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

Abstract

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