Patent Publication Number: US-2022223383-A1

Title: Process system with variable flow valve

Description:
BACKGROUND 
     Embodiments of the present disclosure generally relate to process chambers for semiconductor device fabrication, and in particular to a process chamber having a valve providing variable plasma flow. 
     The production of silicon integrated circuits has placed difficult demands on fabrication operations to increase the number of devices while decreasing the minimum feature sizes on a chip. These demands have extended to fabrication operations including depositing layers of different materials onto difficult topologies and etching further features within those layers. Manufacturing processes for next generation NAND flash memory involve especially challenging device geometries and scales. NAND is a type of non-volatile storage technology that does not require power to retain data. To increase memory capacity within the same physical space, a three-dimensional NAND (3D NAND) design has been developed. Such a design typically introduces alternating oxide layers and nitride layers which are deposited on a substrate and then etched to produce a structure having one or more surfaces extending substantially perpendicular to the substrate. One structure may have over 100 such layers. Such designs can include high aspect ratio (HAR) structures with aspect ratios of 30:1 or more. 
     HAR structures are often coated with silicon nitride (SiNx) layers. Conformal oxidation of such structures to produce a uniformly thick oxide layer is challenging. New fabrication operations are needed to conformally deposit layers on HAR structures, rather than simply filling gaps and trenches. 
     Therefore, an improved process chamber and components for use therein are needed. 
     SUMMARY 
     Embodiments of the present disclosure generally relate to semiconductor device fabrication, more particularly to a process chamber for conformal oxidation of high aspect ratio structures. The process chamber includes a liner assembly that in one embodiment includes a body including a first opening and a second opening opposing the first opening. The opening comprises a first end and a second end opposing the first end, and a flow valve is disposed between the first opening and the second opening. The flow valve is coupled to the body by a rotatable shaft that provides movement of the flow valve in angles between about 0 degrees and about 90 degrees relative to a central axis of the processing chamber. 
     In another embodiment, a processing system is disclosed which includes a process chamber coupled to a remote plasma chamber by a liner assembly. The liner assembly comprises a body including a first opening and a second opening opposing the first opening. The first opening comprises a first end and a second end opposing the first end. The body also includes a flow valve disposed between the first opening and the second opening, the flow valve coupled to the body by a rotatable shaft that provides movement of the flow valve in angles between about 0 degrees and about 90 degrees relative to a central axis of the process chamber. 
     In another embodiment, a process system includes a process chamber including a substrate support portion and a chamber body coupled to the substrate support portion. The chamber body includes a first side and a second side opposite the first side. The process chamber further includes a liner assembly disposed in the first side, wherein the liner assembly includes a flow valve that is rotatable relative to a centerline of the process chamber. The process chamber further includes a distributed pumping structure located in the substrate support portion adjacent to the second side, and a remote plasma source coupled to the process chamber by a connector, wherein the connector is connected to the liner assembly to form a fluid flow path from the remote plasma source to the processing volume. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only exemplary embodiments and are therefore not to be considered limiting of its scope, may admit to other equally effective embodiments. 
         FIG. 1A  is a cross-sectional view of a process system according to embodiments described herein. 
         FIG. 1B  is a perspective view of the process system according to embodiments described herein. 
         FIG. 1C  is a schematic top view of the process system according to embodiments described herein. 
         FIGS. 2A and 2B  are schematic sectional top views of the process chamber. 
         FIG. 3  is a schematic isometric view of the liner assembly coupled to the connector. 
         FIG. 4  is a schematic isometric view of the liner assembly according to another embodiment. 
     
    
    
     To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation. 
     DETAILED DESCRIPTION 
     Embodiments of the present disclosure generally relate to a process chamber for uniform film formation, for example conformal oxidation of high aspect ratio structures. The process chamber includes a liner assembly located in a first side of a chamber body and two pumping ports located in a substrate support portion adjacent a second side of the chamber body opposite the first side. A side pumping manifold is coupled to the process chamber. The side pumping manifold may be used alone or in combination with the two pumping ports to control the flow of radicals within the process chamber. The sde pumping manifold may be located either side of the process chamber. The liner assembly includes a flow valve to control the flow of radicals from the liner assembly to the pumping ports. The liner assembly may be fabricated from quartz to minimize interaction with process gases, such as radicals. The liner assembly is designed to reduce flow constriction of the radicals, leading to increased radical concentration and flux. The flow valve is provided in the liner assembly and may be used to tune the flow of the radicals through the processing region of the process chamber. Additionally, the two pumping ports can be individually controlled to tune the flow of the radicals through the processing region of the process chamber. 
       FIG. 1A  is a cross-sectional view of a process system  100  according to embodiments described herein. The process system  100  includes a process chamber  102  and a remote plasma source  104 . The process chamber  102  may be a rapid thermal processing (RTP) chamber. The remote plasma source  104  may be any suitable remote plasma source, such as a microwave coupled plasma source, that can operate at a power, for example, of about  6  kW. The remote plasma source  104  is coupled to the process chamber  102  to flow plasma formed in the remote plasma source  104  toward the process chamber  102 . The remote plasma source  104  is coupled to the process chamber  102  via a connector  106 . The components of the connector  106  are omitted in  FIG. 1A  for clarity, and the connector  106  is described in detail in connection with  FIG. 3 . Radicals formed in the remote plasma source  104  flow through the connector  106  into the process chamber  102  during processing of a substrate. 
     The remote plasma source  104  includes a body  108  surrounding a tube  110  in which plasma is generated. The tube  110  may be fabricated from quartz or sapphire. The body  108  includes a first end  114  coupled to an inlet  112 , and one or more gas sources  118  may be coupled to the inlet  112  for introducing one or more gases into the remote plasma source  104 . In one embodiment, the one or more gas sources  118  include an oxygen containing gas source, and the one or more gases include an oxygen containing gas. The body  108  includes a second end  116  opposite the first end  114 , and the second end  116  is coupled to the connector  106 . A coupling liner (not shown) may be disposed within the body  108  at the second end  116 . The coupling liner is described in detail in connection with  FIG. 3 . A power source  120  (e.g., an RF power source) may be coupled to the remote plasma source  104  via a match network  122  to provide power to the remote plasma source  104  to facilitate the forming of the plasma. The radicals in the plasma are flowed to the process chamber  102  via the connector  106 . 
     The process chamber  102  includes a chamber body  125 , a substrate support portion  128 , and a window assembly  130 . The chamber body  125  includes a first side  124  and a second side  126  opposite the first side  124 . A slit valve opening  131  is formed in the second side  126  of the chamber body  125  for allowing a substrate  142  to enter and exit the process chamber  102 . In some embodiments, a lamp assembly  132  enclosed by an upper side wall  134  is positioned over and coupled to the window assembly  130 . The lamp assembly  132  may include a plurality of lamps  136  and a plurality of tubes  138 , and each lamp  136  may be disposed in a corresponding tube  138 . The window assembly  130  may include a plurality of light pipes  140 , and each light pipe  140  may be aligned with a corresponding tube  138  so the thermal energy produced by the plurality of lamps  136  can reach a substrate disposed in the process chamber  102 . In some embodiments, a vacuum pressure is provided in the plurality of light pipes  140  by applying a vacuum to an exhaust  144  fluidly coupled to a volume formed within the plurality of light pipes  140 . The window assembly  130  may have a conduit  143  formed therein for circulating a cooling fluid through the window assembly  130 . 
     A processing region  146  may be defined by the chamber body  125 , the substrate support portion  128 , and the window assembly  130 . The substrate  142  is disposed in the processing region  146  and is supported by a support ring  148  above a reflector plate  150 . The support ring  148  may be mounted on a rotatable cylinder  152  to facilitate rotating of the substrate  142 . The cylinder  152  may be levitated and rotated by a magnetic levitation system (not shown). The reflector plate  150  reflects energy to a backside of the substrate  142  to facilitate uniform heating of the substrate  142  and promote energy efficiency of the process system  100 . A plurality of fiber optic probes  154  may be disposed through the substrate support portion  128  and the reflector plate  150  to facilitate monitoring a temperature of the substrate  142 . 
     A liner assembly  156  is disposed in the first side  124  of the chamber body  125  for radicals to flow from the remote plasma source  104  to the processing region  146  of the process chamber  102 . The liner assembly  156  may be fabricated from a material that is oxidation resistant, such as quartz, in order to reduce interaction with process gases, such as oxygen radicals. The liner assembly  156  is designed to reduce flow constriction of radical flowing to the process chamber  102 . The liner assembly  156  is described in detail below. The process chamber  102  further includes a distributed pumping structure  133  formed in the substrate support portion  128  adjacent to the second side  126  of the chamber body  125  to control the flow of radicals from the liner assembly  156  to the pumping ports. The distributed pumping structure  133  is located adjacent to the second side  126  of the chamber body  125 . The distributed pumping structure  133  is described in detail in connection with  FIG. 1C . 
     The process chamber  102  further includes a side pumping manifold  135 . The side pumping manifold  135  is formed in a sidewall of the chamber body  125  and is at least partially obscured by the substrate  142  in  FIG. 1A . The side pumping manifold  135  is positioned on the chamber body  125  between the first side  124  and the second side  126 . Like the distributed pumping structure  133 , the side pumping manifold  135  is utilized to control the flow of radicals from the liner assembly  156  through the processing region  146 . The side pumping manifold  135  may be used alone or in combination with the distributed pumping structure  133 . 
     A controller  180  may be coupled to various components of the process system  100 , such as the process chamber  102  and/or the remote plasma source  104  to control the operation thereof. The controller  180  generally includes a central processing unit (CPU)  182 , a memory  186 , and support circuits  184  for the CPU  182 . The controller  180  may control the process system  100  directly, or via other computers or controllers (not shown) associated with particular support system components. The controller  180  may be one of any form of general-purpose computer processor that can be used in an industrial setting for controlling various chambers and sub-processors. The memory  186 , or computer-readable medium, may be one or more of readily available memory such as random access memory (RAM), read only memory (ROM), floppy disk, hard disk, flash drive, or any other form of digital storage, local or remote. The support circuits  184  are coupled to the CPU  182  for supporting the processor in a conventional manner. The support circuits  184  include cache, power supplies, clock circuits, input/output circuitry and subsystems, and the like. Processing steps may be stored in the memory  186  as software routine  188  that may be executed or invoked to turn the controller  180  into a specific purpose controller to control the operations of the process system  100 . The controller  180  may be configured to perform any methods described herein. 
       FIG. 1B  is a perspective view of the process system  100  according to embodiments described herein. As shown in  FIG. 1B , the process chamber  102  includes the chamber body  125  having the first side  124  and the second side  126  opposite the first side  124 . The process system  100  is shown in  FIG. 1B  with the window assembly  130  and the lamp assembly  132  of  FIG. 1A  removed for clarity. The process chamber  102  may be supported by a frame  160  and the remote plasma source  104  may be supported by a frame  162 . A first conduit  164  is coupled to one of the two pumping ports (not visible in  FIG. 1B ) and a valve  170  is provided in the first conduit  164  to control the flow of radicals within the process chamber  102 . A second conduit  166  is coupled to the other pumping port (not visible in  FIG. 1B ) of the two pumping ports and a valve  172  is provided in the second conduit  166  to control the flow of radicals within the process chamber  102 . A third conduit  171  is coupled to the side pumping manifold  135 . A valve  173  is provided in the third conduit to control the flow of radicals within the process chamber  102 . The first conduit  164 , the second conduit  166 , and the third conduit  171  are coupled to a main exhaust conduit  168 , which may be connected to a vacuum pump (not shown). 
       FIG. 1C  is a schematic top view of the process system  100  of  FIG. 1A  according to embodiments described herein. As shown in  FIG. 1C , the process system  100  includes the remote plasma source  104  coupled to the process chamber  102  via the connector  106 . The process system  100  is shown in  FIG. 1C  with the window assembly  130  and the lamp assembly  132  of  FIG. 1A  removed for clarity. The process chamber  102  includes the chamber body  125  having the first side  124  and the second side  126 . The chamber body  125  may include an interior edge  195  and an exterior edge  197 . The exterior edge  197  may include the first side  124  and the second side  126 . The interior edge  195  may have a shape similar to the shape of a substrate being processed in the process chamber  102 . In one embodiment, the interior edge  195  of the chamber body  125  is circular. The exterior edge  197  may be rectangular, as shown in  FIG. 1C , polygonal, or other suitable shape. In one embodiment, the chamber body  125  is a base ring. The liner assembly  156  is disposed in the first side  124  of the chamber body  125 . The liner assembly  156  includes a flow valve  190 . The flow valve  190  is utilized to tune the flow of the radicals over the substrate  142 . For example, the flow valve  190  may be used to deflect fluid flow from a center of the substrate  142 , and/or provide a higher concentration of radicals near the edge of the substrate  142 . Without the flow valve  190 , an oxide layer formed on the substrate  142  may have a non-uniform thickness, such that the oxide layer at the center of the substrate is thicker than the oxide layer at the edge of the substrate. By utilizing the flow valve  190 , the oxide layer formed on the substrate can have an enhanced thickness uniformity and conformality as compared to conventional approaches (e.g., without the flow valve  190 ). 
     The process chamber  102  includes a distributed pumping structure  133  having a two or more pumping ports  174  and  176 . The two or more pumping ports are connected to one or more vacuum sources and independently flow controlled. In one embodiment, as shown in  FIG. 1C , two pumping ports  174 ,  176  are formed in the substrate support portion  128  adjacent to the second side  126  of the chamber body  125 . The two pumping ports  174 ,  176  are spaced apart and can be controlled independently or together based on process requirements. The pumping port  174  may be connected to the conduit  164  ( FIG. 1B ), and the pumping from the pumping port  174  can be controlled by the valve  170 . The pumping port  176  may be connected to the conduit  166  ( FIG. 1B ), and the pumping from the pumping port  176  can be controlled by the valve  172 . The oxide layer thickness uniformity can be further improved by individually and/or simultaneously controlling pumping from each pumping port  174 ,  176  to achieve desired thickness uniformity and conformality. Fluid, such as oxygen radicals, flowing through the process chamber  102  from the first side  124  to the second side  126  may be increased by opening valve  172  and/or valve  170  in a particular region within process chamber and change the uniformity and conformality of oxide thickness. Increased fluid flowing through the process chamber  102  can increase fluid density, such as oxygen radical density, leading to faster deposition on the substrate  142 . Because the pumping port  174  and the pumping port  176  are spaced apart and controlled independently and/or simultaneously, fluid flowing across different portions of the substrate  142  can be increased or decreased, leading to faster or slower deposition on different portions of the substrate  142  to compensate for thickness non-uniformity of the oxide layer at different portions of the substrate  142 . Additionally, the side pumping manifold  135  can be used alone or in combination with one or both of the pumping ports  174 ,  176  in order to further control radical flow. 
     In one embodiment, the two pumping ports  174 ,  176  are positioned in a spaced apart relation along a line  199 . In one embodiment, the line  199  is perpendicular to a gas flow path from the first side  124  to the second side  126  of the chamber body  125 . The line  199  may be adjacent to the second side  126  of the chamber body  125 , and the line  199  may be outside of the substrate support ring  148 , as shown in  FIG. 1C . In some embodiments, the line  199  may intersect a portion of the substrate support ring  148 . In some embodiments, the line  199  is not perpendicular to the gas flow path, and the line  199  may form an acute or obtuse angle with respect to the gas flow path. The pumping ports  174 ,  176  may be disposed symmetrically or asymmetrically in the substrate support portion  128  with respect to a central axis  198  of the process chamber  102 , as shown in  FIG. 1C . The side pumping manifold  135  is provided in an orientation that is orthogonal to the central axis  198  of the process chamber  102 . The flow valve  190  is coupled to the liner assembly  156  at a pivot point  196 . The pivot point comprises a rotatable shaft. In some embodiments, the pivot point  196  is positioned along the central axis  198  of the process chamber  102 . 
       FIGS. 2A and 2B  are schematic sectional top views of the process chamber  102 . The window assembly  130  and the lamp assembly  132  shown in  FIG. 1A  are removed for clarity. In  FIGS. 2A and 2B , a plasma flow path is indicated by arrows  200 , which travels from the remote plasma source  104  (not shown) through the connector  106  to the processing region  146 . In  FIG. 2A , the pumping ports  174 ,  176  exhaust the plasma from the processing region  146 . In  FIG. 2B , the pumping ports  174 ,  176  as well as the side pumping manifold  135  are utilized to exhaust the plasma from the processing region  146 . The flow path  200  is generally parallel to the central axis  198  of the process chamber  102  upstream of the flow valve  190 . However, adjustment of the flow valve  190  changes the flow path  200  downstream of the flow valve  190 . 
     The flow valve  190  is positioned within the plasma flow path  200 . The flow valve  190  is positioned downstream of the remote plasma source  104  and the connector  106 , and upstream of the substrate  142  positioned on the substrate support ring  148 . The flow valve  190  is configured to rotate about the pivot point  196 . The flow valve  190  may be rotated relative to the central axis  198  of the process chamber  102  to control the flow of radicals within the process chamber  102 . The rotation is indicated by an angle θ. The angle θ may be varied along the direction indicated by the arrow  210 . The angle θ may be varied between 0 degrees (parallel to the central axis  198  of the process chamber  102 ) up to about 90 degrees relative to the central axis  198  of the process chamber  102 . 
     The flow valve  190  may be adjusted manually or be coupled to an actuator  205 . In some embodiments, the angle θ of the flow valve  190  is adjusted between process runs after measurements are completed on a previously processed substrate. For example, oxide thickness uniformity of a first substrate is measured after processing in the process chamber  102 . If the thickness uniformity of the first substrate is not up to specification, the flow valve  190  is then adjusted for processing a second substrate. Additionally, the oxide uniformity may be tuned by using different combinations of the pumping ports  174 ,  176  and the side pumping manifold  135 . 
       FIG. 3  is a schematic isometric view of the liner assembly  156  coupled to the connector  106 . A first opening  300  of the liner assembly  156  is shown. The first opening  300  is in fluid communication with the processing region  146  ( FIG. 1A ) of the process chamber  102  (not shown in  FIG. 3 ). The first opening  300  opposes a second opening  305  that is coupled to the connector  106 . The first opening  300  is larger than the second opening  305 . 
     The first opening  300  includes a lower sidewall  310  and an upper sidewall  315 . The lower sidewall  310  and the upper sidewall  315  may be planar across the first opening  300  or curved across the first opening  300 . The first opening  300  includes a first height H 1  and a second height H 2 . The first height H 1  may be the same as the second height H 2  , or the first height H 1  may be different than the second height H 2  . Varying one or both of the shape of the lower sidewall  310  and the upper sidewall  315 , and the first height H 1  and the second height H 2  , may be provided to vary plasma flow through the liner assembly  156 . 
     For example, the second height H 2  may be less than the first height H 1  such that one or both of the lower sidewall  310  and the upper sidewall  315  are curved inward (i.e., concave). In this example, a center area  320  of the first opening  300  is constricted as compared to ends  325  of the first opening  300 . 
     Variations in the profile of the first opening  300  are utilized to maintain uniform flow on a wider area. In one implementation, variations in one or both of the shape of the lower sidewall  310  and the upper sidewall  315 , and/or the first height Hi and the second height H 2  , provide a 35% reduction in the center area  320  of the first opening  300 . In another implementation, variations in one or both of the shape of the lower sidewall  310  and the upper sidewall  315 , and/or the first height H 1  and the second height H 2  , provide a 40% reduction in the center area  320  of the first opening  300 . In another implementation, variations in one or both of the shape of the lower sidewall  310  and the upper sidewall  315 , and/or the first height H 1  and the second height H 2  , provide a 60% reduction in the center area  320  of the first opening  300 . In another implementation, variations in one or both of the shape of the lower sidewall  310  and the upper sidewall  315 , and/or the first height H 1  and the second height H 2  , provide a 65% reduction in the center area  320  of the first opening  300 . 
     Testing of the process chamber  102  having the liner assembly  156  and flow valve  190  as described herein was performed. The flow valve  190  was tested at varying angles (angle θ (shown in  FIGS. 2A and 2B )) with the first opening  300  liner assembly  156  having various profiles. Center to edge uniformity of an oxide film was measured based on the tests. 
       FIG. 4  is a schematic isometric view of the liner assembly  156  according to another embodiment. The liner assembly  156  coupled to the connector  106  as in other embodiments. The liner assembly  156  of  FIG. 4  is similar to the liner assembly described in  FIG. 3  with the exception of multiple flow valves  190 . In addition, the pivot points  196  of the flow valves  190  is at or near a center of the respective flow valves  190 . Other elements in  FIG. 4  that are described in  FIG. 3  will not be described again for brevity. 
     The multiple flow valves  190  are separated angularly and/or linearly with respect to each other as shown in  FIG. 4 . A length, a height and/or an angular position of each of the flow valves  190  may or may not be same. While four flow valves  190  are shown in  FIG. 4 , the number of flow valves may be more or less depending on process requirements. 
     The flow valve  190  as shown in  FIG. 3  or the multiple flow valves  190  shown in  FIG. 4  is/are utilized to direct plasma flow asymmetrically or offset with respect to the center of a substrate. Adjustment of the angle θ of the flow valve  190  is utilized such that no plasma is flowed directly to the center of the substrate. Due to the angular orientation of the flow valve  190 , a certain amount of plasma flow is “dragged” by the substrate during rotation. The asymmetric plasma flow will provide a parallel and/or a straight constant thickness layer over a certain portion of the substrate as compared to conventional injection which is directed towards the center of the substrate. The layer thickness profile can be controlled or further modified using the various pumping schemes described above. 
     While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.