Abstract:
A substrate container having an enclosure with an access opening for inserting and removing substrates into an interior of the enclosure and a door chassis that is configured to selectively enclose the opening, the door chassis comprising a first wall having a peripheral wall extending therefrom. The substrate container includes a latch mechanism that is operably coupled with the chassis, the latch mechanism configured to operably secure the chassis to the opening. The door of the substrate container includes a textured particle capture region wherein particles generated by the latch mechanism and elsewhere are captured by the particle capture region.

Description:
This application claims priority to U.S. Provisional Application 60/563,526, filed Apr. 18, 2004, entitled “WAFER CONTAINER DOOR WITH PARTICULATE COLLECTING STRUCTURE,” which is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to substrate containers. More particularly, the present invention relates to substrate container doors having textured regions to trap and prevent the circulation of particles or particulates that are generated within the containers. 
     BACKGROUND OF THE INVENTION 
     Substrate containers are used in the semiconductor processing industry for storing and transporting semiconductor wafers, flat panel substrates, and film frames. Examples of containers that are used in the semiconductor processing industry are FOUPs (front opening unified pods), FOSBs (front opening shipping box), and SMIF (standardized mechanical interface) pods. Such containers generally have an enclosure with an open bottom or side that is sealingly closed by a door. The doors often have an interior compartment with a latch mechanism that is visible through a clear or transparent plastic door panel, which is usually formed of polycarbonate. 
     Processing of semiconductor wafers into finished electronic components typically requires many processing steps during which the wafers must be handled and processed. The wafers are very valuable, extremely delicate, and easily damaged by physical and electrical shocks. In addition, successful high-yield processing requires maximum cleanliness and freedom from particles or particulates and other contaminants. Because of this requirement, specialized containers or carriers have been developed for use during processing, handling, and transport of wafers. These containers protect the wafers from physical and electrical hazards and are sealable to protect the wafers from contaminants. Such wafer carriers or containers generally comprise an enclosure having a number of wafer holding shelves inside. One side of the container is open for access but can be enclosed by a door. The doors generally have a latch mechanism to securely retain and seal it in place. Normally, the latch mechanism is enclosed to protect it from damage and accidental actuation. 
     Although wafer enclosures are used in clean environments, undesirable contaminants can accumulate on and in the enclosure over time. Particulate contaminants are generated through frictional contact between parts of the enclosure and in the operation of loading and unloading wafers from the enclosure. Accordingly, an important characteristic for wafer containers is that they must be thoroughly cleanable to ensure that process cleanliness is maintained. Cleaning is generally accomplished with a liquid solution and the parts are dried afterward with compressed air or other gas. 
     Semiconductor wafer fabrication processes are often extremely sensitive to any contamination. Contaminants can be generated in various ways, e.g., by sliding contact of components, such as latching mechanism components, within the substrate container door. As substrate containers are used over time, they can generate and accumulate particulates. Over time, the particulate formation can result in visible smudging, smearing, and/or clouding of the transparent plastic door panels. While this presents an undesirable aesthetic result, such contaminants and particles or particulates also present the risk of entering the enclosure and contaminating the wafers. 
     Because the general problems discussed above have not been addressed by conventional wafer containers, there is a current need for a wafer container addressing the problems and deficiencies inherent with conventional designs. 
     SUMMARY OF THE INVENTION 
     The wafer container of the embodiments of the present invention substantially addresses the aforementioned problems of conventional designs by providing a particle capture feature that collects and captures particles or particulates and substantially alleviates the negative visible effects of such particulates and contamination. 
     A wafer container having an enclosure with an access opening for inserting and removing wafers into an interior of the enclosure and a door chassis that is configured to selectively enclose the opening. In a SMIF pod configuration, the door includes a top wall having a peripheral wall extending downwardly therefrom defining an door chassis interior. The wafer container includes a latch mechanism that is operably coupled with the chassis, the latch mechanism configured to operably secure the chassis to the opening. The wafer container also includes a panel including a particle capture region that is defined on an inner surface thereof, the panel configured to detachably couple the chassis, such that when the panel couples the chassis, the inner surface and chassis define a chassis interior, wherein particles or particulates generated by the latch mechanism are captured by the particle capture region. 
     A feature and advantage of embodiments of the invention is that the particles or particulates are trapped by the isolated textured region and obstructed from circulating within the door and potentially coming into contact with the wafers. 
     Another feature and advantage of embodiments of the invention is that the accumulation of particulates as exemplified by smudging or clouding on the transparent surface is eliminated or reduced. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a bottom perspective view of a wafer container with a door according to an embodiment of the present invention; 
         FIG. 2  is an exploded view of a wafer container having a door and a wafer tray according to an embodiment of the present invention; 
         FIG. 3  is a bottom exploded view of the door of a wafer cassette according to an embodiment of the present invention; 
         FIG. 4  is a perspective view of a panel of the door according to an embodiment of the present invention; 
         FIG. 5  is a close-up view of a panel depicting undulating geometry on the inside surface of the panel according to an embodiment of the present invention; 
         FIG. 6   a  is a top plan view of the inside surface of a panel having a particle capture region with concentric ribbing according to an embodiment of the present invention; 
         FIG. 6   b  is a cross-sectional view of the particle capture region of  FIG. 6   a;    
         FIG. 7   a  is a top plan view of the inside surface of a panel having a particle capture region with linear ribbing according to an embodiment of the present invention; 
         FIG. 7   b  is a cross-sectional view of an embodiment of the particle capture region of  FIG. 7   a;    
         FIG. 8  is a cross-sectional view of an alternative embodiment of the particle capture region of  FIG. 7   a;    
         FIG. 9   a  is a top plan view of the inside surface of the panel with a particle capture region having cross-hatched ribbing according to an embodiment of the present invention; 
         FIG. 9   b  is a cross-sectional view of depicting a geometry created by the crosshatched ribbing of  FIG. 9   a ; and 
         FIG. 9   c  is a cross-sectional view of depicting a particle capture region with random geometry created by the crosshatched ribbing according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A substrate container  20  for carrying substrates is depicted in  FIGS. 1-3 . Referring to  FIG. 2 , wafer container  20  generally includes an enclosure  22  having a door frame  24  defining access opening  26  for accessing interior  28  of container  20 , cassette  30  having a plurality of slots  32  for receiving and holding wafers (not depicted), and door  40  for sealably closing access opening  26 . Door  40  generally includes door chassis portion  40 A and panel portion  40 B. Door  40  may include a plurality of kinematic coupling grooves  41  for locating and securing container  20  on a piece of processing equipment (not depicted). Door  40  may also include locating structures  41 A for receiving and retaining cassette  30 . Referring to  FIG. 3 , door  40  may include top wall  42  and peripheral wall  44  extending away from top wall  42 . Peripheral wall  44  and top wall  42  define interior space  46  of door  40 . Door  40  may include a gasket  47  along door periphery  47 A for sealingly engaging enclosure portion  22 . Door guides  47 B may be provided at each corner  47 C to accurately locate door  40  in door frame  24 . 
     Door  40  may also include at least one latch mechanism  50  disposed in interior space  46  of door  40  for securing door  40  in door frame  24  of enclosure  22 . Latch mechanism  50  may include a pair of latch arms  52 (A),  52 (B), pivotally coupled to lower surface (not depicted) of top wall  42 . Each of latch arms  52 (A),  52 (B), is retractably extendable through openings  44 A in peripheral wall  44  of door  40  and each is configured to latch to door frame  24  of enclosure  22  for securing door  40  in door frame  24 . Cam  53  is rotatably coupled to the lower surface of top wall  42  and is coupled with each of latch arms  52 (A),  52 (B), so that rotation of cam  53  simultaneously moves each of latch arms  52 (A),  52 (B) laterally through openings  43 A to engage and disengage from door frame  24 . An example of a wafer container having a door with a latch mechanism contained therein is disclosed in U.S. Pat. No. 6,749,067, owned by Applicant, which is incorporated herein by reference. 
     Although the actuating portion of latch mechanism  50  is depicted and described herein as a rotating cam, any other suitable member or mechanism capable of imparting a linear sliding motion to latch arms  52 (A),  52 (B), can be used, including a rack and pinion mechanism such as depicted in PCT Application No. WO 01/04022 A1 also hereby incorporated herein by reference. Further details of a cam-operated latching mechanism suitable for use with the various embodiments of the present invention are disclosed in U.S. Pat. No. 6,712,213 and co-pending patent applications Ser. Nos. 10/317,023, and 10/318,374, each incorporated herein by reference. 
     Referring to  FIGS. 3-5 , panel  40 B in the form of transparent panel  70  may be removably coupled to peripheral wall  44  of door  40  for enclosing interior  48 . Clips  70 A engage in receiving structures  70 B on chassis  40 A. While, in an embodiment, panel  70  is transparent, panel  70  may also be non-transparent without departing from the scope of the present invention. Panel  70  has an upper or inside surface  72 , as depicted in  FIGS. 3 and 4  and a lower or outside surface  74  as depicted in  FIGS. 1 and 2 . When coupled to peripheral wall  44  of door  40 , upper surface  72  of panel  70  faces interior  46  of door  40 . In one embodiment of the invention, panel  70  has a pair of openings  76  extending therethrough for providing access to cam  53 . As particularly depicted in  FIG. 6 , the pair of openings  74  may have a generally oval configuration, however, other configurations are also possible. 
     In an embodiment, inside surface  72  of transparent panel  70  may include particle capture regions  75  in the form of discrete textured regions  80  to trap and prevent the dissemination of particles or particulates generated by moving components disposed in interior  46  confronting each other or any other portion of door  40  or transparent panel  70 . While, in an embodiment, textured region  80  is isolated, a plurality of textured regions  80  can be distributed on inner surface  72  without departing from the scope of the present invention. The discrete textured portion  80  of transparent panel  70  may be positioned anywhere on inside surface  72  of transparent panel  70 . As particularly illustrated in  FIGS. 4-7 , textured portion  80  is positioned generally adjacent to cam  53  and proximate openings  74 . In various embodiments, textured region  80  may be positioned generally proximate any moving components such that generated particles or particulates fall into textured region  80  and become trapped therein. In another embodiment of the invention, varying degrees of inside surface  72  are textured. Textured region  80  may also serve as a bearing surface with the texturing configured suitably for such bearing surface. 
     Any mechanical, chemical or optical process may be used to impart a texture into inside surface  72  of transparent panel  70 . For example, textured region  80  will typically be made by molding, but alternatives such as etching or laser machining may be appropriate in certain applications. Also for example, a preformed piece or film with suitable, texturing, and surface properties may be insert molded into the cover. Such preformed textured portion may also serve as a bearing surface. Other processes may also be used without departing from the scope of the present invention. 
     Referring to  FIGS. 6   a - 9   b , various textures may be used to create the textured region  80 . For example, as depicted in  FIGS. 6   a ,  6   b  inside surface  72  of transparent panel  70  may consist of a plurality of concentric ribs  73 . As depicted in  FIG. 6   b , the concentric ribs  73  may have a generally undulating cross sectional geometry. In the alternative embodiment of  FIGS. 7   a ,  7   b ,  8 , textured region  80  may include linear ribs  81 . The linear ribbing may have varying cross sectional geometries. For instance, as depicted in  FIG. 7   b , a v-notched cross sectional geometry may be formed into inside surface  72  to form textured surface  80  of particle capture region  75 . As depicted in  FIG. 8 , a square-notched cross sectional geometry may also be formed. In another embodiment, as depicted in  FIG. 9   a , crosshatched ribs  83  may be formed on inside surface  72  of transparent panel  70  to form textured surface  80  of particle capture region  75 . As particularly illustrated in  FIGS. 9   b  and  9   c , an irregular and/or complex cross sectional geometry may also be formed on inside surface  72  to form textured surface  80  of particle capture region  75 . Other cross sectional geometric shapes are envisioned within the scope of the invention and those discussed should not be considered limiting. 
     In other embodiments, textured region  80  may be imparted onto inside surface  72  of transparent panel  70  by adhering a film having a textured upper surface. The textured film permits a user to position textured region  80  anywhere particles or particulates are being generated. In yet another embodiment, an adhesive may be positioned on inside surface  72  of transparent panel  70  to capture any particulates that may be generated. 
     In operation, textured region  80  is imparted on to or into inside surface  72  of transparent panel  70  at the time of manufacture. As wafer container  20  is being used, the various moving components disposed in interior  46  of door  40  generate particles or particulates. Because transparent panel  70  is disposed below door  70 , the particulates will fall onto inside surface  72  of transparent panel  70 . As the particulates fall onto inside surface  72  they become trapped in textured region  80 , thereby preventing circulation of the particulates through interior  46  of door  70  and potentially coming into contact with the enclosed wafers. When a user desires to remove the particles from the interior of door  46  and textured region  80 , the user simply detaches panel  70  from door  46 , removes the particles, and replaces panel  70  on door  46 . 
     Although the present invention has been described with reference to particular embodiments, one skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and the scope of the invention. Therefore, the illustrated embodiments should be considered in all respects as illustrative and not restrictive.