Ground Strap Assemblies

Abstract

The present disclosure relates to methods and apparatus for plasma processing substrates. In one embodiment, a substrate processing chamber includes a ground strap assembly. The ground strap assembly includes a ground strap and one or more connectors that are coupled to a substrate support and / or a chamber body. Each connector has a first clamping member and a second clamping member. The ground strap is fastened between the first clamping member and the second clamping member of each connector. An inner surface of each of the first clamping member and the second clamping member is coupled to the ground strap and coated with a dielectric coating. Modulation of the thickness and roughness of the inner surface enables adjustment of the capacitive characteristics of the connector.

Description

[0001] background

[0002] field

[0003] Embodiments of the present disclosure generally relate to methods and apparatus for processing substrates (eg, semiconductor substrates) using plasma. More specifically, embodiments of the present disclosure relate to radio frequency (RF) ground strap assemblies for plasma processing chambers.

[0004] Description of related technologies

[0005] Plasma enhanced chemical vapor deposition (PECVD) is used to process substrates, such as semiconductor substrates, solar panel substrates, and flat panel display substrates. PECVD is typically performed by introducing one or more precursor gases into a vacuum chamber having a substrate disposed therein on a substrate support. The precursor gases are directed toward a process space via a gas distribution plate, typically located near the top of the vacuum chamber. The precursor gases are energized (e.g., excited) into a plasma by applying power (e.g., radio frequency (RF) power) to electrodes in the chamber via one or more power supplies coupled to the electrodes. The activated gas or gas mixture then reacts to form a film layer of material on the surface of the substrate disposed on the substrate support. The film layer of material may be, for example, a passivation layer, a gate insulator, a buffer layer, and / or an etch stop layer.

[0006] During processing, the substrate support is electrically grounded to eliminate any voltage drop across the substrate support, which would affect the deposition uniformity of the material film layer across the substrate surface. Additionally, if the substrate support is not properly grounded, arcing and parasitic plasma formation may occur between the substrate support and the chamber body due to the high potential difference between the substrate support and the chamber body. This results in particle formation, metal contamination, non-uniform deposition, yield loss, and hardware damage. The parasitic plasma reduces the concentration and density of the capacitively coupled plasma within the chamber, thereby reducing the deposition rate of the material film layer.

[0007] In order to minimize the occurrence of arcing and parasitic plasma in large area plasma chambers, the substrate support is typically grounded to the chamber body via a thin and flexible ground strap to form a current return path. However, conventional ground strap arrangements provide an electrical return path with considerable inductance (e.g., impedance) at radio frequencies (e.g., 13.56 MHz and higher). As a result, a significant voltage potential difference still exists between the substrate support and the chamber body, resulting in unwanted arcing and parasitic plasma formation at the periphery of the substrate support.

[0008] Therefore, there is a need in the art for an improved substrate processing apparatus having a ground strap assembly with reduced electrical impedance.

[0009] Overview

[0010] The present disclosure relates to methods and apparatus for plasma processing substrates. In one embodiment, a substrate processing chamber is provided. The substrate processing chamber includes a chamber body having one or more chamber walls and a chamber bottom, the one or more chamber walls partially defining a process space, and the chamber bottom coupled to the one or more chamber walls. The chamber bottom further includes a chamber connector coupled to the chamber bottom, the chamber connector having a first clamping member, and the first clamping member is coupled to a second clamping member by one or more fasteners. A substrate support is disposed in the process space and includes a support connector coupled to the substrate support. The support connector has a first clamping member, and the first clamping member is coupled to the second clamping member by one or more fasteners. A grounding strap is coupled to the substrate support at a first end through a support connector, and is coupled to the chamber bottom at a second end through a chamber connector. One or more surfaces of the support connector and / or the chamber connector configured to contact the grounding strap have a dielectric coating formed on the surface.

[0011] In one embodiment, a ground strap assembly is provided. The ground strap assembly includes a chamber connector and a support connector, each of the chamber connector and the support connector having a dielectric coating formed on one or more surfaces of the chamber connector and the support connector. The ground strap assembly further includes a ground strap having a first end and a second end, the first end being coupled to the support connector and the second end being coupled to the chamber connector. The support connector and the chamber connector function as a capacitor.

[0012] In one embodiment, a ground strap assembly is provided. The ground strap assembly includes a ground strap having a first end and a second end, the first end being coupled to a support connector and the second end being coupled to a chamber connector. The first end and the second end of the ground strap are formed of a dielectric material, and the chamber connector and the support connector function as capacitors at the first end and the second end.

[0013] BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to be able to understand in detail the manner in which the above-mentioned features of the present disclosure are achieved, a more specific description of the present disclosure briefly summarized above may be obtained by reference to the embodiments, some of which are illustrated in the accompanying drawings. However, it is noted that the accompanying drawings illustrate only exemplary embodiments and are therefore not to be considered as limiting the scope of the present disclosure, which may allow for other equally effective embodiments.

[0015] Figure 1 A cross-sectional view of a substrate processing system having one or more ground straps coupled to a substrate support in the substrate processing system is illustrated according to one embodiment of the present disclosure.

[0016] Figure 2 A side view of an exemplary ground strap is shown according to one embodiment of the present disclosure.

[0017] Figure 3 Graphics Figure 1 A cross-sectional view of a portion of a substrate processing chamber.

[0018] Figure 4A A cross-sectional view of a portion of a ground strap assembly according to one embodiment of the present disclosure is illustrated.

[0019] Figure 4B A cross-sectional view of a portion of a ground strap assembly according to one embodiment of the present disclosure is illustrated.

[0020] Figure 5 A cross-sectional view of a ground strap assembly according to one embodiment of the present disclosure is illustrated.

[0021] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially utilized on other embodiments without further recitation.

[0022] Specific instructions

[0023] The present disclosure relates to methods and apparatus for plasma processing substrates. In one embodiment, a substrate processing chamber includes a ground strap assembly. The ground strap assembly includes a ground strap and one or more connectors that are coupled to a substrate support and / or a chamber body. Each connector has a first clamping member and a second clamping member. The ground strap is fastened between the first clamping member and the second clamping member of each connector. An inner surface of each of the first clamping member and the second clamping member is coupled to the ground strap and coated with a dielectric coating. Modulation of the thickness, roughness, and dielectric constant of the inner surface enables adjustment of the capacitive characteristics of the connector.

[0024] Embodiments herein are described exemplarily below with reference to use in a PECVD system configured to process a substrate, such as a PECVD system available from Applied Materials, Inc., Santa Clara, California. However, it should be understood that the disclosed subject matter is practical in other system configurations, such as etching systems, other chemical vapor deposition systems, and any other system in which a substrate is exposed to a plasma within a process chamber. It should be further understood that the embodiments disclosed herein may be implemented using process chambers provided by other manufacturers and chambers using different types of substrates. It should also be understood that the embodiments disclosed herein may be applicable to practice in other process chambers configured to process substrates of various shapes, sizes, and dimensions.

[0025] Figure 1 1 is a cross-sectional view of a substrate processing system 100 (e.g., a PECVD apparatus) according to one embodiment. The substrate processing system 100 is configured to process a large area substrate 114 using plasma during the manufacture of liquid crystal displays (LCDs), flat panel displays, organic light emitting diodes (OLEDs), or photovoltaic cells for solar cell arrays. These structures may include pn junctions to form diodes, metal oxide semiconductor field effect transistors (MOSFETs), and thin film transistors (TFTs) for photovoltaic cells.

[0026] The substrate processing system 100 is configured to deposit various materials on the large area substrate 114, including but not limited to dielectric materials, semiconductor materials, and insulating materials. For example, the dielectric materials and semiconductive materials may include polycrystalline silicon, epitaxial silicon, amorphous silicon, microcrystalline silicon, silicon germanium, silicon oxide, silicon oxynitride, silicon nitride, and combinations or derivatives thereof. The substrate processing system 100 is further configured to receive gases in the substrate processing system 100, including but not limited to precursor gases, purge gases, and carrier gases. For example, the plasma processing system may receive gas species such as hydrogen, oxygen, nitrogen, argon, helium, silane, and combinations or derivatives thereof.

[0027] The substrate processing system 100 includes a substrate processing chamber 102 coupled to a gas source 104. The substrate processing chamber 102 includes chamber walls 106 and chamber bottom 108 (collectively referred to as chamber body 101), which partially define a process space 110. Access to and from the process space 110 is typically via a sealable slit valve 112 in the chamber wall 106, which facilitates entry and exit of a substrate 114 into and out of the process space 110. The chamber walls 106 and chamber bottom 108 are typically made of aluminum, aluminum alloys, or other suitable materials for substrate processing. In one embodiment, the chamber walls 106 and chamber bottom 108 are coated with a protective barrier material to reduce the effects of corrosion. For example, the chamber walls 106 and chamber bottom 108 may be coated with a ceramic material, a metal oxide material, or a rare earth-containing material.

[0028] The chamber wall 106 supports the lid assembly 116. The gas distribution plate 126 is suspended from the backing plate 128 in the substrate processing chamber 102, and the backing plate 128 is coupled to the lid assembly 116 or the chamber wall 106. A gas space 140 is formed between the gas distribution plate 126 and the backing plate 128. The gas source 104 is connected to the gas space 140 via a gas supply conduit 141. The gas supply conduit 141, the backing plate 128 and the gas distribution plate 126 are generally formed of a conductive material and are electrically connected to each other. In one embodiment, the gas distribution plate 126 and the backing plate 128 are made of a single piece of material. The gas distribution plate 126 is generally perforated so that the process gas is evenly distributed into the substrate processing space 110.

[0029] The substrate support 118 is disposed within the substrate processing chamber 102 in a generally parallel manner opposite the gas distribution plate 126. The substrate support 118 supports the substrate 114 during processing. Typically, the substrate support 118 is made of a conductive material, such as aluminum, and encapsulates at least one temperature control device that controllably heats or cools the substrate support 118 to maintain the substrate 114 at a predetermined temperature during processing.

[0030] The substrate support 118 has a first surface 120 and a second surface 122. The first surface 120 is opposite the second surface 122. A third surface 121 perpendicular to the first surface 120 and the second surface 122 couples the first surface 120 and the second surface 122. The first surface 120 supports the substrate 114. The second surface 122 has a stem 124 coupled to the second surface 122. The stem 124 couples the substrate support 118 to an actuator (not shown) that moves the substrate support 118 between a raised processing position (as shown) and a lowered position that facilitates transfer of substrates into and out of the substrate processing chamber 102. The stem 124 also provides a conduit for electrical leads and thermocouple leads between the substrate support 118 and other components of the substrate processing system 100.

[0031] The RF power supply 142 is generally used to generate a plasma between the gas distribution plate 126 and the substrate support 118. The RF power supply 142 can generate an electric field between the gas distribution plate 126 and the substrate support 118 to form a plasma from the gas present between the gas distribution plate 126 and the substrate support 118. Various frequencies can be used. For example, the frequency can be between about 0.3 MHz and about 200 MHz, such as about 13.56 MHz. In one embodiment, the RF power supply 142 is coupled to the gas distribution plate 126 via an impedance matching circuit 144 at a first output 146. A second output 148 of the impedance matching circuit 144 is further electrically coupled to the chamber body 101.

[0032] In one embodiment, a remote plasma source (not shown, such as an inductively coupled remote plasma source) may also be coupled between the gas source 104 and the gas space 140. Between processing substrates, a cleaning gas may be provided to the remote plasma source. The cleaning gas may be activated into a plasma within the remote plasma source to form a remote plasma. The activated species generated by the remote plasma source may be provided to the substrate processing chamber 102 to clean chamber components. The RF power source 142 may further activate the cleaning gas to reduce the recombination of dissociated cleaning gas species. Suitable cleaning gases include, but are not limited to, NF3, F2, and SF6.

[0033] One or more grounding straps 130 are electrically connected to the substrate support 118 at a top end 152 of each grounding strap 130 and are electrically connected to the chamber bottom 108 at a bottom end 154 of each grounding strap 130. In one embodiment, the grounding straps 130 are electrically connected to the second surface 122 of the substrate support 118 at the top end 152. In other embodiments, the grounding straps 130 are electrically connected to the third surface 121 at the top end 152. The substrate processing chamber 102 may include any suitable number of grounding straps 130 for grounding the substrate support 118 to the chamber bottom 108, thereby forming an RF current return path (RFC) between the substrate support 118 and the chamber bottom 108. Figure 1 1 ). For example, one strap, two straps, three straps, four straps, five straps, or more straps may be used. The ground straps 130 are configured to shorten the path for RF current during processing and minimize arcing and parasitic plasma near the perimeter of the substrate support 118.

[0034] The substrate support 118 includes one or more support connectors 132 coupled to the substrate support 118. In one embodiment, the one or more support connectors 132 are coupled to the second surface 122 of the substrate support 118. In other embodiments, the one or more support connectors 132 are coupled to the third surface 121 of the substrate support 118. Figure 1 Five support connectors are shown in FIG. 1. However, other numbers of support connectors 132 are also contemplated, depending on the number of ground straps 130 used.

[0035] Similarly, the chamber bottom 108 includes one or more chamber connectors 134 coupled to the chamber bottom 108. In other embodiments, one or more chamber connectors 134 are coupled to the chamber wall 106. Figure 1 108. However, other numbers of chamber connectors 134 are contemplated depending on the number of ground straps 130 used. Figure 1 , each ground strap 130 is coupled to the substrate support 118 via a support connector 132 at a top end 152 and is coupled to the chamber bottom 108 via a corresponding chamber connector 134 at a bottom end 154. The coupling of each ground strap 130 to the support connector 132 and the chamber connector 134 forms a ground strap assembly 150.

[0036] Figure 21 is a side view of an exemplary ground strap 130. The body 232 of the ground strap 130 is generally a thin, flexible rectangular sheet of aluminum material having a top end 152 and a bottom end 154, wherein an optional slit 234 is centrally located along the body 232 between the top end 152 and the bottom end 154. In one example, the ground strap 130 is further manufactured to have one or more folds (not shown) located between the top end 152 and the bottom end 154. In another example, when the substrate support 118 is raised and lowered between the home position and the processing position, the one or more folds may be formed during processing, thereby bending the ground strap 130 and forming the one or more folds. In one embodiment, the length L of the ground strap 130 is between about 14 inches and about 30 inches, such as between about 18 inches and about 28 inches, such as between about 22 inches and about 24 inches. In one embodiment, the width W of the ground strap 130 is between about 0.5 inches and about 2 inches, such as between about 1 inch and about 1.5 inches. Figure 2 One example of a ground strap 130 suitable for use in the processing systems described herein is shown. The ground strap 130 is generally any suitable size, shape, and material to facilitate substrate processing.

[0037] Figure 3 yes Figure 1 1. A cross-sectional view of a portion 300 of a substrate processing chamber 102 is shown. Figure 3 Three ground strap assemblies 150 are shown having ground straps 130 coupled to substrate supports 118 via support connectors 132 and further coupled to chamber bottom 108 via chamber connectors 134. As shown, each ground strap assembly 150 includes a single ground strap 130 coupled to a single support connector 132 and a single chamber connector 134. However, it is also contemplated that one or more ground straps 130 may be coupled to each support connector 132 and / or each chamber connector 134. For example, each support connector 132 and / or each chamber connector 134 may be coupled to two ground straps 130.

[0038] According to one embodiment, each support connector 132 and chamber connector 134 includes a first clamping member 362, 372 and a second clamping member 364, 374, respectively. The grounding strap 130 is fastened between the first clamping member 362 and the second clamping member 364 of each support connector 132 at the top end 152, and the grounding strap 130 is fastened between the first clamping member 372 and the second clamping member 374 of each chamber connector 134 at the bottom end 154. The fastening of the grounding strap 130 is achieved by a mechanical clamping force between the first clamping member 362, 372 and the second clamping member 364, 374.

[0039] Figure 4A The support connector 132 is illustrated in greater detail. In one embodiment, the first clamping member 362 of the support connector 132 is an L-shaped block having a main body 480 and an extension 482. The contact area is between about 0.5 square inches and about 3 square inches, such as between about 1 square inch and about 2 square inches, depending on the desired capacitance. The main body 480 has a major axis X that is substantially parallel to the second surface 122 of the substrate support 118. The extension 482 protrudes from an upper surface 481 of the main body 480 in a manner that is substantially perpendicular to the major axis X and contacts the second surface 122 on an upper surface 483 of the extension 482. Thus, the upper surface 481 of the main body 480 does not directly contact the second surface 122 of the substrate support 118 and is disposed at a distance from the second surface 122 that is equal to the height E of the extension 482. In one embodiment, the upper surfaces 481, 483 are substantially flat.

[0040] When the grounding strap 130 is fastened, the main body 480 further contacts the second clamping member 364 on the lower surface 485 of the main body 480. In one embodiment, the lower surface 485 is substantially flat. In another embodiment, the lower surface 485 has a flat first portion 431 substantially parallel to the second surface 122 and a second portion 433 oriented at an angle α1 relative to the second surface 122. For example, the second portion 433 is oriented at an angle α1 between about 0 degrees and about 45 degrees relative to the first portion 431. In one embodiment, the lower surface 485 further includes a groove (not shown) formed in the lower surface 485 and matching with a protrusion (not shown) formed on the upper surface 487 of the second clamping member 364, or vice versa. The grooves and protrusions formed in the lower surface 485 and the upper surface 487 are shaped and manufactured according to a certain size to accommodate the size of the grounding strap 130, thereby forming a pocket in which the grounding strap 130 is more securely fastened by the support connector 132.

[0041] In one embodiment, the upper surface 487 of the second clamping member 364 is substantially parallel to the lower surface 485 of the first clamping member 362. In one embodiment, the upper surface 487 has a flat first portion 435 that is substantially parallel to the lower surface 485 and a second portion 437 that is defined by a radial curve to accommodate folding of the ground strap 130 when the substrate support 118 is raised and lowered between the home position and the processing position. In other embodiments, the second portion 437 is a flat surface disposed at an angle α2 between about 0 degrees and about 45 degrees relative to the first portion 435. The second clamping member 364 further includes a lower surface 489 that faces the chamber bottom 108. In one embodiment, the lower surface 489 is substantially flat.

[0042] The first clamping member 362 and the second clamping member 364 each include at least one set of fastener holes adapted to receive a fastener (such as a bolt, screw, or the like). For example, the first clamping member 362 includes a first set of fastener holes 456 adapted to receive at least one fastener 466 for coupling the first clamping member 362 to the substrate support 118. The first set of fastener holes 456 are disposed through the main body 480 and the extension 482 of the first clamping member 362. In one embodiment, the first clamping member 362 further includes a second set of fastener holes 458 that are aligned with a third set of fastener holes 460 disposed through the second clamping member 364. The second set of fastener holes 458 and the third set of fastener holes 460 are adapted to receive at least one fastener 468 for coupling the second clamping member 364 to the first clamping member 362. In one embodiment, the second set of fastener holes 458 are disposed only through the main body 480 of the first clamp member 362 and not through the extension 482. In one embodiment, the first clamp member 362 has only one set of fastener holes 458 that are aligned and adapted to receive at least one fastener 468 for coupling the first clamp member 362 to the substrate support 118 and to the second clamp member 364. The one or more sets of fastener holes are disposed near the peripheral edges of the first clamp member 362 and the second clamp member 364 so that the fasteners 466, 468 do not contact the ground strap 130 fastened between the first clamp member 362 and the second clamp member 364.

[0043] Figure 4BThe chamber connector 134 is illustrated in more detail. In one embodiment, each of the first clamping member 372 and the second clamping member 374 of the chamber connector 134 has a major axis X that is substantially parallel to the chamber bottom 108. In one embodiment, the upper surface 491 of the first clamping member 372 and the lower surface 499 of the second clamping member 374 are substantially flat. In one embodiment, each of the lower surface 495 of the first clamping member 372 and the upper surface 497 of the second clamping member 374 has a first portion and a second portion, the first portion being substantially parallel to the chamber bottom 108 and the second portion being oriented at an angle relative to the first portion. For example, the lower surface 495 has a substantially parallel first portion 421 and a second portion 423 oriented at an angle β1 between about 0 degrees and about 45 degrees relative to the first portion 421. Similarly, upper surface 497 has a first portion 425 that is substantially parallel and a second portion 427 that is oriented at an angle β2 between about 0 degrees and about 45 degrees relative to first portion 425 .

[0044] In one embodiment, the lower surface 495 further includes a groove (not shown) formed in the lower surface 495 and matching with a protrusion (not shown) formed on the upper surface 497, or vice versa. The grooves and protrusions formed in the lower surface 495 and the upper surface 497 are shaped and sized to accommodate the size of the ground strap 130, thereby forming a pocket in which the ground strap 130 is more securely fastened by the chamber connector 134. It is further contemplated that the size, shape, and configuration of the chamber connector 134 can be substantially similar to the support connector 132.

[0045] Similar to the support connector 132, the first clamping member 372 and the second clamping member 374 each include at least one set of fastener holes, which are suitable for receiving fasteners (such as bolts, screws, or the like). For example, the second clamping member 374 includes a first set of fastener holes 446, which are suitable for receiving at least one fastener 462 for coupling the second clamping member 374 to the chamber bottom 108. In one embodiment, the second clamping member 374 further includes a second set of fastener holes 448, which are aligned with a third set of fastener holes 450 disposed through the first clamping member 372. The second set of fastener holes 448 and the third set of fastener holes 450 are suitable for receiving at least one fastener 464 for coupling the second clamping member 374 to the first clamping member 372. In one embodiment, the second clamp member 374 has only one set of fastener holes 448 that are aligned and adapted to receive at least one fastener 464 for coupling the second clamp member 374 to the chamber bottom 108 and to the first clamp member 372. The one or more sets of fastener holes are disposed near the peripheral edges of the first clamp member 372 and the second clamp member 374 so that the fasteners 462, 464 do not contact the ground strap 130 fastened between the first clamp member 372 and the second clamp member 374.

[0046] Typically, the components of the ground strap assembly 150 are formed of a conductive material such as aluminum, nickel, a nickel alloy, or the like. In one embodiment, the first clamping member 362, 372 and the second clamping member 364, 374 further include a dielectric coating 490 formed on a desired surface of the first clamping member 362, 372 and the second clamping member 364, 374. The dielectric coating 490 enables the support connector 132 and / or the chamber connector 134 to function as a capacitor along the current return path provided by the ground strap assembly 150.

[0047] In one embodiment, the dielectric coating 490 is formed on surfaces of the support connector 132 and / or the chamber connector 134 that are configured to contact and secure the ground strap 130 between these surfaces. For example, the dielectric coating 490 is formed on the lower surface 485 of the first clamp member 362 and the upper surface 487 of the second clamp member 364. Alternatively or additionally, the dielectric coating 490 is formed on the lower surface 495 of the first clamp member 372 and the upper surface 497 of the second clamp member 374. In addition to the surfaces configured to contact the ground strap 130, the dielectric coating 490 may also be optionally formed on the lower surface 489 of the second clamp member 364 and / or the upper surface 491 of the first clamp member 372. The dielectric coating 490 formed on the lower surface 489 and / or the upper surface 491 may further be used to modulate the capacitive characteristics of the components of the ground strap assembly 150.

[0048] The dielectric coating 490 is formed of any suitable dielectric material, including but not limited to polytetrafluoroethylene (PTFE), polyetheretherketone (PEEK), Teflon, yttrium oxide, or the like. In some embodiments, the dielectric coating 490 is formed by spreading coating. In one embodiment, the dielectric coating 490 is formed by anodizing the desired surfaces of the support connector 132 and the chamber connector 134. For example, the dielectric coating 490 can be formed of anodized aluminum.

[0049] In one embodiment, the thickness of the dielectric coating 490 is between about 10 μm and about 100 μm, such as between about 20 μm and about 80 μm, such as between about 40 μm and about 60 μm. For example, the dielectric coating 490 has a thickness of about 50 μm. In one embodiment, the dielectric coating 490 further has a surface roughness value between about 0 μm and about 5 μm, such as between about 2 μm and about 4 μm. By modulating the thickness and surface roughness of the dielectric coating 490, the capacitive characteristics of the support connector 132 and the chamber connector 134 can be precisely controlled, thereby being able to modulate the impedance across the length of the ground strap assembly 150 and ultimately modulate the voltage potential difference. For example, by reducing the thickness of the dielectric coating 490 formed on the support connector 132 or the chamber connector 134, the capacitance of the component can be increased therein, thereby reducing the overall impedance across the ground strap assembly 150 and causing a reduction in the voltage potential difference between the substrate support 118 and the chamber bottom 108.

[0050] Figure 55 is a cross-sectional view of a ground strap assembly 550. The ground strap assembly 550 is generally similar to the ground strap assembly 150, but includes two ground straps 130, 131 that are coupled together in an overlapping manner at a joint 596 by a dielectric fastener 592. The ground strap 130 is coupled to the support connector 132 at a top end 152, and the ground strap 131 is coupled to the chamber connector 134 at a bottom end 154. The support connector 132 and the chamber connector 134 are generally similar to the above-described embodiments and may include a dielectric coating 490 formed on a desired surface of the support connector 132 and the chamber connector 134. For example, the dielectric coating 490 is formed on a surface of the support connector 132 and the chamber connector 134 to contact the ground straps 130, 131 when the ground straps 130, 131 are clamped in the support connector 132 and the chamber connector 134.

[0051] In one embodiment, the dielectric fasteners 592 include bolts, screws, or the like and matching nuts to couple the ground straps 130, 131 between these elements. Two or more plates 594 may be further provided on opposite sides of the ground straps 130, 131 at the joint 596 to secure the ground straps 130, 131 against each other. The plates 594 may be formed of any suitable metallic material, including but not limited to stainless steel, aluminum, nickel, or the like. Although in Figure 5 592 are shown as screws or bolts, but the dielectric fastener 592 is generally any suitable coupling mechanism.

[0052] The dielectric fastener 592 is formed of any suitable dielectric material, including but not limited to PTFE, PEEK, Torlon, or the like. In one embodiment, the dielectric fastener 592 is formed of the same material as the dielectric coating 490. Similar to the dielectric coating 490, the dielectric fastener 592 acts as a capacitor along the current return path provided by the ground strap assembly 550. By modulating the thickness of the dielectric fastener 592 and the contact area between the dielectric fastener 592 and the ground straps 130, 131, the capacitive characteristics of the dielectric fastener 592 can be precisely controlled, thereby further modulating the impedance across the length of the ground strap assembly 550. In one embodiment, the dielectric fastener 592 also acts as a capacitor in addition to the support connector 132 and / or chamber connector 134 (the support connector 132 and / or chamber connector 134 having the dielectric coating 490 formed thereon). In one embodiment, the dielectric fastener 592 is used as a capacitor in place of the support connector 132 and / or the chamber connector 134. Thus, the ground strap assembly 550 may have any combination of capacitors at one or more locations along the ground strap assembly 550.

[0053] In the operation of a conventional plasma processing chamber, the substrate support provides a return path for the RF power supplied to the gas distribution plate and the substrate support itself, which generates a voltage potential difference between the substrate support and the surrounding inner surface of the chamber body. This potential difference inadvertently generates arcs between the substrate support and the surrounding surface (e.g., the chamber wall). The magnitude of the potential difference and therefore the amount of arcing between the substrate support and the chamber wall depends in part on the resistance and size of the substrate support. Arcing is harmful and leads to particle contamination, film deposition variations, substrate damage, chamber component damage, yield loss, and system downtime.

[0054] Utilizing a ground strap coupled to the substrate support and the chamber body provides an alternate RF return path for RF power supplied to the substrate support or the gas distribution plate, thereby reducing the likelihood of arcing between the substrate support and the chamber body. However, conventional ground strap assemblies still provide significant resistance and impedance along the alternate RF return path that the conventional ground strap assemblies are intended to create, thereby creating a sufficient voltage potential difference between the substrate support and the chamber body to cause arcing between the substrate support and the chamber body.

[0055] By forming a dielectric layer on the ground strap connector and using the connector as a capacitor, the voltage potential difference between the substrate support and the chamber body is significantly reduced, thereby improving RF grounding efficiency. In this way, the reduced voltage potential difference eliminates or reduces arcing between the substrate support and the chamber body.

[0056] In addition, the reduced voltage potential difference reduces the formation of parasitic plasma during processing. During the deposition process, the generated plasma typically leaks into other parts of the chamber, becoming a parasitic plasma that forms undesirable films on various chamber components, such as the chamber walls, chamber bottom, substrate support, and a plurality of ground straps. The formation of parasitic plasma typically occurs between the outer edge of the substrate support or gas distribution plate and the surrounding chamber walls or below the substrate support. Parasitic plasma is detrimental because such plasma negatively affects the plasma uniformity of the thin film deposited on the substrate and may accelerate the erosion of chamber components, such as the ground strap itself. Reducing or eliminating the formation of parasitic plasma during processing thus extends the life of the ground strap 130 and other chamber components.

[0057] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope of the disclosure is to be determined by the claims which follow.

Claims

1. A substrate processing chamber, comprising: A chamber body, the chamber body comprising: one or more chamber walls at least partially defining a process volume; and a chamber bottom coupled to the one or more chamber walls, the chamber bottom having a chamber connector coupled to the chamber bottom, the chamber connector further comprising: a first clamping member coupled to a second clamping member via one or more fasteners; a substrate support disposed in the process space, the substrate support having a support connector coupled to the substrate support, the support connector further comprising: a first clamping member coupled to a second clamping member via one or more fasteners; and A ground strap having a first end and a second end, the first end being coupled to the substrate support at the support connector and the second end being coupled to the chamber bottom at the chamber connector, wherein one or more surfaces of the support connector and / or the chamber connector configured to contact the ground strap have a dielectric coating formed on the one or more surfaces.

2. The chamber of claim 1, wherein the dielectric coating is formed of anodized aluminum.

3. The chamber of claim 1, wherein the dielectric coating is formed from PTFE.

4. The chamber of claim 1, wherein the dielectric coating has a thickness between 10 μm and 100 μm.

5. The chamber of claim 2, wherein the dielectric coating has a thickness between 10 μm and 100 μm.

6. The chamber of claim 1, wherein the dielectric coating has a surface roughness between 0 and 5 μm.

7. The chamber of claim 2, wherein the dielectric coating has a surface roughness between 0 and 5 μm.

8. The chamber of claim 1, wherein the dielectric coating is further formed on one or more surfaces of the support connector and / or the chamber connector that are not configured to contact the ground strap.

9. A ground strap assembly, comprising: a chamber connector having a dielectric coating formed on one or more surfaces of the chamber connector; a support connector having a dielectric coating formed on one or more surfaces of the support connector, the support connector comprising a first clamping member and a second clamping member; and A grounding strap having a first end and a second end, wherein the first end is coupled to the support member connector and the second end is coupled to the chamber connector, wherein the chamber connector and the support member connector act as a capacitor, and wherein the fastening of the grounding strap is achieved by a mechanical clamping force between the first clamping member and the second clamping member.

10. The ground strap assembly of claim 9, wherein the support connector and the chamber connector are formed of aluminum.

11. The ground strap assembly of claim 10, wherein the dielectric coating is formed of anodized aluminum.

12. The ground strap assembly of claim 11, wherein the dielectric coating has a thickness between 10 μm and 100 μm.

13. The ground strap assembly of claim 10, wherein the dielectric coating is formed of PTFE.

14. The ground strap assembly of claim 9, wherein each of the chamber connector and the support connector comprises a first clamping member and a second clamping member coupled together by one or more fasteners.

15. A ground strap assembly, comprising: Chamber connector; a support connector, the support connector comprising a first clamping member and a second clamping member; and A ground strap having a first end and a second end, the first end being coupled to the support connector and the second end being coupled to the chamber connector, the first end and the second end of the ground strap being formed of a dielectric material, wherein the chamber connector and the support connector function as capacitors at the first end and the second end, and wherein fastening of the ground strap is achieved by a mechanical clamping force between the first clamping member and the second clamping member.

16. The ground strap assembly of claim 15, wherein the chamber connector has a dielectric coating formed on one or more surfaces of the chamber connector.

17. The ground strap assembly of claim 16, wherein the support connector has a dielectric coating formed on one or more surfaces of the support connector.

18. The ground strap assembly of claim 16, wherein the support connector and the chamber connector are formed of aluminum.

19. The ground strap assembly of claim 18, wherein the dielectric coating is formed of anodized aluminum.

20. The ground strap assembly of claim 18, wherein the dielectric coating is formed from PTFE.

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