Patent Publication Number: US-9848461-B2

Title: Methods and apparatus for thermally treating a substrate

Description:
FIELD 
     Embodiments of the present disclosure generally relate to substrate processing equipment. 
     BACKGROUND 
     Various substrate process sequences use some type of thermal treatment in addition to the deposition or etch processes that are performed on the substrate. These processes are typically performed in a vacuum environment. Such thermal treatment may be performed before or after the process. For example, a substrate may be thermally treated before processing to degas any absorbed moisture on the substrate. After processing of a substrate, the substrate may be thermally treated to anneal the processed substrate. 
     In many cases, standalone furnaces are used to thermally treat a substrate. However, a separate furnace is costly and occupies a large amount of valuable space in a fab. Also, the thermal treatment, for example for a degas process, takes a relatively long time due to the extensive time for moisture and residue removal to be completed. If the thermal treatment operation (before or after processing) takes longer than the process itself, the throughput of the entire system is negatively impacted. 
     Therefore, the inventor has provided an improved substrate heating apparatus for use with integrated fabrication systems. 
     SUMMARY 
     Embodiments of methods and apparatus for thermally treating a substrate are provided herein. In some embodiments, a thermal treatment apparatus includes a chamber body including an interior volume; a plurality of substrate supports disposed within the interior volume, wherein each of the plurality of substrate supports includes a heating element; a selectively sealable opening in the chamber body sized to allow substrates to be inserted into or removed from the interior volume; a robotic arm disposed in the interior volume to move substrates onto and off of the plurality of substrate supports; and a heating assembly configured to heat substrates disposed on the robotic arm. 
     In some embodiments, a substrate processing system includes: a thermal treatment apparatus as described in any of the embodiments disclosed herein; at least one substrate processing chamber; and at least one transfer robot to transfer substrates between the at least one substrate processing chamber and the thermal treatment apparatus. 
     In some embodiments, a method for thermally treating a substrate includes inserting a substrate into an interior volume of a thermal treatment apparatus using a transfer robot; transferring the substrate from the transfer robot to a robotic arm disposed in the interior volume; heating the substrate to a first predetermined temperature using a plurality of infrared energy sources disposed above the robotic arm; placing the substrate onto one of a plurality of substrate supports in the interior volume using the robotic arm; and heating the substrate to a second predetermined temperature using a heating element disposed in the substrate support. 
     In some embodiments, a thermal treatment apparatus includes a chamber body including an interior volume; a plurality of vertically aligned substrate supports disposed within the interior volume, wherein each of the plurality of substrate supports includes a heating element; a selectively sealable opening in the chamber body sized to allow substrates to be inserted into or removed from the interior volume; a robotic arm disposed in the interior volume to move substrates onto and off of the plurality of substrate supports; and a plurality of halogen lamps disposed in an upper portion of the chamber body proximate the selectively sealable opening configured to heat substrates disposed on the robotic arm. 
     Other and further embodiments of the present disclosure are described below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the present disclosure, briefly summarized above and discussed in greater detail below, can be understood by reference to the illustrative embodiments of the disclosure depicted in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments. 
         FIG. 1  is a schematic view of a processing system suitable for use with a thermal treatment apparatus in accordance with some embodiments of the present disclosure. 
         FIG. 2  is a schematic top view of a thermal treatment apparatus in accordance with some embodiments of the present disclosure. 
         FIG. 3  is a schematic side view of a thermal treatment apparatus in accordance with some embodiments of the present disclosure. 
         FIG. 4  is a schematic top view of a robotic arm suitable for use with a thermal treatment apparatus in accordance with some embodiments of the present disclosure. 
         FIG. 5  is a flow chart illustrating a method of thermally treating a substrate in accordance with some embodiments of the present disclosure. 
     
    
    
     To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. The figures are not drawn to scale and may be simplified for clarity. 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 substrate thermal treatment methods and apparatus for use in integrated substrate fabrication systems. Embodiments of the inventive thermal treatment apparatus advantageously mounts directly to a cluster tool including at least one processing chamber, thus increasing throughput of the cluster tool while minimizing any negative impact on the floor space occupied by the cluster tool. 
       FIG. 1  is a schematic top-view diagram of an exemplary cluster tool  100  (i.e., a substrate processing system) that may be suitable for use with the present inventive apparatus disclosed herein. The cluster tool  100  features at least one substrate processing chamber (e.g., a physical vapor deposition (PVD) chamber)  102  and at least one thermal treatment apparatus  104  (two shown in  FIG. 1 :  104   a ,  104   b ), as described below. Examples of the integrated cluster tool  100  include the ENDURA® integrated tool, available from Applied Materials, Inc., of Santa Clara, Calif. It is contemplated that the methods described herein may be practiced using other cluster tools having suitable process chambers coupled thereto, or in other suitable process chambers. For example, it may be advantageous in some embodiments, to perform the inventive methods discussed above in an integrated tool such that there are limited or no vacuum breaks between processing steps. For example, reduced vacuum breaks may limit or prevent contamination between layers or other portions of the substrate. 
     The cluster tool  100  can include one or more load lock chambers  106 A,  106 B for transferring of substrates into and out of the cluster tool  100  and a controller  118 . Typically, since the cluster tool  100  is under vacuum, the load lock chambers  106 A,  106 B may “pump down” the substrates introduced into the cluster tool  100 . A first transfer robot  110  may transfer the substrates between the load lock chambers  106 A,  106 B, and a first set of one or more substrate processing chambers  112 ,  114  (2 are shown). Each substrate processing chamber  112 ,  114  can be outfitted to perform a number of substrate processing operations including the physical vapor deposition processes described herein in addition to, atomic layer deposition (ALD), chemical vapor deposition (CVD), pre-clean, thermal process/degas, orientation and other substrate processes. In some embodiments, at least one of the substrate processing chambers  112 ,  114  may be replaced with a cool-down station after the substrate is heated in the thermal treatment apparatus  104  and before returning to an atmospheric environment. In some embodiments, the intermediate transfer chambers  122 ,  124  may include low temperature substrate supports on which a heated substrate is placed to cool down. 
     The first transfer robot  110  can also transfer substrates to/from one or more intermediate transfer chambers  122 ,  124 . The intermediate transfer chambers  122 ,  124  can be used to maintain ultrahigh vacuum conditions while allowing substrates to be transferred within the cluster tool  100 . A second transfer robot  130  can transfer the substrates between the intermediate transfer chambers  122 ,  124  and a second set of one or more substrate processing chambers  132 ,  134 ,  136 , and  138 . Similar to substrate processing chambers  112 ,  114 , the substrate processing chambers  132 ,  134 ,  136 ,  138  can be outfitted to perform a variety of substrate processing operations including the physical vapor deposition processes described herein in addition to atomic layer deposition (ALD), chemical vapor deposition (CVD), pre-clean, thermal process/degas, and orientation, for example. Any of the substrate processing chambers  112 ,  114 ,  132 ,  134 ,  136 ,  138  may be removed from the cluster tool  100  if not necessary for a particular process to be performed by the cluster tool  100 . 
       FIGS. 2 and 3  illustrate a schematic top view and a schematic side view, respectively, of a thermal treatment apparatus  200  according to some embodiments of the present disclosure. The thermal treatment apparatus  200  includes a chamber body  202  including an interior volume  204 , a plurality of substrate supports  206  ( 6  shown in  FIG. 3 ), and a robotic arm  208 . In some embodiments, the plurality of substrate supports  206  are vertically aligned to save space. Each of the plurality of substrate supports  206  has a thickness of about 0.5 inches to about 1.5 inches and may be formed of any suitable material, such as, for example, stainless steel. The specific number of substrate supports  206  depends on the throughput of the cluster tool  100 . 
     The chamber body  202  further includes a selectively sealable opening  212  (e.g., a slit valve) to allow for the transfer of a substrate  210  to/from the thermal treatment apparatus  200 . The robotic arm  208  includes a support arm  220  having a plurality of prongs  214  to support the substrate  210  atop the robotic arm. Each of the plurality of substrate supports  206  includes a plurality of notches  216  that correspond to the plurality of prongs  214  of the robotic arm  208 . 
     Each of the plurality of substrate supports  206  includes a heating element  302  to heat a substrate  210  disposed on the substrate support  206 . An electric box  218  is electrically coupled to the heating element  302  disposed in each of the plurality of substrate supports  206  to provide power to the heating element  302 . The heating element  302  may be any suitable heater, such as a resistive heater or the like, and may comprise a single heating element or a plurality of heating elements disposed in a plurality of independently controlled heater zones. 
     Referring to  FIG. 3 , the support arm  220  of the robotic arm  208  is coupled to a shaft  304 . The shaft  304  is coupled to an actuator  306  at an end opposite the support arm  220  to lift and rotate the robotic arm  208  as desired. 
       FIG. 4  depicts schematic view of the interface between the transfer robot  110  and the support arm  220  according to some embodiments of the present disclosure. In order to facilitate the handoff of the substrate  210  from the transfer robot  110  to the robotic arm  208 , the robotic arm support arm  220  has a shape that interfaces with the transfer robot  110 . The support arm  220  includes a plurality of contact elements  402  to contact a backside of the substrate  210 . The plurality of contact elements  402  are formed of a material that substantially prevents damage to the substrate  210  upon contact. In some embodiments, the plurality of contact elements  402  may be sapphire balls. The transfer robot  110  may similarly have a plurality of contact elements  404 . 
     Returning to  FIG. 3 , the thermal treatment apparatus  200  also includes a heating assembly  308  disposed proximate to the selectively sealable opening  212 . The heating assembly  308  includes a plurality of infrared energy sources  310  disposed above a window  312 . The infrared energy sources  310  may be any suitable infrared energy source, such as a plurality of halogen lamps or the like. The window  312  may be formed of any suitable material, such as, for example, quartz. 
     In operation, the transfer robot  110  extends through the selectively sealable opening  212  to transfer a substrate  210  to the thermal treatment apparatus  200 . The robotic arm  208  receives the substrate  210  from the transfer robot  110 . After the substrate  210  is placed on the robotic arm  208 , the actuator  306  adjusts the height of the support arm  220  to a height corresponding to the desired substrate support  206 . The robotic arm  208  is then rotated so that the support arm  220  with the substrate  210  lies above the desired substrate support  206 . The robotic arm  208  is then lowered so that the prongs  214  pass through the notches  216  allowing the support arm  220  to be lowered below and the substrate  210  to rest on the substrate support  206 . In some embodiments, each of the plurality of substrate supports  206  may include a plurality of contact elements  318  to contact a backside of the substrate  210 . The contact elements  318  may be formed of any suitable material to prevent damage to the substrate  210  upon contact. For example, the contact elements  318  may include sapphire balls. After the substrate  210  has been placed on one of the plurality of substrate supports  206 , the electric box  218  energizes the heating element  302  to heat the substrate  210 . 
     In some embodiments, the thermal treatment apparatus  200  may include a purge gas source  314  to supply purge gas to the interior volume  204  and a vacuum pump  316  to maintain the interior volume at vacuum. The window  312  has a thickness sufficient to ensure that the window  312  does not buckle under the vacuum pressure in the interior volume  204 . For example, the window  312  may have a thickness of about 1 inch. 
       FIG. 5  depicts a flow chart illustrating a method  500  of thermally treating a substrate according to some embodiments of the present disclosure. At  505 , the substrate  210  is inserted into the interior volume  204  of the thermal treatment apparatus  200  using the transfer robot  110 . The substrate  210  may be inserted into the thermal treatment apparatus  200  before processing to perform a degas process and/or after processing to perform an anneal process. The degas process removes moisture from the substrate  210 . The anneal process changes the properties of films deposited on the substrate  210  during processing. At  510 , the substrate  210  is transferred from the transfer robot  110  to the robotic arm  208  disposed in the interior volume  204 . 
     At  515 , the substrate  210  is heated to a first predetermined temperature using the plurality of infrared energy sources  310  disposed above the robotic arm  208 . The substrate  210  is heated to the first predetermined temperature while it rests on the robotic arm  208 . At  520 , the substrate  210  is placed onto one of the plurality of substrate supports  206  after the substrate  210  has reached the first predetermined temperature. At  525 , the substrate  210  is heated to a second predetermined temperature using the heating element  302  disposed in the substrate support  206 . The first and second predetermined temperatures are selected based on the process or processes being performed in the cluster tool  100  and the thermal treatment being performed in the thermal treatment apparatus  200  (i.e., degas or anneal). The first predetermined temperature may be greater than or equal to the second predetermined temperature. In some embodiments, the first and second predetermined temperatures are between about 100° C. to about 500° C. 
     The substrate  210  is preheated by radiation using the plurality of infrared energy sources  310  prior to contacting the substrate support  206  to prevent any deformation of the substrate  210  caused by contacting the high temperature substrate support  206 . The substrate support  206  maintains the substrate  210  at the second predetermined temperature for a predetermined period of time necessary to achieve the desired result of the process being performed in the thermal treatment apparatus  200 . 
     Returning to  FIG. 1 , the controller  118  comprises a central processing unit (CPU), a memory, and support circuits for the CPU and facilitates control of the components of the cluster tool  100  and, as such, of methods of thermally treating a substrate, such as discussed herein. The controller  118  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, or computer-readable medium, of the CPU may be one or more of readily available memory such as random access memory (RAM), read only memory (ROM), floppy disk, hard disk, or any other form of digital storage, local or remote. The support circuits are coupled to the CPU for supporting the processor in a conventional manner. These circuits include cache, power supplies, clock circuits, input/output circuitry and subsystems, and the like. The memory stores software (source or object code) that may be executed or invoked to control the operation of the cluster tool  100  in the manner described above. The software routine may also be stored and/or executed by a second CPU (not shown) that is remotely located from the hardware being controlled by the CPU. 
     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.