Polishing apparatus and method for polishing semiconductor wafers using load-unload stations

Abstract

A polishing apparatus and method for polishing semiconductor wafers uses multiple load-unload stations and at least one turn-over robotic wafer handing device to process the wafers so that the wafer can be polished at multiple polishing tables. The turn-over robotic wafer handing device operates to turn over the wafers so that one side of the wafers can be polished at a first polishing table and the other side of the wafers can then be polished at a second polishing table.

1 . A polishing apparatus comprising:
 first and second polishing units, each of the first and second polishing units being configured to polish one side of semiconductor wafers, each of the first and second polishing units comprising:
 a polishing table; and 
 a wafer carrier assembly configured to hold a semiconductor wafer and move the semiconductor wafer to and from the polishing table, the wafer carrier assembly being further configured to move the semiconductor wafer onto the polishing table; 
   first, second, third and fourth load-unload stations, each of the first, second, third and fourth load-unload stations being configured to accommodate one of the semiconductor wafers at a time, the first and second load-unload stations being situated such that the first polishing unit is positioned between the first and second load-unload stations, the third and fourth load-unload stations being situated such that the second polishing unit is positioned between the third and fourth load-unload stations; and   a turn-over robotic wafer handing device positioned between the second and third load-unload stations, the turn-over robotic wafer handing device being configured to transfer the semiconductor wafer from the second load-unload station to the third load-unload station, the turn-over robotic wafer handing device being further configured to turn over the semiconductor wafer when the semiconductor wafer is transferred from the second load-unload station to the third load-unload station.   
     
     
         2 . The apparatus of  claim 1  wherein the first, second, third and fourth load-unload stations are all arranged in a linear manner. 
     
     
         3 . The apparatus of  claim 1  wherein at least one of the first, second, third and fourth load-unload stations is configured to spray fluid onto a wafer carrier of the wafer carrier assembly or the semiconductor wafer when the wafer carrier or the semiconductor wafer is positioned at that load-unload station. 
     
     
         4 . The apparatus of  claim 1  further comprising a washing station positioned between the first and fourth load-unload stations, the washing station being configured to spray fluid onto a wafer carrier of the wafer carrier assembly when the wafer carrier is positioned over the washing station. 
     
     
         5 . The apparatus of  claim 4  wherein the washing station is positioned between the first load-unload station and the polishing table of the first polishing unit, between the polishing table of the first polishing unit and the second load-unload station, between the third load-unload station and the polishing table of the second polishing unit, or between the polishing table of the second polishing unit and the fourth load-unload station. 
     
     
         6 . The apparatus of  claim 1  wherein the wafer carrier assembly of the first polishing unit is configured to be moved between the first load-unload station, the polishing table of the first polishing unit and the second load-unload station, and wherein the wafer carrier assembly of the second polishing unit is configured to be moved between the third load-unload station, the polishing table of the second polishing unit and the fourth load-unload station. 
     
     
         7 . The apparatus of  claim 1  wherein the wafer carrier assembly of the first polishing unit is configured to be moved between the first load-unload station, the polishing table of the first polishing unit and the third load-unload station, and wherein the wafer carrier assembly of the second polishing unit is configured to be moved between the third load-unload station, the polishing table of the second polishing unit and the fourth load-unload station. 
     
     
         8 . The apparatus of  claim 1  wherein the wafer carrier assembly of the first polishing unit is configured to be moved between the first load-unload station, the polishing table of the first polishing unit and the second load-unload station, and wherein the wafer carrier assembly of the second polishing unit is configured to be moved between the second load-unload station, the polishing table of the second polishing unit and the fourth load-unload station. 
     
     
         9 . The apparatus of  claim 1  further comprising:
 another first, second, third and fourth load-unload stations, the another first and second load-unload stations being situated such that the first polishing unit is positioned between the another first and second load-unload stations, the another third and fourth load-unload stations being situated such that the second polishing unit is positioned between the another third and fourth load-unload stations,   wherein each of the first and second polishing units further comprises another wafer carrier assembly configured to hold another semiconductor wafer and move the another semiconductor wafer to and from the polishing table, the wafer carrier assembly being further configured to polish the another semiconductor wafer on the polishing table.   
     
     
         10 . The apparatus of  claim 9  wherein the another first, second, third and fourth load-unload stations are all arranged in a linear manner. 
     
     
         11 . The apparatus of  claim 9  wherein the turn-over robotic wafer handing device is further configured to transfer the another semiconductor wafer from the another second load-unload station to the another third load-unload station. 
     
     
         12 . The apparatus of  claim 9  further comprising another turn-over robotic wafer handing device positioned between the another second load-unload station and the another third load-unload station, the another turn-over robotic wafer handing device being configured to transfer the another semiconductor wafer from the another second load-unload station to the another third load-unload station. 
     
     
         13 . A method for polishing semiconductor wafers, the method comprising:
 moving a semiconductor wafer between a first load-unload station, a first polishing table and a second load-unload station on a first wafer carrier assembly, including polishing a first side of the semiconductor wafer on the first polishing table using the first wafer carrier assembly;   moving the semiconductor wafer between a third load-unload station, a second polishing table and a fourth load-unload station on a second wafer carrier assembly, including polishing a second side of the semiconductor wafer on the second polishing table using the second wafer carrier assembly; and   transferring the semiconductor wafer from the second load-unload station to the third load-unload station using a turn-over robotic wafer handing device, including turning over the semiconductor wafer when the semiconductor wafer is transferred from the second load-unload station to the third load-unload station.   
     
     
         14 . The method of  claim 13  wherein the moving the semiconductor wafer between the first load-unload station, the first polishing table and the second load-unload station includes linearly moving the first wafer carrier assembly between the first load-unload station, the first polishing table and the second load-unload station of the first polishing unit. 
     
     
         15 . The method of  claim 13  further comprising:
 moving another semiconductor wafer between another first load-unload station, the first polishing table and another second load-unload station on another first wafer carrier assembly, including polishing a first side of the another semiconductor wafer on the first polishing pad using the another first wafer carrier assembly; and   moving the another semiconductor wafer between another third load-unload station, the second polishing table and another fourth load-unload station on another second wafer carrier assembly, including polishing a second side of the another semiconductor wafer on the second polishing table using the another second wafer carrier assembly.   
     
     
         16 . The method of  claim 15  wherein the moving the another semiconductor wafer between the another first load-unload station, the first polishing table and the another second load-unload station includes linearly moving the another first wafer carrier assembly between the another first load-unload station, the first polishing table and the another second load-unload station. 
     
     
         17 . The method of  claim 15  further comprising transferring the another semiconductor wafer from the another second load-unload station to the another third load-unload station using the turn-over robotic wafer handing device. 
     
     
         18 . The method of  claim 15  further comprising transferring the another semiconductor wafer from the another second load-unload station to the another third load-unload station using another turn-over robotic wafer handing device. 
     
     
         19 . The method of  claim 13  further comprising:
 transferring the semiconductor wafer from a wafer storage station to a buffer station;   transferring the semiconductor wafer from the buffer station to the first load-unload station;   transferring the semiconductor wafer from the fourth load-unload station to a wafer cleaner; and   transferring the semiconductor wafer from the wafer cleaner to the wafer storage station.