Resistive random-access memory

This article contains information about scheduled or expected future computer chips. It may contain preliminary or speculative information, and may not reflect the final specification of the product.

Resistive random-access memory (RRAM) is a new non-volatile memory type being developed by Fujitsu, Sharp,^[1] Samsung,^[2] Micron Technology,^[3] Spansion,^[4] Macronix,^[5] Winbond,^[6] Unity Semiconductor,^[7] and other companies.

Different forms of RRAM have been disclosed, based on different dielectric materials, spanning from perovskites to transition metal oxides to chalcogenides. Even silicon dioxide has been shown to exhibit resistive switching as early as 1967,^[8] and has recently been revisited.^[9]

The basic idea is that a dielectric, which is normally insulating, can be made to conduct through a filament or conduction path formed after application of a sufficiently high voltage. The conduction path formation can arise from different mechanisms, including defects, metal migration, etc. Once the filament is formed, it may be reset (broken, resulting in high resistance) or set (re-formed, resulting in lower resistance) by an appropriately applied voltage. Recent data suggest that probably many current paths, rather than a single filament, are involved.^[10]

Papers at the IEDM Conference in 2007 suggested for the first time that RRAM exhibits lower programming currents than PRAM or MRAM without sacrificing programming speed, retention or endurance.^[11]

On April 30, 2008 HP announced a memristor, a fundamentally new circuit element that is another possible demonstration of RRAM, and on July 8 they announced they would begin prototyping RRAM using their memristors.^[12]

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