Abstract:
An apparatus and method for conditioning a polishing pad in a polishing system. One embodiment of the apparatus generally includes a movable support member, a conditioner device coupled to the support member, and a first actuator coupled to the support member and adapted to move the conditioner device along a first path. Another embodiment of the apparatus generally includes a platen, a polishing pad supported on the platen, and a conditioner device coupled to a support member and positioned adjacent a region of the polishing pad outside of a substrate polishing area. One embodiment of the method includes raising a conditioner device adjacent to the polishing pad, providing relational movement between the conditioner device and the polishing pad, and lowering the conditioner device away from the polishing pad.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims benefit of U.S. provisional patent application serial No. 60/212,195, filed Jun. 16, 2000, which is herein incorporated by reference. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention generally relates to an apparatus and a method for conditioning a polishing pad in a polishing system.  
           [0004]    2. Background of the Related Art  
           [0005]    Integrated circuits are typically formed on substrates, particularly silicon wafers, by the sequential deposition of conductive, semi-conductive, or insulative layers. Generally, after a series of layers are sequentially deposited and etched, the uppermost surface may become non-planar and require planarization. A substantially planar surface is necessary to ensure accurate lithography needed to produce small feature sizes.  
           [0006]    Chemical mechanical polishing (CMP) is one accepted method of planarization. In CMP, a substrate is typically placed feature-side down on a polishing pad located on a platen. During one conventional polishing process, the polishing pad is rotated by the platen while a carrier rotates the substrate while holding the substrate against the pad by applying pressure to the back of the substrate. The polishing pad can be a removable pad that is attached to the platen for a useful life of the pad and then replaced. One CMP polishing system that utilizes removable pads is a MIRRA® CMP System available from Applied Materials, Inc., as shown and described in U.S. Pat. No. 5,804,507, issued Sep. 8, 1998, entitled “Radially Oscillating Carousel Processing System for Chemical Mechanical Polishing,” which is hereby incorporated by reference in its entirety.  
           [0007]    Alternatively, the pad can be a sheet of polishing material that is incrementally indexed or advanced across a platen as the material wears. This type of system is conventionally known as a “web” system. The web-based system seeks to utilize the continuous feed of polishing pad material by incrementally indexing fresh or new polishing pad material. One CMP web-based polishing system is shown and described in copending U.S. patent application Ser. No. 09/244,456, entitled “Apparatus and Methods for Chemical Mechanical Polishing With an Advanceable Polishing Sheet,” the entirety of which is hereby incorporated by reference. Another CMP polishing system that utilizes the web-based system is the 8200C Polishing System available from Obsidian, Inc., as shown and described in co-pending U.S. patent application Ser. No. 60/185,812, entitled “Planarization System With Multiple Polishing Pads”, the entirety of which is hereby incorporated by reference.  
           [0008]    In some systems, a substrate is polished on a pad in the presence of a polishing fluid, also known as a slurry, which may contain chemicals that pacify or oxidize the layer being polished and abrasives that abrasively remove or polish off the surface of the layer. The interaction of a polishing pad, the chemically reactive polishing fluid, and the abrasive polishing fluid with the surface of the substrate imparts a combination of chemical and mechanical forces to the substrate which planarizes the substrate surface and results in controlled polishing of the exposed layer.  
           [0009]    In a fixed-abrasive system, a polishing pad called a fixed abrasive pad is used which does not require abrasive particles within the slurry. Typically, a polishing fluid without abrasive particles is used in concert with the fixed abrasive pad to provide the chemical component of the polishing process. Examples of such fixed abrasive pads are pads available from the 3M Company of St. Paul, Minn. described in U.S. Pat. No. 5,692,950, by Rutherford et al. (issued Dec. 2, 1997) and U.S. Pat. No. 5,453,312, by Haas et al. (issued Sep. 26, 1995), both of which are hereby incorporated by reference.  
           [0010]    Generally, the fixed abrasive pad contains abrasive particles suspended in a binder or polymer film that is disposed on a web of backing material that abrade the substrate in the planarization process. Typically, a layer of binder on a surface of the fixed abrasive pad does not contain any abrasive particles. As such, before the fixed abrasive pad can be used, the layer of abrasive-free binder on the surface of the abrasive pad must be removed by a conditioning process before the pad can be effectively used. Moreover, the conditioning process may be necessary to place the pad in a condition that produces consistent and reliable polishing results.  
           [0011]    Therefore, there is a need for a system and method for conditioning polishing pads in a substrate processing system and particularly for conditioning fixed abrasive pads.  
         SUMMARY OF THE INVENTION  
         [0012]    An apparatus and method for conditioning a polishing pad in a polishing system. One embodiment of the apparatus generally includes a movable support member, a conditioner device coupled to the support member, and a first actuator coupled to the support member and adapted to move the conditioner device along a first path. Another embodiment of the apparatus generally includes a platen, a polishing pad supported on the platen, and a conditioner device coupled to a support member and positioned adjacent a region of the polishing pad outside of a substrate polishing area. One embodiment of the method includes raising a conditioner device adjacent to the polishing pad, providing relational movement between the conditioner device and the polishing pad, and lowering the conditioner device away from the polishing pad. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    So that the manner in which the above recited features, advantages and objects of the present invention are attained and can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof which are illustrated in the appended drawings.  
         [0014]    It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.  
         [0015]    [0015]FIG. 1 is a top plan view of a substrate polishing apparatus of the present invention.  
         [0016]    [0016]FIG. 2 is a side cross-sectional view of a substrate carrier and a platen.  
         [0017]    [0017]FIG. 3 is a perspective view of one embodiment of a conditioner device.  
         [0018]    [0018]FIG. 3 a  is a top view of the conditioning bar of FIG. 3 attached to a gimbal device.  
         [0019]    [0019]FIG. 4 is a side cross-sectional view of the conditioner device of FIG. 3 in a lower retracted position.  
         [0020]    [0020]FIG. 5 is a side cross-sectional view of the conditioner device of FIG. 3 in an upper extended position.  
         [0021]    [0021]FIG. 6 is an end view of the conditioner device of FIG. 3.  
         [0022]    [0022]FIG. 7 is a flow chart of one embodiment of a method of the present invention.  
         [0023]    [0023]FIG. 8 is a perspective view of another embodiment of a conditioner device. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0024]    [0024]FIG. 1 depicts a top plan view of a CMP system  10  in which embodiments of the invention can be used to advantage or otherwise practiced is disclosed and described in U.S. patent application Ser. No. 09/244,456 assigned to Applied Materials, Inc., located in Santa Clara, Calif. which application is incorporated herein by reference. The system  10  generally includes three platens  12  and a loading station  14  disposed on a baseplate  16 . A carousel  18  having four arms  20  is centrally disposed on the baseplate  16  whereby each arm  20  supports a substrate carrier  22  and positions each substrate carrier  22  over the loading station  14  or over one of the platens  12 . Two of the arms  20  depicted in FIG. 1 are shown in phantom to allow one of the platens  12  and the loading station  14  to be seen. A conditioner device  90 , which will be described in more detail below, is disposed adjacent each platen  12 .  
         [0025]    The carousel  18  is rotatable to move the substrate carriers  22  from one loading station  14  or platens  12  to another. Generally, the process of polishing a substrate comprises having a substrate loaded into each substrate carrier  22 . The substrate carriers  22  move the substrates from the loading station  14  to each platen  12  for processing and back to the loading station  14  to be unloaded. Polishing pads are disposed on the three platens  12 . Alternatively, polishing pads are disposed on the first two platens with a cleaning pad disposed on the third platen to facilitate substrate cleaning at the end of the polishing process.  
         [0026]    Disposed on the baseplate  16  adjacent to each platen  12  is a rotatable rinse arm  80  which includes a plurality of nozzles  82  positioned and adapted to deliver a fluid to the horizontal top surface  62  of the platens  12 . Two or more supply tubes (not shown) are connected to the nozzles  82  and provide a polishing fluid and/or a cleaning fluid to each nozzle  82 . The polishing fluid can comprise chemical polishing agents, de-ionized water, abrasive particles, or a combination thereof to provide the chemical component and mechanical component of the polishing process. Alternatively, the polishing pad can provide the abrasive particles and/or chemical polishing agents. The cleaning fluid typically comprises de-ionized water or other fluids to remove any debris, loose material, or other contamination from the abrasive elements or from the upper surface of the polishing pad.  
         [0027]    A loading robot  24 , an input buffer station  28 , and an output buffer station  26  are disposed on the baseplate  16  adjacent the loading station  14 . The loading robot  24  transfers unpolished substrates from the input buffer station  28  to the loading station  14  and transfers polished substrates from the loading station  14  to the output buffer station  26 .  
         [0028]    The system can further include a factory interface  30  which can be formed integrally with the system or can be a separate component disposed adjacent to the baseplate  16  near the loading station  14 . The factory interface  30  generally comprises a cleaning module  32 , an input module  34 , an interface robot  36 , and one or more wafer cassettes  38 . The interface robot  36  is employed to move substrates between the wafer cassettes  38 , the cleaning module  32 , and the input module  34 . A transfer robot  40  is disposed proximate the factory interface  30  and the baseplate  16  to move substrates from the cleaning module  32  and/or input module  34  to the input buffer station  28  and from the output buffer station  26  back to the cleaning module  32  or alternatively the input module  34 .  
         [0029]    [0029]FIG. 2 illustrates a side cross-sectional view of one of the platens  12  of the CMP system  10  with a substrate carrier  22  supported thereabove. The platen  12  is mounted on a shaft  50  which is rotationally disposed through the baseplate  16  using conventional bearings and slip rings such that electrical, mechanical, pneumatic, control signals, and other connections can be coupled between the baseplate  16  and the platen  12 . The shaft  50  is typically coupled to a motor  52  that provides the rotational motion of the platen  12  during polishing. Alternative embodiments other than a rotatable platen  12  can be used to create relative movement between the substrate and the polishing pad in order to enhance uniform polishing of the substrate surface and uniform wearing of the polishing pad. For example, a substrate carrier can rotate the substrate or move the substrate laterally across the surface of the polishing pad, the polishing pad can move while the substrate carrier positions the substrate on the polishing pad, or a combination of these approaches can be performed.  
         [0030]    For the rotatable platen  12 , a supply roll  56  and a take-up roll  58  are disposed on opposite sides of the platen  12  such that a polishing pad  60 , such as a fixed abrasive pad manufactured by 3M Company of St. Paul, Minn. or other type of polishing pad, can be wound on the rolls  56 ,  58  and run between the rolls  56 ,  58  over the horizontal top surface  62  of the platen  12 . An indexing device (not shown) indexes or advances the polishing pad  60  a predetermined amount across the horizontal top surface  62  of the platen  12  intermittently between the processing steps to supply a fresh area of the polishing pad  60  to the horizontal top surface  62 . Thus, when the polishing pad  60  is indexed, new polishing pad material is supplied by the supply roll  56  and used polishing material is wound on the take-up roll  58 . However, other embodiments of the polishing system can be devised which use a different type of polishing pad, such as a removable pad attached to the platen for the useful life of the pad or a combination of a removable pad and a web-based pad.  
         [0031]    The substrate carrier  22 , such as a TITAN HEAD™ substrate carrier manufactured by Applied Materials, Inc., Santa Clara, Calif. or other type of substrate carrier, generally comprises of a housing  66  with a retaining ring  68  which defines a center recess  70  to hold a substrate  72  face down on the polishing pad  60  during polishing. The retaining ring  68  is typically disposed around the outer perimeter of the substrate  72  to contain the substrate  72  and prevent the substrate  72  from slipping laterally during polishing. The substrate carrier  22  is mounted on a shaft  76  connected to a drive system  77  disposed on the arm  20  of the carousel  18 . The drive system  77  is adapted to rotate the substrate carrier  22 , move the substrate carrier  22  laterally, and to move the substrate carrier  22  vertically towards or away from the platen  12  during polishing.  
         [0032]    The conditioner device is adapted to contact and to abrade a surface of a polishing pad. The conditioning bar removes film from the surface of the polishing pad to reveal the abrasive particles embedded in the polishing pad  60  and/or textures the surface of the polishing pad  60  to form a uniform polishing surface. FIG. 3 is a perspective view of one embodiment of a conditioner device  90  comprising a conditioning bar  92 . The conditioning bar  92  can be a ceramic bar, a brush bar, or a diamond abrasive bar where the part of the conditioning bar  92  that contacts the polishing pad is respectively made of ceramic, brush bristles, or diamond chips connected thereto. In addition, the conditioning bar  92  can be made of any materials that will condition, texture, or abrade the surface of the polishing pad.  
         [0033]    The conditioning bar  92  is attached to a support member  94  by a universal holder  110  which can releasably hold different types of conditioning bars  92  so that the conditioning bar  92  can be quickly replaced or different conditioning bars can be quickly mounted on the support member  94 . One embodiment of the universal holder  110  is a fastener connected to the support member  94  with four threaded holes for receiving four screws. As shown in FIG. 3 and FIG. 3 a,  the conditioner device  90  can further include a gimbal device  112  disposed or connected between the universal holder  110  to the support member  94  which enables the conditioning bar  92  to provide uniform pressure to the surface of the polishing pad.  
         [0034]    The conditioner device  90  can also include a spray bar  122 , having a plurality of spray nozzles  124 , mounted on the support member  94 . The spray nozzles  124  are adapted to provide at least one fluid across the width of the polishing pad to wash away debris and abraded material on the polishing pad. There is no need for the spray bar  122  or nozzles  124  to be in contact with the polishing pad. A hose  125  is connected to the spray bar  122  and adapted to be coupled to a fluid supply source (not shown) to provide fluid to the spray nozzles  124 . The fluid can also comprise a hot liquid in order to melt the polymer film that coats the polishing pad. The force and the direction of the spray nozzles  124 , the temperature of the fluid, and the type of fluids can be varied in order to enhance removal of debris and the polymer film from the surface of the polishing pad  60 .  
         [0035]    The support member  94  is connected to a first actuator  96  which is disposed on a slide  98  connected to a support frame  100 . When engaged, the first actuator  96  raises the conditioning bar  92  and the spray bar  122  from a lower retracted position to an upper extended position. A second actuator  106  is mounted on the support frame  100  and is connected to the housing of the first actuator  96  to move the first actuator  96  laterally on the slide  98  and thereby to move the conditioning bar  92  and the spray bar  122  laterally. In the embodiment shown in FIG. 3, the actuators  96 ,  106  are pneumatic cylinders. The actuators can also be motors, gears, pulleys, pistons, or any other devices that can create movement.  
         [0036]    In addition, other conditioning devices can be devised to abrade the surface of the polishing pad other than a conditioning bar. For instance as shown in FIG. 8, the conditioner device  90  can comprise of spray nozzles  124  adapted to condition the polishing pad only by the action of the sprayed fluids on the polishing pad without the aid of the conditioning bar. In addition, the conditioner device can comprise of a roller (not shown) which conditions the polishing pad by rotating against the surface of the polishing pad. For example, the roller can be a ceramic roller, a brush roller, or a diamond abrasive roller where the part of the roller that contacts the polishing pad is respectively made of ceramic, brush bristles, or diamond chips connected thereto. In addition, a combination of approaches can be devised to abrade the surface of the polishing pad. Furthermore, other movement elements other than an actuator, adapted to move the conditioner device horizontally, can be devised to create relative movement between the conditioner device and the polishing pad. For example, movement can be created by a conditioning roller, a moveable support member attached to the platen, a moveable platen, or by advancement of the polishing pad.  
         [0037]    [0037]FIG. 4 is a side cross-sectional view of the conditioner device  90  of FIG. 3 disposed in a CMP system where the first actuator is disengaged and the conditioning bar  92  and the spray bar  122  are in a lower retracted position. The support frame  100  of the conditioner device  90  is coupled to the bottom of the baseplate  16  so that the support member  100  extends through an aperture  102  in the baseplate  16  and so that the conditioning bar  92  and the spray bar  122  reside in a storage recess  104  in the baseplate  16 . When in a lower, retracted position, the conditioning bar and the spray bar  122  do not obstruct rotational movement of the platen  12  and, therefore, allow polishing of the substrate  72 .  
         [0038]    [0038]FIG. 5 is a side cross-sectional view of the conditioner device  90  of FIG. 3 when the first actuator is engaged and the conditioning bar  92  and the spray bar  122  are in an upper, extended position. The conditioning bar  92  is in contact with the polishing pad  60  on the platen  12  between the supply roll  56  and the horizontal top surface  62  of the platen  12 . However, other embodiments of the conditioner device  90  can be devised so that the conditioning bar  92  is adapted to contact any portion of the polishing pad  60 . In one embodiment, the conditioning bar  92  contacts and conditions a region of the polishing pad  60  which has not reached the substrate polishing area (the area under which the substrate carrier  22  positions the substrate  72  on the polishing pad  60  during polishing) to condition that region of the polishing pad  60  before its use in polishing the substrate  72 .  
         [0039]    The conditioner device  90  can further include a flexible bellows  126  attached to the base of the storage recess  104  in the baseplate  16  and to an upper portion of the support member  94  to protect the conditioner device  90  from fluids delivered by the spray nozzles  124  or by other sources. The platen can further include a backing plate  114  disposed thereon such that when the conditioning bar  92  contacts the polishing pad  60 , the polishing pad is sandwiched between the conditioning bar  92  and the backing plate  114  on the platen  12  in order to prevent movement of the polishing pad  60  as the conditioning bar  92  abrades the surface of the polishing pad  60 . The polishing system  10  can further include a controller  130  that integrates the conditioning of the polishing pad  60  and the polishing of the substrates. Lines  131 ,  132 ,  133 ,  134  couple the controller  130  respectively to the conditioner device  90 , to the platen  12 , to the motor  52  of the platen  12 , and to the drive system  76  of the substrate carrier  22 . In operation, the controller  130  through line  131  signals the first actuator  96  to extend the support member  94  from the storage recess  104  to contact the polishing pad  60  or to retract the support member  94  away from the polishing pad  60 , signals the second actuator  106  to extend and to retract in order to create relational movement between the conditioner device  90  and the polishing pad  60 , and directs the fluid supply source to provide fluid to the spray nozzles  124 . The controller  130  through line  133  signals the motor  52  to rotate the platen  12  in order to create relational movement between the polishing pad  60  and the substrate  72 . The controller  130  through line  134  signals the drive system  76  to move the substrate carrier  22  either over or away from the platen  12 . The controller  130  through line  132  directs the supply roll  56  and the take-up roll  58  to advance the polishing pad  60  by a certain amount.  
         [0040]    [0040]FIG. 6 is an end view of the conditioner device  90  of FIG. 3 when the first actuator is engaged and the conditioning bar  92  and the spray bar  122  are in an upper extended position. In the upper extended position, the conditioner device  90  contacts the polishing pad. The second actuator  106  moves the conditioning bar  92  laterally across the surface of the polishing pad to abrade and condition the polishing pad  60 . The length of conditioning bar  92  is determined by the width of the polishing pad is desired to be conditioned. In one embodiment, the conditioning bar  92  spans a width greater than the width of the polishing pad  60  so that the conditioning bar  92  substantially remains in contact with the entire width of the polishing pad  60  as it moves laterally across the surface of the polishing pad  60 .  
         [0041]    [0041]FIG. 7 is a flow chart of one method of conditioning a polishing pad  60 . The conditioning bar  92  and the spray bar  122  are raised from the storage recess  104  of the baseplate  16  to contact the polishing pad  60 . The conditioning bar  92  is then moved laterally making at least one stroke across the surface of the polishing pad  60  to abrade the surface of the polishing pad  60 . The spray nozzles  124  deliver a fluid across the width of the polishing pad  60  that has been abraded or is being abraded by the conditioning bar  92  to rinse away debris and abraded material from the surface of the polishing pad  60 . In one embodiment, the spray nozzles  124  deliver a fluid to the polishing pad  60  simultaneously as the conditioning bar  92  is moved laterally across the surface of the polishing pad  60 . The conditioning bar  92  and the spray nozzles  124  are then lowered into the baseplate  16  to allow movement of the platen  12 . The polishing pad  60  is indexed or advanced by a length that is no greater than the area just conditioned by the conditioning bar  90 . The polishing pad need not be advanced to cover the entire area of the substrate polishing area. The substrate polishing area can be continuously replenished with new conditioned pad by indexing or advancing a small portion of the polishing pad intermittently between a desired number of polishing steps. The platen  12  is then rotated to polish the surface of the substrate  72 . The steps for the method of conditioning the polishing pad  60  can be performed in other orders. For example, the polishing pad  60  can be indexed before the conditioning bar  92  is moved into contact with the polishing pad  60 .  
         [0042]    While foregoing is directed to the preferred embodiment of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.