A programmable memory cell comprised of a transistor located at the crosspoint
of a column bitline and a row wordline is disclosed. The transistor has its gate
formed from the column bitline and its source connected to the row wordline. The
memory cell is programmed by applying a voltage potential between the column bitline
and the row wordline to produce a programmed n+ region in the substrate underlying
the gate of the transistor. Further, a gate dielectric of the transistor has a
higher breakdown voltage near the source connected to the row wordline than its drain.