Abstract:
In a first aspect, a substrate carrier is provided that includes an enclosure adapted to be sealable and to house at least one substrate. The substrate carrier includes a first port leading into the enclosure and adapted to allow a flow of gas into the enclosure while the substrate carrier is closed. Numerous other aspects are provided.

Description:
[0001]     The present application claims priority from U.S. Provisional Patent Application Ser. No. 60/758,152, filed Jan. 11, 2006, which is hereby incorporated by reference herein in its entirety. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates generally to semiconductor device fabrication systems, and is more particularly concerned with transportation of substrates within a fabrication facility.  
       BACKROUND OF THE INVENTION  
       [0003]     Manufacturing of semiconductor devices typically involves performing a sequence of procedures with respect to a substrate such as a silicon substrate, a glass plate, etc. (Such substrates may also be referred to as wafers, whether patterned or unpatterned.) These steps may include polishing, deposition, etching, photolithography, heat treatment, and so forth. Usually a number of different processing steps may be performed in a single processing system or “tool” which includes a plurality of processing chambers. However, it is generally the case that other processes are required to be performed at other processing locations within a fabrication facility, and it is accordingly necessary that substrates be transported within the fabrication facility from one processing location to another. Depending upon the type of semiconductor device to be manufactured, there may be a relatively large number of processing steps required to be performed at many different processing locations within the fabrication facility.  
         [0004]     It is conventional to transport substrates from one processing location to another within substrate carriers such as sealed pods, cassettes, containers and so forth. To prevent damage to substrates transported within substrate carriers, care should be taken to ensure that substrates are not contaminated during transport with the substrate carriers. Methods and apparatus for reducing the contamination of substrates within a substrate carrier are desired.  
       SUMMARY OF THE INVENTION  
       [0005]     In some aspects, the present invention provides a substrate carrier that includes an enclosure adapted to be sealable and to house at least one substrate; and a first port leading into the enclosure adapted to allow a flow of gas into the enclosure while the substrate carrier is closed.  
         [0006]     In other aspects, the present invention provides a loadport that includes a plate adapted to couple to a door of a substrate carrier to open the substrate carrier. The plate includes a first opening adapted to couple to a first port in the door of the substrate carrier on a first side of the plate and to couple to a gas source on a second side of the plate. The loadport is adapted to allow a flow of gas into the substrate carrier via the first opening in the plate.  
         [0007]     In yet other aspects, the present invention provides a method that includes flowing a gas into a substrate carrier to create a pressure inside the substrate carrier greater than a pressure outside the substrate carrier; and opening a door of the substrate carrier to allow the gas to flow out of the substrate carrier via a door opening.  
         [0008]     In still other aspects, the present invention provides a method that includes flowing inert gas into a closed substrate carrier containing substrates; exhausting air from the substrate carrier; and sealing the substrate carrier once the air has been substantially replaced by the inert gas.  
         [0009]     In still yet other aspects, the present invention provides a method that includes evacuating air from a closed substrate carrier containing substrates; and sealing the substrate carrier once the air has been substantially removed from the substrate carrier. Numerous other aspects are provided.  
         [0010]     Other features and aspects of the present invention will become more fully apparent from the following detailed description of exemplary embodiments, the appended claims and the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE FIGURES  
       [0011]      FIG. 1  is cross-sectional top view of a conventional substrate carrier.  
         [0012]      FIG. 2  is an isometric view of a substrate carrier in accordance with an embodiment of the present invention.  
         [0013]      FIG. 3A  is an isometric view of a purge port in accordance with an embodiment of the present invention.  
         [0014]      FIG. 3B  is an isometric view of an exhaust port in accordance with an embodiment of the present invention.  
         [0015]      FIG. 4A  is a plan side view of a loadport and a substrate carrier in accordance with an embodiment of the present invention.  
         [0016]      FIG. 4B  is an isometric front view of a plate for opening a substrate carrier door in accordance with an embodiment of the present invention.  
         [0017]      FIG. 5  is an isometric rear view of the plate of  FIG. 4B  in accordance with an embodiment of the present invention.  
         [0018]      FIG. 6  is cross-sectional top view of the substrate carrier of  FIG. 2  in accordance with an embodiment of the present invention.  
         [0019]      FIG. 7  illustrates exemplary purge gas flow in a second exemplary substrate carrier in accordance with an embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0020]     During semiconductor device manufacturing, one or more substrates may be transported inside a conventional substrate carrier. However, opening a door of a conventional substrate carrier may adversely affect semiconductor device manufacturing. For example,  FIG. 1  is cross-sectional top view of a conventional substrate carrier  101 . With reference to  FIG. 1 , the conventional substrate carrier  101  includes an enclosure  103  for defining a storage area  105  in which one or more substrates  107  (shown in phantom) may be stored. A door  109  is provided that may be used for sealing the substrate carrier  101  by sealing against the enclosure  103 . In this manner, the door  109  may separate a first environment within the substrate carrier  101  from a second environment outside the substrate carrier  101 .  
         [0021]     During a typical semiconductor device manufacturing process, the pressure P 1  inside the substrate carrier  101  is the same as the pressure P 2  (e.g., ambient pressure) outside the substrate carrier  101 . Accordingly, when the door  109  is opened to insert a substrate into and/or extract a substrate from the substrate carrier  101 , the pressure P 1  in the substrate carrier  101  decreases (due to the outward motion of the door  109 ) and gas (e.g., ambient air) from outside the substrate carrier  101  flows into the substrate carrier  101 .  FIG. 1  illustrates an exemplary flow  111  of such gas into the substrate carrier  101 .  
         [0022]     Because the environment outside the substrate carrier  101  may contain contaminants, allowing flow of the gas into the substrate carrier  101  may introduce contaminants to any substrates within the substrate carrier  101 . In accordance with the present invention, gas (e.g., purging gas) is flowed into a substrate carrier before, during and/or after opening a door of the carrier so as to reduce and/or prevent gas outside of the substrate carrier from entering the substrate carrier as the substrate carrier is opened. Details of the present invention are described below with reference to  FIGS. 2-7 .  
         [0023]      FIG. 2  is an isometric view of a substrate carrier  201  in accordance with an embodiment of the present invention. With reference to  FIG. 2 , the substrate carrier  201  includes an enclosure  203  for defining a storage area (not shown in  FIG. 2 ;  601  in  FIG. 6 ) in which one or more substrates  205  may be stored. The substrate carrier  201  includes a door  207  that may be used to seal the substrate carrier  201  relative to the enclosure  203 . The door  207  may separate a first environment within the substrate carrier  201  from a second environment outside the substrate carrier  201 .  
         [0024]     The substrate carrier  201  includes one or more purge ports  209  adapted to allow a flow of gas, such as air (e.g., clean dry air), N 2 , argon, another inert gas or the like, into the substrate carrier  201  before, during and/or after the door  207  is opened (e.g., moved along the x-axis). Details of the one or more purge ports are described below with reference to  FIG. 3A .  
         [0025]     The substrate carrier  201  includes one or more exhaust ports  211  for expelling gas from the substrate carrier  201  (e.g., gas provided to the substrate carrier  201  via the purge ports  209  while the door  207  is being removed). In this manner, the one or more exhaust ports  211  may prevent over-pressurization of the substrate carrier  201 . In the embodiment of  FIG. 2 , the purge ports  209  and the exhaust port  211  are located on the door  207 . However, the purge ports  209  and/or exhaust port  211  may be positioned differently. For example, in some embodiments, the enclosure  203  may include one or more purge ports  209  and/or one or more exhaust ports  211 . Further, the substrate carrier  201  may include a larger or smaller number of purge ports  209  and/or exhaust ports  211 . In some embodiments, a filter  309 ′ ( FIG. 3B ) may be coupled to an exhaust port  211  such that a gas flowing through the exhaust port  211  passes through and is filtered by the filter before exiting the substrate carrier  201  (e.g., so as to prevent any contaminants within the substrate carrier  201  from escaping). Each purge port  209  similarly may include a filter (as described below).  
         [0026]      FIG. 3A  is an isometric view of a purge port  209  in accordance with an embodiment of the present invention. With reference to  FIG. 3A , the purge port  209  includes a center opening (e.g., hole)  301  adapted to pass a flow (e.g., one-way flow) of gas into the substrate carrier  201 . A filter  309  may be coupled to the center opening  301  such that a gas flowing through the center opening  301  passes through the filter  309  before entering the substrate carrier  201 . Although, the center opening  301  of the substrate carrier  201  is shown as a hole, other shapes may be employed for the center opening  301 .  
         [0027]     The purge port  209  may include a first seal  303 , such as an O-ring, suction cup or the like, surrounding the center opening  301 . The first seal  303  surrounding the center opening  301  ensures a proper seal between the center opening  301  and an upstream source of gas that flows through the center opening  301 .  
         [0028]     In embodiments in which the purge port  209  is included in the substrate carrier door  207 , when gas (e.g., pressurized gas) flows through the center opening  301  (e.g., and through the filter) a force pushing the door  207  in the direction of the gas flow (e.g., away from the source of the gas flow) is exerted on the door  207 . Therefore, the purge port  209  includes a second seal  305  (e.g., O-ring, suction cup or the like) around the first seal  303  that defines an area  307  concentric to the center opening  301  between the first and second seals  303 ,  305 . A vacuum force may be applied to the concentric area  307  to counteract the force exerted on the door  207  while inserting gas into the substrate carrier  201 . The concentric area  307  and area of the center opening  301  are dimensioned such that the vacuum force applied to the concentric area  307  is greater than the force applied to the door  207  by the flow of gas into the substrate carrier  201 . Further, concentricity of the area  307  and the center opening  301  ensures that resulting moment loads are substantially zero.  
         [0029]     In some embodiments, the exhaust port  211  may be similar to the purge ports  209 .  FIG. 3B  is an isometric view of an exhaust port  211  in accordance with an embodiment of the present invention. With reference to  FIG. 3B , the purge port  211  includes a center opening (e.g., hole)  301 ′ adapted to pass a flow (e.g., one-way flow) of air or gas out of the substrate carrier  201 . A filter  309 ′ may be coupled to the center opening  301 ′ such that air flowing through the center opening  301 ′ passes through the filter  309 ′ before exiting the substrate carrier  201 . Although, the center opening  301 ′ of the substrate carrier  201  is shown as a hole, other shapes may be employed for the center opening  301 ′.  
         [0030]     The exhaust port  211  may include a first seal  303 ′, such as an O-ring, suction cup or the like, surrounding the center opening  301 ′. The first seal  303 ′ surrounding the center opening  301 ′ ensures a proper seal between the center opening  301 ′ and an exhaust channel used to carry air/gas that flows through the center opening  301 ′.  
         [0031]     In embodiments in which the exhaust port  211  is included in the substrate carrier door  207 , when air or gas (e.g., pressurized gas) flows through the center opening  301 ′ (e.g., and through the filter) a force pushing the door  207  in the direction of the gas flow (e.g., away from the substrate carrier  201 ) is exerted on the door  207 . Therefore, the exhaust port  211  includes a second seal  305 ′ (e.g., O-ring, suction cup or the like) around the first seal  303 ′ that defines an area  307 ′ concentric to the center opening  301 ′ between the first and second seals  303 ′,  305 ′. A vacuum force may be applied to the concentric area  307 ′ to counteract the force exerted on the door  207  while removing air or gas from the substrate carrier  201 . The concentric area  307 ′ and area of the center opening  301 ′ are dimensioned such that the vacuum force applied to the concentric area  307 ′ is greater than the force applied to the door  207 ′ by the flow of air or gas out of the substrate carrier  201 . Further, concentricity of the area  307 ′ and the center opening  301 ′ ensures that resulting moment loads are substantially zero. Other purge port and/or exhaust port configurations may be used.  
         [0032]     Turning to  FIG. 4A , during semiconductor device manufacturing, a substrate carrier  201  may be supported by a loadport  400  or similar supporting structure and a substrate may be inserted into or extracted from the substrate carrier  201 . For example, the loadport  400  may include a plate  401  or similar structure for opening a substrate carrier door  207  ( FIG. 2 ) as described below with reference to  FIG. 4B .  
         [0033]      FIG. 4B  is an isometric front view of an exemplary plate  401  for opening a substrate carrier door  207  in accordance with an embodiment of the present invention. With reference to  FIGS. 4A and 4B , the plate  401  may be included in a loadport  400 . The plate  401  is adapted to couple to a substrate carrier door  207  which is supported by (e.g., docked in) the loadport  400 .  
         [0034]     The plate  401  includes a purge opening (e.g., hole)  403  corresponding to each center opening  301  of each purge port  209  included in a door  207  to which the plate  401  is to be coupled. Each purge opening  403  is adapted to mate with a center opening  301  of a door  207  such that the first seal  303  of the center opening  301  forms a seal around the purge opening  403 , and therefore, between the center opening  301  and corresponding purge opening  403 . The purge opening  403  is adapted to deliver purge gas to the center opening  301 . Although the purge opening  403  is shown as a hole, other shapes may be employed for the purge opening  403 . Further, in some embodiments, a nipple or similar structure (not shown) may couple to or replace the purge opening  403  such that the nipple mates with the center opening  301  of the purge port  209  when the door  207  is coupled to the front of the plate  401 .  
         [0035]     Similarly, the plate  401  may include a vacuum opening (e.g., hole)  405  corresponding to each concentric area  307  of the one or more purge ports  209  included in the door  207  to which the plate  401  is adapted to couple. An area of the plate  401 , which is around the vacuum opening  405 , couples to the second seal  305  of a door  207 , thereby forming a sealed volume between the plate  401 , door  207 , and first and second seals  303 ,  305 . The vacuum opening  405  is adapted to deliver a vacuum to such volume. Although the vacuum opening  405  is shown as a hole, other shapes may be employed for the vacuum opening  405 . Further, although the first and second seals  303 ,  305  are included in the door  207 , in some embodiments, the first and/or second seal  303 ,  305  may be included in the plate  401 .  
         [0036]     The plate includes an exhaust opening (e.g., hole)  407  corresponding to each exhaust port  211  included in the door  207 . The exhaust opening  407  is adapted to expel air or gas from the substrate carrier  201 . In embodiments in which an exhaust port  211  includes a (concentric) vacuum area (e.g., between first and second seals), the plate  401  may include a vacuum opening (not shown) for applying vacuum to the vacuum area of the exhaust port  211 . In at least one embodiment, a nipple or similar structure (not shown) may be used in place of the exhaust opening  407  and/or any vacuum opening.  
         [0037]      FIG. 5  is an isometric rear view of the plate  401  of  FIG. 4B  coupled to a substrate carrier  201  in accordance with an embodiment of the present invention. With reference to  FIG. 5 , when a substrate carrier  201  is supported by a loadport  400  ( FIG. 4A —not shown in  FIG. 5 ) that employs the plate  401 , the door  207  (obstructed in  FIG. 5 ) of the substrate carrier  201  couples (e.g., docks) with the front of the plate  401 . The rear of the plate  401  is adapted to couple to a source of gas (e.g., purge gas), vacuum and/or exhaust. More specifically, a gas fitting  501  is coupled to each purge opening  403  ( FIG. 4B ) on the rear side of the plate  401 . Each gas fitting  501  is adapted to deliver gas (e.g., pressurized purge gas such as nitrogen, argon, clean dry air, an inert or nonreactive gas, etc.) into the substrate carrier  201  through the purge opening  403  and center opening  301 . Similarly, a vacuum fitting  503  is coupled to each vacuum opening  405  on the rear side of the plate  401 . Each vacuum fitting  503  is adapted to deliver a vacuum to the sealed volume formed between the plate  401 , door  207 , and first and second seals  303 ,  305 . In at least one embodiment, the vacuum delivered to the sealed volume may be greater than the force exerted by the gas flow into the center opening  301  of the door  207  (e.g., while opening the substrate carrier door  207 ). In this manner, the plate  401  remains coupled to the substrate carrier door  207  while gas flows through the center opening  301  into the substrate carrier  201  (e.g., as the plate  401  opens the door  207 ).  
         [0038]     Further, an exhaust fitting  505  is coupled to each exhaust opening  407  ( FIG. 4B ) on the rear side of the plate  401 . Each exhaust fitting  505  is adapted to expel one or more gases from the substrate carrier  201 . Note that if the enclosure  203  includes one or more purge ports  209  and/or one or more exhaust ports  211 , a corresponding fitting(s) may couple to each such port on the enclosure  203 . Further, if the exhaust port  211  includes a vacuum area, an additional vacuum fitting  503  may be provided for applying vacuum thereto.  
         [0039]      FIG. 6  is cross-sectional top view of the substrate carrier  201  in accordance with an embodiment of the present invention. With reference to  FIG. 6 , the door  207  of the substrate carrier  201  is being removed (e.g., via the plate  401  (not shown)). As stated, the door  207  may be opened to insert a substrate into and/or extract a substrate from a storage region  601  of the substrate carrier  201  during semiconductor device manufacturing. As the door  207  is removed, the door  207  may move along the x-axis. As the door  207  is being removed, a region of low pressure  603  having a volume equal to a volume of the displaced door  207  is created. In conventional semiconductor device manufacturing systems and as previously described with reference to  FIG. 1 , as a substrate carrier door  109  ( FIG. 1 ) is removed, ambient air (e.g., ISO Class 1000) flows around the door  109  into the substrate carrier  103  to occupy any such a low-pressure region.  
         [0040]     In contrast, according to the present methods and apparatus, gas (e.g., purge gas) is delivered to the substrate carrier  201  via the one or more purge ports  209  before, during and/or after the door  207  is opened. The purge gas fills the low pressure region  603 . For example, a volume of purge gas may be delivered such that a positive pressure is created inside the substrate carrier  201 . The purge gas increases the pressure inside the substrate carrier  201  such that the pressure within the substrate carrier  201  is greater than ambient pressure. Therefore, gas flows from inside to outside the substrate carrier  201  as the door  207  is opened. Consequently, excess purge gas delivered to the substrate carrier  201  through the purge ports  209  may be expelled from the substrate carrier  201  around the edges of the substrate carrier door  207  as the door  207  is opened.  FIG. 6  illustrates an exemplary flow  605  of such gas into and from the substrate carrier  201 . Other flow patterns may be used.  
         [0041]     Additionally, excess purge gas may be expelled from the exhaust port  211  as the door  207  is opened. Further, while purge gas for creating a positive pressure inside the substrate carrier  201  is delivered, the exhaust port  211  may expel purge gas from the substrate carrier  201  to prevent over-pressurization inside the substrate carrier  201 . In this manner, the exhaust port  211  may serve as an over-pressure relief valve.  
         [0042]     As purge gas is delivered through the one or more purge ports  209 , such as while the door  207  is opened, a vacuum may be delivered via the vacuum opening  405  ( FIG. 4B ) of the plate  401  to the sealed volume between the plate  401 , door  207 , and first and second seals  303 ,  305 . As stated, the vacuum resists a force created by flowing the purge gas into the center opening  301  of the purge port  209 , thereby securing the door  207  to the plate  401 .  
         [0043]      FIG. 7  illustrates exemplary purge gas flow in a second exemplary substrate carrier  701  in accordance with an embodiment of the present invention. With reference to  FIG. 7 , the second exemplary substrate carrier  701  is similar to the substrate carrier  201  of  FIGS. 2-3B  and  5 - 6 . However, in contrast to the substrate carrier  201  of  FIGS. 2-3B  and  5 - 6 , the second exemplary substrate carrier  701  includes one or more features, such as channels or baffles  703  (shown in phantom). (For example, the channels or baffles  703  may be positioned along and/or formed within a bottom interior surface, top interior surface and/or side of an enclosure  705  of the second exemplary substrate carrier  701 ). The one or more channels or baffles  703  may be shaped and/or positioned differently.  
         [0044]     In some embodiments, the second exemplary substrate carrier  701  may create a laminar flow of the purge gas inside the substrate carrier  701 . Further, as a door  707  of the second exemplary substrate carrier  701  is opened, the channels or baffles  703  may cause purge gas delivered inside the second exemplary substrate carrier  701  to flow from the front to the back of the substrate carrier  701  below a substrate  709  stored in the substrate carrier  701  and from the back to the front of the substrate carrier  701  over the substrate  709  (or vice versa). Preferably, purge gas flow around the substrate  709  may be uniform. The above gas flow may release loose particles from a surface of the substrate  709 .  FIG. 7  illustrates an exemplary flow  711  of gas in the substrate carrier  701 . Other flow patterns may be used. For instance, the channels or baffles  703  may deliver a gas to the back of the substrate carrier  701  that (simultaneously) flows toward the front of the substrate carrier  701  over both the top and bottom surfaces of the substrate  709 .  
         [0045]     The foregoing description discloses only exemplary embodiments of the invention. Modifications of the above disclosed apparatus and methods which fall within the scope of the invention will be readily apparent to those of ordinary skill in the art. For instance, although the substrate carrier  201 ,  701  is shown as a Front Opening Unified Pod (FOUP), in some embodiments, other types of substrate carriers, such as top-opening or bottom-opening substrate carriers may be employed. Further, although in some embodiments, the plate  401  is included in a loadport, the plate  401  may be included in any support structure to which a substrate carrier  201 ,  701  couples. Although the present methods and apparatus are described with reference to a small lot sized substrate carrier, substrate carriers of any size may employ the present methods and apparatus.  
         [0046]     In some embodiments, the purge ports  209  may be used to fill the substrate carrier  201 ,  701  with inert gas (e.g., N2, argon, etc.) after substrates are processed, placed in the carrier  201 ,  701  and the door  207 ,  707  is closed. In this way, the substrates are stored in an environment that does not allow oxidation of the films on the substrates (e.g., to prevent degradation of the films due to prolonged exposure to air). Similarly, in some embodiments, the purge ports  209  and/or the exhaust port  211  may be used to evacuate the substrate carrier  201 ,  701  after substrates are processed, placed in the substrate carrier  201 ,  701  and the door  207 ,  707  is closed. The purge ports  209  then may be used to re-introduce air into the carrier  201 ,  701  when the carrier  201 ,  701  is ready to be opened again.  
         [0047]     As used herein, a “small lot” size substrate carrier refers to a substrate carrier that is adapted to hold a maximum of significantly fewer substrates than a conventional “large lot” size substrate carrier which typically holds 13 or 25 substrates. As an example, in one embodiment, a small lot size substrate carrier is adapted to hold a maximum of 5 or less substrates. Other small lot size substrate carriers may be employed (e.g., small lot size carriers that hold a maximum of 1, 2, 3, 4, 5, 6, 7 or more substrates, but significantly less than that of a large lot size substrate carrier). For example, in one embodiment, each small lot size substrate carrier may hold too few substrates for human transport of substrates carriers to be viable within a semiconductor device manufacturing facility.  
         [0048]     Accordingly, while the present invention has been disclosed in connection with exemplary embodiments thereof, it should be understood that other embodiments may fall within the spirit and scope of the invention, as defined by the following claims.