Ground return for plasma processes

A method and apparatus for providing an electrically symmetrical ground or return path for electrical current between two electrodes is described. The apparatus includes at least on radio frequency (RF) device coupled to one of the electrodes and between a sidewall and/or a bottom of a processing chamber. The method includes moving one electrode relative to another and realizing a ground return path based on the position of the displaced electrode using one or both of a RF device coupled to a sidewall and the electrode, a RF device coupled to a bottom of the chamber and the electrode, or a combination thereof.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the present invention generally relate to a method and apparatus for processing substrates, such as solar panel substrates, flat panel substrates, or semiconductor substrates, using plasma. More particularly, embodiments of the present invention relate to a radio frequency (RF) current return path for a plasma processing chamber.

2. Description of the Related Art

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) substrates. PECVD is generally accomplished by introducing a precursor gas into a vacuum chamber having a substrate disposed on a 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 a radio frequency (RF) power to the chamber from one or more RF sources coupled to the chamber. The excited gas reacts to form a layer of material on a surface of a substrate that is positioned on a temperature controlled substrate support. The distribution plate is generally connected to a RF power source and the substrate support is typically connected to the chamber body providing a RF current return path.

Uniformity is generally desired in the thin films deposited using PECVD processes. For example, an amorphous silicon film, such as microcrystalline silicon film, or a polycrystalline silicon film is usually deposited using PECVD on a flat panel for forming p-n junctions required in transistors or solar cells. The quality and uniformity of the amorphous silicon film or polycrystalline silicon film are important for commercial operation. Therefore, there is a need for PECVD chambers with improved plasma and deposition uniformity.

As the demand for larger LCD's and solar panels continues to grow, so does the size of the substrate that is used to make the LCD's and solar panels. The size of the substrates now routinely exceeds 1 square meter in area. When compared to the size of semiconductor substrates, which typically are about 300 millimeters in diameter, it can be easily understood that a chamber sized to process a semiconductor wafer may not be sufficiently large to process a substrate of 1 square meter or larger. Thus, larger area processing chambers need to be developed.

These large area processing chambers may, in some cases, be identical to the semiconductor counterpart chambers where simply scaling up in size achieves acceptable results. In other cases, scaling up the size of the processing chamber is not effective, as unforeseen difficulties occur when scaling up the processing chambers. Designing large chambers for application of RF energy is one example where scaling does not produce satisfactory results.

Additionally, the process conditions for processes that are performed in the large area processing chambers may need to be adjusted. Determining proper gas flows, timing sequences, RF power application, temperature conditions, and other process variables may require a significant amount of research and experimentation that is far beyond routine.

Therefore, care needs to be taken to design a chamber that can process large area substrates.

SUMMARY OF THE INVENTION

Embodiments of the present invention generally relate to a method and apparatus for plasma processing a substrate. More particularly, embodiments of the present invention provide a plasma processing chamber having one or more radio frequency (RF) grounding or return devices adapted to provide an advantageous RF return path.

In one embodiment, a radio frequency return device for a plasma processing chamber is described. The return device includes a base having a shaft movably disposed within an opening formed in the base, a spring coupled between the base and the shaft, the spring comprising a first material made of a metal or metal alloy having an elastic property that is substantially the same at an ambient temperature and a processing temperature of about 200° C. or greater, and a second material substantially encasing the first material, the second material being different than the first material.

In another embodiment, a plasma processing system is described. The plasma processing system includes a chamber, and at least one electrode disposed within the chamber, the at least one electrode facilitating generation of a plasma within the chamber and movable relative to a second electrode within the chamber, the at least one electrode being maintained electrically coupled while moving relative to the second electrode by one or more flexible contact members, at least one of the one or more flexible contact members comprising a material made of a metal or metal alloy that substantially retains elasticity without plastically deforming when the material reaches a temperature above about 200° C.

In another embodiment, a method is described. The method includes moving a first electrode in a chamber relative to a second electrode, applying radio frequency power between the first electrode and the second electrode, and establishing a selective electrical connection between the first electrode and a grounded component of the chamber based on a distance between the first electrode and the second electrode.

In another embodiment, a method is described. The method includes applying a radio frequency power between the movable electrode and a fixed electrode disposed in a chamber, providing a first radio frequency return path to a bottom of the chamber, displacing the movable electrode relative to the fixed electrode, and providing a second radio frequency return path to a sidewall of the chamber through one or more compressible contact members.

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

Embodiments of the present invention generally relate to a method and apparatus for processing substrates using plasma and/or cleaning components using plasma. Embodiments described herein relate to methods of enhancing plasma formation and depositing materials onto a substrate by providing an improved ground or return path for electrical current. In the description that follows, reference will be made to a plasma enhanced chemical vapor deposition (PECVD) chamber, but it is to be understood that the embodiments herein may be practiced in other chambers as well, including physical vapor deposition (PVD) chambers, etching chambers, semiconductor processing chambers, solar cell processing chambers, and organic light emitting display (OLED) processing chambers to name only a few. Suitable chambers that may be used are available from AKT America, Inc., a subsidiary of Applied Materials, Inc., Santa Clara, Calif. It is to be understood that the embodiments discussed herein may be practiced in chambers available from other manufacturers as well.

Embodiments of the present invention are generally utilized in processing rectangular substrates, such as substrates for liquid crystal displays or flat panels, and substrates for solar panels. Other suitable substrates may be circular, such as semiconductor substrates. The chambers used for processing substrates typically include a substrate transfer port formed in a sidewall of the chamber for transfer of the substrate. The transfer port generally includes a length that is slightly greater than one or more major dimensions of the substrate. The transfer port may produce challenges in RF return schemes. The present invention may be utilized for processing substrates of any size or shape. However, the present invention provides particular advantage in substrates having a plan surface area of about 15,600 cm2and including substrates having a plan surface area of about a 90,000 cm2surface area (or greater). The increased size of the substrate surface area presents challenges in uniform processing due to the increased difficulty in providing a suitable ground path, particularly at or near the transfer port. Embodiments described herein provide a solution to these challenges during processing of the larger substrate sizes.

FIG. 1Ais a schematic cross-sectional view of one embodiment of a plasma processing system100. The plasma processing system100is configured to process a large area substrate101using plasma in forming structures and devices on the large area substrate101for use in the fabrication of liquid crystal displays (LCD's), flat panel displays, organic light emitting diodes (OLED's), or photovoltaic cells for solar cell arrays. The substrate101may be thin sheet of metal, plastic, organic material, silicon, glass, quartz, or polymer, among others suitable materials. The substrate101may have a surface area greater than about 1 square meter, such as greater than about 2 square meters. In other embodiments, the substrate101may include a plan surface area of about 15,600 cm2, or greater, for example about a 90,000 cm2plan surface area (or greater). The structures may be thin film transistors which may comprise a plurality of sequential deposition and masking steps. Other structures may include p-n junctions to form diodes for photovoltaic cells.

The plasma processing system100may be configured to deposit a variety of materials on the large area substrates101, including but not limited to dielectric materials (e.g., SiO2, SiOxNy, derivatives thereof or combinations thereof), semiconductive materials (e.g., Si and dopants thereof), barrier materials (e.g., SiNx, SiOxNyor derivatives thereof). Specific examples of dielectric materials and semiconductive materials that are formed or deposited by the plasma processing system100onto the large area substrates may include epitaxial silicon, polycrystalline silicon, amorphous silicon, microcrystalline silicon, silicon germanium, germanium, silicon dioxide, silicon oxynitride, silicon nitride, dopants thereof (e.g., B, P, or As), derivatives thereof or combinations thereof. The plasma processing system100is also 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). One example of depositing silicon thin films on the large area substrate101using the system100may be accomplished by using silane as a processing gas in a hydrogen carrier gas.

As shown inFIG. 1A, the plasma processing system100generally comprises a chamber body102including a bottom117aand sidewalls117bthat at least partially defines a processing volume111. A substrate support104is disposed in the processing volume111. The substrate support104is adapted to support the substrate101on a top surface during processing. The substrate support104is coupled to an actuator138adapted to move the substrate support at least vertically to facilitate transfer of the substrate101and/or adjust a distance D between the substrate101and a showerhead assembly103. One or more lift pins110a-110dmay extend through the substrate support104. The lift pins110a-110dare adapted to contact the bottom117aof the chamber body102and support the substrate101when the substrate support104is lowered by the actuator138in order to facilitate transfer of the substrate101, as shown inFIG. 1B. In a processing position as shown inFIG. 1A, the lift pins110a-110dare adapted to be flush with or slightly below the upper surface of the substrate support104to allow the substrate101to lie flat on the substrate support104.

The showerhead assembly103is configured to supply a processing gas to the processing volume111from a processing gas source122. The plasma processing system100also comprises an exhaust system118configured to apply negative pressure to the processing volume111. The showerhead assembly103is generally disposed opposing the substrate support104in a substantially parallel relationship.

In one embodiment, the showerhead assembly103comprises a gas distribution plate114and a backing plate116. The backing plate116may function as a blocker plate to enable formation of a gas volume131between the gas distribution plate114and the backing plate116. The gas source122is connected to the gas distribution plate114by a conduit134. In one embodiment, a remote plasma source107is coupled to the conduit134for supplying a plasma of activated gas through the gas distribution plate114to the processing volume111. The plasma from the remote plasma source107may include activated gases for cleaning chamber components disposed in the processing volume111. In one embodiment, activated cleaning gases are flowed to the processing volume111. Suitable gases for cleaning include fluorine (F2), nitrogen trifluoride (NF3), sulfur hexafluoride (SF6) and carbon/fluorine containing gases, such as fluorocarbons, for example octofluorotetrahydrofuran (C4F8O), carbonyl fluoride (COF2), hexafluoroethane (C2F6), tetrafluoromethane (CF4), perfluoropropane (C3F8), and combinations thereof. Although carbon and oxygen containing gases may be used, the gases are not favorable due to possible carbon and/or oxygen contamination.

The gas distribution plate114, the backing plate116, and the conduit134are generally formed from electrically conductive materials and are in electrical communication with one another. The chamber body102is also formed from an electrically conductive material. The chamber body102is generally electrically insulated from the showerhead assembly103. In one embodiment, the showerhead assembly103is mounted on the chamber body102by an insulator135.

In one embodiment, the substrate support104is also electrically conductive, and the substrate support104and the showerhead assembly103are configured to be opposing electrodes for generating a plasma108aof processing gases therebetween during processing and/or a pre-treatment or post-treatment process. Additionally, the substrate support104and the showerhead assembly103may be utilized to support a plasma108b(FIG. 1B) of cleaning gases during a cleaning process.

A radio frequency (RF) power source105is generally used to generate the plasma108abetween the showerhead assembly103and the substrate support104before, during and after processing, and may also be used to maintain energized species or further excite cleaning gases supplied from the remote plasma source107. In one embodiment, the RF power source105is coupled to the showerhead assembly103by a first output106aof an impedance matching circuit121. A second output106bof the impedance matching circuit121is electrically connected to the chamber body102.

In one embodiment, the plasma processing system100includes a plurality of first RF devices109aand a plurality of second RF devices109b. Each of the first RF devices109aand second RF devices109bare coupled between the substrate support104and a grounded component of the chamber body102. In one embodiment, the plurality of RF devices109aand109bare configured to control the return path for returning RF current during processing and/or a chamber cleaning procedure. Each of the first RF devices109aand the second RF devices109bmay be selectively activated to be open or closed to electrical current. Each of the plurality of RF devices109aand109bmay be spring forms, straps, wires, or cables adapted to provide a RF conductive medium between the substrate support104and a grounded component of the chamber body102. In one embodiment, the RF devices109aand109bare configured as straps made of, or coated with, a flexible conductive material. In one aspect, the RF devices109aand109bare configured as straps, with the RF devices109ahaving a shorter length than the RF devices109bto facilitate a shorter path for electrical current.

In one embodiment, the RF devices109a,109bmay be configured to make an RF return path open to (i.e., prevent the flow of) RF current. In this embodiment, the RF devices109aand109bmay be configured as a switch. In one aspect, the open/closed characteristic of each of the RF devices109a,109bmay be controlled by the elevation of the substrate support relative to the showerhead assembly103. In some embodiments, the current is prevented from flowing through a predetermined one of the RF devices109a,109bby the elevation of the substrate support, either by triggering a switch or electrically disconnecting the selected RF device from another portion of the RF return path. In one example, the selected RF device may be electrically disconnected from a grounded component of the chamber body102(i.e., a component of the chamber body102that is in electrical communication with the RF power source105). In one embodiment, the plurality of RF devices109aand109bare utilized as RF ground return devices. However, one or more of the plurality of RF devices109a,109bmay be used for other electrical connections to apply or carry electrical current within the plasma processing system100.

During processing, one or more processing gas is flowed to the processing volume111from the gas source122through the showerhead assembly103. A RF power is applied between the showerhead assembly103and the substrate support104to generate a plasma108afrom the processing gases for processing the substrate101. Uniformity of plasma distribution is generally desired during processing, although tuning of the plasma uniformity may also be useful. However, the distribution of the plasma108ais determined by a variety of factors, such as distribution of the processing gas, geometry of the processing volume111, the distance D between the showerhead assembly103and the substrate support104, variations between deposition processes on the same substrate or different substrates, deposition processes and cleaning process, and electrical properties of the RF devices109aand109b. The spacing between, or distance D, between the substrate support104and the showerhead assembly may be adjusted during pre-treatment, post-treatment, processing and cleaning in order to vary the ground return RF return paths. In one aspect, the RF devices109aare configured to be flexible and provide an open circuit for returning RF current based on the position of the substrate support104relative to the showerhead assembly103. In another aspect, the RF devices109aare configured to be flexible and provide a closed circuit for returning RF current based on the position of the substrate support104relative to the showerhead assembly103. In this embodiment, the flexibility of the RF devices109aprovides a closed circuit in a range of the distance D which allows the spacing between the substrate support104and showerhead assembly103to be adjusted while various processes are being performed. For example, the substrate support104may be moved relative to the showerhead assembly103while maintaining a closed circuit with the RF devices109a.

One embodiment of an RF current path is schematically illustrated by arrows inFIG. 1A. InFIG. 1A, the RF current path may be indicative of RF current flow during processing of the substrate101. The RF current generally travels from a first lead123aof the RF power source105to the first output106aof the impedance matching circuit121, then travels along an outer surface of the conduit134to a back surface of the backing plate116, then to a front surface of the gas distribution plate114. From the front surface of the gas distribution plate114, the RF current goes through plasma108aand reaches a top surface of the substrate101or the substrate support104, then through the plurality of RF devices109aand/or109bto an inner surface125of the chamber body102. From the inner surface125, the RF current returns to a second lead123bof the RF power source105from the impedance matching circuit121.

Although an example of returning RF current is shown inFIG. 1Aand described herein as travelling across or through one or all of the plurality of RF devices109aand109b, it is understood that arcing may inadvertently occur between the substrate support104and portions of the inner surface125of the chamber body102. Arcing, or arcing potential, may be caused by numerous conditions within the processing volume111. For example, arcing may be caused at least in part by the position or proximity of the substrate support104relative to grounded components of the chamber body102. Arcing, or arcing potential, is detrimental to processes performed in the system100. Additionally, components of the system100may be damaged by arcing. Thus, reducing or eliminating arcing or arcing potential in PECVD systems is a paramount challenge. The challenges are renewed whenever a process parameter is changed and/or when a larger substrate is used and solving these challenges require a significant amount of research and experimentation that is far beyond routine. The embodiments described herein meet these challenges by providing a RF device that may be utilized to minimize or eliminate arcing in these systems. Thus, in some embodiments, RF current is caused to preferentially flow across or through one or more of the plurality of RF devices109a,109bto minimize the potential of arcing between the chamber body102and the substrate support104. Additionally, positioning and/or spacing of the plurality of RF devices109a,109bmay be adjusted to minimize arcing or arcing potential and/or to enhance RF return.

In some embodiments, the returning RF current may travel across one or more of the plurality of RF devices109aas the shortest return path from the substrate support104and along the inner surface125of the sidewall117bto the second lead123b. In other embodiments, the returning RF current may travel across one or more of the plurality of RF devices109bas the shortest return path from the substrate support104and along the inner surface125of the chamber bottom117aand along the inner surface of the sidewall117bto the second lead123b. The different RF return paths across one or more of the plurality of RF devices109aand109bare explained in greater detail below.

RF Return During Processing

In one embodiment, the return path of the RF current during processing may be dependent on a spacing between the substrate support104and the showerhead assembly103, which is depicted as a distance D. The spacing is controlled by the elevation of the substrate support104. In one embodiment, the distance D is between about 200 mils to about 2000 mils during processing. At this spacing (e.g., elevation of the substrate support104), the RF devices109aand109bmay both remain electrically coupled to the RF power source105. In this embodiment, the RF return path taken by the RF current may be based on the electrical properties and positioning of the RF devices109aand109b. The electrical properties include resistance, impedance and/or conductance of the RF devices109aand109b. For example, since the plurality of RF devices109aare closer and have less impedance for the RF current returning to the second lead123bof the RF power source105, the RF current flows predominantly through the plurality of RF devices109awhile little or no RF current flows through the plurality of RF devices109b.

In one embodiment, a plurality of deposition processes may be performed with the substrate support104at different elevations or spacings. In one example, a first deposition process may be performed at a first spacing when the distance D is between about 200 mils to about 1500 mils. In this embodiment, the plurality of RF devices109aand the plurality of RF devices109bmay be electrically coupled to the substrate support104such that returning RF current flows across all of the RF devices109aand109b. In another example, a second deposition process may be performed at a second spacing when the distance D is greater than about 1200 mils to about 1800 mils, such as greater than about 1500 mils. In this embodiment, the plurality of RF devices109amay be electrically or physically disconnected from the substrate support104such that returning RF current flows solely across RF devices109b. In another example, other deposition processes may be performed at varied distances D between the first spacing and second spacing such that returning RF current flows across one or both of the plurality of RF devices109aand109b.

RF Return During Cleaning

FIG. 1Bis a schematic cross-sectional view of the plasma processing system100shown inFIG. 1A. In this Figure, the plasma processing system100is shown without a substrate to depict a chamber cleaning procedure. In this embodiment, energized cleaning gases are flowed to the showerhead assembly103and the processing volume111from the remote plasma source107to supply a plasma108bwithin the processing volume111. During chamber cleaning, the substrate support104is displaced away from the showerhead assembly103and RF power from the RF power source105may be applied to the processing volume111to maintain or further energize the cleaning gas from the remote plasma source107. In one embodiment, the spacing or distance D of the substrate support104relative to the showerhead assembly103during chamber cleaning is greater than the spacing or distance D of the substrate support104relative to the showerhead assembly103during processing. In one embodiment, the distance D between the substrate support104and the showerhead assembly103during a cleaning process is between about 200 mils to about 5000 mils, or greater.

In one embodiment, a plurality of cleaning steps or processes may be performed with the substrate support104at different elevations or spacings. In one example, a first cleaning process may be performed at a first spacing when the distance D is between about 1100 mils to about 1500 mils. In this embodiment, the plurality of RF devices109aand the plurality of RF devices109bmay be electrically coupled to the substrate support104such that returning RF current flows across all of the RF devices109aand109b. In another example, a second cleaning process may be performed at a second spacing when the distance D is less than about 1100 mils, such as between about 400 mils to 600 mils. In this embodiment, the plurality of RF devices109aand the plurality of RF devices109bmay be electrically coupled to the substrate support104such that returning RF current flows across all of the RF devices109aand109b. In yet another example, a third cleaning process may be performed at a third spacing when the distance D is greater than about 1500 mils, such as between about greater than 1500 mils to about 6000 mils, for example, about 5000 mils. In this embodiment, the plurality of RF devices109amay be electrically or physically disconnected from the substrate support104such that returning RF current flows solely across RF devices109b. The first, second and third cleaning spacing examples may be used together or separately as desired to clean the chamber and other cleaning processes may be performed at varied distances D between the first spacing and third spacing such that returning RF current flows across one or both of the plurality of RF devices109aand109b.

In one embodiment, the elevation of the substrate support104causes a condition that substantially prevents RF current from passing through the RF devices109a. This condition may be caused by providing an open RF circuit in the RF devices109a, or by changing the electrical, property of the RF devices109arelative to the RF devices109b. In one embodiment, the relatively lower position of the substrate support104in the cleaning position relative to the processing position causes the RF return current to flow from the substrate support104across the RF devices109bpreferentially relative to the RF devices109a. In one embodiment, the RF devices109aare detached from one of the sidewall117band the substrate support104when the substrate support104is in this lowered position, thereby creating an RF open condition in the RF devices109a. In this embodiment, the sole return path for RF current may be across the RF devices109b. In another embodiment, the RF devices109amay be connected, but the resistance of the RF devices109amay be greater than the resistance of RF devices109bwhich causes the RF return current to preferentially flow across RF devices109b. The varied resistance of the RF devices may be provided by temporarily coupling a variable resistance circuit to chosen RF devices109a.

RF Return in a Pre-Treatment Process

Before a deposition process, it is sometimes desirable to perform a pre-treatment process on the substrate101. Pre-treatment processes include flowing a pre-treatment gas to the showerhead assembly103and striking a plasma within the chamber above the substrate101. Suitable pre-treatment gases include inert gases or gases free of precursors that may deposit on the substrate, such as argon (Ar), nitrogen (N2), helium (He), ammonia (NH3) and combinations thereof and derivatives thereof, as well as any gas that does not contain a silane, such as SiH4. In one embodiment, a pre-treatment process includes forming a plasma of an inert gas or a gas that does not contain deposition precursors in order to heat the substrate in preparation for a deposition process. Using a plasma of an inert gas facilitates heating of the substrate101in conjunction with a heater disposed on the substrate support104. The pre-treatment heating of the substrate shortens the heating time of the substrate, which increases throughput. In another embodiment, a pre-treatment process includes forming a plasma of an inert gas or a gas that does not contain deposition precursors in order to minimize or eliminate static charges that may have built up in the substrate during substrate transfer. In this embodiment, the plasma redistributes or eliminates electrostatic forces that may have built up in or on the substrate and prepares the substrate for a deposition process.

In one embodiment, the return path of the RF current during a pre-treatment process may be dependent on a spacing between the substrate support104and the showerhead assembly103. The spacing between the substrate support104and the showerhead assembly103, depicted as distance D, may be some position between a processing position and a cleaning position, such as between about 200 mils to about 5000 mils, or greater. Thus, the pre-treatment position of the substrate support104relative to the showerhead assembly103may include a first or lower position (e.g. between about 1500 mils to about 5000 mils) and a second or high position (e.g. between 200 mils to about 1500 mils).

In this embodiment, the RF return path may include RF current returning to the second lead123bof the RF power source105along one or both of the plurality of RF devices109aand109b. In one aspect, the electrical properties of one or both of the plurality of RF devices109a,109bmay be changed to cause returning RF current to preferentially move across one or both of the plurality of RF devices109aand109b. In one embodiment, the elevation of the substrate support104causes a condition that substantially prevents RF current from passing through the RF devices109a. In one embodiment, the elevation of the substrate support104is determinative of the path of returning RF current across the plurality of RF devices109aand109b. In one example, when the elevation of the substrate support104is in the second or high position, the returning RF current flows predominately across the plurality of RF devices109a. The predominant flow across the RF devices109amay occur even when the plurality of RF devices109bare connected to and in electrical communication with the substrate support104and the chamber body102.

In one aspect, the returning RF current may preferentially flow across the RF devices109brelative to the RF devices109a. In one embodiment, the RF devices109aare detached from one of the sidewall117band the substrate support104when the substrate support104is in the first or lower position. In this embodiment, the sole return path for RF current may be across the RF devices109b. The flow across the RF devices109bmay occur even when the plurality of RF devices109aare connected to and in electrical communication with the substrate support104and the chamber body102. In another embodiment, the RF devices109bmay be configured to have different electrical properties or configured as open to RF current when the substrate support104is in the second or higher position. In this embodiment, the RF return path consists of RF current returning preferentially across the RF devices109a. In another aspect, the returning RF current flows across one or both of the plurality of RF devices109aand the plurality of RF devices109bbased on the shortest return path.

RF Return in a Post-Treatment Process

After a deposition process, it is sometimes desirable to perform a post-treatment process on the substrate101. Post-treatment processes include flowing a post-treatment gas to the showerhead assembly103and striking a plasma within the chamber above the substrate101. Suitable post-treatment gases include inert gases, such as argon (Ar), nitrogen (N2), helium (He), ammonia (NH3), hydrogen (H2) and combinations thereof and derivatives thereof. In one embodiment, a post-treatment process includes forming a plasma of an inert gas in order to minimize residual electrostatic charges on the substrate101to assist in lifting the substrate101from the upper surface of the substrate support104. Using a plasma of an inert gas facilitates redistribution of the electrostatic forces acting to hold the substrate101to the substrate support104and allows the substrate101to be moved away from the substrate support104for transfer.

In one embodiment, the return path of the RF current during a post-treatment process may be dependent on a spacing between the substrate support104and the showerhead assembly103. The spacing between the substrate support104and the showerhead assembly103, depicted as distance D, may be some position between a processing position and a cleaning position, such as between about 200 mils to about 5000 mils, or greater. Thus, the post-treatment position of the substrate support104relative to the showerhead assembly103may include a first or low position (e.g. between about 1500 mils to about 5000 mils) and a second or high position (e.g. between 200 mils to about 1500 mils).

In this embodiment, the RF return path may include RF current returning to the second lead123bof the RF power source105along one or both of the plurality of RF devices109aand109b. In one embodiment, the position of the substrate support104relative to the showerhead assembly103and/or the inner surface125of the chamber body102provides the least resistive path for the RF return. In one aspect, the electrical properties of one or both of the plurality of RF devices109a,109bmay be changed to cause returning RF current to preferentially move across one or both of the plurality of RF devices109aand109b. In one embodiment, the elevation of the substrate support104causes a condition that provides a preferential RF return path across the plurality of RF devices109a. The preferential flow across the RF devices109amay occur even when the plurality of RF devices109bare connected to and in electrical communication with the substrate support104and the chamber body102.

In another embodiment, the returning RF current may preferentially flow across the RF devices109brelative to the RF devices109abased on the position of the substrate support104. The preferential flow across the RF devices109bmay occur even when the plurality of RF devices109aare connected to and in electrical communication with the substrate support104and the chamber body102. In one embodiment, the RF devices109aare detached from one of the sidewall117band the substrate support104when the substrate support104is in the first or lower position. In this embodiment, the sole return path for RF current may be across the RF devices109b. In another embodiment, the RF devices109bmay be configured to have different electrical properties or configured as open to RF current when the substrate support104is in the second or higher position. In this embodiment, the RF return path consists of RF current returning preferentially across the RF devices109a. In another aspect, the returning RF current flows across one or both of the plurality of RF devices109aand the plurality of RF devices109bbased on the shortest return path.

FIG. 2Ais a schematic cross-sectional view of one embodiment of a RF device109bconfigured as a flexible cable, sheet material or a strap200. A first end238of the strap200is electrically coupled to the substrate support104by a connection assembly230. In one embodiment, the connection assembly230is connected to a lower side240of the substrate support104. A second end239of the RF device109bis electrically coupled to the chamber bottom117aby a connection assembly229. The RF device109bmay be coupled to the substrate support104and the chamber bottom117aby other mechanisms such as, for example, fasteners235,236, such as screws, clamps or other methods that maintain an electrical connection between the substrate support104, the RF device109b, and the chamber bottom117a. As shown inFIG. 2A, the connection assembly230comprises a shaped clamp232and one or more fasteners235. The connection assembly229also comprises a shaped clamp231and one or more fasteners236.

The connection assemblies229,230each comprise low impedance conductive materials that are resistant to processing and cleaning chemistries. In one embodiment, the connection assemblies229,230comprise aluminum. Alternatively, the materials may comprise titanium, nickel, stainless steel, alloys or combinations thereof, or other suitable materials. In another embodiment, the materials for the connection assemblies229,230may comprise a nickel-molybdenum-chromium alloy, such as a HASTELLOY® material or a HAYNES® 242® material.

FIG. 2Bschematically illustrates an elevation view of the strap200shown inFIG. 2A. The strap200is generally a flat conductive band which is flexible and does not exert a significant restoring (e.g., spring) force when bent. In one embodiment, the strap200comprises a flexible, low impedance conductive material which is resistant to processing and cleaning chemistries. In one embodiment, the strap200is comprised of aluminum. Alternatively, the strap200may comprise titanium, nickel, stainless steel, beryllium copper, alloys or combinations thereof that is coated, wrapped or clad with aluminum or a conductive metallic sheath or coating. In another embodiment, the strap200comprises a nickel-molybdenum-chromium (Ni—Mo—Cr) alloy, such as a HASTELLOY® material or a HAYNES® 242® material. The Ni—Mo—Cr alloy material may be coated, wrapped or clad with aluminum or a conductive metallic sheath or coating.

In one embodiment, the first end238of the strap200has a mounting slot233and the second end239has a mounting slot234. In one embodiment, the strap200has a central slot237configured to increase the flexibility of the strap200and/or to facilitate clearance for a lift pin shaft, such as the shafts of the lift pins110a-110dshown inFIGS. 1A-1B. In one aspect, the central slot237is sized larger than a diameter of a lift pin shaft to facilitate bending of the strap200when the RF device109bis adjacent a lift pin.

FIG. 3Ais a schematic cross-sectional view of one embodiment of a RF device109aconfigured as a flexible cable, sheet material or a strap300. In one embodiment, the RF device109ashown inFIG. 3Amay be used in the chamber body102to provide an electrically conductive path between the substrate support104and the sidewalls117bin portions of the chamber where the sidewalls117bare flat or continuous and do not include a substrate transfer port. Respective ends of the RF device109ainclude connection assemblies329and330configured similarly to the connection assemblies229and230ofFIG. 2A. Fasteners335and336couple the RF device109ato the substrate support104and sidewall117bof the chamber body, respectively. The strap300is generally a flat conductive band which is flexible and does not exert a significant restoring (e.g., spring) force when bent. In one embodiment, the RF device109acomprises a flexible, low impedance conductive material which is resistant to processing and cleaning chemistries. In one embodiment, the strap300is comprised of aluminum. Alternatively, the strap300may comprise titanium, nickel, stainless steel, beryllium copper, alloys or combinations thereof that is coated, wrapped or clad with aluminum or a conductive metallic sheath or coating. In another embodiment, the strap300comprises a nickel-molybdenum-chromium (Ni—Mo—Cr) alloy, such as a HASTELLOY® material or a HAYNES® 242® material. The Ni—Mo—Cr alloy material may be coated, wrapped or clad with aluminum or a conductive metallic sheath or coating.

In this embodiment, the position of the substrate support104is a raised position, which may be a processing position. The raised position of the substrate support104spaces the substrate support104away from the chamber bottom117a, which stretches, straightens or elongates the RF device109b. In one embodiment, the less resistive path for RF current may be along the RF device109abased on the greater distance and/or resistance posed by the elongated orientation of the RF device109b. In one example, the less resistive path for returning RF current may be in the direction of the arrow such that the returning RF current may preferentially travel along RF device109ainstead of along RF device109b. In other embodiments, at least a portion of the returning RF current may travel along one or both of the RF devices109aand109b.

FIG. 3Bis a schematic cross-sectional view the RF devices109aand109bofFIG. 3A. In this embodiment, the substrate support104is in a lowered position, which may be a transfer position or a cleaning position. The lowered position of the substrate support104brings the substrate support104in close proximity to the chamber bottom117a, and the RF device109ais stretched, straightened or elongated. In one embodiment, the less resistive path for RF current may be along the RF device109bbased on the greater distance and/or resistance posed by the elongated orientation of the RF device109a. In one example, the less resistive path for returning RF current may be in the direction of the arrow such that the returning RF current may travel preferentially along RF device109binstead of along RF device109a. In other embodiments, at least a portion of the returning RF current may travel along one or both of the RF devices109aand109b.

FIG. 4is a schematic cross sectional view of another embodiment of a plasma processing system400. Portions of the plasma processing system400are similar to plasma processing system100shown inFIGS. 1A and 1Band are not duplicated for brevity. In this embodiment, the substrate support104is shown in a transfer position. In this embodiment, at least one of the sidewalls117bincludes a substrate transfer port412sized to allow passage of a substrate101retained on a factory transfer device, such as a robot or end effector (not shown). The transfer port412may be configured as a slit valve and includes a sealable door410adapted to open the transfer port412during substrate transfer and seal the processing volume111when closed. One or more lift pins110a-110dextend through the substrate support104to support the substrate101when the substrate101is received from the end effector (not shown) through the port412and when the substrate is ready to be received by the end effector.

A sidewall area405is shown adjacent the transfer port412. The sidewall area405is different than other portions of the sidewall117bas the transfer port412includes a passage or void formed in the inner surface125of the sidewall117bthat is not present in other portions of the sidewalls117bof the chamber body102. For example, if the chamber body is rectangular, three of the sidewalls117bare flat and/or include a substantially planar and continuous inner surface125while a fourth sidewall117bincludes the sidewall area405that is non-flat and/or non-continuous because of the passage defining the transfer port412. The differences between the inner surfaces125of the three sidewalls and the inner surface of the sidewall area405produce incongruent RF return patterns. In one example, RF power applied to the chamber does not a travel symmetrically within the processing volume111. In one aspect, the existence of the transfer port412provides a space where RF current may not concentrate or is minimal because the passage or space defining the transfer port412does not conduct RF current. This results in uneven plasma at or near the port412and uneven deposition on the substrate101in the area at or near the transfer port412relative to other portions of the substrate101. The different sidewalls require different RF return schemes to optimize the RF return and/or prevent arcing in the sidewall area405. In one embodiment, three of the sidewalls117bthat do not include the transfer port412may include the RF devices109autilizing straps300as shown inFIGS. 3A and 3B. However, the RF devices109aon the side of the substrate support104adjacent the transfer port412are adapted to move with the substrate support104, in one embodiment, in order to provide clear access for substrate transfer between the lift pins110a-110dand the transfer port412.

In this embodiment, at least a portion of the RF devices109aare depicted as a plurality of compressible contact members415. The compressible contact members415may be coupled directly to the substrate support104or by a bracket452. The compressible contact members415are thus movable with the substrate support104. In one embodiment, each of the contact members415includes a contact portion456adapted to contact one or more plates or extended members458coupled to the sidewalls117bof the chamber body102. In one aspect, each of the extended members458comprise a plurality of discrete plates extending from the inner surface125of the chamber body102. In one embodiment, the contact portion456and extended members458comprise a conductive material and are utilized to provide a path for electrical current. Each of the compressible contact members415also include an elastic portion454adapted to compress and expand or decompress in response to contact between the contact portion456and a respective extended member458based on the elevation of the substrate support104. In one embodiment, the plasma processing system400includes a shadow frame460adapted to circumscribe at least a portion of the perimeter of the substrate101and the substrate receiving surface of the substrate support104during processing. When the substrate support104is in a transfer position as shown, the shadow frame460may rest on an upper surface of the extended members458.

FIG. 5is a schematic cross sectional view of the processing system400ofFIG. 4showing the substrate101in a processing position. After the end effector (not shown) places the substrate101onto the lift pins110a-110das shown inFIG. 4, the end effector retracts from the processing volume111and the door410may be closed to seal the transfer port412. The substrate support104then raises while the lift pins110a-110dremain stationary until the substrate support104is in the processing position. While the substrate support104moves to the processing position, the substrate support104comes into contact with the substrate101supported by the lift pins110a-110d. The substrate101begins to contact the substrate support104in a center to edge manner due to the sagging of the substrate101. The lift pins110a-110dremain stationary as the substrate support104raises until the substrate support104has raised to a position such that the substrate101supported by the lift pins110a-110dis supported by the substrate support104.

By raising the substrate support104, the lift pins110a-110dare lowered relative to the substrate receiving surface of the substrate support104to place the substrate101on the substrate receiving surface in a substantially flat orientation. In embodiments where a shadow frame460is utilized, the shadow frame460is contacted by the substrate101and/or substrate support104to lift the shadow frame460from a resting position to circumscribe the substrate101and/or the substrate support104. At some position after the substrate101contacts the substrate support104, a pre-treatment process as described above may be performed on the substrate101. Lifting of the substrate support104also provides contact between the contact portions456of the RF devices109aand the extended members458. Thus, returning RF current may be facilitated by the RF devices109aand/or109bin this embodiment.

FIG. 6is a schematic cross-sectional top view of the chamber body102taken along lines6-6ofFIG. 5to show one embodiment of the positioning of the RF devices109a. The chamber body102is shown with the substrate support104disposed therein and the RF devices109aare disposed in a space between the interior surface of the chamber body102and the substrate support104. The contact portions456are adapted to contact the extended members458(four are shown in phantom) to provide a RF return path for the applied RF power. The spacing and concentration of the RF devices109aare configured to provide symmetry in the RF return path to facilitate plasma uniformity and enhanced deposition uniformity on the substrate101(shown in phantom).

In one embodiment, the spacing and concentration of the RF devices109ais adapted to provide a symmetrical appearance to the applied RF power to account for variances in the chamber construction, such as the passage defined by the transfer port412. The spacing or concentration allows the applied RF power to travel symmetrically in the processing volume111when the chamber may not be physically and/or electrically symmetrical. In one aspect, each of the RF devices109aand extended members458are adapted as individual or modular units that may be coupled to the substrate support104at desired positions and may be moved or removed from an existing position, if desired. The modular adaptation allows the RF return path to be tuned by adding, removing, or repositioning RF devices109aas desired. In one embodiment, the RF devices109aare substantially evenly spaced around the perimeter of the substrate support104. In other embodiments, the RF devices109amay be added or removed from different locations of the substrate support104, as needed.

FIGS. 7A and 7Bare isometric and side views, respectively, of one embodiment of a RF device109adepicted as a compressible contact member415. In this embodiment, the compressible contact member415is mounted on a base705that may be coupled to the bracket452(shown in phantom). In another embodiment, the contact member415may be integrated to be part of the bracket452. The bracket452, in turn, would be coupled to a substrate support104(not shown). In one embodiment, the base705includes an opening706adapted to receive a first shaft707. The first shaft707is movably disposed through the opening706to provide relative movement between the base705and the first shaft707. The first shaft707is coupled to a second shaft709that is received inside the spring form710B. A collar713is coupled to the second shaft709to provide a base for the spring form710B. In one embodiment, the first shaft707is movable to any position within a travel distance indicated as750inFIG. 7B. The travel distance750corresponds to the distance range that the substrate support104may be adjusted during various processes while maintaining electrical contact or grounding potential between the substrate support104and the chamber body102.

The compressible contact member415includes at least one elastic portion, shown in this embodiment as spring forms710A and710B. Spring forms710A,710B provide elasticity to the compressible contact member415while spring form710A additionally provides a conductive path for electrical current. In one embodiment, the spring form710B is coupled to a tubular member712having a mounting portion714that houses the spring form710B and provides a mounting interface to couple with the base705.

The compressible contact member415includes a contact pad715coupled to a head portion716of the first shaft707. A first end of the spring form710A is coupled to and in electrical communication with the contact pad715and in one embodiment is sandwiched between the head portion716and the contact pad715. Fasteners, such as bolts or screws may be used to couple the contact pad715to the head portion716. The second end of the spring form710A is coupled to and in electrical communication with the base705by a contact pad cap717which, in one embodiment, sandwiches the spring form710A to the base705. Fasteners, such as bolts or screws may be used to couple the contact pad cap717to the base705.

Referring toFIGS. 7A and 7B, spring forms710A,710B may be a flexible material made with conductive or composite materials having properties that carry or conduct an electrical current. In one embodiment, the flexible material may be sheet material, such as sheet metal or foil, a cable or wire, and combinations thereof, or other conductive elastic member or conductive material. The spring forms710A,710B may be exposed to the processing environment in the plasma processing systems100and400as described herein and the flexible materials are chosen to survive and operate in the extremes encountered in the processing environments. In one embodiment, the flexible material for the spring forms710A,710B may be a metal or metal alloy that substantially retains flexible properties, such as mechanical integrity and/or spring properties, during processing conditions. In one aspect, a first or core flexible material for the spring forms710A,710B includes any metal or metal alloy that substantially retains flexible properties when the flexible material reaches temperatures above 200° C., for example temperatures above about 250° C. to about 300° C. In one embodiment, the flexible property of the first or core material retained at the temperature above 200° C. or up to and including 300° C. is substantially similar to the flexible property of the core material at ambient temperature.

In some embodiments, the flexible material may be in the form of a flat spring, a coil spring, a compression spring or other flexible spring device or spring form. In one embodiment, the spring forms710A,710B comprise a metallic material or metallic alloy, which may additionally be coated, wrapped or clad with a conductive material. Examples of metals and metal alloys include nickel, stainless steel, titanium, a MONEL® material, a HASTELLOY® material, a HAYNES® alloy, such as a HAYNES® 242® material, beryllium copper, or other conductive elastic materials. Examples of conductive materials for the coating, wrapping or cladding include aluminum, anodized aluminum, or other coating, film, or sheet material. In one embodiment, the spring form710A comprises a nickel or titanium alloy sheet material that is wrapped or covered with an aluminum material. In another embodiment, the spring form710A comprises a Ni—Mo—Cr alloy, such as a HASTELLOY® material or a HAYNES® 242® material. The Ni—Mo—Cr alloy material may be coated, wrapped or clad with aluminum or a conductive metallic sheath or coating. In one embodiment, the spring form710B comprises a MONEL® 400 material while the spring form710A comprises a HAYNES® 242® material wrapped with an aluminum foil.

The base705, the pad715, the cap717, the first shaft707and the tubular member712may be made of a conductive material and additionally may be coated or wrapped with a conductive material. Examples of conductive material include aluminum, anodized aluminum, nickel, titanium, stainless steel, alloys thereof or combinations thereof. In one embodiment, the pad715, cap717, first shaft707and tubular member712are made of an anodized aluminum material or a conductive material such as nickel, titanium, stainless steel, alloys thereof or combinations thereof, and coated, wrapped or clad with a conductive material, such as aluminum.

FIG. 7Cis an enlarged view of a portion of the spring form710A ofFIG. 7Bin cross-section. In one embodiment, the spring form710A includes a first or core material770and second material or outer material775. In one embodiment, the core material770and the outer material775comprise the same material, such as a conductive material that is resistant to process chemistries and the process environment. For example, the core material770and the outer material775may comprise aluminum. The aluminum material provides a conductive outer covering that is highly resistant to process chemistries. However, the physical and/or mechanical attributes of aluminum materials may degrade at elevated temperatures and/or repeated compression and decompression. In one example, aluminum includes properties such as tensile strength and modulus of elasticity (Young's modulus) that decrease with increases in temperature. Additionally, yield stress of aluminum may be dramatically lessened at temperatures above about 205° C. and is diminished to a greater extent at higher temperatures. For example, the ultimate tensile strength value of aluminum at a temperature of about 200° C., or greater, is about 40% to about 60% less than the ultimate tensile strength value of aluminum at ambient temperature. Thus, while aluminum may be utilized for the spring form710A, repeated cycling (compression and decompression) and/or elevated temperatures may cause a loss in ductility and may result in failure of the spring form710A.

In another embodiment, the core material770is different than the outer material775and the outer material775is supported by the core material770. In one embodiment, the core material770comprises a material that retains physical and/or mechanical properties at elevated temperatures while the physical and/or mechanical properties of the outer material775may be diminished at elevated temperatures. In one aspect, the flexible and/or ductile properties of the core material770retained at temperatures above about 200° C. is substantially similar to the flexible and/or ductile properties of the core material770at ambient temperature. For example, the outer material775may be aluminum while the core material770may be a metallic alloy. In one embodiment, the core material770has substantially the same properties at ambient temperature or room temperature (e.g., about 25° C.) as when the core material770reaches temperatures of about 200° C. or greater. In one aspect, the core material770has an ultimate tensile strength of about 1250 MPa to about 1290 MPa at room temperature and an ultimate tensile strength of about 1050 MPa to about 1100 MPa at about 425° C. Therefore, the ultimate tensile strength of the core material770is substantially unchanged at temperatures between room temperature and about 200° C. and the core material770thus retains mechanical integrity at the elevated temperatures. In one embodiment, at about 200° C., the core material770retains substantially 85% of the physical and/or mechanical properties possessed at ambient temperature. In another embodiment, at about 200° C., the core material770retains substantially 90% or greater, such as about 95%, of the physical and/or mechanical properties possessed at ambient temperature.

The core material770provides mechanical and/or physical properties that are superior to the aluminum outer material775at temperatures above about 200° C. In one aspect, the core material770and the outer material775differ as the outer material775may reach a fatigue limit in a shorter time period than the core material770due to the elevated temperatures and/or repeated compression and decompression. In one embodiment, the core material770is made from a Ni—Mo—Cr alloy, such as a HASTELLOY® material or a HAYNES® 242® material. The Ni—Mo—Cr alloy has excellent ductility and yield strength retention at temperatures above 200° C., particularly at temperatures greater than about 205° C., for example, between about 210° C. and about 300° C. At these elevated temperatures, a solid aluminum spring form710A may experience a ductility loss. However, the outer material775(aluminum) may be in the form of a coating or foil that is coupled to the core material770and any weakening of the outer material775does not affect the mechanical stability of the core material770. Thus, the spring form710A is resilient and retains mechanical integrity of the spring form710A at elevated temperatures. Although the Ni—Mo—Cr alloy material has excellent corrosion resistant properties, especially in fluorine-containing environments, the outer material775may protect the core material770from plasma and/or gases in the processing volume111.

FIG. 8Ais an isometric cross-sectional view of one embodiment of coupling arrangement for a plurality of compressible contact members415as seen from an interior of the chamber body102. The substrate support104is shown in a raised position such that the contact pads715(not shown in this view) are in contact with the extended members458extending from the inner surface125of the sidewall117b. In this embodiment, each of the compressible contact members415are coupled to an individual bracket452. Each of the brackets452are coupled to the substrate support104. The brackets452may be added or removed as desired in order to tune the RF return path adjacent the transfer port412.

FIG. 8Bis a top view of a portion of the chamber body102ofFIG. 8A. A portion of the contact pad715is shown below the extended member458. It is noted that the compressible contact member415is accessible between the side of the chamber body102and the substrate support104. Thus, when the substrate support104is lowered to a position below the transfer port412, the compressible contact members415may be accessed within the chamber body102from a position above the substrate support104through the transfer port412for maintenance, inspection, replacement or removal by personnel. In one embodiment, two fasteners780coupling the base705to the bracket452may be removed to disengage the base705from the bracket452. Thus, the compressible contact member415may be easily removed or replaced by removal or attachment of the two fasteners780, respectively.

FIG. 9Ais an isometric view of another embodiment of a compressible contact member900coupled to a bracket452. In this embodiment, the bracket452is configured as a bar that is coupled to a substrate support104. In this embodiment, the compressible contact member900is similar to the compressible contact member415shown inFIGS. 8A-8Bwith the exception of three spring forms910A-910C. Spring forms910A,910B may be made of materials having properties that carry or conduct an electrical current. In one embodiment, each of the spring forms910A-910C may be made of the same materials as the spring forms710A,710B described inFIGS. 8A-8B.

In one embodiment, the spring forms910A,910B may be a continuous single sheet material or a single flat spring having two ends905A,905B. Alternatively, the spring forms910A,910B may be two separate, discontinuous pieces of sheet material or two flat springs coupled at respective ends at the contact pad715. In this embodiment, a collar713is shown that is coupled to a second shaft709disposed within the tubular member712. The collar713may be made of a conductive material, such as aluminum or anodized aluminum. The collar713may comprise a nut or include a threaded portion for a set screw that is adapted to fix to the second shaft709. The second shaft709may be of a reduced dimension, such as a diameter, to allow the spring form910C to fit thereover.

FIG. 9Bis an exploded isometric view of the compressible contact member900shown inFIG. 9A. In this embodiment, a spring form910D is a single continuous sheet material or a single flat spring. The spring form910D may be fabricated from the same materials described in reference to spring forms710A.

FIGS. 9C and 9Dare isometric views of one embodiment of a bracket452that includes one or more bases705that are integral to the bracket452. In this embodiment, the bracket452is configured as an elongated bar that is coupled to the substrate support104. The bracket452also includes empty bases915that may be used to couple additional compressible contact members900, if desired, which enhances the modularity of the compressible contact members.

FIG. 10Ais a schematic view of another embodiment of a compressible contact member1000. In this embodiment, the compressible contact member1000is shown from an interior portion of the chamber body102adjacent the port412. From the perspective in the interior of the chamber body102, the port412includes a tunnel1008formed through a sidewall1002that is bounded by an upper portion1004and a lower portion1006of the tunnel1008. The compressible contact member1000includes spring forms1010A,1010B coupled to a contact pad715and a base1005. The spring forms910A,910B may be made from the same materials described in reference to spring forms810A and810B. The spring forms1010A,1010B may be made from the same materials described in reference to spring forms710A.

The base1005is coupled to a bracket452and/or the substrate support104, both of which are not shown in this view for clarity. In the raised position, the contact pad715is adapted to contact a contact surface1060of an extended member458that is fixedly coupled to the interior sidewall1002of the chamber body102. As the compressible contact member1000is coupled to the substrate support and is shown in this view in a raised position, the substrate support would obscure the view of the compressible contact member1000and portions of the extended member458. When the substrate support is lowered for a substrate transfer operation, the compressible contact member1000would move with the substrate support104such that no portion of the compressible contact member1000would interfere with the transfer operation at the port412.

FIG. 10Bis a schematic view of another embodiment of a compressible contact member1000. The compressible contact member1000is shown from an interior portion of the chamber body102at the port412similar to the view ofFIG. 10A. The compressible contact member1000includes spring forms1010A,1010B coupled to a contact pad715and a base1005. The base1005is coupled to a bracket and/or a substrate support, both of which are not shown as the presence of the substrate support would obscure the view of the compressible contact member1000. In this embodiment, the spring forms1010A,1010B are coupled to spacers1018. The spring forms1010A,1010B and may be made from the same materials described in reference to spring forms710A.

FIGS. 11A and 11Bare side cross-sectional views of a portion of the chamber body102showing another embodiment of a compressible contact member1000ofFIG. 10Acoupled to a substrate support104.FIG. 11Ashows the compressible contact member1000and the substrate support104in a raised position andFIG. 11Bshows the compressible contact member1000and the substrate support104in a lowered position. As described above, when the substrate support104is in a lowered position, no portion of the compressible contact member1000is in a position to interfere with the port412.

FIG. 12Ais an isometric side view of another embodiment of a compressible contact member1200. The contact member1200includes a single spring form1210. The single spring form1210may be in the form of a continuous flat piece of material and may comprise the same material as is described in reference to the spring form710A. In this embodiment, the spring form1210comprises one or more bends1215A-1215C adapted to increase compressive force of the spring form1210. In this embodiment, each of the bends1215A-1215C includes a corresponding bend on an opposite side of the spring form1210in a substantial mirror image. In one embodiment, the spring form1210shown inFIG. 12Acomprises a shape similar to the omega symbol (Q). It has been found that the omega-shaped spring form1210extends the life of the spring form1210.

FIGS. 12B-12Eare side views of various embodiments of the spring form1210that may be utilized with the contact member1200shown inFIG. 12A. Each of the spring forms1210may comprise the same material as is described in reference to the spring form710A.

FIGS. 13A and 13Bare cross-sectional views of another embodiment of a compressible contact member1300. The contact member1300includes a spring form1310that may comprise the same material as is described in reference to the spring form710A and any of the shapes shown inFIGS. 12A-12E. The contact member1300includes a spring form910C and may be made of the same materials as the spring form710B described inFIGS. 7A and 7B. The contact member1300includes a construction similar to the construction of the contact member shown inFIGS. 9A and 9Bwith the exception of a roller assembly1305and an inner tubular member1308. The inner tubular member1308is adapted to receive the second shaft709as shown inFIG. 13C.

The roller assembly1305includes one or more rollers or bearings1315connected to a housing1320by a respective shaft1325. Each of the bearings1315are adapted to be at least partially disposed in a cavity1330formed in the housing1320. At least a portion of the bearings1315are adapted contact in inner surface of the tubular member712as the spring form1310is compressed or decompressed. The housing1320is configured as a stop for the spring form910C and includes a lower housing1335adapted as a stop for the opposing side of the spring form910C.

FIG. 13Cis an exploded isometric view of the contact member1300shown inFIGS. 13A and 13B. The spring form1310is not shown in this view for clarity. In this embodiment, the contact pad715is made of aluminum and is coupled to a spring mount1340by a fastener1345made of aluminum. In one embodiment, the first shaft707and housing1320are unified into an integral part and is made of an aluminum or ceramic material. The bearings1315may be made of an aluminum or a ceramic material. The spring form910C may be made of a HASTELLOY® material and is received in an inner diameter of the tubular member712, which may be made of a ceramic or aluminum material. The inner tubular member1308is received between the inner diameter of the spring form910C and the outer diameter of the second shaft709. The inner tubular member1308may be made of a ceramic material and is adapted to reduce particle formation. For example, if the second shaft709and the inner tubular member1308are both made of a ceramic material, particle formation is reduced due to the interaction between the ceramic surfaces. Moreover, use of ceramic materials decreases galling as compared to aluminum components, which extends lifetime and reduces particle formation.

FIGS. 14A and 14Bare isometric views of another embodiment of a compressible contact member1400coupled to a substrate support104.FIG. 14Cis a side cross-sectional view of the contact member1400shown inFIGS. 14A and 14B. The contact member1400includes a spring form1410configured to provide flexibility for the contact member1400without the use of a compression spring as shown inFIGS. 7A and 13A. The spring form1410may comprise the same material as is described in reference to the spring form710A.

The contact member1400includes a bracket1415adapted to hang and/or fasten to a side1420and/or a bottom1425of the substrate support104. The contact member1400includes the second shaft709that is at least partially received by an opening1428formed in the bracket1415. The second shaft709and the configuration of the bracket1415prevents the spring form1410from fully extending or decompressing and also preloads the spring form1410. The contact member1400includes clamps1430A,1430B adapted to couple to the spring form1410. The contact member1400also includes one or more bushings1435that may be configured as a guide for the second shaft709. The bracket1415and the clamps1430A,1430B may be made of aluminum while the second shaft709and the bushings1435may be made from a ceramic material.

FIG. 14Dis a side cross-sectional view of the spring form1410of the contact member1400shown inFIGS. 14A and 14Bin a compressed position.FIGS. 14E and 14Fare isometric views of the contact member1400shown inFIGS. 14A and 14Billustrating the installment or removal of a spring form1410. In one embodiment, the spring form1410is depressed and the second shaft709is removed from the bracket1415. A fastener1440, such a s screw or pin may be adapted as a keeper and inserted into an upper portion of the second shaft709in order to hold the spring form1410onto the second shaft709.

FIG. 14Gis a side cross-sectional view of a contact member1400as described inFIGS. 14A and 14Bcoupled to a substrate support104in a raised position. The contact pad715is shown contacting an extended member458disposed on the inner surface of a sidewall117babove a transfer port412. As the substrate support is lowered, the contact member1400moves with the substrate support and the area interior of the transfer port412is clear for substrate transfer.

FIG. 15is a schematic cross sectional view of another embodiment of a plasma processing system1500. The processing system1500is substantially similar to the processing systems100and400described inFIGS. 1 and 4with the exception of a plurality of compressible contact members1505coupled to an interior sidewall1002of the chamber body102. The compressible contact members1505may be configured similarly to the compressible contact members415,900,1000,1200,1300or1400as described above. In this embodiment, each of the compressible contact members1505include a contact portion1556and an elastic portion1554, which are substantially similar to embodiments of the elastic portion454and contact portion456described above. The compressible contact members1505are coupled to extended members458disposed on the interior of the chamber body102. In embodiments where a shadow frame460may be used, the shadow frame460may rest on the extended members458. Holes or slots may be provided in the perimeter of the shadow frame460to allow clearance for any movable portions of the compressible contact members1505.

In this embodiment, the contact portion1556is adapted to contact a bracket1552disposed on the substrate support104when the substrate support104is in a raised position. In one aspect, the temperature of the chamber body102may be cooler than the temperature of the substrate support104. Thus, coupling of the compressible contact members1505to the chamber body102exposes the compressible contact members1505to a lower temperature as opposed to the temperatures the compressible contact member would experience when coupled to the substrate support104. The lower temperature of the compressible contact members1505may increase the lifetime of the compressible contact members1505.

The embodiments of the RF devices109aand109bdescribed herein provide a superior alternative to the conventional ground/return schemes by allowing RF return in varied positional levels of a substrate support104. Typically, conventional PECVD substrate supports are grounded solely by ground straps which connect to the chamber floor. This ground method utilizes straps that are very long, which may pose great resistance to the returning RF current, thereby allowing high electrical potentials to be generated between the sidewalls of a chamber and the substrate support. The higher electrical potentials may lead to arcing between the sidewalls of the chamber and the substrate support Further, ground straps adjacent the sidewall of the chamber having a transfer port may be in the way during substrate transfer processes. The existence of the transfer port412in one of the sidewalls of the chamber creates a greater asymmetry in the RF return path. Embodiments of the RF devices109aand compressible contact members as described herein allow the susceptor to be grounded to the chamber above the slit valve opening, which shortens the ground path and may be adapted to facilitate a similar or symmetrical ground path on all sides of the chamber. Embodiments of the RF devices109a,109band the compressible contact members as described herein also allow adjustability in the height of the substrate support while maintaining ground potential, which allows the substrate support to be grounded over a greater range of spacing distances for deposition, post- or pre-deposition, and cleaning processes.

Embodiments of the compressible contact members as described herein allow the substrate support to be grounded to the chamber wall above the slit valve opening. Embodiments of the compressible contact members as described herein creates individual ground contact units which mount to the substrate support and or chamber sidewall. In one embodiment, as the substrate support moves up, the compressible contact members engage on fixed grounded surfaces of the chamber above the slit valve opening. The compressible contact member units contain a compliant component which allows the substrate support to maintain a ground contact over a range of process spacing distances. When the substrate support is lowered, the grounding contact units disengage from the grounded contact pads. Embodiments of the compressible contact members as described herein allows the susceptor to be grounded to the chamber body above the slit valve opening eliminating the slit valve opening affecting the RF return path. Embodiments of the RF devices109aallows the RF devices109bto be much shorter. Also, since the ground contact units are each mounted to the substrate support independently and since they have a compliant component they do not rely on surfaces being flat to achieve good electrical contacts.