CN114008755A

CN114008755A - Ground Strap Assembly

Info

Publication number: CN114008755A
Application number: CN201980094654.6A
Authority: CN
Inventors: 邵寿潜; 苏宗辉; 赵来; 周建华; 彭菲
Original assignee: Applied Materials Inc
Current assignee: Applied Materials Inc
Priority date: 2019-04-29
Filing date: 2019-04-29
Publication date: 2022-02-01
Anticipated expiration: 2039-04-29
Also published as: JP7446335B2; KR20210148406A; TWI890674B; JP2022537246A; CN114008755B; WO2020222764A1; KR102739848B1; TW202102066A

Abstract

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

Description

Grounding band component

Background

FIELD

Embodiments of the present disclosure generally relate to methods and apparatus for processing substrates (e.g., semiconductor substrates) using plasma. More particularly, embodiments of the present disclosure relate to a Radio Frequency (RF) ground strap assembly for a plasma processing chamber.

Description of the Related Art

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 the process volume through a gas distribution plate, typically located near the top of the vacuum chamber. The precursor gas is excited (e.g., excited) into a plasma by applying power (e.g., Radio Frequency (RF) power) to electrodes in the chamber by one or more power sources coupled to the electrodes. The activated gas or gas mixture then reacts to form a film of material on the surface of the substrate disposed on the substrate support. The film of material may be, for example, a passivation layer, a gate insulator, a buffer layer, and/or an etch stop layer.

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. In addition, if the substrate support is not properly grounded, an arc may be generated and a parasitic plasma may be formed between the substrate support and the chamber body due to a high potential difference between the substrate support and the chamber body. This leads to particle formation, metal contamination, non-uniformity of 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.

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

Accordingly, there is a need in the art for an improved substrate processing apparatus having a grounding strap assembly with reduced electrical impedance.

SUMMARY

The present disclosure relates to methods and apparatus for plasma processing a substrate. In one embodiment, a substrate processing chamber is provided. A substrate processing chamber includes a chamber body having one or more chamber walls partially defining a process volume and a chamber bottom coupled to the one or more chamber walls. The chamber bottom further includes a chamber connector coupled with the chamber bottom, the chamber connector having a first clamping member coupled to a second clamping member by one or more fasteners. A substrate support is disposed in the process volume and includes a support connector coupled to the substrate support. The support connector has a first clamp member coupled to a second clamp member by one or more fasteners. The ground strap is coupled at a first end to the substrate support by a support connector and at a second end to the chamber bottom by 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 thereon.

In one embodiment, a grounding strap assembly is provided. The grounding strap assembly includes a chamber connector and a support connector each 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 coupled to the support connector and a second end coupled to the chamber connector. The support connector and the chamber connector act as a capacitor.

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

Brief description of the drawings

So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only exemplary embodiments and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments.

Figure 1 illustrates 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, according to one embodiment of the present disclosure.

Figure 2 illustrates a side view of an exemplary grounding strap according to one embodiment of the present disclosure.

Fig. 3 illustrates a cross-sectional view of a portion of the substrate processing chamber of fig. 1.

Figure 4A illustrates a cross-sectional view of a portion of a grounding strap assembly according to one embodiment of the present disclosure.

Figure 4B illustrates a cross-sectional view of a portion of a grounding strap assembly according to one embodiment of the present disclosure.

Fig. 5 illustrates a cross-sectional view of a grounding strap assembly according to one embodiment of the present disclosure.

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.

Detailed description of the invention

The present disclosure relates to methods and apparatus for plasma processing a substrate. 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 coupled to the substrate support and/or the chamber body. Each connector has a first clamping member and a second clamping member. A grounding strap is secured between the first and second clamping members of each connector. An inner surface of each of the first and second clamping members is coupled to the grounding strap and coated with a dielectric coating. Modulation of the thickness, roughness and dielectric constant of the inner surface enables tuning of the capacitive characteristics of the connector.

Embodiments herein are illustratively described below with reference to use in a PECVD system configured to process substrates, such as a PECVD system available from Applied Materials, inc. 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 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 adapted for practice in other process chambers configured to process substrates of various shapes, sizes, and dimensions.

Fig. 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 a Liquid Crystal Display (LCD), flat panel display, Organic Light Emitting Diode (OLED), or photovoltaic cell for a solar cell array. These structures may include p-n junctions to form diodes for photovoltaic cells, Metal Oxide Semiconductor Field Effect Transistors (MOSFETs), and Thin Film Transistors (TFTs).

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

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 a chamber bottom 108 (collectively, the chamber body 101), the chamber walls 106 and the chamber bottom 108 partially defining a process volume 110. The process volume 110 is typically accessed via a sealable slit valve 112 in the chamber walls 106, the slit valve 112 facilitating the entry and exit of the substrate 114 into and out of the

process volume

110, 110. The chamber walls 106 and chamber bottom 108 are typically made of aluminum, aluminum alloy, or other suitable material 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 erosion. For example, the chamber walls 106 and the chamber bottom 108 may be coated with a ceramic material, a metal oxide material, or a rare earth-containing material.

The chamber wall 106 supports a lid assembly 116. A gas distribution plate 126 is suspended from a backing plate 128 in the substrate processing chamber 102, the backing plate 128 being coupled to the lid assembly 116 or the chamber walls 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, backing plate 128, and gas distribution plate 126 are typically formed of an electrically conductive material and are in electrical communication with one another. In one embodiment, the gas distribution plate 126 and backing plate 128 are made from a single piece of material. The gas distribution plate 126 is generally perforated such that the process gases are uniformly distributed into the substrate processing volume 110.

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 an electrically conductive material (e.g., 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.

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) rod 124 coupled to the second surface 122. The rods 124 couple the substrate support 118 to actuators (not shown) that move the substrate support 118 between a raised processing position (as shown) and a lowered position that facilitates substrate transfer into and out of the substrate processing chamber 102. The stem 124 also provides a conduit for electrical and thermocouple leads between the substrate support 118 and other components of the substrate processing system 100.

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

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 into the substrate processing chamber 102 to clean chamber components. The RF power source 142 may further activate the cleaning gas to reduce recombination of dissociated cleaning gas species. Suitable cleaning gases include, but are not limited to, NF₃、F₂And SF₆。

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 to the chamber bottom 108 at a bottom end 154 of each grounding strap 130. In one embodiment, the grounding strap 130 is electrically connected to the second surface 122 of the substrate support 118 at the top end 152. In further embodiments, the grounding strap 130 is electrically connected to the third surface 121 at the tip 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 to form an RF current return path (five straps are shown in figure 1) between the substrate support 118 and the chamber bottom 108. For example, one band, two bands, three bands, four bands, five bands, or more bands may be used. The grounding strap 130 is configured to shorten the path for the RF current during processing and minimize arcing and parasitic plasma near the perimeter of the substrate support 118.

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

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 walls 106. Five chamber connectors are shown coupled to the chamber bottom 108 in fig. 1. However, other numbers of cavity connectors 134 are also contemplated depending on the number of grounding straps 130 used. According to one embodiment shown in fig. 1, each ground strap 130 is coupled to the substrate support 118 via a support connector 132 at a top end 152 and 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.

Fig. 2 is a side view of an exemplary grounding strap 130. The body 232 of the grounding strap 130 is a generally thin, flexible rectangular sheet of aluminum material having a top end 152 and a bottom end 154, with an optional slot 234 centrally located along the body 232 between the top end 152 and the bottom end 154. In one example, the grounding strap 130 is further manufactured with one or more folds (folds) (not shown) between the top end 152 and the bottom end 154. In another example, one or more folds may be formed during processing as the substrate support 118 is raised and lowered between a home position (home position) and a processing position, thereby bending the ground strap 130 and forming one or more folds. In one embodiment, the length L of the grounding strap 130 is between about 14 inches to 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 grounding 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 illustrates one example of a grounding strap 130 suitable for use in the processing system described herein. The grounding strap 130 is generally any suitable size, shape, and material that facilitates substrate processing.

Fig. 3 is a cross-sectional view of a portion 300 of the substrate processing chamber 102 of fig. 1. Figure 3 illustrates three grounding strap assemblies 150, the grounding strap assemblies 150 having a grounding strap 130, the grounding strap 130 coupled to the substrate support 118 by a support connector 132 and further coupled to the chamber bottom 108 by a chamber connector 134. As shown, each grounding strap assembly 150 includes a single grounding strap 130 coupled to a single support connector 132 and a single chamber connector 134. However, it is also contemplated that one or more grounding 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.

According to one embodiment, each support connector 132 and chamber connector 134 includes a

first clamp member

362, 372 and a

second clamp member

364, 374, respectively. The ground strap 130 is secured at the top end 152 between the first and

second clamp members

362, 364 of each support connector 132, and the ground strap 130 is secured at the bottom end 154 between the first and

second clamp members

362, 364 of each chamber connector 134. The fastening of the ground strap 130 is achieved by a mechanical clamping force between the first and

second clamping members

362, 372, 364, 374.

Fig. 4A illustrates the support connector 132 in more detail. In one embodiment, the first clamp 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, for example 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 the upper surface 481 of the main body 480 in a substantially perpendicular manner with respect to the main axis X, and contacts the second surface 122 on an upper surface 483 of the extension 482. Accordingly, 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 equal to the height E of the extension 482. In one embodiment, the

upper surfaces

481, 483 are substantially planar.

When zone 130 is secured, main body 480 further contacts second clamping member 364 on lower surface 485 of main body 480. In one embodiment, 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 at an angle α with respect to the second surface 122₁Oriented second portion 433. For example, second portion 433 is at an angle α between about 0 degrees and about 45 degrees relative to first portion 431₁And (4) orientation. In one embodiment, lower surface 485 further includes a groove (not shown) formed in lower surface 485 that mates with a protrusion (not shown) formed on upper surface 487 of second clamp member 364, or vice versa. The grooves and protrusions formed in the lower surface 485 and the upper surface 487 are shaped and sized to accommodate the size of the grounding strap 130 to form pockets (pockets) in which the grounding strap 130 is more securely fastened by the brace connectors 132.

In one embodiment, upper surface 487 of second clamp member 364 is substantially parallel to lower surface 485 of first clamp member 362. In one embodiment, the upper surface 487 has a flat first portion 435 and a second portion 437, the flat first portion 435 being substantially parallel to the lower surface 485, the second portion 437 being defined by a radial curve (radial curve) to accommodate folding of the ground strap 130 as the substrate support 118 is raised and lowered between the home position and the processing position. In other embodiments, the second portion 437 is at an angle α between about 0 degrees and about 45 degrees with respect to the first portion 435₂A flat surface is provided. The second clamping member 364 further includes a lower surface 489 facing the chamber bottom 108. In one embodimentThe lower surface 489 is substantially flat.

The first and

second clamp members

362, 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 clamp member 362 includes a first set of fastener holes 456, the first set of fastener holes 456 adapted to receive at least one fastener 466 for coupling the first clamp member 362 to the substrate support 118. A first set of fastener holes 456 are provided through the main body 480 and the extensions 482 of the first clamp member 362. In one embodiment, first clamp member 362 further includes a second set of fastener holes 458, the second set of fastener holes 458 being aligned with a third set of fastener holes 460 disposed through second clamp member 364. The second and third sets of

fastener apertures

458, 460 are adapted to receive at least one fastener 468 for coupling the second clamp member 364 to the first clamp 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 extensions 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 described above are disposed near the peripheral edges of the first and

second clamp members

362, 364 such that the

fasteners

466, 468 do not contact the ground strap 130 secured between the first and

second clamp members

362, 364.

Fig. 4B illustrates the chamber connector 134 in more detail. In one embodiment, each of first and

second clamping members

372, 374 of chamber connector 134 has a major axis X that is substantially parallel to chamber bottom 108. In one embodiment, upper surface 491 of first clamping member 372 and lower surface 499 of second clamping member 374 are substantially planar. In one embodiment, each of lower surface 495 of first clamping member 372 and upper surface 497 of second clamping member 374 has a first portion and a second portion, the first portion being substantially parallel toA chamber bottom 108, the second portion oriented at an angle relative to the first portion. For example, the lower surface 495 has a first portion 421 that is substantially parallel and an angle β between about 0 degrees and about 45 degrees with respect to the first portion 421₁An oriented second portion 423. Similarly, upper surface 497 has first portion 425 that is substantially parallel and angle β between about 0 degrees and about 45 degrees with respect to first portion 425₂A second portion 427 of orientation.

In one embodiment, lower surface 495 further includes a groove (not shown) formed in lower surface 495 and mating with a protrusion (not shown) formed on upper surface 497, or vice versa. The recesses and protrusions formed in the lower surface 495 and the upper surface 497 are shaped and sized to accommodate the size of the ground strip 130 to form pockets in which the ground strip 130 is more securely fastened by the chamber connector 134. It is further contemplated that the chamber connector 134 may be substantially similar in size, shape, and configuration to the support connector 132.

Similar to the support connector 132, the first and

second clamp members

372, 374 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 second clamp member 374 includes a first set of fastener holes 446, the first set of fastener holes 446 being adapted to receive at least one fastener 462 for coupling the second clamp member 374 to the chamber bottom 108. In one embodiment, second clamping member 374 further includes a second set of fastener holes 448, second set of fastener holes 448 being aligned with a third set of fastener holes 450 disposed through first clamping member 372. Second set of fastener holes 448 and third set of fastener holes 450 are adapted to receive at least one fastener 464 for coupling second clamping member 374 to first clamping member 372. In one embodiment, second clamping member 374 has only one set of fastener holes 448, the set of fastener holes 448 being aligned and adapted to receive at least one fastener 464 for coupling second clamping member 374 to chamber bottom 108 and to first clamping member 372. The one or more sets of fastener holes described above are disposed near the peripheral edges of the first and second clamping members 372, 344 such that the

fasteners

462, 464 do not contact the ground strap 130 secured between the first and second clamping members 372, 344.

Typically, the components of the grounding strap assembly 150 are formed from a conductive material, such as aluminum, nickel alloy, or the like. In one embodiment, the first and

second clamp members

362, 372, 364, 374 further include a dielectric coating 490 formed on desired surfaces of the first and

second clamp members

362, 372, 364, 374. The dielectric coating 490 enables the support connector 132 and/or the chamber connector 134 to act as a capacitor along the current return path provided by the ground strap assembly 150.

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 the surfaces. For example, a 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, a 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 grounding strip 130, a dielectric coating 490 may also optionally be formed on the lower surface 489 of the second clamping member 364 and/or the upper surface 491 of the first clamping member 372. The dielectric coating 490 formed on the lower surface 489 and/or the upper surface 491 may further serve to modulate the capacitive characteristics of the components of the ground band assembly 150.

The dielectric coating 490 is formed of any suitable dielectric material, including but not limited to Polytetrafluoroethylene (PTFE), Polyetheretherketone (PEEK), teflon, yttria, or the like. In some embodiments, the dielectric coating 490 is formed by brushing (spraying coating). In one embodiment, the dielectric coating 490 is formed by anodizing the desired surfaces of the support member connector 132 and the chamber connector 134. For example, the dielectric coating 490 may be formed from anodized aluminum.

In one embodiment, the dielectric coating 490 has a thickness 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 enabling modulation of the impedance and ultimately the voltage potential difference across the length of the zone assembly 150. 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 components may be increased therein, thereby reducing the overall impedance of the cross-over zone assembly 150 and resulting in a reduction in the voltage potential difference between the substrate support 118 and the chamber body 108.

Fig. 5 is a cross-sectional view of the grounding strap assembly 550. The grounding strap assembly 550 is generally similar to the grounding strap assembly 150, but includes two grounding

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 the top end 152 and the ground strap 131 is coupled to the chamber connector 134 at the bottom end 154. The support connector 132 and the chamber connector 134 are generally similar to the embodiments described above, and may include a dielectric coating 490 formed on desired surfaces of the support connector 132 and the chamber connector 134. For example, the dielectric coating 490 is formed on the surfaces of the support connector 132 and the chamber connector 134 to contact the grounding straps 130, 131 when the grounding straps 130, 131 are clamped in the support connector 132 and the chamber connector 134.

In one embodiment, the dielectric fasteners 592 include bolts, screws, or the like and mating nuts to couple the grounding straps 130, 131 between these elements. Two or more plates 594 may further be disposed on opposite sides of the grounding straps 130, 131 at the joints 597 to secure the grounding straps 130, 131 against one another. Plate 594 may be formed of any suitable metallic material, including but not limited to stainless steel, aluminum, nickel, or the like. Although shown as screws or bolts in fig. 5, the dielectric fasteners 592 are generally any suitable coupling mechanism.

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

In operation of a conventional plasma processing chamber, the substrate support provides a return path for RF power supplied to the gas distribution plate and the substrate support itself, while a voltage potential difference is generated between the substrate support and the surrounding inner surface of the chamber body. This potential difference inadvertently creates an arc between the substrate support and surrounding surfaces, such as the chamber walls. The magnitude of the potential difference, and thus the amount of arcing between the substrate support and the chamber walls, depends in part on the resistance and size of the substrate support. Arcing is detrimental and results in particle contamination, film deposition variation, substrate damage, chamber component damage, yield loss, and system downtime.

Utilizing a ground strap coupled to the substrate support and the chamber body provides an alternative 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, the conventional grounding strap assembly still provides significant resistance and impedance along the alternative RF return path that the conventional grounding strap assembly is intended to create, while creating a sufficient voltage potential difference between the substrate support and the chamber body to create an arc between the substrate support and the chamber body.

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. As such, the reduced voltage potential difference eliminates or reduces arcing between the substrate support and the chamber body.

In addition, the reduced voltage potential difference reduces parasitic plasma formation during processing. During the deposition process, the generated plasma typically leaks into other parts of the chamber as parasitic plasma, which forms undesirable films on various chamber components, such as the chamber walls, the chamber bottom, the substrate support, and the plurality of grounding 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 plasmas are detrimental because such plasmas negatively impact plasma uniformity of thin films deposited on substrates and may accelerate erosion of chamber components (e.g., the ground strap itself). Reducing or eliminating parasitic plasma formation during processing thus extends the life of the ground strap 130 and other chamber components.

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 thereof is determined by the claims that follow.

Claims

1. A substrate processing chamber, comprising:

a chamber body comprising:

one or more chamber walls that at least partially define the process space; 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 clamp member coupled to the second clamp member by 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 clamp member coupled to the second clamp member by one or more fasteners; and

a ground strap having a first end coupled to the substrate support at the support connector and a second end coupled at the chamber is coupled to the chamber bottom at the junction, wherein one or more surfaces of the support connector and/or the chamber connector configured to contact the ground strap have Dielectric coating formed on the surface.

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 of PTFE.

4. The chamber of claim 1, wherein the thickness of the dielectric coating is between about 10 [mu]m and about 100 [mu]m.

5. The chamber of claim 2, wherein the thickness of the dielectric coating is between about 10 [mu]m and about 100 [mu]m.

6. The chamber of claim 1, wherein the dielectric coating has a surface roughness between about 0 and about 5 [mu]m.

7. The chamber of claim 2, wherein the dielectric coating has a surface roughness between about 0 and about 5 [mu]m.

8. The chamber of claim 1, wherein the medium 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. Electrocoating.

9. A ground strap assembly comprising:

a chamber connector having a dielectric coating formed on one or more surfaces of the chamber connector;

a buttress connector having a dielectric coating formed on one or more surfaces of the buttress connector; and

a ground strap having a first end coupled to the support connector and a second end coupled to the chamber connector, wherein the The chamber connector and the support connector act as capacitors.

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 thickness of the dielectric coating is between about 10 [mu]m and about 100 [mu]m.

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 includes a first clip coupled together by one or more fasteners member and a second clamping member.

15. A ground strap assembly comprising:

chamber connector;

support connector; and

a ground strap having a first end coupled to the support connector and a second end coupled to the chamber connector, the ground strap having a first end coupled to the support connector and a second end coupled to the chamber connector The first and second ends of the strip are formed of a dielectric material, wherein the chamber connector and the support connector serve as capacitors at the first and second ends.