HIGH-ASPECT-RATIO SUBMICRON SILICON PILLARS FABRICATED BY PHOTOASSISTED ELECTROCHEMICAL ETCHING AND OXIDATION

A technique for fabricating submicron free-standing silicon pillars ha s been developed. The silicon pillars have a high packing density, and aspect ratios over 50:1 can easily be achieved. Photoassisted electro chemical etching in hydrofluoric acid is used to etch deep macropores in n-type silicon wafers which have been patterned by standard photoli thography. The regular macropores can be used for fabricating photonic band-gap structures. The bulk silicon remaining between the close-pac ked macropores is oxidized, Free-standing pillars are then formed by s ubsequently wet etching the silicon dioxide. The pillars are the initi al structures for forming quantum wires using further oxidation and et ch steps. (C) 1995 American Institute of Physics.