Grounding device for plasma processing chamber

Abstract

The present disclosure provides radio frequency (RF) return devices and processing chambers thereof. The RF devices include a bracket mechanically coupled to a substrate support, a first mounting plate, and a mounting base. A cover plate is mechanically coupled to the first mounting plate and the mounting base. A base plate is disposed over the mounting base. A plurality of stacking plates is disposed between the first mounting plate and the base plate. A strap is mechanically coupled to the mounting base. A second mounting base is mechanically coupled to the strap

Description

PATENTAttorney Docket No.: 44024945WO01GROUNDING DEVICE FOR PLASMA PROCESSING CHAMBERBACKGROUNDField

[0001] Embodiments described herein generally relate to methods and apparatus for processing substrates. More particularly, embodiments described herein relate to a grounding device for a processing chamber.Description of the Related Art

[0003] Plasma enhanced chemical vapor deposition (PECVD) is generally employed to deposit thin films on substrates, such as semiconductor substrates, solar panel substrates, and liquid crystal display (LCD) and organic light emitting diode (OLED) substrates used in display manufacture. PECVD is generally accomplished by introducing a precursor gas into a vacuum chamber having a substrate disposed on a susceptor or substrate support. The precursor gas is typically directed through a gas distribution plate situated near the top of the vacuum chamber. The precursor gas in the vacuum chamber is energized (e.g., excited) into a plasma by applying RF power to the chamber from one or more RF sources coupled to the chamber. The excited gas reacts to form a thin film of material on a surface of the substrate (or devices formed thereon). The gas distribution plate is generally connected to a RF power source and the susceptor is typically connected to the chamber body providing a RF current return path, e.g., a metal return path such as a metal band or strap.

[0004] Conventional PECVD processes operate at temperatures exceeding 400 °C when depositing thin films on substrates. Temperatures exceeding 400 °C can lead to premature breakdown and / or breakage of the RF current return paths, thereby causing arcing and reduction of RF current flow. Attempts to increase the longevity of the RF current return paths have focused on using materials such as alternative metal alloys. Unfortunately, these alternative metal alloys have a higher RF impedance, thereby requiring a coating material to reduce the RF impedance. The coating material can peel from the nickel-based alloy thereby causing reverse bending, and subsequent particle contamination during processing.PATENTAttorney Docket No.: 44024945WO01

[0005] Accordingly, there is a need in the art for improved RF current return paths.SUMMARY

[0006] In some embodiments, the present disclosure provides radio frequency (RF) return devices. The RF devices include a bracket mechanically coupled to a substrate support, a first mounting plate, and a mounting base. A cover plate is mechanically coupled to the first mounting plate and the mounting base. A base plate is disposed over the mounting base. A plurality of stacking plates is disposed between the first mounting plate and the base plate. A strap is mechanically coupled to the mounting base. A second mounting base is mechanically coupled to the strap.

[0007] In other embodiments, the present disclosure provides process chambers. The process chambers include a chamber body. A substrate support is disposed in the chamber body. A RF return device is included, in which the RF return device includes a bracket mechanically coupled to the substrate support, a first mounting plate, and a mounting base. A cover plate is mechanically coupled to the first mounting plate and the mounting base. A base plate is disposed over the mounting base. A plurality of stacking plates are disposed between the first mounting plate and the base plate. A strap is mechanically coupled to the mounting base. A second mounting base is mechanically coupled to the strap and the chamber body.

[0008] In other embodiments, the present disclosure provides process chambers. The process chambers include a chamber body. A substrate support is disposed in the chamber body. A reflector is disposed below the substrate support. A RF return device is included, in which the RF return device includes a plurality of stacking plates.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] So that the manner in which the above recited features of the disclosure can be understood in detail, a more particular description as described herein, 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 typical embodiments of this disclosure and are therefore notPATENTAttorney Docket No.: 44024945WO01 to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments.

[0010] Figure 1A is a schematic cross-sectional view of one embodiment of a plasma processing system when a substrate support is at a first position, according to one or more of the embodiments described herein.

[0011] Figure 1 B is a schematic cross-sectional view of the plasma processing system of Figure 1A when a substrate support is at a second position, according to one or more of the embodiments described herein.

[0012] Figures 2A and 2B are schematic cross-sectional views of a radio frequency (RF) return device, according to one or more of the embodiments described herein.

[0013] Figure 3 is a graph representing an average power ratio of a processing system, according to one or more embodiments described herein.

[0014] Figure 4 is a graph representing a temperature rate of change of a processing system, according to one or more embodiments described herein.

[0015] Figures 5A and 5B are graphs representing a temperature differences between a top surface of a conventional ground strap and a top surface of the RF return device, according to one or more embodiments described herein.

[0016] Figures 6A and 6B are graphs representing a temperature change of a top surface of the RF return device, according to one or more embodiments described herein. To facilitate understanding, identical reference numerals have been used, wherever possible, to designate identical elements that are common to the figures. It is contemplated that elements and / or process steps of one embodiment may be beneficially incorporated in other embodiments without additional recitation.DETAILED DESCRIPTION

[0017] Embodiments of the present disclosure generally relate to a method and apparatus for processing substrates using plasma and / or cleaning components using plasma. More specifically, embodiments provided herein generally relate to a radioPATENTAttorney Docket No.: 44024945WO01 frequency (RF) return device configured to provide a grounding path between a substrate support or a susceptor of a process chamber and the process chamber. For example, the RF return device may be configured to be mounted to a bottom surface, e.g. a chamber bottom, and / or side wall of the process chamber to provide the grounding path. The process chamber may be a plasma enhanced chemical vapor deposition (PECVD) chamber, a physical vapor deposition (PVD) chamber, an etching chamber, a semiconductor processing chamber, a solar cell processing chamber, an organic light emitting display (OLED) processing chamber, or the like.

[0018] The use of an RF return device in accordance with embodiments and techniques of the present disclosure may enable a reduction in the temperature that the RF return device and its various components are exposed to, which may increase the durability and lifetime of the RF return device. In addition, a reflector may be disposed along a bottom surface of the susceptor, thereby reducing radiation heat transfer between the susceptor and the RF return device. The reduction of radiation heat transfer can further reduce the temperature that the RF return device is exposed to, thereby enhancing the longevity of the RF return device.Processing System

[0019] Figure 1A is a schematic cross-sectional view of one embodiment of a plasma processing system 100 when a substrate support 150 is at a first position (e.g. , a processing position), according to one or more of the embodiments described herein. The plasma processing system 100 may be configured to process a substrate 101 using plasma in forming structures and devices on the substrate 101 for use in the fabrication of liquid crystal displays (LCDs), flat panel displays, OLED devices, or photovoltaic cells for solar cell arrays. The substrate 101 may be a thin sheet of metal, plastic, organic material, silicon, glass, quartz, or polymer, among others suitable materials.

[0020] The plasma processing system 100 may be configured to deposit a variety of materials on the substrate 101 , including dielectric materials (e.g., silicon dioxide (SiC ), silicon oxynitride (SiOxNy), derivatives thereof, or combinations thereof), semiconductive materials (e.g., silicon (Si) and dopants thereof), or barrier materialsPATENTAttorney Docket No.: 44024945WO01(e.g., Silicon nitride (SiNx), SiOxNyor derivatives thereof). The plasma processing system 100 may also be configured to receive gases such as argon, hydrogen, nitrogen, helium, or combinations thereof, for use as a purge gas or a carrier gas (e.g., Ar, H2, N2, He, derivatives thereof, or combinations thereof).

[0021] As shown in Figure 1A, the plasma processing system 100 generally includes a chamber body 102 including a chamber bottom 117a and two sidewalls 117b, 117c that at least partially define a processing volume 111 . A substrate support 150 (also referred to as a susceptor) is disposed in the processing volume 111. The substrate support 150 is adapted to support the substrate 101 on a top surface 156 of the substrate support 150 during processing. The substrate support 150 is coupled to an actuator 138 by a shaft 137. The actuator 138 is configured to move the substrate support 150 at least vertically to (1 ) facilitate transfer of the substrate 101 into and out of the chamber body 102 and / or (2) adjust a distance D between the substrate 101 and a showerhead assembly 103. One or more lift pins 110a, 110b, 110c, and 110d may extend through the substrate support 150. The lift pins 110a, 110b, 110c, and 110d are adapted to contact the chamber bottom 117a of the chamber body 102 and support the substrate 101 above the top surface 156 of the substrate support 150 when the substrate support 150 is lowered by the actuator 138 in order to facilitate transfer of the substrate 101 , for example, using the position of the substrate support 150 as shown in Figure 1 B. In a processing position as shown in Figure 1 A, the lift pins 110a, 110b, 110c, and 110d are adapted to be flush with or slightly below the top surface 156 of the substrate support 150 to allow the substrate 101 to lie flat on the substrate support 150.

[0022] In some embodiments, the substrate 101 and the substrate support 150 may have a surface area greater than about 5 square meters, such as, for example, about 5.5 square meters. In some embodiments, the substrate 101 and / or the substrate support 150 can be rectangular and can include dimensions of about 2200 mm on a minor side by about 2500 mm on a major side, or greater. In other embodiments, the substrate 101 and the substrate support 150 can be smaller. The structures formed on the substrate 101 may be OLED devices, thin film transistors, or p-n junctions to form diodes for photovoltaic cells.PATENTAttorney Docket No.: 44024945WO01

[0023] The showerhead assembly 103 may be configured to supply a processing gas to the processing volume 111 from a processing gas source 122. The plasma processing system 100 also may include an exhaust system 118 configured to apply negative pressure to the processing volume 111. The showerhead assembly 103 may generally be disposed opposing the substrate support 150. For example, the showerhead assembly 103 may be disposed directly above the substrate support 150, in a substantially parallel relationship.

[0024] The showerhead assembly 103 may include a gas distribution plate 114 and a backing plate 116. The backing plate 116 may function as a blocker plate to enable formation of a gas volume 131 between the gas distribution plate 114 and the backing plate 116. The processing gas source 122 is connected to the gas distribution plate 114 by a conduit 134. In some embodiments, a remote plasma source 107 may be coupled to the conduit 134 for supplying a plasma of activated gas through the gas distribution plate 114 to the processing volume 111. The plasma from the remote plasma source 107 may include activated gases (e.g., fluorine (F)) for cleaning chamber components disposed in the processing volume 111.

[0025] The gas distribution plate 114, the backing plate 116, and the conduit 134 may generally be formed from electrically conductive materials and may be in electrical communication with one another. The chamber body 102 is also formed from an electrically conductive material. The chamber body 102 may generally be electrically insulated from the showerhead assembly 103. In some embodiments, the showerhead assembly 103 can be suspended below a top of the chamber body 102 by attaching the showerhead assembly 103 to an insulator 135 that electrically separates the showerhead assembly 103 from the chamber body 102.

[0026] In some embodiments which may be combined with other embodiments, the substrate support 150 may be electrically conductive. The substrate support 150 and the showerhead assembly 103 may be configured as opposing electrodes for generating a plasma 108a between the substrate support 150 and the showerhead assembly 103 during processing and / or a pre-treatment or post-treatment process. Additionally, the substrate support 150 and the showerhead assembly 103 may alsoPATENTAttorney Docket No.: 44024945WO01 be utilized to support a plasma 108b (Figure 1 B) of cleaning gases during a cleaning process.

[0027] The plasma processing system 100 can include a RF power source 105 that can be used to generate the plasma 108a between the showerhead assembly 103 and the substrate support 150 before, during, and after processing. The RF power source 105 may also be used to maintain energized species or further excite cleaning gases supplied from the remote plasma source 107. The RF power source 105 can be coupled to the showerhead assembly 103 to supply RF power for generating the plasma 108a. The RF power source 105 can also be connected to the chamber body 102 to allow for a return path for RF power. The RF power source 105 can make these corresponding connections to the showerhead assembly 103 and to the chamber body through an impedance matching circuit 121 .

[0028] The plasma processing system 100 includes a RF return device 200. In some embodiments, the plasma processing system 100 further includes a plurality of electrical connectors 113. The RF return device 200 electronically couples the substrate support 150 and the chamber body 102, which can be used as the ground connection for the RF power source 105. Although two RF return devices are illustrated in Figures 1 A and 1 B, it is contemplated that the plasma processing system 100 may include any number of RF return devices 200. The RF return device 200 may also be referred to as a side grounding device, and / or a bottom grounding device.

[0029] As described in further detail below, the RF return device 200 may be electrically conductive and may be configured to be mechanically and / or electrically coupled to the substrate support 150 during certain operations performed in the plasma processing system 100. For example, the RF return device 200 may be configured to selectively contact and / or provide a ground path between the substrate support 150 and the chamber bottom 117a of the grounded chamber body 102, as illustrated in Figure 1A. Alternatively, the RF return device 200 may be configured to selectively contact and / or provide a ground path between the substrate support 150 and the sidewalls 117b, 117c of the grounded chamber body 102. When the substrate support 150 is raised to the position shown in Figure 1A, or when the substrate supportPATENTAttorney Docket No.: 44024945WO01150 moves to the position shown in Figure 1 B, the RF return device 200 is in contact (e.g., electrical contact) with the substrate support 150.

[0030] The plasma processing system 100 may further include a shadow frame support 124 that extends inwardly into the processing volume 111 from the sidewalls 117b, 117c of chamber body 102. The shadow frame support 124 may be configured to support a shadow frame (not illustrated) that may be used during various operations performed in the plasma processing system 100. For example, a shadow frame may be used to protect portions of the substrate support 150 that remain exposed when supporting a substrate 101 during processing of the substrate 101.

[0031] An example RF current path during substrate 101 processing is schematically illustrated by arrows in Figure 1 A. The RF current generally travels from a first lead 123a of the RF power source 105 to a first output 106a of the impedance matching circuit 121 , then travels along an outer surface of the conduit 134 to a back surface of the backing plate 116, and then to a front surface of the gas distribution plate 114. From the front surface of the gas distribution plate 114, the RF current goes through plasma 108a and reaches a top surface of the substrate 101 or the substrate support 150, then through the RF return device 200 and / or the electrical connectors 113 to an inner surface 125 of the chamber bottom 117a of the chamber body 102. From the inner surface 125, the RF current returns to the to a second lead 123b of the RF power source 105 after going through a connection 106b to the impedance matching circuit 121.

[0032] In some embodiments, the return path of the RF current during processing may be dependent on a spacing between the substrate support 150 and the showerhead assembly 103, which is depicted as a distance D. The spacing of this distance D is controlled by the elevation of the substrate support 150. In one embodiment, the distance D can be between about 200 mils to about 2000 mils during processing, and different distances D can be used for different processes or when cleaning is performed. In one example, the distance D may be between 600 mils and 1200 mils. At the spacing D shown in Figure 1A, the RF return device 200 and the electrical connectors 113 may both remain electrically coupled to the RF power sourcePATENTAttorney Docket No.: 44024945WO01105. In this embodiment, the RF return path taken by the RF current may be based on the electrical properties and positioning of the RF return device 200 and the electrical connectors 113 with some of these properties including resistance, impedance, and / or conductance of the RF return device 200 and the electrical connectors 113.

[0033] Optionally, a reflector 151 is disposed below the substrate support 150, offset a distance, L. The distance, L, can be a distance can be about 1 mm to about 50 mm. For example, the reflector 151 can be disposed below the substrate support 150 by a distance of about 5 mm to about 30 mm. The reflector 151 can be coupled to the actuator 138 by the shaft 137, such that the reflector maintains the distance, L, from the substrate support 150 during the transition between the first position and the second position.

[0034] The reflector 151 includes a reflective material, such as a metallic material, a polished material, an alloy material, or a combination thereof. For example, the reflective material can include one or more of polished stainless steel, aluminum, polished aluminum, titanium, silver, gold, titanium, silica, or a combination thereof. The reflector 151 can include an emissivity of less than 0.4. Without being bound by theory, the reflector 151 can reduce heat that radiates from the substrate support 150 towards the RF return device 200 by reflecting heat towards the substrate support 150. Advantageously, an increase in the longevity of the RF return device 200 can occur due to the reduced heat exposure at the RF return device 200.

[0035] Figure 1 B is a schematic cross-sectional view of the plasma processing system 100 of Figure 1 A when the substrate support 150 is at a second position (e.g., a cleaning position), according to one or more of the embodiments described herein. In Figure 1 B, the plasma processing system 100 is shown without the substrate 101 to depict a chamber cleaning procedure, and arrows are shown to schematically depict RF current flow. In these embodiments, energized cleaning gases are flowed to the showerhead assembly 103 and the processing volume 111 from the remote plasma source 107 to supply a plasma 108b within the processing volume 111. During chamber cleaning, the substrate support 150 is moved away from the showerheadPATENTAttorney Docket No.: 44024945WO01 assembly 103 and RF power from the RF power source 105 may be applied to the processing volume 111 to maintain or further energize the cleaning gas from the remote plasma source 107. In some embodiments, the spacing or distance D of the substrate support 150 relative to the showerhead assembly 103 during chamber cleaning is greater than the spacing or distance D of the substrate support 150 relative to the showerhead assembly 103 during processing (e.g., deposition), for example as shown in Figure 1A. In some embodiments, the distance D between the substrate support 150 and the showerhead assembly 103 during a cleaning process is between about 200 mils to about 5000 mils, or greater. In Figure 1 B, the substrate support 150 is located at a distance from the RF return device 200, so that the substrate support 150 is electrically disconnected from the chamber body 102.

[0036] In some embodiments which may be combined with other embodiments, the RF return device 200 may be configured to be mounted on the chamber body 102 (e.g., on the chamber bottom 117a and / or a sidewall 117b, 117c of the chamber body 102) instead of on the substrate support 150. As a result of being located further away from the substrate support 150, the RF return device 200 and its components may be susceptible to lower temperatures (e.g., a reduction of about 15 °C to about 60 °C of temperature at the RF return device 200), resulting in a more durable and longer- lasting RF return devices.RF Return Device

[0037] Figures 2A and 2B are schematic cross-sectional views of a RF return device 200, according to one or more of the embodiments described herein. As described above, the RF return device 200 may be configured to be in electrical contact the substrate support 150. The RF return device 200 may include a cover plate 210, base plate 220, a bracket 230, a plurality of stacking plates 240, a first mounting plate 250, a mounting base 255, a second mounting plate 260, and a strap 270, as illustrated in Figures 2A and 2B.

[0038] The bracket 230 may be configured to couple the RF return device 200 to the chamber body 102. For example, the bracket 230 may couple the RF return device 200 to a chamber bottom 117a of the chamber body 102, as illustrated inPATENTAttorney Docket No.: 44024945WO01Figures 1 A and 1 B. The bracket 230 may be formed of an electrical conductor, such as a conductive metal (e.g., aluminum) or a material coated with a metal (e.g., aluminum), or an alloy (e.g., an aluminum-containing alloy). Without being bound by theory, the bracket 230 can include a metal material, e.g., aluminum, such that the RF impedance is suitable to transmit one or more RF currents from the substrate support 150 to the chamber body 102. In some cases, the bracket 230 may include one or more fasteners (not shown) configured to couple the bracket 230 (e.g., and the RF return device 200) to the chamber body 102. The fasteners may be implemented as screws or bolts. In some cases, the bracket 230 can include an aperture disposed centrally in the bracket 230. Without being bound by theory, the aperture can provide enhanced flexibility without increasing stress. Moreover, and without being bound by theory, the aperture can reduce the total surface area of the bracket 230, thereby reducing an amount of radiation received from the substrate support.

[0039] In some embodiments, which may be combined with other embodiments, the bracket 230 may be mechanically coupled to a first mounting plate 250. The first mounting plate 250 may be formed of a conductor, such as a conductive metal (e.g., aluminum) or a material coated with a metal (e.g., aluminum), or an alloy (e.g., an aluminum-containing alloy). Without being bound by theory, the first mounting plate 250 can include a metal material, e.g., aluminum, such that the RF impedance is suitable to transmit one or more RF currents from the substrate support 150 to the chamber body 102.

[0040] The first mounting plate 250 may be mechanically coupled to the cover plate 210. The cover plate 210 can include a ceramic material, e.g., an oxide such as aluminum oxide, zinc oxide, yttrium oxide, silicon oxide, or a combination thereof. The cover plate 210 can be fastened to the first mounting plate using one or more fasteners (not shown) configured to couple the cover plate 210 to the first mounting plate 250. The fasteners may be implemented as screws or bolts. Without being bound by theory, the cover plate 210 can reduce an amount of heat that is transferred from the substrate support to the strap 270, thereby reducing and / or eliminating RF return strap degradation and / or fracture. Moreover, and without being bound by theory, the coverPATENTAttorney Docket No.: 44024945WO01 plate 210 can prevent parasitic plasma from forming between the strap and the chamber body.

[0041] The plurality of stacking plates 240 and the base plate 220 may be disposed between the first mounting plate 250 and the mounting base 255. The plurality of stacking plates 240 can include a ceramic material, e.g., an oxide such as aluminum oxide, zinc oxide, ytrrium oxide, silicon oxide, or a combination thereof. Each stacking plate of the plurality of stacking plates 240 can include a rectangular, square, and / or substantially planar shapes. Without being bound by theory, the rectangular, square, and / or substantially planar shape can increase the surface area of each stacking plate of the plurality of stacking plates, thereby reducing heat transfer among subsequent stacking plates.

[0042] In some embodiments, which may be combined with other embodiments, the plurality of stacking plates 240 can include a range of about 2 stacking plates to about 10 stacking plates. Each stacking plate of the plurality of stacking plates 240 includes a height of about 0.1 cm to about 1 cm. Without being bound by theory, the plurality of stacking plates 240 can reduce an amount of heat that is transferred from the substrate support to the strap 270 due to the reduced width of the plurality of stacking plates 240 compared to the base plate 220, thereby reducing and / or eliminating RF return strap degradation and / or fracture. Additionally, and without being bound by theory, the interface between each stacking plate of the plurality of stacking plates can reduce heat transfer between stacking plates, thereby further reducing heat transfer. In some embodiments, a distance between the first mounting plate 250 and the base plate 220 may include a distance of about 0.2 cm to about 10 cm.

[0043] The base plate 220 can include a ceramic material, e.g., an oxide such as aluminum oxide, zinc oxide, ytrrium oxide, silicon oxide, or a combination thereof. The base plate 220 can be fastened to the mounting base 255 using one or more fasteners (not shown) configured to couple the base plate 220 to the mounting base 255. The fasteners may be implemented as screws or bolts. In some embodiments, which may be combined with other embodiments the base plate 220 and the plurality of stackingPATENTAttorney Docket No.: 44024945WO01 plates 240 are secured between the first mounting plate 250 and the mounting base 255 based on pressure. For example, a pressure of about 1 newton*meter (Nm) to about 5 N / m may be applied to secure the base plate 220 and the plurality of stacking plates 240 between the first mounting plate 250 and the mounting base 255. Without being bound by theory, the base plate 220 can reduce an amount of heat that is transferred from the substrate support to the strap 270, thereby reducing and / or eliminating RF return strap degradation and / or fracture.

[0044] The mounting base 255 may be formed of a conductor, such as a conductive metal (e.g., aluminum) or a material coated with a metal (e.g., aluminum), or an alloy (e.g., an aluminum-containing alloy). Without being bound by theory, the mounting base 255 can include a metal material, e.g., aluminum, such that the RF impedance is suitable to transmit one or more RF currents from the substrate support 150 to the chamber body 102. In some cases, the mounting base 255 may include one or more fasteners (not shown) configured to couple the strap 270 (e.g., and the RF return device 200) to the chamber body 102. The fasteners may be implemented as screws. The mounting base 255 can include a curved ledge along a lateral portion of the mounting base 255. The curved ledge can reduce a bend angle of the strap during movement, thereby reducing strain and breakage of the strap.

[0045] The second mounting plate 260 may be used to form the electrical connection between the chamber bottom 117a of the chamber body 102 and the substrate support 150 through the RF return device 200 (see e.g., Figure 1A). Because the RF return device 200 is electrically connected to the chamber bottom 117a of the chamber body 102, this contact between the second mounting plate 260 and chamber body 102 allows RF current from the RF power source 105 to flow between the substrate support 150 and the chamber bottom 117a of the chamber body 102, which may be connected to an electrical ground for the RF power source 105.

[0046] The first mounting plate 250, via the bracket 230 and mounting base 255, and the second mounting plate 260 are mechanically coupled to the strap 270. For example, the strap 270 may be mounted (e.g., fastened) to the first mounting platePATENTAttorney Docket No.: 44024945WO01250, via the bracket 230 and mounting base 255, and the second mounting plate 260. The strap 270 may also be referred to as a ground strap because the strap 270 may serve as a ground connection for the RF power provided by the RF power source 105. In some embodiments, the strap 270 can be an extension of the bracket 230, in which the bracket 230 extends to form the strap 270. For example, the strap 270 may be used to provide the electrical connection between the substrate support 150 and the chamber body 102. In this example, the RF return path taken by the RF current of the RF power source 105 may travel from the substrate support 150, the bracket 230, the strap 270, and to a chamber bottom 117a of the chamber body 102 to ground the RF current.

[0047] The strap 270 may include a first section 272 and a second section 274. The first section 272 can move relative to the second section 274 during processes performed in the plasma processing system 100, thereby changing (e.g., increasing or decreasing) an angle 276 between the first section 272 and the second section 274. For example, as the substrate support 150 is raised and the strap 270 extends upwards, the angle 276 between the first section 272 and the second section 274 increases. As a further example, as the substrate support 150 is lowered and the strap 270 extends downwards, the angle 276 between the first section 272 and the second section 274 decreases.

[0048] The strap 270 can be formed of a conductor, such as a conductive metal (e.g., aluminum) or a material coated with a metal (e.g., aluminum), or an alloy (e.g., an aluminum-containing alloy). In some embodiments, the strap 270 may be implemented as a V-strap, U-strap, or other strap including at least one angled or bent portion. One or more of the components of the RF return device 200 may have an anodized surface. The anodized surface may include anodized aluminum. The cover plate 210, the base plate 220, the bracket 230, the plurality of stacking plates 240, the first mounting plate 250, the mounting base 255, the second mounting plate 260, and the strap 270 of the RF return device 200 may have the anodized surface. For example, the cover plate 210, the base plate 220, and the plurality of stacking plates 240 of the RF return device 200 may have an anodized surface including an oxide, e.g., aluminum oxide.PATENTAttorney Docket No.: 44024945WO01

[0049] In some embodiments, which may be combined with other embodiments, an anodizing process may be applied to one or more of the components of the RF return device 200. Applying the anodizing process to components of the RF return device 200 may increase the resistance of the components to corrosion and wear without subsequently increasing particle contamination. For example, anodization may be applied to the cover plate 210, the base plate 220, and the plurality of stacking plates 240 of the RF return device 200, in which the strap 270 would not be anodized to avoid delamination and / or particle contamination complications. The anodization may include chromic acid anodizing, such as anodization MIL-A-8625.

[0050] Examples

[0051] A first heating cycle was performed on a processing system having the RF return device 200 of the present disclosure. The first heating cycle included heating a substrate support from room temperature, e.g., about 25 °C, to 420 °C. A nitrogen gas flow was introduced to the processing system at a flow rate of about 20 slm. Once the temperature of 420 °C was reached, the substrate support was stabilized at 420 °C for a period of 1 hour, in which no nitrogen gas was introduced. A first cooling cycle was performed on the processing system. The first cooling cycle included reducing the temperature of the substrate support from 420 °C to 230 °C. No nitrogen gas was introduced to the processing chamber during the first cooling cycle. A second heating cycle was performed on a processing system, in which the second heating cycle included heating the substrate support from 230 °C to 420 °C. A nitrogen gas flow was introduced to the processing system at a flow rate of about 20 slm. Once the temperature of 420 °C was reached, the substrate support was stabilized at 420 °C for a period of 1 hour, in which no nitrogen gas was introduced. A second cooling cycle was performed, in which the second cooling cycle included reducing the temperature of the substrate support from 420 °C to room temperature, e.g., about 25 °C. No nitrogen gas was introduced to the processing chamber during the second cooling cycle.

[0052] Example 1 : Average power ratioPATENTAttorney Docket No.: 44024945WO01

[0053] A power required to stabilize the substrate support after the first heating cycle and the second heating cycle of a processing system having a reflector was compared to processing system having no reflector. A nominal power of 100% was used to compare the power ratios between the processing system with the reflector and the processing system without the reflector. For example, as shown in FIG. 3, a power level of 100% would equate to the power required to stabilize the substrate support temperature following the first heating cycle and the second heating cycle. The power required to stabilize the substrate support temperature following the first heating cycle and the second heating cycle was determined at a center location, an inner location, and an outer location of the substrate support. The inner location was monitored at four locations, e.g., location A, location B, location C, and location D. The outer location was monitored at four locations, e.g., location E, location F, location G, and location H.

[0054] As shown in Figure 3, a reduction of power to stabilize the temperature of the substrate support at an inner location and outer location following the first heating cycle and the second heating cycle occurred. A total reduction of power of about 12% occurred in the processing system having the reflector, thereby providing a power savings of about 1500 W during processing. Without being bound by theory, a processing system having a reflector disposed below the substrate support was able to maintain more stable temperatures at reduced power consumption levels compared to processing systems that do not have a reflector.

[0055] Example 2: Substrate Support Temperature Rate of Change

[0056] As shown in Figure 4, a temperature rate of change during the first heating cycle, the second heating cycle, the first cooling cycle, and the second cooling cycle of a processing system having a reflector was compared to processing system having no reflector. An increase in temperature rate of change occurred during the first heating cycle of about 0.01 degrees / min. An increase in temperature rate of change occurred during the second heating cycle of about 0.05 degrees / min. A decrease in temperature rate of change occurred during the first cooling cycle of about -0.06 degrees / min. A decrease in temperature rate of change occurred during the secondPATENTAttorney Docket No.: 44024945WO01 cooling cycle of about -0.06 degrees / min. Without being bound by theory, a processing system having a reflector disposed below the substrate support was able to maintain achieve the processing temperatures at a faster rate, in which the processing temperatures were maintained for longer periods of time allowing longer processing windows to occur.

[0057] Example 3: Temperature comparison of RF return device following the second heating cycle

[0058] A temperature of an RF return device of a processing system was determined following the second heating cycle. A conventional RF return device (Reference) was compared to an RF return device of the present disclosure (Example). Both the Reference and Example were analyzed with or without a reflector present within the processing chamber. Temperatures were analyzed at four locations, e.g., location 1 , location 2, location 3, and location 4. Results are shown below in reference to table 1.Table 1.

[0059] As shown in Figures 5A and 5B, a decrease in temperature occurred in both the no reflector and reflector analyses in the Example processing chamberPATENTAttorney Docket No.: 44024945WO01 compared to the reference processing chamber, thereby increasing the durability and longevity of the RF return device due to the reduced temperatures of the RF return device. When a reflector was present in the processing chamber a greater reduction in temperature of the RF return device was achieved, thereby further increasing the durability and lifetime of the RF return device.

[0060] Example 4 Temperature comparison of RF return device following the first heating cycle

[0061] A temperature of an RF return device of a processing system was determined following the first heating cycle. A conventional RF return device (Reference) was compared to an RF return device of the present disclosure (Example). Both the Reference and Example were analyzed with or without a reflector present within the processing chamber. Temperatures were analyzed at four locations, e.g., location 1 , location 2, location 3, and location 4. Results are shown below in reference to table 2.Table 2.PATENTAttorney Docket No.: 44024945WO01

[0062] A decrease in temperature occurred in the reflector analyses for both the Example processing chamber and the Reference processing chamber. For example, a reduction of temperature of about 5 °C occurred in the Reference processing chamber and a reduction of temperature of about -20 °C occurred in the Example processing chamber, as shown in Figures 6A and 6B. Without being bound by theory, the Example RF return device in combination with a reflector provided a greater reduction in temperature, thereby further increasing the durability and lifetime of the RF return device.

[0063] In summation, the embodiments described herein provide a RF return device configured to be mounted on a chamber body (e.g., a chamber bottom 117a of the chamber body 102), in which the RF return device provides a grounding path between a substrate support and the process chamber. The RF return device components thereof, e.g., strap 270 may be susceptible to lower temperatures (e.g., less than 400 ° C instead of the conventional temperatures of greater than 400 °C), resulting in more durable and longer-lasting RF return devices. In addition, a reflector may be disposed along a bottom surface of the susceptor, thereby reducing radiation heat transfer between the susceptor and the RF return device. The reduction of radiation heat transfer can further reduce the temperature that the RF return device is exposed to, thereby enhancing the longevity of the RF return device.

[0064] 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

PATENTAttorney Docket No.: 44024945WO01What Is Claimed Is:1 . A radio frequency (RF) return device, comprising: a bracket mechanically coupled to a substrate support, a first mounting plate, and a mounting base; a cover plate mechanically coupled to the first mounting plate and the mounting base; a base plate disposed over the mounting base; a plurality of stacking plates disposed between the first mounting plate and the base plate; a strap mechanically coupled to the mounting base; and a second mounting base mechanically coupled to the strap.

2. The device of claim 1 , wherein the bracket, the first mounting plate, the mounting base, the strap, the second mounting base, or a combination thereof comprises a conductor.

3. The device of claim 2, wherein the conductor comprises a conductive metal.

4. The device of claim 3, wherein the conductive metal comprises aluminum or an aluminum-containing alloy.

5. The device of claim 1 , wherein the cover plate, the plurality of stacking plates, the base plate, or a combination thereof comprises a ceramic material.

6. The device of claim 5, wherein the ceramic material comprises an oxide.

7. The device of claim 6, wherein the oxide comprises aluminum oxide, zinc oxide, yttrium oxide, silicon oxide, or a combination thereof.

8. The device of claim 1 , wherein the strap comprises a first section and a second section.PATENTAttorney Docket No.: 44024945WO019. The device of claim 1 , wherein the second mounting base is mechanically coupled to a chamber bottom of a chamber body.

10. The device of claim 9, wherein the second mounting base is clamped to the chamber bottom of the chamber body.

11. A process chamber, comprising a chamber body; a substrate support disposed in the chamber body; and a RF return device, wherein the RF return device comprises: a bracket mechanically coupled to the substrate support, a first mounting plate, and a mounting base; a cover plate mechanically coupled to the first mounting plate and the mounting base; a base plate disposed over the mounting base; a plurality of stacking plates disposed between the first mounting plate and the base plate; a strap mechanically coupled to the mounting base; and a second mounting base mechanically coupled to the strap and the chamber body.

12. The process chamber of claim 11 , wherein the bracket, the first mounting plate, the mounting base, the strap, the second mounting base, or a combination thereof comprises aluminum or an aluminum-containing alloy.

13. The process chamber of claim 11 , wherein the cover plate, the plurality of stacking plates, the base plate, or a combination thereof comprises aluminum oxide, zinc oxide, yttrium oxide, silicon oxide, or a combination thereof.

14. The process chamber of claim 11 , wherein the strap comprises a first section and a second section.PATENTAttorney Docket No.: 44024945WO0116. The process chamber of claim 11 , wherein the second mounting base is mechanically coupled to a chamber bottom of the chamber body.

17. A process chamber, comprising a chamber body; a substrate support disposed in the chamber body; a reflector disposed below the substrate support; and a RF return device, wherein the RF return device comprises a plurality of stacking plates.

18. The process chamber of claim 17, wherein the reflector is offset a distance of about 1 mm to about 50 mm from the substrate support.

19. The process chamber of claim 17, wherein the reflector comprises a polished stainless steel, aluminum, polished aluminum, titanium, silver, gold, titanium, silica, or a combination thereof.

20. The process chamber of claim 17, wherein the reflector comprises an emissivity of less than 0.4.

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