In this paper, we consider a scheduling problem for a single batch processing machine in semiconductor wafer fabrication facilities (wafer fabs). A batch is a group of jobs that are processed at the same time on a single machine. The jobs belong to incompatible families. Only jobs of the same family can be batched together. Each job has a weight, a due date, and a ready time. The performance measure of interest is the total weighted tardiness (TWT). The ready times are calculated based on information related to upstream machines that is stored in a Manufacturing Execution System (MES). Therefore, they can be uncertain. We propose a genetic algorithm (GA)-based approach. Sampling is used to take into account the uncertainty of the ready times. Results of computational experiments are reported that demonstrate that this approach performs well with respect to computing time and solution quality.