Method for Scheduling Single-arm Cluster Tools with Wafer Revisiting and Residency Time Constraints

摘要

In semiconductor manufacturing, there are wafer fabrication processes in cluster tools that need a wafer to visit some processing steps for more than once, leading to a revisiting process. Also, wafers may be subject to wafer residency time constraints. By considering atomic layer deposition (ALD) as a typical wafer revisiting process, this invention studies the challenging scheduling problem of single-arm cluster tools for the ALD process with wafer residency time constraints. By recognizing that the key to this problem is to schedule the robot tasks, the present invention presents different robot task sequencing strategies. With these strategies for different cases, the present invention performs the schedulability analysis and derives the schedulability conditions for such tools for the first time. If schedulable, the present invention proposes scheduling algorithms to obtain an optimal schedule efficiently. Illustrative examples are given to show the application of the proposed concepts and approach. Abstract figure: FIG. 3 Docket No.: UM1192AUOO 31 Loadlock Loadlock k-1I -I-iStep 1I 0 Step 2 -r Step 3 Docket No.: UM I 192AU00 32