Abstract:
Methods and apparatus for delivering a polishing fluid to a chemical mechanical polishing surface is provided. In one aspect, the apparatus comprises a vertical arm having a delivery portion located proximate to a circumference of a polishing surface, a first nozzle disposed on the delivery portion and adapted to dispense the polishing fluid with a first adjustable droplet size, and at least a second nozzle disposed on the delivery portion and adapted to dispense the polishing fluid with a second adjustable droplet size. In another aspect of the invention, the apparatus comprises a horizontal arm having a delivery portion disposed at least partially over a polishing surface, a first nozzle disposed on the delivery portion and adapted to dispense the polishing fluid with a first adjustable droplet size across a first region of the polishing surface, and at least a second nozzle disposed horizontally spaced from the first nozzle on the delivery portion, and adapted to dispense the polishing fluid with a second adjustable droplet size across a second region of the polishing surface.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims benefit of U.S. provisional patent application Ser. No. 60/592,669, filed Jul. 30, 2004, which is herein incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     Embodiments of the present invention generally relate to a slurry delivery method and apparatus for polishing a substrate in a chemical mechanical polishing system.  
         [0004]     2. Description of the Related Art  
         [0005]     Chemical mechanical planarization, or chemical mechanical polishing (CMP), is a common technique used to planarize substrates. Chemical mechanical planarization systems generally utilize a polishing head to retain and press a substrate against a polishing surface of a polishing material while providing motion therebetween. In conventional CMP techniques, a substrate carrier or polishing head is mounted on a carrier assembly and positioned in contact with a polishing article in a CMP apparatus. The carrier assembly provides a controllable pressure to the substrate urging the substrate against the polishing article. The article is moved relative to the substrate by an external driving force. Thus, the CMP apparatus effects polishing or rubbing movement between the surface of the substrate and the polishing article while dispersing a polishing composition to effect both chemical activity and mechanical activity.  
         [0006]     Some planarization systems utilize a polishing head that is moveable over a stationary platen that supports the polishing material. Other systems utilize different configurations including a rotating platen to provide relative motion between the polishing material and the substrate. A polishing fluid is typically disposed between the substrate and the polishing material during polishing to provide chemical activity that assists in the removal of material from the substrate. Some polishing fluids may also contain abrasives.  
         [0007]     One of the challenges in developing robust polishing systems and processes is providing uniform material removal across the polished surface of the substrate. For example, as the substrate travels across the polishing surface, the edge of the substrate is often polished at a higher rate. This is due in part to the tendency of the substrate to nose drive, that is, centrifugal and frictional forces force the substrate to move toward the exterior of the support surface as the substrate moves across the support surface.  
         [0008]     An additional problem with polishing uniformity is the distribution of slurry on the polishing surface. If the slurry is unevenly distributed, the polishing surface may not evenly polish across the substrate surface. If too little slurry is used, the polishing surface may distort the features of the substrate surface. If too much slurry is applied, valuable slurry may be wasted. Therefore, a system for delivering a polishing fluid to a chemical mechanical polishing surface that adjustably distributes and conserves slurry is needed.  
       SUMMARY OF THE INVENTION  
       [0009]     The present invention generally provides a method and apparatus for delivering a polishing fluid to a chemical mechanical polishing surface. In one aspect, an apparatus is provided for delivering a polishing fluid to a chemical mechanical polishing surface including a vertical arm having a delivery portion located proximate to a circumference of a polishing surface, a first nozzle disposed on the delivery portion and adapted to dispense the polishing fluid with a first adjustable droplet size, and at least a second nozzle disposed on the delivery portion and adapted to dispense the polishing fluid with a second adjustable droplet size.  
         [0010]     In another aspect, an apparatus is provided for delivering a polishing fluid to a chemical mechanical polishing surface including a horizontal arm having a delivery portion disposed at least partially over a polishing surface, a first nozzle disposed on the delivery portion and adapted to dispense the polishing fluid with a first adjustable droplet size across a first region of the polishing surface, and at least a second nozzle disposed horizontally spaced from the first nozzle on the delivery portion, and adapted to dispense the polishing fluid with a second adjustable droplet size across a second region of the polishing surface.  
         [0011]     In another aspect, an apparatus is provided for delivering a polishing fluid to a chemical mechanical polishing surface including a delivery arm, two or more nozzles disposed on a delivery portion of the delivery arm with each nozzle adapted to disperse the polishing fluid with an adjustable droplet size wherein each nozzle has an aperture that is independently controlled, a tubing system configured to supply fluid to the two or more nozzles, a pump system to provide a controlled pressure to the tubing system, and a control system to independently control each aperture of each nozzle and the pump system.  
         [0012]     In another aspect, a method is provided for delivering a polishing fluid to a chemical mechanical polishing surface including dispensing the polishing fluid onto the polishing material with a controlled droplet size across a first region of the polishing material, and dispensing the polishing fluid onto the polishing material with a controlled droplet size across a second region of the polishing material, wherein a first nozzle provides polishing fluid with an adjustable first angle between the arm and the first region of the polishing surface and at least second nozzle provides polishing fluid with an adjustable second angle between the arm and the second region of the polishing surface. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]     So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. 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.  
         [0014]      FIG. 1  is a sectional view of a polishing system having one embodiment of a polishing fluid delivery system.  
         [0015]      FIG. 2  is a plan view of the system of  FIG. 1 .  
         [0016]      FIG. 3  is a sectional view of an alternative embodiment of a polishing fluid delivery system.  
         [0017]      FIG. 4  is a sectional view of an additional alternative embodiment of a polishing fluid delivery system. 
     
    
     DETAILED DESCRIPTION  
       [0018]     The present invention provides a slurry delivery method and apparatus for polishing a substrate in a chemical mechanical polishing system. In one aspect, the invention provides a slurry delivery method and apparatus that utilizes a plurality of nozzles that may be configured to dispense droplets with adjustable size and adjustable droplet stream path angles.  
         [0019]     Examples of polishing systems which may be adapted to benefit from aspects of the invention are disclosed in U.S. Pat. No. 6,244,935 issued Jun. 12, 2001 by Birang, et al. and U.S. Pat. No. 5,738,574 issued Apr. 14, 1998 to Tolles, et al., both of which are incorporated by reference in their entirety.  
         [0020]      FIG. 1  depicts one embodiment of a polishing system  100  for polishing a substrate  112  having a polishing fluid delivery system  102  that controls the distribution of polishing fluid  114  across a polishing material  108 . Although the polishing fluid delivery system  102  is described in reference to the illustrative polishing system  100 , the invention has utility in other polishing systems that process substrates in the presence of a polishing film. The exemplary polishing system  100  includes a platen  104  and a polishing head  106 . The platen  104  is generally positioned below the polishing head  106  that holds the substrate  112  during polishing. The platen  104  is generally disposed on a base  122  of the system  100  and coupled to a motor (not shown). The motor rotates the platen  104  to provide at least a portion of a relative polishing motion between the polishing material  108  disposed on the platen  104  and the substrate  112 . Relative motion between the substrate  112  and the polishing material  108  may be provided by alternative mechanisms. For example, at least a portion of the relative motion between the substrate  112  and polishing material  108  may be provided by moving the polishing head  106  over a stationary platen  104 , moving the polishing material linearly under the substrate  112 , or moving both the polishing material  108  and the polishing head  106 .  
         [0021]     The polishing material  108  is supported by the platen  104  so that a polishing surface  116  faces upward towards the polishing head  106 . The polishing material  108  is fixed to the platen  104  by adhesives, vacuum, mechanical clamping, or other means during processing. Optionally, and particularly in applications where the polishing material  108  is configured as a web, belt, or linear polishing material, the polishing material  108  is fixed to the platen  104  and is releasable, typically by employing a vacuum disposed between the polishing material  108  and platen  104  as described in the previously incorporated U.S. Pat. No. 6,244,935.  
         [0022]     The polishing material  108  may be a conventional or a fixed abrasive material. Conventional polishing material  108  is generally comprised of a foamed polymer and disposed on the platen  104  as a pad. In one embodiment, the conventional polishing material  108  is foamed polyurethane. Such conventional polishing material  108  is available from Rodel Corporation, located in Newark, Del.  
         [0023]     Fixed abrasive polishing material  108  is generally comprised of a plurality of abrasive particles suspended in a resin binder that is disposed in discrete elements on a backing sheet. Fixed abrasive polishing material  108  may be utilized in either pad or web form. As the abrasive particles are contained in the polishing material, systems utilizing fixed abrasive polishing materials generally utilize polishing fluids that do not contain abrasives. Examples of fixed abrasive polishing material are disclosed in U.S. Pat. No. 5,692,950, issued Dec. 2, 1997 to Rutherford, et al., and U.S. Pat. No. 5,453,312, issued Sep. 26, 1995 to Haas, et al., both of which are hereby incorporated by reference in their entireties. Such fixed abrasive polishing material  108  is additionally available from Minnesota Manufacturing and Mining Company (3M), located in Saint Paul, Minn.  
         [0024]     The polishing head  106  generally is supported above the platen  104 . The polishing head  106  retains the substrate  112  in a recess  120  that faces the polishing surface  116 . The polishing head  106  typically moves toward the platen  104  and presses the substrate  112  against the polishing material  108  during processing. The polishing head  106  may be stationary or rotate or move orbitally, linearly, or in a combination of motions while pressing the substrate  112  against the polishing material  108 . One example of a polishing head  106  that may be adapted to benefit from the invention is described in U.S. Pat. No. 6,183,354 B1, issued Feb. 6, 2001 to Zuniga, et al., and is hereby incorporated by reference in its entirety. Another example of a polishing head  106  that may be adapted to benefit from the invention is a TITAN HEAD™ wafer carrier, available from Applied Materials, Inc., of Santa Clara, Calif.  
         [0025]     The polishing fluid delivery system  102  generally comprises a delivery arm  130 , a plurality of nozzles  132  disposed on the arm  130  and at least one polishing fluid source  134 . The delivery arm  130  is configured to meter polishing fluid  114  at different flow rates along the arm  130  to control the distribution of polishing fluid  114  on the polishing surface  116  of the polishing material  108 . As the polishing fluid  114  is generally supplied from a single source, the polishing fluid  114  may be disposed on the polishing material  108  in a uniform concentration but in varying volume across the surface of the polishing material  108 .  
         [0026]     The delivery arm  130  is generally coupled to the base  122  proximate to the platen  104 . The delivery arm  130  generally has at least a portion  136  that is suspended over the polishing material  108 . The delivery arm  130  may be coupled to other portions of the system  100  as long as the portion  136  is positioned to deliver polishing fluid  114  to the polishing surface  116 .  
         [0027]     The plurality of nozzles  132  is disposed along the portion  136  of the delivery arm  130  which is disposed above the platen  104 . In one embodiment, the nozzles  132  comprise at least a first nozzle  140  and a second nozzle  142 . Typically, the first nozzle  140  is positioned on the arm  130  radially inward of the second nozzle  142  relative to the center of rotation of the polishing material  108 . The distribution of polishing fluid  114  across the polishing material  108  may be controlled to flow polishing fluid  114  from the first nozzle  140  at a rate different than the flow from the second nozzle  142 .  
         [0028]     Nozzles  132  are configured to provide a controlled amount of fluid at an adjustable delivery angle and a controlled droplet size to the surface of the polishing material  108 . The nozzles  132  have apertures that may be adjusted to provide flow at a specific angle, for example between 0 and 90° normal to the substrate. The apertures may have a hole size of 50 microns or less. The apertures may also be adjusted to provide a specific droplet size, for example 15 microns. The improved control over the droplet size and angle of fluid delivery provides a more tailored slurry application to the polishing material  108 . This improved control facilitates a more uniform thickness, thinner film across the surface of the polishing material  108 . The film may have a thickness of 100 mils or less, preferably 50 mils or less. The film may have a thickness as thin as 1 micron or less. Because the film of polishing fluid is thinner and more controlled, less fluid than that required by conventional processes is needed to compensate for fluid losses such as fluid losses due to centrifugal forces across the surface of the polishing material. The nozzle position and flow rates of the first and second nozzles  140  and  142  may be selected to provide overlapping film streams, providing another slurry film tailoring mechanism.  
         [0029]     The flow rates exiting the first and second nozzles  140 ,  142  may vary from each other. The flow rates may be fixed relative to each other or be independently adjustable. In one embodiment, the fluid delivery arm  130  includes a polishing fluid supply line  124  that has a tee connection between the first and second nozzles  140 ,  142 . A tee fitting  126  is coupled to the supply line  124  and has a first delivery line  144  coupled to first nozzle  140  and a second delivery line  146  branching therefrom that is coupled to the second nozzle  142 .  
         [0030]     At least one of the nozzles  132  is controlled by a flow control mechanism  150 . The flow control mechanism  150  may be a device which provides a fixed ratio of flow between the nozzles  140 ,  142  or the flow control mechanism  150  may be adjustable to provide dynamic control of the flow rates. Examples of flow control mechanisms  150  include fixed orifices, pinch valves, proportional valves, restrictors, needle valves, restrictors, metering pumps, mass flow controllers and the like. Alternatively, the flow control mechanism  150  may be provided by a difference in the relative pressure drop between the fluid delivery lines  144 ,  146  coupling each nozzle  140 ,  142  and the tee fitting  126 .  
         [0031]     The polishing fluid source  134  is typically disposed externally to the system  100 . In one embodiment, the polishing fluid source  134  generally includes a reservoir  152  and a pump  154 . The pump  154  generally pumps the polishing fluid  114  from the reservoir  152  through the supply line  124  to the nozzles  132 .  
         [0032]     The polishing fluid  114  contained in the reservoir  152  is typically deionized water having chemical additives that provide chemical activity that assists in the removal of material from the surface of the substrate  112  being polished. As the polishing fluid  114  is supplied to the nozzles  132  from a single source such as the reservoir  152 , the fluid  114  flowing from the nozzles  132  is substantially homogeneous, not varied in concentration of chemical reagents or entrained abrasives. Optionally, the polishing fluid may include abrasives to assist in the mechanical removal of material from the surface of the substrate. The polishing fluids are generally available from a number of commercial sources such as Cabot Corporation of Aurora, Ill., Rodel Inc., of Newark, Del., Hitachi Chemical Company, of Japan, and Dupont Corporation of Wilmington, Del.  
         [0033]     In operation, the substrate  112  is positioned in polishing head  106  and brought in contact with the polishing material  108  supported by the rotating platen  104 . The polishing head  106  may hold the substrate stationary or may rotate or otherwise move the substrate to augment the relative motion between the polishing material  108  and substrate  112 . The polishing fluid delivery system  102  flows the polishing fluid  114  through the supply line  124  to the first and second polishing nozzles  140 ,  142 .  
         [0034]      FIG. 2  depicts a plan view of the system  100  illustrating the flow of polishing fluid  114  onto the portions  202  and  204  of the polishing material  108 . A first flow  206  of polishing fluid  114  flows out the first nozzle  140  and onto the first portion  202  at a first rate while a second flow  208  of polishing fluid  114  flows out the second nozzle  142  and onto the second portion  204  at a second rate. Generally, the first flow  206  is different than the second flow  208  thus providing a controlled distribution of polishing fluid  114  across the polishing surface  116  of the polishing material  108 . In one embodiment, the first flow  206  has a rate that is at least about 1.15 times a rate of the second flow  208 . The controlled distribution of the polishing fluid  114  across the polishing material  108  allows material removal from the surface of the substrate  112  to be tailored across the width of the substrate  112  by controlling the relative flows of polishing fluid  114  onto the polishing material  108 . More polishing fluid  114  may be provided to either the first portion  202  of the polishing material  108  or the second portion  204 . Optionally, additional nozzles may be utilized to provide different amounts of polishing fluid  114  on other portions of the polishing material  108  where at least two portions of the polishing material  108  have polishing fluid  114  disposed thereon at different flow rates.  
         [0035]     In one mode of operation, the substrate  112  being polished by the system  100  is processed with polishing fluid  114  provided from the first nozzle  140  and the second nozzle  142 . Polishing fluid  114  is disposed on the polishing material  108  from the first nozzle  140  at a first rate. Polishing fluid  114  is simultaneously disposed on the polishing material  108  from the second nozzle  142  at a second rate. In one embodiment, the first flow is about 1.2 to about 20 times the second flow rate.  
         [0036]     As depicted in  FIG. 2 , the first nozzle  140  generally provides polishing fluid  114  at a first rate to a first portion  202  of the polishing surface  116  while the second nozzle  142  provides polishing fluid  114  at a second rate to a second portion  204  of the polishing surface  116 . The portions  202  and  204  may overlap, especially when the apertures of nozzles  140 ,  142  are selected to target a specific region across polishing material  108 . The spray patterns  206 ,  208  are selected to provide variable slurry distribution across polishing material  108 , often to provide more slurry to the exterior or towards the diameter of the polishing material. For example, portion  204  may require more slurry than portion  202 . In this manner, the distribution of polishing fluid  114  across the width of the polishing material  108  is regulated.  
         [0037]     The control scheme prevents loss of slurry by creating uniform slurry overlap of portions  202  and  204  and encourages a polishing profile that is tailored to specific substrates based on repeated substrate measurements before and after polishing. Alternativley, adjusting the control scheme may occur substrate by substrate. Referring to  FIG. 1 , configurations having dynamic, adjustable control mechanisms  150  such as proportional valves, needle valves, mass flow controllers, metering pumps, peristaltic pumps and the like, the distribution of polishing fluid  114  on the polishing material  108  may be tailored during the process. For example, the rate of polishing fluid from the first nozzle  140  may be applied to the polishing material  108  at a first rate during one portion of the process and adjusted to a second rate during another portion of the process. The rate of polishing fluid  114  delivery from the second nozzle  142  may also be varied during the polishing process. The adjustments of polishing fluid flows from nozzles  140 ,  142  are infinite. The use of additional nozzles disposed between the first nozzle  140  and the second nozzle  142  allows the uniformity profile to be further modified and locally shaped by providing more or less polishing fluid  114  at a nozzle disposed between the first nozzle  140  and the second nozzle  142  (see discussion of  FIG. 3  below).  
         [0038]     Optionally, a polishing fluid delivery system having dynamic control over the flow rates from the nozzles  140 ,  142  may include a metrology device  118  to provide process feed-back for real-time adjustment of the polishing fluid distribution. Typically, the metrology device  118  detects a polishing metric such as time of polish, thickness of the surface film being polished on the substrate, surface topography, or other substrate attribute.  
         [0039]     In one embodiment, the polishing material  108  may include a window (not shown) that allows a metrology device  118  to view the surface of the substrate  112  disposed against the polishing material  108 . The metrology device  118  generally includes a sensor  162  that emits a beam  164  that passes through the window (not shown) to the substrate  112 . A first portion of the beam  164  is reflected by the surface of the substrate  108  while a second portion of the beam  164  is reflected by a layer of material underlying the polished surface of the substrate  112 . The reflected beams are received by the sensor  162  and a difference in wavelength between the two portions of reflected beams are resolved to determine the thickness of the material on the surface of the substrate  112 . Generally, the thickness information is provided to a controller (not shown) that adjusts the polishing fluid distribution on the polishing material  108  to produce a desired polishing result on the substrate&#39;s surface. One monitoring system that may be used to advantage is described in U.S. patent application Ser. No. 5,893,796, issued Apr. 13, 1999 by Birang, et al., and is hereby incorporated herein by reference in its entirety.  
         [0040]     Optionally, the metrology device  118  may include additional sensors to monitor polishing parameters across the width of the substrate  112 . The additional sensors allow for the distribution of polishing fluid  114  to be adjusted across the width of the substrate  112  so that more or less material is removed in one portion relative to another portion of the substrate  112 . Additionally, the process of adjusting the flow rates from the nozzles  140 ,  142  may occur iteratively over the course of a polishing sequence to dynamically control the rate of material removal across the substrate  112  at any time. For example, the center of the substrate  112  may be polished faster by providing more polishing fluid to the center of the substrate  112  at the beginning of a polishing sequence while the perimeter of the substrate  112  may be polished faster at the end of the polishing sequence by providing more polishing fluid to the perimeter area.  
         [0041]      FIG. 3  depicts another embodiment of a polishing fluid delivery system  300  having a plurality of nozzles  302 . Angles  320  and  322  illustrate the angles that may be adjusted to modify the resulting slurry film properties such as distribution profile or thickness. The system  300  may be configured similarly to the fluid delivery system  102  of  FIG. 1  (having a single polishing fluid delivery line) or may be configured so that each nozzle  302  has a dedicated supply line  304  coupled to a fluid source  306 . Fluidly coupled to each supply line  304  is a metering device  308 . The metering device  308  may be a metering pump such as a gear pump, a peristaltic pump, a positive displacement pump, a diaphragm pump and the like. Each metering device  308  is coupled to a controller (not shown) that controls the amount of polishing fluid  114  provided to each nozzle  302  of the system  300 . As each metering device  308  is independently controllable, the flow of polishing fluid  114  from each of the plurality of nozzles  302  is controlled independent from the other nozzles so that the distribution of polishing fluid  114  on the polishing material  108  can be arranged in practically infinite configurations.  
         [0042]     As described above, each metering device may vary the flow of polishing fluid delivered to the polishing material  108  over the course of polishing. For example, one of the nozzles  302  may increase the flow of polishing fluid  114  flowing therethrough while the substrate is being polished. Another one of the nozzles may decrease the flow of polishing fluid  114  during polishing. Of course, infinite variations in nozzle flow rates at any time may be configured to produce a desired polishing result. As the flow of polishing fluid is independently controllable through each nozzle  302 , polishing attributes may be tailored across the width of the substrate over the duration of substrate processing.  
         [0043]     The fluid delivery source  306  may be used in concert with a metrology device  312  to control the rate or location of material removal from a surface  318  of the substrate  112  being polished. Generally, the rate of removal or remaining thickness of material disposed on the surface  318  of the substrate  112  may be detected by the metrology device  312  and provided to the controller which, in turn, adjusts the various flow rates exiting each nozzle  302  to produce a desired polishing result, for example, faster polishing on the perimeter of the substrate  112 .  
         [0044]     In one embodiment, the polishing material  108  may include a window  310  that allows the metrology device  312  to view the surface  318  of the substrate  112  disposed against the polishing material  108 . The metrology device  312  generally includes a sensor  314  that emits a beam  316  that passes through the window  310  to the substrate  112 . A first portion of the beam  316  is reflected by the surface  318  of the substrate  108  while a second portion of the beam  316  is reflected by a layer of material underlying the polished surface  318  of the substrate  112 . The reflected beam is received by the sensor  314  and a difference in wavelength between the two portions of reflected beam is resolved to determine the thickness of the material on the surface  318  of the substrate  112 . Generally, the thickness information is provided to the controller that adjusts the polishing fluid distribution on the polishing material  108  to produce a desired polishing result on the substrate surface  318 .  
         [0045]     Optionally, the metrology device  312  may include additional sensors to monitor polishing parameters across the width of the substrate  112 . The additional sensors allow for the distribution of polishing fluid  114  to be adjusted across the width of the substrate  112  so that more or less material is removed in one portion relative to another portion of the substrate  112 . Additionally, the process of adjusting the flow rates from the nozzles  302  may occur iteratively over the course of a polishing sequence to dynamically control the rate of material removal across the substrate  112  at any time. For example, the center of the substrate  112  may be polished faster by providing more polishing fluid to the center of the substrate  112  at the beginning of a polishing sequence while the perimeter of the substrate  112  may be polished faster at the end of the polishing sequence by providing more polishing fluid to the perimeter area.  
         [0046]      FIG. 4  is an additional alternative embodiment of a slurry distribution system  400 . A delivery arm  401  is vertically positioned to support the nozzles  402 . That is, the delivery arm  401  is static and has less range of motion than the arm of embodiments of  FIGS. 1-3 . The polishing fluid  414  flows from the nozzles  402  at angles  410 ,  412  to the polishing material  408  that is supported by the platen  403 . Slurry is supplied to the nozzles  402  from the slurry reservoir  452  through the fluid supply line  424 . The fluid supply line  424  is pressurized by the pump  454 .  
         [0047]     Nozzles  132 ,  402  are configured to provide a controlled amount of fluid at an adjustable delivery angle and an adaptable droplet size to the surface of the polishing material  108 ,  408 . The nozzles  132 ,  402  have apertures that may be adjusted, for example, from 0 to 90° to provide flow at a specific angle  410 ,  412 . The apertures may also be adjusted to provide a specific droplet size, for example 15 Å. The improved control over the droplet size and angle of fluid delivery provides a more tailored slurry application to the polishing material  108 ,  408 . This improved control facilitates a more uniform thickness, thinner film across the surface of the polishing material  108 ,  408 . Because the film of polishing fluid is thinner and more controlled, less fluid than that required by conventional processes is needed to compensate for fluid losses due to centrifugal forces across the surface of the polishing material.  
         [0048]     While the foregoing is directed to embodiments 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.