Application of BOE and KOH+IPA for fabrication of smooth nanopore membrane surface for artificial kidney

This paper reports square silicon nanopore filtration membrane fabrication on <100>-oriented silicon substrate by employing potassium hydroxide (KOH) + isopropyl alcohol (IPA) wet etching. The aim of the study is to get a smooth membrane surface as the nanopore patterning base. A constant heated temperature of 80 °C employing double boil technique is used in both buffer oxide etching (BOE) and KOH etching steps to shorten time taken and get a better surface roughness. 10 minutes quick exposed nitride layer removal is achieved using the constant high temperature setting, while an add-on of 10 % IPA in KOH etchant aids in producing a uniform and smooth etched surface. A smooth surface roughness is required in patterning uniform filtration nanopores later on, and applied as a filtration membrane in artificial kidney.