Micron-Size and Submicron-Size Light-Emitting Porous Silicon Structures

Abstract

We have developed three classes of techniques to produce micron-size and submicron-size light emitting porous Si (LEPSi) patterns and to protect the rest of the wafer. In the 1st class, LEPSi lines down to 2 μm width have been made using a photoresist/silicon nitride trilayer mask, followed by anodization. PL mapping of the structures indicates that the protected regions have not been etched. Using electron beam lithography sub-0.5 micron porous Si lines have been generated. In the 2nd class, formation of porous Si is inhibited by amorphizing Si using ion implantation followed by anodization and annealing. The crystallinity and electrical properties of the implanted region have been fully characterized after annealing. Using focussed ion-beam implantation, LEPSi patterns of the order of 100 nm have been obtained. The 3rd class consists of enhancing the formation of porous Si by a low energy/low dose bombardment (ion-milling) with argon ions prior to anodization. Under appropriate conditions, we have observed a strong enhancement of the formation rate of LEPSi where bombardment took place, possibly due to the generation of a large number of defects on the wafer surface.