Patent Document

BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     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. 
     2. Description of Related Art 
     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. 
     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. 
     For many applications the closed process chamber needs to be purged with ozone or an inert gas such as nitrogen, prior to commencement of a given process, or between successive processes. Additionally, for many applications the process chambers also need to be cleaned, for example by rinsing with deionized water. 
     An improved design for closed chamber single wafer wet processing is described in commonly-owned copending application U.S. Pub. No. 2013/0134128, in which the lid for the chamber is equipped with a fluid distribution ring that is either resilient or maintained at a very small gap from the edge of the surrounding chamber wall. However, it has proven difficult in practice to assemble the chamber without damaging the edge of the annular gap. Moreover, when the ring is made of a resilient material, it has been found that such material may expand during high temperature processing, thereby causing the gap to close partially and impair the purging function. 
     SUMMARY OF THE INVENTION 
     The present inventors have developed an improved apparatus for treating wafer-shaped articles, as well as an improved lid for use with such an apparatus. 
     Thus, in one aspect, the present invention relates to an apparatus for processing wafer-shaped articles, comprising a closed process chamber, the closed process chamber comprising a housing providing a gas-tight enclosure. A rotary chuck is located within the closed process chamber, and is adapted to hold a wafer shaped article thereon. A lid is secured to an upper part of the closed process chamber, the lid comprising an annular chamber, gas inlets communicating with the annular chamber and opening on a surface of the lid facing outwardly of the closed process chamber, and gas outlets communicating with the annular chamber and opening on a surface of the lid facing inwardly of the closed process chamber. 
     In preferred embodiments of the apparatus according to the present invention, the lid comprises an upper plate formed from a composite fiber-reinforced material and a lower plate that faces into the closed process chamber and is formed from a chemically-resistant plastic, the annular chamber being formed in the lower plate. 
     In preferred embodiments of the apparatus according to the present invention, the annular chamber is defined by a radially-inwardly extending groove formed in a lower region of the lid, and a ring that is fitted in an outer part of the groove so as to close the annular chamber. 
     In preferred embodiments of the apparatus according to the present invention, the annular chamber is defined by a radially-inwardly extending groove formed in a peripheral region of the lower plate, and a ring that is fitted in an outer part of the groove so as to close the annular chamber. 
     In preferred embodiments of the apparatus according to the present invention, the lower region of the lid and the ring are each formed from a chemically-resistant plastic selected independently 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 preferred embodiments of the apparatus according to the present invention, there are at least three gas inlets. 
     In preferred embodiments of the apparatus according to the present invention, there are at least 60 gas outlets, preferably at least 80 gas outlets, and more preferably at least 100 gas outlets. 
     In preferred embodiments of the apparatus according to the present invention, gas nozzles are each fitted to a respective gas inlet and configured to connect to a gas supply conduit or manifold. 
     In preferred embodiments of the apparatus according to the present invention, first additional gas outlets open on a surface of the lid facing inwardly of the closed process chamber, the additional gas outlets being positioned radially inwardly of the annular chamber, the additional gas outlets being oriented so as to generate a rotating gas flow beneath the lid. 
     In preferred embodiments of the apparatus according to the present invention, second additional gas outlets open on a surface of the lid facing inwardly of the closed process chamber, the second additional gas outlets being positioned radially inwardly of the annular chamber, the additional gas outlets being oriented so as to generate a gas flow directed radially outwardly of the lid. 
     In another aspect, the present invention relates to a lid for closing a process chamber used for processing wafer-shaped articles. The lid comprises an annular chamber, gas inlets communicating with the annular chamber and opening on an outwardly facing surface of the lid, and gas outlets communicating with the annular chamber and opening on an inwardly facing surface of the lid. 
     In preferred embodiments of the lid according to the present invention, the lid comprises an upper plate formed from a composite fiber-reinforced material and a lower plate formed from a chemically-resistant plastic, the annular chamber being formed in the lower plate. 
     In preferred embodiments of the lid according to the present invention, the annular chamber is defined by a radially-inwardly extending groove formed in a lower region of the lid, and a ring that is fitted in an outer part of the groove so as to close the annular chamber. 
     In preferred embodiments of the lid according to the present invention, the annular chamber is defined by a radially-inwardly extending groove formed in a peripheral region of the lower plate, and a ring that is fitted in an outer part of the groove so as to close the annular chamber. 
     In preferred embodiments of the lid according to the present invention, the lower region of the lid and the ring are each formed from a region chemically-resistant plastic selected independently 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 preferred embodiments of the lid according to the present invention, there are at least three gas inlets. 
     In preferred embodiments of the lid according to the present invention, there are at least 60 gas outlets, preferably at least 80 gas outlets, and more preferably at least 100 gas outlets. 
     In preferred embodiments of the lid according to the present invention, gas nozzles are each fitted to a respective gas inlet and configured to connect to a gas supply conduit or manifold. 
     In preferred embodiments of the lid according to the present invention, first additional gas outlets open on the inwardly facing surface of the lid, the first additional gas outlets being positioned radially inwardly of the annular chamber, the first additional gas outlets being oriented so as to generate a rotating gas flow beneath the lid. 
     In preferred embodiments of the lid according to the present invention, second additional gas outlets open on the inwardly facing surface of the lid, the second additional gas outlets being positioned radially inwardly of the annular chamber, the second additional gas outlets being oriented so as to generate a gas flow directed radially outwardly of the lid. 
    
    
     
       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 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; 
         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; 
         FIG. 3  is sectional perspective view of an embodiment of a lid according to the present invention; 
         FIG. 4  shows a part of  FIG. 3  on a larger scale; 
         FIG. 5  is a side view of the lower plate  60  of the preceding embodiment; 
         FIG. 6  is a sectional view taken along the line VI-VI of  FIG. 5 ; and 
         FIG. 7  is an enlarged view of the detail VII in  FIG. 5 . 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     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 . 
     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 use of the apparatus. The rotary chuck  30  incorporates a rotary drive comprising ring gear  38 , which engages and drives a plurality of eccentrically movable gripping members for selectively contacting and releasing the peripheral edge of a wafer W. 
     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. 
     The lid  36  is of an improved design, and comprises an upper plate  50  formed from a composite fiber-reinforced material and a lower plate  60  that faces into the process chamber and is formed from a chemically-resistant plastic, which in this embodiment is ECTFE. Sandwiched between the upper plate  50  and lower plate  60  in this embodiment is a stainless steel plate  70  (see  FIG. 3 ). 
     As can be seen in  FIG. 3 , the lid  36  may further include an electrical heating layer  62  for heating the lower plate  60  to a temperature that prevents condensation of process vapors from occurring on the surface of plate  60  that faces into the process chamber. Electrical heating layer  62  is preferably a silicone rubber heater. 
     Spacer plate  64  serves to maintain the heater layer  62  pressed into contact with lower plate  60 , as does the annular spacer  66 , which latter element is preferably formed from stainless steel. 
     Lid  36  may be secured to the process chamber by bolts (not shown) that pass through bores  58 . 
     Referring now to  FIGS. 4-7 , the lower plate  60  of lid  36  is formed with a radially inwardly extending annular groove  65  that opens on the periphery of plate  60 . A ring  66  is fitted in the opening of that groove  65 , to form an annular chamber. Upper openings in the plate  60  communicate with the annular chamber, and receive nozzles  54  that are attached to a gas supply so as to supply purge gas into the annular chamber. Preferably there are at least three such nozzles  54 . 
     Purge gas exits the annular chamber through a much larger number of much smaller outlets  67  that extend from the annular chamber and open on the lower surface of lower plate  60 , which is a surface that faces inwardly of the closed process chamber when the lid is in place. As shown in  FIG. 6 , there are 120 outlets  67  in this embodiment, although the number of such outlets can of course be varied as desired to create a target gas flow profile. 
     First additional gas outlets  63  also open on the lower surface of lower plate  60 , but are positioned radially inwardly of the annular chamber. Outlets  63  are supplied by separate gas nozzles  57 . Second additional gas outlets  67  also open on the lower surface of lower plate  60 , and, like the first additional outlets  63 , are positioned radially inwardly of the annular chamber. These second additional gas outlets  63  are likewise supplied by separate gas nozzles  59 . 
     With reference to  FIG. 6 , it can be seen that the outlets  63  are moreover oriented so as to generate a rotating gas flow beneath said lid. In particular, the three outlets  63  together generate a flow of purge gas that rotates in a generally clockwise direction, as indicated by the circular arrow in  FIG. 6 . 
     On the other hand, the stator  32  and rotor  30  operate to rotate the chuck in a counter-clockwise direction. The opposite directions of rotation as between the chuck and the flow of purge gas through outlets  63  has been found to provide an especially thorough and efficient purging of the chuck ambient within the closed process chamber, especially in the region above the wafer W. 
     That effect can be further improved by the provision of the second additional outlets  69 , which direct their flow of purge gas radially outwardly of the lower plate  60 , yet are also positioned inwardly of the annular chamber formed in plate  60 . 
     Simulations were performed to compare the performance of the lid design as described herein with the purge ring of the commonly-owned copending application U.S. Pub. No. 2013/0134128. For wafers of 300 mm diameter rotated at speeds of 350 or 400 rpm, it was found that flow patterns of purge gas having improved velocity and uniformity could be obtained with the present design despite specifying much lower total flow rates of purge gas. 
     For example, with total flow rate of gaseous nitrogen of 40 liters per minute (lpm) or 75 lpm, the flow pattern was improved in relation to the previous design at flow rates of 120 lpm. In the present design, a flow rate of 40 lpm is obtained by specifying 25 lpm flow through the outlets  67  and 15 lpm flow through the additional outlets  63 ,  69 , and a flow rate of 75 lpm is obtained by specifying 50 lpm flow through the outlets  67  and 25 lpm flow through the additional outlets  63 ,  69 . 
     With reference to  FIGS. 1 and 2 , it will be noted that the wafer W in the foregoing embodiments hangs downwardly from the rotary chuck  30 , supported by the gripping members  40 , such that fluids supplied through inlet  56  would impinge upon the upwardly facing surface of the wafer W. 
     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 . 
     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 . 
     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 . 
     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. 
     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. 
     An exhaust opening  16  traverses the wall  10  of chamber  1 , and is connected to a suitable exhaust conduit. 
     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  either through the lid  36 , or, more preferably, through a side door (not shown) in the chamber wall  10 . However, when the lid  36  is in position and when any side door has been closed, the chamber  1  is gas-tight and able to maintain a defined internal pressure. 
     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 . 
     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 the exhaust port  46  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. 
     During processing of a wafer, processing fluids may be directed through medium inlets  56  and/or  28  to 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. 
     Provision of the inner chamber  48  within the overall process chamber  1  thus enhances the safety of environmentally closed chambers by permitting the gases and liquids used for wafer processing to be better isolated from the exterior environment of the process chamber, and reduces the risk of process gas, chemical fumes, hot vapor such as vaporized isopropyl alcohol, ozone and the like being released to the tool environment. 
     It will be understood that the foregoing description and specific embodiments shown herein are merely illustrative of the invention and the principles thereof, and that modifications and additions may be easily made by those skilled in the art without departing from the spirit and scope of the invention, which is therefore understood to be limited only by the scope of the appended claims.

Technology Category: 5