Patent Publication Number: US-9890473-B2

Title: Batch epitaxy processing system having gas deflectors

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims benefit of U.S. Provisional Patent Application Ser. No. 62/020,722, filed Jul. 3, 2014, and U.S. Provisional Patent Application Ser. No. 62/082,951, filed Nov. 21, 2014, which are herein incorporated by reference. 
    
    
     BACKGROUND 
     Field 
     Embodiments of the present disclosure generally relate to apparatus and methods for forming epitaxial materials on substrates, such as semiconductor substrates. 
     Description of the Related Art 
     Epitaxy refers to the formation of a crystalline overlayer on a crystalline substrate. Epitaxial films may be grown from gaseous or liquid precursors using the crystalline substrate as a seed crystal. Thus, the grown films may have the same or similar crystallographic orientation with respect to the crystalline substrate. Crystalline substrates are processed one at a time to obtain sufficient epitaxial film quality due to processing restraints with respect to process gas flow. However, because only a single substrate is processed at a time, epitaxial formation can often be a bottle neck of device throughput. 
     Therefore, there is a need for a method and apparatus to form epitaxial films on multiple substrates concurrently. 
     SUMMARY 
     Embodiments described herein generally relate to methods and apparatus for batch processing of substrates during epitaxial film formation. In one example, a process chamber includes a chamber lid and substrate support. The chamber lid includes a centrally disposed gas inlet and a first gas deflector coupled to the chamber lid and adapted to direct the first process gas laterally across surfaces of a plurality of substrates. The lid also includes one or more gas outlets disposed radially outward of the centrally disposed gas inlet. The lid also includes a plurality of lamps disposed between the centrally disposed gas inlet and the one or more gas outlets. The substrate support is rotatable and includes a gas passage formed therein. The gas passage introduces a second process gas to the internal volume of the process chamber. A second gas deflector is adapted to direct the second process gas laterally across the surfaces of the plurality of substrates. 
     In another example, a process chamber comprises a chamber body and a chamber lid disposed on the chamber body. The chamber lid includes a centrally disposed gas inlet for introducing a first process gas to an internal volume of the process chamber. The chamber lid also includes a first gas deflector coupled to the chamber lid for directing the first process gas laterally across surfaces of a plurality of substrates. The chamber lid also includes one or more gas outlets disposed radially outward of the centrally disposed gas inlet. A plurality of lamps is disposed within the chamber lid. The process chamber further comprises a rotatable substrate support disposed within the process chamber. The rotatable substrate support is adapted to support the plurality of substrates thereon. The rotatable substrate support includes a second gas deflector adapted to direct the second process gas laterally across the surface of the plurality of substrates. 
     In another example, a method of processing a plurality of substrates comprises introducing process gas through a gas inlet formed in a chamber lid. The chamber lid is positioned on a chamber body. The method further comprises deflecting the process gas laterally across the surfaces of one or more substrates. The method also includes introducing additional process gas through a gas inlet formed in a substrate support. The method also includes deflecting the additional process gas laterally across the surfaces of the one or more substrates. The method also includes exhausting the process gas and the additional process gas from the chamber body. 
    
    
     
       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, and the disclosure may admit to other equally effective embodiments. 
         FIG. 1  illustrates a sectional view of a process chamber according to one embodiment of the disclosure. 
         FIG. 2  illustrates a sectional view of a process chamber according to another embodiment of the disclosure. 
         FIG. 3  illustrates a bottom plan view of a chamber lid, according to one embodiment of the disclosure. 
         FIG. 4  illustrates a top plan view of a substrate support, according to one embodiment of the disclosure. 
         FIG. 5  illustrates a sectional view of a gas deflector, according to one embodiment of the disclosure. 
         FIG. 6  illustrates a processing system, according to one embodiment of the disclosure. 
         FIG. 7  illustrates a processing system, according to another embodiment of the disclosure. 
     
    
    
     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 described herein generally relate to methods and apparatus for batch processing of substrates during epitaxial film formation. In one example, a process chamber includes a chamber lid and substrate support. The chamber lid includes a centrally disposed gas inlet and a first gas deflector coupled to the chamber lid and adapted to direct the first process gas laterally across surfaces of a plurality of substrates. The lid also includes one or more gas outlets disposed radially outward of the centrally disposed gas inlet, and a plurality of lamps disposed between the centrally disposed gas inlet and the one or more gas outlets. The substrate support is rotatable and includes a gas passage formed therein for introducing a second process gas to the internal volume of the process chamber. The substrate support also includes a second gas deflector adapted to direct the second process gas laterally across the surfaces of the plurality of substrates. 
       FIG. 1  illustrates a sectional view of a process chamber  100  according to one embodiment of the disclosure. The process chamber  100  includes a chamber body  102  having a chamber lid  104  disposed thereon. The chamber body  102  defines an internal volume having a purge region  106   a  and a process region  106   b . A substrate support  108  is positioned within the internal volume and divides the internal volume into the purge region  106   a  and the process region  106   b . In one example, the substrate support  108  is a circular support member having an upper surface  108   u  and a lower surface  108   d . The substrate support  108  is formed from graphite and may optionally include a silicon carbide coating thereon, and is adapted to support a plurality of substrate  110  on the upper surface  108   u  thereof. For example, the substrate support  108  may include one or more recess  108   r  formed therein for supporting four, six, eight, or more substrates  110 . 
     A support shaft  112  is coupled to and centrally positioned relative to the lower surface  108   d  of the substrate support  108 . The support shaft  112  is a cylindrical member formed from quartz, graphite, or graphite coated with silicon carbide. A gas conduit  114  is positioned axially within the support shaft  112  to facilitate transfer of process gas from a process gas source  116  to the process region  106   b  via gas lines  118 . A bearing sleeve  120  containing a plurality of bearings  122  therein is positioned radially outward of the gas conduit  114 . The bearing sleeve  120  facilitates rotation of the support shaft  112  relative to the stationary gas conduit  114  to effect rotation of the substrate support  108 . A rotating seal  123  may be disposed between the support shaft  112  and the gas lines  118  to facilitate a fluid-tight connection therebetween. An actuator  121 , such as a motor, is coupled to the support shaft  112  to facilitate rotational and vertical movement of the support shaft  112  and the substrate support  108  coupled thereto. 
     The substrate support  108  may include one or more gas passages  124  formed through a plate  170  disposed in a central portion of the substrate support  108 . The central portion of the substrate support  108  may include a recess  171  formed therein to accommodate the plate  170 . In one example, multiple gases may be introduced to the recess  171  before flowing through the plate  170 . In such an example, the recess  171  facilitates mixing of gases prior to entering the process region  106   b  through the plate  170 . 
     The gas passages  124  of the plate  170  facilitate transfer of process gas from the gas conduit  114  to the process region  106   b  through the substrate support  108 . As process gas enters the process region  106   b , the process gas contacts a gas deflector  126  centrally coupled to and extending from an upper surface  108   u  of the substrate support  108 . The gas deflector  126  includes a support post  126   s  coupled to a lower surface of a gas deflection member  126   d . In one example the gas deflection member  126   d  may be a disc-shaped or circular member, and the support post  126   s  may be disposed centrally relative thereto. In one example, the support post  126   s  may be coupled to a central portion of the plate  170 . 
     The gas deflector  126  is positioned adjacent to the one or more gas passages  124  and is adapted to direct process gas exiting from the one or more gas passages  124  in a lateral direction, as illustrated by arrows  128 . The process gas flows radially outward and flows parallel to an upper surface of the substrates  110  to facilitate formation of an epitaxial film on the upper surface of the substrates  110 . In one example, a lower surface of the gas deflection member  126   d  may have a conical shape having surfaces disposed at an angle relative to the upper surface  108   u  of the substrate support  108 . In one example, the lower surface of the gas deflection member  126   d  may positioned at an angle relative to the upper surface  108   u  between about parallel and about 60 degrees. In one example, the gas deflector  126  may be formed form quartz; however, other materials are also contemplated. 
     A chamber lid  104  is supported on the chamber body  102 . The chamber lid  104  may be formed from stainless steel, aluminum, or other metals and metal alloys. The chamber lid includes a plurality of lamps  130  disposed therein and exposed on a lower surface thereof in order to facilitate radiant heating of the substrates  110  positioned thereunder. The plurality of lamps  130  may be positioned in a circular configuration to track the rotation of the substrates  110 . A gas conduit  132  is disposed radially inward of the plurality of lamps  130  and centrally with respect to the chamber lid  104 . The gas conduit  132  is disposed axially through the chamber lid  104  to fluidly couple process gas line  134  to the process region  106   b  through openings  138   o  formed in a plate  138   p . The process gas line  134  is coupled to the process gas source  116 . The process gas source  116  may provide one or more process gases, including silicon or germanium sources, inert gases, group III sources, group V sources, and dopants such as n-type or p-type dopants. Process gas provided through the gas conduit  132  is a redirected by a gas deflector  136 . The gas deflector may be the same or similar to the gas deflector  126 , and may direct incoming process gas radially outward as shown by arrows  137 . In one example, gas deflected by the gas deflectors  126  and  136  maintains a laminar flow regime as the process gas flows adjacent to substrates  110  to facilitate uniform epitaxial formation. The distance between the gas deflectors  126  and  136  may be about 2 mm or less in a processing or elevated position of the substrate support  108 . 
     One or more exhaust plenums  138  are disposed radially outward of the plurality of lamps  130  to facilitate evacuation of gas from the process region  106   b . The one or more exhaust plenums  138  are formed in a lower surface of the chamber lid  104 , and are positioned sufficiently radially outward of the substrates  110  to facilitate a parallel gas flow relative to the upper surface of the substrates  110 . For example, as shown in  FIG. 1A , the one or more exhaust plenums  138  are positioned such that an upward flow of process gas towards the exhaust plenums, as shown by arrows  140 , does not begin until radially outward of the substrates  110 . The one or more exhaust plenums  138  may be coupled to an exhaust pump  139  to facilitate removal of process gases from the process region  106   b.    
     A heater  142 , such as a resistive heater, may be positioned within the purge region  106   a  beneath the substrate support  108 . The heater  142  may be coupled to or supported by a lower surface of the chamber body  102 . The heater  142  may have a similar footprint as the substrate support  108 . Alternatively, the heater  142  may be a plurality of lamps adapted to direct radiant heat to the substrate support  108 . 
     In an alternative embodiment, it is contemplated that one of the gas deflectors  126 ,  136  may be omitted. In such an embodiment, an opposite surfaces of the remaining gas deflector may be utilized to deflect process gas introduced to the process chamber  100  through both the chamber lid  104  and the substrate support  108 . 
       FIG. 2  illustrates a sectional view of a process chamber  200  according to another embodiment of the disclosure. The process chamber  200  is similar to the process chamber  100 , however, the process chamber  200  includes a substrate support  208  having one or more exhaust plenums  244  formed therein. The one or more exhaust plenums  244  facilitate removal of gases through the substrate support  208 . The one or more exhaust plenums  244  are formed in the upper surface  208   u  of the substrate support  208  and are disposed laterally outward of substrates  110 . In one example, the one or more exhaust plenums  244  may be disposed proximate an outer edge of the substrate support  208 . In one example, the one or more exhaust plenums  244  is a circular or ring-shaped channel. 
     The one or more exhaust plenums  244  are coupled to an exhaust pump  246  via one or more conduits  248  (one is shown) to facilitate removal of gases through the substrate support  208 . The one or more exhaust plenums  244  are disposed opposite the one or more exhaust plenums  138 ; however, it is contemplated that the one or more exhaust plenums  244  may be disposed radially inward or outward relative to the one or more exhaust plenums  138 . The one or more exhaust plenums  244  may be discrete plenums positioned at predetermined intervals around the periphery of the substrate support  208 . Alternatively, the one or more exhaust plenums  244  may be a continuous exhaust channel formed around the periphery of the substrate support  208 . 
     In another example, the one or more exhaust plenums  244  may be positioned adjacent to and in close proximity with the radially outward edges of the substrates  110 . The one or more exhaust plenums  244  further facilitate lateral gas flow parallel to the surface of the substrate  110  by influencing the flow of gas as it is exhausted, as shown by arrow  250 . Thus, some process gas is drawn upward as shown by arrow  140 , while some gas is drawn downwards, as shown by arrow  250 , resulting in a net lateral flow as gas moves relative to the substrates  110 . The net lateral flow enhances deposition uniformity. It is contemplated that the relative amount of gas evacuated through the one or more exhaust plenums  138 ,  244  may be adjusted to achieve the desired flow regime of process gas within the process region  106   b . A gas deflector  292  may be positioned radially outward of each of the one or more exhaust plenums  244  to facilitate directing of gas into the one or more exhaust plenums  244 . The gas deflector  292  may be positioned at an angle with respect to the upper surface of the substrate support  208 , such as about 45 degrees to about 135 degrees, for example, 90 degrees. While not shown for clarity, it is contemplated that the process chamber  200  may include a bearing sleeve  120  and a rotating seal  123  (shown in  FIG. 1 ) to facilitate rotation of the substrate support  208 . The actuator  121  may facilitate vertical and/or rotational actuation of the substrate support  208 . Additionally, although not shown, it is to be understood that the process chamber  200  may include one or more pyrometers disposed therein for detecting a temperature of the substrates  110 . 
       FIG. 3  illustrates a bottom plan view of a chamber lid  304 , according to one embodiment of the disclosure. The chamber lid  304  is similar to the chamber lid  104 ; however, the chamber lid  304  includes a ring-shaped exhaust plenum  338  disposed at a radially-outward edge thereof. A plurality of lamps  130  including individual lamps  331  are disposed radially inward of the ring-shaped exhaust plenum  338  and radially outward of the gas deflector  136 . Multiple openings  138   o  are formed in the chamber lid  304  and are positioned beneath the gas deflector  136  for facilitating introduction of process gases into a process chamber. The openings  138 o are shown in phantom. It is contemplated that the size, position, and amount of lamps  331  may be adjusted to affect a desired level of heating of substrates. Other lamp patterns and configurations are contemplated. 
       FIG. 4  illustrates a top plan view of a substrate support  108 , according to one embodiment of the disclosure. The substrate support  108  includes a centrally positioned gas deflector  126 , under which one or more gas passages  124  (five are shown) are disposed to facilitate introduction of process gases to the internal volume of the process chamber. A plurality of substrates may be disposed on the substrate support  108  to facilitate formation of an epitaxial film thereon. Although eight substrates  110  are shown, it is contemplated that more or less substrates  110  may be positioned on the substrate support  108 , and that the substrate support  108  may be sized accordingly. 
       FIG. 5  illustrates a sectional view of a gas deflector  526 , according to one embodiment of the disclosure. The gas deflector  526  may be used in place of the gas deflectors  126  and  136  shown in  FIG. 1 . In one example, a single gas deflector  526  may replace both gas deflectors  126  and  136 . The gas deflector  526  includes a support post  526   s  for coupling the gas deflector  526  to a chamber lid or to a substrate support. The support post  526   s  is coupled to or integrally formed with a gas deflection member  526   d.    
     The gas deflection member  526   d  includes a first gas deflection surface  552  disposed adjacent the support post  526   s . The first gas deflection surface  552  is adapted to laterally direct process gas introduced to a process chamber through a conduit (not shown) adjacent the first gas deflection surface  552 . The first gas deflection surface may be disposed at an angle of about 5 degrees to about 90 degrees relative to the support post  526   s , such as about 45 degrees to about 90 degrees. 
     The gas deflection member  526   d  also includes a second gas deflection surface  554  disposed opposite of the first gas deflection surface  552 . The second gas deflection surface  554  is conically shaped and is adapted to laterally deflect process gas directed at that second gas deflection surface  554 . In one embodiment, it is contemplated that the second gas deflection surface  554  may be planar or substantially planar. 
       FIG. 6  illustrates a processing system  660  according to one embodiment of the disclosure. The processing system  660  includes a factory interface  661  adapted to receive substrates for processing from one or more cassettes  662 . The factory interface  661  includes a robot therein for transferring robots to/from load locks  663   a ,  663   b . The load locks  663   a ,  663   b  facilitate transfer of substrates to and from a batch substrate pre-clean chamber  664 . The batch substrate pre-clean chamber  664  may adapted to remove oxides, such as native oxides, from the surfaces of substrates disposed therein. 
     The batch substrate pre-clean chamber  664  is coupled to a mainframe  666  through one or more buffer chambers  665   a ,  665   b  (two are shown). The mainframe  666  facilitates transfer of substrates from the one or more buffer chambers  665   a ,  665   b  to process chamber  667   a ,  667   b . In one embodiment, one or more of the process chambers  667   a ,  667   b  may be a process chamber such as process chambers  100 ,  200  described herein. Due to the positioning of the process chambers  667   a ,  667   b , side access of the process chambers  667   a ,  667   b  is permitted from an area  668 , thereby reducing the footprint of the processing system  660 . 
       FIG. 7  illustrates a processing system  760  according to another embodiment of the disclosure. The processing system  760  is similar to the processing system  660 ; however, the pre-clean chamber  664  may be replaced with a transfer chamber  789  housing one or more robots therein and adapted to transfer substrates therethrough. A plurality of pre-clean chambers  764   a - d  (four are shown) may be disposed about in and communication with the transfer chamber. Each of the pre-clean chambers  764   a - d  may be adapted to receive a substrate from the transfer chamber  789 , and to perform a pre-clean operation therein on the substrate before the substrate is transferred back to the transfer chamber  789 . 
     Benefits of embodiments herein include uniform epitaxial deposition during batch process of substrates, thus increasing substrate throughput. While embodiments herein generally use lamps for heating of substrates, it is contemplated that resistive heaters may also be utilized in addition to, or as an alternative to, lamps. 
     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.