Lecture
This lecture covers the fundamentals of dry etching in a gas plasma, including the directionality of etching, etching anisotropy, and the selection of dry etching processes. It explains how chemically reactive fluorine radicals are produced in a plasma to etch materials like silicon in an isotropic way. The lecture also discusses the use of different gases like Ar, CF4, and C4F8 for etching or passivating films. Additionally, it explores methods to increase etching anisotropy by sidewall protection and provides simple rules for choosing dry etchants based on factors like the fluorine-to-carbon ratio, substrate bias, and material being etched.