电化学腐蚀多孔硅表面形貌的结构特性

Surface Microstructure of Porous Silicon Prepared by Electrochemical Etching

多孔硅作为微电子机械系统中重要的热绝缘层和牺牲层材料,其表面形貌结构特性是影响多孔硅上薄膜器件性能的重要因素．为此,利用双槽电化学腐蚀方法制备了多孔硅薄膜,并通过原子力显微镜和场发射扫描电子显微镜对制备多孔硅的表面形貌和孔径大小分布进行了观察．结果发现:腐蚀初期,在硅表面会有大量的硅柱形成,硅柱的直径、高度、分布密度与电流密度成正比关系;硅柱在进一步腐蚀过程中会消失,多孔硅的表面粗糙度随着腐蚀的进行,先减小再增大,最后达到稳定值0．52nm;多孔硅孔径大小分布区间随腐蚀时间增加变窄．

The surface microstructure of porous silicon is important for the performance of components in microelectron mechanical systems （MEMS）. Porous silicon layers are prepared by electrochemical etching with different current density and time in double cell. Atomic force microscopy（AFM） and field emission scanning electron microscopy（FESEM） are used to investigate the morphologies of porous silicon. The results show that： in the initial stage, silicon poles are formed, its diameter, height and distribution are directly proportinal to the current density;silicon poles are dissolved in the etching process, and the roughness firstly reduces then increases, in the end, reaches an invariable value of 0.52 nm;the value range of pore diameter becomes smaller with etching time increasing.