Abstract:
The present disclosure relates to methods and apparatus for a thin film encapsulation (TFE). A process kit for TFE is provided. The process kit is an assembly including a window, a mask parallel to the window, and a frame. The process kit further includes an inlet channel for flowing process gases into the volume between the window and the mask, an outlet channel for pumping effluent gases away from the volume between the window and the mask, and seals for inhibiting the flow of process gases and effluent gases to undesired locations. A method of performing TFE is provided, including placing a substrate under the mask of the above described process kit, flowing process gases into the process kit, and activating some of the process gases into reactive species by means of an energy source within a processing chamber.

Description:
BACKGROUND 
       [0001]    1. Field 
         [0002]    Embodiments of the present disclosure generally relate to an apparatus for processing large area substrates. More particularly, embodiments of the present disclosure relate to an atomic layer deposition (ALD) system for device fabrication and in situ cleaning methods for a showerhead of the same. 
         [0003]    2. Description of the Related Art 
         [0004]    Organic light emitting diodes (OLED) are used in the manufacture of television screens, computer monitors, mobile phones, other hand-held devices, etc. for displaying information. A typical OLED may include layers of organic material situated between two electrodes that are all deposited on a substrate in a manner to form a matrix display panel having pixels that may be individually energized. The OLED is generally placed between two glass panels, and the edges of the glass panels are sealed to encapsulate the OLED therein. 
         [0005]    The OLED industry, as well as other industries that utilize substrate processing techniques, must encapsulate moisture-sensitive devices to protect them from ambient moisture exposure. A thin conformal layer of material has been proposed as a means of reducing Water Vapor Transmission Rate (WVTR) through encapsulation layer(s). Currently, there are a number of ways this is being done commercially. Using an ALD process to cover a moisture-sensitive device is being considered to determine if the conformal nature of these coatings can provide a more effective moisture barrier than other coatings. 
         [0006]    ALD is based upon atomic layer epitaxy (ALE) and employs chemisorption techniques to deliver precursor molecules on a substrate surface in sequential cycles. The cycle exposes the substrate surface to a first precursor and then to a second precursor. Optionally, a purge gas may be introduced between introductions of the precursors. The first and second precursors react to form a product compound as a film on the substrate surface. The cycle is repeated to form the layer to a desired thickness. 
         [0007]    One method of performing ALD is by Time-Separated (TS) pulses of precursor gases. This method has several advantages over other methods, however one drawback of TS-ALD is that every surface (e.g., the interior of the chamber) exposed to the precursors will be coated with deposition. If these deposits are not removed periodically, they will tend to flake and peel off eventually, leading to particulates ending up on the substrate and hence degraded moisture barrier performance of the deposited layer. If there is no effective way to clean the undesired deposits from the chamber surfaces in situ, then those chamber surfaces must be removed for cleaning “off-line”. If the chamber has to be opened to accomplish removing and replacing chamber surfaces for cleaning, then vacuum has to be broken in the chamber (e.g., the chamber is brought to atmospheric pressure) and this breaking of vacuum will lead to excessive chamber down-time. 
         [0008]    There is a need, therefore, for a processing chamber allowing for removal and cleaning of the main key elements of the chamber which will accumulate extraneous deposits with minimal down-time. 
       SUMMARY 
       [0009]    A process kit for use in an ALD chamber is provided. The process kit generally includes a window, a mask disposed parallel to the window, and a frame connected with the window and the mask. The frame has at least one inlet channel connecting a first outer surface of the frame with a first inner surface of the frame, wherein the first inner surface is between the window and the mask. The frame also has at least one outlet channel connecting a second outer surface of the frame with a second inner surface of the frame, wherein the second inner surface of the frame is between the window and the mask. 
         [0010]    In another embodiment, a processing system for performing ALD is provided. The processing system generally includes an ALD processing chamber, wherein pressure within the ALD processing chamber is maintained at 1 torr or less and the ALD processing chamber has a first slit valve opening configured to permit passage of a process kit therethrough. The processing system further includes a first slit valve operable to open and close the first slit valve opening of the ALD processing chamber, wherein the first slit valve is operable to make an air-tight seal when closed, an inlet manifold operable to press against seals of a process kit and enable a flow of gases to an inlet channel of the process kit, an outlet manifold operable to press against seals of the process kit and enable a flow of gases from an outlet channel of the process kit, and one or more differential pump and purge assemblies operable to press against seals of the process kit and pump gases away from the process kit. 
         [0011]    In another embodiment, a method for performing ALD is provided. The method generally includes positioning a substrate and a process kit within an ALD processing chamber, wherein the process kit includes a window, a mask disposed parallel to the window, and a frame connected with the window and the mask. The frame has at least one inlet channel connecting a first outer surface of the frame with a first inner surface of the frame, wherein the first inner surface is between the window and the mask. The frame also has at least one outlet channel connecting a second outer surface of the frame with a second inner surface of the frame, wherein the second inner surface of the frame is between the window and the mask. Positioning the process kit within the ALD processing chamber generally includes pressing seals around an opening of an inlet channel of the process kit against an inlet manifold of the ALD processing chamber, pressing seals around an opening of an outlet channel of the process kit against an outlet manifold of the ALD processing chamber, and pressing other seals of the process kit against differential pump and purge assemblies of the ALD processing chamber. The method further includes flowing process gases via the inlet manifold into the process kit and pumping effluent gases out of the process kit via the outlet manifold. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    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. 
           [0013]      FIG. 1  illustrates an exemplary processing system, according to certain aspects of the present disclosure. 
           [0014]      FIG. 2  illustrates a side view of an exemplary chamber for ALD, according to certain aspects of the present disclosure. 
           [0015]      FIG. 3  illustrates a front view of an exemplary chamber for ALD, according to certain aspects of the present disclosure. 
           [0016]      FIGS. 4A and 4B  illustrate a process kit within a processing chamber, according to aspects of the present disclosure. 
           [0017]      FIG. 5  illustrates a process kit, according to aspects of the present disclosure. 
           [0018]      FIGS. 6A, 6B, and 6C  show positions of a process kit and substrate in a processing chamber, according to aspects of the present disclosure. 
           [0019]      FIG. 7  illustrates a front view of an exemplary chamber for ALD, according to certain aspects of the present disclosure. 
           [0020]      FIG. 8  illustrates a process kit, according to aspects of the present disclosure. 
       
    
    
       [0021]    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 disclosed in one embodiment may be beneficially utilized on other embodiments without specific recitation. 
       DETAILED DESCRIPTION 
       [0022]    Embodiments of the present disclosure include a processing system that is operable to deposit a plurality of layers on a substrate, the plurality of layers capable of acting as an encapsulation layer on an OLED formed on the substrate. The system includes a plurality of processing chambers, with each processing chamber operable to deposit one or more of the plurality of layers. The processing system further includes at least one transfer chamber and at least one load lock chamber. The at least one transfer chamber enables transfer of substrates between the plurality of processing chambers without breaking vacuum in the processing system. The at least one load lock chamber enables loading and removal of substrates from the processing system without breaking vacuum in the processing system. The processing system further includes a mask chamber that enables loading and removal of masks used in the processing chambers without breaking vacuum in the processing system. 
         [0023]    Embodiments of the disclosure include chemical vapor deposition (CVD) processing chambers that are operable to align a mask with respect to a substrate, position the mask on the substrate, and perform CVD to deposit an encapsulation layer on an OLED formed on the substrate. The CVD process performed in the CVD processing chambers may be plasma-enhanced CVD (PECVD), but the embodiments described herein may be used with other types of processing chambers and are not limited to use with PECVD processing chambers. The encapsulation layers deposited by the CVD processing chambers may comprise silicon nitride SiN, but the embodiments described herein may be used with other types of processing chambers and are not limited to use with SiN CVD processing chambers. 
         [0024]    Embodiments of the disclosure include an atomic layer deposition (ALD) processing chamber that is operable to align a mask with respect to a substrate, position the mask on the substrate, and perform ALD to deposit an encapsulation layer on an OLED formed on the substrate. The ALD process performed in the ALD processing chamber may be time-separated ALD (TS-ALD), but the embodiments described herein may be used with other types of processing chambers and are not limited to use with TS-ALD processing chambers. The encapsulation layers deposited by the ALD processing chambers may comprise aluminum oxide Al 2 O 3 , but the embodiments described herein may be used with other types of processing chambers and are not limited to use with SiN CVD processing chambers. 
         [0025]    The embodiments described herein may be used with other types of deposition processes and are not limited to use for encapsulating OLEDs formed on substrates. The embodiments described herein may be used with various types, shapes, and sizes of masks and substrates. 
         [0026]    The substrate is not limited to any particular size or shape. In one aspect, the term “substrate” refers to any polygonal, squared, rectangular, curved or otherwise non-circular workpiece, such as a glass substrate used in the fabrication of flat panel displays, for example. 
         [0027]    In the description that follows, the terms “gas” and “gases” are used interchangeably, unless otherwise noted, and refer to one or more precursors, reactants, catalysts, carrier gases, purge gases, cleaning gases, effluent, combinations thereof, as well as any other fluid. 
         [0028]      FIG. 1  is a cross sectional top view showing an illustrative processing system  100 , according to one embodiment of the present disclosure. The processing system  100  includes a load-lock chamber  104 , a transfer chamber  106 , a handling (e.g., tool and material handling) robot  108  within the transfer chamber  106 , a first CVD processing chamber  110 , a second CVD processing chamber  112 , a control station  114 , an ALD processing chamber  116 , and a mask chamber  118 . The first CVD processing chamber  110 , second CVD processing chamber  112 , ALD processing chamber  116 , and each chamber&#39;s associated hardware are preferably formed from one or more process-compatible materials, such as aluminum, anodized aluminum, nickel plated aluminum, stainless steel, quartz, and combinations and alloys thereof, for example. The first CVD processing chamber  110 , second CVD processing chamber  112 , and ALD processing chamber  116  may be round, rectangular, or another shape, as required by the shape of the substrate to be coated and other processing requirements. 
         [0029]    The transfer chamber  106  includes slit valve openings  121 ,  123 ,  125 ,  127 ,  129  in sidewalls adjacent to the load-lock chamber  104 , first CVD processing chamber  110 , second CVD processing chamber  112 , ALD processing chamber  116 , and mask chamber  118 . The handling robot  108  is positioned and configured to be capable of inserting one or more tools (e.g., substrate handling blades) through each of the slit valve openings  121 ,  123 ,  125 ,  127 ,  129  and into the adjacent chamber. That is, the handling robot can insert tools into the load-lock chamber  104 , the first CVD processing chamber  110 , the second CVD processing chamber  112 , the ALD processing chamber  116 , and the mask chamber  118  via slit valve openings  121 ,  123 ,  125 ,  127 ,  129  in the walls of the transfer chamber  106  adjacent to each of the other chambers. The slit valve openings  121 ,  123 ,  125 ,  127 ,  129  are selectively opened and closed with slit valves  120 ,  122 ,  124 ,  126 ,  128  to allow access to the interiors of the adjacent chambers when a substrate, tool, or other item is to be inserted or removed from one of the adjacent chambers. 
         [0030]    The transfer chamber  106 , load lock chamber  104 , first CVD processing chamber  110 , second CVD processing chamber  112 , ALD processing chamber  116 , and mask chamber  118  include one or more apertures (not shown) that are in fluid communication with a vacuum system (e.g., a vacuum pump). The apertures provide an egress for the gases within the various chambers. In some embodiments, the chambers are each connected to a separate and independent vacuum system. In still other embodiments, some of the chambers share a vacuum system, while the other chambers have separate and independent vacuum systems. The vacuum systems can include vacuum pumps (not shown) and throttle valves (not shown) to regulate flows of gases through the various chambers. 
         [0031]    Masks, mask frames, and other items placed within the first CVD chamber  110 , second CVD chamber  112 , and ALD processing chamber  116 , other than substrates, may be referred to as a “process kit.” Process kit items may be removed from the processing chambers for cleaning or replacement. The transfer chamber  106 , mask chamber  118 , first CVD processing chamber  110 , second CVD processing chamber  112 , and ALD processing chamber  116  are sized and shaped to allow the transfer of masks, mask frames, and other process kit items between them. That is, the transfer chamber  106 , mask chamber  118 , first CVD processing chamber  110 , second CVD processing chamber  112 , and ALD processing chamber  116  are sized and shaped such that any process kit item can be completely contained within any one of them with all of the slit valve openings  121 ,  123 ,  125 ,  127 ,  129  closed by each slit valve opening&#39;s  121 ,  123 ,  125 ,  127 ,  129  corresponding slit valve  120 ,  122 ,  124 ,  126 ,  128 . Thus, process kit items may be removed and replaced without breaking vacuum of the processing system, as the mask chamber  118  acts as an airlock, allowing process kit items to be removed from the processing system without breaking vacuum in any of the chambers other than the mask chamber. Furthermore, the slit valve opening  129  between the transfer chamber  106  and the mask chamber  118 , the slit valve openings  123 ,  125  between the transfer chamber  106  and the CVD processing chambers  110 ,  112 , and the slit valve opening  127  between the transfer chamber  106  and the ALD processing chamber  116  are all sized and shaped to allow the transfer of process kit items between the transfer chamber  106  and the mask chamber  118 , CVD processing chambers  110 ,  112 , and ALD processing chamber  116 . 
         [0032]    The mask chamber  118  has a door  130  and doorway  131  on the side of the mask chamber  118  opposite the slit valve opening  129  of the transfer chamber  106 . The doorway is sized and shaped to allow the transfer of masks and other process tools into and out to the mask chamber  118 . The door  130  is capable of forming an air-tight seal over the doorway  131  when closed. The mask chamber  118  is sized and shaped to allow any process kit item to be completely contained within the mask chamber  118  with both the door  130  closed and the slit valve  128  leading to the transfer chamber  106  closed. That is, the mask chamber  118  is sized and shaped such that any process kit item can be moved from the transfer chamber  106  into the mask chamber  118  and the slit valve  128  can be closed without the door  130  of the mask chamber  118  being opened. 
         [0033]    For simplicity and ease of description, an exemplary coating process performed within the processing system  100  will now be described. The exemplary coating process is controlled by a process controller, which may be a computer or system of computers that may be located at the control station  114 . 
         [0034]    Referring to  FIG. 1 , the exemplary processing of a substrate optionally begins with the handling robot  108  retrieving a mask from the mask chamber  118  and placing the mask in the ALD processing chamber  116 . Placing a mask in the ALD processing chamber  116  is optional because a mask may be left in the ALD processing chamber  116  from earlier processing, and the same mask may be used in processing multiple substrates. Similarly, the handling robot  108  may optionally retrieve other masks from the mask chamber  118  and place the masks in the first and second CVD processing chambers  110  and  112 . In placing masks within the first and second CVD processing chambers  110 ,  112  and the ALD processing chamber  116 , the appropriate slit valves  122 ,  124 ,  126 ,  128  between the chambers may be opened and closed. 
         [0035]    Next, the handling robot  108  retrieves a substrate from the load-lock  104  and places the substrate in the first CVD processing chamber  110 . The process controller controls valves, actuators, and other components of the processing chamber to perform the CVD processing. The process controller causes the slit valve  122  to be closed, isolating the first CVD processing chamber  110  from the transfer chamber  106 . The process controller also causes a substrate support member, or susceptor, to position the substrate for CVD processing. If the mask was not placed into the correct processing position by the handling robot, then the process controller may activate one or more actuators to position the mask. Alternatively or additionally, the susceptor may also position the mask for processing. The mask is used to mask off certain areas of the substrate and prevent deposition from occurring on those areas of the substrate. 
         [0036]    The process controller now activates valves to start the flow of precursor and other gases into the first CVD processing chamber  110 . The precursor gases may include silane SiH 4 , for example. The process controller controls heaters, plasma discharge components, and the flow of gases to cause the CVD process to occur and deposit layers of materials on the substrate. In one embodiment, the deposited layer may be silicon nitride SiN, although embodiments of the disclosure are not limited to this material. As noted above, embodiments of the disclosure may also be used to perform PECVD. The CVD process in the exemplary processing of the substrate is continued until the deposited layer reaches the required thickness. In one exemplary embodiment, the required thickness is 5000 to 10000 Angstroms (500 to 1000 nm). 
         [0037]    When the CVD process in the first CVD processing chamber  110  is complete, the process controller causes the first CVD processing chamber  110  to be evacuated and then controls the susceptor to lower the substrate to a transfer position. The process controller also causes the slit valve  122  between the first CVD processing chamber  110  and the transfer chamber  106  to be opened and then directs the handling robot  108  to retrieve the substrate from the first CVD processing chamber  110 . The process controller then causes the slit valve  122  between first CVD processing chamber  110  and the transfer chamber  106  to be closed. 
         [0038]    Next, the process controller causes the slit valve  126  between the transfer chamber  106  and the ALD processing chamber  116  to be opened. The handling robot  108  places the substrate in the ALD processing chamber  116 , and the process controller causes the slit valve  126  between the transfer chamber  106  and the ALD processing chamber  116  to be closed. The process controller also causes a substrate support member, or susceptor, to position the substrate for ALD processing. If the mask was not placed into the correct processing position by the handling robot, then the process controller may activate one or more actuators to position the mask. Alternatively or additionally, the susceptor may position the mask for processing. The mask is used to mask off certain areas of the substrate and prevent deposition from occurring on those areas of the substrate. 
         [0039]    The process controller now activates valves to start the flow of precursor and other gases into the ALD processing chamber  116 . The particular gas or gases that are used depend upon the process or processes to be performed. The gases can include trimethylaluminium (CH 3 ) 3 Al (TMA), nitrogen N 2 , and oxygen O 2 , however, the gases are not so limited and may include one or more precursors, reductants, catalysts, carriers, purge gases, cleaning gases, or any mixture or combination thereof. The gases may be introduced into the ALD processing chamber from one side and flow across the substrate. Depending on requirements of the processing system, the process controller may control valves such that only one gas is introduced into the ALD processing chamber at any particular instant of time. 
         [0040]    The process controller also controls a power source capable of activating the gases into reactive species and maintaining the plasma of reactive species to cause the reactive species to react with and coat the substrate. For example, radio frequency (RF) or microwave (MW) based power discharge techniques may be used. The activation may also be generated by a thermally based technique, a gas breakdown technique, a high intensity light source (e.g., UV energy), or exposure to an x-ray source. In the exemplary process, oxygen is activated into a plasma, and the plasma reacts with and deposits a layer of oxygen on the substrate. The process controller then causes TMA to flow across the substrate, and the TMA reacts with the layer of oxygen on the substrate, forming a layer of aluminum oxide on the substrate. The process controller causes repetition of the steps of flowing oxygen, activating oxygen into a plasma, and flowing TMA to form additional layers on the substrate. The process controller continues repeating the described steps until the deposited layer of aluminum oxide is the required thickness. In one exemplary embodiment, the required thickness is 500 to 700 Angstroms (fifty to seventy nm). 
         [0041]    When the ALD process in the ALD processing chamber  116  is complete, the process controller causes the ALD processing chamber  116  to be evacuated and then controls the susceptor to lower the substrate to a transfer position. The process controller also causes the slit valve  126  between the ALD processing chamber  116  and the transfer chamber  106  to be opened and then directs the handling robot  108  to retrieve the substrate from the ALD processing chamber  116 . The process controller then causes the slit valve  126  between ALD processing chamber  116  and the transfer chamber  106  to be closed. 
         [0042]    Still referring to  FIG. 1 , next, the process controller causes the slit valve  124  between the transfer chamber  106  and the second CVD processing chamber  112  to be opened. The handling robot  108  places the substrate in the second CVD processing chamber  112 , and the process controller causes the slit valve  124  between the transfer chamber  106  and the second CVD processing chamber  112  to be closed. Processing in the second CVD processing chamber  112  is similar to the processing in the first CVD processing chamber  110  described above. In the exemplary processing of the substrate, the CVD process performed in the second CVD processing chamber  112  is continued until the deposited layer reaches the desired thickness. In one exemplary embodiment, the desired thickness is 5000 to 10000 Angstroms (500 to 1000 nm). 
         [0043]    Thus, when the process in the second CVD processing chamber  112  is complete, the substrate will be coated with a first layer of SiN that is 5000 to 10000 Angstroms thick, a layer of Al 2 O 3  that is 500 to 700 Angstroms thick, and a second layer of SiN that is 5000 to 10000 Angstroms thick. The layer of Al 2 O 3  is believed to lower the water vapor transfer rate through the encapsulation layer, as compared to SiN alone, thus improving the reliability of the encapsulation, as compared to encapsulating with SiN alone. 
         [0044]    In the exemplary process described above with reference to  FIG. 1 , each of the CVD processing chambers  110 ,  112  and the ALD processing chamber  116  is loaded with a mask. Alternatively, the processing system  100  may perform a process wherein a mask moves with a substrate from processing chamber to processing chamber. That is, in a second exemplary process, a substrate and mask are placed (simultaneously or individually) in the first CVD processing chamber  110 , and the slit valve  122  between the transfer chamber  106  and the first processing chamber  110  is closed. A CVD process is then performed on the substrate. The substrate and mask are then moved (simultaneously or individually) into the ALD processing chamber  116 , and the slit valve  126  between the transfer chamber and the ALD processing chamber  116  is closed. An ALD process is then performed on the substrate. The substrate and mask are then moved (simultaneously or individually) into the second CVD processing chamber  112 . A CVD process is then performed on the substrate, and the substrate and mask are then removed from the second CVD processing chamber  112 . The substrate may be removed from the processing system  100 , if complete, and the mask may be used for processing a new substrate or removed from the processing system  100  for cleaning, for example. 
         [0045]      FIG. 2  is a partial cross sectional side view showing an illustrative ALD processing chamber  200  with a process kit  250  in processing position, according to embodiments of the present disclosure. The process kit is described in greater detail below with reference to  FIGS. 4 and 5 . The ALD processing chamber shown in  FIG. 2  is similar to the ALD processing chamber  116  shown in  FIG. 1 . In one embodiment, the processing chamber  200  includes a chamber body  202 , a lid assembly  204 , a substrate support assembly  206 , a process gas inlet assembly (see  FIG. 3 ) and a pumping port assembly (see  FIG. 3 ). The lid assembly  204  is disposed at an upper end of the chamber body  202 , and the substrate support assembly  206  is at least partially disposed within the chamber body  202 . 
         [0046]    The chamber body  202  includes a slit valve opening  208  formed in a sidewall thereof to provide access to the interior of the processing chamber  200 . As described above with reference to  FIG. 1 , the slit valve opening  208  is selectively opened and closed to allow access to the interior of the chamber body  202  by a handling robot (see  FIG. 1 ). 
         [0047]    In one or more embodiments, the chamber body  202  includes one or more apertures (not shown) that are in fluid communication with a vacuum system (e.g., a vacuum pump). The apertures provide an egress for gases within the processing chamber. The vacuum system is controlled by a process controller to maintain a pressure within the ALD processing chamber suitable for the ALD process. In one embodiment of the present disclosure, the pressure in the ALD processing chamber is maintained (by, e.g., a process controller) at a pressure of 500 to 700 mTorr. 
         [0048]    The lid assembly  204  may include one or more differential pump and purge assemblies  220 . The differential pump and purge assemblies are mounted to the lid assembly with bellows  222 . The bellows  222  allow the pump and purge assemblies  220  to move vertically with respect to the lid assembly  204  while still maintaining a seal against gas leaks. When the process kit  250  is raised into a processing position, a compliant first seal  286  and a compliant second seal  288  on the process kit  250  are brought into contact with the differential pump and purge assemblies  220 . The first and second seals  286 ,  288  are compressed when the process kit  250  is in the processing position, and the differential pump and purge assemblies  220  can move to maintain the desired compression force on the first and second seals  286 ,  288 . The first and second seals  286 ,  288  may be made, for example, from a rubber or plastic material that is compatible with exposure to the process gases and effluent. The differential pump and purge assemblies  220  are connected with a vacuum system (not shown) and maintained at a low pressure. When processing is occurring in the ALD processing chamber  200 , the vacuum system (not shown) connected with the differential pump and purge assemblies  220  is controlled (by, e.g., a process controller) to draw a vacuum at a pressure equal to or lower than the pressure of the ALD processing chamber  200 . For example, when processing is occurring and pressure in the ALD processing chamber  200  is being maintained at 500 to 700 mTorr (see above), the differential pump and purge assemblies  220  are drawing a vacuum at 400 to 500 mTorr. By drawing a vacuum at a pressure lower than the pressure in the ALD processing chamber  200 , the differential pump and purge assemblies  220  can prevent any gases that leak past the seals on the process kit  250  from entering the ALD processing chamber  200 . If there are leaks in the first and second seals  286 ,  288 , the lower pressure within the differential pump and purge assemblies  220  causes gases within the ALD processing chamber  200  to leak into the differential pump and purge assemblies  220 , rather than gases leaking from the differential pump and purge assemblies  220  into the ALD processing chamber  200 . 
         [0049]    The processing chamber  200  may include a valve block assembly (not shown). The valve block assembly comprises a set of valves and controls the flow of the various gases (e.g., process gases, carrier gases, and purge gases) into the processing chamber  200 . 
         [0050]    Still referring to  FIG. 2 , the lid assembly  204  includes a radio frequency (RF) cathode  210  that can generate a plasma of reactive species within the processing chamber  200  and/or within the process kit  250  (see below with reference to  FIG. 4 ). Temperature of the RF cathode  210  is controlled (by, e.g., a process controller) during processing in the ALD processing chamber  200  to influence temperature of the process kit  250  and substrate  232  and improve performance of the ALD processing. The temperature of the RF cathode  210  may be measured by a pyrometer (not shown), for example, or other sensor in the ALD processing chamber  200 . The RF cathode  210  may be heated by electric heating elements (not shown), for example, and cooled by circulation of cooling fluids, for example. Any power source capable of activating the gases into reactive species and maintaining the plasma of reactive species may be used. For example, radio frequency (RF) or microwave (MW) based power discharge techniques may be used. The activation may also be generated by a thermally based technique, a gas breakdown technique, a high intensity light source (e.g., UV energy), or exposure to an x-ray source. 
         [0051]    Still referring to  FIG. 2 , the substrate support assembly  206  can be at least partially disposed within the chamber body  202 . The substrate support assembly can include a substrate support member or susceptor  230  to support a substrate  232  for processing within the chamber body. According to embodiments of the present disclosure, the susceptor can also support (see  FIG. 4 ) the process kit  250 . The susceptor can be coupled to a substrate lift mechanism (not shown) through a shaft  224  or shafts  224  which extend through one or more openings  226  formed in a bottom surface of the chamber body. The substrate lift mechanism can be flexibly sealed to the chamber body by a bellows  228  that prevents vacuum leakage from around the shafts. The substrate lift mechanism allows the susceptor  230  to be moved vertically within the ALD processing chamber  200  between a lower robot entry position, as shown, and processing, process kit transfer, and substrate transfer positions. In some embodiments, the substrate lift mechanism moves between fewer positions than those described. 
         [0052]    In one or more other embodiments, the susceptor  230  has a flat, rectangular surface or a substantially flat, rectangular surface, as required by the shape of the substrate and other processing requirements. In one or more embodiments, the substrate  232  may be secured to the susceptor using a vacuum chuck (not shown), an electrostatic chuck (not shown), or a mechanical clamp (not shown). The temperature of the susceptor  230  may be controlled (by, e.g., a process controller) during processing in the ALD processing chamber  200  to influence temperature of the substrate  232  and the process kit  250  and improve performance of the ALD processing. The susceptor  230  may be heated by, for example, electric heating elements (not shown) within the susceptor  230 . The temperature of the susceptor may be determined by pyrometers (not shown) in the processing chamber  200 , for example. 
         [0053]    Still referring to  FIG. 2 , the susceptor  230  can include one or more bores  234  through the susceptor to accommodate one or more lift pins  236 . Each lift pin is typically constructed of ceramic or ceramic-containing materials, and is used for substrate-handling and transport. Each lift pin  236  is mounted so that they may slide freely within a bore  234 . In one aspect, each bore is lined with a ceramic sleeve to help the lift pins to freely slide. Each lift pin is moveable within its respective bore  234  by contacting the chamber body  202  when the support assembly  206  is lowered, as illustrated in  FIG. 2 . The support assembly  206  is movable such that the upper surface of the lift pin  236  can be located above the substrate support surface  238  of the susceptor  230  when the support assembly  206  is in a lower position. Conversely, the upper surface of the lift pins  236  is located below the upper surface  238  of the susceptor  230  when the support assembly  206  is in a raised position. Thus, part of each lift pin  236  passes through its respective bore  234  in the susceptor  230  when the support assembly  206  moves from a lower position to an upper position, and vice-versa. 
         [0054]    When contacting the chamber body  202 , the lift pins  236  push against a lower surface of the substrate  232 , lifting the substrate off the susceptor  230 . Conversely, the susceptor  230  may raise the substrate  232  off of the lift pins  236 . The lift pins  236  can include enlarged upper ends or conical heads to prevent the lift pins  236  from falling out of the susceptor  230 . Other pin designs can also be utilized and are well known to those skilled in the art. 
         [0055]    In one embodiment, one or more of the lift pins  236  include a coating or an attachment disposed thereon that is made of a non-skid or highly frictional material to prevent the substrate  232  from sliding when supported thereon. A preferred material is a heat-resistant, polymeric material that does not scratch or otherwise damage the backside of the substrate  232 , which may create contaminants within the processing chamber  200 . 
         [0056]    In some embodiments, the susceptor includes process kit insulation buttons  237  that may include one or more compliant seals  239 . The process kit insulation buttons  237  may be used to carry the process kit  250  on the susceptor  230 . The one or more compliant seals  239  in the process kit insulation buttons  237  are compressed when the susceptor lifts the process kit  250  into the processing position (see discussion of processing below, with reference to  FIGS. 1-5 ). The process kit insulation buttons  237  may be made of aluminum oxide Al 2 O 3  or another material with a high electrical resistance to insulate the susceptor from electrical charges induced on the process kit due to the processing. 
         [0057]    Referring back to  FIG. 2 , the susceptor  230  can be moved vertically within the chamber body  202  so that the susceptor  230  contacts the process kit  250  (see  FIG. 4 ). The process kit  250  may be on the susceptor  230  during part of the movement of the process kit  250  into or out of the processing chamber  200 . A distance between the process kit  250  and the RF cathode  210  can be controlled. An optical or other sensor (not shown), for example, can provide information concerning the position of the susceptor  230  within the chamber  200 . 
         [0058]      FIG. 3  is a partial cross-sectional view from the front of the ALD processing chamber  200  illustrated in  FIG. 2 . That is,  FIG. 3  shows the same ALD processing chamber as shown in  FIG. 2 , but from a different point of view. Visible in  FIG. 3  are the process gas inlet assembly  310  and the pumping port assembly  330 . 
         [0059]    The process gas inlet assembly  310  supplies process gases to the ALD processing chamber  200 . Process gases used may include trimethylaluminium (TMA) Al 2 (CH 3 ) 6 , oxygen O 2 , and nitrogen N 2 . The process gases may be supplied in a continuous flow or may be pulsed, either individually or together. The process gas inlet assembly  310  comprises one or more inlet pipes  312 , a bellows  314 , an inlet manifold  316 , an inlet contact surface  318 , and seals  320 . 
         [0060]    Process gases are supplied from a process gas source (e.g., a tank or pipeline, not shown) to the one or more inlet pipes  312 . The flow of process gases is controlled by, for example, a process controller (not shown) controlling the operation of one or more valves in a valve block (not shown). The one or more inlet pipes  312  are connected with the ALD processing chamber  200  by a bellows  314 . The bellows  314  allows the one or more inlet pipes  312  and inlet manifold  316  to move with respect to the ALD processing chamber  200  (e.g., when the process kit  250  contacts the inlet contact surface  318  as shown in  FIG. 4 ) without allowing air to leak into the ALD processing chamber  200 . The process gases flow through the inlet pipe  312  and into the inlet manifold  316 . 
         [0061]    The process gases flow through the inlet manifold  316 , through one or more channels  322  in the inlet contact surface  318 , and into one or more inlet channels  354  in the process kit  250  (see also  FIG. 4 ). The inlet contact surface  318  may be made from any material compatible with exposure to the process gases and effluent gases, for example, polytetrafluoroethylene (PTFE). One or more seals  320  seal the joint between the inlet manifold  316  and the inlet contact surface  318  to inhibit process gases from leaking into the ALD processing chamber  200 . 
         [0062]    Effluent gases, which comprise reaction products and unreacted process gases, are pumped out of one or more outlet channels  356  in the process kit  250  via the pumping port assembly  330 . The pumping port assembly comprises one or more outlet pipes  332 , a bellows  334 , an outlet manifold  336 , an outlet contact surface  338 , and seals  340 . 
         [0063]    Effluent gases from within the process kit  250  (see the description of ALD processing with reference to  FIG. 4  below) exit the process kit  250  via one or more outlet channels  356 . The effluent gases flow through the outlet channels  356  and into one or more channels  342  in the outlet contact surface  338  (see also  FIG. 4 ). 
         [0064]    The effluent gases flow through the channels  342  in the outlet contact surface  338  and into the outlet manifold  336 . The outlet contact surface  338  may be made from any compliant material compatible with exposure to the process gases and effluent gases, for example, polytetrafluoroethylene (PTFE). One or more seals  340  seal the joint between the outlet contact surface  338  and the outlet manifold  336  to inhibit effluent gases from leaking into the ALD processing chamber  200 . 
         [0065]    The effluent gases flow through outlet manifold  336  and into the one or more outlet pipes  332 . The bellows  334  allows the one or more outlet pipes  332  and outlet manifold  336  to move with respect to the ALD processing chamber  200  (e.g., when the process kit  250  contacts the outlet contact surface  338  as shown in  FIG. 4 ) without allowing air to leak into the ALD processing chamber  200 . 
         [0066]    The effluent gases are pumped out of the one or more outlet pipes  332  by a vacuum system (not shown). 
         [0067]      FIGS. 4A and 4B  show partial cross-sectional front views of the process kit  250  and the susceptor  230  and lid assembly  204  of the ALD processing chamber  200 .  FIG. 4B  shows an enlarged view of the indicated portion of  FIG. 4A  to more clearly present details. The illustrated components are in a processing position, with a substrate  232  positioned for performing ALD. 
         [0068]    According to embodiments of the present disclosure, the process kit  250  may comprise a mask  458 , a window  460 , and a frame assembly  470 . The process kit  250  has at least one inlet channel  354  connecting a first outer surface  402  of the frame assembly  470  with a first inner surface  404  of the frame assembly  470  that is between the mask  458  and the window  460 . The process kit  250  also has at least one outlet channel  356  connecting a second outer surface  410  with a second inner surface  412  of the frame assembly  470  that is between the mask  458  and the window  460 . As illustrated in  FIG. 4A , when the process kit  250  is in a processing position, the at least one inlet channel  354  is aligned with the one or more channels  322  in the inlet contact surface  318  of the process gas inlet assembly  310 . Also, when the process kit  250  is in a processing position, the at least one outlet channel  356  is aligned with the one or more channels  342  in the outlet contact surface  338  of the pumping port assembly  330 . 
         [0069]    In some embodiments of the present disclosure, the frame assembly  470  may comprise an upper member  472 , a window clamping member  474 , a middle member  476 , and a lower member  478 . In embodiments of the process kit  250  comprising a window clamping member  474 , the window  460  is clamped between the window clamping member  474  and the upper member  472 . 
         [0070]    Referring to  FIG. 4A  and  FIG. 4B , in some embodiments of the present disclosure, the process kit  250  further comprises at least one window seal  480 , at least one seal  482  surrounding an opening of the inlet channel  354 , at least one seal  484  surrounding an opening of the outlet channel  356 , a first seal  286  on the upper surface of the frame assembly  470 , a second seal  288  on the upper surface of the frame assembly  470 , and one or more seals  490 . In embodiments comprising a window seal  480 , the window  460  is held by the window seal  480  and the window clamping member  474 , with the window  460  between the window seal  480  and the window clamping member  474 . The window seal  480 , at least one seal  482  surrounding an opening of the inlet channel  354 , at least one seal  484  surrounding an opening of the outlet channel  356 , first seal  286 , second seal  288 , and seals  490  may all be made of a compliant material (e.g., rubber, PTFE) that is compatible with exposure to the processing gases and effluent gases. 
         [0071]    The mask  458  and lower member  478  may be made of Invar or other materials that are compatible with exposure to process and effluent gases and have low coefficient of thermal expansion. It is desirable that the mask  458  and the lower member  478  be made from materials with low coefficients of thermal expansion to reduce variations in the locations of the deposited coatings caused by variations in temperature during processing. That is, variations in masked locations caused by temperature variations are reduced, if the mask  458  and a frame member holding the mask  458  (e.g., the frame lower member  478 ) are made from a material with a low coefficient of thermal expansion. 
         [0072]    The upper member  472  and middle member  476  of the frame assembly  470  may be made of aluminum, anodized aluminum, nickel plated aluminum, stainless steel, quartz, or other materials compatible with exposure to the process gases and effluent gases. 
         [0073]    During ALD processing in the ALD processing chamber  200 , the susceptor  230  positions the substrate  232  just below the mask  458  of the process kit  250 . While the susceptor  230  is positioning the substrate  232 , the susceptor  230  is also pressing the process kit  250  into contact with the differential pump and purge assemblies  220  (see  FIG. 2 ), the inlet contact surface  318  (see also  FIG. 3 ), and the outlet contact surface  338  (see also  FIG. 3 ). Pressing the process kit into contact with the differential pump and purge assemblies  220  (see  FIG. 2 ), the inlet contact surface  318  (see also  FIG. 3 ), and the outlet contact surface  338  (see also  FIG. 3 ) causes compression of the at least one seal  482  surrounding an opening of the inlet channel  354 , at least one seal  484  surrounding an opening of the outlet channel  356 , first seal  286 , and second seal  288 . The at least one seal  482  surrounding an opening of the inlet channel  354 , at least one seal  484  surrounding an opening of the outlet channel  356 , first seal  286 , and second seal  288  all inhibit the leakage of process and/or effluent gases into the processing chamber  200 . 
         [0074]    In other embodiments of the present disclosure, the process kit  250  is held in position against the differential pump and purge assemblies  220  (see  FIG. 2 ), the inlet contact surface  318  (see also  FIG. 3 ), and the outlet contact surface  338  (see also  FIG. 3 ) by a separate mechanical chuck (not shown), vacuum chuck (not shown), or magnetic chuck (not shown). When held by one of the various chucks, the process kit  250  may be held against the differential pump and purge assemblies  220  (see  FIG. 2 ), the inlet contact surface  318  (see also  FIG. 3 ), and the outlet contact surface  338  (see also  FIG. 3 ) with the various seals  482 ,  484 ,  286 ,  288  compressed, or the process kit  250  may be held in a position without some or all of the various seals  482 ,  484 ,  286 ,  288  being compressed. 
         [0075]      FIG. 5  shows a top view of an exemplary process kit  250 . As shown, the window  460 , window clamping member  474 , upper member  472 , an opening of an inlet channel  354 , and an opening of an outlet channel  356  are visible in the top view of the process kit  250 . Also visible are one seal  482  surrounding the opening of the inlet channel  354 , one seal  484  surrounding the opening of the outlet channel  356 , the first seal  286  on the upper surface of the frame, and the second seal  288  on the upper surface of the frame. Various screws connecting the window clamping member  474  to the upper member  472  are not shown in  FIG. 5 , so that other features can be seen more clearly. 
         [0076]    While the exemplary process kit  250  shown in  FIG. 5  has only a single slit-shaped (i.e., having a high length-to-width ratio, e.g., 4 to 1) opening to the inlet channel  354 , the disclosure is not so limited. While the illustrated slit-shaped opening has sharp corners, embodiments of the disclosure may have slit-shaped openings with rounded ends. In addition, embodiments of the present disclosure may use openings of many other shapes, for example, square, ovoid, and rectangular openings to the inlet channel  354  may be used. Also, embodiments of the disclosure may use more than one inlet channel  354 , with each inlet channel  354  having a corresponding opening or openings. Each opening may be surrounded by a seal  482 , or more than one opening may be surrounded by one seal  482 . 
         [0077]    Similarly, while the exemplary process kit  250  shown in  FIG. 5  has only a single slit-shaped opening to the outlet channel  356 , the disclosure is not so limited. While the illustrated slit-shaped opening has sharp corners, embodiments of the disclosure may have slit-shaped openings with rounded ends. In addition, embodiments of the present disclosure may use openings of many shapes, for example, square, ovoid, and rectangular openings to the outlet channel  356  may be used. Also, embodiments of the disclosure may use more than one outlet channel  356 , with each outlet channel  356  having a corresponding opening or openings. Each opening may be surrounded by a seal  484 , or more than one opening may be surrounded by one seal  484 . 
         [0078]    The window  460  of the process kit  250  may be made of quartz, for example, or another material that both allows radiant energy (e.g., infrared rays, ultraviolet rays, or RF energy) to penetrate into the process kit  250  and is compatible with exposure to process gases and effluent gases. 
         [0079]    The window clamping member  474  may be made of aluminum oxide Al 2 O 3  or another material that can clamp the quartz or other material of the window  460  without being damaged by exposure to the energy (e.g., infrared rays, ultraviolet rays, or RF energy) used to convert process gases to reactive species (e.g., RF energy from the RF cathode  210 ). 
         [0080]    The various seals  482 ,  484 ,  286 , and  288  may be made of PTFE, rubber, or another compliant material that is compatible with exposure to process gases and effluent gases. 
         [0081]    In order to further describe the process kit  250 , an exemplary ALD process performed using the process kit  250  in the ALD processing chamber  200  will now be described, with reference to  FIGS. 1-5 . 
         [0082]    In the exemplary ALD process, a process kit  250  is present in the ALD processing chamber  200  (see  FIG. 2 ) when the handling robot  108  (see  FIG. 1 ), under the direction of a process controller (not shown), places a substrate  232  on the lift pins  236  in the ALD processing chamber  200  (see  FIG. 2 ). The handling robot  108  places the substrate  232  in the ALD processing chamber  200  by means of a blade or other robotic tool that the handling robot  108  inserts into the ALD processing chamber  200  via the slit valve  208  (see  FIG. 2 ). 
         [0083]    The process controller then directs the substrate support assembly  206  (see  FIG. 2 ) to raise the substrate  232  into a processing position below the mask  458  of the process kit  250  (see  FIG. 4A ). When the substrate  232  is in the process position, the process controller starts the flow of process gases into the ALD processing chamber  200  via the process gas inlet assembly  310  (see  FIG. 3 ). The process gases may be flowed as a mixture of multiple precursors (e.g. TMA and O 2 ) and carrier gases (e.g., Helium), or, if time separated ALD (TS-ALD) is to be performed, then each precursor gas (possibly mixed with a carrier gas) flows in separate pulses from each other precursor gas source. 
         [0084]    The process gases flow through the inlet manifold  316 , through one or more channels  322  in the inlet contact surface  322 , and into one or more inlet channels  354  of the process kit (see  FIG. 3 ). The process gases flow through the inlet channels  354  and into the volume between the window  460  and mask  458  of the process kit  250  (see  FIG. 4A ). While the process gases are in the volume between the window  460  and mask  458 , the process gases may be activated into reactive species (e.g., plasma) by the RF cathode  210  (or other means of activating the process gases) of the ALD processing chamber  200 . The process gases can be activated within the process kit  250 , because the window  460  allows activating rays (or other energy) to penetrate into the process kit  250 . For example, oxygen can be activated into a plasma within the volume between the window  460  and the mask  458 . 
         [0085]    The process gases and any activated species of the process gases react with and coat the substrate  232 . For example, a plasma of oxygen may react with and coat the substrate  232 . In the example, TMA may then react with the oxygen coating on the substrate, forming a layer of aluminum oxide on the substrate. The mask  458  controls the exposure of the substrate so that coatings of materials are deposited in desired locations of the substrate  232 , and not deposited in areas of the substrate  232  where the coatings are not desired. 
         [0086]    Effluent gases (e.g., reaction products and unreacted process gases) are pumped out of the process kit  250  via one or more outlet channels  356  (see  FIGS. 3 and 4 ). Effluent gases flow from the one or more outlet channels  356  into the one or more channels  342  in the outlet contact surface, through the outlet manifold  336 , and into the one or more outlet pipes  332 , as described above. 
         [0087]    Some process gases may leak past the one or more seals  482  surrounding the opening of the inlet channel  354 . Process gases leaking past the seal(s)  482  are inhibited from moving into other parts of the ALD processing chamber  200  by the first seal  286  and second seal  288  on the upper surface of the frame of the process kit  250  (see  FIG. 5 ). In addition, process gases leaking past the seal(s)  482  may be pumped out of the ALD processing chamber  200  by the differential pump and purge assemblies  220  (see  FIG. 2 ). 
         [0088]    Some effluent gases may leak past the one or more seals  484  surrounding the opening of the outlet channel  356 . Effluent gases leaking past the seal(s)  484  are inhibited from moving into other parts of the ALD processing chamber  200  by the first seal  286  and second seal  288  on the upper surface of the frame of the process kit  250  (see  FIG. 5 ). In addition, effluent gases leaking past the seal(s)  484  may be pumped out of the ALD processing chamber  200  by the differential pump and purge assemblies  220  (see  FIG. 2 ). 
         [0089]      FIGS. 6A, 6B, and 6C  show front views (i.e., from the same point of view as  FIG. 3 ) of positions of a process kit and substrate during the placement of a process kit and a substrate in the exemplary ALD processing chamber  200 , in preparation for performing processing.  FIG. 6A  shows the position of the process kit  250  immediately after the process kit  250  has been placed in the processing chamber  200 . The process kit  250  is placed in the processing chamber  200  by the handling robot  108  (see  FIG. 1 ) via the slit valve opening  208  (see  FIG. 2 ). The process kit  250  is placed on process kit alignment pins  602  by the handling robot  108 . The process kit alignment pins  602  have ends of conical or other shape that help to align the process kit  250  with the processing position of the process kit  250 . 
         [0090]    The process kit alignment pins  602  are connected with a process kit lift mechanism (not shown) that can raise and lower the process kit alignment pins  602 . After the handling robot has placed the process kit  250  on the process kit alignment pins  602 , the process kit lift mechanism raises the process kit alignment pins  602 , which raise the process kit  250 . 
         [0091]      FIG. 6B  shows the process kit alignment pins  602  and process kit  250  in a raised position. The raised position shown in  FIG. 6B  may be referred to as a substrate loading position. When the process kit alignment pins  602  and process kit  250  are in the substrate loading position, the handling robot (see  FIG. 1 ) may place a substrate  232  within the processing chamber  200  via the slit valve opening  208  (see  FIG. 2 ). The substrate  232  is placed on the lift pins  236 . The handling robot  108  then withdraws the tool (e.g., a blade) used to place the substrate within the processing chamber  200 , and the process controller causes the slit valve  208  to be closed. After the handling robot  108  has withdrawn the tool from the processing chamber  200 , the substrate lift mechanism (not shown) can raise the one or more shafts  224  (see  FIG. 2 ), which raise the susceptor  230 . 
         [0092]      FIG. 6C  shows the process kit  250 , susceptor  230 , and substrate  232  in the processing position. As shown in more detail in  FIGS. 4 and 4A , the process kit  250  is lifted into the processing position by the susceptor  230 . The process kit  250  is in contact with the inlet contact surface  318  and the outlet surface contact  338  when the process kit  250  is in the processing position. 
         [0093]    When processing is complete, the substrate lift mechanism (not shown) lowers the susceptor  230 . The process kit  250  comes to rest on the process kit alignment pins  602 , and the substrate  232  comes to rest on the lift pins  236 , as shown in  FIG. 6B . 
         [0094]      FIG. 7  is a partial cross-sectional view from the front of an exemplary ALD processing chamber  700  illustrated. The exemplary ALD processing chamber  700  is similar to the exemplary processing chamber  200  illustrated in  FIG. 2 . Visible in  FIG. 7  are two pumping port assemblies  730   a ,  730   b.    
         [0095]    Process gas is supplied to the ALD processing chamber  700  via one or more inlets  702 . The process gases may enter a plenum  704  before the process gases flow into the interior of the ALD processing chamber  700 . The process gases may be supplied in a continuous flow or may be pulsed, either individually or together. Some or all of the process gases may be activated into a reactive species (e.g., a plasma) in the plenum  704  before they flow into the interior of the ALD processing chamber. 
         [0096]    Process gases are supplied from a process gas source (e.g., a tank or pipeline, not shown) to the one or more inlet pipes  712   a ,  712   b . The flow of process gases is controlled by, for example, a process controller (not shown) controlling the operation of one or more valves in a valve block (not shown). 
         [0097]    The process gases flow through the plenum  704 , through the one or more inlets  702 , and into one or more inlet channels  754  in a process kit  750  (see also  FIG. 8 ). One or more seals  720  seal the joint between the inlet  702  and the inlet channel  754  to inhibit process gases from leaking into the ALD processing chamber  200 . 
         [0098]    Effluent gases, which comprise reaction products and unreacted process gases, are pumped out of one or more outlet channels  756   a ,  756   b  in the process kit  750  via the pumping port assemblies  730   a ,  730   b . The pumping port assemblies  730   a ,  730   b  comprise one or more outlet pipes  732   a ,  732   b , bellows  734   a ,  734   b , outlet manifolds  736   a ,  736   b , outlet contact surfaces  738   a ,  738   b , and seals  740   a ,  740   b.    
         [0099]    Effluent gases from within the process kit  750  (see the description of ALD processing with reference to  FIG. 4  above) exit the process kit  750  via one or more outlet channels  756   a ,  756   b . The effluent gases flow through the outlet channels  756   a ,  756   b  and into one or more channels  742   a ,  742   b  in the outlet contact surfaces  738   a ,  738   b.    
         [0100]    The effluent gases flow through the channels  742   a ,  742   b  in the outlet contact surfaces  738   a ,  738   b  and into the outlet manifolds  736   a ,  736   b . The outlet contact surfaces  738   a ,  738   b  may be made from any compliant material compatible with exposure to the process gases and effluent gases, for example, polytetrafluoroethylene (PTFE). One or more seals  740   a ,  740   b  seal the joints between the outlet contact surfaces  738   a ,  738   b  and the outlet manifolds  736   a ,  736   b  to inhibit effluent gases from leaking into the ALD processing chamber  700 . 
         [0101]    The effluent gases flow through outlet manifolds  736   a ,  736   b  and into the one or more outlet pipes  732   a ,  732   b . The bellows  734   a ,  734   b  allow the one or more outlet pipes  732   a ,  732   b  and outlet manifolds  736   a ,  736   b  to move with respect to the ALD processing chamber  700  (e.g., when the process kit  750  contacts the outlet contact surfaces  738   a ,  738   b  as shown) without allowing air to leak into other portions of the ALD processing chamber  700 . 
         [0102]    The effluent gases are pumped out of the one or more outlet pipes  732   a ,  732   b  by a vacuum system (not shown). 
         [0103]      FIG. 8  shows a top view of an exemplary process kit  750 . The exemplary process kit  750  has some similarity to the exemplary process kit  250  illustrated in  FIG. 2 , and similar terminology is used to describe similar components. As shown, two windows  760   a ,  760   b , window clamping members  774   a ,  774   b , upper member  772 , an opening of an inlet channel  754 , and two openings of outlet channels  756   a ,  756   b  are visible in the top view of the process kit  750 . Also visible are one seal  782  surrounding the opening of the inlet channel  754 , two seals  784   a ,  784   b  surrounding the openings of the outlet channels  756   a ,  756   b , and a first seal  786  on the upper surface of the frame. It is to be noted that the windows  760   a ,  760   b  and window clamping members  754   a ,  754   b  are optional. If the windows  760   a ,  760   b  and window clamping members  754   a ,  754   b  are not present, then the upper member  772  may enclose the interior of the process kit  750 . Various screws connecting the window clamping members  774   a ,  774   b  to the upper member  772  are not shown in  FIG. 8 , so that other features can be seen more clearly. 
         [0104]    While the exemplary process kit  750  shown in  FIG. 8  has only a single slit-shaped (i.e., having a high length-to-width ratio, e.g., 4 to 1) opening to the inlet channel  754 , the disclosure is not so limited. While the illustrated slit-shaped opening has sharp corners, embodiments of the disclosure may have slit-shaped openings with rounded ends. In addition, embodiments of the present disclosure may use openings of many other shapes, for example, square, ovoid, and rectangular openings to the inlet channel  754  may be used. Also, embodiments of the disclosure may use more than one inlet channel  754 , with each inlet channel  754  having a corresponding opening or openings. Each opening may be surrounded by a seal  782 , or more than one opening may be surrounded by one seal  782 . 
         [0105]    Similarly, while the exemplary process kit  750  shown in  FIG. 8  has two single slit-shaped openings to the outlet channels  756   a ,  756   b , the disclosure is not so limited. While the illustrated slit-shaped openings have sharp corners, embodiments of the disclosure may have slit-shaped openings with rounded ends. In addition, embodiments of the present disclosure may use openings of many shapes, for example, square, ovoid, and rectangular openings to the outlet channels  756   a ,  756   b  may be used. Also, embodiments of the disclosure may use more than one outlet channel  756   a ,  756   b , with each outlet channel  756   a ,  756   b  having a corresponding opening or openings. Each opening may be surrounded by a seal  784   a ,  784   b , or more than one opening may be surrounded by one seal  784   a ,  784   b.    
         [0106]    The windows  760   a ,  760   b  of the process kit  750  may be made of quartz, for example, or another material that both allows radiant energy (e.g., infrared rays, ultraviolet rays, or RF energy) to penetrate into the process kit  750  and is compatible with exposure to process gases and effluent gases. 
         [0107]    The window clamping members  774   a ,  774   b  may be made of aluminum oxide Al 2 O 3  or another material that can clamp the quartz or other material of the windows  760   a ,  760   b  without being damaged by exposure to the energy (e.g., infrared rays, ultraviolet rays, or RF energy) used to convert process gases to reactive species. 
         [0108]    The various seals  782 ,  784   a ,  784   b , and  786  may be made of PTFE, rubber, or another compliant material that is compatible with exposure to process gases and effluent gases. 
         [0109]    The process controller described above with reference to  FIG. 1  can operate under the control of a computer program stored on a hard disk drive of a computer. For example, the computer program can dictate the process sequencing and timing, mixture of gases, chamber pressures, RF power levels, susceptor positioning, slit valve opening and closing, and other parameters of a particular process. 
         [0110]    To provide a better understanding of the foregoing discussion, the above non-limiting examples are offered. Although the examples may be directed to specific embodiments, the examples should not be interpreted as limiting the disclosure in any specific respect. 
         [0111]    Unless otherwise indicated, all numbers expressing quantities of ingredients, properties, reaction conditions, and so forth, used in the specification and claims are to be understood as approximations. These approximations are based on the desired properties sought to be obtained by the present disclosure, and the error of measurement, and should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Further, any of the quantities expressed herein, including temperature, pressure, spacing, molar ratios, flow rates, and so on, can be further optimized to achieve the desired layer and particle performance. 
         [0112]    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.