Methods for transporting wafers for vacuum processing

Abstract

A workpiece handling system with dual load locks, a transport chamber and a process chamber. Workpieces may be retrieved from one load lock for processing at vacuum pressure, while workpieces are unloaded from the other load lock at the pressure of the surrounding environment. The transport chamber has a transport robot with two arms. Processed workpieces and new workpieces may be exchanged by a simple under/over motion of the two robot arms. The transport robot rotates about a central shaft to align with the load locks or the process chamber. The robot may also be raised or lowered to align the arms with the desired location to which workpieces are deposited or from which workpieces are retrieved. The two load locks may be positioned one above the other such that a simple vertical motion of the robot can be used to select between the two load locks. The two load locks and transport robot allow almost continuous processing. Additional process chambers may be added to the transport chamber to further increase throughput. Each stage of the workpiece handling system may also be designed to handle multiple workpieces, such as two side by side workpieces. Throughput is increased while allowing shared machinery to be used. Linear and rotational doors may be used for the load locks to provide a simple, compact design.

We claim:  
     
         1 . A method for processing semiconductor wafers comprising: 
 providing a first load lock and a second load lock above the first load lock;    providing a transport robot in a transport chamber;    providing a processing chamber adjacent to the transport chamber;    maintaining the transport chamber at a first pressure;    providing an external robot outside of the transport chamber in an environment having a second pressure;    adjusting the vertical position of the transport robot to select between the first load lock and the second load lock;    removing at least one semiconductor wafer from the load lock selected by the transport robot and using the transport robot to transfer the semiconductor wafer to the processing chamber; and    using the external robot to access the load lock that is not selected by the transport robot    
     
     
         2 . The method of  claim 1 , wherein the step of removing at least one semiconductor wafer from the load lock selected by the transport robot further comprises removing at least two semiconductor wafers at a time from the load lock selected by the transport robot.  
     
     
         3 . The method of  claim 1 , wherein the transport robot has a first arm and a second arm.  
     
     
         4 . The method of  claim 3 , wherein the step of removing at least one semiconductor wafer from the load lock selected by the transport robot further comprises using the first arm to remove the at least one semiconductor wafer.  
     
     
         5 . The method of  claim 4 , further comprising placing at least one semiconductor wafer in the load lock selected by the transport robot using the second arm.  
     
     
         6 . The method of  claim 3 , wherein the step of removing at least one semiconductor wafer from the load lock selected by the transport robot further comprises removing at least two semiconductor wafers at a time using the first arm of the transport robot.  
     
     
         7 . The method of  claim 6 , further comprising placing at least two semiconductor wafers at a time in the load lock selected by the transport robot using the second arm.