SEMICONDUCTOR MANUFACTURING PROCESS CHAMBER COOLING FLANGE FOR REMOTE PLASMA SOURCE SUPPLY

Cooling flanges and semiconductor manufacturing processing chamber comprising the cooling flanges are disclosed. The cooling flanges comprise a flange body with a gas channel extending through the length thereof. The gas channel has an inlet funnel, a middle channel and an outlet funnel with a purge gas inlet in a side of the flange body. The purge gas inlet connects to the middle channel of the gas channel.

TECHNICAL FIELD

Embodiments of the disclosure are directed to cooling flanges for semiconductor manufacturing equipment. In particular, embodiments of the disclosure are directed to cooling flanges without isolation valves for remote plasma source (RPS) connection.

BACKGROUND

Reliably producing submicron and smaller features is one of the key requirements of very large scale integration (VLSI) and ultra large scale integration (ULSI) of semiconductor devices. However, with the continued miniaturization of circuit technology, the dimensions of the size and pitch of circuit features, such as interconnects, have placed additional demands on processing capabilities. The various semiconductor components (e.g., interconnects, vias, capacitors, transistors) require precise placement of high aspect ratio features. Reliable formation of these components is critical to further increases in device and density.

Additionally, the electronic device industry and the semiconductor industry continue to strive for larger production yields while increasing the uniformity of layers deposited on substrates having increasingly larger surface areas. These same factors in combination with new materials also provide higher integration of circuits per unit area on the substrate.

Some semiconductor manufacturing processes use remote plasma sources (RPS) for generation of a plasma that is flowed into the process region of a processing chamber. To maintain sufficient temperature control of the process within the processing chamber, a cooling flange is often positioned between the RPS and the processing chamber. Current cooling flanges positioned between the remote plasma source (RPS) and the processing chamber include an isolation valve to allow for an inert gas (e.g., argon (Ar)) purge. These isolation valves impose resistance to the flow of plasma from the RPS to the processing chamber and are inadequate for purging effectiveness. Additionally, current cooling flanges are constrained to lower temperatures (less than about 70° C.). Furthermore, the current cooling flanges provide a 2-point contact with mating processing chamber parts leading chamber-to-chamber temperature variations.

Accordingly, there is a need in the art for improved cooling flanges to connect the RPS to a semiconductor manufacturing process chamber.

SUMMARY

In some aspects, the techniques described herein relate to a cooling flange to connect a remote plasma source (RPS) to a semiconductor manufacturing processing chamber, the cooling flange including: a flange body with an inlet face and an outlet face defining a length of the cooling flange, an inlet flange on an inlet end of the flange body, the inlet flange including the inlet face and having an inlet flange thickness, an outlet flange on an outlet end of the flange body, the outlet flange including the outlet face and having an outlet flange thickness; a gas channel extending through the length of the flange body, the gas channel having an inlet opening in the inlet face of the flange body and an outlet opening in the outlet face of the flange body; and a purge gas inlet opening in a side of the flange body along the length of the flange body between the inlet flange and the outlet flange, the purge gas inlet opening in fluid communication with the gas channel.

In some aspects, the techniques described herein relate to a cooling flange to connect a remote plasma source (RPS) to a semiconductor manufacturing processing chamber, the cooling flange including: a flange body with an inlet face and an outlet face defining a length of the cooling flange, an inlet flange on an inlet end of the flange body, the inlet flange including the inlet face and having an inlet flange thickness, an outlet flange on an outlet end of the flange body, the outlet flange including the outlet face and having an outlet flange thickness; a gas channel extending through the length of the flange body, the gas channel having an inlet opening in the inlet face of the flange body and an outlet opening in the outlet face of the flange body, the gas channel having an inlet funnel, a middle tube and an outlet funnel, the middle tube connecting the inlet funnel with the outlet funnel; and a purge gas inlet opening in a side of the flange body along the length of the flange body between the inlet flange and the outlet flange, the purge gas inlet opening in fluid communication with the middle tube of the gas channel.

In some aspects, the techniques described herein relate to a semiconductor manufacturing processing chamber including: a chamber lid including a gas inlet, the gas inlet having an inlet opening in a top face of the chamber lid; a remote plasma source (RPS) above the chamber lid; and a cooling flange connecting the remote plasma source (RPS) to the chamber lid, the cooling flange including: a flange body with an inlet face and an outlet face defining a length of the cooling flange, an inlet flange on an inlet end of the flange body, the inlet flange including the inlet face and having an inlet flange thickness, an outlet flange on an outlet end of the flange body, the outlet flange including the outlet face and having an outlet flange thickness, a gas channel extending through the length of the flange body, the gas channel having an inlet opening in the inlet face of the flange body and an outlet opening in the outlet face of the flange body, and a purge gas inlet opening in a side of the flange body along the length of the flange body between the inlet flange and the outlet flange, the purge gas inlet opening in fluid communication with the gas channel, wherein the gas channel of the cooling flange is in fluid communication with the remote plasma source (RPS) and the gas inlet of the chamber lid.

DETAILED DESCRIPTION

“Atomic layer deposition” or “cyclical deposition” as used herein refers to a process comprising the sequential exposure of two or more reactive compounds to deposit a layer of material on a substrate surface. As used in this specification and the appended claims, the terms “reactive compound”, “reactive gas”, “reactive species”, “precursor”, “process gas” and the like are used interchangeably to mean a substance with a species capable of reacting with the substrate surface or material on the substrate surface in a surface reaction (e.g., chemisorption, oxidation, reduction, cycloaddition). The substrate, or portion of the substrate, is exposed sequentially to the two or more reactive compounds which are introduced into a reaction zone of a processing chamber.

FIGS.1and2illustrate a conventional cooling flange100that uses a combination of pneumatic valves110to control flow of plasma through the gas channel120. The cooling flange100connects to the gas funnel130(or gas inlet) of the processing chamber. The gas funnel130of some embodiments is a component of the gas distribution system of the processing chamber and may include one or more additional components (e.g., a showerhead).

The cooling flange100connects to the gas funnel130through a flange140. O-ring grooves150are formed in one or more of the bottom of the cooling flange100, the top of the gas funnel130, top of the flange140or bottom of the flange140. The presence of the O-ring grooves150impacts the contact points between the cooling flange100and the gas funnel130. In the conventional cooling flange illustrated, there are two points; a first contact point151and a second contact point152. The first contact point151is between the gas channel120and the O-ring groove150on the bottom of the cooling flange100, between the cooling flange100and the gas funnel130. The second contact point152is at the outer edge of the cooling flange100outside the O-ring grooves150between cooling flange100and the flange140. The region between the first contact point151and the second contact point152may not be completely sealed or have full contact, affecting the temperature control, resulting in chamber-to-chamber variations in temperature uniformity.

The pneumatic valves110all for the addition of an inert gas flow to the gas channel120either during flow of a plasma through the cooling flange100, as a diluent gas, or without plasma flow, as a purge gas. The pneumatic valves110interrupt the flow path of the gas channel120, causing inefficient purging of the cooling flange100and increasing turbulence of the flow from the plasma supply. Additionally, the pneumatic valves110impose temperature constraints on the cooling flange. The pneumatic valves110have a maximum operating temperature of about 70° C.

One or more embodiments of the disclosure advantageously provide cooling flanges that provide improved purging efficiency. Some embodiments advantageously provide an efficient flow of plasma without flow restrictions. Some embodiments advantageously provide cooling flanges with improved temperature constraints.

In some embodiments, the removal of the pneumatic isolation valves from the cooling flange removes the temperature constraint of 70° C., allowing for higher temperature processes.

In some embodiments, a single point contact between the cooling flange and the processing chamber is provided. The single point contact eliminates temperature fluctuation issues. In some embodiments, the cooling flange is in direct contact with the mixer and/or the lid of the processing chamber.

Some embodiments of the disclosure help avoid or minimize precursor back streaming towards the remote plasma source. The length of the cooling flange is configured to avoid back streaming of precursors.

Some embodiments of the disclosure provide for improved cooling flange purging efficiency by connecting the purge gas line closer to the inlet funnel and/or by removing the isolation valves. Without the isolation valves, the flow path of the plasma through the cooling flange is not obstructed, minimizing flow restrictions. Elimination of the isolation valves simplifies construction and costs of the cooling flange. Some embodiments reduce leakage points by eliminating the isolation valves.

Some embodiments avoid back streaming of gases into the RPS without the use of valves. Some embodiments allow for improved contact between the cooling flange and the mixer or process chamber lid reducing temperature variations and improving chamber-to-chamber matching.

Some embodiments of the cooling flange are designed in such a way, that the length of cooling flange is configured to eliminate back streaming of gases. Sufficient length of the cooling flange prevents back flow of precursors from getting close to the RPS generator. In some embodiments, use of hydrogen (H2) as the purge gas shows negligible or no back diffusion of the precursor and with efficient purging from top completely restrict the diffusion of precursors.

When cooling is employed, a water channel can be used adjacent the RPS generator. The cooling channel can be moved to either or both ends of the flange. For purge gas, a direct gas line weldment can be connected to the cooling flange which reduces the flow path resistance.

FIG.3illustrates a orthographic projection of a cooling flange200in accordance with one or more embodiments of the disclosure.FIG.4is a cross-sectional schematic view of a cooling flange200connected to the gas inlet of a gas distribution assembly according to one or more embodiments of the disclosure.FIG.5is a cross-sectional schematic view of a cooling flange200according to one or more embodiments of the disclosure.

The cooling flanges200of some embodiments are configured to connect a remote plasma source (RPS)350to a processing chamber300.FIG.6illustrates a cross-sectional schematic view of a processing chamber300with remote plasma source350connected through a cooling flange200according to one or more embodiment of the disclosure.

Referring toFIGS.3through5, one or more embodiments if the disclosure are directed to cooling flanges200. The cooling flange200comprises a flange body210. The flange body210has an inlet face212and an outlet face214that define a length LCFof the cooling flange200.

In some embodiments, an inlet flange220is on an inlet end211of the flange body210. The inlet flange220of some embodiments includes the inlet face212of the flange body210. The inlet flange220has an inlet flange thickness TIF.

In some embodiments, an outlet flange225is on the outlet end213of the flange body210. The outlet flange225of some embodiments includes the outlet face214of the outlet face214. The outlet flange225has an outlet flange thickness TOF.

In some embodiments, the flange body210includes both an inlet flange220on the inlet end211and an outlet flange225on the outlet end213.

The flange body210can be made of any suitable material known to the skilled artisan. In some embodiments, the flange body210comprises stainless steel or aluminum.

In some embodiments, one or more of the inlet flange220or the outlet flange225comprises a cooling channel230formed in the inlet face212. The embodiments illustrated inFIGS.3and4include a cooling channel230in the inlet face212of the inlet flange220. The skilled artisan will recognize that the arrangement of components illustrated inFIGS.3and4are merely representative of some possible configurations of the cooling flange200and will understand that construction of a similar cooling flange with cooling channel230on the outlet face214of the outlet flange225.

The inlet end211of the illustrated embodiment includes the cooling channel230in the inlet face212. The cooling channel230of some embodiments includes a cooling tube235that extends through the cooling channel230from a first end231of the cooling channel230to a second end232of the cooling channel230. The embodiment illustrated inFIG.3shows a first cooling fitting233connected to the cooling tube235at the first end231and a second cooling fitting234connected to the cooling tube235at the second end232. The cooling channel230can be any suitable dimensions based on, for example, the thickness of the flange that the cooling channel230is formed in and/or the size of the cooling tube235to be used. The cooling tube235can be made of any suitable material known to the skilled artisan. In some embodiments, the cooling tube235comprises a material with good thermal conductive properties to ensure sufficient thermal transfer between the flange body210and the cooling tube235. Suitable cooling tubes materials include, but are not limited to, copper, stainless steel, aluminum, etc.

The inlet flange220illustrated includes a plurality of apertures236that can be used to connect the cooling flange200to a remote plasma source, as is described below. The outlet flange225illustrated includes a plurality of apertures238that can be used to connect the cooling flange200to a gas distribution assembly of a processing chamber, as is described below. The skilled artisan will recognize the manner in which the plurality of apertures236in the inlet flange220and the plurality of apertures238in the outlet flange225can be used to form the respective connections. For example, a suitable fastener (e.g., bolts) can be used with the plurality of apertures236in the inlet flange220or plurality of apertures238in the outlet flange225to connect the cooling flange200to the adjacent components.

The inlet end211of some embodiments, as shown inFIGS.3and4, includes one or more O-ring groove237. The O-ring groove237can be sized for any suitable O-ring known to the skilled artisan and can be used to help provide a fluid-tight seal between the inside of the O-ring and the outside of the O-ring. In some embodiments, the outlet end213of includes one or more O-ring groove239. In the embodiment illustrated inFIG.4, there are two O-ring grooves239. In some embodiments, one of the O-ring grooves239in the outlet end213of the flange body210(i.e., in the outlet face214of the outlet flange225) is a cooling channel similar to cooling channel230illustrated in the inlet flange220.

A gas channel240extends through the length LCFof the flange body210. The gas channel240has an inlet opening242in the inlet face212and an outlet opening244in the outlet face214of the flange body210.

The length LCFof the flange body210is configured to avoid back streaming of precursor gases from the outlet opening244reaching the inlet opening242. In some embodiments, the length of the cooling flange is greater than 2 inches, 3 inches, 4 inches or 5 inches. In some embodiments, the length of the cooling flange is less than 15 inches, 14 inches, 13 inches, 12 inches, 11 inches, or 10 inches. In some embodiments, the cooling flange has a length in the range of 2 inches to 15 inches, or in the range of 3 inches to 14 inches, or in the range of 4 inches to 12 inches, or in the range of 5 inches to 10 inches. In some embodiments, the length LCF of the flange body210of the cooling flange200is greater than or equal to 2 inches and less than or equal to 15 inches, or greater than or equal to 4 inches and less than or equal to 12 inches.

The gas channel240of some embodiments, as shown inFIGS.4and5, comprises an inlet funnel250, a middle tube260and an outlet funnel270. The middle tube260connects the inlet funnel250with the outlet funnel270. The length LGCIof the inlet funnel250is measured from the inlet opening242in the inlet face212to a transition255with the middle tube260. The length LGCOof the outlet funnel270is measured from the outlet opening244in the outlet face214to a transition265with the middle tube260. The length LGCMof the middle tube260is measured from the transition255with the inlet funnel250to the transition265with the outlet funnel270.

The inlet funnel250is shaped with a largest diameter at the inlet opening242and the smallest diameter at the transition255with the middle tube260. The inlet angle ΘIis measured relative to the central axis245of the gas channel240. The inlet angle ΘIof the inlet funnel250, according to some embodiments, is in the range of 15° to 55°, measured relative to the central axis245of the gas channel240. In some embodiments, the angle ΘIis in the range of 20° to 45°, or about 30°.

The inlet diameter DIFis measured as the widest part of the inlet funnel250located at the inlet opening242. The inlet diameter DIFis also referred to as the maximum diameter at the inlet face212of the flange body210. In some embodiments, the inlet diameter DIFis in the range of 1 inch to 3 inches, or in the range of 1.5 inches to 2.5 inches, or about 2 inches.

The outlet funnel270is shaped with the largest diameter at the outlet opening244and the smallest diameter at the transition265with the middle tube260. The outlet angle ΘOis measured relative to the central axis245of the gas channel240. In some embodiments, the outlet angle ΘOof the outlet funnel270, according to some embodiments, is in the range of 30° to 70°, measured relative to the central axis245of the gas channel240. In some embodiments, the angle ΘOis in the range of 40° to 60°, or in the range of 50° to 55°.

The outlet diameter DOFis measured as the widest part of the outlet funnel270located at the outlet opening244. The outlet diameter DOFis also referred to as the maximum diameter at the outlet face214of the flange body210. In some embodiments, the maximum diameter at the outlet face214(the outlet diameter DOF) is in the range of 0.5 inches to 2 inches, or in the range of 1 inch to 1.5 inches or about 1.25 inches.

The middle tube260connecting the inlet funnel250with the outlet funnel270of some embodiments has a substantially uniform diameter DMTalong the length LGCMof the middle tube260. As used in this manner, a “substantially uniform diameter” varies at any point along the length LGCMby less than or equal to 10% relative to the average diameter. In some embodiments, the diameter DMThas a diameter in the range of 0.2 inches to 0.5 inches, or in the range of 0.3 inches to 0.4 inches.

Referring again toFIGS.3through5, some embodiments of the disclosure include a purge gas inlet opening280in a side215of the flange body210. The purge gas inlet opening280is positioned along the length LCFof the flange body210between the inlet flange220and the outlet flange225. The purge gas inlet opening280is in fluid communication with the gas channel240through purge gas channel282.

The purge gas channel282can be connected to the gas channel240at any point along the length LCFof the flange body210. In some embodiments, the purge gas inlet opening280is in fluid communication through the purge gas channel282with the middle tube260of the gas channel240.

The location of the junction between the purge gas channel282and the middle tube260may affect the backflow of precursors from the outlet face214of the flange body210flowing backward to the inlet face212and into the remote plasma source connected to the inlet face212. In some embodiments, the purge gas inlet opening280connects to the middle tube260of the gas channel240at a distance DPJwithin 1 inch of the inlet funnel250. The distance DPJis measured from the transition255between the inlet funnel250and the middle tube260to the edge284of the purge gas channel282closest to the transition255. In some embodiments, the distance DPJis less than or equal to 2.5 inches, 2 inches, 1.5 inches, 1 inch, 0.75 inches, 0.5 inches or 0.25 inches.

The diameter of the purge gas inlet channel282is configured to provide a sufficient flow of purge gas into the gas channel240to prevent backflow of precursor through the flange body210. In some embodiments, the purge gas inlet channel282has a diameter DPCin the range of 0.25 inches to 1.5 inches, or in the range of 0.5 inches to 1.25 inches, or in the range of 0.75 inches to 1 inch. In some embodiments, the diameter DPCof the purge gas inlet channel282is greater than or equal to the diameter DMTof the middle tube260.

In some embodiments, the purge gas inlet opening280is in a flat face286in the cylindrical wall (side215) of the flange body210. The flat face286formed in the side215provides a location for the attachment of a gas inlet valve (not shown) to the flange body210of the cooling flange200.

FIG.6illustrates a schematic representation of a semiconductor manufacturing processing chamber300in accordance with one or more embodiments of the disclosure. The processing chamber300includes a chamber body302with a sidewall304, bottom306and chamber lid308that enclose an interior309of the chamber. The chamber body302can be made of any suitable material known to the skilled artisan. For example, the chamber body302in some embodiments is made of stainless steel. The various components of the embodiments illustrated in the Figures have different cross-hatching for visualization purposes. The different cross-hatching is only to make it easier to distinguish between parts and is not related to the materials of construction.

The chamber lid308of some embodiments includes a gas distribution assembly or gas injector, as will be understood by the skilled artisan. The chamber lid308of some embodiments comprises a gas inlet315. The gas inlet315includes an inlet opening316in the chamber lid308.

In the illustrated embodiment the inlet opening316includes a gas distribution assembly configured to provide a flow of one or more gases into the interior309of the semiconductor manufacturing processing chamber300. In some embodiments, the gas distribution assembly includes a showerhead320located within the interior309semiconductor manufacturing processing chamber300. In the illustrated embodiment, the showerhead320is connected to the chamber lid308and is coplanar with the chamber lid308. However, the skilled artisan will recognize that this arrangement is merely an example of one possible configuration and that the showerhead320can be within the interior309of the semiconductor manufacturing processing chamber300or part of the chamber lid308that bound the interior309. The showerhead320is part of the gas distribution assembly and may be referred to as a gas distribution plate.

The showerhead320has a front surface322and a back surface324that define the thickness of the showerhead320. A plurality of apertures326extend through the thickness of the showerhead320. The plurality of apertures326allow a gas to flow from the region adjacent the back surface324to the interior309of the semiconductor manufacturing processing chamber300through the showerhead320.

The showerhead320can be made of any suitable material known to the skilled artisan. In some embodiments, the showerhead320is made of a conductive material that can be used to generate a plasma within the interior309of the semiconductor manufacturing processing chamber300. In some embodiments, the showerhead320comprises one or more of stainless steel or aluminum.

A gas funnel330is positioned on the showerhead320. The gas funnel330has a front surface332and a back surface334. An opening336extends through the center of the gas funnel330. The front surface332of some embodiments has a concave-shaped inner portion and a flat outer portion. The flat outer portion of the front surface332of the gas funnel330is in contact with the back surface324of the showerhead320to form a gas plenum between the back surface324of the showerhead320and the concave-shaped inner portion of the front surface332of the gas funnel330.

A substrate support340is located within the interior309of the semiconductor manufacturing processing chamber300. The substrate support340of some embodiments comprises a support body341positioned on a support shaft342. The support body341has a support surface343configured to support a semiconductor wafer345for processing. The support shaft342of some embodiments is configured to move the support body341closer to/further from the showerhead320and/or around a rotational axis of the support shaft342.

In some embodiments, the support body341includes a thermal element344configured to heat the semiconductor wafer345on the support surface343. The thermal element344can be any suitable heating mechanism known to the skilled artisan. For example, in some embodiments, the thermal element344comprises a resistive heating element that is connected to a power supply (not shown) configured to apply power to the thermal element344to heat the support body341. In some embodiments, the support body341includes an electrostatic chuck (ESC) (not shown). The skilled artisan will be familiar with the construction of the ESC and the manner in which the ESC is powered and employed.

The semiconductor manufacturing processing chamber300of some embodiments, as shown inFIG.6, includes a remote plasma source (RPS)350positioned above the chamber lid308. As used in this manner, the direction term “above” is used to describe the location of the remote plasma source350relative to the chamber lid308on the page of the Figure. The skilled artisan will recognize that the arrangement of components in the processing chamber can be varied so that the entire chamber is inverted or turned sideways without deviating from the scope of the disclosure. The remote plasma source350can be any suitable plasma source known to the skilled artisan.

The cooling flange200connects the remote plasma source (RPS)350to the chamber lid308. The cooling flange200illustrated has an inlet flange220and outlet flange225. The inlet flange220is connected to the remote plasma source350and the outlet flange225is connected to the gas funnel330of the gas distribution assembly. In use, a plasma generated in the remote plasma source350flows through the gas channel240of the cooling flange200into the opening336in the back surface334of the gas funnel330, into the plenum325between the front surface332of the gas funnel330and the back surface324of the showerhead320, and then through the plurality of apertures326in the showerhead320into the process region305between the substrate support340and the showerhead320.

In some embodiments, a purge gas flow is provided through the purge gas inlet opening280into the purge gas channel282, and then into the gas channel240. The purge gas flows through the gas channel240of the cooling flange200into the gas funnel330of the semiconductor manufacturing processing chamber300. The purge gas flow can be provided in a constant flow, in pulses or varied. In some embodiments, the purge gas flow is provided through the cooling flange200into the gas funnel330when the remote plasma source350is not powered so that a flow of inert gas flows into the interior309of the semiconductor manufacturing processing chamber300through the showerhead320even without a plasma flow. In some embodiments, the remote plasma source350is used as a passthrough for a process gas that is not ignited into a plasma. The non-plasma process gas flows into the cooling flange200and is joined with the purge gas flow in the gas channel240to flow into the gas funnel330.

In the embodiment illustrated inFIG.6, the cooling flange200is connected directly to the back surface334of the gas funnel330by any suitable connector known to the skilled artisan. In some embodiments, the cooling flange200is connected to the gas funnel330using a plurality of bolts extending through the plurality of apertures238of the outlet flange225of the flange body210(seeFIG.3). In some embodiments, an O-ring positioned in the one or more O-ring groove239in the outlet face214of the outlet end213of the outlet flange225(seeFIG.4) helps to form a fluid-tight seal between the gas channel240and the outside environment. The cooling flange200is connected to the gas funnel330by a single point contact between the outlet flange225and the gas funnel330. The inventors have found that manufacturing cooling flanges with multiple contact surfaces is impractical due at least in part to the tolerance requirements to ensure proper contact at more than one surface.

A cooling tube235is illustrated inFIG.6as being connected to the inlet flange220of the flange body210. A flow of a cooling fluid is passed through the cooling tube235so that the cooling fluid flow around the inlet flange220between the remote plasma source350and the remainder of the flange body210below the inlet flange220. In some embodiments, the cooling fluid is connected to a recirculation system (not shown) to reuse the cooling fluid repeatedly while maintaining a consistent temperature for the cooling fluid and without contamination concerns. The cooling fluid can be any suitable fluid known to the skilled artisan for cooling purposes. For example, a liquid with a relatively high heat capacity compared to water (e.g., ethylene glycol or an aqueous solution of ethylene glycol) may be advantageously used to efficiently remove heat buildup in the inlet flange220from the remote plasma source350.

Referring back toFIG.4, in some embodiments, the cooling flange200is connected to the gas funnel330through a mixer360. The mixer360is a component positioned adjacent the back surface334of the gas funnel330with a leg364that extends from a mixer flange361into the inlet opening336of the gas funnel330. A plurality of apertures362in the mixer flange361allow a flow of gas to pass from the cooling flange200into the gas funnel330. The leg364in the illustrated embodiment has a plurality of baffles366positioned at an end of the mixer360inside the inlet opening336. The plurality of baffles366cause turbulence in the flow of gas through the inlet opening336to mix the gaseous components of the flow more thoroughly. In the embodiment illustrated inFIG.4, the cooling flange200is connected to the gas funnel330through the mixer flange361of the mixer360with a single point contact, the outlet face214of the outlet end213of the flange body210. In some embodiments, the baffles366are positioned 180° apart to increase mixing and turbulence within the gas flow.