Multiple-bit programmable resistive memory using diode as program selector

摘要

A method and system for multiple-bit programmable resistive cells having a multiple-bit programmable resistive element and using diode as program selector are disclosed. The first and second terminals of the diode having a first and second types of dopants can be fabricated from source/drain of MOS in a well for MOS devices or fabricated on the same polysilicon structure. If a multiple-bit programmable resistive cell has 2n (n>1) distinct resistance levels to store n-bit data, at least 2n−1 reference resistance levels can be designated to differential resistances between two adjacent states. Programming multiple-bit programmable resistive elements can start by applying a program pulse with initial program voltage (or current) and duration. A read verification cycle can follow to determine if the desirable resistance level is reached. If the desired resistance level has not been reached, additional program pulses can be applied.

主权项

1. A programmable resistive memory, comprising:
a plurality of multiple-bit programmable resistive memory cells, at least one of the multiple-bit programmable resistive memory cells having an programmable resistive element with 2n (n>1) distinct resistance levels and at least one diode as program selectors; wherein the first and second terminals of the diode with a first and second types of dopants being built as the source/drain of a MOS device in a well for MOS devices or on the same polysilicon structure; a program control circuit to apply high voltage or high current pulses to program the programmable resistive cells; and a sensing circuit with at least 2n−1 reference resistance levels to sense the programmable resistive cell into digital data,wherein the programmable resistive memory is configured to program to the desirable resistance level by repetitively turning on the program control circuit to program the multiple-bit programmable resistive memory cells, andwherein the sensing circuit is configured to verify the data until the desirable resistance level is reached, andwherein the program control circuit or the sensing circuit has at least one register to store program count or bit count.