Patent Publication Number: US-10312129-B2

Title: Variable adjustment for precise matching of multiple chamber cavity housings

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a divisional of and claims the right of priority based on U.S. application Ser. No. 15/050,159, entitled “VARIABLE ADJUSTMENT FOR PRECISE MATCHING OF MULTIPLE CHAMBER CAVITY HOUSINGS,” and filed on Feb. 22, 2016, which claims the benefit of U.S. Provisional Application No. 62/234,532, entitled “VARIABLE ADJUSTMENT FOR PRECISE MATCHING OF MULTIPLE CHAMBER CAVITY HOUSINGS,” and filed Sep. 29, 2015, the contents of which are incorporated herein by reference to the extent such contents do not conflict with the present disclosure. 
    
    
     FIELD OF INVENTION 
     The invention relates to a multiple-chambered reaction system for processing semiconductor substrates. Specifically, the invention relates to a vertical adjustment component of the reaction system to allow for precise matching of wafer processes within different chambers. 
     BACKGROUND OF THE DISCLOSURE 
     Assemblies in reaction chambers generally may allow for lateral adjustment and leveling of a wafer lift mechanism. A wafer is disposed on a wafer holder, which may have a heating element. The lateral adjustment allows for horizontal centering of a wafer within the reaction chamber. The lateral adjustment takes place by using independent x-y adjustment block assemblies. For systems with multiple reaction chambers, the lateral adjustment is duplicated for each reaction chamber to center and level the wafer holder. 
     With respect to leveling of the wafer lift mechanism, leveling ensures that a wafer disposed on the wafer lift mechanism is as flat as possible and parallel to a showerhead disposed above the wafer. The leveling is accomplished through a tripod leveling system. The tripod leveling system includes a three point leveling system with ports to impart pressure onto the wafer to allow for a desired flat position of the wafer. The heater is leveled by the tripod (3-point adjustment) and the tripod is ‘carried’ by the lateral adjusting plate so that centering can be accomplished after leveling. This is due to the fact that leveling will change the position of the heater platen relative to the chamber circular bore. These systems usually have an individual wafer lift mechanisms for each reaction chamber. 
     Reaction systems exist with multiple chambers to allow for different processing steps. For some of these systems, each chamber may have its own wafer lift mechanism. However, multiple individual wafer lift mechanisms have a disadvantage as each individual lift mechanism incurs significant capital costs. In addition, the cost may rise due to maintenance of each individual wafer lift mechanism. Individual lifts have the following additional disadvantages: (1) More complex software checks are required for motion to occur, slowing throughput; (2) Imprecise motion matching due to manufacturing variances and tolerance stack-ups; (3) Component stack-up due to multiple identical parts requirements and the supporting cables/hoses required for actuation; (4) Multiplied opportunities for sensor failure with a lack of system redundancy (a ‘master’ lift assembly can have multiple redundant sensors if needed and can be easily recovered from a motion sensor error); and (5) Longer system down-time during maintenance due to repetitive setups being required for each chamber and its motion system. 
     Furthermore, certain applications may require a chamber to be split into separate sections or cavities. While it may be possible to have individual wafer lift mechanisms for each cavity, the cost issues described above and potential spacing issues may not make this feasible. Prior approaches to this issue have utilized a series of tunnels and gas distribution systems to raise separate wafer holders. Other approaches include certain ‘carousel’ systems that have been used in Physical Vapor Deposition (PVD) ‘sputtering’ applications with satisfactory results. These same methods were not as suited for Chemical Vapor Deposition (CVD) and its variant methods including Plasma-enhanced CVD (PECVD) and Atomic Layer Deposition (ALD). These last systems have been the driving force for multiple-wafer processing in matched-chamber environments to regain the throughput lost to PVD systems. 
     In addition, for multiple cavity systems, another issue with multiple individual wafer lift mechanisms is the reproducibility of reaction conditions. In certain applications, precise chamber matching may be required to allow for process duplication between different cavities. Merely disposing two wafer holders for two cavities on a single wafer lift mechanism may be insufficient because discrepancies with the vertical positions of the two wafer holders may exist as a result of a tolerance stack-up. 
     A tolerance stack-up is known in the art as an aggregation of mechanical variances within dimensions of various parts within an assembly, resulting in a minimum and maximum value range of variations. An aggregate variation can be great enough to affect the reproducibility of conditions within different cavities. This could potentially lead to defects in manufacturing, as well as decreased chamber life due to deposition material ‘leakage’ into non-process regions of the chamber. As a result, a need exists for a system that allows for the matching of vertical positions in multiple separate cavities of a reaction chamber. 
     SUMMARY OF THE DISCLOSURE 
     In accordance with at least one embodiment of the invention, a system is disclosed that comprises: a reference bar that is configured to have a fixed position relative to a horizontal bar; a moveable tie bar configured to move in a vertical position relative to the reference bar; a first movable block coupled to the movable tie bar; a first set of sliding brackets; a first susceptor; a set of rails; and a jacking screw mounted within the reference bar and the movable tie bar, wherein a rotation of the jacking screw causes a vertical movement of the first susceptor. 
     In accordance with at least one embodiment of the invention, a reaction system is disclosed that comprises: a first chamber cavity; a second chamber cavity; a first susceptor in the first chamber cavity; a second susceptor in the second chamber cavity; a main lift assembly that comprises: a main lift drive; a horizontal bar; a first baseplate; and a second baseplate; and a slave vertical lift assembly comprising: a reference bar; a movable tie bar; a first set of movable blocks; a first set of sliding brackets; a set of rails; and a jacking screw. 
     In accordance with at least one embodiment of the invention, a method is disclosed that comprises: providing a first chamber cavity for processing a first substrate and a second chamber cavity for processing a second substrate; operating a main lift driver as part of a primary lift assembly to vertically move a first susceptor in the first chamber cavity and to vertically move a second susceptor in the second chamber cavity, the first susceptor configured to hold the first substrate and the second susceptor configured to hold the second substrate; and rotating a jacking screw as part of a secondary lift assembly to match a vertical position of the second substrate with a vertical position of the first substrate. 
     For purposes of summarizing the invention and the advantages achieved over the prior art, certain objects and advantages of the invention have been described herein above. Of course, it is to be understood that not necessarily all such objects or advantages may be achieved in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught or suggested herein without necessarily achieving other objects or advantages as may be taught or suggested herein. 
     All of these embodiments are intended to be within the scope of the invention herein disclosed. These and other embodiments will become readily apparent to those skilled in the art from the following detailed description of certain embodiments having reference to the attached figures, the invention not being limited to any particular embodiment(s) disclosed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
       These and other features, aspects, and advantages of the invention disclosed herein are described below with reference to the drawings of certain embodiments, which are intended to illustrate and not to limit the invention. 
         FIG. 1  illustrates a side view of reaction system according to at least one embodiment of the invention. 
         FIG. 2  illustrates a side view of a lift mechanism according to at least one embodiment of the invention. 
         FIG. 3  illustrates an angled view of an adjuster assembly according to at least one embodiment of the invention. 
         FIG. 4  illustrates a side view of the adjuster assembly according to at least one embodiment of the invention. 
         FIG. 5  illustrates a bottom view of the adjuster assembly according to at least one embodiment of the invention. 
         FIG. 6  illustrates a top view of the adjuster assembly according to at least one embodiment of the invention. 
         FIG. 7  illustrates a back view of the adjuster assembly according to at least one embodiment of the invention. 
         FIG. 8  illustrates a cross-sectional view of the adjuster assembly according to at least one embodiment of the invention. 
         FIG. 9  illustrates a side view of the reaction system according to at least one embodiment of the invention. 
         FIG. 10  illustrates a side view of the reaction system according to at least one embodiment of the invention. 
     
    
    
     It will be appreciated that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of illustrated embodiments of the present disclosure. 
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Although certain embodiments and examples are disclosed below, it will be understood by those in the art that the invention extends beyond the specifically disclosed embodiments and/or uses of the invention and obvious modifications and equivalents thereof Thus, it is intended that the scope of the invention disclosed should not be limited by the particular disclosed embodiments described below. 
       FIG. 1  illustrates a reaction system  10  according to at least one embodiment of the invention. The reaction system  10  includes a first reaction cavity  15  and a second reaction cavity  20 . The first reaction cavity  15  and the second reaction cavity  20  may comprise of separate chambers or of a single chamber with a divider. The first reaction cavity  15  and the second reaction cavity  20  each comprise an upper portion  25  and a lower portion  30 . 
     Substrate S 1 , S 2  may be loaded onto a susceptor  35  when the susceptor  35  is positioned in the lower portion  30 . The susceptor  35  also includes a susceptor heater  40  and a susceptor heater shaft  45 . According to another embodiment of the invention, the susceptor  35 , heater  40 , and the susceptor heater shaft  45  may be of a single piece design and is interchangeable with the multi-piece design illustrated. The susceptor  35  may have alignment tools to allow for accurate positioning of the substrates S 1 , S 2 . The substrates S 1 , S 2  may then be processed, when the susceptor  35  is positioned in the upper portion  25 . A reaction cavity housing  50  may comprise of several different sections in order to provide a substantially closed environment for the processing of substrates S 1 , S 2 . 
     Movement of the substrates S 1 , S 2  and the susceptor  35  is due in part to a vertical lift assembly  55 . The vertical lift assembly  55  comprises a main lift driver  60  configured to move a horizontal bar  65  up and down in a direction  70 . The main lift driver  60  may comprise a motor having position feedback via an encoder, hall-effect sensors, or a combination thereof. Attached to the horizontal bar  65  via a set of brackets  75  is a bottom plate  80 . The bottom plate  80  is configured to hold a bellows mounting plate  85 , upon which a bellows  90  is mounted. The bellows  90  expands and contracts depending upon a position of the susceptor  35  while maintaining isolation of external atmosphere and internal vacuum within the chamber. 
       FIG. 2  illustrates a vertical lift assembly  100  according to at least one embodiment of the invention. The vertical lift assembly  100  includes a main lift driver  105 , which is connected to a horizontal bar  110 . The horizontal bar  110  is mounted to a pair of horizontal sliding blocks  115 . The horizontal sliding blocks  115  move up and down a pair of guide rails  120 . A pair of support bars  125  provides guidance of the horizontal sliding blocks  115  in the up and down movement and serves as a hard-stop to limit vertical upward travel. A plate cap  130  attaches the vertical lift assembly  100  to the bottom of the chamber. 
     The vertical lift assembly  100  includes a master lift component  150  and a slave lift component  200 . Both the master lift component  150  and the slave lift component  200  are connected to the horizontal bar  110 . The master lift component  150  comprises a set of brackets  155 , a susceptor heater shaft  160 , and a rigid-mounted bottom plate  165 . On top of the bottom plate  165  is disposed a bellows mounting plate  170 . A bellows  175  is connected to the bellows mounting plate  170 . At the top of the bellows  175  is a mounting plate  180 , which connects to a bottom of a reaction chamber. 
     Disposed on top of the bellows mounting plate  170  are a set of adjusting micrometers  185 . The adjusting micrometers  185  provide for minor height changes of the bellows mounting plate  170  to allow for three-point leveling of the bellows mounting plate  170  and the susceptor mounted to the leveling plate. According to one embodiment of the invention, three adjusting micrometers  185  may be used to accomplish a three-point leveling. In another embodiment of the invention, two adjusting micrometers  185  may be used. Three-point leveling may still be accomplished with two adjusting micrometers  185  if the point without the adjusting micrometer is used as a fixed reference point. 
     Disposed below the bottom plate  165  are a set of clamps  190 . The set of clamps  190  are responsible for maintaining the level adjustment and centering adjustment once it is established. A set of mirrored adjusters  195  are responsible for x-y lateral adjustment of the bellows mounting plate  170 . It is preferred that a clamp  190  exists for each mirrored adjuster  195  as well and each fixed point. Within the bellows mounting plate  170 , a heater may be installed in order to provide heat to the susceptor through the susceptor heater shaft  160 . 
     The slave lift component  200  shares a number of similarities as the main lift component  150 . The slave lift component  200  comprises in part an adjustable bottom plate  210 . On top of the bottom plate  210  is disposed a bellows mounting plate  215 . A bellows  220  is connected to the bellows mounting plate  215 . At the top of the bellows  215  is a mounting plate  225 , which connects to a bottom of a reaction chamber. 
     Disposed on top of the bellows mounting plate  215  are a set of adjusting micrometers  230 . The adjusting micrometers  230  provide for minor height changes of the bellows mounting plate  215  to allow for three-point leveling of the bellows mounting plate  215 . According to one embodiment of the invention, three adjusting micrometers  230  may be used to accomplish a three-point leveling. In another embodiment of the invention, two adjusting micrometers  230  may be used. Three-point leveling may still be accomplished with two adjusting micrometers  230  if the point without the adjusting micrometer is used as a fixed reference point. 
     Disposed below the bottom plate  205  are a set of clamps  235 . The set of clamps  235  are responsible for maintaining the level adjustment and centering adjustment once it is established. A set of adjusters  240  are responsible for x-y adjustment of the bottom plate  210  and the bellows mounting plate  215 . As with clamps  190 , it is preferred that a clamp  235  exists for each mirrored adjuster  240  as well and each fixed point. 
     Within the bellows mounting plate  215 , a heater may be installed in order to provide heat to the susceptor through the susceptor heater shaft  205 . A set of cooling tubes  245  may be attached to the bellows mounting plate  170  and the bellows mounting plate  215  to prevent overheating of the vacuum-to-atmosphere seal. 
     The slave lift portion  200  differs from the main lift portion  150  by including additional components. The slave lift portion  200  also comprises a movable bracket  255 , a movable tie bar  260 , a reference bar  265 , and a jacking screw  270 . As will be explained in further detail, movement of the jacking screw  270  will cause movement of the moveable tie bar  260  and the movable bracket  255 , resulting in a vertical adjustment of the susceptor rod  205  and a substrate on top of a susceptor. 
       FIG. 3  illustrates an angled view of the slave lift portion  250  according to at least one embodiment of the invention. A set of movable brackets  255  are attached to a bottom plate  210  (not illustrated, but explained with respect to  FIG. 2 ). The set of movable brackets  255  are also connected to a movable tie bar  260 . A fixed tie bar  275  and a set of mounting brackets  275 ′ do not move with respect to the horizontal bar  110  as the fixed tie bar  275  is connected to the horizontal bar. Attached to the fixed tie bar  275  is a set of rails  280 . Along these rails, a set of sliding blocks  285  moves up and down. The set of sliding blocks  285  is attached to the set of movable brackets  255  and the movable tie bar  260 . 
       FIG. 4  is a front view of the slave lift portion  250  according to at least one embodiment of the invention. The set of movable brackets  255  is mounted to the set of sliding blocks  285  with a mounting screw  290 . Movement of the jacking screw  270  will cause the movable tie bar  260  to move, resulting in causing the set of sliding blocks  285  and the movable brackets  255  to move, while the horizontal bar  110 , the fixed tie bar  275  and mounting brackets  275 ′, and the reference bar  265  stay in place. Screws  295  provide locking force to prevent movement after final adjustment and must be loosened prior to any vertical adjustments of the slave assembly. 
       FIG. 5  is a top view of the slave lift portion  250  according to at least one embodiment of the invention. The interlocking of the rails  280  and the sliding blocks  285  is such that the movable brackets  255  and the movable tie bar  260  are capable of easily sliding up and down with precise movements. 
       FIG. 6  is a bottom view of the slave lift portion  250  according to at least one embodiment of the invention. A set of screws  295 ′ may be used to connect the reference bar  265  to the horizontal bar  110  to provide the thrusting surface required to raise or lower the slave assembly. The screws  295 ′ may comprise threaded screws, although other fastening devices may be used. As previously mentioned, turning of the jacking screw  270  may allow for movement of the movable tie bar  260  and the sliding blocks  285 . This in turn will cause the movable brackets  255  and a substrate located on a susceptor to move upwards or downwards. 
       FIG. 7  illustrates a back view of the slave lift portion  250  according to at least one embodiment of the invention. The horizontal bar  110  is connected to the fixed tie bar  275 , and has an opening to view the movable tie bar  260 . Position of the movable tie bar  260  can be viewed through the opening of the horizontal bar  110  depending upon the turning of the jacking screw  270 . A U-shaped opening  305  also serves as the upper motion limit of the slave assembly. An upper ‘notched’ cut-out in the horizontal bar  110  serves as a lower hard stop. The combination of these features controls absolute positioning relative to the master susceptor position. 
       FIG. 8  illustrates a cross sectional view of the slave lift portion  250  from  FIG. 4 . The jacking screw  270  interfaces with the reference bar  265  and the movable tie bar  260  through several components. The jacking screw  270  is configured to be held in place within the reference bar  265  by a lower threaded nut  310  and an upper threaded nut  315 . These nuts  310 ,  315  set the tension for the thrust bearing and are locked into place to prevent going out of adjustment. An upper thrust bearing race  320 , a lower thrust bearing race  325 , and a thrust bearing roller and cage  330  allow for force to be applied relative to capture faces in the reference bar  265 . A helicoil thread insert  340  may be configured to prevent galling of the threads of the screw under load. Depending upon the direction the force is applied, the z-axis adjuster moves up or down along a direction  335 . For example, force exerted against the lower thrust race  325  is accomplished by turning the jacking screw  270  counter clockwise, which in-turn causes the movable tie bar  260  to travel upward. Once the position is set, locking screws  295  prevent undesired vertical movement of the slave assembly relative to the master, ensuring consistent and synchronous vertical position of both susceptors and substrates. 
     Likewise an opposite motion will result in the movement of the movable tie bar  260  along an opposite direction  325 . The rotation of the jacking screw  270  may take place via an operator or potentially a programmable robot or potentially a miniature pneumatic linear or rotary actuator. 
       FIG. 9  illustrates a reaction system  400  in accordance with at least one embodiment of the invention.  FIG. 9  is similar to the reaction system illustrated in  FIG. 1 , but shows a susceptor and substrate in a different position. The reaction system  400  comprises a first chamber cavity  405  and a second chamber cavity  410 , in which substrates can be processed. A reaction cavity housing  415  may comprise of several different sections in order to provide a substantially closed environment for the processing of the substrates. 
     Within the first chamber cavity  405 , a first substrate S 1  is brought upward into a processing position by a first susceptor  420 . The first susceptor  420  may also include a first susceptor heater  425 . The processing position is defined in part by a first baseplate  430  that juts from the reaction cavity housing  415 . The first substrate S 1  being in an up position is evidenced by a contraction of a first bellow  435 . The first bellow  435  is mounted upon a first bellow mounting plate  440 , which is disposed on a first lower plate  445 . The first lower plate  445  is mounted on a horizontal bar  450 . Movement of the horizontal bar  450  is driven by a main lift driver  455 . 
     Within the second chamber cavity  410 , a second substrate S 2  is brought upward into a processing position by a second susceptor  460 . The second susceptor  460  may also include a second susceptor heater  465 . The processing position within the second chamber cavity  410  is defined in part by a second baseplate  470  that juts from the reaction cavity housing  415 . The second substrate S 2  being in an up position is evidenced by a contraction of a second bellow  475 . The second bellow  475  is mounted upon a second bellow mounting plate  480 , which is disposed on a second lower plate  485 . The second lower plate  485  is mounted on the horizontal bar  450 . On the side of the horizontal bar  450  associated with the second susceptor  460  is also installed a vertical lift assembly  500 , similar to the embodiments discussed above. The vertical lift assembly includes in part a jacking screw  505 . 
     As shown in  FIG. 9 , there is a small discrepancy  510  in the vertical positions of the first substrate S 1  and the second substrate S 2 . The discrepancy  510  can result as a result of a tolerance stack-up error. An aggregate variation within components of the reaction system  400  can be great enough to affect the reproducibility of conditions within the first reaction cavity  405  and the second reaction cavity  410 . As previously stated, inability to reproduce conditions accurately could potentially lead to defects in manufacturing, as well as decreased chamber life due to deposition material ‘leakage’ into non-process regions of the chamber. 
       FIG. 10  illustrates a reaction system  400  in accordance with at least one embodiment of the invention. The small discrepancy  510  shown in  FIG. 9  can be eliminated by turning the jacking screw  505 . Turning the jacking screw  505  in a direction  515  will move the second susceptor  460  and the second substrate S 2  upward in a direction  520 . As a result, the vertical positions of the first substrate S 1  and the second substrate S 2  will be matched, allowing a reproduction of conditions within the first chamber cavity  405  and the second chamber cavity  410 . 
     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, the 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. 
     It is to be understood that the configurations and/or approaches described herein are exemplary in nature, and that these specific embodiments or examples are not to be considered in a limiting sense, because numerous variations are possible. The specific routines or methods described herein may represent one or more of any number of processing strategies. Thus, the various acts illustrated may be performed in the sequence illustrated, in other sequences, or omitted in some cases. 
     The subject matter of the present disclosure includes all novel and nonobvious combinations and subcombinations of the various processes, systems, and configurations, and other features, functions, acts, and/or properties disclosed herein, as well as any and all equivalents thereof.