分子动力学模拟不同入射角度的SiF3+对SiC表面的作用

采用分子动力学模拟方法研究了300K入射能量150eV时,以不同角度(5°、30°、60°和75°)入射的SiF3+与SiC表面的相互作用过程。模拟中使用了用于Si-F-C体系的Tersoff-Brenner势能函数。模拟结果显示,入射SiF3+与SiC表面相互作用后会分解,分解率随着入射角度的增加而减小。分解产物除少量散射外,大部分会沉积在SiC表面,Si和F在SiC表面的平均饱和沉积量随入射角度的增加而减少。随着SiF3+不断轰击SiC表面,SiC表面会形成Si-F-C反应层,且反应层厚度随着入射角度的增加而减少。同时发现SiC中的Si原子较C原子更容易被刻蚀,与实验结果一致。当刻蚀达到稳定,入射角度为5°、30°、60°和75°时,C的刻蚀率分别约为0.026、0.038、0.018、0.005,Si的刻蚀率分别约为0.043、0.051、0.043和0.023。各入射角度下,产物分子种类主要为F、SiF和SiF2。F和SiF产物量随入射角度增加而增加,而SiF2产量随入射角度增加而减少。在入射角度等于5°和30°时,SixFyCz是主要的含C产物;而在入射角度等于60°和75°时,CF是主要的含C产物。在入射角度等于5°和30°时,SiF2是主要的含Si产物;在入射角度等于60°和75°时,SiF是主要的含Si产物。刻蚀主要通过化学增强的物理溅射进行。

Angular Effects of SiF3+ Etching SiC Surfaces: MD Study

Molecular dynamics simulations were performed to investigate the angular effects of SiF3+ bombarding SiC surfaces at the incident energy of 150eV.The improved Tersoff-Brenner type potentials for the Si-C-F system was employed.The simulation results show that with the energetic SiF3+ ions impacting on the SiC surface they will dissociate.It is found that most dissociated products deposit on the surface.The rates of dissociation and deposition decrease with increasing incident angle.Accompanying with deposition of SiF3+ ions and etching of SiC,a steady-state reactive Si-F-C layer is formed.With increasing incident angle,the thickness of reaction layer decreases.The etch yield of Si atoms from SiC is higher than that of C atoms from SiC.This is in good agreement with experimental data.When the steady-state etching is reached,the etching ratios of C are ~0.026,~0.038,~0.018 and ~0.005 at 5°,30°,60° and 75°,respectively.The etching ratios of Si from SiC are ~0.043,~0.051,~0.043 and ~0.023 at 5°,30°,60° and 75°,respectively.In etching products,the F,SiF and SiF2 species are dominant at all incident angles.With increasing incident angles,the yields of F and SiF increase and the yield of SiF2 decreases.In Si-containing pro-ducts,SiF2 is dominant at 5°and 30°,while SiF is dominant at 60° and 75°.Most etch products are produced by chemical-enhanced physical sputtering.