AFM变载荷刻划硅基底的分子动力学研究

基于改进的分子动力学模型,研究了原子力显微镜(AFM)探针在硅表面变载荷刻划的形变特性。利用结构辨认算法显示非晶层的形成,并建立切屑分布的定量评价指标。在此基础上考察刻划速度、针尖半径和探针锥角对刻划效果的影响。结果表明:(1)当刻划速度小于0.3 nm/ps或大于等于1.5 nm/ps时,基底表面的切屑较少,刻划速度对沟槽表面的影响不大;(2)当针尖半径小于等于1 nm时,探针会发生磨损,当针尖半径大于等于1.5 nm时,探针发生弹性形变,针尖半径为2~3.5 nm能达到最佳刻划效果;(3)较大的锥角有利于减少基底表面的切屑分布。

Molecular dynamics simulation of AFM scratching on silicon with varying load

A series of molecular dynamics (MD) simulation are performed to study the surface deformation behavior of silicon substrate scratched by an atomic force microscopy (AFM) probe. A modified MD model is established, a quantitative index is proposed to describe the pile distribution, and the structure recognition algorithm is used to reveal the generation process of non-crystal layer. On these bases, the effects of scratching velocity, tip radius and probe wedge angle on the scratching process are investigated. Results show that (1) The scratching velocity has little effect on the groove surface. The piles on substrate surface are the least when the scratching velocity is less than 0. 3 nm/ps or greater than or equal to 1.5 nm/ps. (2) The probe wears and tears when the tip radius is less than or equal to 1 nm. The probe deforms elastically when the tip radius is greater than or equal to 1.5 nm. The tip radius should be 2-3.5 nm for the best scratching results. (3) The large wedge angle helps to reduce the piles distributed on the substrate surface.