Active magnetic field canceling system

The extremely low frequency (ELF) magnetic field has significant impact on yield rate especially when the processing reaches less than 14 nanometer in next-generation nano-Fab. For sensitive equipments such as the SEMs, TEMs, STEMs, FIB writers, and E-beam writers, it suggests that the ELF magnetic field should be lower than 0.5 milli-Gauss to guarantee good yield. Therefore, mitigating the magnetic field by active/passive approaches such as the material shielding, wire permutation, and active canceling are highly demanded.