C-shield modifications for plasma uniformity without compromising mechanical strength or lifetime of the C-shield

Abstract

A confinement ring for a plasma processing chamber includes an upper horizontal section, a vertical section, and a lower horizontal section. The upper horizontal section extends between an upper inner radius and an outer radius of the confinement ring, and the lower horizontal section extends between a lower inner radius and an outer radius of the confinement ring and includes an extension section extending to the lower inner radius. A top surface of the lower horizontal section provides an angle downward toward the lower inner radius. The vertical section is disposed between the outer radius and the inside radius of the confinement ring. The vertical section connects the upper horizontal section of the confinement ring to the lower horizontal section.

Description

Technical Field

[0001] The invention relates to a confinement ring for a semiconductor process module. Background Art

[0002] In semiconductor processing, substrates undergo various operations to form features that define integrated circuits. For example, for a deposition operation, a substrate is received into a processing chamber, and depending on the type of feature to be formed, a specific type of reactive gas is supplied to the chamber, and RF power is applied to generate a plasma. The substrate is received on a substrate support (e.g., an electrostatic chuck) defined on a lower electrode. An upper electrode, such as a showerhead, is used to provide a specific type of reactive gas into the processing chamber. RF power is applied to the reactive gas through a corresponding matching network to generate a plasma, which is used to selectively deposit ions on the surface of the substrate to form microscopic features. The reactive gas produces byproducts, such as particles and gases, which need to be quickly removed from the plasma chamber to maintain the integrity of the microscopic features formed on the surface of the substrate.

[0003] In order to confine the generated plasma within the process region, a set of confinement rings are defined to surround the process region. In addition, in order to improve throughput and ensure that most of the plasma is located on the substrate received for processing, the confinement rings surrounding the plasma region can be designed to extend the process region so as to cover not only the area above the substrate but also the area above the edge ring that is disposed around the substrate (when it is received for processing) and the outer confinement ring that is disposed adjacent to the edge ring. The set of confinement rings is used not only to confine the plasma within the process region, but also to protect the internal structure of the process chamber, including protecting the chamber walls.

[0004] The integrity of features formed on the surface of the substrate depends on uniform plasma density in the process region. The plasma uniformity can be adjusted by adjusting the shape of the confinement ring (e.g., C-shield) to increase the volume of the process region. However, any changes to the shape or design of the confinement ring, for example, to increase the size of the volume in the confinement ring, may require significant changes to the hardware used in the process chamber, such as process chamber baffles, supporting hardware, etc.). Alternatively, changing the design of the confinement ring may result in compromised mechanical strength or shorten the useful life of the confinement ring.

[0005] It is in this context that embodiments of the present invention are proposed. Summary of the invention

[0006] Various embodiments of the present invention define the design of a confinement ring used in a plasma processing chamber for confining plasma within a plasma region. The confinement ring is defined as including an upper horizontal section extending between an outer radius and an upper inner radius, a lower horizontal section extending between an outer radius and a lower inner radius, and a vertical section extending between the bottom surface of the upper horizontal section and the top surface of the lower horizontal section defined at the outer radius. The top surface of the lower horizontal section of the confinement ring is defined by a slope defined by an angle provided along the top surface downward toward the lower inner radius. The slope causes the thickness of the lower horizontal section to be different, wherein the thickness of the lower horizontal section near the inner radius of the confinement ring is greater than the thickness of the lower horizontal section at the lower inner radius. In some embodiments, the bottom surface of the lower horizontal section is defined as being flat. Alternatively, in addition to defining a slope on the top surface, a second slope is also defined along the bottom surface of the lower horizontal section. The second slope is formed by a second angle provided along the bottom surface downward toward the lower inner radius. The second slope at the bottom surface can be defined by adding additional material for the confinement ring. In some embodiments, forming the second slope along the bottom surface of the lower horizontal segment causes the thickness of the lower horizontal segment near the inner radius to be equal to the thickness of the lower horizontal segment at the lower inner radius. In alternative embodiments, forming the second slope along the bottom surface of the lower horizontal segment can cause the thickness of the lower horizontal segment near the inner radius to be different from the thickness of the lower horizontal segment near the lower inner radius. Modifying the shape of the confinement ring by including an inclined geometry of the lower horizontal segment helps to adjust the plasma uniformity within the plasma region without redesigning other hardware components of the plasma processing chamber. In addition, the modifications made to the lower horizontal segment (e.g., defining an inclined surface along the top and bottom surfaces of the lower horizontal segment) avoid adversely affecting the mechanical strength or service life of the consumable confinement ring.

[0007] The lower horizontal section includes a plurality of grooves defined along the length of the lower horizontal section. Each groove is defined to extend radially from the inner diameter to the outer diameter along the lower horizontal section and vertically between the top surface and the bottom surface of the lower horizontal section. A plurality of grooves are used to remove byproducts and neutral gas species generated in the plasma region while ensuring that the plasma is optimally confined in the plasma region. In some embodiments, each groove may be defined to include a parallel groove geometry because the inner groove radius defined at the inner diameter is equal to the outer groove radius defined at the outer diameter. In an alternative embodiment, in addition to including an inclined geometry for the lower horizontal section, a plurality of narrow grooves are defined using a tapered groove geometry. The geometry of the tapered groove is beneficial because the groove experiences different wear along the length of the groove due to continuous exposure to the plasma. The tapered groove geometry helps to optimize the limited space between the management grooves while increasing the service life of the confinement ring.

[0008] For example, the wear of the slot is greater at the inner diameter than at the outer diameter. This uneven wear can be attributed to the change in plasma volume near the inner diameter of the slot as opposed to the outer diameter. When the wear reaches a critical dimension, the confinement ring needs to be replaced to ensure that plasma unconfinement does not occur. The tapered geometry of the slot helps to address the uneven wear while extending the service life of the confinement ring. The tapered slot geometry effectively utilizes the area around the slot by defining a narrow end at the inner diameter and a wider end at the outer diameter. The tapered geometry allows the narrow end of the slot to approach the critical dimension at approximately the same time as the wide end of the slot, resulting in the entire slot length reaching the critical confinement dimension at the end of the service life. The tapered slot geometry effectively utilizes the area around the slot, especially at the outer diameter, thereby extending the service life of the confinement ring while maintaining optimal plasma confinement in the plasma region. Therefore, as the number of process cycles that the confinement ring can be used for in the plasma processing chamber increases, the cost associated with the consumable confinement ring decreases. Thus, by modifying the confinement ring structure (ie, including the tapered slot profile and the sloped lower horizontal section), the original life expectancy of the confinement ring is maintained (ie, the life of the confinement ring is not compromised) without requiring redesign of other plasma processing chamber hardware components.

[0009] In one embodiment, a confinement ring for a plasma processing chamber is disclosed. The confinement ring includes an upper horizontal section, a lower horizontal section, and a vertical section. The upper horizontal section extends between an upper inner radius and an outer radius of the confinement ring. The lower horizontal section extends between a lower inner radius and an outer radius of the confinement ring. The top surface of the lower horizontal section provides an angle downward toward the lower inner radius, wherein the angle defines a slope along the top surface. The lower horizontal section includes an extension section extending downward along the lower inner radius. The vertical section is disposed between the outer radius and the inside radius of the confinement ring. The vertical section connects the upper horizontal section and the lower horizontal section of the confinement ring.

[0010] In one embodiment, the bottom surface of the lower horizontal section is flat such that a first thickness of the lower horizontal section near the inner radius is greater than a second thickness of the lower horizontal section at the lower inner radius.

[0011] In one embodiment, the first thickness is about 10% to about 40% greater than the second thickness.

[0012] In one embodiment, the angle defines a slope along the top surface of the lower horizontal segment. The slope is defined as being between about 0.20° and about 1° measured from the horizontal x-axis.

[0013] In one embodiment, the bottom surface of the lower horizontal segment provides a second angle downward toward the lower inner radius. The second angle defines a second slope. The second angle of the second slope defined on the bottom surface is equal to the angle of the slope defined on the top surface of the lower horizontal segment, so that the first thickness of the lower horizontal segment near the inner radius is equal to the second thickness of the lower horizontal segment defined at the lower inner radius.

[0014] In one embodiment, a first height defined between the bottom surface of the upper horizontal section and the top surface of the lower horizontal section near the inner radius is less than a second height defined between the bottom surface of the upper horizontal section and the top surface of the lower horizontal section at the lower inner radius of the confinement ring.

[0015] In one embodiment, the lower horizontal section, the upper horizontal section, and the vertical section are integrally connected to define a C-shaped structure configured to confine plasma generated in the plasma processing chamber.

[0016] In one embodiment, the lower horizontal section includes a plurality of grooves. Each groove of the plurality of grooves extends radially from an inner diameter to an outer diameter along the lower horizontal section. The inner groove radius of each groove at the inner diameter is equal to the outer groove radius at the outer diameter.

[0017] In one embodiment, the inner diameter of the groove is larger than the inner ring diameter defined by the lower inner radius, and the outer diameter of the groove is smaller than the outer ring diameter defined by the outer radius of the confinement ring.

[0018] In one embodiment, the lower horizontal section includes a plurality of grooves. Each groove of the plurality of grooves extends radially from the inner diameter to the outer diameter along the lower horizontal section. The inner groove radius of each groove at the inner diameter is smaller than the outer groove radius at the outer diameter.

[0019] In one embodiment, the difference between the inner groove radius and the outer groove radius of each groove defines the groove taper, so that each groove tapers from the outer diameter to the inner diameter. The size of the inner groove radius and the outer groove radius that affect the groove taper is determined as the inverse of the wear rate at the corresponding groove inner diameter and outer diameter. The ratio of the inner groove radius to the outer groove radius is between about 1:1.1 and about 1:1.5.

[0020] In one embodiment, the upper inner radius of the confinement ring is greater than the lower inner radius.

[0021] In one embodiment, the extension section defined in the lower horizontal section extends vertically downward at the lower inner radius.

[0022] In one embodiment, the extension section defined in the lower horizontal section is defined by an inclined top section and a vertical bottom section. The inclined top section provides a third angle downward at a downwardly inclined point defined on the top surface of the lower horizontal section at the lower inner radius, and the vertical bottom section is defined to extend downward from the bottom of the inclined top section.

[0023] In one embodiment, the top surface of the upper horizontal section includes a plurality of holes. Each hole of the plurality of holes is configured to receive a portion of a fastening device defined on a bottom surface of the upper electrode for coupling the confinement ring to the upper electrode of the plasma processing chamber.

[0024] In one embodiment, the extended section of the lower horizontal section is configured to rest on a radio frequency gasket defined on a top surface of a lower electrode of the plasma processing chamber.

[0025] In another alternative embodiment, a confinement ring for a plasma processing chamber is disclosed. The confinement ring includes an upper horizontal section, a lower horizontal section, and a vertical section. The upper horizontal section extends between an upper inner radius and an outer radius of the confinement ring. The lower horizontal section extends between a lower inner radius and an outer radius of the confinement ring. The top surface of the lower horizontal section provides a first angle downward toward the lower inner radius to define a first slope along the top surface. The bottom surface of the lower horizontal section provides a second angle downward toward the lower inner radius to define a second slope along the bottom surface. The lower horizontal section includes an extension section extending downward along the lower inner radius. The vertical section is disposed between the outer radius and the inner radius of the confinement ring. The vertical section connects the upper horizontal section of the confinement ring to the lower horizontal section.

[0026] In one embodiment, the first angle of the first slope is equal to the second angle of the second slope.

[0027] In one embodiment, a first thickness of the lower horizontal segment near the inner radius is equal to a second thickness of the lower horizontal segment at the lower inner radius. A first height defined between a bottom surface of the upper horizontal segment and a top surface of the lower horizontal segment near the inner radius is less than a second height defined between a bottom surface of the upper horizontal segment and a top surface of the lower horizontal segment at the lower inner radius.

[0028] In one embodiment, the lower horizontal section includes a plurality of grooves. Each groove of the plurality of grooves extends radially from an inner diameter to an outer diameter along the lower horizontal section. The inner groove radius of each groove at the inner diameter is equal to the outer groove radius of each groove at the outer diameter. The inner diameter of each groove is greater than the inner ring diameter of the confinement ring defined by the lower inner radius, and the outer diameter of the groove is less than the outer ring diameter of the confinement ring defined by the outer radius.

[0029] In one embodiment, the lower horizontal section includes a plurality of grooves. Each groove of the plurality of grooves extends radially from the inner diameter to the outer diameter along the lower horizontal section. The inner groove radius of each groove at the inner diameter is smaller than the outer groove radius at the outer diameter.

[0030] In yet another alternative embodiment, a plasma processing chamber for confining plasma therein is disclosed. The plasma processing chamber includes a lower electrode for supporting a substrate and an upper electrode disposed above the lower electrode. The plasma processing chamber includes a confinement ring disposed between the lower electrode and the upper electrode. The confinement ring includes an upper horizontal section, a lower horizontal section, and a vertical section. The upper horizontal section extends between an upper inner radius and an outer radius of the confinement ring. The lower horizontal section extends between a lower inner radius and an outer radius of the confinement ring. The top surface of the lower horizontal section provides an angle downward toward the lower inner radius. The angle defines a slope along the top surface. The lower horizontal section has an extension section extending downward along the lower inner radius. The vertical section is disposed between the outer radius and the inside radius of the confinement ring. The vertical section connects the upper horizontal section and the lower horizontal section of the confinement ring.

[0031] In one embodiment, the bottom surface of the lower horizontal section provides a second angle downward toward the lower inner radius. The second angle defines a second slope along the bottom surface. The second angle of the second slope defined along the bottom surface is equal to the angle of the slope defined by the top surface of the lower horizontal section.

[0032] In one embodiment, the lower horizontal section includes a plurality of grooves. Each groove in the plurality of grooves is designed to extend radially from the inner diameter to the outer diameter along the lower horizontal section. The inner groove radius of each groove at the inner diameter is smaller than the outer groove radius of each groove at the outer diameter.

[0033] In one embodiment, each groove has an inner diameter greater than an inner ring diameter defined by a lower inner radius of the confinement ring, and an outer diameter of the groove is less than an outer ring diameter defined by an outer diameter of the confinement ring.

[0034] In one embodiment, the upper inner radius of the confinement ring is greater than the lower inner radius.

[0035] In one embodiment, the lower horizontal section, the vertical section and the upper horizontal section of the confinement ring define a continuous C-shaped structure for confining plasma in a plasma region defined in a plasma processing chamber. The confinement ring is made of one of silicon or polysilicon or silicon carbide or boron carbide or ceramic or aluminum.

[0036] In one embodiment, the extension section is integrally formed with the lower horizontal section, the vertical section, and the upper horizontal section of the confinement ring. The extension section is configured to extend vertically below a bottom surface of the lower horizontal section.

[0037] In one embodiment, the upper electrode is electrically grounded and the lower electrode is connected to a radio frequency power source through a corresponding matching network. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 An enlarged vertical cross-sectional view of a portion of a plasma processing chamber in which a confinement ring having a tapered geometry defined along a top surface of a lower horizontal section is shown according to one embodiment.

[0039] Figure 2A An exemplary confinement ring having a tapered geometry defined along a top surface of a lower horizontal section is shown according to one embodiment.

[0040] Figure 2B Shows Figure 2A An alternative embodiment of a confinement ring is shown in FIG. 2 , wherein both the top and bottom surfaces of the lower horizontal section of the confinement ring define a conical geometry.

[0041] Figure 2C Shows Figure 2A An alternative embodiment of a confinement ring is shown in , wherein the top section of the extension section has a straight profile.

[0042] Figure 3 A representative graph of the variation in plasma density as it corresponds to an oxide cap etch rate across a radius of a substrate surface (when present) is shown according to one embodiment.

[0043] Figure 4A An expanded view of a portion of a confinement ring having a tapered geometry along a top surface of a lower horizontal section and a plurality of grooves having parallel groove profiles defined along the lower horizontal section is shown according to one embodiment.

[0044] Figure 4B Shows Figure 4A An alternative implementation of a confinement ring is shown in , wherein the top and bottom surfaces along the lower horizontal section have tapered geometries, and a plurality of grooves having tapered geometries are defined along the lower horizontal section of the confinement ring.

[0045] Figure 5A An expanded view of the tapered geometry of the slot defined along the lower horizontal section of the confinement ring is shown according to one implementation.

[0046] Figure 5B An expanded view of a starting profile of a groove having a tapered geometry and the groove wear profile at the end of the life of a confinement ring is shown according to one embodiment.

[0047] Figure 6 is a top perspective view of a confinement ring according to one embodiment. DETAILED DESCRIPTION

[0048] In various implementations described herein, a confinement ring for a plasma processing chamber is designed to increase the useful life of the confinement ring while ensuring optimal plasma confinement in a plasma region defined in the plasma processing chamber. The confinement ring for a plasma processing chamber includes an upper horizontal section, a vertical section, and a lower horizontal section. The upper horizontal section is defined as extending from an outer radius to an upper inner radius, and the top and bottom surfaces of the upper horizontal section are defined as flat. The lower horizontal section is defined as extending from an outer radius to a lower inner radius. The vertical section is disposed between the outer radius and the inner radius of the confinement ring and connects the upper horizontal section and the lower horizontal section of the confinement ring. The top surface of the lower horizontal section includes a conical geometry to define a slope that slopes downward toward the lower inner radius. The slope defined on the top surface causes a change in the thickness of the lower horizontal section and the lower inner radius of the confinement ring near the inner radius. In addition, the slope causes a change in the height of the gap defined between the bottom surface of the upper horizontal section and the top surface of the lower horizontal section near the inner radius and at the lower inner radius. The change in height causes an increase in the volume of plasma generated in the plasma region, particularly in the region covered by the confinement ring (e.g., above an edge exclusion region of the substrate and in the region above an edge ring surrounding the substrate when the substrate is present in the plasma processing chamber).

[0049] Increasing the gap in the confinement ring has a positive effect on plasma uniformity. The uniformity of the plasma can be attributed to the change in plasma diffusion caused by the increase in volume within the plasma region. Therefore, the plasma uniformity can be modulated by changing the shape of the confinement ring used to confine the plasma in the plasma region without redesigning other hardware components of the plasma processing chamber. Existing methods of changing the traditional design of the confinement ring require major changes to the hardware, otherwise the mechanical strength will be compromised, thus affecting the service life of the confinement ring.

[0050] Selective changes are made to the confinement rings (e.g., including a slope along a lower horizontal section of the confinement ring) to increase the volume of the plasma. The changes made to the confinement rings do not require changes to any other hardware components within the plasma processing chamber (e.g., chamber diaphragms, mating hardware, etc.) because the changes made to the confinement ring structure do not substantially deviate from the overall structure of the confinement ring. In some implementations, additional modifications can be made to the bottom surface of the lower horizontal section by including a slope to improve the mechanical strength of the confinement ring and the overall life of the confinement ring. The slope can be defined in the bottom surface by adding additional material of the confinement ring along the length of the bottom section to provide an angle downward toward the lower inner radius. The additional material in the bottom surface is designed to increase the thickness of the lower horizontal section to provide overall thickness uniformity along the length of the lower horizontal section while continuing to maintain the slope at the lower horizontal section.

[0051] The lower horizontal section includes a plurality of grooves for effectively removing byproducts from the plasma region while maintaining plasma confinement in the plasma region. The narrow groove is defined as extending longitudinally from the inner diameter to the outer diameter along the lower horizontal section, and extending in the depth direction between the top surface and the bottom surface of the lower horizontal section to provide a conduit for the byproducts of the plasma region. In some embodiments, the groove may be defined as a parallel groove geometry including a length, wherein the inner groove radius at the inner diameter is the same as the outer groove radius at the outer diameter. In an alternative embodiment, the groove may be defined as including a tapered groove geometry, so that the groove is narrow at the inner diameter and wide at the outer diameter. The side with a wider outer diameter has a wider outer groove radius, and the side with a narrower inner diameter has a narrower inner groove radius. The size of the inner groove radius at the inner diameter of each groove and the outer groove radius at the outer diameter is determined as the inverse of the wear rate at the corresponding inner diameter and outer diameter. By starting with a narrower groove at the inner diameter, more wear is allowed to occur at the inner diameter before reaching the critical size of plasma non-confinement. At the end of service life, the smaller inner groove radius at the ID compensates for the high wear rate at the ID, while the wider outer groove radius compensates for the low wear rate at the OD, resulting in a straight groove profile along the length of the groove. The difference in inner and outer groove radius causes each groove to reach its restraint limit simultaneously along the entire groove length. The tapered groove may result in some open area along the narrow sides. To compensate for the open area along the narrow sides, the total number of grooves can be increased. The increase in the total number of grooves takes into account the expected amount of wear along the narrow sides of the tapered groove.

[0052] The improved confinement ring structure having an inclined geometry along the length of the lower horizontal section and a tapered slot geometry defining a plurality of slots along the length of the lower horizontal section results in: (a) an overall improvement in plasma uniformity, (b) effective removal of byproducts, and (c) an overall increase in confinement ring life. The above advantages can be achieved without redesigning other hardware components (e.g., chamber diaphragm, mating hardware, etc.) within the plasma processing chamber. With the above overview of the invention, specific embodiments will now be described with reference to the various drawings.

[0053] Figure 1 A simplified block diagram of a portion of a plasma processing chamber 100 using a confinement ring for confining plasma in one embodiment is shown. In one embodiment, the plasma processing chamber 100 can be a capacitively coupled plasma (CCP) processing chamber (or hereinafter referred to as a "plasma processing chamber"), which includes a lower electrode 104 to provide radio frequency (RF) power to the plasma processing chamber 100, and an upper electrode 102 to provide a process gas to generate plasma within the plasma processing chamber 100. The lower electrode 104 is connected to an RF power source 106 through a corresponding matching network 107, wherein a first end of the RF power source 106 is connected to the matching network 107, and a second end of the RF power source 106 is electrically grounded. The RF power source 106 may include one or more RF power generators (not shown).

[0054] In one embodiment, the top surface of the lower electrode 104 defines a substrate support surface on which the substrate 110 is received for processing. When receiving the substrate 110 for processing, the substrate support surface adjacent to the lower electrode 104 defines an edge ring 112 to surround the substrate 110. When the substrate is supported on the substrate support surface of the lower electrode 104, the top surface of the edge ring 112 is defined to be coplanar with the top surface of the substrate 110. The edge ring 112 is configured to extend the processing region (represented by the plasma region 108) for the plasma generated within the plasma processing chamber 100 to extend over an area beyond the edge of the substrate to an extended processing region covering the outer edge of the edge ring 112 and beyond the outer edge. One or more dielectric rings 120 are disposed adjacent to the outer edge of the edge ring 112. The RF power supply 106 is connected to the bottom of the lower electrode through the matching network 107 and provides RF power to the plasma processing chamber 100. The ground ring 122 is disposed adjacent to and below a portion of the one or more dielectric rings 120 and is configured to surround the lower electrode 104. The support structure 118 is disposed as part of a ground ring 122 surrounding the lower electrode 104. The RF gasket 116 is disposed on a top surface of the support structure 118. In some embodiments, the RF gasket 116 can be disposed within a channel defined on the top surface of the support structure 118. The support structure 118 can be made of a quartz element or any other insulating material suitable for use in the plasma processing chamber 100.

[0055] In one embodiment, the upper electrode 102 may be a showerhead including one or more inlets (not shown) connected to one or more process gas sources (not shown) and a plurality of outlets distributed on a bottom surface of the upper electrode 102 facing the lower electrode 104. The plurality of outlets are configured to supply process gas from the one or more process gas sources to a plasma processing region (or simply referred to as a “plasma region”) 108 defined between the upper electrode 102 and the lower electrode 104. The upper electrode 102 may be composed of a plurality of electrodes. Figure 1 One such embodiment is illustrated, in which the upper electrode 102 includes an inner upper electrode 102a disposed at the center and an outer electrode 102b disposed adjacent to and surrounding the inner upper electrode 102a. In this embodiment, the upper electrode 102 is electrically grounded to provide a grounded return path for the RF power supplied to the plasma processing chamber 100. The outer electrode 102b includes a plurality of fastening devices (not shown) disposed along the bottom surface. The fastening devices are used to couple the upper electrode 102 to the confinement ring 140.

[0056] A confinement ring structure (or hereinafter simply referred to as "confinement ring") 140 is disposed between the upper electrode 102 and the lower electrode 104. The confinement ring 140 defines a confinement chamber volume in which the plasma generated in the chamber is fully controlled. The confinement chamber volume defines a plasma region 108. The confinement ring 140 is a C-shaped structure with a C-shaped opening facing the interior of the plasma region 108, which is defined between the upper electrode 102 and the lower electrode 104 of the processing chamber 100. Based on the shape of the confinement ring 140 and the function of confining the plasma in one area, the confinement ring may also be referred to as a "C-shaped shield". The confinement ring 140 is used to confine the plasma within the extended plasma region 108 in the plasma processing chamber 100. The confinement ring 140 is configured to be coupled to the outer electrode 102b, which is a part of the upper electrode 102, at the top. The confinement ring 140 is a part of the upper electrode 102 and the bottom section of the confinement ring 140 is configured to rest on the top surface of the support structure 118 of the lower electrode 104. The RF gasket 116 is disposed on the top surface of the support structure 118 to provide a tight coupling between the upper electrode 102 and the lower electrode 104 when the plasma processing chamber 100 is to be used for processing. The RF gasket 116 ensures that the coupling between the upper electrode 102 and the lower electrode 104 is airtight. In one embodiment, the support structure 118 is configured to surround the lower electrode 104 including at least the substrate support surface, the edge ring 112, one or more dielectric rings 120, and the ground ring 122.

[0057] It should be noted that Figure 1 The plasma processing chamber is shown as including only certain parts, but in reality the plasma processing chamber includes multiple additional components required to process the substrate. In addition, Figure 1 The various components shown may not be drawn to scale and / or may be exaggerated in order to identify different features of the various components.

[0058] In general, confinement ring 140 includes an upper horizontal section 141, a vertical section 142, and a lower horizontal section 143. Upper horizontal section 141 extends a first length and is defined by a bottom surface 141a facing plasma region 108 and a top surface 141b facing away from plasma region 108. A plurality of holes are distributed on top surface 141b to receive fastening means defined on the bottom surface of outer electrode 102b when confinement ring 140 is coupled to upper electrode 102. In one embodiment, bottom surface 141a and top surface 141b of upper horizontal section 141 are substantially flat (i.e., horizontal). In another embodiment, a first step 148a is defined on top surface 141b of upper horizontal section 141 at an inner edge of upper horizontal section 141. The first step 148a can be used to receive the outer electrode 102b and can be used to provide a secure fit of the confinement ring 140 when the confinement ring 140 is coupled to the outer electrode 102b. In the present embodiment, the bottom surface 141a of the upper horizontal segment 141 is substantially flat. In yet another embodiment, the first step 148a is defined on the top surface 141b of the upper horizontal segment 141, and the second step 148b is defined on the bottom surface 141a of the upper horizontal segment 141 at the inner edge of the upper horizontal segment 141. In the present embodiment, the first step 148a and the second step 148b can both extend a certain height. In another embodiment, the first step 148a can extend a first height and the second step 148b can extend a second height. In another embodiment, the bottom surface 141a of the upper horizontal segment 141 provides an angle upward toward the upper inner radius 151 to define a slope along the upper horizontal segment. In one example, the inclination angle on the bottom surface of the upper horizontal section may be defined as greater than 0° and less than 1°, although other ranges of inclination are also contemplated.

[0059] Vertical section 142 includes an inner surface 142a facing plasma region 108 and an outer surface 142b facing away from plasma region 108 and toward the inside of the wall of processing chamber 100. In one embodiment, inner surface 142a and outer surface 142b of vertical section 142 are vertical. Figure 1 An example is shown in which the inner surface 142a and the outer surface 142b of the vertical section 142 are vertical. In another embodiment, the inner surface 142a of the vertical section 142 is arcuate, and the outer surface 142b of the vertical section 142 is vertical. In yet another embodiment, both the inner surface 142a and the outer surface 142b of the vertical section 142 are arcuate.

[0060] The lower horizontal segment 143 extends a second length and is defined by a top surface 143a facing the plasma region 108 and a bottom surface 143b facing away from the plasma region 108. The top surface 143a of the lower horizontal segment 143 slopes downward from the vertical segment toward the inner edge of the lower horizontal segment 143. The slope in the lower horizontal segment 143 results in a change in the height of the gap defined between the upper horizontal segment 141 and the lower horizontal segment 143. In some embodiments, a first height "h1" defined between the upper horizontal segment 141 and the lower horizontal segment 143 near the vertical segment 142 is less than a second height "h2" defined between the upper horizontal segment 141 and the lower horizontal segment 143 near the inner edge of the lower horizontal segment 143. In addition, the lower horizontal section 143 includes an extension section 144, which is disposed at the inner side edge of the lower horizontal section 143 and extends downward from the bottom surface 143b of the lower horizontal section 143. Figure 1 As shown, the extension section 144 includes a straight inner side surface.

[0061] In one embodiment, the upper horizontal section 141, the vertical section 142, and the lower horizontal section 143 may be integrally connected to define a C-shaped structure. In another embodiment, the upper horizontal section 141, the vertical section 142, and the lower horizontal section 143 may be three separate parts, wherein the bottom surface of the upper horizontal section 141 is designed to rest on the top of the vertical section 142 and coupled to the top surface of the vertical section 142. The bottom surface of the vertical section 142 is designed to rest on the top of the lower horizontal section 143 and coupled to the top surface 143a of the lower horizontal section 143. The upper horizontal section 141, the vertical section 142, and the lower horizontal section together form a C-shaped structure for confining the plasma generated within the plasma processing chamber 100 in the plasma region 108.

[0062] Figure 2A An enlarged cross-sectional view of a confinement ring 140 used in a plasma processing chamber 100 is shown in one embodiment. Figure 2AThe annotations of identify various reference points of confinement ring 140. As described above, confinement ring 140 is a C-shaped structure and includes an upper horizontal section 141, a vertical section 142, a lower horizontal section 143, and an extension section 144. Upper horizontal section 141 extends between outer radius 150 and upper inner radius 151 of confinement ring 140 and includes a bottom surface 141a and a top surface 141b. The bottom surface 141a and the top surface 141b of upper horizontal section 141 may or may not include a step at the upper inner radius 151. Bottom surface 141a faces plasma region 108 and top surface 141b faces away from plasma region 108. Top surface 141b of upper horizontal section 141 includes a plurality of fastening holes (or simply "holes" - not shown) uniformly distributed in a circular direction and defined to align with corresponding fastening means provided along the bottom surface of outer electrode 102b. The fastening means of outer electrode 102 b and the fastening holes on the top surface 141 b of outer electrode 102 b are defined to couple confinement ring 140 to upper electrode 102 .

[0063] The vertical section 142 of the confinement ring is disposed between the outer diameter 150 and the inner diameter 153 of the confinement ring 140. The vertical section 142 includes an inner surface 142a facing the inner side of the plasma region 108 and an outer surface 142b facing away from the plasma region 108. One or both of the inner surface 142a and the outer surface 142b of the vertical section 142 can be vertical or arcuate. The vertical section extends a certain height between the upper horizontal section 141 and the lower horizontal section 143 to define a gap for confining the plasma. In some embodiments, the vertical section 142 couples the upper horizontal section 141 to the lower horizontal section 143 to define a C-shaped structure.

[0064] Lower horizontal section 143 extends between outer diameter 150 and lower inner radius 152 of confinement ring 140. In one embodiment, lower inner radius 152 of confinement ring 140 is smaller than upper inner radius 151 of confinement ring 140. Lower horizontal section includes top surface 143a and bottom surface 143b. Top surface 143a of lower horizontal section 143 is defined to provide an angle downward toward lower inner radius 152, while bottom surface 143b of lower horizontal section 143 is defined to be flat. The angle defines a slope along top surface 143a of lower horizontal section 143. In one embodiment, the slope starts near inner radius 153 of confinement ring and extends toward lower inner radius 152. Top surface 143a having a slope and bottom surface 143b having a flat profile result in a thickness that varies along the length of lower horizontal section 143. For example, the slope along top surface 143a results in a first thickness "T1" near inner radius 153 of confinement ring 140 and a second thickness "T2" near lower inner radius 152 of confinement ring 140, wherein T1>T2. In one embodiment, first thickness T1 is defined to be about 10% to about 40% greater than second thickness T2. In addition, the variation in thickness results in a variation in the height of a gap defined between bottom surface 141a of upper horizontal segment 141 and top surface 143a of lower horizontal segment 143, wherein the gap defines plasma region 108. For example, the slope results in a first height "h1" defined near inner radius 153 of confinement ring 140 and a second height "h2" defined near lower inner radius 152, wherein the first height h1 is less than the second height h2.

[0065] In one embodiment, the inclination angle 147 defined by the slope in the lower horizontal section 143 relative to the horizontal x-axis can be defined as between about 0.20° and about 1°. The above range of the angle of the slope is provided by way of example only and should not be considered limiting. Therefore, in some embodiments, it is contemplated that the angle of the slope is greater than or less than this range, and such an increase or decrease in angle can be based on the internal dimensions of the plasma processing chamber 100, the type of process being performed, the type of process gas used to generate the plasma, the type of byproducts and neutral gas species generated and to be removed, the inlet and outlet of the plasma processing chamber, etc. In one embodiment, the confinement ring is made of silicon. In other embodiments, the confinement ring can be made of polysilicon, or silicon carbide, or boron carbide, or ceramic, or aluminum, or any other material capable of withstanding the processing conditions of the plasma region 108.

[0066] The lower horizontal section 143 includes an extended section 144' defined at the lower inner radius 152. Figure 2AIn the embodiment shown, the extension section 144' includes an inclined top section 144a and a vertical bottom section 144b. This design of the extension section 144 is different from Figure 1 The design used in Figure 1 The extended section 144 includes a straight inner surface of the extended section, and Figure 2A The extension section includes an inclined portion of the top of the extension section 144'. The inclined top section 144a defined by the downwardly inclined point 149 is inclined at a certain angle, wherein the downwardly inclined point 149 is defined at the intersection of the top surface 143a and the inner surface of the lower inner radius 152. The inclination angle of the inclined top section 144a can be between about 0° and about 10°. The above range is provided as an example and should not be considered to be limiting or exhaustive. The vertical bottom section 144b is disposed below the inclined top section 144a and extends vertically downward beyond the height of the bottom surface 143b of the lower horizontal section 143. The extension section 144' provides continuity with the lower horizontal section 143. The vertical bottom section 144b is configured to rest on the RF gasket 116, which is disposed on the top surface of the support structure 118 defined in the lower electrode 104.

[0067] Figure 2B In one embodiment, Figure 2A A design variation of the confinement ring 140 is shown in FIG. Figure 2B The confinement ring 140′ in the embodiment includes a slope defined along the bottom surface 143b of the lower horizontal section 143 in addition to the slope defined on the top surface 143a of the lower horizontal section 143 of the confinement ring 140. Figure 2A and 2B Identical components are denoted by the same reference numerals and function in a similar manner. The bottom surface 143b of the lower horizontal section 143 is defined to provide a second angle downward toward the lower inner radius 152 to define a second slope along the bottom surface 143b of the lower horizontal section 143. Similar to Figure 2A In one embodiment, the second slope is defined as starting from near the inner radius 153 of the confinement ring and extending to the lower inner radius 152. In one embodiment, the second angle of the second slope defined along the bottom surface 143b of the lower horizontal section 143 is equal to the angle of the slope defined along the top surface 143a of the lower horizontal section 143. For example, the second slope is defined as between about 0.20° and about 1°. In this embodiment, the thickness of the lower horizontal section 143 is uniform along the length of the lower horizontal section 143.

[0068] In another embodiment, the second angle of the second slope defined along the bottom surface 143b can be different from the slope defined along the top surface 143a. For example, the second angle of the second slope can be greater than the angle of the slope along the top surface 143a, thereby causing the thickness to vary along the length of the lower horizontal section 143. In this embodiment, the thickness T1 near the inner radius 153 can be less than the thickness T2 near the lower inner radius 152. This embodiment is Figure 2A A variation of the embodiment shown in which the thickness varies along the length of the lower horizontal section 143. For example, the thickness T1 near the inner radius 153 is less than the thickness T2 near the lower inner radius 152, while Figure 2A In the embodiment of FIG. 1 , the thickness T1 near the inner radius 153 is greater than the thickness T2 near the lower inner radius 152 . This can accommodate the additional wear expected at the lower inner radius 152 due to exposure to the plasma in the plasma region 108 .

[0069] Figure 2C Pictured Figure 2A 14. In this embodiment, the extension section 144 is defined by a top section 144a' and a vertical bottom section 144b. The top section 144a' is shown as including a straight line profile along the inside surface disposed at the lower inner radius 152, rather than Figure 2A The inclined top section shown in Figure 2C In the illustrated embodiment, the top segment 144a' extends downward at the lower inner radius 152 to the bottom surface 143b of the lower horizontal segment 143, and the vertical bottom segment 144b is an extension of the top segment 144a', wherein the vertical bottom 144b extends below the bottom surface 143b of the lower horizontal segment 143 of the confinement ring 140.

[0070] Figures 2A-2C The illustrated embodiment shows a vertical cross-sectional view of confinement ring 140 wherein a ramp is defined along top surface 143a and along top surface 143a and bottom surface 143b. Figure 2A and 2B The cross-sectional view of FIG. 1 also shows grooves 145 defined along the length of lower horizontal section 143 of confinement ring 140. Confinement ring 140 includes a plurality of grooves evenly distributed along lower horizontal section 143 of confinement ring 140, wherein each groove extends between the inner diameter and the outer diameter in the length direction and extends between the top surface 143a and the bottom surface 143b of the lower horizontal section in the depth direction. Details related to the geometry of the grooves will be referred to in Figure 4A and 4B A plurality of slots 145 defined along the lower horizontal section 143 provide conduits for byproducts to escape the plasma region while optimally confining the plasma within the plasma region.

[0071] Figure 3 A graph identifying changes in etch rate due to plasma density variations across the radius of the substrate when using a confinement ring having a sloped geometry defined in the lower horizontal section 143 in one embodiment is shown. The graph shows the oxide capping etch rate on the surface of a substrate processed using a confinement ring having a sloped geometry as described in various embodiments. The capping etch rate represents a reasonable measure of the plasma density on the surface of the substrate. Graph line 301 shows the change in etch rate on the surface of the substrate when a confinement ring without a slope is used, and graph line 302 shows the change in etch rate on the surface of the substrate when a confinement ring having a slope defined along the lower horizontal section 143 is used. The etch rate represented along graph line 301 shows more variation along the length of the substrate until the edge exclusion region defined by line 304. The variation in etch rate is more apparent in graph line 301 for a 150 mm substrate for radii between about 70 mm and about 135 mm, as can be seen in box 303. For example, the etch rate shows a gradual decrease along the substrate surface until the midpoint of the radius (i.e., up to about 70 mm), after which the etch rate begins to increase significantly until the edge exclusion region of the substrate. On the other hand, graph line 302 shows that the etch rate gradually decreases along the length of the substrate surface until the edge exclusion region. The gradual decrease in etch rate shown in graph line 302 is assumed to be due to changes in plasma diffusion in the increased plasma volume caused by the increase in the gap defined between the upper horizontal segment and the lower horizontal segment of confinement ring 140.

[0072] In one embodiment, the amount of inclination along the lower horizontal section can be defined as increasing the first height 'h1' and the second height 'h2' (i.e., the gap defined between the upper horizontal section 141 and the lower horizontal section 143) by about +2mm to about +8mm. The effect of this increase on the overlying layer etching rate is shown by the graph line 302, particularly in the area covered by the box 303. As an example, a slope between about 0.55° and about 0.60° defined along the top surface 143a of the lower horizontal section 143 will result in a difference between the second height 'h2' and the first height 'h1' from about 0.60mm to about 0.65mm. In one embodiment, the upper inner radius 151 is defined between about 203mm (about 8 inches) and about 218.5mm (about 8.6 inches). In one embodiment, the lower inner radius 152 is defined between about 177mm (about 7 inches) and about 198.5mm (about 7.8 inches). In one embodiment, the inside radius 153 is defined between about 248 mm (about 9.8 inches) and about 262 mm (about 10.3 inches). In one embodiment, the outside radius is defined between about 254 mm (about 10 inches) and about 267 mm (about 10.5 inches). In one embodiment, the length of the groove 145 is defined between about 48 mm (about 1.9 inches) and about 61 mm (about 2.4 inches). In one embodiment, the depth (i.e., thickness T1) of the lower horizontal section 143a is defined between about 6 mm (about 0.25 inches) and about 8.4 mm (about 0.33 inches). In one embodiment, the slope defined on lower horizontal section 143a can result in a first height h1 between about 29 mm (about 1.18 inches) and about 31 mm (about 1.22 inches) and a second height between about 31 mm (about 1.22 inches) and about 32 mm (about 1.24 inches). In one embodiment, the thickness T2 caused by the slope on lower horizontal section 143a can be defined between about 5.8 mm (about 0.23 inches) and about 7.2 mm (about 0.28 inches). The above ranges for the various components of the confinement ring are provided by way of example only and should not be considered limiting. Other ranges for the various components or adjustments to the above ranges can be envisioned based on the internal dimensions of plasma processing chamber 100, the type of process being performed, the type of process gas used to generate the plasma, the type of byproducts and the type of neutral gas generated and to be removed, the inlet and outlet of the plasma processing chamber, the geometry of the hardware components of the plasma processing chamber, etc.

[0073] Figure 4A and 4BA variation of a confinement ring having a plurality of slots defined along the length of a lower horizontal section 143 of confinement ring 140 in some exemplary embodiments is shown. The plurality of slots 145 along the length of lower horizontal section 143 are used to effectively remove byproducts formed within plasma region 108 during processing of substrate 110. Figure 4A , each groove 145 of the plurality of grooves is shown extending radially between an inner diameter (ID) 145a and an outer diameter (OD) 145b of lower horizontal section 143. ID 145a of groove 145 is greater than an inner ring diameter (IRD) of lower horizontal section 143, wherein IRD is defined by lower inner radius 152 of lower horizontal section 143. OD 145b of groove 145 is defined as greater than ID 145a of groove 145 but less than an outer ring diameter (ORD) of confinement ring 140, wherein ORD is defined by outer radius 150 of confinement ring 140. In other words, groove 145 extends a length 'l' (i.e., l=OD-ID) that is less than a width 'w' of lower horizontal section 143 (i.e., w=ORD-IRD). Each groove 145 is defined using a parallel groove geometry, wherein an inner groove radius (ISR) 145c at an inner diameter (ID) 145a of the groove 145 is equal to an outer groove radius (OSR) 145d at an outer diameter (OD) 145b of the groove 145. Each groove 145 having a parallel groove geometry is defined to extend between a top surface 143a and a bottom surface 143b of the lower horizontal section 143.

[0074] Figure 4B An alternative embodiment of groove 145' is shown defined along the surface of lower horizontal section 143 of confinement ring 140". In this embodiment, groove 145' uses a tapered groove geometry rather than a Figure 4A The parallel groove geometry of the groove 145 in the embodiment of the present invention is defined by the parallel groove geometry of the groove 145 in the embodiment of the present invention. Figure 4ALikewise, each slot 145 ′ extends from an inner diameter (ID) 145 a to an outer diameter (OD) 145 b. ID 145 a is less than the IRD of the lower horizontal section 143 , where the IRD is defined by the lower inner radius 152 . OD 145b is greater than the IRD but less than the ORD of confinement ring 140″, where ORD is defined by outer radius 150. In this embodiment, each of the plurality of slots 145′ is defined using a tapered slot geometry to include a slot cone. The slot cone is formed by defining a narrow inner slot radius (ISR) 145c′ at ID 145a of slot 145′ and a wider outer slot radius (OSR) 145d′ at OD 145b of slot 145′. The variation in ISR 145c′ and OSR 145d′ causes each slot 145′ to be narrower at inner diameter ID 145a and wider at outer diameter OD 145b. To compensate for the narrow ISR at inner diameter ID 145a, in one embodiment, the length 'l' of slot 145′ may be increased to provide sufficient area for byproducts and neutral gas species to escape plasma region 108. In an alternative embodiment, the number of slots 145′ may be increased to compensate for the narrow ISR at ID 145a. A narrow ISR 145c' at 145a, wherein the number of grooves 145' increases corresponds to the wear of the grooves 145'.

[0075] The ISR 145c' and OSR 145d' of each slot 145' are sized to be the inverse of the wear rate at the corresponding inner and outer diameters (ID 145a, OD 145b) of the slot 145'. Due to the amount of plasma that different portions along the length of the slot 145' must be exposed to, the wear along the length of the slot 145' is non-uniform, with the area of ​​the slot 145' at the inner diameter wearing more than the area of ​​the slot 145' at the outer diameter. Making the slot narrower at ID 145a will increase the life of the confinement ring by offsetting the onset of reaching the critical width when plasma escapes through the slot. At the same time, making the outer diameter 145b of the slot larger ensures that gas conduction losses are not incurred due to the narrower ID 145a. The geometry of the tapered slot allows the wear of the slot 145' at ID 145a to reach the critical size at about the same time as the wear of the slot 145' at OD 145b. Even with the tapered slot geometry, the ISR and OSR are sized to remove byproducts and neutral gas species from plasma region 108. The tapered geometry used to define the slots extends the useful life of confinement ring 140'.

[0076] Figure 4A and 4BThe slots 145 and 145' shown in [Fig. 0] are not drawn to scale and are enlarged to illustrate the slot profile for defining the slots along the length of the lower horizontal section 143 of the confinement rings 140, 140". In some embodiments where the confinement ring 140 includes an inclined top surface 143a and an inclined bottom surface 143b along the length of the lower horizontal section 143, the angle of the bottom surface is defined to be equal to the angle on the top surface so as to keep the bottom surface parallel to the top surface. This design helps to improve the mechanical strength of the confinement ring 140, thereby increasing the service life. A further increase in the service life can be envisioned by using a tapered slot profile to define the slots along the lower horizontal section 143 of the confinement ring 140. The tapered slot profile for defining the slot 145, together with the inclined lower horizontal section 143, results in maintaining an optimal plasma density in the plasma region 108 so as to provide an optimal etching rate over the entire substrate surface, while ensuring that the wear of the slots along the length of the slots reaches the critical dimension approximately simultaneously.

[0077] Figure 5A An example of a tapered slot profile for defining a slot 145' along the lower horizontal section 143 of a confinement ring 140 used in a plasma processing chamber is shown in one embodiment. Figure 5A Also shown is the variation in the slot profile of the slot 145' defined using a tapered slot profile relative to the slot 145 defined using a parallel slot profile. The slot 145' with the tapered slot profile is shown in red, while the slot 145 with the parallel slot profile is shown in gray. As previously described, the slot 145' is defined to extend along the horizontal surface of the lower horizontal section 143 between an inner diameter (ID) 145a and an outer diameter (OD) 145b, where the ID 145a of the slot 145' is greater than the inner ring diameter (IRD) defined by the lower inner radius 152 of the lower horizontal section 143, and the OD 145b of the slot 145' is greater than the ID 145a but less than the outer ring diameter (ORD) of the confinement ring defined by the outer radius 150. The slot 145' (shown in red in [Fig. 0]) includes a wider or broader slot width at the outer diameter (OD) defined by the outer slot radius (OSR) 145d' and a narrower slot width at the inner diameter (ID) defined by the inner slot radius (ISR) 145c' (i.e., ISR145c' < OSR145d'). Due to the different wear of the slot along the slot length, the tapered geometry of the slot 145' provides more area for slot wear at the inner diameter than at the outer diameter, such that the tapered slot 145' as a whole can reach the critical dimension approximately simultaneously when the confinement ring 140' needs to be replaced. This is different from the slot 145 defined using a parallel slot profile (shown in gray in [Fig. 0]) Figure 5A which includes a relatively constant slot width along its length. Figure 5A145). Grooves 145 having parallel groove profiles define a consistent groove width along the length of groove 145, i.e., the inner groove width at ID 145a of groove 145 defined by ISR 145c is equal to the outer groove width at OD 145b defined by OSR 145d. Parallel groove profiles may result in uneven wear along the length of groove 145, requiring replacement of the entire confinement ring 140.

[0078] Therefore, in order to prevent premature replacement of confinement ring 140 and extend the service life of the confinement ring, while ensuring that the mechanical strength of the confinement ring is not compromised throughout its service life, confinement ring 140 may be designed to include lower horizontal section 143 having a slope defined along top surface 143a and bottom surface 143b of lower horizontal section 143 and groove 145′ having a tapered groove profile. Adding a slope to bottom surface 143b of lower horizontal section 143 keeps the bottom surface parallel to the inclined top surface, especially when the slope defined by bottom surface 143b is equal to the slope defined by top surface 143a, thereby improving the mechanical strength of the confinement ring. Variations in the design of confinement ring 140 (e.g., defining a slope along top surface 143a of lower horizontal section 143 and slots 145 having parallel slot profiles, or defining a slope along top surface 143a of lower horizontal section 143 and slots 145' having tapered slot profiles) are also contemplated to improve plasma density across the length of the substrate surface.

[0079] Figure 5B An exemplary wear profile of a groove 145' defined by a tapered groove profile in one embodiment is shown. The initial profile of groove 145' is shown in the center as a thick red line, where the ISR 145c at ID 145a is less than the OSR 145d at OD 145b. When confinement ring 145' is exposed to plasma from plasma region 108, during process operation, regions along the length of groove 145' exhibit uneven wear, where regions near inner diameter (ID) 145a exhibit more wear than regions around outer diameter (OD) 145b. Because the narrow end near the inner diameter of groove 145' has a high wear rate, while the wider end near the outer diameter of groove 145' has a lower wear rate, the region near the wider end reaches the critical size limit slower than the region near the narrow end, and thus the wider end of groove 145' can withstand the same amount of process operation as the narrow end before the wider end of groove 145' reaches the critical size limit, thereby extending the useful life of confinement ring 140'. Figure 5BThe end-of-life profile of the tapered groove 145' is shown as a thin rounded rectangle surrounding the tapered groove 145', where wear in a region along the length of the tapered groove reaches a critical size at about the same time that the confinement ring needs to be replaced to avoid a plasma unconfinement event. For more information on the use of a tapered groove profile to define the groove 145' along the lower horizontal section 143 of the confinement ring, reference may be made to commonly owned and co-pending International Patent Application No. PCT / US20 / 053894, filed on October 30, 2020, entitled "Wear Compensating Confinement Ring," the entire contents of which are incorporated herein by reference.

[0080] In some embodiments, the groove taper size defined by the wider groove size at the outer diameter OD 145b and the narrow groove size at the inner diameter ID 145a is set to the inverse of the wear rate. By adjusting the groove taper according to the change in the wear rate, the high wear rate of the inner diameter ID145a is compensated by the low wear rate of the outer diameter OD 145b, thereby producing an approximately straight groove profile at the end of the service life. The groove width along the entire groove length reaches the constraint limit (i.e., critical dimension) almost at the same time. The tapered geometry makes more efficient use of the area at the outer diameter. In order to compensate for the open area in the lower horizontal section caused by the reduction in the size of the groove at the inner diameter, additional grooves can be defined. The number of additional grooves can be defined by considering the amount of wear space required for each groove to reach the critical size at the narrow end and the wide end. The geometry of the tapered groove extends the amount of wear that the groove can withstand before reaching the unconstrained limit, thereby extending the service life and reducing the cost of consumables.

[0081] Figure 6A top perspective view of a confinement ring 140 used in a plasma processing chamber 100 to confine plasma in a plasma region 108 is shown. The confinement ring 140 is a C-shaped structure configured to be disposed along a periphery of the plasma region 108 to confine the plasma in the plasma region 108, which extends above a substrate 110 received on a substrate support surface defined in the lower electrode, an edge ring 112, and one or more dielectric rings 120. The confinement ring 140 is a replaceable consumable part. The top surface of the confinement ring includes a plurality of fastening holes 146 uniformly disposed in a circular direction, wherein the fastening holes 146 are configured to align with and receive fastening devices defined along a bottom surface of the outer electrode 102b of the upper electrode 102. The confinement ring 140 as shown shows a slope defined along a top surface 143a in a lower horizontal section 143 of the confinement ring 140. Additional slopes may be defined along the bottom surface 143b of the lower horizontal section 143 to increase the plasma density along the length of the substrate and the mechanical strength of the confinement ring, so that the confinement ring 140 can withstand additional process operations. The lower horizontal section 143 may also include grooves having a parallel groove profile or a tapered groove profile. The tapered groove profile provides additional benefits over the parallel groove profile because the tapered groove profile provides additional wear area near the inner diameter than near the outer diameter, thereby increasing the useful life of the confinement ring.

[0082] Advantages of the confinement rings described in various embodiments include improved plasma uniformity without adversely affecting other hardware components (e.g., chamber diaphragms, mating hardware, etc.) or adversely affecting the mechanical strength or life of the confinement rings. Plasma uniformity is adjusted by modifying the shape of the confinement rings without affecting the strength or original life expectancy of the confinement rings. This results in cost improvements for consumable confinement rings because the confinement rings can withstand more process operations before reaching critical size limits along the lower horizontal section and along the length of the slots. Other advantages will be apparent to those skilled in the art after reviewing the various embodiments described herein.

Claims

1. A confinement ring for a plasma processing chamber, comprising: an upper horizontal section extending between an upper inner radius and an outer radius of the confinement ring; a lower horizontal section extending between a lower inner radius of the confinement ring and the outer radius, the top surface of the lower horizontal section providing an angle downwardly toward the lower inner radius from adjacent the inside radius of the confinement ring, the lower horizontal section having an extension section extending to the lower inner radius; and A vertical section is disposed between the outer radius and the inner radius of the confinement ring, the vertical section connecting the upper horizontal section and the lower horizontal section of the confinement ring.

2. The confinement ring according to claim 1, wherein: The bottom surface of the lower horizontal section is flat such that a first thickness of the lower horizontal section near the inside radius is greater than a second thickness of the lower horizontal section at the lower inside radius.

3. The confinement ring according to claim 2, wherein: The first thickness is 10% to 40% greater than the second thickness.

4. The confinement ring of claim 1, wherein: The angle defines a slope along the top surface of the lower horizontal section, the slope being between 0.20° and 1° as measured relative to the horizontal x-axis.

5. The confinement ring of claim 1, wherein: the bottom surface of the lower horizontal section provides a second angle downwardly toward the lower inner radius, the second angle defining a second slope along the bottom surface of the lower horizontal section, the second angle of the second slope along the bottom surface being equal to the angle of the slope along the top surface of the lower horizontal section, and Wherein a first thickness of the lower horizontal section defined near the inner radius is equal to a second thickness of the lower horizontal section defined at the lower inner radius.

6. The confinement ring of claim 1, wherein: A first height defined between the bottom surface of the upper horizontal section and the top surface of the lower horizontal section near the inner radius is less than a second height between the bottom surface of the upper horizontal section and the top surface of the lower horizontal section at the lower inner radius of the confinement ring.

7. The confinement ring of claim 1, wherein: The lower horizontal section, the vertical section, and the upper horizontal section are integrally connected to define a C-shaped structure.

8. The confinement ring of claim 1, wherein: The lower horizontal section also includes a plurality of slots, wherein each slot extends radially along the lower horizontal section from an inner diameter to an outer diameter, an inner slot radius of each slot at the inner diameter being equal to an outer slot radius of each slot at the outer diameter.

9. The confinement ring of claim 8, wherein: The inner diameter of the groove is larger than an inner ring diameter of the confinement ring defined by the lower inner radius, and the outer diameter of the groove is smaller than an outer ring diameter of the confinement ring defined by the outer radius.

10. The confinement ring of claim 1, the lower horizontal section further comprising a plurality of grooves, wherein each groove radially extends from an inner diameter to an outer diameter along the lower horizontal section, and an inner groove radius of each groove at the inner diameter is smaller than an outer groove radius of each groove at the outer diameter.

11. The confinement ring of claim 10, wherein the difference between the inner groove radius and the outer groove radius of each groove defines a groove taper, each groove tapers from the outer diameter to the inner diameter, wherein the inner groove radius and the outer groove radius affecting the groove taper are defined as the inverse of the wear rate at the corresponding inner and outer diameters of the groove, and The ratio of the inner groove radius to the outer groove radius is between 1:1.1 and 1:1.

5.

12. The confinement ring of claim 1, wherein: The upper inner radius is greater than the lower inner radius.

13. The confinement ring of claim 1, wherein: The extension section extends vertically downward at the lower inner radius.

14. The confinement ring of claim 1, wherein: The extension section includes an inclined top section and a vertical bottom section, wherein the inclined top section provides a third angle downward at a downward inclination point defined on the top surface at the lower inner radius of the lower horizontal section, and the vertical bottom section is defined as extending downward from the bottom of the inclined top section.

15. The confinement ring of claim 1, wherein: The top surface of the upper horizontal section includes a plurality of holes, each of the plurality of holes being configured to receive a portion of a fastening device defined on a bottom surface of an upper electrode for coupling the confinement ring to the upper electrode of the plasma processing chamber.

16. The confinement ring of claim 1, wherein: The extended section of the lower horizontal section is configured to rest on a radio frequency gasket defined on a top surface of a lower electrode of the plasma processing chamber.

17. A confinement ring for use in a plasma processing chamber, comprising: an upper horizontal section extending between an upper inner radius and an outer radius of the confinement ring; a lower horizontal section extending between a lower inner radius and the outer radius of the confinement ring, a top surface of the lower horizontal section providing a first angle downwardly toward the lower inner radius to define a first slope along the top surface, and a bottom surface of the lower horizontal section providing a second angle downwardly toward the lower inner radius to define a second slope along the bottom surface, the lower horizontal section having an extension section extending downwardly along the lower inner radius, wherein the extension section extends below the bottom surface of the lower horizontal section; as well as A vertical section is disposed between the outer radius and the inner radius of the confinement ring, the vertical section connecting the upper horizontal section and the lower horizontal section of the confinement ring.

18. The confinement ring of claim 17, wherein: The first angle of the first slope is equal to the second angle of the second slope.

19. The confinement ring of claim 17, wherein a first thickness of the lower horizontal section near the inner radius is equal to a second thickness of the lower horizontal section at the lower inner radius, and in, A first height defined between the bottom surface of the upper horizontal section and the top surface of the lower horizontal section proximate the inner radius is less than a second height defined between the bottom surface of the upper horizontal section and the top surface of the lower horizontal section at the lower inner radius.

20. The confinement ring of claim 17, wherein: The lower horizontal section further comprises a plurality of slots, wherein each slot radially extends from an inner diameter to an outer diameter along the lower horizontal section, an inner slot radius of each slot at the inner diameter being equal to an outer slot radius of each slot at the outer diameter, and The inner diameter of each groove is larger than the inner ring diameter of the confinement ring defined by the lower inner radius, and the outer diameter of each groove is smaller than the outer ring diameter of the confinement ring defined by the outer radius.

21. The confinement ring of claim 17, wherein the lower horizontal section further comprises a plurality of grooves, wherein each groove radially extends from an inner diameter to an outer diameter along the lower horizontal section, and an inner groove radius of each groove at the inner diameter is smaller than an outer groove radius of each groove at the outer diameter.

22. A plasma processing chamber for confining plasma therein, the plasma processing chamber comprising a lower electrode for supporting a substrate and an upper electrode disposed above the lower electrode, the plasma processing chamber comprising: A confinement ring is disposed between the lower electrode and the upper electrode, the confinement ring comprising: an upper horizontal section extending between an upper inner radius and an outer radius of the confinement ring; a lower horizontal section extending between a lower inner radius of the confinement ring and the outer radius, the top surface of the lower horizontal section providing an angle downwardly toward the lower inner radius from adjacent the inside radius of the confinement ring, the angle defining a ramp along the top surface, the lower horizontal section having an extension section extending downwardly along the lower inner radius; and A vertical section is disposed between the outer radius and the inner radius of the confinement ring, the vertical section connecting the upper horizontal section and the lower horizontal section of the confinement ring.

23. The plasma processing chamber of claim 22, wherein: The bottom surface of the lower horizontal section provides a second angle downward toward the lower inner radius, the second angle defining a second slope along the bottom surface, the second angle of the second slope along the bottom surface being equal to the angle of the slope along the top surface of the lower horizontal section.

24. The plasma processing chamber of claim 22, wherein: The lower horizontal section further comprises a plurality of grooves disposed along the lower horizontal section, each groove radially extending from an inner diameter to an outer diameter along the lower horizontal section, an inner groove radius of each groove at the inner diameter being smaller than an outer groove radius of each groove at the outer diameter, and The inner diameter is larger than an inner ring diameter of the confinement ring defined by the lower inner radius, and the outer diameter is smaller than an outer ring diameter of the confinement ring defined by the outer radius.

25. The plasma processing chamber of claim 22, wherein: The upper inner radius is greater than the lower inner radius of the confinement ring.

26. The plasma processing chamber of claim 22, wherein: The confinement ring defined by the lower horizontal section, the upper horizontal section and the vertical section defines a continuous C-shaped structure to confine the plasma generated in the plasma processing chamber in a plasma region, and the confinement ring is made of one of silicon, polysilicon, silicon carbide, boron carbide, ceramic, or aluminum.

27. The plasma processing chamber of claim 22, wherein the extension section is integrally formed with the lower horizontal section, the vertical section, and the upper horizontal section of the confinement ring, the extension section being configured to extend vertically below a bottom surface of the lower horizontal section.

28. The plasma processing chamber of claim 22, wherein: The upper electrode is electrically grounded and the lower electrode is connected to a radio frequency power source through a corresponding matching network.

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