Patent ID: 7660181

Claim:
A method of operating a nonvolatile memory device, comprising: providing at least one nonvolatile memory cell which comprises a first diode portion, a second diode portion and an antifuse dielectric layer separating the first diode portion from the second diode portion; applying a forward bias to the nonvolatile memory cell to rupture the antifuse dielectric layer such that a conductive link extends through the antifuse dielectric layer and such that the first diode portion and the second diode portion form a diode, and to switch the diode from the first resistivity, unprogrammed state to the second resistivity, programmed state, wherein the second resistivity state is lower than the first resistivity state; applying a reverse bias to the diode to switch the diode to a third resistivity, unprogrammed state, wherein the third resistivity state is higher than the second resistivity state; applying a forward bias to the diode to switch the diode to a fourth resistivity, programmed state, wherein the fourth resistivity state is lower than the third resistivity state; and sensing a resistivity state of the diode as a data state of the memory cell.