Effect of isopropyl alcohol (IPA) on etching rate and surface roughness of silicon etched in KOH solution

This paper studies the etching process of <;100> silicon wafers in Potassium Hydroxide (KOH) solution by patterning the silicon nitride with a square frame. The mutual relationship of the etching rate and temperature variation has been analysed. Particular additives like isopropyl alcohol can be added to the KOH solution to improve the smoothness of the surface plane. This smooth surface is necessary to produce pores on the silicon membrane. The addition of 10% IPA is proven to improve the surface roughness and increase the etching rate. This is verified by inspecting the substrate under AFM and optical microscopy. The micro pipes produced after an etching process were also reduced using the IPA.