Apparatus and method for polishing semiconductor wafers

Abstract

An apparatus and method for polishing semiconductor wafers uses multiple polishing surfaces, multiple polishing heads and multiple wafer stations to sequentially polish the semiconductor wafers. The wafer stations includes at least one wafer load-unload station to transfer the semiconductor wafers between the wafer load-unload station and the polishing heads.

1 . An apparatus for polishing semiconductor wafers, said apparatus comprising:
 first, second and third polishing surfaces positioned around a rotational axis;   first, second and third wafer stations positioned around said rotational axis between said first, second and third polishing surfaces such that each of said first, second and third wafer stations is positioned between adjacent polishing surfaces of said first, second and third polishing surfaces, said first wafer station being a wafer load-unload station configured to receive a semiconductor wafer so that said semiconductor wafer is unloaded onto said first wafer station before being transferred from said first wafer station; and   a rotation assembly including first, second and third polishing heads, said rotation assembly being configured to rotationally move each of said first, second and third polishing heads about said rotational axis between at least some of said first, second and third polishing surfaces and said first, second and third wafer stations,   wherein the number of polishing heads, the number of polishing surfaces and the number of wafer stations included in said apparatus are the same.   
     
     
         2 . The apparatus of  claim 1  wherein said first, second and third wafer stations are positioned around said rotational axis such that said first, second and third wafer stations are equally spaced to each other around said rotational axis. 
     
     
         3 . The apparatus of  claim 1  wherein said first, second and third polishing surfaces are positioned around said rotational axis such that said first, second and third polishing surfaces are equally spaced to each other around said rotational axis. 
     
     
         4 . The apparatus of  claim 1  wherein said second and third wafer stations are wafer load-unload stations configured to load and unload said semiconductor wafers to and from at least one of said first, second and third polishing heads. 
     
     
         5 . The apparatus of  claim 4  wherein said rotation assembly is configured to rotate said first, second and third polishing heads back and forth around said rotational axis such that said first polishing head is rotated exclusively among said first wafer station, said first polishing surface and said second wafer station, said second polishing head is rotated exclusively among said second wafer station, said second polishing surface and said third wafer station, and said third polishing head is rotated exclusively among said third wafer station, said third polishing surface and said first wafer station. 
     
     
         6 . The apparatus of  claim 1  wherein each of said second and third wafer stations is a wafer washing station configured to spray fluid onto a particular polishing head of said first, second and third polishing heads to wash said particular polishing head and one of said semiconductor wafers being held by said particular polishing head. 
     
     
         7 . The apparatus of  claim 1  wherein said first, second and third polishing heads are coupled to a rotational shaft such that said first, second and third polishing heads are rotationally moved in unison when said rotational shaft is rotated. 
     
     
         8 . The apparatus of  claim 7  wherein each of said first, second and third polishing heads is connected to a respective pivoting mechanism that is connected to said rotational shaft so that each of said first, second and third polishing heads can be pivoted about a respective pivoting axis that is rotated by said rotational shaft about said rotational axis. 
     
     
         9 . The apparatus of  claim 7  wherein said rotation assembly further includes first, second and third washing arms with spray nozzles to spray fluid onto said first, second and third polishing surfaces when said washing arms are rotated over said first, second and third polishing surfaces. 
     
     
         10 . The apparatus of  claim 9  wherein said first, second and third washing arms are attached to said rotational shaft such that said first, second and third washing arms are rotated in unison with said first, second and third polishing heads when said rotational shaft is rotated. 
     
     
         11 . The apparatus of  claim 1  further comprising a pivoting wafer transfer device with a wafer load-unload cup, said pivoting wafer transfer device being positioned near said first wafer station such that said wafer load-unload cup can be pivoted to be positioned over said first wafer station to transfer said semiconductor wafers between at least one of said first, second and third polishing heads and said wafer load-unload cup. 
     
     
         12 . An apparatus for polishing semiconductor wafers, said apparatus comprising:
 first, second and third polishing surfaces positioned around a rotational axis; and   first, second, third and fourth wafer load-unload stations positioned around said rotational axis between said first, second and third polishing surfaces such that said second wafer load-unload station is positioned between said first and second polishing surfaces, said third wafer load-unload station is positioned between said second and third polishing surfaces, and said first and fourth wafer load-unload stations are positioned between said first and third polishing surfaces; and   a rotation assembly including first, second and third polishing heads, said rotation assembly being configured to rotationally move each of said first, second and third polishing heads about said rotational axis between at least some of said first, second and third polishing surfaces and said first, second, third and fourth wafer load-unload stations.   
     
     
         13 . The apparatus of  claim 12  wherein said rotation assembly is configured to rotate said first, second and third polishing heads back and forth around said rotational axis such that said first polishing head is rotated exclusively among said first wafer load-unload station, said first polishing surface and said second wafer load-unload station, said second polishing head is rotated exclusively among said second wafer load-unload station, said second polishing surface and said third wafer load-unload station, and said third polishing head is rotated exclusively among said third wafer load-unload station, said third polishing surface and said fourth wafer load-unload station. 
     
     
         14 . An apparatus for polishing semiconductor wafers, said apparatus comprising:
 first and second polishing surfaces positioned around a rotational axis;   first and second wafer load-unload stations positioned around said rotational axis between said first and second polishing surfaces such that each of said first and second wafer stations is positioned between said first and second polishing surfaces, each of said first and second wafer load-unload stations being configured to receive a semiconductor wafer so that said semiconductor wafer is unloaded onto said first and second wafer load-unload stations before being transferred from said first and second load-unload stations; and   a rotation assembly including first and second polishing heads, said rotation assembly being configured to rotationally move each of said first and second polishing heads about said rotational axis between at least some of said first and second polishing surfaces and said first and second wafer load-unload stations,   wherein the number of polishing heads, the number of polishing surfaces and the number of wafer load-unload stations included in said apparatus are the same.   
     
     
         15 . The apparatus of  claim 14  wherein said first and second polishing surfaces are positioned around said rotational axis such that centers of said first and second polishing surfaces and rotational axis define a first straight line. 
     
     
         16 . The apparatus of  claim 15  wherein said first and second wafer load-unload stations are positioned around said rotational axis such that centers of said first and second wafer load-unload stations and said rotational axis define a second straight line. 
     
     
         17 . The apparatus of  claim 16  wherein said first and second polishing surfaces and said first and second load-unload wafer stations are arranged such that said first straight line is not perpendicular to said second straight line. 
     
     
         18 . The apparatus of  claim 14  wherein said rotation assembly is configured to rotate said first and second polishing heads back and forth around said rotational axis such that said first polishing head is rotated exclusively among said first wafer load-unload station, said first polishing surface and said second wafer load-unload station, and said second polishing head is rotated exclusively among said second wafer load-unload station, said second polishing surface and said first wafer load-unload station. 
     
     
         19 . The apparatus of  claim 14  wherein said first and second polishing heads are coupled to a rotational shaft such that said first and second polishing heads are rotationally moved in unison when said rotational shaft is rotated. 
     
     
         20 . The apparatus of  claim 19  wherein each of said first and second polishing heads is connected to a respective pivoting mechanism that is connected to said rotational shaft so that each of said first and second polishing heads can be pivoted about a respective pivoting axis that is rotated by said rotational shaft about said rotational axis. 
     
     
         21 . The apparatus of  claim 19  wherein said rotation assembly further includes first and second washing arms with spray nozzles to spray fluid onto said first and second polishing surfaces when said washing arms are rotated over said first and second polishing surfaces. 
     
     
         22 . The apparatus of  claim 21  wherein said first and second washing arms are attached to said rotational shaft such that said first and second washing arms are rotated in unison with said first and second polishing heads when said rotational shaft is rotated. 
     
     
         23 . The apparatus of  claim 14  further comprising a pivoting wafer transfer device with a wafer load-unload cup, said pivoting wafer transfer device being positioned near said first wafer load-unload station such that said wafer load-unload cup can be pivoted to be positioned over said first wafer load-unload station to transfer said semiconductor wafers between at least one of said first and second polishing heads and said wafer load-unload cup. 
     
     
         24 . An apparatus for polishing semiconductor wafers, said apparatus comprising:
 first and second polishing surfaces positioned around a rotational axis such that centers of said first and second polishing surfaces and said rotational axis define a first straight line;   first and second wafer stations positioned around said rotational axis between said first and second polishing surfaces such that each of said first and second wafer stations is positioned between said first and second polishing surfaces and centers of said first and second wafer stations and said rotational axis define a second straight line, said first and second wafer stations being arranged with respect to said first and second polishing surfaces such that said first straight line is not perpendicular to said second straight line; and   a rotation assembly including first and second polishing heads, said rotation assembly being configured to rotationally move each of said first and second polishing heads about said rotational axis between at least some of said first and second polishing surfaces and said first and second wafer stations,   wherein the number of polishing heads, the number of polishing surfaces and the number of wafer stations included in said apparatus are the same.   
     
     
         25 . The apparatus of  claim 24  wherein said second wafer station is a wafer load-unload station configured to load and unload said semiconductor wafers to and from at least one of said first and second polishing heads. 
     
     
         26 . The apparatus of  claim 24  wherein said rotation assembly is configured to rotate said first and second polishing heads back and forth around said rotational axis such that said first polishing head is rotated exclusively among said first wafer station, said first polishing surface and said second wafer station, and said second polishing head is rotated exclusively among said second wafer station, said second polishing surface and said first wafer station. 
     
     
         27 . The apparatus of  claim 24  wherein said second wafer station is a wafer washing station configured to spray fluid onto a particular polishing head of said first and second polishing heads to wash said particular polishing head and one of said semiconductor wafers being held by said particular polishing head. 
     
     
         28 . The apparatus of  claim 24  wherein said first and second polishing heads are coupled to a rotational shaft such that said first and second polishing heads are rotationally moved in unison when said rotational shaft is rotated. 
     
     
         29 . The apparatus of  claim 28  wherein each of said first and second polishing heads is connected to a respective pivoting mechanism that is connected to said rotational shaft so that each of said first and second polishing heads can be pivoted about a respective pivoting axis that is rotated by said rotational shaft about said rotational axis. 
     
     
         30 . The apparatus of  claim 28  wherein said rotation assembly further includes first and second washing arms with spray nozzles to spray fluid onto said first and second polishing surfaces when said washing arms are rotated over said first and second polishing surfaces. 
     
     
         31 . The apparatus of  claim 30  wherein said first and second washing arms are attached to said rotational shaft such that said first and second washing arms are rotated in unison with said first and second polishing heads when said rotational shaft is rotated. 
     
     
         32 . The apparatus of  claim 24  further comprising a pivoting wafer transfer device with a wafer load-unload cup, said pivoting wafer transfer device being positioned near said first wafer station such that said wafer load-unload cup can be pivoted to be positioned over said first wafer station to transfer said semiconductor wafers between at least one of said first and second polishing heads and said wafer load-unload cup. 
     
     
         33 . An apparatus for polishing semiconductor wafers, said apparatus comprising:
 first and second polishing surfaces positioned around a rotational axis;   first, second and third wafer load-unload stations positioned around said rotational axis between said first and second polishing surfaces such that said first and third load-unload stations are positioned between said first and second polishing surfaces and said second load-unload station is positioned between said first and second polishing surfaces; and   a rotation assembly including first and second polishing heads, said rotation assembly being configured to rotationally move each of said first and second polishing heads about said rotational axis between at least some of said first and second polishing surfaces and said first, second and third wafer load-unload stations.   
     
     
         34 . The apparatus of  claim 33  wherein said rotation assembly is configured to rotate said first and second polishing heads back and forth around said rotational axis such that said first polishing head is rotated exclusively among said first wafer load-unload station, said first polishing surface and said second wafer load-unload station, and said second polishing head is rotated exclusively among said second wafer load-unload station, said second polishing surface and said third wafer load-unload station. 
     
     
         35 . A system for polishing semiconductor wafers, said system comprising:
 first and second polishing apparatuses, each of said first and second polishing apparatuses comprising:
 first, second and third polishing surfaces positioned around said rotational axis; and 
 first, second and third wafer stations positioned around said rotational axis between said first, second and third polishing surfaces such that each of said first, second and third wafer stations is positioned between adjacent polishing surfaces of said first, second and third polishing surfaces, said first wafer station being a wafer load-unload station configured to receive a semiconductor wafer so that said semiconductor wafer is unloaded onto said first wafer station before being transferred from said first wafer station; and 
 a rotation assembly including first, second and third polishing heads, said rotation assembly being configured to rotationally move each of said first, second and third polishing heads about said rotational axis between at least some of said first, second and third polishing surfaces and said first, second and third wafer stations; 
   a wafer transfer device positioned adjacent to said first and second polishing apparatuses to access said first wafer station of each of said first and second polishing apparatuses; and   a post-CMP cleaner positioned adjacent to said wafer transfer device such that said wafer transfer device is positioned between said post-CMP cleaner and said first and second polishing apparatuses, said post-CMP cleaner being configured to clean said semiconductor wafers that have been polished in one of said first and second polishing apparatuses and transferred to said post-CMP cleaner by said wafer transfer device.   
     
     
         36 . A system for polishing semiconductor wafers, said system comprising:
 first and second polishing apparatuses, each of said first and second polishing apparatuses comprising:
 first, second and third polishing surfaces positioned around said rotational axis; 
 first, second and third wafer stations positioned around said rotational axis between said first, second and third polishing surfaces such that each of said first, second and third wafer stations is positioned between adjacent polishing surfaces of said first, second and third polishing surfaces, said first wafer station being a wafer load-unload station configured to receive a semiconductor wafer so that said semiconductor wafer is unloaded onto said first wafer station before being transferred from said first wafer station; 
 a rotation assembly including first, second and third polishing heads, said rotation assembly being configured to rotationally move each of said first, second and third polishing heads about said rotational axis between at least some of said first, second and third polishing surfaces and said first, second and third wafer stations; and 
   a wafer transfer device positioned adjacent to said first and second polishing apparatuses to access said first wafer station of each of said first and second polishing apparatuses,   wherein said first and second polishing apparatuses are orientated such that said first wafer station and said first and third polishing surfaces of each of said first and second polishing apparatuses are closer to said wafer transfer device than said second wafer and third wafer stations and said second polishing surface.   
     
     
         37 . The system of  claim 36  wherein said first and third polishing surfaces of said first and second polishing apparatuses are linearly arranged. 
     
     
         38 . A method for polishing semiconductor wafers, said method comprising:
 transferring a semiconductor wafer between a first wafer station of a polishing apparatus and one of first, second and third polishing heads of a rotation assembly of said polishing apparatus, said first wafer station being a wafer load-unload station;   sequentially polishing said semiconductor wafer on first, second and third polishing surfaces of said polishing apparatus using at least one of said first, second and third polishing heads of said rotation assembly; and   sequentially transferring said semiconductor wafer to second and third wafer stations of said polishing apparatus using at least one of said first, second and third polishing heads of said rotation assembly, each of said first, second and third wafer stations being positioned between adjacent polishing surfaces of said first, second and third polishing surfaces.   
     
     
         39 . The method of  claim 38  further comprising:
 unloading said semiconductor wafer onto said second wafer station from a particular polishing head of said first, second and third polishing heads when said particular polishing head is positioned over said second wafer station; and   loading said semiconductor wafer onto a different polishing head of said first, second and third polishing heads from said second wafer station when said different polishing head is positioned over said second wafer station.   
     
     
         40 . The method of  claim 38  further comprising spraying fluid from said second wafer station onto said semiconductor wafer when said semiconductor wafer is positioned at said second wafer station. 
     
     
         41 . The method of  claim 38  wherein said sequentially transferring includes rotationally moving said first, second and third polishing heads in unison about a rotational axis by rotating a rotational shaft to which said first, second and third polishing heads are coupled. 
     
     
         42 . The method of  claim 41  further comprising independently pivoting said first, second and third polishing heads about pivoting axes, each of said pivoting axes being located between one of said first, second and third polishing heads and said rotational axis. 
     
     
         43 . The method of  claim 38  further comprising spraying fluid onto said first, second and third polishing surfaces from first, second and third washing arms of said rotation assembly when said washing arms are rotated over said first, second and third polishing surfaces. 
     
     
         44 . The method of  claim 38  further comprising:
 receiving said semiconductor wafer at a wafer load-unload cup of a pivoting wafer transfer device of said polishing apparatus;   pivoting said wafer load-unload cup over said first wafer station; and   loading said semiconductor wafer onto one of said first, second and third polishing heads from said wafer load-unload cup.   
     
     
         45 . The method of  claim 38  further comprising:
 unloading said semiconductor wafer onto a wafer load-unload cup of a pivoting wafer transfer device of said polishing apparatus from one of said first, second and third polishing heads, said wafer load-unload cup being positioned over said first wafer station; and   pivoting said wafer load-unload cup away from said first wafer station for removal.   
     
     
         46 . The method of  claim 38  further comprising transferring said semiconductor wafer to a fourth wafer station of said polishing apparatus using said third polishing head of said rotation assembly after said semiconductor wafer is polished on said third polishing surface, including unloading said semiconductor wafer onto said fourth wafer station of said polishing apparatus from said third polishing head for removal, said fourth wafer station being positioned between said first wafer station and said third polishing surface. 
     
     
         47 . A method for polishing semiconductor wafers, said method comprising:
 transferring a semiconductor wafer between a first wafer load-unload station of a polishing apparatus and one of first and second polishing heads of a rotation assembly of said polishing apparatus;   sequentially polishing said semiconductor wafer on first and second polishing surfaces of said polishing apparatus using at least one of said first and second polishing heads of said rotation assembly; and   transferring said semiconductor wafer to a second wafer load-unload station of said polishing apparatus using at least one of said first and second polishing heads of said rotation assembly after said semiconductor wafer is polished on said first polishing surface, including unloading said semiconductor wafer onto said second wafer load-unload station, each of said first and second wafer load-unload stations being positioned between said first and second polishing surfaces.   
     
     
         48 . The method of  claim 47  wherein said transferring said semiconductor wafer to said second wafer load-unload station includes rotationally moving said first and second polishing heads in unison about a rotational axis by rotating a rotational shaft to which said first and second polishing heads are coupled. 
     
     
         49 . The method of  claim 48  further comprising independently pivoting said first, and second polishing heads about pivoting axes, each of said pivoting axes being located between one of said first and second polishing heads and said rotational axis. 
     
     
         50 . The method of  claim 47  further comprising spraying fluid onto said first and second polishing surfaces from first and second washing arms of said rotation assembly when said washing arms are rotated over said first and second polishing surfaces. 
     
     
         51 . The method of  claim 47  further comprising:
 receiving said semiconductor wafer at a wafer load-unload cup of a pivoting wafer transfer device of said polishing apparatus;   pivoting said wafer load-unload cup over said first wafer load-unload station; and   loading said semiconductor wafer onto one of said first and second polishing heads from said wafer load-unload cup.   
     
     
         52 . The method of  claim 47  further comprising:
 unloading said semiconductor wafer onto a wafer load-unload cup of a pivoting wafer transfer device of said polishing apparatus from one of said first and second polishing heads, said wafer load-unload cup being positioned over said first wafer load-unload station; and   pivoting said wafer load-unload cup away from said first wafer load-unload station for removal.   
     
     
         53 . The method of  claim 47  further comprising transferring said semiconductor wafer to a third wafer load-unload station of said polishing apparatus using said second polishing head of said rotation assembly after said semiconductor wafer is polished on said second polishing surface, including unloading said semiconductor wafer onto said third wafer unload-load station from said second polishing head for removal, said third wafer load-unload station being positioned between said first wafer load-unload station and said second polishing surface. 
     
     
         54 . A method for polishing semiconductor wafers, said method comprising:
 transferring a semiconductor wafer between a first wafer station of a polishing apparatus and one of first and second polishing heads of a rotation assembly of said polishing apparatus, said first wafer station being a wafer load-unload station;   sequentially polishing said semiconductor wafer on first and second polishing surfaces of said polishing apparatus using at least one of said first and second polishing heads of said rotation assembly, said first and second polishing surfaces being positioned around a rotational axis such that centers of said first and second polishing surfaces and said rotational axis define a first straight line; and   transferring said semiconductor wafer to a second wafer station of said polishing apparatus using at least one of said first and second polishing heads of said rotation assembly after said semiconductor wafer is polished on said first polishing surface, said first and second wafer stations being positioned around said rotational axis between said first and second polishing surfaces such that each of said first and second wafer stations is positioned between said first and second polishing surfaces and centers of said first and second wafer stations and said rotational axis define a second straight line, said first and second wafer stations being arranged with respect to said first and second polishing surfaces such that said first straight line is not perpendicular to said second straight line.   
     
     
         55 . The method of  claim 54  further comprising:
 unloading said semiconductor wafer onto said second wafer station from said first polishing head; and   loading said semiconductor wafer onto said second polishing head from said second wafer station.   
     
     
         56 . The method of  claim 54  further comprising spraying fluid from said second wafer station onto said semiconductor wafer when said semiconductor wafer is positioned at said second wafer station. 
     
     
         57 . The method of  claim 54  wherein said transferring said semiconductor wafer to said second wafer station includes rotationally moving said first and second polishing heads in unison about said rotational axis by rotating a rotational shaft to which said first and second polishing heads are coupled. 
     
     
         58 . The method of  claim 57  further comprising independently pivoting said first, and second polishing heads about pivoting axes, each of said pivoting axes being located between one of said first and second polishing heads and said rotational axis. 
     
     
         59 . The method of  claim 54  further comprising spraying fluid onto said first and second polishing surfaces from first and second washing arms of said rotation assembly when said washing arms are rotated over said first and second polishing surfaces. 
     
     
         60 . The method of  claim 54  further comprising:
 receiving said semiconductor wafer at a wafer load-unload cup of a pivoting wafer transfer device of said polishing apparatus;   pivoting said wafer load-unload cup over said first wafer station; and   loading said semiconductor wafer onto one of said first and second polishing heads from said wafer load-unload cup.   
     
     
         61 . The method of  claim 54  further comprising:
 unloading said semiconductor wafer onto a wafer load-unload cup of a pivoting wafer transfer device of said polishing apparatus from one of said first and second polishing heads, said wafer load-unload cup being positioned over said first wafer station; and   pivoting said wafer load-unload cup away from said first wafer station for removal.   
     
     
         62 . A method for polishing semiconductor wafers, said method comprising:
 transferring a semiconductor wafer to a first wafer station of a polishing apparatus using a wafer transfer device, said first wafer station being a wafer load-unload station;   sequentially transferring said semiconductor wafer to first, second and third polishing surfaces of said polishing apparatus using first, second and third polishing heads, respectively, of a rotation assembly of said polishing apparatus;   sequentially polishing said semiconductor wafer on said first, second and third polishing surfaces of said polishing apparatus using said first, second and third polishing heads, respectively, of said rotation assembly;   sequentially transferring said semiconductor wafer to second, third and fourth wafer stations of said polishing apparatus using said first, second and third polishing heads, respectively, of said rotation assembly, said first wafer station being positioned between said fourth wafer station and said first polishing surface, said second wafer station being positioned between said first and second polishing surfaces, said third wafer station being positioned between said second and third polishing surfaces, and said fourth wafer station being positioned between said third polishing surface and said first wafer station; and   removing said semiconductor wafer from said fourth wafer station of said polishing apparatus using said wafer transfer device, said fourth wafer station being another wafer load-unload station.   
     
     
         63 . The method of  claim 62  wherein said sequentially transferring said semiconductor wafer to said first, second and third polishing surfaces of said polishing apparatus includes rotationally moving said first, second and third polishing heads in unison about a rotational axis by rotating a rotational shaft to which said first, second and third polishing heads are coupled. 
     
     
         64 . A method for polishing semiconductor wafers, said method comprising:
 transferring a semiconductor wafer to a first wafer station of a polishing apparatus using a wafer transfer device, said first wafer station being a wafer load-unload station;   sequentially transferring said semiconductor wafer to first and second polishing surfaces of said polishing apparatus using first and second polishing heads, respectively, of a rotation assembly of said polishing apparatus;   sequentially polishing said semiconductor wafer on said first and second polishing surfaces of said polishing apparatus using said first and second polishing heads, respectively, of said rotation assembly;   sequentially transferring said semiconductor wafer to second and third wafer stations of said polishing apparatus using said first and second polishing heads, respectively, of said rotation assembly, said first wafer station being positioned between said third wafer station and said first polishing surface, said second wafer station being positioned between said first and second polishing surfaces, said third wafer station being positioned between said second polishing surface and said first wafer station; and   removing said semiconductor wafer from said third wafer station of said polishing apparatus using said wafer transfer device, said third wafer station being another wafer load-unload station.   
     
     
         65 . The method of  claim 64  wherein said sequentially transferring said semiconductor wafer to said first and second polishing surfaces of said polishing apparatus includes rotationally moving said first and second polishing heads in unison about a rotational axis by rotating a rotational shaft to which said first and second polishing heads are coupled.