Anisotropic etching of inverted pyramids in the sub-100 nm region

We have investigated the generation of inverted pyramids in the sub-100 nm region. A process based on e-beam lithography and anisotropic etching in aqueous KOH was developed which allows the generation of sub-100 nm pyramidal etch pits in a reproducible manner. Inverted pyramids as small as 75 nm with a period of 130 nm were produced. AFM-measurements have shown that such etch pits possess a very sharp tip curvature radius which was typically below 5 nm. In order to demonstrate that these structures can be further processed, the pyramidal etch pits were filled with metal and the supporting silicon was finally removed.