单晶硅超精密磨削过程的分子动力学仿真

MOLECULAR DYNAMICS SIMULATION IN MONOCRYSTAL SILICON GRINDING

对内部无缺陷的单晶硅超精密磨削过程进行了分子动力学仿真,从原子空间角度观察了微量磨削过程,解释了微观材料去除、表面形成和亚表面损伤机理,并分析了磨削过程中的磨削力和磨削能量消耗。研究表明:磨削过程中,在与磨粒接触的硅表面原子受到磨粒的挤压和剪切发生变形,堆积在磨粒的前方,当贮存在变形晶格中的应变能超过一定值时,硅的原子键断裂,即完成了材料的去除;随着磨粒的运动,磨粒前下方的硅晶格在磨粒的压应力作用下晶格被打破,形成了非晶层,非晶层不断向前向深处扩展,造成了单晶硅亚表面的损伤;同时部分非晶层原子在压应力的作用下与已加工表层断裂的原子键结合,重构形成已加工表面变质层。

The molecular dynamic method is employed to simulate the grinding process of defect-free monocrystal silicon, explain the micro-scale mechanism of material removal, surface generation and sub-surface damage, and then analyze the grinding force and the grinding energy dissipation on atomic scale. The research shows： Some silicon atoms are deformed and piled up in front of the abrasive because of the abrasive＇s extrusion and cut. When the energy in silicon lattice reaches its maximum value, the bonds of silicon atoms are broken and the material is removed. With the advancement of the abrasive, the silicon lattice under the abrasive is fractured, and then the amorphous layers are formed and propagated, which causes the sub-surface damage. At the same time, some amorphous atoms are reconstructed and the degenerating layer of the machined surface is formed.