Tunnel magnetoresistive current sensors for IC testing

In this work, we demonstrate that tunnel magnetoresistive (TMR) elements can be used as sensitive built-in current sensors in the μA–mA range for IC testing. The sensor can be integrated in CMOS and uses a technology similar to the magnetic random access memory (MRAM) technology; therefore the implementation of the sensor is expected to be cost-effective in ICs containing embedded MRAM. A sensitivity of 2.5 (mV/V)/mA and a current resolution of about 5 μA have been achieved. The design, fabrication process and measurement results of different sensor geometries are presented and discussed.