Patent Publication Number: US-9412564-B2

Title: Semiconductor reaction chamber with plasma capabilities

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This Application is a continuation of and claims priority to U.S. patent application Ser. No. 13/948,055 entitled “SEMICONDUCTOR REACTION CHAMBER WITH PLASMA CAPABILITIES,” filed Jul. 22, 2013, which issued as U.S. Pat. No. 9,018,111 on Apr. 28, 2015, the disclosure of which is hereby incorporated herein by reference. 
    
    
     FIELD OF THE DISCLOSURE 
     This disclosure relates generally to semiconductor processing, and more particularly to an apparatus and method for providing an excited species of a processing gas to a substrate or wafer in a reaction chamber. 
     BACKGROUND 
     Semiconductor fabrication processes are typically conducted with the substrates supported within a chamber under controlled conditions. For many purposes, semiconductor substrates (e.g., wafers) are heated inside the process chamber. For example, substrates can be heated by direct physical contact with an internally heated wafer holder or “chuck.” “Susceptors” are wafer supports used in systems where the wafer and susceptors absorb heat. 
     Some of the important controlled conditions for processing include, but are not limited to, pressure of the chamber, fluid flow rate into the chamber, temperature of the reaction chamber, temperature of the fluid flowing into the reaction chamber, and wafer position on the susceptor during wafer loading. 
     Heating within the reaction chamber can occur in a number of ways, including lamp banks or arrays positioned above the substrate surface for directly heating the susceptor or susceptor heaters/pedestal heaters positioned below the susceptor. Traditionally, the pedestal style heater extends into the chamber through a bottom wall and the susceptor is mounted on a top surface of the heater. The heater may include a resistive heating element enclosed within the heater to provide conductive heat and increase the susceptor temperature. 
     Consistent processing and consistent results generally require careful control and metering of processing gases in the system. One of the last resorts for controlling the processing gas is at the showerhead where the processing gas then contacts the wafer in the reaction chamber. Further, obtaining optimal flow rates and uniformity may be difficult at times due to showerhead holes becoming clogged or parasitic precursor reactions occurring within the showerhead. 
     Plasma based reactors may use direct plasma integral to the reactor or remote plasma positioned upstream of the reactor. Direct plasma can create a more intense and effective plasma but may also damage the substrate. Conversely, remote plasma reduces the risk of damage to the substrate but may suffer from the excited species being less active and therefore not properly reacting with a film on the substrate. 
     SUMMARY 
     Various aspects and implementations are disclosed herein that relate to a reaction chamber with plasma capabilities for processing a wafer. In one aspect, a processing chamber includes a reaction chamber having a processing area, a processing gas inlet in communication with the processing area, a first excited species generation zone in communication with the processing gas inlet and a second exited species generation zone in communication with the processing gas inlet. 
     In one implementation, the first and second excited species generation zones may be in communication with each other. The first and second excited species generation zones may be selectively in communication with each other. A valve may be positioned between the first excited species generation zone and the processing gas inlet. A valve may be positioned between the second excited species generation zone and the processing gas inlet. The first and second excited species generation zones may be non-co-axial. 
     The first and second excited species generation zones may be co-axially aligned. The first and second excited species generation zones may generate combustibly incompatible excited precursors. The first excited species generation zone may excite a fluorine-based chemistry and the second excited species generation zone may excite a chlorine-based chemistry. The first and second excited species generation zones may each further include an inductively coupled plasma generator. The first and second excited species generation zones inductively coupled plasma generators are each separately controlled. The first and second excited species generation zones may each further include a capacitively coupled plasma generator. The first and second excited species generation zones capacitively coupled plasma generators are each separately controlled. 
     The processing chamber may further include an inert gas flow positioned between the first and second excited species generation zones. The first and second excited species generation zones may be separated by inert gas valves. The first and second excited species generation zones may be at least partially composed of alumina or quartz. The first and second excited species generation zones may be energized with a single coil. 
     In another aspect, a method of processing a substrate may include the steps of loading a substrate within a processing area, activating a first excited species generation zone to provide a first excited species precursor to the processing area during a first pulse and, activating a second excited species generation zone to provide a second excited species precursor different from the first excited species precursor to the processing area during a second pulse. 
     In an implementation, the first and second excited species generation zones are different generation zones. 
     In another aspect, the method of delivering a plurality of precursors to a processing area may include the steps of providing a first and second excited species generation zones in communication with the processing area, selectively flowing a first precursor through the first excited species generation zone while exciting the first excited species generation zone, and selectively flowing a second precursor through the second excited species generation zone while exciting the second species generation zone. 
     This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Furthermore, the claimed subject matter is not limited to implementations that solve any or all disadvantages noted in any part of this disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a schematic sectional view of a reaction chamber with dual plasma generation regions. 
         FIG. 2  illustrates a schematic sectional view of the dual plasma generation regions. 
         FIG. 3  illustrates a schematic sectional view of the dual plasma generation regions. 
         FIG. 4  illustrates a schematic sectional view of the dual plasma generation regions 
         FIG. 5  illustrates a schematic sectional view of a second aspect dual plasma generation regions. 
         FIG. 6  illustrates a top schematic sectional view of the second aspect dual plasma generation regions taken generally about line  6 - 6  in  FIG. 5 . 
         FIG. 7  illustrates a schematic sectional view of the second aspect dual plasma generation regions. 
         FIG. 8  illustrates a schematic sectional view of the second aspect dual plasma generation regions. 
         FIG. 9  illustrates a schematic sectional view of a third aspect dual plasma generation regions. 
         FIG. 10  illustrates a top schematic sectional view of a third aspect dual plasma generation regions. 
         FIG. 11  illustrates an enlarged schematic sectional view of a fourth aspect dual plasma generation regions. 
     
    
    
     DETAILED DESCRIPTION 
     The present aspects and implementations may be described in terms of functional block components and various processing steps. Such functional blocks may be realized by any number of hardware or software components configured to perform the specified functions and achieve the various results. For example, the present aspects may employ various sensors, detectors, flow control devices, heaters, and the like, which may carry out a variety of functions. In addition, the present aspects and implementations may be practiced in conjunction with any number of processing methods, and the apparatus and systems described may employ any number of processing methods, and the apparatus and systems described are merely examples of applications of the invention. 
       FIG. 1  illustrates a processing chamber  18  with a reaction chamber  20  having an upper chamber  22  and a lower chamber  24 . Upper chamber  22  includes a showerhead  26 , while lower chamber  24  generally includes a susceptor assembly  28  as may be commonly known in the art to receive wafer  30  for loading, unloading, and processing. While the present disclosure illustrates and describes a showerhead  26  in a split chamber with upper and lower sections, it is within the spirit and scope of the present disclosure to incorporate showerhead  26  in a non-split chamber reactor or a cross-flow reactor without a showerhead. As is also commonly known, showerhead  26  is fed with an inlet manifold  32  (or manifold port injectors or other suitable injecting means in a cross-flow reactor) so that gas flow within the reactor is represented by arrows  33 . 
     Inlet manifold  32  may include a valve  34  which is commonly known in precursor delivery systems and may be a standard pneumatic valve, a mechanical valve, an inert gas valve, or any other suitable valve mechanism. Upstream of valve  34  may be a separation pipe  36  in some implementations with additional valves  38  and  40  similar to valve  34  which function to selectively isolate the various precursor inlets from each other. While not specifically shown, additional purge or vacuum ports and/or lines may be oriented downstream of valves  38  and  40  to assist with purging the separation pipe  36  and inlet manifold  32 . Valves  34 ,  38 , and  40  may be separately controlled with a controller  42  via control lines  44 ,  46 , and  48  respectively or any other suitable controlling system. 
     Precursor A  50  passes through an outlet pipe  52  upstream of valve  38 , while Precursor B  54  passes through outlet pipe  56  upstream of valve  40 . Precursor A  50  passes through a first excited species generation zone  58  while Precursor B  54  passes through a second excited species generation zone  60 . As can be seen proper valves may be used to isolate the first and second excited species generation zones  58  and  60  so that a reaction between the precursors flowing through each of the respective excited species generation zones can be prevented. 
     Each of first and second excited species generation zones  58  and  60  may include a Faraday shield  62  on an outer periphery of each zone. First excited species generation zone  58  may include control lines  64  and  66 , while second excited species generation zone  60  may include control lines  68  and  70  The various control lines  64 ,  66 ,  68 , and  70  connect to an excited species generation controller  72  as will be described in greater detail below. 
       FIG. 2  illustrates sectional views of first and second excited species generation zones  58 ,  60 . Both first and second excited species generation zones  58  and  60  include the faraday shield  62 , a safety sheath  74 , an electrical coil  76 , and a generation zone tubing  78 . A cooling region  80  is formed between safety sheath  74  and generation zone tubing  78  to provide a cooled inert gas flow to contact and maintain a proper operating temperature of the electrical coil  76  position therein. Generation zone tubing  78  includes an opening  82  therein for receiving Precursor A  50  or Precursor B depending on which excited species generation zone the tubing is positioned in. Advantageously, opening  82  is in fluid communication with appropriate precursor bottles to supply the processing gas and outlet pipe  52  or  56  before passing though gate valves  38  or  40  and ultimately gate valve  34  before reaching the reactor chamber. Generation zone tubing  78  may be composed of any suitable material for the precursors that will be utilized within opening  82 . For example, when precursors that incorporate fluorine, oxygen, or hydrogen are utilized the generation zone tubing may be alumina, while when the precursors that incorporate chlorine, oxygen, or silicon chloride are utilized the generation zone tubing may be quartz. The key is that the etch or deposition chemistries are compatible with the generation zone tubing material without unwanted reactions or particle generation. Electrical coil  76  is connected to control lines  64 ,  66  or  68 ,  70  (as appropriate) to provide electrical current at the excited species generation zones to form a magnetic field and form an excited species within the appropriate opening  82  for Precursor A  50  or Precursor B  54 . 
     Referring now to controller  72 , a powering and matching circuit  84  are shown within controller  72  while a switching circuit  86  may also be incorporated within controller  72  and operated by a processing chamber controller (not shown) in accordance with an appropriate processing recipe or program. Power and matching circuit  84  is designed to provide the proper impedance and power to electrical coils  76  to generate an adequate enough excited species within the appropriate generation zone tubing  78  that the excited species can be moved with an inert gas through the gate valves, the showerhead, and finally the wafer surface. It is also further conceived that each of the first and second exited species generation zones may need different or variable power in which case controller  72  may be regulated to provide this variable current as needed and the power circuit may utilize RF or any other suitable mechanism for power. Referring back to valves  34 ,  38 , and  40 , actuators  88  are positioned in each valve and are electrically or pneumatically controlled to open or close depending on the process step being performed. One of skill in the art will immediately appreciate that any suitable mechanism may be incorporated to prevent/permit gas flow through the valves, including actuators  88  or any other device or method known in the art. Preferably, the valves will be capable of high radical conductance to limit and/or prevent the loss of excited species. 
       FIG. 3  illustrates Precursor A  50  being directed through generation zone tubing  78  as indicated by arrows  90 , while  FIG. 4  illustrates Precursor B  54  being directed through generation zone tubing  78  as indicated by arrows  92 . In  FIG. 3 , when Precursor A  50  is necessary for wafer processing, gate valve  40  remains in the closed position while gate valve  38  and gate valve  34  open in the directions associated with arrows  94  after an appropriate amount of energy has been transferred to the precursor through coil  76 . Similarly, when Precursor B  54  is necessary for wafer processing, gate valve  38  remains in the closed position while gate valve  40  and gate valve  34  open in the direction associated with arrows  94  after an appropriate amount of energy has been transferred to the precursor through coil  76 . 
     In operation, the processes shown in  FIGS. 3 and 4  are performed separately so that the precursors, whether excited or not, do not meet. In some instances if the precursors were to mix severe damage would result. Further, the excited species generation zones may be separated from one another so that even though both excited species generation zones are being provided with activated species, only one of the activated species, or neither during a chamber purging step, reach the reaction chamber. In another implementation, the switching circuit  86  may be used to selectively activate only one appropriate excited species generation zone at a time to reduce power consumption. Finally, as can be seen in  FIG. 4 , the first and second excited species generation zones may be offset from one another and non-coaxial in one implementation. 
       FIGS. 5 through 8  illustrate a second embodiment of first and second excited species generation regions  96  within a single faraday shield  62 . In this second implementation, Precursor A  50  and Precursor B  54  are positioned co-axial with each other and share the same excited species generation source or electrical coil  76  and safety sheath  74 . Again, similar to the previous implementation, cooling inert gas may flow over electrical coil  76  through cooling region  80 . The second implementation  96  may also directly incorporate inert gas flow  98  through both the first and second excited species generation zones to direct the respective excited species precursor to the reaction chamber. 
     In the disclosed second implementation  96 , Precursor B  54  is flowing through an outer region  100  formed by region walls  102  and  104  which may be formed in the shape of a cylinder formed from a material which is complimentary and compatible with the precursor (alumina or quartz by way of non-limiting example). A gap  106  may be positioned radially inward of region wall  104  while region wall  108  forms a central opening  110 . Region wall  108  is also preferably formed from a material which is complimentary and compatible with the precursor used therein and may be, by way of non-limiting example, alumina or quartz. 
       FIG. 7  illustrates Precursor A  50  being activated and moving through central opening  110  as indicated by arrows  112 . Precursor A  50  may be moved through the first excited species generation zone with inert gas  98  and may leave the first excited species generation zone because a gate valve is opened to permit communication between the central opening  110  and reaction chamber  20 . Arrows  114  indicate the flow path of Precursor B  54  and a gate valve blocking the flow so that Precursor B  54  within the second exited species generation zone cannot leave outer region  100 . Thus, a selectively excited precursor can be provided to the reaction chamber on a selective basis with non-compatible precursors. 
       FIG. 8  illustrates Precursor B  54  being activated and moving through outer region  100  as indicated by arrows  116 . Precursor B  54  may be moved through the second excited species generation zone with inert gas  98  and may leave the second excited species generation zone because a gate valve is opened to permit communication between the outer region  100  and reaction chamber  20 . Arrows  118  indicate the flow path of Precursor A  50  and a gate valve blocking the flow so that Precursor A  50  within the first excited species generation zone cannot leave central opening  110 . In operation, Precursor A  50  will be provided to the reaction chamber  20  without Precursor B  54  and then Precursor B  54  will be provided to the reaction chamber  20  without Precursor A  50  in a cyclical process during an etching or deposition process. In this manner, incompatible precursors may be utilized within the reaction chamber without damage or danger. 
       FIGS. 9 and 10  illustrate views of a third implementation excited species generation zone  120  with a capacitively coupled plasma generator instead of an inductively coupled plasma generator as shown and described above. Once again, region walls  102  and  104  may be cylindrical in shape and define an outer region  100  where Precursor A  50  may be excited and then selectively provided to reaction chamber  20 . The plasma generator may include an inner electrode  122  and an outer electrode  124  which are connected to control lines  64  and  66  respectively. In operation, the capacitively coupled plasma inner electrode  122  and outer electrode  124  are activated by controller  72  and may selectively excite Precursor A  50  before flowing the precursor into the reaction chamber  20  for a deposition or etching process. Functionally, the third implementation excited species generation zone  120  is similar to the previously described embodiments with the exception of incorporating a capacitively coupled generator instead of an inductively coupled generator. Further, the third implementation excited species generation zone  120  may utilize non-coaxially arranged generation zones similar to the first aspect and a second excited species generation zone  120  may be positioned in selective communication with the reaction chamber in a similar manner to those previously described without departing from the spirit and scope of the present disclosure. 
       FIG. 11  illustrates a fourth implementation of an excited species generation zone  126  with faraday shield  62  and safety sheath  74 . Similar to previous capacitively coupled plasma generators, inner electrode  122  and outer electrode  124  are positioned inside and outside, respectively, of the precursor regions. An outer region  128  is formed by a first wall  130  and a second wall  132  with a precursor flowing between the two walls. An inner region  134  is formed by a third wall  136  and a four wall  138 . Walls  130 ,  132 ,  136 , and  138  may be formed of any suitable material (alumina, quartz, etc.) depending on the precursor in contact with those particular walls. In operation, a single capacitively coupled plasma generator can excite precursor in both inner region  134  and outer region  128  and the flow of those excited species is controlled by gate valves. Alternatively, separate capacitively coupled plasma generators may be utilized for each separate precursor and the flow of excited species of each precursor can be independently controlled through gate valves or based on plasma operation. 
     In operation, a wafer  30  is loaded on susceptor  28  and a first precursor is activated or excited within one of the first or second excited species generation zones before passing through the necessary gate valves and into the reaction chamber through showerhead  26 . At the same time, the second precursor may be retained within the other of the excited species generation zones until the gate valves are opened to permit passage there through. Next, the first precursor flow is stopped with gate valves and the second excited precursor or an inert gas may be provided to the reaction chamber. Since multiple implementations of a plasma generator are shown and described, a single CCP or ICP may be operated continuously to maintain an excited species in both excited species generation zones or separate CCPs and ICPs may be utilized and triggered just before the excited species is needed in the reaction chamber. In this manner, the inlet manifold and reaction chamber can selectively receive excited species of any number of precursors without the precursors coming in contact with each other during processing. Thus it is seen that incompatible excited precursors may be utilized to process a wafer or to etch a reaction chamber by selectively flowing excited species activated in separate plasma generating zones. 
     These and other embodiments for methods and apparatus for a reaction chamber with dual plasma generation regions therein may incorporate concepts, embodiments, and configurations as described with respect to embodiments of apparatus for measuring devices described above. The particular implementations shown and described are illustrative of the invention and its best mode and are not intended to otherwise limit the scope of the aspects and implementations in any way. Indeed, for the sake of brevity, conventional manufacturing, connection, preparation, and other functional aspects of the system may not be described in detail. Furthermore, any connecting lines shown in the various figures are intended to represent exemplary functional relationships and/or physical couplings between the various elements. Many alternative or additional functional relationship or physical connections may be present in the practical system, and/or may be absent in some embodiments. Further, various aspects and implementations of other designs may be incorporated within the scope of the disclosure. 
     As used herein, the terms “comprises”, “comprising”, or any variation thereof, are intended to reference a non-exclusive inclusion, such that a process, method, article, composition or apparatus that comprises a list of elements does not include only those elements recited, but may also include other elements not expressly listed or inherent to such process, method, article, composition or apparatus. Other combinations and/or modifications of the above-described structures, arrangements, applications, proportions, elements, materials or components used in the practice of the present invention, in addition to those not specifically recited, may be varied or otherwise particularly adapted to specific environments, manufacturing specifications, design parameters or other operating requirements without departing from the general principles of the same.