Crystalline and liquid Si3 N4 characterization by first-principles molecular dynamics simulations

Silicon nitride (Si3 N4 ) has a wide range of engineering applications where its mechanical and electronic properties can be effectively exploited. In particular, in the microelectronics field, the amorphous silicon nitride films are widely used as charge storage layer in metal-alumina-nitrideoxide nonvolatile memory devices. Atomic structure of amorphous silicon nitride is characterized by an high concentration of traps that control the electric behavior of the final device by the trappingde-trapping mechanism of the electrical charge occurring in its traps. In order to have a deep understanding of the material properties and, in particular, the nature of the electrical active traps a detailed numerical characterization of the crystalline and liquid phases is mandatory. For these reasons first-principles molecular dynamics simulations are extensively employed to simulate the crystalline Si3 N4 in its crystalline and liquid phases. Good agreement with experimental results is obtained in terms of density and formation entalpy. Detailed characterization of c-Si3 N4 electronic properties is performed in terms of band structure and band gap. Then constant temperature and constant volume first-principles molecular dynamics is used to disorder a stoichiometric sample of Si3 N4 . Extensive molecular dynamics simulations are performed to obtain a reliable liquid sample whose atomic structure does not depend on the starting atomic configuration. Detailed characterization of the atomic structure is achieved in terms of radial distribution functions and total structure factor

Crystalline and liquid Si

Silicon nitride (Si3 N4) has a wide range of engineering applications where its mechanical and electronic properties can be effectively exploited. In particular, in the microelectronics field, the amorphous silicon nitride films are widely used as charge storage layer in metal-alumina-nitrideoxide nonvolatile memory devices. Atomic structure of amorphous silicon nitride is characterized by an high concentration of traps that control the electric behavior of the final device by the trappingde-trapping mechanism of the electrical charge occurring in its traps. In order to have a deep understanding of the material properties and, in particular, the nature of the electrical active traps a detailed numerical characterization of the crystalline and liquid phases is mandatory. For these reasons first-principles molecular dynamics simulations are extensively employed to simulate the crystalline Si3 N4 in its crystalline and liquid phases. Good agreement with experimental results is obtained in terms of density and formation entalpy. Detailed characterization of c-Si3 N4 electronic properties is performed in terms of band structure and band gap. Then constant temperature and constant volume first-principles molecular dynamics is used to disorder a stoichiometric sample of Si3 N4 . Extensive molecular dynamics simulations are performed to obtain a reliable liquid sample whose atomic structure does not depend on the starting atomic configuration. Detailed characterization of the atomic structure is achieved in terms of radial distribution functions and total structure factor

Programming Operations Analysis and Statistics in One Selector and One Memory Ovonic Threshold Switching + Phase‐Change Memory Double‐Patterned Self‐Aligned Structure

published by Wiley-VCH GmbHPhys. Status Solidi RRL2024, 2300429https://onlinelibrary.wiley.com/doi/full/10.1002/pssr.202300429International audienceThis study explores the reliability of a phase‐change memory (PCM) cointegrated with an ovonic threshold switching (OTS) selector (one selector and one memory [1S1R] structure) based on an innovative double‐patterned self‐aligned architecture. The variability of the threshold voltage (Vth) for both the SET and RESET states is examined, comparing different distribution models to validate the use of mean and standard deviation as viable metrics. The dispersion of Vth is tracked under different programming conditions to provide insight into the evolution of device behavior over SET/RESET, endurance cycles, and read cycles. The PCM device is based on a “wall” structure and on Ge 2 Sb 2 Te 5 alloy, while the OTS is based on a GeSbSeN alloy. The analysis focuses on the programming characteristics and SET pulse optimization, studying current control and pulse fall times. The results are based on statistical data obtained from a kb‐sized memory array. A memory window of over 2 V is achieved. The research helps understanding the DPSA architecture, and PCM + OTS in general, offering insights into their programming, variability, and reliability targeting crossbar applications