Method of making a magnetoelectronic device

DETAILED DESCRIPTION An object of the present invention therefore is to provide an improved architecture for a hybrid Hall Effect device to be used as a memory cell in a memory array.
A further object of the present invention is to provide an improved architecture for a random access memory array of hybrid Hall Effect memory cells which permits a bias voltage (or current) to be provided to each such cell, thus resulting in improved signal level and signal-to-noise ratio characteristics for such array.
Another object of the present invention is to provide an improved memory cell for application in a memory array environment, which affords improved cell isolation and reduced cross talk between cells in the array.
According to the present invention, an array of modified Hall Effect plate memory elements with improved performance is formed by providing the bias source I.
sub.
B or (V.
sub.
B) directly to each cell in the array to increase the SNR.
The outputs of the Hall Effect plate memory elements can be coupled to a select transistor which acts as an isolation element to reduce cross-talk between cells in the array.
In this way, the magnetization state of the ferromagnetic layer and the output of the Hall Effect plate for each hybrid memory cell is retained and isolated from other hybrid memory cells.
The bias source and ground for the cells are provided by additional individual levels of lithography, and this choice increases the number of fabrication steps (and levels) by comparison with the simpler array described earlier.
However, the hybrid Hall Effect device requires far fewer levels than conventional dynamic random access memories (DRAM) and this economy of fabrication is only marginally diminished by the addition of a few levels.
In the preferred cell architecture, one selection transistor is fabricated within each cell.
When a select transistor for a particular cell is addressed the Hall voltage developed by that cell is the only voltage transmitted to the input line of a sense amplifier that is common to a column of cells