Mask cycle time and serviceability improvement through capacity planning and scheduling software

This paper reports on how the manufacturing line simulator, Mansim, and the short interval scheduler, OnTime, both of which are by Tyecin Systems, have been used in the mask job shop environment for capacity planning and scheduling so as to reduce current manufacturing cycle time and improve customer serviceability. To use the aforementioned software, a model which accurately represents the manufacturing line was built. The model includes mask process flows, process times, tool capabilities, tool failures, alternate processing loops, process yields, priority rules, and alternate tool options. The first major problem in developing this model was estimating the time it takes to write and inspect a mask. It was determined that a data model using regression analysis to estimate write and inspect times based upon known product parameters was necessary. Previously, write and inspect times were estimated using mask yield; however, using regression model and making write and inspect times a function of multiple parameters greatly improved the correlation between estimated and actual write and inspect times. As a result, a reliable capacity plan and short interval schedule could be generated no matter what the complexity of the mask.