Method and system for wafer lot order
First Claim
1. 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.
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Abstract
Methods and systems for wafer lot ordering using including estimation of allowable queue time based on utilization loss and rework percentage have been achieved. The method invented comprises steps of ranking lots, allocating equipment to the exit step of queue time, calculating and determining the optimal allowable queue time based on utilization loss and rework percentage, calculating the next available time for equipment, calculating earliest release time, and releasing lot/batch and pre-assign it to the equipment at exit step. The present invention can be applied to other manufacturing lines than semiconductor manufacturing.
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Citations
26 Claims
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1. 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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A system to establish a wafer lot order of a semiconductor manufacturing line by controlling queue time of wafer lots, comprising:
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means to create a list of all production lots waiting at a gate step of queue time control, wherein said lots are ranked according their priority; means to create a list of all manufacturing equipments allocated to exit steps of queue time control, wherein said equipments are ranked according their priority; means of a resource and process constraint database, which is used to check if said manufacturing equipments are qualified to run a production lot and if said equipment has production resources required for said lot; means to determine optimal allowable queue time by running a simulation with different allowable queue time settings of said production lots considering utilization loss and rework required; means to calculate earliest release time for production lots based on said optimal allowable queue time and based on calculated next available time of exit equipment; and means to release and to assign production lots to manufacturing equipment. - View Dependent Claims (25, 26)
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Specification