Recipe cascading in a wafer processing system

A method of operating a wafer cluster tool, wherein the wafer cluster tool includes a plurality of process chambers for processing a plurality of wafers, the method comprising:

• loading the plurality of wafers into the wafer cluster tool, wherein each wafer of the plurality of wafers is loaded after an end of one sending period, the sending period comprising a predetermined uniform time interval;
• processing the plurality of wafers in the cluster tool, wherein the plurality of wafers are processed concurrently in the cluster tool according to a plurality of recipes, wherein each recipe of the plurality of recipes includes a plurality of process times for the process chambers in the wafer cluster tool, the process times comprising a unit of the predetermined uniform time interval.

A method of scheduling a wafer cluster tool, wherein the wafer cluster tool is coupled to a computer system for scheduling the cluster tool, the method comprising:

• inputting a plurality of recipes into the computer system, wherein each recipe of the plurality of recipes includes a plurality of process times for the cluster tool, the process times comprising a unit of a predetermined uniform time interval;
• outputting a schedule for the wafer cluster tool, such that the schedule enables the wafer cluster tool to process a plurality of wafers concurrently using the plurality of recipes, wherein each wafer of the plurality of wafers is processed at a uniform rate based on the predetermined uniform time interval.

A wafer cluster tool comprising:

• a plurality of processing chambers for processing a plurality of wafers, wherein the plurality of wafers are processed according to a plurality of recipes, such that each recipe of the plurality of recipes specifies a plurality of process times for a wafer from the plurality of wafers;
• a plurality of wafer transporters for transporting the plurality of wafers between the process chambers;
• a scheduler coupled to the wafer cluster tool, the scheduler including a computer program running on a computer system, wherein the scheduler ensures that the cluster tool processes the plurality of wafers concurrently and determines a schedule for the cluster tool by use of a genetic algorithm encoded in the computer program.