Liu Ping, Pei Qing-Xiang, Zhang Yong-Wei
Institute of High Performance Computing, A*STAR, Singapore, 138432, Singapore.
Sci Rep. 2022 Jul 13;12(1):11860. doi: 10.1038/s41598-022-16199-y.
Layered h-BN may serve as an important dielectric and thermal management material in the next-generation nanoelectronics, in which its interactions with electron beam play an important role in device performance and reliability. Previous studies report variations in the failure strength and mode. In this study, using molecular dynamics simulations, we study the effect of local heat injection due to the electron beam and h-BN interaction on the failure start time and failure mode. It is found that at the same heat injection rate, the failure start time decreases with the increase in the layer number. With the introduction of point defects in the heating zone, the failure always starts from the defect site, and the start time can be significantly shortened. For monolayer h-BN, failure always starts within the layer, and once failure starts, its propagation is through melting or vaporization of the h-BN atoms, and no swelling occurs. For multiple layers, once failure starts within the h-BN film, swelling occurs first. With continued heating, the large pressure induced by melting and vaporization can cause the burst of the layers above, leading to the formation of a pit. In the presence of multiple defects within the heating zone, these defects can interact, causing a further reduction in the failure start time. We also reveal the relation of beam power with layer-by-layer failure mode and swelling/pit formation mode. The present work not only reproduces many interesting experimental observations, but also reveal several interesting mechanisms responsible for the failure processes and modes. It is expected that the findings revealed here may provide useful references for the design and engineering of h-BN for device applications.
层状六方氮化硼（h-BN）可能成为下一代纳米电子学中重要的介电和热管理材料，其中它与电子束的相互作用对器件性能和可靠性起着重要作用。先前的研究报道了其失效强度和模式的变化。在本研究中，我们使用分子动力学模拟，研究了由于电子束与h-BN相互作用引起的局部热注入对失效起始时间和失效模式的影响。研究发现，在相同的热注入速率下，失效起始时间随层数的增加而减少。在加热区域引入点缺陷后，失效总是从缺陷部位开始，且起始时间可显著缩短。对于单层h-BN，失效总是在层内开始，一旦失效开始，其传播是通过h-BN原子的熔化或汽化，不会发生膨胀。对于多层h-BN，一旦在h-BN薄膜内开始失效，首先会发生膨胀。随着持续加热，熔化和汽化产生的巨大压力会导致上方各层破裂，形成一个坑。在加热区域存在多个缺陷时，这些缺陷会相互作用，导致失效起始时间进一步缩短。我们还揭示了束功率与逐层失效模式以及膨胀/坑形成模式之间的关系。本工作不仅重现了许多有趣的实验观察结果，还揭示了导致失效过程和模式的几个有趣机制。预计这里揭示的结果可为h-BN在器件应用中的设计和工程提供有用的参考。
