High-speed wafer magnetic field inspection for semiconductor manufacturing

Abstract

We propose a new Magneto-optical Kerr effect (MOKE) system which consists of a dedicated electromagnet and a sensor for inspecting next generation memory, such as Spin-Transfer Torque Magnetoresistive Random Access Memory (STTMRAM). Conventional MOKE system is able to measure a magnetic hysteresis loop at a specific point by detecting the polarization rotation angle with changing the magnetic field intensity with the precision of less than 0.1deg on the reflected light. However, it takes several tens of seconds for measuring each point. We have demonstrated that inspection throughput of more than 1 wafer per hour with 2um pixel resolution can be achieved using proposed method called SCAN MOKE.