Patent ID: 7610111

Claim:
A method to establish a wafer lot order of a semiconductor manufacturing line by controlling queue time of wafer lots, comprising the steps of (1) ranking lots of semiconductor wafers waiting at gate step of queue time control and ordering said ranked lots on a lot list; (2) allocating equipment to an exit step of queue time control and ranking said equipment according to priority on an equipment list; (3) selecting equipment having highest priority as current equipment; (4) selecting a lot having highest priority; (5) checking a resource and process constraint database if said equipment selected is qualified to run said lot selected and if resources required are available and select another equipment as current equipment from said equipment list if said check is negative; (6) calculating minimal batch size if the equipment of said exit step is a batch tool; (7) determining optimal allowable queue time of said lot selected based on utilization loss and rework percentage; (8) calculating the earliest release time for the equipment selected; and (9) releasing the lot selected and assigning it to the equipment selected if the current time is not later than the calculated earliest release time otherwise select the next lot on the lot list and go to step (5), if there are no more lots on the lot list go to exit.