Lecture
This lecture covers the process of etching, which involves removing select materials from the wafer surface using wet or dry etching techniques. Wet etching relies on chemical reactions with a liquid etchant, while dry etching exposes wafers to gaseous etchants in an RF-energized plasma. The lecture explains the definitions of etch rate and selectivity, the steps involved in wet etching, and provides examples of isotropic and anisotropic etching. It also discusses physical and chemical dry etching methods, including ion beam etching and reactive ion etching. The challenges and main issues related to etching, such as aspect ratio dependent etching and polymer residues, are highlighted, along with solutions to overcome them.