

[0058] In the following drawings, components similar to those in Embodiment 1 described above are denoted by the same reference numerals, and their descriptions may be omitted.

[0059] Figure 5 is a schematic diagram showing an example of the configuration of the outer rings 51a and 52a according to a modified example of Embodiment 1. More specifically, Figure 5(a) is a bottom view showing the overall configuration of the outer ring 52a. Figure 5(b) is a perspective cross-sectional view showing the outer rings 51a and 52a superimposed on each other. Figure 5(c) is a cross-sectional view of one side of the outer rings 51a and 52a.

[0060] As shown in Figure 5(a), at least one pin 525 is provided on the lower surface of each of the multiple dividing members 522a of the outer ring 52a, that is, on the surface facing the outer ring 51a. In the example in Figure 5(a), each dividing member 522 has two pins 525 arranged at equal intervals on its inner edge and two pins 525 arranged at equal intervals on its outer edge opposite to these. However, the number and arrangement of pins 525 on each dividing member 522 are not limited to the example in Figure 5(a).

[0061] As shown in Figures 5(b) and 5(c), multiple insertion holes 515 are provided on the upper surface of the annular portion 512a of the outer ring 51a, that is, on the surface facing the outer ring 52a, at positions opposite to each of the multiple pins 525 of the outer ring 52a. When the outer ring 52a is superimposed on the annular portion 512a of the outer ring 51a, the multiple pins 525 of the outer ring 52a are inserted into the corresponding insertion holes 515 of the outer ring 51a, thereby fixing the outer rings 51a and 52a together. Furthermore, when attaching the outer ring 51a to the outer ring 52a, the positioning of the outer rings 51a and 52a together becomes easier.

[0062] Figure 6 is a schematic diagram showing another example of the configuration of the outer rings 51b and 52 according to a modified example of Embodiment 1. More specifically, Figure 6(a) is a perspective cross-sectional view showing the outer rings 51b and 52 superimposed on each other. Figure 6(b) is a cross-sectional view of one side of the outer rings 51b and 52.

[0063] In the example shown in Figure 6, the outer ring 52 of Embodiment 1 described above is used together with the outer ring 51b of the modified example.

[0064] As shown in Figure 6(a), the annular portion 512b of the outer ring 51b is provided with a plurality of slits 514, and the surface facing the outer ring 52 on which the outer ring 52 is placed is an annular groove 517 that is recessed relative to the inner and outer edges of the outer ring 51b. At this time, the depth of the groove 517 of the annular portion 512b is approximately equal to, for example, the thickness of the outer ring 52. On the other hand, the inner and outer edges of the outer ring 51 each have protrusions 516 that project annularly relative to the groove 517.

[0065] The outer ring 52 is positioned to fit into the groove 517 of the outer ring 51b. At this time, the upper surface of the outer ring 52 is approximately equal in height to the upper surface of the protrusion 516 of the outer ring 51b. This fixes the outer rings 51b and 52 together. It also facilitates the positioning of the outer rings 51b and 52 together. Furthermore, because the upper surface of the protrusion 516 of the outer ring 51b and the upper surface of the outer ring 52 are at the same height, it is possible to create a configuration without protrusions or other elements that could disturb the plasma, thereby suppressing the influence of these outer rings 51b and 52 on the plasma.

[0066] As shown in Figure 6(b), the projection 516 on the inner edge side of the annular portion 512b of the outer ring 51b may be eliminated and made the same height as the bottom surface of the groove 517. In this case, the inner edge end of the outer ring 52 may be widened to the same size as or greater than the inner edge end of the outer ring 51b. However, in this case, it may become difficult to position the inner edges of the outer ring 52 and the outer ring 51b. Therefore, to facilitate this positioning, the pin 525 and insertion hole 515 may be provided only on the inner edge, as shown in Figure 5. This makes it possible to determine the inner edge positions of the outer ring 52 and the outer ring 51b.

[0067] Figure 7 is a schematic diagram showing yet another example of the configuration of the outer rings 51c and 52 according to a modification of Embodiment 1. More specifically, Figure 7 is a perspective cross-sectional view showing the outer rings 51c and 52 superimposed on each other.

[0068] In the example shown in Figure 7, the outer ring 52 of Embodiment 1 described above is used together with the outer ring 51c of the modified example.

[0069] As shown in Figure 7, the annular portion 512c of the outer ring 51c has a plurality of slits 514c that have a larger opening area than the individual slits 524 of the outer ring 52. These slits 514c are separated by a plurality of spokes 518 that extend radially from the inner edge to the outer edge of the annular portion 512c.

[0070] As a result, the multiple slits 514c in the annular portion 512c of the outer ring 51c are configured to have a fan-shaped opening. Furthermore, the multiple slits 514c of the annular portion 512c correspond to several adjacent slits 524 of the multiple slits 524 of the outer ring 52. In other words, these several slits 524 are arranged to overlap with one of the slits 514c of the outer ring 51.

[0071] Furthermore, as described above, the annular portion 512c of the outer ring 51c is configured as a frame into which the outer ring 52 can be fitted. At this time, the multiple spokes 518 of the annular portion 512c support the outer ring 52, which is positioned on the annular portion 512c, from below. In this way, the outer rings 51c and 52 are fixed together by fitting the outer ring 52 into the frame of the annular portion 512c. In addition, the positioning of the outer rings 51c and 52 becomes easier.

[0072] In the modified plasma processing apparatus, the outer ring 52a has a pin 525 that protrudes from the surface facing the annular portion 512a of the outer ring 51a, and the annular portion 512a of the outer ring 51a has an insertion hole 515 on the surface facing the outer ring 52a into which the pin 525 of the outer ring 52a can be inserted.

[0073] This allows for more precise positioning and fixing of the outer ring 52a relative to the outer ring 51a. By fixing the outer rings 51a and 52a to each other, it is possible to suppress misalignment between these outer rings 51a and 52a during operation of the modified plasma processing apparatus.

[0074] In another example of a modified plasma processing apparatus, the annular portion 512b of the outer ring 51b has an annular groove 517 recessed from the inner and outer edges of the annular portion 512b on the surface facing the outer ring 52, and the outer ring 52 is configured to be fitted into the groove 517 of the outer ring 51b.

[0075] This configuration also allows for the positioning and fixing of the outer ring 52 relative to the outer ring 51b. Furthermore, because the surface of the outer ring 51b where the slit 514 is provided is recessed as a groove 517, the shielding effect from the plasma is enhanced, and the expansion of the slit 514 can be further suppressed.

[0076] In another example of a modified plasma processing apparatus, the thickness of the outer ring 52 is substantially equal to the depth of the groove 517 in the annular portion 512b of the outer ring 51b. This prevents surface irregularities from forming on these components when the outer ring 52 is fitted into the groove 517 of the outer ring 51b, thereby suppressing the influence on the plasma.

[0077] In yet another example of a modified plasma processing apparatus, the number of slits 524 in the outer ring 52 is greater than the number of slits 514c in the outer ring 51c, and two or more of the slits 524 are positioned to overlap with one of the slits 514c in the outer ring 51c.

[0078] This configuration also allows for the positioning and fixing of the outer ring 52 relative to the outer ring 51c. Furthermore, since it has a simple configuration without slits 514, etc., the cost of the outer ring 51c can be reduced.

[0079] These modified plasma processing apparatuses also provide the same effects as the plasma processing apparatus 1 of the above-described embodiment.

[0080] [Embodiment 2] Embodiment 2 will now be described in detail with reference to the drawings. Embodiment 2 differs from Embodiment 1 described above in that the flat outer ring is positioned on the lower surface of the C-shaped outer ring.

[0081] In the following drawings, components similar to those in Embodiment 1 described above are denoted by the same reference numerals, and their descriptions may be omitted.

[0082] (Example of plasma processing apparatus configuration) Figure 8 is a schematic cross-sectional view showing an example of the configuration of the plasma processing apparatus 2 according to Embodiment 2. The plasma processing apparatus 2 is equipped with a plasma containment mechanism 60 instead of the plasma containment mechanism 50 of Embodiment 1 described above.

[0083] The plasma containment mechanism 60 includes outer rings 61 and 62, an adjustment plate 63, and a motor (not shown) for driving the adjustment plate 63. The outer ring 61 has a C-shaped cross-section on one side. The outer ring 62 is positioned on the lower surface of the outer ring 61. The adjustment plate 63 faces the outer ring 62 and is configured so that its distance from the outer ring 62 can be adjusted.

[0084] (Example of outer ring configuration) Next, using Figures 9 and 10, we will describe a detailed example of the configuration of the outer rings 61 and 62 included in the plasma containment mechanism 60.

[0085] Figures 9 and 10 are schematic diagrams showing an example of the configuration of the outer rings 61 and 62 according to Embodiment 2.

[0086] More specifically, Figure 9(a) is a top view showing the annular portion 612 of the outer ring 61, Figure 9(b) is a top view showing the overall configuration of the outer ring 52, and Figure 9(c) is a top view showing the outer rings 61 and 62 superimposed.

[0087] Figure 10(a) is a cross-sectional view of one side of the outer rings 61 and 62, showing the cross-section of the slit 624 of the outer ring 62 that overlaps vertically with the slit 614 of the outer ring 61. Figure 10(b) is a cross-sectional view of one side of the outer rings 61 and 62, showing the cross-section of the slit 624 of the outer ring 62 that does not overlap with the slit 614.

[0088] As shown in Figure 9(a), the outer ring 61 has an annular and flat annular portion 612. The annular portion 612 is provided with a plurality of slits 614 that penetrate the annular portion 612 in the thickness direction and are arranged radially toward the outer edge of the annular portion 612. The other configurations of the outer ring 61 are the same as in Embodiment 1 described above.

[0089] As shown in Figure 9(b), the outer ring 62 has an annular member 622 that is configured to be circular and flat. The annular member 622 is provided with a plurality of slits 624 that penetrate the annular member 622 in the thickness direction and are arranged radially toward the outer edge of the annular member 622.

[0090] The number of slits 624 in the outer ring 62 is twice the number of slits 614 in, for example, the outer ring 61. Therefore, the multiple slits 624 are more densely arranged than the multiple slits 614, and the spacing between them is about half that of the multiple slits 614.

[0091] As shown in Figure 9(c), when the outer ring 62 is superimposed on the annular portion 612 of the outer ring 61, every other slit 624 of the outer ring 62 overlaps with each of the slits 614 of the outer ring 61 in the vertical direction. In other words, half of the slits 624 overlap with one of the slits 614, and the other half do not overlap with any of the slits 614.

[0092] In Figure 9(c), the slit 624 of the outer ring 62 that does not overlap with the slit 614 of the outer ring 61 is shown with a dashed line.

[0093] As shown in Figure 10, the outer ring 61 has, in addition to the annular portion 612 described above, an annular portion 611 that is separated from the annular portion 612 at a predetermined distance and facing it, and a wall portion 613 that connects the annular portion 611 and the annular portion 612.

[0094] Furthermore, at least one screw 625 is provided on the upper surface of the multiple annular members 622 of the outer ring 62, that is, on the surface facing the outer ring 61. The number and arrangement of these screws 625 on the outer ring 62 may be the same as the pins 525 provided on the outer ring 52a in Figure 5, which is shown as an example of the modified embodiment 1 described above. Alternatively, the number and arrangement of these screws 625 may differ from the pins 525 in Figure 5 described above.

[0095] On the lower surface of the annular portion 612 of the outer ring 61, that is, the surface facing the outer ring 62, a plurality of insertion holes 615 are provided at positions opposite to the plurality of screws 625 of the outer ring 62.

[0096] When the outer ring 62 is superimposed on the annular portion 612 of the outer ring 61, the multiple screws 625 of the outer ring 62 are each inserted into the corresponding insertion holes 615 of the outer ring 61, thereby allowing the outer ring 62 to be attached to the lower surface of the outer ring 61.

[0097] As shown in Figure 10(a), the opening areas of the slits 614 and 624 of the outer rings 61 and 62 are approximately equal, and when either of the slits 624 of the outer ring 62 overlaps with the corresponding slit 614 of the outer ring 61, their outer shapes are approximately identical.

[0098] As shown in Figure 10(b), at positions where the slits 614 and 624 of the outer rings 61 and 62 do not overlap in the vertical direction, the slit 624 of the outer ring 62 is blocked by the annular portion 612 of the outer ring 61.

[0099] In the plasma processing apparatus 2 of Embodiment 2, the atmosphere inside the processing container 11 is exhausted through the slits 624 of the outer ring 62 that overlap with the slits 614 of the outer ring 61, and the corresponding slits 614.

[0100] (Example of using the outer ring) Next, we will explain examples of how to use the outer rings 61 and 62 of Embodiment 2 using Figures 11 to 15.

[0101] Figure 11 is a top view showing the overall configuration of the outer rings 61 and 62 according to Embodiment 2 after a predetermined usage time has elapsed.

[0102] As shown in Figure 11, the outer rings 61 and 62, after being used in the plasma processing apparatus 2 for a predetermined time, are worn down by exposure to plasma for that time. As a result, the opening areas of the multiple slits 614 in the outer ring 61 are all enlarged. Similarly, among the multiple slits 624 in the outer ring 62, the opening area of ​​the slits 624 that overlap vertically with the slits 614 of the outer ring 61 is also enlarged.

[0103] On the other hand, as shown by the dashed lines in Figure 11, the slits 624 that are positioned every other slit 624 and do not overlap vertically with the slits 614 of the outer ring 61 were covered by the annular portion 612 of the outer ring 61 within the plasma processing apparatus 2. As a result, there was almost no wear due to the plasma, and the opening area was maintained almost as it was when new.

[0104] Figure 12 is a cross-sectional view of one side of the outer rings 61 and 62 according to Embodiment 2 after a predetermined period of use has elapsed.

[0105] More specifically, Figure 12(a) shows a cross-section of the slit 624 of the outer ring 62 that overlaps vertically with the slit 614 of the outer ring 61. Figure 12(b) shows a cross-section of the slit 624 of the outer ring 62 that does not overlap with the slit 614.

[0106] As shown in Figure 12(a), at the positions where the slits 614 and 624 of the outer rings 61 and 62 overlap each other, the opening area of ​​both slits 614 and 624 is enlarged due to plasma wear.

[0107] As shown in Figure 12(b), in the position where the slit 624 of the outer ring 62 does not overlap with the slit 614 of the outer ring 61, it is protected by the annular portion 612 of the outer ring 61, and the opening area of ​​the slit 624 of the outer ring 62 is hardly enlarged.

[0108] Figure 13 is a top view showing the overall configuration of the outer ring 62 according to Embodiment 2 after a predetermined period of use has elapsed.

[0109] As shown in Figure 13(a) and as described above, every other slit 624 of the outer ring 62 overlapped vertically with the slit 614 of the outer ring 61, and therefore its aperture area expanded due to plasma wear. On the other hand, every other slit 624 located between these was protected by the outer ring 61, and therefore did not experience plasma wear, and its aperture area hardly expanded.

[0110] In the plasma processing apparatus 2 of Embodiment 2, after a predetermined usage time has elapsed, the outer ring 62, which is in the state described above, is temporarily removed from the outer ring 61, rotated by a predetermined angle around its center point as viewed from the top surface, and then reattached to the outer ring 61. When attached to the plasma processing apparatus 2, the center point of the outer ring 62, which serves as the axis of rotation for the outer ring 62, substantially coincides with the center point in the plane of the wafer stage 20.

[0111] As shown in Figure 13(b), by rotating the outer ring 62 by a predetermined angle, the multiple slits 624 that were originally positioned to overlap each of the slits 614 of the outer ring 61 in the vertical direction move to a position where they do not overlap the slits 614 of the outer ring 61. On the other hand, the remaining slits 624 that were originally positioned not to overlap the slits 614 of the outer ring 61 in the vertical direction move to a position where they overlap one of the slits 614 of the outer ring 61.

[0112] Figure 14 is a top view showing how the outer rings 61 and 62 according to Embodiment 2 are superimposed at a different angle after a predetermined period of use. More specifically, Figure 14(a) shows the overall top surface of the outer ring 61, Figure 14(b) shows the overall top surface of the outer ring 62, and Figure 14(c) shows the overall top surfaces of the outer rings 61 and 62 superimposed on each other.

[0113] As shown in Figure 14(b), by rotating the outer ring 62 by a predetermined angle from its initial mounting position, the multiple slits 624 that were previously protected from plasma in positions that did not overlap with the slits 614 of the outer ring 61 and whose opening area was hardly enlarged are now positioned in the positions corresponding to each of the slits 614 of the outer ring 61, as shown in Figure 14(a).

[0114] As shown in Figure 14(c), when the outer ring 61 in Figure 14(a) and the outer ring 62 in Figure 14(b) are superimposed, the slits 624 of the outer ring 62, whose opening area is hardly enlarged, are positioned on the bottom surface of each of the multiple slits 614 of the outer ring 61. When these outer rings 61 and 62 are viewed from above, the inner edges of the slits 624 of the outer ring 62 should be visible protruding from the openings of each of the slits 614 of the outer ring 61.

[0115] In this way, after a predetermined period of use, the outer ring 62 is rotated by a predetermined angle and reattached to the outer ring 61, thereby correcting the opening area of ​​the enlarged slit 614 of the outer ring 61 to approximately the same opening area as when it was new, due to the almost unenlarged slit 624 of the outer ring 62.

[0116] The usage time of the outer rings 61 and 62 before the rotation of the outer ring 62 can be defined as the time before the plasma containment characteristics become unstable due to wear of the outer rings 61 and 62. The above usage time of the outer rings 61 and 62 can also be said to be the time when the outer ring 61 reaches the end of its lifespan, for example, when the outer ring 61 is used alone.

[0117] Figure 15 is a cross-sectional view of one side of the outer rings 61 and 62 after reinstallation according to Embodiment 2.

[0118] More specifically, Figure 15(a) shows a cross-section of the slit 624 of the outer ring 62 that overlaps vertically with the slit 614 of the outer ring 61. Figure 15(b) shows a cross-section of the slit 624 of the outer ring 62 that does not overlap with the slit 614.

[0119] As shown in Figure 15(a), new slits 624 of the outer ring 62 are positioned below each slit 614 of the outer ring 61. The slits 614 of the outer ring 61 have an enlarged opening area compared to their original state due to the plasma treatment. However, the opening area of ​​the new slits 624 of the outer ring 62, positioned below the slits 614, has hardly enlarged. Therefore, the overall opening area of ​​the slits 614 and 624 of the outer rings 61 and 62 as a whole remains approximately the same as the opening area when they were new.

[0120] As shown in Figure 15(b), the slit 624, which has been enlarged due to wear of the outer ring 62, is positioned so as not to overlap with the slit 614 of the outer ring 61.

[0121] After the outer ring 62 has rotated, the atmosphere inside the processing container 11 is exhausted through the slit 624 of the outer ring 62 that now overlaps with the slit 614 of the outer ring 61, and the corresponding slit 614.

[0122] (Example of plasma treatment) Next, an example of plasma processing of a wafer 10 in the plasma processing apparatus 2 of Embodiment 2 will be described using Figure 16. The processing of the wafer 10 in the plasma processing apparatus 2 is performed, for example, as part of the manufacturing process of a semiconductor device.

[0123] Figure 16 is a flowchart showing an example of the plasma processing procedure in the plasma processing apparatus 2 according to Embodiment 2.

[0124] As shown in Figure 16, new outer rings 61 and 62 are attached to the plasma processing apparatus 2 (step S101), and a predetermined number of wafers 10 are subjected to plasma processing (step S102). Plasma processing on the wafers 10 continues as long as the usage time of the outer rings 61 and 62 is less than a predetermined time (step S103: No).

[0125] The operating time of the outer rings 61 and 62 is determined by integrating the plasma generation time, for example, based on the operating time of the high-frequency power supply 44 provided in the plasma processing device 2. The integrated plasma generation time is also called the RF (Resonance Frequency) integrated time.

[0126] If the usage time of the outer rings 61 and 62 exceeds a predetermined time (step S103: Yes), and if the number of rotations of the currently used outer ring 62 has not reached a predetermined number (step S104: No), the outer ring 62 is rotated by a predetermined angle from its initial mounting angle and reattached to the outer ring 61 (step S105), and the plasma treatment of the wafer 10 is continued (step S102).

[0127] If the outer ring 62 currently in use has already been rotated a predetermined number of times (step S104: Yes), then the use of that outer ring 62 is discontinued and replaced with a new outer ring 62.

[0128] In the examples shown in Figures 9 to 15 above, the outer ring 62 can be rotated only once during use, and after rotation, it is replaced again when the predetermined usage time has been reached.

[0129] With the above steps, the plasma processing in the plasma processing apparatus 2 of Embodiment 2 is completed.

[0130] (Overview) According to the semiconductor device manufacturing method of Embodiment 2, an outer peripheral ring 61 is used, which includes an annular portion 612 having a plurality of slits 614 arranged radially outward from the outer edge of the wafer stage 20, and an outer peripheral ring 62 is disposed on the surface of the annular portion 612 opposite to the surface facing the annular portion 611, which is arranged radially outward from the outer edge of the wafer stage 20, and has a plurality of slits 624, which is more numerous than the plurality of slits 614.

[0131] By using a plasma processing apparatus 2 equipped with such outer rings 61 and 62, overall wear of the outer rings 61 and 62 can be suppressed, enabling stable plasma containment over a long period of time.

[0132] According to the semiconductor device manufacturing method of Embodiment 2, the outer ring 62 is positioned at a predetermined angle to the outer ring 61 with respect to the center point in the plane of the wafer stage 20 as the axis of rotation, and the same number of slits 624 as the number of slits 614 are overlapped vertically with the number of slits 614. Plasma processing is then performed on the wafer 10 placed on the wafer stage 20 with the number of slits 614 and the same number of slits 624 overlapping vertically.

[0133] As a result, during the plasma treatment described above, half of the slits 624 of the outer ring 62 are kept from being exposed to the plasma. Therefore, half of the slits 624 of the outer ring 62 can be kept in a nearly new condition for a predetermined period of time.

[0134] According to the semiconductor device manufacturing method of Embodiment 2, when the plasma treatment time reaches a predetermined time, the outer ring 62 is rotated with respect to the outer ring 61 at a predetermined angle different from that described above, using the center point in the plane of the wafer stage 20 as the axis of rotation, so that the same number of new slits 624 as the multiple slits 614 are superimposed on the multiple slits 614 in the vertical direction, and plasma treatment is performed on the wafer placed on the wafer stage 20 with the multiple slits 614 and the new slits 624 superimposed in the vertical direction.

[0135] This allows the outer rings 61 and 62 to be used even after a predetermined usage time has elapsed, and again until that predetermined usage time is reached. Therefore, in principle, the overall lifespan of the outer rings 61 and 62 can be doubled.

[0136] In the above-described embodiment 2, it is assumed that the rotation of the outer ring 62 and its reattachment to the outer ring 61 are performed manually. However, a configuration may be provided that allows the outer ring 62 to be automatically rotated relative to the outer ring 61 using known technologies such as gears and motors.

[0137] Furthermore, in the embodiments 1 and 2 and their modifications described above, the plasma processing apparatus 1 is configured as an RIE apparatus, but it is not limited to this. The plasma processing apparatus may also be an apparatus that performs plasma processing other than etching, such as a CDE (Chemical Dry Etching) apparatus or a CVD (Chemical Vapor Deposition) apparatus.

[0138] [Note] Preferred embodiments of the present invention are described below.

[0139] (Note 1) According to one aspect of the present invention, In the processing vessel where plasma processing is performed, the lower electrode is positioned on the outer circumference of the lower electrode, which is opposite the upper electrode. The first annular portion has a plurality of first slits arranged radially outward from the outer edge of the lower electrode, A second annular portion facing the first annular portion at a predetermined distance, A first outer ring having a wall portion connecting the outer edge of the first annular portion and the outer edge of the second annular portion, The first annular portion is positioned on the surface opposite to the surface facing the second annular portion, A second outer ring is provided, which is arranged radially outward from the outer edge of the lower electrode and has a plurality of second slits, which are more numerous than the plurality of first slits. A method for manufacturing a semiconductor device, carried out in a plasma processing apparatus comprising an exhaust unit that exhausts the inside of the processing container via the first and second outer rings, Using the in-plane center point of the lower electrode as the axis of rotation, the second outer ring is positioned at a first angle with respect to the first outer ring, and the same number of third slits as the number of first slits are superimposed vertically on the number of first slits from among the plurality of second slits. With the plurality of first slits and the third slit overlapping in the vertical direction, the plasma treatment is performed on the first substrate placed on the lower electrode. When the plasma processing time reaches a predetermined time, the second outer ring is rotated so that it forms a second angle with respect to the first outer ring, using the center point of the lower electrode in the plane as the axis of rotation, so that the same number of fourth slits as the number of first slits are superimposed vertically on the number of first slits from among the plurality of second slits. With the plurality of first slits and the fourth slit overlapping in the vertical direction, the plasma treatment is performed on the second substrate placed on the lower electrode. A method for manufacturing a semiconductor device is provided.

[0140] (Note 2) In the method for manufacturing the semiconductor device described in Appendix 1 above, The exhaust unit exhausts the inside of the processing container through the second slits, which are among the plurality of second slits and which overlap the plurality of first slits in the vertical direction.

[0141] (Note 3) In the method for manufacturing the semiconductor device described in Appendix 1 above, When the second outer ring is positioned at the first angle with respect to the first outer ring, the exhaust unit exhausts the inside of the processing container through the plurality of first slits and the third slit. When the second outer ring is positioned at the second angle with respect to the first outer ring, the exhaust unit exhausts the inside of the processing container through the plurality of first slits and the fourth slit.

[0142] (Note 4) In the method for manufacturing the semiconductor device described in Appendix 1 above, The aforementioned plasma processing apparatus is On the opposite side of the first annular portion, an adjustment plate is further provided that faces the second outer ring, The distance between the adjustment plate and the second outer ring is adjusted according to the pressure in the space enclosed by the first annular portion and the second annular portion.

[0143] (Note 5) According to another aspect of the present invention, A processing container for processing substrates, An upper electrode that supplies processing gas into the processing container, A lower electrode is positioned in the processing container opposite to the upper electrode, on which the substrate is placed, A power supply that supplies power to at least one of the upper electrode and the lower electrode to generate plasma in the processing container, First and second outer rings are arranged on the outer circumference of the lower electrode, The device comprises an exhaust section that exhausts the inside of the processing container via the first and second outer rings, The first outer ring described above is A first annular portion having multiple first slits, A second annular portion facing the first annular portion at a predetermined distance, It has a wall portion connecting the outer edge of the first annular portion and the outer edge of the second annular portion, The aforementioned second outer ring is The first annular portion has a plurality of second slits arranged on either the upper or lower surface, at least a portion of which overlaps with the plurality of first slits in the vertical direction, A plasma processing device is provided.

[0144] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of symbols]

[0145] 1,2...Plasma processing apparatus, 10...Wafer, 11...Processing container, 14...Gas exhaust port, 20...Wafer stage, 30...Shower head, 44...High-frequency power supply, 50,60...Plasma containment mechanism, 51,51a~51c,52,52a,61,62...Outer ring, 53,63...Adjustment plate, 71...Pressure gauge, 72...Vacuum pump, 100...Control unit, 511,512,512a~512c...Ring section, 522...Divided member, 514,524,614,624...Slit, 515,615...Insertion hole, 516...Protrusion, 517...Groove, 525...Pin, 622...Ring section, 625...Screw.

Claims

1. An outer ring set used in a plasma processing apparatus for processing substrates, A first annular portion having multiple first slits, A second annular portion is located opposite the first annular portion at a predetermined distance, A first outer ring having a wall portion connecting the outer edge of the first annular portion and the outer edge of the second annular portion, The present invention comprises a second outer ring positioned on the surface of the first annular portion facing the second annular portion, and having a plurality of second slits positioned to overlap the plurality of first slits in the vertical direction, Outer ring set.

2. The plurality of first slits are, The first ring portion is arranged radially toward the outer edge portion, The plurality of second slits are, The following are arranged radially toward the outer edge of the second outer ring: The outer ring set according to claim 1.

3. The number of the plurality of second slits is greater than the number of the plurality of first slits. Two or more of the plurality of second slits are positioned to overlap with one of the plurality of first slits. The outer ring set according to claim 2.

4. The number of the plurality of second slits is, The number of the aforementioned plurality of first slits is equal to the number of first slits, The outer ring set according to claim 2.

5. The opening area of ​​each of the plurality of second slits is Smaller than the opening area of ​​each of the plurality of first slits, The outer ring set according to claim 4.

6. The second outer ring is, It has a pin protruding from the surface opposite to the first annular portion, The first annular portion is, The surface facing the second outer ring has an insertion hole into which the pin can be inserted. The outer ring set according to claim 1.

7. In the first annular portion, The surface facing the second outer ring is an annular groove recessed from the inner and outer edges of the first ring portion. The second outer ring is, It is configured to be able to be fitted into the groove. The outer ring set according to claim 1.

8. The second outer ring is, It is composed of multiple members that combine with each other to form a ring shape. The outer ring set according to claim 1.

9. A processing container for processing substrates, An upper electrode that supplies processing gas into the processing container, A lower electrode is positioned in the processing container opposite to the upper electrode, on which the substrate is placed, A power supply that supplies power to at least one of the upper electrode and the lower electrode to generate plasma in the processing container, First and second outer rings are arranged on the outer circumference of the lower electrode, The system includes an exhaust section that exhausts the inside of the processing container via the first and second outer rings, The first outer ring is, A first annular portion having multiple first slits, A second annular portion is located opposite the first annular portion at a predetermined distance, It has a wall portion connecting the outer edge of the first annular portion and the outer edge of the second annular portion, The second outer ring is, The upper surface of the first annular portion is arranged and has a plurality of second slits positioned to overlap the plurality of first slits in the vertical direction, Plasma processing equipment.

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