Micro-patterned porous silicon using proton beam writing

Abstract

A high-energy beam of hydrogen or helium ions focused to a small spot in a nuclear microprobe selectively damages a silicon lattice. This damage acts as an electrical barrier during subsequent formation of porous silicon by electrochemical etching of p-type wafers, so the un-irradiated regions are preferentially anodized. This process has opened up new research directions for the fabrication of a variety of high-aspect ratio, multi-level microstructures in silicon, such as gratings, photonic lattices and waveguides. The same process enables local modifications and control of the properties of the porous silicon, leading to new luminescent micro-structures in which both the spatial location and the wavelength and intensity of emission can be carefully controlled. The reflectivity and transmission of Bragg reflectors and microcavities fabricated in porous silicon can also be controlled using this same process and examples are given of each of these applications. © 2006 American Institute of Physics.