Improvement of mini fab uptime by the multi-task and multi-functional tools

Multi-task and multi-functional tools can achieve alternative operations for example LPCVD deposition of both Poly Si and SiN films with good repeatability and few particulate. Using those tools we can reduce total tool number and "only-one tool" which means one tool only exists for a type of tool in the fab. We have also considered mini-fab availabilities and evaluate both methods of a full calculation and an approximate calculation. The results show that the tool reduction is more effective to obtain good fab availability and uptime, especially the reduction of "only-one tool" is most important to improve mini-fab availability. The approximate calculation is simple to estimate the fab availability and has a possibility to extend mega-fab estimations.