Abstract:
A wafer carrier used for a chemical mechanical device has a polishing head and a pad conditioner. The polishing head has a retainer ring secured to a bottom of the polishing head to hold a wafer. The pad conditioner can be fixed on a surface of the retainer ring, attached to side surfaces of the retainer ring, or embedded in the retainer ring, such that the pad conditioner and the polishing head can be integrally formed.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of Taiwan application serial no. 90125046, filed Oct. 11, 2001. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a chemical mechanical polishing (CMP) device. More specifically, the present invention relates to a CMP device having a wafer carrier. 
     2. Description of the Related Art 
     A chemical mechanical polishing method is a technology that can provide global planarization by using a polishing tool and an appropriate reagent. 
     FIG. 1 is a schematic side view of a conventional chemical mechanical polishing (CMP) device. FIG. 2 is a schematic top view of a conventional CMP device. 
     With reference to FIGS. 1 and 2, the conventional CMP device includes a polishing table  100 , a wafer carrier  106 , a polishing pad  102 , a tube  110 , and a pad conditioner  108 . The wafer carrier  106  is used to hold a wafer  104  to be polished. The carrier  106  has a vacuum hole (not shown) for sucking the wafer  104  and has a retainer ring (not shown) for supporting the wafer  104 . The polishing pad  102  is arranged on the polishing table  100 . The tube  110  conveys a polishing slurry  110   a  to the polishing pad  102 . The pad conditioner  108  has a plurality of diamond grits to scrape against the surface of the polishing pad  102  so as to remove the polishing slurry remained in the polishing pad  102 . During the CMP process, the polishing table  100  and the wafer carrier  106  rotates in a predetermined direction and the wafer carrier  106  catches a back surface  104   a  of the wafer  104 , with the front surface  104   b  of the wafer  104  being pressed on the polishing pad  102 . The tube  110  continuously supplies the polishing slurry  110   a  to the polishing pad  102 , such that a chemical reaction between the front surface  104   b  of the wafer  104  and the reagent in the polishing slurry  110   a  occurs while the pad  102  contacts with protruding portions on the wafer. Meanwhile, the polishing pad  102  mechanically polishes the wafer  104  by using the abrasive grains in the polishing slurry  110   a  to remove the protruding portions on the wafer. After the chemical and mechanical polishing process repeats several times, a smooth surface can be obtained. 
     In general, the polishing pad has a plurality of pits thereon which help to convey the polishing slurry and to polish the wafer. The pits have an average depth of 1-2 microns. However, the depth of the pit decreases as the number of the polished wafer increases, which may degrade the polishing performance. Further, during polishing, the pit of the polishing pad can be filled by the abrasive grains in the polishing slurry or the polished-off substance from the wafer such that the polishing characteristics disappear. Therefore, a pad conditioner  108  is needed for removing the fillings of the pits so as to recover the polishing characteristics, such as uneven surface of the pad  102 . 
     However, the conventional CMP device has a discrete wafer carrier and a separate pad conditioner, which requires more space. Furthermore, it is difficult to maintain a conventional CMP device that has complicate configuration. 
     SUMMARY OF THE INVENTION 
     In one aspect of the present invention, a wafer carrier used for CMP consists of a wafer carrier and a pad conditioner, in which the space and the maintenance fee for the CMP device can be effectively reduced. 
     In order to achieve the above and other objects of the present invention, a wafer carrier having a polishing head and a pad conditioner is provided. The polishing head has a retainer ring at a bottom thereof to hold a wafer. The pad conditioner is fixed on one surface of the retainer ring. The pad conditioner can be in contact with one of the polishing pads of the chemical mechanical device. 
     Furthermore, a wafer carrier used for a chemical mechanical device comprising a polishing head and a pad conditioner is provided. The polishing head has a retainer ring at a bottom thereof to hold a wafer in the bottom of the polishing head. The pad conditioner is attached to side surfaces of the polishing head. One conditioning surface of the pad conditioner is roughly parallel to one surface of the retainer ring. The pad conditioner can be in contact with one of the polishing pads of the chemical mechanical device. 
     Also, a wafer carrier used for a chemical mechanical device comprising a polishing head and a pad conditioner is provided. The polishing head has a retainer ring at a bottom thereof to hold a wafer. The pad conditioner is embedded in the retainer ring. The pad conditioner can be in contact with one of the polishing pads of the chemical mechanical device. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed. 
     The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principle of the invention. In the drawings, 
     FIG. 1 is a schematic side view of a conventional chemical mechanical polishing (CMP) device; 
     FIG. 2 is a schematic top view of a conventional CMP device; 
     FIG. 3 is a schematic view of a wafer carrier of a CMP device according to a first preferred embodiment of the present invention; 
     FIG. 4 is a schematic view of a wafer carrier of a CMP device according to another first preferred embodiment of the present invention; 
     FIG. 5 is a schematic view of a wafer carrier of a CMP device according to a second preferred embodiment of the present invention; 
     FIG. 6 is a schematic view of a wafer carrier of a CMP device according to another second preferred embodiment of the present invention; 
     FIG. 7 is a schematic view of a wafer carrier of a CMP device according to a third preferred embodiment of the present invention; and 
     FIG. 8 is a schematic view of a wafer carrier of a CMP device according to another third preferred embodiment of the present invention; 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Reference will now be made in detail to the present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts. 
     First Embodiment 
     FIGS. 3 and 4 show a wafer carrier used for CMP according to a first preferred embodiment of the present invention. 
     With reference to FIG. 3, the wafer carrier  300  includes a polishing head  301  and a pad conditioner  308 . The polishing head  301  holds a wafer  302  in a retainer ring  307  at a bottom of the polishing head  301 . The pad conditioner  308  is fixed on one surface of the retainer ring  307 . The wafer carrier  300  further includes a resilient porous film (not shown) which presses the wafer  302  into the porous film in a wet state for supporting the wafer  302 . Alternatively, a wafer carrier  300  further includes a vacuum hole (not shown) to suck the wafer  302  while a nitrogen gas is charged, such that the polishing rates at the center and edge of the wafer can be fine tuned. Moreover, a floating retainer ring (not shown) can be used to transfer the stress at the edge of the wafer  302  thereto, while pneumatically contacting with the polishing pad. 
     In this embodiment, the pad conditioner  308  consists of a conditioning plate  304  and a plurality of grains  306 . The conditioning plate  304  is fixed on one surface of the retainer ring  307 . The conditioning plate  304  has such a thickness that the polishing of the wafer  302  is not adversely affected. The grains  306  are arranged in the conditioning plate  304 , each of which is partly exposed. The grains  306  can be formed of diamond or ceramic, for example. 
     As shown in FIG. 4, patterns or grains can be further provided on the bottom of the retainer ring  306 . In this case, the retainer ring  306  can be used instead the pad conditioner  308 . 
     The pad conditioner  308  or the retainer ring  307  having patterns or grains thereon comes into contact with the polishing pad to remove the substance in the pits and to recover the polishing characteristics while polishing the wafer. 
     Second Embodiment 
     FIGS. 5 and 6 show a CMP device having a wafer carrier according to a second embodiment of the present invention. 
     With reference to FIG. 5, a wafer carrier  400  includes a polishing head  401  and a pad conditioner  408 . A wafer  402  is hold in a retainer ring  407  at a bottom of the polishing head  401 . The pad conditioner  408  attaches to a side of the polishing head  401  and a conditioning surface  405  of the pad conditioner  408  is parallel to the retainer ring  407 . Preferably, the conditioning surface  405  of the pad conditioner  408  is at the same level as the surface  407  of the polishing head  401 . The wafer carrier  400  further includes a resilient porous film (not shown) which presses the wafer  402  into the porous film in a wet state for supporting the wafer  402 . Alternatively, a wafer carrier  400  further includes a vacuum hole (not shown) to suck the wafer  402  while a nitrogen gas is charged, such that the polishing rates at the center and edge of the wafer can be fine tuned. Moreover, a floating retainer ring (not shown) can be used to transfer the stress at the edge of the wafer  402  thereto, while pneumatically contacting with the polishing pad. 
     In this embodiment, the pad conditioner  408  consists of a lug  404  and a plurality of grains  406 . The lug  404  attaches to the side of the polishing head  401 . The grains  406  are arranged in the lug  404 , each of which is partly exposed. The grains  406  can be formed of diamond or ceramic, for example. 
     As shown in FIG. 6, patterns or grains can be further provided on the bottom of the retainer ring  407 . In this case, the retainer ring  407  can provide the same function as the pad conditioner  408  during operation. 
     The pad conditioner  408  or the retainer ring  407  having patterns or grains thereon comes into contact with the polishing pad to remove the substance in the pits and to recover the polishing characteristics while polishing the wafer. 
     Third Embodiment 
     FIGS. 7 and 8 show a CMP device according to a third preferred embodiment of the present embodiment. 
     With reference to FIG. 7, the wafer carrier  500  includes a polishing head  501  and a pad conditioner  508 . A wafer  502  is hold in the retainer ring  507  at a bottom of the polishing head  501 . The wafer carrier  500  further includes a resilient porous film (not shown) which presses the wafer  502  into the porous film in a wet state for supporting the wafer  502 . Alternatively, a wafer carrier  500  further includes a vacuum hole (not shown) to suck the wafer  502  while a nitrogen gas is charged, such that the polishing rates at the center and edge of the wafer can be fine tuned. Moreover, a floating retainer ring (not shown) can be used to transfer the stress at the edge of the wafer  502  thereto, while pneumatically contacting with the polishing pad. 
     In this embodiment, the pad conditioner  508  consists of a lug  504  and a plurality of grains  506 . The lug  504  is embedded in one surface of the retainer ring  507 . The grains  506  are arranged in the lug  504 , each of which is partly exposed. The grains  506  can be formed of diamond or ceramic, for example. 
     As shown in FIG. 8, patterns or grains can be further provided on the bottom of the retainer ring  507 . In this case, the retainer ring  507  can provide the same function as the pad conditioner  508  during operation. 
     The pad conditioner  508  or the retainer ring  507  having patterns or grains thereon comes into contact with the polishing pad to remove the substance filled in the pits and to recover the polishing characteristics while polishing the wafer. 
     In the present invention, the pad conditioner can be fixed on the surface of the retainer ring at the bottom of the polishing head, on the side of the polishing head, or embedded in the surface of the retainer ring. The polishing head and the pad conditioner can be thus combined. 
     With a combination of the wafer carrier and the pad conditioner, the space for the CMP device can be effectively utilized. Therefore, the maintenance fee can be reduced. Furthermore, the polishing pad can preserve the polishing characteristics while the wafer carrier is polished. 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.