Patent Document

BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to apparatus for liquid treatment of wafer-shaped articles. 
     2. Description of Related Art 
     Semiconductor wafers undergo a variety of wet processing stages during manufacture of integrated circuits. To accommodate such processes, a single wafer may be supported in relation to one or more treatment fluid nozzles by a chuck associated with a rotatable or non-rotatable carrier. 
     U.S. Pat. Nos. 4,903,717 and 5,513,668 describe such chucks wherein a plurality of pins assemblies arranged in a circular series contact a peripheral edge of the wafer. The contact surfaces of the pin assemblies are eccentric to the rotational axes of the pin assemblies, and can thus be driven in unison by a common ring gear between a radially inward use position and a radially outward loading and unloading position. Commonly-owned copending application U.S. 2010/0206481 describes a variation on such pin assemblies in which the contact surfaces of the pin assemblies support the weight of the wafer, and position the wafer at a fixed height above the upper plate of the chuck. 
     More recent versions of such chucks have included heating assemblies that are positioned above the upper plate of the chuck but below the level where a wafer is supported, an example of such a chuck being described in commonly-owned copending application U.S. 2013/0061873. 
     The repair and maintenance of such chucks is relatively complicated and time-consuming, because, in order to replace even one of the pin assemblies, the chuck has to be disassembled from its associated drive and elevating unit, removed from its associated process module, and dismantled to its individual components under clean room conditions. This operation is especially time-consuming in the case of chucks equipped with heating assemblies as identified above, because the entire lamp housing has to be removed before the chuck itself can be removed from its associated drive unit. 
     SUMMARY OF THE INVENTION 
     Thus, in one aspect, the present invention relates to an apparatus for processing wafer-shaped articles, comprising a rotary chuck adapted to hold a wafer shaped article thereon. The rotary chuck comprises a peripheral series of pins configured to contact an edge region of a wafer-shaped article. Each of the pins projects upwardly from the rotary chuck, and each of the pins is individually secured to the rotary chuck by a respective connecting mechanism. Any selected one of the pins can be removed from the rotary chuck by disconnecting its corresponding connecting mechanism without removing any structure of the rotary chuck that surrounds any others of the pins. 
     In preferred embodiments of the apparatus according to the present invention, the rotary chuck comprises a chuck base body and a cover, and wherein each of the pins projects upwardly from the cover. 
     In preferred embodiments of the apparatus according to the present invention, the rotary chuck is mounted for rotation about a central spindle, and a heating assembly is stationarily mounted above an upper surface of rotary chuck and below a level at which the pins contact an edge of a wafer-shaped article. 
     In preferred embodiments of the apparatus according to the present invention, each connecting mechanism comprises an insert having an opening through which an upper part of a corresponding pin can pass, each the pin comprises a base portion that is wider than the opening in its corresponding insert, and each insert is received in a corresponding recess formed in an upper surface of the rotary chuck and is fastened to the rotary chuck with the base portion of a corresponding pin captive within the rotary chuck beneath the insert. 
     In preferred embodiments of the apparatus according to the present invention, when the connecting mechanism is disconnected from the rotary chuck, the corresponding pin and insert can be lifted conjointly away from the chuck by pulling upwardly on the corresponding pin. 
     In preferred embodiments of the apparatus according to the present invention, a ring gear is mounted interiorly of the chuck, the ring gear being in simultaneous meshing engagement with each of the circular series of pins. 
     In preferred embodiments of the apparatus according to the present invention, each of the circular series of pins has an enlarged base confined within the rotary chuck and comprises gear teeth meshing with the ring gear. 
     In preferred embodiments of the apparatus according to the present invention, the insert is secured to the rotary chuck by a pair of screws. 
     In preferred embodiments of the apparatus according to the present invention, each of the pair of screws has a collar that keeps the screw attached to the insert. 
     In preferred embodiments of the apparatus according to the present invention, the insert comprises screw threading on a lower surface thereof and is screwed into a threaded bore formed with the recess. 
     In preferred embodiments of the apparatus according to the present invention, an O-ring is mounted in a groove surrounding the recess, to prevent ingress of liquid into the rotary chuck between the insert and the recess. 
     In preferred embodiments of the apparatus according to the present invention, a lip seal is mounted between the insert and a shoulder of the recess, to prevent ingress of liquid into the rotary chuck between the insert and the recess. 
     In preferred embodiments of the apparatus according to the present invention, each of the series of pins and its associated connecting mechanism is made from one or more chemically-resistant plastics selected from the group consisting of polytetrafluoroethylene (PTFE), perfluoroalkoxy (PFA), polyphenylenesulfide (PPS), polyetheretherketone (PEEK), polystyrene/polyethylstyrene (PS/PES), ethylene tetrafluoroethylene (ETFE), polyvinylidene fluoride (PVDF), homopolymer of chlorotrifluoroethylene (PCTFE), fluorinated ethylene propylene (FEP), and ethylene chlorotrifluoroethylene (ECTFE). 
     In another aspect, the present invention relates to a rotary chuck for processing wafer-shaped articles, the rotary chuck being adapted to hold a wafer shaped article thereon. The rotary chuck comprises a peripheral series of pins configured to contact an edge region of a wafer-shaped article. Each of the pins projects upwardly from an upper plate of the rotary chuck, and each of the pins is individually secured to the upper plate by a respective connecting mechanism. Any selected one of the pins can be removed from the rotary chuck by disconnecting its corresponding connecting mechanism without removing the upper plate. 
     In preferred embodiments of the rotary chuck according to the present invention, each connecting mechanism comprises an insert having an opening through which an upper part of a corresponding pin can pass, and each pin comprises a base portion that is wider than the opening in its corresponding insert. Each insert is received in a corresponding recess formed in the upper plate and is fastened to the rotary chuck with the base portion of a corresponding pin captive within the rotary chuck beneath the insert. 
     In preferred embodiments of the rotary chuck according to the present invention, when the connecting mechanism is disconnected from the rotary chuck, the corresponding pin and insert can be lifted conjointly away from the chuck by pulling upwardly on the corresponding pin. 
     In yet another aspect, the present invention relates to an upper plate assembly for use in a rotary chuck for processing wafer-shaped articles, comprising an upper plate having formed therein a circular series of openings whose size and position is selected to allow a corresponding one of a peripheral series of pins to pass through a respective one of the openings when the upper plate is mounted on a rotary chuck. Each of the openings adjoins a corresponding recess formed in an upper surface of the upper plate. The assembly includes a set of inserts, a respective one of the inserts corresponding to each of the recesses, the inserts each having a hole through which an upper part of one of a peripheral series of pins can pass when the insert is received in its corresponding recess and when the upper plate is mounted on a rotary chuck. Each of the inserts is individually connectable to the upper plate by a respective connecting mechanism. 
     In preferred embodiments of the upper plate assembly according to the present invention, each the insert is secured to the upper plate by a pair of screws. 
     In preferred embodiments of the upper plate assembly according to the present invention, each of the pair of screws has a collar that keeps the screw attached to the insert. 
     In preferred embodiments of the upper plate assembly according to the present invention, each insert comprises screw threading on a lower surface thereof and is screwed into a threaded bore formed with the recess. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other objects, features and advantages of the invention will become more apparent after reading the following detailed description of preferred embodiments of the invention, given with reference to the accompanying drawings, in which: 
         FIG. 1  is a perspective view of a conventional rotary chuck; 
         FIG. 2  is a partial sectional view taken along the line II-II of  FIG. 1 ; 
         FIG. 3  is a perspective view of a rotary chuck according to an embodiment of the present invention; 
         FIG. 4  is a partial sectional view taken along the line IV-IV of  FIG. 3 ; 
         FIG. 5  is a partial sectional view taken along the line V-V of  FIG. 3 ; 
         FIG. 6  is an enlarged view of the detail VI in  FIG. 3 ; 
         FIG. 7  is a view corresponding to  FIG. 6 , in which the pin assembly and insert have been removed; 
         FIG. 8  is a perspective view of a pin assembly suitable for use in preferred embodiments of the present invention; 
         FIG. 9  is a perspective view of an insert suitable for use in preferred embodiments of the present invention; 
         FIG. 10  is a perspective view of a pin assembly as in  FIG. 8  combined with an insert as in  FIG. 9 ; 
         FIG. 11  is a view similar to  FIG. 4 , of another embodiment of an insert suitable for use in preferred embodiments of the present invention; and 
         FIG. 12  is a cross-section through yet another embodiment of an insert suitable for use in preferred embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring now to the drawings,  FIG. 1  depicts a conventional spin chuck that holds a wafer W thereon in a generally horizontal orientation. The spin chuck includes a rotary base body  1  to which upper plate  2  is connected. A series of pin assemblies  4  project upwardly through openings formed in the upper plate  2 . 
     As shown in greater detail in  FIG. 2 , each pin assembly  4  comprises an enlarged based equipped with gear teeth  6 , which mesh with the gear teeth  7  of a common ring gear  3  that drives all of the pin assemblies  4  in unison. Because the contact region  5  of each pin assembly  4  is eccentric to the rotational axis of the pin assembly, that rotation displaces the contact region  5  radially of the spin chuck, as described for example in U.S. Pat. Nos. 4,903,717 and 5,513,668. The correct positioning of the pin assemblies  4  is aided by respective needle bearings  8  and associated springs  9 . 
     However, as discussed above, in order to remove any given pin assembly  4  for repair or maintenance or replacement, the entire chuck must be disassembled, including removing the upper plate  2  from the chuck base body  1 . 
     Referring now to  FIG. 3 , in a first embodiment according to the invention, a rotary chuck  12  is mounted in a process module  11  for single wafer wet processing of semiconductor wafers. Each chuck  12  holds a single wafer, but there may be a plurality of such chuck mounted in a given process module  11 , with the chucks being controlled by common control mechanisms and supplied by common wafer handling equipment. Pin assemblies  40  are positioned so as to hold a wafer W of a predetermined diameter, for example, 300 mm or 450 mm. Rotary chuck  12  comprises a chuck base body  10  and an upper plate  20  secured thereto. 
     An infra-red heating assembly  60  comprising one or more IR lamps  68  is positioned above the upper plate  20  of the chuck  12 . As described more fully in commonly-owned copending application U.S. 2013/0061873, the heating assembly  60  is mounted on a stationary post that passes through the center of chuck  12 , so that the heating assembly  60  remains stationary as the chuck  12  rotates. Furthermore, the heating assembly, although above the upper plate, is below the level at which a wafer W is held by pin assemblies  40 , so that the heating assembly  60  heats a wafer W from the underside. The stationary structure also accommodates fluid supply nozzles  62 ,  64 ,  66 , which supply respectively different gases and/or liquids to the underside of a wafer W. 
     As shown in  FIG. 4 , each pin assembly  40  projects upwardly from the upper plate  20 , passing through a respective opening  26  that traverses the upper plate  20 . Unlike in the spin chuck of  FIGS. 1 and 2 , in the present embodiment the opening  26  is sufficiently wide to permit the entire pin assembly, including the enlarged base  42  thereof, to be removed through the opening  26 . 
     Also positioned within the opening  26  of upper plate  20 , and surround the main shaft of pin assembly  40 , is an insert  50 . An O-ring  22  is seated in a groove formed in opening  26 , to prevent liquid from entering the chuck  12  between the insert  50  and the upper plate  20 . Insert  50  includes an opening  56  which, like opening  26 , is preferably cylindrical. The width (or diameter) of opening  56  is however less than that of opening  26 , so that the main shaft of the pin assembly  40  can pass through the opening  56 , but the enlarged base portion  42  cannot pass through opening  56 . 
     Also visible in  FIG. 4  are a ring gear  30  that meshes via teeth  37  with corresponding teeth formed on the enlarged base portion  42  of each pin assembly  40 , and a needle bearing  18  and associated spring  19 , for positioning the respective pin assembly  40 . 
     Turning now to  FIGS. 5-7 , it can be seen that each insert  50  is secured to the upper plate  20  by a pair of screws  52 . In particular, each insert  50  is received in a corresponding recess  24  formed in the upper plate  20 . Recess  24  includes the opening  26  that traverses the upper plate  20 , and a pair of recessed, non-traversing regions in which bores  28  are formed for receiving the screws  52 . 
     Thus, to remove a pin assembly  40  from the chuck  12  of  FIGS. 3-7 , it is necessary only to unscrew the screws  52 , whereafter the pin assembly can be grasped, for example at the contact region  45  thereof, and lifted out of engagement with teeth  37  of ring gear  30 , up and out of the chuck through opening  26  in the upper plate  20 , along with the insert  50  that will remain captive on the pin assembly  40 . 
     It will be appreciated that the above operation is much quicker and simpler than in the prior art, as the chuck  12  need not be disassembled or removed from its drive and elevating unit, or, indeed, even removed from its surrounding process module  11 . 
       FIG. 8  shows a pin assembly  40  more clearly, including the eccentric contact region  45  that bears against a wafer edge in use, and also provides subjacent support to the wafer so that it is maintained at a predetermined distance above the upper plate  20 . Also shown is the enlarged base portion  42 , which includes gear teeth  46  formed integrally therewith, the gear teeth  42  of each pin assembly in use being in simultaneous meshing engagement with the gear teeth  37  of common ring gear  30 . 
     Pin assembly  40  also preferably includes a registration or “timing” mark, such as the hole  47  formed in the enlarged base portion  42 , which is formed at the same angular position on each of the pin assemblies  40 , so that each pin assembly  40  can be more readily inserted into the chuck through opening  26  and into meshing engagement with the gear teeth  37  of gear ring  30  in its correct angular orientation relative to the other pin assemblies  40 . 
       FIG. 9  shows an insert  50  more clearly, including the central opening  56  through which the main shaft of pin assembly  40  may pass, but which does not permit passage of the enlarged base portion  42 , and a pair of openings  54  that receive the screws  52  in this embodiment so that the flat heads of the screws are flush mounted with the upper surface of the insert  50 . 
     In  FIG. 10 , the insert  50  is shown captive on the pin assembly  40 , as it would be in use and also when the screws  52  are removed and the pin assembly  40  is extracted from the chuck  12  by lifting the pin assembly  40  and insert  50  out of the upper plate  20  of the chuck  12 . 
       FIG. 11  shows another embodiment of an insert  51  suitable for use in preferred embodiments according to the present invention. The insert  51  of  FIG. 11  is in general symmetrical about the rotational axis of pin assembly  40 , and is secured to the upper plate  21  not by separate screws  52  but instead by its own screw threading  53  that mates with corresponding threading formed in the threaded bore  27  of plate  21 . 
     The part  55  of insert  51  that projects above the surface of upper plate  21  is preferably nut-shaped, so as to be able to receive a deep socket that has clearance for the pin assembly  40  and allows the insert  51  to be screwed into the threaded bore  27  of upper plate  21 . 
     An O-ring  23  is seated in a groove of the bore  27  above the threaded part thereof, to prevent liquid from seeping between the insert  51  and the upper plate  21 . Alternatively or in addition, the insert  21  may be formed with a lip seal  57  that creates a friction fit between the insert  51  and the upper plate  21 . 
     Lastly, in  FIG. 12 , yet another embodiment of an insert  58  is illustrated, which is like the insert  50  described in connection with  FIGS. 5-7 , but in which the screws  52  are captive within the insert  58 , by virtue of collars  59 , which permit the screws  52  to be screwed and unscrewed from the bores  28  in recess  24 , but which prevent the screws  52  from being removed from the insert  58 . This embodiment therefore further simplifies the assembly and disassembly of pin assemblies from the upper plate, as it eliminates any risk of the screws  52  falling into the chuck  12  or elsewhere in the process module  11 . 
     While the present invention has been described in connection with various preferred embodiments thereof, it is to be understood that those embodiments are provided merely to illustrate the invention, and should not be used as a pretext to limit the scope of protection conferred by the true scope and spirit of the appended claims.

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