ABSTRACT
Within an integrated circuit manufacturing process, there are several wet chemical etching or stripping operations that use a single chemical immersion bath. Examples of single chemical immersion process operations include: photoresist develop, silicon dioxide etch, using dilute hydrofluoric acid (HF) or buffered oxide etch, photoresist strip, using a hot sulfuric acid/hydrogen peroxide mixture (piranha), and silicon nitride etch, using hot phosphoric acid. The most apparent feature of the chemical immersion bath is that many wafers are processed through the bath before fresh chemical is substituted for used chemical. The last step of a chemical immersion process is the wafer-drying operation. A centrifugal spin dryer system is most commonly used. Spin dryers are commonly recognized as an unpredictable source of particulate contamination. Common sources of particles in the nitrogen stream are: gas solenoid or diaphragm valves, rotating drive mechanisms, and gas entry manifolds and injectors.
