单晶硅纳米级磨削过程的理论研究

Theoretical Study on the Monocrystal Silicon Nanometric Grinding Process

对内部无缺陷的单晶硅纳米级磨削过程进行了分子动力学仿真,从磨削过程中瞬间原子位置、磨削力、原子间势能、损伤层深度等角度研究了纳米级磨削加工过程,解释了微观材料去除、表面形成和亚表面损伤机理。研究表明:磨削过程中,单晶硅亚表面损伤的主要形式是非晶结构形式,无明显的位错产生,硅原子间势能的变化是导致单晶硅亚表面损伤的重要原因;另外,发现磨粒原子与硅原子之间有黏附现象发生,这是由于纳米尺度磨粒的表面效应而产生的。提出了原子量级条件下单晶硅亚表面损伤层的概念,并定义其深度为沿磨削深度方向原子发生不规则排列的原子层的最大厚度。

The molecular dynamics method was employed to simulate the grinding process of defect -free monocrystal silicon, to explain the micro- scale mechanism of material removal, surface generation and sub- surface damage from the viewpoint of instantaneous distribution of atoms, grinding force, potential energy among silicon atoms and depth of damage layers. Under the conditions of present simulation, it is discovered that the subsurface damage is mainly composed of the amorphous layers,no obvious dislocations are found. And the subsurface damage of the monocrystal silicon is mainly concerned with the variation of potential energy among silicon atoms. The sorption among silicon atoms and diamond atoms is occurred due to the surface effect of the single grit. On atomic scales, the depth of subsurface damage layer of monoerystal silicon was defined as the maximal thickness of the atomic layers with random array in the subsurface of monocrystal silicon in the direction of grinding depth.