Robot pre-positioning in a wafer processing system

A method for positioning a robot in a wafer cluster tool, the wafer cluster tool including a first process module, a second process module, and a third process module, the method comprising:

• generating a deterministic schedule for the wafer cluster tool, the schedule having a periodicity defined by a sending period, wherein the schedule has a first pickup time for the first module in the cluster tool, and a second pickup time for the third module, the second pickup time occurring after the first pickup time, the deterministic schedule including a first instant and a second instant, wherein the first and second instants are separated by a time span equal to the sending period;
• loading a first wafer in the cluster tool at the first instant;
• picking up a second wafer from the first module with a robot, the picking up the second wafer occurring between the first and second instants;
• delivering the second wafer from the first module to the second module with the robot before the second instant;
• immediately after the delivering the second wafer, positioning the robot at the third module, the positioning the robot at the third model occurring before the second pickup time;
• and
• delivering the second wafer from the third module to a fourth module by use of the robot before the second instant;
• wherein the first module is coupled to a first local clock, the second module is coupled to a second local clock, the third module is coupled to a third local clock, and the fourth module is coupled to a fourth local clock.

A method of positioning robots in a wafer cluster tool, the wafer cluster comprising a plurality of process modules, the wafer cluster including a first robot and a second robot, wherein the wafer cluster tool operates according to a periodic schedule, the periodic schedule being defined by a sending period, the method comprising:

• a) transferring a first wafer from a first process module in the plurality of process modules to a second process module in the plurality of modules by use of the first robot;
• b) immediately after step a, positioning the first robot at a third process module
• c) transferring a second wafer from a third process module in the plurality of process modules to a fourth process module in the plurality of modules by use of the second robot;
• d) immediately after step c, positioning the second robot at a fifth process module;
• wherein steps a through d are conducted within a first time interval, the first time interval having a duration equal to the sending period.