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Dawn of the Brain-Gate Era: PCM Electro-Migration Problem Solved

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Ron Neale
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Re: Sb, Te segregation
Ron Neale   1/14/2017 7:14:55 AM
In my article I used the term electro-migration as a general term to cover the process of high current density element separation. I am reminded electro migration is a one directional effect caused by momentum transfer from majority carriers to atoms. When the active region is melted, Sb atoms become positive ions and Te atoms become negative ions due to their different electro-negativity. Sb moves toward cathode and Te moves toward anode. It is suggested the terms "elemental segregation" or "electro-separation" should be used instead of "electro-migration.

On weak ground I suppose one could argue on the basis of conservation of volume that the movement of Te by electro-migration to the anode would result in the displacement of antimony towards the cathode. If the model of my article is correct, i.e. central core of active material with crystalline material on either side. The Te rich material (see Fig 2) has not been molten and the Te enrichment and Sb depletion of it must be accounted for by some mechanisms other than the movement of ions in molten material.

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Sb, Te segregation
resistion   1/12/2017 10:12:22 AM
Still surprised that Sb, Te segregation still plaguing PCM. MRAM has its share of issues as well, starting with larger than DRAM cell size.

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