We compare single wafer systems, conventional batch systems and fast ramp batch systems in terms of throughput, cycle time and cost per wafer for four different processes. Comparison is based on dynamic fab simulations done with proprietary software package. The results show that vertical furnaces are the best choice in terms of throughput and cost per wafer for those processes for which both a single wafer and a batch process exist. Fast ramp furnaces are an attractive option to conventional batch furnaces in case a shorter cycle time is needed. Single Wafer systems show a substantially lower cycle time, but a higher cost per wafer. These additional costs might be justified by short cycle times in e.g. ASIC's manufacturing and in product development.