Contamination issues in gas delivery for semiconductor processing

The contamination contribution from two functionally similar gas delivery systems supplying a process tool is quantified in this investigation. The conventional gas delivery system consists of single-melt stainless steel tubing (~20 Ra), elastomer components, and the ultraclean gas delivery system consists of double-melt stainless steel (~5 Ra), all metal components. Moisture, oxygen, and hydrocarbon impurities desorbing from the wetted surfaces of the gas delivery system are analyzed using an atmospheric pressure ionization mass spectrometer (APIMS). Particle contamination from components in the gas delivery system is characterized with a condensation nucleus counter (CNC) using static and dynamic testing. Corrosion-induced particulate occurring in the heat-affected-zone (HAZ) near welded portions in tubing is also studied. The moisture contribution of the conventional gas delivery system is a factor of six greater than that from the ultraclean gas delivery system and the oxygen contamination is a factor of three greater. The particle shedding (0.01 μm) in the static mode from the conventional manifold is 20 times greater than that from the ultraclean manifold. The HAZ of the conventional weldment shows aggressive corrosion-induced particulate and loss of the electropolished surface compared to the HAZ of the ultraclean weldment. The effect of the choice of material, components and manufacturing techniques is correlated to the extent of contamination contributed by the gas delivery system