Abstract:
Apparatus and methods for aligning large susceptors in batch processing chambers are described. Apparatus and methods for controlling the parallelism of a susceptor relative to a gas distribution assembly are also described.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The application claims priority to U.S. Provisional Application No. 62/171,968, filed Jun. 5, 2015, the entire disclosure of which is incorporated by reference herein. 
     
    
     TECHNICAL FIELD 
       [0002]    The present disclosure relates generally to apparatus and methods for positioning and/or rotating a susceptor assembly. More specifically, embodiments of the disclosure are directed to apparatus and methods for moving a batch processing susceptor assembly in multiple axes. 
       BACKGROUND 
       [0003]    Some batch processing chambers have relatively large diameter susceptors (1 m or more) to hold a sufficient number of wafers for processing. The susceptor is rotated in close proximity (3 mm-0.5 mm) to the injector plate which is another large diameter disc-like component. The parallelism between these components is tuned to control the deposition process. Currently, these components are positioned manually, which takes about three hours. The parallelism changes with respect to the susceptor temperature and chamber pressure. Accordingly, there is a need for apparatus and methods to align and control parallelism to meet the tight clearances and impact of changing process parameters. 
       SUMMARY 
       [0004]    One or more embodiments of the disclosure are directed to susceptor assemblies comprising a shaft that can support a susceptor and a positioning system. The positioning system comprises a bottom plate, a top plate and at least three actuators positioned between and in contact with the bottom plate and the top plate. Each of the actuators has a body and a rod with a rod end positioned within the body. Each rod is slidably movable along an axis of the body to move the top plate closer to or further from the bottom plate. 
         [0005]    Additional embodiments of the disclosure are directed to processing chambers comprising a vacuum chamber having a bottom with an opening therethrough. A susceptor assembly comprises a shaft that can support a susceptor and a positioning system. The positioning system comprises a bottom plate, a top plate and at least three actuators positioned between and in contact with the bottom plate and the top plate. Each of the actuators has a body and a rod with a rod end positioned within the body. Each rod is slidably movable along an axis of the body to move the top plate closer to or further from the bottom plate. The susceptor assembly is positioned so that the shaft extends through the opening in the bottom of the vacuum chamber. A susceptor is connected to a top of the shaft within the vacuum chamber. 
         [0006]    Additional embodiments of the disclosure are directed to processing chambers comprising a vacuum chamber with a bottom with an opening therethrough. A shaft extends through the opening and supports a susceptor within the vacuum chamber. A bearing assembly includes a spherical roller bearing positioned around the shaft to form a seal between the shaft and the vacuum chamber. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    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 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. 
           [0008]      FIG. 1  shows a cross-sectional view of a batch processing chamber in accordance with one or more embodiment of the disclosure; 
           [0009]      FIG. 2  shows a partial perspective view of a batch processing chamber in accordance with one or more embodiment of the disclosure; 
           [0010]      FIG. 3  shows a schematic view of a batch processing chamber in accordance with one or more embodiment of the disclosure; 
           [0011]      FIG. 4  shows a schematic view of a portion of a wedge shaped gas distribution assembly for use in a batch processing chamber in accordance with one or more embodiment of the disclosure; 
           [0012]      FIG. 5  shows a schematic view of a batch processing chamber in accordance with one or more embodiment of the disclosure; 
           [0013]      FIG. 6  shows a partial perspective view of a batch processing chamber in accordance with one or more embodiment of the disclosure; 
           [0014]      FIG. 7  shows a perspective view of a v-block for use with one or more embodiments of the disclosure; 
           [0015]      FIGS. 8A and 8B  show linear actuators with spherical rod ends in accordance with one or more embodiment of the disclosure; 
           [0016]      FIG. 9  shows a partial perspective view of a batch processing chamber in accordance with one or more embodiment of the disclosure; 
           [0017]      FIG. 10  shows a partial perspective view of a batch processing chamber in accordance with one or more embodiment of the disclosure; 
           [0018]      FIG. 11  shows a partial cross-sectional view of a spherical bearing assembly in accordance with one or more embodiment of the disclosure; 
           [0019]      FIGS. 12A and 12B  show partial cross-sectional views of a spherical bearing assembly in use in accordance with one or more embodiment of the disclosure; and 
           [0020]      FIG. 13  shows a partial cross-sectional view of a spherical bearing in accordance with one or more embodiment of the disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    Before describing several exemplary embodiments of the disclosure, it is to be understood that the disclosure is not limited to the details of construction or process steps set forth in the following description. The disclosure is capable of other embodiments and of being practiced or being carried out in various ways. The embodiments described and illustrations are intended as examples only and are not to be construed as limiting the disclosed apparatus or method. 
         [0022]    A “substrate” as used herein, refers to any substrate or material surface formed on a substrate upon which film processing is performed during a fabrication process. For example, a substrate surface on which processing can be performed include materials such as silicon, silicon oxide, strained silicon, silicon on insulator (SOI), carbon doped silicon oxides, silicon nitride, doped silicon, germanium, gallium arsenide, glass, sapphire, and any other materials such as metals, metal nitrides, metal alloys, and other conductive materials, depending on the application. Substrates include, without limitation, semiconductor wafers. Substrates may be exposed to a pretreatment process to polish, etch, reduce, oxidize, hydroxylate, anneal and/or bake the substrate surface. In addition to film processing directly on the surface of the substrate itself, in the present disclosure, any of the film processing steps disclosed may also be performed on an underlayer formed on the substrate as disclosed in more detail below, and the term “substrate surface” is intended to include such underlayer as the context indicates. Thus for example, where a film/layer or partial film/layer has been deposited onto a substrate surface, the exposed surface of the newly deposited film/layer becomes the substrate surface. 
         [0023]    According to one or more embodiments, the apparatus and methods can be used with an atomic layer deposition (ALD) process. In such embodiments, the substrate surface is exposed to the precursors (or reactive gases) sequentially or substantially sequentially. As used herein throughout the specification, “substantially sequentially” means that a majority of the duration of a precursor exposure does not overlap with the exposure to a co-reagent, although there may be some overlap. As used in this specification and the appended claims, the terms “precursor”, “reactant”, “reactive gas” and the like are used interchangeably to refer to any gaseous species that can react with the substrate surface. 
         [0024]    The various embodiments described can be employed with any type of system in which multi-axis motion is used. For descriptive purposes, embodiments are shown in use with a spatial ALD batch processing chamber. Those skilled in the art will understand that the apparatus and methods may be adapted for use in other environments or with other processing chambers. For example, a time-domain ALD processing chamber, a chemical vapor deposition chamber. 
         [0025]      FIG. 1  shows a cross-section of a batch processing chamber  100  including a gas distribution assembly  120 , also referred to as injectors or an injector assembly, and a susceptor assembly  140 . The gas distribution assembly  120  is any type of gas delivery device used in a processing chamber. The gas distribution assembly  120  includes a front surface  121  which faces the susceptor assembly  140 . The front surface  121  can have any number or variety of openings to deliver a flow of gases toward the susceptor assembly  140 . The gas distribution assembly  120  also includes an outer edge  124  which in the embodiments shown, is substantially round. 
         [0026]    The specific type of gas distribution assembly  120  used can vary depending on the particular process being used. Embodiments of the disclosure can be used with any type of processing system where the gap between the susceptor and the gas distribution assembly is controlled. In a binary reaction, the plurality of gas channels can include at least one first reactive gas A channel, at least one second reactive gas B channel, at least one purge gas P channel and/or at least one vacuum V channel. The gases flowing from the first reactive gas A channel(s), the second reactive gas B channel(s) and the purge gas P channel(s) are directed toward the top surface of the wafer. Some of the gas flow moves horizontally across the surface of the wafer and out of the processing region through the purge gas P channel(s). 
         [0027]    In some embodiments, the gas distribution assembly  120  is a rigid stationary body made of a single injector unit. In one or more embodiments, the gas distribution assembly  120  is made up of a plurality of individual sectors (e.g., injector units  122 ), as shown in  FIG. 2 . Either a single piece body or a multi-sector body can be used with the various embodiments of the disclosure described. 
         [0028]    The susceptor assembly  140  is positioned beneath the gas distribution assembly  120 . The susceptor assembly  140  includes a top surface  141  and at least one recess  142  in the top surface  141 . The susceptor assembly  140  also has a bottom surface  143  and an edge  144 . The recess  142  can be any suitable shape and size depending on the shape and size of the substrates  60  being processed. In the embodiment shown in  FIG. 1 , the recess  142  has a flat bottom to support the bottom of the wafer; however, the bottom of the recess can vary. In some embodiments, the recess has step regions around the outer peripheral edge of the recess which are sized to support the outer peripheral edge of the wafer. The amount of the outer peripheral edge of the wafer that is supported by the steps can vary depending on, for example, the thickness of the wafer and the presence of features already present on the back side of the wafer. 
         [0029]    In some embodiments, as shown in  FIG. 1 , the recess  142  in the top surface  141  of the susceptor assembly  140  is sized so that a substrate  60  supported in the recess  142  has a top surface  61  substantially coplanar with the top surface  141  of the susceptor  140 . As used in this specification and the appended claims, the term “substantially coplanar” means that the top surface of the wafer and the top surface of the susceptor assembly are coplanar within ±0.5 mm, ±0.4 mm, ±0.3 mm, ±0.25 mm, ±0.2 mm, ±0.15 mm, ±0.10 mm or ±0.05 mm. 
         [0030]    The susceptor assembly  140  of  FIG. 1  includes a shaft  160  which is capable of lifting, lowering and rotating the susceptor assembly  140 . The susceptor assembly may include a heater, or gas lines, or electrical components within the center of the shaft  160 . The shaft  160  may be the primary means of increasing or decreasing the gap between the susceptor assembly  140  and the gas distribution assembly  120 , moving the susceptor assembly  140  into proper position. The susceptor assembly  140  may also include fine tuning actuators  162  which can make micro-adjustments to susceptor assembly  140  to create a predetermined gap  170  between the susceptor assembly  140  and the gas distribution assembly  120 . In some embodiments, the gap  170  distance is in the range of about 0.1 mm to about 5.0 mm, or in the range of about 0.1 mm to about 3.0 mm, or in the range of about 0.1 mm to about 2.0 mm, or in the range of about 0.2 mm to about 1.8 mm, or in the range of about 0.3 mm to about 1.7 mm, or in the range of about 0.4 mm to about 1.6 mm, or in the range of about 0.5 mm to about 1.5 mm, or in the range of about 0.6 mm to about 1.4 mm, or in the range of about 0.7 mm to about 1.3 mm, or in the range of about 0.8 mm to about 1.2 mm, or in the range of about 0.9 mm to about 1.1 mm, or about 1 mm. 
         [0031]    The processing chamber  100  shown in the Figures is a carousel-type chamber in which the susceptor assembly  140  can hold a plurality of substrates  60 . As shown in  FIG. 2 , the gas distribution assembly  120  may include a plurality of separate injector units  122 , each injector unit  122  being capable of depositing a film on the wafer, as the wafer is moved beneath the injector unit. Two pie-shaped injector units  122  are shown positioned on approximately opposite sides of and above the susceptor assembly  140 . This number of injector units  122  is shown for illustrative purposes only. It will be understood that more or less injector units  122  can be included. In some embodiments, there are a sufficient number of pie-shaped injector units  122  to form a shape conforming to the shape of the susceptor assembly  140 . In some embodiments, each of the individual pie-shaped injector units  122  may be independently moved, removed and/or replaced without affecting any of the other injector units  122 . For example, one segment may be raised to permit a robot to access the region between the susceptor assembly  140  and gas distribution assembly  120  to load/unload substrates  60 . 
         [0032]    Processing chambers having multiple gas injectors can be used to process multiple wafers simultaneously so that the wafers experience the same process flow. For example, as shown in  FIG. 3 , the processing chamber  100  has four gas injector assemblies and four substrates  60 . At the outset of processing, the substrates  60  can be positioned between the injector assemblies  30 . Rotating  17  the susceptor assembly  140  by 45° will result in each substrate  60  which is between gas distribution assemblies  120  to be moved to a gas distribution assembly  120  for film deposition, as illustrated by the dotted circle under the gas distribution assemblies  120 . An additional 45° rotation would move the substrates  60  away from the injector assemblies  30 . With spatial ALD injectors, a film is deposited on the wafer during movement of the wafer relative to the injector assembly. In some embodiments, the susceptor assembly  140  is rotated in increments that prevent the substrates  60  from stopping beneath the gas distribution assemblies  120 . The number of substrates  60  and gas distribution assemblies  120  can be the same or different. In some embodiments, there is the same number of wafers being processed as there are gas distribution assemblies. In one or more embodiments, the number of wafers being processed are fraction of or an integer multiple of the number of gas distribution assemblies. For example, if there are four gas distribution assemblies, there are 4x wafers being processed, where x is an integer value greater than or equal to one. 
         [0033]    The processing chamber  100  shown in  FIG. 3  is merely representative of one possible configuration and should not be taken as limiting the scope of the disclosure. Here, the processing chamber  100  includes a plurality of gas distribution assemblies  120 . In the embodiment shown, there are four gas distribution assemblies (also called injector assemblies  30 ) evenly spaced about the processing chamber  100 . The processing chamber  100  shown is octagonal, however, those skilled in the art will understand that this is one possible shape and should not be taken as limiting the scope of the disclosure. The gas distribution assemblies  120  shown are trapezoidal, but can be a single circular component or made up of a plurality of pie-shaped segments, like that shown in  FIG. 2 . 
         [0034]    The embodiment shown in  FIG. 3  includes a load lock chamber  180 , or an auxiliary chamber like a buffer station. This chamber  180  is connected to a side of the processing chamber  100  to allow, for example the substrates (also referred to as substrates  60 ) to be loaded/unloaded from the chamber  100 . A wafer robot may be positioned in the chamber  180  to move the substrate onto the susceptor. 
         [0035]    Rotation of the carousel (e.g., the susceptor assembly  140 ) can be continuous or discontinuous. In continuous processing, the wafers are constantly rotating so that they are exposed to each of the injectors in turn. In discontinuous processing, the wafers can be moved to the injector region and stopped, and then to the region  84  between the injectors and stopped. For example, the carousel can rotate so that the wafers move from an inter-injector region across the injector (or stop adjacent the injector) and on to the next inter-injector region where the carousel can pause again. Pausing between the injectors may provide time for additional processing steps between each layer deposition (e.g., exposure to plasma). 
         [0036]      FIG. 4  shows a sector or portion of a gas distribution assembly  220 , which may be referred to as an injector unit  122 . The injector units  122  can be used individually or in combination with other injector units. For example, as shown in  FIG. 5 , four of the injector units  122  of  FIG. 4  are combined to form a single gas distribution assembly  220 . (The lines separating the four injector units are not shown for clarity.) While the injector unit  122  of  FIG. 4  has both a first reactive gas port  125  and a second reactive gas port  135  in addition to purge gas ports  155  and vacuum ports  145 , an injector unit  122  does not need all of these components. 
         [0037]    Referring to both  FIGS. 4 and 5 , a gas distribution assembly  220  in accordance with one or more embodiment may comprise a plurality of sectors (or injector units  122 ) with each sector being identical or different. The gas distribution assembly  220  is positioned within the processing chamber and comprises a plurality of elongate gas ports  125 ,  135 ,  155  and vacuum ports  145  in a front surface  121  of the gas distribution assembly  220 . The plurality of elongate gas ports  125 ,  135 ,  155  and vacuum ports  145  extend from an area adjacent the inner peripheral edge  123  toward an area adjacent the outer peripheral edge  124  of the gas distribution assembly  220 . The plurality of gas ports shown include a first reactive gas port  125 , a second reactive gas port  135 , a vacuum port  145  which surrounds each of the first reactive gas ports and the second reactive gas ports and a purge gas port  155 . 
         [0038]    With reference to the embodiments shown in  FIG. 4 or 5 , when stating that the ports extend from at least about an inner peripheral region to at least about an outer peripheral region, however, the ports can extend more than just radially from inner to outer regions. The ports can extend tangentially as vacuum port  145  surrounds reactive gas port  125  and reactive gas port  135 . In the embodiment shown in  FIGS. 4 and 5 , the wedge shaped reactive gas ports  125 ,  135  are surrounded on all edges, including adjacent the inner peripheral region and outer peripheral region, by a vacuum port  145 . 
         [0039]    Referring to  FIG. 4 , as a substrate moves along path  127 , each portion of the substrate surface is exposed to the various reactive gases. To follow the path  127 , the substrate will be exposed to, or “see”, a purge gas port  155 , a vacuum port  145 , a first reactive gas port  125 , a vacuum port  145 , a purge gas port  155 , a vacuum port  145 , a second reactive gas port  135  and a vacuum port  145 . Thus, at the end of the path  127  shown in  FIG. 4 , the substrate has been exposed to gas streams from the first reactive gas port  125  and the second reactive gas port  135  to form a layer. The injector unit  122  shown makes a quarter circle but could be larger or smaller. The gas distribution assembly  220  shown in  FIG. 5  can be considered a combination of four of the injector units  122  of  FIG. 4  connected in series. 
         [0040]    The injector unit  122  of  FIG. 4  shows a gas curtain  150  that separates the reactive gases. The term “gas curtain” is used to describe any combination of gas flows or vacuum that separate reactive gases from mixing. The gas curtain  150  shown in  FIG. 4  comprises the portion of the vacuum port  145  next to the first reactive gas port  125 , the purge gas port  155  in the middle and a portion of the vacuum port  145  next to the second reactive gas port  135 . This combination of gas flow and vacuum can be used to prevent or minimize gas phase reactions of the first reactive gas and the second reactive gas. 
         [0041]    Referring to  FIG. 5 , the combination of gas flows and vacuum from the gas distribution assembly  220  form a separation into a plurality of processing regions  250 . The processing regions are roughly defined around the individual reactive gas ports  125 ,  135  with the gas curtain  150  between  250 . The embodiment shown in  FIG. 5  makes up eight separate processing regions  250  with eight separate gas curtains  150  between. A processing chamber can have at least two processing region. In some embodiments, there are at least three, four, five, six, seven, eight, nine, 10, 11 or 12 processing regions. 
         [0042]    During processing a substrate may be exposed to more than one processing region  250  at any given time. However, the portions that are exposed to the different processing regions will have a gas curtain separating the two. For example, if the leading edge of a substrate enters a processing region including the second reactive gas port  135 , a middle portion of the substrate will be under a gas curtain  150  and the trailing edge of the substrate will be in a processing region including the first reactive gas port  125 . 
         [0043]    A factory interface  280 , which can be, for example, a load lock chamber, is shown connected to the processing chamber  100 . A substrate  60  is shown superimposed over the gas distribution assembly  220  to provide a frame of reference. The substrate  60  may often sit on a susceptor assembly to be held near the front surface  121  of the gas distribution assembly  120  (also referred to as a gas distribution plate). The substrate  60  is loaded via the factory interface  280  into the processing chamber  100  onto a substrate support or susceptor assembly (see  FIG. 3 ). The substrate  60  can be shown positioned within a processing region because the substrate is located adjacent the first reactive gas port  125  and between two gas curtains  150   a,    150   b.  Rotating the substrate  60  along path  127  will move the substrate counter-clockwise around the processing chamber  100 . Thus, the substrate  60  will be exposed to the first processing region  250   a  through the eighth processing region  250   h,  including all processing regions between. For each cycle around the processing chamber, using the gas distribution assembly shown, the substrate  60  will be exposed to four ALD cycles of first reactive gas and second reactive gas. 
         [0044]    A precision linear positioning system with four axes of motion can be used to position the susceptor in close proximity to the gas injector. This can be seen in  FIG. 6 . The position system can be constructed using a bottom plate with three equally spaced linear actuators rigidly mounted perpendicular to the bottom plate surface. Each actuator can provide precision vertical motion and is coupled to the top plate with a 4-degree-of-freedom (4-DOF) joint. In some embodiments, as shown in  FIGS. 8A and 8B , the 4-DOF joint can comprise a spherical rod in bearing attached to a linear bearing. In some embodiments, the 4-DOF joint comprises a kinematic coupling feature (see  FIG. 9 ) that provides pitch, yaw, roll and one linear degree of freedom aligned with the center of the top plate. The rotation access for the susceptor can be integrated to the top plate for processing and adding the fourth axis of motion. In one or more embodiments, the system provides position repeatability to less than 0.005 inches. 
         [0045]      FIG. 6  shows a processing chamber incorporating a susceptor assembly according to one or more embodiment of the disclosure. The susceptor assembly  340  includes a shaft  160  that can support a susceptor  341 . The susceptor  340  is shown as a flat plate but can also include recesses or pockets like those shown in  FIG. 2 . 
         [0046]    Referring back to  FIG. 6 , a positioning system  300  communicates with the shaft  160  to move the susceptor  341 . As used in this regard, the term “communicates” means that at least one of the components is capable of affecting the position of or is in contact, either directly or indirectly, with another component. The positioning system  300  of some embodiments can move the susceptor  341  along the z-axis (i.e., up and down in the Figures), along the x-axis or y-axis to cause the susceptor  341  to tilt relative to the gas distribution assembly  320 . 
         [0047]    The positioning system  300  in  FIG. 6  comprises a bottom plate  301 , a top plate  302  and at least three actuators  310 . Each of the actuators  310  are positioned between and in contact with the bottom plate  301  and the top plate  302 . Each of the actuators  310  has a body  311  and a rod  312  with a rod end  313  movable within the body  311 . Each of the rods  312  are slidably movable within the body so that the length of the rod extending from the body can be varied. Thus, the rods  312  can be moved along an axis of the body  311  to move the top plate  302  closer to or further from the bottom plate  301 . As used herein the movement of the susceptor  341  closer to or further from the gas distribution assembly  320  is referred to as movement along the z-axis. 
         [0048]    The embodiment shown in  FIG. 6  includes v-blocks  316  which each actuator is in contact with.  FIGS. 8A and 8B  show an expanded view of a v-block  316 . The groove  317  in the v-block  316  is aligned radially with respect to the center of the top plate  302 . As used in this regard, the “center” of the top plate  302  means the center of the motion with respect to the actuators and shaft. The shape of the top plate may be concentric about the center or can be irregular. The radial alignment with the center of movement allows the end  313  of the rod  312  to slide along the length defined along the groove  317 , of the v-block toward and away from the center. 
         [0049]    In some embodiments, the v-block  316  further comprises an end plate  318  positioned on either or both ends of the v-block  316 . The v-block  316  can be positioned so that the end plate  318  is at the outer end of the v-block  316  so that movement of the end  313  of the rod  312  cannot extend further from the center than the end plate  318 . 
         [0050]    The embodiment shown in  FIG. 6  is gravity supported so that there is no mechanical connection between the end  313  of the rod  312  and the top plate  302 . In some embodiments, there is a mechanical connection between the bottom plate  301  and the top plate  302 . For example,  FIGS. 8A and 8B  show a mechanically connected system in which each actuator  310  is in contact with a linear bearing  379 .  FIG. 8A  shows a front view of the actuator  310  with rod  312  extending from the top of the body  311 . In the embodiment shown, the rod end  313  has a spherical bearing  374  to connect with a socket  375 . The term “spherical” used in this regard means that the end of the rod has convex sides and does not imply a perfect sphere. The purpose of the convex sides of the spherical bearing  374  is to cooperatively interact with concave portions  376  of the socket  375 . The cooperative interaction of the spherical bearing  374  and socket  375  allow the alignment of the bearing and socket to change angles as the rod  312  moves. The socket  375  has a bracket  377  with a channel  378  therethrough.  FIG. 8B  shows a side view of the actuator of  FIG. 8A . The channel  378  of the bracket  377  can cooperatively interact with a linear bearing  379 . Just like the v-block  316  of  FIG. 6 , the linear bearing  379  can be connected to, or integrally formed with, the top plate  302 . The linear bearing  379  can be aligned radially with respect to the center of movement of the top plate  302 . Movement of the rod  312  will cause the top plate  302  to tilt and the bracket  377  to slide along the length (i.e., the elongate axis) of the linear bearing  379 . Without being bound by any particular theory of operation, it is believed that allowing the rod end  313  to slide along either the v-block  316 , the linear bearing  379 , or other bearing type component, minimizes stress on the components. The bearings of some embodiments allow adequate range of motion and provide positive retention of the supported elements allowing inversion of the elements without disengagement (lifting off the v-blocks). 
         [0051]    The combined motion and position of each actuator provides precision pitch, roll and z motion to position, in this embodiment, the susceptor. The movement can align the susceptor to injector assembly to very tight tolerances depending on the resolution/accuracy of the motion actuators used. In some embodiments, the movement can align the susceptor to injector assembly to less than about 0.05, 0.045, 0.04, 0.035, 0.03, 0.025, 0.02, 0.015, 0.01 or 0.005 inches. The motion provided by the positioning system  300  allows for the integration of a vertical actuator arrangement into the vacuum chamber with either a bellows or lip seal. In conventional systems, the entire actuator shaft moves in multiple directions due to a hinged actuator on the bottom plate making vacuum feedthrough difficult to design. 
         [0052]    Referring again to  FIG. 6 , the positioning system  300  can be located outside of the vacuum chamber  101 . Here, the bottom of the vacuum chamber  101  has an opening  102  therethrough. The shaft  160  passes through the opening  102  and supports a susceptor  341  inside the vacuum chamber  101  and is in communication with, or connected to, the top plate  302  of the positioning system  300 . 
         [0053]    To maintain a gas-tight seal on the vacuum chamber  101 , a bellows  382  may be included. The bellows  382  of  FIG. 6  connects, or contacts, the top plate  302  and the vacuum chamber  101 . Movement of the shaft  160  along the z-axis causes the bellows  382  to expand or contract without breaking the vacuum in the vacuum chamber  101 . While bellows are shown, those skilled in the art will understand that other sealing mechanisms can be employed. For example, lip seals, magnetic couplings or any other method of sealing a linear motion axis in vacuum. 
         [0054]      FIG. 9  shows another embodiment in which the positioning system is located within the vacuum chamber  101 . Here, the shaft  160  extends through the top plate  302  and the bottom plate  301  of the positioning system  300 . The positioning system  300  can be completely located within the vacuum chamber of partially within the vacuum chamber. A bellows  382  is shown below the bottom plate  301  in  FIG. 9  to illustrate that a portion of the system  300  can pass through an opening in the vacuum chamber  101  while maintaining a gas-tight seal. The embodiment shown in  FIG. 9  includes actuator seals  319  below the bottom plate  301 . The actuator seals  319  may provide sufficient space for the movement of the actuators while maintaining a gas-tight seal. 
         [0055]      FIG. 10  shows another embodiment of a precision linear positioning system  400  with four axes of motion which can be used to, for example, position a susceptor in close proximity to a gas injector plate. The system can be constructed using a spherical roller bearing  390  attached to the vacuum chamber  101 . The roller bearing  390  can be a mechanical bearing or air bearing. The roller bearing  390  provides bearing support for rotation about the z-axis, rotation about the x-axis and rotation about the y-axis. A bellows  382 , also referred to as a bellows seal, may be included below the roller bearing  390  to provide a barrier between the process environment and atmosphere while allowing rotation about the x-, y- and z-axes of the rotational lip seal. In some embodiments, a staged vacuum lip seal (not shown) below the bellows provides vacuum isolation barrier for the rotation motion about the z-axis (theta rotation). A rotational motor (also called a theta motor  355 ) may be attached to the frame  410  of the positioning system  400  to integrate with the lip seal and provide a mounting point for the x, y and z stages  420  that support and actuate the load. The frame  410  with the theta motor  355 /lip seal may be attached to an x, y and z stage  420  to provide the precision motion for aligning the susceptor  341  to the injector plate. 
         [0056]    The theta motor  355 , shown in  FIGS. 6, 9 and 10 , rotates the shaft  160  to rotate the susceptor  341 . The theta motor  355  can be any suitable motor that is able to accurately and consistently rotate the heavy components. 
         [0057]    The frame  410  shown in  FIG. 10  includes a top plate  302  and bottom plate  301 . The top and bottom plates are connected by a plurality of support rods  411 . The distance between the top plate  302  and the bottom plate  301  can be any suitable distance depending on the size of components located between. For example, in the embodiment shown in  FIG. 10 , the minimum distance between the top plate  302  and the bottom plate  301  is the amount of space occupied by the theta motor  355 . 
         [0058]    The stage  420  shown is made up of a combination of x-axis motors, y-axis motors and z-axis motors. The x-axis motion may be done using an x-axis track  421  with a slidable platform  422  thereon. The platform  422  can move along the length of the x-axis track  421  to tilt the susceptor. The point at which the shaft  160  passes through the opening  102  in the vacuum chamber  101  acts as a mostly fixed point so that moving the platform  422  causes the susceptor to be pivoted about the opening location. The y-axis motion may be done using a y-axis track  424  with a slidable platform  426  thereon. The platform  426  can move along the length of the y-axis track  424  to tilt the susceptor in an axis perpendicular to the x-axis. The z-axis motion can be done using a z-axis motor  428  connected to an actuator  429  that moves along the z-axis. The actuator  429  can be mechanically connected to the frame  410  using a plate like that shown in  FIG. 10 . In some embodiments, the actuator  429  engages the frame  410  by frictional interaction without mechanical fasteners. The stage  420  can have stacked linear tracks like that shown or other shapes including, but not limited to, arc shaped tracks. The stage  420  can be other types of multi-axis components including, but not limited to, tripod and hexapod. 
         [0059]    One or more embodiments of the disclosure incorporate vacuum isolation and 4-DOF motion of the susceptor. The motions include rotation about the x-axis, rotation about the y-axis, translation in the z-axis and rotation about the z-axis. The stages of some embodiments are positioned capable of handling the load at the bottom of a stack of carriages almost perpendicular to the load. Accordingly, some embodiments provide bearing support, motion and vacuum isolation in a single component that can be easily separated for simple and reliable integration. 
         [0060]    Referring to  FIG. 11 , some embodiments include a bearing assembly  440  between the bellows  382  and the vacuum chamber  101 . The bearing assembly shown includes a lip seal  442  (or staged vacuum), a bellows  382  connected to the lip seal  442  and a connection plate  444  between the bellows  382  and the vacuum chamber  101 . The bearing assembly  440  creates a vacuum seal between the interior of the vacuum chamber  101  and the atmosphere. Region  445  can be under the same pressure as the vacuum chamber  101  or different pressure and may also include a staged vacuum to ensure that any leakage does not impact the vacuum chamber  101 . 
         [0061]    The bearing assembly  440  shown includes a spherical roller bearing  450  positioned around the shaft  160  and forming a seal between the shaft  160  and the vacuum chamber  101 . The spherical roller bearing  450  is positioned at the opening  102  of the vacuum chamber  101 . The spherical roller bearing  450  has two main components; an inner ring  452  and an outer ring  454 . When shaft  160  is rotated about the z-axis, the inner ring  452  rotates as well. The amount of rotation, relative to that of the shaft  160 , can be anywhere from completely stopped (i.e., no rotation) or up to the rotation speed of the shaft depending on the type of inner ring  452 . In some embodiments, the inner ring  452  rotates at the same speed as the shaft  160 . The outer ring  454  remains fixed in place and allows the inner ring  452  to rotate in the x-y plane, that is, about the z-axis. Additionally, the outer ring  454  can allow the inner ring  452  to rotate in the x-z and y-z planes as the susceptor (not shown) is tilted, allowing the shaft  160  to pass through the outer ring  454  in a direction that is not normal to the primary plane of the outer ring  454 .  FIG. 12A  shows a partial view of the spherical roller bearing  450  with the shaft extending normal to the plane of the outer ring  454 .  FIG. 12B  shows a partial view of the spherical roller bearing  450  tilted in the x-z plane so that the shaft  160  is no longer perpendicular to the plane of the outer ring  454 . The cross-hatching is used to delineate the different components and does not necessarily refer to the materials making up the individual components. For example, the inner ring, outer ring and shaft can all be made from aluminum, or each component can be a different material. The outer ring  454  shown is positioned in a gap  456  in the connection plate  444 . The gap  456  can be sized to securely hold the outer ring and prevent or minimize gas leakage between the region  445  and the interior of the vacuum chamber  101 . 
         [0062]    In some embodiments, the lip seal  442  is in a fixed location on the shaft  160  so that the lip seal  442  moves with the shaft  160  along the z-axis when the shaft is raised or lowered. The bellows  382  expands and contracts to maintain the vacuum seal between the bottom of the vacuum chamber  101  and the lip seal  442 . The lip seal  442  allows rotation of the shaft  160  about the z-axis. 
         [0063]      FIG. 13  shows another spherical roller bearing  450  where both the inner ring  452  and outer ring  454  are semicircular instead of planar. Like other spherical roller bearings, the tilt of the inner ring  452  within the outer ring  454  is variable depending on the shape and size of the inner and outer rings. In the embodiment of  FIG. 13 , the amount of tilt that can be applied to the shaft  160  depends on the size of the opening  458  in the outer ring. 
         [0064]    Roller bearings that are suitable for use include, but are not limited to, mechanical bearings, air bearings, bearings that support rotation about the x-, y-and z-axes and translation along the z-axis. A staged vacuum or lip seal can be used between the inner ring  452  and outer ring  454 , and between the inner ring  452  and the shaft  160 . This may provide vacuum barrier while still allowing rotation. 
         [0065]    Reference throughout this specification to “one embodiment,” “certain embodiments,” “one or more embodiments” or “an embodiment” means that a particular feature, structure, material, or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. Thus, the appearances of the phrases such as “in one or more embodiments,” “in certain embodiments,” “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily referring to the same embodiment of the disclosure. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments. 
         [0066]    Although the disclosure herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present disclosure. It will be apparent to those skilled in the art that various modifications and variations can be made to the method and apparatus of the present disclosure without departing from the spirit and scope of the disclosure. Thus, it is intended that the present disclosure include modifications and variations that are within the scope of the appended claims and their equivalents.