A reliable and sufficiently dimensioned exhaust infrastructure is a fundamental prerequisite for the safe and stable operation of wet process equipment. Efficient extraction of highly corrosive chemi- cal vapors (e.g. HF, HNO3) is essential to maintain controlled process conditions, ensure personnel safety for operators and maintenance engineers, and prevent long-term degradation of equipment components caused by chemical exposure.

During chemical start-up of a compact wetbench used for silicon wet-etching, insufficient exhaust performance was observed particularly during the wafer transfer step from the etch tank to the rinse tank. As the wafers exit the chemical bath, highly corrosive and toxic NOx-containing vapors are generated due to the reaction between residual etchant on the wafer surfaces and ambient oxygen. The release rate increases sharply at the air–liquid interface, creating a transient emission peak that must be effectively removed by the local exhaust system to avoid fugitive emissions and process-area contamination.
With the exhaust system already operating at full capacity, no further optimization was possible within the existing setup. Exhaust volume flow was identified as the key factor for rapid removal of chemical vapors. A Levitronix® BFS high-performance fan was therefore installed and qualified, enabling the wet bench’s release for production.

To assess interactions between the tool, cleanroom, and exhaust infrastructure, the entire scenario was subsequently simulated using AP&S SimLAB. The resulting insights improved understanding of system behavior and have been applied to other customer projects facing insufficient exhaust capabilities.