Chalcogenide materials and their application to Non-Volatile Memories

doi:10.1016/j.mee.2010.06.042

Microelectronic Engineering

Volume 88, Issue 5, May 2011, Pages 807-813

https://doi.org/10.1016/j.mee.2010.06.042 Get rights and content

Abstract

Chalcogenide materials are chemical compounds consisting of at least one chalcogen ion, i.e. a chemical element in column VI of the periodic table also known as the oxygen family. More precisely the term chalcogenide refers to the sulphides, selenides, and tellurides. Among the various applications of this class of materials, we review here two types of Non-Volatile Memories (NVM): the Phase Change Memories (PCM) which rely on the rapid crystallisation and high electrical contrast between the amorphous and crystalline phases of some of these compounds, and the Current Bridging Random Access Memories (CBRAM) which make use of the ionic conduction of compounds containing metallic ions.

Section snippets

Chalcogenide materials

Chalcogenide materials are chemical compounds consisting of at least one chalcogen ion, i.e. a chemical element in column VI of the periodic table. These compounds show similar patterns in their electron configuration, especially the outermost shells, resulting in similar trends in chemical behaviour. They form covalent glasses with properties intermediate between those of organic polymers and oxide glasses. These properties result from their bonding characteristics which can be best described

Phase Change Memories (PCM)

A PCM is a solid state memory, in which each node of the memory cell array consists of a selector device in series with a storage element made of a small volume of so-called phase change material. The binary information is coded through the structural state of the phase change material, being either amorphous or crystalline. The reading principle relies on the large electrical resistivity contrast between the two states, the crystalline phase being typically 10³ times more conductive than the

Current Bridging Random Access Memories (CBRAM)

Current Bridging Random Access Memories (CBRAM) make use of the ionic conduction of the chalcogenide glasses. The high resistance OFF state consists of a small volume of metal-doped chalcogenide sandwiched between two electrodes, one of it being a soluble metallic anode. The transition toward the low resistance ON state is induced by a voltage pulse: the negative potential applied to the inert cathode leads to the electro-migration of dissolved positives ions and hereafter electro-deposition of

Conclusion

PCM and CBRAM are two alternative Non-Volatile Memory technologies which are currently at completely different maturity levels. From a materials point of view, the open questions regard respectively the ultimate performances that PCM cells can reach and the degree of reliability that CBRAM can fulfil. In conclusion, we would like to mention PCM and CBRAM are only two of the various commercial applications of chalcogenide materials: phase change materials are also used for rewritable optical

Acknowledgements

The author wishes to acknowledge the dedication of the LETI teams involved in the PCM and CBRAM programs, which have respectively been carried out in the frame of CEA-LETI/ST Microelectronics and CEA-LETI/Freescale collaborations.

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The films grow under near thermodynamic equilibrium conditions as another consequence of the enclosure by the hot wall [1]. The chalcogenides are useful for various applications [3], including thermoelectrics [4,5], non-volatile memories [6] and solar cells [7]. Some of them are well-known as topological insulators [8].
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Chalcogenide materials and their application to Non-Volatile Memories

Abstract

Section snippets

Chalcogenide materials

Phase Change Memories (PCM)

Current Bridging Random Access Memories (CBRAM)

Conclusion

Acknowledgements

Solid-State Electr.

Solid State Ionics

Journal of Non-Crystalline Solids

Microelectron. Eng.

J. Phys. C: Solid State Phys.

Nat. Mater.

Nat. Mater.

Nat. Mater.

Nat. Mater.

IEEE Trans. Electron Dev.

J. Appl. Phys.

Phys. Rev. B

Japanese J. Appl. Phys.

J. Magn. Soc. Japan

Phys. Stat. Sol. (a)

J. Appl. Phys.

Phys. Rev. B

J. Electrochem. Soc.

IEEE Trans. Electron Dev.

Appl. Phys. Lett.