Indenter Size Effect on Stress Relaxation Behaviors of Surface-modified Silicon: A Molecular Dynamics Study

J Chen and L Fang and HQ Chen and K Sun and J Han, JOURNAL OF WUHAN UNIVERSITY OF TECHNOLOGY-MATERIALS SCIENCE EDITION, 37, 370-377 (2022).

DOI: 10.1007/s11595-022-2541-z

Long-lasting constant loading commonly exists in silicon-based microelectronic contact and can lead to the appearance of plastic deformation. Stress relaxation behaviors of monocrystalline silicon coated with amorphous SiO2 film during nanoindentation are probed using molecular dynamics simulation by varying the indenter's size. The results show that the indentation force (stress) declines sharply at the initial and decreases almost linearly toward the end of holding for tested samples. The amount of stress relaxation of SiO2/Si samples indented with different indenters during holding increases with growing indenter size, and the corresponding plastic deformation characteristics are carefully analyzed. The deformation mechanism for confined amorphous SiO2 film is depicted based on the amorphous plasticity theories, revealing that the more activated shear transformation zones(STZs) and free volume within indented SiO2 film promote stress relaxation. The phase transformation takes place to monocrystalline silicon, the generated atoms of Si-II and bct-5 phases within monocrystalline silicon substrate during holding are much higher than those for smaller indenter.

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