Abstract:
A method and apparatus is provided that comprises an improved substrate polishing pad conditioning plate. In one embodiment, the conditioning plate contains multiple channels interposed between the abrasive surfaces so as to manage slurry and debris to resist clogging the abrasive surface of the conditioning plate so as to enable conditioning of the polishing pad.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to an apparatus and method of using a substrate polishing pad conditioning apparatus and, more particularly, to a conditioning plate that has recessed portions for managing polishing agents and unwanted debris.  
         BACKGROUND OF INVENTION  
         [0002]    During the microelectronic device fabrication process, multiple integrated circuits are formed upon the surface of substrate. Examples of substrates include, but are not limited to silicon wafers, gallium arsenide wafers and the like. Each integrated circuit consists of micro electronic devices electrically interconnected with conductive traces known as interconnects. Interconnects are patterned from conductive layers formed on the surface of the substrate. The ability to form stacked layers of interconnects has allowed for more complex micro circuits to be implemented in and on relatively small surface areas of the substrate. With the number of micro circuits increasing and becoming more complex, the number of layers of a substrate are increasing. Accordingly, planarity of the substrate surface becomes a critical dimension, and is now found to be important to maximizing circuit performance.  
           [0003]    Chemical mechanical polishing (CMP) is a known method of planarizing the surface of a layer of a substrate. CMP combines chemical etching and mechanical abrasion to remove roughness on the surface of the substrate. FIG. 1 is an example of a top view of a known CMP process. During the CMP process, the substrate  10 , being attached to a head  12 , is inverted such that the integrated circuit-embodied surface opposably faces a polishing pad  14 . Polishing pad  14  is saturated with a slurry containing abrasive particles and a mild chemical etchant that softens or catalyzes the exposed surface being planarized. The polishing pad  14  is fixedly attached to a turntable or platen (not shown). The substrate  10  is polished by placing the substrate  10  into contact with the polishing pad  14  while the polishing pad  14  is rotated on the platen. The surface roughness of the integrated circuit-embedded embedded surface of the substrate  10  is removed by the combined action of chemical softening of the exposed surface material and physical abrasion brought about by relative movement between the polishing pad  14 , the slurry and the substrate  10 .  
           [0004]    As portions of the substrate  10  are removed by the polishing pad  14 , a combination of slurry and debris tends to clog the surface of the polishing pad  14 , such that over time, the polishing pad  14  becomes less effective. The surface of polishing pad  14  is cleaned by conditioning disc  16 , which has an abrasive surface that engages the polishing pad surface. Known conditioning discs are typically made of stainless steel and have an abrasive surface, such as coatings like diamond grit or with surface marks. The abrasive surface of conditioning disc  16 , however, tends to clog with slurry and debris, thereby rendering less and less effective over time. The spent conditioning discs are removed from the CMP machine and either treated to refresh the conditioning surface or discarded. This process is time consuming, expensive and complicates achieving accurate planarity due to uneven declining effectiveness over the life of the conditioning disc.  
           [0005]    Accordingly, new configurations and methods are needed for providing a conditioning disc that will resist clogging, and which provides for minimal downtime and replacement, thereby reducing manufacturing costs. 
       
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0006]    [0006]FIG. 1 is a top view of a CMP process machine;  
         [0007]    [0007]FIG. 2 is a perspective view of a conditioning apparatus in accordance with an embodiment of the invention;  
         [0008]    [0008]FIG. 3 is a side view of a CMP process machine using a conditioning apparatus in accordance with an embodiment of the invention;  
         [0009]    [0009]FIG. 4 is a top view of another embodiment of the conditioning apparatus in accordance with the invention; and  
         [0010]    [0010]FIG. 5 is a top view of another embodiment of the conditioning apparatus in accordance with the invention.  
     
    
     DESCRIPTION  
       [0011]    In the following detailed description, reference is made to the accompanying drawings which form a part hereof wherein like numerals designate like parts throughout, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. Therefore, the following detailed description is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims and their equivalents.  
         [0012]    [0012]FIG. 2 is a perspective view of an embodiment in accordance with the present invention, showing a conditioning plate  17  comprising a plurality of recessed portions or channels  18  that define a plurality of adjacent conditioning surfaces  20 . Though shown as circular in the illustrated embodiment, conditioning plate  17  can be oblong, polygonal or similarly shaped. The conditioning plate  17  revolves in the process of conditioning the polishing pad (shown as  19  in FIG. 3) by managing the slurry and debris accumulating thereon. Debris and slurry are transition from the conditioning surfaces  20  into the channels  18 . Channels  18  then can move debris and slurry toward the perimeter  23  or toward the center  22 , depending on the rotation of the conditioning plate  17 . Conditioning surfaces  20  are thereby continuously cleared of slurry and debris, thus prolonging the effectiveness of the conditioning surfaces  20 .  
         [0013]    The conditioning surfaces  20  and the channels  18  can taper from the perimeter of the conditioning plate  17  toward the center  22  and may be generally swept back in a counter rotational direction. Each conditioning surface  20  can have a generally convex leading edge  24  and concave trailing edge  26 . The conditioning plate  17  can be rotated as indicated by rotational arrow  28 , such that the slurry and debris within the channels  18  is urged toward the perimeter  23  of the conditioning plate  17 , moving the material away from the conditioning surface  20  of the conditioning plate  17  and from the polishing surface of the polishing pad (shown as  19  in FIG. 3). Conditioning plates can be made of stainless steel, or any other metal allow or composite material, including but not limited to plastic, carbon bases, or fiber reinforced. The Conditioning surfaces can be abrasive through coatings, like diamond grit, or with surface marks.  
         [0014]    The leading edge  24  and trailing edge  26  can be curved in varying degrees, as well as being straight, depending on predetermined factors such as the rotational speed of the conditioning plate  17  and the polishing pad  14  (shown as  19  in FIG. 3), slurry viscosity, and the expected amount of debris removal. Finally, the leading edge and trailing edge, though shown to be substantially vertical, may be tapered to allow material to gradually transition from the conditioning surface  20  to channel  18 .  
         [0015]    The rotation of conditioning plate  17  can be reversed, opposite of that shown by rotational arrow  28 . Reverse rotation of the conditioning plate  17  urges the slurry toward the center  22  of conditioning plate  17 . Such a rotation may be advantageous for low viscosity slurries used for certain polishing applications. In the reverse direction, the channels  18  tend to retain the slurry and debris on the conditioning surface  20  of the conditioning plate  17 .  
         [0016]    [0016]FIG. 3 is a side view of a CMP process machine with the conditioning plate  17 . Substrate  10 , secured to head  12 , opposably faces polishing pad  19  secured to rotatable platen  21 . Conditioning plate  17 , secured to head  15  and linkage  33 , opposably faces polishing pad  19 . Depending on the configuration of channels  18 , conditioning plate can rotated in a direction that urges the slurry and debris toward perimeter  23 , or in the opposite direction to urge the slurry and debris toward the center  22 . The conditioning surfaces  20  keep the surface of polishing pad  19  from slurry and debris buildup. Linkage  33  can also move head  15  and conditioning disk  17  in a linear direction to condition the entire surface of the polishing pad  19 .  
         [0017]    [0017]FIG. 4 is a top view of another embodiment of the conditioning plate  31  in accordance with the present invention. The ratio between the width of the channels  25  and the width of the conditioning surfaces  27  is considerably smaller than that shown in FIG. 2. The conditioning plate  31  comprises channels  25 , the width and depth of which are determined for a particular purpose that depend on a number of factors, including, but not limited to, the slurry consistency and viscosity, the size and amount of debris to be removed from the substrate and the rotational speed of both conditioning plate  19  and the polishing pad  19  (shown in FIG. 3).  
         [0018]    [0018]FIG. 4 is a top view of a conditioning plate  32  in accordance with another embodiment of the present invention. The conditioning plate  21  comprises a center  22  that is part of the conditioning surface  29 , and the channels  30  do not traverse the entire diameter of the conditioning plate  32 .  
         [0019]    Although specific embodiments have been illustrated and described herein for purposes of description of the preferred embodiment, it will be appreciated by those of ordinary skill in the art that a wide variety of alternate and/or equivalent implementations calculated to achieve the same purposes may be substituted for the specific embodiments shown and described without departing from the scope of the present invention. Those with skill in the art will readily appreciate that the present invention may be implemented in a very wide variety of embodiments. This application is intended to cover any adaptations or variations of the embodiments discussed herein. Therefore, it is manifestly intended that this invention be limited only by the claims and the equivalents thereof.