What types of etching are used in conventional chip fabrication technologies such as TSMC 0.18, dry or wet?
Plasma etching is a technology that enables narrow linewidths and high aspect ratios. It has completely replaced wet etching for feature patterning in modern ICs and it is mandatory in polysilicon surface micromechanics. It has also been applied to structures and applications that are not at all possible with wet etching. For instance, plasma etching without resist mask is essential for planarization and spacer formation.