The effect of Ge content on structural evolution of Ge-rich GeSbTe alloys at increasing temperature

Pražáková, Lucie; Nolot, Emmanuel; Martínez, E.; Rouchon, D.; Fillot, F.; Bernier, Nicolas; Elizalde, R.; Bernard, M.; Navarro, G.

doi:10.1016/j.mtla.2022.101345

Cited by 8 publications

(11 citation statements)

References 36 publications

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“…An additional consideration is on the amount of crystallized Ge that results rather small, as inferred from the overall intensity of the XRD and, more evidently, Raman peaks. Again, in this case, our observations are compatible with the results from L. Prazakova et al [35], who reported that the crystallization of the cubic GST phase is followed by the heterogeneous nucleation and consequent growth of the Ge crystalline phase. This sequential crystallizations have been well-observed in layers with low Ge content, since they take place at different temperatures.…”

Section: Resultssupporting

confidence: 93%

“…Therefore, even from Raman investigations, we do not have an indication of a full crystallization of both Ge-rich GST and Ge [33,34]. Our interpretation is compatible with a recent discussion on the Ge-rich GST crystallization by L. Prazakova et al [35]. They studied, by Raman spectroscopy and XRD techniques, the crystallization mechanism of Ge-rich GST alloys with a large Ge enrichment Furthermore, from the inspection of the UPS spectra in Figure 2c,d a clear difference in the valence band (VB) line shape can be seen.…”

Section: Resultssupporting

confidence: 91%

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Growth, Electronic and Electrical Characterization of Ge-Rich Ge–Sb–Te Alloy

et al. 2022

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In this study, we deposit a Ge-rich Ge–Sb–Te alloy by physical vapor deposition (PVD) in the amorphous phase on silicon substrates. We study in-situ, by X-ray and ultraviolet photoemission spectroscopies (XPS and UPS), the electronic properties and carefully ascertain the alloy composition to be GST 29 20 28. Subsequently, Raman spectroscopy is employed to corroborate the results from the photoemission study. X-ray diffraction is used upon annealing to study the crystallization of such an alloy and identify the effects of phase separation and segregation of crystalline Ge with the formation of grains along the [111] direction, as expected for such Ge-rich Ge–Sb–Te alloys. In addition, we report on the electrical characterization of single memory cells containing the Ge-rich Ge–Sb–Te alloy, including I-V characteristic curves, programming curves, and SET and RESET operation performance, as well as upon annealing temperature. A fair alignment of the electrical parameters with the current state-of-the-art of conventional (GeTe)n-(Sb2Te3)m alloys, deposited by PVD, is found, but with enhanced thermal stability, which allows for data retention up to 230 °C.

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Section: Resultssupporting

confidence: 93%

Section: Resultssupporting

confidence: 91%

Growth, Electronic and Electrical Characterization of Ge-Rich Ge–Sb–Te Alloy

et al. 2022

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“…[17,24,25] However, the latter represents a real challenge for out-of-stoichiometry alloys like GGST, which result at the end of the process in composite materials with highly inhomogeneous composition and large element concentration spread. [14,18,20] In this case, quantitative evaluation with The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/pssr.202200458. DOI: 10.1002/pssr.202200458 Ge-rich GST (GGST) alloys have been shown to fulfill the tough temperature specifications required by automotive applications.…”

Section: Challenges Of Physical Analysis On Embedded Devicesmentioning

confidence: 99%

“…As previously stated, GGST alloys are very sensitive to temperature and TB, showing a crystallization process that occurs concurrently with segregation in Ge and Ge 2 Sb 2 Te 5 phases. [18][19][20][21][22][23] Thus, from a process integration point of view, GGST is sensitive to different BEOLs, which may differ by TB and deposed dielectrics. At the end of the process, GGST results in a significantly segregated material with possible impact on reliability and yield performances.…”

Section: Transmission Electron Microscopy Analysis and Experimental R...mentioning

confidence: 99%

“…[17] Previous literature has been focused on the characterization and understanding of the specific GGST crystallization mechanism, revealing its dual nature: a first Ge depletion step, to expel all the Ge in excess from the GST matrix, followed by the crystallization of the whole alloy in two separated compositions, namely, Ge 2 Sb 2 Te 5 and Ge. [18][19][20][21][22][23]…”

Section: Introduction 1embedded Phase Change Memory Framework and Sta...mentioning

confidence: 99%

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Advanced Metrics for Quantification of By‐Process Segregation beyond Ternary Systems

Petroni

Patelmo

Serafini

et al. 2023

Physica Rapid Research Ltrs

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Ge‐rich GST (GGST) alloys have been shown to fulfill the tough temperature specifications required by automotive applications. Thus, they are the most promising materials for the embedded phase‐change memory market. In this respect, the characterization of the material properties once patterned and fully integrated is instrumental to improve the process and optimize the device performance. A description of the material behavior through a realistic sequence of process steps is still missing. Herein, a statistical‐based methodology capable to extract advanced metrics for the quantification of by‐process segregation beyond ternary systems is presented, capable to quantify thermal evolution of any out‐of‐stoichiometry and segregated material beyond ternary systems. The methodology to study the physical behavior of GGST as a function of a typical back‐end‐of‐line (BEOL) process is exploited, providing a further comparison between three different BEOL‐ended GGST.

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Film Thicknesses Influence on the Interfacial Thermal Resistances within Ge‐Rich Ge₂Sb₂Te₅/Ge₂Sb₂Te₅ Multilayers

Chassain,

Kusiak,

Gaborieau

et al. 2023

Physica Rapid Research Ltrs

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Phase change memories (PCRAM) are often made of chalcogenide alloys in the form of multilayer systems (MLS). The mostly used alloys are Ge2Sb2Te5 and Ge‐rich Ge2Sb2Te5. The current article reports on the thermal characterization of very thin (<5 nm) Ge‐rich Ge2Sb2Te5/Ge2Sb2Te5 MLS by modulated photothermal radiometry (MPTR). The MPTR method allows for the investigation of such samples by determining, with an inverse method, the total thermal resistance of the stack deposited on the substrate. With the measurement of the total thermal resistance, it is possible to determine the thermal conductivity of the deposit and the interfacial thermal resistances between layers. The interfacial thermal resistance between Ge‐rich Ge2Sb2Te5/Ge2Sb2Te5 is characterized, which is an important parameter to reduce the energy cost of the PCRAM functioning. It is also possible to highlight a decrease in interface quality inside the MLS after the beginning of the phase transition around 250 °C.

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The effect of Ge content on structural evolution of Ge-rich GeSbTe alloys at increasing temperature

Cited by 8 publications

References 36 publications

Growth, Electronic and Electrical Characterization of Ge-Rich Ge–Sb–Te Alloy

Growth, Electronic and Electrical Characterization of Ge-Rich Ge–Sb–Te Alloy

Advanced Metrics for Quantification of By‐Process Segregation beyond Ternary Systems

Film Thicknesses Influence on the Interfacial Thermal Resistances within Ge‐Rich Ge₂Sb₂Te₅/Ge₂Sb₂Te₅ Multilayers

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The effect of Ge content on structural evolution of Ge-rich GeSbTe alloys at increasing temperature

Cited by 8 publications

References 36 publications

Growth, Electronic and Electrical Characterization of Ge-Rich Ge–Sb–Te Alloy

Growth, Electronic and Electrical Characterization of Ge-Rich Ge–Sb–Te Alloy

Advanced Metrics for Quantification of By‐Process Segregation beyond Ternary Systems

Film Thicknesses Influence on the Interfacial Thermal Resistances within Ge‐Rich Ge2Sb2Te5/Ge2Sb2Te5 Multilayers

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Film Thicknesses Influence on the Interfacial Thermal Resistances within Ge‐Rich Ge₂Sb₂Te₅/Ge₂Sb₂Te₅ Multilayers