A Bi-Objective Optimization Approach for a Parallel Machine Scheduling Problem Minimizing Total Quality Loss and Total Tardiness

In wafer fabrication, production quality is a key performance index which is subject to machine condition deterioration. This paper studies a parallel machine scheduling problem that can typically be found in the photolithography process. A bi-objective optimization model is proposed, which is solved with a sequential approach where the total quality loss is first minimized followed by the total tardiness. An optional maintenance operation is also considered to restore the machine condition to a certain level. Optimality properties are discussed, based on which an exact scheduling algorithm is developed. Experimental analyses derived from real data demonstrate the effectiveness of the proposed algorithm and support some managerial insights.