Abstract
In order to more deeply understand the PCM basic working principles and to better translate them into a real, working device, the PCM thermal model considerations, the fragility-related behavior of the phase change material, and the phase change material ionic motion aspects represent fundamental steps of the path. This chapter will be devoted on one hand to the insights into the cell thermal parameters, studied thanks to electrical measurements and aiming at the comprehension of the thermal resistance behavior in real PCM devices. On the other hand, the chapter will be focused on the discussion of advanced properties involving the phase change materials when heated up, in terms of both their fragility behavior and the relationship between fragility, viscosity and crystallization velocity, and the ionic motion effects. Concerning the thermal model, the discussion will be focused on some remarkable parameters, like thermal resistance, melting temperature, and power dissipation, their experimental evaluation and how much they are impacted by the geometry, and by the phase change material integrated into the PCM cell. Fragility is one of the characteristics making some phase change materials unique or a stronger material close to the glass temperature and a more flexible material close to the melting temperature. Understanding the ion migration effects during operation represents, instead, a mandatory step to enable the overcoming of possible issues at high number of cycles, derived from the fact that the phase change material goes through changes and hence cannot be considered as a uniform compound along its lifetime. So, on one hand, a successful implementation of PCM requires careful analysis and engineering of heat generation and thermal resistance from the cell core toward the outer thermal boundaries, and this represents a very important stage for power consumption optimization and for the SET operation performance. On the other hand, the SET operation itself as well as the reliability of PCM through lifetime is directly linked to the material and its specific alloy in terms of fragility behavior and elemental migration, respectively.
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Boniardi, M. (2018). Thermal Model and Remarkable Temperature Effects on the Chalcogenide Alloy. In: Redaelli, A. (eds) Phase Change Memory. Springer, Cham. https://doi.org/10.1007/978-3-319-69053-7_3
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DOI: https://doi.org/10.1007/978-3-319-69053-7_3
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