Optimization of O₂ Plasma After Silicon Etch Process to Prevent Br-Induced Equipment Corrosion and Pattern Abnormality

Although hydrogen bromide (HBr) is an effective silicon etchant for patterning, it also generates SiBrx as a contaminant that causes equipment corrosion in the presence of moisture. We can apply O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> plasma post-etch treatment (PET) to remove this, while it also comes with the risk of triggering abnormal etch profile. As balancing this trade-off relationship by optimizing settings of O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> PET is essential, our research revealed the behaviors of Br and O on wafers exposed to various O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> plasma conditions, leading to the determination of optimal O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> PET settings with 2.5 to 5 percent of oxygen gas composition.