Gerardo's Research
MEMS-Based Magnetic Probe Microscopy
Introduction
A scanning-probe magnetic microscopy based on a high resolution magnetic
tunnel junction (MTJ) sensor is under construction. MTJ sensors are highly
sensitive magnetic field sensors but suffer from large 1/f noise. We have
developed a new approach for reducing the 1/f noise in an MTJ sensor by
using a MEMS resonator to mechanically modulate the magnetic field signal
to a high frequency. 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
(>10kHz). We have developed a fabrication process where the MTJ sensor is
fabricated first on the surface of an SOI wafer. Next, MEMS actuators are
fabricated in a two step deep reactive ion etching process. We have
demonstrated that the actuator designs work and began the final MTJ-MEMS
layout. Integrated devices are currently under fabrication and will be
characterized subsequently.