Embodiments of reversible resistive memory cells using polysilicon diodes are disclosed. The programmable resistive devices can be fabricated using standard
CMOS logic processes to reduce
cell size and cost. In one embodiment, polysilicon diodes can be used as program selectors for reversible resistive memory cells that can be programmed based on magnitude, duration,
voltage-limit, or current-limit of a supply
voltage or current. These cells are PCRAM, RRAM, CBRAM, or other memory cells that have a reversible
resistive element coupled to a polysilicon
diode. The polysilicon
diode can be constructed by P+ / N+ implants on a polysilicon substrate as a program selector. The memory cells can be used to construct a two-dimensional
memory array with the N-terminals of the diodes in a row connected as a wordline and the reversible resistive elements in a column connected as a bitline. By applying a
voltage or a current to a selected bitline and to a selected wordline to turn on the
diode, a selected
cell can be programmed into different states reversibly based on magnitude, duration, voltage-limit, or current-limit. The data in the reversible resistive memory can also be read by turning on a selected wordline to couple a selected bitline to a
sense amplifier. The wordlines may have high-resistivity local wordlines coupled to low-resistivity global wordlines through conductive contact(s) or via(s).