Patent Publication Number: US-11643725-B2

Title: Hardware to prevent bottom purge incursion in application volume and process gas diffusion below heater

Description:
TECHNICAL FIELD 
     The present technology relates to components and apparatuses for semiconductor manufacturing. More specifically, the present technology relates to processing chamber distribution components and other semiconductor processing equipment. 
     BACKGROUND OF THE INVENTION 
     During substrate processing operations, such as chemical vapor deposition (CVD) operations, processing gases may diffuse below a top surface of a substrate support. The diffused processing gases result in deposition of material onto outer surfaces of the substrate support and/or other components or surfaces of the substrate processing chamber that are not the substrate. The deposition can delay substrate processing operations, cause production downtime for substrate processing chambers, result in increased cleaning time, reduce throughput, cause non-uniform deposition on the substrate, and/or cause substrate defects. 
     Thus, there is a need for improved systems and methods that can be used to reduce diffusion of processing gases below the top surface of the substrate support. These and other needs are addressed by the present technology. 
     BRIEF SUMMARY OF THE INVENTION 
     Exemplary semiconductor processing chambers may include a substrate support that may include a top surface. A peripheral edge region of the top surface may be recessed relative to a medial region of the top surface. The semiconductor processing chambers may include a pumping liner disposed about an exterior surface of the substrate support. The semiconductor processing chambers may include a liner disposed between the substrate support and the pumping liner. The liner may be spaced apart from the exterior surface of the substrate support to define a purge lumen between the liner and the substrate support. The semiconductor processing chambers may include an edge ring seated on the peripheral edge region of the substrate support. The edge ring may extend beyond a peripheral edge of the substrate support and above at least a portion of the liner. A gap may be formed between a bottom surface of the edge ring and a top surface of the liner. The gap and the purge lumen may be fluidly coupled with one another. 
     In some embodiments, one or both of an inner edge and an outer edge of the top surface of the liner may be rounded. A top surface of the edge ring and the medial region of the top surface of the substrate support may be at a substantially same height when the substrate support is in a process position. The gap may separate the bottom surface of the edge ring and the top surface of the liner by a vertical distance of between about 80 mils and 300 mils. A distal edge of the edge ring may extend radially outward beyond at least half of a thickness of the liner. An inner surface of the liner may include a protrusion that extends inward toward the exterior surface of the substrate support. A lateral distance between the exterior surface of the substrate support and the protrusion may be between about 60 mils and 100 mils. The liner may include a ceramic material. 
     Some embodiments of the present technology may also encompass semiconductor processing chambers. The semiconductor processing chambers may include a showerhead that at least partially defines a top of the chamber. The showerhead may define a plurality of apertures that extend through a thickness of the showerhead. The semiconductor processing chambers may include a substrate support disposed beneath the showerhead. The substrate support may include a top surface. A peripheral edge region of the top surface may be recessed relative to a medial region of the top surface. The substrate may be vertically translatable within the chamber between a process position and a transfer position. The semiconductor processing chambers may include a liner disposed laterally outward of and spaced apart from an exterior surface of the substrate support to define a purge lumen between the liner and the substrate support. The semiconductor processing chambers may include an edge ring seated on the peripheral edge region of the substrate support when the substrate support is in the process position, the edge ring extending beyond a peripheral edge of the substrate support and above at least a portion of the liner. A gap may be formed between a bottom surface of the edge ring and a top surface of the liner. The gap and the purge lumen may be fluidly coupled with one another. 
     In some embodiments, the edge ring may be seated on the top surface of the liner when the substrate support is in the transfer position. A top surface of the edge ring and the medial region of the top surface of the substrate support may be at a substantially same height when the substrate support is in the process position. The gap may separate the bottom surface of the edge ring and the top surface of the liner by a vertical distance of between about 80 mils and 300 mils. The semiconductor processing chambers may include a pumping liner radially outward of the liner. One or both of an inner edge and an outer edge of the top surface of the liner may be chamfered. The semiconductor processing chambers may include a purge gas source coupled with a bottom of the purge lumen. 
     Some embodiments of the present technology may also encompass methods of processing a semiconductor substrate. The methods may include flowing a precursor into a semiconductor processing chamber via a showerhead that is disposed above a substrate support on which the semiconductor substrate is positioned. The methods may include simultaneously flowing a purge gas through a purge lumen defined by an exterior surface of the substrate support and a liner that is spaced apart from the substrate support. The methods may include diverting the purge gas laterally outward using an edge ring that is positioned atop a peripheral edge of the substrate support and that extends laterally outward of a top end of the purge channel such that the purge gas and the precursor diffuse with one another at a diffusion position that is radially outward of a bevel of the semiconductor substrate. 
     In some embodiments, the methods may include choking the flow of the purge gas within one or both of the purge lumen and a gap formed between a bottom surface of the edge ring and a top surface of the liner. A gap formed between a bottom surface of the edge ring and a top surface of the liner may separate the bottom surface of the edge ring and the top surface of the liner by a vertical distance of between about 80 mils and 300 mils. The methods may include venting the precursor and the purge gas out of the semiconductor chamber via a pumping liner that is disposed proximate the diffusion position. 
     Such technology may provide numerous benefits over conventional systems and techniques. For example, the processing systems may provide multi-substrate processing capabilities that may be scaled well beyond conventional designs. Additionally, each chamber system may include an edge ring that ensures that process gases and purge gases diffuse with one another at positions that are remote from the substrate and the substrate support. These and other embodiments, along with many of their advantages and features, are described in more detail in conjunction with the below description and attached figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A further understanding of the nature and advantages of the disclosed technology may be realized by reference to the remaining portions of the specification and the drawings. 
         FIG.  1    shows a schematic cross-sectional view of a substrate processing chamber according to some embodiments of the present technology. 
         FIG.  2 A  shows a schematic cross-sectional view of a substrate processing chamber with a substrate support in a transfer position according to some embodiments of the present technology. 
         FIG.  2 B  shows a schematic cross-sectional view of the substrate processing chamber of  FIG.  2 A  with the substrate support in a process position according to some embodiments of the present technology. 
         FIG.  2 C  shows an enlarged schematic partial cross-sectional view of the substrate processing chamber of  FIG.  2 A  according to some embodiments of the present technology. 
         FIG.  2 D  shows an enlarged schematic partial cross-sectional view of the substrate processing chamber of  FIG.  2 A  according to some embodiments of the present technology. 
         FIG.  2 E  shows an enlarged schematic partial cross-sectional view of the substrate processing chamber of  FIG.  2 A  according to some embodiments of the present technology. 
         FIG.  3    shows operations of an exemplary method of processing a semiconductor substrate according to some embodiments of the present technology. 
     
    
    
     Several of the figures are included as schematics. It is to be understood that the figures are for illustrative purposes, and are not to be considered of scale or proportion unless specifically stated to be of scale or proportion. Additionally, as schematics, the figures are provided to aid comprehension and may not include all aspects or information compared to realistic representations, and may include exaggerated material for illustrative purposes. 
     In the appended figures, similar components and/or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label by a letter that distinguishes among the similar components. If only the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the letter. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Substrate processing operations may include delivering process gases to a substrate support to deposit film on a wafer or other substrate. The diffusion of process gases within a processing chamber may result in deposition of material not only on the wafer, but also on surfaces of the substrate support. For example, residue may be deposited on lateral exterior surfaces of the substrate support, which may be difficult to clean. This residue may delay substrate processing operations, cause production downtime for substrate processing chambers, result in increased cleaning time, reduce throughput, cause non-uniform deposition on the substrate, and/or cause substrate defects. 
     Conventional systems may attempt to prevent the formation of residue on the substrate support and/or other chamber components through the use of a bottom purge gas flow, which may obstruct the flow of process gases at areas near the chamber components. However, it is very difficult to perfectly balance the flow rates of the process gases and purge gases to provide the diffusion or mixing position of the purge and process gases at the interface of the edge of the wafer and the substrate support. This results in processing issues. For example, if purge gas reaches a bevel and/or other edge portion of the wafer there may be film uniformity issues across the surface of the wafer. If the process gases reach the lateral exterior surfaces of the substrate support there will be residue formation on the substrate. 
     The present technology overcomes these challenges by utilizing edge rings that divert flow of both the process gas and the purge gas outward away from both the wafer and the substrate support. This moves the diffusion position away from the wafer and the substrate support and ensures that the wafer is isolated from purge gas and the lateral exterior surface of the substrate support is isolated from process gases. 
     Although the remaining disclosure will routinely identify specific deposition processes utilizing the disclosed technology, it will be readily understood that the systems and methods are equally applicable to other deposition and cleaning chambers, as well as processes as may occur in the described chambers. Accordingly, the technology should not be considered to be so limited as for use with these specific deposition processes or chambers alone. The disclosure will discuss one possible system and chamber that may include pedestals according to embodiments of the present technology before additional variations and adjustments to this system according to embodiments of the present technology are described. 
       FIG.  1 A  shows a schematic cross-sectional view of an exemplary substrate processing chamber  100 , according to one implementation. The substrate processing chamber  100  may be, for example, a chemical vapor deposition (CVD) chamber or a plasma enhanced CVD chamber. The present disclosure contemplates that other chambers may be used, such as an atomic layer deposition (ALD) chamber or a physical vapor deposition (PVD) chamber. The substrate processing chamber  100  may have a chamber body  102  and a chamber lid  104  disposed on the chamber body  102 . The chamber body  102  may define an internal volume  106  between one or more sidewalls and a base of the chamber body  102  and the chamber lid  104 . The chamber body  102  may be made of a single body, or two or more bodies. 
     The substrate processing chamber  100  may include a gas distribution assembly  116  coupled to or disposed in the chamber lid  104  to deliver a flow of one or more process gases  109  into a processing region  110  through a showerhead  101 . The one or more process gases may include one or more of Ar and/or C3H6, among other gases. In one example, the one or more process gases may include one or more reactive gases. The showerhead  101  may include a backing plate  126  and a faceplate  130 . The gas distribution assembly  116  may include a gas manifold  118  coupled to a gas inlet passage  120  formed in the chamber lid  104 . The gas manifold  118  may receive a flow of one or more processing gases from one or more gas sources  122 . While two gas sources  122  are shown, any number of gas sources may be provided in various embodiments. The flow of processing gases received from the one or more gas sources  122  may distribute across a gas box  124 , flow through a plurality of openings  191  of the backing plate  126 , and further distribute across a plenum  128  defined by the backing plate  126  and the faceplate  130 . The flow of processing gases  109  may then flow into a processing region  110  of the internal volume  106  through one or more gas openings  132  formed in a lower surface  119  of the faceplate  130  of the showerhead  101 . 
     A substrate support  138  may be disposed within internal volume  106  defined by the chamber body  102 . The substrate supports  138  may be pedestals as illustrated, although a number of other configurations may also be used. The substrate support  138  may support a substrate  136  within the substrate processing chamber  100 . The substrate support  138  may support the substrate  136  on a support surface  139  of the substrate support  138 . The substrate support  138  may include a heater and/or an electrode disposed therein. The electrode may receive direct current (DC) voltage, radio frequency (RF) energy, and/or alternating current (AC) energy to facilitate processing. The lower surface  119  of the faceplate  130  of the showerhead  101  may face the support surface  139  of the substrate support  138 . The support surface  139  may face the lower surface  119  of the faceplate  130  of the showerhead  101 . The substrate support  138  may be made of a single body, or two or more bodies. 
     The substrate support  138  may be movably disposed in the internal volume  106  by a lift system  195 . Movement of the substrate support  138  may facilitate transfer of the substrate  136  to and from the internal volume  106  through a slit valve formed through the chamber body  102 . The substrate support  138  may also be moved to different processing positions for processing of the substrate  136 . 
     During substrate processing, as process gases (such as the process gases  109 ) flow into the processing region  110 , a heater may heat the substrate support  138  and the support surface  139 . Also during substrate processing, the electrode in the substrate support  138  may propagate radio frequency (RF) energy, alternating current (AC), or direct current (DC) voltage to facilitate plasma generation in the processing region  110  and/or to facilitate chucking of the substrate  136  to the substrate support  138 . The heat, gases, and energy from the electrode in the substrate support  138  may facilitate deposition of a film onto the substrate  136  during substrate processing. The faceplate  130 , which may be grounded via coupling to the chamber body  102 , and the electrode of the substrate support  138 , may facilitate formation of a capacitive plasma coupling. When power is supplied to the electrode in the substrate support  138 , an electric field may be generated between the faceplate  130  and substrate support  138  such that atoms of gases present in the processing region  110  between the substrate support  138  and the faceplate  130  are ionized and release electrons. The ionized atoms accelerate to the substrate support  138  to facilitate film formation on the substrate  136 . 
     A pumping device  103  may be disposed in the substrate processing chamber  100 . The pumping device  103  may facilitate removal of gases from the internal volume  106  and processing region  110 . The gases exhausted by the pumping device  103  may include one or more of a process gas and a process residue. The process residue may result from the process of depositing a film onto the substrate  136 . 
     The pumping device  103  may include a pumping liner  160  disposed on the chamber body  102 . For example, the pumping liner  160  may be seated on a stepped surface  193  of the chamber body  102  and a liner  159  may be disposed between the substrate support  138  and the pumping liner  160 . The stepped surface  193  may be stepped upwards from a bottom surface  154  of the chamber body  102 . The pumping liner  160  may be made of a single body, or two or more bodies. The pumping liner  160  may be made from material including one or more of aluminum, aluminum oxide, and/or aluminum nitride. The liner  159  may be made from an electrically isolating material, such as a ceramic material. In one example, the liner  159  may be made of one or more of quartz, a ceramic material including aluminum such as aluminum oxide and/or aluminum nitride, or any other suitable material. The pumping liner  160  may be disposed around the substrate support  138  and may encircle the substrate support  138 . A portion of a purge gas flow path  111  may be defined by an inner surface of the liner  159  and a lateral exterior surface of the substrate support  138 . The substrate processing chamber  100  may include a purge gas inlet  113  disposed at a bottom of the chamber body  102 . The purge gas inlet  113  may be an opening formed in a bottom surface of the chamber body  102 . The purge gas inlet  113  may be fluidly coupled with a purge gas source  114  that supplies one or more purge gases  179  to the purge gas inlet  113 . A bowl  112  may be disposed in the internal volume  106 . The bowl  112  may define a purge gas volume  115 . One or more bellows  117  may be disposed in the purge gas volume  115 . One or more purge gas baffles  161  may be disposed in the purge gas volume  115 . One or more bellows  121  may be disposed above a horizontal portion  112   b  of the bowl  112  and below a bottom surface  198  of the substrate support  138 . The one or more bellows  121  may separate a dead volume  163  from a portion of the purge gas flow path  111  that is between the one or more bellows  121  and a vertical portion  112   a  of the bowl  112 . 
     During substrate processing operations, and while processing gases  109  flow into the processing region  110  from the showerhead  101 , the purge gas inlet  113  may flow the one or more purge gases  179  into the purge gas volume  115 . The horizontal portion  112   b  of the bowl  112  may include one or more purge gas openings  197  that flow the purge gases  179  from the purge gas volume  115  and into the purge gas flow path  111 . The one or more purge gas openings  197  may be disposed radially outwardly of the one or more bellows  121 . While the processing gases  109  flow toward the substrate  136  to deposit films on the substrate  136 , the purge gases  179  may flow upwards in the purge gas flow path  111  to prevent the processing gases  109  from diffusing downwards into the purge gas flow path  111 . The processing gases  109  and the purge gases  179  may meet and/or mix at a diffusion position that is proximate the support surface  139 . The processing gases  109  and the purge gases  179  may mix to form a gas mixture  148  that is exhausted by the pumping device  103 . The pumping device  103  may include the pumping liner  160  and the liner  159 . 
     The one or more purge gases  179  may include one or more inert gases, such as one or more of Ar and/or N2. The one or more process gases  109  may flow into the processing region  110  from the showerhead  101  at a first flow rate. In one example, the first flow rate may be a volumetric flow rate having units of standard cubic centimeters per minute (SCCM). The one or more purge gases  179  may flow into the purge gas volume  115  from the purge gas inlet  113  at a second flow rate. In one example, the second flow rate may be a volumetric flow rate having units of SCCM. The second flow rate may be a ratio R 1  relative to the first flow rate. For example, the ratio R 1  may be within a range of 0.25 to 0.75 of the first flow rate, within a range of 0.25 to 0.50 of the first flow rate, or within a range of 0.48 to 0.52. In one embodiment, which can be combined with other embodiments, the ratio R 1  may be about 0.25, 0.30, 0.40, or 0.5 of the first flow rate. The ranges and examples of the ratio R 1  of the second flow rate relative to the first flow rate may incur benefits such as preventing at least a portion of processing gases from diffusing into the purge gas flow path  111  below the support surface  139  during substrate processing operations. Reducing or preventing such diffusion reduces or eliminates the likelihood that processing gases  109  will deposit materials onto surfaces other than the substrate  136 . Reducing deposition on surfaces other than the substrate  136  reduces or eliminates delays, throughput reductions, operational costs, cleaning time, and/or substrate defects. 
     The substrate processing chamber  100  may be part of a substrate processing system  180  that includes a controller  181  coupled to the substrate processing chamber  100 . The controller  181  may be part of a non-transitory computer readable medium. 
     The controller  181  may control aspects of the substrate processing chamber  100  during substrate processing. The controller  181  include a central processing unit (CPU)  182 , a memory  183 , and a support circuit  184  for the CPU  182 . The controller  181  may facilitate control of the components of the substrate processing chamber  100 . The controller  181  may be a computer that can be used in an industrial setting for controlling various chamber components and sub-processors. The memory  183  may store instructions, such as software (source code or object code), that may be executed or invoked to control the overall operations of the substrate processing chamber  100  in manners described herein. The controller  181  may manipulate respective operations of controllable components in the substrate processing chamber  100 . For example, the controller  181  may control the operations of the gas sources  122  to introduce processing gases, the purge gas source  114  to introduce purge gases, and/or a vacuum pump  133  (described below) to exhaust gases to eliminate or reduce contaminant particles (such as residue) in the substrate processing chamber. As an example, the controller  181  may control the lift system  195  to raise and lower the substrate support  138 , and the heater and the electrode of the substrate support  138  to supply heat and energy to facilitate processing. 
     The pumping liner  160  may be fluidly coupled to a foreline  172  through a first conduit  176  and a second conduit  178 . The foreline  172  may include a first vertical conduit  131 , a second vertical conduit  134 , a horizontal conduit  135 , and an exit conduit  143 . The exit conduit  143 , in one example, is a third vertical conduit. In one example, the first conduit  176  and the second conduit  178  may be openings formed in the chamber body  102 . The first conduit  176  and/or the second conduit  178  may be tubes or other flow devices that extend between a surface of the chamber body  102 , such as bottom surface  154 , and the pumping liner  160 . As an example, the first conduit  176  and/or the second conduit  178  may be part of the first vertical conduit  131  and the second vertical conduit  134 , respectively. In such an example, the first vertical conduit  131  and the second vertical conduit  134  may extend through the chamber body  102  and be coupled to the pumping liner  160 . In one embodiment, which can be combined with other embodiments, the first conduit  176  and the second conduit  178  each may be an opening formed in one or more sidewalls of the chamber body  102 . 
     The first conduit  176  may be fluidly coupled to the pumping liner  160  and the first vertical conduit  131  of the foreline  172 . The second conduit  178  may be fluidly coupled to the pumping liner  160  and the second vertical conduit  134  of the foreline  172 . The first vertical conduit  131  and the second vertical conduit  134  may be fluidly coupled to the horizontal conduit  135 . The horizontal conduit  135  may include a first portion  137  coupled to the first vertical conduit  131 , a second portion  140  coupled to the second vertical conduit  134 , and a third portion  141  coupled to the exit conduit  143 . The horizontal conduit  135  may include a first end  149  adjacent to the first vertical conduit  131  and a second end  151  adjacent to the second vertical conduit  134 . The horizontal conduit  135  may be made up of a single body or can be fabricated from one or more components. 
     The first conduit  176 , second conduit  178 , first vertical conduit  131 , second vertical conduit  134 , and horizontal conduit  135  may be configured to direct gases therethrough. The first conduit  176 , second conduit  178 , first vertical conduit  131  and/or second vertical conduit  134  need not be completely vertical and may be angled or may include one or more bends and/or angles. The present horizontal conduit  135  need not be completely horizontal and may be angled or may include one or more bends and/or angles. 
     The exit conduit  143  may be fluidly coupled to a vacuum pump  133  to control the pressure within the processing region  110  and to exhaust gases and residue from the processing region  110 . The vacuum pump  133  may exhaust gases from the processing region  110  through the pumping liner  160 , the first conduit  176 , the second conduit  178 , the first vertical conduit  131 , the second vertical conduit  134 , the horizontal conduit  135 , and the exit conduit  143  of the foreline  172 . 
     The pumping liner  160  may be fluidly coupled to the exit conduit  143  through the second conduit  178 , second vertical conduit  134  and the horizontal conduit  135 . The gas mixture  148  may flow from the annulus  105 , through the exhaust port  145 , and into the second conduit  178 . A second exhaust port of the pumping liner  160  may be disposed between the annulus  105  and the first conduit  176 . The second exhaust port may be fluidly coupled to the exit conduit  143  through the first conduit  176 , first vertical conduit  131  and the horizontal conduit  135 . In addition to flowing through the exhaust port  145 , the gas mixture  148  may flow through the second exhaust port and into the first conduit  176 . 
     The first vertical conduit  131  may flow the gas mixture  148  from the first conduit  176  and into the first portion  137  of the horizontal conduit  135 . The second vertical conduit  134  may flow the gas mixture  148  from the second conduit  178  and into the second portion  140  of the horizontal conduit  135 . The first portion  137  and the second portion of the horizontal conduit  135  may flow the gas mixture  148  from the first vertical conduit  131  and the second vertical conduit  134 , respectively, and into the third portion  141  of the horizontal conduit  135 . The third portion  141  of the horizontal conduit  135  may flow the gas mixture  148  from the horizontal conduit  135  and into the exit conduit  143 . The exit conduit  143  may exhaust the gas mixture  148  from the exhaust port  145  and the second exhaust port that is disposed between the annulus  105  and the first conduit  176 . 
     Although two conduits  176 ,  178 ; two vertical conduits  131 ,  134 ; and a pumping liner  160  with an exhaust port  145  and a second exhaust port are illustrated, any number of conduits, vertical conduits, and/or exhaust ports may be implemented in various embodiments. For example, the pumping liner  160  may have at least three exhaust ports that are fluidly coupled to respective conduits and vertical conduits. The third conduit may be coupled to the third vertical conduit and the third vertical conduit may be coupled to the horizontal conduit  135 . The three exhaust ports may be disposed along a circumferential axis of the pumping liner  160  approximately equidistant from each other, such as 120 degrees from each other. 
       FIG.  2 A  shows a schematic partial cross-sectional view of an exemplary semiconductor processing chamber  200  according to some embodiments of the present technology.  FIG.  2 A  may include one or more components discussed above with regard to  FIG.  1   , and may illustrate further details relating to that chamber. Chamber  200  is understood to include any feature or aspect of chamber  100  discussed previously in some embodiments. The chamber  200  may be used to perform semiconductor processing operations including deposition of hardmask materials as previously described, as well as other deposition, removal, and cleaning operations. Chamber  200  may show a partial view of a processing region of a semiconductor processing system, and may not include all of the components, and which are understood to be incorporated in some embodiments of chamber  200 . 
     As noted,  FIG.  2 A  may illustrate a portion of a processing chamber  200 . The chamber  200  may include a number of lid stack components, which may facilitate delivery or distribution of materials through the processing chamber  200  into a processing region  210 . A chamber lid plate  204  may extend across one or more plates of the lid stack and may provide structural support for various components, such as an output manifold  218 . Chamber  200  may include a chamber body  202 , a gas box  224 , a backing plate  226 , and a showerhead  201 . 
     Chamber  200  may include a substrate support  238 , which may include a support surface  239  on which a substrate  236  may be supported. The support surface  239  may include a medial region  231  that defines substrate seat and a peripheral edge region  233 . A top surface of the peripheral edge region  233  may be recessed and/or otherwise lower than a top surface of the medial region  231 . The substrate support  238  may include a heater and/or an electrode disposed therein. The electrode may receive direct current (DC) voltage, radio frequency (RF) energy, and/or alternating current (AC) energy to facilitate processing. The substrate support  238  may be vertically translatable along a central axis of the substrate support  238  between a transfer position as illustrated, and a process position. For example, a lift system  295  may be used to raise and lower the substrate support  238  between the transfer position and one or more process positions. In the transfer position, substrates  236  may be transferred to and from the substrate support  238  via a slit valve formed through the chamber body  202 . 
     A pumping liner  260  may be disposed about an exterior surface of the substrate support  238 . A liner  259  may be disposed between the substrate support  238  and the pumping liner  260 . For example, an outer surface of the liner  259  may be positioned against an inner surface of the pumping liner  260 , with an inner surface of the liner  259  being spaced apart from the exterior surface of the substrate support  238 . The exterior surface of the substrate support  238  and the inner surface of the liner  259  may define a gap that operates as a purge lumen  211 , which may be coupled with a purge gas source  214 . The liner  259  may be made from an electrically isolating material, such as a ceramic material. In one example, the liner  259  may be made of quartz, a ceramic material including aluminum such as aluminum oxide and/or aluminum nitride, and/or any other suitable material. The top inner edge and/or the top outer edge of the liner  259  may be rounded and/or chamfered, which may help reduce or eliminate surface singularities that may create flow separation and/or otherwise impact flow uniformity through the purge lumen  211 . 
     Chamber  200  may include an edge ring  270  that is positioned radially outward of the medial region  231  of the support surface  239 . For example, an inner portion of the edge ring  270  may be vertically aligned with the peripheral edge region  233  of the support surface  239 , while an outer portion of the edge ring  270  is in vertical alignment with at least a portion of the liner  259 . A medial portion of the edge ring  270  may extend over the purge lumen  211 . When the substrate support  238  is in the transfer position as shown in  FIG.  2 A , outer portion of the edge ring  270  may be seated on a top surface of the liner  259 , and the edge ring  270 . As the substrate support  238  is raised to the process position using the lift system  295 , the peripheral edge region  233  of the support surface  239  contacts the inner portion of the edge ring  270  and lifts the edge ring  270  off of the top surface of the liner  259 . As shown in  FIG.  2 B , in the process position the edge ring  270  is seated on the peripheral edge region  233  of the support surface  239 , with the outer portion of the edge ring  270  extending beyond the peripheral edge of the substrate support  238  and above at least a portion of the liner  259  such that a gap  272  is formed between a bottom surface of the edge ring  270  and a top surface of the liner  259 . The gap  272  may be fluidly coupled with the purge lumen  211 . 
       FIG.  2 C  illustrates a schematic partial cross-sectional view of the edge ring  270  seated on the peripheral edge region  233  of the support surface  239  while the substrate support  238  is in the process position. In this position, a top surface of the edge ring  270  may be at a same height or at a substantially same height as a top surface of the medial region  231  of the support surface  239 . For example, the edge ring  270  may have a thickness that is equal or substantially equal to a distance between top surfaces of the medial region  231  and the peripheral edge region  233  of the support surface  239 . This arrangement may help prevent the formation of any eddies, other circulation, and/or other changes in flow pattern of process gases from the showerhead  201  near the edge of the substrate  236  that could affect film deposition on the substrate  236 . As used herein, the term substantially may be understood to mean within or about 10%, within or about 5%, within or about 3%, within or about 1%, or less. The edge ring  270  may be positioned on the peripheral edge region  233  with an inner edge of the edge ring  270  abutting a transition area  237  formed between the medial region  231  and the peripheral edge region  233  such that no gap exists between the edge ring  270  and the transition area  237 . The transition area  237  may be tapered as shown here, or may be in the form of a vertical step. The inner portion and/or medial portion of the edge ring  270  may be thicker than an outer portion of the edge ring  270 , which may better facilitate formation of the gap  272  between the bottom surface of the edge ring  270  and the top surface of the liner  259 . A transition between the thicker portion and the thinner portion of the edge ring  270  may be tapered and/or stepped. 
     The medial portion of the edge ring  270  extends over the top of the purge lumen  211  and a distal edge  274  of the edge ring  270  extends radially outward over the liner  259 . For example, the distal edge  274  may extend beyond at least or about 10% of a thickness of the liner  259 , at least or about 20% of the thickness of the liner  259 , at least or about 30% of the thickness of the liner  259 , at least or about 40% of the thickness of the liner  259 , at least or about 50% of the thickness of the liner  259 , at least or about 60% of the thickness of the liner  259 , at least or about 70% of the thickness of the liner  259 , or more. Such positioning of the edge ring  270  may force purge gases from the purge lumen  211  to flow radially outward through the gap  272  and towards the pumping liner  260  as shown by arrow  280 , while the process gases from the showerhead  201  flow outward toward the pumping liner  260  between the showerhead  201  and the top surface of the edge ring  270  as shown by arrow  285 . This may move a diffusion position  275  (where the purge gas and process gases mix) radially outward and away from the substrate  236  and substrate support  238 . By moving the diffusion position  275  away from the substrate support  238 , the flow of purge gas through purge lumen  211  and gap  272  may prevent process gases from contacting lateral sides of the substrate support and may thereby prevent any film residue from accumulating on such surfaces. Similarly, the outward-disposed diffusion position  275  may enable the flow of process gases to prevent purge gases from reaching the substrate  236  to ensure that better film uniformity on the substrate  236  is achieved. 
     A size of the purge lumen  211  and/or gap  272  may be selected to further alter the location of the diffusion position  275  to ensure that the process gases do not reach the lateral exterior surface of the substrate support  238 . For example, the liner  259  may be spaced apart from the exterior surface of the substrate support  238  to form a purge lumen  211  having a width of between or about 20 mils and 600 mils, between or about 40 mils and 500 mils, between or about 60 mils and 300 mils, or between or about 80 mils and 200 mils, with a thinner purge lumen  211  leading to higher localized purge gas flow velocities that prevent process gases from entering the gap  272  and/or purge lumen  211  and reaching the lateral exterior surface of the substrate support  238 . Similar effects may be achieved by adjusting a height of the liner  259  relative to the bottom surface of the edge ring  270  to adjust a size of gap  272 . For example, the gap  272  may separate the bottom surface of the edge ring and the top surface of the liner by a vertical distance of between or about 80 mils and 300 mils, between or about 100 mils and 250 mils, or between or about 120 mils and 200 mils, with a smaller gap  272  leading to higher localized purge gas flow velocities that prevent process gases from entering the gap  272  and/or purge lumen  211 . 
     A size of the gap  272  and/or purge lumen  211  may be constant or substantially contestant as shown here. In some embodiments, a design of the liner  259  may be adjusted to create a purge gas flow path with a variable cross-section at one or more locations. For example,  FIG.  2 D  illustrates a schematic partial cross-sectional view of chamber  200  with a liner  259   d . Liner  259   d  may be similar to liner  259 , but may include a protrusion  261  that is formed on an inner surface of the liner  259   d . For example, the protrusion  261  may extend inward to the exterior surface of the substrate support  238 , which may narrow a width of the purge lumen  211   d  and create a choke point that increases the localized purge gas flow velocity. For example, a lateral distance between the exterior surface of the substrate support  238  and the protrusion  261  may be between or about 60 mils and 100 mils, between or about 70 mils and 90 mils, or about 80 mils.  FIG.  2 E  illustrates a schematic partial cross-sectional view of chamber  200  with a liner  259   e . Liner  259   e  may be similar to liner  259 , but may include a top surface that tapers and/or otherwise slopes downward in an outward direction toward the pumping liner  260 . This may create a gap  272   e  having an increasing cross-section in a downstream direction toward the pumping liner  260 , which may alter the diffusion position  275 . It will be appreciated that other variations in liner designs may be utilized to adjust the flow characteristics of the purge gas to create a diffusion position  275  that isolates the substrate  236  from purge gas flow and isolates the lateral exterior surface of the substrate support  238  from process gas flow. 
       FIG.  3    shows operations of an exemplary method  300  of semiconductor processing according to some embodiments of the present technology. The method  300  may be performed in a variety of processing chambers, including processing chambers  100  and  200  described above, which may include edge rings and liners according to embodiments of the present technology, such as edge ring  270  and liner  259 . Method  300  may include a number of optional operations, which may or may not be specifically associated with some embodiments of methods according to the present technology. 
     Method  300  may include a processing method that may include operations for forming a hardmask film or other deposition operations. The method may include optional operations prior to initiation of method  300 , or the method may include additional operations. For example, method  300  may include operations performed in different orders than illustrated. In some embodiments, method  300  may include flowing a precursor into a semiconductor processing chamber via a showerhead that is disposed above a substrate support on which the semiconductor substrate is positioned at operation  305 . The method  300  may include simultaneously flowing a purge gas through a purge lumen defined by an exterior surface of the substrate support and a liner that is spaced apart from the substrate support at operation  310 . The method  300  may include diverting the purge gas laterally outward using an edge ring that is positioned atop a peripheral edge of the substrate support and that extends laterally outward of a top end of the purge channel such that the purge gas and the precursor diffuse with one another at a diffusion position that is radially outward of a bevel of the semiconductor substrate at operation  315 . The diffusion position may be selected such that purge gas is prevented from reaching the substrate by the flow or process gas from the showerhead and such that the process gas is prevented from reaching the lateral exterior surface of the substrate support by the flow of purge gas. This helps ensure that better film uniformity is achieved on the substrate, while eliminating film residue from forming on the lateral exterior surface of the substrate support. 
     In some embodiments, the method  300  may include choking the flow of the purge gas within the purge lumen and/or a gap formed between a bottom surface of the edge ring and a top surface of the liner. For example, the liner may be designed and/or positioned to create one or more choke points that increase the localized purge gas flow velocity to help push the diffusion point radially outward. The method may include venting the precursor and the purge gas out of the semiconductor chamber via a pumping liner that is disposed proximate the diffusion position. A gap formed between a bottom surface of the edge ring and a top surface of the liner separates the bottom surface of the edge ring and the top surface of the liner by a vertical distance of between about 80 mils and 300 mils. 
     In the preceding description, for the purposes of explanation, numerous details have been set forth in order to provide an understanding of various embodiments of the present technology. It will be apparent to one skilled in the art, however, that certain embodiments may be practiced without some of these details, or with additional details. 
     Having disclosed several embodiments, it will be recognized by those of skill in the art that various modifications, alternative constructions, and equivalents may be used without departing from the spirit of the embodiments. Additionally, a number of well-known processes and elements have not been described in order to avoid unnecessarily obscuring the present technology. Accordingly, the above description should not be taken as limiting the scope of the technology. 
     Where a range of values is provided, it is understood that each intervening value, to the smallest fraction of the unit of the lower limit, unless the context clearly dictates otherwise, between the upper and lower limits of that range is also specifically disclosed. Any narrower range between any stated values or unstated intervening values in a stated range and any other stated or intervening value in that stated range is encompassed. The upper and lower limits of those smaller ranges may independently be included or excluded in the range, and each range where either, neither, or both limits are included in the smaller ranges is also encompassed within the technology, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included. 
     As used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise. Thus, for example, reference to “a heater” includes a plurality of such heaters, and reference to “the protrusion” includes reference to one or more protrusions and equivalents thereof known to those skilled in the art, and so forth. 
     Also, the words “comprise(s)”, “comprising”, “contain(s)”, “containing”, “include(s)”, and “including”, when used in this specification and in the following claims, are intended to specify the presence of stated features, integers, components, or operations, but they do not preclude the presence or addition of one or more other features, integers, components, operations, acts, or groups.