Integration of MEMS Actuators with Magnetic Tunnel Junction Sensors

We are developing techniques to integrate magnetic tunnel junction (MTJ) sensors with MEMS actuators for magnetic scanning-probe microscopy applications. In this application, the MTJ sensor is raster-scanned over a specimen and spatial variations in the magnetic field are recorded. We have developed a fabrication process where the MTJ sensor is fabricated first on the surface of an SOI wafer. Subsequently, MEMS actuators are fabricated in a two step deep reactive ion etching process. We have carried out electromechanical testing of the actuator voltage-to-position and frequency response. MEMS actuators are uniquely suited to achieve both precise, micron-scale control of the average sample-to-sensor separation and to AC modulate the separation and MTJ signal at a very high frequency (>10 kHz).