Method of storing and retrieving information for a resistive random access memory (RRAM) with multi-memory cells per bit
View Patent ↗Some embodiments include methods of storing and retrieving data for an RRAM array. The array is subdivided into a plurality of memory bits, with each memory bit having at least two memory cells. A memory bit is programmed by simultaneously changing resistive states of all memory cells within the memory bit. The memory bit is read by determining summed current through all memory cells within the memory bit. Some embodiments include RRAM having a plurality of memory cells. Each of the memory cells is uniquely addressed through a bitline/wordline combination. Memory bits contain multiple memory cells coupled together, with the coupled memory cells within each memory bit being in the same resistive state as one another.
1. A method of storing and retrieving data for a resistive random access memory (RRAM) array of X memory cells comprising:
forming individual memory bits, each of the individual memory bits having Y coupled memory cells, where Y is an integer greater than or equal to 2, such that the RRAM array has no more than X/Y of the individual memory bits; the Y coupled memory cells of each of the individual memory bits being arranged in parallel and being maintained in a common resistive state as one another during reading and writing operations; each of the individual memory bits having Y coupled memory cells providing enhanced reliability as compared to memory bits having only single memory cells; and wherein the array of X memory cells is sub-divided into a plurality of the individual memory bits each having an identical number Y of coupled memory cells, with each set of Y coupled memory cells comprised by one of the individual memory bit being configured to be separately programmed relative to other sets of Y coupled memory cells comprised by others of the individual memory bits, the programming of each individual memory bit including addressing the Y coupled memory cells of the individual memory bit by paired wordlines and a single bitline or by paired bitlines and a single wordline; and
separately programming one or more of the individual memory bits relative to others of the individual memory bits.
2. The method of claim 1 wherein the Y memory cells of the individual memory bit are read simultaneously.
3. The method of claim 1 wherein the Y memory cells of the individual memory bit are programmed substantially simultaneously.
4. The method of claim 1 wherein Y is two.
5. The method of claim 4 wherein each memory cell is uniquely addressed; and wherein the Y memory cells of each of the individual memory bits are addressed by paired wordlines and individual bitlines.
6. The method of claim 4 wherein each memory cell is uniquely addressed; and wherein the Y memory cells of each of the individual memory bits are addressed by paired bitlines and individual wordlines.
7. The method of claim 1 wherein Y is greater than two.
8. The method of claim 1 wherein the resistive random access memory comprises phase change memory.
9. The method of claim 1 wherein the resistive random access memory comprises multivalent metal oxide.
10. The method of claim 1 wherein the resistive random access memory comprises conductive bridging random access memory.
11. The method of claim 1 wherein the resistive random access memory (RRAM) comprises binary oxide.