低能离子束刻蚀单晶硅表面形貌与粗糙度的研究

Morphology and Roughness on Silicon Surface During Low Energy Ion Beam Erosion

研究了低能Ar+离子束对单晶硅表面的刻蚀效果.使用自制的冷阴极离子源,通过控制离子束的入射能量和刻蚀时间等因素,对单晶硅(100)表面进行刻蚀,采用原子力显微镜(AFM)和非接触式表面测量仪对刻蚀后硅片的表面形貌以及表面粗糙度(RMS)进行测量.实验结果表明:当离子束正入射、束流密度为20μA/cm2、刻蚀时间为30min、刻蚀距离为7cm时,入射能量从800eV增加到1 200eV的过程中,此时表面光滑起主要作用,表面粗糙度逐渐减小;继续增大入射能量到1 600eV时,表面粗糙度开始增大,当入射能量达到1 400eV时,通过AFM观察,硅片表面出现了自组织纳米点状结构,此时表面粗糙起主要作用;延长刻蚀时间同样可以看到粗糙度先减小后增加,延长刻蚀时间到90min,表面的粗糙度达到1.245nm,AFM观察表明,随着时间的增加,由于样片表面原子扩散影响,点状结构排列趋于均匀.

The effect of low energy ion beam erosion on silicon surface quality was studied. The silicon （100） surface was eroded, controlling the incident energy and erosion time of ion beam from the cool cathode ion source. The eroded surface morphology was observed with atomic force microscopy （AFM） and the surface roughness was measured with noncontact measurement instrument. The results showed as follows. The surface roughness decreased, surface smoothing appeared mainly, with the increasing of incident energy from 800 eV to 1 200 eV, while the parameters are the incident ion beam density of 20μA/cm2,erosion time of 30 rain,etching distance of 7 cm. The minimum surface roughness of 0. 341 nm was obtained when the incident energy reached 1 200 eV. Further increasing of the incident energy upto 1 600 eV, led to increase surface roughness. While the incident energy reached 1 400 eV, the selforganized nano-dots structure was observed on the surface of silicon by the AFM, the surface roughing appeared mainly. The surface roughness decreased first and then increased afterwards with the extension of erosion time. While extending the erosion time to 90 min,the surface roughness reached 1. 245 nm. It was observed that the point-like structures arranged uniformly with the time extended due to atomic diffusion on the surface.