Spin polarized tunneling for memory cell application

Spin dependent tunnel junctions were fabricated and characterized, using CoFe electrodes with an insulating barrier of 1.5-1.8 nm Al/sub 2/O/sub 3/. Magnetoresistance (MR) signals of 27% were measured for a junction with 123 k/spl Omega/ resistance (12/spl times/2 /spl mu/m/sup 2/ area). The MR signal decreases 50% for a bias voltage of 400 mV. The self-aligned microlithography fabrication process is described, and the storage and retrieval of data bits is illustrated. The engineering problems the authors faced in using tunnel junctions as memory cells are reviewed.