Analyses on Cleanroom-Free Performance and Transistor Manufacturing Cycle Time of Minimal Fab

In this paper, we introduce our developed clean-localized system for a cleanroom-free semiconductor manufacturing where a wafer is air-tightly transferred between the carrier and the machine via a load port and process in a clean chamber. The system has been applied to “minimal fab” specially designed to process a half-inch wafer for low-cost and low-volume device productions. To confirm the localized clean-performance of our system, we have measured the clean levels in process chamber of a machine and the wafer transfer system. Both are resulting in ISO class 4, while the clean level of the circumstance is in ISO class 9. In order to estimate the system performance in the issue of electronic device properties, we fabricate a traditional MOSFET using minimal fab for the entire process. The measured density of interface states (Dit) of the MOSFET was 7.7×1010 cm^-2 and the off-leak current was 4×10^-12 A. These are sufficiently low to confirm the acceptable particle contamination level of the system which has less impact on the device characteristics. Due to a compact size of the minimal machine, the wafer transfer distance between processes is minimized. The process efficiency of the minimal fab in terms of wafer transfer time and wafer waiting time is also studied.