Fabrication of nanoporous silicon nitride and silicon oxide films of controlled size and porosity for combined electrochemical and waveguide measurements

摘要

We demonstrate a method for controlled etching of vertical nano-sized pores over macroscopic areas. The method employs particle lithography to defme a pattern, for which the density can be varied in a wide range and the size of the pores can be varied independently. The particle pattern is transferred into a chrome mask on the substrate. We show how a thin nano-patterned mask is sufficient to etch sub-100 nm pores in dielectric materials at an aspect ratio of 20:1. This creates possibilities to reach optimal design parameters for porous waveguides for increased sensitivity and simultaneous electrochemical measurements. The feasibility of these applications is also demonstrated by applying the process to making functional plasmon-coupled waveguides with buried electrochemical electrodes.