Resistive random-access memory

	Email		Print
	Bookmark		Link

Resistive random-access memory

Resistive random-access memory (RRAM) is a new non-volatile memory type being developed by many companies. The technology bears some similarities to CBRAM

Programmable metallization cell

The programmable metallization cell, or PMC, is a new form of non-volatile memory computer memory being developed at Arizona State University and its spinoff, Axon Technologies....
and phase change memory.

Different forms of RRAM have been disclosed, based on different dielectric materials, spanning from perovskite

Perovskite

A perovskite is any material with the same type of crystal structure as calcium titanium oxide At the high pressure conditions of the Earth's mantle , the pyroxene enstatite, MgSiO3, transforms into a denser perovskite-structured polymorphism ; this phase may be the most common mineral in the Earth.....
s to transition metal oxides

Transition metal oxides

Transition metal oxides comprise a class of materials that contain transition metals and oxides. Well known materials include Yttrium barium copper oxide....
to chalcogenide

Chalcogenide

A chalcogenide is a chemical compound consisting of at least one chalcogen ion and at least one more electropositive element. Although all group 16 elements of the periodic table are defined as chalcogens, the term is more commonly reserved for sulfides, selenides, and tellurides, rather than oxides....
s. Even silicon dioxide has been shown to exhibit resistive switching as early as 1967, and has recently been revisited.

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.

Discussion

Ask a question about 'Resistive random-access memory'

Start a new discussion about 'Resistive random-access memory'

Answer questions from other users

Full Discussion Forum

Encyclopedia

Resistive random-access memory (RRAM) is a new non-volatile memory type being developed by many companies. The technology bears some similarities to CBRAM

Programmable metallization cell

Perovskite

Transition metal oxides

Transition metal oxides comprise a class of materials that contain transition metals and oxides. Well known materials include Yttrium barium copper oxide....
to chalcogenide

Chalcogenide

Mechanism

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.

Demonstrations

Papers at the IEDM Conference in 2007 suggested for the first time that RRAM exhibits lower programming currents than PRAM

Phase-change memory

Phase-change memory is a type of NVRAM. PRAM uses the unique behavior of chalcogenide glass, which can be "switched" between two states, crystalline and amorphous solid, with the application of heat....
or MRAM

MRAM

Magnetoresistive Random Access Memory is a non-volatile memory Computer storage technology, which has been under development since the 1990s. Continued increases in density of existing memory technologies – notably Flash RAM and DRAM – kept it in a niche role in the market, but its proponents believe that the advantages are so ov...
without sacrificing programming performance, retention or endurance. On April 30, 2008 HP announced a memristor

Memristor

Memristors are a class of Passive circuit element two-terminal circuit elements that maintain a function al relationship between the time integrals of electric current and voltage....
, 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. At IEDM 2008, the highest performance RRAM technology to date was demonstrated by ITRI

Itri

Itri is an agricultural centre divided in two parts by a small river, the Pontone. It lies in a valley between the Monti Aurunci and the sea, not far from the Gulf of Gaeta....
, showing switching times less than 10 ns and currents less than 30 microamps.

Future applications

RRAM has the potential to become the front runner among other non-volatile memories. Compared to PRAM, RRAM operates at a faster timescale (switching time can be less than 10 ns), while compared to MRAM, it has a simpler, smaller cell structure (less than 8F² MIM stack). Compared to flash memory and racetrack memory, a lower voltage is sufficient and hence it can be used in low power applications.

AFM

Atomic force microscope

The atomic force microscope or scanning force microscope is a very high-resolution type of Scanning probe microscopy, with demonstrated resolution of fractions of a nanometer, more than 1000 times better than the diffraction limited....
data suggest that RRAM is scalable down to 30 nm; below this scale, its nature is harder to predict, mainly due to difficulty in probing such small sizes. However, the motion of oxygen atoms is a key phenomenon for oxide-based RRAM; one study has indicated that oxygen motion may take place in regions as small as 2 nm. It is believed that if a filament is responsible, it would not exhibit direct scaling with cell size. Instead, the current compliance limit (set by an outside resistor, for example) could define the current-carrying capacity of the filament.