Abstract:
A device and method for processing wafer-shaped articles comprises a process chamber and a rotary chuck located within the process chamber. The rotary chuck is adapted to be driven without physical contact through a magnetic bearing. The rotary chuck comprises a series of gripping pins adapted to hold a wafer shaped article in a position depending downwardly from the rotary chuck. The rotary chuck further comprises a plate that rotates together with the rotary chuck. The plate is positioned above an area occupied by the wafer-shaped article, and shields upper surfaces of the process chamber from liquids flung off of a wafer-shaped article during use of the rotary chuck.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The invention relates generally to an apparatus for treating surfaces of wafer-shaped articles, such as semiconductor wafers, wherein one or more treatment fluids may be recovered from within a closed process chamber. 
         [0003]    2. Description of Related Art 
         [0004]    Semiconductor wafers are subjected to various surface treatment processes such as etching, cleaning, polishing and material deposition. 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 carrier, as is described for example in U.S. Pat. Nos. 4,903,717 and 5,513,668. 
         [0005]    Alternatively, a chuck in the form of a ring rotor adapted to support a wafer may be located within a closed process chamber and driven without physical contact through an active magnetic bearing, as is described for example in International Publication No. WO 2007/101764 and U.S. Pat. No. 6,485,531. Treatment fluids which are driven outwardly from the edge of a rotating wafer due to centrifugal action are delivered to a common drain for disposal. 
         [0006]    Conventional rotary chucks that are adapted to be driven without physical contact through a magnetic bearing, expose both sides of a wafer to the process chamber ambient, which the present inventors have discovered can give rise to various disadvantages. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention in one aspect relates to a device for processing wafer-shaped articles, comprising a process chamber and a rotary chuck located within the process chamber. The rotary chuck is adapted to be driven without physical contact through a magnetic bearing. The rotary chuck comprises a series of gripping pins adapted to hold a wafer shaped article in a position depending downwardly from the rotary chuck. The rotary chuck further comprises a plate that rotates together with the rotary chuck. The plate is positioned above an area occupied by a wafer-shaped article when the rotary chuck is in use, and the plate shields upper surfaces of the process chamber from liquids flung off of a wafer-shaped article during use of the rotary chuck. 
         [0008]    In preferred embodiments of the device according to the present invention, the plate is positioned parallel to a plane in which a major surface of a wafer shaped article will be present during use of the rotary chuck, thereby to define a gap of a predetermined width between the plate and the plane. 
         [0009]    In preferred embodiments of the device according to the present invention, the predetermined width is from about 0.1 to 5 mm, and preferably from about 0.5 to 2 mm. 
         [0010]    In preferred embodiments of the device according to the present invention, the plate is positioned parallel to an overlying lid of the process chamber, thereby to define a gap of a predetermined width between the plate and the lid. In preferred embodiments of the device according to the present invention, the predetermined width is from about 0.1 to 10 mm, preferably from about 0.5 to 5 mm, and more preferably from about 1 to 3 mm. 
         [0011]    In preferred embodiments of the device according to the present invention, the process chamber comprises a lid overlying the plate, and a nozzle assembly mounted on the lid, the nozzle assembly having a discharge end traversing the lid and a central region of the plate, whereby process fluids can be supplied via the nozzle assembly to an upwardly-facing surface of a wafer-shaped article during use of the device. 
         [0012]    In preferred embodiments of the device according to the present invention, the device further comprises at least one infra-red (IR) lamp positioned outside the process chamber and overlying the plate. 
         [0013]    In preferred embodiments of the device according to the present invention, the at least one IR lamp is positioned adjacent a lid of the process chamber, and wherein at least a portion of the lid and the plate are formed from materials transparent to IR radiation emitted by the at least one IR lamp. 
         [0014]    In preferred embodiments of the device according to the present invention, the process chamber comprises an interior cover disposed within the process chamber, the interior cover being movable between a first position in which the rotary chuck communicates with an outer wall of the closed process chamber, and a second position in which the interior cover seals against an inner surface of the closed process chamber adjacent the rotary chuck to define a gas-tight inner process chamber. 
         [0015]    In preferred embodiments of the device according to the present invention, the interior cover forms a lower portion of the inner process chamber when in the second position. 
         [0016]    In preferred embodiments of the device according to the present invention, the magnetic bearing comprises a stator located outside the closed process chamber. 
         [0017]    The present invention in another aspect relates to a method for processing wafer-shaped articles, comprising positioning a wafer-shaped article on a rotary chuck within a process chamber such that the wafer-shaped article is held by the rotary chuck in a position depending downwardly from the rotary chuck, and forming a film of liquid in a gap between an upper side of the wafer-shaped article and a plate carried by the rotary chuck, the plate overlying and extending parallel to the wafer-shaped article, thereby to define a gap of a predetermined width. 
         [0018]    In preferred embodiments of the method according to the present invention, the predetermined width is from about 0.1 to 5 mm, and preferably from about 0.5 to 2 mm. 
         [0019]    In preferred embodiments of the method according to the present invention, the rotary chuck is adapted to be driven without physical contact through a magnetic bearing. 
         [0020]    In preferred embodiments of the method according to the present invention, the method also includes heating the wafer-shaped article using at least one infra-red (IR) lamp positioned outside the process chamber, wherein portions of the process chamber and the plate overlying the wafer-shaped article are transparent to IR radiation emitted by the at least one IR lamp. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    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: 
           [0022]      FIG. 1  is an explanatory cross-sectional side view of a process chamber according to a first embodiment of the invention, with the interior cover shown in its first position; 
           [0023]      FIG. 2  is an explanatory cross-sectional side view of a process chamber according to the first embodiment of the invention, with the interior cover shown in its second position; 
           [0024]      FIG. 3  is an explanatory cross-sectional perspective view of the lid and chuck of the first embodiment, with a wafer in position; and 
           [0025]      FIG. 4  is an enlarged view of the detail IV in  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0026]    Referring now to  FIG. 1 , an apparatus for treating surfaces of wafer-shaped articles according to a first embodiment of the invention comprises an outer process chamber  1 , which is preferably made of aluminum coated with PFA (perfluoroalkoxy) resin. The chamber in this embodiment has a main cylindrical wall  10 , a lower part  12  and an upper part  15 . From upper part  15  there extends a narrower cylindrical wall  34 , which is closed by a lid  36 . 
         [0027]    A rotary chuck  30  is disposed in the upper part of chamber  1 , and surrounded by the cylindrical wall  34 . Rotary chuck  30  rotatably supports a wafer W during used of the apparatus. The rotary chuck  30  incorporates an annular drive comprising ring gear  38 , which engages and drives a plurality of eccentrically movable gripping members  40  for selectively contacting and releasing the peripheral edge of a wafer W. 
         [0028]    In this embodiment, the rotary chuck  30  is a ring rotor provided adjacent to the interior surface of the cylindrical wall  34 . A stator  32  is provided opposite the ring rotor adjacent the outer surface of the cylindrical wall  34 . The rotor  30  and stator  32  serve as a motor by which the ring rotor  30  (and thereby a supported wafer W) may be rotated through an active magnetic bearing. For example, the stator  32  can comprise a plurality of electromagnetic coils or windings that may be actively controlled to rotatably drive the rotary chuck  30  through corresponding permanent magnets provided on the rotor. Axial and radial bearing of the rotary chuck  30  may be accomplished also by active control of the stator or by permanent magnets. Thus, the rotary chuck  30  may be levitated and rotatably driven free from mechanical contact. Alternatively, the rotor may be held by a passive bearing where the magnets of the rotor are held by corresponding high-temperature-superconducting magnets (HTS-magnets) that are circumferentially arranged on an outer rotor outside the chamber. With this alternative embodiment each magnet of the ring rotor is pinned to its corresponding HTS-magnet of the outer rotor. Therefore the inner rotor makes the same movement as the outer rotor without being physically connected. 
         [0029]    The lid  36  has a nozzle assembly  42  mounted on its exterior, which supplies a medium inlet  44  that traverses the lid  36  and opens into the chamber above the wafer W. It will be noted that the wafer W in this embodiment hangs downwardly from the rotary chuck  30 , supported by the gripping members  40 , such that fluids supplied through inlet  44  would impinge upon the upwardly facing surface of the wafer W. 
         [0030]    Rotary chuck  30  also comprises a plate  52  that is positioned above a wafer W when the chuck  30  is in use. Plate  52  preferably overlies the entire upper surface of wafer W, except where the plate  52  is open to permit passage of the discharge end of the nozzle assembly  42 . 
         [0031]    The lid  36  in this embodiment also includes a set of IR heating elements  62 , which permit a wafer W to be rapidly heated through the intervening thickness of the lid  36  and the plate  52 , both of which are therefore made in this embodiment of a material that is substantially transparent to the IR radiation emitted by the heating elements  62 , such as quartz glass. 
         [0032]    In case wafer  30  is a semiconductor wafer, for example of 300 mm or 450 mm diameter, the upwardly facing side of wafer W could be either the device side or the obverse side of the wafer W, which is determined by how the wafer is positioned on the rotary chuck  30 , which in turn is dictated by the particular process being performed within the chamber  1 . 
         [0033]    The apparatus of  FIG. 1  further comprises an interior cover  2 , which is movable relative to the process chamber  1 . Interior cover  2  is shown in  FIG. 1  in its first, or open, position, in which the rotary chuck  30  is in communication with the outer cylindrical wall  10  of chamber  1 . Cover  2  in this embodiment is generally cup-shaped, comprising a base  20  surrounded by an upstanding cylindrical wall  21 . Cover  2  furthermore comprises a hollow shaft  22  supporting the base  20 , and traversing the lower wall  14  of the chamber  1 . 
         [0034]    Hollow shaft  22  is surrounded by a boss  12  formed in the main chamber  1 , and these elements are connected via a dynamic seal that permits the hollow shaft  22  to be displaced relative to the boss  12  while maintaining a gas-tight seal with the chamber  1 . 
         [0035]    At the top of cylindrical wall  21  there is attached an annular deflector member  24 , which carries on its upwardly-facing surface a gasket  26 . Cover  2  preferably comprises a fluid medium inlet  28  traversing the base  20 , so that process fluids and rinsing liquid may be introduced into the chamber onto the downwardly facing surface of wafer W. 
         [0036]    Cover  2  furthermore includes a process liquid discharge opening  23 , which opens into a discharge pipe  25 . Whereas pipe  25  is rigidly mounted to base  20  of cover  2 , it traverses the bottom wall  14  of chamber  1  via a dynamic seal  17  so that the pipe may slide axially relative to the bottom wall  14  while maintaining a gas-tight seal. 
         [0037]    An exhaust opening  16  traverses the wall  10  of chamber  1 , whereas a separate exhaust opening (not shown) traverses the lid  36 . Each exhaust opening is connected to suitable exhaust conduits (not shown), which are preferably independently controlled via respective valves and venting devices. 
         [0038]    The position depicted in  FIG. 1  corresponds to loading or unloading of a wafer W. In particular, a wafer W can be loaded onto the rotary chuck  30  through a side door  46  in the chamber wall  10 . However, when the lid  36  is in position and when side door  46  has been closed, the chamber  1  is gas-tight and able to maintain a defined internal pressure. 
         [0039]    In  FIG. 2 , the interior cover  2  has been moved to its second, or closed, position, which corresponds to processing of a wafer W. That is, after a wafer W is loaded onto rotary chuck  30 , the cover  2  is moved upwardly relative to chamber  1 , by a suitable motor (not shown) acting upon the hollow shaft  22 . The upward movement of the interior cover  2  continues until the deflector member  24  comes into contact with the interior surface of the upper part  15  of chamber  1 . In particular, the gasket  26  carried by deflector  24  seals against the underside of upper part  15 , whereas the gasket  18  carried by the upper part  15  seals against the upper surface of deflector  24 . 
         [0040]    When the interior cover  2  reaches its second position as depicted in  FIG. 2 , there is thus created a second chamber  48  within the closed process chamber  1 . Inner chamber  48  is moreover sealed in a gas tight manner from the remainder of the chamber  1 . Moreover, the chamber  48  is preferably separately vented from the remainder of chamber  1 , which is achieved in this embodiment by the provision of an exhaust port opening into the chamber  48 , independently from the exhaust port  16  that serves the chamber  1  in general, and the remainder of the chamber  1  in the  FIG. 2  configuration. 
         [0041]    During processing of a wafer, processing fluids may be directed through nozzle assembly  42  through the central opening in plate  52  and onto a rotating wafer W in order to perform various processes, such as etching, cleaning, rinsing, and any other desired surface treatment of the wafer undergoing processing. 
         [0042]    Provision of the plate  52  integrated with chuck  30 , between wafer W and the top  36  of chamber  1 , gives rise to a number of advantages. This plate  52  can be quartz in case an IR lamp is used to heat up the media (e.g. sulfuric acid) to guarantee the IR transparency. 
         [0043]    The plate  52  in use is rotating with the chuck and at the same speed thereof, and hence also is rotating with a wafer W gripped by the chuck  30 , and also at the same speed as wafer  30 . This design therefore serves to minimize turbulence in the employed process fluids. 
         [0044]    Moreover, when IR heating lamps are used, the plate  52  permits preventing residual heat transfer, because the gap between the chuck  30  and the lamps, i.e., the gap above plate  52  and below lid  36 , can be actively cooled (for example, with nitrogen and/or deionized water). 
         [0045]    Furthermore, it is possible to minimize temperature differences during a drying process by cooling the plate  52  with deionized water. Still further, residual process media above the wafer W on the underside of plate  52 , caused for example by splashing and/or condensation, can be rinsed simultaneously during the aforementioned deionized water rinse, or can be rinsed with deionized water after completion of the process. 
         [0046]    As the plate  52  segregates the chamber interior from the upwardly facing side of the wafer W, this serves to minimize contamination by backsplashing and or particles. Plate  52  furthermore permits enhanced atmosphere control above the wafer. Still further, this design also allows gap processes, i.e., processes in which the gap between wafer and the chuck is filled with liquid. 
         [0047]      FIG. 3  shows only the lid  36  and chuck  30  of  FIGS. 1 and 2 , with a wafer W still in position. IR lamps  62  are formed as a series of concentric circular elements, and are individually controllable to provide a tuned heating of a wafer W. Nozzle assembly  42  in this embodiment comprises three separate conduits  54 ,  56 ,  58  each connected to a respective supply of a process fluid. For example, one of the conduits may supply deionized water, another nitrogen gas, and the third a process fluid such as concentrated sulfuric acid. 
         [0048]    At least the lower portion  68  of lid  36 , like plate  52 , is formed of a material that is substantially transparent to the wavelengths of the IR lamps  62 , an example of the material utilized for lid portion  68  and plate  52  in this embodiment being quartz. When IR lamps  62  are not used, then both plate  52  and lid portion  68  may be formed from other materials, such as aluminum coated with PFA (perfluoroalkoxy) resin. 
         [0049]    In the detail of  FIG. 4 , it can be seen that plate  52  is spaced from the underlying wafer W by a small gap  64 , which is preferably from about 0.1 to 5 mm, and more preferably from about 0.5 to 2 mm. Gap  64  permits performing gap processes as noted above, i.e., processes in which the gap between wafer and the chuck is filled with liquid.  FIG. 4  also shows that the plate  52  is spaced from the overlying lid portion  68  by a small gap  66 , which is preferably from about 0.1 to 10 mm, more preferably from about 0.5 to 5 mm, and still more preferably from about 1 to 3 mm. Gap  66  permits the plate  52  and hence the wafer W to be actively cooled, for example with nitrogen and/or deionized water, thereby to prevent residual heat transfer from wafer W after it has been heated using IR lamps  62 . The same active cooling technique can be utilized to minimize temperature differences during a drying process.