Abstract The creep properties and deformation behaviors of monocrystalline silicon coated by an amorphous SiO2 film with diverse thickness are explored using nanoindentation via molecular dynamics simulation. It is found that the creep displacement grows sharply at the beginning and then steadily towards the end of holding, and the final creep displacement is significantly larger at higher peak load. For a given bilayer SiO2/Si composite, the stress exponent n decreases with increasing peak load, exhibiting an inverse indentation size effect (ISE). At the same peak load, n decreases slightly with the increasing SiO2 film thickness. Careful analysis suggests the densification of amorphous SiO2 with different thickness occurs under three peak load during loading. The extent plastic deformation of SiO2 occurring during loading, to which depends on the thickness of SiO2 film and peak load, alters the creep behaviors of composites. The creep result indicates that SiO2 film undergoes densification during holding, and there is an increased deformation amount for SiO2 film and underlying silicon substrate under higher peak load. The study may be helpful for materials removal during CMP process and microdevices design in MEMS.

中文翻译：

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表面改性硅的蠕变行为：分子动力学研究

摘要 利用纳米压痕技术通过分子动力学模拟研究了不同厚度非晶SiO2 薄膜包覆单晶硅的蠕变特性和变形行为。发现蠕变位移在开始时急剧增长，然后在保持结束时稳定增长，最终蠕变位移在较高的峰值载荷下显着增大。对于给定的双层 SiO2/Si 复合材料，应力指数 n 随着峰值载荷的增加而降低，表现出逆压痕尺寸效应 (ISE)。在相同的峰值负载下，n随着SiO2薄膜厚度的增加而略有下降。仔细分析表明，在加载过程中，在三个峰值载荷下，不同厚度的非晶 SiO2 会发生致密化。SiO2 在加载过程中发生塑性变形的程度，取决于 SiO2 膜的厚度和峰值载荷，改变复合材料的蠕变行为。蠕变结果表明SiO2薄膜在保持过程中发生致密化，在较高的峰值载荷下，SiO2薄膜和下面的硅衬底的变形量增加。该研究可能有助于 CMP 工艺过程中的材料去除和 MEMS 中的微器件设计。