Abstract:
A method for rinsing and drying a workpiece includes placing the workpiece into a chamber and spinning the workpiece. A rinsing fluid, such as water, is applied onto the workpiece through a first outlet in the chamber, with the rinsing fluid moving outwardly towards the edge of the workpiece via centrifugal force, to rinse the workpiece. A drying fluid, such as an alcohol vapor, is applied onto the workpiece through the first outlet, with the drying fluid moving outwardly towards the edge of the workpiece via centrifugal force, to dry the workpiece. The drying fluid advantageously follows a meniscus of the rinsing fluid across the workpiece surface. The rinsing fluid, or the drying fluid, or both fluids, may be applied near or at a central area of the workpiece.

Description:
[0001]     This Application is a: Continuation of U.S. patent application Ser. No. 10/632,495 filed Jul. 31, 2003 and now pending, which is a Division of U.S. patent application Ser. No. 09/672,572 filed Sep. 28, 2000, now U.S. Pat. No. 6,632,292B1, which is a Continuation-in-Part of U.S. patent application Ser. No. 09/437,926 filed Nov. 10, 1999, now U.S. Pat. No. 6,413,436, which is a Continuation of International Application No. PCT/US99/05674, filed Mar. 15, 1999, designating the U.S. and published in English, which claims priority to U.S. patent application Ser. Nos.: 
        Ser No. 09/041,649 filed Mar. 13, 1998, now U.S. Pat. No. 6,318,385;     Ser. No. 09/113,435 filed Jul. 10, 1998, now U.S. Pat. No. 6,264,752;     Ser. No. 09/041,901 filed Mar. 13, 1998, now U.S. Pat. No. 6,350,319;     U.S. Provisional Application 60/116,750 filed Jan. 22, 1999;     and U.S. Provisional Application 60/117,474 filed Jan. 27, 1999.        
 
         [0007]     The above-listed Applications and U.S. Pat. No. 6,423,642 are incorporated herein by reference.  
     
    
     BACKGROUND  
       [0008]     One of the most important processes in the fabrication of integrated circuits involves the rinsing and drying of the semiconductor wafers between various chemical processing steps. During rinsing, de-ionized (DI) water is often used to assist in the removal of chemicals from the surface of the wafer. After rinsing is completed, the wafer surface must be dried. It is during the drying step that wafer contamination often results. Such contamination is due to the fact that the evaporation of the DI water deposits contaminant particles on the wafer surface.  
         [0009]     Various techniques have been proposed for the rinsing and drying of semiconductor wafers. One technique used to both rinse and dry wafers relies upon a spin rinser/dryer. Such a system uses a DI rinse water spray to rinse the wafer. The wafer is spun during the drying step thereby removing the water from the surface of the semiconductor wafer through evaporation and the action of centrifugal acceleration.  
         [0010]     Other techniques used to dry wafers include the use of isopropyl alcohol (IPA) vapor dryers, full displacement IPA dryers, and other forms of IPA dryers. These IPA dryers rely upon a large quantity of a solvent, such as IPA and other volatile organic liquids, to facilitate drying of the semiconductor wafer. One limitation of this type of dryer is its use of large solvent quantities which are highly flammable and often hazardous to health and environment. Further, these dryer types are often quite expensive. Still further, the large quantities of hot solvent are often incompatible with certain recessed pattern wafers and may be detrimental to certain device structures.  
         [0011]     A still further drying technique is known as a Marangoni dryer. In a Marangoni dryer, the wafer is slowly withdrawn from the rinsing liquid in an atmosphere having a vapor that is miscible with the rinsing liquid. As the wafer is withdrawn, a meniscus is formed at the wafer surfaces. The surface tension of the rinsing fluid at the meniscus is reduced as a result of the presence of the vapor. The reduced surface tension gives rise to a substantially particle free drying process.  
         [0012]     The demands for integrated circuit rinsing/drying processes may ultimately require more control and economic efficiency from the rinser/dryer. As such, a substantially new approach to rinsing and drying of the semiconductor wafer has been undertaken which provides greater control of the rinsing and drying fluids. Further, wafers may be rinsed and dried on an individual basis more quickly when compared to the drying of an individual wafer using any of the foregoing processes 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]      FIG. 1  is a cross-sectional view of a rinser/dryer housing and a rotor assembly constructed in accordance with one embodiment of the invention.  
         [0014]      FIG. 2  is an exploded view of a further embodiment of a rinser/dryer housing.  
         [0015]      FIG. 3  is a top plan view of the rinser/dryer housing of  FIG. 2  when the housing is in an assembled state.  
         [0016]      FIG. 4  is a cross-sectional view of the rinser/dryer housing taken along line IV-IV of  FIG. 3 .  
         [0017]      FIG. 5  is a cross-sectional view of the rinser/dryer housing taken along line V-V of  FIG. 3 .  
         [0018]      FIG. 6  is a cross-sectional view of the rinser/dryer housing taken along line VI-VI of  FIG. 3 .  
         [0019]      FIGS. 7A and 7B  are cross-sectional views showing the rinser/dryer housing in a closed state and connected to a rotary drive assembly.  
         [0020]      FIGS. 8A and 8B  are cross-sectional views showing the rinser/dryer housing in an open state and connected to a rotary drive assembly.  
         [0021]      FIGS. 9 and 10  are schematic diagrams of exemplary processing tools including the present rinser/dryer.  
         [0022]      FIG. 11  is a schematic diagram of one embodiment of a fluid supply system that may be used to supply rinsing and drying fluids to the rinser/dryer. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0023]      FIG. 1  is a cross-sectional view of one embodiment of a rinser/dryer, shown generally at  10 . The embodiment of the rinser/dryer  10  of  FIG. 1  is generally comprised of a rotor  15  and a rinser/dryer housing  20 . The rotor  15  includes support members  25  that extend downwardly to engage the rinser/dryer housing  20 . Each of the support members  25  includes a groove  30  dimensioned to engage a radially extending flange  35  that extends about a peripheral region of the rinser/dryer housing  20 . A motor assembly  40  rotates a hub  45 , including the support members  25 , about a central axis  47 . Rinser/dryer housing  20  is thus secured for rotation with the hub  45  when support members  25  are engaged with flange  35 . Other constructions of the rotor  15  and the engagement mechanism used for securement with the rinser/dryer housing  20  may also be used.  
         [0024]     The rinser/dryer housing  20  of the embodiment of  FIG. 1  defines a substantially closed rinser/dryer chamber  50 . Preferably, the substantially closed rinser/dryer chamber  50  is formed in the general shape of the workpiece  55  and closely conforms with the surfaces of the workpiece. The specific construction of  FIG. 1  includes an upper chamber member  60  having an interior chamber face  65 . The upper chamber member  60  includes a centrally disposed fluid inlet opening  70  in the interior chamber face  65 . The specific construction also includes a lower chamber member  75  having an interior chamber face  80 . The lower chamber member  75  has a centrally disposed fluid inlet opening  85  in the interior chamber face  80 . The upper chamber member  60  and the lower chamber member  75  engage one another to define the rinser/dryer chamber  50 . The upper chamber member  60  includes sidewalls  90  that project downward from the interior chamber face  65 . One or more outlets  100  are disposed at the peripheral regions of the rinser/dryer chamber  50  through the sidewalls  90  to allow fluid within the chamber  50  to exit therefrom through centrifugal acceleration that is generated when the housing  20  is rotated about axis  47 .  
         [0025]     In the illustrated embodiment, the workpiece  55  is a generally circular wafer having upper and lower planar surfaces. As such, the rinser/dryer chamber  50  is generally circular in plan view and the interior chamber faces  65  and  80  are generally planar and parallel to the upper and lower planar surfaces of the workpiece  55 . The spacing between the interior chamber faces  65  and  80  and the upper and lower planar surfaces of the workpiece  55  is generally quite small. Such spacing is preferably minimized to provide substantial control of the physical properties of a rinsing/drying fluid flowing through the interstitial regions.  
         [0026]     The wafer  55  is spaced from the interior chamber face  80  by a plurality of spacing members  105  extending from the interior chamber face  80 . Preferably, a further set of spacing members  110  extend from the interior chamber face  65  and are aligned with the spacing members  105  to grip the wafer  55 .  
         [0027]     Fluid inlet openings  70  and  85  provide communication passageways through which one or more rinsing/drying fluids may enter the chamber  50  for processing the wafer surfaces. In the illustrated embodiment, rinsing/drying fluids are delivered from above the wafer  55  to inlet  70  through a fluid supply tube  115  having a fluid outlet nozzle  120  disposed proximate inlet  70 . Fluid supply tube  115  extends centrally through the rotor  15  and is preferably concentric with the axis rotation  47 . Similarly, rinsing/drying fluids are delivered from below the wafer  55  to inlet  85  through a fluid supply tube  125 . Fluid supply tube  125  terminates at a nozzle  130  near inlet  85 . Although nozzles  120  and  130  terminate at a position that is spaced from their respective inlets, tubes  115  and  125  may be extended so that gaps  135  are not present. Rather, nozzles  120  and  130  or tubes  115  and  125  may include rotating seal members that abut and seal with the respective upper and lower chamber members  60  and  75  in the regions of the inlets  70  and  85 .  
         [0028]     During processing, one or more rinsing/drying fluids are individually or concurrently supplied through fluid supply tubes  115  and  125  and inlets  70  and  85  for contact with the surfaces of the workpiece  55  in the chamber  50 . Preferably, the housing  20  is rotated about axis  47  by the rotor  15  during processing to generate a continuous flow of any fluid within the chamber  50  across the surfaces of the workpiece  55  through centrifugal force. Rinsing/drying fluid entering the inlet openings  70  and  85  are thus driven across the workpiece surfaces in a direction radially outward from the center of the workpiece  55  to the edge of the workpiece  55 . At the edge of the workpiece  55 , any spent rinsing/drying fluid is directed to exit the chamber  50  through outlets  100 . Spent rinsing/drying fluids may be accumulated in a cup reservoir disposed below and/or about the rinser/dryer housing  20 .  
         [0029]      FIG. 2  is a perspective view of a further rinser/dryer construction wherein the rinser/dryer is disposed at a fixed processing station and can open and close to facilitate insertion and extraction of the workpiece. The rinser/dryer, shown generally at  200 , has upper and lower chamber members,  205  and  210 , respectively. As in the prior embodiment, the upper chamber member  205  includes a generally planar chamber face  215  having a centrally disposed inlet  220 . Although not shown in the view of  FIG. 2 , the lower chamber member  210  likewise has a generally planar interior chamber face  225  having a central inlet  230 . The upper chamber member  205  includes a downwardly extending sidewall  235  that, for example, may be formed from a sealing polymer material or may be formed integrally with other portions of member  205 .  
         [0030]     The upper and lower chamber members,  205  and  210 , are separable from one another to accept a workpiece. With a workpiece disposed between them, the upper and lower chamber members,  205  and  210 , move toward one another to form a chamber in which the workpiece is supported in a position in which it is spaced from the planar interior chamber faces  215  and  225 . In the embodiment of the rinser/dryer disclosed in  FIGS. 2-8B , the workpiece, such as a semiconductor wafer, is clamped in place in the chamber formed by the upper and lower chamber members,  205  and  210 , between a plurality of support members  240  and corresponding spacing members  255  when the upper and lower chamber members are joined to form the chamber (see  FIG. 7B ). Axial movement of the upper and lower chamber members toward and away from each other is facilitated by a plurality of fasteners  307 . Preferably, the fasteners  307  bias the upper and lower chambers to a closed position as illustrated at  FIG. 7A .  
         [0031]     In the disclosed embodiment, the wafer support members  240  extend about a peripheral region of the upper chamber member  205  at positions that are radially exterior of the sidewall  235 . The wafer support members  240  are preferably disposed for linear movement along respective axes  245  to allow the support members  240  to clamp the wafer against the spacing members  255  when the upper and lower chamber members are disposed in a closed position (see  FIG. 7A ), and to allow the support members  240  to release the wafer from such clamping action when the upper and lower chamber members are separated (see  FIG. 8A ). Each support member  240  includes a support arm  250  that extends radially toward the center of the upper chamber member  205 . An end portion of each arm  250  overlies a corresponding spacing member  255  that extends from the interior chamber face  215 . Preferably, the spacing members  255  are each in the form of a cone having a vertex terminating proximate the end of the support arm  250 . Notches  295  are disposed at peripheral portions of the lower chamber member  210  and engage rounded lower portions  300  of the wafer support members  240 . When the lower chamber member  210  is urged upward to the closed position, notches  295  engage end portions  300  of the support members  240  and drive them upward to secure the wafer  55  between the arms  250  of the supports  240  and the corresponding spacing members  255 . This closed state is illustrated in  FIG. 5 . In the closed position, the notches  295  and corresponding notches  296  of the upper chamber member (see  FIG. 2 ) provide a plurality of outlets at the peripheral regions of the rinser/dryer  200 . Radial alignment of the arm  250  of each support member  240  is maintained by a set pin  308  that extends through lateral grooves  309  disposed through an upper portion of each support member.  
         [0032]     The construction of the fasteners  307  that allow the upper and lower chamber members to be moved toward and away from one another is illustrated with respect to  FIGS. 2, 6  and  7 B. As shown, the lower chamber member  210  includes a plurality of hollow cylinders  270  that are fixed thereto and extend upward through corresponding apertures  275  at the peripheral region of the upper chamber member  205  to form lower portions of each fastener  307 . Rods  280  extend into the hollow of the cylinders  270  and are secured therein to form an upper portion of each fastener  307 . Together, the rods  280  and cylinders  270  form the fasteners  307  that allow relative linear movement between the upper and lower chamber members,  205  and  210 , along axis  283  between the open and closed position. Two flanges,  285  and  290 , are disposed at an upper portion of each rod  280 . Flange  285  functions as a stop member that limits the extent of separation between the upper and lower chamber members,  205  and  210 , in the open position. Flanges  290  provide a surface against which a biasing member, such as a spring (see  FIG. 6 ) or the like, acts to bias the upper and lower chamber members,  205  and  210 , to the closed position.  
         [0033]     With reference to  FIG. 6 , the spring  303  or the like, has a first end that is positioned within a circular groove  305  that extends about each respective fastener  307 . A second end of each spring is disposed to engage flange  290  of the respective fastener  307  in a compressed state thereby causing the spring to generate a force that drives the fastener  307  and the lower chamber member  210  upward into engagement with the upper chamber member  205 .  
         [0034]     The rinser/dryer  200  is designed to be rotated about a central axis during processing of the workpiece. To this end, a centrally disposed shaft  260  extends from an upper portion of the upper chamber member  205 . As will be illustrated in further detail below in  FIGS. 7A-8B , the shaft  260  is connected to engage a rotary drive motor for rotational drive of the rinser/dryer  200 . The shaft  260  is constructed to have a centrally disposed fluid passageway (see  FIG. 4 ) through which a processing fluid may be provided to inlet  220 . Alternatively, the central passageway may function as a conduit for a separate fluid inlet tube or the like.  
         [0035]     As illustrated in  FIGS. 3 and 4 , a plurality of optional overflow passageways  312  extend radially from a central portion of the upper chamber member  205 . Shaft  260  terminates in a flared end portion  315  having inlet notches  320  that provide fluid communication between the upper portion of processing chamber  310  and the overflow passageways  312 . The flared end  315  of the shaft  260  is secured with the upper chamber member  205  with, for example, a mounting plate  325 . Mounting plate  325 , in turn, is secured to the upper chamber member  205  with a plurality of fasteners  330  ( FIG. 5 ). Overflow passages  312  allow processing fluid to exit the chamber  310  when the flow of fluid to the chamber  310  exceeds the fluid flow from the peripheral outlets of the chamber.  
         [0036]      FIGS. 7A and 7B  are cross-sectional views showing the rinser/dryer  200  in a closed state and connected to a rotary drive assembly, shown generally at  400 , while  FIGS. 8A and 8B  are similar cross-sectional views showing the rinser/dryer  200  in an opened state. As shown, shaft  260  extends upward into the rotary drive assembly  400 . Shaft  260  is provided with the components necessary to cooperate with a stator  405  to form a rotary drive motor assembly  410 .  
         [0037]     As in the embodiment of  FIG. 1 , the upper and lower chamber members  205  and  210  join to define the substantially closed rinser/dryer chamber  310  that, in the preferred embodiment, substantially conforms to the shape of the workpiece  55 . Preferably, the wafer  55  is supported within the chamber  310  in a position in which its upper and lower faces are spaced from the interior chamber faces  215  and  225 . As described above, such support is facilitated by the support members  240  and the spacing members  255  that clamp the peripheral edges of the wafer  55  when the rinser/dryer  200  is in the closed position of  FIGS. 7A and 7B .  
         [0038]     It is in the closed state of  FIGS. 7A and 7B  that processing of the wafer  55  takes place. With the wafer secured within the rinser/dryer chamber  310 , processing fluid is provided through passageway  415  of shaft  260  and inlet  220  into the interior of chamber  310 . Similarly, processing fluid is also provided to the chamber  310  through a processing supply tube  125  that directs fluid flow through inlet  230 . As the rinser/dryer  200  is rotated by the rotary drive motor assembly  410 , any fluid supplied through inlets  220  and  230  is driven across the surfaces of the wafer  55  by forces generated through centrifugal acceleration. Spent processing fluid exits the processing chamber  310  from the outlets at the peripheral regions of the rinser/dryer  200  formed by notches  295  and  296 . Such outlets exist since the support members  240  are not constructed to significantly obstruct the resulting fluid flow. Alternatively, or in addition, further outlets may be provided at the peripheral regions.  
         [0039]     Once processing has been completed, the rinser/dryer  200  is opened to allow access to the wafer, such as shown in  FIGS. 8A and 8B . After processing, actuator  425  is used to drive an actuating ring  430  downward into engagement with upper portions of the fasteners  307 . Fasteners  307  are driven against the bias of spring  303  causing the lower chamber member  210  to descend and separate from the upper chamber member  205 . As the lower chamber member  210  is lowered, the support members  240  follow it under the influence of gravity or a biasing member while concurrently lowering the wafer  55 . In the lower position, the rinser/dryer chamber  310  is opened thereby exposing the wafer  55  for removal and/or allowing a new wafer to be inserted into the rinser/dryer  200 . Such insertion and extraction can take place either manually, or by an automatic robot.  
         [0040]      FIGS. 9 and 10  illustrate two different types of processing tools, each of which may employ one or more processing stations including the rinser/dryer constructions described above.  FIG. 9  is a schematic block diagram of a tool, shown generally at  600 , including a plurality of processing stations  605  disposed about an arcuate path  606 . The processing stations  605  may all perform similar processing operations on the wafer, or may perform different but complementary processing operations. For example, one or more of the processing stations  605  may execute an electrodeposition process of a metal, such as copper, on the wafer, while one or more of the other processing stations perform complementary processes such as, for example, clean/dry processing, pre-wetting processes, photoresist processes, etching processes, etc.  
         [0041]     Wafers that are to be processed are supplied to the tool  600  at an input/output station  607 . The wafers may be supplied to the tool  600  in, for example, S.M.I.F. pods, each having a plurality of the wafers disposed therein. Alternatively, the wafers may be presented to the tool  600  in individual rinser/dryer housings, such as at  20  of  FIG. 1 .  
         [0042]     Each of the processing stations  605  may be accessed by a robotic arm  610 . The robotic arm  610  transports the rinser/dryer housings, or individual wafers, to and from the input/output station  607 . The robotic arm  610  also transports the wafers or housings between the various processing stations  605 .  
         [0043]     In the embodiment of  FIG. 9 , the robotic arm  610  rotates about axis  615  to perform the transport operations along path  606 . In contrast, the tool shown generally at  620  of the  FIG. 10  utilizes one or more robotic arms  625  that travel along a linear path  630  to perform the required transport operations. As in the embodiment of  FIG. 9 , a plurality of individual processing stations  605  are used, but more processing stations  605  may be provided in a single processing tool in this arrangement.  
         [0044]      FIG. 11  illustrates one manner of controlling the provision of rinsing/drying fluids that are supplied to the rinser/dryer of any of the foregoing embodiments. As illustrated, the fluid supply system, shown generally at  800 , includes a nitrogen gas supply  805 , an IPA supply  810 , an IPA vaporizer  815 , a DI water supply  820 , optional heating elements  825 , optional flowmeters  830 , optional flow regulators/temperature sensors  835 , and valve mechanism  840 . All of the various components of the system  800  may be under the control of a controller unit  845  having the appropriate software programming.  
         [0045]     In operation of the rinser/dryer, the valve mechanism  840  is connected to supply DI water from supply  820  to both the upper and lower inlets of the rinser/dryer chamber. As the water is supplied to the chamber, the wafer is spun at, for example, a rate of 200 RPM. This causes the water to flow across each surface of the wafer under the action of centrifugal acceleration. Once a sufficient amount of water has been supplied to the chamber to rinse the wafer surfaces, valve mechanism  840  is operated to provide a drying fluid, preferably comprised of nitrogen and IPA vapor, to both the upper and lower inlets of the rinser/dryer chamber. Valve mechanism  840  is preferably operated so that the front of the drying fluid immediately follows the trailing end of the DI water. As the drying fluid enters the chamber, centrifugal acceleration resulting from the spinning of the wafer drives the drying fluid across the wafer surface and follows a meniscus across the wafer surface formed by the DI water. The IPA vapor assists in providing a drying of the surface of the wafer at the edge of the meniscus. Drying of the wafer may be further enhanced by heating the DI water and/or the nitrogen/IPA vapor using heating elements  825 . The particular temperature at which these fluids are supplied may be controlled by the controller  845 . Similarly, flow regulators  835  and flowmeters  830  may be used by controller  845  to regulate the flow of the DI water and/or the nitrogen/IPA vapor to the rinser/dryer chamber.  
         [0046]     On an individual wafer basis, the drying time for the individual wafer in the disclosed systems is substantially reduced when compared to the more traditional Marangoni process implementations. The drying time in such processes is governed by the following equation: t=d/v  
         [0000]     where:  
         [0000]    
       
          t=drying time;  
          d=wafer diameter; and  
          v=meniscus velocity.  
       
     
         [0050]     As such, the drying time is directly proportional to the diameter of the wafer, which is the distance that the meniscus travels over the wafer surface. In the rinser/dryer of the present invention, the meniscus originates at the center of the wafer and, as such, experiences a travel distance that is effectively ½ of the total diameter of the wafer. This results in a drying time that is approximately ½ of the drying time experienced in a typical Marangoni processor in which the entire wafer is submersed in the rinsing fluid and gradually extracted therefrom.  
         [0051]     The foregoing constructions also give rise to the ability to perform sequential processing of a single wafer using two or more rinsing/drying fluids sequentially provided through a single inlet of the reaction chamber. Still further, the ability to concurrently provide different fluids to the upper and lower surfaces of the wafer opens the opportunity to implement novel rinsing/drying processing operations.  
         [0052]     The present invention has been illustrated with respect to a wafer. However, it will be recognized that the present invention has a wider range of applicability. By way of example, the present invention is applicable in the processing of disks and heads, flat panel displays, microelectronic masks, and other devices requiring effective and controlled wet processing.  
         [0053]     Numerous modifications may be made to the foregoing system without departing from the basic teachings thereof. Although the present invention has been described in substantial detail with reference to one or more specific embodiments, those of skill in the art will recognize that changes may be made thereto without departing from the scope and spirit of the invention as set forth in the appended claims.