Plasma Processing Equipment

Abstract

To provide a plasma processing apparatus capable of forming a stable electric field distribution and an RF environment around a substrate support portion.SOLUTION: A plasma processing apparatus includes a chamber, a plasma generation unit configured to generate plasma inside the chamber, a substrate support portion disposed inside the chamber, a first conductive ring arranged to surround the substrate on the substrate support portion, an insulating ring arranged to surround the first conductive ring, and a second conductive ring which is arranged to surround the insulating ring and connected to a ground potential or a DC potential. The second conductive ring has an annular projecting portion that projects upward from the height of the top surface of the insulating ring.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a plasma processing apparatus. [Background technology]

[0002] Patent Document 1 discloses that in a plasma processing apparatus including a mounting table, an inner focus ring, an outer focus ring, lift pins, and a moving mechanism, the lift pins are raised by the moving mechanism in response to wear of the inner focus ring, thereby lifting the inner edge ring. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-53538 A Summary of the Invention [Problem to be solved by the invention]

[0004] The technology according to the present disclosure provides a plasma processing apparatus capable of forming a stable electric field distribution and RF environment around a substrate support part. [Means for solving the problem]

[0005] One aspect of the present disclosure includes a plasma generating device including a chamber, a plasma generating unit configured to generate plasma in the chamber, a substrate support disposed in the chamber, a first conductive ring disposed to surround a substrate on the substrate support, an insulating ring disposed to surround the first conductive ring, and a second conductive ring disposed to surround the insulating ring and connected to a ground potential or a DC potential, the second conductive ring having an annular protruding portion protruding upward from the height of an upper surface of the insulating ring. The annular protruding portion has a vertical dimension of 2 mm or more and 10 mm or less. A plasma processing apparatus. Effect of the Invention

[0006] According to the present disclosure, a plasma processing apparatus capable of forming a stable electric field distribution and RF environment around a substrate support part is provided. [Brief description of the drawings]

[0007] [Figure 1] 1 is a schematic diagram showing an example of the configuration of a plasma processing system; [Diagram 2] 1 is a vertical cross-sectional view showing a configuration example of a plasma processing apparatus according to an embodiment; [Diagram 3] 4 is an enlarged view of a main portion showing the periphery of a side wall of the substrate support portion; FIG. [Figure 4A] FIG. 13 is an explanatory diagram showing the state inside the chamber when there is no ground ring. [Figure 4B] FIG. 13 is an explanatory diagram showing the state inside the chamber when there is no ground ring. [Figure 5A] FIG. 13 is an explanatory diagram showing the state inside the chamber when a ground ring is present. [Figure 5B] FIG. 13 is an explanatory diagram showing the state inside the chamber when a ground ring is present. [Figure 6A] 1 is a graph showing the amount of fluctuation in electric field strength caused by a change in plasma density. [Figure 6B] FIG. 6B is a supplementary explanatory diagram for FIG. 6A. [Figure 6C] FIG. 6B is a supplementary explanatory diagram for FIG. 6A. [Figure 7] 11 is a graph showing the relationship between the height of the annular protrusion and the amount of fluctuation in electric field strength. [Figure 8] 1 is an enlarged view of a main portion of an example of a ground ring having a high annular protruding portion. FIG. [Figure 9] 13 is an enlarged view of a main portion showing another example of the configuration of the ground ring. FIG. [Figure 10A] 13 is an enlarged view of a main portion showing another example of the configuration of the ground ring. FIG. [Figure 10B] 13 is an enlarged view of a main portion showing another example of the configuration of the ground ring. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] In a semiconductor device manufacturing process, a processing gas supplied into a chamber is excited to generate plasma, and various plasma processes such as etching, film formation, and diffusion are performed on a semiconductor substrate (hereinafter simply referred to as a "substrate") supported by a substrate support. In the plasma processes, a plurality of annular members such as an edge ring and a cover ring (hereinafter the plurality of annular members are collectively referred to as a "ring assembly") are arranged to surround the substrate supported by the substrate support.

[0009] In the above-mentioned various plasma processes, the plasma generated in the chamber may cause wear on the chamber members such as the ring assembly and the substrate support, or may cause reaction products (hereinafter referred to as "deposits") to adhere to these chamber members. In particular, when wear or deposition occurs on the ring assembly arranged to surround the substrate, the electric field intensity and RF (Radio Frequency) radiation may increase around the substrate support (particularly the electrostatic chuck). Fluctuations in the thermal (temperature) frequency environment can affect process results, especially near the edge of the substrate.

[0010] Furthermore, the electric field conditions, particularly around the sidewall of the ring assembly, are easily affected by plasma generation conditions (e.g., plasma density), which can reduce the efficiency of controlling plasma generation above the substrate, affecting process results.

[0011] The technology disclosed herein has been made in consideration of the above circumstances, and provides a plasma processing apparatus capable of forming a stable electric field distribution and RF environment around a substrate support. Hereinafter, a plasma processing system including a plasma processing apparatus according to the present embodiment will be described with reference to the drawings. In this specification and the drawings, elements having substantially the same functional configurations are denoted by the same reference numerals, and duplicated descriptions will be omitted.

[0012] <Plasma processing system> In one embodiment, the plasma processing system includes a plasma processing apparatus 1 and a control unit 2, as shown in FIG. 1. The plasma processing apparatus 1 includes a plasma processing chamber 10, a substrate support unit 11, and a plasma generation unit 12. The plasma processing chamber 10 has a plasma processing space. The plasma processing chamber 10 also has at least one gas supply port for supplying at least one processing gas to the plasma processing space, and at least one gas exhaust port for exhausting gas from the plasma processing space. The gas supply port is connected to a gas supply unit 20, which will be described later, and the gas exhaust port is connected to an exhaust system 40, which will be described later. The substrate support unit 11 is disposed in the plasma processing space, and has a substrate support surface for supporting a substrate.

[0013] The plasma generating unit 12 is configured to generate plasma from at least one processing gas supplied into the plasma processing space. The plasma formed in the plasma processing space may be a capacitively coupled plasma (CCP), an inductively coupled plasma (ICP), an electron-cyclotron-resonance plasma (ECR plasma), a helicon wave plasma (HWP), or a surface wave plasma (SWP), etc. Also, various types of plasma generating units may be used, including an alternating current (AC) plasma generating unit and a direct current (DC) plasma generating unit. In one embodiment, the AC signal (AC power) used in the AC plasma generating unit has a frequency in the range of 100 kHz to 10 GHz. Thus, the AC signal includes a radio frequency (RF) signal and a microwave signal. In one embodiment, the RF signal has a frequency in the range of 200 kHz to 150 MHz.

[0014] The control unit 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to perform various steps described in the present disclosure. The control unit 2 may be configured to control each element of the plasma processing apparatus 1 to perform various steps described herein. In one embodiment, a part or all of the control unit 2 may be included in the plasma processing apparatus 1. The control unit 2 may include, for example, a computer 2a. The computer 2a may include, for example, a processing unit (CPU: Central Processing Unit) 2a1, a storage unit 2a2, and a communication interface 2a3. The processing unit 2a1 may be configured to perform various control operations based on a program stored in the storage unit 2a2. The storage unit 2a2 may include a random access memory (RAM), a read only memory (ROM), a hard disk drive (HDD), a solid state drive (SSD), or a combination thereof. The communication interface 2a3 may communicate with the plasma processing apparatus 1 via a communication line such as a local area network (LAN).

[0015] <Plasma processing equipment> Next, a configuration example of a capacitively coupled plasma processing apparatus 1 will be described as an example of the above-mentioned plasma processing apparatus 1. FIG.

[0016] The plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply 20, a power supply 30, and an exhaust system 40. The plasma processing apparatus 1 also includes a substrate support 11 and a gas inlet. The substrate support 11 is disposed in the plasma processing chamber 10. The gas inlet is configured to introduce at least one processing gas into the plasma processing chamber 10. The gas inlet includes a shower head 13. The shower head 13 is disposed above the substrate support 11. In one embodiment, the shower head 13 constitutes at least a part of a ceiling of the plasma processing chamber 10. Inside the plasma processing chamber 10, a plasma processing space 10s is formed, which is defined by the shower head 13, a sidewall 10a of the plasma processing chamber 10, and the substrate support 11. The plasma processing chamber 10 has at least one gas inlet for supplying at least one processing gas to the plasma processing space 10s and at least one gas outlet for exhausting gas from the plasma processing space 10s. The plasma processing chamber 10 is grounded. The showerhead 13 and the substrate support 11 are electrically isolated from the plasma processing chamber 10 .

[0017] The substrate support 11 includes a main body 110 and a ring assembly 120. The upper surface of the main body 110 has a central region 110a (substrate support surface) for supporting a substrate (wafer) W, and an annular region 110b (ring support surface) for supporting the ring assembly 120. The annular region 110b surrounds the central region 110a in a plan view. The substrate W is disposed on the central region 110a, and the ring assembly 120 is disposed on the annular region 110b so as to surround the substrate W on the central region 110a.

[0018] In one embodiment, the main body 110 includes a base 111 and an electrostatic chuck 112. The base 111 includes a conductive member. The conductive member of the base functions as a lower electrode. The electrostatic chuck 112 is disposed on an upper surface of the base 111. The upper surface of the electrostatic chuck 112 constitutes the above-mentioned central region 110a (substrate support surface) and the above-mentioned annular region 110b (ring support surface).

[0019] The ring assembly 120 includes a plurality of annular members. As shown in Fig. 3 as an example, the ring assembly 120 includes an edge ring 121, a cover ring 122, and a ground ring 123. The edge ring 121, the cover ring 122, and the ground ring 123 are arranged in this order from the radially inner side (the electrostatic chuck 112 side). The edge ring 121 is arranged to surround the substrate W on the substrate support 11.

[0020] Edge ring 121 as a first conductive ring is disposed on annular region 110b (ring support surface) so as to surround substrate W supported on central region 110a (substrate support surface). Edge ring 121 is a conductive ring-shaped member and can be made of at least one of various materials such as silicon (Si), silicon carbide (SiC), and silicon oxide.

[0021] The cover ring 122 as an insulating ring is disposed on the outer circumferential side walls of the edge ring 121 and the main body portion 110 so as to surround the edge ring 121 and the main body portion 110. The cover ring 122 is an insulating ring-shaped member, and can be made of at least one of various materials such as quartz, Si-doped quartz, and alumina.

[0022] Ground ring 123 as a second conductive ring is disposed on the outer circumferential side wall of cover ring 122 so as to surround cover ring 122. Ground ring 123 is connected to a ground potential. Ground ring 123 is a ring-shaped member having electrical conductivity, and may be made of at least one of various materials such as silicon (Si), silicon carbide (SiC), silicon oxide, and conductive metals such as aluminum (Al). In one embodiment, ground ring 123 has a vertically elongated rectangular cross-sectional shape.

[0023] In the plasma processing in the plasma processing apparatus 1, the ground ring 123 may be exposed to the plasma processing space 10s. In this case, for example, if the ground ring 123 is made of a conductive metal such as aluminum (Al), the ground ring 123 may be corroded or contaminated due to the influence of radicals generated during the plasma processing. For this reason, particularly when the ground ring 123 is made of a conductive metal such as aluminum (Al), it is preferable that the ground ring 123 has a plasma-resistant coating layer on its surface. For example, a material containing yttria (Y) can be selected as the coating material. Also, instead of providing a coating layer on the surface of ground ring 123, a cover member having plasma resistance may be placed on the surface of ground ring 123. Examples of materials that can be selected for forming the cover member include silicon (Si) and quartz.

[0024] 3, the ground ring 123 is disposed so as to have an annular protruding portion (annular vertical protruding portion) 123a such that the upper surface of the ground ring 123 is at least higher than the upper surface of the cover ring 122. That is, the annular protruding portion 123a protrudes upward from the height of the upper surface of the cover ring 122. As an example, the annular protruding portion 123a is formed so that the upper surface of the ground ring 123 has a height (vertical dimension) H of 2 mm or more, preferably at least 2.5 to 3.5 mm or more, above the upper surface of the cover ring 122.

[0025] 3, the ground ring 123 may be connected to a ground potential via a bottom ring 124 serving as a third conductive ring. As an example, the bottom ring 124 is disposed so as to extend from the lower end of the ground ring 123 toward the radially inner periphery side (the main body 110 side). The bottom ring 124 is a ring-shaped member having electrical conductivity, and may be formed of a metal member such as aluminum (Al). The ground ring 123 and the bottom ring 124 may be configured as an integral body or as separate bodies.

[0026] Although not shown in the drawings, the ground ring 123 may be configured to be movable up and down by an actuator or the like.

[0027] Although not shown, the substrate support 11 may include a temperature adjustment module configured to adjust at least one of the electrostatic chuck 112, the ring assembly 120, and the substrate W to a target temperature. The temperature adjustment module may include a heater, a heat transfer medium, a flow path, or a combination thereof. A heat transfer fluid such as brine or gas flows through the flow path. The substrate support 11 may also include a heat transfer gas supply unit configured to supply a heat transfer gas (backside gas) between the back surface of the substrate W and the upper surface of the electrostatic chuck 112.

[0028] Returning to the explanation of Figure 2. A conductive baffle plate 130 connected to a ground potential may be disposed around the substrate support 11. In this case, the ground ring 123 may be connected to the ground potential via the conductive baffle plate 130. The conductive baffle plate 130 may be formed of a metal member such as aluminum (Al). The conductive baffle plate 130 has a plurality of through holes and is configured to exhaust gas in the plasma processing space 10s from a gas exhaust port 10e via the plurality of through holes.

[0029] Moreover, the conductive baffle plate 130 is disposed so that the upper surface of the conductive baffle plate 130 is at the same height as the upper surface of the ground ring 123 or is lower than the upper surface of the ground ring 123 as shown in FIG.

[0030] The shower head 13 is configured to introduce at least one processing gas from the gas supply unit 20 into the plasma processing space 10s. The shower head 13 has at least one gas supply port 13a, at least one gas diffusion chamber 13b, and multiple gas inlets 13c. The processing gas supplied from the gas supply unit 20 to the gas supply port 13a passes through the gas diffusion chamber 13b and is introduced into the plasma processing space 10s from the multiple gas inlets 13c. The shower head 13 also includes a conductive member. The conductive member of the shower head 13 functions as an upper electrode. In addition to the shower head 13, the gas introduction unit may include one or more side gas injectors (SGI) attached to one or more openings formed in the side wall 10a.

[0031] The gas supply 20 may include at least one gas source 21 and at least one flow controller 22. In one embodiment, the gas supply 20 is configured to supply at least one process gas from a respective gas source 21 through a respective flow controller 22 to the showerhead 13. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Additionally, the gas supply 20 may include one or more flow modulation devices to modulate or pulse a flow rate of the at least one process gas.

[0032] The power source 30 includes an RF power source 31 coupled to the plasma processing chamber 10 via at least one impedance matching circuit. The RF power source 31 is configured to supply at least one RF signal (RF power), such as a source RF signal and a bias RF signal, to a conductive member (lower electrode) of the substrate support 11 and / or a conductive member (upper electrode) of the showerhead 13. This causes a plasma to be formed from at least one processing gas supplied to the plasma processing space 10s. Thus, the RF power source 31 can function as at least a part of the plasma generating unit 12. In addition, a bias potential is generated on the substrate W by supplying a bias RF signal to the lower electrode, and ion components in the formed plasma can be attracted to the substrate W.

[0033] In one embodiment, the RF power supply 31 includes a first RF generating unit 31a and a second RF generating unit 31b. The first RF generating unit 31a is coupled to the lower electrode and / or the upper electrode via at least one impedance matching circuit, and is configured to generate a source RF signal (source RF power) for plasma generation. In one embodiment, the source RF signal has a frequency in the range of 13 MHz to 150 MHz. In one embodiment, the first RF generating unit 31a may be configured to generate a plurality of source RF signals having different frequencies. The generated one or more source RF signals are supplied to the lower electrode and / or the upper electrode. The second RF generating unit 31b is coupled to the lower electrode via at least one impedance matching circuit, and is configured to generate a bias RF signal (bias RF power). In one embodiment, the bias RF signal has a lower frequency than the source RF signal. In one embodiment, the bias RF signal has a frequency in the range of 400 kHz to 13.56 MHz. In one embodiment, the second RF generating unit 31b may be configured to generate a plurality of bias RF signals having different frequencies. The generated bias RF signal or signals are provided to the lower electrode, and in various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed.

[0034] The power supply 30 may also include a DC power supply 32 coupled to the plasma processing chamber 10. The DC power supply 32 includes a first DC generator 32a and a second DC generator 32b. In one embodiment, the first DC generator 32a is connected to the lower electrode and configured to generate a first DC signal. The generated first bias DC signal is applied to the lower electrode. In one embodiment, the first DC signal may be applied to another electrode, such as a chucking electrode in the electrostatic chuck 112. In one embodiment, the second DC generator 32b is connected to the upper electrode and configured to generate a second DC signal. The generated second DC signal is applied to the upper electrode. In various embodiments, at least one of the first and second DC signals may be pulsed. It is noted that the first and second DC generators 32a, 32b may be provided in addition to the RF power supply 31, or the first DC generator 32a may be provided instead of the second RF generator 31b.

[0035] The exhaust system 40 may be connected to, for example, a gas exhaust port 10e provided at the bottom of the plasma processing chamber 10. The exhaust system 40 may include a pressure regulating valve and a vacuum pump. The pressure regulating valve regulates the internal pressure of the plasma processing space 10s. The vacuum pump may include a turbomolecular pump, a dry pump, or a combination thereof.

[0036] Although various exemplary embodiments have been described above, the present invention is not limited to the above-described exemplary embodiments, and various additions, omissions, substitutions, and modifications may be made. In addition, elements in different embodiments can be combined to form other embodiments.

[0037] For example, in the above embodiments, the ground ring 123, the bottom ring 124, and the conductive baffle plate 130 are each connected to a ground potential, but the ground ring 123, the bottom ring 124, and the conductive baffle plate 130 may be connected to a constant DC potential (e.g., DC power supply 32) instead of or in addition to the ground potential.

[0038] <Effects of the Grand Ring> Here, Fig. 4A is an image diagram showing the electric field distribution (dashed line in the figure) and impedance (Zx and Zy in the figure) when high-density plasma is generated in the plasma processing space 10s when the ring assembly 120 does not include the ground ring 123. Also, Fig. 4B is an image diagram showing the electric field distribution and impedance when low-density plasma is generated in the plasma processing space 10s when the ring assembly 120 does not include the ground ring 123.

[0039] 4A, when high-density plasma (shaded area Pl in the figure) is generated in the plasma processing space 10s, plasma is also formed around the outer peripheral sidewall of the substrate support 11 (cover ring 122), and the outer peripheral space of the substrate support 11 (cover ring 122) is regarded as a conductor space of the same potential. Therefore, the RF current applied from the RF power supply 31 flows through the surface layers of the main body 110 and the edge ring 121, and as a result, an electric field (electric field) around the substrate support 11 is formed along the sidewalls of the main body 110 (particularly the electrostatic chuck 112) and the edge ring 121, as shown in FIG. On the other hand, when low-density plasma is generated in the plasma processing space 10s, the plasma becomes extremely thin around the outer peripheral sidewall of the substrate support 11 (cover ring 122), and the outer peripheral space of the substrate support 11 (cover ring 122) is regarded as a non-conductive space. Therefore, the RF current applied from the RF power supply 31 flows through the surface layers of the main body 110, the edge ring 121, and the cover ring 122, and as a result, an electric field (electric field) around the substrate support 11 is formed along the outer peripheral sidewall of the cover ring 122, as shown in FIG. 4B.

[0040] In addition, as shown in Figures 4A and 4B, depending on the plasma formation conditions in the plasma processing space 10s, whether the outer peripheral space of the substrate support 11 (cover ring 122) is regarded as a conductive space or a non-conductive space changes, and accordingly, the impedance Zx (radial component) distribution fluctuates. At this time, if the input power from the RF power source 31 is constant, the impedance Zx distribution fluctuates, causing the Zy (height component) distribution to fluctuate as well. Therefore, the process performance on the substrate W changes due to the change in the Zx and Zy distributions of the input power from the RF power source 31.

[0041] In this way, when the ring assembly 120 does not include the ground ring 123, the electric field condition and impedance around the outer peripheral sidewall of the substrate support 11 (cover ring 122) are likely to fluctuate due to changes in plasma formation conditions. Also, because the electric field condition and impedance fluctuate in this way, during plasma processing, the process results such as the etching rate near the edge of the substrate W are likely to fluctuate, particularly when the ring assembly 120 (edge ​​ring 121 and cover ring 122) is worn out or deposits are attached around the outer peripheral sidewall (changes over time in the members inside the chamber).

[0042] In contrast, as shown in Figures 5A and 5B, when the ring assembly 120 includes a ground ring 123, the RF current applied from the RF power supply 31 flows from top to bottom through the ground ring 123 regardless of the plasma formation conditions, and then flows to ground.

[0043] As a result, when the ring assembly 120 includes the ground ring 123, RF current flows through the ground ring 123 regardless of the plasma formation conditions, so that the electric field (electric field) conditions around the outer side wall of the substrate support 11 (cover ring 122) do not fluctuate due to changes in the plasma formation conditions and can be stabilized. In addition, since the ground ring 123 functions as a shielding plate, the impedance Zx distribution is prevented from fluctuating due to the plasma formation conditions. This allows the input power from the RF power supply 31 to be used only for controlling the impedance Zy, thereby appropriately improving the process control efficiency on the substrate W.

[0044] Furthermore, by arranging the ground ring 123 along the outer circumferential side wall of the main body 110 in this manner, stable process control can be achieved regardless of the adhesion or wear of deposits occurring in the outer circumferential space of the ground ring 123. In other words, the substrate support 11 can have a robust structure that is not affected by the adhesion or wear of deposits occurring in the outer circumferential space of the ground ring 123.

[0045] 6A shows the simulation results of the difference in electric field strength at each position (corresponding to P1 to P5 shown in FIGS. 6B and 6C) of the chamber internal members depending on the presence or absence of plasma around the outer circumferential sidewall of the substrate support 11 (hereinafter referred to as "side plasma") in each of the cases where the ring assembly 120 does not include the ground ring 123 (see FIG. 6B) and where the ring assembly 120 includes the ground ring 123 (see FIG. 6C). That is, the simulation results show the amount of variation in electric field strength at each position when the plasma generation conditions (plasma density) are changed in the plasma processing space 10s.

[0046] As shown in FIG. 6C, in this simulation, the annular protruding portion 123a is not formed on the upper portion of the ground ring 123.

[0047] As shown in FIG. 6A, when the ring assembly 120 does not include the ground ring 123, the electric field strength varies depending on the presence or absence of side plasma at each of the positions P1 to P5. However, by arranging the ground ring 123 along the outer peripheral side wall of the main body 110, the amount of variation in the electric field strength can be reduced. In particular, it is understood that, as shown in FIG. 6A, at positions P2 to P5 other than the end portion (position P1) of cover ring 122, the variation in electric field intensity due to the presence or absence of side plasma can be made as small as possible.

[0048] This is because, as shown in FIG. 4, when the ring assembly 120 does not include the ground ring 123, the electric potential distribution varies around the outer side wall of the substrate support 11 (cover ring) depending on the presence or absence of side plasma, thereby indirectly affecting the electric field around the electrostatic chuck 112. In this regard, by arranging the ground ring 123 along the outer peripheral side wall of the main body 110, the potential distribution around the outer peripheral side wall of the substrate support portion 11 (cover ring) can be stabilized regardless of changes in plasma density, thereby stabilizing the electric field around the electrostatic chuck 112.

[0049] <Annular protruding part of the ground ring> 6A, even when the ring assembly 120 includes the ground ring 123, a large fluctuation in electric field strength occurs at the end (position P1) of the cover ring 122 compared to the other positions P2 to P5. However, the present inventors have found that the fluctuation in electric field strength occurring at the end (position P1) of the cover ring 122 can be reduced by providing an annular protruding portion 123a on the top surface of the ground ring 123 that is higher than the top surface of the cover ring 122, as shown in FIG.

[0050] FIG. 7 is a graph showing the relationship between the height H of the annular protruding portion 123a of the ground ring 123 (see FIG. 3: the difference between the top surface of the ground ring 123 and the top surface of the cover ring 122) and the difference in electric field strength at position P1 with and without side plasma.

[0051] 7, by forming the annular protruding portion 123a so that the top surface of the ground ring 123 is higher than the top surface of the cover ring 122, it is understood that the fluctuation in the electric field intensity at the end portion (position P1) of the cover ring 122 shown in FIG 6A is reduced. In other words, it is understood that a stable electric field can be formed regardless of changes in the plasma generation conditions (plasma density). It is also apparent that, at this time, the greater the height H of the annular protruding portion 123a formed on the ground ring 123, the smaller the fluctuation in the electric field intensity at the end portion (position P1) of the cover ring 122 becomes.

[0052] This is believed to be due to the fact that by raising the position of the upper surface of the ground ring 123 so as to form the annular protruding portion 123a in this manner, the sheath can be pushed up above the ground ring 123 when plasma is generated, and the plasma can be more effectively confined to the plasma processing space 10s above the substrate W.

[0053] Here, the inventors conducted intensive research and found that, as shown in Fig. 7, the improvement rate (the slope of the graph in the figure) of the fluctuation amount of the electric field strength at the end (position P1) of the cover ring 122 becomes smaller when the height H of the annular protruding portion 123a reaches a boundary of about 2 mm. In other words, it was found that the fluctuation amount of the electric field strength at the end (position P1) of the cover ring 122 can be optimized by setting the height H of the annular protruding portion 123a to at least 2 mm.

[0054] On the other hand, for example, as shown in FIG. 8, if the height H of the annular protrusion 123a is increased so as to cover most of the plasma processing space 10s in the vertical direction, the exhaust conductance increases, and there is a risk that the exhaust system 40 will not be able to properly exhaust the plasma processing space 10s.

[0055] From the above viewpoints, the height H of the annular protruding portion 123a of the ground ring 123 is desirably 2 mm or more and 10 mm or less, more desirably 2.5 mm or more and 5 mm or less, and even more desirably 2.5 mm or more and 3.5 mm or less. If the height H of the annular protruding portion 123a is less than 2 mm, the fluctuation amount of the electric field intensity may not be optimized as shown in Fig. 7. Also, if the height H of the annular protruding portion 123a exceeds 10 mm, the plasma processing space 10s may not be properly evacuated.

[0056] <Effects of the Plasma Processing Apparatus According to the Embodiment> According to the plasma processing apparatus 1 of the above embodiment, by arranging the ground ring 123 connected to a ground potential so as to surround the cover ring 122, a stable electric field (electric field) can be formed around the substrate support 11 (particularly the electrostatic chuck 112) regardless of the plasma processing conditions (e.g., plasma density). Specifically, the RF current applied from the RF power supply 31 flows from top to bottom through the ground ring 123, and then flows to the ground. This generates a magnetic field in a direction perpendicular to the current direction, and the generated magnetic field acts to confine the plasma in the plasma processing space 10s above the substrate W. This improves the controllability of the process for the substrate W.

[0057] Furthermore, by disposing the ground ring 123 along the outer circumferential side wall of the cover ring 122 in this manner, stable process control can be achieved even if deposits adhere to or are consumed in the outer circumferential space of the ground ring 123. In other words, the substrate support 11 can have a robust structure that is not affected by deposits adhere to or are consumed in the outer circumferential space of the ground ring 123.

[0058] Furthermore, according to the above embodiment, the annular protruding portion 123a is formed so that the upper surface of the ground ring 123 is higher than the upper surface of the cover ring 122. This makes it possible to push up the sheath during plasma generation, and more suitably confine the plasma in the plasma processing space 10s above the substrate W. In other words, this further improves the controllability of the process for the substrate W.

[0059] As described above, if the height H of the annular protruding portion 123a of the ground ring 123 exceeds 10 mm, the exhaust conductance increases, which may prevent the plasma processing space 10s from being properly exhausted. On the other hand, from the viewpoint of more suitably suppressing the fluctuation of the electric field intensity caused by the change of the plasma generation conditions (e.g., plasma density) at the end (position P1) of the cover ring 122, it is preferable that the height H of the annular protruding portion 123a is as large as possible, i.e., 10 mm or more, and more preferably, the upper surface of the ground ring 123 (annular protruding portion 123a) contacts the shower head 13 constituting the ceiling of the plasma processing space 10s. In other words, it is preferable to separate the plasma processing space 10s above the substrate W from the outer peripheral space of the ground ring 123.

[0060] From the above viewpoints, the ground ring 123 may be configured so that the height H of the annular protruding portion 123a is 10 mm or more, or the top surface of the ground ring 123 (annular protruding portion 123a) is in contact with the shower head 13 as shown in FIG. 9, and one or more exhaust holes (through holes) 123b for improving exhaust conductance may be formed in the annular protruding portion 123a of the ground ring 123. The one or more through holes penetrate from the inner peripheral surface to the outer peripheral surface of the ground ring 123. The shape of the exhaust hole 123b is not particularly limited as long as it is formed to penetrate the ground ring 123 in the thickness direction. Specifically, the exhaust hole 123b may have any shape, such as a vertical slit, a horizontal slit, or punching. In this manner, by forming the height H of the annular protruding portion 123a of the ground ring 123 large and forming an exhaust hole 123b in the annular protruding portion 123a, the plasma processing space 10s can be evacuated by the exhaust system 40 while suppressing fluctuations in electric field strength caused by changes in plasma generation conditions (e.g., plasma density).

[0061] When the upper surface of the ground ring 123 (annular protruding portion 123a) is brought into contact with the shower head 13 in this manner, an interference member (not shown) made of a plasma-resistant material may be disposed at the contact interface between the ground ring 123 and the shower head 13. By providing an interference member in this manner, it is possible to suppress the generation of deposits due to contact between the ground ring 123 and the shower head 13.

[0062] In the above embodiment, the ground ring 123 is formed to have a vertically elongated rectangular cross-sectional shape, but the cross-sectional shape of the ground ring 123 is not limited to this, and the ground ring 123 may be formed to have any cross-sectional shape as long as it can be connected to a ground potential.

[0063] 10A, the ground ring 123 may have a second annular protruding portion (annular horizontal protruding portion) 123c that protrudes inward from the annular protruding portion 123a and covers a part of the upper surface of the cover ring 122. In this case, the ground ring 123 has a substantially L-shaped cross section with its upper portion (annular protruding portion 123a) protruding radially inward (toward the cover ring 122). Deposits generated during plasma processing tend to accumulate and adhere to the gap at the boundary between the cover ring 122 and the ground ring 123 on the upper surface of the ring assembly 120. In this regard, as shown in Fig. 10A, by configuring the gap at the boundary between the cover ring 122 and the ground ring 123 to be covered by the second annular protruding portion 123c, the volume and adhesion of deposits at the boundary can be suppressed.

[0064] Note that the second annular protruding portion 123c does not necessarily have to be formed on the upper portion of the ground ring 123 as shown in FIG. 10A, so long as it is formed so as to cover at least the gap that is the above-mentioned boundary portion. 10B, for example, when the height H of the annular protruding portion 123a is configured to be large, it is sufficient that at least a part of the annular protruding portion 123a protrudes inward at a height position corresponding to the upper surface position of the covering ring 122. Even in such a case, if at least a part of the upper surface of the covering ring 122 (the gap that is the above-mentioned boundary portion) can be covered, the volume and adhesion of deposits at the boundary portion can be suppressed.

[0065] For example, although not shown, the ground ring 123 may be formed by combining an annular member having a vertically elongated rectangular cross-sectional shape with an annular member having a horizontally elongated rectangular cross-sectional shape. In other words, the ground ring 123 may have a step in its cross-sectional shape.

[0066] The embodiments disclosed herein should be considered as illustrative and not restrictive in all respects. The above-described embodiments may be omitted, substituted, or modified in various forms without departing from the scope and spirit of the appended claims. [Explanation of symbols]

[0067] 1. Plasma processing equipment 10 Plasma Processing Chamber 11 Substrate support 110a central area 12 Plasma generating section 121 Edge Ring 122 Covering 123 Grand Ring 123a Annular protruding part

Claims

1. A chamber; a plasma generating unit configured to generate a plasma in the chamber; a substrate support disposed within the chamber; a first conductive ring disposed to surround a substrate on the substrate support; an insulating ring disposed to surround the first conductive ring; a second conductive ring disposed around the insulating ring and connected to a ground potential or a DC potential; the second conductive ring has an annular protruding portion protruding upwardly from the level of an upper surface of the insulating ring; The plasma processing apparatus, wherein the annular protruding portion has a vertical dimension of 2 mm or more and 10 mm or less.

2. The plasma processing apparatus of claim 1 , wherein the annular protruding portion has a vertical dimension of 2.5 mm or more and 5 mm or less.

3. The plasma processing apparatus of claim 1 , wherein the annular protruding portion has a vertical dimension of 2.5 mm to 3.5 mm.

4. A chamber; a plasma generating unit configured to generate a plasma in the chamber; a substrate support disposed within the chamber; a first conductive ring disposed to surround a substrate on the substrate support; an insulating ring disposed to surround the first conductive ring; a second conductive ring disposed around the insulating ring and connected to a ground potential or a DC potential; the second conductive ring has an annular protruding portion protruding upwardly from the level of an upper surface of the insulating ring; The annular protruding portion has a vertical dimension of 10 mm or more, The annular protruding portion has one or more through holes penetrating from the inner peripheral surface to the outer peripheral surface of the second conductive ring.

5. The plasma processing apparatus of claim 4 , wherein the annular protruding portion abuts against a ceiling of the chamber.

6. 6. The plasma processing apparatus according to claim 1, wherein the second conductive ring is disposed on an outer circumferential side wall of the insulating ring.

7. A chamber; a plasma generating unit configured to generate a plasma in the chamber; a substrate support disposed within the chamber; a first conductive ring disposed to surround a substrate on the substrate support; an insulating ring disposed to surround the first conductive ring; a second conductive ring disposed around the insulating ring and connected to a ground potential or a DC potential; the second conductive ring has an annular protruding portion protruding upwardly from the level of an upper surface of the insulating ring; The second conductive ring is disposed on an outer circumferential side wall of the insulating ring.

8. 8. The plasma processing apparatus according to claim 1, wherein the second conductive ring has a coating layer containing a material having plasma resistance.

9. a cover member disposed to cover the second conductive ring; 8. The plasma processing apparatus according to claim 1, wherein the cover member is made of a material having plasma resistance.

10. A chamber; a plasma generating unit configured to generate a plasma in the chamber; a substrate support disposed within the chamber; a first conductive ring disposed to surround a substrate on the substrate support; an insulating ring disposed to surround the first conductive ring; a second conductive ring disposed around the insulating ring and connected to a ground potential or a DC potential; the second conductive ring has an annular protruding portion protruding upwardly from the level of an upper surface of the insulating ring; a cover member disposed to cover the second conductive ring; The cover member is made of a plasma-resistant material.

11. 11. The plasma processing apparatus of claim 1, wherein the second conductive ring has an annular horizontal protruding portion that protrudes inwardly from the annular protruding portion and covers at least a portion of an upper surface of the insulating ring.

12. A chamber; a plasma generating unit configured to generate a plasma in the chamber; a substrate support disposed within the chamber; a first conductive ring disposed to surround a substrate on the substrate support; an insulating ring disposed to surround the first conductive ring; a second conductive ring disposed around the insulating ring and connected to a ground potential or a DC potential; the second conductive ring has an annular protruding portion protruding upwardly from the level of an upper surface of the insulating ring; The second conductive ring has an annular horizontal protruding portion protruding inwardly from the annular protruding portion and covering at least a portion of a top surface of the insulating ring.

13. 13. The plasma processing apparatus according to claim 1, wherein the insulating ring is made of at least one of quartz, silicon-doped quartz, and alumina.

14. 14. The plasma processing apparatus according to claim 1, wherein the first conductive ring is made of at least one of silicon, silicon carbide, and silicon oxide.

15. 15. The plasma processing apparatus according to claim 1, wherein the second conductive ring is made of at least one of silicon, silicon carbide, silicon oxide, and a conductive metal.

16. 16. The plasma processing apparatus according to claim 1, wherein the second conductive ring has a vertically elongated rectangular cross-sectional shape.

17. a third conductive ring disposed below the second conductive ring and connected to a ground potential or a DC potential; 17. The plasma processing apparatus according to claim 1, wherein the second conductive ring is connected to a ground potential or a DC potential via the third conductive ring.

18. The plasma processing apparatus of claim 17 , wherein the third conductive ring is formed of a conductive metal.

19. a conductive baffle plate disposed around the substrate support and connected to a ground potential or a DC potential; The plasma processing apparatus according to any one of claims 1 to 18, wherein the conductive baffle plate is positioned at the same height as an upper surface of the second conductive ring or at a lower height than an upper surface of the second conductive ring.

20. The plasma processing apparatus of claim 19 , wherein the second conductive ring is connected to a ground potential or a DC potential through the conductive baffle plate.

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