通过聚焦离子束(focused ion beam, FIB) 轰击处理制备得到一种新的微纳级多孔硅结构, 并通过实验实现可控化. 在图形化过程中, FIB 轰击处的周围区域内多孔硅的电化学腐蚀被抑制, 出现了抑制区, 称为屏蔽区域. 屏蔽区域的形成主要是由FIB 轰击过程中硅粒子的二次碰撞所引起的. 屏蔽区域的宽度在一定范围内与FIB 的轰击电压、硅衬底的阻值成正相关. 报道了一种圆形多孔硅结构: 圆环上多孔硅密集分布, 而环内完全没有孔结构, 圆外围的屏蔽区域依然存在, 使得该圆形结构得以从周围环境中独立出来. 这种内部完全屏蔽的圆结构的直径最大可达10 μm.
A porous silicon (PSi) process for realizing controllable micro-to-nano scale features after focused ion beam (FIB) treatment is reported. An area, in which electrochemical etching is suppressed, therefore termed a shielding area, exists around the patterns treated by FIB. The area is formed due to a secondary knocked-on effect in the FIB process. The size of the shielding area is positively related to the energy used in FIB and resistivity of the silicon substrate. The shielding area on PSi has a width of 14 μm. The circular feature of PSi with a diameter as large as 10 μm is reported here for the first time. Inside the area no pores appear, while outside the shielding area remains.
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