Applied linear programming model to optimize resist arrangement

Photolithography holds the bottleneck of productivity and carries the role of supplier in semiconductor industry, which is considered to be the most popular industry among other high-tech industries nowadays in the world. Therefore, photolithography procedure should be the most critical manufacturing process in semiconductor industry. To maximize productivities by using existing steppers is the goal for all the semiconductor manufactories, since the stepper is the key and most expensive equipment in the photolithography process. Therefore, how to improve and balance the stepper capacity is one of the major missions for us. However, the resist is the major key point of what layers stepper can run, so how to arrange the resist distribution into steppers decides whether the loading of each stepper is balanced or not. This study focused on the resist distribution system, and tried to develop an optimal system by referring to some important references. We treated linear programming as the basic model to achieve optimization for resist distribution. This model can exactly compute the quantity of resists that were used; meanwhile, it can accurately predict the amount deviated by the change of wafer start plan. From experience and statistics, the model fit the field data quite well.